Manufacturing method of refill for writing instrument

Abstract

To provide a writing instrument refill that can secure a necessary and sufficient ink storage capacity and the mechanical strength of an end portion of an ink storage tube without expanding the outer diameter of the ink storage tube, and a writing instrument using the same.SOLUTION: The writing instrument refill includes an ink storage tube 1 formed into a cylindrical shape by making it straight with a resin material and a writing chip 2 attached to the end portion of the ink storage tube. At the end portion of the ink storage tube 1, a press-fitting portion 1a is formed so as to be thick toward the inner peripheral surface and having an opening hole penetrating in the axial direction at the center thereof. The writing chip 2 or a relay member 3 that supports the writing chip is press-fitted and attached to the press-fitting portion 1a.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a method for manufacturing a refill for a writing instrument, for example, used for a ballpoint pen. [Background technology]

[0002] 2. Description of the Related Art A refill for a writing instrument used in a ballpoint pen or the like generally has a ballpoint tip as a writing part, which is press-fitted into one end (front end) of an ink reservoir tube. In addition, in order to ensure ease of molding and visibility of the ink amount, resin materials such as polypropylene have conventionally been used for the ink reservoir tube.

[0003] Figure 14 shows a cross-sectional view of an example of a conventional ballpoint pen refill, and the example shown in Figure 14 shows a configuration in which a ballpoint pen tip 2 is attached to the front end of an ink containing tube 1 via a joint member 3. The outer circumferential surface of the ink containing tube 1 is formed into a flush cylindrical shape, and the inside diameter of the front end of the ink containing tube 1 into which the joint member 3 is fitted and the inside diameter of the axial center part of the ink containing tube 1 that constitutes the ink containing section are configured into a straight shape with approximately the same dimension. Such a ballpoint pen refill using an ink reservoir tube with a straight inner peripheral surface is disclosed in, for example, Patent Document 1.

[0004] Similarly, a ballpoint pen refill has been proposed in which the outer peripheral surface of the ink containing tube is formed into a flush cylindrical shape, and the inner diameter of the front end of the ink containing tube into which the ballpoint pen tip is fitted is hollowed out to be larger than the inner diameter of the axial center portion that constitutes the ink containing section; this is disclosed in Patent Document 2, for example.

[0005] In the above-mentioned ballpoint pen refill, the front end of the ink reservoir tube into which the ballpoint pen tip is fitted must have a certain thickness in order to ensure its strength. Therefore, the ballpoint pen refills disclosed in the above-mentioned Patent Documents 1 and 2 have a certain thickness, which poses a practical problem in that they cannot secure a sufficient amount of ink storage.

[0006] Thus, as an example of a writing instrument refill designed to ensure a sufficient amount of ink storage, there can be mentioned a ballpoint pen refill as disclosed in Patent Document 3. However, the ballpoint pen refill shown in Patent Document 3 uses an ink containing tube whose cross section perpendicular to the axis is sector-shaped, so that an ink containing tube of a size corresponding to the barrel must be individually prepared for each model, which poses an issue in terms of versatility.

[0007] Furthermore, it is difficult to make an ink containing tube, whose cross section perpendicular to the axis is sector-shaped, flexible, and when this is used in a multi-function writing instrument that houses multiple refills within the barrel, technical problems arise in that smooth operation cannot be expected, such as the difficulty of alternately moving the ballpoint tip in and out of the opening at the tip of the barrel. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] JP 2002-59682 A [Patent Document 2] JP 2006-175745 A [Patent Document 3] Japanese Patent Application Publication No. 11-321178 Summary of the Invention [Problem to be solved by the invention]

[0009] This invention has been made in response to the above-mentioned problems with conventional writing instrument refills, and aims to provide a manufacturing method for a writing instrument refill that can ensure a necessary and sufficient ink storage volume without expanding the outer diameter dimension of the ink containing tube, and that can sufficiently ensure the mechanical strength of the end of the ink containing tube to which the writing tip (ballpoint pen tip) is attached.

