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  Subjects -> MANUFACTURING AND TECHNOLOGY (Total: 279 journals)
    - CERAMICS, GLASS AND POTTERY (25 journals)
    - MACHINERY (32 journals)
    - MANUFACTURING AND TECHNOLOGY (171 journals)
    - METROLOGY AND STANDARDIZATION (3 journals)
    - PACKAGING (15 journals)
    - PAINTS AND PROTECTIVE COATINGS (5 journals)
    - PLASTICS (27 journals)
    - RUBBER (1 journals)

MACHINERY (32 journals)

Acta Mechanica Solida Sinica     Full-text available via subscription   (Followers: 9)
Advanced Energy Materials     Hybrid Journal   (Followers: 17)
Applied Mechanics Reviews     Full-text available via subscription   (Followers: 24)
BER : Consumer Goods Industries Survey     Full-text available via subscription  
BER : Intermediate Goods Industries Survey     Full-text available via subscription   (Followers: 1)
BER : Manufacturing Survey : Full Survey     Full-text available via subscription   (Followers: 2)
CORROSION     Full-text available via subscription   (Followers: 3)
Electric Power Components and Systems     Hybrid Journal   (Followers: 8)
Engenharia Agrícola     Open Access  
High Speed Machining     Open Access   (Followers: 1)
High Temperature Materials and Processes     Hybrid Journal   (Followers: 5)
International Journal of Machine Tools and Manufacture     Hybrid Journal   (Followers: 5)
International Journal of Machining and Machinability of Materials     Hybrid Journal   (Followers: 5)
International Journal of Manufacturing Technology and Management     Hybrid Journal   (Followers: 7)
International Journal of Precision Technology     Hybrid Journal  
International Journal of Rapid Manufacturing     Hybrid Journal   (Followers: 3)
International Journal of Rotating Machinery     Open Access   (Followers: 2)
Journal of Machinery Manufacture and Reliability     Hybrid Journal   (Followers: 1)
Journal of Machinery Manufacturing and Automation     Open Access   (Followers: 2)
Journal of Mechanics     Hybrid Journal   (Followers: 17)
Journal of Strain Analysis for Engineering Design     Hybrid Journal   (Followers: 5)
Journal of Terramechanics     Hybrid Journal   (Followers: 1)
Machine Design     Partially Free   (Followers: 13)
Machines     Open Access   (Followers: 2)
Materials     Open Access   (Followers: 5)
Mechanics Based Design of Structures and Machines: An International Journal     Hybrid Journal   (Followers: 3)
Micromachines     Open Access   (Followers: 3)
Practical Machinery Management for Process Plants     Full-text available via subscription  
Pump Industry Analyst     Full-text available via subscription  
Russian Engineering Research     Hybrid Journal  
Sensor Review     Hybrid Journal   (Followers: 1)
Surface Engineering and Applied Electrochemistry     Hybrid Journal   (Followers: 5)
Journal Cover   International Journal of Machine Tools and Manufacture
  [SJR: 3.363]   [H-I: 81]   [5 followers]  Follow
    
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 0890-6955
   Published by Elsevier Homepage  [2812 journals]
  • IFC - Editorial board
    • Abstract: Publication date: September 2015
      Source:International Journal of Machine Tools and Manufacture, Volume 96




      PubDate: 2015-07-28T20:54:46Z
       
  • A smooth curve evolution approach to the feedrate planning on five-axis
           toolpath with geometric and kinematic constraints
    • Abstract: Publication date: Available online 20 July 2015
      Source:International Journal of Machine Tools and Manufacture
      Author(s): Sun Yuwen, Zho Yang, Bao Yurong, Guo Dongming
      Feedrate planning with geometric and kinematic constraints is crucial for sculptured surface machining. Due to the non-linear relationship between the Cartesian space and the joint space, the feedrate planning method for a given five-axis toolpath is very limited compared with that in three-axis machining. To achieve the exact control of the chord error and the kinematic characteristics of cutter and machine tool, this paper presents a new feedrate planning method for five-axis parametric path using a smooth curve evolution strategy. The constraints in feedrate planning are first classified as two types of neighbor-independent (NI) constraints and neighbor-dependent (ND) constraints. Then for constraint violated region, the detailed formulas of determining the update feedrates of violated sampling points are given using a decoupled manner. As a result, NI and ND constraints are satisfied respectively with one step and multi-step smooth curve evolution technique, which can smoothly deform the target feedrate profile to the desired update positions. Simulations and experiments are performed on the given tool path to validate the effectiveness of the proposed feed planning method. The results show that the proposed method is robust and effective in the exact control of constraints in the feedrate planning on complex five-axis toolpath.


      PubDate: 2015-07-28T20:54:46Z
       
  • Investigation into effect of thermal expansion on thermally induced error
           of ball screw feed drive system of precision machine tools
    • Abstract: Publication date: October 2015
      Source:International Journal of Machine Tools and Manufacture, Volume 97
      Author(s): Hu Shi, Chi Ma, Jun Yang, Liang Zhao, Xuesong Mei, Guofang Gong
      In order to investigate the effect of thermal expansion on the ball screw feed drive system of a precision boring machine tool, theoretical modeling of and experimental study on thermally induced error along with heat generation characteristics are focused in this paper. A series of thermal experiments are conducted on the machine tool to measure and collect the thermodynamic data with the feed drive system operating at different speeds. Based on the heat generation and transfer analysis of ball screw system, thermal expansion of screw shaft in the axial direction is modeled mathematically. Relationships between the thermal error and axial elongation are established to characterize the thermal error distribution considering the thermal expansion coefficient as a temperature-variant parameter. It turns out that the thermal error varies with different working positions through the ball screw length and working time nonlinearly, and there definitely exists certain transform from the thermal expansion to the thermal error obtained by measurement. In addition, regression analysis is employed to carry out the theoretical modeling of thermal error with the temperature data of the critical heat generation points. The relations between temperature rise and thermal error are formulated directly while taking the thermal expansion as an implicit variable. Experiments under a different condition are preformed and the proposed methods for thermal error modeling prove to be effective and accurate enough to be used in the machining process as well.
      Graphical abstract image

      PubDate: 2015-07-28T20:54:46Z
       
  • Study on the effects of changes in temperature-sensitive points on thermal
           error compensation model for CNC machine tool
    • Abstract: Publication date: October 2015
      Source:International Journal of Machine Tools and Manufacture, Volume 97
      Author(s): Enming Miao, Yi Liu, Hui Liu, Zenghan Gao, Wei Li
      In thermal error compensation technology on computer numerical control (CNC) machine tool, selecting appropriate and stable temperature-sensitive points for modeling and compensation, is crucial for improving the accuracy of machine. In this paper, the temperature-sensitive points are changeable is proved by analyzing batches of experiment data of air cutting experiments on Leaderway-V450 machine, so it changes the degree of multi-collinearity among temperature variables, causes a serious impact on linearization and forecasting accuracy of the model, and can’t guarantee the model’s robustness. Based on the above analysis, a modeling method of principal component regression (PCR) algorithm is proposed, which can eliminate the influence of multi-collinearity among temperature variables. On this basis, according to the characteristic of PCR algorithm, traverse optimization method for selecting the optimum temperature measuring points is put forward as well. And both of two methods are given practice tests through triaxial thermal error experiments of actual machine. And the results show, PCR model significantly reduces the effects of changes in temperature-sensitive points on model’s accuracy; what’s more, the model has good forecasting accuracy and robustness by using PCR model combines with traverse optimization method. So that makes real-time compensation for thermal error on CNC machine more applied engineering.


      PubDate: 2015-07-28T20:54:46Z
       
  • Friction compensation controller for load varying machine tool feed drive
    • Abstract: Publication date: September 2015
      Source:International Journal of Machine Tools and Manufacture, Volume 96
      Author(s): Wonkyun Lee , Chan-Young Lee , Young Hun Jeong , Byung-Kwon Min
      The load applied to a machine tool feed drive changes during the machining process as material is removed. This load change alters the Coulomb friction of the feed drive. Because Coulomb friction accounts for a large part of the total friction the friction compensation control accuracy of the feed drives is limited if this nonlinear change in the applied load is not considered. This paper presents a new friction compensation method that estimates the machine tool load in real time and considers its effect on friction characteristics. A friction observer based on a Kalman filter with load estimation is proposed for friction compensation control considering the applied load change. A specially designed feed drive testbed that enables the applied load to be modified easily was constructed for experimental verification. Control performance and friction estimation accuracy are demonstrated experimentally using the testbed.


