PURPOSE: To adapt the spring back of the skirt edge portion after forming process to be in the inward direction, by causing the portion to become the skirt edge to be inwardly bent by a recess portion provided at the upper edge of the reducing surface of the die and a projection provided at the lower edge of the internal wall surface of the blank holder.
CONSTITUTION: The upper edge of the reducing surface 28 of the die 24 is cut off and a recess portion 44 is thereby provided, and a projection 45 to fit in the recess portion 44 is provided at the lower edge of the internal wall surface of the blank holder 33 integrally therewith. The portion 53 to become the skirt edge is inwardly bent when the portion 52 to become the mask skirt of the shadow mask blank 51 is clamped and pressed by the die 24 and the blank holder 33. The portion 54 to become the spherical portion is bulged out when the punch 38 is lowered with the portion 52 to become the mask skirt kept as clamped with pressure. Then, with the clamping pressure released, the punch 38 is further pushed down along the reducing surface 28 of the die 24, and thus, the portion 52 to become the mask skirt undergoes the reducing process until the same reaches the level below the recess portion 44.
ISHIDA TADAYOSHI
SUMIYOSHI SEISHIYOU
| JPS5498567A | 1979-08-03 | |||
| JPS54157470A | 1979-12-12 |