Optical non-contact plate formation limit measurement method

Abstract

The invention relates to an optical non-contact plate formation limit measurement method, and belongs to the technical field of metal plate formation. The optical non-contact plate formation limit measurement method comprises the steps of preparation a sample, in which a plate blank is cut to a test piece with a size and geometrical shape conforming to standard requirement; performing grid printing, in which grids are printed on the test piece by an electrolyte corrosion method; performing expansion experiment, in which expansion experiment is performed on a formation experiment machine untilthe test piece is necked or broken; calibrating a camera, in which the camera is calibrated by an optical strain measurement equipment; processing grid strain, in which image information of a sample surface is recorded from a plurality of angles, and analysis and processing are performed to primary and secondary strain distribution of a deformation unstable part of the experiment piece; and building a formation limit diagram, fitting obtained limit strain points to form an appropriate curve or constructing a strip-shaped region so as to build a plate formation limit diagram. The optical non-contact plate formation limit measurement method has the characteristics of measurement operation convenience, high automation, accurate measurement result and reliability and has good universality.

Description

technical field [0001] The invention relates to the technical field of sheet metal forming, in particular to a method for measuring sheet forming limit based on optical non-contact. Background technique [0002] In the field of sheet metal forming, the forming limit diagram (Forming Limit Diagram, FLD) is used to determine the degree of deformation that the sheet can achieve when it is stretched, bulging, or a combination of stretching and bulging, reflecting the plastic deformation of the sheet. The ultimate strain at steady state. It is a quantitative description of the formability of sheet metal and an important method to evaluate the formability of sheet metal. It provides a basis for conveniently studying the forming limit of sheet metal and evaluating the theory of tensile instability. At present, there are usually two methods for measuring the forming limit of sheet metal: 1. Theoretical calculation; 2. Experimental determination. The theoretical calculation of the ...

AI Technical Summary

Problems solved by technology

However, the theoretical derivation only conforms to a specific linear or approximately linear strain path, while the stamping of actual sheet metal, especially in the case of more complex parts or multi-process forming, often deviates from the linear strain path, resulting in inaccurate judgments plate instability

Moreover, the scope of application of different yield criteria is limited, there are many parameters involved, and the calculation accuracy is affected by many factors, so there are not many applications

Images