      PubDate: 2015-07-14T03:48:28Z
       
  • JianguoLinProf.Fundamentals of Materials Modelling for Metals Processing
           Technologies2015Imperial College Press
    • Abstract: Publication date: September 2015
      Source:International Journal of Machine Tools and Manufacture, Volume 96
      Author(s): Paulo A.F. Martins



      PubDate: 2015-07-14T03:48:28Z
       
  • Modeling dynamic stability in high-speed micromilling of
           Ti–6Al–4V via velocity and chip load dependent cutting
           coefficients
    • Abstract: Publication date: September 2015
      Source:International Journal of Machine Tools and Manufacture, Volume 96
      Author(s): Kundan K. Singh , V. Kartik , Ramesh Singh
      An increase in the demand for miniaturized components has resulted in the development of mechanical micromachining processes, such as micromilling. However, scaling down the process for micromilling operations require micro-tools, whose stiffness values are orders of magnitude lower than the conventional tools. The limited stiffness of the micro-end mills is a big impediment in machining difficult-to-cut materials, such as hardened steels and Ti-alloys. To address this issue, the cutting forces and hence the chip loads need to be reduced by using very high spindle rotational speeds. However, at lower chip loads ploughing may occur instead of cutting resulting in cutting force variation and high spindle speeds can excite higher order modes. Consequently, high spindle speeds and low chip loads in a tool with limited stiffness can lead to chatter induced dynamic instability which deteriorates the part quality, surface finish and tool life. Hence, identification of stable cutting parameters is necessary to avoid the chatter in high speed micromilling. Since the dynamic stability depends on the speed and the chip load (feed/flute), mechanistic force model with a constant cutting coefficient will yield inaccurate results. In this paper, the mechanistic force model based on velocity and chip load dependent cutting coefficient has been incorporated into the analytical stability model to predict the cutting forces and the stability lobe diagrams for high-speed micromilling of Ti6Al4V. The force predictions from the mechanistic model using velocity and chip load dependent cutting coefficient are in better agreement with experimentally measured forces as compared to constant cutting coefficients. Up to a spindle speed of 70,000rpm, the maximum prediction errors in stability boundary for a 500µm diameter end-mill using constant and velocity–chip load dependent cutting coefficients are ~33% and ~11%, respectively.


      PubDate: 2015-07-14T03:48:28Z
       
  • Local toolpath smoothing for five-axis machine tools
    • Abstract: Publication date: September 2015
      Source:International Journal of Machine Tools and Manufacture, Volume 96
      Author(s): Sneha Tulsyan , Yusuf Altintas
      When five axis CNC machine tools follow series linear toolpath segments, the drives experience velocity, acceleration and jerk discontinuities at the block transition points. The discontinuities result in fluctuations on machine tool motions which lead to poor surface quality. This paper proposes to insert quintic and septic micro-splines for the tool tip and tool-orientation, respectively, at the adjacent linear toolpath segments. Optimal control points are calculated for position and orientation splines to achieve C 3 continuity at the junctions while respecting user-defined tolerance limits. The geometrically smoothed corners are traveled at a smoothly varying feed with cubic acceleration trajectory profile. The proposed method is experimentally demonstrated to show improvements in motion smoothness and tracking accuracy in five-axis machining of free-form surfaces found in dies, molds and aerospace parts.


      PubDate: 2015-07-14T03:48:28Z
       
  • A realtime curvature-smooth interpolation scheme and motion planning for
           CNC machining of short line segments
    • Abstract: Publication date: September 2015
      Source:International Journal of Machine Tools and Manufacture, Volume 96
      Author(s): Wei Fan , Chen-Han Lee , Ji-Hong Chen
      G01 codes generated by CAM (Computer Aided Manufacturing) system are the most common form of tool path in CNC (Computer Numerical Control) machining. For the piecewise linear path, tangential and curvature discontinuities bring about large fluctuation of feedrate and acceleration, which produces vibration of machine tool. In recent studies, the methods for G 2 (curvature-continuous) tool-path smoothing and jerk-limiting feedrate scheduling were developed. However there still exist the deficiencies when these methods are employed in CNC machining. It is difficult to simultaneously ensure that the tool path is chord-error-constrained and G01-point-interpolated in real time. In addition, heavy computational load hinders realtime processing in CNC system. Recently the scholars experimentally found the potential of G 3 (curvature-smooth) trajectory and jerk-continuous motion in reducing the vibration of machinery. This work proposes a realtime tool-path smoothing algorithm, generating G 3 interpolative tool path composed by mixed linear and quartic Bezier segments. The purpose of the smoothing scheme is the simultaneous considerations of G 3 continuity, confined chord error, G01 points interpolated, and realtime performance. And the tool path generated is optimized in curvature variation energy (CVE) and analytical curvature extrema is available. To reduce the vibration, a high-efficient algorithm of jerk-continuous (JC) feedrate scheduling for G 3 tool path is provided. Finally, a realtime tool-path processing scheme is developed, including G 3 interpolation and motion planning functions. As shown in the simulation, the contour error, curvature of tool path, feedrate fluctuation and machining time are reduced compared with G 2 transition scheme. The experiment on a machine tool is conducted to demonstrate the advantages of the proposed algorithm in vibration reduction and surface quality, compared with G 2 transition scheme.


      PubDate: 2015-07-14T03:48:28Z
       
  • Wear patterns and wear mechanisms of cutting tools used during the
           manufacturing of chopped carbon fiber
    • Abstract: Publication date: October 2015
      Source:International Journal of Machine Tools and Manufacture, Volume 97
      Author(s): Zhongfu Shen , Longsheng Lu , Jiawei Sun , Feng Yang , Yong Tang , Yingxi Xie
      Chopping carbon fiber is an efficient way to manufacture short carbon fiber reinforced plastic (SCFRP). Drastic wear of cutting tools during this process has been observed because of the highly abrasive nature of carbon fiber. Wear patterns and wear mechanisms need to be investigated to reduce tool wear and prolong tool life. This paper presents the formation and transition of wear patterns during the chopping process. The chopped rate is less than 95% after 21k cuts; thus, tool specimens and data are collected from the initial 21k cuts. Overall, the wear forms a crescent shape along the tool edge at one cutting position. This wear pattern is due to an uneven wear volume caused by the uneven distribution of filaments in the fibers, which forms an oval profile of the chopped carbon fiber. The oval profile results in more crescent shaped wear, which causes a more uneven filaments distribution, leading to a high wear rate. Conical structures at the ends of the chopped carbon fiber and micro scratches on the tool edge are observed. Thus, the abrasive wear mechanism during chopping is verified. The wear pattern on the tool profile is a combination of cutting edge rounding (CER) and rake face wear. Two wear stages divided by 8k cuts are introduced: the CER wear stage (before) and rake face wear stage (after). In the CER wear stage, the wear rate is basically stable at 32μm/2k cuts and the wear pattern is an increasing CER up to 20μm. The rake angle is approximately stable at 79°. In the rake face wear stage, the wear rate begins to increase and the wear pattern transitions from the CER wear to massive rake face wear in which the CER decreases and leans towards the flank face and the rake angle rapidly decreases. The CER decreases to 4μm, and the rake angle decreases to 14° at the end. The wear pattern includes a groove that appears on the tool rake face in this stage, which is similar to crater wear on the rake face of a traditional turning tool because of the low hardness of the tool interior. Moreover, analytical models based on 3-body abrasive wear theory are developed to explain these wear patterns and wear mechanisms.


