JPH0986091A - Barrel of a writing implement - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a case cylinder, which is formed of a synthetic resin by extrusion molding, of a writing implement which has a simple structure, can be manufactured easily at low cost, and provides satisfactory sealing performance with respect to a cap. SOLUTION: At a head end of a barrel 1 formed of a synthetic resin by extrusion molding, a tapered draw section 3 is formed by heat drawing. On the outer face of the draw section 3, a hermetic mounting section 4 (annular smooth plane) with respect to a cap 7 is integrally formed. Further, on the inner face of the draw section 3 at the back part of the hermetic mounting section 4, a nib holding section 5 (inward protrusion) having an air groove 6 is integrally formed.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a writing instrument (for example,
Ball pens, felt-tip pens, marking pens, brush pens, fountain pens, small tube pens, etc.). More specifically,
The present invention relates to a barrel for a writing instrument in which a tapered end portion of a tubular body formed by extrusion molding of a synthetic resin is provided with a tapered portion by heating and drawing.

[0002]

2. Description of the Related Art Conventionally, as a barrel of a writing instrument, a barrel in which a distal end of a hollow material formed by extruding a resin material such as vinyl chloride or polypropylene is heat-drawn into a tapered shape is widely known.

However, as shown in FIG. 7, in the conventional barrel 9, the airtight mounting part 92 with the cap 94 is formed by heat-drawing the tip of the barrel 9, and the barrel 9 is behind the throttle.
It is provided on the outer surface, that is, on the outer surface of the barrel 9 that is not subjected to heat drawing. Generally, the outer peripheral surface of the extruded body has minute scratches and irregularities, and has an unstable shape with low dimensional accuracy. Therefore, the airtight mounting portion 92 is provided on the outer surface of the shaft cylinder 9 which is not subjected to the heat drawing process. In the conventional barrel 9, the cap 94
Does not satisfy the sufficient sealing performance with. Moreover, the conventional barrel 9 requires time and labor for manufacturing because the air hole 93 (lateral hole) is formed in the narrowed portion 91 by a drill or the like.

Further, Japanese Utility Model Publication No. 6-86974 discloses that
In order to form a fitting protrusion on the tip of the extruded barrel, the end of the extruded barrel is inserted into a heated jig with a conical hole to form a tapered tip. After cooling the barrel, a barrel in a writing instrument is disclosed in which a groove is formed in the tip by cutting or polishing, and a ring having a protrusion on the outer periphery is press-fitted into the groove.

However, the shaft cylinder disclosed in the above publication not only increases the number of parts due to the ring, but also requires a step of forming a groove, a step of attaching a ring, etc., which complicates the manufacturing process and can be provided at a low cost. I can't.

[0006]

SUMMARY OF THE INVENTION The present invention is to solve the above-mentioned problems of the prior art, and in an axial cylinder made of an extruded product, it is possible to satisfy a sufficient sealing performance with a cap and the structure is simple. It is intended to provide a shaft of a writing instrument which is easy to manufacture at low cost.

[0007]

Means for Solving the Problems Outline The present invention relates to a barrel 1 of a writing instrument, in which a tapered drawing portion 3 is provided at a tip end portion of a cylindrical body 2 formed by extrusion molding of synthetic resin by heating drawing processing. The requirement is that the airtight mounting portion 4 with the cap 7 is integrally formed on the outer surface of the narrowed portion 3 by heat drawing processing.

Airtight Mounting Part The airtight mounting part 4 is an annular smooth surface, that is, an annular straight surface (cylindrical outer surface) or an annular tapered surface (tapered conical outer surface).
It is preferred that Further, in the case of heat drawing, when the pen tip holding portion 5 having the air groove 6 penetrating in the axial direction is integrally formed on the inner surface of the drawing portion 3, when the pen tip holding portion 5 is formed.
The airtight mounting portion 4 is preferably integrally formed on the outer surface of the front throttle portion 3 or the rear surface of the pen tip holding portion 5 rearward of the throttle portion 3.

