Screwdriver Slider Position Detection for Small Screw Engagement
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Solution Overview
Problem
Existing screwdrivers face challenges in detecting engagement with small screws and verifying the final position of screws relative to the work surface, leading to increased screw driving time and potential failure due to cross-threading.
Innovation Solution
A screwdriver design incorporating a movable slider with a position detector, such as an optical encoder, that tracks the relative movement between the slider and carriage to accurately detect screw engagement and verify the final position, allowing for transitions between low, high, and medium RPM steps based on torque and position thresholds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If torque threshold detection is used to detect screw engagement, then the screwdriver can detect engagement for large screws, but it cannot detect engagement for small screws where engagement torque is too small
Solution Approach 1:
The patent introduces a slider as an intermediary mechanical element between the screw bit and the work surface. The slider converts the difficult-to-measure small engagement torque into a measurable displacement distance. When the screw engages the work surface, the slider moves relative to the carriage, and this displacement is detected by an encoder, enabling engagement detection for small screws without relying on torque thresholds.
Solution Approach 2:
The patent replaces the torque-based mechanical detection system with a position-based optical detection system. Instead of measuring engagement torque mechanically, the system uses an optical encoder to measure the displacement distance of the slider, substituting a mechanical measurement approach with an optical sensing approach that has higher precision and better adaptability to small screws.
2Productivity
If high RPM is used during the angle step to expedite the screw driving process, then productivity increases, but the risk of cross-threading increases if engagement is not accurately detected
Solution Approach 1:
The patent implements a feedback control system where the encoder continuously monitors the displacement distance of the slider. When the slider displacement reaches a predetermined threshold indicating proper engagement, the system provides feedback to transition from low RPM search step to high RPM angle step. This feedback mechanism ensures accurate engagement detection before high-speed operation, preventing cross-threading while maintaining productivity.
3Device complexity
If the screwdriver operates without position feedback verification, then device complexity is reduced, but the ability to verify final screw position and detect errors is lost
Solution Approach 1:
The patent makes the encoder serve multiple functions: it detects slider displacement during the search step for engagement detection, tracks position during the angle step for speed control, and verifies final position during the torque step for error detection. This multi-functionality allows the system to achieve comprehensive position verification without adding separate verification devices, maintaining relatively simple system structure while improving reliability.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This design ensures efficient screw driving by accurately detecting screw engagement and preventing cross-threading, reducing screw driving time and improving the reliability of the screwing process.
Implementation Method 1
the encoder comprises an emitter operable to emit light and a detector operable to detect the light, the emitter and detector coupled to the carriage, and the slider comprises a pattern operable to reflect the light
Data Source
AI summary
A screwdriver is disclosed comprising a base, a carriage moveably coupled to the base, an actuator operable to move the carriage relative to the base, and a slider comprising an attached screw bit, wherein the slider is coupled to the base through the carriage and the slider is moveably coupled to the carriage such that the slider and attached screw bit move together relative to the carriage. The screwdriver further comprises a position detector operable to detect a position of the slider relative to the carriage. In one embodiment, the carriage is moved relative to the base to move the screw towards the work surface. After the screw contacts the work surface, the carriage is moved further relative to the base causing the slider to move relative to the carriage, and the movement of the slider relative to the carriage is detected using the position detector.