Ceramic Guide Pin Clearance for Resistance Welding Alignment
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Solution Overview
Problem
Resistance welding methods face challenges in maintaining coaxial alignment of cylindrical members due to shearing stress, leading to guide pin wear or breakage, especially when using phenolic resin or non-tilting ceramic pins.
Innovation Solution
A ceramic guide pin with a radial clearance is used, allowing it to tilt and absorb shearing stress, combined with a columnar and large-diameter portion design for increased durability and ease of removal, and optional elastic members for central axis stabilization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a guide pin made of phenolic resin is used, then the guide pin can be inserted and removed easily, but the guide pin becomes worn and diameter decreases due to shearing stress when resistance welding is repeated
Solution Approach 1:
The guide pin is made of ceramic material instead of phenolic resin, providing a composite solution that combines the wear resistance of ceramic with the functional requirements of the guide pin. The ceramic material maintains its diameter even after repeated resistance welding operations, eliminating the wear problem while still allowing for insertion and removal operations.
2Reliability
If a guide pin made of ceramic is used to prevent wear, then wear resistance is improved, but the guide pin may break due to shearing stress when resistance welding is repeated
Solution Approach 1:
The guide pin is designed with a specific geometric structure including a large-diameter portion and a columnar portion with different diameters. This dynamic geometric design allows the guide pin to better distribute and withstand shearing stresses during repeated resistance welding operations, preventing breakage while maintaining wear resistance.
3Manufacturing precision
If the outer peripheral surface of the first member contacts the inner surface of the insertion hole, then positioning precision is improved, but the guide pin cannot tilt to absorb shearing stress
Solution Approach 1:
The guide pin features a non-uniform diameter design with a large-diameter portion and a columnar portion of smaller diameter. This local quality variation allows different sections of the guide pin to serve different functions: the large-diameter portion provides stable positioning, while the columnar portion allows controlled tilting to absorb shearing stresses, thereby maintaining both precision and durability.
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 ceramic guide pin effectively resists wear and breakage, maintaining coaxial alignment and extending its lifespan, with a tilting range of 0.1 mm or more sufficient to absorb shearing stress, while the design facilitates easy removal of welded components.
Implementation Method 1
there is a risk that the axes of the two members will be displaced from each other owing to a shearing stress applied to the contact surfaces of the two members when the pressure is applied in the current applying process
Implementation Method 2
an elastic member arranged in the insertion hole and generating an elastic force in a direction to press the guide pin toward a central axis of the insertion hole
Implementation Method 3
positioning the guide pin and the first member by inserting the guide pin and the first member into the insertion hole such that the insertion hole, the first member, and the guide pin are coaxial with each other
Implementation Method 4
applying a voltage between the first and second electrodes to conduct a current through the contact surfaces of the first and second members
Data Source
Figure 1
Figure 2A~2E
Figure 3A~3C
AI summary
In resistance welding, an end portion 42a and a flange portion 43a are welded together at contact surfaces thereof by applying a voltage between a first electrode 61 and a second electrode 80 while an inner casing 43 and a main metal piece 42 are pressed in directions toward each other. When a shearing stress due to the pressure is applied to a guide pin 70, since the guide pin 70 is made of ceramic, the guide pin 70 is more resistant to wear compared to a guide pin made of, for example, a phenolic resin. In addition, a clearance D is provided between a large-diameter portion 72 of the guide pin 70 and an inner surface of a guide-pin insertion hole 65b. Accordingly, the guide pin 70 is capable of tilting in the radial direction, so that the guide pin 70 can tilt so as to partially absorb the shearing stress. Therefore, the guide pin 70 is more resistant to breakage compared to a guide pin made of ceramic that is not capable of tilting. Thus, the life of the guide pin 70 used in the resistance welding process can be prolonged.