Assembly method for two symmetrical bolt-bearing joints based on the tightening model and angle-eccentricity relationship

This paper focused on the assembly of two symmetrically distributed bolt-bearing joints, both the single bolt tightening control and two bolts adjusting were studied. An improved assembly method for two annular parts connected by these two bolt-bearing joints was proposed to improve the tightening quality of these joints and the eccentricity between these two annular parts. First, the tightening process of single bolt-bearing joint was analyzed, and the mathematical model of the tightening process was established. Then, aiming to improve the tightening quality, an improved tightening control method for single bolt-bearing joint was proposed based on the mathematical model. Finally, the angle-eccentricity relationship was studied, and the eccentricity adjustment strategy based on the inverse sequence method was presented for adjusting the eccentricity between two connected parts. Considering that the measurement of the bearing preload is not convenient, the eccentricity was measured for indirectly reflecting the preload. The tightening experiments verified that the scatter of preload was obviously reduced under the improved tightening control method. The results of eccentricity adjustment experiments indicate that the eccentricity reduce gradually during the loosening and tightening process, and the eccentricity is less than 3.4 μm after adjustment process, which enough to meet the assembly requirements of the target groupware.