JPS57155572A - Heating roll for fixing device - Google Patents

Abstract

PURPOSE:To provide a roll which withstands bending load thoroughly despite the average decrease in thickness, is decreased of heat capacity and is reduced of warm-up time by forming the heating roll core to the wall thickness thicker in the central part of the roll and thinner gradually toward the end part. CONSTITUTION:A metallic heating roll 1 is hollow, and its core part 2 of a cylindrical shape in outside circumferential surface and both end shaft parts 3 are coupled to one body in disc parts 4. The inside circumferential surface 5 of the core part 2 is formed to a tapered shape of the inside diameter increasing gradually toward the center of the core part 2 from the parts adjacent to the parts 4. Despite the slight increase in the wall thickness at the center of the roll core width and the increase in the bending ridigity of the heating roll, the wall thickness of the roll core is smaller toward both ends of the roll core and therefore the heat capacity of the heating roll can be made smaller than that for the prior art and the fixing device of a short warm-up time is obtained with no increase in the capacity of an electric power source.