Pipe Coupling Grip Element Hardening Against Cheese Slicer Effect
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Solution Overview
Problem
Existing coupling devices for pipes, such as those described in EP 0 974 780, face issues with reduced tensile strain resistance when used on hard pipes with protective layers and tend to lose grip on softer pipes, leading to the 'cheese slicer effect', which compromises their performance.
Innovation Solution
The coupling device features a grip element with dents pressed out of the plane and subjected to a peening operation, supported by pressure members with protrusions that enhance dent hardness and prevent the cheese slicer effect, allowing for improved tensile strain resistance and durability without increasing material costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If dents are pressed out of the plane of the grip element without peening treatment, then the manufacturing process is simple and costs are low, but the dents are not hard enough and the device loses grip on softer pipes (cheese slicer effect)
Solution Approach 1:
The peening operation is performed on the edges of the slit-like openings before the dents are pressed out of the plane of the grip element. This preliminary hardening treatment ensures that when the dents are subsequently formed, they have sufficient hardness to grip softer pipes without the cheese slicer effect, while maintaining a relatively simple overall manufacturing process
Solution Approach 2:
The patent changes the physical state and properties of the grip element material through peening treatment. The peening process alters the crystal structure of the metal, increasing the hardness of the dent regions. This parameter change in material properties enables the dents to maintain their sharpness and gripping effectiveness on softer pipes
2Strength
If the coupling device uses a grip element design suitable for hard pipes, then tensile strain resistance on hard pipes is improved, but the device loses grip on softer pipes due to the cheese slicer effect
Solution Approach 1:
The grip element is designed with localized different properties: the dent regions are hardened through peening treatment to provide high local hardness for gripping softer pipes, while the rest of the grip element maintains its original properties for overall structural integrity and tensile strain resistance on hard pipes. This local differentiation allows the single device to effectively handle both hard and soft pipes
3Reliability
If the dents are made harder to prevent cheese slicer effect on softer pipes, then grip retention on softer pipes is improved, but the manufacturing process becomes more complex and costly
Solution Approach 1:
The peening treatment is applied as a preliminary step in the manufacturing process, before the dents are pressed out. This timing allows the hardening to be integrated into the existing manufacturing workflow without requiring additional complex equipment or processes, thereby improving grip retention on softer pipes while keeping manufacturing relatively simple
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 modified grip element design enhances tensile strain resistance and durability, effectively addressing the limitations of previous devices by maintaining grip on both hard and soft pipes and extending the device's lifespan without maintenance.
Implementation Method 1
a suitable and preferable way to subject the edges of the slit like openings to the peening operation
Implementation Method 2
This brings about the advantage to modify the crystal structure of the metal that is used for the grip element, including the structure of the dents that are pressed out of the plane of the grip element. The dents will accordingly be harder which improves their effectiveness.
Data Source
Figure 1
Figure 2A~2C
Figure 3A~3D
AI summary
Coupling device for a pipe, comprising a sleeve for receiving the pipe and at least one sealing member to provide a seal between the sleeve and the pipe, a pressure member for applying a pressure to the sleeve and to the pipe, and a grip element extending along at least a part of the perimeter of the pipe, wherein the grip element is provided with dents pressed out of the plane of the grip element adjacent to slit like openings punched out of the grip element, wherein the device comprises multiple grip elements, each grip element being supported by at least one pressure member, which pressure member is provided with protrusions that mate with the back of the dents that are pressed out of the plane of the grip element.