Metallic Shaft Roller Member with Exposed Straight Areas
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Solution Overview
Problem
In image forming apparatuses, the rotational sliding resistance of cylindrical-shaped metallic shafts used in charging rollers is high due to projection and depression areas, which hinders the rotational support and increases the risk of image failure.
Innovation Solution
A roller member with a metallic shaft covered by a conductive resilient layer, where the shaft has opposing end portions with straight areas and projection/depression areas, with the projection and depression areas entirely covered and at least part of the straight areas exposed, reducing the contact with bearings and thus minimizing sliding resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If projection and depression areas are provided on the mating portion to increase the strength of the metallic shaft, then the strength of the metallic shaft is improved, but the bearing portion is caught by the projection and depression area, causing rotational sliding resistance to increase
Solution Approach 1:
The harmful projection and depression areas are extracted from the bearing contact region. The straight area is designed to extend beyond the projection and depression area in the axial direction, creating a clean contact surface for the bearing that is free from the problematic geometric features, thus eliminating the source of high sliding resistance while preserving the strength-enhancing projections and depressions in the mating portion
Solution Approach 2:
The metallic shaft is segmented into distinct functional zones: the mating portion with projection and depression areas for strength, and the straight area extending beyond it for bearing support. This segmentation allows each zone to fulfill its specific function without interfering with the other, resolving the contradiction between strength and low sliding resistance
2Ease of manufacture
If the metallic shaft is made with a simple cylindrical shape, then the manufacturing process is simplified, but the strength at the mating portion is insufficient
Solution Approach 1:
The metallic shaft employs local quality by providing projection and depression areas only at the mating portion where strength is needed, while maintaining a smooth cylindrical shape in the straight area for bearing contact. This localized modification achieves the required strength without complicating the overall manufacturing process
Data Source
AI summary
A roller member used in an image forming apparatus including: a metallic shaft; and a covering layer, wherein the metallic shaft has a cylindrical shape formed so that one end portion and the other end portion of the metallic plate oppose each other, the one end portion and the other end portion each include a straight portion, a projection, and a depression, the projections on the one end portion engage the depressions on the other end portion, a straight area is located outside a projection and depression area in which the projection on the one end portion and the projection on the other end portion are aligned in an axial direction of the metallic shaft, and the projection and depression area is entirely covered with the covering layer and at least part of the straight area is exposed from the covering layer.