Steel knives for cutting glass gobs - where cutting zone is fully hardened but shaft is tempered to spring hardness to increase performance and life of knife

摘要

Knives are used in pairs moving towards each other to cut gobs from a continuous glass stream. Each knife is made of highly alloyed steel sheet, where the cutting zone consists of hardened steel, and has a V-shaped edge and a bent profile. Cutting zone blends into a tapered shaft possessing spring hardness and employed to fix the knive on a holder. Cutting zone pref. has a hardness of 56-64, esp. 60-63 HRc; whereas the shaft has a hardness of 40-50 HRc, esp. 45-48 HR. The edges of the tapered shaft are pref. bent in a curve which blends into the profile used on the cutting zone. Knives which can operate at a higher number of strokes/minute, have increased life and can cut gobs up to 600 g wt.