Due to the influence of taper error of tubing thread, the basic hand tightness gap between the inner thread and the outer thread or between the inner thread and the outer thread is 0.076mm, which increases to less than 0.0124 mm.
The main reasons for the large taper error in processing tubing threads are as follows:
Machine tool errors are mainly caused by transmission errors of NC lathe and uneven wear of guide rail of model lathe.
Profiling error, including the errors caused by profiling manufacturing accuracy, the rigidity of profiling frame, profiling adjustment and profiling wear;
The inappropriate processing methods mainly include the errors caused by the lack of rough and fine turning, the large cutting depth, the elastic deformation of the die and the tool yielding of the workpiece, and the inadequate rigidity of the workpiece, resulting in the process tool yielding, the starting position of the thread sparse tool close to the workpiece, etc.