Spark Plug Welding Sag Removal via Feedback Control
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Solution Overview
Problem
The reduction in spark plug diameter leads to a narrow radial clearance between the metal shell and insulator, causing lateral flying sparks, and existing methods struggle to sufficiently remove welding sags to secure the required clearance.
Innovation Solution
A method for manufacturing spark plugs that includes a welding step for joining the ground electrode to the metal shell, followed by a controlled cutting and measuring process using a working tool, camera, and laser displacement gauge to accurately remove welding sags, with feedback mechanisms to ensure precise clearance adjustment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the spark plug diameter is reduced to respond to engine downsizing and improve fuel consumption, then the compactness and fuel efficiency are improved, but the radial clearance between the metal shell and insulator becomes narrow causing lateral flying sparks
Solution Approach 1:
The welding sag is removed in advance through machining before the ground electrode is welded to the metal shell. This preliminary removal of welding sag ensures that sufficient radial clearance is maintained between the metal shell and insulator even when the spark plug diameter is reduced, preventing lateral flying sparks while allowing compact design
2Manufacturing precision
If conventional machining is used to remove welding sag after ground electrode welding, then some welding sag can be removed, but it is difficult to sufficiently remove the welding sag to secure demanded clearance
Solution Approach 1:
The welding sag removal operation is performed before ground electrode welding, allowing for more effective and complete removal of welding sag. This timing enables sufficient radial clearance to be secured between the metal shell and insulator, which cannot be achieved when removal is attempted after welding when the sag has already formed
3Manufacturing precision
If the working position of the working tool is precisely controlled during cutting of welding sag, then the welding sag can be accurately removed without damaging other parts, but the process complexity increases
Solution Approach 1:
A control system precisely controls the working position of the cutting tool by receiving signals from a position detection device and adjusting the tool position accordingly. This feedback mechanism enables accurate removal of welding sag without damaging the ground electrode or metal shell, achieving high manufacturing precision while managing process complexity through automated control
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 effectively reduces welding sags without damaging other parts, ensuring a consistent and accurate radial clearance, thereby preventing lateral flying sparks and improving spark plug performance.
Implementation Method 1
the remaining quantity of the welding sag is measured using a laser displacement gauge
Data Source
Figure 1
Figure 2
Figure 3(A)~3(B)
AI summary
A method for manufacturing a spark plug comprises: welding a ground electrode 30 to a tip of a metal shell (metallic shell) 50; and removing a welding sag WS formed on and over inner surfaces of the ground electrode and the metal shell from a work WK in which the ground electrode is welded to the tip of the metal shell, the welding step including: cutting the welding sag using a working tool 400 while a control unit 710 controls a working position of the working tool with respect to the work; and measuring 300, 500 a remaining quantity of the welding sag after the cutting step and the control unit performing a feedback of a measured value of the remaining quantity of the welding sag measured in the measuring step to a working position of a working tool in the cutting step for a subsequent work.