JP4357219B2 - Ballpoint pen manufacturing method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a ball-point pen tip that is rotatably held by projecting a part of a ball from a tip end portion by performing a caulking process that plastically deforms the tip end portion inward.
[0002]
[Prior art]
Conventionally, as shown in FIG. 4, the ball 10 is inserted into a ball holding chamber 22 having an ink circulation hole 23 in the center of the bottom wall 25 and a radial groove 24 extending radially from the ink circulation hole 23, A ball-point pen tip 21 is well known in which a part of the ball 10 is protruded from the tip end portion 26 and held in a rotatable manner by applying a caulking process that plastically deforms the portion 26 inward.
[0003]
In ballpoint pens equipped with the above-mentioned ballpoint pen tip, oil-based ink or ink with shear thinning viscosity is a type that does not have an ink occlusion body in the ink storage tube and is directly packed with ink. Care must be taken because the ink dripping phenomenon, that is, the ink dripping from the tip of the tip occurs when the tip is left faced downward.
[0004]
In such a conventional ballpoint pen tip 21, the tip surface 27 of the tip tip portion 26 is flat, and the tip tip portion 26 is plastically deformed at a predetermined angle inward by caulking. At this time, the tip end portion 26 has a ball as a fulcrum and the outer wall surface and the inner wall surface extend, and a recess 28 is formed at the center of the tip surface 27 of the chip tip portion 26.
[0005]
In addition, the conventional chip structure having a dent on the tip surface of the tip of the chip causes a phenomenon that when the corner of the tip surface of the tip of the tip comes into contact with the paper surface during writing, the paper surface is scratched and paper fibers are entangled. was there.
[0006]
In order to prevent the outer corner portion of the tip surface of the tip of the tip from coming into contact with the paper surface, “ball ball tip manufacturing apparatus and ball pen tip” in Japanese Patent Application Laid-Open No. 2000-6571 and “ As disclosed in “Method for Manufacturing Ballpoint Pen Tip”, the outer corner of the tip surface of the tip of the tip was plastically deformed after caulking.
[0007]
By the way, the ink discharge mechanism of the oil-based ballpoint pen is that the ball at the tip of the tip rotates, and the ink attached to the ball is transferred to the writing surface through a minute gap between the ball and the inner wall of the tip of the tip, resulting in a handwriting. The ink ejection mechanism differs depending on the characteristics of the ink. For example, the ink is transferred to the writing surface by a capillary tube or penetrating action against the background of the rotation of the ball at the tip of the chip. In the oil-based ballpoint pen, ink return is performed in which excess ink that has been ejected from the tip of the tip and not transferred to the writing surface returns to the tip again.
[0008]
[Patent Document 1]
"Japanese Patent Laid-Open No. 2000-6571"
[Patent Document 2]
"JP-A-8-72460"
[0009]
[Problems to be solved by the invention]
As a result of studying the ink drooping as described above by the present inventor, even if the ink outflow from the chip is prevented by a coil spring or the like as described above, the ink viscosity or the minute gap between the ball and the inner wall of the tip of the chip Depending on the size of the ink, when ink returns, the ink accumulates in the dent on the tip of the tip and does not easily return to the tip, so it accumulates at the tip of the tip and the excess ink hangs down from the tip of the tip. It was found that this occurred.
[0010]
Further, changing the shape, such as chamfering the outer corner of the tip surface of the tip of the tip after caulking, may greatly increase the dimensional accuracy. Furthermore, if the outer corner of the tip surface of the tip of the tip is plastically deformed simultaneously with the caulking process, an uneven thickness portion tends to occur at the tip of the tip, resulting in a decrease in the ball holding force and a small amount of the ball and the inner wall of the tip of the tip. Variations are likely to occur in the gap.
[0011]
The present invention has been made in view of these prior arts, and it is an object of the present invention to provide a ball-point pen tip and a method for manufacturing the ball-point pen tip that are unlikely to cause ink drooping and that are difficult to entrain paper fibers during writing.
[0012]
[Means for Solving the Problems]
