An indirect measurement method of volumetric errors for linear axes in CNC machine tools

2014 ◽  
pp. 213-215
Keyword(s):  
Machine Tools ◽  
Measurement Method ◽  
Indirect Measurement ◽  
Cnc Machine Tools ◽  
Cnc Machine ◽  
Volumetric Errors

Volumetric Positioning Errors of CNC Machining Tools and Laser Sequential Step Diagonal Measurement

2006 ◽  
Vol 315-316 ◽  
pp. 98-102 ◽  
Author(s):  
J.H. Shen ◽  
H.T. Zhang ◽  
Hong Tao Cao ◽  
Jian Guo Yang ◽  
C. Wang
Keyword(s):  
Machine Tools ◽  
Measurement Method ◽  
Measurement Data ◽  
Cnc Machining ◽  
Cnc Machine Tools ◽  
Cnc Machine ◽  
Transformation Matrices ◽  
Positioning Errors ◽  
Analysis Measurement ◽  
Key Factor

The volumetric positioning precision of CNC machine tools is the key factor to get high machining precision, so the analysis, measurement and compensation of the volumetric error is becoming more and more important. In this paper, the modeling results of 3-axes CNC machine tools with four different configurations are given based on rigid body theory and homogeneous coordination transformation matrices. An improved sequential step diagonal measurement method is proposed and analyzed because the current laser measurement methods are complex and time cost. At the final section of the paper, the measurement data was applied into the error compensation and the sequential step diagonal measurement method was validated efficient and convenient.

Compensation System for Thermal Deformations of Ballscrews

2014 ◽  
Author(s):  
Michał Kowal ◽  
Roman Staniek
Keyword(s):  
Thermal Expansion ◽  
Machine Tools ◽  
Kinematic Chain ◽  
Indirect Measurement ◽  
Cnc Machine Tools ◽  
Positioning Error ◽  
Cnc Machine ◽  
Measurement Systems ◽  
Drive Systems ◽  
Precise Machine

Accurate ballscrews are vital components of precise machine tool drive systems. As determined by direct measurement systems, the ballscrew positioning error has no bearing on the final positioning accuracy of the axis. For economical reasons, however, most machine tools are equipped with indirect measurement systems, in which errors stemming from thermal expansion of the ballscrew constitute approximately 60% of the kinematic chain error sum. Moreover, the currently observed boost in productivity of modern CNC machine tools leads to significant amplification of energy dispersal values in the nut-screw systems, due to the increased positioning velocity of the controlled axes. This, in turn, contributes to a rise of positioning error values through thermal expansion of the aforementioned ballscrews. This article deals with technological and constructional problems of screw lengthening compensation. It enumerates methods of thermal expansion-based error compensation as attained through utilization of indirect measurement systems. Finally, it presents experimental data indicating the possibility of effective screw lengthening compensation, thus proposing an alternative to the currently applied compensation systems.

Research on the Cutting Force Induced Error Measurement Method of the CNC Machine Tools

2012 ◽  
Vol 220-223 ◽  
pp. 426-430
Author(s):  
Huan Lao Liu ◽  
Bao Yue Chen ◽  
Feng Liu ◽  
Guang Yu Tan
Keyword(s):  
Cutting Force ◽  
Machine Tools ◽  
Measurement Method ◽  
One Dimension ◽  
Cnc Machine Tools ◽  
Error Measurement ◽  
Cnc Machine ◽  
Working Process ◽  
Machine Error ◽  
Hard Cutting

The cutting force induced error has been more important as the hard cutting and hard cutting material used. This paper proposed the direct measurement method of cutting force induced error, which realized the corresponding directly of the cutting force and the value of error in the working process. According to the discrimination of machine error characteristics reflected by the different measuring methods, it puts forward to building the mixed error model based on the measuring technology of one dimension and two dimension. The results could provides the test data and theoretical basis for the mechanism of the processing performance affected by the dynamic behavior of machine tools.

Measurement Method for Measuring Circular Motion Error of CNC Machine Tools

2008 ◽  
Vol 381-382 ◽  
pp. 145-148
Author(s):  
K.H. Lin ◽  
Ya Hui Hu ◽  
C.A. Chan ◽  
Ming Chang
Keyword(s):  
Measurement System ◽  
Machine Tools ◽  
Measurement Method ◽  
Circular Motion ◽  
Numerical Control ◽  
Cnc Machine Tools ◽  
Small Scale ◽  
Large Radius ◽  
Cnc Machine ◽  
Motion Error

The dynamic characteristic of CNC (computer numerical control) machine tools is a critical role to decide the accuracy and speed of machine. It is very important to improve the precision and reduce the motion error so as to manufacture complex and fine products. In general, the motion error is estimated by a two or three-dimensional ball bar measurement system. Although this technology is capable of dynamical measurement, its condition should be confined to a low speed or a large radius. A new measurement method for measuring circular motion error of CNC machine tools is proposed in this paper. The instrument consists of a dual-frequency laser interferometer, a beam splitter and two corner cubes. In order to evaluate the exactness of the results we get from our measurement system, we use RSF’s grid encoder to do another experiment and compare both the results. According to the results shown, our measurement system can measure both of the X and Y axes of the plane of the CNC stage in a small scale at the same time and can simplify the calibration procedure as well as shorten the time of measurement. This method can accomplish the two-axis measurement at a high speed, without being restricted by radius variations. It is a good, simple and effective measurement method.

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