Papers by Author: Gang Wei Cui

Abstract: Volumetric error has large effect on machine tool accuracy; improving CNC machine tool accuracy through error compensation has received significant attention recently. This paper intends to represent volumetric error measurement based on laser tracker. The volumetric error is modeled by homogenous transformation matrix with each coordinate corresponding to each motion axis. Based on parts of spatial points volumetric error, the geometric errors which affect volumetric positioning error are verified through particle swarm optimization with the L₂ parameters as the target function. The chebyshev orthogonal polynomials are applied to approximate geometric errors.

Abstract: The thermal deformation of ram system in a heavy-duty CNC milling-boring machine tool has a serious effect on its accurateness. This paper analyses quantificationally the temperature field and deformation field of the ram system, and gives the ram’s heat sources, calculating quantity of heat and transferring type of heat. And then a finite element analysis is performed, the analyzing results provide basic theoretical data for thermal error compensation in machine tools.

Abstract: Thermal error of machine tool is the main in total machine tool error, and obviously impairs the accuracy of the machined workpieces. Ram is a very important component of heavy-duty floor type boring-milling machine, and its thermal deformation is a significant source causing errors in machining process. Aiming at the thermal elongation of heavy type milling boring machine tool ram, the machine tool thermal errors are measured and compensated. Temperature compensation function in NC system is applied. Experiment results shows that 90% ram positioning error can be compensated.

Abstract: Synthetic error of CNC machine tool, mainly including geometric error and thermal error, is generally affected by many factors. And temperatures that include environment temperature and temperature asymmetry of machine tool are most important factor. Aiming at geometric error and thermal error mainly, this paper proposed a real-time synthetic error compensation solution for CNC machine tool based on Differential Resolver Function (DRF). The principle of this solution is offsetting the origin of workpiece coordinate system when implementing the NC code in machine tool. After real-timely collecting machine tool coordinates position and thermal key points’ temperatures, synthetic errors are calculated by the synthetic model that is beforehand constructed and stored in compensation equipment, and then the pulses that represent coordinate system origin offsetting value are generated and sent into NC system by DRF to realize synthetic error compensation of CNC machine tool.

Abstract: One of the difficult issues in thermal error modeling is to select appropriate temperature variables. In this paper, two selection strategies are introduced to overcome this difficulty. After measuring the temperatures and thermal errors of a heavy-duty CNC milling-boring machine tool by a laser tracker, four temperature variables which are the foundation of thermal error modeling are selected for each feed axis from fifteen temperature variables according to major factor strategy and non-interrelated strategy.

Abstract: It is inefficient and complicate to detect geometric errors of a heavy machine tool with large scale dimensions by using traditional laser interferometer. With the development of the laser tracker convenient for measuring large scale dimension, the accuracy of the laser tracker can meet the accuracy requirements for geometric error measurement of heavy machine tools. In this paper a method of using laser tracker for detecting and identifying the error of a heavy NC boring and milling machine tool is introduced. The measuring experiment demonstrates that this new method can improve the measurement efficiency.