METHOD AND DEVICE FOR PRODUCING METAL SPRINGS

摘要

The present invention comprises: a temperature increase step of causing the temperature to rise to a predetermined nitriding process temperature; a first nitriding step of supplying ammonium gas to provide a high nitriding potential while maintaining the nitriding process temperature; a nitriding potential decrease step of decreasing the nitriding potential to a low level sufficient to avoid formation of a compound layer on a metal spring main body by stopping the supply of ammonium gas and supplying hydrogen gas and nitrogen gas at a ratio of 3:1 while maintaining the nitriding process temperature; and a second nitriding step of maintaining the nitriding process temperature and the low nitriding potential. It is believed that if the first nitriding step is continued for a predetermined duration or longer, the high nitriding potential will cause formation of a compound layer on the metal wire spring main body. Accordingly, the duration of the first nitriding step is set shorter than the predetermined duration.