[0010] In addition, an object of the present invention is to provide a refill and a writing instrument that, even when used in a multi-function writing instrument that houses multiple writing instrument refills within a barrel, can take advantage of their flexibility and allow each writing tip to smoothly appear and disappear alternately from the tip opening of the barrel. [Means for solving the problem]

[0011] The manufacturing method of a refill for a writing instrument according to the present invention, which has been made to solve the above-mentioned problems, is a manufacturing method of a refill for a writing instrument comprising an ink reservoir tube formed of a resin material in a straight cylindrical shape, and a writing tip attached to an end of the ink reservoir tube, wherein a press-fit portion is formed at the end of the ink reservoir tube, the press-fit portion being thickened toward the inner circumferential surface and having an opening hole penetrating in the axial direction at the center thereof, and the writing tip or a joint member supporting the writing tip is press-fitted and attached to one end of the press-fit portion, ,stomach The end of the ink receiving tube is heated and melted by the welding tip. A gas inlet hole is formed in the center of the welding tip. is formed. In this case, the ink containing tube Pressure The wall thickness of the inlet is 0.5mm or more, and the pipe thickness is 0.25mm to 0.45mm. Tosu It is desirable to do so.

[0012] Preferably, the press-fitting portion is provided at both ends of the ink reservoir tube. Approximately the same dimensions Formed 。 Effect of the Invention

[0013] According to the above-mentioned method for manufacturing a refill for a writing instrument, a press-fit portion is formed at the end of the cylindrical ink reservoir tube, the press-fit portion being thickened toward the inner circumferential surface and having an opening hole penetrating the axial direction at the center. Therefore, a writing tip (ballpoint pen tip) can be attached by utilizing the press-fit portion formed by this opening hole. In this case, since the press-fit portion is formed thicker toward the inner peripheral surface, it is possible to ensure sufficient mechanical strength for the attachment portion of the writing tip, and to make the thickness of the ink reservoir tube excluding the press-fit portion relatively thin. This makes it possible to provide a writing instrument refill that can ensure a sufficient amount of ink storage.

[0014] Furthermore, with the writing instrument refill having the above-described configuration, the above-described effects can be obtained without expanding the outer diameter or overall length of the ink containing tube, so that even when the writing instrument refill is housed within the barrel, the barrel diameter does not increase, and the refill can be particularly suitably used for multi-function writing instruments in which each writing tip can be operated to alternately appear and disappear from the tip opening of the barrel. [Brief description of the drawings]

[0015] [Figure 1] 1 is an external view showing a first embodiment of a refill used in a writing instrument according to the present invention. FIG. [Diagram 2] 2 is a central cross-sectional view of the writing instrument refill shown in FIG. 1. [Diagram 3] 2 is an enlarged central cross-sectional view showing a single structure of an ink containing tube used in the refill shown in FIG. 1. [Figure 4] 1A is a schematic diagram showing a first means for forming a thick-walled press-fit portion at the end of the ink containing tube. FIG. [Diagram 5] FIG. 13 is a schematic diagram showing the second means. [Figure 6] FIG. 11 is a schematic diagram showing the third means. [Figure 7] FIG. 11 is a schematic diagram showing the fourth means. [Figure 8] FIG. 2 is an external view showing a second embodiment of a refill used in the writing instrument according to the present invention. [Figure 9] 9 is a central cross-sectional view of the writing instrument refill shown in FIG. 8. [Figure 10] 9 is an enlarged central cross-sectional view showing a single structure of an ink containing tube used in the refill shown in FIG. 8. [Figure 11] FIG. 2 is an external view showing the state in which the writing instrument refill is used in a multi-function writing instrument. [Figure 12] 12 is a central cross-sectional view of the multi-function writing instrument shown in FIG. [Figure 13] FIG. 2 is an enlarged external view showing a combination of a slider and a refill for a writing instrument provided in a multi-function writing instrument. [Figure 14] FIG. 1 is a central cross-sectional view showing an example of a conventional writing instrument refill. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] The writing instrument refill and writing instrument according to the present invention will be described based on the embodiments shown in the drawings, which take as an example a ballpoint pen refill and a multi-function writing instrument in which a plurality of ballpoint pen refills are housed in a barrel. First, Figures 1 to 3 show a first form of ballpoint pen refill, in which a coupling member 3 with a ballpoint pen tip 2 already attached thereto is press-fitted to one end (front end) of an ink containing tube 1 made of a resin material such as polypropylene. The ink containing tube 1 is formed in a cylindrical shape with a flush surface along the axial direction, and as shown in an enlarged view of both ends in Figure 3, first and second press-fit portions 1a are formed at both ends of the ink containing tube 1, which are thickened toward the inner circumferential surface.

