JPS6048355B2 - Ballpoint pen and its manufacturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a ballpoint pen and a method for manufacturing the same, and more particularly to an improvement in a ballpoint pen in which a ball is held at the tip of a thin metal tube of a pen tip, and a method for manufacturing the same.

Conventionally, as a ballpoint pen J for fine print using water-based ink, a porous fiber bundle for introducing water-based ink is filled into a metal thin tube whose rear end is fixed to a holder, and a porous fiber bundle is filled in the tip of the metal thin tube. A structure is known in which a ceramic body having pores in the axial direction is fitted into the fiber bundle, and a portion of the fiber bundle protrudes from the pores of the ceramic body.

In such a ballpoint pen, water-based ink in a holder is introduced into a porous fiber bundle in a metal capillary, and the ink is supplied by the fiber bundle protruding from a hole in a ceramic body at the tip of the metal capillary for writing. However, such ballpoint pens have the drawback of poor smoothness when writing because the ceramic body at the tip, which has a large coefficient of friction, is brought into contact with the writing surface. For this reason, ballpoint pens are known in which a ball is held at the tip of a thin metal tube.

For example, a ballpoint pen (Japanese Utility Model Publication No. 166681/1981) has been proposed in which a porous fiber bundle is filled in a thin metal tube and a ball is held at the tip of the thin metal tube by caulking. This ballpoint pen, like conventionally well-known ballpoint pens, has an ink from the ball. Ink is supplied and smooth writing is possible. However, this ballpoint pen uses a porous fiber bundle that easily deforms to fix the ball under pressure, and the ball has a significantly smaller diameter than conventional balls, which causes the ball to drop when writing. This had the disadvantage that the writing performance was significantly impaired because the metal tube sank into the thin metal tube beyond its intended position. In addition, as another ballpoint pen, a synthetic resin ball seat having an ink introduction hole in the axial direction of the thin metal tube is inserted into the entire metal thin tube, and the ball is brought into contact with the ball seat at the tip of the metal thin tube. A structure (Japanese Unexamined Patent Publication No. 55-97992) has been proposed.

However, in ballpoint pens with this structure, a synthetic resin ball seat is inserted into almost the entire metal capillary except for the tip, so the difference in thermal expansion coefficient between the metal capillary and the synthetic resin ball seat As a result, the ball at the tip of the thin metal tube, which is press-fixed to the ball seat, shifts from its intended position, resulting in a disadvantage that the writing performance is significantly impaired. The present invention has been made to solve the above-mentioned drawbacks, and includes a pen tip consisting of a holder and a metal thin tube whose rear end side is integrated with the holder, and a ball is held at the tip of the metal thin tube of the pen tip. An object of the present invention is to provide a ballpoint pen that has a structured structure, can write fine print smoothly, and can prevent the ball from shifting its position during use, thereby preventing the ball from sinking into a metal capillary tube or falling off, and a method for manufacturing the same. It is.

That is, the ballpoint pen of the present invention includes a holder made of synthetic resin having an ink introduction hole, a thin metal tube whose rear end side is inserted into a cylindrical portion of the holder, and the metal covered near the tip of the cylindrical portion. At least one or more first small holes drilled in the side wall portion of the thin tube; and a synthetic resin material that is integrally provided on the inner surface of the cylindrical portion and projects into the first small hole of the metal thin tube. a protrusion, at least one or more second small holes drilled in the side wall near the tip of the metal thin tube, and a part of the outer surface buried inside the metal thin tube near the tip. A pen tip consisting of a ball receiving part made of synthetic resin that protrudes into the second small hole of the thin tube, and an ink introduction hole penetrated through the ball receiving part in the axial direction of the metal thin tube, and the metal of the pen tip is This device is characterized in that a ball is rotatably held at the tip of the thin tube by the thin tube and the ball receiving portion.

