Measuring Path without Tool Center Point Function for B-Type Five-Axis Machine Tool

2013 ◽  
Vol 284-287 ◽  
pp. 493-497
Author(s):  
Chen Hua She ◽  
Wen Yuh Jywe ◽  
Jheng Jie Huang
Keyword(s):  
Machine Tool ◽  
Machine Tools ◽  
Simulation Software ◽  
Free Form ◽  
Motion Error ◽  
Center Point ◽  
Wide Range ◽  
Assembly Error ◽  
Five Axis ◽  
Free Form Surfaces

Five-axis machine tools with three linear axes and two rotary axes can produce complex products with free-form surfaces requiring a high degree of precision. However, motion errors of each axis and its assembly error are accumulated in the positioning error of the cutting tool relative to a workpiece. There are many devices reported in the literature on the identification of kinematic errors based on the measurement of the motion error. According to the measurement paths in the ISO draft, ISO/CD 10791-6, the kinematic tests can be applicable to different configurations of five-axis machine tools. However, the advanced controller with tool center point (TCP) function is required while performing kinematic tests. This paper proposed the methodology of generating measurement path without TCP function for B-type five-axis machine tool. The developed module can transform the measuring path into an NC program used for lower hand controller. Verification using VERICUT solid cutting simulation software demonstrated the veracity of the generated five-axis NC code. The proposed methodology is applicable in a wide range of five-axis machine tool configurations; however, further testing with actual measuring applications will be required for further verification.

Tool Path Planning and NC Generation of Tilted Plane Machining Features for Five-Axis Machining

2011 ◽  
Vol 697-698 ◽  
pp. 309-313 ◽  
Author(s):  
Chen Hua She ◽  
Yueh Hsun Tsai
Keyword(s):  
Machine Tool ◽  
Degrees Of Freedom ◽  
Tool Path ◽  
Simulation Software ◽  
Free Form ◽  
Parent Child Relationship ◽  
Machining Feature ◽  
Machining Errors ◽  
Tilted Plane ◽  
Five Axis

Designs of free-form surface products are becoming increasingly complex. In traditional three-axis machine tool machining, errors that are caused by repetitive positioning and the costs of fixture jig design and manufacturing are critical. Since multi-axis machining provides two more rotational degrees of freedom than a three-axis machine tool, the former can solve these problems, and has therefore become the trend of precision cutting. As multi-axis machined parts often have holes and grooves on the tilted plane, this work proposes a method for machining tilted working plane features and for NC generation on a five-axis machine. The developed module can provide common geometric features, allowing the user to alter the machining feature and sequence on the tilted plane quickly using the parent-child relationship in a tree diagram, and plan the tool path. The postprocessor module developed in this paper can transform the tool path into an NC program required for machining. Finally, solid cutting simulation software is utilized to confirm the feasibility and correctness of the tool path and NC data of the tilted plane machining feature.

Nonlinear Error Compensation Based on the Optimization of Swing Cutter Trajectory for Five-Axis Machining

2021 ◽  
Author(s):  
Liangji Chen ◽  
Jinmeng Tang ◽  
Wenyi Wu ◽  
Zisen Wei
Keyword(s):  
Machine Tool ◽  
Error Compensation ◽  
Rotation Axis ◽  
Kinematic Model ◽  
Free Form ◽  
Nonlinear Error ◽  
Center Point ◽  
Parameterized Model ◽  
Five Axis ◽  
The Impact

Abstract In order to solve the problem of deviation between actual and theoretical machining paths due to the presence of rotation axis in five-axis machining, an interpolation algorithm based on the optimization of swing cutter trajectory and the method of corresponding nonlinear error compensation are proposed. Taking A-C dual rotary table five-axis machine tool as an example, the forward and reverse kinematic model of the machine tool is established according to the kinematic chain of the machine tool. Based on the linear interpolation of rotary axis, the generation mechanism of nonlinear error is analyzed, the modeling methods of cutter center point and cutter axis vector trajectory are proposed respectively, and the parameterized model of swing cutter trajectory is formed. The formula for the nonlinear error is obtained from the two-dimensional cutter center point trajectory. According to the established model of swing cutter trajectory, the synchronous optimization method of cutter center point trajectory and cutter axis vector trajectory is proposed, and the nonlinear error compensation mechanism is established. First, pre-interpolation is performed on the given cutter location data to obtain a model of the swing cutter trajectory for each interpolated segment. Then the magnitude of the nonlinear error is calculated based on the parameters of the actual interpolation points during formal interpolation, and the interpolation points with large errors are compensated for the nonlinear error. The simulation results show that the proposed method can effectively reduce the impact of nonlinear errors on machining, and is of high practical value for improving the accuracy of cutter position and the quality of complex free-form machining in five-axis machining.

