Developing Unit Press-Fit and Capillary Adhesive Joining
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Solution Overview
Problem
The reduction in size of image forming apparatuses and cartridges has made it difficult to secure a joining space for bonding using traditional methods like limonene, and there are challenges in fixing functional materials such as polyacetal resin that are not melted by limonene.
Innovation Solution
A developing unit design that includes a developing roller, a frame body, a bearing member, and an end portion member with specific geometric features allowing for press-fitting and capillary filling with adhesive, enabling strong joining in limited spaces without requiring large injection ports or melting of all components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the image forming apparatus is reduced in size, then the compactness is improved, but the joining space for bonding becomes insufficient
Solution Approach 1:
The joining space is segmented into two distinct regions: a first region with a press-fit relationship (no gap) and a second region with a capillary phenomenon occurrence space (gap between inner and outer peripheral surfaces). This segmentation allows each region to serve its specific function within the limited overall joining space, enabling compact design while maintaining effective bonding areas.
Solution Approach 2:
Different local qualities are provided in different regions of the joining space. The first region has a press-fit quality (tight fit without gap) for structural support, while the second region has a gap quality that enables capillary phenomenon for adhesive infiltration. This local differentiation optimizes the use of limited space by giving each region its specific functional property.
2Device complexity
If limonene is used for bonding, then the joining process is simplified, but functional materials like polyacetal resin cannot be fixed
Solution Approach 1:
The pressing member is designed with differentiated regions: a first pressing portion that applies pressure to melt and bond resin materials, and a second pressing portion that maintains a non-contact relationship with functional materials like polyacetal resin. This local quality differentiation allows limonene-based bonding to work effectively for compatible materials while preserving the integrity of non-melted functional materials.
Solution Approach 2:
The pressing member is segmented into multiple functional portions: a pressing portion for applying bonding pressure to resin materials, and a non-pressing portion that avoids contact with functional materials. This segmentation enables the bonding process to selectively affect only the intended materials without damaging incompatible functional components.
3Device complexity
If traditional bonding methods are used, then the joining process is simple, but high strength joining cannot be achieved in limited space
Solution Approach 1:
The joining structure is segmented into a press-fit region (first region) that provides mechanical interlocking and structural strength, and a capillary region (second region) that enables adhesive infiltration for chemical bonding. This segmentation combines mechanical and chemical bonding mechanisms to achieve high joining strength within limited space.
Solution Approach 2:
The joining system uses a composite approach combining press-fit mechanical connection (for immediate structural strength) and capillary adhesive infiltration (for chemical bonding strength). This composite joining method achieves superior overall strength by leveraging both mechanical interlocking and chemical adhesion in the limited available space.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This design allows for high-strength joining in compact spaces, preventing adhesive overflow and ensuring that non-melted materials like polyacetal resin are not affected, thus maintaining structural integrity and reducing size constraints.
Implementation Method 1
the second region being inserted into the hole portion with a gap between an outer peripheral surface of the protruding portion and an inner peripheral surface of the hole portion... at least a part of the communication hole and the gap are filled with an adhesive
Data Source
AI summary
In a developing unit, one of a frame body and an end portion member, which sandwich a bearing member rotatably supporting a developing roller in an axis direction of the developing roller, includes a hole portion depressed in the axis direction on a surface facing the bearing member, and the other of the frame body and the end portion member includes a protruding portion inserted into the hole portion. The protruding portion includes a first region that is press-fitted into an inner wall surface of the hole portion, and a second region that faces the inner wall surface with a gap therebetween, and at least the gap is filled with an adhesive via a communication hole that extends in a direction intersecting the rotation axis direction such that the gap leads to an outside of the frame body.