Bending formation method of small-curvature bending radius L type thin-wall aluminum alloy bent pipe

Abstract

The invention discloses a bending formation method of a small-curvature bending radius L type thin-wall aluminum alloy bent pipe. Two ends of the bent inner side of a long pipe blank of an aluminum alloy thin-wall pipe blank are grooved by 35-45 degrees; a protective agent is coated at the external of the pipe blank; oily molybdenum disulfide is sprayed in the semi-cylindrical surface of an area from the from part of the bent inner side of the pipe blank to the front part pi D, so that a material on the bent inner side of the pipe is facilitated to flow and to improve wrinkling; a traditional polyurethane round bar is replaced; multiple polyurethane cylinder blocks are filled in the pushed end of the pipe blank; and compared with an integral polyurethane filler rod, the taking out is easier after formation, and the forming efficiency is improved. Meanwhile, the polyurethane cylinder blocks with proper hardness, thickness and diameter facilitate internal support of the bent pipe, and are not liable to generate wrinkles on the bent inner side; and the jacking force of a core head is reinforced during forming to supply enough internal pressure into the pipe through a filler to force a lot of materials to flow to the front groove so as to prevent wrinkling to form the qualified small-curvature bending radius L type thin-wall aluminum alloy pipe.

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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