Impulse Wrench Screw Joint Quality Assessment via Ultrasonic and Angular Measurement
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Solution Overview
Problem
Existing methods, such as ultrasonic techniques, struggle to accurately determine the quality and reliability of screw joint tightening processes using torque impulse wrenches, as they fail to detect faults like wrong clamp length or premature yield, due to the intermittent dynamic action and potential equipment malfunctions.
Innovation Solution
Combining ultrasonic clamp load indication with angular displacement measurements from an angle encoder to provide independent verification of the tightening process, ensuring reliable detection of faults and quality assessment by comparing lapsed angular displacement against predetermined limits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If ultrasonic technique is used to measure clamp load, then measurement capability is provided, but measurement precision is insufficient for high precision screw joints
Solution Approach 1:
The patent combines ultrasonic clamp load indication with torque measurement to create a dual-parameter assessment system. By merging these two independent measurement methods, the system can cross-validate results and detect faults that would be missed by either method alone, such as wrong clamp length or premature yield that affect joint quality without necessarily changing clamp load.
Solution Approach 2:
The patent introduces torque measurement as an intermediary parameter to verify the validity of ultrasonic clamp load measurements. The torque value serves as a reference point to determine whether the ultrasonic measurement is reliable, allowing the system to identify when ultrasonic measurements may be erroneous due to faulty screw joint parts.
2Loss of information
If torque sensor is used to measure delivered torque, then torque information is obtained, but reliability is low due to intermittent dynamic action of impulse wrench
Solution Approach 1:
The patent performs torque measurement during the tightening process rather than attempting to measure the final static torque. By measuring torque impulses during the dynamic tightening process, the system captures information that would be lost if only final static measurement were attempted, while using the cumulative effect to overcome the intermittency problem.
Solution Approach 2:
The patent utilizes the periodic nature of impulse wrench operation, measuring torque during each impulse cycle. By taking multiple torque measurements during the intermittent dynamic action and processing them collectively, the system extracts reliable torque magnitude information that would be impossible to obtain from a single static measurement.
3Device complexity
If single measurement method is used, then simplicity is maintained, but detection capability is insufficient to identify all screw joint faults
Solution Approach 1:
The patent merges ultrasonic measurement and torque measurement into a unified assessment system that evaluates both clamp load and torque parameters. This combination enables detection of multiple fault types including wrong clamp length, premature yield, and peak-jumping, which would be undetectable with a single measurement method while maintaining manageable system complexity through integrated processing.
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
This method enhances the accuracy of screw joint quality assessment by identifying faults and ensuring safety and reliability in the tightening process, even when ultrasonic measurements are erroneous, thereby guaranteeing the quality and safety of the structure.
Implementation Method 1
an ultra sonic wave element (24) and a control unit for calculating the time of flight for the ultra sonic waves through the screw joint
Implementation Method 2
measuring the time of flight of ultrasonic waves through the screw joint
Implementation Method 3
a reading of a redundant parameter not influenced by the dynamic forces of the impulse tightening process, the total lapsed rotation angle
Data Source
AI summary
A method for determining the quality of a screw joint tightening process performed by means of a torque impulse wrench, comprising clamp load determination via calculation of the time of flight for ultra sonic waves induced into the screw joint, and comparing of a total rotation movement of the screw joint with predetermined angle limit values as a target axial load level has been indicated by the time of flight of ultra sonic waves induced in the screw joint. Occurring discrepancies between the obtained total rotation movement of the screw joint and the angle limit values would indicate a faulty screw joint and/or a malfunctioning ultra sonic wave flight time measurement, which means an unacceptable tightening process quality.