Method for improving bowl opening of straightened end of drill collar steel

The invention relates to a method for improving an end bowl opening of straightened drill collar steel, and belongs to the technical field of drill collar steel production processes in the metallurgical industry. According to the technical scheme, seven-roller straightening is adopted, the rolling reduction of 1 # upper and lower rollers and 3 # upper and lower rollers is 4-5 mm, and the rolling reduction of 2 # upper and lower rollers is 1-2 mm; the anti-bending amount is 15 to 16 mm; the angles of the straightening rollers are as follows: the angle of a 1 # upper roller and a 1 # lower roller is 29.5-30 degrees, the angle of a 2 # upper roller is 30-31 degrees, the angle of a 3 # upper roller is 29.5-30 degrees, and the angle of a lower roller is 32-32.5 degrees; and the straightened end of the round steel is chamfered, the chamfering angle ranges from 30 degrees to 45 degrees, and the chamfering length ranges from 1 mm to 2 mm. The method has the beneficial effects that the internal structure stress of the