Screw With Integrated Extensometer for Tightening Force Measurement
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Solution Overview
Problem
Existing screw tightening force measurement methods are time-consuming, difficult to implement, and weaken the screw due to machining processes, failing to reliably measure static tightening force over time due to factors like thermal stress and vibrations.
Innovation Solution
A screw with a housed extensometer and electronic components, including a coil, power supply, and microprocessor, allowing for contactless energy transmission and wireless measurement signal transmission, enabling quick, easy, and robust measurement of tightening force without the need for batteries or direct electrical connections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If an extensometer is fitted inside the screw shank to measure tensile force, then measurement capability is provided, but the screw becomes weaker and more difficult to manufacture due to additional machining processes
Solution Approach 1:
The measuring element is housed inside a cavity within the screw shank, nesting the measurement function within the existing screw structure. This allows the extensometer to be protected and integrated without requiring external attachments that would compromise screw strength.
Solution Approach 2:
A cavity is introduced as an intermediary structure within the screw shank to house the measuring element. This cavity serves as a mediator that accommodates the extensometer while maintaining the overall structural integrity of the screw through proper design and positioning.
2Measurement precision
If traditional extensometer installation methods are used inside the screw, then measurement is enabled, but the measuring process becomes time-consuming and difficult
Solution Approach 1:
The cavity for housing the measuring element is pre-formed during screw manufacturing, and the extensometer is pre-positioned within this cavity before final assembly. This preliminary preparation eliminates time-consuming on-site installation procedures and simplifies the measurement setup process.
Solution Approach 2:
The screw structure itself provides the cavity and housing for the measuring element, making the measurement system self-contained. The screw design incorporates the measurement capability intrinsically, eliminating the need for complex external measurement apparatus and reducing setup complexity.
3Use of energy by moving object
If batteries or direct electrical connections are used to power the extensometer, then continuous power supply is provided, but the screw design becomes more complex and robustness is reduced
Solution Approach 1:
The patent replaces traditional mechanical power supply methods (batteries, wires, direct electrical connections) with a contactless electromagnetic induction system. A coil wound around the screw shank serves as a transformer primary, inducing current in the extensometer through magnetic coupling, thereby eliminating the need for physical electrical connections and reducing design complexity.
Solution Approach 2:
Electromagnetic induction serves as an intermediary mechanism for power transfer. The coil and extensometer form a transformer system where magnetic fields act as the mediator to transfer energy without direct electrical contact, simplifying the overall system design while maintaining power supply functionality.
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 rapid, precise, and reliable measurement of screw tightening force at any time after assembly, reducing energy consumption and maintaining screw robustness by using contactless power supply and efficient energy transfer, allowing for precise data transmission and improved precision through averaging multiple measurements.
Implementation Method 1
The power supply is connected to the coil to receive electrical energy from the coil itself... the coil is configured to define a contactless transmission line, constituting a secondary (or primary) of a transformer
Implementation Method 2
the extensometer is fitted inside the shank of the screw to measure the tensile force the screw itself is subjected to
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
A screw (1) comprises: a threaded shank (101) extending along a longitudinal axis (103); a head (102) engageable by a tightening tool to tighten the screw; an extensometer (106) housed in a longitudinal cavity (104) made in the shank (101), to measure a measurement parameter representing a tightening force of the screw; a coil (3), a power supply (4), a microprocessor (5) and a transmitter, all located in a housing (107) made in the head (102). The power supply (4) is connected to the coil (3) to receive electrical energy by electromagnetic induction through a contactless transmission line (7), and to the microprocessor (5) and extensometer (106) to supply them with electric power. The microprocessor (5) is connected through a conditioning module (6) to the extensometer (106) to receive the measurement parameter and to the transmitter to transmit the measurement parameter to the outside of the screw through a wireless measurement signal.