Fastening Tool Motor Feedback for Consistent Screw Depth
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Solution Overview
Problem
Existing fastening tools experience variable fastening depth due to fluctuations in the engagement between the driver bit and the screw, leading to inconsistent screw insertion and potential embedding of the screw head.
Innovation Solution
The fastening tool includes a controller that detects the disengagement between the driver bit and the screw, stopping the motor rotation when the screw head is flush with the surface, ensuring consistent fastening depth by controlling the rotation and movement of the driver bit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the driver bit is pressed against the screw with force to ensure engagement, then the fastening reliability is improved, but the fastening depth becomes inconsistent due to variation in engagement amount
Solution Approach 1:
The controller monitors the rotation state of the driver bit during fastening operation and automatically stops rotation when disengagement is detected, using feedback from the operational state to maintain consistent fastening depth regardless of engagement variations
Solution Approach 2:
The system uses the natural disengagement phenomenon that occurs when the screw head becomes flat as a self-indicating signal to stop the fastening process, eliminating the need for external depth measurement devices
2Manufacturing precision
If the driver bit rotation is stopped early to prevent over-fastening, then the fastening depth consistency is improved, but the fastening reliability decreases when engagement amount varies
Solution Approach 1:
The controller continuously monitors the rotation state of the driver bit and adjusts the stopping timing based on real-time detection of disengagement, providing adaptive feedback control that maintains both depth consistency and reliability
3Manufacturing precision
If a detection device is added to monitor fastening state, then the fastening depth consistency is improved, but the device complexity increases
Solution Approach 1:
The system utilizes the driver bit's own rotation motor as the detection device, leveraging the existing operational component to provide self-diagnosis of the fastening state without requiring separate sensors or detection mechanisms
Solution Approach 2:
The rotation motor serves dual functions: driving the driver bit rotation and acting as the detection device for monitoring engagement state, eliminating the need for separate detection components
Data Source
Figure 1A
Figure 1B~1C
Figure 2A~2B
AI summary
A fastening tool includes a bit holding portion configured to hold a driver bit engageable with a screw and that is rotatable in a circumferential direction and movable in an axial direction of the driver bit, a motor configured to rotate the bit holding portion, a controller configured to control the motor, and a detector configured to detect a state of the motor. In a state where the screw engaged with the driver bit is fastened to a fastening target, the controller determines whether the driver bit and the screw are disengaged based on the state of the motor detected by the detector and stops the rotation of the motor in a case where the controller determines that the driver bit and the screw are disengaged.