Tightening Device Two-Stage Torque Verification
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Solution Overview
Problem
Existing tightening devices struggle to accurately verify if a fastening member has reached the desired set torque without loosening the fastening member, particularly in applications like tightening vehicle wheel nuts, where multiple tightening cycles are needed to ensure the correct torque is applied.
Innovation Solution
A tightening device and method that utilize a motor, torque detector, and control unit to perform a first tightening process to reach a preset set torque and a second tightening process with reduced motor output, allowing phased increases and decreases in torque to confirm the fastening member is tightened to at least the second set torque, preventing over-tightening.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a fastening member is tightened to a preset torque and then loosened to check the torque, then the torque verification can be performed, but the tightening process becomes complex and time-consuming with multiple loosening and re-tightening cycles
Solution Approach 1:
The patent applies preliminary action by performing a first tightening process that intentionally applies a higher initial torque to ensure the fastening member is adequately seated and engaged before the verification stage. This preliminary tightening action prepares the joint so that the subsequent second tightening process can accurately verify the torque without requiring loosening and re-tightening cycles.
2Manufacturing precision
If additional tightening is applied to ensure the fastening member reaches the set torque, then the torque accuracy is improved, but over-tightening may occur causing damage or deformation
Solution Approach 1:
The patent applies dynamics by using a two-stage tightening process where the motor output is dynamically adjusted between stages. The first tightening process uses a higher initial output to ensure proper engagement, while the second tightening process uses a reduced initial output for precise torque verification. This dynamic adjustment of motor output prevents over-tightening while ensuring adequate torque application.
Solution Approach 2:
The patent applies feedback by using a torque detector to continuously monitor the tightening torque during both the first and second tightening processes. The control unit receives the detected torque values and compares them against preset targets, automatically adjusting the motor output to achieve the desired torque without exceeding it. This closed-loop feedback control prevents over-tightening while ensuring accurate torque application.
3Object-affected harmful factors
If the motor output is reduced in the second tightening process to prevent over-tightening, then the risk of damage is reduced, but the ability to correct inadequate tightening is limited
Solution Approach 1:
The patent applies preliminary action by ensuring the first tightening process adequately engages the fastening member with a higher initial torque. This preliminary action creates a reliable baseline, so that the subsequent second tightening process with reduced motor output can safely verify torque without risking over-tightening, while the initial engagement ensures adequate tightening was achieved.
Data Source
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AI summary
A tightening device (20) and a tightening method are able to check that a fastening member has been fastened to a desired set torque or greater after being tightened, without loosening the fastening member. The tightening device (20) executes a first tightening process of adjusting the output of a motor (24) after measured torque that is measured by a torque detector (50) has reached a preset first control start torque (VF), such that the measured torque reaches a preset first set torque in a phased manner through repeated increases and decreases in torque, and blocking power supply to the motor (24) when the measured torque reaches the first set torque, and then executes a second tightening process of driving the motor at an initial output (VO) that is less than in the first tightening process, adjusting the output of the motor after the measured torque that is measured by the torque detector has reached a preset second control start torque, such that the measured torque reaches a preset second set torque in a phased manner through repeated increases and decreases in torque, and blocking power supply to the motor (24) when the measured torque reaches the second set torque.