Spark Plug Ground Electrode Laser Keyhole Welding
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Solution Overview
Problem
Existing spark plug manufacturing processes, particularly those using resistance welding, often result in extruded material that requires removal, known as weld flash, especially when working with nickel-based alloys like Inconel®, which complicates downstream metalworking processes.
Innovation Solution
The use of a high energy density laser to create a fused weld joint with laser keyhole welds between the ground electrode and metal shell, eliminating the need for weld flash removal and enhancing attachment strength and conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If resistance welding is used to attach ground electrode to metal shell, then the attachment process is simple and fast, but extruded material (weld flash) is generated that requires removal
Solution Approach 1:
The patent replaces the mechanical resistance welding process with a laser-based welding system. The laser beam provides localized heating that melts and fuses the ground electrode to the metal shell without generating significant weld flash, thereby eliminating the need for post-weld flash removal operations while maintaining high welding speed.
Solution Approach 2:
The patent changes the welding parameters by using laser energy with specific power density, pulse duration, and focal point control to achieve deep penetration welding with minimal material extrusion. This allows the welding process to complete quickly while avoiding the generation of weld flash that would require removal.
2Strength
If laser keyhole weld is used to attach ground electrode to metal shell, then weld flash is eliminated and attachment strength is improved, but the process requires high energy input
Solution Approach 1:
The patent employs pulsed laser welding where the laser beam is delivered in controlled pulses rather than continuous operation. This periodic energy input allows the material to melt and fuse during the pulse duration, then cool and solidify between pulses, achieving strong attachments while managing overall energy consumption and heat input to the workpiece.
Solution Approach 2:
The laser keyhole weld process utilizes controlled phase transitions of the metal materials. The high energy density laser creates a keyhole cavity through rapid melting and vaporization, then the material solidifies as the laser moves on, creating a strong fused joint. This phase transition mechanism allows efficient energy utilization and strong attachment formation.
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 laser keyhole welds provide a stronger and more reliable attachment than traditional methods, reducing the need for post-weld processing and improving thermal and electrical conductivity across the interface, while maintaining material integrity.
Implementation Method 1
The fused weld joint includes one or more laser keyhole weld(s). The laser keyhole weld(s) have material of the metal shell and material of the ground electrode solidified in a temporary cavity created via impingement of a laser beam producing the laser keyhole weld(s).
Implementation Method 2
material of the metal shell and material of the ground electrode solidified in a temporary cavity created via impingement of a laser beam
Data Source
AI summary
A spark plug has a metal shell, an insulator, a center electrode, and a ground electrode. One or more firing tips can be attached to the center electrode, to the ground electrode, or to both electrodes. The metal shell and ground electrode are attached together by way of one or more laser keyhole welds at an interface of the shell and electrode. Before the laser keyhole welds, resistance welding can be executed for a temporary attachment.