Pen Tip Holding Section The pen tip holding section 5 is preferably formed integrally with the inner surface of the drawing section 3 during the heat drawing process. Further, it is preferable that the pen tip holding portion 5 is provided on the outer surface of the throttle portion 3 in front of or behind the airtight mounting portion 4. Also, the pen tip holder 5
Specifically, an axial projection in which a plurality of air grooves 6 are provided so as to penetrate in the axial direction, in other words, a plurality of air grooves 6 are arranged at appropriate intervals on the inner peripheral surface, and the air grooves 6 are provided between them. A plurality of ribs extending in the direction is preferred. Further, in addition to this, in the pen tip holding portion 5, the air groove 6 may be a rib having an arcuate cross section in which one air groove 6 is provided in an annular inward projection (or an annular reduced diameter portion).

Hot-drawing Hot-drawing is performed with synthetic resin (for example, polypropylene,
Vinyl chloride, polyethylene, polystyrene, acrylic,
A squeeze die 8 in which the tip of the tubular body 2 obtained by extrusion molding of polyethylene terephthalate, ABS resin, etc. is heated.
After the insertion into the tapered concave portion 81, the tip of the tubular body 2 is pulled out from the concave portion 81 to form the tapered narrowed portion 3 on the distal end of the tubular body 2. Simultaneously with the heating drawing process, the airtight mounting portion 4 is integrally formed on the outer surface of the drawing portion 3 and the core pin 82 of the heated drawing die 8 having an appropriate shape is pressed against the inner surface of the drawing portion 3. The pen nib holder 5 having the air groove 6 can be integrally formed (see FIG. 4). Before performing the heat drawing process, the cylindrical body 2 is preferably a cylindrical body having a circular cross section in that the airtight mounting portion 4 having sufficient sealing performance can be easily formed in the narrowed portion 3, but other than this, In addition, the cross section may be any of a polygonal shape such as a triangle, a quadrangle, a hexagon, and an octagon, or an oval shape. Further, it is preferable that the narrowed portion 3 obtained by the hot-drawing process has a circular cross section in terms of ensuring airtightness.

[0011]

The function of the narrowed portion 3 formed by the heat-drawing process is that the outer peripheral surface has few fine irregularities, scratches, or distortion, and is stable in size and shape. Therefore, the diaphragm 3
The airtight mounting portion 4 formed integrally with the outer surface can maintain sufficient airtightness with the cap 7. In addition, by heat-drawing a synthetic resin extruded product, the barrel 1 having a simple structure and easy to manufacture can be provided at low cost.

Since the airtight mounting portion 4 has an annular smooth surface and does not have an undercut portion formed by an annular protrusion or the like, when the tubular body 2 is pulled out from the drawing die 8, it can be easily pulled out. The airtight mounting portion 4 can be maintained in an optimum shape for maintaining airtightness without breaking the shape.

By forming the pen tip holding portion 5 in which the air groove 6 is axially formed so as to be integrally formed on the inner surface of the narrowed portion 3, the air hole can be formed like the shaft cylinder 1 made of the conventional extruded body. It is possible to shorten the manufacturing process without needing to pierce. Furthermore, the airtight mounting portion 4 is integrally formed on the outer surface of the throttle portion 3 in front of the pen tip holding portion 5 or the outer surface of the throttle portion 3 behind the pen tip holding portion 5, so that the throttle portion 3 has a modified shape having an air groove. Since the cross section (that is, the wall thickness variation portion) is provided, even if a sink mark is generated on the outer surface of the throttle unit 3 during the heat drawing, the airtight mounting portion 4 is not affected by the sink mark and has a proper ring shape. Can be maintained.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, specific embodiments of the present invention will be described with reference to the drawings.

