JP2004330607A - Ball-point pen tip - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To realize a uniform gap 10 between the outer peripheral surface of a ball and the inner peripheral surface of a ball housing chamber by a method wherein the cross-sectional shape of the inner peripheral surface of the ball housing chamber is made circular. <P>SOLUTION: A plurality of recesses 3 are formed by punching on the outer peripheral surface near the tip of a metal pipe 2. A plurality of inward projected parts 4 for a ball bearing seat are formed on the inner peripheral surface of the pipe 2 having the recesses 3 locating thereon. An annular tip edge part 5 is formed by plastically deforming the tip of the pipe 2 inwards. The ball housing chamber 8, which rotatably holds the ball 9 therein, is provided within the pipe 2 lying between the inward projected parts 4 and the tip edge part 5. By punching the outer peripheral surface of the pipe 2 radially outwards the ball housing chamber 8, a plurality of minute recesses 6, the radial depth of each of which is shallower than that of the recess 3, are formed. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a ballpoint pen tip. In the present invention, “front” refers to the pen tip ball side, and “rear” refers to the opposite side.
[0002]
[Prior art]
Conventionally, in a ball-point pen tip of this type, for example, in Patent Document 1, an appropriate number of inwardly projecting portions forming a ball receiving surface are formed at predetermined positions on an outer peripheral surface of a small-diameter pipe made of metal. There is disclosed a device in which a ball is placed on a vehicle and the ball is rotatably held.
[0003]
[Patent Document 1]
Japanese Utility Model Publication No. 62-25586
[Problems to be solved by the invention]
As shown in FIGS. 9 to 11, the conventional ballpoint pen tip is formed by forming a concave portion 3a by punching on the outer peripheral surface of a pipe 2a in order to obtain an inwardly protruding portion 4a for a ball receiving seat. Due to the effect of the punching, the cross-sectional shape of the ball storage chamber 8a becomes distorted from a circular shape, and the gap 10a between the outer peripheral surface of the ball 9a and the inner peripheral surface of the ball storage chamber 8a has a fixed width. And tend to be non-uniform. In such a case, the conventional ball-point pen tip deteriorates the sealing property between the tip edge portion 5a and the ball 9a, leaks ink to the outside when the pen tip is downward, or produces directionality in ink discharge, and depending on the writing direction. There is a possibility that the difference in the ink discharge amount becomes large, the rotation of the ball becomes non-uniform, and the writing feeling is deteriorated.
[0005]
The present invention has been made to solve the above-mentioned conventional problems, and has a circular cross-sectional shape of an inner peripheral surface of a ball accommodating chamber to reduce a gap between an outer peripheral surface of a ball and an inner peripheral surface of the ball accommodating chamber. It is intended to provide a ballpoint pen tip that can be made uniform.
[0006]
[Means for Solving the Problems]
[1] In the present invention, a plurality of recesses 3 are formed by performing punching on an outer peripheral surface near a tip of a metal pipe 2, and a ball receiving seat is formed on an inner peripheral surface of the pipe 2 where the concave portion 3 is located. A plurality of inwardly projecting portions 4, and further, the tip of the pipe 2 is plastically deformed inward to form an annular leading edge 5, and the inward projecting portion 4, the leading edge 5, The ball-point pen tip 1 provided with a ball storage chamber 8 for rotatably holding a ball 9 in the pipe 2 between the pipes 2, wherein the outer peripheral surface of the pipe 2 radially outside the ball storage chamber 8 is punched. , A plurality of minute recesses 6 having a shallower radial depth than the recesses 3 are required (claim 1).
[0007]
According to the first aspect, the cross-sectional shape of the inner peripheral surface of the ball accommodating chamber 8 is corrected to a circular shape by punching for forming the minute concave portion 6. Thereby, the gap 10 between the outer peripheral surface of the ball 9 and the inner peripheral surface of the ball storage chamber 8 becomes uniform. As a result, it is possible to obtain the ballpoint pen tip 1 in which the sealing performance between the tip edge portion 5 and the ball 9 is improved, a handwriting having no direction is obtained, and the writing feeling is improved by the uniform rotation of the ball 9. .
[0008]
[2] In the ball-point pen tip 1 of the first aspect, it is preferable that the inner peripheral surface of the pipe 2 where the minute concave portion 6 is located is not in contact with the ball 9 (claim 2).
