JP4237545B2 - Pipe-type ballpoint pen tip and manufacturing method thereof - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a pipe-type ballpoint pen tip and a manufacturing method thereof. More specifically, the present invention relates to a pipe-type ballpoint pen tip provided with an inward protruding portion for a ball receiving seat by pressing and deforming the vicinity of a metal pipe inward, and a method for manufacturing the same. In the present invention, “front” refers to the ball side for the pen tip, and “rear” refers to the opposite side.
[0002]
[Prior art]
Conventionally, a pipe-type ballpoint pen may be bent due to a large pressure during writing, or the adhesive force between the pen tip and the pen tip holder may loosen due to aging, etc. was there. In order to prevent this, for example, Patent Document 1 discloses that a metal pipe is fixed to the tip of a synthetic resin holder, a metal base is fixed to the holder, and the base is an outer periphery of the pipe behind the ball holding portion. A configuration covering the surface is disclosed.
[0003]
Further, Patent Document 2 discloses a ball-point pen tip in which a front portion is reduced in diameter by roll rolling, and an inward projection (inward protruding portion of the present application) for a ball receiving seat is formed on the reduced front portion. ing.
[Patent Document 1]
Utility Model Registration No. 2607064 [Patent Document 2]
Japanese Patent Publication No. 3-5999 [0004]
[Problems to be solved by the invention]
The ballpoint pen of Patent Document 1 requires a base for supporting the outer peripheral surface of the pipe, which increases the number of parts and increases the manufacturing cost.
[0005]
In the ballpoint pen tip of Patent Document 2, the outer diameter of the front part is reduced by rolling, and the inner diameter of the front part is also reduced at the same time. Therefore, fine wrinkles in the axial direction tend to occur on the inner surface of the front part. Due to the generation of the wrinkles, the surface of the inward protruding portion for the ball seat becomes uneven, and smooth rotation of the ball cannot be obtained during writing, giving the user an unpleasant tingling feeling.
[0006]
In addition, in the conventional pipe-type ballpoint pen tip, even if a thick pipe is simply used in order to improve the strength against bending, punching becomes difficult, and an inward protruding portion having an appropriate shape (that is, a ball receiving seat) ) May not be obtained.
[0007]
The present invention solves the above-mentioned conventional problems, and can increase the strength against bending of the pipe without increasing the number of parts, and can easily obtain a ball seat of an appropriate shape. It is intended to provide a ballpoint pen tip. Furthermore, it is an object of the present invention to provide a pipe-type ballpoint pen tip that suppresses the generation of wrinkles on the surface of the inward projecting portion and obtains smooth ball rotation during writing.
[0008]
[Means for Solving the Problems]
[1] The present invention is a pipe-type ballpoint pen tip 1 in which a ball 3 is rotatably held at the tip of a metal pipe 2, and the metal pipe 2 has a thin portion 4 formed at the tip. And a thick portion 5 continuously provided behind the thin portion 4, a plurality of concave portions 6 are formed by punching on the outer peripheral surface of the thin portion 4, and the inner portion of the thin portion 4 where the concave portion 6 is located A plurality of inwardly projecting portions 7 for ball receiving seats are formed on the peripheral surface, the outer diameter A1 of the thin portion 4 other than the concave portion 6 is set smaller than the outer diameter A2 of the thick portion 5, and The inner diameter B1 at the front of the inward projecting portion 7 of the thin portion 4 and the rear portion of the inward projecting portion 7 of the thin portion 4 is set to be substantially equal to the inner diameter B2 of the thick portion 5. 1) is a requirement.
[0009]
The thickness of the thick portion 5 improves the strength of the pipe 2 against bending, and the bending of the pipe 2 due to a large writing pressure during writing can be suppressed. Further, since the inward protruding portion 7 is formed in the thin portion 4, the inward pressing deformation is facilitated, and the appropriately shaped inward protruding portion 7 (ball receiving seat) can be easily obtained. That is, without increasing the number of parts (that is, increasing the manufacturing cost), it is possible to suppress the bending of the pipe 2 and to easily obtain the inward protruding portion 7 having an appropriate shape.
