Radial Compression Mechanism With Constant Die Gap
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Solution Overview
Problem
Existing radial compression mechanisms for medical devices like stents and catheters suffer from inconsistent die-to-die gaps and inaccuracies in maintaining a round cavity shape, leading to potential damage and suboptimal compression.
Innovation Solution
A radial compression mechanism featuring pivotally mounted dies with elongated arcuate bodies and inwardly spiraling orientation, where the working tips have sliding and convex surfaces forming a constant gap, allowing for uniform rotation and maintaining a round cavity shape during compression.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If wedge-shaped dies with planar surfaces are arranged to form a cylindrical cavity with hinges, then the mechanism can change cavity diameter, but the gap between adjacent wedges varies with diameter causing potential damage to compressed device parts
Solution Approach 1:
The patent applies curvature by replacing the planar surfaces of traditional wedge-shaped dies with arcuate (curved) surfaces. Each die has an elongated arcuate body with a concave sliding surface that contacts the convex working surface of adjacent dies. This curved geometry ensures that as the dies rotate about hinge points, the gap between adjacent dies remains substantially constant throughout the compression cycle, eliminating the variable gap problem that causes stent strut damage while maintaining the ability to vary cavity diameter.
2Manufacturing precision
If linear guides are used to drive wedge-shaped dies, then the gap between wedges can be constant, but the positional relationship of die ends becomes inaccurate reducing cavity roundness
Solution Approach 1:
The patent divides the compression system into multiple independently rotatable dies, each mounted on its own hinge point. Rather than using a single linear guide system that compromises roundness, each die rotates independently about its hinge point while maintaining contact with adjacent dies through their arcuate surfaces. This segmentation allows each die to maintain accurate positional relationship with its neighbors, ensuring the cavity remains round while the constant gap is maintained through the curved surface geometry.
Solution Approach 2:
The arcuate geometry of the die bodies with concave and convex working surfaces ensures that as each die rotates independently about its hinge point, the gap between adjacent dies remains substantially constant. The curved surfaces are specifically shaped so that during rotation, the contact point between adjacent dies moves along the arcuate surfaces while maintaining a constant separation distance, thereby preserving both cavity roundness and gap uniformity simultaneously.
3Reliability
If more hinge points are added to reduce maximum gap, then the mechanism size increases, but compact design requires larger gaps
Solution Approach 1:
The arcuate geometry of the dies fundamentally changes the relationship between mechanism size and gap magnitude. With curved surfaces, the gap between adjacent dies remains substantially constant throughout the compression cycle, regardless of the number of hinge points or the size of the mechanism. This eliminates the tradeoff where more hinge points are needed to reduce maximum gap in traditional mechanisms. The constant gap is achieved through the geometric relationship of the arcuate surfaces, allowing compact mechanism design without sacrificing reliability.
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 ensures a constant gap between dies, providing consistent and accurate compression across varying diameters, reducing the risk of damage and improving the roundness of the compressed device.
Implementation Method 1
Each die of the plurality of dies has a sliding surface and a working surface with a juncture of the sliding surface and the working surface defining the working tip. The concave sliding surface of each die is positioned in juxtaposition to the convex working surface of an adjacent die and the concave sliding surface of each die is formed to mate with the convex working surface of the adjacent die.
Data Source
AI summary
Radial compression mechanism includes a plurality of dies each having an elongated arcuate body with an outer end pivotally attached to a hinge plate and an inner working tip. The dies are mounted on the hinge plate in an inwardly spiraling orientation with the outer ends positioned in a circle and the working tips cooperating to define a central product-receiving cylindrically-shaped cavity. The product-receiving cavity is transitional between an open and a closed orientation. The working tip of each die has a sliding surface and a working surface with the sliding surface positioned in parallel juxtaposition to the working surface of an adjacent die and a constant width gap therebetween. Driving mechanism is coupled to rotatably drive all of the dies in unison to transition between open and closed orientations. The width of the gap remains constant during transition and between the open and closed orientations.