[0009]
Thereby, smooth rotation of the ball 9 is maintained in the ball storage chamber 8. If the ball 9 comes into contact with the inner peripheral surface (the bulging portion 7) of the pipe 2 where the minute concave portion 6 is located, the smooth rotation of the ball 9 may be impaired.
[0010]
[3] The ball-point pen tip 1 according to claim 2, wherein each of the inwardly projecting portions 4 is provided with an inclined front surface portion 41, and the minute concave portion is provided between the adjacent inwardly projecting portion 4 front surface portions 41. It is preferable that the inner peripheral surface of the pipe 2 where the position 6 is located be located (claim 3).
[0011]
Thereby, even if the inner diameter of the inner peripheral surface of the pipe 2 where the minute concave portion 6 is located (the diameter of a virtual inscribed circle contacting the vertex of the bulging portion 7) is smaller than the outer diameter of the ball 9, It is possible to easily obtain a configuration in which the inner peripheral surface of the pipe 2 where the minute concave portion 6 is located does not contact the ball 9.
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION
An embodiment of the present invention will be described with reference to the drawings.
[0013]
(First embodiment)
1 to 4 show a first embodiment of a ballpoint pen tip 1 according to the present invention.
[0014]
The ball-point pen tip 1 according to the present embodiment includes a concave portion 3 formed on the outer peripheral surface near the tip of a metal pipe 2 by punching, and an inward protrusion for a ball receiving seat formed on the inner peripheral surface of the pipe 2 of the concave portion 3. Part 4, a tip edge 5 formed by inwardly plastically deforming the tip of the pipe 2 in an annular shape, and a ball housing formed in the pipe 2 between the inward projection 4 and the tip edge 5. It comprises a chamber 8, a ball 9 rotatably held in the ball storage chamber 8, and a minute recess 6 formed on the outer peripheral surface of the pipe 2 where the ball storage chamber 8 is located.
[0015]
Specifically, the metal pipe 2 is made of stainless steel (for example, austenitic stainless steel such as SUS304, SUS305, and SUS321). At least the tip of the pipe 2 is cylindrical. In addition, a conical tapered portion 21 whose outer diameter decreases toward the front is formed on the outer peripheral surface of the distal end portion of the pipe 2.
[0016]
On the outer peripheral surface near the tip of the pipe 2, punching is performed at equal intervals at three places on the same circumference, thereby forming three concave portions 3. At the same time, three inwardly projecting portions 4 projecting radially inward are formed on the inner peripheral surface of the pipe 2 where the concave portions 3 are located. The front portion 41 of the inwardly protruding portion 4 serves as a ball receiving seat that supports the rear surface of the ball 9.
[0017]
The punching is performed by simultaneously punching three punches radially inward on the outer peripheral surface near the tip of the pipe 2. Since the tip of the punch has a tapered shape (specifically, a cone-shaped or pyramid-shaped pointed shape), the front surface portion 41 of the inwardly protruding portion 4 has a ball receiving seat inclined with respect to the axis. It becomes.
[0018]
On the outer peripheral surface of the pipe 2 radially outward of the ball accommodating chamber 8, three small concave portions 6 having a shallower radial depth than the concave portions 3 are formed at equal intervals by punching. Is done. The minute concave portion 6 is formed on an axial extension line passing through the center of the distance between the adjacent concave portions 3. Further, the bottom of the minute recess 6 is located slightly forward of the bottom of the recess 3. As shown in FIG. 1, the line AA passes through the bottom of each minute recess 6, and the line BB passes through the bottom of each recess 3. That is, the line AA is located slightly forward of the line BB, and passes through the front surface portion 41 inclined with respect to the axis of the inwardly protruding portion 4.
[0019]
Due to the minute concave portion 6, a bulging portion 7 slightly protruding radially inward is formed on the inner peripheral surface of the pipe 2 of the ball storage chamber 8. The bulging portion 7 is formed at the center of the distance between the inclined front surfaces 41 (ball receiving seats) of the adjacent inwardly projecting portions 4. Therefore, the bulging portion 7 protrudes largely inward in the radial direction, and even if the diameter of the virtual inscribed circle contacting the vertex of the bulging portion 7 becomes smaller than the outer diameter of the ball 9, the bulging portion 7 does not contact the ball 9. Can be easily set.
