Soft-Metal Press Sleeve Geometry for Low-Force Pipe Fittings
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Solution Overview
Problem
Existing pipe fitting systems require high forming forces and specialized tools for connecting plastic and plastic-metal composite pipes, often resulting in leaky connections and material damage due to complex pressing geometries and lack of guidance during compression.
Innovation Solution
A compression sleeve made of metal with microhardness less than 65 HV1, specifically in the range of 40 to 50 HV1, and a geometry with a wall thickness to outer diameter ratio of less than 0.06, allowing for reduced compression forces and large-area, uniform pressing, eliminating the need for additional elastomer seals and preventing creases and jamming.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If compression sleeves made of stainless steel with standard geometry are used, then connection stability is improved, but high forming forces are required and expensive specialized press machines are needed
Solution Approach 1:
The patent changes the material parameter (microhardness) of the compression sleeve from standard stainless steel (typically >150 HV1) to a softer metal with microhardness of less than 65 HV1. This parameter change allows the material to be more easily deformed during compression, reducing the forming force required while maintaining connection stability through the controlled softness that enables uniform radial deformation.
Solution Approach 2:
The patent applies local quality by creating a specific geometric feature - a pressing portion with reduced wall thickness (ratio of wall thickness to outer diameter less than 0.06) in the compression sleeve. This localized thinning creates a specific zone that deforms more easily under compression, concentrating the deformation where needed and reducing the overall force required while maintaining connection integrity.
2Reliability
If strongly contoured press geometries are used, then connection stability is improved, but jamming of pressing jaws and formation of press creases occur
Solution Approach 1:
The patent changes the geometric parameters of the compression sleeve by providing a pressing portion with a specific wall thickness to outer diameter ratio of less than 0.06. This geometric modification creates a more favorable deformation profile that distributes stress more evenly during compression, preventing the concentration of forces that lead to jamming and crease formation while maintaining connection stability.
3Strength
If compression sleeves with standard wall thickness are used, then structural strength is improved, but high compression forces are required
Solution Approach 1:
The patent applies local quality by creating a pressing portion with reduced wall thickness (ratio of wall thickness to outer diameter less than 0.06) at the specific location where compression is applied. This localized thinning reduces the force required for deformation at the pressing zone while the rest of the sleeve maintains sufficient wall thickness to provide overall structural strength and connection integrity.
Solution Approach 2:
The compression sleeve is effectively segmented into different functional zones: a pressing portion with reduced wall thickness for easy deformation and compression, and other portions with standard wall thickness for maintaining structural strength. This segmentation allows different parts of the same component to have different thicknesses optimized for their specific functions.
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
Enables a firm, tight connection with reduced forming work and susceptibility to errors, using simpler pressing tools, such as cordless screwdrivers or hand tools, and provides clear visibility for pipe insertion depth, thus improving connection reliability and ease of use in on-site installations.
Implementation Method 1
a press section of a fitting is deformed radially inwards with the pipe section inserted by means of a press tool in such a way that a permanent and tight, possibly even non-detachable connection is produced
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
The invention relates to a fitting for connecting to at least one pipe, in particular a plastic pipe or plastic-metal composite pipe, comprising a main body (4), at least one support body (6) connected to the main body (4) and for introducing into a pipe end, and at least one press sleeve (8) connected to the main body (4) and for receiving the pipe end, wherein the press sleeve (8) has a cylindrical press section (10). The technical problem of improving the fitting for pressing, in particular with small motor-driven or hand-operated pressing tools, is achieved in that the press sleeve (8) is produced from a metal with a microhardness of less than 65HV1, in particular less than 50HV1, preferably in the range between 40 and 50HV1, measured according to Vickers hardness test, and in that the ratio of the wall thickness (s) of the press section (10) to the outer diameter (d) of the press section (10) is less than 0.06, preferably in the range between 0.03 and 0.06. The invention also relates to a method for producing a connection.