Spark Plug Discharge Chip Laser Welding Smooth Surface
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Solution Overview
Problem
Existing methods for manufacturing spark plugs with discharge chips often result in sharp corner portions due to steps between the discharge and base member-joining parts, leading to high electric field strengths and flying sparks, and face challenges in recycling and cost due to material separation.
Innovation Solution
A method involving a chip making step where a discharge chip is joined with a base member-joining part of lower melting point, followed by temporary resistance welding and main laser welding to smooth connect the discharge chip to the electrode base member, eliminating sharp edges and ensuring stable joining.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the discharge chip is obtained by joining the discharge part and the base member-joining part by resistance welding and blanking, then the manufacturing process is simple, but a step is formed between the discharge part and base member-joining part creating sharp corner portions
Solution Approach 1:
A filler material is introduced as an intermediary substance between the discharge part and base member-joining part. This filler material has a melting point lower than both components, allowing it to be selectively removed after joining. The filler enables the joining process while preventing step formation, and its subsequent removal leaves a smooth transition surface without sharp corners.
Solution Approach 2:
The invention changes the thermal parameter (melting point) of the filler material to be lower than both the discharge part and base member-joining part. This parameter difference enables selective removal of the filler after joining, allowing the sharp corner portions to be eliminated while maintaining the structural integrity of the main components.
2Reliability
If the diameter of the base member-joining part is set greater than the discharge part to maintain constant joining area, then the joining area is constant, but a step is formed creating sharp corner portions
Solution Approach 1:
The filler material serves as a mediator that compensates for the diameter difference between the base member-joining part and discharge part. By filling the radial gap, it enables constant joining area while preventing step formation. After removal, it leaves a smooth tapered transition that eliminates sharp corners while maintaining the beneficial constant joining area.
3Strength
If noble metals are used for the discharge chip, then wear resistance is secured, but cost increases and resource exhaustion occurs
Solution Approach 1:
The invention applies local quality by using noble metals only for the discharge part where wear resistance is critical, while the base member-joining part uses cheaper materials. This localized application of expensive materials minimizes noble metal consumption while maintaining the required wear resistance at the critical discharge interface.
Solution Approach 2:
The invention creates a composite structure combining noble metal discharge part with non-noble metal base member-joining part. This composite approach allows optimization of each component's material properties for its specific function while reducing overall noble metal content compared to using noble metals throughout the entire discharge chip.
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 method prevents flying sparks by eliminating sharp corner portions and allows for smooth connection of the discharge chip, enhancing electric field distribution and reducing recycling costs by maintaining a constant joining area without sharp edges.
Implementation Method 1
a temporary joining step of temporarily joining the discharge chip, at the base member-joining part, to the electrode base member by resistance welding
Implementation Method 2
a main joining step of joining, by laser welding, the discharge chip to the electrode base member so that a side surface of the discharge part and a surface of the electrode base member are smoothly connected
Data Source
Figure 1
Figure 2(a)~2(b)
Figure 3~4
AI summary
A method of manufacturing a spark plug 1 in which at least one of a center electrode 2 and a ground electrode 3 includes a discharge chip 5. In a chip making step, the discharge chip 5 is made by joining a discharge part 51 arranged on a spark discharge gap 11 side and a base member-joining part 52 that is made of a material having a lower melting point than the discharge part 51 and to be joined to an electrode base member 30. In a temporary joining step, the discharge chip 5 is temporarily joined, at the base member-joining part 52, to the electrode base member 30 by resistance welding. In a main joining step, the discharge chip 5 is joined, by laser welding, to the electrode base member 30 so that a side surface 511 of the discharge part 51 and a surface 31 of the electrode base member 30 are smoothly connected by a connecting surface 523 that has no sharp edge.