Electric Pulse Tool Self-Correction for Accurate Screw Tightening
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Solution Overview
Problem
Electric pulse tools face challenges in maintaining accuracy and ergonomics during tightening operations, as powerful torque pulses can lead to over-tightening, requiring corrections and increasing the risk of damaging screw joints, while also straining operators due to high reaction forces and prolonged operation times.
Innovation Solution
An electric pulse tool equipped with sensors and a processor that delivers torque pulses in two directions, adjusting to reach and correct torque levels within predetermined intervals, allowing for rapid and reliable tightening with reduced operator strain.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If powerful torque pulses are provided to quickly build up clamp force, then productivity is improved, but accuracy deteriorates due to increased risk of missing target torque
Solution Approach 1:
The tightening process is divided into multiple discrete torque pulses instead of continuous application. Each pulse is controlled individually, allowing the system to approach the target torque in incremental steps. This segmentation enables both rapid tightening (through multiple quick pulses) and accurate control (by adjusting individual pulse magnitudes and counting pulses until target is reached).
Solution Approach 2:
The torque pulse characteristics are made dynamic and adaptive. The control system adjusts pulse magnitude, frequency, and duration based on real-time feedback from torque sensors and angle meters. This dynamic adjustment allows the system to maintain accuracy while achieving rapid tightening by optimizing pulse parameters during the tightening process rather than using fixed powerful pulses throughout.
2Use of energy by moving object
If fewer torque pulses are provided to improve energy efficiency, then energy consumption is reduced, but accuracy deteriorates due to increased risk of over-tightening
Solution Approach 1:
Real-time feedback from torque sensors and angle meters during each pulse enables precise control. The system continuously monitors the tightening state and adjusts subsequent pulses accordingly, allowing accurate achievement of target torque with fewer pulses. The feedback mechanism prevents over-tightening by detecting when the target is reached or exceeded, eliminating the need for excessive safety margins that would require more pulses.
Solution Approach 2:
The system dynamically changes torque pulse parameters (magnitude, duration, frequency) based on the current tightening state. By adapting pulse characteristics to the specific requirements of each tightening operation and real-time conditions, the system achieves accurate torque application with minimal pulses, optimizing both energy efficiency and precision.
3Loss of time
If high torque pulses are used to reduce operation time, then productivity is improved, but ergonomics deteriorate due to increased reaction forces on operator
Solution Approach 1:
The total torque requirement is segmented into multiple smaller pulses distributed over time. This segmentation reduces the peak reaction force experienced by the operator during any single pulse, making the tool easier to handle. The cumulative effect of multiple smaller pulses achieves the same tightening result as fewer large pulses, maintaining productivity while improving ergonomics.
Solution Approach 2:
The tightening is achieved through periodic torque pulses rather than continuous or single large pulses. This periodic action allows brief intervals between pulses where the operator can maintain control and react to tool behavior. The rhythmic nature of pulsed operation reduces operator fatigue and improves comfort compared to sustained high-torque application, while still achieving rapid tightening through optimized pulse sequences.
Data Source
Figure 1
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AI summary
Electric pulse tool (10) that can correct itself if the determined parameter value associated with the tightening of a screw joint exceeds the target parameter value, the tool comprising: an output shaft (12); a sensor (14), (15), (25) arranged to determine a parameter value associated with the tightening of the screw joint; a processor (16) and a memory (26). Whereby the electrical pulse tool (10) is operative to: provide torque pulses on the output shaft (12) in a first direction until the determined parameter value associated with the tightening of the screw joint reaches within or above a predetermined first interval including a target parameter value. And provide at least one torque pulse on the output shaft (12) in a second direction that is opposite to the first direction in case the determined parameter value exceeds the target parameter value within a predetermined second interval.