JP2004299255A - Bottomed tubular body, its molding method and writing utensil utilizing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent an axial deflection due to defective hole/uneven wall thickness from developing by a method wherein a tubular part and a bottom part are integrated under an arbitrary combination such as single color base or two color base material. <P>SOLUTION: In this bottomed tubular body, the body tubular part and an the bottom part of the bottomed tubular body are respectively integrated by a two color molded body made of one and the same kind or different kinds of resin. The molding method of the bottomed tubular body comprised a process for obtaining either one of the tubular part and the bottom part by injection-molding molten resin in a primary mold cavity and a process for molding under the condition that the resultant molded part being held in the final mold cavity the other part by injection-molding one and the same kind or different kinds of resin in order to simultaneously integrate the molded part and the other part into a finally shaped two color molded body. As for a writing utensil, the bottomed tubular body is employed as an ink housing tube for filling writing ink inside and a tip coating part is equipped at the open side of the bottomed tubular body. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a bottomed cylindrical body, a molding method therefor, and a writing instrument using the same, and more particularly to a bottomed cylindrical body having a long axis and preventing occurrence of shaft bending and hole opening failure due to uneven thickness. The present invention relates to a molding method and a writing instrument using the same.
[0002]
[Prior art]
A bottomed cylindrical body having a certain length, such as a shaft cylinder such as a ballpoint pen, an ink storage tube, a mechanical pencil core tank, a cap, a cosmetic container, a test tube, etc., usually has a rod-shaped core pin and a metal covering the same. The cavity between the inner wall of the mold cavity and the molten resin is injection-filled and integrally molded. In this case, since the rod-shaped core pin has one end fixed to the cavity wall and protrudes into the cavity, the rod-shaped core pin is protruded when the high-pressure, high-speed molten resin flows into the cavity during injection molding. Since the tip of the core pin at the end part sways and is unbalanced, a problem that the molten resin is non-uniformly charged occurs, and a large or small thickness uneven portion is easily generated particularly in the wall thickness of the molded long shaft cylindrical body.
[0003]
Once the deviation occurs, more of the gas flows into the thicker wall with the smaller resistance. For this reason, the inclination of the core pin becomes larger. Since the thickness of the side wall portion of the molded product has a large or small uneven thickness, there is a problem that the shaft is bent due to a difference in shrinkage during cooling. There is also a problem that the inner wall surface of the cavity is damaged by the core pin. Further, in recent years, a shaft cylinder such as an ink storage tube of a writing instrument or the like has become longer and thinner, and the above-mentioned problem has been increasingly noticeable.
[0004]
In order to solve the above problems, the following prior arts have been proposed.
For example, the resin flowed in a state where one end of an elongated core pin was supported in a single mold cavity and the other end was held at the bottom of the cavity so as not to be tilted, and the resin flowed back in a state where the core pin was held upright. After detecting the above, a method of forming a bottomed cylindrical body by displacing the core pin so that the gap between the cavity and the core pin becomes the same has been proposed (see Patent Document 1). This prevents the core pin from being tilted when the resin flows, so that the thickness of the molded product does not vary in thickness, but the detection means and the displacement means are required, and the mold structure becomes complicated, and There is a problem that it is difficult to control the timing of the displacement of the core pin in order to ensure a sufficient bottom wall thickness.
[0005]
Also, a means is provided in which a holding pin for pressing the tip of the core pin in the cavity through a resilient member such as a coil spring is urged from the bottom of the core pin, and the holding pin is retracted before the resin is filled in the cavity. It has also been proposed to provide the molded product with a uniform thickness by providing the same (see Patent Document 2). Further, the ejector pin is biased and supported by a force (a resilient member such as a coil spring) smaller than the injection pressure of the molding material in a direction in which the tip of the ejector pin engages with the tip of the core pin. It has also been proposed that a resin flow into a gap generated by displacing a pin to form a thickness of a bottom portion (see Patent Document 3).
[0006]
[Patent Document 1]
JP-A-8-99337 [Patent Document 2]
JP-A-8-11171 [Patent Document 3]
Japanese Utility Model Publication No. 60-138725
In the above-described method for forming a bottomed cylindrical body, in particular, the formation of a gap corresponding to the thickness of the bottom portion is performed by the balance between the pressing force of the repelling member and the resin injection pressure. There is a disadvantage that it is difficult to form a sufficient gap due to variations in injection pressure and injection pressure. For this reason, the inflow of the molten resin is insufficient, the thickness of the bottom of the bottomed cylindrical body is reduced, and there is a risk that a defective perforation occurs and the stored ink or the like leaks from the bottom. In addition, since each of the above-mentioned molding methods is an injection molded product from a single-color molten resin with one cavity, there is a disadvantage that only a single-colored bottomed cylinder can be obtained.
