Composite Sucker Rod Joint with Nonlinear Wedge
Find Innovative SolutionsGenerate Solutions
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 joint design featuring a carbon or graphite composite rod with a nonlinearly varying wedge inserted into a steel fitting, which expands to occupy the fitting's space, providing high tensile strength and minimizing cross-sectional area, while a plug handles small compressive loads.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If stranded wire is used to construct the rod, then the rod can be assembled, but the tensile strength is reduced because strands do not occupy the entire cross-sectional area and are not perfectly aligned
Solution Approach 1:
The patent uses a solid composite rod made of carbon or graphite fibers embedded in a resin matrix. This composite structure allows the rod to achieve high tensile strength while occupying minimal cross-sectional area, as the fibers are continuously aligned with the rod axis and occupy the entire cross-section, eliminating the voids present in stranded wire constructions.
Solution Approach 2:
The patent changes the fundamental parameter of rod construction from discrete stranded wires to a continuous solid composite material. This parameter change enables full cross-sectional area utilization and perfect fiber alignment with the load axis, maximizing tensile strength for the given cross-sectional area.
2Strength
If the rod diameter is increased to provide higher tensile strength, then the rod can carry larger loads, but the rod no longer fits within the narrow tubing bore
Solution Approach 1:
The solid composite rod construction allows achieving high tensile strength in a smaller cross-sectional area compared to stranded wire rods. The continuous fiber reinforcement throughout the solid matrix provides superior strength-to-area ratio, enabling the rod to fit within narrow tubing bores while maintaining the required load-bearing capacity.
3Ease of manufacture
If a simple linear wedge contour is used, then the manufacturing is easier, but stress concentrations occur and the fit is not optimal
Solution Approach 1:
The patent employs a nonlinear wedge contour with curved surfaces that smoothly vary the cross-sectional dimensions. This curved geometry eliminates sharp corners and sudden transitions that would cause stress concentrations, while still being manufacturable using conventional machining or molding processes. The smooth curvature distributes stresses more evenly throughout the joint.
Solution Approach 2:
The wedge contour is designed with different curvature radii at different locations to optimize the fit and stress distribution. The local geometry is tailored to match the specific requirements of each region of the fitting, providing optimal contact and stress distribution throughout the joint while maintaining manufacturability.
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 joint achieves significantly higher tensile strength than conventional designs, enabling longer, lighter sucker rods to lift payloads effectively within narrow tubing, and can be applied to various tension-loaded applications.
Implementation Method 1
The wedge is then inserted into the rod, causing the rod to expand or swage outward
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. 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.