JP2862196B2 - Manufacturing method of writing implements - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a writing instrument in which a valve ball for preventing writing liquid from flowing back is accommodated in a cylinder.

[0002]

2. Description of the Related Art Some conventional writing implements have an ink backflow prevention mechanism for preventing the ink (writing liquid) inside from flowing back to the tail end when the pen tip is directed upward. .

For example, Japanese Utility Model Publication No. 4-52067 discloses that
A projecting ridge extending in the axial direction is formed in the ballpoint pen, a ball seat is formed at a position on the tail end side thereof, and a valve chamber is formed between the seat and the projecting ridge. Shows a valve ball movably accommodated therein. According to such a writing instrument, at the time of writing, when the pen tip is directed downward, the valve ball abuts on the ridge, thereby preventing the valve ball from coming off to the distal end side. Ink flows out to the pen tip through between the ridges, and when the pen tip is turned up other than when writing, the valve ball sits on the receiving seat to block the flow of ink, Backflow of the ink to the tail end side is prevented.

[0004]

The writing instrument has a structure in which a valve ball is confined in a valve chamber, and the valve chamber is formed in a mouthpiece integrally formed of an elastically deformable material such as synthetic resin. Therefore, in order to obtain this writing instrument, it is necessary to push a valve ball (valve ball) from the inside of the ridge with elastic deformation of the mouth plug into the valve chamber. However, such a manufacturing method has the following problems to be solved.

[0005] When the valve ball is pushed into the valve chamber, the resistance is large, and it is difficult to press-fit the valve ball.

[0006] At the time of press-fitting of the valve ball, the ridge may cause plastic deformation (generally, an increase in diameter), and the retaining of the valve ball may be impaired. Further, in a writing instrument such as a ball-point pen which is applied to a centrifugal separator in order to push out ink to a nib before shipping, at the time of the centrifugal separation, the valve ball bites into the plastically deformed ridge and does not come off. Therefore, the valve may not function. Such biting may also occur due to an impact or the like when the writing implement is inadvertently dropped.

The present invention has been made in view of the above circumstances, and has as its object to provide a method capable of easily and conveniently manufacturing a writing instrument having a valve chamber having a simple structure.

[0008]

According to the present invention, a valve chamber is provided in the middle of a cylindrical body made of an elastically deformable material and having a writing liquid flow passage formed therein, and a valve ball for preventing backflow is provided in the valve chamber. In the method for manufacturing a writing instrument, which is accommodated and has a regulating portion that regulates the movement of the valve ball toward the distal end at the distal end portion of the valve chamber, the water forming a solid phase at normal temperature on the surface of the valve ball. After attaching an insoluble lubricant (eg, oleic acid amide or stearic acid amide), the valve ball is pressed into the valve chamber from the inside of the regulating portion.

As a method for adhering the lubricant to the surface of the valve bulb, a method in which the lubricant is dissolved in a solvent other than water, the solution is applied to the surface of the valve bulb, and then dried.

[0010] Here, "normal temperature" means a temperature at which a writing instrument is normally used, that is, a temperature of less than about 40 ° C.

[0011]

According to the above method, a lubricant such as oleamide or stearamide is previously adhered to the surface of the valve ball, so that the valve ball is pressed into the valve chamber from inside the regulating portion. Resistance is reduced, and deformation of the regulating portion is also prevented. In addition, since the above-mentioned lubricant is solid at normal temperature and does not dissolve in water, it does not affect the writing liquid at the time of use.

Further, even if the lubricant is solid at room temperature, it is dissolved in a solvent other than water, and the solution is applied to the surface of the valve ball and dried, so that the lubricant is removed from the valve ball. Good adhesion to the surface.

[0013]

7 and 8 show an example of a writing implement manufactured by the method of the present invention. Although a ballpoint pen is shown in this embodiment, the present invention can be applied to the manufacture of various writing tools that require prevention of backflow of a writing liquid.

The illustrated ball-point pen has an outer cylinder 10, and an inner cylinder 12 is inserted into the outer cylinder 10, and ink (writing liquid) is stored in the inner cylinder 12. Both cylinders 10, 12
Is closed with a tail plug (not shown).
A front tube (tubular body) 14 made of an elastically deformable material such as a synthetic resin is attached to the tip of the.

The outer peripheral surface of the front cylinder 14 is composed of a small-diameter cylindrical portion 16, a large-diameter cylindrical portion 17, and a tapered conical portion 18 in this order from the tail end side. The small-diameter cylindrical portion 16 and the large-diameter cylindrical portion 17 are fitted into the distal end portions of the inner cylinder 12 and the outer cylinder 10, respectively, until the step portion 20 between the outer cylinder 10 and the step portion 18 contacts the distal end surface of the outer cylinder 10. .