      PubDate: 2015-07-14T03:48:28Z
       
  • An accurate, efficient envelope approach to modeling the geometric
           deviation of the machined surface for a specific five-axis CNC machine
           tool
    • Abstract: Publication date: August 2015
      Source:International Journal of Machine Tools and Manufacture, Volume 95
      Author(s): Yuansheng Zhou , Zezhong C. Chen , Xujing Yang
      Geometric deviation, defined as the difference between the nominal surface and the simulation model of the machined surface, is the fundamental concern of five-axis tool path planning. Since the machined surface is part of the cutter envelope surface generated by the cutter motion, it is necessary to calculate the envelope surface in order to obtain the geometric deviation. In the stage of tool path planning, current approaches calculate the cutter envelope surface by using the cutter motion along the given tool path. However, the cutter motion of practical machining on a specific five-axis CNC machine tool is different from the given tool path. Moreover, the computation is very challenging when the accurate cutter motion of practical machining is applied to calculate the envelope surface. To overcome these two problems, a geometric envelope approach with two major distinctions is proposed in this paper. First, the envelope surface of the cutter undergoing a general motion is efficiently obtained as a closed-form vector expression. Second, the accurate cutter motion, which is determined by machine kinematic and interpolation scheme in practical machining, can be easily applied to calculate the accurate envelope surface. With the envelope surface, the geometric deviation is calculated to estimate the overcut or undercut in five-axis milling. An example is given to demonstrate the validity of the proposed method.


      PubDate: 2015-07-14T03:48:28Z
       
  • A position independent geometric errors identification and correction
           method for five-axis serial machines based on screw theory
    • Abstract: Publication date: August 2015
      Source:International Journal of Machine Tools and Manufacture, Volume 95
      Author(s): Jixiang Yang , J.R.R. Mayer , Yusuf Altintas
      Position independent geometric errors (PIGEs), which are caused by imperfect assembly of five-axis machine tools, need to be identified and compensated to improve the accuracy of machined parts. This paper presents the identification and correction of serial five-axis machine tools based on screw theory. The proposed identification model is based on a generalized Jacobian function for a variety of five-axis machine configurations as opposed to the models based on homogeneous transformation matrices (HTMs). The screw theory allows a global description of rigid body motion without constructing the local frames on each drive module as required by the HTMs method. An explicit inverse kinematics model is proposed to compensate the geometric errors directly as opposed to the existing approximate linearized or iterative methods. The proposed identification and correction of PIGEs methods are verified through simulations and experiments with ball-bar tests on a five-axis machine tool.


      PubDate: 2015-07-14T03:48:28Z
       
  • Stochastic modelling of abrasive waterjet footprints using finite element
           analysis
    • Abstract: Publication date: August 2015
      Source:International Journal of Machine Tools and Manufacture, Volume 95
      Author(s): P. Lozano Torrubia , D.A. Axinte , J. Billingham
      The proposal of erosion models to predict the jet footprint during abrasive waterjet machining is a key element for the development of this technology, but it is very challenging because of the inherent fluctuations of the process. This issue becomes critical when the size of the cutting systems is reduced, since the relative size of these deviations increases. The present paper considers for the first time a modelling framework capable of predicting the average shape of AWJM footprints and, of great novelty, the variability along the trench, combining finite element analysis and Monte Carlo methods, and verifying the model using different feed speeds and tilt angles. For that purpose, the relevance of each random parameter, such as shape (sharpness), size and relative orientation of the abrasive particles, has been investigated through parametric studies on these variables. Multiple particle simulations with randomly generated input were performed to determine the effect of operating parameters in the overall variability of the jet footprint. The process was simulated using Abaqus 6.14 as multiple garnet particles hitting a target of Ti–6Al–4V at very high velocity, eroding the target by plastic deformation and material removal. The model shows successfully the influence of single particle parameters, such as the shape, on the surface variability. The results for the footprint variability show that stochastic methods are suitable to model these fluctuations, and it is also shown that this approach yields accurate estimates of the average profile after multiple jet passes with error less than 5%.


      PubDate: 2015-07-14T03:48:28Z
       
  • Optimal process parameters for parallel turning operations on shared
           cutting surfaces
    • Abstract: Publication date: August 2015
      Source:International Journal of Machine Tools and Manufacture, Volume 95
      Author(s): C. Brecher , A. Epple , S. Neus , M. Fey
      To enhance productivity in industrial settings, turning machines are increasingly being used with multiple turrets. This machine configuration enables parallel machining at different or at the same cutting surface using independent tools. However, there is a dynamic interaction between the cutting processes due to the waviness induced on the shared cutting surface as well as due to the dynamic coupling through the machine structure. This dynamic interaction can lead to a significant reduction of the chip removal rate compared to two conventional processes. To utilize the productivity advantage of parallel turning processes, an examination of the process-machine-interaction considering the dynamic coupling of the cutting processes is required. Hence, this paper discusses parametrization for stable processing of parallel turning operations. Therefore, time and frequency domain-based simulation models are developed and matched with experimental cutting tests. Additionally, the influence of the radial angle between the tools is investigated. This angle influences the dead time between two successive cuts for parallel turning processes on the same cutting surface. The dead time in turn directly affects the process stability limit. Thus, with the help of the developed simulation models, an optimal process parametrization for parallel turning operations can be determined.


      PubDate: 2015-07-14T03:48:28Z
       
  • A review on spindle thermal error compensation in machine tools
    • Abstract: Publication date: August 2015
      Source:International Journal of Machine Tools and Manufacture, Volume 95
      Author(s): Yang Li , Wanhua Zhao , Shuhuai Lan , Jun Ni , Wenwu Wu , Bingheng Lu
      Thermal error caused by the thermal deformation is one of the most significant factors influencing the accuracy of the machine tool. Among all the heat sources which lead to the thermal distortions, the spindle is the main one. This paper presents an overview of the research about the compensation of the spindle thermal error. Thermal error compensation is considered as a more convenient, effective and cost-efficient way to reduce the thermal error compared with other thermal error control and reduction methods. Based on the analytical calculation, numerical analysis and experimental tests of the spindle thermal error, the thermal error models are established and then applied for implementing the thermal error compensation. Different kinds of methods adopted in testing, modeling and compensating are listed and discussed. In addition, because the thermal key points are vital to the temperature testing, thermal error modeling, and even influence the effectiveness of compensation, various approaches of selecting thermal key points are introduced as well. This paper aims to give a basic introduction of the whole process of the spindle thermal error compensation and presents a summary of methods applied on different topics of it.


      PubDate: 2015-07-14T03:48:28Z
       
  • On the mechanism and mechanics of material removal in ultrasonic machining
    • Abstract: Publication date: September 2015
      Source:International Journal of Machine Tools and Manufacture, Volume 96
      Author(s): Sanjay Agarwal
      Precision abrasive machining processes such as ultrasonic machining are commonly employed to machine glasses, single crystals and ceramic materials for various industrial applications. Until now, precision machining of hard and brittle materials are poorly investigated from the fundamental and applied point of views. Taking into account the major technological importance of this subject to the production of functional and structural components used in high performance systems, it is often desired to estimate the machining rate for productivity while maintaining the desired surface integrity. The success of this approach, however, requires not only the fundamental understanding of the material removal on the microstructural scale but also the relationship between the machining characteristics and material removal rate in ultrasonic machining. In this study, the ultrasonic machining of glass was investigated with respect to mechanism of material removal and material removal rate (with basic machining parameters) with a mild steel tool using boron carbide abrasive in water as slurry. The analysis indicates that the material removal was primarily due to the micro-brittle fracture caused on the surface of the workpiece. For micro-brittle fracture mode, the relationship for the material removal rate, considering direct impact of abrasive grains on the workpiece, based on a simple fracture mechanics analysis has been established. The effect of machining conditions on material removal rate has been discussed. This research provides valuable insights into the material removal mechanism and the dependence of material removal rate on machining conditions and mechanical properties of workpiece material in ultrasonic machining.


