Spring Force Tester with Distributed Load Cells for Low-Range Measurement
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Solution Overview
Problem
Current spring testing equipment is limited in measuring low force ranges due to friction losses and is application-specific, failing to account for all three-dimensional forces acting on springs, particularly in the low force range of 0.5N to 100N, and is not capable of general applicability.
Innovation Solution
A spring force tester system with two plate and load-cell assemblies that attach to a standard spring tester, capable of determining load distribution and penetration points at both ends of springs, using multiple load cells to measure forces and moments in various directions, and includes a method for calibration and force vector calculation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If standard spring testing equipment is used, then measurement capability is limited to high force ranges (10-20 kN), but the invention enables measurement in low force ranges (0.5-100 N)
Solution Approach 1:
The system divides the measurement function into multiple load cells (at least two, preferably three or more) distributed across separate plates. Each load cell measures force components independently, allowing the system to resolve total force into axial, radial, and moment components. This segmentation enables accurate measurement of low forces by distributing the measurement burden across multiple sensors rather than relying on a single high-capacity load cell.
Solution Approach 2:
The invention introduces plates with distributed load cells as intermediary measurement elements between the spring and the testing machine. These plates serve as force distribution and measurement interfaces, converting the spring's complex three-dimensional force application into measurable components at multiple discrete points. The load cells act as intermediaries that translate mechanical force into electrical signals for precise measurement and calculation of penetration points.
2Adaptability or versatility
If application-specific SUL testers are used, then testing capability is limited to squareness under load, but the invention provides general applicability for various spring types and force components
Solution Approach 1:
The system is designed with universal plates and distributed load cells that can accommodate various spring types (helical, wave, disc, and other cylindrical springs) and measure multiple force components (axial forces, radial forces, and moments) simultaneously. The same hardware configuration can test different spring geometries and force conditions by adjusting measurement parameters and calculation algorithms, eliminating the need for application-specific testing equipment.
Solution Approach 2:
The invention transitions from measuring only axial squareness under load (one-dimensional measurement) to capturing three-dimensional force components by distributing load cells in multiple spatial arrangements on plates. This dimensional expansion allows measurement of axial forces, radial forces, and moments simultaneously, providing comprehensive force characterization that works across diverse spring applications.
3Force
If friction losses in testing equipment are present, then measurement capability is lost in very low force ranges, but the invention achieves accurate measurement from 0.5N to 100N
Solution Approach 1:
The invention extracts and eliminates the friction problem by removing traditional friction-prone mechanical contact elements from the measurement path. Instead of using friction-based force transmission mechanisms, the system employs distributed load cells that directly sense force components through minimal-contact mounting arrangements on the plates, extracting the measurement function from friction-dependent mechanical linkages.
Solution Approach 2:
The system replaces friction-prone mechanical force transmission mechanisms with direct electrical sensing using load cells. The load cells convert mechanical force into electrical signals through piezoelectric or strain gauge effects, eliminating the need for friction-based mechanical linkages and allowing accurate measurement of very low forces down to 0.5N without energy loss to friction.
4Loss of information
If only axial forces are measured, then three-dimensional force components are not fully characterized, but the invention measures and calculates all force components including side forces and moments
Solution Approach 1:
The system segments the force measurement into orthogonal components by strategically positioning load cells on plates to capture axial forces, radial forces, and moments independently. Each load cell measures a specific force component based on its position and orientation, and the system reconstructs the complete three-dimensional force state by combining these segmented measurements through coordinate transformation and calculation algorithms.
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
Enables accurate measurement of forces ranging from 0.5N to 100N, including side forces and moments, providing comprehensive three-dimensional force component testing for various types of springs, improving the precision and applicability of spring testing beyond existing limitations.
Implementation Method 1
Each plate includes a plurality of recesses and a load cell positioned in each recess
Data Source
AI summary
A spring force component tester for determining a load distribution on each end of a spring of generally cylindrical shape using three, mutually-parallel load cells. One tester includes a lower plate and an upper plate movable with respect to the lower plate. Each plate includes a plurality of recesses and a load cell positioned in each recess. Each plurality of recesses is positioned such that a center of each recess is a point on a circle coaxial to the plate. The tester also includes a data logger that obtains and stores load cell outputs from the load cells and spring tester electronics that obtain height measurements of the upper plate and send a trigger signal to a computer. The computer executes application software when the computer receives the trigger signal that reads the load cell outputs stored in the data logger, and calculates a spring force acting along the spring axis between approximately 0.5 Newton and 100 Newton.