Impact Tool Motor Control for Tightening Precision
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Solution Overview
Problem
Existing impact tools may continue to rotate the motor after a fastening member is tightened, leading to over-tightening.
Innovation Solution
An impact tool with a control unit that performs vector control on the motor, includes an impact detection unit to determine if an impact operation is being performed, and executes restriction processing by lowering or stopping the motor's revolutions when the impact operation is detected.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the motor continues to rotate after the fastening member is tightened, then the productivity is improved by maintaining continuous operation, but the manufacturing precision deteriorates by over-tightening the fastening member
Solution Approach 1:
The control unit monitors the current value from the motor during operation and detects impact operations through current fluctuations. When impact is detected, the control unit automatically adjusts motor rotation speed or stops rotation, creating a closed-loop feedback system that prevents over-tightening while maintaining continuous operation capability
Solution Approach 2:
The control unit is pre-programmed with impact detection algorithms that monitor current patterns and predict when the fastening member will be fully tightened. By detecting impact operations before actual over-tightening occurs, the system takes preliminary action to adjust motor rotation, preventing the harmful effect before it happens
Data Source
AI summary
An impact tool includes a motor, a control unit, an output shaft, a transmission mechanism, and an impact detection unit. The transmission mechanism includes an impact mechanism. The impact mechanism performs an impact operation according to magnitude of torque applied to the output shaft. The impact detection unit determines, based on at least one of an excitation current (current measured value) to be supplied to the motor or a torque current (current measured value) to be supplied to the motor, whether or not the impact operation is being performed. The control unit fulfills an impact response function by performing restriction processing in response to detection of the impact operation by the impact detection unit as a trigger. The restriction processing includes at least one of lowering the number of revolutions of the motor or stopping rotating the motor.