| 摘要 |
PURPOSE:To ensure a stable touch of a head even with a long period of use by forming a pad surface having a curvature approximately in the circumferential direction (revolving direction) of a sheet on the contact surface between a pad and the sheet and having different curvatures of the pad surface between a pad at the inlet side of the sheet and a pad at the outlet side of the sheet. CONSTITUTION:Pads 3a and 3b having a curvature R approximately in the circumferential direction of a sheet 2 are provided at both ends of a head 1 moving in the radius direction of the sheet 2 while holding the sheet between at the opposite side to the head 1. When the sheet 2 is revolved toward an arrow (a), air films 4a and 4b are formed between pads 3a and 3b and the sheet 2 during revolutions of the sheet 2. However a turbulent flow is produced with the pad 3b at the outlet side and therefore the thickness (h) of the film 4b is reduced. Thus the air film is not produced easily. In this connection, the curvature R2 of the pad 3b is set larger than the curvature R1 of the pad 3a in order to increase the thickness (h). As a result, the stable film 4b can be obtained even on the surface of the pad 3b. |
