Patent ID: 7287408
Filing Date: 2007-10-30
Classification: B21D

Abstract:
1. An apparatus for producing a battery case which has a tubular shape with a closed end and which houses an electricity-generating element, the apparatus comprising: a die assembly including: a blanking die having a die hole with a predetermined size; a drawing die having a die hole whose size is smaller than that of the die hole of the blanking die; a redrawing die having a die hole whose size is smaller than that of the die hole of the drawing die; and an ironing die having a die hole whose size is smaller than that of the die hole of the redrawing die, the blanking die, the drawing die, the redrawing die and the ironing die being coaxially arranged in series in the order of the sizes of the die holes of the respective dies, such that the respective dies are inhibited from moving; a first punch which is disposed coaxially with respect to the die assembly so as to be located on one side of the blanking die remote from the drawing die, such that the first punch can be inserted into the die hole of the blanking die and which has a first accommodation hole that extends so as to be coaxial with the die hole of the blanking die; a second punch which is accommodated coaxially in the first accommodation hole of the first punch such that the second punch can be advanced toward the blanking die, which is disposed so as to be insertable into the die hole of the drawing die as a result of the advancing movement thereof from the first accommodation hole, and which has a second accommodation hole that extends so as to be coaxial with the first accommodation hole; a third punch which is accommodated coaxially in the second accommodation hole of the second punch such that the third punch can be advanced toward the blanking die and which is disposed so as to be insertable sequentially into the die hole of the redrawing die and the die hole of the ironing die as a result of the advancing movement thereof from the second accommodation hole; and a moving mechanism which permits the inserting movement of the first punch into the die hole of the blanking die, the advancing movement of the second punch from the first accommodation hole and the advancing movement of the third punch from the second accommodation hole to be performed independently of each other, wherein, with a metal plate positioned between the blanking die and the first punch, the inserting movement of the first punch, the advancing movement of the second punch and the advancing movement of the third punch are carried out sequentially in order by the moving mechanism to sequentially perform: a blanking operation by the first punch and the blanking die on the metal plate so as to form a metal blank having a configuration that corresponds to the die hole of the blanking die; a drawing operation by the second punch and the drawing die on the metal blank so as to form a tubular intermediate product having a closed end and a predetermined depth; and a redrawing operation by the third punch and the redrawing die and an ironing operation by the third punch and the ironing die on the tubular intermediate product so as to form a tubular battery case as an end product having a closed end and a smaller wall thickness and a larger depth than the tubular intermediate product.