A test device and method for obtaining forming limit diagrams under complex loading conditions

Abstract

The invention discloses a test device and method for acquiring forming limit diagrams under the complicated loading condition and belongs to the technical field of forming processing of metal plates. The test device is formed by refitting a specially made male die on the premise that a multifunctional plate forming machine is included originally, and other devices and molds are original equipment; the specially made male die comprises a small male die and a large male die, a hoop interface is arranged at the lower end of the small male die and used for butt joint with a hydraulic ejection rod, and a cavity capable of being in sleeving connection with the small male die is formed in the large male die. By means of the provided test device and method, complicated loading can be further realized, corresponding predeformation on plates is not required before bulging, and the ageing problem and the relatively complicated test process are avoided. The plates in the same size are adopted, plates in various sizes are not required to be processed, batch processing can be performed, the test time is saved, and the test period is shortened.

Description

Technical field: [0001] The invention belongs to the technical field of sheet metal forming and processing, and in particular relates to a test device and method for obtaining a forming limit diagram under complex loading conditions. Background technique: [0002] The forming limit diagram (Forming Limit Diagram, FLD) is the ultimate strain e 1 、e 2 (engineering strain) or ε 1 , ε 2 (True strain) constitutes a strip-shaped area or curve, which divides the entire graphic area into three parts: safe area, rupture area and critical area. FLD can fully reflect the action of sheet metal in one-way and two-way tensile stress The local forming limit below is a quantitative description of the formability of the sheet metal and a judgment curve for the success or failure of the stamping process. It is important in both the actual stamping production of the sheet metal and the numerical simulation analysis of the sheet metal. application. [0003] There are usually two methods fo...

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Problems solved by technology

[0006] 1. There is no definite theoretical system to determine the forming limit diagram of a certain sheet during theoretical calculation. The calculation process is complex and error-prone, and before the calculation, it is necessary to obtain some required material performance values ​​through material performance experiments, such as processing Hardening index, thickness anisotropy coefficient, etc.

[0007] 2. The test method needs to process sheets of different sizes, that is, a variety of samples are required

The method to realize the complex loading path is essentially divided into two tests, that is, pre-deformation and then bulging. The two tests are not carried out at the same time, and the aging time after sheet metal processing is not considered, and most of the parts are formed at one time or at intervals. The time is very short, so the above complex loading conditions may have a certain impact on the test results due to aging

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