Flexible die for stretching and bending shaping fracture

Abstract

The invention provides a flexible die for stretching and bending forming fracture. The die comprises a punch insert block, a punch insert block seat, an insert block seat fixing baffle, a lower plate, a guide block, a blank holder, a matrix, a draw bead, a displacement sensor fixed slot and a displacement sensor stay wire positioning pin. According to combination of two data acquisition apparatuses for punch insert block pressure and for matrix displacement, bearing state of a plate can be analyzed through pressure variation of the punch insert block, and a shaping depth of the plate can be analyzed through measuring of the matrix displacement, so as to comprehensively compare and analyze characteristics of different shaping fracture modes of advanced high strength steel. Characteristics of different shaping fracture modes can be compared conveniently and effectively to satisfy requirements of research on shaping shearing fracture characteristics of an advanced high strength steel automobile plate.

Description

technical field [0001] The invention relates to a mold in the technical field of plastic forming, in particular to a flexible stretching and bending forming fracture feature mold. Background technique [0002] Advanced high-strength steel has lower yield ratio, better strain distribution ability, and higher strain hardening characteristics; at the same time, this type of steel also has better collision characteristics and higher fatigue life. Therefore, advanced high-strength steels have broad application prospects in the lightweighting of the automotive industry. However, experiments have found that shear fractures are prone to occur near the fillets of the punch and die during the stretch-bending process of advanced high-strength steels. The necking fractures observed are significantly different from the other and are unique to advanced high strength steels. The forming limit curve established based on the material necking instability theory cannot predict this kind of f...

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Problems solved by technology

[0003] After searching the literature of the prior art, it was found that Ji Hoon Kim et al published a paper "The shear fracture of dual-phase steel" ("Shear fracture of dual-phase steel") in the journal "International Journal of Plasticity" in 2011, In this paper, the thermodynamic finite element model is used to simulate and analyze the draw-bend experimental results of several high-strength dual-phase steels with different strength levels. This study mainly considers the influence of temperature factors on the forming results, but the experimental equipment used is not only bulky, but also And it is too complicated, which is quite different from the equipment used in the traditional stamping forming process

B.S.Levy and C.J.Van Tyne used the stress-based forming limit curve to predict the forming results of several high-strength double steels, and verified the above results with the ASB (Angular stretch bend) test, but the insert height of the ASB test device Larger, inconvenient to replace; and it is difficult to accurately measure the forming depth of the sample (relevant literature: B.S.Levy, C.J.Van Tyne. Predicting breakage on a die radius with a straight bend axis during sheet forming. Journal of Materials Processing Technology, 2009, 209 :2038-2046.)

Danielle Zeng, Z.Cedric Xia et al. studied the shear fracture mechanism of high-strength dual-phase steel, and analyzed the characteristics of high-strength dual-phase steel shear fracture relative to necking fracture by comparing the experimental and simulation results. However, its experimental equipment is relatively large, resulting in a large size of the experimental sample, low economy and convenience of the experiment, and poor symmetry of the experimental equipment (relevant literature: Danielle Zeng, Z.Cedric Xia, Hua-Chu Shih ,Ming F.Shi.Development of Shear Fracture Criterion for Dual-Phase Steel Stamping.SAE2009-01-1172.)

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