PURPOSE: To prolong the service life of a die by forming a nib of a ceramics and a die case of a hot toll steel respectively and installing an intermediately fitting case having an intermediate thermal expansion coefficient between the nib and the case.
CONSTITUTION: A nib 1 is formed of a ceramics such as SiALON, etc., and a die case 3 is composed of a hot steel such as SKD61, etc., and an intermediately fitting case 2 having an intermediate thermal expansion coefficient is put between the above two members. In that time, the nib 1 is brought into contact with the case 2 through a taper part, which has a smaller dia. on the approach side and a larger die. on the relief side. The members of the nib 1, case 2, and case 3 are assembled by interference fitting. Seizing and damage to the nib 1 are eliminated to prolong the service life of the die because of using the ceramics having the excellent high temp. strength and thermal shock resistance and of adoption of the triple structure.
HARA HISAO
OGATA KENJI
