Tapping simulation to reduce radial pitch diameter difference of threads

The internal thread is the most important part of the components. Any processing failure or reduction in precision cannot achieve the perfect assembly of the components without gaps. As a vital parameter to evaluate the quality of internal threads, radial pitch diameter difference has a great influence on the processing quality of internal threads. When matched with qualified external threads, radial pitch diameter difference exceeds the allowable value of the internal thread, the life and reliability of the threaded connection will be reduced, and the threaded connection may fail completely and even cause huge economic losses. Unfortunately, there are few reports on the research of radial pitch diameter difference in the past. In actual production, due to the harsh conditions of the tapping process, it is difficult to accurately control radial pitch diameter difference of threads, which results in that the quality of small-diameter internal threads cannot be guaranteed. Therefore, this paper developed a quasi-static model to predict radial pitch diameter difference in tapping and simulates radial pitch diameter difference at different chamfer lengths and spindle speeds through this model. The simulation results show that the chamfer length and spindle speed have an effect on radial pitch diameter difference. It is the smallest at 2 pitches and 1400 rev/min, which are 1.4 mm and 1.8 mm, respectively. In a word, tapping simulation not only determines the influencing factors of radial pitch diameter difference, but also reduces test costs, laying a solid foundation for the further experimental research.