JP3694995B2 - Writing instrument cap - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention consists of an injection molded product of synthetic resin, comprising an outer cylinder part with an open end at the end and an inner cylinder part that is a bottomed cylinder with one end closed at the open end of the inner cylinder part. And has a connecting part that connects integrally with the inner wall of the outer cylinder part, and prevents suffocation when an infant or the like communicating with both opening ends of the outer cylinder part clogs the cap in the throat near the opening end of the inner cylinder part The present invention relates to a writing instrument cap formed with an air circulation hole for use.
[0002]
[Prior art]
Conventionally, as a cap of a writing instrument having an air circulation hole for preventing suffocation, an outer cylinder part that secures an air (breathing) passage and an inner cylinder part that airtightly holds the pen tip of the writing instrument body are known. It has been. As an example, the ones shown in Japanese Utility Model Laid-Open No. 2-58981 and Japanese Utility Model Laid-Open No. 3-9879 can be cited, but the air (breathing) flow passage of such a cap has an outer cylinder portion. And an air circulation hole is formed in the connecting part of the inner cylinder part and the inner cylinder part.
[0003]
[Problems to be solved by the invention]
Depending on the position of the air circulation hole, which is a part of the air flow passage, there was a problem. In other words, in the case where the air circulation hole is formed only in the inner cylinder portion, the connecting portion between the inner cylinder portion and the outer cylinder portion is formed as an inward protruding portion of the outer cylinder portion, and is attached to the writing instrument body. There is a concern that the tip of the pen tip may be damaged by touching the tip of the pen tip. Therefore, the area of the inward projecting portion where the pen tip abuts when the air circulation hole is formed in the connecting portion between the outer cylinder portion and the inner cylinder portion so as to be continuous with the air circulation hole of the inner cylinder portion. The concern that the pen tip will be damaged will decrease. However, the formation of air circulation holes in the connecting portion causes a problem on the mold in the case of a synthetic resin injection-molded product. That is, in the portion of the mold corresponding to the air circulation hole of the connecting portion, the core pin collides with the cavity, and there is a problem that the portion is damaged such as wear or deformation, resulting in poor durability . .
[0004]
[Means for Solving the Problems]
That is, the present invention is made of an injection molded product of synthetic resin, and is composed of an outer cylindrical portion whose end is an open port and an inner cylindrical portion which is a bottomed cylindrical body whose one end is closed, and the open end of the inner cylindrical portion A connecting part that is integrally connected to the inner wall of the outer cylinder part at the part, and an air circulation hole for preventing suffocation that communicates with both opening end parts of the outer cylinder part is formed in the vicinity of the opening end of the inner cylinder part In the writing instrument cap, the air circulation hole is formed in the side wall of the inner cylinder part, and a part of the air circulation hole is formed by the edge of the connection part, and the air circulation hole in the connection part is formed. A gist of the present invention is a writing instrument cap characterized in that a thin wall portion is formed on the edge, and the thin wall portion is formed so as to be broken when the pen tip comes into contact therewith.
[0005]
[Action]
The air circulation hole is formed in the inner cylinder part, and the minimum air circulation amount when clogged in the throat is secured in this part. Also, by making the portion corresponding to the air circulation hole of the connecting portion a thin portion, the pen tip breaks the thin portion when the pen tip abuts on this portion, and an excessive load is not applied to the pen tip, Damage to the nib is avoided. In addition, the mold core pin and the cavity corresponding to the thin film portion do not collide, so that the mold has high durability.
[0006]
【Example】
Hereinafter, an example will be described with reference to the drawings. 1 is a longitudinal sectional view of a cap of a writing instrument according to the present invention, and an outer cylinder portion 1 having front and rear ends as an open port and an inner cylinder portion 2 which is a bottomed cylindrical body having one end closed are shown as inner cylinders. The connecting portion 4 is connected in the vicinity of the opening 3 of the portion 2. The outer tube portion 1 has a fitting projection 5 for a writing instrument main body (not shown) at the rear end portion of the inner hole, and a pen nib (not shown) is brought into circumferential contact with the writing tool main body in the inner tube inner hole. It has the annular protrusion 6 which makes airtight. Moreover, the inner cylinder part 2 has the air circulation hole 7 in the side wall. The air circulation hole 7 allows the two openings of the outer cylinder portion to communicate with each other, so that a minimum breathing can be ensured even when an infant or the like clogs the cap in the throat.
[0007]
