Variable Taper Plug for Metal Pipe Inside Diameter Expansion
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Solution Overview
Problem
The existing methods for expanding the inside diameter of metal pipes or tubes result in non-uniformity and overshooting deformation, leading to inconsistencies in the inside diameter both circumferentially and axially, which affects the precision of the expanded end portion.
Innovation Solution
A plug with a specific geometry, featuring a taper portion with a gradually increasing diameter and a parallel portion, is used to expand the metal pipe or tube, where the taper angle and axial distance are optimized to prevent overshooting deformation, ensuring the inside diameter equals the diameter of the parallel portion, thereby improving dimensional precision.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a conventional plug with constant taper angle is used for expanding the inside diameter of metal pipe, then the expanding operation can be completed, but overshooting deformation occurs and the inside diameter precision deteriorates
Solution Approach 1:
The patent applies parameter changes by modifying the taper angle distribution along the plug length. Instead of using a constant taper angle, the plug features a variable taper angle that decreases from the head end to the tail end. Specifically, the taper angle at any position is determined by the ratio of the diameter difference to the axial distance, creating a controlled deformation profile that prevents overshooting while achieving precise inside diameter expansion.
Solution Approach 2:
The patent implements local quality by creating different taper angles at different locations along the plug. The head end portion has a larger taper angle to initiate expansion, while the tail end portion has a smaller taper angle to control and complete the expansion without overshooting. This spatial variation in geometric properties allows different sections of the pipe to undergo controlled deformation appropriate to their position in the expansion process.
2Volume of moving object
If the plug is pushed into the metal pipe to expand the inside diameter, then the inside diameter increases, but non-uniformity in the circumferential and axial directions occurs
Solution Approach 1:
The patent uses parameter changes by progressively varying the taper angle along the axial direction of the plug. This gradual change in geometric parameter ensures that the expansion force is distributed uniformly along the pipe wall, preventing localized deformation and ensuring dimensional uniformity in both circumferential and axial directions while achieving the desired inside diameter increase.
3Productivity
If the taper angle is increased to expand the inside diameter more effectively, then the expansion efficiency improves, but bending deformation increases and causes instability
Solution Approach 1:
The patent resolves this contradiction by implementing a controlled parameter change where the taper angle varies along the plug length. The head end has a larger taper angle for effective expansion initiation, while the tail end has a smaller taper angle to maintain stability and control bending deformation. This gradual parameter transition allows efficient expansion while maintaining deformation stability throughout the process.
Solution Approach 2:
The patent applies the curvature principle by using a smoothly varying taper profile instead of sharp transitions. The continuous curvature of the taper surface ensures gradual force application, reducing sudden bending moments and maintaining deformation stability while achieving effective expansion efficiency.
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 effectively prevents overshooting deformation, resulting in a consistent inside diameter equal to the parallel portion of the plug, enhancing the dimensional precision of the expanded metal pipe or tube, with an expansion ratio of less than 8% ensuring minimal deformation intensity.
Implementation Method 1
the portion 11 on the metal pipe where the taper portion 31 of the plug 3 is passing undergoes bending deformation toward the outside direction of the metal pipe 1, and the portion 11 of the metal pipe 1 is expanded in its inside diameter as a result
Data Source
AI summary
The plug is for expanding the inside diameter of the end portion of a metal pipe. Its cross section is a circle, and includes a taper portion and a parallel portion connected to the tail end of the taper portion. The diameter of the taper portion gradually increases from the head end of the taper portion to the tail end of the taper portion where the diameter is D1. The axial distance LR from the point where the diameter D2=D1×0.99 to the tail end where the diameter is D1 satisfies the Expression 22≦LR/((D1−D2)/2)≦115. The taper angle on the surface where the diameter is D2 is larger than or equal to the taper angle on the tail surface of the taper portion following the point where the diameter is D2. The diameter of the parallel portion is D1.