| 摘要 |
<p>PURPOSE:To prevent hardening failure and damages of a hardening device owing to improper hardening positions by starting high-frequency heating when a material to be hardened enters the correct hardening position between an upper center and a lower center in subjecting the material to be hardened to high-frequency hardening. CONSTITUTION:After the central part of the bottom surface of a material 12 to be hardened is engaged to the leading end part of a lower center 13, an upper center 9 descending together with an elevating spindle 7 is engaged to the central part of the top surface of the material 12, whereby the material 12 is set in the correct position to be hardened by high frequencies. At this time, electric circuits are formed by a choke coil 5, a DC regulated power supply 2, a relay 3, a variable resistor 4, the ground, a lower center stand 14, the lower center 13, the material 12, the upper center 9 and a choke coil 5, whereby the relay 3 is energized. A high-frequency heating coil 11 is energized and controlled by the operation of the contacts of the relay 3, whereby the hardening operation is carried out only in the correct hardening position, and the hardening failure and the damaging of the hardening device at the abnormal heating patterns by wrong positions are prevented.</p> |
