A push-bending forming method for l-shaped thin-walled aluminum alloy elbow with small curvature bending radius

Abstract

The invention discloses a push-bending forming method of an L-shaped thin-walled aluminum alloy elbow pipe with a small curvature radius. By bending a long pipe blank of an aluminum alloy thin-walled pipe blank, the inner two ends are beveled at 35° to 45°. And apply a protective agent on the outside of the tube blank, spray oily molybdenum disulfide on the semi-cylindrical surface of the inner front part of the tube blank and the area πD away from the front part, which is beneficial to the material flow inside the tube bending and improve wrinkling; and replace the original Some polyurethane round rods are filled with several polyurethane cylindrical blocks inside the pushed end of the tube blank, which is easier to take out after forming than the integral polyurethane filler rod, which improves the forming efficiency. At the same time, the polyurethane cylindrical block with appropriate hardness, thickness and diameter is conducive to the internal support of the elbow, and is not easy to cause wrinkles on the inner side of the bend; during the forming process, the thrust of the core head is increased, and the filler provides sufficient internal pressure in the pipe to force the material to slope forward. A large amount of flow at the mouth, so as to avoid wrinkling, and form qualified L-shaped thin-walled aluminum alloy pipe fittings with small curvature bending radius.

Description

technical field [0001] The invention relates to the technical field of pipe bending, in particular to a push-bending method for an L-shaped thin-walled aluminum alloy elbow with a small curvature radius. Background technique [0002] Pipe push bending is a bending method that pushes the tube blank with filler inside into the bending mold for forming. It is generally used to form a 90° pipe bend whose relative bending radius R is less than 1 times the pipe diameter D (R≦D) Head, that is, except for the 90° arc section of the pipe elbow, there are basically no straight pipe sections at both ends. This is because the pipe fittings with less than 1 times the relative bending radius are prone to wrinkling on the inside and cracking on the outside, so it is difficult to bend pipes less than 1 times the relative bending radius in other existing pipe bending methods. At present, the pipe is push-bent to form a pipe fitting with a relative bending radius of 1 times. The length of th...

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Problems solved by technology

The length of the tube blank of this part is obviously greater than πD or πR, and basically reaches or exceeds 2πD. At this time, even if the material is beveled before and after the tube blank, the material cannot be smoothly transferred due to the long distance from the inner side of the tube tail close to the pusher to the bending part. The groove of the pipe tail disappears, which inevitably produces serious wrinkles on the inner side of the elbow. At present, such parts are often welded by 90° elbow welding straight pipe or half pipe stamping and welding, which increases the production cycle and improves the quality of the pipe. cost

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