Example 1 (see FIGS. 1 and 2) The shaft cylinder 1 is made of a cylindrical extruded body of synthetic resin such as polypropylene or vinyl chloride. A tapered drawing portion 3 is formed at the tip of the barrel 1 by heat drawing. At the time of the hot drawing, the pen tip holding portion 5 composed of two ribs having an arc-shaped cross section is integrally formed on the inner surface of the drawn portion 3, and two air grooves 6 are arranged between the ribs. Set up. At the same time, the drawing portion 3 in front of the pen tip holding portion 5
An airtight mounting portion 4 made of an annular straight surface is integrally formed on the outer surface. That is, by the heat drawing, fine irregularities and distortions on the outer peripheral surface of the extruded body can be corrected, and further, the drawing portion 3 where the airtight mounting portion 4 is located has an annular uniform wall thickness. Since there is no risk of sink marks during molding, the airtight mounting portion 4 has an appropriate shape with sufficient sealing performance.

Application Example (FIG. 3) A pen tip 11 (for example, a pen tip for a writing pen made of a plastic porous body) is attached to the tip end opening portion of the shaft cylinder 1 of FIG. 1, and the pen tip 11 is an air groove. It is held by a pen tip holding unit 5 having a unit 6. An ink occlusion body 12 made of a fiber bundle is housed in the barrel 1. The tip of the ink occlusion body 12 is connected to the rear end of the pen tip 11 by immersion.
An air groove 6 is formed around the pen tip 11 by the pen tip holder 5.
Is provided, and the inside of the barrel 1 is communicated with the outside air by the air groove 6.

In addition to this, the pen tip 11 may be, for example,
Rod-shaped fiber bundle resin processed product, ballpoint pen tip with ink guide core inside, fountain pen nib with slit at the tip and ink guide core inside, or ink in the axial direction on the outer or inner surface Examples thereof include a pen tip made of a synthetic resin extruded product having a lead-out path.

The cap 7 is formed by integrally molding the inner cylinder 71 and the outer cylinder 72 by injection molding of synthetic resin. The inner cylinder 71 is provided with an annular seal portion 73 (annular projection) that can be brought into close contact with the airtight mounting portion 4 of the shaft cylinder 1 on the inner surface, and is integrally connected to the inner surface of the outer cylinder 72. Further, on the inner surface of the outer cylinder 72, a plurality of point-shaped projections 74 that can be fitted to the outer surface of the shaft cylinder 1 are provided.

Heat Drawing (FIG. 4) Next, the heat drawing will be described. The drawing die 8 is composed of a tapered recess 81 and a core pin 82 protruding from the bottom of the recess 81. An annular smooth surface 83 for molding the airtight mounting portion 4 of an annular straight surface is provided on the inner surface near the bottom of the recess 81. On the other hand, the core pin 8
On the outer surface of the shaft 2, there are formed a notch and a ridge 84 having a circular cross section for forming the rib and the air groove 6 of the pen tip holder 5 of the barrel 1 of FIG. The heated drawing die 8
After the tip portion of the cylindrical tubular body 2 obtained by extrusion molding is press-fitted into the concave portion 81, the tip portion is removed from the concave portion 81. As a result, the tapered throttle portion 3 is formed at the tip of the shaft cylinder 1, and at the same time, the rib of the pen tip holding portion 5 and the air groove 6 are integrally formed on the inner surface of the throttle portion 3, and the outer surface of the throttle portion 3 is formed. The airtight mounting portion 4 is integrally formed with the.

Embodiment 2 (FIGS. 5 and 6) The front end of the barrel 1 is formed by heat drawing to form a narrowed portion 3 consisting of a front portion having an annular tapered surface and a rear portion having an annular straight surface. . During the heat drawing, the airtight mounting portion 4 is provided on the rear surface of the outer surface of the drawing portion 3, while the pen tip holding portion 5 having four ribs and four air grooves 6 therebetween is provided on the inner surface of the drawing portion 3. Are integrally molded. The airtight mounting part 4 is located behind the pen tip holding part 5.

Pen point 11 (for example, a resin processed body of fiber)
Is press-fitted from the opening of the tip of the barrel 1, and the pen tip holder 5
It is held by (4 ribs). The pen tip 11 has its rear end immersed and connected to the tip of the ink occlusion body 12 housed in the barrel 1.