[0008]
[Problems to be solved by the invention]
From the current situation, the problem of the present invention is that the main body cylindrical portion (side wall portion) and the bottom portion are integrated with any combination of monochromatic type, two-color type, or transparent type or translucent type and opaque type. It is an object of the present invention to provide a bottomed cylindrical body that prevents shaft bending due to poor opening and uneven thickness, a molding method thereof, and a writing instrument using the same.
[0009]
[Means for Solving the Problems]
As a result of various studies to solve the above problems, the present inventors have found that the problem can be solved by integrating the main body forming the bottomed cylindrical body and the bottom by two-color injection molding, and completed the present invention.
That is, the bottomed tubular body of the present invention is characterized in that the main body tubular portion and the bottom portion forming the bottomed tubular body are integrated by a two-color molded body made of the same or different resin.
According to the present invention, each of the main body tubular portion and the bottom portion of the bottomed tubular body can be selected from any combination such as a single color system, a two-color system, or a transparent system or a translucent system and an opaque system. It is excellent in effect and there is no liquid leakage and shaft bending due to the integration.
[0010]
Here, as a preferred embodiment of the present invention, a bottomed cylindrical body in which a bottom has a rising portion around the periphery, and the rising portion is integrated with at least a lower end portion of the main body cylindrical portion.
In addition, a bottomed cylindrical body in which a rising portion around the bottom is a double wall structure and sandwiches the lower end of the main body cylindrical portion and is integrated with each other.
Further, a bottomed cylindrical body or the like in which the main body cylindrical part is made of a transparent or translucent and the bottom is made of an opaque resin molded body, and a band-shaped rising part around the bottom is integrated so as to cover the longitudinal direction of the main body cylindrical part. Are listed.
[0011]
As a molding method of the present invention, a step of obtaining one of a main body cylindrical portion and a bottom portion forming a bottomed cylindrical body by injection molding of a molten resin into a primary mold cavity; The step of holding the primary molded article, and the same or different molten resin is injected and filled into the remaining voids in the mold cavity of the final molded article, and the other part is simultaneously molded into a two-color molded article of the final shape. And a step of integrating them.
According to such a molding method, for example, when molding the main body cylindrical portion open at both ends by injecting the molten resin into the primary mold cavity, since the rod-shaped core pin or the main body cylindrical portion can be fixed at both ends, the tip or the whole of the rod-shaped core pin tilts. A long-axis cylindrical portion having a uniform thickness and an arbitrary appearance without being dripped or deformed is formed. When the bottom is molded, a two-color molded article having a final shape with excellent dimensional accuracy can be easily molded.
[0012]
Further, in the above-mentioned molding method, of the main body cylindrical portion and the bottom portion forming the bottomed cylindrical body, the main body cylindrical portion is obtained by injection molding of a molten resin into the primary mold cavity, and is obtained in the mold cavity of the final molded product. When holding the main body cylinder obtained by the primary molding, it is desirable that at least a part of the outer peripheral wall of the main body cylinder is brought into contact with the mold cavity of the final molded product.
At the time of molding the final molded product, if there is no gap between the main body cylindrical portion and the mold cavity of the final molded product and there is a gap over the entire circumference, the core pin may swing due to the injection pressure of the resin. However, as described above, the deflection can be prevented by bringing at least a part of the outer peripheral wall of the main body cylindrical portion into contact with the mold cavity of the final molded product.
[0013]
Further, the writing instrument of the present invention has the above-described bottomed cylindrical body as an ink storage tube filled with writing ink therein, and has an ink reservoir on the open side thereof, and a tip application section via an ink guide core. It is a writing implement characterized by doing.
As a preferred embodiment of the writing instrument, the ink storage tube has a band-shaped opaque portion covered with a band-shaped rising portion from the outer peripheral surface of the bottom, and a band-shaped transparent portion or a translucent portion, the rest of which can see through the ink filling state inside. It is a writing implement formed of two colors.
According to the writing instrument of the present invention, there is no danger of ink or the like leaking from the bottom of the ink storage tube, and by selecting an arbitrary combination of a monochromatic system, a dichromatic system, or a transparent system and an opaque system. It is easy to check the ink filling state and has excellent color decoration effect.
[0014]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail.
