JPH0327818Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) This invention relates to a synthetic resin pen nib in which ribs protruding inward from the outer peripheral wall are integrated at the center to ensure a plurality of ink passages.

(Prior Art) An example of a pen nib of the type described above is shown in FIG. The pen nib A ₃ is made of polyacetal, polyamide, etc., and has six ribs 2 ₃ protruding inward from the annular outer peripheral wall 1 ₃ , and every other rib 2 ₃ comes together at the center. This ensures _three ink passages. The pen nib A ₃ , which is manufactured by extrusion molding using self-fusion of monofilament, is subject to certain questions, such as whether the outer wall of the outer peripheral wall 1 ₃ has a perfect circular shape or not.
The shape and number of the ribs 2 ₃ are determined as appropriate based on the manufacturer's ideas, but usually the ink passage 3
₃ is manufactured so that the largest inscribed circle that can be drawn in the cross section is located on the outer peripheral wall side. This is intended to compensate for the fact that the ribs 2 _{and 3} are integrated at the center, which is advantageous in terms of strength, but has disadvantages in terms of ink discharge because the ink passage is divided into a plurality of parts. Specifically, the purpose is to suppress clogging of the ink passage ₃₃ due to the occurrence of wear burrs on the outer peripheral wall ₁₃ , which is most likely to cause wear burrs due to its large thickness. It should be noted that the six inscribed circles 43 drawn in FIG. ₃ are the largest of the inscribed circles.

(Problem to be solved by the invention) When assembled into a writing instrument, ink ejection is insufficient. The cause of this occurrence will be discussed by the present inventors in the (effects) section below, but it is possible to restore the ink ejection performance of the writing instrument to the originally set ink ejection performance after assembly when the ink ejection becomes insufficient. This is extremely troublesome.

(Means for solving the problem) The largest inscribed circle that can be drawn in the cross section of the ink passage is provided near the center of the pen tip. That is, the present invention is a synthetic resin pen nib in which ribs protruding inward from the outer circumferential wall are integrated at the center to ensure a plurality of ink passages, and the ink passages are The gist of this invention is a synthetic resin nib characterized by having the largest inscribed circle that can be drawn near the center of the nib.

(Function) Pen nibs are usually shaped so that the center reaches the tip most, such as hemispherical or cannonball-shaped. When assembling a writing instrument, ink advances from the rear through the ink passage of the nib due to capillary force.
At this time, if the largest inscribed circle that can be drawn with respect to the ink passage exists on the outer circumferential wall side as shown in FIG. 3, the advance of ink on the outer circumferential wall side will be delayed. That is, a state is created in which ink has not reached the openings on the outer circumferential wall side, but has already advanced to the openings in other parts where openings exist beyond the outer circumferential wall side. In this state, the speed relationship between the ink advancing from the rear and the ink coming around from other parts to the opening on the outer circumferential wall side becomes a problem. If the ink advancing from the rear is delayed, air bubbles will be generated in the ink passage near the opening on the outer peripheral wall side. As is well known, air bubbles generated in the ink passage prevent ink from advancing from the rear due to capillary force, resulting in poor ink discharge.

On the other hand, if the largest inscribed circle that can be drawn exists in the vicinity of the center of the pen nib, the ink will be relatively less likely to enter the opening in the vicinity of the center of the nib. It becomes a thing late. In this case, as described above, it is considered that the ink from other parts that has already reached the opening tries to go around to the vicinity of the center of the pen tip. However, the direction in which the ink tries to go around is inward, and there is a wall surface that extends further ahead, so the area where the ink reaches the opening gradually expands toward the center of the nib. It turns out. Therefore, the generation of bubbles in the ink passage in the vicinity of the center of the pen tip is extremely suppressed, if at all. This is what the present inventors are considering.

