Reusable Support Ring for Prosthetic Socket Preform
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Solution Overview
Problem
The existing methods for producing prosthetic limb sockets are slow, expensive, and result in significant scrap material due to the use of square plastic sheets and expensive clamping frames, with the added cost of metal reinforcing rings that become scrap after use.
Innovation Solution
A flat circular thermoplastics disk is injection molded with recesses for a support ring, allowing for a reusable interfitting connection that simplifies the process by preventing lateral movement and enabling efficient reuse of the support ring with new disks, reducing equipment needs and production time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of substance
If a square plastic sheet is used with a clamping frame, then the socket can be formed, but significant scrap material is produced and the process is slow and expensive
Solution Approach 1:
The patent transitions from using square sheets with corners to circular sheets. The circular shape eliminates the corner portions that were previously scrapped, allowing the entire sheet to be utilized for socket formation. This curvature change directly reduces material waste while maintaining the structural integrity needed for socket formation.
Solution Approach 2:
The support ring serves multiple functions: it provides structural support during heating, enables easy handling and inversion of the heated sheet, and acts as a reusable fixture that eliminates the need for expensive clamping frames. This multi-functional design reduces both material waste and production time.
2Reliability
If a clamping frame is used to secure the sheet, then the sheet can be held in place, but the frame is expensive, has limited service life, and requires significant time to attach and remove
Solution Approach 1:
The patent extracts the clamping frame from the process entirely by using a support ring that the circular sheet can be directly placed upon. The support ring provides the necessary positioning and support without requiring attachment mechanisms, eliminating the time-consuming attachment and removal steps while maintaining reliable sheet positioning during heating.
Solution Approach 2:
The support ring is prepared in advance as a reusable fixture that provides pre-positioned support for the circular sheet. This preliminary preparation eliminates the need for time-consuming attachment operations during each socket formation cycle, as the sheet simply needs to be placed on the pre-positioned ring.
3Strength
If a metal reinforcing ring is molded within the disk, then the disk structure is strengthened, but the ring adds to the cost and becomes scrap after use
Solution Approach 1:
The patent recovers the support ring after use by separating it from the formed socket. The ring is not discarded with the socket but is instead removed and reused for subsequent sockets. This recovery process eliminates the continuous generation of scrap rings while maintaining the structural support needed during the forming process.
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
This approach significantly reduces production time and cost while minimizing equipment requirements by allowing the reuse of the support ring and minimizing scrap material, resulting in a more efficient and cost-effective method for creating prosthetic limb sockets.
Implementation Method 1
the square plastic sheet softens
Implementation Method 2
a vacuum within the hollow model and through fine holes or pores within the model
Data Source
AI summary
A preform for making a prosthetic limb socket includes an injection molded disk of thermoplastics material, and a peripheral portion of the disk is supported by a rigid metal ring. The ring and the peripheral disk portion have an interfitting connection which permits the disk and ring to be heated in an oven. The ring and softened disk are then inverted and stretched downwardly over a positive model of a residual limb while a vacuum is introduced through holes within the model to form a plastic socket which conforms to the model. The interfitting connection may be peripherally spaced studs on the ring and projecting into corresponding holes in the disk or may be an annular rib or arcuate rib sections on the ring which project into an annular recess or arcuate cavities within the disk. After the plastic cools, the ring is separated for reuse.