      PubDate: 2015-07-14T03:48:28Z
       
  • IFC - Editorial board
    • Abstract: Publication date: August 2015
      Source:International Journal of Machine Tools and Manufacture, Volume 95




      PubDate: 2015-07-14T03:48:28Z
       
  • On-machine measurement of location errors on five-axis machine tools by
           machining tests and a laser displacement sensor
    • Abstract: Publication date: August 2015
      Source:International Journal of Machine Tools and Manufacture, Volume 95
      Author(s): Zhouxiang Jiang , Bao Song , Xiangdong Zhou , Xiaoqi Tang , Shiqi Zheng
      This paper proposes an on-machine measurement (OMM) of all location errors on five-axis machine tools. Five machining patterns are successively performed on a cubic workpiece. The basic idea is to use a set of large rotations of rotary axes to prolong the moving distance of linear axes when squareness errors of linear axes are identified. Then, a set of small rotations of rotary axes are used to decouple the squareness errors of linear and rotary axes. Based on this, the long and deep slots in previous machining tests are improved to be a set of short and shallow ones. These miniaturized slots reduce the material removal and minimize the influence of cutting force and thermal deformation on the measuring results. Then the cutting tool is substituted by a laser displacement sensor (LDS) to measure the mismatch between the finished surfaces of the corresponding slots. All the measured surfaces are located on the bottom of the slots to fit the LDS characteristic of one dimensional measurement. Three gestures of the rotary table and tilting head are used to implement the single-setup OMM and the influence of location errors on the measuring results is compensated. Validation of the identified values is also provided by a set of simple tests using different measuring instruments. The efficiency and accuracy of location errors measurement method on five-axis machine tools are improved.


      PubDate: 2015-07-14T03:48:28Z
       
  • Design of trigonometric velocity scheduling algorithm based on
           pre-interpolation and look-ahead interpolation
    • Abstract: Publication date: September 2015
      Source:International Journal of Machine Tools and Manufacture, Volume 96
      Author(s): Yunsen Wang , Dongsheng Yang , Rongli Gai , Shuaihua Wang , Shujie Sun
      To generate continuous velocity, acceleration and jerk curves of parametric interpolation in high-speed and high-accuracy machining, this paper presents a trigonometric velocity scheduling algorithm based on two-time look-ahead interpolation (pre-interpolation and look-ahead interpolation). The algorithm consists of three modules: pre-interpolation, look-ahead interpolation and real-time interpolation. The pre-interpolation module aims to explore and record the information of the path to be machined. The look-ahead interpolation module firstly calculates the velocity scheduling functions according to the data recorded by pre-interpolation, and then tests and adjusts the feedrate scheduling schemes constantly. The real-time interpolation module adapts the method of beforehand deceleration or delaying acceleration according to the signals received from pre-interpolation and look-ahead interpolation to guarantee the processing accuracy. Simulation and experimental tests demonstrate the availability, effectiveness and advantages of the trigonometric velocity scheduling algorithm. And the proposed trigonometric velocity scheduling algorithm based on pre-interpolation and look-ahead interpolation could realize smooth velocity, acceleration and jerk control with restricted chord error and implement high-quality CNC processing.


      PubDate: 2015-07-14T03:48:28Z
       
  • Influence of machining errors on form errors of microlens arrays in
           ultra-precision turning
    • Abstract: Publication date: September 2015
      Source:International Journal of Machine Tools and Manufacture, Volume 96
      Author(s): Xianlei Liu , Xiaodong Zhang , Fengzhou Fang , Zhen Zeng , Huimin Gao , Xiaotang Hu
      Ultra-precision turning is widely used in machining microlens arrays. Machining errors have an effect on the form accuracy of the whole microlens array, but they have not been fully studied, especially the effect on the optical performance. A machining error model of microlens arrays is built to analyse the coordinate distortions and form errors easily based on multi-body system theory and a homogeneous transformation matrix. The simulative and experimental results verified the influence of three major machining errors (tool alignment errors (∆x, ∆y), tool nose radius error (∆R) and squareness error (∆θ) from the proposed approach. Through the simulation and experimental approach, this study describes the distribution of the form errors as axisymmetric; the form error of the centre part of the row and column cells is minimal, whereas that of the diagonal cells is the maximum. The optical performance of the cells has the same correlation as the form errors. Based on the above study, a horizontal off-centring machining method is proposed to achieve high form accuracy and uniform optical performance.


      PubDate: 2015-07-14T03:48:28Z
       
  • Mechanistic modeling of five-axis machining with a general end mill
           considering cutter runout
    • Abstract: Publication date: September 2015
      Source:International Journal of Machine Tools and Manufacture, Volume 96
      Author(s): Zhou-Long Li , Jin-Bo Niu , Xin-Zhi Wang , Li-Min Zhu
      The accurate and fast prediction of cutting forces in five-axis milling of free-form surfaces remains a challenge due to difficulties in determining the varying cutter-workpiece engagement (CWE) boundaries and the instantaneous uncut chip thickness (IUCT) along the tool path. This paper proposes an approach to predict the cutting forces in five-axis milling process with a general end mill considering the cutter runout effect that is inevitable in the practical machining operations. Based on the analytical model of cutting edge combined with runout parameters, the expression of the rotary surface formed by each cutting edge undergoing general spatial motion is firstly derived. Then by extracting the feasible contact arc along the tool axis, a new arc-surface intersection method is developed to determine the CWE boundaries fast and precisely. Next, the circular tooth trajectory (CTT) model is developed for the calculation of the IUCT with a slight sacrifice of accuracy. In comparison with the true IUCT calculated by the trochoidal tooth trajectory model, the approximation error introduced by the circular assumption is negligible while the computational efficiency improves a lot. Finally, combining with the calibrated cutting coefficients and runout parameters, comprehensive formulation of the cutting force system is set up. Simulations and experimental validations of a five-axis flank milling process show that the novel CTT model possesses obvious advantages in computing efficiency and accuracy over the existing approaches. Rough machining of a turbo impeller is further carried out to test the practicability and effectiveness of the proposed mechanistic model.


      PubDate: 2015-07-14T03:48:28Z
       
  • Amorphization and C segregation based surface generation of
           Reaction-Bonded SiC/Si composites under micro-grinding
    • Abstract: Publication date: August 2015
      Source:International Journal of Machine Tools and Manufacture, Volume 95
      Author(s): Quanli Zhang , Suet To , Qingliang Zhao , Bing Guo
      Micro-grinding of Reaction-Bonded SiC/Si composites (RB–SiC/Si) were conducted to investigate the surface generation mechanism. The results showed that amorphization occurred for both SiC and Si phases, and C segregation appeared on SiC surface and at the interface of SiC and Si. The surface generation mechanism changed from micro-breaking to smoother surface, but accompanied by formation of many micro-pits at phase boundaries with the decrease of feed rate. It was identified that the material removal mode was closely related to amorphization and C segregation (i.e. amorphization would promote ductile material removal while C segregation would aggravate surface fracture and increase the number of micro-pits). Furthermore, it was found that the distribution of micro-pits corresponded with the random and stochastic properties of diamond grits, and the formation of micro-pits during machining process determined the surface roughness. To explain the mechanism of micro-pits formation, a simple interaction model between diamond grit and workpiece was proposed.


      PubDate: 2015-07-14T03:48:28Z
       
  • Stiffness analysis and experiment of a novel 5-DoF parallel kinematic
           machine considering gravitational effects
    • Abstract: Publication date: August 2015
      Source:International Journal of Machine Tools and Manufacture, Volume 95
      Author(s): Binbin Lian , Tao Sun , Yimin Song , Yan Jin , Mark Price
      In order to carry out high-precision machining of aerospace structural components with large size, thin wall and complex surface, this paper proposes a novel parallel kinematic machine (PKM) and formulates its semi-analytical theoretical stiffness model considering gravitational effects that is verified by stiffness experiments. From the viewpoint of topology structure, the novel PKM consists of two substructures in terms of the redundant and overconstrained parallel mechanisms that are connected by two interlinked revolute joints. The theoretical stiffness model of the novel PKM is established based upon the virtual work principle and deformation superposition principle after mapping the stiffness models of substructures from joint space to operated space by Jacobian matrices and considering the deformation contributions of interlinked revolute joints to two substructures. Meanwhile, the component gravities are treated as external payloads exerting on the end reference point of the novel PKM resorting to static equivalence principle. This approach is proved by comparing the theoretical stiffness values with experimental stiffness values in the same configurations, which also indicates equivalent gravity can be employed to describe the actual distributed gravities in an acceptable accuracy manner. Finally, on the basis of the verified theoretical stiffness model, the stiffness distributions of the novel PKM are illustrated and the contributions of component gravities to the stiffness of the novel PKM are discussed.


