Volumetric error modeling and compensation considering thermal effect on five-axis machine tools

Author(s):  
Yi Zhang ◽  
Jianguo Yang ◽  
Sitong Xiang ◽  
Huixiao Xiao

This article intends to provide an error compensation system for five-axis machine tools. A volumetric error model is established with homogeneous transformation matrix method, from which compensation values of both orientation and position errors can be obtained. Thirty-seven errors on a five-axis machine tool are classified into three categories – functional, random, and negligible errors, among which the effect of the first one on volumetric accuracy is considered as great enough to be included in this model. Some typical modeling methods are discussed on positioning and straightness errors, considering both geometric and thermal effects. Then, we propose a compensation implementation technique based on the function of external machine zero point shift and Ethernet data communication protocol for machine tools. Finally, laser diagonal measurements have been conducted to validate the effectiveness of the proposed volumetric error compensation system.

2014 ◽  
Vol 513-517 ◽  
pp. 4202-4205
Author(s):  
Hong Xin Zhang ◽  
Qian Jian Guo

With the increasing requirements of the machining accuracy of CNC machine tools, the impact of thermal deformation is growing. Thermal error compensation technology can predict and compensate the thermal errors in real-time, and improve the machining accuracy of the machine tool. In this paper, the research objects of thermal error compensation is expanded to the volumetric error of the machine tool, the volumetric error modeling of a three-axis machine tool is fulfilled and a compensator is developed for the compensation experiment, which provides scientific basis for the improvement of the machining accuracy.


2013 ◽  
Vol 284-287 ◽  
pp. 1723-1728
Author(s):  
Shih Ming Wang ◽  
Han Jen Yu ◽  
Hung Wei Liao

Error compensation is an effective and inexpensive way that can further enhance the machining accuracy of a multi-axis machine tool. The volumetric error measurement method is an essential of the error compensation method. The measurement of volumetric errors of a 5-axis machine tool is very difficult to be conducted due to its complexity. In this study, a volumetric-error measurement method using telescoping ball-bar was developed for the three major types of 5-axis machines. With the use of the three derived error models and the two-step measurement procedures, the method can quickly determine the volumetric errors of the three types of 5-axis machine tools. Comparing to the measurement methods currently used in industry, the proposed method provides the advantages of low cost, easy setup, and high efficiency.


Author(s):  
Qiang Cheng ◽  
Bingwei Sun ◽  
Zhifeng Liu ◽  
Qiunan Feng ◽  
Peihua Gu

Error compensation technique is a recognized and cost-effective method to improve machining accuracy of machine tools. In this article, a new compensation method for geometric error is proposed based on Floyd algorithm and product of exponential screw theory. Based on topological structure and measured data, volumetric geometric error modeling is established by product of exponential screw theory. Then, the improved Floyd minimum-distance method was used to establish an error compensation model by adjusting weight unceasingly. In order to verify the effectiveness and generality of the method proposed in this article, two experiments were designed. A total of 5 five-axis machining centers of the same type with different use time were selected to carry out the simulation experiments. Results show that the Floyd method can provide higher compensation precision, that is, Floyd algorithm compensation method can keep positioning errors within the range [−8 µm, 9 µm]. In addition, roundness error, coaxial error, and surface roughness were reduced in the actual machining experiments of two machined conical tables. Therefore, it can be seen that the proposed compensation method is effective to improve machining accuracy of machine tools.


2014 ◽  
Vol 1037 ◽  
pp. 283-287
Author(s):  
Shuang Ding ◽  
Xiao Diao Huang ◽  
Chun Jian Yu

This paper describes the enhancement of the machining precision of 5-axis machine tools. Most post-processors did not consider the pose errors so that the processing error was increased invisibly. A post processing method with pose error compensation was proposed for table/spindle-tilting type machine tools.12 position errors and 12 rotation errors were compensated by the proposed method. Mathematical model contained pose errors which converted cutter location data into machine motion coordinates was established based on inverse kinematics and the analytical solutions of NC code were derived. The tool paths of the freeform surface machining were posted with the presented method. And the simulation experiment was carried out which verified the feasibility of the post processing method with pose error compensation. Comparison of processing error shows that the post processing with pose error compensation can effectively improve the machining accuracy by approximately 50%.


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