| 摘要 |
PURPOSE:To perform in-furnace coating soldering excellent in paint adhesiveness in good efficiency, by a method wherein a steel material is soldered in a high temp. furnace while the soldered material is heat treated to enhance the strength thereof and electrodeposition coating is succeedingly performed. CONSTITUTION:A steel material to be soldered is charged into the work charging chamber 2 of a soldering furnace 1 and transferred through a preheating chamber 2 by an endless conveyor 6 running in said chamber 2. After the steel material is preheated by the heater 302 in the preheating chamber 2, the preheated steel material is transferred through a heating chamber 4 and heated to 800-1,200 deg.C by a heater 402 to be subjected to soldering treatment. In order to enhance tensile strength lowered by this heat treatment, the heated steel material is cooled to 400-560 deg.C at once in a cooling chamber 5 by gas while the cooled steel material is charged into the cooling liquid 701 in a heat treatment chamber 7 and quenched to enhance tensile strength. Succeedingly, the steel material is drawn up from the heat treatment tank 7 by a conveyor 703 and, after drying by self-holding heat, passed through the aqueous paint 804 in the electrodeposition tank 803 of a painting apparatus 8 by a conveyor 9 to be subjected to electrodeposition coating while the paint is baked to the steel material in a baking chamber 805.
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