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Ding S.,Nanjing University of Technology | Huang X.,Nanjing University of Technology | Yu C.,Nanjing Gongda CNC Technology Co. | Liu X.,University of Illinois at Chicago
International Journal of Advanced Manufacturing Technology | Year: 2015

It has been proven that error compensation is a key technique to improve machining accuracy. However, existing iteration and recursive compensation algorithm is difficult to realize. Hence, a simple and rapid compensation method is considerably necessary for engineering application. In this paper, a novel compensation strategy just by algebraic operation was first proposed for machining accuracy improvement. Error motion transformation was introduced to build the position-independent geometric error (PIGE) model according to homogeneous transformation matrix (HTM). Then, the analytical numerical control (NC) code expression with error compensation was derived and used for NC code generation. In addition, the presented method is appropriate for post-processing of non-orthogonal machine tool. At last, simulation and cutting experiment were demonstrated to verify the feasibility and effectiveness of the proposed method. Taking hemisphere surface as the test object, the simulation results showed that the effects of PIGEs could be eliminated by the proposed method. The experiment results with compensation indicated that the machining accuracy improved to about 14 % compared with those without compensation. © 2015 Springer-Verlag London

Ding W.,Nanjing Institute of Technology | Zhu S.,Nanjing Institute of Technology | Wang M.,Nanjing Institute of Technology | Huang X.,Nanjing Gongda CNC Technology Co.
Jixie Gongcheng Xuebao/Journal of Mechanical Engineering | Year: 2015

With the development of CNC rotary tables for the trend of large scale, the difficulty of the research on the mechatronic characteristics is increased. Taking a large-scale CNC rotary table as an example, based on the consideration of the structural dynamics, kinematics, servo control system and its interaction, a detailed mechatronic model is established, and the speed response of the CNC rotary table is analyzed. In order to identify the effect of each compliant element of the mechanical transmission chain to the vibration performance of the CNC rotary table, the modal sensitivity analysis of the transmission chain is performed. The theoretical analysis and experiments indicate that the speed response of the rotary table is delayed due to the compliance effect of the mechanical transmission chain, and the compliance is the main limited factor for the performance of the CNC rotary table. The Coulomb friction is benefit to quickly damp the oscillations of the speed response, and a suitable Coulomb friction contributes to the performance of the rotary table. The rotary inertia of the motor shaft and the torsional stiffness of the worm are the biggest performance problems of the large-scale CNC rotary table. ©2015 Journal of Mechanical Engineering.

Cai Z.,Nanjing University of Technology | Hong R.,Nanjing University of Technology | Cui J.,Nanjing Gongda CNC Technology Co.
Jinshu Rechuli/Heat Treatment of Metals | Year: 2015

To solve the problems such as single function, closed control system and poor data management for slewing bearing overall quenching machine, an automatic control system was designed, which was based on the core controller PLC and HMI touch screen working as the human-computer interaction interface. The time sequence and logic control for overall quenching procedure were realized and the real-time parts processing parameters were accessed since the touch screen monitors the dynamic process. The key parameters such as power and quenching time can be set according to the manufacturing requirements from the user. As a result, this system not only resolved the problems of poor parameter data management and the openness of system, but also improved the quenching efficiency and stability, and ultimately accomplished the automation control of the overall quenching process. ©, 2015, Chinese Mechanical Engineering Society of Heat Treatment. All right reserved.

Ding S.,Nanjing University of Technology | Huang X.,Nanjing University of Technology | Yu C.,Nanjing Gongda CNC Technology Co. | Liu X.,University of Illinois at Chicago
International Journal of Machine Tools and Manufacture | Year: 2016

Geometric errors are the major error sources of machine tools. Different geometric error models have been used in published studies according to the different definitions of geometric errors of the rotary axis. This is considerably dangerous as it makes the definition of geometric errors ambiguous and may reduce the effect of geometric error identification and compensation. This phenomenon has not been noticed yet. In this paper, another two used geometric error models of rotary axis are firstly introduced and analyzed, named as "Error first model" and "Motion first model". These two models were both verified correctly by an example. After a detailed comparison, errors identified with these two models are discovered to have a certain relationship. "Error first model" is preferred for the modeling and definition of geometric errors of rotary axis. An experiment has been conducted on a 5-axis machine tool to demonstrate the correctness of our research. The results show that the identified geometric errors of rotary axis according to the two error models are greatly different and deserved to be concerned. © 2015 Elsevier Ltd. All rights reserved.

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