Semi-left-hand-thread-removal screw for slippage
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Solution Overview
Problem
Existing screws are difficult to unscrew due to slippage issues caused by damaged screw cap grooves, rust, or improper operation, leading to increased resistance and potential damage during removal.
Innovation Solution
A semi-left-hand-thread-removal screw design featuring a sink hole with an inscribed polygon structure at the screw end head and a reverse thread on the screw shank, allowing for easy insertion with a common screwdriver and removal with a left-hand-thread screwdriver, utilizing a pulling-out hole for additional force and rotation assistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a common screw cap groove (I-shaped, cross-shaped, hexagon) is used, then the screw can be easily inserted with a common screwdriver, but the screw cap groove may slip during unscrewing due to damage, rust, or improper operation
Solution Approach 1:
The screw head is divided into two functional zones: a lower portion with a common screw cap groove for easy insertion, and an upper portion with a reverse thread for reliable removal. This segmentation allows each zone to optimize its specific function without compromising the other.
Solution Approach 2:
The upper portion of the screw head features a reverse thread (opposite handedness to the bolt thread) that engages with a special screwdriver. When the special screwdriver is inserted and rotated, the reverse thread converts the rotational motion into a pulling force that reliably removes the screw even when the common groove slips.
2Strength
If the screw is retained for a long time and becomes rusted, then the screw provides strong fastening, but the resistance to unscrew increases and slippage becomes more likely
Solution Approach 1:
The reverse thread on the upper portion of the screw head creates a mechanical advantage that converts rotational motion into a strong pulling force. This allows the screw to be reliably removed even when rusted or tightly fastened, as the reverse thread engagement prevents slippage and provides sufficient force to overcome corrosion.
Solution Approach 2:
The special screwdriver with the rotatable part is designed to engage the reverse thread immediately upon insertion. The rotatable part can be manually rotated to initiate the unscrewing action, providing preliminary force to overcome static friction and rust before the main removal force is applied.
3Reliability
If a special screwdriver is used to engage the reverse thread, then the screw can be reliably removed even when slipped, but the device complexity increases
Solution Approach 1:
The special screwdriver serves multiple functions: the lower portion engages the common screw cap groove for insertion, while the upper rotatable part engages the reverse thread for reliable removal. This multi-functionality consolidates what would otherwise require two separate tools into one device.
Solution Approach 2:
The rotatable part of the special screwdriver is nested within the handle structure. When the screwdriver is inserted into the screw head, the rotatable part can rotate independently within the handle to engage the reverse thread, creating a compact integrated design.
Data Source
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AI summary
A semi-left-hand-thread-removal screw, comprising a screw end head and a bolt, wherein a sink hole is provided on the screw end head, a lower portion of the sink hole is an inscribed polygon structure or an I-shaped structure, a thread which is opposite to the bolt is provided on an upper portion of the sink hole, the inscribed polygon structure is an inscribed hexagon. Preferably, the invention has the following characteristics and use ways: the semi-left-hand-tread-removal screw can be screwed in with a common inscribed hexagon screwdriver and an inscribed hexagon structure thereof which are embedded into each other; the screw can be unscrewed with a left-hand-thread screwdriver which is matched with a left-hand-thread structure thereof and screwed in the left-hand-thread structure thereof, after the left-hand-thread screwdriver is screwed in tightly, the screwdriver is continuously co-rotated and then the screw may be unscrewed. Therefore, when the screw of the invention is unscrewed, the screw may be rapidly and effectively unscrewed no matter whether a screw cap groove is slipped. The invention has a reasonable structure, and may effectively prevent the screw from slipping when the screw is unscrewed.