Further, the method of the present invention includes a fixed mold having a first molding chamber;
A shaft pin that is inserted and fixed at a predetermined position in the molding chamber, a first gate portion that is formed in the fixed mold and communicates with a portion of the molding chamber near the shaft pin, and a first gate that can be opened and closed with respect to the fixed mold. a second molding chamber provided in the movable mold and located coaxially with the first molding chamber; an ejecting sleeve inserted into the molding chamber so as to be freely retractable; a center pin which is inserted into the movable mold so as to be able to move forward and backward and has two step portions on the distal end side such that the center pin becomes thinner toward the distal end; After the movable mold is opened relative to the fixed mold when manufacturing a ballpoint pen using a device comprising a second gate portion that is partially integrated with the first gate portion when closed against the fixed mold. , a step of advancing the ejecting sleeve to a predetermined position in the second molding chamber, and further advancing the center pin along the sleeve to sufficiently protrude from the surface of the movable mold that comes into contact with the fixed mold; A metal thin tube having at least one first and second small hole drilled in the side wall of the end and the side wall near the tip, respectively, is prepared, and a metal thin tube is inserted into the protruding center pin from the rear end side of the metal thin tube. A step of fitting most of the tube and fixing the rear end surface of the thin tube by abutting it against the first stepped part of the pin, moving the movable mold to abut the fixed mold, and fixing the tip of the center pin at the same time. a step of bringing the shaft core pin inserted and fixed into the mold into contact with the end surface of the arrow-shaped groove and covering the arrow-shaped groove with the tip side of the metal capillary tube; The molten synthetic resin is supplied to the second gate part, and from the first gate part, the fixed mold, the movable mold are integrated into the first and second molding chambers, the metal thin tube fitted to the center pin, and Molten synthetic resin is injected into the space between the center pin, and the molten resin flows from the space into the first small hole of the metal capillary, and the metal capillary passes from the second gate part through the second small hole of the metal capillary. A process of molding a pen tip in which a thin metal tube and a synthetic resin holder part are integrated by injecting the metal tube between the arrow-shaped groove of the shaft core part, and a process of molding the pen tip by opening it with respect to the movable mold and the fixed mold. A process of moving the pen tip along with the center pin, a process of moving the ejecting sleeve further into the center pin to remove the pen tip from the center pin, and inserting a ball into the tip of the thin metal tube of this pen tip and performing a culling process to form a hole. Examples of the metal capillary tube used in the present invention include a stainless steel capillary tube and a brass capillary tube.

The number of first and second small holes formed in the metal thin tube used in the present invention is preferably one or more, preferably about two to five. The shapes of these first and second small holes are arbitrary, such as round, square, and elongated. However, these first and second small holes do not necessarily have to be the same number, the same shape, and the same size. For example, the first small hole may be round, and two small holes may be provided, and the second small hole may be square. In addition, it is also possible to provide three. Examples of the synthetic resin used in the present invention include thermoplastic resins such as acetal resin, polyamide resin, and polyimide resin.

Next, embodiments of the present invention will be described with reference to the drawings. 1st
Figures a to e show a manufacturing apparatus used in the method of the present invention and a part of its manufacturing process.

1 in the figure is a fixed mold, and this fixed mold 1 has a fixed side core 2, a fixed side plate 3 that surrounds and fixes the outer peripheral surface of this core 2, and is arranged on the rear surfaces of these cores 2 and face plate 3. A fixed side auxiliary base 4 is provided. A first molding chamber 5 passing through the core 3 in the horizontal direction is provided. A shaft pin 7 having an arrow-shaped groove 6 at its tip is inserted and fixed into the molding chamber 5 halfway into the molding chamber 5 . Furthermore, a first gate portion 8 is provided extending from the top of the face plate 3 to the core 2 and communicating with a portion of the molding chamber 5 near the arrow-shaped groove portion 6. Further, numeral 1 in the figure is a movable mold that opens and closes with respect to the fixed mold 1.

This movable mold 1 includes a movable side core 10, a movable side plate 11 that surrounds and fixes the outer peripheral surface of this core 10, and these cores 10 and 10.
and a movable auxiliary base 12 arranged on the rear surface of the face plate 11.
It is equipped with. A second molding chamber 13 passing through the core 10 in the horizontal direction is provided, and a through hole 14 communicating with the molding chamber 13 is bored in the auxiliary base 12 . A protruding sleeve 15 is inserted into the through hole 14 and the molding chamber 13 from the auxiliary base 12 side so that it can move forward and backward. Also, inside this sleeve 15 is a center pin 1.
6 is inserted from the auxiliary base 12 side so that it can move forward and backward.
The center pin 15 has two step portions 17, 17 on the distal end side, which become thinner toward the distal end. is formed. Furthermore, a first gate part 8, which extends from the upper part of the face plate 11 to the core 10 and communicates with the molding chamber 13, is partially integrated with the first gate part 8 when the movable mold 1 is closed with respect to the fixed mold 1. Two gate sections 18 are provided. Next, a process for manufacturing a ballpoint pen using the above-mentioned apparatus will be explained. [1
] First, after moving the movable mold 1 in the direction of arrow A and opening it relative to the fixed mold 1, the ejecting sleeve 15 is moved.
was introduced from the through hole 14 of the movable auxiliary base 12 to a predetermined position in the second molding chamber 13.

