Writing Tool Refill with Localized Wall Thickness
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Solution Overview
Problem
Conventional writing tools with refills have a limited ink capacity due to small dimensions, and when refills are replaced, the writing tip or relay member often detaches from the ink reservoir tube, causing ink to scatter.
Innovation Solution
A writing tool design with a refill having an ink reservoir tube with a thinner wall thickness and a larger inner diameter, where the connection strength between the ink reservoir tube and the writing tip or relay member is enhanced, ensuring the refill detaches reliably from the barrel without ink scattering.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the wall thickness of the ink reservoir tube is reduced to increase ink capacity, then the ink capacity is improved, but the connection strength between the ink reservoir tube and the writing tip or relay member deteriorates
Solution Approach 1:
The ink reservoir tube is designed with non-uniform wall thickness: the main body has a thin wall thickness of 0.56 mm or less to maximize ink capacity, while the connecting portion at the tip end has a locally thickened wall thickness of 0.08 mm or more to ensure strong connection between the writing tip/relay member and the ink reservoir tube. This local quality differentiation resolves the contradiction between ink capacity and connection strength.
2Volume of moving object
If the outer diameter of the ink reservoir tube is kept small to maintain compact size, then the compactness is improved, but the ink capacity deteriorates
Solution Approach 1:
The invention changes the wall thickness parameter of the ink reservoir tube from conventional thick walls to a thin wall thickness of 0.56 mm or less. This parameter change allows the inner diameter to be maximized within the constrained outer diameter, thereby increasing ink capacity while maintaining the compact size required for portable writing tools.
3Ease of operation
If the refill is designed for easy detachment from the barrel, then the ease of operation is improved, but the reliability of preventing tip detachment during removal deteriorates
Solution Approach 1:
The ink reservoir tube is designed with differentiated wall thickness: thin walls (0.56 mm or less) in the main body for easy detachment from the barrel, and a locally thickened connecting portion (0.08 mm or more) at the tip end to ensure the writing tip or relay member remains securely attached during refill removal. This local quality differentiation resolves the contradiction between ease of operation and reliability.
Data Source
AI summary
A writing tool includes a refill having an ink reservoir tube formed to be a straight cylinder whose wall thickness is less than 0.56 mm; and a writing tip or a relay member holding the writing tip attached to a first end of the ink reservoir tube, wherein the refill is detachably attached to a barrel, wherein in the refill, amounting strength between the writing tip or the relay member holding the writing tip and the ink reservoir tube is set higher than a mounting strength between the barrel and a connecting portion of the ink reservoir tube. There is provided a writing tool that can prevent the occurrence of a problem such as leakage of ink at a time of replacement of refills and perform replacement of refills smoothly.