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1. Introduction
The cold heading process, also known as the cold forming process, is an essential step in screw making, which refers to forging the blank into a certain shape of screw head: it begins with a slug cut from a progressive coil or wire, then a series of strong hammers and dies to form the screw head.
The screw header punch and the cold heading die are used to force the end of the blank into the desired shape: Generally, there are two header punches; the punch of the first impact is used to push the workpiece into the matrix for the final upsetting, and the second punch (second blow) is used for the final forging.
Both the header punches are equipped on the moving part of the machine, contained in the punch casings; while the cold heading die is fixed to support the metal blank. Compared with the cold heading die, the screw header punches are smaller but made of high-strength steel with increased hardenability, such as tungsten carbide, alloy steel, etc. As in the cold heading process, the header punches encounter and experience great loading, the strength of the material is important for the cold heading.
2. Specifications
Lituo offers header punches for different shapes of the head and heading slots of the screws. We mainly offer finishing punches according to the Cross, Pozi (Star punch) standards for hexagonal, square, and slotted heads. It’s worth mentioning that we also offer special punches on customers’ drawings for heading heads of non-standard hardware.
The main specifications of the screw header punches are the following:
3. Applications
According to the types of head and recess of the screw, there could be multiple punches. Generally, the two-impact press machine is the most popular type. In this case, there are at least two screw header punches.
First Punch (First Impact)—The first header punch is used to push the workpiece into the die, centers it, protecting the workpiece from buckling, and prepares it for the second punch ( final punch)
Second Punch (Second Impact)—The second screw punch is used for the final forging of the screw head. Usually, it’s smaller than the first screw header punch.
4. Advantages
Lituo offers a great variety of screw header punches to forge screw heads and recesses of different shapes, such as Star punch, etc.
The advantages of our screw header punches are the following:
Compressive strength and hardness—Our screw header punches are mainly made of tungsten carbide, alloy steel, etc. The toughness, compressive strength, and hardness of the header punches are key indicators in the cold heading process.
High precision—Our screw header punches are designed with high precision and accuracy.
High compatibility with cold heading machines—We offer header punches in different sizes, suitable for different types of cold heading machines. Besides, we can also implement header punches according to the customer’s drawings.