Next, the center pin 16 inserted into the sleeve 15 was advanced so that the first stepped portion 17 on the front side of the sleeve 15 was positioned in front of the core 10 (as shown in FIG. 1A). .

[Ii] Next, two first and second small holes 19, 19, 20 are formed around the side wall of the rear end and the side wall of the tip, respectively.
Prepare a stainless steel thin tube 21 with holes 20 at 90° intervals, and fit most of the protruding center pin 16 from the rear end side of this stainless steel thin tube 21, and insert the rear end surface of the thin tube 21 into the first pin 16. It was fixed in contact with the stepped portion 17.

In other words, most of the stainless steel thin tube 21, except for the vicinity of the tip where the second small holes 20, 20 are bored, is fitted into the peripheral surface of the center pin 16 extending from the tip to the first stepped portion 17 (
(Illustrated in Figure 1b). [III] Next, the movable mold 1 is moved in the direction of arrow B, and the core 2 and face plate 3 of the fixed mold 1 are moved.
The front of. The core 10 and the front surface of the face plate 11 of the movable mold 1 were brought into contact with each other. At this time, as shown in Figure 1c, the first and second
At the same time, the molding chambers 5 and 12 of the center pin 1 are integrated.
The tip of the stainless steel tube 1.9 contacts the arrow-shaped groove 6 of the shaft pin 7, and the tip of the stainless steel tube 1.9 contacts the arrow-shaped groove 6.
is covered. The first and second gate portions 8 and 18 formed on the fixed side plate 3 and the movable side plate 11 are integrated. This step completes the preparation for molding. [Iv] Next, molten acetal resin was supplied to the integrated first and second gate parts 8 and 18. At this time, Figure 1 d
As shown in the figure, the acetal resin is divided into a first gate part 8 and a second gate part 18. The acetal resin from the first gate part 8 is injected into the first and second molding chambers 5 and 12 into which the center pin 16 and the stainless steel thin tube 2-1 are inserted, and then into the first small hole 19 of the stainless steel thin tube 21. , 19. At the same time, the acetal resin from the second gate part 18 is injected between the thin tube 21 and the arrow-shaped groove 6 of the shaft core 7 through one of the second small holes 20 of the thin tube 21. By such injection, a pen tip 23 in which a stainless steel tube 21 was integrated with a holder 22 made of acetal resin was molded. [
v] Next, the movable mold 1 is moved again in the direction of arrow A and opened relative to the fixed mold 1, thereby moving the pen tip 11 together with the center pin 16 toward the movable mold 1 (Fig. 1 e).
(Illustrated).

Subsequently, the ejecting sleeve 15 was further advanced, and the pen tip 23 in contact with the distal end surface thereof was removed from the movable mold 9 to obtain the pen tip 11 shown in FIG. 1F. The holder 22 constituting this pen tip 23 has a large diameter cylindrical portion 2 that forms an ink introduction hole 24 from near the center to the rear end.
5, and a small-diameter cylindrical portion 28 that communicates with the ink introduction hole 24 through a communication hole 27 provided in the partition wall 26 near the center from the center to the tip side. On the other hand, the rear end side of the stainless steel thin tube 21 is integrally inserted into the small diameter cylindrical portion 28 of the holder 22.
That is, the inner surface of the small diameter cylindrical portion 28 is integrally provided with acetal resin protrusions 29, 29 that protrude into the first small holes 19, 19 bored at the rear end side of the stainless steel tube 21. As a result, the thin tube 21 is integrally inserted into the small diameter cylindrical portion 28. Further, an acetal resin ball receiving part 31 having ink circulation holes 30 is buried near the tip of the stainless steel thin tube 21, and a part of the outer surface of the ball receiving part 31 has the tip of the stainless steel thin tube 21 buried therein. Protrusions 32, 32 made of acetal resin are integrally provided that protrude into second small holes 20, 20 bored in the vicinity of the parts. ■] Next, a metal ball 33 with an outer diameter of 0.677!771 is inserted from the tip opening of the stainless steel tube 21.
After inserting the ball into contact with the front surface of the ball receiving part 31 inside, the tip part 34 was caulked into a bullet shape to hold the ball 33 in a rotatable manner (Fig. 1g). Figure, 3rd
(Illustrated)

In addition, Fig. 2 is an enlarged cross-sectional view along the line ■-■ of Fig. 1 g,
FIG. 3 is an enlarged sectional view taken along the line ■-■ in FIG. 1g.
Thereafter, a ballpoint pen was manufactured by inserting the holder 22 of the pen tip 23 into a pen shaft (not shown). According to the method of the present invention, ballpoint pens having various effects and deficiencies as described below can be easily produced by using a device having a double cage structure.

