Showing papers in "International Journal of Machine Tools & Manufacture in 1995"
TL;DR: In this paper, an experimental study of orthogonal cutting mechanisms was conducted in the edge trimming of unidirectional Graphite/Epoxy composite with polycrystalline diamond tools, and the effects of tool geometry and operating conditions were evaluated from an analysis of chip formation, cutting force and machined surface topography.
Abstract: An experimental study of orthogonal cutting mechanisms was conducted in the edge trimming of unidirectional Graphite/Epoxy composite with polycrystalline diamond tools. The effects of tool geometry and operating conditions were evaluated from an analysis of chip formation, cutting force and machined surface topography. All aspects of material removal were found to be primarily dependent on the fibre orientation. Discontinuous chip formation was noted throughout this study, regardless of trimming parameters. Chip dimensions and force measurements depicted a change in chip formation with fibre orientation, and the presence of three distinct mechanisms in the edge trimming of fiber reinforced composite material. A combination of cutting, shearing and fracture along the fibre/matrix interface was observed.
335 citations
TL;DR: In this article, the Iosipescu shear test was used to evaluate the inplane shear strength of fiber angle test specimens and a model for predicting the cutting forces and the dependence of cutting direction on machinability requirements was presented.
Abstract: With the increasing use of fiber reinforced plastic (FRP) composites outside the defense, space and aerospace industries, namely, civilian industries, machining of these materials is assuming a significant role. Unit cost rather than solely performance at any cost will be the consideration for the implementation of FRP composites to consumer industries. The current knowledge of machining FRP composites, unfortunately, is inadequate for its optimum utilization in many applications. This paper presents some observations made on the orthogonal machining of unidirectional carbon fiber reinforced plastic (UD-CFRP) laminates with different fiber orientations. Iosipescu shear test was adopted to evaluate the inplane shear strength of varied fiber angle test specimens. A model for predicting the cutting forces and the dependence of cutting direction on machinability requirements is presented.
306 citations
TL;DR: In this article, a feed-forward neural network is used to associate the cutting parameters with the cutting performance and a simulated annealing (SA) algorithm is applied to the neural network for solving the optimal cutting parameters based on a performance index within the allowable working conditions.
Abstract: Owing to the complexity of wire electrical discharge machining (wire-EDM), it is very difficult to determine optimal cutting parameters for improving cutting performance. The paper utilizes a feedforward neural network to associate the cutting parameters with the cutting performance. A simulated annealing (SA) algorithm is then applied to the neural network for solving the optimal cutting parameters based on a performance index within the allowable working conditions. Experimental results have shown that the cutting performance of wire-EDM can be greatly enhanced using this new approach.
280 citations
TL;DR: In this paper, a model for peripheral milling of very flexible, cantilevered plates with slender end mills is presented, where the plate has varying structural properties in the axial and feed directions due to metal removal.
Abstract: Peripheral milling of very flexible, cantilevered plates with slender end mills is modeled. The plate has varying structural properties in the axial and feed directions due to metal removal. The cutter is modeled as a cantilevered continuous elastic beam with flexible clamping in the collet. The plate structural properties are updated using the finite element technique as the cutter and plate interact at changing contact zones along the feed direction. The analytical cutting force and surface generation model considers partial separation of tool and plate structures due to static displacements. The experimentally verified model predicts the cutting forces and dimensional surface error on the plate. The model identifies the required feed variation along the plate in order to keep the static form errors within the specified tolerance of the part. The model is developed to improve dimensional accuracy in peripheral milling of very flexible aerospace components.
207 citations
TL;DR: In this article, the shape and joint transformations for inaccurate links and joints using small angle approximations were used to find the total volumetric error in the workspace as a function of all the possible errors.
