Segmented Mandrel Holding Device for Stent Coating Runout
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Solution Overview
Problem
Existing stent holding devices suffer from issues such as runout, sagging, buckling, inhomogeneous coatings, and coating defects due to varying clamping forces and inadequate centering, leading to compromised effectiveness and increased production costs in medical device coating processes.
Innovation Solution
A multi-purpose holding device with a rigid frame and interchangeable support members that securely align and rotate stents without extending through them, minimizing surface contact and ensuring precise positioning to prevent runout and coating defects, allowing for simultaneous stent handling and inspection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If mandrels with small diameter and long length are used to support stents, then the stent can be held during coating, but the mandrel easily bends causing runout of the stent
Solution Approach 1:
The mandrel is divided into multiple rigid segments (first mandrel segment, second mandrel segment, third mandrel segment) connected by rigid linkages. This segmentation allows each segment to maintain rigidity independently while the overall structure achieves the required length for supporting the stent, preventing bending and runout.
Solution Approach 2:
Instead of using a single long mandrel that bends in the longitudinal dimension, the invention uses multiple short rigid segments connected by linkages that provide rotational freedom. This transforms the problem from a single-dimensional rigidity issue to a multi-dimensional solution where rigid segments are connected through angular linkages.
2Reliability
If support members are used to clamp the stent, then the stent can be secured for rotation, but varying clamping forces cause sagging or buckling
Solution Approach 1:
The support members are designed to contact the stent at multiple points (inner surface and outer surface) and automatically adjust to distribute clamping forces evenly. The stent itself serves as the reference for positioning, with support members conforming to its geometry, eliminating the need for external alignment fixtures and ensuring uniform coating distribution.
Solution Approach 2:
Different portions of the support members have different contact characteristics - some contact the inner surface of the stent while others contact the outer surface. This local differentiation allows the support structure to adapt to the stent's geometry and distribute forces uniformly, preventing sagging and buckling.
3Volume of moving object
If mandrels with small diameter are used, then the device can be compact, but runout of several mm occurs affecting coating weight consistency
Solution Approach 1:
The mandrel is segmented into multiple rigid sections connected by linkages, maintaining a compact overall structure while ensuring each segment is sufficiently rigid to prevent runout. The segmented design allows the device to remain compact while achieving the precision needed for consistent coating weight.
4Ease of manufacture
If conventional holding devices are used, then stent coating can be performed, but coating accumulations and defects occur due to interference with spray plume
Solution Approach 1:
The design removes traditional interfering elements from the coating path. The support members are positioned and shaped to minimize interference with the spray plume, and the mandrel structure is configured to allow unobstructed coating application, eliminating coating accumulations and defects.
Data Source
AI summary
This invention relates to a multi-purpose holding device to handle, support and rotate one or more hollow cylindrical objects. The holding device consists of a rigid frame and support members for precise alignment and rotation of one or more objects within the frame structure. A method is also provided to reproducibly support, rotate and inspect the hollow cylindrical objects.