) Ink from a pen shaft (not shown) is supplied to the introduction hole 24 of the holder 22, the communication hole 27, the stainless steel thin tube 21, and the ball receiving portion 31 buried inside the thin tube 21 near its tip.
The ink is supplied to the tip 34 of the capillary tube 19 through the ink distribution holes 30 . Since the ball 33 is held rotatably by the front surface of the high ball receiving portion 31, fine letters can be written smoothly by rotating the ball 33 on the writing surface. (2) During the above writing, the rear surface side of the held ball 331 comes into contact with a synthetic resin ball receiving part 31 buried inside near the tip of the stainless thin tube 21, and the receiving part 31 is placed behind the thin tube 21. pushed to the edge.

However, as shown in FIG. 1 g) and FIG.
Projections 32, 32 that project inward are integrally formed. Therefore, even if the ball receiving portion 31 is pushed toward the rear end of the thin tube 21 by the ball 33, the second small holes 20, 20
Due to the protrusions 32, 32 present within. The stopper action can prevent the ball receiving portion 31 from sliding toward the rear end of the thin tube 21. As a result, during writing, the ball 33 can be prevented from sinking into the stainless steel thin tube 21 from its intended position, and good writing performance can be maintained for a long period of time. (
3) The ball receiving part 31 made of synthetic resin is not buried entirely inside the stainless steel thin tube 21, but is partially embedded near the tip of the thin tube 21, so that the ball receiving part 31 made of synthetic resin is not buried entirely inside the stainless steel thin tube 21. Even if the coefficient of thermal expansion is larger than that of the stainless steel thin tube 21, the distance that the ball receiving portion 31 expands in the axial direction due to the influence of heat can be suppressed to a small extent.

As a result, it is possible to prevent the small diameter ball 33 from sliding toward the tip side or falling off due to the expansion of the ball receiving portion 31 during writing, and good writing performance can be maintained for a long period of time. (4) In the first small holes 19, 19 of the stainless steel thin tube 21, there are protrusions 29, 29 made of synthetic resin that are integrated with the small diameter cylindrical part 28.
, the stainless steel thin tube 21 is firmly fixed to the small-diameter cylindrical portion 28, that is, the holder 22, via the projections 29, 29.

Therefore, pulling out of the stainless steel tube 21 can be reliably prevented. In addition, since the stainless steel thin tube 21 is integrated with the holder 22, the pen tip 23 does not have to go through the complicated process of inserting the holder into the pen shaft and inserting the metal thin tube into the holder as in the past. A ballpoint pen can be assembled by inserting the large-diameter cylindrical portion 25 of the holder 22 into a pen shaft (not shown). As a result, the productivity of ballpoint pens can be improved and automatic assembly becomes possible. (5) The rear end of the stainless steel thin tube 21 is inserted into the small-diameter cylindrical portion 28 of the holder 22, and its tip side protrudes from the holug 22 with a sufficient length.

As a result, the small diameter long stainless steel tube 21 inserted into the small diameter cylindrical part 28 of the holder 22 protrudes from the tip of the ballpoint pen, so that the shielding of the paper during writing can be reduced and writing performance can be improved. In addition, in the above embodiment, an axial center pin having an arrow-shaped groove was used to form an ink circulation hole in the ball receiving part, but an empty ball receiving part was formed, and after molding, an ink circulation hole was formed in the ball receiving part using a laser or the like. You can open it.

As described in detail above, according to the present invention, a ball is held at the tip of a thin metal tube that is integrated with a holder and whose tip side protrudes from the holder by a predetermined length, and fine letters can be written smoothly. It also prevents the ball from shifting its position during use, prevents the ball from sinking into the metal tube or falling off, and maintains good writing performance for a long time.Furthermore, the assembly process can be shortened and automatic assembly is possible, and other writing It is possible to provide a ballpoint pen that has remarkable effects such as ease of writing without being blocked by time, and a method for easily manufacturing such a ballpoint pen.