Abstract: The total volumetric error within the workspace of a machine tool is induced by the propagation of both scalar and position dependent geometrical errors, as well as time-variant thermal errors. This paper presents a compact volumetric error model which can be used as a basis for a practical compensation scheme. The broad objective is to increase the achievable accuracy of an industrial five-axis CNC machine tool. In place of using Denavit-Hartenberg (D-H) transformations, the method used here directly considers the shape and joint transformations for inaccurate links and joints using small angle approximations and then finds the total volumetric error in the workspace as a function of all the possible errors. The development of the model shows that angular deviations are independent of translational errors. However, the tool point deviations are dependent on both translational and rotational errors. The model has been used for the design and testing of a compensation strategy. The simulation studies indicate that CNC compensation for errors in X , Y and Z axes is possible. However, the capability of the CNC compensation for pitch, roll and yaw errors is dependent on the positioning of the rotary axes on the machine tool. This is shown by an example using the compensation scheme developed.
142 citations
TL;DR: In this paper, the results obtained are useful in describing the damage history and to help design drill geometries specifically conceived for composite machining, and qualitative agreement of the observed behaviour with the predictions of the model presented in the literature is assessed.
Abstract: In the drilling of reinforced plastics the quality of the cut surfaces is strongly dependent on the appropriate choice of drilling parameters. The aim of this work is to clarify the interaction mechanisms between the drilling tool and material. Drilling tests were carried out on glass-polyester composites using standard HSS tools; drilling was interrupted at preset depths to study damage development during drilling. The specimens, polished by a metallographic technique, were examined by optical microscopy to identify any damage. The results obtained are useful in describing the damage history and to help design drill geometries specifically conceived for composite machining. The qualitative agreement of the observed behaviour with the predictions of the model presented in the literature and some of their intrinsic limitations are assessed.
126 citations
TL;DR: In this article, a new approach to extend rotary ultrasonic machining to face milling of ceramics is proposed, which keeps all the material removal mechanisms of rotary UML machining.
Abstract: Among the various material removal processes applicable to ceramic materials, rotary ultrasonic machining has the potential for high material removal rate while maintaining low machining pressure and resulting in less surface damage. The limitation of rotary ultrasonic machining is that only circular holes or cavities can be machined due to the rotary motion of the tool. Attempts have been made by other researchers to extend rotary ultrasonic machining process to machining flat surfaces or milling slots. However, these extensions either changed the material removal mechanisms or had some severe drawbacks. One of the reasons for this might be an insufficient understanding of the material removal mechanisms involved. In this paper, a new approach to extend rotary ultrasonic machining to face milling of ceramics is proposed, which keeps all the material removal mechanisms of rotary ultrasonic machining. The development of the experimental apparatus and the design of the cutting tool are described. Preliminary experimental results are presented and discussed.
125 citations
TL;DR: In this article, a technique for multi-scale characterization of engineering surfaces by applying wavelet transform is introduced. But the technique is limited in characterizing multi-dimensional surface features relevant to manufacturing processes and functions.
Abstract: Conventional surface characterization techniques involving random process analysis are limited in characterizing multi-scale surface features relevant to manufacturing processes and functions. This paper introduces a novel technique for multi-scale characterization of engineering surfaces by applying wavelet transform. The main advantages of wavelet transform over other existing signal processing techniques are its space-frequency localization and multi-scale view of the components of a signal. Utilizing these properties of wavelet transform, we can effectively apply multi-channel filter banks to the surface data and link the manufacturing and functional aspects of a surface with its multi-scale features. Surfaces produced by typical manufacturing processes are analyzed using wavelet transform, and the usefulness of wavelet transform in the multi-scale analysis of engineering surfaces is demonstrated.
116 citations
TL;DR: In this article, the use of an active dynamic absorber to suppress machine tool chatter in a boring bar is studied, where the vibrations of the system are reduced by moving an absorber mass using an active device such as an piezoelectric actuator, to generate an inertial force that counteracts the disturbance acting on the main system.