On the inner surface of the cap 7, an annular seal portion 73 (annular protrusion) for maintaining airtightness is provided. When the cap 7 is attached to the tip portion, the annular seal portion 73 and the airtight attachment portion 4 are brought into close contact with each other, the pen tip 11 side is sealed, and the ink from the pen tip 11 is prevented from drying up. Although the annular seal portion 73 is an annular protrusion in the drawing, it may be a tapered or straight annular smooth surface.

In the first and second embodiments, the pen tip 11
Although the outer surface of the pen tip holding portion 5 is directly held, the pen tip holding portion 5 may be press-fitted and held by interposing another member such as a holder member. That is, the pen tip 11 of the present invention also includes one having a holder member.

[0024]

As described above, the shaft cylinder of the writing instrument of the present invention has the structure of claim 1 (that is, a tapered drawing portion is provided at the tip of a cylinder formed by extrusion molding of synthetic resin by heating drawing. By forming the airtight mounting part with the cap integrally on the outer surface of the part), it is possible to maintain sufficient airtightness with the cap, and it is ideal as an inexpensive barrel that is simple in structure and easy to manufacture. .

According to the structure of claim 2 (that is, the airtight mounting portion is an annular smooth surface), when the tubular body is pulled out from the drawing die, the airtight mounting portion can be easily removed and the shape of the airtight mounting portion can be removed. The shape can be maintained optimally for keeping airtightness without breaking.

According to a third aspect of the present invention (that is, an inner surface of the throttle portion is integrally formed with a pen tip holding portion having an air groove penetrating in the axial direction, the pen tip holding portion is provided in front of the pen tip holding portion or behind the pen tip holding portion. With the configuration in which the airtight mounting portion is integrally formed on the outer surface of the throttle portion), it is not necessary to form an air hole unlike a conventional barrel made of an extruded body, and the manufacturing process can be shortened. In addition, during heat drawing, even if sink marks occur on the outer surface of the throttle part due to wall thickness fluctuation due to the pen tip holding part equipped with air grooves, the airtight mounting part is not affected by the sink marks and has a proper shape. Can be maintained.

[Brief description of drawings]

FIG. 1 is a longitudinal sectional view of a main part of a first embodiment of the present invention.

2 is a cross-sectional view taken along the line AA of FIG.

FIG. 3 is a longitudinal sectional view of an essential part showing an application example of FIG.

FIG. 4 is a vertical cross-sectional view for explaining the hot drawing of the shaft cylinder of FIG.

FIG. 5 is a longitudinal sectional view of an essential part showing an application example of the second embodiment of the present invention.

6 is a cross-sectional view taken along the line BB of FIG.

FIG. 7 is a longitudinal sectional view of a main part showing a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Shaft cylinder 11 Pen tip 12 Ink occlusion body 2 Cylindrical body 3 Throttling part 4 Airtight mounting part 5 Pen tip holding part 6 Air groove 7 Cap 71 Inner cylinder 72 Outer cylinder 73 Annular seal part 74 Point projection 8 Throttling die 81 Recess 82 core pin 83 annular smooth surface 84 ridge

Claims (3)

[Claims] 1. A tapered portion (3) formed by extruding a synthetic resin into a tip portion of a cylindrical body (2) by heating and drawing.
A barrel (1) of a writing instrument, wherein the airtight mounting part (4) with the cap is integrally formed on the outer surface of the throttle part (3). 2. The barrel of the writing instrument according to claim 1, wherein the airtight mounting portion (4) is an annular smooth surface. 3. A pen tip holder (5) having an air groove (6) axially penetratingly formed integrally with the inner surface of the throttle portion (3), and a diaphragm in front of the pen tip holder (5). The barrel of the writing instrument according to claim 1 or 2, wherein an airtight mounting portion (4) is integrally formed on the outer surface of the portion (3) or the outer surface of the narrowed portion (3) behind the pen tip holding portion (5).