[0010]
[0011]
According to the first aspect (that is, A1 <A2 and B1 = B2), even if the outer peripheral surface of the thin portion 4 is deformed in a reduced diameter, the inner peripheral surface of the thin portion 4 is not deformed in a reduced diameter. Therefore, wrinkles can be prevented from occurring on the inner peripheral surface of the thin-walled portion 4, and smooth rotation of the ball 3 without wrinkles during writing can be obtained. If wrinkles occur on the inner peripheral surface of the thin wall portion 4, if the wrinkles appear on the surface of the inward protruding portion 7, smooth rotation of the ball 3 at the time of writing cannot be obtained, and 3 gives an unpleasant sensation with rotation. Further, the outer diameter A2 of the thick portion 5 can be set larger than the outer diameter A1 of the thin portion 4, so that when the thick portion 5 of the pipe 2 is fixed to a pen tip holder or the like, the fixing force is improved, and writing is performed. The wobbling of the pipe 2 at the time can be further suppressed.
[0012]
[ 2 ] Further, according to the present invention, a straight center pin 10 is inserted into the center portion of the straight inner hole 21 of the metal pipe 2, and the rotating roller 11 is pressed against the outer peripheral surface of the center portion of the pipe 2. Forming a thin portion 4 at the center of the pipe 2 and forming a thick portion 5 on both sides of the pipe not subjected to the rolling, and a thin portion forming step. Thereafter, a straight center pin 10 is inserted into the central portion of the pipe 2 and the pipe 2 is cut by rolling by pressing the rotary cutting blade 12 to the outer peripheral surface of the central portion of the thin wall portion 4. An edge portion forming step for forming a tapered edge portion 8 at the tip of each of the cut pipes 2, and after the edge portion forming step, the outer peripheral surface of the thin portion 4 is compounded by punching. Forming the plurality of inward projecting portions 7 for the ball receiving seat on the inner peripheral surface of the thin portion 4 where the recessed portion 6 is located, and the inward projecting portion. A pipe-type ballpoint pen tip comprising: a caulking process in which the ball 3 is accommodated on the front side of the inward projecting portion 7 after the forming step, and then the tip of the edge portion 8 is bent inward to hold the ball 3. The manufacturing method (Claim 2 ) is a requirement.
[0013]
Wherein the manufacturing method according to claim 2, it is possible to obtain a pipe type ballpoint pen chip 1 according to claim 1. That is, without increasing the number of parts (that is, increasing the manufacturing cost), the bending of the pipe 2 can be suppressed and the inward protruding portion 7 having an appropriate shape can be easily obtained. Further, since the inner peripheral surface of the thin portion 4 is not deformed to reduce the diameter, wrinkles can be prevented from occurring on the inner peripheral surface of the thin portion 4 and smooth rotation of the ball 3 without wrinkling during writing (ie, Smooth writing quality). Further, since the outer diameter A2 of the thick portion 5 can be set larger than the outer diameter A1 of the thin portion 4, when the thick portion 5 of the pipe 2 is fixed to a pen tip holder or the like, the fixing force is improved, and writing is performed. The wobbling of the pipe 2 at the time can be further suppressed.
[0014]
[ 3 ] In the manufacturing method according to claim 2 , after the thin portion forming step, the center pin 10 can be extracted from the pipe 2, and then a new center pin 10 can be inserted to perform the edge portion forming step. However, it is preferable to perform the edge portion forming step after the thin portion forming step without removing the center pin 10 in the pipe 2 (Claim 3 ).
[0015]
Thereby, in the process from the thin-walled portion forming step to the edge portion forming step, the trouble of pulling out the center pin 10 from the inside of the pipe 2 and the trouble of reinserting the center pin 10 into the pipe 2 become unnecessary, and the manufacturing time can be shortened. .
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described with reference to the drawings.
[0017]
(Pipe ballpoint pen tip)
One embodiment of the pipe-type ballpoint pen tip 1 of the present invention is shown in FIGS.
