Cold Metal Locks and Stitching Pins for Cast Crack Repair
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Solution Overview
Problem
Existing methods for repairing damaged cast metal components, such as welding and brazing, introduce heat that alters the metal structure and weakens the casting, while cold metal repair techniques like adhesive bonding lack strength and reliability, especially under high stress loads.
Innovation Solution
A cold metal repair apparatus and method using elongate metal locks with overlapping circular lobes and stitching pins that create a friction fit and stress distribution, allowing for secure repair without heat-induced damage, featuring a unique thread pattern for a liquid-tight and gas-tight seal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If welding or brazing is used to repair cracked cast metal components, then the repair can withstand high stress loads, but the heat alters the metal structure and creates discontinuities that weaken the casting strength
Solution Approach 1:
The patent replaces thermal joining processes (welding/brazing) with a mechanical fastening system consisting of metal locks and stitching pins. The metal locks are inserted into drilled holes transverse to the crack, and stitching pins are threaded along the crack to mechanically secure the cracked portions without applying heat, thereby avoiding metal structure alteration while maintaining repair strength
Solution Approach 2:
The repair system is divided into discrete components: metal locks positioned at intervals transverse to the crack, and stitching pins threaded along the crack length. This segmentation allows the repair to distribute stress across multiple points rather than creating a single heat-affected zone, maintaining structural integrity without thermal damage
2Object-affected harmful factors
If adhesive bonding materials such as epoxy are used for casting repair, then the repair process avoids heat damage, but the bonding strength is insufficient to withstand high stress loads
Solution Approach 1:
The patent employs a composite repair system combining metal components (locks and pins) with mechanical fastening elements (threaded holes). This composite approach provides superior strength compared to adhesive bonding alone, while still avoiding heat damage by using cold mechanical fastening methods rather than thermal processes
Solution Approach 2:
The metal locks and stitching pins serve as intermediary mechanical elements that transfer and distribute loads across the cracked region. These intermediaries provide the necessary bonding strength that adhesive materials alone cannot achieve, while maintaining the no-heat advantage
3Ease of operation
If conventional metal repair techniques are used, then the repair can be performed in-situ, but the heat associated with the process alters the metal structure and creates discontinuities
Solution Approach 1:
The patent replaces thermal repair processes with a purely mechanical system that can be applied in-situ. The metal locks are forced into drilled holes and stitching pins are threaded along the crack, providing a cold repair method that maintains operational convenience while eliminating heat-induced discontinuities and metal structure alterations
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 solution provides a stronger, more reliable repair that prevents crack spreading and misalignment, achieving a liquid-tight and gas-tight seal without compromising the strength of the metal lock grip, thus enhancing the overall repair strength.
Implementation Method 1
create a friction fit and stress distribution
Implementation Method 2
create a friction fit and stress distribution
Data Source
AI summary
A lock and pin for the structural and fluid tight repair of cracks not amenable to high temperature repairs or synthetic material patches. Fluid tight pins and locks seal the crack while one or more locks prevent the crack from growing. These repairs need to endure the remaining life cycle of the machinery part while withstanding all the strain, pressure, heat and expansion and contraction of the part before the crack(s) were formed. Often these cracks evolved due to engineering design flaws that will require even greater strength from these areas than when new.