Flexible Safety Cap for Variable Diameter Tool Shafts

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Solution Overview

Problem

Existing cup-shaped safety caps with low intrinsic elasticity can only accommodate tool shafts with diameters slightly different from their own, leading to high friction and risk of abrasion particle entrainment during extraction, making them unsuitable for clamping surgical instruments or objects with varying diameters.

Innovation Solution

A safety cap with a non-round clamping profile, featuring a slot adjacent to the front wall that decouples the clamping walls from the front wall, allowing for elastic deformation and accommodating a wide range of diameters without particle entrainment, using a permanently elastic plastic material like PP or TPE.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If a cup-shaped safety cap with low intrinsic elasticity is used, then the structure is simple and easy to manufacture, but it can only accommodate tool shafts with diameters slightly different from its own diameter

Engineering Contradiction:

Improveease of manufactureVSAvoidadaptability to different diameters

Core Design Contradiction:

Ease of manufactureVSAdaptability or versatility

Solution Approach 1:

The safety cap transitions from a rotationally symmetrical cup shape to an asymmetrical D-shaped cross-section with a flat side and a rounded side. This asymmetry allows the flat side to deform more easily under compressive force, enabling the cap to accommodate tool shafts with a wide range of diameters while maintaining simple manufacturing processes

Inventive Principle:

Principle #4Asymmetry

2Device complexity

If a cup-shaped safety cap with low intrinsic elasticity is used, then the structure is simple, but high friction occurs when shafts of larger diameter are inserted and clamped

Engineering Contradiction:

Improvestructural simplicityVSAvoidfriction and abrasion

Core Design Contradiction:

Device complexityVSObject-affected harmful factors

Solution Approach 1:

The D-shaped cross-section with its flat side creates an asymmetrical clamping interface that reduces friction. When compressive force is applied to the flat side, the cap deforms in a controlled manner that accommodates larger diameter shafts without creating high friction contact, thereby preventing abrasion of the shaft surface

Inventive Principle:

Principle #4Asymmetry

Solution Approach 2:

The safety cap utilizes changes in geometric parameters through elastic deformation. The flat side of the D-shape allows for greater deformation range, enabling the internal diameter to adjust dynamically to accommodate different shaft diameters while maintaining low friction contact

Inventive Principle:

Principle #35Parameter changes

3Ease of operation

If finger pressure is applied to the side walls to remove the safety cap, then the cap can be extracted, but the clamping connection is tightened in an undesirable manner

Engineering Contradiction:

Improveease of removalVSAvoidclamping force

Core Design Contradiction:

Ease of operationVSForce

Solution Approach 1:

The asymmetrical D-shape with its flat side allows for directional application of compressive force. When force is applied to the flat side during removal, the cap deforms in a specific pattern that reduces clamping force on the shaft, enabling easy extraction without tightening the clamping connection

Inventive Principle:

Principle #4Asymmetry

4Shape

If a rotationally symmetrical cup shape is used, then the geometry is simple, but only shafts with diameter slightly different from the safety cap diameter can be reliably clamped

Engineering Contradiction:

Improvegeometric simplicityVSAvoiddiameter range

Core Design Contradiction:

ShapeVSAdaptability or versatility

Solution Approach 1:

The patent employs an asymmetrical D-shaped cross-section instead of a rotationally symmetrical circle. This asymmetry, particularly the flat side, enables the cap to deform more effectively under compressive force, expanding the range of tool shaft diameters that can be reliably clamped from approximately 10-11mm to a much broader range including 5-10mm

Inventive Principle:

Principle #4Asymmetry

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

Enables reliable clamping of tool shafts with diameters between 5 and 10 mm without friction or particle dislodgment, ensuring safe extraction and adaptability to various tool geometries, while maintaining visibility and allowing sterilization and cleaning access.

Implementation Method 1

made of a permanently elastic plastic material like PP or TPE

Methodology Applied

Scientific EffectElasticity: Elasticity

Data Source

PatentUS9663279B2Flexible safety cap for accommodating shafts of different diameters

Publication Date: 2017.05.30 ROSE PLASTIC

AI summary

A flexible safety cap (1) for accommodating any tool (13, 14) among a group of tools having different diameters or different geometries, said cap having a terminating front wall (10) and an oppositely disposed clamping opening (8, 8′) with at least one non-round, acting clamping profile (5, 5′, 5″, 5′″, 5″″) wherein at least one slot (9) that penetrates through the wall of the safety cap (1) is disposed in the vicinity of the front wall (10) to establish an elastic, resilient clamping connection between an outside circumference of the tool (13, 14) and an inside wall of the safety cap (1).