Spark Plug Electrode Laser Welding Segmentation
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Solution Overview
Problem
The existing method of joining a noble metal tip to an electrode body in spark plugs using laser welding often results in inclination of the noble metal tip due to simultaneous molten states during the welding process.
Innovation Solution
A two-step laser welding method is employed, where the first zone is welded excluding part of the fixed region, followed by a second zone that includes an unwelded portion, allowing for solidification before the second welding step, thereby preventing the entire fixed region from becoming molten simultaneously.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the entire joint interface is welded in a single laser welding step, then welding efficiency is improved, but the noble metal tip becomes inclined due to simultaneous molten state
Solution Approach 1:
The welding process is divided into two separate welding steps: a first welding step that welds a first zone of the joint interface, and a second welding step that welds a second zone of the joint interface. This segmentation prevents the entire fixed region from becoming molten simultaneously, thereby suppressing inclination of the noble metal tip while maintaining welding efficiency.
2Speed
If the laser beam irradiates the entire joint interface simultaneously, then welding speed is improved, but the noble metal tip inclines due to uniform heating
Solution Approach 1:
The joint interface is divided into a first zone and a second zone that are welded at different times. The first welding step welds the first zone while excluding at least part of the fixed region, and the second welding step welds the second zone including the remaining unwelded portion. This temporal and spatial segmentation of the welding process prevents uniform heating of the entire joint interface, thereby maintaining the straightness of the noble metal tip.
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 effectively suppresses the inclination of the noble metal tip during the welding process, ensuring a stable weld joint and maintaining the wear resistance of the noble metal tip.
Implementation Method 1
a first welding step of welding a first zone of the joint interface by continuously irradiating with a laser beam while moving an irradiation position of the laser beam along the joint interface
Data Source
Figure 1
Figure 2A~2B
Figure 3
AI summary
The present application relates to a method of manufacturing a spark plug in which an electrode (30) has a noble metal tip (39) joined to an electrode body (31) by laser welding. The proposed method includes a fixing step and first and second separate welding steps. In the fixing step, the noble metal tip (39) is fixed to the electrode body (31) so as to define a joint interface of a first surface of the noble metal tip (39) and a second surface of the electrode body (31). In the first welding step, laser welding is performed on a first zone (35a) of the joint interface excluding at least a part of a region of the noble metal tip (39) fixed by the fixing step. In the subsequent second welding step, laser welding is performed on a second zone (35b) of the joint interface including an unwelded portion of the joint interface left without being welded by the first welding step.