Method for forming pipe fitting with internal high pressure and external low pressure and forming machine

Abstract

The invention discloses a method for forming a pipe fitting with internal high pressure and external low pressure. The method comprises the steps that a pipe fitting to be formed is put into a cavity,a swelling region is formed between the pipe fitting to be formed and the inner wall of the cavity, low pressure fluid is continuously injected into the swelling region, then high pressure fluid is injected into the inner part of the pipe fitting to be formed, the high pressure fluid forms the pressure on the outer wall of the pipe fitting to be formed, so that the pipe fitting to be formed expands to the swelling region, when the pipe fitting expands to fit the inner wall of the cavity, supplying of the low pressure fluid is stopped, the formed pie fitting is taken out, and a working cycle is completed. The invention further discloses a forming machine, and the pipe fitting is formed according to the forming machine for a pipe fitting with internal high pressure and external low pressure. According to the method for forming a pipe fitting with internal high pressure and external low pressure, a first through hole and a second through hole are formed in a die for circulating the low pressure fluid into and out of the swelling region, a certain pressure P1 is formed for pipe fitting, so that it is guaranteed that the pipe fitting can swell uniformly everywhere, and a good forming effect is achieved.

Description

technical field [0001] The invention relates to the technical field of pipe fitting production equipment, in particular to a pipe fitting internal high pressure external low pressure forming method and a forming machine. Background technique [0002] The production and processing of hot-end pipe fittings (connecting pipe fittings between the automobile engine and exhaust pipe) and body structural parts (automobile chassis supports, transverse and longitudinal beams, instrument beams, etc.) are mostly produced by internal high-pressure forming technology, that is, injection High-pressure water, the left and right side cylinders are fed to make the product expand to the required shape; the cross-sectional area of ​​the hot-end pipe fittings generally changes greatly, that is, the local expansion is large, and the expansion area is prone to cracking; the conventional process is to carry out Multiple annealing and multiple forming can meet the forming requirements. The specific ...

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Problems solved by technology

[0003] 1. Cracks are easy to occur during molding, the scrap rate is high, and the quality requirements for welds are high;

[0004] 2. In order to reduce the proportion of forming cracks, it is necessary to perform multiple annealing, eliminate the forming stress, and form multiple times to meet the processing requirements. This process consumes a lot of energy, increases the demand for equipment, and increases the processing cost;

[0005] 3. Due to the influence of raw material performance, molding pressure and annealing process in the first forming stage, the size of the product after the first forming stage cannot be effectively controlled, which will affect the secondary forming;

[0006] 4. There are many technological processes, the difficulty of process quality control is increased, and the cost is increased

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