Impact Rotary Tool Shutoff Control Using Estimated Tightening Torque
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Solution Overview
Problem
Rotary impact tools face challenges in accurately achieving target torque values due to variations in screw members and tightened members, leading to inefficiencies in torque management, particularly when the actual materials differ from those used during master table creation, resulting in either under or over-tightening.
Innovation Solution
The rotary impact tool incorporates a microcomputer-based control unit with an impact detection system and torque estimation unit to calculate tightening torque values, allowing for parameter setting modes that enable the schedule controller to adjust and optimize parameter values for precise torque management, including seating determination levels and preset torque steps, based on actual tightening torque data.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a torque measurement means is provided in the output shaft to measure actual tightening torque directly, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent introduces an intermediary approach by using impact detection sensors and rotation angle sensors to indirectly measure tightening torque. Instead of directly measuring torque in the output shaft, the system detects impact forces during the tightening process and calculates torque based on the relationship between impact energy and rotation angle, thereby achieving accurate torque measurement without complex direct measurement devices
Solution Approach 2:
The patent replaces direct mechanical torque measurement with a sensing and calculation system. By substituting physical torque sensors with impact detection sensors and using computational methods to derive torque from sensor data, the system achieves accurate measurement while reducing device complexity
2Productivity
If the master table is created using predetermined screw members and tightened members, then productivity is improved through automated parameter setting, but adaptability deteriorates when actual materials differ from those used during master table creation
Solution Approach 1:
The patent makes the parameter setting dynamic by allowing real-time adjustments based on actual material conditions. The system can modify parameters during operation when material variations are detected, transitioning from static predetermined parameters to dynamic adaptive parameters, thereby maintaining both productivity and adaptability
Solution Approach 2:
The patent implements feedback mechanisms that monitor actual tightening results and material conditions, then use this information to adjust parameters. The feedback loop enables the system to learn from actual material variations and automatically adapt parameters, combining the efficiency of automated setting with the flexibility to handle material differences
3Ease of operation
If the motor is stopped automatically when a predetermined number of impacts is reached, then ease of operation is improved through automated shut-off, but manufacturing precision deteriorates when material conditions vary
Solution Approach 1:
The patent transforms the shut-off criterion from a fixed predetermined number of impacts to a dynamic value that adjusts based on actual material conditions and detected impact characteristics. The system calculates the appropriate shut-off point in real-time, enabling automated operation while maintaining precision despite material variations
Solution Approach 2:
The patent changes the parameter used for shut-off control from a fixed impact count to a variable parameter that adapts to material conditions. By modifying the shut-off criterion based on detected impact forces, rotation angles, and material response, the system maintains both automated operation and tightening precision
Data Source
Figure 1
Figure 2A~2C
Figure 3
AI summary
A mode setting unit 17 sets a parameter setting mode or a work mode. A parameter setting unit 15 sets a plurality of parameter values in the parameter setting mode. A torque estimation unit 19 calculates a tightening torque value by using a detection result from an impact detection unit 12. In a work mode, a control unit 10 stops a rotation of a motor 2 based on the plurality of parameter values set by the parameter setting unit 15 and in accordance with the tightening torque value calculated by the torque estimation unit 19. In the parameter setting mode, a work information storage unit 20 stores the tightening torque value calculated by the torque estimation unit 19 during a tightening work according to a user operation, and the parameter setting unit 15 sets the plurality of parameter values based on the tightening torque value stored in the work information storage unit 20.