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When to Use the Cold Heading Process

As a professional machining manufacturer, we use the most appropriate machining process to precision machine products and reduce customers' purchasing costs and production time. Precision casting, forging, and profile machining are all very common. In addition cold heading, oil extrusion and other processes are also often used. The following is an introduction to the cold heading process and when it is used.

The use of molds at room temperature on the metal bar upsetting (often local upsetting) shaping of the forging method. Usually used to make the head of screws, bolts, rivets, etc.. Can reduce or replace the cutting process.

Forging billet material can be copper, aluminum, carbon steel, alloy steel, stainless steel and titanium alloy, etc., the material utilization rate can reach 80 ~ 90%. Cold heading is mostly carried out on special cold heading machine, which is convenient to realize continuous, multi-station and automatic production. On the cold heading machine, it can sequentially complete the process of cutting material, heading, accumulating, forming, chamfering, thread rolling, shrinking and trimming. The production efficiency is high, it can reach more than 300 pieces/min, and the maximum diameter of the cold heading workpiece is 48mm. The bar is automatically fed into a certain degree by the feeder, cut off into blanks by the cutter, and then sent to the accumulating and punching station for cold heading by the clamping conveyor in turn.

This technology belongs to a kind of cold forming, which is the processing way of punching, shearing, bending, stretching and so on to the material without heating. Cold forming processes include cold heading, cold rolling and die forging.

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The main advantages of cold forming steel structure:

1, compared with thicker hot rolled steel sections, cold formed steel can be processed to apply smaller loads and shorter spans.

2, through the cold forming process can be economically obtained unusual cross-sectional shape, to obtain a satisfactory strength-to-weight ratio.

3、Considering the compact type for packing and transportation, nestable sections can be produced.

4、No expansion or deformation under environmental gravity.

Cold heading process for mass production of automotive fasteners, motorcycles, bicycles, home appliances on the automated production of shaped is essential to the manufacturing method, with the cutting process can work compared to the metal fibers (metal flow line) along the shape of the product is a continuous shape, grain without disconnecting, and thus improve the strength of the product, especially excellent mechanical properties, and saves raw materials.

Along with the environmental protection calls for more and more high, fasteners also more and more attention to environmental issues. Therefore, for the cold heading process for mass production of automotive fasteners, motorcycles, bicycles, home appliances on the automated production of shaped is essential to the manufacturing method, compared with the cutting process, metal fibers (metal flow line) along the shape of the product is a continuous shape, grain without disconnecting, and thus improve the strength of the product, in particular, excellent mechanical properties, and save raw materials.

With the growing call for environmental protection, fasteners are also more and more attention to environmental issues. Therefore, the cold heading technology as a non-cutting molding is more and more in pursuit of high strength and high value-added.

Recently, the development trend of cold heading and cold extrusion composite technology.

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1、Constrained stamping

The distance between the shape and the edge of the hole is less than the thickness of the punch, the inner diameter is more than one-half of the outer diameter, and the height is more than 1.5 times of the inner diameter of the punch, and the effect of constrained punching is better. Since the distance between the shape and the edge of the hole is relatively close, the force of the punching needle affects the shape and causes the dimensions of the shape to change. In order to prevent changes in the dimensions of the profile, it is necessary to keep this part of the profile in a constrained state. Due to the action of the constraint force, the stamping part is in the state of compressive stress, in this state of punching compressive stress, take the appropriate gap can get all the bright strip stamping effect.

2、Cutting and squeezing molding

Usually, the head of the bolt is formed by cold heading plastic processing, and the cutting and squeezing forming process has more advantages than the rising process. Before cutting and squeezing forming, the blank must be shaped, through shaping can be obtained in line with the process requirements of the blank. The size of the blank must be emphasized, and the shape of the blank before extrusion should be determined according to the situation of the parts, and the shape of the blank is conducive to the flow of material. If the blank size is too large, that is, too large a margin for cutting and squeezing, the need for cutting and squeezing force is larger, easy to cause the cut and squeeze the mold life is reduced, the possibility of accidental damage to the mold to increase, and the consumption of raw materials; cutting and squeezing the margin is too small, cutting and squeezing the part is easy to fall off the corner, the shape of the incomplete, do not get the satisfaction of the appearance of the quality.

Mold structure focuses on the design of the cutting and squeezing film, processing, the edge of the working size of the best control in the middle and lower limits, the angle of the cutting and squeezing die to be appropriate, the edge must be ground, polished, roughness Ra0.025 to Ra0.050μm, with the highest life expectancy.

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3、Drawing and forging forming

Cold extrusion of raised thick-walled parts and deep-drawing forming of cup-shaped shaped parts into one, to plate as a material, the use of deep-drawing and compression of the composite molding method and the formation of fasteners, the molding characteristics of the head of the formation of the raised and increased wall thickness.

4、Localized forming

There are two concepts of upsetting, one is the whole upsetting, that is, the end face of the whole product has the effect of force; the second is the local upsetting, that is, only in the necessary part of the effect of pressure. The whole forming, due to the processing area is large, forming load is high, need large tonnage press, for local forming, can use lower load to get the necessary plate thickness change, in the hole, groove forming is very widely used.

①Step parts

joints as an example to illustrate the main points of forming and application, engineering design: according to the design drawing machining - annealing - phosphorus saponification - extrusion (semi-closed extrusion and forming steps).

②Microfabrication

Out of the locking and chip removal needs, some of the fastening screws have 1 ~ 3 scraping groove processing, extrusion process can be used, representative of the automotive combination of bolts scraping groove molding.

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