As the type of the resin for molding the main body cylindrical portion and the bottom portion forming the bottomed cylindrical body of the present invention, the same type that is completely heat-sealed integrally, and a system including the same resin portion that is partially heat-sealed. The material is selected from so-called heat-adhesive elastomers which can be thermally bonded to a resin by introducing a functional group which has an electronic interaction with the coating, and ordinary thermoplastic resins. Further, each selected resin may be any combination of the same color, different colors, transparent or translucent and opaque, and the like. Further, since the main body cylindrical portion and the bottom portion are formed by injection molding using two types of mold cavities, the form in which the two are integrated is arbitrary.
[0015]
Hereinafter, a specific embodiment of a bottomed cylinder of the present invention will be described with reference to the accompanying drawings.
Example 1
FIGS. 1A and 1B are enlarged cross-sectional views near the lower end showing an example of a bottomed cylindrical body of the present invention in which a flat bottom is integrated with the lower end of a main body cylindrical part.
Here, (a) is obtained by integrating the main body cylindrical portion 1 and the flat (disk) -shaped bottom portion 2 as a two-color molded body of the same color or a different color by using the same kind of resin by heat fusion.
(B) is a projection in which a protruding portion 1a bent around the lower end of the main body tubular portion 1 is embedded in a thick flat (disk) -shaped bottom portion 2 and integrated.
[0016]
Example 2
FIGS. 2 (a) and 2 (b) show a bottomed cylindrical body of the present invention, which is a two-color molded body, in which a rising portion 3 around the bottom is integrated with the lower end of the main body cylindrical section. It is an expanded sectional view of a vicinity.
Here, (a) is a thin portion 1 b having a step formed on the outer surface of the lower end portion 1 of the main body cylindrical portion 1, and a rising portion 3 around the bottom portion 2 is integrated.
(B) is a thin portion 1b having a step formed on the inner surface of the lower end portion 1 of the main body cylindrical portion, and a rising portion 3 around the bottom portion is integrated.
[0017]
Example 3
FIGS. 3 (a) and 3 (b) show an example of the present invention, which is a two-color molded body, in which the rising portion around the bottom has a double wall structure and sandwiches and integrates the lower end of the main body cylindrical portion. It is an expanded sectional view near the lower end part which shows. Here, (a) of FIG. 3 shows that the thickness of the lower end portion 1c of the main body cylindrical portion 1 is reduced to a tapered shape and embedded in the rising portion 3 around the bottom portion 2 to form a double wall structure. Things. FIG. 3 (b) is a drawing in which a throttle portion 1d is provided at the lower end portion of the main body cylinder portion 1 by a step, and the lower portion is formed of two rising portions 3a (outside) and 3b (inside) around a bottom portion 2 in height. It is sandwiched and integrated into the rising part of the heavy wall. In this case, the contact area can be increased because the two walls are fitted and integrated with each other, so that the adhesive strength can be increased.
[0018]
Example 4
FIG. 4 shows a two-color molded body, of which the main cylindrical portion 1 is formed together with a part of a long band-shaped rising portion 3a and another short band-shaped rising portion 3c among the rising portions around the bottom portion 2. FIG. 5 is an enlarged cross-sectional view of the entirety showing an example in which the longitudinal direction is covered by a double wall with an inner rising portion 3b.
[0019]
Example 5
An example of the method of forming the bottomed cylinder shown in the fourth embodiment will be described with reference to FIGS.
FIG. 5 is a longitudinal sectional view showing a state in which a primary molded product, which is a main part of a main body cylinder part opened at both ends, is injection-molded in the primary mold cavity. FIG. 6 is a longitudinal sectional view showing the primary molding in the final mold cavity. FIG. 4 is a longitudinal sectional view showing a state in which a product is held by a core pin fixed at one end, and a main portion of a bottom portion and a rising portion are formed and integrated by injection molding of the same or different molten resin.
[0020]
First, in FIG. 5, reference numeral 4 denotes a primary mold cavity forming a main outer peripheral wall of the main body cylindrical portion, which is formed by being surrounded by a plurality of split mold plates 5 and the like. Reference numeral 6 denotes a rod-shaped core pin which forms the inner peripheral wall of the main body cylindrical portion 1 in the cavity 4, one end 7 of which is fixed by being sandwiched between the movable mold plate 8, the fixed plate 9, and the protruding plate 10. 11 is fitted and fixed to the fixed mold plate 12. 13 is a sprue runner hole when the molten resin is injected, and 14 is a gate port. Here, the molten resin is injected from the gate port 14 into the gap formed by the cavity 4 and the rod-shaped core pin 6, but the rod-shaped core pin 6 has both ends 7 and 11 fixed. A primary formed body having a shape and a thickness is easily formed.
