Screw Preload Measurement Using a Leadscrew Force Transducer
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Solution Overview
Problem
Existing methods for assessing the quality of tightening tools, such as industrial screwdrivers, are not very accurate due to inconsistencies in the behavior of simulated brakes, leading to errors in measuring torque and angle during screwing operations.
Innovation Solution
A device with a transducer and resistive sensor system that measures tensile stress on a leadscrew, allowing for precise assessment of the preloading of screws during tightening, using a Wheatstone bridge configuration and an electronic board for signal management, and a greasing system for lubrication.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If torque and angle are measured during screwing to assess tightening tool quality, then the assessment can be performed, but the measurement accuracy is poor due to brake uniformity errors
Solution Approach 1:
The patent introduces a transducer as an intermediary element between the screw and the measurement system. This transducer contains a leadscrew that converts the rotational tightening action into linear tensile force, which is then measured by a force sensor. This intermediary mechanism eliminates the need for direct torque and angle measurements that were previously affected by brake uniformity errors, thereby resolving the contradiction between measurement accuracy and brake reliability.
2Measurement precision
If tensile force is measured on a transducer during tightening, then the assessment accuracy improves, but the device complexity increases
Solution Approach 1:
The patent replaces the complex mechanical measurement system (torque sensors, angle encoders, brake mechanisms) with a simpler force measurement system. By using a leadscrew mechanism combined with a single force sensor on the transducer, the system achieves accurate assessment of tightening quality through tensile force measurement alone, thereby improving assessment accuracy while reducing overall device complexity.
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 and uniform measurement of tensile force, improving the assessment of tightening tool quality by providing reliable data on the true torsion applied to the system, accounting for friction and rigidity coefficients.
Implementation Method 1
using a Wheatstone bridge configuration
Implementation Method 2
resistive sensor system that measures tensile stress
Implementation Method 3
greasing system for lubrication
Data Source
AI summary
A device for measuring the preloading of a screw during a screwing operation including a container body in which a support is inserted, inside which there is a leadscrew into which such screw is screwed by a tightening tool, at the bottom of such support and connected thereto a transducer being arranged, capable of measuring the traction generated on itself as a result of the compression created by the screwing of the screw into the leadscrew.