JPH10236066A - Casing for writing utensil - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a casing for writing utensil, 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: A refill support hole 5 whose inside diameter is slightly larger than the outside diameter of a refill is provided at 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 outside diameter of the refill support hole 5, and which is so designed that a gate mark 6 appears at a place on its inner face is provided outside the refill support hole 5 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]

According to the present invention, there is provided a refill supporting hole having an inner diameter slightly larger than the outer diameter of the refill 3 in a shaft of the writing instrument according to the present invention, that is, in a deep portion of the shaft tip opening 4 through which the refill 3 penetrates. In addition to the provision of the portion 5, the inside diameter of the refill support hole 5 is larger than that of the refill support hole 5 at the entrance of the shaft tip opening 4 outside the refill support hole 5, and the gate mark 6 appears at the inner surface thereof. The problem can be solved by a writing instrument shaft having the opening portion 7 provided.

[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] The shaft tip opening 4 through which the tip end of the refill 3 penetrates has an inner diameter that changes in the middle portion, the entrance portion is wide, and the back portion is narrow. That is, the inner end of the shaft tip opening 4 is a refill support hole 5, and the inner diameter thereof is set slightly larger than the outer diameter of the refill 3. However, the outer diameter of the refill in this case is the refill support hole 5
Means the outer diameter of the part passing through.

[0007] The shaft tip opening 4 outside the refill support hole 5
Is an opening portion 7. This opening 7
Is a place where the inner surface faces the gate of the mold at the time of injection molding, and the mark of cutting the gate at the time of mold release after molding, that is, the gate mark 6 is, as shown in FIG. 3 and FIG. Is to appear. The inner diameter of the widening portion 7 is set to be larger than the inner diameter of the refill support hole 5. That is, a step is formed between the inner surface of the opening 7 and the inner surface of the refill support hole 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.

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

[0009]

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 the refill support hole 5 and the widening portion 7 so that the gate mark 6 appears on the widening portion 7. And the accuracy of the refill support hole 5 can be increased without difficulty. In addition, since the inner diameter of the opening portion 7 is made larger than the inner diameter of the refill support hole portion 5 to provide a step 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 hole 5. There is no. Therefore, despite the appearance of the gate mark 6, the refill 3
Is supported without trouble by the refill support hole 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;

[Description of Signs] 1 Rear shaft 2 Front shaft 3 Refill 4 Shaft tip opening 5 Refill support hole 6 Gate mark 7 Enlarged opening

Claims (1)

[Claims] 1. A refill support hole 5 whose inner diameter is slightly larger than the outer diameter of the refill 3 is provided in a deep portion of the shaft tip opening 4 through which the refill 3 penetrates, and a shaft tip outside the refill support hole 5 is provided. A writing implement shaft, characterized in that an opening portion 7 having an inner diameter larger than that of the refill support hole portion 5 and having a gate mark 6 at an inner surface thereof is provided at an entrance portion at the end opening 4.