| 摘要 |
<p>PURPOSE:To form a hardened layer to a uniform width and depth by energizing a high-frequency heating coil which moves in follow up to the part to be hardened of a crank shaft at a specific period while rotating the crank shaft at the time of subjecting the pin part and journal part of the crank shaft to high-frequency hardening. CONSTITUTION:The crank shaft is rotated in a direction P around a rotation center 22. The arrival of the center 21 of the pin part 12 of the crank shaft at a point S past a point C is detected by a limit switch 35S and a controller 34 starts energization to the high-frequency surface hardening coil 30 which moves in follow up to the pin part 12. The arrival of the center 21 of the pin part 12 at a point A is detected by a limit switch 35a and the energization quantity is decreased by the controller 34; in succession, the arrival of said part at a point B is detected by a limit switch 35b and the energization quantity of high-frequency current is returned to the original quantity. This energization quantity is continued until the center of the pin part 12 arrives at the point A past the point S and the point T. The energization quantity is decreased again when the center arrives at the point A and this operation is repeated prescribed times, by which the high-frequency hardened layer is formed to the layer having the uniform width and depth without having fluctuations.</p> |
