JPH10236067A - Casing for writing utensils - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a casing for writing utensils, which is so designed that a gate mark appears on an inner face of a top end port of the casing, the gate mark is inconspicuous, and the external appearance of the casing is made better, and which is capable of supporting a refill, or obtaining a desired dimensional accuracy at a place of guiding the refill, irrespective of appearance of the gate mark on the inner face of the top end port of the casing. SOLUTION: Refill support protrusions 5 whose inscribed diameter is slightly larger than the outside diameter of a refill are provided at a plurality of places in the peripheral direction on an inner face of an inner part in a top end port 4 of a casing, through which the refill is penetrated. Further, an expanded port 7 whose inside diameter is larger than the inscribed diameter at places where the refill support protrusions 5 are provided, and which is so designed that a gate mark 6 appears at a place on its inner face is provided outside the places where the refill support protrusions 5 are provided, and at an inlet portion of the top end port 4 of the casing.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an injection-molded plastic writing instrument shaft having a shaft tip opening through which a refill is inserted at the tip.

[0002]

2. Description of the Related Art When a shaft of a writing instrument is injection-molded with plastic, a mark of a mold gate, that is, a gate mark appears on the product, but when the gate mark appears on the surface of the product, the appearance of the product deteriorates and the commercial value is reduced. Goes down. Therefore, it is common to design a mold so that a gate mark appears in a place where a product is inconspicuous. In the case of a writing instrument shaft, for example, the inner surface of the shaft tip opening through which the refill penetrates is preferable as a location where the gate mark appears. This is because the gate mark is hard to be seen from the outside in this place. However, the shaft tip opening is a place to support the tip of the refill so as not to shake, and when the refill comes and goes, it is a place to guide the refill smoothly, so its inner diameter is slightly larger than the outer diameter of the refill. It is necessary to increase the dimensional accuracy in such a manner, but if a gate mark appears on the inner surface of the shaft tip opening, there is a problem that it is difficult to obtain a desired dimensional accuracy.

[0003]

SUMMARY OF THE INVENTION According to the present invention, a gate mark is made to appear on an inner surface of a shaft tip opening to make the gate mark hard to see, so that the appearance is improved and the shaft tip opening is improved. It is an object of the present invention to provide a writing instrument shaft that can support or guide a refill even though a gate mark appears on an inner surface thereof and can obtain a desired dimensional accuracy.

[0004]

The above object is achieved by the shaft of the writing instrument of the present invention, that is, at a plurality of circumferential locations on the inner surface of the inner portion of the shaft tip opening 4 through which the refill 3 penetrates.
A refill support protrusion 5 whose inscribed diameter is slightly larger than the outer diameter of the refill 3 is provided, and a refill support protrusion is provided at the entrance of the shaft tip opening 4 outside the place where the refill support protrusion 5 is provided. This can be solved by a writing implement shaft characterized in that an inner diameter is larger than an inscribed diameter of a portion where the portion 5 is provided, and an opening portion 7 is provided so that a gate mark 6 appears on the inner surface portion.

[0005]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view showing a shaft of a knocking ballpoint pen according to an embodiment of the present invention. This shaft is composed of a rear shaft 1 and a front shaft 2 which are screwed together, and both the rear shaft 1 and the front shaft 2 are made of plastic and injection-molded using a mold. The refill 3 is housed inside the shaft, and the tip of the refill 3 can be freely protruded and retracted at a shaft tip port 4 provided at the tip of the front shaft 2 as shown in FIGS.

[0006] In the inner part of the shaft tip opening 4 through which the tip of the refill 3 penetrates, there are provided refill support projections 5 at four locations in the circumferential direction on the inner surface thereof. The inscribed diameter of the portion where the refill support protrusion 5 is provided is set slightly larger than the outer diameter of the refill 3. However, the outer diameter of the refill 3 in this case refers to the outer diameter of a portion passing through the portion where the refill support protrusion 5 is provided.

Outside the location where the refill support projection 5 is provided, the entrance of the shaft tip opening 4 is an opening 7. The opening 7 has an inner surface facing the gate of the mold at the time of injection molding, and a mark obtained by cutting the gate at the time of mold release after molding, that is, a gate mark 6 is shown in FIGS. As shown, it appears at its inner surface. The inner diameter of the opening 7 is the same as that of the refill support projection 5.
The dimension is set to be larger than the inscribed diameter of the place where is provided.
That is, a step is formed between the inner surface of the opening 7 and the inner surface of the refill support protrusion 5. This step is set so as to be larger than the protruding height of the gate mark 6 that appears on the inner surface of the opening 7. The gate mark 6 may appear at only one location as shown in FIGS. 3 and 4, but may appear at a plurality of locations or on the entire circumference of the inner surface of the opening 7.

In the above-described embodiment, the refill support protrusions 5 are provided at four positions, but may be provided at three positions as shown in FIG.

Further, in the above embodiment, the surface of the refill support protrusion 5 is a flat surface, but the surface of the refill support protrusion 5 may be a curved surface as shown in FIGS.

Although the above embodiment relates to the axis of a knock-type ballpoint pen, the present invention is not limited to this, and the type of writing instrument is free.

[0011]

The axis of the writing instrument according to the present invention is as described above. First, the gate mark 6 is made to appear at the inner surface of the widened portion 7 of the shaft tip opening 4, so that the gate mark 6 is inconspicuous. The appearance looks good. Next, the shaft tip opening 4 is divided into a portion where the refill support protrusion 5 is provided and an opening 7 so that the gate mark 6 appears on the opening 7 so that the refill support protrusion 5 is provided. The accuracy of the location where the refill support protrusion 5 is provided can be easily increased without being affected by the gate mark 6.
Also, since the inside diameter of the mouth opening portion 7 is made larger than the inscribed diameter of the place where the refill support projection 5 is provided, and a step is provided on the inner surface,
Even if the gate mark 6 that appears in the opening 7 protrudes slightly, the amount of protrusion can be absorbed by the step on the inner surface, and the gate mark 6 has no effect on the refill 3 supported by the refill support protrusion 5. There is no. Therefore, despite the appearance of the gate mark 6, the refill 3
Is supported without hindrance by the refill support projection 5,
In addition, when the person appears and disappears, the operation is smoothly guided, so that no malfunction occurs.

[Brief description of the drawings]

FIG. 1 is a partially cut-away side view showing a state in which a tip portion of a refill projects from a shaft tip opening.

FIG. 2 is a partially cut-away side view showing a state in which a refill is immersed inside a shaft.

FIG. 3 is an enlarged cross-sectional view of a shaft tip.

FIG. 4 is a view taken along the line AA of FIG. 3;

FIG. 5 is an enlarged front view of a shaft tip opening as viewed from the front.

FIG. 6 is an enlarged sectional view of a shaft tip portion.

FIG. 7 is a view taken along line BB of FIG. 6;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Rear shaft 2 Front shaft 3 Refill 4 Shaft tip port 5 Refill support convex part 6 Gate mark 7 Enlarged part

Claims (1)

[Claims] 1. A refill support projection 5 whose inner diameter is slightly larger than the outer diameter of the refill 3 is provided at a plurality of circumferential locations on the inner surface of the inner portion of the shaft tip opening 4 through which the refill 3 penetrates. The inner diameter is larger than the inscribed diameter of the location where the refill support projection 5 is provided at the entrance of the shaft tip opening 4 outside the location where the refill support projection 5 is provided,
A writing implement shaft, characterized in that an opening 7 is provided on the inner surface thereof so that a gate mark 6 appears.