JP2001080279A - Extra lead case - Google Patents

Abstract

(57) [Summary] [Object] The present invention prevents the core from adhering to the inner wall surface of the case main body due to static electricity, prevents uneven thickness during molding of the case main body, and damages the mold due to malfunction of the mold. Can be prevented. [Constitution] In a refill lead case for housing a sharp lead formed of a synthetic resin, holes are formed at two opposing positions in front of an outer peripheral portion of a case body of the refill lead case, and an inner hole portion of the case body is provided. Forming a rib-shaped protrusion that appropriately bulges to the front end of the inner hole portion including the periphery of the hole opened in the inner wall, and the width of the rib-shaped protrusion is slightly larger than the width of the hole. Be set.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a refill lead case for a sharp pencil having a projection provided on an inner wall of an inner hole of a case body.

[0002]

2. Description of the Related Art Conventionally, when a core housing cylinder of a sharp pencil is made of a synthetic resin, the sharp core slides on the inner wall surface of the core housing cylinder due to the swing of the sharp pencil. As a result, there is a problem that static electricity is generated due to friction between the core and the inner wall of the core housing cylinder, and the sharp core adheres to the inner wall surface of the core housing cylinder. In order to minimize the contact area between the sharp core and the inner wall surface of the core housing cylinder, the applicant of the present application
No. 4-179252 proposed that a projection could be formed on the inner wall of the core housing cylinder to prevent the sharp core from adhering to the inner wall surface of the core housing cylinder due to static electricity. However, in the above-mentioned conventional example, when the core accommodating cylinder is formed by injection molding or the like, when the core pin of the mold is removed from the core accommodating cylinder, the protrusion that becomes an undercut is forcibly pulled out, and the projection is removed. Since the core receiving cylinder is distorted or deformed, there is a problem in defective molding and maintenance of the mold.

[0003]

SUMMARY OF THE INVENTION The present invention relates to a refill case for a mechanical pencil, but has the same problems as the above-mentioned refill case for mechanical pencils. In view of the above, it is possible to solve the above-mentioned conventional drawbacks and to prevent the core from adhering to the inner wall surface of the case body due to static electricity. In addition, it is possible to prevent uneven wall thickness during molding of the case body and prevent damage to the mold due to malfunction of the mold.

[0004]

The present invention has the following arrangement to achieve the above object. The refill lead case according to the first aspect of the present invention is a refill lead case for housing a sharp lead formed of a synthetic resin, wherein holes are provided at two opposing locations in front of the outer periphery of the case body of the refill lead case. The case body is formed to have a rib-shaped protrusion that appropriately swells forward to the front end of the inner hole, including the periphery of the hole opened in the inner wall of the case body, and to the width of the hole. The width of the rib-shaped protrusion is set slightly larger.

[0005]

1 to 12 show a lead case 1 for a mechanical pencil according to an embodiment of the present invention. First, in the refill lead case 1 shown in FIGS. 1 to 5, a plurality of sharp leads are accommodated in an inner hole 2d of a case body 2 having a front end closed from an opening at a rear end, and a shaft at a rear end. The cap 3 is removably fastened so that the core accommodated in the part 4 does not escape to the outside. An engaging portion 4a is formed on the outer peripheral portion of the shaft portion 4 by a protrusion or a groove.
A locking portion is formed on the inner peripheral portion of the locking portion so as to be engaged with the locking portion 4a and lockable. (It is also possible to use a screw as an interlocking portion.) Further, holes 2b are formed at two opposing positions in front of the outer peripheral portion of the case body 2.

FIG. 6 is an enlarged view of a portion A shown in FIG. 5, FIG. 7 is a sectional view taken along line AA of FIG. 6, and FIG. 8 is a sectional view taken along line BB of FIG. As shown in the figure, a circular hole 2b having an appropriate taper is formed inward at two opposing positions in front of the outer peripheral portion of the case body 2. Further, in front of the inner hole 2d of the case main body 2, the hole 2b is opened in the inner wall. In addition, a rib-shaped protrusion 2a is formed which swells appropriately to the front including the periphery of the hole 2b to the front end of the inner hole. In addition, the rib-shaped protrusion 2a corresponds to the width of the hole 2b.
Are set slightly larger. Therefore, the hole 2b
Has no protrusions 2a on both sides in the horizontal direction or is formed in a thin film shape.

The rear end of the cap 3 has a slit-shaped ventilation hole 3a divided at a required position along the circumferential direction.
Are formed. This vent hole 3a can be used if an infant accidentally swallows the cap 3 and clogs his throat.
It is provided to enable emergency ventilation to avoid suffocation. Also, this slit-shaped vent hole 3a is
The slit width is set slightly smaller than the diameter so that the sharp core does not leak.

