Pencil Sharpener Contour Tool for Uniform Tip Edge
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Solution Overview
Problem
Conventional pencil sharpeners often produce uneven, jagged transitions between the lead and casing material at the pencil tip, leading to aesthetic issues and potential skin irritation or injury, especially when used on sensitive areas like eyelids or lips.
Innovation Solution
A pencil sharpener with a circular cone-shaped guide channel and a contour tool that introduces a shoulder into the tip, smoothing the transition between the lead and casing materials, creating a rotationally symmetrical shape and minimizing the risk of skin irritation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a conventional pencil sharpener with a conical guide channel is used, then the pencil can be sharpened efficiently, but the transition between lead and casing material becomes uneven and jagged
Solution Approach 1:
The guide channel is divided into two distinct sections: a conical section for initial sharpening and a cylindrical section for final smoothing. This segmentation allows each section to perform its specific function optimally - the conical section removes material efficiently while the cylindrical section creates a uniform sheath edge, thereby resolving the contradiction between sharpening efficiency and edge uniformity.
Solution Approach 2:
The conical guide channel section performs the preliminary action of shaping the pencil tip and removing excess material before the pencil enters the cylindrical section. This preliminary conical shaping prepares the pencil for the final smoothing action in the cylindrical section, ensuring that the sheath edge is uniformly formed after the sharpening process.
2Device complexity
If the pencil is guided with play in the pencil guide channel, then the sharpener structure remains simple, but the pencil tip becomes misaligned and the sheath edge becomes crooked
Solution Approach 1:
The guide channel exhibits local quality variation along its length - the conical section has a larger diameter that accommodates the pencil with appropriate play for material removal, while the cylindrical section has a precisely fitted diameter that constrains the pencil for accurate sheath edge formation. This local variation in dimensional quality allows the simple structure to achieve precise alignment where needed.
3Shape
If the jacket material thickness approaches zero at the transition area, then the pencil design is compact, but the material splinters and creates an uneven edge
Solution Approach 1:
The conical guide channel section acts as a cushioning zone that gradually reduces the jacket material thickness before it reaches the critical zero-thickness region. By progressively shaping the transition area in the conical section, the pencil is prepared for the final smoothing in the cylindrical section, preventing sudden material failure and splintering at the sheath edge.
Data Source
Figure 1
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AI summary
A pencil sharpener (1) for sharpening a pencil (2), in particular a cosmetic pencil, is described, which is especially suitable for producing a particularly uniform outer edge in the area of the pencil tip of the sharpened pencil when used as intended. The sharpener (1) comprises a sharpener body (20) in which a pencil guide channel (26) is incorporated. The pencil guide channel (26) includes at least one circular cone-shaped channel section (28). On the outside of the sharpener body (20), the pencil guide channel (26) opens into a pencil insertion opening (25). Furthermore, the sharpener (1) comprises a peeling blade (21) positioned approximately tangentially to the outer surface of the circular cone-shaped channel section (28). The peeling blade (21) serves to peel off a pencil tip (6), which comprises a front lead section (7) and a rear outer section (8).Furthermore, the pencil sharpener (1) comprises a contour tool (23) for cutting out a shoulder (9) into the pencil tip (6), which is recessed relative to a circular conical surface (10) of the pencil tip (6). The contour tool (23) is arranged with respect to the pencil guide channel (26) such that it introduces the shoulder (9) into the transition between the lead section (7) and the casing section (8) of the pencil tip (6).