[0018]
The ballpoint pen tip 1 of the present embodiment includes a metal pipe 2 having a cylindrical thin portion 4 at the tip and a cylindrical thick portion 5 extending rearward from the thin portion 4, and the thin portion A recess 6 formed by punching on the outer peripheral surface in the vicinity of the tip of 4, an inward projection 7 for a ball receiving seat formed on the inner peripheral surface of the thin portion 4 where the recess 6 is located, A taper-shaped edge portion 8 that is bent inwardly into a ring shape and crimped, a ball housing chamber 9 formed in a thin portion 4 between the inward projection portion 7 and the edge portion 8, and the ball The ball 3 is rotatably held in the storage chamber 9.
[0019]
Specifically, the metal pipe 2 is made of stainless steel (for example, austenitic stainless steel such as SUS304, SUS305, or SUS321). A thin portion 4 having a thickness C1 of 0.14 mm is formed at the front portion of the pipe 2, and a thick portion 5 having a thickness C2 of 0.19 mm is formed at the rear portion of the pipe 2. . The inner diameter B1 of the thin wall portion 4 other than the inner protrusion portion 7 (that is, the front and rear portions of the inner protrusion portion 7) is set substantially equal to the inner diameter B2 of the thick wall portion 5. Specifically, the inner diameter B1 of the thin portion 4 and the inner diameter B2 of the thick portion 5 are set to 0.52 mm. The outer diameter A1 of the thin portion 4 is set to 0.8 mm, and the outer diameter A2 of the thick portion 5 is set to 0.9 mm. Between the outer peripheral surface of the thin-walled portion 4 and the outer peripheral surface of the thick-walled portion 5, a conical surface 22 whose diameter increases toward the rear is formed.
[0020]
On the outer peripheral surface in the vicinity of the tip of the thin-walled portion 4, punching is performed at three locations on the same circumference at equal intervals, whereby three recesses 6 are formed. At the same time, three inward projecting portions 7 projecting radially inward are formed on the inner peripheral surface of the pipe 2 where the recess 6 is located. The front portion of the inward protruding portion 7 serves as a ball receiving seat that supports the rear surface of the ball 3.
[0021]
A ball 3 having an outer diameter of 0.5 mm is accommodated in the inside of the thin portion 4 on the front side of the inward protruding portion 7. And after accommodating the said ball | bowl 3, the taper-shaped edge part 8 of the front-end | tip of the said thin part 4 is bend | folded annularly inward, and it crimps. A ball housing chamber 9 having an inner diameter B1 of 0.52 mm is formed between the edge portion 8 and the inward projecting portion 7, and the ball 3 is rotatably held therein.
[0022]
(Pipe ballpoint pen manufacturing method)
FIG. 4 shows a manufacturing method of the pipe-type ballpoint pen tip 1 of the embodiment. The manufacturing process proceeds in the order of (a) → (b) → (c) → (d) → (e) → (f) as shown by the arrows in FIG.
[0023]
FIG. 4A shows the metal pipe 2 before the thin portion forming step.
Here, the metal pipe 2 comprises a relatively thick straight cylindrical pipe 2 having an outer diameter of 0.9 mm, an inner diameter of 0.52 mm, and a wall thickness of 0.19 mm. A straight inner hole 21 (inner diameter 0.52 mm) penetrating in the axial direction is formed in the axial center of the pipe 2.
[0024]
FIG. 4B shows a thin portion forming process.
A straight center pin 10 having an outer diameter substantially equal to the inner diameter of the inner hole 21 of the pipe 2 (outer diameter 0... 0) is provided at the center of the straight cylindrical metal pipe 2 shown in FIG. 52 mm) is inserted, and the two rotating rollers 11 are pressed against the outer peripheral surface of the central portion of the metal pipe 2. The rotating roller 11 includes a straight surface 11a having a constant outer diameter in the direction of the rotation axis formed in the center portion, and tapered surfaces 11b (angle formed by the rotation axis: 30 degrees) formed on both sides of the straight surface 11a. .
