Gas-liquid composite hot forming process method for closed pipe

Abstract

The invention provides a gas-liquid composite hot forming process method for a closed pipe. The gas-liquid composite hot forming process method comprises the following steps that the pipe is heated to obtain a pipe blank, gas is introduced into the pipe blank, compression molding is carried out on a high-strength section, a low-strength section is cooled in air, liquid water is injected into the pipe blank, and die assembly molding is carried out on the low-strength section. According to the process method, the high-strength section and the low-strength section are machined and formed correspondingly, so that control and implementation are convenient, the mechanical properties of the high-strength section and the low-strength section are uniform, compression deformation is adopted for the transition section between the high-strength section and the low-strength section, the axial stress difference caused by bending in the thickness direction is eliminated, mechanical property transition is natural, and the part size precision is high; and a die does not need to be heated, so that the service life of the die is prolonged, and the production cost is reduced.

Description

technical field [0001] The invention belongs to the field of parts processing technology, and in particular relates to a technology method for gas-liquid compound thermoforming of closed pipe parts. Background technique [0002] Thermoformed parts are formed when the material is heated to the austenite state. Under this condition, the material has good formability and small springback; during the quenching process in the pressure-holding mold, the austenite structure of the material transforms into a martensite structure, thereby achieving a higher The strength (about 1500MPa). Thermoformed parts are widely used in the field of lightweight automobiles. However, because the structure of formed parts is a single martensitic structure, the elongation rate of formed parts is low, only 5-7%. It is not conducive to the impact energy absorption of parts. To solve this problem, the mechanical properties of special parts of parts need to be softened and controlled. [0003] For the...

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Problems solved by technology

[0004] The performance of the parts produced by the above method is uniform, and the performance (tensile strength) of the pipe fittings reaches about 1500MPa uniformly, and it is impossible to realize the flexible control of the mechanical properties of the tubular parts

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