| Thread connection is the primary connection mode of mechanical product, which has good maneuverability and simple structure. The thread connection of large size is widely used in petrochemical, aeronautics, astronautics, military industry, etc. A kind of thin-walled shell production with large size thread connection is assembled by belting clamping mechanism. When assembly, slipping often occurs as the belt clamping force is too small; while if the clamping force is too large, thread is difficult to screwed in, even stuck. Thus it cannot reach preset pre-tightening force. Moreover, belt clamping force has a great effect on the efficiency and quality of the assembly.Therefore, with thin-walled big thread as the research object, the clamping force control in the process of assembly is studied deeply. The approximate calculation formula of the belting critical friction torque is derived from theoretical analysis of the stress relationship in the assembly process.Mechanical model of the assembly process of threaded is established, and the law of effect of radial load on the thread friction is settled, which provides a theoretical basis for the numerical simulation.Finite element model of thin-walled big thread connection structure is established. The relationship between the belting clamping force, the belting critical friction, the thread critical friction is solved. The reasonable value range of clamping force is analyzed.The belting critical friction and thread critical friction under different clamping force have been obtained through experiment. The model is verified by comparing the experimental results with simulation results.Through these research, we have a more clearly understand about the relationship between belt clamping force and the mechanical properties of thin-walled large thread, and get a reasonable value range for clamping force. Our research has a significant guide for the improvement on the assembly process and tools about the thin-walled large size thread.
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