[0017] The first and second press-fit portions 1a are configured with an opening hole that penetrates the thick-walled central portion along the axial direction, and the coupling member 3 is pressed into the thick-walled first press-fit portion 1a, and the ballpoint pen tip 2 is attached to the front end of the ink containing tube 1 via this coupling member 3. Also, the ballpoint pen tip 2 may be directly press-fitted into the ink containing tube 1 without using an intermediate member such as the joint member 3 at the front end of the ink containing tube 1. In the example shown in FIGS. 1 to 3, the thick press-fit portions 1a formed at both ends of the ink containing tube 1 are integrally formed with the ink containing tube 1, respectively.

[0018] In the ballpoint pen refill shown in this example, the press-fit portion 1a formed at the end of the ink reservoir 1 is thickened toward the inner circumferential surface, so that it is possible to ensure sufficient mechanical strength of the attachment portion of the ballpoint pen tip 2. The thickness of the press-fit portion 1a is preferably 0.5 mm or more. Therefore, compared to the conventional example shown in Fig. 14, the ink containing tube 1 excluding the press-fit portion 1a can have a relatively thin tube thickness. The tube thickness can be less than 0.5 mm, which is thinner than the wall thickness of the press-fit portion 1a. In particular, taking into consideration the moldability of the press-fit portion 1a, etc., a thickness of 0.25 mm to 0.45 mm is preferable. This makes it possible to provide a ballpoint pen refill that can secure a sufficient amount of ink storage without expanding the outer diameter dimension of the ink containing tube 1. The axial length A of the press-fit portion 1a is preferably 1.5 mm to 5 mm in order to ensure an appropriate press-fitting force and an appropriate amount of ink, and the strength of the attachment portion with the ballpoint pen tip 2 or the joint member 3 is preferably 9.8 N or more. The strength of the attachment portion is measured using a commercially available push-pull gauge of 500 N (a force gauge manufactured by Imada Co., Ltd.) to measure the force required to pull the ballpoint pen tip 2 or the joint member 3 attached to the press-fit portion 1a out of the ink reservoir 1. The outer diameter of the ink reservoir 1 is preferably 2.8 mm to 3.5 mm, so that the ink reservoir 1 can be used without feeling any difference from conventional writing implements.

[0019] Figure 4 shows a first means for forming the press-fit portion 1a at the end of the ink containing tube 1. The example of forming the press-fit portion 1a shown in Figure 4 is called an impulse welder (IPW), and uses a welding tip 11 that heats and melts the end of the ink containing tube 1. That is, the welding tip 11 is formed with an annular recess 11a into which the end of the ink containing tube 1 can be inserted, and a heating element (not shown) is attached to the welding tip 11 so that it is heated by Joule heat, for example. Also, a gas introduction hole 11b is formed in the center of the welding tip 11, and the gas introduction hole 11b can be used to introduce a cooling gas (air).

[0020] Fig. 4(A) shows the state where the end of the ink containing tube 1 is inserted into the annular recess 11a of the welding tip 11. In this state, the welding tip 11 is heated, and the end of the ink containing tube 1 made of a resin material is softened and melted. As the end of the ink containing tube 1 softens and melts, a press-fit portion 1a that is thicker toward the inner circumferential surface is formed at the end of the ink containing tube 1 along the annular recess 11a of the welding tip 11, as shown in Fig. 4(B).

