Tong Assembly Load Cell with Biasing Alignment

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Solution Overview

Problem

Conventional load cells for tong assemblies used in oil and gas well construction are expensive due to complex manufacturing and assembly processes, necessitating a more cost-effective solution for accurately measuring torque in tubular connections.

Innovation Solution

A load cell design featuring a body with a chamber containing strain gauges, a first eye for pivotal coupling to the power tong, and a second eye with a biasing member for alignment with the backup tong, allowing for accurate torque measurement and alignment during operation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If conventional load cells are used for torque measurement in tong assemblies, then measurement precision is maintained, but manufacturing cost and device complexity increase significantly

Engineering Contradiction:
Improvetorque measurement precisionVSAvoidload cell structure complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The load cell is segmented into distinct functional components: a body portion with integrated strain gauges, eye portions for coupling, and a biasing member for alignment. This segmentation allows each component to be optimized independently and assembled from standard parts, reducing overall manufacturing complexity while maintaining measurement precision through the strategic placement of strain gauges in the body portion.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The load cell body serves multiple functions simultaneously: it acts as the structural element that experiences torque-induced strain, houses the strain gauge sensors, and provides mounting points for the eye portions. This multi-functionality reduces the number of separate components needed, simplifying the overall device structure while maintaining accurate torque measurement capabilities.

Inventive Principle:
Principle #6Universality (Multi-functionality)

2Measurement precision

If conventional load cells with complex parts and machining are used, then measurement accuracy is achieved, but manufacturing cost increases

Engineering Contradiction:
Improvetorque measurement accuracyVSAvoidmanufacturing cost
Core Design Contradiction:
Measurement precisionVSEase of manufacture

Solution Approach 1:

The load cell is designed using inexpensive, easily manufacturable materials and components. The body is made from cost-effective materials that can be produced through simple casting or machining processes, and the strain gauges are standard off-the-shelf components rather than custom-made sensors. This approach significantly reduces manufacturing cost while maintaining sufficient measurement accuracy for torque monitoring applications.

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

Solution Approach 2:

The biasing member is designed to automatically align the load cell with the backup tong during operation, eliminating the need for complex alignment mechanisms or manual adjustment procedures. This self-aligning feature reduces manufacturing complexity and cost by replacing what would otherwise require precision machining and assembly fixtures with a simple spring-loaded alignment system.

Inventive Principle:
Principle #25Self-service

3Ease of manufacture

If a simple load cell structure is used, then manufacturing cost is reduced, but alignment accuracy and measurement reliability deteriorate

Engineering Contradiction:
Improvemanufacturing simplicityVSAvoidalignment accuracy
Core Design Contradiction:
Ease of manufactureVSReliability

Solution Approach 1:

The biasing member functions as a counterbalancing element that automatically compensates for misalignment between the load cell and the backup tong. By applying a restoring force that pushes the load cell into proper alignment, the biasing member ensures reliable torque measurement without requiring complex alignment fixtures or precision machining, thus maintaining both manufacturing simplicity and measurement reliability.

Inventive Principle:
Principle #8Anti-weight (Counterweight)

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 solution provides a cost-effective means to measure torque in tubular connections, ensuring the joint is neither too loose nor too tight, while the biasing member ensures proper alignment and accurate data collection, enhancing operational efficiency.

Implementation Method 1

a strain gauge disposed in the chamber

Methodology Applied
Scientific EffectStrain gauge measurement: Piezoresistive Effect

Implementation Method 2

A biasing member is disposed around the second eye for biasing the body relative to the tong assembly

Methodology Applied
Scientific EffectElastic restoration: Elasticity

Data Source

PatentEP4139557B1Load cell for a tong assembly
Publication Date: 2024.01.03 WEATHERFORD TECHNOLOGY HOLDINGS LLC
  • EP4139557B1 patent drawingFigure 1A
  • EP4139557B1 patent drawingFigure 1B
  • EP4139557B1 patent drawingFigure 1C~1D

AI summary

A load cell for use with a tong assembly includes a body; a chamber formed in the body; and a strain gauge disposed in the chamber. The load cell also includes a first eye for pivotal coupling to the tong assembly, and a second eye for pivotal coupling to the tong assembly. An optional biasing member is disposed around the second eye for biasing the body relative to the tong assembly.