Fluid pressure forming method for small-radius elbow

Abstract

The invention provides a fluid pressure forming method for a small-radius elbow. A device for implementing the method comprises an upper die, a lower die, a lower sealing ring, a lower push head, an upper sealing ring, an upper push head, a transition section, an initial pipe billet, a semi U-shaped groove and the like; and a large-radius elbow is formed by numerical control pipe bending or pushing and bending and then put into the semi U-shaped groove of the die for fluid pressure forming. By the method using the device, the relative bending radius is reduced in a mode of increasing the diameter of the elbow by bulging and reducing the bending radius, so that the small-radius elbow is manufactured by fluid pressure forming. By the method, the small-radius elbow made of stainless steel, aluminum alloy, titanium alloy or the like can be formed by using a warm medium, a high-temperature heat medium or a high-temperature gas medium. By the method, the roundness of a bent section can be increased, and the relative bending radius is 0.7 to 2.0; and the method has the advantages of good part reshaping property, uniform wall thickness, high strength and rigidity and the like.

Description

technical field [0001] The invention belongs to the technical field of metal pressure processing, in particular to a fluid pressure forming method for a small-radius elbow. Background technique [0002] After years of development, the bending and forming of pipe fittings has formed a variety of processing methods. Divided according to different standards, the bending method can be divided into the following types: according to whether the tube blank is heated during bending, it can be divided into hot bending and cold bending; according to the different bending methods, it can be divided into stretch bending and compression bending. , bending, push bending, rolling and extrusion bending; according to the different ways of restricting the pipe during bending, it can be divided into internal restriction of pipe fittings, external restriction of pipe fittings and internal and external restriction of pipe fittings; according to whether there is core material filling during bendi...

AI Technical Summary

Problems solved by technology

[0006] (3) The equipment used in the bending method can easily cause the outer wall of the catheter to be excessively thinned or even cracked, so it is difficult to form a small-radius elbow;

[0007] (4) Although the small radius elbow made by the shear bending method can achieve a small relative bending radius, the material flow distribution in the middle straight section and the curved section is not good, so it is easy to crack;

[0008] (5) Although the internal and medium pressure push bending method can form an elbow with a small bending radius, the processing efficiency is relatively low, and when the filler shrinks or the fluidity is not good, it is easy to cause the inner wall to wrinkle;

[0009] (6) Rubber mandrel constrained push bending does not require sealing and has high processing efficiency, but the internal pressure distribution of the rubber is uneven, which easily leads to wrinkling, so the inner wall of the catheter is not smooth, and the selection and durability of rubber need to be studied;

[0010] (7) Although the forming method and equipment of filler push bending are simple, the deformation and wall thickness of the front section of the catheter deformation are not easy to control, the wall thickness is uneven, and the uneven internal pressure of the filler can easily lead to wrinkling;

[0012] In summary, the existing bending methods for thin-walled small-radius catheters generally have defects such as low strength and poor formability.

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