As shown in FIG. 1, a large-diameter hole 24 and a small-diameter hole 26 are formed in the center portion of the front cylinder 14 in the axial direction continuously from the front end side. A valve ball 22 made of a steel ball or the like is accommodated. Here, the large-diameter hole 24 has a diameter D larger than the diameter of the valve bulb 22,
The small diameter hole 26 has a diameter d smaller than the diameter of the valve bulb 22.

In the portion of the large-diameter hole 24 adjacent to the small-diameter hole 26, raised portions 28 are formed at four locations in the circumferential direction. The surface of each raised portion 28 (that is, the inner surface of the front cylinder 14)
Are flat surfaces, and the portions surrounded by the ridges 28 are shown in FIG.
The valve chamber 31 has a substantially square cross section as shown in FIG.
The cross-sectional shape of the valve chamber 31 has a substantially square shape substantially circumscribing the valve ball 22, more specifically, a shape in which the dimension a of each of the four sides is slightly larger than the diameter of the valve ball 22 and the four vertexes are arcs. Is set.

Further, the tip side portion of each raised portion 28 (FIG. 1)
In the upper part), a ridge (restriction part) 30 protruding further inward than the raised part 28 is formed. Each ridge 3
0 has a linear end parallel to the surface of the raised portion 28 (that is, parallel to each side of the substantially polygonal cross section of the valve chamber 31);
The dimension b of a substantially square figure extending in the same direction and surrounded by these ridges 30, that is, the dimension b of one side of the figure shown in the center of FIG. 2 is set to be smaller than the diameter of the valve bulb 22. I have. Therefore, the bulb 22 is provided with these ridges 3
By contact with 0, it cannot move further to the tip side.

On the other hand, the valve chamber 31 surrounded by each raised portion 28
A step is formed at the boundary between the ink passage and the ink passage formed by the small-diameter hole 26. The step is a seal portion 27 having an inwardly convex spherical surface over the entire circumference as shown in FIG. . The valve ball 22 is confined in a valve chamber 31 formed between the seal portion 27 and the ridge 30, and is movable in the valve chamber 31 in the axial direction. The ball 22 is in line contact with the seal portion 27 over the entire circumference (point contact in each cross section), so that the flow of ink is reliably prevented at this portion.

In FIGS. 7 and 8, reference numeral 32 denotes a pen tip, the tail end side shaft 34 of which is fitted to the tip end of the large diameter hole 24.

In this writing instrument, first, as shown in FIG. 7, when the tip of the writing instrument is turned downward, the valve chamber 3 is closed.
The valve ball 22 in 1 falls toward the tip portion, and stands still while hitting the ridge 30. In this state, gaps 29 are formed at four corners in the valve chamber 31 due to the difference between the cross-sectional shape (substantially polygonal shape) and the planar shape (circle) of the valve ball 22 (see FIG. 3). Gaps 29 are also formed at the four corners due to the difference in shape between the enclosed square and the bulb 22 (see FIG. 2).
Accordingly, ink is reliably supplied from the tail end side to the pen tip through these gaps 29.

On the other hand, when the tip of the writing instrument is turned upward, the valve ball 22 in the valve chamber 31 falls toward the tail end, and rests on the seal 27. In this state, since the seal portion 27 and the valve ball 22 are in contact with each other over the entire circumference, the flow of the ink is reliably prevented at this portion, and the backflow of the writing liquid from the front end side to the tail end side is prevented. Becomes

Next, a method of manufacturing the writing instrument will be described below. 1) The front cylinder 14 is integrally formed into the above-mentioned shape using an elastically deformable synthetic resin such as polypropylene. 2) A lubricant is attached to the surface of the valve bulb 22. As the lubricant, use is made of a lubricant which is solid at room temperature and insoluble in water, such as oleic amide and stearic amide described later. As a method of attaching the lubricant, the lubricant may be once dissolved in a solvent other than water (for example, an alcohol solvent), and the solution may be applied to the surface of the valve bulb 22 and then dried. 3) The valve ball 22 is inserted into the front cylinder 14 from the large-diameter hole 24 side, and is further expanded from the inside of the ridge 30 into the valve chamber 31 behind the ridge 30 while elastically expanding the diameter. Press in. Thereby, the valve ball 22 is in a state of being confined in the valve chamber 31. 4) Assemble the parts including the front tube 14 to complete the writing implement.

