JPS6359395B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method of manufacturing a plastic pen body. More specifically, an annular portion consisting of a ring in which a large number of filaments and brittles made of thermoplastic resin are fused to each other, and a protruding portion adjacent to and protruding centripetally from the inner periphery of the annular portion; The present invention relates to a method of manufacturing a rod-shaped pen body having a cross-sectional shape in which a gap serving as an ink conduction path is formed between the protruding portions.

BACKGROUND TECHNOLOGY Conventionally, in a method for manufacturing a rod-shaped pen body, in which a thermoplastic resin in a molten state is extruded from a die provided with a large number of holes, the resin is brought into contact with each other and fused together to form a rod-shaped pen body. The nozzle part for forming the part and the nozzle part for forming the protruding piece are arranged on the same level without being separated (for example,
(See the respective implementation drawings of JP-A-51-21927 and JP-A-51-70023). Therefore, the molten resins extruded from the holes are successively fused in the same region through the same process, forming an outer shell annular part and a protruding piece protruding inward from the inner wall of the annular part, thereby forming a pen. make up the body.

Problems to be Solved by the Invention Therefore, the formation of the outer shell annular portion and the formation of the protruding pieces are as follows:
Since they are inseparable, they mutually influence each other's sensitivity, and there are various restrictions when arranging each other's holes. For example, in the configuration of the outer shell annular portion to maintain the shape and arrangement of the protruding pieces involved in the ink flow function and the durability function, if one function is not satisfied, the other will be adversely affected, and both It was difficult to satisfy the functions. In addition, it has been difficult to manufacture a stable and highly accurate pen body because variations in extrusion conditions and variations in perforation accuracy directly affect the melting of the filaments in the inner and outer layers.

The present invention eliminates the problems caused by the conventional manufacturing method described above, and also uses thermoplastic resins with various melting characteristics, such as those with little expansion when discharged from each hole of the nozzle part, and those with melt viscosity ranging from low to high. Materials with low melt elasticity such as thermoplastic resins, metal powders such as aluminum powder, pigment powders such as titanium oxide, ceramic powders, lubricants such as boron nitride, and other fillers blended with thermoplastic resins may also be removed from the nozzle. This invention discloses a method for manufacturing rod-shaped pen bodies made of various materials and having various performances by ensuring mutual fusion of discharged molten resin.

Means for Solving the Problems (and Effects) The method for manufacturing a pen body according to the present invention involves extruding a thermoplastic resin in a molten state from a die provided with a large number of holes, and bringing the thermoplastic resin into contact with and fusing with each other, In manufacturing a rod-shaped pen body whose diameter is reduced to a desired diameter, a molding die with a specific structure is used to extrude and form the outer shell annular portion and the protruding pieces in distinct areas within a single die, while forming the outer shell. Contact the inner wall of the annular part with the proximal end of the protruding piece,
It is characterized in that it is self-attached and then stretched to produce a rod-shaped pen body of a desired diameter.

The invention will be explained below with reference to the drawings.

The molding die 1 used in the present invention has a nozzle part 8 for forming a protruding piece located at the axis and at the front end, and a nozzle part 9 for forming an outer shell annular part located concentrically with the outer layer and behind the nozzle part. and an annular three-dimensional space 12 formed on the front surface of the nozzle part.

Specifically, it is convenient to construct the above-mentioned molding die by assembling the inner mold 2 and the outer cylindrical mold 11 in a connected manner. The internal mold 2 leaves the top surface of a columnar protrusion 4 with a circular or polygonal cross section extending vertically in the center of the base plate 3, and has a hollow hole 5 penetrated therein. A large number of holes 6 are arranged in multiple layers on the top surface, and a large number of holes 6 are arranged in at least one layer on the drilled protrusion piece forming nozzle part 8 and the base plate located on the outer layer of the proximal end of the columnar protrusion 4. , a nozzle portion 9 for forming an outer shell annular portion is provided.

On the other hand, the outer cylindrical mold 11 is a cylindrical body in which a columnar hole 10 having a circular or polygonal cross section is penetrated, and the outer cylindrical mold 11 is designed to contain the columnar protrusion 4 of the inner mold 2 concentrically therein. The molding die 1 is constructed by connecting them as shown in FIGS. 1 and 4.

In this way, an annular three-dimensional space is formed between the outer circumferential wall of the columnar projection and the inner circumferential wall of the outer cylinder mold.

The molding die can be constructed by connecting and assembling the inner mold and the outer cylinder mold as described above, but is not limited to this, and any die for forming protruding pieces that satisfies the above-mentioned requirements. Any structure may be used as long as it has a nozzle part, a nozzle part for forming an outer shell annular part, and an annular three-dimensional space part. For example, the inner mold and the outer cylindrical mold may not be separate bodies, but may be formed integrally by metal processing, mold processing, etc., or may be formed by partially joining them.

The molding die configured as described above is attached to the discharge section of an extrusion molding machine (not shown) and used for manufacturing.

The molten thermoplastic resin is introduced through each hole of the annular part forming nozzle part, and is brought into close contact with each other within the annular three-dimensional space to form a close-packed, substantially non-porous annular fused body. Extruded. On the other hand, at the same time, the molten resin introduced from the internal hollow hole of the columnar protrusion of the shaft center is discharged from each hole of the protrusion piece forming nozzle part, and is instantly brought into contact with and fused with each other to form a protrusion piece. At this time, the proximal end of the protruding piece instantly comes into contact with the inner wall of the annular fused body and is fused and integrated, forming a desired rod-shaped pen body.

