MIM Pipe Joint Gripping Elements With Controlled Hardness
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Solution Overview
Problem
Existing sealing and restraint systems for fluid pipelines, particularly in the waterworks industry, require cost-effective and efficient methods to produce durable, high-density gripping elements with precise dimensions and improved material properties, such as density, yield strength, and tensile strength, while minimizing equipment wear and production costs.
Innovation Solution
The use of special metal injection molding (MIM) techniques, specifically the Tundra® Technology, to produce gripping elements with controlled hardness ranging from 34 HRC to 45 HRC, allowing for improved dimensional control and enhanced material properties, reducing shrinkage to less than 10% and increasing the cyclic life of the gripping teeth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional metal injection molding techniques are used to produce gripping elements, then production cost is reduced, but dimensional control deteriorates due to shrinkage exceeding 10%
Solution Approach 1:
The patent applies parameter changes by modifying the hardness parameter of the gripping teeth to a specific range (34-45 HRC) through controlled heat treatment processes. This optimization resolves the contradiction by achieving both cost-effective MIM production and improved dimensional stability, as the controlled hardness prevents excessive deformation during assembly while maintaining manufacturing efficiency.
Solution Approach 2:
The patent employs composite materials by integrating metal gripping teeth with elastomeric gasket material to form a unified sealing and restraint component. This composite structure combines the dimensional stability and strength of metal with the sealing capability of elastomers, achieving both cost-effectiveness and precise dimensional control in a single manufactured part.
2Duration of action of moving object
If gripping teeth are made with high hardness to increase durability, then cyclic life is improved, but material brittleness increases leading to fracture under cyclic load
Solution Approach 1:
The patent optimizes the hardness parameter to a specific range (34-45 HRC) through controlled heat treatment, resolving the contradiction between durability and fracture resistance. This parameter optimization ensures the gripping teeth are hard enough to resist wear and maintain cyclic life while remaining ductile enough to withstand cyclic loading without brittle fracture.
3Productivity
If MIM process is used to produce gripping elements, then production efficiency is improved, but equipment wear increases
Solution Approach 1:
The patent reduces equipment wear in the MIM process by optimizing the hardness of the gripping teeth to 34-45 HRC. This parameter control prevents excessive hardness that would cause rapid wear of molding equipment while maintaining production efficiency through the automated MIM process.
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 MIM process enables the production of high-quality, durable, and flexible gripping elements that withstand up to 25,000 cycles under 0 to 350 PSI cyclic load without fracturing, offering a cost-effective solution with less equipment wear and improved structural integrity.
Implementation Method 1
The method generally includes the steps of: injection molding or extruding a green part gripping element from an MIM feedstock; thermally or catalytically debinding and sintering the green part to produce a brown part; hardening the brown part
Implementation Method 2
thermally or catalytically debinding and sintering the green part to produce a brown part
Implementation Method 3
hardening the brown part, the hardening step being carried out to achieve adaptive hardening of the gripping teeth by hardening within a selected range
Implementation Method 4
The MIM process enables the production of high-quality, durable, and flexible gripping elements that withstand up to 25,000 cycles under 0 to 350 PSI cyclic load without fracturing
Data Source
AI summary
A method is shown for manufacturing a hardened gripping element for a sealing and restraint system used for forming a pipe joint in a fluid pipeline. Instead of machining the gripping elements used in the system from a metal stock, a special series of metal injection molding steps are utilized. A metal polymer composite mix is first formed having a metal particulate phase and a polymer phase. A green metal composite article is formed by either extruding the composite mix or molding the composite mix into a metal polymer composite article having at least one gripping surface having a plurality of gripping teeth. The green composite article is subjected to thermal debinding and sintering to produce a brown part. The brown part is selectively hardened in the range from about 42 HRC to 45 HRC to produce a finished or near finished hardened gripping element.