[0021]
In FIG. 6, a rod-shaped core pin 6 'for forming an inner peripheral wall and a bottom inner wall of the final molded product has one end in a final mold cavity 4' designed to form an outer peripheral wall of the final molded product. The portion 7 'is fixed in the same manner as in FIG. 5, but the tip 11' is held open in the cavity 4 ', leaving a gap for a predetermined bottom thickness. The core pin 6 ′ may be swung in the radial direction by the injection pressure of the resin, but since the primary outer peripheral wall 18 of the main body cylindrical portion is already formed by the primary side molding and is in contact with the cavity 4 ′, the side wall is There is no danger of holes or the like being formed in the holes. Further, since the bottom has a constant thickness without changing as in Patent Literatures 2 and 3, the bottom can be reliably formed. Here, in the final mold cavity 4 ', molten resin of the same or different type as the primary molded product is injected into the sprue runner hole 13' and the gate port into the remaining space formed by the primary molded product and the rod-shaped core pin 6 '. By being injected from 14 ′, the bottom and the rising portion are formed, and at the same time, the molded product shown in FIG. 4 can be obtained which is integrated with the primary molded product and integrated with the two-color molded product having the final shape. In addition, since the cylindrical portion 1 forms the contact portion 18 that contacts the final mold cavity 4 ', it is possible to reduce the occurrence of uneven thickness or the like due to the deflection of the core pin that occurs during resin injection. In the bottomed cylindrical body taken out of the final mold cavity, a part of the band-shaped rising portion from the bottom enters the space in the longitudinal direction of the main body cylindrical portion, and is covered with the same or different resin as the main body cylindrical portion. It is integrated.
[0022]
Example 6
A writing implement as an example of the use of the bottomed cylindrical body of the present invention will be described with reference to FIG.
In FIG. 7, a part of the elongated band-shaped rising part 3a of the rising part around the bottom part 2 described in FIG. 4 covers the longitudinal direction of the main body cylinder part 1, and the other short band-shaped rising part is formed. The bottomed cylinder integrated with the rising portions 3c and 3b is used as an ink storage tube, and the inside is filled with writing ink such as water-based ink. On the open side, an ink reservoir 15 and ink penetrating therethrough are provided. A tip coating unit 17 is provided via an induction core 16. Here, as described in FIG. 4, the ink storage tube has a plurality of strip-shaped opaque portions covered with a strip-shaped rising portion from the outer peripheral surface of the bottom portion, and a strip-shaped transparent portion whose remainder can see through the ink filling state inside. Or a writing implement formed of two colors of a translucent part. Such a writing instrument can be appropriately used integrally with a cap (not shown) for covering the tip application portion.
[0023]
The ink reservoir 15 is provided with a plate-like body 15d provided on the outer periphery of an ink guide core 16 for guiding the aqueous ink or the like to the tip application section 17, and an ink reservoir provided in front of the plate-like body 15d. 15b for discharging air or ink from the ink storage tube or introducing air or ink into the ink storage tube, and a plate connected to the air replacement hole 15a. And a longitudinal groove 15c formed in the axial direction so as to cut out the body 15d. The ink that is about to leak to the outside due to the expansion of the air inside the ink storage tube is formed between the plate-like members 15d of the ink reservoir via the air replacement holes 15a and the vertical grooves 15c. It is retained in the gap by capillary action. In addition, the ink reservoir 15 is not limited to the one using a plate-like body as described above, and for example, a sponge-like one can also be used. The structure of the coating unit 17 attached to the tip of the ink storage tube may be any type of coating, such as a tapered tip made by bundling a large number of fibers, or a ballpoint pen type consisting of a spherical ball and a chip holder holding it. Tools, etc., but are not particularly limited.
[0024]
【The invention's effect】
As described above, the bottomed cylindrical body of the present invention provides a color decoration effect by selecting any combination of a single-color system, a two-color system, or a transparent system and an opaque system for the main body cylindrical unit and the bottom unit. Is also excellent.
Further, in the method of forming a bottomed cylindrical body and a bottom portion of the present invention, a long-axis cylindrical portion having an arbitrary appearance state having a uniform thickness and a high dimensional accuracy is formed as compared with the conventional molding method.
Furthermore, the use of the bottomed cylindrical body of the present invention as a writing instrument has no danger of ink or the like leaking from the bottom of the ink storage tube, and can be any single-color or two-color type, or any type such as a transparent type and an opaque type. By selecting a combination, it is easy to check the ink filling state and the color decoration effect is excellent.
[Brief description of the drawings]
FIG. 1 is an enlarged cross-sectional view of the vicinity of a lower end portion composed of a combination of a tubular portion and a flat plate bottom as an example of a bottomed tubular body of the present invention;
(A) is one in which the lower end of the cylindrical portion is fused and integrated with the bottom of the flat plate.