Characterization of Kinematic Error Model Consistency for Five-Axis Machine Tools

2018 ◽  
Author(s):  
Le Ma ◽  
Douglas A. Bristow ◽  
Robert G. Landers
Keyword(s):  
Machine Tool ◽  
Machine Tools ◽  
Error Model ◽  
Data Sets ◽  
Kinematic Error ◽  
Interior Space ◽  
Error Models ◽  
Wide Range ◽  
Kinematic Error Model ◽  
Five Axis

New metrology tools, such as laser trackers, are enabling the rapid collection of machine tool geometric error over a wide range of the workspace. Error models fit to this data are used to compensate for high-order geometric errors that were previously challenging to obtain due to limited data sets. However, model fitting accuracy can suffer near the edges of the measurable space where obstacles and interference of the metrology equipment can make it difficult to collect dense data sets. In some instances, for example when obstacles are permanent fixtures, these locations are difficult to measure but critically important for machining, and thus models need to be accurate at these locations. In this paper, a method is proposed to evaluate the model accuracy for five-axis machine tools at measurement boundaries by characterizing the statistical consistency of the model fit over the workspace. Using a representative machine tool compensation method, the modeled Jacobian matrix is derived and used for characterization. By constructing and characterizing different polynomial order error models, it is observed that the function behavior at the boundary and in the unmeasured space is inconsistent with the function behavior in the interior space, and that the inconsistency increases as the polynomial order increases. Also, the further the model is extrapolated into unmeasured space, the more inconsistent the kinematic error model behaves.

Influence of Servo Characteristics on Motion Accuracy of Parallel Kinematic Mechanism

2012 ◽  
Vol 523-524 ◽  
pp. 762-767 ◽  
Author(s):  
Ryuta Sato ◽  
Michitaka Maegawa ◽  
Gen Tashiro ◽  
Keiichi Shirase
Keyword(s):  
Machine Tool ◽  
Machine Tools ◽  
Servo Motor ◽  
Motion Error ◽  
Center Point ◽  
Parallel Kinematic Mechanism ◽  
Parallel Kinematic ◽  
Motion Characteristics ◽  
Dimensional Errors ◽  
Kinematic Mechanism

Parallel kinematic mechanism (PKM) is applied to machine tools and robots since its flexibility and speed. In machine tools, additionally, motion accuracy is strongly desired. Although various research works aimed to calibrate static geometrical deviations of the PKM machines in order to improve motion accuracy, influence of dynamic motion error of servo system has not been investigated well up to now. In this study, the influence of servo characteristics on motion accuracy of a PKM machine tool driven by six servo motors is discussed, because it is expected that the contouring motion accuracy of a PKM machine tool is strongly depends on the servo characteristics. A servo motor which installed to the machine is modeled to simulate the motion characteristics of each servo motor. The motor models are coupled with a model of link mechanism, and the motion accuracy of a tool center point is simulated. Also, both of positional and angular errors are simulated successfully. As the results of the simulations, it is clarified that the motion accuracy is strongly depends on the servo characteristics and location of the tool center point. In addition, the motion errors are observed as six dimensional errors. It is also discussed that the influence of friction torques on the motion accuracy.

Linked Ball Bar for Flexible Motion Error Measurement for Machine Tools

2017 ◽  
Vol 11 (2) ◽  
pp. 188-196 ◽  
Author(s):  
Daisuke Kono ◽  
◽  
Fumiya Sakamoto ◽  
Iwao Yamaji
Keyword(s):  
Machine Tool ◽  
Machine Tools ◽  
Measurement Range ◽  
Motion Error ◽  
Ball Bar ◽  
Displacement Direction ◽  
The Difference ◽  
Tool Motion ◽  
Five Axis ◽  
Analytical Resolution

