发布时间：2021-04-01 10:58:38 来源：http://www.jnskdj.com 作者：骏豪 浏览量：
Compared with the imported tap, the cold kneading imported tap has many advantages in processing soft data (≤ HRC35) threaded hole. Because cold kneading forming tapping is kneading rather than cutting data, chip will not occur when kneading imported tap. Compared with the cut thread, the cold kneading thread has higher external tensile strength, bending strength and shear strength. The higher strength comes from the mechanism of thread formation, which is formed by permanent plastic deformation of workpiece data.
The service life of cold kneading tap is generally longer than that of cutting tap, because cold kneading tap has no sharp cutting edge which is easily and rapidly worn. The cold kneading forming tap can also process thread with larger length diameter ratio than the cutting tap. In addition, compared with the cutting tap, the thread size produced by cold kneading tap generally has better consistency.
However, in order to achieve this scale consistency, we need to pay a certain value. In cold kneading forming tapping, it is necessary to process more precise center hole. The success of cold kneading tapping depends on the diameter of the central hole, which is generally smaller than that of tapping with a cutting tap. The error of one unit of aperture scale may cause the error of four units of thread scale. Therefore, before cold kneading tapping, it may be necessary to ream the center hole.
If the center hole size is too large, there will be no enough data for cold kneading forming tap to knead the correct size of thread. If the center hole ruler is too small, the cold kneading tap will have to squeeze more information to form the thread, and then the tap will wear too fast. In addition, in order to form each thread, it is necessary to squeeze more information when processing coarse thread. The more information kneaded, the more possibility of cold work hardening. Stainless steel, titanium alloy and nickel base alloy are all prone to cold work hardening. Therefore, these data may shorten the life of tap or cause tap fracture.
The thread holes on hard data can also be processed by thread milling cutter. Generally speaking, there is no big problem in processing high hardness data with carbide thread milling cutter. Thread milling can better control the tool feed rate. In addition, thread milling is generally a safe way to process thread holes on hard data. Especially, once the thread milling cutter is broken in the thread hole, it is very simple to adopt the rescue method. Once the cutting tap is broken in the screw hole, it is much more difficult to take out the broken tap from the hole and rescue the general valuable workpiece, sometimes even completely impossible. Therefore, in the mold manufacturing industry and aviation industry, thread milling is generally the preferred method for processing threaded holes on hard materials.
In addition, in thread milling, the manufacturer can control the thread size more easily. Thread milling cutter is processed by spiral interpolation (including the movement of X, y and Z axes of CNC machine tool). When the thread milling cutter is worn, the spiral interpolation of the cutter can be compensated by the machine tool programming, and then the dimension of the processed thread can always meet the specification requirements. However, compared with thread tapping, the processing cost of thread milling may be higher, so it is necessary to consider this point when selecting the processing technology.