INTERNAL WELD TRIMMER AND METHOD OF ITS THERMAL PROCESSING Russian patent published in 2011 - IPC B23K37/08 C21D1/18 C21D9/18 C22C38/36 

FIELD: metallurgy.

SUBSTANCE: tool is made from alloyed tool steel containing the following components in wt %: carbon - 2.00-2.20; chromium - 11.0-12.0; tungsten - 0.50-0.80; vanadium - 0.15-0.30; molybdenum - 0.60- 0.90. Stepped flat knife from alloyed tool steel is arranged on working face of cylindrical male mould along its lengthwise axis and features straight and skewed inward cutting edges. Distance between cutting edges and cylindrical male mould length exceeds maximum weld trimmer crosswise thickness. Cylindrical male mould and flat knife share outer surface with its diametre not exceeding minimum inner diametre of the tube with due allowance for tolerable height of nearby weld trimmer. Flat knife step height equal half the diametre of cylindrical male mould. Trimmer thermal processing includes hardening made in steps by preheating to 200-300°C and subsequent heating to 1020-1050°C salt bath, and one-run tempering at 400-500°C for at least 3 hours along with cooling in air.

EFFECT: tool higher life and reduced wear in producing drill pipe with welded locks.

2 cl, 2 dwg