      PubDate: 2015-07-14T03:48:28Z
       
  • Laser polishing of selective laser melted components
    • Abstract: Publication date: August 2015
      Source:International Journal of Machine Tools and Manufacture, Volume 95
      Author(s): S. Marimuthu , A. Triantaphyllou , M. Antar , D. Wimpenny , H. Morton , M. Beard
      The shape complexities of aerospace components are continuously increasing, which encourages industries to refine their manufacturing processes. Among such processes, the selective laser melting (SLM) process is becoming an economical and energy efficient alternative to conventional manufacturing processes. However, dependant on the component shape, the high surface roughness observed with SLM parts can affect the surface integrity and geometric tolerances of the manufactured components. To account for this, laser polishing of SLM components is emerging as a viable process to achieve high-quality surfaces. This report details an investigation carried out to understand the basic fundamentals of continuous wave laser polishing of SLM samples. A numerical model, based on a computational fluid dynamic formulation, was used to assist the understanding of melt pool dynamics, which significantly controls the final surface roughness. The investigation identified the input thermal energy as the key parameter that significantly affect the melt pool convection, and essentially controls the surface quality. Minimum meltpool velocity is essential to achieve wider laser polished track width with good surface finish. Experimental results showed a reduction of surface roughness from 10.2μm to 2.4μm after laser polishing with optimised parameters. Strategies to control the surface topology during laser polishing of SLM components are discussed.


      PubDate: 2015-07-14T03:48:28Z
       
  • Analytical modeling and experimental validation of micro end-milling
           
    • Abstract: Publication date: Available online 6 July 2015
      Source:International Journal of Machine Tools and Manufacture
      Author(s): L. Zhou , F.Y. Peng , R. Yan , P.F. Yao , C.C. Yang , B. li
      This paper presents a novel micro end-milling cutting forces prediction methodology including the edge radius, material strengthening, varying sliding friction coefficient and run-out together. A new iterative algorithm is proposed to evaluate the effective rake angle, shear angle and friction angle, which takes into account the effects of edge radius as well as varying sliding friction coefficient. A modified Johnson-Cook constitutive model is introduced to estimate the shear flow stress. This model considers not only the strain-hardening, strain-rate and temperature but also the material strengthening. Furthermore, a generalized algorithm is presented to calculate uncut chip thickness considering run-out. The cutting forces model is calibrated and validated by NAK80 steel, and the relevant micro slot end-milling experiments are carried out on a 3-axis ultra-precision micro-milling machine. The comparison of the predicted and measured cutting forces shows that the proposed model can provide very accurate predicted results. Finally, the effects of material strengthening, edge radius and cutting speed on the cutting forces are investigated by the proposed model and some conclusions are given as follows: (1) the material strengthening behavior has significant effect on micro end-milling process at the micron level. (2) Cutting forces predicted increase with the increase of edge radius. (3) Considering varying sliding friction coefficient can enhance the sensitivity of the predicted cutting forces to cutting speed.


      PubDate: 2015-07-14T03:48:28Z
       
  • IFC - Editorial board
    • Abstract: Publication date: July 2015
      Source:International Journal of Machine Tools and Manufacture, Volume 94




      PubDate: 2015-07-14T03:48:28Z
       
  • Feasibility study of in-process compensation of deformations in flexible
           milling
    • Abstract: Publication date: July 2015
      Source:International Journal of Machine Tools and Manufacture, Volume 94
      Author(s): Eduardo Diez , Hilde Perez , Juan Marquez , Antonio Vizan
      During the machining of thin-walled parts, deformation can occur resulting in dimensional errors. These dimensional errors cause a variation on cutting forces. From the actual measured cutting forces and the estimated forces resultant from rigid machining, it is possible to determine the value of this deformation. Based on this, an on-line system for compensating workpiece errors, has been developed. The system is based on correcting the relative position of the tool-workpiece during machining by means of a piezoelectric actuator. The objective is achieved in real time to compensate for the part deformations from the measurement of the cutting forces, without the programming of the tool path trajectories in the machine tool being affected.


      PubDate: 2015-07-14T03:48:28Z
       
  • Theoretical and experimental investigation on the novel
           end-fly-cutting-servo diamond machining of hierarchical
           micro-nanostructures
    • Abstract: Publication date: July 2015
      Source:International Journal of Machine Tools and Manufacture, Volume 94
      Author(s): Zhiwei Zhu , Suet To , Shaojian Zhang
      By combining the concepts of fast/slow tool servo and fly cutting, a novel end-fly-cutting-servo (EFCS) system with four-axis motions is proposed for deterministic generation of hierarchical micro-nanostructures, which are conventionally difficult for both mechanical and non-mechanical methods to achieve. In the EFCS system, an intricately shaped primary surface is generated by material removal, while the desired secondary nanostructure is simultaneously constructed using residual tool marks by actively controlling the tool loci. The optimal toolpath determination strategy, as well as surface generation algorithm for the EFCS system, has been developed with consideration of geometries and installation poses of the diamond tool. Numerical simulation of surface generation is conducted to demonstrate the effectiveness of the novel machining method and features of the obtained hierarchical structures. A nanostructured micro-aspheric array and a nanostructured F-theta freeform surface are successfully fabricated in experiments. This research provides a very promising technique for the generation of hierarchical micro-nanostructures to realize performance integration of artificial components.
      Graphical abstract image

      PubDate: 2015-07-14T03:48:28Z
       
  • Study on mechanics and key technologies of laser nondestructive
           mirror-separation for KDP crystal
    • Abstract: Publication date: July 2015
      Source:International Journal of Machine Tools and Manufacture, Volume 94
      Author(s): Leimin Deng , Huan Yang , Xiaoyan Zeng , Baoye Wu , Peng Liu , Xizhao Wang , Jun Duan
      KDP crystal is an important electro-optic material in various laser systems. At present, the greatest difficulty is the cutting and polishing of large-scale crystals. In this study, a laser nondestructive mirror-separation technology (LNMS) for KDP crystal has been developed for the first time by skillfully adopting femtosecond laser pretreating and fiber laser separating. The separating efficiency of LNMS is at least 200 times faster than that of traditional mechanical cutting, and a nondestructive mirror-separated crystal sidewall with surface roughness (S a ) of 4.7nm (P−V) and 2.1nm (RMS), flatness of 5.433μm and an angular precision about 0.06° could be obtained using the LNMS method. The effects of laser separating parameters, including laser power, laser moving speed and internal stress release on separating accuracy and quality, were investigated and optimized; meanwhile its principle was expounded as well as its mechanism was discussed. The experimental and analyzed results show that the LNMS technology may also have a prospect in the analysis of residual stress distribution inside KDP crystal. A numerical simulation on the thermal stress in the LNMS separating process of KDP crystal was developed to analyze the separating mechanism, which is in good agreement with the theoretical analysis and experimental results.
      Graphical abstract image

      PubDate: 2015-07-14T03:48:28Z
       
  • Numerical modeling and experimental measurement of MQL impingement over an
           insert in a milling tool with inner channels
    • Abstract: Publication date: July 2015
      Source:International Journal of Machine Tools and Manufacture, Volume 94
      Author(s): Arnaud Duchosal , Sana Werda , Roger Serra , René Leroy , Hédi Hamdi
      This paper compares experimental and numerical simulations of liquid film formation for different rotating velocities of a milling tool. The numerical model used was based on an unsteady Reynolds–Average Navier–Stokes (RANS) formulation and multiphase Lagrangian model for liquid film formation by the droplet impingement model on a solid surface. The details of spray–wall interaction are presented and the model was used to simulate the liquid film formation in the Micro-Quantity Lubrication (MQL) coolant process for different milling tool velocities. The shape and the size of the liquid film obtained by the calculation and the experiments were compared to improve understanding of the MQL cooling process. Overall, good agreement was observed between the numerical and the experimental measurements of liquid film size from an estimated numerical film thickness border. This study provided greater understanding of oil mist behavior. The impingement analyses predicted better lubrication when highly oriented channels and high inlet pressure were used, especially in High Speed Machining.
      Graphical abstract image

