HEADING PUNCHES FOR COLD HEADING MACHINES
FIRST PUNCH - PRELIMINARY FOR SCREWS AND SELF-TAPPING SCREWS
The preliminary punch - the punch of the first impact is used to push the cut workpiece into the matrix and prepare the workpiece for final upsetting. The function of the first punch is the formation of a set of conical metal in the die, while the main task is to pre-fill it before the formation of the head.
The constructive performance of the first punches, their location on the die mirror can be different and is determined by the design of the parts.
When landing the pins on a two-impact press machine, the first impact with the help of a punch pushes the workpiece into the die, centers it, protecting it from buckling and prepares it for the second impact with the final (second) punch, which performs the bulk of the work.
Depending on the complexity of the shape of the head of the rod product, one or more preliminary punches are required. Accordingly, you will need a two-stroke single-position automatic machine or a multi-position automatic machine.
During operation, the punches are subjected to high power loads. Therefore, punches for cold heading processes are made of high-strength steels with increased hardenability, which have certain mechanical properties that contribute to an increase in resistance.
In most cases it is tungsten carbide, alloy steel, uncoated. For punches, toughness, compressive strength and hardness are key indicators.