Machine Tool Feed System Angular Contact Ball Bearing Dynamic Parameters Experimental And Theoretical Analysis

To meet various cutting requirements of different material, the spindle and the feed systems of machine tool should have good dynamic characteristics. Regarded as commonly supporting parts of machine tool, dynamic characteristics of angular contact ball bearings were the weak links in the spindle and the feed systems, which would directly affected the overall dynamic performance. So the study on the dynamic characteristics of angular contact ball bearings played an important role. In the applications, common dynamic parameters of bearings mainly consisted of dynamic stiffness and damping in the axial and radial directions.Firstly, in the paper, the assignment formulae about the stiffness and damping value of bearings radial equivalent unit was deduced based on the Sjovas load integral formulae, and the determination of bearings axial equivalent unit was also proposed. Compared with the experimental results, it showed that the modeling approach could accurately analyze the bearings dynamic parameters.Secondly, a single DOF dynamic model of bearing which considered foundation (bearings sleeve) responses was proposed to identify the bearings dynamic parameters, and then the formulae were deduced to calculate the bearings dynamic parameters. Based on the theoretical model of LEVY modal identification, the program was written by the software MatLab to identify the bearings dynamic parameters. The comparison of experimental and fitted curves indicated that the identification method was of high accuracy.Thirdly, based on a large number of modal experiments, the effects of bearings dynamic parameters were analyzed under different load cases. The comparison among different bearings under different axial load cases about dynamic stiffness and damping showed that the number and diameter of ball played a positively significant role to dynamic stiffness and damping of bearings.Finally, the simplified mathematical model of bearings dynamic stiffness was established in the paper, the quadratic interpolation particle swarm optimization algorithm was proposed to solve the model, and then the corresponding program was written. Taking type bearings NSK50TAC100A as example, the effects of bearings speed about dynamic stiffness were calculated and analyzed under different load cases.