      PubDate: 2015-07-14T03:48:28Z
       
  • Investigation of the effects of spindle unbalance induced error motion on
           machining accuracy in ultra-precision diamond turning
    • Abstract: Publication date: July 2015
      Source:International Journal of Machine Tools and Manufacture, Volume 94
      Author(s): P. Huang , W.B. Lee , C.Y. Chan
      In ultra-precision machining, error motions of the aerostatic bearing spindle (ABS) have significant effects on the machining accuracy. Spindle unbalance is a critical factor attributing to error motions of the ABS. Much work currently has been focused on the measurement of error motions and spindle balancing. However, the unbalance induced spindle error motion (UISEM) and the corresponding effects on machining accuracy are not well understood. In this paper, a dynamics model of the ABS was established to characterize the UISEM and its dynamic behavior with consideration of the unbalance effects. A series of groove turning experiments were especially designed to investigate the UISEM. Good agreement between theoretical and experimental results was achieved, demonstrating the low frequency enveloping phenomenon of the error motions of the ABS, identified as the unique superposition effects of two motion components at high frequency in the spindle vibration. In addition, the experimental result reveals that the relative distance between the rotational axis of the ABS and the tool tip varies with respect to the different spindle speeds, significantly degrading the machining accuracy.


      PubDate: 2015-07-14T03:48:28Z
       
  • CFRP drilling: Fundamental study of local feed force and consequences on
           hole exit damage.
    • Abstract: Publication date: July 2015
      Source:International Journal of Machine Tools and Manufacture, Volume 94
      Author(s): Cédric Bonnet , Gérard Poulachon , Joël Rech , Yannick Girard , Jean Philippe Costes
      Carbon Fiber-Reinforced by Plastic (CFRP) is now commonly used in the aircraft industry. The main challenge is to manufacture this difficult-to-cut work material, considering its quality criteria and economical aspects. Drilling is the main machining operation required for the assembly of the aircraft structure. In this paper, results are presented and discussed regarding exit delamination studied at a local scale. Because of the anisotropic properties of CFRP, the fiber cutting modes change with the composite sequence combined with the drill revolution parameters. The local feed forces generated by the cutting edge on the hole bottom may be correlated with delaminating aspects. A posttreatment method is proposed to analyze precisely these feed force and cutting torque distributions. Appropriate ply sequences are identified in order to limit the mechanical load concentration and the risk of delamination or uncut fibers


      PubDate: 2015-07-14T03:48:28Z
       
  • Integrated post-processor for 5-axis machine tools with geometric errors
           compensation
    • Abstract: Publication date: July 2015
      Source:International Journal of Machine Tools and Manufacture, Volume 94
      Author(s): Nuodi Huang , Yongqiao Jin , Qingzhen Bi , Yuhan Wang
      Geometric errors of 5-axis machine tools introduce great deviation in real workpiece manufacture and on-machine measurement like touch-trigger probe measurement. Compensation of those errors by toolpath modification is an effective and distinguished method considering the machine calibration costs and productivity. Development of kinematic transformation model is involved in this paper to clarify the negative influences caused by those errors at first. The deviation of the designed toolpath and the real implemented toolpath in workpiece coordinate system is calculated by this model. An iterative compensation algorithm is then developed through NC code modification. The differential relationship between the NC code and the corresponding real toolpath can be expressed by Jacobi matrix. The optimal linear approximation of the compensated NC code is calculated by utilizing the Newton method. Iteratively applying this approximation progress until the deviation between the nominal and real toolpath satisfies the given tolerance. The variations of the geometric errors at different positions are also taken into account. To this end, the nominal toolpath and the geometric errors of the specific 5-axis machine tool are considered as the input. The new compensated NC code is generated as the output. The methodology can be directly utilized as the post-processor. Experimental results demonstrate the sensibility and effectiveness of the compensation method established in this study.


      PubDate: 2015-07-14T03:48:28Z
       
  • Prediction and identification of rotary axes error of non-orthogonal
           five-axis machine tool
    • Abstract: Publication date: July 2015
      Source:International Journal of Machine Tools and Manufacture, Volume 94
      Author(s): Dongju Chen , Lihua Dong , Yanhua Bian , Jinwei Fan
      This paper proposes an efficient and automated scheme to predict and identify the position and motion errors of rotary axes on a non-orthogonal five-axis machining centre using the double ball bar (DBB) system. Based on the Denavit-Hartenberg theory, a motion deviations model for the tilting rotary axis B and rotary C of a non-orthogonal five-axis NC machine tool is established, which considers tilting rotary axis B and rotary C static deviations and dynamic deviations that total 24. After analysing the mathematical expression of the motion deviations model, the QC20 double ball bar (DBB) from the Renishaw Company is used to measure and identify the motion errors of rotary axes B and C, and a measurement scheme is designed. With the measured results, the 24 geometric deviations of rotary axes B and C can be identified intuitively and efficiently. This method provides a reference for the error identification of the non-orthogonal five-axis NC machine tool.


      PubDate: 2015-07-14T03:48:28Z
       
  • Shear-thickening polishing method
    • Abstract: Publication date: July 2015
      Source:International Journal of Machine Tools and Manufacture, Volume 94
      Author(s): Min Li , Binghai Lyu , Julong Yuan , Chenchen Dong , Weitao Dai
      A shear-thickening polishing (STP) method utilizing the shear thickening mechanism of non-Newtonian power-law fluid based slurry is proposed for curved surface polishing. The STP principle and micro-material removal action are analyzed. The high-performance STP slurry with the shear-thickening rheological behaviors has been prepared. To achieve the material removal mechanism of STP process, based on the Preston formula, fluid dynamics and shear thickening mechanism, the material removal rate (MRR) model is established and the difference of MRR between theoretical and experimental results is 6.12%. The experimental and theoretical tests of STP process are conducted to investigate the influences of polishing velocity, abrasive concentration and grain size on MRR and surface roughness. Compared with Newtonian fluid slurry, STP slurry can achieve much higher MRR and better surface quality due to shear-thickening effect. MRR of Cr12Mo1V1 (die steel) is up to 13.69μm/h, and surface roughness is reduced from R a 105.95nm to R a 5.1nm within 0.5h of processing. This indicates that STP is a promising processing method for precision finishing or polishing.


      PubDate: 2015-07-14T03:48:28Z
       
  • Dynamic electromechanical coupling resulting from the air-gap fluctuation
           of the linear motor in machine tools
    • Abstract: Publication date: July 2015
      Source:International Journal of Machine Tools and Manufacture, Volume 94
      Author(s): Xiaojun Yang , Dun Lu , Jun Zhang , Wanhua Zhao
      This paper investigates a dynamic electromechanical coupling resulting from the air-gap fluctuation of the linear motor in machine tools. The modes of the mechanical vibration are analyzed firstly in the linear motor feed system. Then the influence of mechanical vibration on the air-gap fluctuation is researched. Based on the Maxwell's equation and energy method, the analytical expression of the motor thrust is established considering the air-gap fluctuation. Then we discuss the effects of air-gap fluctuation on the motor thrust. At last, the dynamic electromechanical coupling caused by the air-gap fluctuation is theoretically analyzed and verified by experiments. The results show that the mechanical vibration can affect the characteristics of the motor thrust conversely causing the fluctuation of the motor air-gap. The air-gap fluctuation can produce new thrust harmonics. These new thrust harmonics excite mechanical system again, and then the electromechanical coupling loop is formed, leading to a worse dynamic precision of the feed system. In addition, the couplings will aggravate with the increase of velocity and load.


