Electric Pulse Tool Reaction Force Control
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Solution Overview
Problem
Existing power-assisted tools, particularly handheld ones, face challenges in minimizing reaction force on operators during tightening operations, leading to ergonomic issues and variations in final torque, necessitating an improved pulsed fastening method and apparatus.
Innovation Solution
An electric power tool with a motor driven by controlled energy pulses, utilizing an angle sensor to monitor angular displacement, velocity, or acceleration, allowing for dynamic control of energy supply to prevent exceeding threshold values, thereby reducing operator reaction force and improving ergonomics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If continuous energy is supplied to the motor, then the tightening process is fast, but the reaction force on the operator increases
Solution Approach 1:
The motor is supplied with pulsed energy instead of continuous energy, creating periodic action that reduces reaction force while maintaining tightening capability. The pulsed current supply allows the motor to deliver torque in controlled bursts, reducing the continuous reaction force on the operator while still achieving the required tightening speed and torque application.
2Ease of operation
If pulsed energy is supplied to reduce reaction force, then operator comfort improves, but the tightening process becomes slower
Solution Approach 1:
The system dynamically adjusts the parameters of energy pulses (duration, magnitude, frequency) based on real-time feedback from the angle sensor and torque measurements. This dynamic control allows the pulsed energy supply to optimize both operator comfort and tightening speed, adapting the pulse characteristics to maintain productivity while reducing reaction force.
Solution Approach 2:
The system uses feedback from angle sensors and torque measurements to control the energy pulse supply. The angle sensor provides real-time information about shaft rotation, and this feedback is used to adjust the pulsed energy supply to maintain optimal tightening speed while keeping reaction force within acceptable limits for operator comfort.
3Productivity
If high energy pulses are used to maintain tightening speed, then productivity is high, but the angular displacement threshold is exceeded
Solution Approach 1:
The system performs preliminary measurement of angular displacement using the angle sensor before applying energy pulses. This preliminary action allows the control system to adjust the pulse parameters in advance to ensure that the angular displacement threshold is not exceeded, maintaining manufacturing precision while preserving tightening speed through optimized pulse delivery.
Data Source
AI summary
An electric power tool, configured to perform tightening operations where torque is delivered in a series of pulses, includes an electrical motor adapted to drive a rotating shaft of the electric power tool, and an angle sensor for sensing a parameter related to an angular displacement of the electric power tool. The electric motor is adapted to be fed with a train of controlled current pulses. The electric power tool is adapted to control a current supplied in the current pulses based at least in part on an output signal from the angle sensor to not exceed a limit threshold value for the parameter related to an angular displacement of the electric power tool.