| 摘要 |
<p>PURPOSE:To stabilize tempering temp. and to stabilize the surface hardness after the tempering by providing a control device which controls the rate of supply of quenching water to a high frequency hardening device which accomplishes tempering by remaining heat. CONSTITUTION:A product 2 supported with upper and lower centers 1, 1' is inserted into a hardening coil 3, and is electrically heated, whereafter cooling water is ejected from the cooling water ejection holes 3' opened on the inside surface of the coil 3 to harden the product 2. The input side of a microcomputer 11 as a control device in this case is connected to an integrating meter 6 for electric power, a thermometer 6 for measuring water temp. and a flowmeter 9 for measuring the flow rate of cooling water, the output sides whereof are connected to a control valve 10 for the supply of the cooling water. The quantity of the heat deprived of by quenching water is calculated, and the valve 10 is so controlled that the difference between the calculated value and the quantity of heat in the high frequency heating attains a prescribed value. The remaining heat after the high frequency heating is thus made constant.</p> |