[0021] In this state, the heating of the welding tip 11 is stopped and cooling air is sent into the through hole 11b in the direction indicated by the arrow, whereby the end of the ink containing tube 1 is cooled and a thick-walled press-fit portion 1a is formed at the end, and the end is released from the welding tip 11. If necessary, the other end of the ink containing tube 1 can be treated in the same manner to obtain an ink containing tube 1 having a thick press-fit portion 1a integrally formed at each end.

[0022] Figure 5 shows a second means for forming the aforementioned press-fit portion 1a at the end of the ink containing tube 1. In the example shown in Figure 5, press-fit portions 1a formed of separate members are attached to both ends of the ink containing tube 1, and a means for attaching them using an adhesive can be used. Furthermore, by attaching the press-fit portion 1a to both ends of the ink containing tube 1 by thermal welding, the thick press-fit portion 1a can be formed substantially integrally with the ink containing tube 1.

[0023] Fig. 6 shows a third means for forming the press-fit portion 1a at the end of the ink containing tube 1. The example shown in Fig. 6 shows an example of metal molding using upper and lower split dies 13, 14 and first and second core pins 15, 16. That is, the ink containing tube 1 is formed by the upper and lower split dies 13, 14 and the first core pin 15, and the thick-walled press-fit portion 1a is formed by the upper and lower split dies 13, 14 and the second core pin 16. In this case, the press-fit portion 1a can be molded integrally with the ink containing tube 1 at the same time. In the example shown in FIG. 6, the press-fit portion 1a is formed only on one end side of the ink containing tube 1.

[0024] Figure 7 shows a fourth means for forming the press-fit portion 1a at the end of the ink containing tube 1. The example shown in Figure 7 uses a so-called three-dimensional printer, and the ink containing tube 1 and the press-fit portion 1a can be molded integrally at the same time by stacking layers of material (filament) discharged from a reciprocating printer head 18.

[0025] Figures 8 to 10 show a second embodiment of a refill for a writing instrument (ballpoint pen refill). In the ballpoint pen refill shown in Figures 8 to 10, the ballpoint pen tip 2 is directly press-fitted into the front end of the ink containing tube 1 without an intermediate member. The ink containing tube 1 in this second embodiment is also formed into a cylindrical shape flush with the axial direction, and as shown in Figure 10, first and second press-fit portions 1a are formed at both ends of the ink containing tube 1 by openings that are thicker toward the inner circumferential surface and penetrate in the axial direction.

[0026] In addition, in this second embodiment, the press-fit portion 1a at the front end of the ink containing tube 1 to which the ballpoint pen tip 2 is attached is further formed with an abutment portion 1b on the central side of the ink containing tube 1, the abutment portion 1b having an axial hole 1c with a smaller diameter than the opening hole constituting the press-fit portion 1a. When a ballpoint pen tip 2 as shown in Figure 9 is pressed into the press-fitting portion 1a, it is not necessary to form a step on the outer peripheral surface of the ballpoint pen tip 2 to abut against the end of the ink containing tube 1; therefore, the tubular ballpoint pen tip 2 can be pressed into the press-fitting portion 1a, and the abutment portion 1b serves as a positioning stopper by the abutment of the rear end of the ballpoint pen tip 2.

[0027] In addition, for the ink containing tube 1 used in the ballpoint pen refill shown in Figures 8 to 10, the press-fit portion 1a and the abutment portion 1b can be formed at the end of the ink containing tube 1 by appropriately adopting the means shown in Figures 4 to 7 already described.

[0028] 11 to 13 show an example in which the writing instrument refill (ballpoint pen refill) is used in a multiple-color ballpoint pen. This compound multi-color ballpoint pen has an outer shell formed by a front shaft 21 and a rear shaft 22, and the front shaft 21 has a tip portion tapered into a cone shape and opens to a tip opening 23. The writing tip (ballpoint pen tip) 2 of the ballpoint pen refill is selectively extended from the tip opening 23.

