| 摘要 |
PROBLEM TO BE SOLVED: To restrain the occurrence of filming by forming many minute cracks on the surface of the elastic rubber layer of an outer periphery part. SOLUTION: A developing roll 1 is constituted of a core bar 2, a base rubber layer 3 (elastic rubber layer) attached to the outer periphery part of the core bar 2, and a coating layer 4 (elastic rubber layer) applied to the outer periphery part of the layer 3; and the layer 4 is constituted of two layers such as a lower layer 4a on the inside and a surface layer 4b on the outside, and many minute cracks are formed on the surface of the layer 4b. The minute cracks are formed by using a crack forming jig constituted of a cutting roller, a driving roller and a feeding roller. Three rollers are set in parallel with each other by leaving space in between and arranged so that they are respectively positioned at the apexes of a triangle. The crack forming jig is arranged in a heating device capable of heating the entire device. The directions of the formed minute cracks are various and the shape thereof is linear or polygonal, then some of the adjacent cracks contact with each other in a depth direction and some of them do not contact on the surface of the layer 4b. |