      PubDate: 2015-07-14T03:48:28Z
       
  • Augmented Taylor's expansion method for B-spline curve interpolation for
           CNC machine tools
    • Abstract: Publication date: July 2015
      Source:International Journal of Machine Tools and Manufacture, Volume 94
      Author(s): Mo Chen , Wan-Sheng Zhao , Xue-Cheng Xi
      In computer numerical control (CNC) systems, parametric curves can be used instead of a large amount of linear blocks to describe tool paths for freeform surface or curve machining. However, existing parametric curve interpolation methods may cause large feed fluctuations or even a failure of the machining process near the sharp corners of a parametric curve. Therefore, a parametric curve interpolation method with an error correction and failure prevention scheme is required. In this paper, the augmented Taylor's expansion (ATE) method for computing B-spline curve parameters is proposed. A group of calibrators consisting of the knots and the arc lengths between adjacent knots are pre-computed before the interpolation starts. The parameter is computed based on Heun's method in a prediction–correction manner, and the accumulated errors caused by the cut-off errors of Taylor's expansion are eliminated by the calibrators at the knots. To cope with the extreme cases that usually occur near the sharp corners of a curve, a linear parametric interpolation between the previous parameter and its next calibrator is carried out when Heun's method fails to obtain a parameter in the domain. Simulation and experimental results show that, when the arc length increments are kept small enough near the sharp corners, the ATE method attains high accuracy and robust computation. The proposed method is also applicable to the NURBS curves.


      PubDate: 2015-07-14T03:48:28Z
       
  • Analysis on critical Conditions of sidewall wrinkling for hydroforming of
           thin-walled tee-joint
    • Abstract: Publication date: Available online 23 June 2015
      Source:International Journal of Machine Tools and Manufacture
      Author(s): Gang Liu , Junyang Peng , Shijian Yuan , Bugang Teng , Kai Li
      Based on the sidewall wrinkling phenomena in hydroforming of thin-walled Tee-joint, an analytical model for tube wrinkling under double side constraints was proposed to calculate the critical wrinkling stress. The effects of stress ratio, diameter-to-thickness ratio and tube material properties on critical condition of sidewall wrinkling were investigated. It is found that the middle of the main tube side wall is the most dangerous position for wrinkling within hydroforming of thin-walled Tee-joint. At a certain internal pressure, the critical wrinkling stress increases with increasing of ratio of hoop stress to axial stress and material strength coefficients, but decreases with increasing of work-hardening exponent and ratio of diameter to thickness. Through the analytical model combining FEM simulation, the critical wrinkling loading path according to the relation between axial feeding and internal pressure was obtained. Experimental results validates that wrinkle can be avoided if the pressure is above the critical wrinkling loading path, otherwise, wrinkle occurs. It is also verified that the analytical model of critical wrinkling stress is reasonable for the thin-walled Tee-joint hydroforming process.


      PubDate: 2015-07-14T03:48:28Z
       
  • Ultrasonic measurement of contact stiffness and pressure distribution on
           spindle-holder taper interfaces
    • Abstract: Publication date: Available online 20 June 2015
      Source:International Journal of Machine Tools and Manufacture
      Author(s): Fei Du , Baotong Li , Jie Zhang , Quan Min Zhu , Jun Hong
      The measurement of contact characteristics of the spindle-holder taper interface is critical for the evaluation of the performance of a machine tool spindle system. In this study, an ultrasonic method was proposed to measure the contact stiffness and pressure distribution on the taper interface. The taper interface was scanned by an ultrasound transducer, and the nominal contact area was directly estimated from the resulting ultrasonic reflection coefficient. The normal stiffness distribution was determined by the spring-damper model from the reflection coefficient. On this basis, the distributed and global radial stiffness of the taper interface was calculated by the presented theoretical formulas. Meanwhile, a calibration curve was established to convert the ultrasonic reflection to contact pressure. Based on the proposed ultrasonic method, the effects of angle fitting error and clamping force were studied. The results show that the contact area, contact pressure and contact stiffness increase with the clamping force. As the angle fitting error increases, the contact area decreases, while the pressure and stiffness at the big end of the taper interface become much larger than these at the small end. In the meantime, the global radial stiffness increases first and then decreases. This result suggests that a larger angle fit error within the permissible range is better for the global radial stiffness. Moreover, the measured results confirm that a taper joint with an angle fit error larger than +36” is not suitable for practical application, because the contact pressure at the small end is too small. To compare with the ultrasonic method, the geometrical shape profiles of the contact surfaces were constructed, and FE models were also established for contact pressure predictions. The comparison shows that the ultrasound results are consistent with the surface shape profiles and the numerical predictions. Besides, one of the taper interfaces was measured three times with the same clamping force, and the results indicate that the repeatability of the proposed method is good.


      PubDate: 2015-07-14T03:48:28Z
       
  • Drilling Delamination and Thermal Damage of Carbon Nanotube / Carbon Fiber
           Reinforced Epoxy Composites Processed by Microwave Curing
    • Abstract: Publication date: Available online 20 June 2015
      Source:International Journal of Machine Tools and Manufacture
      Author(s): Nanya Li , Yingguang Li , Jing Zhou , Yongxi He , Xiaozhong Hao
      The drilling-induced delamination and thermal damage of carbon fiber reinforced epoxy composite materials are serious problems especially for high value components of the aviation industry. To suppress the delamination and drilling ablation, an innovative approach was employed in this study. The multiwalled carbon nanotubes (MWCNTs) were introduced to the matrix resin to improve the interlaminar strength and thermal conductivity. The as-prepared composite was processed by microwave curing to enhance the interface strength between carbon fiber and the carbon nanotubes modified matrix. During the drilling processes, optical fiber Bragg grating sensors were utilized to precisely measure the drilling temperature. Experimental results indicated that the interlaminar fracture toughness was increased by more than 66% compared to that of the traditional thermal cured samples without MWCNTs. And the delamination factor was decreased by 16% according to the computerized tomography scanning results. The maximum drilling temperature of the MWCNTs reinforced composite was below the glass transition temperature of the matrix resin and declined by 23 oC compared to traditional composites. With this novel method of carbon nanotube modification and microwave curing, we provide the capability of reducing the drilling delamination and thermal damage of carbon fiber composites simultaneously, and explored the possibility of manufacturing and machining integration.


      PubDate: 2015-07-14T03:48:28Z
       
  • IFC - Editorial board
    • Abstract: Publication date: June 2015
      Source:International Journal of Machine Tools and Manufacture, Volume 93




      PubDate: 2015-07-14T03:48:28Z
       
  • Evaluation of measurement uncertainty in H-drive stage during high
           acceleration based on Monte Carlo method
    • Abstract: Publication date: June 2015
      Source:International Journal of Machine Tools and Manufacture, Volume 93
      Author(s): Yongmeng Liu , Maoqiang Yuan , Jieru Cao , Jiwen Cui , Jiubin Tan
      This paper presents an integrated error propagation analysis method to estimate the measurement uncertainty using Monte Carlo method in order to analyze the measurement accuracy of an H-drive stage with air bearing during high acceleration subjected to the influence of a variety of errors, including straightness errors, thermal errors, deformation errors and air bearing gap change errors caused by acceleration force. Firstly, the integrated error propagation model of an H-drive stage is built combined with the effects of the various error sources based on the multi-body system and instrument precision theory. Then these errors are identified by experiments and finite element analysis and the influence of each error in six degrees of freedom displacement is obtained. Finally, the displacement measurement uncertainty of the stage in the reference coordinate system is evaluated by Monte Carlo method, within 95% probability, the displacement measurement results and the expanded uncertainty in x and y directions are calculated x=(165.000±0.064)mm and y=(195.000±0.054)mm respectively. The proposed method can be used in the error budget of precise machine design and applied in error compensation to improve the measurement and control accuracy of precise machine workpiece stage.


      PubDate: 2015-07-14T03:48:28Z
       
  • Precise contour following for biaxial systems via an A-type iterative
           learning cross-coupled control algorithm
    • Abstract: Publication date: June 2015
      Source:International Journal of Machine Tools and Manufacture, Volume 93
      Author(s): Jianhua Wu , Chao Liu , Zhenhua Xiong , Han Ding
      This paper proposes an A-type iterative learning cross-coupled control (CCC) algorithm for biaxial systems. An algebraic equation based contour error model is used as the CCC input. This model has the advantage that it is zero if and only if the real value vanishes. The iterative learning CCC is designed to make its input converge to zero. Hence, it is expected to that the contour error will converge to zero as well. After analyzing the control algorithm convergence condition in the frequency domain, the proposed method is implemented on a motion stage. Experimental results show that the algorithm perfectly follows contours as the cycles approach infinity regardless of whether tracking errors are small or large.


