METHOD OF STRAIGHTENING OF STEEL THIN-WALLED PIPED COMBINED WITH TEMPERING Russian patent published in 2015 - IPC B21D3/16 C21D9/08 

FIELD: machine building.

SUBSTANCE: method of heat treatment with simultaneous straightening of steel thin-walled pipes with separating partition along the inner diameter includes pipe heating in the furnace for tempering, straightening using the mandrel, holding at the preset temperature and cooling. The straightening is performed using two mandrels with sliding sectors and with the cylinder piston, the motion of which by means of compressed air pressure through lever system provides the travel of sliding sectors of the first mandrel in a radial direction. A temper heating of the pipe is performed in the furnace without a mandrel. Before unloading of the heated tube from the furnace on its upper side the heated to the same temperature the cylindrical process steel screen with gripping, heated to the same temperature, is put on and connected with the pipe with the help of sockolets. The pipe with screen is unloaded from the furnace with the gripper. The pipe is lowered onto the immobile first mandrel and it is placed inside the pipe bottom with the subsequent fixation on the first mandrel for correcting the pipe shape by means of radial move of sliding sectors. The process steel screen is removed from the pipe top and the second mandrel is placed inside the pipe top with its fixation on internal surface of the pipe top. The compressed air is supplied to the piston of the second mandrel for the form correcting. Then the accelerated cooling of the pipe with the help of compressed air supply to the external surface of the pipe is performed. After that the compressed air supply to the pistons of the first and second mandrels is commuted for shifting of sliding sectors of the first and second mandrels along the radius towards the centre of mandrels to cancel the direct contact with the internal surface of the pipe. After that from the pipe top the second mandrel is removed, and the pipe is removed from the first fixed mandrel.

EFFECT: ensuring of accurate geometrical sizes of thin-walled pipes during tempering, reliable obtaining of required complex of mechanical properties and hardness of pipes, according to specifications.

2 cl, 1 ex