High-grade Cnc Machine Screw Bearing Thermal Characteristics Analysis And Experiment Design

With the development of machine tools to high-precision and high-speed, the thermal deformation has significant effects on machining accuracy. The rolling bearing supporting ball screw is essential to machine tools, and it’s also the important heating source of machine tools. So it’s very important to study the thermal characteristics of bearing for the design and optimization of machine tools. In this paper, the thermal characteristics of the angular contact ball bearing with contact angular60°was studied.The quasi static state of angular contact ball bearing was modeled. The movement and friction of bearing under the influence of axial forces and speeds were analyzed. On the basis, the intensity heating source of bearing inner ring, bearing outer ring and balls were calculated.On the basis of analyzing the heat transfer theory, finite element model and heat transfer model with thermal contact resistance were created. Owing to the ANSYS finite element method, the temperature field was computed with thermal contact resistance, which was compared with that without thermal contact resistance. The law how the thermal contact resistance effected on bearing temperature field was obtained. The expressions of calculating thermal preload under the condition of axial position preload were formulated. The variation of the biggest contact press and static stiffness under the condition of the influence of thermal preload were calculated.The test-bed testing thermal characteristic was designed with characteristics of simple structure and universal. This test-bed mainly considered the influence of axial forces and speeds, which could test various types of bearing. It also could test the temperature of inner ring, outer ring, shaft and bearing housing at the same time. A new way to obtain thermal contact resistance was proposed, which combined experiments with finite element method. It could recognize the thermal contact resistance among bearing, shaft and bearing housing. Compared with previous methods, the method had the advantages of high accuracy and easy manipulation.