Construction and using method of VRB (Variable Thickness Rolled Blank) forming limit stress diagram

Abstract

The invention discloses a construction and using method of a VRB (Variable Thickness Rolled Blank) forming limit stress diagram. The construction and using method comprises the following steps: 1) determining basic parameters of a sample material, wherein the basic parameters of the material comprise material coefficient of normal anisotropy (r), material coefficient of strain hardening (n) and material constant K; 2) obtaining forming limit curves of various equal-thickness blanks of the corresponding sample material by using a bulging experiment; 3) converting the forming limit curves of different strain paths under different thickness of the corresponding sample material into corresponding forming limit stress curves according to corresponding yield criterions and a formula; 4) connecting the forming limit stress curves into a curved surface, i.e. a three-dimensional forming limit stress diagram, by using an interpolation method. The construction and using method of the VRB forming limit stress diagram has the advantage that since the traditional forming limit strain curves are converted into the forming limit stress curves which are further converted into the three-dimensional forming limit stress diagram which considers the blank thickness, whether the VRB can be successfully formed or not can be judged more intuitively and accurately.

Description

technical field [0001] The present invention relates to the field of (Variable Thickness Rolled Blanks, VRB) stamping forming processing, in particular to the construction and use of variable thickness plate (VRB) stamping forming limit stress diagram, which is mainly used to judge the fracture in the forming of variable thickness plate (VRB), Evaluation of the formability of thickened plate (VRB). Background technique [0002] Sheet metal forming is an important part of metal forming, and it is widely used in manufacturing industries such as aerospace, automobile, light industry and household appliances. Different from volume forming, sheet metal forming is mainly deformed in a flat state. There are two main deformation modes and four states; stretching-based "release" includes pull-pull and pull-compression. state. The "retraction" that focuses on compression includes two states of compression-compression and pull-compression. [0003] When the sheet metal forming metho...

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Problems solved by technology

[0007] The problem to be solved by the present invention is to provide a method for establishing and using the forming limit stress diagram of variable thickness plate (VRB), which can not only solve the problem that the traditional forming limit diagram cannot predict the forming ability of variable thickness plate (VRB), but also provide a A method that can accurately and conveniently evaluate the cracking problem in the forming process of variable thickness plate (VRB). This method can not only be used for the forming limit prediction of steel variable thickness plate, but also for the forming limit prediction of other material variable thickness plate

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