Ballpoint Pen Tip Ink Groove Design for High Viscosity Flow
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Solution Overview
Problem
Conventional ballpoint pen tips with springs for biasing the writing ball forward face challenges in maintaining sufficient ink flow rates with high viscosity inks, as the spring's presence reduces the effective ink guide hole sectional area, leading to poor outflow characteristics and increased risk of ink drops.
Innovation Solution
A ballpoint pen tip design featuring a tapered holder with inwardly narrowed portions, radial ink grooves, and an elastic member that biases the writing ball forward, where the ink grooves are wider than the biasing portion to prevent the elastic member from getting stuck, and inward protrusions help maintain ink flow without impairing outflow characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a spring is inserted in the ballpoint pen tip to bias the writing ball forward, then the risk of ink drop is reduced, but the effective sectional area of the ink guide hole is diminished, leading to poor ink outflow characteristics
Solution Approach 1:
The ink guide hole is divided into two functional sections: a front section with a smaller diameter that accommodates the spring's biasing portion, and a rear section with a larger diameter that ensures sufficient ink flow. This segmentation allows the spring to perform its biasing function while the larger rear section maintains adequate ink outflow characteristics even with high viscosity inks.
2Productivity
If the width of ink grooves is expanded to ensure ink flow rate, then ink outflow characteristics are improved, but the rod part of the spring may get stuck in the ink grooves
Solution Approach 1:
The ink grooves are designed with different width characteristics at different locations: they are wider in the front section where the spring's biasing portion passes through to prevent the spring from getting stuck, and can be narrower in other sections to maintain proper ink flow characteristics. This local variation in groove geometry resolves the contradiction between preventing spring jamming and maintaining ink flow rate.
3Device complexity
If the ink guide hole diameter is reduced to accommodate the spring, then the spring can be installed, but the ink flow rate becomes insufficient, especially with high viscosity inks
Solution Approach 1:
The ink guide hole is segmented into a front portion with smaller diameter for spring accommodation and a rear portion with larger diameter for maintaining ink flow. This allows the spring to be installed while ensuring sufficient ink outflow rate, particularly for high viscosity inks that require larger passage dimensions.
4Productivity
If the ink grooves are made wider to improve ink flow, then ink outflow characteristics are enhanced, but the manufacturing precision requirements increase due to the need to prevent spring jamming
Solution Approach 1:
The ink grooves are designed with location-specific width characteristics: wider dimensions at the front section where the spring passes through to prevent jamming, and controlled narrower dimensions in other sections. This local quality approach allows the grooves to be wide enough to prevent spring jamming while maintaining proper ink flow characteristics, without requiring uniformly high manufacturing precision throughout the entire groove structure.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The design ensures consistent ink flow and prevents ink drops while maintaining ink outflow rates, even with high viscosity inks, by preventing the elastic member from being stuck in the ink grooves and reducing fluid resistance.
Implementation Method 1
an elastic member adapted to bias the writing ball forward is inserted in the back hole
Implementation Method 2
The width in the circumferential direction of each of the ink grooves is larger than the outer diameter of the rod shaped biasing portion
Data Source
Figure 1(A)~1(B)
Figure 2
Figure 3~4
AI summary
A ballpoint pen tip which, even if ink having less outflow characteristics, such as ink containing large particles or ink having high viscosity, is used, does not cause a written trace to be faint, does not cause the ink to drop, and does not impair the outflow characteristics. Ink grooves (31) are formed around an ink guide hole (30) at equally distributed places, said ink guide hole (30) connecting a ball house (26) and a back hole (28) of a holder (21) for holding the writing ball (35), and the ink grooves (31) radially penetrate through from the ball house (26) side to the front end portion (29) of the back hole (28). Inward protrusions (32) which protrude inward are formed at positions which are respectively in contact with the rear ends of the ink grooves (31). If the inner diameter of the ink guide hole (30) is A, the inner diameter of the front end portion (29) of the back hole (28) is B, the diameter of the circle circumscribing the ink grooves (31) is C, and the diameter of the circle inscribing the inward protrusions (32) is D, the relationships of A < B < C, and D < B are satisfied.