Cold heading process is increasingly widely used in mechanical manufacturing, especially in the production of standard fasteners, due to its high productivity, good product quality, significant reduction in material consumption, lowering production costs and improving working conditions. Among them, the most representative products produced by multi-station cold heading machines are bolts, screws and nuts.
Cold heading is carried out at room temperature. Cold heading can improve the mechanical properties of metal parts. The following table shows the comparison of mechanical strength between cold-heading bolts and machined bolts:
As can be seen from the table, regardless of the specification of the bolts, the tensile strength after cold heading processing is about 10% higher than that after cutting processing, and in some cases, it can even be increased by 20%. This is because the metal fibers of cold heading processed products are not cut, the internal structure of the metal is compacted, and the existence of work hardening phenomenon occurs, so the mechanical properties of the metal are improved.
2. Cold heading process can improve the utilization rate of materials. Take cold-heading bolts as an example. The new process "concave" hexagonal head bolts can achieve a material utilization rate of over 99%. Apart from the loss of the head and tail of the material, it has achieved complete no-cutting processing. If cutting processing is used, the material utilization rate is only 40%. The material utilization rate of cold-heading nuts can also reach about 80%, while that of machined nuts is only 54%.
3. The cold heading process can significantly enhance productivity. Compared with the original cutting process, the production rate of cold heading nuts is approximately 25 to 30 times higher.
4. Due to the adoption of multi-station cold heading machines, all processes can be processed simultaneously on one machine tool, thereby reducing equipment investment, the production space occupied by the equipment, and the transportation of semi-finished products between processes. In particular, it has alleviated the labor intensity of workers and improved working conditions.
5. Cold heading process can enhance the surface finish of products and ensure their accuracy. The general finish can reach V5, and for special requirements, it can reach V6. For mass production of bolts, nuts, etc., their accuracy can be fully guaranteed.
Cold heading process is one of the new metal pressure processing processes with little or no cutting. It is a processing method that utilizes the plastic deformation of metals under the action of external forces and, with the aid of molds, redistributes and transfers the volume of metals to form the required parts or blanks. Cold heading process is most suitable for the production of standard fasteners such as bolts, screws, nuts, rivets and pins.
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