Test method based on forming limit diagrams for plate hydroforming

Abstract

Provided is a test method based on forming limit diagrams for plate hydroforming. The method comprises the steps that a series of test plates, assistant plates and laminated assistant plates of different width dimensions and specific shapes are overlapped on a female mold in a specific mode; the plates are subjected to forming limit testing in an overlapped plate hydroforming mode; the forming performance of the laminated assistant plates is higher than that of materials of the test plates, and it is ensured that the test plates enter an unstable rupture state firstly; and then all second principal strain positive portions and second principal strain negative portions under linear loading are obtained by measuring test-pieces of different widths, and accordingly all the complete hydroforming limit diagrams are obtained. The test method based on the forming limit diagrams for plate hydroforming carries out quasi-complement on the vacancy of the forming limit diagrams for plate hydroforming. The method has the advantage of overlapped plate formation so that pressure transfer of a hydraulic chamber can be guaranteed. In the hydroforming process, completeness of brake beads is ensured through the assistant plates, gap uniformity is ensured, and the plates are prompted to deform sufficiently. The test method has the advantages of being high in efficiency, small in number of molds, low in cost, safe and convenient to operate, and the like.

Description

technical field [0001] The invention belongs to the acquisition of sheet metal strain forming limit curves, in particular to an experimental method for testing the forming limit of materials in a hydraulic free bulging process. Background technique [0002] Hydroforming is an advanced flexible forming technology that utilizes high-pressure forming of flowing liquids. With the rapid development of advanced technology, hydroforming is at the forefront and is becoming more and more mature. Sheet metal hydroforming is to use flexible liquid medium to replace some traditional rigid molds for sheet metal parts, that is, to become flexible manufacturing, and the advantages of flexible manufacturing are good quality, high precision, high energy utilization and many other advantages. At present, it is widely promoted in the fields of automobile and aviation. It is traditionally believed that hydroforming is a bulging process, and each position of the sheet is in a state of tension,...

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Problems solved by technology

However, since the strain forming limit judgment of traditional materials is not suitable for liquid-filled forming, it is impossible to obtain a complete forming limit diagram under different linear paths, that is, it is impossible to judge the forming limit of each part of a complex part

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