Screw Preload Measurement Using a Tensile Force Transducer
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for assessing the quality of tightening tools, such as industrial screwdrivers, are inaccurate due to variability in the behavior of simulated brakes and bolts, leading to inconsistent measurements of torque and angle during screw tightening.
Innovation Solution
A device that measures the preloading of a screw in a joint using a transducer with a resistive sensor and Wheatstone bridge configuration, which senses the tensile stress generated during screwing, allowing for precise assessment of the tightening process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If torque and angle measurements are used to assess tightening tool quality, then the assessment can be performed during the tightening sequence, but the measurements are inaccurate due to variability in brake behavior
Solution Approach 1:
The patent introduces a transducer as an intermediary element between the screw and the measurement system. This transducer directly measures the tensile force generated during tightening, serving as a mediator that provides accurate measurements without being affected by the variability of brake behavior. The transducer converts the mechanical tensile force into measurable signals, eliminating the need to rely on brake uniformity for accurate assessment.
Solution Approach 2:
The patent replaces the mechanical measurement approach (measuring torque and angle through brakes) with a direct force measurement approach using a transducer. Instead of indirectly assessing tightening quality through mechanical parameters that depend on brake uniformity, the system directly measures the tensile force, substituting the mechanical measurement chain with a more direct and reliable sensing mechanism.
2Measurement precision
If a transducer is used to measure tensile force directly, then measurement accuracy improves, but the device complexity increases
Solution Approach 1:
The transducer is designed to perform multiple functions: it serves as both the mounting structure for the leadscrew and the measurement element for detecting tensile force. By integrating these functions into a single component, the patent reduces overall device complexity while maintaining measurement accuracy. The sensor is similarly integrated into the transducer structure, further consolidating the system.
Solution Approach 2:
The patent employs a nested structure where the leadscrew is constrained within the transducer, and the sensor is integrated within the transducer structure. This nesting approach allows multiple components to occupy the same space efficiently, reducing the overall device footprint and complexity while maintaining all necessary measurement and structural functions.
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 device provides accurate and uniform measurements of tensile force, enabling improved evaluation of tightening tool quality by accounting for friction and rigidity coefficients, thus enhancing the assessment of screwdriver performance.
Implementation Method 1
The aforesaid transducer comprises a preferably cylindrical upper portion 41 joined to a base disc 42... At least one sensor 43 capable of sensing the tensile stress undergone by the transducer is provided on the lateral surface of the cylindrical portion
Implementation Method 2
A device that measures the preloading of a screw in a joint using a transducer with a resistive sensor and Wheatstone bridge configuration, which senses the tensile stress generated during screwing
Data Source
Figure 1~2a
Figure 2b~5
Figure 4~7
AI summary
A device for measuring the preloading of a screw during a screwing operation comprising a container body (2) in which a support (3) is inserted, inside which there is a leadscrew into which such screw (V) is screwed by means of a tightening tool, at the bottom of such support and connected thereto a transducer (4) 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.