To make the temperature in an annealing furnace having an opening for welded parts uniform by installing a conveyance means for conveying the welded parts on a prescribed route, an infrared ray lamp for heating the welded parts, and a circulating means for circulating temperature in the furnace.
In an annealing furnace 2 having an opening 5, welded parts 4, 4 are moved vertically elevators 6Vf, 6Vb as a vertical conveyance means and moved horizontally by roller conveyers 6Lt, 6Lm, 6Lb as a horizontal conveyance means. A lot of infrared ray lamps 9, 9... are installed above each horizontal conveyance means 6Lt, 6Lm, 6Lb. An upper part 3a is connected with a lower part 3b by a duct 10, and a circulating fan 11 is installed in the upper part 3a. The welded part 4 is moved alternately on the routes of the opening 5a → horizontal conveyance means 6Lt → 6Lm and the opening 5a →horizontal conveyance means 6Lt → 6Lb to be transferred to the opening 5a so that the temperature in the furnace is made uniform by the fan 11.
SAKANO KAZUYOSHI
KAGEYAMA HIROYUKI
GYOTOKU SEIICHI