A measuring instrument, Linked Ball Bar (LBB), is developed to measure machine tool motion errors quickly, flexibly, and robustly. The LBB employs the concept of double ball bar (DBB) and measures the distance between two balls attached to the spindle and table. The problem of short measurement range, the drawback of the DBB, is solved using a link. The measurement accuracy of the LBB is investigated. The analytical resolution of displacement measurement using the LBB is under 30 nm when the displacement direction coincides with the sensitivity direction. The difference between the LBB and the laser interferometer is less than 1 μm in the center measurement range of 75 mm. The repeatability of the LBB is ±0.4 μm and is at the same level as the interferometer. The kinematic error of a five-axis machine tool is measured using the LBB to demonstrate its validity. The parallelism between the C-axis and Z-axis identified using the LBB agrees with the result measured using the cylindrical square. The difference between the LBB and the cylindrical square is about 10 μm/m at the maximum. The LBB can provide quick and flexible measurements of the motion errors of five-axis machine tools.

An Attempt of Error Tracing and Compensation Method of the Linkage Error of Five-Axis CNC Machine Tool

2018 ◽  
Author(s):  
Zhong Jiang ◽  
Jiexiong Ding ◽  
Qicheng Ding ◽  
Li Du ◽  
Wei Wang
Keyword(s):  
Machine Tool ◽  
Machine Tools ◽  
Manufacturing Industry ◽  
Complex Surface ◽  
Compensation Method ◽  
Cnc Machine ◽  
Linkage Error ◽  
Error Tracing ◽  
Five Axis ◽  
Five Axes

Nowadays the five-axis machine tool is one of the most important foundations of manufacturing industry. To guarantee the accuracy of the complex surface machining, multi-axis linkage performance detection and compensation of five-axis machine tools is necessary. RTCP (Rotation Tool Center Point) is one of the basic essential functions for the five-axis machine tools, which can keep the tool center with the machining trajectory when five axes move synchronously. On the basis of RTCP function, a way to detect multi-axes linkage performance of five-axis machine tools is briefly introduced, and linkage error model is built in accordance with the topological structure of machine tool. Based on the feature of the linkage errors of the five-axis machine tool, the error tracing and compensation method is proposed. Some simulations and experiments that verify the error tracing method could locate the linkage error category are established. Therefore, a new attempt to detect and compensate the linkage error of the five-axis machine tool is provided in this paper.

A Universal Postprocessor of General Table-Tilting Type of Five-Axis Machine Tools Without Rotational Tool Center Point Function for Actual NC Code Generation

2018 ◽  
Author(s):  
Guoqiang Fu ◽  
Hongli Gao ◽  
Tengda Gu
Keyword(s):  
Code Generation ◽  
Machine Tools ◽  
Kinematic Chain ◽  
Rotary Axes ◽  
Nc Code ◽  
Rotation Axes ◽  
Cutting Test ◽  
Center Point ◽  
Rtcp Function ◽  
Five Axis

The postprocessor is essential for machining with five-axis machine tools. This paper develops one universal postprocessor for table-tilting type of five-axis machine tools without rotational tool center point (RTCP) function. Firstly, positions of two rotary axes and the workpiece in the machine coordinate system (MCS) are introduced into the kinematic chain of the five-axis machine tools. The uniform product of exponential (POE) formula of the tool relative to the workpiece is established to obtain the universal forward kinematics. On this basis, the postprocessor of table-tilting type of five-axis machine tools is developed. The calculation of rotation angles of rotation axes is proposed in details, including the calculation of double solutions, the determination of rotation angles of C-axis and the selection principle of the shortest path of rotation angles. Movements of linear axes are calculated with rotation angles of rotary axes. The generated movements of all axes are actual positions of all axes relative to their zero positions, which can be used for machining directly. The postprocessor does not rely on RTCP function with positions of rotary axes and the workpiece in MCS. Finally, cutting test in VERICUT and real cutting experiments on SmartCNC500_DRTD five-axis machine tool are carried out to verify the effectiveness of the proposed postprocessor.

scholarly journals Efficient and Innovative Polishing Processes for Smoothing Complex Surface Geometries and Internal Contours on Brittle-Hard Components

2020 ◽  
Vol 238 ◽  
pp. 03010
Author(s):  
Marcel Binder ◽  
Sebastian Henkel ◽  
Anne-Marie Schwager ◽  
Christoph Letsch ◽  
Jens Bliedtner ◽  
...  
Keyword(s):  
Current Trend ◽  
Glass Ceramics ◽  
Complex Surface ◽  
Fused Silica ◽  
Free Form ◽  
Resource Saving ◽  
Processing Technologies ◽  
Wide Range ◽  
Monolithic Components ◽  
Free Form Surfaces

The material fused silica, as well as other brittle-hard materials such as glass ceramics, have great potential for use in a wide range of applications due to their special material properties. The technical advantages of these materials require sophisticated processing technologies, including polishing steps, in order to be able to use these interesting materials advantageously. In addition, a current trend in modern optical manufacturing is the use of free-form surfaces and monolithic components that combine several optical and mechanical functions in one part. Novel or improved processes are needed in order to meet future requirements for resource-saving and effective production methods at the same time.

