Vision measurement method for anisotropic performance parameters in sheet forming

An anisotropic and visual measurement technology, applied in the field of mechanical processing, can solve the problems of large workload, low efficiency and low precision, and achieve the effect of short measurement cycle, simple work and simple operation.

Inactive Publication Date: 2014-11-12
SOUTHWEAT UNIV OF SCI & TECH
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  • Abstract
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  • Claims
  • Application Information

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Problems solved by technology

The experimental method can obtain a more accurate plastic strain ratio, but because of the need to repeat the measurement of the sample many times, this method can obtain the plastic strain ratio r It is cumbersome and has the following disadvantages: (1) The workload of manual measurement is large and the accuracy is low; (2) The yield deformation of the sample during the axial loading process, the delay effect of the initialization delay effect of the longitudinal and horizontal extensometer system, and the instantaneous transient caused by the speed switching The inertial effect will cause r The error of the value and strain path characteristics affects the accuracy; (3) The processing of later experimental data is complicated and the efficiency is not high

Method used

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  • Vision measurement method for anisotropic performance parameters in sheet forming
  • Vision measurement method for anisotropic performance parameters in sheet forming
  • Vision measurement method for anisotropic performance parameters in sheet forming

Examples

Experimental program
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Embodiment 1

[0074] The present invention proposes a method for measuring the anisotropic performance parameters of sheet metal, and the specific 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 1 material tensile testing machine 1, sheet metal sample 2, 2 CCD cameras 3, 2 LED lights 4, 1 controller 5 and 1 computer 6, etc.

[0075] The first step is sample preparation, cutting the sheet blank into samples that meet the standard size and geometric shape requirements (GB / T5027-1999), a group of experimental samples cut from a certain clad sheet such as image 3 shown. Create speckle patterns on the surface area of ​​the sample to be measured by artificial spraying. Requirements for the preparation of sheet metal samples: a) It should be ensured that the edge of the prepared sample is free of cracks, and the surface should not have defects such as scratches; b) The surface of...

Embodiment 2

[0084] The implementation steps of this example are the same as Example 1. The sample material used in this example is AA6061 (aluminum material), and the sample size is as follows: image 3 shown. Utilize the true stress-strain curve of the AA6061 sample that the inventive method obtains as Figure 8 shown, according to Figure 9 The straight line between the true strain in the length direction and the true strain in the width direction obtained by the interval regression fitting shown in the figure shows the slope m =-0.39755, and then calculated r =0.65989.

Embodiment 3

[0086] The implementation steps of this embodiment are the same as in Example 1. The sample material used in this embodiment is SPCC (cold-rolled low-carbon steel), and the sample size is as follows image 3 shown. Utilize the true stress-strain curve of the SPCC sample that the inventive method obtains as Figure 10 shown, according to Figure 11 The straight line between the true strain in the length direction and the true strain in the width direction obtained by the interval regression fitting shown in the figure shows the slope m =-0.60718, and then calculated r =1.54570.

[0087] In order to verify the accuracy of strain calculation from digital speckle images, the Figure 12 The image acquisition device shown is designed and realized the standard tensile test of steel specimens, and the accuracy verification and comparison are carried out by using the extensometer, as shown in Figure 13 As shown, the index values ​​decrease from the inside to the outside on the ...

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Abstract

The invention discloses a vision measurement method for anisotropic performance parameters in sheet forming, belonging to the field of machining methods. The vision measurement method comprises the following steps of: (1) sample preparation; (2) camera calibration; (3) image acquisition; (4) speckle strain calculation; (5) selection of deformation state; (6) regression analysis processing; and (7) calculation of anisotropic performance parameters. The vision measurement method disclosed by the invention has the beneficial effects that the strain data of sheet forming can be measured in a high-efficiency manner so as to calculate the anisotropic performance parameters, and has the characteristics of convenience in measurement operation, high automation degree, accurate and reliable measurement result and non-contact measurement.

Description

technical field [0001] The invention belongs to the field of mechanical processing methods and relates to a method for measuring anisotropic performance parameters of sheet metal forming. Background technique [0002] plastic strain ratio r It is an important index to express the anisotropic performance dominated by the texture. When the metal sheet sample is stretched in the axial direction to produce uniform plastic deformation, the ratio between the true strain in the width direction and the true strain in the thickness direction within the gauge length of the sample is ratio, which is defined as follows: [0003] (1) [0004] in: a 0 - the thickness of the initial gauge length of the sample; [0005] b 0 - the width of the initial gauge length of the sample; [0006] l 0 - the length of the initial gauge length of the sample. [0007] According to the plastic strain ratio measured in three directions of 0°, 45° and 90° from the rolling direction on th...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): G01N21/84
Inventor 蔡勇刘震昆向科峰梁晋罗成明廖晓波
Owner SOUTHWEAT UNIV OF SCI & TECH
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