JP2004025782A - Ball-point pen tip - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a ball-point pen tip which can follow an internal structure of a conventional tip and is easy to caulk. <P>SOLUTION: In the ball-point pen tip, a ball is inserted in a ball holding chamber having an ink flow channel at the center of the bottom wall and radial grooves extending radially from the ink flow channel, the apex of the tip is caulked to inwardly plastic deform the same to form a caulking part at the apex of the tip, thereby rotatably holding the ball, by allowing a part of the ball to protrude from the apex of the tip. A stepped part comprising at least two faces, in which the opening part side of the apex of the tip is contracted in diameter, is formed on the outer wall of the apex of the tip, making the connecting part of the two faces constituting the stepped part as the inflection point of the caulking part. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a ballpoint pen tip formed by forming a caulked portion in which a tip end portion of a ball is plastically deformed inward so that a part of a ball protrudes from the tip end portion and is rotatably held.
[0002]
[Prior art]
Conventionally, the ball is inserted 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 a crimping process for plastically deforming the tip end portion inward is performed. It is well known that a ball-point pen tip is formed such that a portion of a ball protrudes from a tip end portion by forming a caulking portion at a tip end portion so as to be rotatably held.
[0003]
However, as described above, the crimping process plastically deforms the tip end portion of the tip inward, so that the amount of plastic deformation may vary due to a springback phenomenon or the like. Such variation in the amount of plastic deformation is such that if the amount of plastic deformation is small, the clearance between the ball and the opening at the tip end of the chip becomes large, and the amount of ink spilled out becomes large, causing poor handwriting such as tearing or reducing the ball holding force. For this reason, ball drop easily occurs, and when the amount of plastic deformation is large, the clearance between the ball and the opening at the tip end becomes small, the amount of ink flowing out is small, and there is a risk of causing handwriting defects such as rubbing and skipping. .
[0004]
In consideration of these problems, Japanese Patent Application Laid-Open No. 11-268467, entitled "Ball Pen Tip Manufacturing Method" discloses a method of manufacturing the ball holding portion by wiping the tip of the inner wall surface with a tool having a diameter larger than the inside diameter of the tip of the ball holding portion. It is disclosed that a ball is inserted into a holding portion, and then a reduced diameter portion is formed by caulking with a caulking tool.
[0005]
By the way, it is needless to say that various studies have been made on the tip structure, such as ink followability and ink bleeding amount, and it is particularly necessary to set the internal structure complicatedly and precisely.
[0006]
[Problems to be solved by the invention]
However, when the inner wall surface of the ball holding chamber is processed, the influence on the handwriting such as ink followability is large as described above. Therefore, it is necessary to examine not only the swaged portion but also the internal structure. Furthermore, since it is not possible to visually confirm whether or not the starting position of the caulking portion is at the set position, there is a problem that the length of the caulking portion needs to be measured.
[0007]
The present invention has been made in view of these conventional techniques, and an object of the present invention is to provide a ball-point pen tip which can follow the conventional internal structure of a chip and can be easily caulked.
[0008]
[Means for Solving the Problems]
The present invention solves the above problem by inserting a ball into a ball holding chamber having an ink circulation hole in the center of a bottom wall and a radial groove extending radially from the ink circulation hole, and a tip end portion of the ball is placed inside. In a ballpoint pen tip which is formed by caulking for plastic deformation and forming a caulked portion at the tip end portion so that a part of the ball protrudes from the tip end portion and is rotatably held, an outer wall of the tip end portion is provided. In addition, a step portion composed of at least two surfaces is formed, and a joint between the two surfaces forming the step portion is defined as an inflection point of the caulking portion.
[0009]
In addition, the surface located on the chip rear end side of the two surfaces constituting the step portion has substantially the same angle as the caulking angle of the caulking portion.
[0010]
BEST MODE FOR CARRYING OUT THE INVENTION
The ball-point pen tip 1 according to the first embodiment shown in FIGS. 1 and 2 has a bottom having an ink circulation hole 5 and a radially extending radial groove 6 communicating with the ink circulation hole 5 in the center of the ball holding chamber 2. The ball 11 is placed on the wall 4 and the tip end portion 7 is plastically deformed inward at an angle (caulking angle α1) larger than the angle γ1 of the chip outer wall by a caulking tool (not shown) (α1>). By applying γ1), a swaged portion 8 is formed at the tip end portion 7, and the ball 11 is rotatably held so that a part of the ball 11 projects from the tip end portion 7.
[0011]
