Dual-Mandrel PEX Expansion Tool for Faster Uniform Tube Expansion
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Solution Overview
Problem
Existing PEX expansion tools are inefficient in terms of cycle time, leading to prolonged operation times for expanding PEX tubing before fitting insertion.
Innovation Solution
A PEX expansion tool with a motor-driven mandrel system that performs rapid cycles of axial extension and retraction, utilizing a first and second mandrel with spaced contact surfaces to evenly expand jaws, achieving a cycle time of one second or less.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If existing PEX expansion tools are used, then the structure is simple and easy to manufacture, but the cycle time is prolonged and productivity is low
Solution Approach 1:
The mandrel is divided into a first mandrel and a second mandrel that operate independently but cooperatively. The first mandrel engages the jaws at a first location while the second mandrel engages at a second location, allowing simultaneous expansion forces to be applied at multiple points. This segmentation enables faster expansion cycles while maintaining structural manageability through modular design.
Solution Approach 2:
The expansion tool employs dynamic mandrels that can extend and retract along the tube axis. The first and second mandrels are movable relative to each other and to the jaws, allowing them to adapt their positions during the expansion cycle. This dynamic capability enables rapid expansion and retraction movements that reduce cycle time while maintaining control over the expansion process.
2Productivity
If rapid expansion cycles are implemented, then productivity increases, but the force distribution and expansion uniformity may be compromised
Solution Approach 1:
By dividing the expansion force application into multiple segments (first mandrel at first location, second mandrel at second location), the tool achieves more uniform force distribution across the jaws. Each mandrel applies expansion force at its respective engagement point, and the combined effect produces uniform jaw expansion even during rapid cycles.
Solution Approach 2:
The jaws serve as an intermediary element between the mandrels and the PEX tube. The first and second mandrels apply forces to the jaws, which then transmit these forces uniformly to the tube end. This intermediary mechanism ensures that rapid mandrel movements are translated into controlled, uniform tube expansion.
3Manufacturing precision
If multiple mandrels with spaced contact surfaces are used, then expansion force is evenly distributed, but the device complexity increases
Solution Approach 1:
The first and second mandrels are combined into a single integrated mandrel assembly that moves cooperatively. While the mandrels have spaced contact surfaces for even force distribution, they are structurally linked and can be controlled as a unified system. This merging approach achieves uniform force distribution without requiring completely independent complex mechanisms for each mandrel.
Solution Approach 2:
The multi-mandrel system serves multiple functions simultaneously: the first mandrel engages jaws at the first location, the second mandrel engages at the second location, and together they provide balanced expansion forces. The spaced contact surfaces of both mandrels work in unison to achieve uniform force distribution across all jaws, maximizing the utility of each additional component.
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 efficiently expands PEX tubing in minimal time, ensuring quick and secure fitting installation by evenly distributing the expansion force, thereby reducing overall operation time.
Implementation Method 1
a drive mechanism configured to convert a rotational input from the motor into translational movement of the mandrel
Implementation Method 2
The PEX tube elastically recovers around the fitting to form a tight connection
Data Source
Figure 1
Figure 2~3
AI summary
An expansion tool comprising: a housing; a motor supported by the housing; a mandrel; and a drive mechanism configured to convert a rotational input from the motor into translational movement of the mandrel between an extended position and a retracted position. The expansion tool is configured to perform cycles of axially extending and retracting the mandrel. An elapsed time for one cycle of moving the mandrel from the retracted position to the extended position and back to the retracted position defines a cycle time of the expansion tool. The cycle time is one second or less.