Tethering Assembly for Grinders Using Mechanical Fasteners

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Solution Overview

Problem

Existing tethering methods for power hand tools like grinders and cut-off tools are cumbersome, unsafe, and prone to failure due to lack of suitable attachment points, leading to potential tool entanglement or damage from moving parts and heat.

Innovation Solution

A tethering assembly kit with ring connectors and a wire rope sling that attaches to the power hand tool's gear housing, positioning the tether-connector loop away from the tool's working parts, ensuring secure and safe tethering without interfering with the tool's operation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the tether is wrapped around the gear housing and secured with bonding tape, then the tether can be attached to the tool, but the bonding tape is prone to slip off when the tool body gets hot from use

Engineering Contradiction:

Improvetether attachment reliabilityVSAvoidtool body temperature

Core Design Contradiction:

ReliabilityVSTemperature

Solution Approach 1:

The patent replaces the chemical bonding method (bonding tape) with a mechanical attachment system. Ring connectors are secured to the gear housing using mechanical fasteners such as clips, snap-fit mechanisms, or set screws, which maintain secure attachment regardless of temperature increases during tool operation.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The tethering system is divided into separate functional components: ring connectors attach to the gear housing, the sling connects the ring connectors, and the tether attaches to the worker. This segmentation allows each component to be optimized independently, with the attachment mechanism designed specifically for thermal environment resistance.

Inventive Principle:

Principle #1Segmentation

2Ease of manufacture

If the tether is wrapped around the gear housing, then the tether can be attached to the tool, but the tether is positioned close to the moving parts and can become entangled with the rotating tool head or be severed by the grinding/cutting wheel

Engineering Contradiction:

Improvetether attachment simplicityVSAvoidtether entanglement and damage risk

Core Design Contradiction:

Ease of manufactureVSObject-affected harmful factors

Solution Approach 1:

The ring connectors are positioned on the gear housing in a location that projects the tether attachment point away from the rotational plane of the cutting wheel. The sling is configured to extend rearward and upward, positioning the tether connection in three-dimensional space clear of the tool's moving parts, thereby eliminating entanglement risks while maintaining simple attachment.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

3Ease of manufacture

If the tether is wrapped around the gear housing, then the tether can be attached to the tool, but the tether may be burned from sparks emitted from the work piece

Engineering Contradiction:

Improvetether attachment simplicityVSAvoidspark-induced tether damage

Core Design Contradiction:

Ease of manufactureVSObject-affected harmful factors

Solution Approach 1:

The sling acts as an intermediary component that positions the tether away from the hazard zone. By routing the tether through the sling and securing it at a distance from the cutting wheel, the system creates a physical barrier and spatial separation that protects the tether from spark exposure while maintaining the simplicity of attachment.

Inventive Principle:

Principle #24Intermediary (Mediator)

4Shape

If the tool body reduces in size towards the rear end, then the tool design is compact and ergonomic, but the bonding tape is prone to slip off the gear housing

Engineering Contradiction:

Improvetool body shapeVSAvoidtether attachment reliability

Core Design Contradiction:

ShapeVSReliability

Solution Approach 1:

The patent replaces the bonding tape system that relied on surface adhesion with a mechanical attachment system using ring connectors secured by clips, snap-fit mechanisms, or set screws. These mechanical fasteners engage with positive geometry on the gear housing, providing reliable attachment that is independent of the tool body's tapering shape or thermal conditions.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Data Source

PatentUS11173593B2Tethering assembly and method for grinders and like tools

Publication Date: 2021.11.16 PURE SAFETY GROUP INC

AI summary

A combination power hand tool and tethering assembly comprises a power hand tool selected from the group consisting of a grinder, a polisher, a cut-off tool, and a drill. The hand tool has a gear housing with a fastener bore configured and arranged to receive a fastener. The tethering assembly comprises a connector having a fastener opening and a tether configured and arranged to be connected to the connector. The fastener extends through the fastener opening and into the fastener bore thereby connecting the connector and the power hand tool. The tether is configured and arranged to be selectively coupled to one of a worker and an anchor object thereby selectively interconnecting the connector and the one of the worker and the anchor object.