Research And Optimization Of Bolt Assembly Stress For Machine Tool Based On The Kriging Model

Bolt assembly of machine tool is an important part of machine tool manufacturing. Assembly quality will affect the performance of the machine tool directly. At present there is no systematic and definite study on the evaluation of the quality of bolt assembly. The assembly quality depends on the assembly experience of the manufacturers, thus the assembly quality is difficult to maintain stability. In this paper, we study at start with the assembly stress generated in the process of bolt assembly, by means of experimental testing and modeling analysis, study the influence of assembly stress state and dynamic strain and vibration of machine tool. Put forward an assembly quality evaluation method and assembly process based on assembly stress test- data analysis- modeling optimization, this method has a certain reference value for the improvement of assembly quality and achievement of excellent assembly.This paper firstly introduces the current situation of the domestic machine tool manufacturing, shortcomings of domestic machine tools are summarized. On the basis of summarizing the previous studies, a method for analyzing the assembly quality of machine tools by assembly stress test is proposed.Based on the line track sliding table- working platform bolt assembly of an experimental platform as the research object, the assembly stress state was studied by means of experimental test. The experimental results show that if all the bolts were assembled with the same recommended torque, the assembly stress on each slide seat shows great difference.And then experiments were designed to research the single bolt assembly state of stress. The results show that the roughness has great influence on the stress characteristics of bolt assembly,that with the increase of roughness, the compressive strain of bolt assembly along the direction of the bolt is gradually increased. This also proves to a certain extent that the inhomogeneity of assembly stress state among line track sliding tables is reasonable and universal.On the basis of the above research, in this paper, we aimed at the sliding block-working platform bolt assembly, 39 different assembly stress states were designed, dynamic strain and vibration were tested in each assembly stress state. Based on the experimental data, the Kriging model was established, the influence of assembly stress state on dynamic strain and vibration performance is analyzed with the model. On the basis of this, a method for evaluating the quality of assembly is formed.Besides, on the basis of ensuring the accuracy of the model, in order to improve the performance of dynamic strain, the assembly parameter was optimized. The optimization results were compared with the traditional assembly process, showing that the relative indexes of dynamic strain were greatly improved. A assembling quality evaluation method and assembling method is proposed based on this result. This result has a certain reference value for the improvement of assembly quality and achievement of excellent assembly.