Analysis and improvement of the positioning accuracy of rotary axes of compound machine tools based on pitch error compensation

2020 ◽  
Vol 31 (11) ◽  
pp. 115003
Author(s):  
Yingchun Wu ◽  
Jianxin Shen
Keyword(s):  
Error Compensation ◽  
Machine Tools ◽  
Positioning Accuracy ◽  
Rotary Axes ◽  
Pitch Error

The Study on CNC Machine Tools Reform and Error Analysis

2013 ◽  
Vol 299 ◽  
pp. 16-18
Author(s):  
Xue Peng Liu ◽  
Dong Mei Zhao
Keyword(s):  
Error Analysis ◽  
Error Compensation ◽  
Machine Tools ◽  
Servo System ◽  
Control Program ◽  
Cnc Machine Tools ◽  
Cnc Machine ◽  
Positioning Accuracy ◽  
Pitch Error

The control program and servo system of CNC machine tools is analyzed. By pitch error and quadrant error compensation, the positioning accuracy in X-direction is ± 20 μ m.

A Study on the Development of a Practical Postprocessor for 5-Axis Machining

2010 ◽  
Author(s):  
J. D. Hwang ◽  
H. C. Jung ◽  
K. B. Park ◽  
Y. G. Jung
Keyword(s):  
Machine Tools ◽  
Inverse Kinematics ◽  
General System ◽  
Visual Basic ◽  
Work Piece ◽  
Cutting Simulation ◽  
Rotary Axes ◽  
Data Formats ◽  
Data Vector ◽  
Nc Data

This paper deals with the development of a practical postprocessor for 5-axis machine tools. Recently, special 5-axis machine tools with non-orthogonal rotary axes as well as typical 5-axis machine tools with orthogonal rotary axes have been introduced. In the present work, the general equations of NC data for 5-axis configurations with non-orthogonal rotary axes are exactly expressed by the inverse kinematics, and a Windows-based postprocessor written in Visual Basic was developed according to the proposed algorithm. The developed postprocessor is a general system suitable for all kinds of 5-axis machine tools not only with orthogonal rotary axes but also with non-orthogonal rotary axes, thereby expanding the range of application of the developed postprocessor. In addition, through implementation of the developed postprocessor and verification by a cutting simulation and machining experiment, the effectiveness of the proposed algorithm was confirmed. Compatibility was improved by allowing exchange of data formats such as RTCP controlled NC data, Vector post NC data, and POF CL data, and convenience was increased by adding the function of work-piece origin offset. Consequently, a practical post-processor for 5-axis machining has been developed.

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.

An Analytical C3 Continuous Local Corner Smoothing Algorithm for Four-Axis Computer Numerical Control Machine Tools

2018 ◽  
Vol 140 (5) ◽  
Author(s):  
Qin Hu ◽  
Youping Chen ◽  
Jixiang Yang ◽  
Dailin Zhang
Keyword(s):  
Machine Tools ◽  
Numerical Control ◽  
Cnc Machine Tools ◽  
Smoothing Algorithm ◽  
Linear Motion ◽  
Tool Orientation ◽  
Cnc Machine ◽  
B Splines ◽  
Rotary Axes ◽  
Tip Position

Linear motion commands of multi-axis computer numerical control (CNC) machine tools need to be smoothed at the transition corners, because the velocity discontinuities at corners can result in fluctuations on machine tool motions and lead to poor surface quality. However, no research has been reported on local corner smoothing algorithm for four-axis CNC machine tools with two rotary axes by considering their special kinematic characteristics. To this end, this paper proposes an analytical C3 continuous local corner smoothing algorithm for four-axis CNC machines with two rotary axes. After coordinates transformation, the tool tip positions and tool orientations are smoothed by locally inserting specially designed three-dimensional (3D) quintic B-splines and one-dimensional (1D) quintic B-splines into the corners between linear motion segments, respectively. The smoothing algorithm guarantees C3 continuity of the tool tip position and C3 continuous synchronization of the tool orientation related to the tool tip position, through analytically evaluating control points of the inserted microsplines. The maximum error tolerances of the tool tip position and tool orientation are mathematically constrained. Experiments on an in-house developed four-axis machine verify the efficacy of the proposed algorithm, where maximal errors caused by the local corner smoothing algorithm are constrained, the synchronization of the tool orientation and the tool tip position are achieved, and the proposed C3 continuous corner smoothing algorithm has lower jerk and jounce but higher tracking and contour accuracy than C2 continuous algorithm.

scholarly journals Rapid Measurement and Identification Method for the Geometric Errors of CNC Machine Tools

2019 ◽  
Vol 9 (13) ◽  
pp. 2701 ◽  
Author(s):  
Li ◽  
Yang ◽  
Gao ◽  
Su ◽  
Wei ◽  
...  
Keyword(s):  
Error Compensation ◽  
Machine Tools ◽  
Degrees Of Freedom ◽  
Cnc Machine Tools ◽  
Geometric Errors ◽  
Two Dimensional ◽  
Cnc Machine ◽  
Angle Sensor ◽  
Identification Method ◽  
Measuring Machine

Error compensation technology offers a significant means for improving the geometric accuracy of CNC machine tools (MTs) as well as extending their service life. Measurement and identification are important prerequisites for error compensation. In this study, a measurement system, mainly composed of a self-developed micro-angle sensor and an L-shape standard piece, is proposed. Meanwhile, a stepwise identification method, based on an integrated error model, is established. In one measurement, four degrees-of-freedom errors, including two-dimensional displacement and two-dimensional angle of a linear guideway, can be obtained. Furthermore, in accordance with the stepwise identification method, the L-shape standard piece is placed in three different planes, so that the measurement and identification of all 21 geometric errors can be implemented. An experiment is carried out on a coordinate measuring machine (CMM) to verify the system. The residual error of the angle error, translation error and squareness error are 1.5″, 2 μm and 3.37″, respectively, and these are compared to the values detected by a Renishaw laser interferometer.

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