Abstract
The limit drawing ratio is important in manufacturing deep-drawn cylindrical products because it determines the size of the products.
In this paper, a simple method for determining the limit drawing ratio of deep-drawing plastic sheet is proposed. A Rockwell superficial hardness tester (HR15-Y) was used to measure the impression depth with or without a test load and the limit drawing ratio was expressed as a function of the ratio of the two values obtained.
The experimental results indicate that the limit drawing ratio (LDR) for plastic sheet can be given by one of the following formula:
(1) When the material yield conditions follow the maximum shearing stress theory,
LDR=e(h0/hp+0.5)
(2) When the material yield conditions follow the maximum main stress theory,
LDR=1+(h0/hp+0.5)
where h0=impression depth without test load
hp=impression depth with test load
e=natural logarithm
