The bolt threads are generally cold worked so that the thread blanks within a certain diameter range pass through the twisting plate and the threads are formed by the pressure of the wire. The plastic flow line of the threaded portion can be obtained without being cut, the strength is increased, the precision is high, and the product of uniform quality is widely used.
In order to produce the outer diameter of the thread of the final product, the required blank diameter is different because it is limited by factors such as the accuracy of the thread and the presence or absence of plating of the material. Rolling thread refers to a processing method in which a thread is formed by plastic deformation. It is a rolling (twisting plate) mold with the same pitch and shape as the thread being machined, and the cylindrical blank is squeezed while rotating the screw blank, and finally the tooth shape on the rolling mold is transferred to On the screw blank, the thread is formed.
The common point of rolling thread processing is that the number of rolling revolutions does not have to be too much. If it is too much, the efficiency is low, and the surface of the thread is prone to separation or disorder. On the other hand, if the number of revolutions is too small, the diameter of the thread is easily rounded, and the initial pressure during the rolling is abnormally increased, resulting in a shortened life of the mold.
Common defects in rolling threads: surface cracks or scratches on the threaded part; chaotic buckle; the thread part is out of round. If these defects occur in large quantities, they will be discovered during the processing stage. If the number of occurrences is small, the production process will not notice that these defects will flow to the user, causing trouble. Therefore, the key issues of processing conditions should be summarized and these key factors controlled in the production process.