As shown in FIG. 2 which is an enlarged view of the I part of FIG. 1 and FIG. 3 which is a cross-sectional view taken along the line II-II, a pen tip is attached to the connecting part 4 between the outer cylinder part 1 and the inner cylinder part 2. A thin portion 4a that can be easily broken by a weak force when abutting is formed. The thin-walled portion 4a is formed at a position corresponding to the air circulation hole 7 of the inner cylinder portion 2, and when the pen tip comes into contact with the portion and breaks the portion, the pen tip passes through the edge of the air circulation hole 7 as it is. Since it is accommodated in the inner cylinder, it is suppressed as much as possible that an excessive load is applied to the pen tip. Here, as an example, when the nib is thin like a synthetic resin nib having a communication hole, the thickness of the thin portion 4a is 0.10 mm or less if the cap is made of a soft material such as polypropylene. are preferred, preferably 0.08mm or less if the relatively rigid material of approximately nylon or polyoxymethylene, when although relatively thick, such as a fiber collecting body as a pen tip, if soft material such as polypropylene It is preferably 0.12 mm or less, and is preferably 0.10 mm or less if it is a relatively hard material such as nylon or polyoxymethylene.
[0008]
Another example is shown in FIGS. The number of air circulation holes is increased as compared with those in FIGS. 1 to 4, and the pen tip is less likely to be damaged. By increasing the number of air circulation holes 7, the proportion of the thin portion 4a in the connecting portion 4 is also relatively increased, and the connecting portion between the thin portions is further thinned. Also, it can be shifted to the thin part side immediately.
[0009]
In this example, the number of air circulation holes 7 is increased, and accordingly the number of connecting portions 4 is increased in the same manner. . That is, the injection molded product having holes such as the air circulation holes 7 has a portion where the flow of the resin is merged due to the structure of the mold, and the resin which has been cooled and solidified slightly at the portion is completed. A so-called weld that is a groove-like depression may be formed in the molded product. In this example, the weld may occur in the outer wall portion of the outer cylinder portion 1 . However, in the case where a large number of connecting portions 4 are formed as in this example, the amount of the relative resin reaching the joining point of the resin at the time of molding can be reduced, and the time to reach the joining point is also short. In other words, the resins can be merged while being in a relatively complete molten state. Therefore, even if the weld is difficult to occur, even if it occurs, it is dispersed as many as possible, and the depth of the recess is shallow, and the appearance can be hardly affected.
[0010]
In addition, since it is a synthetic resin injection-molded product and a writing instrument cap, the writing instrument cap originally protects the pen tip of the writing instrument body and prevents ink from evaporating from the part. However, when the air circulation hole 7 is provided, there is a possibility that the ink evaporation from the pen tip may be prevented from being adversely affected. That is, a synthetic resin molded product molded by injection molding shrinks and decreases in volume when cooled after molding. For example, when polypropylene resin is used, the volume is said to decrease by about 2%. In the case where the annular projection 6 is formed in the inner hole of the inner cylindrical portion 2 and the writing instrument main body is attached as in this example, the portion and the outer wall of the writing instrument main body are brought into close contact with each other to hold the pen tip in an airtight manner In the case where there is a portion where the resin does not exist on the same circumference, such as the air circulation hole 7, there is a possibility that a problem occurs in maintaining airtightness. In other words, the fact that there is a portion where resin does not exist and the portion where resin does not exist on the same circumference means that there is a subtle difference in the shrinkage dimension when the resin shrinks immediately after molding, and the part of the molded product after shrinkage is circular It may become a shape close to a polygon. This difference in shrinkage size also affects the shrinkage of the annular projection 6, and there is a concern that a good close contact with the writing instrument body cannot be obtained. However, as in this example, each of the air circulation holes is narrow and a large fraction is formed, so that the difference in shrinkage dimension is relatively small, and the annular protrusion 6 is in close contact with the writing instrument body. It is difficult to adversely affect
[0011]
【The invention's effect】
As described above, the cap of the writing instrument of the present invention ensures a minimum air flow when clogged in the throat, does not impose an excessive load on the pen tip, and avoids damage to the pen tip. Moreover, the durability of the mold for molding the cap is also high.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view showing an example.
FIG. 2 is an enlarged view of a portion I in FIG.
FIG. 3 is a view taken along the line II-II in FIG.
FIG. 4 is a longitudinal sectional view showing another example.
FIG. 5 is an enlarged view of a portion I in FIG. 4;
6 is a view taken along the line II-II in FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Outer cylinder part 2 Inner cylinder part 3 Opening part 4 Connection part 4a Thin part 5 Fitting protrusion 6 Annular protrusion 7 Air flow hole

Claims (1)

It consists of an injection molded product of synthetic resin, consisting of an outer cylinder part with an open end at the end and an inner cylinder part that is a bottomed cylinder with one end closed, and the outer cylinder part at the open end of the inner cylinder part has a connecting portion connecting the inner wall and integral, in the cap of the writing instrument obtained by forming an air circulation hole for preventing choking which communicates with both opening ends of the outer tubular portion near the open end of the inner cylindrical portion, said An air circulation hole is formed in the side wall of the inner cylinder part, and a part of the air circulation hole is formed by an edge of the connection part, and a thin part is formed at an edge forming the air circulation hole in the connection part. In addition, the cap of the writing instrument, characterized in that the thin portion is a thin portion that can be torn when the pen tip comes into contact with it.

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