Camming Clamp Mechanism for Pipe Extraction
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Solution Overview
Problem
Conventional pipe extraction methods using lever arms struggle with achieving sufficient grip-to-thrust ratio, leading to pipe slippage, and require sacrificial wire ropes that are time-consuming to install and cause premature wear on cutting elements.
Innovation Solution
A camming clamp mechanism that generates a clamp force exceeding five times the thrust force, reducing the coefficient of friction required for slippage to 0.14-0.10, allowing for pipe extraction without wire ropes by applying 100-140 tons of force with jaws, enabling longer pipe lengths to be extracted without slippage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If lever arms are used to provide clamp force, then the device structure is simple, but the grip-to-thrust ratio is insufficient (2.5-4.5 times) causing pipe slippage
Solution Approach 1:
The patent changes the mechanical parameter of force multiplication by replacing lever arms with a camming mechanism. The camming plates convert rotational motion into linear clamp force, achieving a grip-to-thrust ratio of 5-10 times, which resolves the insufficient clamp force issue while maintaining structural simplicity.
Solution Approach 2:
The patent substitutes the lever arm mechanical system with a camming mechanism. The camming plates with curved surfaces create mechanical advantage through geometric conversion of motion, providing superior force multiplication (5-10 times grip-to-thrust ratio) compared to traditional lever arms (2.5-4.5 times), thereby preventing pipe slippage.
2Duration of action of stationary object
If wire ropes are used to attach through the pipe, then cutting elements wear prematurely, but removing wire ropes requires alternative attachment methods
Solution Approach 1:
The patent extracts the wire rope from the system entirely. Instead of using wire ropes that pass through the pipe and require cutting (causing element wear), the camming mechanism applies clamp force directly to the pipe surface, eliminating the need for wire ropes and preserving cutting element life.
Solution Approach 2:
The camming mechanism creates self-gripping clamp force through its geometric design. The curved cam surfaces automatically generate sufficient friction and mechanical advantage to secure the pipe during extraction, eliminating the need for separate wire rope attachment and making the system self-sufficient.
3Reliability
If high clamp force is applied to prevent slippage, then pipe extraction reliability improves, but the coefficient of friction required increases
Solution Approach 1:
The patent changes the force multiplication parameter from 2.5-4.5 times (lever arms) to 5-10 times (camming mechanism). This increased mechanical advantage reduces the required friction coefficient while maintaining high clamp force, thereby improving extraction reliability without increasing friction requirements.
Solution Approach 2:
By substituting lever arms with a camming mechanism, the system achieves superior force multiplication (5-10 times grip-to-thrust ratio). This mechanical substitution reduces the dependency on high friction coefficients, making the extraction process more reliable with lower friction requirements.
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 camming clamp mechanism effectively pulls pipes longer than thirty feet without wire ropes, reducing stress required for movement and allowing for simultaneous pipe extraction and installation of new HDPE pipes, minimizing disruption and wear on equipment.
Implementation Method 1
A camming clamp mechanism is shown that generates a clamp force much greater than what can be achieved with lever arms. The clamp force may exceed five times the thrust force, and may in fact be 7-10 times the thrust force required to extract the pipe from the ground.
Implementation Method 2
These numbers are achievable but the pipe may slip and cause the extraction method to be unsuccessful. The camming clamp mechanism may apply a force to the pipe of 100-140 tons, with half of the force applied by each jaw.
Data Source
AI summary
A pipe extraction machine can be used to remove a buried pipe from the ground. The machine has a carriage with jaws that grip the buried pipe. While gripped, the carriage moves relative to a support structure to pull the pipe out of the ground. Jaws are actuated by rotating clamp plates and maintained in opposition by static horizontal grooves. The jaws remain opposed and aligned during rotation of the clamp plates. A pipe shear may remove the pipe one piece at a time. A pipe puller can be used at the back end of the pipe being removed to simultaneously install a new pipe along the same path.