• 한국자동차공학회논문집
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• 제2권1호
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• pp.73-83
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• 1994

Press formabilities of aluminum sheets for automobile body were investigated. Plane strain stretching test (called RIST-PSST), cupping test and U bending test were performed to assess the press formability of aluminum sheets respectively. The results showed that aluminum sheets are generally inferior to cold-rolled steel sheet of deep drawing quality (CSP3N) in press formability. The limiting punch height (LPH) and limiting plane strain (FLCo) of aluminum sheets are 50%-70% level compared to that of CSP3N. Moreover, the limiting drawing ratios(LDR) of aluminum sheets are ranged between 1.95 and 2.1. The poor press formability of aluminum sheets is responsible for low values of total elongation and plastic anisotropy parameter in tensile characteristic. The shape fixability of aluminum sheets evaluated in U bending test is very poor due to its low elastic modulus compared to CSP3N.

• 한국정밀공학회지
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• 제13권5호
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• pp.53-59
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• 1996

Warm deep drawing of single-action dies using local heating has appeared to be an alternative attractive production method of multi-operation die sets generally used at room temperature in deep drawing of rectangular cup. Uniaxial tensile tests and deep drawing tests of various materials are carried out and the effect of temperature on tensile properties and drawability are examined at temperatures up to 200 .deg. C under three kinds of lubricants of teflon film, vinyl film and drawing oil. Good formability is achieved when punch and die temperature were differentiated intentionally in order to get large tensile strength(TS) at punch shoulder protion and small TS at die side. Throughout the experiments, it has been shown that the limiting drawing height of STS316L was increased with heating die and blank holder at 100 .deg. C, but that of STS430 wasn't. When vinyl or teflon film was attached on the plates, the drawability was increased considerably.

• 산업기술연구
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• 제19권
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• pp.67-74
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• 1999

The mechanical properties including forming limit and deep-drawability of commercially-used sheet metals were experimentally estimated in this study. Uniaxial tensile test to obtain basic mechanical properties was carried out, followed by limiting dome height (LDH) test and forming limit diagram (FLD) test to quantitatively evaluate the sheet-formability. Deep drawing and reverse drawing tests were also performed to find out the critical values of the blank holding force and the gap between the die and the blank holder which enabled the deep drawing and reverse drawing of a successful cop without any wrinkle or fracture. The thickness of the cup wall along the rolling-, transeverse- and $45^{\circ}$-directions was measured and compared with one another. And the punch force-stroke curve and the critical punch force expected from the theory coincided with the experimental result very well for mild steel while not for aluminium alloy.

• 대한기계학회논문집
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• 제17권12호
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• pp.3094-3104
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• 1993

The five punch and die sets are selected as the examples of arbitrary cross sections which have two opposite inclined sides. Two kinds of blank shapes are designed for all cross sections. One(h-b1.) is determined by slip-line theory and the other (G-b1.) is determined conventionally as the similar shapes with the cross sections which were used by Gopinathan. As a result of the experimental procedures, the superiority of the blank shapes designed by slip-line theory is verified in the limiting drawing ratio, the uniformity of cup height and the thickness distributions.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1995년도 춘계학술대회 논문집
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• pp.209-214
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• 1995

This paper describes that the effects of punch speed and temperatures of the die and the blank holder on the drawability are examined. Up to now, multi-stage of dies sets have been used generally at room temperature in deep drawing of rectangular shaped components. But using local heating, it is shown that one stage of die set was capable of deep drawing and the drawability was increased and sheet thickness of component was drawn somewhat uniformly. Rectangular deep drawing experiments on two kinds of stainless steel STS316L, STS430 of 1.0 mm thickness have been conducted using local heating. The limiting drawing height can be increased by heating the die and the blank holder up to 100 .deg. C at STS316L. Commercial lubricants hadn't an effect on drawability in rectangular deep drawing, but vinyl and teflon film had an effect on it.