[0025]
The two rotating rollers 11 have the same rotational direction and rotational speed, and roll the metal pipe 2 between the two rotating rollers 11. Thereby, the center part of the said pipe 2 is rolled by the straight surface 11a of the rotating roller 11, and the thin part 4 is formed there. A thick portion 5 is formed at a portion other than the central portion of the pipe 2 that is not subjected to the rolling process (that is, on both sides of the thin portion 4). Specifically, the thin portion 4 has an outer diameter A1 of 0.8 mm, an inner diameter B1 of 0.52 mm, and a thickness C1 of 0.14 mm, and the thick portion 5 has an outer diameter A2 of 0.1 mm. 9 mm, the inner diameter B2 is set to 0.52 mm, and the wall thickness C2 is set to 0.19 mm. That is, the outer diameter A1 of the thin portion 4 is set smaller than the outer diameter A2 of the thick portion 5 (A1 <A2), and the inner diameter B1 of the thin portion 4 matches the inner diameter B2 of the thick portion 5. The thickness C1 of the thin portion 4 is set to be thinner than the thickness C2 of the thick portion 5 (C1 <C2). A conical surface 22 (angle formed by the axis: 30 degrees) is formed between the thin portion 4 and the thick portion 5 by the tapered surface 11b of the rotating roller 11.
[0026]
FIG. 4C shows an edge portion forming process.
While the center pin 10 (outer diameter 0.52 mm) used in the thin-walled portion forming process is inserted in the central portion of the metal pipe 2 in which the thin-walled portion 4 is formed, the metal pipe 2 is not inserted. The two rotary cutting blades 12 are brought into pressure contact with the outer peripheral surface of the central portion. The rotary cutting edge 12 includes two tapered surfaces 12a (angle formed with the rotation axis: 25 degrees) formed on both sides of the outer peripheral surface, and an annular top 12b at a location where the two tapered surfaces 12a intersect. .
[0027]
Similar to the thin-walled portion forming step, the two rotary cutting blades 12 have the same rotational direction and rotational speed, and the metal pipe 2 is rolled between the two rotary cutting blades 12. As a result, the central portion of the pipe 2 is rolled by the tapered surface 12a of the rotary cutting blade 12, and the edge portion 8 is formed there, and at the same time, the pipe 2 is formed at the central portion by the annular top portion 12b of the rotary cutting blade 12. Cut into halves. A tapered edge portion 8 having a tapered surface 12a (angle formed by the axis: 25 degrees) on the outer peripheral surface is formed at the tip of each of the cut pipes 2. FIG. 4D shows the pipe 2 after the edge portion forming step.
[0028]
FIG. 4E shows the inward protrusion forming step.
After the edge portion forming step, three concave portions 6 are formed at equal intervals on the same circumference on the outer peripheral surface near the tip of the thin portion 4 by punching. At the same time, three inward projecting portions 7 projecting radially inward are formed on the inner peripheral surface of the pipe 2 where the recess 6 is located. The front portion of the inward protruding portion 7 serves as a ball receiving seat that supports the rear surface of the ball 3. The punching is performed by simultaneously punching three punches 13 radially inwardly on the outer peripheral surface near the tip of the thin portion 4. During the punching process, a conical pointed guide pin 14 is inserted into the distal end opening of the thin portion 4, and the guide pin 14 is pressed against the front surface portion of the inward projecting portion 7. Since the tip of the punch 13 has a conical pointed shape, the front surface of the inward projecting portion 7 is a ball receiving seat inclined with respect to the axis.
[0029]
FIG. 4 (f) shows the caulking process.
After the inward projecting portion forming step, the ball 3 is accommodated in the thin portion 4 on the front side of the inward projecting portion 7, and then the edge portion 8 at the tip of the thin portion 4 is used as the conical inner surface of the caulking die 15. The edge portion 8 is bent inward to be plastically deformed (caulking). Thereby, a part of the ball 3 is slightly protruded forward, and the ball 3 is prevented from coming out, and the ball accommodating chamber 9 (inner diameter 0. 0) formed between the edge portion 8 and the inward protruding portion 7 is prevented. 52 mm), the ball 3 is rotatably held, and the pipe-type ballpoint pen tip 1 is obtained.
[0030]
【The invention's effect】
According to the first aspect of the present invention, a pipe-type ballpoint pen tip that can improve the strength against bending of a pipe without increasing the number of parts and can easily form a ball receiving seat having an appropriate shape is obtained.