[0008]

Next, the operation of the present invention will be described. First, FIGS. 9 and 10 show a state where the sharp core 5 is accommodated in the inner hole 2 d of the case main body 2. If the projection 2a is not provided, there is a problem that the accommodated sharp core comes into line contact with the inner wall surface of the case body over its entire length and adheres due to static electricity. However, by providing the projection 2a, both ends of the core are provided. And only one point in the middle is in contact, so that it is difficult to adhere due to static electricity. In addition, a hole 2b is formed substantially at the rear end of the projection 2a, and static electricity is discharged by this hole. Therefore, it is harder to adhere due to static electricity, and the required core can be easily taken out from the case body.

In addition, holes 2b are formed at two opposing positions in front of the outer peripheral portion of the case main body 2 so as to open into the inner wall of the inner hole.
By forming the rib-shaped protrusion 2a which swells appropriately to the front including the periphery of b to the front end of the inner hole, the following effects are obtained in relation to the mold structure and the molding operation. That is, in the mold, a groove forming the rib-shaped protrusion 2a is provided in the core pin forming the inner hole 2d of the case main body 2, and the pin member forming the hole 2b is inserted into the groove. . Accordingly, the movement of the core pin in the vertical direction as well as in the horizontal direction can be extremely finely restricted, so that the core pin can be prevented from bending and uneven thickness of the molded product can be prevented. When the above-mentioned groove is not provided in the core pin, the movement in the left-right direction can be restricted, but the movement in the vertical direction cannot be restricted.

Although the pin member is set so as to jump into the groove of the core pin when the mold is closed, that is, at the time of molding, the resin is injected into the mold even when the pin member jumps into the groove of the core pin. If it is before, the core pin can move in the pull-out direction. This means that the core pin is normally located at a predetermined position, and then the pin member is set to jump into the groove of the core pin. However, in the unlikely event that the pin member jumps first due to a malfunction of the mold, etc. Even if the core pin moves to a predetermined position afterwards, the pin member and the core pin do not interfere with each other, so there is no risk of damaging the mold.

Further, by providing a gate position for molding at the front end position of the case main body, the groove of the core pin has a function of a guide groove for flowing the injected resin.
Elimination of the resin in the mold is eliminated, and the resin flows with a uniform pressure around the core pin, and an effect of preventing the core pin from being bent can be expected. In addition, the effect of preventing bubbles from entering the molded article can be expected by eliminating the entrapment of the resin.

FIGS. 11 and 12 show another embodiment in which a sharp core 5 is housed in an inner hole of a case body 6. FIG. The basic configuration and operation are the same as those of the above embodiment, and only the differences will be described. First, FIG.
Shows that the curved end of the projection 6a avoids the problem that when the sharp core is inserted into the case body, the projection is difficult to insert due to the core being caught on the projection. Note that the rear end is not limited to a curved surface and is selected according to design convenience such as a slope and a mountain shape. FIG. 12 further shows that a protrusion 6c is additionally provided to further reduce the adhesion of the core due to static electricity.

In the above embodiment, the holes 2b and 6b are not limited to a circle but may be a square. Further, although the case body is shown in a cylindrical shape, it can of course be formed in a polygon such as a triangle and a quadrangle.

[0014]

According to the present invention, holes are drilled at two opposing positions in front of the outer periphery of the case main body of the refill lead case, and the periphery of the hole opened on the inner wall of the inner hole of the case main body is directed forward. By forming a rib-shaped protrusion that appropriately swells to the front end of the inner hole, it is possible to prevent the sharp core from adhering to the inner wall surface of the case body due to static electricity. In addition, it is possible to prevent uneven wall thickness during molding of the case body and prevent damage to the mold due to malfunction of the mold.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing an embodiment of a refill lead case of the present invention.

FIG. 2 is a diagram showing an upper end of a cap.

FIG. 3 is a front view showing the appearance of a refill lead case.

FIG. 4 is a front view of a case body.

FIG. 5 is a vertical sectional view of a case main body.

FIG. 6 is an enlarged view of a portion A in FIG.

FIG. 7 is a sectional view taken along the line AA of FIG. 6;

FIG. 8 is a sectional view taken along the line BB of FIG. 6;

FIG. 9 is a longitudinal sectional view of a main part showing a state where a sharp core is inserted into a case main body.

FIG. 10 is a cross-sectional view of a main part showing a state where a sharp core is inserted into a case body.

FIG. 11 is a longitudinal sectional view of a main part showing a state in which a sharp core is inserted into a case body according to another embodiment.

FIG. 12 is a cross-sectional view of a main part showing a state where a sharp core is inserted into a case body according to another embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Extra lead case 2 Case main body 2a Projection 2b hole 2c Depression for gate 2d Inner hole 3 Cap 3a Vent hole 4 Shaft 4a Locking part 5 Sharp core 6 Case main body 6a Projection 6b Hole 6c Projection

Claims (1)

[Claims] 1. A replacement lead case for housing a sharp lead formed of a synthetic resin, wherein two holes are formed at two opposing positions in front of an outer peripheral portion of a case body of the replacement lead case, and the inside of the case body is formed. A rib-shaped protrusion is formed which swells forward to the front end of the inner hole including the periphery of the hole opened in the inner wall of the hole, and the width of the rib-shaped protrusion is slightly smaller than the width of the hole. Extra lead case that is set to be large.