Method and apparatus for quenching a tubular workpiece

An apparatus for quenching a tubular-workpiece, comprising plural rolls which are in contact with the workpiece along a length thereof and at three or more points about a circumference thereof;

• a cooling means for supplying cooling liquid to the workpiece;
• a pressing means for pressing at least one of the rolls against the workpiece;
• a thermometer for measuring temperature of the workpiece;
• a pressure signal generating means for generating a setting input signal in dependence on the temperature measured by said thermometer;
• and a pressure controller for controlling said pressing means independence on said setting input signal to control the pressure of said at least one roll against the workpiece.

an apparatus for quenching a tubular workpiece, comprising a set of dies, each of which has plural projections and plural recesses formed on an inner face thereof;

• a press removably mounted to said dies for pressing at least one of said dies against the workpiece;
• cooling liquid blow holds formed in at least one of said dies and opening into said recess;
• a pressure controller for controlling the pressure of said at least one of said dies against the workpiece by changing a setting input for the pressure during the quenching;
• a thermometer for measuring temperature of the workpiece and a pressure signal generating means for generating said setting input in dependence on the temperature measured by said thermometer.

A method of quenching a workpiece, comprising the steps of:

• holding the workpiece in a quenching location;
• quenching the workpiece while the workpiece is held in said quenching location;
• pressing a pressure member against the workpiece so as to apply a warp constraining force thereto during quenching;
• and
• during the quenching step, continuously increasing the warp constraining force applied to the workpiece by adjusting said pressure member to increase the warp constraining force applied thereby against the workpiece in correspondence with an increase of an elasticity limit stress due to a temperature decrease of the workpiece caused by the quenching.

An apparatus for quenching a workpiece, comprising:

• a holding device for holding the workpiece in a quenching location;
• cooling fluid supply means for applying cooling fluid to the workpiece at the quenching location for quenching the workpiece;
• a pressure member for pressing against the workpiece so as to apply a warp constraining force thereto during quenching of the workpiece;
• and
• pressure control means for, during the quenching step, continuously increasing the warp constraining force applied to the workpiece by adjusting said pressure member to increase the warp constraining force applied thereby against the workpiece in correspondence with an increase of an elasticity limit stress due to a temperature decrease of the workpiece caused by the quenching.