| 摘要 |
<p>PURPOSE:To manufacture the high frequency bend tube of a small bend radius, which can hold <=Hv 248 in a state of bending, and <=Hv 207 as the case may be, and also, can select a working speed of the maximum efficiency. CONSTITUTION:In the method for allowing a steel tube of a prescribed component composition to be subjected to high frequency induction heating to 850-1050 deg.C, and manufacturing a bend tube whose bend radius is <= three folds of the tube outside diameter, while executing water cooling, a relation of a carbon equivalent, a working speed of the steel tube, and the maximum hardness after the working processing is derived in advance, and based on the relation concerned, the working speed is determined in accordance with the carbon equivalent of the steel tube so as to satisfy prescribed hardness, and bending is executed. By selecting the working speed in accordance with the carbon equivalent of a tube stock, a high frequency bend tube of a small bend radius of prescribed hardness or below can be manufactured at a necessary and sufficient working speed in a state of high frequency bending, and the cost can be curtailed remarkably.</p> |
