Analysis And Research On Thermal Characteristics Of The Milling-turning Compound Machining Center

With the development of science and technology, modern mechanical products have more requirements for the structure and performance of mechanical parts, which demand that the machine tool have more processing capacity and precision. Precision machining technology has become an indispensable part of the modern machinery manufacturing technology, while the factor of restrict processing precision is the variety of error of the machine in which the error caused by thermal deformation has become the main error.This paper, taking the XCM1600machining center as the research object, analyzes the heat source distribution and heat transfer mechanisms and calculates heat generation intensity of the main heat source and heat transfer coefficient of the machining center on the basis of analyzing domestic and international research on thermal characteristics of machine tool. By using the finite element software ANSYS Workbench to simulate the temperature field and thermal deformation of the machining center, calculating the degree of the influence parts’thermal deformation exert upon thermal drift of using thermal information chain. The temperature measuring points were optimized and thermal error prediction model of Z direction of spindle were established. At the same time, the error compensation control strategy were presented. The contents and the problem were solved as follows:1. First, on the basis of researching on structural performance and key technologies about thermal characteristics of XCM1600machine center, the heat distribution and heat transfer mechanism were analyzed, the heat transfer process of the machine were analyzed in the condition of the spindle system as an example. Heat generation intensity of the main heat source which include motors, bearings, screw nut and guide and heat transfer coefficients of parts of the machining center were calculated.2. The simplified three-dimensional model of machining center were established with Pro/Engineer software in the condition of ensuring the original assembly relation. Under the assumption that the environment temperature is20℃, the steady-state temperature field and thermal deformation field of machining center were simulated with finite element software ANSYS Workbench. The steady-state temperature field and thermal deformation field of the spindle system were analyzed in comprehensively. 3. The degree of the influence parts’ thermal deformation exert upon spindle thermal drift in three directions were calculated by using thermal information chain. Results show that the spindle system and turret system have a big influence on spindle thermal drift where the spindle system have greatest impact on the axial thermal drift and the turret systems have greatest impact on the radial thermal drift.4. The temperature measuring points were optimized by the method that combine fuzzy clustering analysis with multiple correlation coefficient. The result is the measuring point were decreased from the initial16to5points under the circumstances of meeting the accuracy.5. The thermal error prediction model of spindle Z direction were established by Fuzzy neural network algorithm. The simulate results show that the maximum predicted error of the model is1.72μm. Processing accuracy of machine center will be significantly improved by using this thermal error compensate model and the error compensation control strategy were presented.