Abstract: In this paper, the use of an active dynamic absorber to suppress machine tool chatter in a boring bar is studied. The vibrations of the system are reduced by moving an absorber mass using an active device such as an piezoelectric actuator, to generate an inertial force that counteracts the disturbance acting on the main system. An equivalent lumped mass model of a boring bar with active dynamic absorber is considered. A cutting process model that considers the dynamic variation of shear and friction angle, that causes self-excited chatter during the cutting process, is applied to the lumped mass model. The theory of regenerative chatter is also applied to the model. Stability boundaries have been calculated for maximum permissible width of cut as a function of cutting speed. A comparison of the boundaries for chatter-free cutting operation of a plain boring bar, a boring bar with passive tuned dynamic absorber and a boring bar with active dynamic absorber is provided in this paper. The comparison shows that a substantial increase in the maximum permissible width of cut for stable cutting operation, over a range of cutting speeds, is obtained for a boring bar equipped with an active dynamic absorber.
103 citations
TL;DR: In this paper, the impact of various parameters on the residual stress, surface roughness, and work hardening of workpieces machined by end-milling results from the cutting conditions and tool geometries.
Abstract: The surface quality-including residual stress, surface roughness, and work hardening—of workpieces machined by end-milling results from the cutting conditions and tool geometries. The parameters considered in the present work are the cutting speed, feed, depth of cut, tool nose radius and flank width. The analyses of the data and the building model are carried out using the Takushi method and the response surface methodology (RSM). Variance analyses and experimental examinations are conducted to find the prominent parameters and to determine the adequacy of the model. It is shown that the cutting speed, feed, tool nose radius, and flank width have significant effects on the residual stresses and there is an interaction between the cutting speed and the flank width; that the surface roughness is affected by the tool nose radius and feed; and that these parameters do not exert a significant influence on the work hardening. There is a good correlation between the experimental and the predicted results derived from the model.
98 citations
TL;DR: In this paper, a laser heating mechanism initiating the drilling process is examined, including conduction and convection effects and assuming a steady-state evaporation process, and the maximum temperature attained inside the material, nucleation, explosion process and drilling efficiency are predicted.
Abstract: A laser heating mechanism initiating the drilling process is examined. The study includes conduction and convection effects and assumes a steady-state evaporation process. This enables estimation of the limits of the Fourier theory in laser drilling applications. Using the model described in the analysis, maximum temperature attained inside the material, nucleation, explosion process and drilling efficiency are predicted. The results obtained from the present work for the vapor front velocity are compared to those obtained from previous experiments. In addition, a laser drilling experiment is carried out while monitoring the surface evaporation process. This enables correlation of the theoretical results with the experiments.
TL;DR: In this article, a tool failure detection was conducted in two steps by using Wavelet Transformations and Neural Networks (WT-NN) and adaptive resonance theory (ART2)-type self-learning neural networks.
Abstract: Detection of tool failure is very important in automated manufacturing. In this study, tool failure detection was conducted in two steps by using Wavelet Transformations and Neural Networks (WT-NN). In the first step, data were compressed by using wavelet transformations and unnecessary details were eliminated. In the second step, the estimated parameters of the wavelet transformations were classified by using Adaptive Resonance Theory (ART2)-type self-learning neural networks. Wavelet transformations represent transitionary data and complex patterns in a more compact form than time-series methods (frequency and time-domain) by using a family of the most suitable wave forms. Wavelet transformations can also be implemented on parallel processors and require less computations than Fast Fourier Transformation (FFT). The training of ART2-type neural networks is faster than backpropagation-type neural networks and ART2 is capable of updating its experience with the help of an operator while it is monitoring the sensory signals. The proposed approach was tested in over 171 cases and all the presented cases were accurately classified. The proposed system can be easily trained to inspect data during transition and/or any complex cutting conditions. The system will indicate failure instantaneously by creating a new category, thus alerting the operator.
TL;DR: In this article, a feed-forward neural network is used to model cutting force components and the volume of the displaced work material displaced by the tool flank is calculated using the equations of motion iteratively until a convergence criterion is satisfied.
Abstract: This paper presents a new mechanistic model to study the complex and highly nonlinear process damping force in chatter vibration. In the developed model, a feedforward neural network is used to model cutting force components. The process damping force due to the interface between the tool flank and machined surface is estimated through the calculation of the volume of the work material displaced by the tool flank. To properly calculate the volume of the displaced work material, the vibration of the tool relative to the workpiece is solved using the equations of motion iteratively until a convergence criterion is satisfied. The study has shown that the developed model is much better than previous models in the analysis of dynamic behaviors of the nonlinear process damping force in chatter vibration.