(Example) A first example is shown in the attached FIG. 1. The pen nib A ₁ has six ribs 2 ₁ that protrude inward from the outer peripheral wall 1 ₁ , and every other rib 2 ₁ comes together at the center to form three ink passages 3 ₁ . The points secured are the same as the aforementioned pen nib _A3 . Although the shape of the rib 2 ₁ is different from the shape of the rib 2 ₃ , it may have any suitable shape. In the ink passage 3 ₁ of this pen nib A ₁ , an inscribed circle 4 ₁ is drawn with a solid line at the top of three ribs 2 ₁ that are not integrated at the center. It is the largest inscribed circle that can be drawn for each ink passage ₃₁ , and from the viewpoint of ink ejection performance during writing, it is recommended to set the diameter to about 0.055 mm to 0.075 mm. Generally good against inks. Although it is not necessary that all three have the same diameter, it is preferable for the ink passages ₃₁ to have the same shape in order to suppress the directionality of writing, so they are shown as having the same diameter in the figure. Further, in the figure, six inscribed circles are drawn by broken lines on the outer circumferential wall 1 ₁ side, and these are the second largest inscribed circle 4 ₁ near the center. From the viewpoint of the above-mentioned "wear burr", it is better to make it exist if possible, and it is better to have a smaller value than the diameter of the inscribed circle ₄₁ , and to make it about 0.045 mm to 0.065 mm. good. In addition, each ink passage 3 ₁
There are two for each, but they do not necessarily have to have the same diameter.

Next, in FIG. 2 showing the second embodiment, the biggest difference between the pen nib A ₂ and the pen nib A ₁ is that there is a narrow width toward the center of the integrated part of the rib 2 ₂ that is integrated at the center. The ink passage 3 2 is provided with a groove portion 5 ₂ and a groove portion 6 ₂ with _a narrow width facing outward in the outer peripheral wall 1 ₂ . Groove 6 ₂ from Groove 5 ₂
The stronger the capillary force is, the better, but by forming a part where such strong capillary force acts in contact with or near a large inscribed circle, it is possible to reduce the ink pen when assembled into a writing instrument. The time required to reach the open end can be shortened. Note that the inscribed circle indicated by the broken line is the second largest inscribed circle after the inscribed circle 4 ₂ .

(Effect of the invention) Although the pen nib has excellent strength and the ribs are integrated in the center, it is difficult to produce defective products due to insufficient ink ejection when assembled into writing instruments, and therefore, the ink ejection performance is very good. It becomes a stable mass-produced product. By the way, regarding the pen nib A ₂ explained as the second embodiment, the diameter is 0.88 mm, the diameter of the ink passage 3 ₂ is 0.60 mm,
Prepare 100 polyacetal tubes with a diameter of 0.07 mm for the inscribed circle 4 ₂ (all three pieces) and a diameter of 0.06 mm for the circle indicated by the broken line in Figure 2, and fill them with water-based black pigment ink (4.7 cps). A defective product occurred that caused blurred handwriting when assembled into a writing instrument using an ink absorber, immediately kept in a horizontal position, and written after one hour when the ink was thought to have sufficiently reached the open end of the ink passage ₃₂ . The number was only one.

[Brief explanation of the drawing]

1 and 2 are cross-sectional views showing a first embodiment and a second embodiment of the present invention, respectively, and FIG. 3 is a cross-sectional view showing an example of a pen nib according to the present invention. A ₁ , A ₂ , A ₃ ... Pen tip, 1 ₁ , 1 ₂ , 1 ₃ ... Outer peripheral wall, 2 ₁ , 2 ₂ , 2 ₃ ... Rib, 3 ₁ , 3 ₂ , 3 ₃ ...
...Ink passage, 4 ₁ , 4 ₂ , 4 ₃ ...The largest inscribed circle that can be drawn.

Claims (1)

[Scope of utility model registration request] A synthetic resin nib in which ribs protruding inward from the outer circumferential wall are integrated at the center to ensure multiple ink passages, and the ink passages are formed as an inscribed circle that can be drawn in a cross section. A synthetic resin nib characterized by having the largest portion near the center of the nib.