[0031]
According to claim 1 , since the inner peripheral surface of the thin wall portion is not deformed and reduced in diameter, it is possible to avoid the occurrence of wrinkles on the inner peripheral surface of the thin wall portion, and smooth rotation of the ball without wrinkles during writing can be obtained. . In addition, the outer diameter of the thick part can be set larger than the outer diameter of the thin part, so that when the thick part of the pipe is fixed to the pen tip holder etc., the fixing force is improved, and the pipe wobbles during writing. It can be further suppressed.
[0032]
According to the second aspect of the present invention, it is possible to easily suppress the bending of the pipe and to obtain an inward protruding portion having an appropriate shape without increasing the number of parts. Further, since the inner peripheral surface of the thin portion is not deformed and reduced in diameter, it is possible to avoid the occurrence of wrinkles on the inner peripheral surface of the thin portion, and smooth rotation of the ball without wrinkles during writing can be obtained. In addition, the outer diameter of the thick part can be set larger than the outer diameter of the thin part, so that when the thick part of the pipe is fixed to the pen tip holder etc., the fixing force is improved, and the pipe wobbles during writing. It can be further suppressed.
[0033]
According to the third aspect , in the process from the thin-walled portion forming step to the edge portion forming step, it is not necessary to remove the center pin from the pipe and to insert the center pin again in the pipe, and the manufacturing time can be shortened.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view showing an embodiment of a pipe-type ballpoint pen tip according to the present invention.
FIG. 2 is an enlarged vertical sectional view of a main part of FIG.
FIG. 3 is an end view taken along line XX of FIG.
4A shows a pipe before a thin part forming process, FIG. 4B shows a thin part forming process, FIG. 4C shows an edge part forming process, and FIG. 4D shows a part after the edge part forming process. (E) shows an inward protrusion forming process, and (f) shows a caulking process.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Pipe type ball-point pen tip 2 Pipe 21 Inner hole 22 Conical surface 3 Ball 4 Thin part 5 Thick part 6 Recessed part 7 Inward protrusion part 8 Edge part 9 Ball storage chamber 10 Center pin 11 Rotating roller 11a Straight surface 11b Tapered surface 12 Rotation Cutting edge 12a Tapered surface 12b Annular top 13 Punch 14 Guide pin 15 Caulking die A1 Thin part outer diameter A2 Thick part outer diameter B1 Thin part inner diameter B2 Thick part inner diameter C1 Thin part thickness C2 Thick part Thickness

Claims (3)

A pipe-type ballpoint pen tip that rotatably holds a ball at the tip of a metal pipe, wherein the metal pipe is connected to a thin portion formed at the tip and a rear side of the thin portion. And forming a plurality of recesses by punching on the outer peripheral surface of the thin-walled portion and forming a plurality of inward protruding portions for a ball receiving seat on the inner peripheral surface of the thin-walled portion where the concave portion is located , The outer diameter of the portion other than the concave portion of the thin portion is set to be smaller than the outer diameter of the thick portion, and the front portion of the thin portion and the rear portion of the thin portion. The pipe-type ballpoint pen tip is characterized in that the inner diameter of is set to be substantially equal to the inner diameter of the thick wall portion . Insert a straight center pin into the center of the straight inner hole of the metal pipe, and press the rotating roller against the outer peripheral surface of the center of the pipe to make a thin wall at the center of the pipe. Forming a thick part on both sides of the pipe not subjected to the rolling process at the same time,
After the thin-walled portion forming step, a straight center pin is inserted into the central portion of the pipe, and the pipe is cut by rolling by pressing a rotary cutting blade on the outer peripheral surface of the central portion of the thin-walled portion. At the same time, an edge portion forming step of forming a tapered edge portion at the tip of each cut pipe,
After the edge portion forming step, a plurality of concave portions are formed on the outer peripheral surface of the thin portion by punching, and at the same time, a plurality of inward protruding portions for ball receiving seats are formed on the inner peripheral surface of the thin portion where the concave portion is located. An inward protrusion forming step to be formed;
A pipe-type ballpoint pen tip comprising: a caulking process for holding the ball after the inner projecting part forming step, and then holding the ball by bending the tip of the edge part inward. Manufacturing method. The pipe type ball-point pen tip manufacturing method according to claim 2, wherein after the thin-walled portion forming step, the edge-portion forming step is performed in an inserted state without removing the center pin in the pipe.

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