PVC Pipe Mechanical Fitting With Differential Friction Grip Ring
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing compression fittings for PVC-based materials, such as c-PVC and PVC-U, fail to provide reliable connections due to material brittleness and inability to withstand deformation, while solvent cement connections are being phased out by regulations.
Innovation Solution
A mechanical fitting that uses frictional interfaces with varying coefficients of friction to secure PVC-based pipes without deformation, employing a grip ring with an inner friction coefficient 1.7 to 7.1 times higher than the outer coefficient to maintain the pipe against pull-out forces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If compression fittings are used to connect PVC-based pipes, then the connection mechanism is simple and widely applicable, but the pipe material becomes deformed and fails due to brittleness
Solution Approach 1:
The invention changes the fundamental connection parameter from compression-based to friction-based. The grip ring is designed with a high friction coefficient surface (μ≥0.3) that contacts the pipe externally, eliminating the need to deform the pipe material. The nut applies axial force to tighten the grip ring around the pipe, creating a secure friction-based connection that preserves pipe integrity while ensuring reliable connection.
2Adaptability or versatility
If deformation-based connection is used, then the fitting can be universally applied to different pipe materials, but PVC-based pipes cannot withstand the deformation and become fragile
Solution Approach 1:
The invention applies local quality by creating a high friction coefficient zone at the contact interface between the grip ring and pipe. The grip ring features a textured or roughened outer surface with μ≥0.3, while the inner surface has μ<0.2 to allow easy assembly. This localized friction enhancement at the pipe-contact interface provides strong holding power without requiring deformation, making it suitable for brittle PVC-based materials while maintaining universal applicability.
3Reliability
If solvent cement connection is used to avoid deformation, then the pipe integrity is preserved, but regulations are evolving to prohibit solvent use
Solution Approach 1:
The invention replaces the chemical connection mechanism (solvent cement) with a mechanical friction-based system. The grip ring with high friction coefficient (μ≥0.3) creates a secure mechanical connection through friction and axial clamping force, eliminating the need for chemical solvents entirely. This mechanical substitution maintains pipe integrity while ensuring compliance with evolving regulations that prohibit solvent use.
4Ease of manufacture
If a uniform friction coefficient is used for the grip ring, then the manufacturing is simpler, but the nut cannot slide properly during tightening while the pipe may slip
Solution Approach 1:
The invention applies different friction characteristics to different zones of the grip ring. The outer surface has a high friction coefficient (μ≥0.3) to prevent pipe slippage during tightening, while the inner surface has a low friction coefficient (μ<0.2) to allow the nut to slide smoothly during assembly. This differential friction design enables proper assembly operation while maintaining connection reliability.
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 friction-based connection ensures a secure, leak-tight assembly with minimal pipe deformation (0.5% or less), replacing the need for solvent cement and preventing pipe failure under pressure.
Implementation Method 1
The inner ring surface has an inner friction coefficient for defining an inner friction interface between the pipe and the grip ring, the outer ring surface has an outer friction coefficient for defining an outer friction interface between the grip ring and one of the main body and the nut. The inner friction coefficient is 1.7 to 7.1 higher than the outer friction coefficient.
Data Source
AI summary
A mechanical fitting for connecting pipes or for attaching a pipe is provided. The mechanical fitting comprises: a main body extending axially between a body end and an open end defining an insertion space for a pipe, a grip ring designed to close over a pipe, and a nut movably mounted over the main body for tightening the ring. The grip ring has an outer ring surface and an inner ring surface, wherein the inner ring surface has an inner friction coefficient for defining an inner friction interface between the pipe and the grip ring, the outer ring surface has an outer friction coefficient for defining an outer friction interface between the grip ring and one of the main body and the nut, wherein the inner friction coefficient is higher the outer friction coefficient. An assembly and a method of assembly are also proposed.