TL;DR: In this article, an on-line error compensation system for coordinate measuring machines (CMMs) is described, which is based on three laser optical Multi-Degree-of-Freedom Measurement Systems (MDFM systems), each for one axis of CMMs.
Abstract: An on-line error compensation system for coordinate measuring machines (CMMs) is described, which is based on three laser optical Multi-Degree-of-Freedom Measurement Systems (MDFM systems), each for one axis of CMMs. Twelve of the twenty-one error components associated with a CMM are measured on-line by these MDFM systems. The remaining error components are measured by off-line methods which use commercially available measurement systems, such as a laser interferometer. Two mathematical error models have been developed to synthesize the error components and to predict the errors at the probe stylus tip. One model corresponds to the conventional off-line error compensation and the other to the on-line error compensation. The errors predicted by these models are then subtracted from the nominal coordinates of the CMM, thus improving its measurement accuracy. Diagonal tests using a laser interferometer system were designed to check the error compensation effect. Test results showed that the use of the on-line compensation system can further improve the compensation effect as compared with the conventional off-line compensation system.
TL;DR: In this article, the influence of high pressure waterjet delivered into tool-chip interface in two different methods, namely, waterjet injected directly into the toolchip interface through a hole in the tool rake face, and water jet injected into tool chip interface through an external nozzle, was explored in terms of cutting force, surface finish, chip shape and tool wear.
Abstract: The efficiency of the metal cutting operations depends upon the thermal/frictional conditions at the tool-chip interface. The use of high pressure waterjet as a coolant/lubricant to improve the thermal/frictional conditions in milling operations was studied here. The influence of high pressure waterjet delivered into tool-chip interface in two different methods, namely, waterjet injected directly into the tool-chip interface through a hole in the tool rake face, and waterjet injected into tool-chip interface through an external nozzle, was explored in this study. The effectiveness of these developed methods was evaluated in terms of cutting force, surface finish, chip shape and tool wear.
TL;DR: In this paper, an offset beam element model was proposed to predict the assembly variation of deformable sheet metal parts joined by resistance spot welding, and the model was applied to predict sheet metal assembly variation for one-dimensional (1D) models extracted from industrial practice.
Abstract: Dimensional variation in sheet metal assembly affects product fit and functionality. To predict the variation of assembled products, variation simulation analysis has been gradually adopted in the early design stage. However, variation simulation based on rigid body assumptions usually results in over estimation of the assembly variation. In this paper, we propose an offset beam element model for predicting the assembly variation of deformable sheet metal parts joined by resistance spot welding. The purpose of using the offset beam element is to include the shear effect provided by resistance spot weld nuggets that cannot be captured by the conventional beam element. The offset element is then applied to predict sheet metal assembly variation for one-dimensional (1D) models extracted from industrial practice. The first example evaluates the effects of sheet metal thicknesses on assembly variation. The second example shows how the assembly sequence affects assembly variation. These models provide interesting insights into the mechanisms of variation stackup and will lead to the understanding of more complex sheet metal assemblies.
TL;DR: In this paper, a hierarchical planning system using heuristics for path planning in dimensional inspection using coordinate measuring machines (CMMs) is presented to automate the planning of a collision-free inspection path for dies and molds.
Abstract: A hierarchical planning system using heuristics for path planning in dimensional inspection using coordinate measuring machines (CMMs) is presented. The objective is to automate the planning of a collision-free inspection path for dies and molds. The proposed system demonstrates that the inspection paths of geometrically complex parts having multiple surfaces can automatically be generated with efficiency. This is made possible by appropriate CMM abstractions, genuine 3D collision detections, and heuristic modifications of reasonably assumed default inspection paths. Automatic generation of probe angles based on a local accessibility analysis of a given surface is also presented. The collision-free inspection path can then be simulated in a CAD environment before it is carried out by the real CMM. Both simulation and experiment show excellent results of the proposed path planning strategies and demonstrate the feasibility of automatic path planning in dimensional inspection of dies and molds using CMMs.