      PubDate: 2015-07-14T03:48:28Z
       
  • High-speed dry electrical discharge machining
    • Abstract: Publication date: June 2015
      Source:International Journal of Machine Tools and Manufacture, Volume 93
      Author(s): Yang Shen , Yonghong Liu , Yanzhen Zhang , Hang Dong , Wanyun Sun , Xiaolong Wang , Chao Zheng , Renjie Ji
      A novel high-speed dry electrical discharge machining (EDM) method was proposed in this study. Using this method, the material can be rapidly melted by extremely high discharge energy and flushed out of the discharge gap by high-pressure and high-speed air flow. The material removal rate (MRR) of dry EDM was significantly improved by the proposed method. The MRR of dry EDM is usually in tens mm3/min, whereas the MRR of the proposed method can be as high as 5162mm3/min, which improves the MRR by 2nd to 3rd order of magnitude. Investigation was conducted systemically. The influences of work piece polarity, discharge current, pulse duration time, gas pressure, and electrode rotation speed on machining performance were studied. The machining mechanism of this method was thoroughly analyzed. Moreover, the re-solidified layer, surface morphology, elementary composition, and phase of AISI 304 stainless steel for high-speed dry EDM were also investigated. Theoretical and technical foundations were laid for the industry application of dry EDM.


      PubDate: 2015-07-14T03:48:28Z
       
  • Thermally induced positioning error modelling and compensation based on
           thermal characteristic analysis
    • Abstract: Publication date: June 2015
      Source:International Journal of Machine Tools and Manufacture, Volume 93
      Author(s): Wenlong Feng , Zihan Li , Qunying Gu , Jianguo Yang
      To decrease the thermally induced positioning error of machine tools, a novel approach for modelling and compensation is proposed in this study. The cause of this error is determined to be dynamic pitch error, and its manifestations are discussed in this study. The thermal expansion of a screw shaft under the influence of friction heat is analysed theoretically, and a mathematical model of the transient temperature of the screw with regard to time is developed. A temperature calculation method in the cases of cooling in the process of warming up and warming up after cooling is also introduced. To solve the problem of heat unevenly distributed of the entire screw shaft, the screw shaft is divided into several evenly distributed heat regions, and the established model is fit for each region. The synthetic model is established by superposition of all models of the regions. In addition, an external error compensation system is developed based on a function called external mechanical origin offset in Fanuc CNC systems. Six test pieces are machined to validate the accuracy of the model and the effectiveness of the error compensation system. The result indicates that the accuracy of the pieces is significantly improved compared with that obtained without error compensation. The synthetic model of the entire screw shaft is demonstrated to be an effective approach to improve the accuracy of machine tools.


      PubDate: 2015-07-14T03:48:28Z
       
  • Investigation of material deformation mechanism in double side incremental
           sheet forming
    • Abstract: Publication date: June 2015
      Source:International Journal of Machine Tools and Manufacture, Volume 93
      Author(s): B. Lu , Y. Fang , D.K. Xu , J. Chen , S. Ai , H. Long , H. Ou , J. Cao
      Double side incremental forming (DSIF) is an emerging technology in incremental sheet forming (ISF) in recent years. By employing two forming tools at each side of the sheet, the DSIF process can provide additional process flexibility, comparing to the conventional single point incremental forming (SPIF) process, therefore to produce complex geometries without the need of using a backing plate or supporting die. Although this process has been proposed for years, there is only limited research on this process and there are still many unanswered open questions about this process. Using a newly developed ISF machine, the DSIF process is investigated in this work. Focusing on the fundamental aspects of material deformation and fracture mechanism, this paper aims to improve the understanding of the DSIF process. Two key process parameters considered in this study include the supporting force and relative position between master and slave tools. The material deformation, the final thickness distribution as well as the formability under varying conditions of these two process variables are investigated. To obtain a better understanding from the experimental results, an analytical model has been developed to evaluate the stress state in the deformation zone. Using the developed model, an explicit relationship between the stress state and key process parameters can be established and a drop of stress triaxiality can be observed in the double contact zone, which explains the enhanced formability in the DSIF process. Based on the analytical and experimental investigation, the advancements and challenges of the DSIF process are discussed with a few conclusions drawn for future research.


      PubDate: 2015-07-14T03:48:28Z
       
  • Analysis of the transient backlash error in CNC machine tools with closed
           loops
    • Abstract: Publication date: June 2015
      Source:International Journal of Machine Tools and Manufacture, Volume 93
      Author(s): Shengyu Shi , Jing Lin , Xiufeng Wang , Xiaoqiang Xu
      Backlash is one of the most commonly encountered nonlinear phenomena in feed drives, which degrades the contouring accuracy of machine tools. The full-closed loop could suppress the adverse effects of backlash significantly. However, a transient backlash error (TBE) remains. Unfortunately, the mechanism of the TBE is completely different from that of the conventional backlash error. The purpose of this paper is to reveal the mechanism of the TBE. First, for the demonstration of the TBE, a general model is derived from an industrial feed drive with the closed loop control. Subsequently, the model is simplified further. Based on the simplified model, the mechanism is described and clarified in detail, and furthermore, the analytical formulations of TBEs are derived for the cases of straight line and circle, respectively. Finally, several simulations and experiments are given to validate the proposed models and formulations.


      PubDate: 2015-07-14T03:48:28Z
       
  • IFC - Editorial board
    • Abstract: Publication date: May 2015
      Source:International Journal of Machine Tools and Manufacture, Volume 92




      PubDate: 2015-07-14T03:48:28Z
       
  • Hyper-third order full-discretization methods in milling stability
           prediction
    • Abstract: Publication date: May 2015
      Source:International Journal of Machine Tools and Manufacture, Volume 92
      Author(s): C.G. Ozoegwu , S.N. Omenyi , S.M. Ofochebe
      Full-discretization methods beyond the third order is not yet explored except for this work in which the fourth and fifth order methods are presented. It is seen in earlier works that accuracy of milling stability analysis using the full-discretization method rises from the first order method to the second order method and continues to rise to the third order method. It is seen in this work that the rise in accuracy of the full-discretization method with order continues to the proposed fourth order method where it (accuracy) peaks before a decline to the proposed fifth order method.


      PubDate: 2015-07-14T03:48:28Z
       
  • Tube electrode high-speed electrochemical discharge drilling using
           low-conductivity salt solution
    • Abstract: Publication date: May 2015
      Source:International Journal of Machine Tools and Manufacture, Volume 92
      Author(s): Yan Zhang , Zhengyang Xu , Di Zhu , Jun Xing
      Film cooling holes are widely used in the aerospace industry, and their fabrication requires high machining speed and accuracy, as well as good surface quality. Tube electrode high-speed electrochemical discharge drilling (TSECDD) is a promising hybrid machining method for the fabrication of film cooling holes in difficult-to-machine superalloys. An electrochemical reaction can occur if a low-conductivity salt solution is used in the drilling. Materials can also be removed at a high speed using electrical discharge machining (EDM). Thus, TSECDD and electrochemical machining (ECM) can be combined into a unique machining process using a low-conductivity salt solution. This machining process achieves both a high machining speed and good surface finish. In this study, the material removal mechanism of TSECDD was studied using a low-conductivity salt solution, and comparisons with high-speed electrical discharge drilling were made. The performance of the process was investigated using salt solutions of various conductivities. The results show that there are different material removal mechanisms in the frontal gap and the lateral gap and that, in the latter, there is a transition from EDM to ECM. Experiments conducted using TSECDD confirm that the use of this process with a low-conductivity salt solution can improve the machining surface and machining efficiency achieved. The results also show that the use of a low-conductivity solution improves the material removal rate, the hole diameter, and the taper angle.


      PubDate: 2015-07-14T03:48:28Z
       
 
 
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