[0020]
After the concave portion 3 for the ball receiving seat is formed, the inner peripheral surface of the pipe 2 (the inner peripheral surface of the ball accommodating chamber 8) near the concave portion 3 has a non-circular cross-sectional shape slightly distorted from circular. Has become. However, the inner peripheral surface of the ball accommodating chamber 8 is corrected to a circular cross section by the minute concave portion 6. Therefore, as shown in FIG. 4, the gap 10 between the outer peripheral surface of the ball 9 and the inner peripheral surface of the ball storage chamber 8 becomes uniform.
[0021]
An annular distal edge 5 is formed at the distal end of the pipe 2 by plastic deformation radially inward. The inner peripheral surface of the tip edge 5 prevents the ball 9 from coming off, and the inner peripheral surface of the tip edge 5 contacts the ball 9 in a ring shape to prevent the leakage of ink. The sealing performance between the ball and the ball 9 is improved. In FIG. 1, the two-dot chain line indicates the tip edge 5.
[0022]
(Second embodiment)
5 to 8 show a second embodiment of the ballpoint pen tip 1 according to the present invention.
[0023]
The ball-point pen tip 1 according to the present embodiment includes a concave portion 3 formed on the outer peripheral surface near the tip of a metal pipe 2 by punching, and an inward protrusion for a ball receiving seat formed on the inner peripheral surface of the pipe 2 of the concave portion 3. Part 4, a tip edge 5 formed by inwardly plastically deforming the tip of the pipe 2 in an annular shape, and a ball housing formed in the pipe 2 between the inward projection 4 and the tip edge 5. It comprises a chamber 8, a ball 9 rotatably held in the ball storage chamber 8, and a minute recess 6 formed on the outer peripheral surface of the pipe 2 where the ball storage chamber 8 is located.
[0024]
Specifically, the metal pipe 2 is made of stainless steel (for example, austenitic stainless steel such as SUS304, SUS305, and SUS321). At least the tip of the pipe 2 is cylindrical. In addition, a conical tapered portion 21 whose outer diameter decreases toward the front is formed on the outer peripheral surface of the distal end portion of the pipe 2.
[0025]
On the outer peripheral surface near the tip of the pipe 2, punching is performed at four positions on the same circumference at equal intervals, thereby forming four concave portions 3. At the same time, four inwardly projecting portions 4 projecting radially inward are formed on the inner peripheral surface of the pipe 2 where the recesses 3 are located. The front portion 41 of the inwardly protruding portion 4 serves as a ball receiving seat that supports the rear surface of the ball 9.
[0026]
The punching is performed by simultaneously punching four punches radially inward on the outer peripheral surface near the tip of the pipe 2. Since the tip of the punch has a conical or pyramidal pointed shape, the front surface portion 41 of the inwardly protruding portion 4 becomes a ball receiving seat inclined with respect to the axis.
[0027]
On the outer peripheral surface of the pipe 2 radially outward of the ball accommodating chamber 8, four small concave portions 6 having a shallower radial depth than the concave portions 3 are formed at regular intervals on the same circumference by punching. Is done. The minute concave portion 6 is formed on an axial extension line passing through the center of the distance between the adjacent concave portions 3. Further, the bottom of the minute recess 6 is located slightly forward of the bottom of the recess 3. As shown in FIG. 5, the CC line passes through the bottom of each minute recess 6, and the DD line passes through the bottom of each recess 3. That is, the line CC is located slightly forward of the line DD and passes through the front surface portion 41 inclined with respect to the axis of the inwardly protruding portion 4.
[0028]
Due to the minute concave portion 6, a bulging portion 7 slightly protruding radially inward is formed on the inner peripheral surface of the pipe 2 of the ball storage chamber 8. The bulging portion 7 is formed at the center of the distance between the inclined front surfaces 41 (ball receiving seats) of the adjacent inwardly projecting portions 4. Therefore, the bulging portion 7 protrudes largely inward in the radial direction, and even if the diameter of the virtual inscribed circle contacting the vertex of the bulging portion 7 becomes smaller than the outer diameter of the ball 9, the bulging portion 7 does not contact the ball 9. Can be easily set.
