Resin Pipe Coupling Torque Input Design
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Solution Overview
Problem
Resin pipe couplings face challenges with low mechanical strength and torque dispersion due to manual application, leading to inadequate fastening torque for preventing water leakage while risking breakage, especially in applications like water supply pipes.
Innovation Solution
The design incorporates a torque input portion with a polygonal shape and recessed concave surfaces, optimizing the length division value to ensure suitable torque input without excessive torque, which reduces stress concentration and prevents breakage by strategically placing concave portions to break before the pipe coupling fails.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If manual torque application is used, then ease of operation is improved, but torque dispersion increases leading to unreliable fastening
Solution Approach 1:
The patent designs the torque input portion with specific geometric features (polygonal shape with concave portions) that pre-determine the torque transmission characteristics. The concave portions are positioned to create stress concentration points that will break at a predetermined torque level, thereby preliminarily setting the fastening torque limit before actual assembly occurs.
Solution Approach 2:
The patent changes the geometric parameters of the torque input portion, specifically the shape and position of concave portions on the polygonal surfaces. By adjusting parameters like the depth, width, and angular position of these concave features, the torque dispersion is controlled and a reliable fastening torque range is achieved.
2Reliability
If higher fastening torque is applied to prevent water leakage, then sealing performance is improved, but breakage risk increases
Solution Approach 1:
The concave portions are designed in advance to break at a specific torque level that is higher than the torque needed for water leakage prevention but lower than the torque that would cause pipe coupling failure. This preliminary design ensures that excessive torque is limited before it can cause damage.
Solution Approach 2:
The patent introduces local variations in the torque input portion geometry through concave portions at specific locations on the polygonal surfaces. These localized features create controlled stress concentration points that differ from the overall structure, allowing torque limitation without compromising the overall strength of the pipe coupling.
3Weight of moving object
If the pipe coupling is made entirely of resin, then weight is reduced and cost is lowered, but mechanical strength decreases
Solution Approach 1:
The patent optimizes the geometric parameters of the torque input portion and screw thread engagement to compensate for the lower material strength of resin. By adjusting parameters like thread pitch, engagement length, and torque input portion geometry, the mechanical strength is enhanced while maintaining the weight advantages of resin construction.
Data Source
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AI summary
A pipe coupling (10) has a pipe coupling main body (10A) that is pipe-shaped, a screw portion (12B) that is provided at an axial direction one end portion of the pipe coupling main body (10A), a torque input portion (14) that is polygonal and is provided at an axial direction intermediate portion of the pipe coupling main body (10A) and has, in a peripheral direction, plural tool contacting surfaces (14B) to which torque is inputted, and concave portions (30) that are provided in the tool contacting surfaces (14B) and are recessed in a radial direction from the tool contacting surfaces (14B). A division value obtained by dividing length L1 in an axial direction of the tool contacting surfaces (14B) except for the concave portion (30) by length L2 in the axial direction of the tool contacting surface (14B) including the concave portion (30) is 0.18 to 0.88.