In order to solve the above problem, the present invention inserts a ball into a ball holding chamber having an ink circulation hole in the center of the bottom wall and a radial groove extending radially from the ink circulation hole, and the tip end of the chip is directed inward. In a ballpoint pen tip manufacturing method in which a caulking process for plastic deformation is performed and a part of the ball protrudes from the tip end part and is rotatably held, before the tip end part is caulked , The outer and inner corners of the tip surface are chamfered, and a convex portion including a flat surface and a chamfered portion is formed at the tip end portion of the chip .
[0013]
Further, the chamfers on the outer and inner corners of the tip end portion of the tip end portion are chamfers that form roundness.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
The ball-point pen tip 1 according to the embodiment shown in FIGS. 1 to 3 has a bottom wall 5 having an ink circulation hole 3 and a radially extending radial groove 4 communicating with the ink circulation hole 3 in the center of the ball holding chamber 2. The ball 10 is placed on the tip 10 and the tip end portion 6 is plastically deformed inward (in the direction of the arrows in FIGS. 1 and 2) at a predetermined caulking angle by a caulking processing tool (not shown). It is rotatably held so as to protrude from the tip end portion 6.
[0015]
Before the tip end portion 6 is caulked, the outer and inner corners of the tip end surface 7 of the tip end portion 6 are chamfered to form the chamfered portion 8, so that the tip end portion of the tip end has a convex 9 shape after caulking. Thus, even if the inner wall and the outer wall of the tip end portion 6 are extended by caulking, the recessed portion 28 is not formed on the tip end surface as in the conventional ballpoint pen tip 21 shown in FIG. Extend in the direction.
[0016]
Therefore, as described above, it is possible to easily return to the inside of the chip from the minute gap between the ball 10 and the tip end portion 6 at the time of ink return, and ink dripping does not easily occur. In addition, since the edge of the tip surface of the tip of the tip is not formed by forming the recessed portion, the tip of the tip of the tip is difficult to contact the paper surface during writing, and even if temporarily contacted, it is difficult to scratch the paper surface. , Paper fiber can be made difficult to entrain.
[0017]
The chamfering in the present invention is not particularly limited, such as C chamfering or R chamfering, but R chamfering, that is, by forming a round corner at the tip of the tip of the tip, when contacting the paper surface, Hard to scratch the paper. In addition, the tip shape is not particularly limited, and if the corner portion of the tip end portion of the tip is chamfered, the caulking angle, the presence / absence of a ball seat, the number and shape of the radial grooves, etc. are conventionally known. What is necessary is just to select and select the ball-point pen tip shape suitably.
[0018]
【The invention's effect】
Since the ball-point pen tip of the present invention has the structure as described above, it has been possible to provide a ball-point pen tip and a method for manufacturing the ball-point pen tip that are unlikely to cause ink drooping and that do not easily involve paper fibers during writing.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view according to a first embodiment.
2 is an enlarged vertical cross-sectional view of a main part, partly omitted, in FIG. 1;
FIG. 3 is an enlarged vertical sectional view of a principal part, partially omitted, showing a state before crimping in FIG. 1;
FIG. 4 is an enlarged vertical cross-sectional view of a main part, partially omitted, showing a conventional ballpoint pen tip.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Ball-point pen tip 2 Ball holding chamber 3 Ink flow hole 4 Radial groove 5 Bottom wall 6 Tip end 7 Tip end 8 Chamfer 9 Protrusion 10 Ball

Claims (2)

Inserting the ball into a ball holding chamber having an ink circulation hole in the center of the bottom wall and a radial groove extending radially from the ink circulation hole, and applying a caulking process to plastically deform the tip end of the chip inward, a part of the ball In the method of manufacturing a ballpoint pen tip that protrudes from the tip end portion and is rotatably held, the outer and inner corners of the tip end portion of the tip end portion are chamfered before crimping the tip end portion. And the convex part which consists of a flat surface and a chamfering part was formed in the said tip front-end | tip part, The manufacturing method of the ball-point pen tip characterized by the above-mentioned . 2. The method of manufacturing a ballpoint pen tip according to claim 1, wherein the chamfering of the outer and inner corners of the tip end portion of the tip is a chamfer forming a round shape.

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