| 摘要 |
PROBLEM TO BE SOLVED: To enable a long time operation at a high temperature preventing disconnection between a heater and a lead wire by applying a low voltage and high current to a resistor heater made of a metal mainly composed of iron. SOLUTION: An electric heating device 1 is formed of a heater 3, a terminal 2, and an insulating layer 4 made of ceramics and for covering the whole surface of the heater 3 except for the terminal 2 fitting part. The heater 3 is formed by cutting zigzag a rectangular flat plate of iron. Voltage is applied between the terminals 2, 2 so as to heat the heater 3. The alternating current power source voltage at a low frequency from a power source at AC 200 V is converted to the direct current voltage by an initial stage rectifier unit, and continuously, inverted to the alternating current voltage at a high frequency by a high frequency converting unit. This high frequency alternating current voltage is stepped down to the low voltage by a transformer, and converted to the direct current by a final stage rectifier unit. 5 V of low voltage and 100 A of high current are desirably applied to the heater 3. The heater 3 is formed of a strip iron plate having a large cross sectional area, and it can not be cut by burning at 700-800 deg.C of the heating temperature of a manifold M in the case of injection forming the metal with a hot runner mold.
|
