JPS56144824A - Forming method for sheet material into round cylinder - Google Patents

Abstract

PURPOSE: To form a sheet material into a round cylinder while causing a material flow within the sheet material so as to make a parallel groove with a small gap, by feeding a sheet material into the gap between a rotating core roll and an external roll rotating with larger circumferential velocity than that of the core roll.

CONSTITUTION: A heat sheet material 11 is fed into the gap between a core roll 13 having outer diameter approximately equal to inner diameter of the completed cylindrical product 11a and an external roll 14 made of a hard elastic material. Hereupon, the advancing direction of the sheet material 11, the advancing direction 16 of the surface of core roll 13, and the advancing direction 17 of the surface of external roll 14, are all made the same, by rotating the core roll 13 in the opposite direction to the rotation of the external roll 14; besides, the circumferential velocity of the external roll 14 is made faster than that of the core roll 13. Hereby, the ratios between the advancing velocity of the sheet material 11 and the circumferential velocities of the core roll 13 and the external roll 14 become different so that the skin of the sheet material 11 on the external roll 14 side is more strongly dragged than the skin on the core roll 13 side, and thereby a material flow is caused within the sheet material 11, which results in a completed round cylinder formed with a good roundness around the core roll 13.

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