Forming limit measuring device under bilinear strain path and testing method

Abstract

The invention provides a forming limit measuring device under a bilinear strain path and a testing method, and belongs to the technical field of metal sheet forming. The forming limit measuring device comprises a main cylinder, an upper cross beam, a blank pressing cross beam, a blank pressing spring, a draw bead and the like. The method comprises the steps that a test sample is fixed on a blank pressing ring, a camera and an illuminating lamp are fixed on the upper cross beam, and focusing of a measuring system is completed; an upper male die moves downwards to drive the test sample to generate stain, and after the upper male die makes contact with and tightly presses a female die, a reverse-drawing male die moves upwards under the driving action of a lower ejection cylinder until the test sample is necked or broken; stain at the necked or broken position is measured by adopting a strain testing and analyzing system to obtain the forming limit of the material under the bilinear strain path. The forming limit measuring device under the bilinear strain path and the testing method have the advantages that the limit strain of the sheet under the bilinear strain path can be quickly and accurately measured.

Description

technical field [0001] The invention belongs to the technical field of sheet metal forming, and in particular relates to a forming limit measuring device and a testing method under a bilinear strain path. The device is used for the forming limit test and research of metal sheet materials under the bilinear strain path. Background technique [0002] In the field of sheet metal forming, the forming limit diagram (FLD) is an important method to evaluate the sheet metal formability, which reflects the ultimate strain of the sheet metal when plastic instability occurs. FLD provides a basis for conveniently studying sheet forming limit and evaluating tensile instability theory. Under laboratory conditions, the forming limit diagram can usually be determined by using a rigid punch to bulge a metal sheet. By changing the sample size or lubrication conditions, the sheet material can be obtained in one-way tension, two-way constant tension and plane strain, etc. The ultimate strain ...

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Problems solved by technology

[0005] The purpose of the present invention is to provide a forming limit measuring device and testing method...

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