Manufacturing Of Bolts

As one of the leading suppliers in the fastener industry, Shuifu Hanyang

Machinery Technology Co., Ltd. is well versed in every step and aspect

of bolt production. Yang Min, the technical manager of Shuifu Hanyang

Machinery Technology Co., Ltd. factory, said, "We do not produce

catalog parts - everything we produce is designed according to

customer requirements. There are multiple different options for

producing suitable bolts, depending on where the fasteners are used

Cold heading process

Generally speaking, cold forging is a combination of multiple processes

to obtain the final shape of the part. Figure 2 is an example of cold

forging. After cutting the billet, it is composed of a combination of shaft

forward extrusion, cup reverse extrusion, cup forward extrusion,

upsetting, punching, and tube forward extrusion.

Splitting into multiple processing steps is to avoid excessive pressure

during a single forming process. Reducing forming pressure and

minimizing the number of processes is the key to process design, as

fewer processes result in lower costs

upsetting

Figure 3a shows the free upsetting of the outer surface without being

constrained by the mold. The processing pressure increases with

frictional constraint. When the height H of the billet is greater than the

diameter D0 (H/D0>1.0) during deformation, C=about 1.2. However,

when the billet becomes thinner, C will rise to about 2.5.

When the compression rate increases, as shown in Figure 4, cracks will

occur in the oblique and longitudinal directions on the outer

circumferential surface. The occurrence of cracks depends on the

ductility of the material, which requires the use of materials specially

manufactured for cold forging. As the reduction rate increases, Figure 3

shows the magnitude of the constraint coefficients for various upsetting

forming processes.