Sealed Fastener Head Geometry to Reduce Bacterial Harborage

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Solution Overview

Problem

Conventional fasteners in robotic systems and high-vibration environments face challenges in sealing against foreign contaminants and reducing the risk of surface damage, as they often have crevices that harbor contaminants and can be difficult to clean, leading to contamination hazards.

Innovation Solution

A fastener design featuring a concave sealing surface, a bearing surface positioned internally, an angled flange to shed liquids, and a tool-receiving protrusion without recesses, which reduces the likelihood of contaminant intrusion and surface damage, and includes a centering pilot for precise alignment and uniform compression of a sealing ring.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If conventional fasteners are used, then the fastening function is achieved, but crevices and surface roughness harbor contaminants making cleaning difficult

Engineering Contradiction:

Improvecontaminant harborageVSAvoidfastener structure complexity

Core Design Contradiction:

Object-affected harmful factorsVSEase of manufacture

Solution Approach 1:

The fastener head is segmented into distinct functional surfaces: a bearing surface for contact with the workpiece, a sealing surface for receiving the sealing ring, and a flange with specific geometry. This segmentation allows each surface to be optimized for its specific function while collectively reducing contaminant harborage points

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different surfaces of the fastener are given different geometric qualities tailored to their function: the bearing surface is flat and smooth for even contact, the sealing surface has specific curvature to maintain sealing ring contact, and the flange has an angled configuration to shed liquids. This local optimization reduces areas where contaminants can accumulate

Inventive Principle:

Principle #3Local quality

2Reliability

If fasteners are added to attach surfaces, then the attachment function is achieved, but foreign materials can work into interstices between fastener and surface

Engineering Contradiction:

Improvesealing capabilityVSAvoidfastener component count

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

A sealing ring is introduced as an intermediary element between the fastener and the workpiece surface. This sealing ring fills the interstice that would otherwise exist between the fastener bearing surface and the workpiece, preventing foreign materials from working into the joint while maintaining the attachment function

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The sealing ring is nested within the fastener assembly, specifically received by the sealing surface of the fastener head. This nested configuration allows the sealing function to be integrated into the fastener structure without adding external complexity to the overall assembly

Inventive Principle:

Principle #7Nested doll (Nesting)

3Ease of operation

If fasteners have crevices for tool engagement, then tool-handling is enabled, but the slot on screw head can harbor contaminants

Engineering Contradiction:

Improvetool engagementVSAvoidcontaminant accumulation in fastener features

Core Design Contradiction:

Ease of operationVSObject-affected harmful factors

Solution Approach 1:

The traditional recessed slot for tool engagement is extracted and replaced with a protruding tool-receiving feature. This protrusion extends from the fastener head surface, providing tool engagement capability while eliminating the recessed cavity that would otherwise harbor contaminants during tightening operations

Inventive Principle:

Principle #2Taking out (Extraction)

4Strength

If fasteners are tightened against surface, then the attachment is secured, but tools may contact and mar the surface of the object

Engineering Contradiction:

Improveattachment securityVSAvoidsurface marring

Core Design Contradiction:

StrengthVSObject-affected harmful factors

Solution Approach 1:

The flange is designed with an angled configuration that preliminarily directs liquids and potential contaminants away from the bearing surface before the tool makes contact during tightening. This preliminary action protects the workpiece surface from marring while still allowing the tool to engage the fastener for secure attachment

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentUS11059188B2Fasteners with reduced bacterial harborage points, sealing capabilities, and component protection features

Publication Date: 2021.07.13 SCHMALZ FLEXIBLE GRIPPING INC

AI summary

Exemplary embodiments relate to a fastener suitable for industrial tasks. Some embodiments include a sealing surface sized so that an outer surface of a sealing ring is located at approximately the same diameter as the fastener head, thus reducing ingress risk for foreign contaminants. Further embodiments provide a centering pilot to improve sealing consistency and quality. Some embodiments provide an angled flange on the fastener head to lift tightening tools away from the surface to which the fastener is being applied, and to shed liquids readily. The portion of the head that receives the tightening tools may be relatively small (approximately the same diameter as the fastener's threaded shaft) to reduce the risk of over-torquing. A bearing surface of the fastener may be located below the sealing ring (towards the threaded shaft) to prevent the fastener from marring the unsealed surface to which the fastener is being applied.