Process: Wire pickling-Annealing (depending on the type of fasteners used, the wire is also drawn directly)-Pickling (washed oxide scales, etc.)–Drawing line-Forming on cold heading machine–Rolling On-machine rolling of teeth — heat treatment (generally 6.8 and nuts below 8 are generally not heat-treated) — plating (according to customer needs)-packaging-shipping
Cold heading: It is to use the plasticity of the metal to apply pressure or cold drawing with cold mechanics to achieve the purpose of solid deformation of the metal. (Basic definition)
The method of forging the top of the bar or wire at room temperature by thickening. Cold heading is mainly used to manufacture bolts, nuts, iron nails, rivets and steel balls. The forging material can be copper, aluminum, carbon steel, alloy steel, stainless steel and titanium alloy, etc., and the material utilization rate can reach 80 to 90%. Cold heading is mostly carried out on a dedicated cold heading machine, which is convenient for continuous, multi-station and automated production. On the cold heading machine, it can complete the processes of material cutting, heading, accumulation, forming, chamfering, thread rolling, diameter reduction and trimming. The production efficiency is high, which can reach more than 300 pieces / min, and the diameter of the largest cold heading workpiece is 48 mm. The schematic diagram of cold heading bolt process is a typical process of cold heading bolt. The multi-station nut automatic cold heading machine is a multi-station nut automatic cold heading machine. The bar material is automatically fed into a certain length by the feeding mechanism, and the cutting mechanism cuts it into a blank, and then is sent to the accumulation pressure forming and punching station by the clamp conveying mechanism for forming.
Cold heading means that the raw material is stamped at room temperature, and hot heading means that the raw material is stamped after being heated. There is no special requirement for the specific use. Generally, cold heading is required because of such surface finish and material organization The ingredients will be more compact, and the larger workpieces are often processed by hot upsetting.
Forged head, also called hot pier, heats the head and burns red, extruded;
Most of them come out because it saves materials. Depending on the tonnage size and bolt diameter of the pier forging machine, cold pier or hot pier technology can be used.
Small batches of special or special bolt hex heads are milled after turning.
Single piece of small batch can use die threading, lathe thread picking, cyclone milling and other methods.
In mass production, the methods of thread rolling and thread rolling are often used, and the efficiency is very high. Because the bolt rod forming method has cold drawing and diameter reduction, the diameter of the unthreaded part of this bolt is not necessarily slightly smaller. When using cold drawing, it is slightly smaller; when using reduced diameter, it can be the same diameter or slightly larger than the thread.
Bolt material is aluminum alloy, zinc alloy, copper alloy and other low-melting alloys or metals, and die casting method can also be used. Steel is not made by die casting.
Forming of the hexagonal head of the bolt: there are cold pier, hot pier, the product is directly produced after upsetting, some are machined after upsetting, and all are machined.
Upset bolt heads have machining marks, and there are mold fixture marks at the root.
The thread of the bolt is mechanically threaded, which is similar to the manual die. There is a machine tool turning system, and a large diameter bolt turning system works. There are also "thread rolling", which uses the "thread rolling machine" to extrude the thread with the "thread rolling plate". The diameter of the non-threaded part of this bolt is slightly smaller.
Light bolt (cold upsetting) and wool bolt (hot hitting).
The cold heading is mainly to take the lead after pulling the wire, and to die. · As the name implies, coldness is to screw at normal temperature.
There are also hot hits, also called red hits. This is because big bolts are hit with red only, after heating the material and hitting.
The surface of cold-headed bolts is pretty, and the surface of the red bolts has oxide scale, which is not good.
Screw inspection mainly inspects its external dimensions, thread accuracy, and whether there are any cracks. This is required to use a flaw detector and a mirror image.
The production of ordinary screws is divided into two processes, the first is the punch, that is, the head of the screw is now punched out of the wire, and the wire is cut. The second is thread rolling, that is, on the basis of the previous process, two files are used to set the thread out.
Link to this article：Fastener Production Process Details
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