Nonlinear Wedge Joint for High-Tension Composite Rod Fittings
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Solution Overview
Problem
Existing sucker rods lack sufficient tensile strength while occupying a minimal cross-sectional area, particularly in applications like oil wells where rods must withstand high tension loads and fit within small diameters, and prior solutions using stranded wire or materials are suboptimal.
Innovation Solution
A high tensile strength joint is created using a carbon or graphite composite rod with a smoothly varying nonlinear wedge inserted into a steel fitting, where the wedge's dimension matches the fitting's internal diameter contour, ensuring maximum space utilization and high strength under tension.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If stranded wire rods are used to reduce weight and fit within small tubing, then the cross-sectional area is minimized, but the tensile strength decreases because strands do not occupy the entire cross-sectional area and filaments are not aligned parallel to the rod axis
Solution Approach 1:
The patent employs composite materials consisting of high-strength filaments embedded in a metal matrix. The filaments are arranged substantially parallel to the rod axis and occupy the entire cross-sectional area, combining the high tensile strength of the filaments with the structural integrity of the metal matrix. This composite structure resolves the contradiction by achieving both maximum cross-sectional utilization and maximum tensile strength.
Solution Approach 2:
The invention applies local quality by creating a non-uniform structure where the filaments are strategically positioned and oriented parallel to the rod axis in regions subjected to high tensile loads. The metal matrix provides local support and load distribution, while the filaments provide localized high-strength reinforcement where needed most, optimizing the strength-to-area ratio.
2Strength
If traditional metal rods are used to achieve high tensile strength, then the tensile strength is sufficient, but the weight increases and the rod may not fit within narrow tubing bores
Solution Approach 1:
The composite structure combines lightweight high-strength filaments with a metal matrix, achieving the necessary tensile strength while significantly reducing weight compared to solid metal rods. The filaments provide the primary tensile load-bearing capacity with minimal weight, while the metal matrix provides structural support and fits within narrow tubing bores.
Solution Approach 2:
The invention changes the material parameters by selecting filaments with exceptional strength-to-weight ratios and arranging them in a specific configuration. By controlling the filament orientation, density, and distribution, the rod achieves high tensile strength with minimized weight and optimized dimensions for narrow tubing installation.
3Ease of manufacture
If filaments are arranged not exactly parallel to the rod axis to allow for manufacturing flexibility, then manufacturing is easier, but the tensile strength is reduced because the filaments do not optimally resist axial loads
Solution Approach 1:
The patent applies local quality by ensuring that in the critical load-bearing regions, the filaments are arranged substantially parallel to the rod axis to maximize tensile strength. Manufacturing flexibility is maintained in non-critical regions where slight variations in filament orientation do not significantly affect overall performance, allowing for practical manufacturing while preserving optimal strength characteristics where needed.
Data Source
AI summary
A joint exhibits high tensile strength. The joint includes a solid rod having a slit or opening into which a wedge is inserted. The rod and wedge are inserted into a fitting. Only a small amount of adhesive material is applied between the fitting and the rod. The adhesive material may be blended with non-adhesive, non-compressible “beads” that have a preferred diameter in order to insure that the desired adhesive thickness is achieved between the fitting and the rod. The internal surface of the fitting has a contour which continuously and nonlinearly varies with distance along the fitting. The wedge has a dimension having a similar contour. The shape of the contour can be described by a polynomial of order two or higher. The joint can be used to construct a sucker rod for an oil well, or it can be used in other applications. The joint can support high tensile loads, over long distances, while occupying a very narrow tubing bore.