Angled Screwstrip Slots Prevent Driver Misalignment
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Solution Overview
Problem
Conventional screwstrips often experience misalignment issues due to the precise timing required for the feed pawl to engage with rectangular slots, leading to potential misfeeds as the pawl may hit or miss the vertical rear edge of the slots in autofeed screwdrivers.
Innovation Solution
The introduction of angled slots with a leading edge perpendicular to the screwstrip's travel line and a trailing edge at an oblique angle, which allows the feed pawl to engage more forgivingly and prevent misalignment, ensuring consistent advancement of the screwstrip.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If rectangular slots with vertical rear edges are used in conventional screwstrips, then the structure is simple and easy to manufacture, but the feed pawl may hit or miss the vertical rear edge leading to misalignment and misfeeds
Solution Approach 1:
The patent applies asymmetry by changing the slot geometry from a symmetric rectangular shape with vertical rear edges to an asymmetric shape with an angled rear edge. This asymmetric design allows the feed pawl to engage more reliably with the slot, preventing misalignment and misfeeds while maintaining simplicity in manufacturing.
2Reliability
If precise timing is required for the feed pawl to engage with rectangular slots, then the advancement can be controlled, but the system becomes sensitive to timing errors causing misfeeds
Solution Approach 1:
The patent applies parameter changes by modifying the geometric parameters of the slot, specifically the rear edge angle. This parameter change makes the engagement between the feed pawl and slot less sensitive to timing variations, allowing the system to tolerate timing errors without causing misfeeds, thereby improving reliability and adaptability.
3Ease of manufacture
If the feed pawl engages with rectangular slots having vertical rear edges, then the structure is simple, but misalignment occurs when the driver is still retracting
Solution Approach 1:
The patent resolves this contradiction by introducing asymmetry in the slot design, specifically angling the rear edge. This asymmetric geometry prevents misalignment during the retraction phase while remaining simple to manufacture using standard machining processes, thus maintaining ease of manufacture while improving feed accuracy.
Data Source
AI summary
A screwstrip is disclosed including angled slots which allow a driver of an automated screwdriver to advance the screwstrip. The slots include a leading edge, which may be perpendicular to the line of travel of the screwstrip, and a trailing edge provided at an oblique angle with respect to the line of travel of the screwstrip. A slot including an angled sidewall is more forgiving and prevents misalignment of the driver with the slots.