TL;DR: In this article, various steel specimens have been surface ground under dry conditions, with soluble oil and by a liquid nitrogen jet, and significant improvements in the chip formation and reduction in specific energy requirement, grinding temperature and residual stress were observed in cryo-grinding when compared with grinding dry and with a soluble oil.
Abstract: Grinding yields high temperature which not only limits the wheel life but also induces tensile residual stresses, micro-cracks, etc. at the ground surfaces. This problem becomes acute when the components are of hard and strong materials and used in dynamic loading. In such cases intensive cooling is essential. In this work various steel specimens have been surface ground under dry conditions, with soluble oil and by a liquid nitrogen jet. Significant improvements in the chip formation and reduction in specific energy requirement, grinding temperature and residual stress were observed in cryo-grinding when compared with grinding dry and with soluble oil.
TL;DR: In this paper, the development and application of PCD cutting tools are outlined for the drilling and single blade reaming of aluminium-silicon alloys containing 7% and 13% silicon and aluminium 2618 MMC alloy reinforced with 15 vol% silicon carbide (SiC) particulate.
Abstract: Following a review of metal matrix composite (MMC) materials and production methods, the paper outlines the development and application of PCD cutting tools. Experimental data are presented for the drilling and single blade reaming of aluminium-silicon alloys containing 7% and 13% silicon and aluminium 2618 MMC alloy reinforced with 15 vol% silicon carbide (SiC) particulate. Though initially aimed only at aerospace and defence products, MMCs have progressively moved into higher volume applications and are currently under evaluation for volume automotive components. Compared with standard hypoeutectic and hypereutectic cast aluminium-silicon alloys, tool wear when machining MMC is shown to be up to seven times more severe. Tools used for drilling include HSS-M2, diamond plated HSS, WC, TiN coated WC and PCD. Other than when using PCD drills, tool life was extremely short due to the abrasive nature of the (SiC) reinforcement. Similarly, results from PCD reaming tests confirmed that diamond tooling provides the only realistic tooling option.
TL;DR: In this article, a least square inverse scheme is applied to solve the unknown boundary at the tool-work interface based on the surface temperatures measured outside the cutting zone by an infrared (IR) pyrometer.
Abstract: An inverse heat conduction problem of end milling is studied in this paper. The transient tool-face temperature and heat dissipation to the workpiece in the milling area are estimated by an inverse finite element method with the temperatures measured on the machined surface. A least square inverse scheme is applied to solve the unknown boundary at the tool-work interface based on the surface temperatures measured outside the cutting zone by an infrared (IR) pyrometer. An ellipsoidal mapping model is adopted for coordinate transformation of a moving heat source system, which is treated in a one-dimensional (1D) ellipsoidal coordinate. The numerical and experimental results show a good agreement in the estimation for the flame heating and end milling of steel and aluminum alloy.
TL;DR: In this paper, the authors presented an experimental and numerical study of fracture initiation in thin aluminum oxide ceramics (AI2O3) during laser cutting in the experiments, alumina plates with thickness of 08 mm were cut at cutting speeds of 13-152 mm/sec by continuous-wave CO2 laser with power ranging from 200 to 700 W.
Abstract: This paper presents an experimental and numerical study of fracture initiation in thin aluminum oxide ceramics (AI2O3) during laser cutting In the experiments, alumina plates with thickness of 08 mm were cut at cutting speeds of 13–152 mm/sec by continuous-wave CO2 laser with power ranging from 200 to 700 W Criteria for fracture initiation are correlated with laser power and cutting speed A hybrid method for modeling fracture initiation is introduced whereby the kerf width is determined through an analytical solution and the temperature and stress distributions are found through a numerical plane stress model Temperature dependence of material properties was incorporated in the model Effect of cutting speed and laser power on the fracture initiation was analyzed quantitatively and good agreement was obtained between the experiment and the numerical simulation The results showed that avoidance of fracture initiation results from a high energy density cutting condition (high laser power and low cutting speed)
TL;DR: In this article, a real-time error compensation (RTEC) system is developed to correct thermally-induced and geometric errors on a four-axis dual-spindle turning center.
