PURPOSE: To provide the titled drum free of voids or exposure of metal at a stepped portion by a method wherein after heating the weld to a specified temperature and fixing a correction film to the weld by a pressing roll of elastic body, the weld is reheated to a higher temperature for thermowelding the correction film.
CONSTITUTION: The metal drum 1 is preheated at an around its weld 1a, by a preheating HF induction coil 10, to the temperature which is 10W100°C higher than the tack point of the correction film 3 (or thermowelding layer, in the case of a laminate). Next, the drum 1 together with the correction film 3 is passed between a support roll 8 and a pressing roll 4 of elastic body to fix the film 3 to the inside surface of the weld 1a, and then the weld 1a is heated by a post-heating HF induction coil 11 to the temperature higher than the preheating temperature so as to thermoweld the film 3 perfectly. Accordingly, the correction film can be thermowelded with high bonding strength without generation of voids, pores, exposure of metal at the stepped portion, elongation and cutting of film, or the like.
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IMATANI TSUNEO
ISHIBASHI KAZUHISA
TOYOSHIMA MAKOTO
