Liquid-Ejecting Head Secondary Molding Resin Intrusion Prevention
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Solution Overview
Problem
In the manufacturing of liquid-ejecting heads, the die slide injection molding process can cause deformation and volume reduction of hollow areas, leading to reduced reliability due to resin flow into these areas during secondary molding, affecting the precision and efficiency of liquid paths.
Innovation Solution
A method involving a main mold and a sliding die mold where the distance between the resin injection area and the opening is greater than the gap between the inner and outer surfaces, preventing resin flow into the liquid paths during secondary molding by maintaining a sufficient distance and ensuring proper alignment and connection of parts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If resin is injected at high pressure during secondary molding to connect parts, then connection strength is improved, but hollow areas deform and volume is reduced
Solution Approach 1:
A resin non-injection area acts as an intermediary barrier between the resin injection area and the hollow area. This barrier prevents direct resin flow into the hollow area while still allowing the injection pressure to effectively connect the parts. The convex section and opening configuration creates a controlled interface that mediates between the high-pressure injection process and the sensitive hollow structure.
Solution Approach 2:
The mold is designed with spatially varying properties: a resin non-injection area with specific dimensions is created adjacent to the hollow area, while the convex section and opening are positioned with precise dimensional relationships. This local differentiation allows high-pressure injection in some areas while protecting specific hollow areas from resin intrusion, enabling both strong connections and precise volume maintenance.
2Productivity
If resin injection pressure is increased during secondary molding, then manufacturing efficiency is improved, but liquid path volume accuracy deteriorates
Solution Approach 1:
The resin non-injection area serves as a protective intermediary that allows high-pressure resin injection to proceed efficiently while preventing resin from entering the liquid path hollow areas. This enables maintaining high injection pressures for manufacturing efficiency without compromising the volume accuracy of the liquid paths.
Solution Approach 2:
The mold design incorporates localized features including a resin non-injection area positioned adjacent to hollow areas forming liquid paths, with specific dimensional relationships (distance greater than wall thickness). This local quality differentiation enables high-pressure injection throughout most of the mold while protecting specific regions to maintain liquid path volume accuracy.
3Ease of manufacture
If die slide injection molding is used to form complicated internal construction, then ease of manufacture is improved, but part deformation occurs during secondary molding
Solution Approach 1:
The resin non-injection area acts as a protective barrier during secondary molding, preventing resin from forcing its way into pre-formed hollow areas. This allows the die slide injection molding process to successfully create complicated internal constructions without causing deformation of existing hollow structures during the connection phase.
Solution Approach 2:
The mold is pre-configured with a resin non-injection area and properly positioned convex sections before secondary molding begins. This preliminary arrangement of mold features ensures that when high-pressure resin injection occurs, the protective barriers are already in place, preventing deformation of hollow areas formed during primary molding.
Data Source
AI summary
Provided is a method for manufacturing a liquid-ejecting head whereby in die slide injection molding it is possible to stably inject resin in secondary molding without damaging the shapes of parts that were formed in primary molding. In order for that, in the connecting section in which a convex section of a cover member is inserted into an opening of a liquid-supply member, the closest distance to the opening in the area where secondary resin is injected is made larger than the gap between the opening and the convex section. As a result, the resin is prevented from flowing into a liquid path during the secondary molding.