Table-Based Volumetric Error Compensation of Large Five-Axis Machine Tools

2016 ◽  
Vol 139 (2) ◽  
Author(s):  
Jennifer Creamer ◽  
Patrick M. Sammons ◽  
Douglas A. Bristow ◽  
Robert G. Landers ◽  
Philip L. Freeman ◽  
...  
Keyword(s):  
Machine Tool ◽  
Error Compensation ◽  
Machine Tools ◽  
Data Gathering ◽  
Measurement Data ◽  
Geometric Error ◽  
Compensation Method ◽  
Geometric Errors ◽  
Simultaneous Generation ◽  
Five Axis

This paper presents a geometric error compensation method for large five-axis machine tools. Compared to smaller machine tools, the longer axis travels and bigger structures of a large machine tool make them more susceptible to complicated, position-dependent geometric errors. The compensation method presented in this paper uses tool tip measurements recorded throughout the axis space to construct an explicit model of a machine tool's geometric errors from which a corresponding set of compensation tables are constructed. The measurements are taken using a laser tracker, permitting rapid error data gathering at most locations in the axis space. Two position-dependent geometric error models are considered in this paper. The first model utilizes a six degree-of-freedom kinematic error description at each axis. The second model is motivated by the structure of table compensation solutions and describes geometric errors as small perturbations to the axis commands. The parameters of both models are identified from the measurement data using a maximum likelihood estimator. Compensation tables are generated by projecting the error model onto the compensation space created by the compensation tables available in the machine tool controller. The first model provides a more intuitive accounting of simple geometric errors than the second; however, it also increases the complexity of projecting the errors onto compensation tables. Experimental results on a commercial five-axis machine tool are presented and analyzed. Despite significant differences in the machine tool error descriptions, both methods produce similar results, within the repeatability of the machine tool. Reasons for this result are discussed. Analysis of the models and compensation tables reveals significant complicated, and unexpected kinematic behavior in the experimental machine tool. A particular strength of the proposed methodology is the simultaneous generation of a complete set of compensation tables that accurately captures complicated kinematic errors independent of whether they arise from expected and unexpected sources.

On-Machine Metrology System Using Confocal Chromatic Probe and Motion Error Correction for Ultra-Precision Machine Tool

2020 ◽  
Author(s):  
Hao Duan ◽  
Shinya Morita ◽  
Takuya Hosobata ◽  
Masahiro Takeda ◽  
Yutaka Yamagata
Keyword(s):  
Machine Tool ◽  
Free Form ◽  
Reference Curve ◽  
Optical Surface ◽  
Motion Error ◽  
Precision Machine ◽  
Ultra Precision ◽  
Axis Position ◽  
Form Deviation ◽  
Accuracy And Repeatability

Abstract Aspherical or free-form optical surface machining using an ultra-precision machine tool is a common and effective method in precision optics manufacturing. However, this method sometimes causes waviness due to the machine’s motion in mid-spatial frequency (MSF) form deviations. This waviness lowers the quality of the optical surface. To address this problem, we use the waviness of the axial displacement of the ultra-precision machine tool. The waviness is obtained by a non-contact on-machine metrology (OMM) system that measures an optical flat as a correction reference curve, which is used to correct the surface of the workpiece to reduce the effect of waviness in advance. The OMM system consists of a displacement probe and a machine tool axis position capture device. The probe system uses a confocal chromatic probe on an ultra-precision machine tool to evaluate the form deviation of the workpiece with 1 nm resolution. The axis position capture system uses a signal branch circuit of linear scale on each axis from the ultra-precision machine tool. The OMM system is tested in terms of accuracy and repeatability. In comparison to the results of the shaper cutting of an oxygen-free copper (OFC) workpiece with feed-forward correction, we were able to reduce the profile error from 125.3 nm to 42.1 nm in p-v (peak to valley) and eventually also reduced the waviness.

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