Roll forming method

The plastic forming method of producing bolts or screws using thread rolling dies (thread rolling dies) is called thread rolling. The general production method is as follows: the thread pitch of the die cavity is the same as the product. Two dies are positioned so that the blank is positioned opposite each other. Through the relative movement or rolling motion of the dies, the blank clamped in the forming area is plastically deformed during rotation, gradually filling the die cavity and forming a male thread.

The blank is processed at room temperature. Thread rolling with a thread rolling die is a traditional processing method, suitable for processing threads with smaller diameters. The movable thread rolling die moves reciprocating linearly relative to the fixed thread rolling die, and is inserted into the die cavity and rolled 5-6 times to form a thread.

The advantage of this method is that feeding and unloading are relatively convenient, but the efficiency is relatively low (the output of small-diameter threads is about 150 pieces/min, and the output of larger bolts with a diameter not exceeding 25mm is 30-40 pieces/min). Using the combined thread rolling die shown in the table below, the thread rolling method between a rotating cylindrical die and a stationary combined die avoids idle strokes and improves production efficiency. When producing threads with a diameter of 36mm, the output can reach 400~600 pieces/min.