| 摘要 |
PROBLEM TO BE SOLVED: To make the paper contact pressure of the end part and central part of a rubber roller almost same mutually and to enhance the coefficient of fiction of the whole to obtain large feed force by making the spring constant of the rubber of the end part of the rubber roller wherein a shaft is inserted into a tube of which the surface is composed of rubber larger than that of the central part thereof. SOLUTION: A rubber roller 11 is, for example, constituted by inserting a shaft 3 into a tube at least of which the surface is composed of rubber and the tube 21 may be one wherein a rubber layer 41 is formed on the surface of a hard resin layer 51 or one entirely composed of rubber. The ratio LA/LB of the length LA of the end region A of the rubber roller in the axial direction of the shaft 3 and the length LB of the central part B thereof is set to 0.1-1.4. The ratio HA/HB of the hardness HA of the rubber layer 41A in the end region and the hardness HB of the rubber layer 41B in the central region is set to 1.05-1.50, pref., 1.10-1.40. Since the spring constant of the rubber of the end part is larger than that of the rubber of the central part, large feed force can be obtained. |