As described above, in this method, since the front cylinder 14 having the valve chamber 31 is integrally formed of a synthetic resin, the structure is simplified as compared with, for example, assembling the valve chamber with a plurality of parts. be able to. In addition, after the front cylinder 14 is integrally formed, before the valve ball 22 is inserted therein, the valve ball 2
Since the lubricant is attached to the surface of the valve ball 2, the valve ball 2
2 can be reduced, and the workability can be improved. Further, with the decrease in the resistance, it is possible to prevent the plastic deformation of the ridge 30 when the valve ball 22 is press-fitted, and to prevent the valve function in the valve chamber 31 from being impaired due to such deformation. You can also.

Further, since the above-mentioned lubricant is a water-insoluble one which forms a solid phase at normal temperature, it does not adversely affect the writing liquid when a writing instrument is used. That is,
Various writing liquids (for example, aqueous inks) conventionally used can be used without inconvenience.

* Experimental data Table 1 below shows the results of investigations on the suitability of the lubricant used in the present invention with respect to lubricants such as fatty acid esters, fatty acid amides and mineral oils. In addition, in the same table, the column of "bulb bite" indicates the number of cases where the valve ball 22 bites into the ridge 30 when the writing implement was assembled and then centrifuged.

[0027]

[Table 1]

From the table, it is found that oleic acid amide and stearic acid amide are particularly excellent in ink repellency and stickiness, and can reliably prevent bite of a bulb, and are suitable as a lubricant used in the present invention. I can understand.

In the present invention, regardless of the specific structure of the valve chamber, the present invention is applied to the production of various types of devices having a restricting portion for preventing the valve ball from coming off and in which the valve ball is confined. be able to.

[0030]

As described above, according to the present invention, a cylinder having a valve chamber is formed from an elastically deformable material, and a lubricant is applied to the surface of the valve ball before the valve ball is pressed into the valve chamber. Since it is made to adhere, the writing instrument with a simple check valve with a non-return valve has a simple structure while reducing the resistance of the press-fitting and preventing the plastic deformation of the regulating portion of the cylindrical body and the loss of the valve function in the valve chamber due to the press-fitting. Can be easily manufactured. Moreover,
Since a water-insoluble lubricant that forms a solid phase at room temperature is used as the lubricant, the lubricant does not adversely affect the writing liquid. In particular, by using oleic amide or stearic amide as the lubricant, an excellent lubricating effect can be obtained, and the adverse effect of the lubricant on the writing liquid can be effectively prevented.

Further, by dissolving the above-mentioned lubricant in a solvent other than water, applying this solution to the surface of the above-mentioned valve ball and drying it, even a water-insoluble lubricant can easily adhere to the surface of the above-mentioned valve ball. There is an effect that can be made.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a front tube constituting a writing instrument according to an embodiment of the present invention.

FIG. 2 is a sectional view taken along line AA of FIG.

FIG. 3 is a sectional view taken along line BB of FIG. 1;

FIG. 4 is a transverse sectional view showing a state where a valve ball is removed in FIG. 2;

FIG. 5 is a transverse sectional view showing a state where a valve ball is removed in FIG. 3;

FIG. 6 is an enlarged sectional view of a seal portion in the front cylinder.

FIG. 7 is a longitudinal sectional view showing a state in which a pen tip is directed downward in the writing instrument.

FIG. 8 is a longitudinal sectional view showing a state in which a pen tip is directed upward in the writing instrument.

[Explanation of symbols]

 14 Front cylinder (cylindrical body) 22 Valve ball 30 Ridge (Regulator) 31 Valve chamber

Claims (3)

(57) [Claims] A valve chamber is provided in the middle of a cylindrical body made of an elastically deformable material and having a writing fluid flow passage formed therein. A valve ball for preventing backflow is housed in the valve chamber, and a valve chamber for the valve chamber is provided. In the method for manufacturing a writing instrument, in which a regulating portion for regulating the movement of the valve ball toward the distal end is formed at the distal end portion, a water-insoluble lubricant that forms a solid phase at normal temperature is attached to the surface of the valve ball. Thereafter, the valve ball is pressed into the valve chamber from the inside of the regulating portion. 2. The method for manufacturing a writing instrument according to claim 1, wherein the lubricant is dissolved in a solvent other than water, and this solution is applied to the surface of the valve ball and dried. A method for manufacturing a writing instrument, comprising press-fitting. 3. The method for manufacturing a writing instrument according to claim 1, wherein the lubricant is oleic amide or stearic amide.