METHOD OF MAKING DRILLING STRING LOCK PART BILLETS Russian patent published in 2012 - IPC B21K21/00 B21J1/04 

FIELD: process engineering.

SUBSTANCE: invention relates to machine building, particularly, to making drilling string lock parts from thick-wall tubes with ID-to-OD ratio of 0.1-0.9.Tubes represents off-grade scrap and wastes of structural steels doped by chromium, nickel, molybdenum and vanadium with carbon content making 0.25-0.43 %. Tubes are subjected to chemical analysis, visual, measurement and ultrasound control. Then, tube with strength and impact resistance of steel are cut into initial ring billets. Heated initial billets are forged in tools with contact surfaces to sizes of string lock part billet increased by machining allowance. Then, produced forged pieces are annealed and subjected to roughing. Now, carried out are ultrasound control and thermal processing to strength class 735. Thermally processed forged pieces are finished to sizes of string lock part billets.

EFFECT: possibility to use grade scrap and wastes of structural steels.

5 cl, 11 dwg, 2 tbl, 1 ex