Spark Plug Ground Electrode Projection Welding
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Solution Overview
Problem
Conventional spark plug manufacturing methods result in large gaps and hollow recesses between the intermediate member and the outer electrode base material when subjected to thermal cycling, leading to reliability issues and heat transfer problems.
Innovation Solution
A method involving projection-welding with a projecting portion on the intermediate member or outer electrode base material to ensure reliable welding over a wider area, preventing gaps and hollow recesses through improved heat transfer and structural integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional resistance welding is used to join the intermediate member and outer electrode base material, then the manufacturing process is simple, but large gaps form at the radially central portion during thermal cycling due to insufficient pressure application
Solution Approach 1:
A projecting portion is formed in advance on either the intermediate member or outer electrode base material at the radially central portion. This preliminary structural modification ensures that pressure is automatically applied to the central portion during welding, preventing gap formation during subsequent thermal cycling while maintaining process simplicity
Solution Approach 2:
The projecting portion is localized specifically at the radially central portion where gaps tend to form, rather than modifying the entire component. This localized modification concentrates the pressure application exactly where needed, improving joint reliability at the critical area without complicating the overall manufacturing process
2Ease of manufacture
If the intermediate member and outer electrode base material are not reliably welded at the radially central portion, then manufacturing is easier, but hollow portions form in the fused metal alloy portion due to poor heat transfer and high-temperature oxidation
Solution Approach 1:
The projecting portion is created beforehand to ensure reliable pressure contact at the radially central portion during welding. This preliminary action prevents poor heat transfer and subsequent high-temperature oxidation that would otherwise create hollow portions in the fused metal alloy
Solution Approach 2:
By concentrating the projecting portion at the radially central portion, the invention locally improves heat transfer and welding quality exactly where hollow portions are most likely to form, preventing this harmful effect without affecting other areas
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 effectively prevents large gaps and hollow recesses during thermal cycling, enhancing the reliability and durability of the spark plug by ensuring a strong and efficient joint between the intermediate member and the outer electrode base material.
Implementation Method 1
projection-welding the intermediate member to the outer electrode base material by means of a projecting portion provided on at least one of the intermediate member and the outer electrode base material
Implementation Method 2
a chip (outer electrode chip) is laser-welded to the first surface of the intermediate member
Data Source
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AI summary
A spark plug (100) including a center electrode (130) and a ground electrode (140), which is formed by joining a ground electrode chip (143) to a ground electrode base material (141) via an intermediate member (142). A method for producing the spark plug (100) includes providing a projecting portion (142p) on the intermediate member (142), and projection-welding the intermediate member (142) to the ground electrode base material (141) by means of the projecting portion (142p), to thereby join the intermediate member 142 to the ground electrode base material (141). Further, the intermediate member (142) of the spark plug (100) includes a cylindrical columnar portion (142e) which is joined to the ground electrode chip (143), and a flange portion (142d) which is joined to the ground electrode base material (141) and which flange portion (142d) has a diameter greater than that of the cylindrical columnar portion (142e).