Metal-Resin Joint Surface Texturing for Airtight Molding
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Solution Overview
Problem
Conventional methods for joining metal and resin materials fail to secure sufficient airtightness at the joint portion.
Innovation Solution
A metal-resin composite molded product is formed by irradiating the metal member with a high-energy beam to create a surface texture with an arithmetic mean peak curvature of 2500 to 5000 (1/mm), followed by injection-molding the thermoplastic resin to enhance adhesion and airtightness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional joining methods (gluing, screwing) are used to join metal and resin, then the joining process is simple, but airtightness at the joint portion is insufficient
Solution Approach 1:
The metal surface is pre-processed with laser irradiation to create a specific roughness profile (Rz: 3-10 μm, Ra: 1-3 μm) before the resin is applied. This preliminary surface treatment creates anchor points and increases surface area, enabling the resin to mechanically interlock with the metal surface, thereby achieving sufficient airtightness without requiring additional sealing components or complex joining procedures.
Solution Approach 2:
The invention changes the physical parameters of the metal surface by controlling its roughness within specific ranges (Rz: 3-10 μm, Ra: 1-3 μm) through laser processing. By optimizing these surface parameters, the joint strength and airtightness between metal and resin are significantly improved, resolving the contradiction between simple joining and sufficient sealing performance.
2Reliability
If laser processing is used to create surface texture, then airtightness is improved, but the processing time and energy consumption increase
Solution Approach 1:
The invention optimizes laser processing parameters (power, speed, pulse duration) to achieve the required surface roughness (Rz: 3-10 μm, Ra: 1-3 μm) within a practical processing time. By carefully controlling these parameters, sufficient airtightness is achieved without excessive energy consumption or processing time, balancing quality with efficiency.
Solution Approach 2:
Instead of processing the entire metal surface uniformly, the laser is applied only to the specific areas that will contact the resin, creating the necessary roughness profile only where needed. This partial processing approach reduces overall processing time and energy consumption while still achieving the required airtightness at the joint portion.
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
The method significantly enhances airtightness at the joint portion by ensuring the resin effectively adheres to the metal member's surface texture, reducing leaks.
Implementation Method 1
irradiating a surface of the metal member with a high-energy beam, thereby causing the surface to have surface texture in which an arithmetic mean peak curvature for the surface is in a range from 2500 to 5000 (1/mm)
Data Source
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AI summary
One embodiment of the present invention is a metal-resin composite molded product including a metal member and a thermoplastic resin that are joined to each other. The metal member in this metal-resin composite molded product includes one surface. The one surface includes a joint surface portion that is joined to the thermoplastic resin and on which unevenness is formed. A cluster of substantially spherical parts are formed on the joined surface portion. An arithmetic mean peak curvature for the cluster is in a range from 2500 to 5000 (1/mm).