Multi-Axis Load Cell with Annular Flange Groove
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Solution Overview
Problem
Existing multi-axis load cells are inefficient in maximizing the rigidity ratio of the load cell body to the sensing region, leading to reduced performance and increased height due to the need for extensive machining of a one-piece cylindrical design, which compromises end stiffness and manufacturing complexity.
Innovation Solution
A two-piece load cell design with joined rigid cylindrical mounting elements and a thin-walled sensing region, featuring an annular flange and groove configuration that minimizes internal space while maintaining sufficient axial length for accurate force and moment measurement, thereby enhancing rigidity and reducing manufacturing complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a one-piece cylindrical design is used, then the load cell can be manufactured with a single structure, but the rigidity ratio of the load cell body to the sensing region is reduced and the height increases
Solution Approach 1:
The load cell is divided into two separate cylindrical portions: a first cylindrical portion and a second cylindrical portion. These portions are joined together to form the complete load cell structure. This segmentation allows each portion to be optimized independently - the first portion can be designed for maximum rigidity while the second portion contains the sensing region, thereby improving the overall rigidity ratio without increasing height.
2Device complexity
If a one-piece cylindrical design is used, then the structure is simple, but the manufacturing complexity increases due to extensive machining requirements
Solution Approach 1:
By dividing the load cell into two separate cylindrical portions that are joined together, the manufacturing process can be optimized for each portion independently. This segmentation reduces the extensive machining requirements of a one-piece design, as each portion can be manufactured with less complex machining operations and then assembled through joining processes.
3Measurement precision
If the internal space between mounting elements is increased to accommodate sensing region, then the sensing region has sufficient axial length, but the mounting element rigidity is reduced
Solution Approach 1:
The segmentation into two cylindrical portions allows the sensing region to be positioned at the junction between the portions. This configuration provides sufficient axial length for accurate force and moment measurement while maintaining the rigidity of the mounting elements, as each cylindrical portion can be optimized for its specific function - one for rigidity and one for sensing.
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 two-piece design achieves improved rigidity and reduced height, with increased mass and reduced moment-induced errors, while simplifying machining and enhancing performance by allowing strain gauges to be affixed directly to the sensing region, resulting in a more efficient and effective force transducer.
Implementation Method 1
Through a mechanical arrangement, the force being sensed deforms a strain gauge. The strain gauge measures the deformation (strain) as an electrical signal, because the strain changes the effective electrical resistance of the wire.
Implementation Method 2
A Wheatstone bridge is an electrical circuit used to measure and unknown resistance by balancing two legs of a bridge circuit. One leg of which contains the unknown value.
Data Source
AI summary
A compact multi-axis load cell with opposing rigid mounting elements includes annular flanges at the perimeter of the elements. A sensing region is formed between the rigid mounting elements by bonding, as by welding or brazing, opposing annular flanges at their end surfaces. To increase the mass and rigidity of the opposing mounting elements, the annular flanges may be partially formed by a peripheral groove, the groove defining a portion of an inside surface of the annular flange. The peripheral groove provides sufficient flange length for affixing strain gauges while positioning internal surfaces of the mounting elements close together in order to reduce the overall length of the load cell. Sensing circuits affixed to the outside surface of the sensing region provide output signals responsive to forces and moments exerted between the rigid mounting elements in at least two substantially perpendicular directions.