Radial Compression Device With Constrained Die Gap Control
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Solution Overview
Problem
Existing radial compression mechanisms for medical devices like stents and catheters suffer from variable die-to-die gaps, inaccurate positional relationships, and manufacturing dimensional variability, leading to suboptimal compression accuracy and precision, especially at small diameters.
Innovation Solution
A radial compression mechanism featuring a constraining structure with isosceles-triangular die arranged in a circular pattern, guided by rolling balls for precise linear motion, and a driving mechanism that maintains a constant die-to-die gap independent of cavity diameter, allowing for accurate and uniform compression.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If wedge-shaped die with hinged connection are used to form cylindrical cavity, then the mechanism size can be reduced, but the die-to-die gap becomes variable and increases at intermediate diameters
Solution Approach 1:
The mechanism divides the cavity formation into multiple wedge-shaped die segments that can be independently positioned. Each die is carried on its own linear guide, allowing independent control of each segment's position to maintain consistent gaps while achieving compact overall mechanism size through the wedge geometry.
Solution Approach 2:
Linear guides are introduced as intermediary components between the stationary part and each die. These guides constrain each die's motion path independently, ensuring accurate positional relationships and constant die-to-die gaps without requiring the dies to be directly connected to each other through hinges.
2Manufacturing precision
If linear guides with individual die constraint are used, then die-to-die gap can be kept constant, but the mechanism becomes larger and more complex with many parts
Solution Approach 1:
Multiple linear guides are merged into a single stationary part structure. The guides are integrated into one consolidated component rather than being separate attachments, reducing the total number of parts while maintaining individual constraint of each die.
Solution Approach 2:
The stationary part serves multiple functions simultaneously: it houses all linear guides, provides the structural framework for the mechanism, and establishes the reference frame for all die movements. This multi-functionality reduces the need for separate components for each function.
3Ease of operation
If many parts and attachments are used to constrain die motion, then individual die positioning can be controlled, but manufacturing dimensional variability affects cavity roundness
Solution Approach 1:
Each die serves itself by being independently constrained on its own linear guide. The die's motion is self-controlled within the guide's tolerance, eliminating the need for additional attachments or complex inter-die constraint mechanisms that would introduce more sources of dimensional variability.
4Manufacturing precision
If hinge point circle diameter is increased to reduce maximum gap, then gap consistency improves, but the overall mechanism size increases
Solution Approach 1:
The mechanism transitions from a static hinged configuration to a dynamic system where each die can move independently along its linear guide. This dynamic independence allows the dies to maintain optimal positioning throughout the compression stroke, achieving consistent gaps without requiring a large hinge point circle diameter.
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 mechanism achieves precise and uniform compression with constant die-to-die gaps, enabling accurate radial force measurement and improved manufacturing tolerances, even at small diameters as low as 0.3 mm, reducing the risk of device damage and enhancing the roundness of the compressed product.
Implementation Method 1
each die being constrained to move reciprocally and linearly along the corresponding bearing surface
Data Source
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AI summary
A radial compression mechanism includes a constraining structure with a cut-out defined by a plurality of bearing surfaces. A plurality of die are carried by the constraining structure and arranged in a circular pattern about a central axis. Each die has a base side positioned in parallel juxtaposition to a corresponding bearing surface and each die is constrained to move reciprocally and linearly along the corresponding bearing surface. Working surfaces of the plurality of die cooperate to form a cavity that is movable between an open position and a closed position. A driving mechanism is coupled to at least one of the plurality of die to drive all of the die in unison between the open position and the closed position.