Necking and flaring cold extrusion process of seamless steel pipe

Straight tie rods and tie rods are two important parts of the steering system of an automobile. 35- steel seamless steel pipe is used as the raw material, and the seamless steel pipe of which specification, diameter and wall thickness to use is determined according to the load of the front axle and the bending angle of the tie rod. However, most seamless steel pipes need shrinking and flaring to produce products. The shrinking and flaring of seamless steel pipes is a forming process in which the mouth of the pre-formed steel pipe is reduced and enlarged through the shrinking and flaring dies.
Why is the seamless steel pipe shrinking?
In the case of materials with the same weight and length, the tie rods and tie rods will choose materials with larger diameter and relatively thin wall thickness. Why?
When designing the chassis of each automobile manufacturer, especially the layout of the straight tie rods will be considered. As a result, the straight tie rods will not be worthy of the name. Generally, there will be 1 to 4 bending points, and a maximum of 5 bending points will appear. The bending point with the largest bending angle becomes the breaking point of tie rod fatigue. The force at the bending point can be decomposed into axial force and radial force. Axial force forms tensile pressure, which requires sufficient cross-sectional area. At the same time, the radial force forms the bending force, which requires a relatively large outer diameter to obtain a sufficient section modulus. The selected material has a relatively large outer diameter and thin wall, so the inner hole thread and the riveted inner hole cannot be processed. It is necessary to shrink the mouth to a certain outer diameter before processing the threaded inner hole and riveting the inner hole.

Why should seamless steel pipe be flared?
There is a tie rod assembly structure, the accessories are installed in the port of the tie rod, and the tie rod needs to be flared to a certain outer diameter to form enough space inside.

• Shrinking and expanding hot extrusion process

( 1 ) Shrinking and flaring hot extrusion means that the material is heated above the specified temperature, and its plasticity is good in its hot state. The equipment used: super audio frequency, forging machine, necking machine, flaring machine, etc. .
( 2 ) Heat shrinking process: end heating , rough forging , rolling , compression, natural cooling, and car port (this is one end shrinking, both ends shrinking repeat the above process).
( 3 ) Process flow of thermal flaring: port heating, rolling extrusion flaring, natural cooling, and car port ( this is one end flaring, both ends flaring repeat the above technological process ) .

• Shrinking and expanding cold extrusion process

( 1 ) The shrinking and expanding cold extrusion process is a hydraulic push die
Tool, directly extruded nozzle forming.

( 2 ) One-end necking and flaring process: lubricating oil on the mold and nozzle, squeezing the nipple, flaring, and a car port.

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