| 摘要 |
<p>PURPOSE:To make excellent both dimensional precision and external appearance for product, and to improve the life of die, etc., at the time of plastic working for hard workability metal materials like SUS steel by means of part former, header and wire drawing machine. CONSTITUTION:A high frequency induction heating device 10 or direct electrical heating device 20 is arranged in front of a header 1, heating SUS304 steel to the prescribed temp. and forging bolt parts. Both dimensional precision and external appearance are good in the heating temp. range of 80-250 deg.C, rather defective for external appearance at 300C, defective for external appearance at 400 deg.C. On the other hand, dimensional precision at 50 deg.C becomes defective. In the case of over 80 deg.C of heating temp. the die life is improved more than double as compared to that of cold working. In the case of high frequency induction heating and direct electrical heating, use of a high frequency electric current under 300kHz prevents local heating of surface, obtaining good external appearance.</p> |