Abstract: A real-time error compensation (RTEC) system is developed to correct thermally-induced and geometric errors on a four-axis dual-spindle turning center. These errors vary with different cutting tool positions as well as different thermal conditions, thus real-time correction is required. Two problems in the current RTEC approach are addressed: (1) the difficulty in the actual measurement of error components according to the defined coordinates and (2) the selection of a small set of appropriate temperature variables from numerous candidate thermal sensors on a machine structure. A flexible error measurement method and an optimal temperature variable selection process are proposed to overcome these difficulties. After machine errors were characterized and modeled, the effectiveness of the developed RTEC system was evaluated by using laser inspection and an actual cutting test. The maximal diagonal displacement error is corrected from 75.0 to 7.5 μm. In the cutting test, the part diameter error of a car steering joint is reduced from 60 to 10 μm.
TL;DR: In this paper, the authors investigated chip geometry and cutting force in the balkend milling process, including the chip geometry, the cutting force, the tool deflection and the deflection sensitivity of the surface geometry.
Abstract: The study of machining errors caused by tool deflection in the balkend milling process involves four issues, namely the chip geometry, the cutting force, the tool deflection and the deflection sensitivity of the surface geometry. In this paper, chip geometry and cutting force are investigated. The study on chip geometry includes the undeformed radial chip thickness, the chip engagement surface and the relationship between feed boundary and feed angle. For cutting force prediction, a rigid force model and a flexible force model are developed. Instantaneous cutting forces of a machining experiment for two 2D sculptured surfaces produced by the ball-end milling process are simulated using these force models and are verified by force measurements. This information is used in Part 2 of this paper, together with a tool deflection model and the deflection sensitivity of the surface geometry, to predict the machining errors of the machined sculptured surfaces.
TL;DR: In this paper, an artificial neural network based technique which correlates the thermal error field to the machine temperature field is then developed to model the measured multiple thermal errors all together, and a PC based error compensation scheme has also been developed to upgrade a FANUC CNC controller for real-time thermal error compensation.
Abstract: This research is concerned with enhancing the accuracy of a machining center through compensating for the thermally induced errors of the spindle and leadscrews using software. A quick set-up and multiple degree of freedom measurement system consisting of an on-machine probe and artifacts has been developed to accelerate and simplify the thermal error measurement. An artificial neural network based technique which correlates the thermal error field to the machine temperature field is then developed to model the measured multiple thermal errors all together. Test results show that the ANN can not only fit the highly nonlinear thermal errors well, but has also predicted thermal errors well even under varying or new cutting conditions with a precision of more than 85%. A PC based error compensation scheme has also been developed to upgrade a FANUC CNC controller for real-time thermal error compensation. Test results on a vertical machining center show that a 70–90% reduction of thermal errors has been gained after compensation.
TL;DR: In this article, a computer-aided error compensation scheme was developed to enhance the accuracy of multi-axis CNC machine tools by compensating for machine geometric and thermal errors in software way.
Abstract: A computer-aided error compensation scheme has been developed to enhance the accuracy of multi-axis CNC machine tools by compensating for machine geometric and thermal errors in software way. Stationary geometric errors including the coupling effect of linkage errors between machine slides are calibrated off line. Dynamic thermal errors are predicted on line by an artificial neural network model. Because machine errors are variant with the cutting time and slide positions, a PC based compensation controller has been developed to upgrade commercial CNC controllers for real-time error compensation. The real-time compensation capability is achieved by digital I/0 communication between the compensation controller and CNC controller without the need of any hardware modification to the machine servo-drive loops. The compensation scheme implemented on a horizontal machining center has been proven to improve the machine accuracy by one order of magnitude using a laser interferometer and cutting test.
TL;DR: In this paper, a preform design method which employs an alternative boundary node release criterion in the finite element simulation of backward deformation of forging processes is presented. But this method does not consider the effect of releasing each of a select group of boundary element nodes at each finite element solution step and the particular detached node which results in the minimum shape complexity factor will be released for the current step.
