PEX Expansion Tool With Rotating Collar for Uniform Jaw Expansion
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Solution Overview
Problem
Existing PEX expansion tools lack efficient mechanisms for expanding PEX tubing consistently and effectively, leading to potential indentations and increased cycle times during the expansion process.
Innovation Solution
An expansion tool with a housing, a rotatable collar, jaws, a mandrel, and a cone, where the mandrel expands the jaws by moving to an extended position, and a rotation mechanism incrementally rotates the collar to ensure smooth expansion and reduce friction, utilizing a motor with high and low speed configurations and a drive mechanism for precise translational movement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a mandrel is used to expand the jaws, then the expansion force is improved, but the cycle time increases
Solution Approach 1:
The expansion tool employs a cam mechanism that converts rotational motion into periodic reciprocating motion of the mandrel. The cam rotates continuously while the mandrel performs periodic expansion strokes, allowing the tool to maintain high expansion force during each stroke while operating at high rotational speeds to reduce overall cycle time.
Solution Approach 2:
The patent replaces traditional hydraulic or pneumatic expansion systems with a mechanically-driven cam and follower system. This mechanical substitution enables direct transmission of high forces through rigid components while allowing rapid cycling through high-speed rotation, eliminating the slower actuation rates of fluid-based systems.
2Productivity
If the jaws are expanded rapidly, then the productivity is improved, but the manufacturing precision deteriorates due to potential indentations
Solution Approach 1:
The jaw faces are designed with specific surface characteristics including lubrication grooves and controlled surface finishes in the expansion contact areas. This local quality control ensures uniform expansion across the PEX tubing surface while allowing rapid expansion, preventing indentations through optimized local surface properties rather than restricting overall expansion speed.
Solution Approach 2:
The cam mechanism is designed to provide a controlled ramp-up of expansion force at the beginning of each stroke, allowing the jaws to gradually engage the PEX tubing before reaching maximum expansion. This preliminary gradual engagement prevents sudden impact forces that could cause indentations, while the overall rapid cycling maintains high productivity.
3Loss of energy
If a rotation mechanism is added to the collar, then the friction is reduced, but the device complexity increases
Solution Approach 1:
The rotation mechanism is integrated into the existing cam drive system, where the cam's rotational motion simultaneously drives both the mandrel reciprocation and the collar rotation. This merging of functions allows the collar to rotate and reduce friction during jaw retraction without requiring a separate dedicated rotation mechanism, thereby minimizing additional complexity.
Solution Approach 2:
The collar's rotation is driven by the same cam mechanism that drives the expansion action, making the friction-reduction feature self-powered from the existing motion source. The cam's rotational input automatically produces both the expansion stroke and the collar rotation, eliminating the need for external power or control systems for the rotation function.
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 tool ensures consistent expansion of PEX tubing with reduced indentations and faster cycle times, promoting a quality seal with fittings by minimizing friction and optimizing the expansion process.
Implementation Method 1
The PEX tube elastically recovers around the fitting to form a tight connection
Implementation Method 2
the cone includes means for containing grease to lubricate the inner surfaces of the plurality of jaws
Implementation Method 3
a rotation mechanism is configured to incrementally rotate the collar
Data Source
AI summary
An expansion tool includes a housing, a collar rotatably coupled to the housing, the collar including a plurality of slots, a plurality of jaws, each jaw having a projection received in a corresponding one of the plurality of slots such that the jaws are coupled for co-rotation with the collar, a mandrel moveable relative to the housing between a retracted position and an extended position, the mandrel engageable with the jaws to expand the jaws in response to movement of the mandrel to the extended position, and a cone received within the plurality of jaws and engageable with inner surfaces of the plurality of jaws. The mandrel is configured to engage the cone to move the cone with the mandrel to expand the jaws as the mandrel moves toward the extended position, and a rotation mechanism is configured to incrementally rotate the collar.