Refill Case Asymmetric Locking Saw-Toothed Portions
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Solution Overview
Problem
In electric staplers, the existing feeding mechanism with obliquely arranged feeding pawls can cause poor feeding due to the unlocking of return-preventing claws, leading to staple-sheet floating and potential breakage, especially when the number of staple-sheets is large and under vibration, and the small pitch between teeth in the locking saw-toothed portions is difficult to form in synthetic resin.
Innovation Solution
The refill case design features bilaterally symmetric return-preventing claws that engage with locking saw-toothed portions with shifted phases, allowing one claw to lock into the other's peak when the first unlocks, reducing the moving amount of the staple pressing member to half the pitch, thus preventing floating and poor feeding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the pitch between teeth of the locking saw-toothed portion is made small to prevent staple-sheet floating, then the reliability of feeding is improved, but the ease of manufacture deteriorates because it is difficult to form small pitches in synthetic resin
Solution Approach 1:
The patent applies asymmetry by making the phases of the right and left locking saw-toothed portions different from each other. Specifically, when one return-preventing claw unlocks from a peak, the other claw is positioned at a different phase, causing it to engage with a peak at a different timing. This asymmetric phase relationship prevents simultaneous unlocking of both claws, thereby reducing the maximum floating distance to less than one pitch without requiring smaller pitch dimensions that would be difficult to manufacture in synthetic resin.
2Stability of the object's composition
If the number of staple-sheets is large increasing the whole weight, then the stability of the staple pressing member is improved, but the reliability deteriorates because the feeding pawl may disengage when the staple-sheet floats
Solution Approach 1:
The asymmetric phase configuration of the locking saw-toothed portions ensures that when one return-preventing claw unlocks, the other claw remains engaged with a peak at a different phase. This prevents the staple pressing member from floating by more than one pitch distance, ensuring the feeding pawl remains engaged with the staple-sheet groove even when heavy stacks of staple-sheets are being fed.
Solution Approach 2:
The patent implements a cushioning effect by having one return-preventing claw remain engaged with a peak while the other unlocks. This creates a buffering mechanism where the engaged claw prevents excessive floating before the other claw can re-engage, cushioning against the harmful effect of staple-sheet floating and preventing feeding pawl disengagement.
3Reliability
If the return-preventing claw is made to lock firmly to prevent unlocking under vibration, then the reliability is improved, but the device complexity increases due to the need for phase-shifted saw-toothed portions
Solution Approach 1:
The patent resolves the contradiction by implementing asymmetry in the phase configuration of the locking saw-toothed portions rather than adding complex locking mechanisms. The different phases are integrated into the basic saw-toothed structure, allowing the return-preventing claws to lock firmly during normal operation while preventing simultaneous unlocking under vibration. This approach improves reliability without significantly increasing device complexity, as it modifies the geometry of existing components rather than adding new mechanisms.
Data Source
AI summary
A refill case is provided with: an accommodating part (2) for accommodating staple-sheets (1); a staple pressing member (4) for pressing a top of the staple-sheets (1); locking saw-toothed portions (6a, 6b) having saw-toothed shapes; and return-preventing claws (5) formed ends of the staple pressing member (4) and engaged with the locking saw-toothed portions. A phase of the saw-toothed shape of the right locking saw-toothed portion is shifted from a phase of the saw-toothed shape of the left locking saw-toothed portion.