[Brief explanation of the drawing]

Figures 1a-g are cross-sectional views showing the manufacturing process of a hole pen in an embodiment of the present invention, Figure 2 is an enlarged cross-sectional view taken along the line ■-■ of Figure 1g, and Figure 3 is a cross-sectional view of Figure 1g. FIG. 1...Fixed mold, 2...Core, 5
....First molding chamber, 6 ....Sagittal groove, 7 .... Axis pin, 8 ....First
Gate part, 1...Movable mold, 10...
・Core, 13...Second molding chamber, 14...
...Through hole, 15...Protrusion sleeve, 16
...Center pin, 17,,172...Step part, 18...Second gate part, 19...
...First small hole, 20...Second small hole, 21.
... Stainless steel tube, 22 ... Holder,
11...Pen tip, 24...Ink introduction hole, 28...Small diameter cylindrical part, 29...
...Protrusion, 30...Ink distribution hole, 31...
...Ball receiving part, 32...Protrusion part. 33...Ball.

Claims (1)

[Scope of Claims] 1. A holder made of synthetic resin having an ink introduction hole, a thin metal tube whose rear end side is inserted into a cylindrical portion of the holder, and the metal covered near the tip of the cylindrical portion. At least one or more first small holes drilled in the side wall portion of the thin tube; and a synthetic resin material that is integrally provided on the inner surface of the cylindrical portion and projects into the first small hole of the metal thin tube. a protrusion, at least one or more second small holes drilled in the side wall near the tip of the metal thin tube, and a part of the outer surface buried inside the metal thin tube near the tip. A pen tip consisting of a ball receiving part made of synthetic resin that protrudes into the second small hole of the thin tube, and an ink flow hole penetrated through the ball receiving part in the axial direction of the metal thin tube, and the metal of the pen tip is A ballpoint pen characterized in that a ball is rotatably held at the tip of the thin tube by the thin tube and the ball receiving portion. 2. A fixed mold having a first molding chamber, a shaft core pin inserted and fixed to a predetermined position in the molding chamber, and a first mold formed in the fixed mold and communicating with a portion of the molding chamber near the shaft core pin. a gate part, a movable mold that opens and closes with respect to the fixed mold, a second molding chamber provided in the movable mold and located coaxially with the first molding chamber, and a movable mold that moves forward and backward into the molding chamber. an ejecting sleeve that is freely inserted; a center pin that is inserted into the sleeve so that it can move back and forth and has two step portions on the distal end side so that the tip becomes thinner; and the second molding chamber that is formed in the movable mold. In manufacturing a ballpoint pen using an apparatus comprising a second gate part that communicates with the movable mold and is partially integrated with the first gate part when the movable mold is closed with respect to the fixed mold, After the mold is opened relative to the fixed mold, the ejecting sleeve is advanced to a predetermined position in the second molding chamber, and the center pin is further advanced along the sleeve to bring the movable mold into contact with the fixed mold. A step of sufficiently projecting from the surface of the mold, and at least one first hole formed in the side wall of the rear end and the side wall near the tip.
, preparing a metal thin tube having a second small hole, and fitting most of the metal thin tube into the protruding center pin from the rear end side of the metal thin tube;
A process of fixing the rear end surface of the thin tube by abutting it on the first stepped part of the pin, moving the movable mold to abut the fixed mold, and simultaneously inserting and fixing the tip of the center pin into the fixed mold. a step of contacting the end face of the arrow-shaped groove of the shaft core pin and covering the arrow-shaped groove with the tip side of the metal capillary tube; The molten synthetic resin is supplied from the first gate part to the space between the first and second molding chambers where the fixed mold and movable mold are integrated, and the metal thin tube and the center pin fitted to the center pin. The molten synthetic resin is injected, and the molten resin is allowed to flow from the space into the first small hole of the metal capillary, and the molten resin flows between the metal capillary and the shaft core from the second gate portion through the second small hole of the metal capillary. The process of molding a pen tip with an integrated metal capillary and synthetic resin holder by injecting it between the arrow-shaped groove, and moving the pen tip together with the center pin by opening the movable mold and the fixed mold. a step of further advancing the ejecting sleeve to demold the pen tip of the center pin; and a step of inserting a ball into the tip of the metal capillary of the pen tip and holding the ball by caulking. A method for manufacturing a ballpoint pen characterized by: