Uni-directional stretching test clamp for warm shaping of metal plate

Abstract

A uni-directional stretching test clamp for warm shaping of a metal plate relates to the technology of testing warm shaping performance of metal plates. The clamp consists of a displacement magnitude leading-out part, a stretching test element positioning and clamping part and a test machine connecting part, and can lead the displacement magnitude of scale distance of a stretching test element with different softness degrees out of a heating furnace so as to provide convenience for accurately measuring the displacement by using an extensometer. After the stretching test element is provided with a clamp, the direction of a loading force and the direction of the length of the stretching test element can be ensured to be on the same line. A cooling device can effectively cool the connecting place between the clamp and a testing machine. The clamp can effectively improve the accuracy of a test result.

Description

technical field [0001] The invention relates to a technology for testing the thermal forming properties of metal sheets, in particular to a tensile test fixture for testing the mechanical properties of uniaxial tensile in the warm forming of metal sheets. Background technique [0002] When studying the warm forming properties of metal sheets, the stress-strain curve and elongation of the material under warm forming conditions can be obtained through uniaxial tensile tests at different temperatures, so as to deduce the strain hardening index and The strain rate sensitivity coefficient is used to study the influence of each parameter on the material properties. [0003] Compared with the tensile test at room temperature, the uniaxial tensile test under heating has many particularities. First: the tensile test piece must always be in a heated environment during the entire test process, so the displacement of the gauge length of the tensile test piece cannot be directly measure...

AI Technical Summary

Problems solved by technology

But its design has the following problems: 1. It is impossible to install an extensometer when measuring the displacement of the gauge length, and the displacement of the gauge length can only be approximately replaced by the overall deformation of the tensile test piece, which reduces the accuracy of the test

2. The positioning of the tensile test piece adopts the method of "one pin on both sides". There is over-positioning, and the positioning accuracy depends on the manufacturing accuracy of the profile of the tensile test piece, so it cannot be guaranteed that the direction of the loading force is collinear and oblique The wedge clamping method makes the installation of the tensile test piece more cumbersome; 3. There is no cooling device, which cannot prevent the adverse effects of high temperature on the sensor at the chuck of the testing machine

However, the design of the fixture still has deficiencies: 1. It is impossible to install an extensometer when measuring the displacement of the gauge length, and the displacement of the gauge length can only be approximately replaced by the overall deformation of the tensile test piece, which reduces the accuracy of the test; 2. The method of mechanical centering is used to ensure that the length direction of the tensile test piece is collinear with the direction of the loading force, which increases the precision requirements for the processing and assembly of the parts of the fixture.

However, its design still has the following disadvantages: 1. The degree of softening of the material is different at different temperatures. The higher the temperature, the greater the degree of softening of the material, and the easier it is for the protrusion at the gauge length position in the middle of the tensile test piece to draw rod tension in the displacement. 2. The tensile test piece is positioned with a pin and is not clamped, so it cannot be guaranteed that the length direction of the tensile test piece is collinear with the direction of the loading force; 3. The cooling of the The water passes through the cooling device in a direct flow, and the cooling capacity is lower than that of the circulation

Therefore, the test device can be used in the case of warm forming, but it is not suitable for high temperature heat test

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