[0029] A plurality of guide slits 24 (four in this example) are formed along the axial direction at the rear end of the rear axle 22. An operating portion 25a formed on a slider 25 is disposed in each guide slit 24 so as to protrude outward from the rear axle and be slidable in the axial direction. An inner cylindrical member 27 is housed within the rear axle 22 in which the guide slits 24 are formed, and an engaging surface 27a for engaging the slider 25 in an advanced state is formed on the inner cylindrical member 27. In addition, the rear end of the inner cylindrical member 27 is formed with a slightly narrower diameter and protrudes from the rear end of the rear barrel 22. A cap member 29 having a clip 28 formed integrally therewith is fitted and attached so as to cover the protruding portion of the inner cylindrical member 27.

[0030] As shown in Fig. 13, the front end of the slider 25 is attached to the thick second press-fit portion 1a (see Figs. 2 and 3) formed at the rear end of the ink containing tube 1, and a return spring (not shown) is disposed so as to surround each ink containing tube 1 and the slider 25. As a result, each ink containing tube 1 and slider 25 is disposed in a state in which it is biased toward the rear in the axial direction of the compound multi-color ballpoint pen.

[0031] In this state, when any one of the sliders 25 is moved forward by using the operating portion 25a, the operating portion 25a of this slider 25 moves forward along the groove formed in the inner tube member 27 and drops in the axial direction. As a result, the rear end locking portion 25b of the slider 25 is locked to the locking surface 27a formed in the inner tube member 27. At this time, the refill attached to the slider 25 is appropriately curved due to its own flexibility, and the ballpoint pen tip 2 at its tip is held in a state where it protrudes from the tip opening 23.

[0032] In this state, when the second slider 25 is moved forward, the unlocking cam 25c formed on the second slider 25 comes into contact with the pressed projection 25b of the first slider 25 that is already locked in the forward state, and pushes the rear end locking portion 25b of the first slider 25 outward. This releases the first slider 25 from its locked state. As a result, the first slider 25 moves back due to the action of the return spring described above, and the rear end locking portion 25b of the second slider 25 locks onto the locking surface 27a formed on the inner tube member 27, thereby replacing the ballpoint pen tip 2 extended from the tip opening 23.

[0033] According to the manufacturing method of the writing instrument refill of the present invention, as already explained, the thickness of the ink containing tube 1 can be made relatively thin except for the press-fit portion 1a at the end, so that it is possible to provide a writing instrument refill that can secure a sufficient amount of ink storage without expanding the outer diameter dimension of the ink containing tube. Furthermore, by making the thickness of the ink containing tube relatively thin, the entire writing instrument refill can be made flexible, and when this is used in the multi-function writing instrument described above, the flexibility can be utilized to ensure smooth protruding and retracting movement of each writing tip.

[0034] In the above description, a ballpoint pen refill has been given as an embodiment, but the present invention can also be applied to writing instruments equipped with writing tips other than ballpoint pen tips, and the same effects as those described above can be obtained. [Explanation of symbols]

[0035] 1 Ink reservoir tube 1a Press-fit portion (opening hole) 1b Contact part 1c shaft hole 2 Writing tip (ballpoint pen tip) 3 Joint members 11 Welding tip 11a Annular recess 11b Gas inlet 13 Upper split type 14 Lower split type 15 First core pin 16 Second core pin 18 Printer Head 21 Front axle 22 rear axle 24 Guide slit 25 Slider 25a Operation section

Claims

[Claim 1] A method for manufacturing a refill for a writing instrument, comprising: an ink reservoir tube formed of a resin material into a straight cylindrical shape; and a writing tip attached to an end of the ink reservoir tube, the method comprising the steps of: a press-fit portion is formed at an end of the ink reservoir tube, the press-fit portion being thickened toward an inner peripheral surface and having an opening hole penetrating in an axial direction at a center thereof, and the writing tip or a joint member supporting the writing tip is press-fitted and attached to one end of the press-fit portion, A manufacturing method for a refill for a writing instrument, characterized in that the press-in portion is formed by heating and melting the end of the ink containing tube with a welding tip, and a gas introduction hole is formed in the center of the welding tip.

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