What are the benefits of cold forging? Fastener cold forging forming process analysis

Why cold forging?

Cold forging of fasteners can improve the mechanical properties, maintain the integrity of the metal fiber structure, increase the utilization rate of materials, and reduce the labor intensity of workers.

The basic concept of cold forging

Metal is upsetting at room temperature to complete the plastic deformation of the metal by means of the die, and hit the specified geometric shape, size and quality requirements. This process is cold forging

Deformation degree of cold forging and upsetting force

The ratio of the difference between the original height of the upsetting part of the blank and the height after the upsetting to the original height, or the ratio of the increase of the interface agent after the upsetting of the blank to the cross-sectional area after the upsetting, including the upsetting and extrusion Two variants.

Upsetting is the degree of axial deformation expressed by the pressing rate, and the degree of radial deformation during extrusion is expressed by the reduction of area. Upsetting force is the main basis for determining process parameters, designing molds, designing cold forging machines and selecting special equipment.

There are many factors that determine the size of the upsetting force, mainly in the following aspects: (Guide: What are the common types of fasteners?)

Mechanical properties of metal, degree of deformation of workpiece shape, friction, mold shape

Commonly used calculation formula for cold forging upsetting force

Main equipment and characteristics of cold forging process

One-die two-stroke cold forging machine: mainly used for small head deformation, simple products, relatively low cost, and high production efficiency. Common such as: rivets, countersunk screws, slotted screws.

Two-die three-stroke cold forging machine: mainly used for large deformation of the head, short rod, and multi-step special-shaped parts.

Three-die three-stroke cold forging machine: mainly used for hexagon head bolts, cylindrical head hexagon socket bolts, and relatively simple products.

Two-die four-stroke cold forging machine: mainly used for large deformation of the head, short rod, and multi-step special-shaped parts.

Four-die four-stroke cold forging machine, five-die five-stroke cold forging machine, six-die six-stroke cold forging machine: mainly used for products with large head deformation and more complex special-shaped parts.

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