Hydraulic Plug Shell Deformation for Low-Force Sealing
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Solution Overview
Problem
Existing hydraulic plugs require axial force for installation, leading to design complexity and potential material cracking, and involve costly reaming processes with waste removal issues.
Innovation Solution
A hydraulic plug manufacturing method involving a shell with a circumferential wall and expander head, where the expander head has a convex contact surface, and the shell is plastically deformed to create a constricted opening with a ramp, allowing the expander to be retained and sealing the passage without the need for precise matching tapered surfaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional tapered hydraulic plugs are used requiring axial force for installation, then sealing is achieved, but design complexity increases and material cracking may occur
Solution Approach 1:
The patent inverts the traditional expansion mechanism by using a tensile force applied to the expander stem rather than compressive axial force. The expander is pulled outward against the tapered internal surface of the shell, creating a wedge action that expands the shell radially outward to seal against the passage wall. This inversion eliminates the need for complex axial force balancing and step engagement design.
Solution Approach 2:
The shell is pre-formed with a tapered internal surface and an opening wider than the sealed end before the expander is installed. This preliminary shaping of the shell cavity allows the expander to be inserted and then pulled outward to create the sealing expansion, eliminating the need for on-site reaming operations and reducing installation complexity.
2Ease of manufacture
If reaming process is used to create tapered hole, then plug installation is enabled, but manufacturing cost increases and waste removal becomes problematic
Solution Approach 1:
The passage is pre-formed with a cylindrical hole of constant diameter rather than requiring on-site tapered reaming. The shell is then pre-formed with a tapered internal surface that matches the desired seal geometry. This separates the manufacturing processes, allowing the passage to be drilled once and the shell to be pre-tapered, eliminating waste removal issues during installation.
Solution Approach 2:
The sealing function is segmented into two independent components: the passage remains cylindrical and simple to drill, while the shell contains the tapered surface needed for sealing. This segmentation allows each component to be manufactured optimally without requiring complex on-site reaming operations.
3Reliability
If expander is driven into shell with axial force, then sealing is achieved, but additional process steps and waste removal are required
Solution Approach 1:
Instead of driving the expander axially into the shell with compressive force, the patent applies a tensile force to pull the expander outward against the tapered internal surface of the shell. This creates a wedge action that expands the shell radially to seal against the passage wall, eliminating the need for complex axial force application equipment and reducing installation steps.
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
This method reduces installation forces, simplifies manufacturing, and enhances sealing performance by creating a non-linear internal surface that engages the expander head, reducing material stress and manufacturing costs.
Implementation Method 1
the expander further comprising a stem that extends out from the cavity for applying a tensile force to the head
Implementation Method 2
The head of the expander acts as a wedge to expand the shell within the passage to seal it off
Implementation Method 3
plastically deforming a region of the shell adjacent its open end, to form a constricted opening retaining the head of the expander within the cavity
Data Source
Figure 1A~3
Figure 4A~4B
Figure 5A~5B
AI summary
There is provided a method of manufacturing a hydraulic plug (2). A shell (3) comprising a circumferential wall (3c), a sealed end (5), an open end (6) and a cylindrical cavity (9) opening to the open end is provided. The open end of the shell is wider externally than the sealed end. A head (4a) of an expander (4) is inserted into the cavity, the expander further comprising a stem (4b) that extends out from the cavity for applying a tensile force (T) to the head. The head of the expander has a convex contact surface (4d) which is rounded in an axial direction (A) of the cavity. A region (10) of the shell adjacent its open end is plastically deformed causing material from the circumferential wall of the shell to be displaced radially inward around the head of the expander to form a constricted opening (9b) retaining the expander within the cavity. The deforming reshapes an internal surface (9a) of the cavity from a cylindrical to a non-linear shaped ramp leading up to a constricted opening.