Formed Article Laser Welding with Controlled Molten Pool Area
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Solution Overview
Problem
Existing laser welding methods for polyamide resins in complex components, such as battery cases, fail to achieve sufficient bonding strength and reliability, with issues like interfacial peeling and unsatisfactory appearance characteristics.
Innovation Solution
The method involves laser welding a transmitting resin member and an absorbing resin member, with a molten pool area between 0.210 mm² to 1.00 mm², using a resin composition containing polyamide-based resins and specific fillers, and optimizing laser beam transmittance to enhance bonding strength and appearance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If laser welding is performed on polyamide resin components, then bonding speed and cleanliness are improved, but bonding strength is insufficient
Solution Approach 1:
The patent applies parameter changes by optimizing laser beam parameters (power, speed, focal position) and resin composition parameters (polymer type, filler content, moisture content) to achieve both high bonding speed and sufficient bonding strength. Specifically, controlling the laser beam power density and scanning speed while adjusting the resin's moisture content to 0.5-5% creates optimal welding conditions that resolve the contradiction between speed and strength
Solution Approach 2:
The patent uses composite materials by formulating a resin composition containing polyamide polymer, inorganic filler (30-70 wt%), and controlled moisture content. This composite structure allows the material to simultaneously provide laser transmittance, bonding strength, and structural integrity, resolving the contradiction between welding speed and bond strength
2Object-generated harmful factors
If laser welding is performed on polyamide resin components, then environmental cleanliness is improved, but appearance characteristics are unsatisfactory
Solution Approach 1:
The patent applies parameter changes by optimizing laser processing parameters (beam power, scanning speed, focal position) to control the welding zone's thermal input. By precisely controlling these parameters, the method achieves clean welding without excessive melting or discoloration, maintaining appearance quality while preserving environmental benefits
3Device complexity
If laser welding is performed on polyamide resin components, then processing simplicity is improved, but reliability of bonded portion is insufficient
Solution Approach 1:
The patent applies parameter changes by controlling resin moisture content (0.5-5%) and laser beam parameters to ensure reliable bonding. By optimizing these parameters, the method achieves consistent welding quality and fracture modes without complex equipment modifications, maintaining processing simplicity while improving reliability
Solution Approach 2:
The patent applies feedback by monitoring and controlling resin moisture content and laser processing parameters to achieve consistent welding quality. This controlled approach ensures reliable bonding strength and proper fracture modes, improving reliability while maintaining the simplicity of the laser welding process
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 approach results in improved bonding strength, reliability, and enhanced appearance characteristics of the bonded points, suitable for complex components like battery cases.
Implementation Method 1
a bonding surface is irradiated with laser light from the transmitting resin member side such that the absorbing resin member forming the bonding surface is melted with the energy of the laser light and bonded
Data Source
AI summary
A formed article obtained by performing laser welding on a transmitting resin member and an absorbing resin member, includes: a bonded part where the transmitting resin member and the absorbing resin member are bonded to each other by the laser welding, in which a molten pool is observed at the bonded part in a cross section that includes a normal to the transmitting resin member or the absorbing resin member and is orthogonal to a scanning direction of a laser beam, an area of the molten pool is 0.210 mm2 or more and 1.00 mm2 or less, the transmitting resin member and the absorbing resin member are each molded from a resin composition, the resin composition contains a thermoplastic resin, the thermoplastic resin contains at least a polyamide-based resin (A1), and a glass transition point temperature of the resin composition is 85° C. or higher.