In (b), the lower end of the cylindrical portion is bent and embedded in the bottom of the flat plate to be integrated.
FIG. 2 is an enlarged cross-sectional view of the vicinity of a lower end portion formed by a combination of a cylindrical portion and a rising portion around a bottom portion, as another example of the bottomed cylindrical body of the present invention;
(A) is a structure in which a thin portion having a step is provided on the outer surface of the lower end of the cylindrical portion, and a rising portion around the bottom is integrated.
(B) has a stepped thin portion provided on the inner surface of the lower end of the cylindrical portion, and a rising portion around the bottom is integrated.
FIG. 3 is an enlarged cross-sectional view of the vicinity of a lower end portion formed of a combination of a cylindrical portion and a double wall structure around a bottom portion as another example of the bottomed cylindrical body of the present invention;
(A) is that the thickness of the lower end portion of the cylindrical portion is reduced in a tapered shape and embedded in a rising portion around the bottom portion to be integrated with a double wall structure.
In (b), a step is provided at the lower end of the cylindrical portion, and the tube is narrowed down.
FIG. 4 is an enlarged cross-sectional view near a lower end showing an example in which a band-shaped rising portion around a bottom portion is integrated so as to cover a longitudinal direction of a main body cylindrical portion.
FIG. 5 is a longitudinal sectional view showing a state in which a main body cylinder is injection-molded in a primary mold cavity in the molding method of the present invention.
FIG. 6 is a longitudinal sectional view showing a state in which a primary molded product is held in a final mold cavity in the molding method of the present invention, and a bottom portion and a rising portion are molded and integrated.
7A is a longitudinal sectional view of a writing instrument as an example of the use of the bottomed cylindrical body of the present invention, FIG. 7B is an AA ′ sectional view, and FIG. 7C is a BB ′ sectional view. It is.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Cylindrical part 2 Bottom part 3 Standup part around bottom 4 Primary mold cavity 5 Split mold plate 6 Rod-shaped core pin 7 One end of core pin 8 Movable mold plate 9 Fixed plate 10 Projection plate 11 Core pin tip 12 Fixed side mold Board 13 Sprue runner hole 14 Gate port 15 Ink reservoir 16 Ink guide core 17 Tip application section 18 Contact section

Claims (8)

A bottomed tubular body, wherein a main body tubular portion and a bottom portion forming a bottomed tubular body are integrated by a two-color molded body made of the same or different resin. The bottomed cylindrical body according to claim 1, wherein the bottom has a rising portion around the periphery, and the rising portion is integrated with at least a lower end of the main body cylindrical portion. The bottomed cylindrical body according to claim 1 or 2, wherein the rising portion around the bottom has a double wall structure and sandwiches the lower end of the main body cylindrical portion and is integrated with each other. 4. The method according to claim 2, wherein the main body cylinder is formed of a transparent or translucent resin molded body whose bottom is opaque, and a band-shaped rising portion around the bottom is integrated so as to cover the longitudinal direction of the main body cylinder. The bottomed cylindrical body as described. A step of obtaining one of the main body cylindrical portion and the bottom portion forming the bottomed cylindrical body by injection molding of a molten resin into the primary mold cavity, and holding the primary molded product in the mold cavity of the final molded product And a step of injecting and filling the same or different kinds of molten resin into the remaining voids in the mold cavity of the final molded product, molding the other portion, and simultaneously integrating the same into the final shape two-color molded body. A method for forming a bottomed cylindrical body, characterized in that: A step of obtaining the main body cylinder part by injection molding of a molten resin into the primary mold cavity of the main body cylinder part and the bottom part forming the bottomed cylindrical body; and a step of obtaining the final molded product in the mold cavity by the above-described primary molding. The step of holding the main body cylindrical portion, and the same or different type of molten resin is injected and filled into the remaining voids in the mold cavity of the final molded product to form the bottom portion and at the same time to be integrated with the final shape two-color molded body And a step of holding the main body cylindrical portion obtained by the primary molding in the mold cavity of the final molded product, wherein at least a part of the outer peripheral wall of the main body cylindrical portion is formed. Characterized by contacting the mold with the mold cavity of the final molded product. A writing ink is filled inside the bottomed cylindrical body according to any one of claims 1 to 4 as an ink storage tube, and the open side thereof is coated with an ink reservoir and an ink guide core. A writing instrument comprising a part. The ink storage tube is formed of two colors of a band-shaped opaque portion covered by a band-shaped rising portion from the outer peripheral surface of the bottom portion, and a transparent portion or a translucent portion that can see through the ink filling state inside. 7. The writing implement according to 7.

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