| 摘要 |
<p>PURPOSE:To control a steel pipe to a specified heating temp. in the stage of heating the moving steel pipe to the specified temp. by correcting the set value of a heat input setter to an adequate value when the pipe end comes within the heating range by an induction heating coil or when the speed of the steel pipe changes. CONSTITUTION:A steel pipe 1 transferred in an arrow direction is inductively heated by a high-frequency induction coil 2. A detector 8 for the transfer speed of the pipe 1 and a pipe end detector consisting of a light emitting element 10A and a photodetector 10B are disposed just before the coil 2. A setter 4 which sets the quantity of heat input to the pipe 1 from the outside diameter, wall thickness and material of the pipe 1, external temp., etc. is provided and is connected to an arithmetic circuit 11. When the heating range (l) of the coil 2 is totally the steel pipe, the steel pipe is heated in accordance with the setter 4. When the transfer speed of the pipe 1 changes or the pipe end comes to said range, such change or the pipe end is detected and the quantity of heat input is corrected in the circuit 11 by increasing or decreasing the quantity of the heat input with a change in the speed or decreasing the volume of when the pipe end comes within the heating range (l) of the coil 2, by which the electric power input to the coil 2 from a high-frequency power source 3 is adequately controlled.</p> |