[0029]
After the concave portion 3 for the ball receiving seat is formed, the inner peripheral surface of the pipe 2 (the inner peripheral surface of the ball accommodating chamber 8) near the concave portion 3 has a non-circular cross-sectional shape slightly distorted from circular. Has become. However, the inner peripheral surface of the ball accommodating chamber 8 is corrected to a circular cross section by the minute concave portion 6. Therefore, as shown in FIG. 8, the gap 10 between the outer peripheral surface of the ball 9 and the inner peripheral surface of the ball storage chamber 8 becomes uniform.
[0030]
An annular distal edge 5 is formed at the distal end of the pipe 2 by plastic deformation radially inward. The inner peripheral surface of the tip edge 5 prevents the ball 9 from coming off, and the inner peripheral surface of the tip edge 5 contacts the ball 9 in a ring shape to prevent the leakage of ink. The sealing performance between the ball and the ball 9 is improved. In FIG. 5, the two-dot chain line indicates the leading edge 5.
[0031]
In the present invention, the minute concave portions 6 are formed on the extension line in the axial direction passing through the center of the distance between the adjacent concave portions 3 one by one as in the above embodiment. May be formed in plural.
[0032]
In the present invention, it is sufficient that the minute concave portion 6 is at least on an extended line in the axial direction passing between adjacent concave portions 3 (that is, the outer peripheral surface of the pipe 2 excluding the extended line in the axial direction passing through the concave portion 3). It does not necessarily have to be formed on an axial extension passing through the center of the distance between the adjacent recesses 3.
[0033]
In the present invention, it is also effective to adopt a configuration in which the ball 9 is urged forward by a resilient member such as a spring so that the ball 9 comes into close contact with the inner peripheral surface of the distal end portion 5. Thereby, a more reliable sealing property between the tip edge portion 5 and the ball 9 can be obtained.
[0034]
【The invention's effect】
According to the first aspect, the cross-sectional shape of the inner peripheral surface of the ball storage chamber is corrected to be circular by punching for forming a minute concave portion, whereby the outer peripheral surface of the ball and the inner peripheral surface of the ball storage chamber are formed. Is uniform.
[0035]
According to the second aspect, smooth rotation of the ball is maintained in the ink storage chamber.
[0036]
According to the third aspect, even when the inner diameter of the inner peripheral surface of the pipe where the minute concave portion is located is smaller than the outer diameter of the ball, it is easy to obtain a configuration in which the inner peripheral surface of the pipe where the minute concave portion is located does not contact the ball. Can be.
[Brief description of the drawings]
FIG. 1 is a vertical sectional view showing a main part of a first embodiment of the present invention.
FIG. 2 is an end view taken along the line AA of FIG. 1;
FIG. 3 is an end view taken along line BB of FIG. 1;
FIG. 4 is a plan view of FIG. 1;
FIG. 5 is a vertical sectional view showing a main part of a second embodiment of the present invention.
FIG. 6 is an end view taken along line CC of FIG. 5;
7 is an end view taken along line DD of FIG. 5;
FIG. 8 is a plan view of FIG. 5;
FIG. 9 is a longitudinal sectional view of a main part showing a conventional example.
FIG. 10 is an end view taken along line XX of FIG. 9;
FIG. 11 is a plan view of FIG. 9;
[Explanation of symbols]
REFERENCE SIGNS LIST 1 ball-point pen tip 2 pipe 21 tapered portion 3 concave portion 4 inwardly protruding portion 41 front surface portion 5 tip edge portion 6 minute concave portion 7 bulging portion 8 ball accommodating chamber 9 ball 10 gap

Claims (3)

A plurality of recesses are formed by performing punching on the outer peripheral surface near the tip of the metal pipe, and a plurality of inwardly projecting portions for ball receiving seats are formed on the inner peripheral surface of the pipe where the concave portions are located. Further, a ball that plastically deforms the tip of the pipe inward to form an annular tip edge, and rotatably holds a ball in the pipe between the inward projection and the tip edge. In a ball-point pen tip provided with a housing chamber, a plurality of minute recesses having a shallower depth in the radial direction than the recess are formed by performing punching on a pipe outer peripheral surface radially outward of the ball housing chamber. A ballpoint pen tip characterized by the following: The ball-point pen tip according to claim 1, wherein an inner peripheral surface of the pipe where the minute concave portion is located is not in contact with the ball. 3. The pipe according to claim 2, wherein each of the inward projections has an inclined front surface, and an inner peripheral surface of the pipe in which the minute concave portion is located is located between front surfaces of the adjacent inward projections. Ballpoint pen tip.

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