The chip outer wall 3 is formed in a tapered shape (angle γ1) whose diameter gradually decreases toward the tip end opening 2a, and a step 9 formed of two step forming surfaces 9a and 9b is formed on the chip outer wall 3. . By forming the step 9 (9a, 9b) in which the tip end opening 2a side is reduced in diameter, the surfaces 9a and 9b constituting the step 9 are joined when the tip end 7 is plastically deformed inward. The portion 10 becomes an inflection point, and is easily plastically deformed inward. In addition, since the caulking portion 8 is plastically deformed with the joint portion 10 of the step portion forming surfaces 9a and 9b constituting the step portion 9 as an inflection point, it is set without actually measuring the length L1 of the caulking portion 8. It can be confirmed from the appearance that the length L1 is obtained.
[0012]
The ballpoint pen tip 21 of the second embodiment shown in FIGS. 3 and 4 is a modification of the step portion 29 formed on the outer wall 23 of the tip. Other than that, like the first embodiment, The ball 31 is placed on the bottom wall 24 having an ink circulation hole 25 and a radially extending radial groove 26 communicating with the ink circulation hole 25 at the center of the ball holding chamber 22, and a caulking tool (not shown) By crimping (α2> γ2) the tip end portion 27 at an angle larger than the angle γ2 of the outer wall of the tip (caulking angle α2), a crimped portion 28 is formed at the tip end portion 27, and the ball 31 Are rotatably held so that a part of them protrudes from the tip end portion 27.
[0013]
The chip outer wall 23 is formed in a tapered shape (angle γ2) that gradually decreases in diameter toward the tip end opening 22a, and a step 29 formed of two step forming surfaces 29a and 29b is formed on the chip outer wall 23. I do. By forming the step portion 29 whose diameter is reduced on the side of the tip end opening portion 22a, the joining portion 30 of the step portion forming surfaces 29a and 29b constituting the step portion 29 at the time of caulking for plastically deforming the tip end portion 27 inward. Becomes an inflection point, and is easily plastically deformed inward. Further, since the caulking portion 28 is plastically deformed with the joint portion 30 of the step portion forming surfaces 29a and 29b constituting the step portion 29 as an inflection point, the length is set without actually measuring the length L2 of the caulking portion 28. It can be confirmed from the appearance that the length L2 is obtained.
[0014]
Although the shape of the step in the present invention is not particularly limited, the angle (β2) of the surface 29b located on the chip rear end side of the step forming surfaces 29a and 29b forming the step 29 is defined by the caulking angle (α2 ), The caulking angle α2 of the caulking portion 28 is formed at the set angle, or the angle β2 of the surface 29b connected to the outer wall on the chip rear end side is set. It can be easily confirmed from the appearance by reference.
[0015]
In this embodiment, only one step is formed for convenience. However, when performing two-step caulking, a plurality of steps may be formed, such as forming two steps. The method of forming the step portion is not particularly limited, but can be easily formed by cutting or the like. Further, in the present embodiment, the shape of the ballpoint pen tip is formed without forming the ball seat, but the shape of the inside of the chip is not limited to the shape having the ball seat. Further, the ball may be constantly pressed against the inner wall at the tip end by a coil spring or the like.
[0016]
【The invention's effect】
Since the ball-point pen tip of the present invention has the above-described structure, the ball-point pen tip can follow the conventional chip internal structure and can provide a ball-point pen tip which can be easily caulked.
[Brief description of the drawings]
FIG. 1 is an enlarged vertical cross-sectional view of a main part of a first embodiment, partially omitted.
FIG. 2 is an enlarged vertical cross-sectional view of a main part, partially omitted, showing a state before crimping in FIG. 1;
FIG. 3 is an enlarged vertical cross-sectional view of a main part of a second embodiment, partly omitted.
FIG. 4 is an enlarged longitudinal sectional view of a main part, partially omitted, showing a state before crimping in FIG. 3;
[Explanation of symbols]
1, 21 Ballpoint pen tip 2, 22 Ball holding chamber 2a, 22a Tip tip opening 3, 23 Outer wall 4, 24 Bottom wall 5, 25 Ink circulation hole 6, 26 Ink circulation groove 7, 27 Tip tip 8, 28 Caulking Section 9, 29 Step 9a, 29a Step forming surface 9b, 29b Step forming surface 10, 30 Joint (inflection point)
11, 31 Ball α1, α2 Caulking angle β2 Angle γ1, γ2 of tip rear end surface Angle of chip outer wall

Claims (2)

The ball is inserted 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 a caulking process is performed to plastically deform the tip end portion inward. By forming a caulking portion, a step portion composed of at least two surfaces is formed on an outer wall of the tip portion of the ball-point pen tip in which a part of the ball protrudes from the tip end portion and is rotatably held. And a joint between the two surfaces constituting the step portion is defined as an inflection point of the caulking portion. 2. The ball-point pen tip according to claim 1, wherein a surface located on a tip rear end side of the two surfaces constituting the step portion has substantially the same angle as a swaging angle of the swaging portion. 3.

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