Fastening Tool Bit Feed Control to Prevent Screw Tightening Float
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Solution Overview
Problem
Existing fastening tools lack the ability to control the moving speed of a driver bit in accordance with the rotation speed of a screw, leading to incomplete tightening due to reaction forces that cause the tool body to float away from the fastening target.
Innovation Solution
A fastening tool equipped with a bit holding portion, a first motor for rotating the bit, a second motor for moving the bit holding portion axially, and a control unit to manage the position and speed of the bit holding portion, allowing precise control of the driver bit's movement speed relative to the screw's rotation speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the bit forward speed is increased to improve tightening efficiency, then productivity is improved, but the reaction force increases causing the tool body to float away from the fastening target
Solution Approach 1:
The patent implements dynamic speed control where the bit forward speed is automatically adjusted based on the screw rotation speed. The control unit receives rotation speed information from the rotation sensor and dynamically adjusts the bit moving speed to maintain an appropriate speed difference, preventing excessive reaction forces while maximizing tightening efficiency.
Solution Approach 2:
The patent employs a feedback mechanism where the rotation sensor continuously monitors the screw rotation speed and feeds this information back to the control unit. The control unit then adjusts the bit moving speed accordingly, creating a closed-loop control system that prevents tool floatation while maintaining high productivity.
2Reliability
If the bit forward speed is reduced to prevent tool floatation, then reliability of screw tightening is improved, but productivity decreases
Solution Approach 1:
The system dynamically adjusts the bit forward speed based on real-time rotation speed measurements. By maintaining an appropriate speed difference between bit movement and screw rotation, the system ensures reliable screw tightening without excessive reaction forces, while adapting the speed to maximize productivity under different operating conditions.
Solution Approach 2:
The control unit changes the operational parameters (bit forward speed) based on the measured rotation speed. By adjusting the speed parameter dynamically rather than using a fixed speed, the system achieves both reliable tightening and high productivity across varying operational conditions.
3Device complexity
If a spring mechanism is used to drive the screw, then device complexity is reduced, but control precision of bit moving speed is insufficient
Solution Approach 1:
The patent replaces the purely mechanical spring-driven system with an electromechanical system. Motors are used to drive both the screw rotation and bit movement, allowing for precise electronic control of speeds. The control unit can independently regulate the bit forward speed based on rotation speed feedback, achieving precise speed control that a mechanical spring system cannot provide.
4Device complexity
If pneumatic pressure is used to move the bit, then device complexity is reduced, but control precision of bit moving speed is insufficient
Solution Approach 1:
The patent replaces the pneumatic system with an electromechanical system using motors. This substitution enables precise electronic control of the bit forward speed through the control unit, which can adjust the motor speed based on feedback from the rotation sensor. The electronic control system provides superior speed precision compared to pneumatic pressure control.
Data Source
AI summary
A fastening tool includes: a bit holding portion which detachably holds a driver bit and is configured to rotate in a circumferential direction of the driver bit and move in an axial direction of the driver bit; a first motor configured to rotate the bit holding portion; a second motor configured to move the bit holding portion along the axial direction; and a control unit configured to control a position of the bit holding portion along the axial direction by the number of rotations of the second motor. The control unit is configured to control a moving speed of a screw moved by rotation of the first motor or a rotation speed of the first motor.