Core?processing?and?heat?treatment

Mandrel blank after straightening, and 15MM margin left in diameter, so that peeling out surface crack, tensile strength is 900-1000N/MM2. In order to avoid the shank fracture, impact toughness values specified: 17J laterally or in vertical 55J instead.
Mandrel diameter tolerance of + / - 0.05MM is allowed for, in the cross section is 0.02MM, the surface roughness is R0.8um. Annealing: 800-850 ℃, the tensile strength of 900-1000N/MM2. Quenching: 980-1020 ℃, depth of 10-15MM, the mandrel and tensile strength of 1900-2000N/MM2, HRC55-58.: 625-635 ℃ tempering quenching hardness, thermal insulation 2 hours temper. The tensile strength decreased to 1300-1450N/MM2, tempering hardness up to HRC45-58.
Mandrel fabrication process:
A new blank after annealing and foreign purchase plant into the shop, and then in the rotary cutting head with KIESER LING (Germany) for finishing, finishing, polishing sand belt machine polishing by. After polishing, the pipe thread lathe mandrel head and tail, mandrel processed sent by medium frequency induction hardening and tempering treatment.