Abstract: This paper presents a preform design method which employs an alternative boundary node release criterion in the finite element simulation of backward deformation of forging processes. The method makes use of the shape complexity factor which provides an effective measure of forging difficulty. The objective is to release die contacting nodes in a sequence which will minimize the geometric complexity throughout the backward deformation simulation. This is done by calculating the effect of releasing each of a select group of boundary element nodes at each finite element solution step. The particular detached node which results in the minimum shape complexity factor will be released for the current step. This process continues for each backward step until the last few nodes remain in contact. This design method is demonstrated through the simulated forging of an integrated blade and rotor turbine disk blank. A preform shape developed by this method is compared with an empirically designed preform. Performance parameters for comparison include die fill, flash volume, effective strain variance, frictional power and die load. Comparing the results of the forward simulations indicates improved performance of the preform design using FEM based backward deformation method over that of the empirical design.
TL;DR: In this article, the authors describe a new profiler for fast 3D measurements of both optically smooth and optically rough surfaces based on scanning white light techniques, which utilizes an efficient algorithm to extract and save only the region of interference.
Abstract: We describe a new profiler for fast 3-dimensional measurements of both optically smooth and optically rough surfaces based on scanning white light techniques. The profiler utilizes an efficient algorithm to extract and save only the region of interference, substantially reducing both the acquisition and analysis time while measuring rougher surfaces and larger step heights than conventional phase shifting techniques. The instrument measures steps to 100 microns, scans a 10 micron range in 5 seconds and has a smooth surface repeatability of 0.5nm.
TL;DR: In this paper, a tool deflection model is developed to calculate the corresponding horizontal tool-deflection at the surface generation points on the cutter, and the sensitivity of the machining errors to tool deflections, both in magnitude and direction, has been analyzed via the deflection sensitivity of surface geometry.
Abstract: This paper presents a surface generation model for sculptured surface productions using the ball-end milling process. In this model, machining errors caused by tool deflections are studied. As shown in Part 1 of this paper, instantaneous horizontal cutting forces can be evaluated from the cutting geometries using mechanistic force models. In this paper, a tool deflection model is developed to calculate the corresponding horizontal tool deflection at the surface generation points on the cutter. The sensitivity of the machining errors to tool deflections, both in magnitude and direction, has been analyzed via the deflection sensitivity of the surface geometry. Machining errors are then determined from the tool deflection and the deflection sensitivity of the designed surface. The ability of this model in predicting dimensional errors for sculptured surfaces produced by the ball-end milling process has been verified by a machining experiment. In addition to providing a means to predict dimensional accuracy prior to actual cutting, this surface generation model can also be used as a tool for quality control and machining planning.
TL;DR: In this article, the authors reveal the mechanism of phase transformation of workmaterials induced by grinding using the finite element method and the heat source generated during grinding was considered as a moving heat flux with a triangular profile.
Abstract: One of the most important problems in high precision grinding is the optimisation of the surface residual stress distribution of ground components. It has been realised that the heat generated in the grinding zone plays a central role in the phase transformation of workmaterials that would alter the residual stress formation. The purpose of this paper was to reveal the mechanism of phase transformation of workmaterials induced by grinding. The finite element method was used to simulate the grinding processes. The heat source generated during grinding was considered as a moving heat flux with a triangular profile. Effects of table speed, heat flux distribution, thermal properties of workmaterials and convective features of coolant were discussed in detail. It was found that an optimal combination of grinding conditions could minimise the depth of phase transformation. The results of this paper also offered essential information for the mechanism exploration of residual stresses in ground components.
TL;DR: In this article, the method of multiple regression is used to analyze the thermal deformation of a ball screw feed drive system, and the test results show that this method can well predict the thermal deformations of the ball screw during variation of the speed of rotation.
Abstract: In machine tools with semi-closed loop numerical control, the thermal deformation of the ball screw directly produces the position error of the feed drive system. In this work the method of multiple regression is used to analyze the thermal deformation of a ball screw feed drive system. Key points of thermal source (front bearing, nut and back bearing) were selected as independent variables of the analysis model. The test results show that this method can well predict the thermal deformation of the ball screw during variation of the speed of rotation.