Spark Plug Electrode Welding Surface Roughness Control
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Solution Overview
Problem
Conventional resistance welding methods for spark plugs result in variations in welding due to fluctuations in contact resistance between the electrode base material and the tip, leading to inconsistent joining strength.
Innovation Solution
The method involves polishing or grinding the electrode base material to create surfaces with specific roughness levels to ensure consistent contact resistance, thereby stabilizing the Joule heat and ensuring a strong bond between the electrode base material and the noble metal tip through controlled surface roughness and contact areas.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional resistance welding is performed without surface treatment, then the welding process is simple, but variations in contact resistance cause variations in welding quality
Solution Approach 1:
The patent applies preliminary surface treatment (polishing or grinding) to the electrode base material before resistance welding to create surfaces with controlled roughness. This preliminary action ensures consistent contact resistance between the electrode base material and tip, thereby eliminating variations in welding quality while maintaining a relatively simple overall process
2Reliability
If the surface of the electrode base material is made smoother, then contact resistance decreases, but Joule heat generation during welding is reduced
Solution Approach 1:
The patent optimizes the surface roughness parameter of the electrode base material to a specific range (arithmetic average roughness Ra of 0.5 μm to 5 μm). This parameter change achieves a balance where contact resistance is sufficiently stable for reliable welding, while maintaining adequate Joule heat generation for proper melting and bonding of the tip and electrode base material
3Reliability
If the contact area between the electrode base material and tip is increased, then contact resistance is reduced, but the welding strength is reduced
Solution Approach 1:
The patent optimizes the contact area parameter between the electrode base material and tip to a specific range (0.3 mm² to 1.0 mm²). This parameter optimization achieves a balance where contact resistance is sufficiently stable for reliable welding, while maintaining adequate welding strength through proper melting and bonding
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 variations in welding, enhancing the joining strength and consistency of the spark plug assembly by ensuring controlled Joule heat generation and surface contact, leading to improved performance and reliability.
Implementation Method 1
the electrode base material and the tip are melted and bonded to each other by Joule heat generated by contact resistance between the electrode base material and the tip
Implementation Method 2
a first surface having an area larger than or equal to an area making contact with the tip is produced on the electrode base material by performing at least one of polishing and grinding thereon
Data Source
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AI summary
To provide a method for manufacturing a spark plug such that variations in welding of an electrode base material and a tip can be suppressed. A first surface having an area larger than or equal to an area making contact with the tip is produced on the electrode base material by performing at least one of polishing and grinding thereon, and a second surface having an area larger than or equal to an area making contact with a first electrode is produced on the electrode base material by performing polishing or the like thereon. Resistance welding is performed by applying current between the first electrode and a second electrode, after the first surface of the electrode base material and the tip have been brought into contact with each other, the first electrode has been brought into contact with the second surface of the electrode base material, and the second electrode has been brought into contact with the tip.