Hot push forming process for stainless steel elbow

What is the hot push forming process for stainless steel elbow?

The stainless steel elbow hot push forming process uses a special elbow pushing machine, a core mold and a heating device, so that the blank placed on the mold moves forward under the push of the pusher, is heated, expanded, and bent during the movement. The process of forming. The deformation characteristic of the hot thrust of stainless steel elbow is to determine the diameter of the blank according to the law of the volume change before and after plastic deformation of the metal material. The diameter of the blank used is smaller than the diameter of the elbow, and the deformation process of the blank is controlled by the core mold to make the inner arc The flow of the compressed metal compensates for other portions that are thinned by the expansion of the diameter, thereby obtaining an elbow having a uniform wall thickness.
The heating process of the forming process is medium frequency or high frequency induction heating (the heating coil can be multi-turn or single-turn), the flame and the reverberatory furnace are heated, and the heating method is determined according to the forming product requirements and energy conditions.

1 Stainless steel elbow manufacturing process

Hot push

The hot push stainless steel elbow adopts a section of stainless steel pipe to push an elbow. The manufacturing process is as follows:

20181022073946 69457 - Hot push forming process for stainless steel elbow
Preparation process (pushing process, blank drawing) → unloading (with sawing machine) → inner wall lubrication of tube blank (deburring) → feeding → hot toughening → shaping (using press, integral tire) → scribing + cutting → Heat treatment (if necessary) → Water pressure test (when required) → Pipe end groove → Dimensional inspection → Nondestructive testing → Finished product storage. The stainless steel elbow heat treatment and hydrostatic test procedure can be determined according to the actual performance requirements of the stainless steel elbow.

2 Characteristics of stainless steel elbow

The stainless steel elbow hot push forming process has the characteristics of beautiful appearance, uniform wall thickness and continuous operation, and is suitable for mass production. Therefore, it is the main forming method for carbon steel and alloy steel elbows, and is also applied to some specifications of stainless steel bends. The formation of the head.

3 Problems in the hot push process of elbows (short-radius stainless steel elbows are especially obvious)

20181022082510 78793 - Hot push forming process for stainless steel elbow

  1. Push-made semi-finished products, the tube port of the stainless steel elbow presents the shape of the horseshoe mouth. After testing, the diameter and ellipticity of the nozzle are out of tolerance, and the end face of the nozzle is not flat;
  2. The inner tube wall of the tube port is thin, and the wall thickness reduction rate is excessive;
  3. In the scribing + cutting process, one end needs to cut off materials of 30-50 mm, and the material utilization rate is low;
  4. Special equipment (bed, press, plastic tire) and unloading workers must be equipped in the production process.

4 Improved stainless steel elbow hot push forming process

4.1 Reduction and integration in manufacturing processes

In the conventional hot push process, the port of the tube blank cannot be pressed against the mandrel under the action of the pushing force, which is the main cause of the problems (1) and (2), and the cutting in the problem (3) must be performed. To solve this problem.
In order to avoid the occurrence of problems (1)-(3), it was found through long-term observation that when two stainless steel elbows of 90° or smaller angle were cut with a 180° stainless steel elbow, the two ports at the cutting position were relatively neat. Subsequently, the cutting port was tested several times, and the port size was found to meet the technical requirements. Therefore, we found a breakthrough point to solve the problem: in the process of pushing the stainless steel elbow, in order to ensure that the stainless steel elbow blank is always attached to the core, the whole material length is pushed, and when the stainless steel elbow semi-finished product is pushed out of the mandrel, Cut again.
After many studies and experiments, the manufacturing process of the conventional hot push stainless steel elbow has been greatly improved, and the improved manufacturing process is as follows.
Preparation process (pushing process) → lubrication of inner wall of tube blank, feeding → pushing + cutting → heat treatment (when necessary) → hydraulic pressure test (when required) → pipe end groove → size inspection → non-destructive testing → finished product warehouse.
The improved manufacturing process is reduced and integrated in the conventional manufacturing process, mainly including the following aspects.

4.2 Reduce the blanking process

The billet of the conventional elbow hot push manufacturing process pushes a stainless steel elbow for a section of the billet. At the same time as the technician prepares the process, the length of the billet for the single elbow must be calculated in advance (this length is based on theoretical calculation, according to The specifications of the stainless steel elbows are different and the actual experience is obtained. The drawings are issued, and the special sawing machine for cutting the workpiece is used for cutting and deburring. The improved manufacturing process reduces the calculation of the length of the tube blank, the issuance of the drawings, and the blanking process.

4.3 Reduce the shaping process

In the process of pushing a bend of a section of the tube blank used in the conventional hot push stainless steel elbow, the tube blank tube port will form a horseshoe mouth shape due to the expansion and pushing. The tube port portion diameter and ellipticity are out of tolerance, and the tube end face is Uneven, the wall thickness at the tube port is thin. The shaping process uses a press and a special shaping tire to shape the diameter and ellipticity of the semi-finished stainless steel elbow pipe port to meet the technical standards. The improved manufacturing process reduces this process.

4.4 Integrate “hot push and scribing + cutting” as “push side + cut”

The semi-finished product made by the conventional hot push process, the wall thickness of the horseshoe mouth and the port at the end of the tube is extremely thin, so that the tube end works at the groove, which is very large, and the scribing + gas cutting process is required, and the cutting is generally 30-50 mm. Left and right, then groove processing. After the improvement, the combination of “hot push and scribing + cutting” is the “hot push + cut” process.

5 Elbow hot push manufacturing process improved advantages

5.1 Pushing a number of stainless steel elbows with a stainless steel pipe to improve material utilization and work efficiency

After the improvement, the blanking process is reduced, and the length of the single stainless steel elbow is not used for the blanking of the stainless steel elbow, and the inner wall of the stainless steel pipe is directly coated with the lubricant, and the mandrel is pushed, that is, a piece of stainless steel is used. The tube pushes a plurality of stainless steel elbows, which reduces the calculation of the length of the tube blank, the issuance and drawing of the drawings, and greatly improves the material utilization rate and work efficiency.

5.2 Integrate “hot push and scribing + cut” as “overturn + cut” to ensure the quality of the elbow is improved

When a plurality of elbows are pushed by a stainless steel pipe, when the stainless steel elbow pushes out the part of the mandrel to reach the process requirement angle, the cutting mechanism is used to cut the stainless steel elbow along the stainless steel elbow by requiring a radial angle line (reserving the groove) The cutting line is at the front port of the stainless steel elbow 1 and the rear port of the stainless steel elbow 2, which ensures that the tube blank has no fracture on the mandrel. The shape of the stainless steel elbow has been determined during cutting, which avoids the formation of the shape of the horseshoe mouth and ensures the formation. The quality of the head port.

5.3 Reduced equipment, staffing and energy consumption

Reduce the cutting process and shaping process, eliminating the investment and power consumption of sawing machines, presses, plastic tires and other equipment, workers, plastic workers, etc.; integration of “hot push and scribing + cutting” as ” Push + cut “changes the cutting in two cold states in a conventional manufacturing process to a hot state cutting, reducing energy consumption.

Source: China Stainless Steel Elbow Manufacturer – Yaang Pipe Industry Co., Limited (

(Yaang Pipe Industry is a leading manufacturer and supplier of nickel alloy and stainless steel products, including Super Duplex Stainless Steel Flanges, Stainless Steel Flanges, Stainless Steel Pipe Fittings, Stainless Steel Pipe. Yaang products are widely used in Shipbuilding, Nuclear power, Marine engineering, Petroleum, Chemical, Mining, Sewage treatment, Natural gas and Pressure vessels and other industries.)

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