Parallel Safety Chain for Heavy Pipe Tool Tether

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Solution Overview

Problem

Heavy pipe end prep tools, weighing over 600 lbs., pose a safety hazard due to the risk of drawbar springs breaking when overloaded, causing the tool to unexpectedly drop, which can result in injury and equipment damage.

Innovation Solution

A safety tether system comprising a safety chain that operates in parallel with the drawbar springs, providing a load rating several times the weight of the tool and ensuring the chain is locked between the tool and a fixed support without compromising its integrity, preventing the springs from bottoming out and reducing the likelihood of breakage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If drawbar springs are used to support the weight of the heavy pipe end prep tool, then the operator can shake or rock the tool to ensure proper centering, but the springs may bottom out and break when extended to their maximum load limit, causing the tool to unexpectedly drop

Engineering Contradiction:

Improveability to shake or rock the tool for centeringVSAvoidrisk of spring breakage and tool dropping

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

A safety chain is installed in parallel with the drawbar springs to provide a backup support mechanism before the springs can bottom out and break. The safety chain is positioned to engage and limit the extension of the springs, preventing them from reaching their maximum load limit and reducing the risk of breakage while allowing the operator to shake or rock the tool for proper centering.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

Solution Approach 2:

The safety chain acts as an intermediary element between the tool and the support structure, providing an additional layer of protection. When the drawbar springs approach their extension limit, the safety chain engages to prevent further extension, thereby protecting the springs from breaking while still allowing the necessary movement for tool centering.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If the safety chain is made very strong with a load rating several times that of the tool weight, then it provides a significant safety factor, but it may be difficult to lock the chain between the tool and fixed support without compromising the chain's integrity

Engineering Contradiction:

Improvesafety factor against tool droppingVSAvoiddifficulty of installing lock without compromising chain integrity

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The locking mechanism is extracted from the chain itself and implemented as a separate component system. The chain remains intact and undamaged, while separate locking components (such as locks or retainers) are used to secure the chain between the tool and the fixed support, thus maintaining the chain's full strength and integrity while providing the necessary safety factor.

Inventive Principle:

Principle #2Taking out (Extraction)

3Reliability

If the safety chain length is made shorter than the spring's extended length, then it prevents the springs from bottoming out, but it may interfere with the full range of motion needed for tool manipulation

Engineering Contradiction:

Improveprevention of spring bottoming outVSAvoidrange of motion for tool manipulation

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The safety chain is designed with appropriate length and attachment geometry to dynamically adapt to the tool's movement requirements. The chain length is carefully selected to engage the springs at or near their maximum safe extension point while still allowing the tool sufficient range of motion for shaking and rocking during centering operations. The parallel arrangement of the chain with the springs allows both components to work together dynamically throughout the tool's operational range.

Inventive Principle:

Principle #15Dynamics

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

The safety tether system effectively prevents the tool from falling by distributing the weight and providing a significant safety factor, reducing the risk of spring breakage and ensuring operator safety during manual manipulation of heavy tools.

Implementation Method 1

at least one expandable spring having a characteristic maximum load rating and interconnected between said first and second end brackets

Methodology Applied

Scientific EffectElasticity: Elasticity

Implementation Method 2

a safety chain interconnected between said first and second end brackets in parallel with said at least one spring, said chain having an extended length less than a length of said at least one spring when extended to a predetermined limit

Methodology Applied

Scientific EffectMechanical constraint:

Data Source

PatentUS8439326B2Safety tether for pipe end prep tool

Publication Date: 2013.05.14 ESCO TOOL

AI summary

A safety tether is provided for securing a heavy work tool. The safety tether includes one or more springs that serve to carry some of the weight of the work tool. A safety chain is provided in parallel connection with the springs. The length of the chain is less than the extended length of a spring at its maximum rated load, thus precluding extension of the springs to that link, greatly reducing any likelihood that the springs will break. In the event of spring breakage, the chain serves as a safety chain, stopping the tool from falling.