Visual measurement method of plate forming limit curve (FLC)

A forming limit curve and visual measurement technology, which is applied in the field of mechanical processing, can solve the problems of heavy workload for detection and calculation of limit strain, heavy workload for grid drawing, and low efficiency. It achieves short measurement cycle, wide application range, Simple operation effect

CN102435512BActive Publication Date: 2013-07-31XI AN JIAOTONG UNIV
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Patent Information

Authority / Receiving Office
CN · China
Patent Type
Patents(China)
Current Assignee / Owner
Publication Date
2013-07-31

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Abstract

The invention discloses a visual measurement method of a plate forming limit curve (FLC), comprising the following steps: firstly, preparing for a specimen; secondly, calibrating a camera; thirdly, acquiring an image; fourthly, calculating speckle strain; fifthly, establishing parallel section lines; sixthly, fitting node data of the section lines; seventhly, solving limit strain; and eighthly, establishing plate FLC. Through the operation steps, the visual measurement method of the plate FLC, provided by the invention, can be used for efficiently measuring the plate forming limit strain to establish the FLC. The visual measurement method of the plate FLC has the characteristics of convenience in measurement operation, high degree of automation, accurate and reliable measurement result and non-contact measurement.
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Description

Technical field:

[0001] The invention belongs to the field of mechanical processing, and relates to a method for measuring sheet metal forming limit curves, in particular to a visual measurement method for sheet metal forming limit curves. Background technique:

[0002] The Forming Limit Curve (FLC), also known as the Forming Limit Diagram (FLD), is used to determine the degree of deformation that a specified material can achieve when it is stretched, bulging, or a combination of stretching and bulging. It is a quantitative description of the formability of the sheet metal, and it is also a judgment curve for the success or failure of the stamping process.

[0003] There are usually two methods for determining the sheet metal forming limit curve: 1. Theoretical calculation; 2. Experimental determination.

[0004] The theoretical calculation of the forming limit is mainly done by using different yield criteria and plastic constitutive relations, and using different tensile i...

Examples

Embodiment Construction

[0032] The present invention will be further described in detail below in conjunction with the accompanying drawings and the measurement experiment of FLC of a certain steel material.

[0033] The present invention proposes a kind of sheet metal FLC measuring method, concrete operation steps are as follows figure 1 shown. The hardware structure of the experimental device used is as follows: figure 2 As shown, it is mainly composed of 2 CCD cameras, 2 LED lights, 1 sheet forming machine (or 1 material tensile testing machine), 1 computer, etc.

[0034] The first step is sample preparation, cutting the sheet blank into a sample that meets the standard size and geometric shape requirements (GBT24171.2), a group of experimental samples cut from a certain type of steel such as image 3 shown. Use artificial spray paint to make speckle patterns on the surface area of ​​the sample to be measured (such as Figure 4 shown). Requirements for the preparation of sheet metal samples:...