The annular three-dimensional space is designed to close-pack the molten resin introduced from each hole of the nozzle for forming the outer shell annular part in this limited space to form a substantially non-porous annular fused body and extrude it. Contribute to As shown in Fig. 4, the diameter of the inner post hole in the outer cylinder mold is gradually reduced toward the front end, or the projection is extended to make the diameter smaller. The discharge pressure is increased by reducing the diameter of the discharge side of the three-dimensional space,
It can function even more effectively.

In addition, in order to more effectively fuse the proximal end of the protruding piece with the inner wall of the outer shell annular part in the manufacturing process, a columnar protruding body 4 is used as shown in FIGS. 4 and 5.
An appropriate number of conductive holes 7 can be provided to communicate the internal hollow hole 5 and the annular three-dimensional space 12.

In the manufacturing process of the present invention, the ink conduction path 16
In order to secure a space where the amount of air is reduced, conventionally known means such as blowing air through the air introduction pipe 17 and discharging it from the air discharge hole 18 are applied. In addition, the holes arranged and drilled in the nozzle part are designed to ensure that the molten self-adhesive resins come into contact with each other and are fused.
As shown in the figure, the discharge direction of the holes is enlarged, or on the discharge side of the die, a part of the part between the holes is cut out as shown in Figures 10 and 11, and a means is used to make the holes communicate with each other. , as shown in Figures 8 and 9,
It is also possible to provide a slit or the like to communicate between the holes.

Examples will be described in more detail below.
Pen body with the cross-sectional shape shown in Figure 12 (Example 1)
In this case, dies drilled in the arrangement illustrated in FIG. 2 are used. Specifically, in the nozzle part 9 for forming the outer shell annular portion, 36 holes with diameters of 0.45 mm and 0.43 mm are arranged on concentric circles with diameters of 7.4 mm and 6.4 mm, respectively, at equal intervals and on each circle. The holes are arranged at positions corresponding to the middle of each hole on the other circle, and on the other hand, the protruding piece forming nozzle part 8 has four holes arranged centripetally on the sixth equal line passing through the center. Groups of holes arranged in rows of 1 and groups of holes arranged in a cross pattern of 7 are arranged alternately.

This die is attached to the cylinder of an extrusion molding machine, heated to 180°C, extruded the molten polyacetal resin, and the resulting large number of monofilaments are fused together and stretched to form a rod with the cross-sectional shape shown in Figure 12. I got a body.

This rod-shaped body has an outer diameter of 0.60 mm and a cross-sectional shape consisting of an outer shell annular portion 14 and a protruding piece 13, and a gap serving as an ink guide path 16 is formed between these members. The annular part has a thickness of 0.09 mm and is composed of filaments fused together in a close-packed state.
The resin filling rate in the annular portion is 100%, and the outer periphery is approximately circular.

As shown in FIG. 13 (Example 2), a pen body having a cross-sectional shape in which the inner wall of the outer shell annular portion is formed with a rough surface consisting of finely uneven stripes is manufactured using the die shown in FIG. 3. This die is formed by forming a large number of fine unevenness lines 15 in the axial direction on the outer peripheral wall of the columnar projection 4, and differs from the die shown in FIG. 2 only in this point. The pen body is manufactured in the same manner as described above.

The pen body shown in Fig. 14 is another example, and has four independent ink passage spaces separated by protruding pieces, and during manufacturing, air is introduced into positions corresponding to each space. Stretch molding is performed while blowing air through the tube 17.

Effects of the invention Compared to a manufacturing method using a conventional molding die (in which a nozzle part for forming an outer shell annular part and a nozzle part for forming a protruding piece are arranged on the same die plane), the extrusion conditions can be reduced. Needless to say, there is a large tolerance for variations in the flow rate and drilling accuracy, and thermoplastic resins with various melting characteristics, such as those that expand little when discharged from each hole in the nozzle, and those that have a low melt viscosity. Nozzle This method ensures the fusion of the molten resin discharged from the molten resin, making it possible to reliably manufacture a series of rod-shaped pen bodies made of various materials and with various performances. A fused, virtually non-porous, high-strength pen body, and a pen body with an improved affinity for ink (wettability), which has a rough surface consisting of a large number of fine irregularities on the inner wall of the annular portion. can be manufactured with high efficiency.

[Brief explanation of the drawing]

1 and 4 are longitudinal sectional views of the molding die, FIG. 2 is a plan view of FIG. 1, FIG. 3 is a plan view of the die for forming uneven stripes, and FIGS. 12 and 13. The figure is an enlarged sectional view of a pen body manufactured by the die, FIG. 14 is an enlarged sectional view of another example of a pen body, FIG. 5 is a plan view of FIG. 4, and FIGS. FIG. 10 is a vertical cross-sectional view of a main part of the nozzle portion for forming a protruding piece, and FIGS. 7, 9, and 11 are plan views of each of the nozzle portions. 1... Molding die, 2... Internal mold, 3...
Base plate, 4... Column-shaped protrusion, 5... Hollow hole, 6...
Hole, 7... Conduction hole, 8... Nozzle part for forming protruding piece, 9... Nozzle part for forming outer shell annular part, 10...
Columnar hole, 11...Outer cylinder mold, 12...Annular three-dimensional space part, 13...Protrusion piece, 14...Outer shell annular part, 1
5... Fine uneven stripes, 16... Ink conduction path, 1
7...Air introduction pipe, 18...Air discharge hole, 19...
...Small void.

Claims (1)

[Scope of Claims] 1. Manufacturing of a rod-shaped pen body in which thermoplastic resin in a molten state is brought into contact and fused together in the process of extruding it from a die provided with a large number of holes, thereby reducing the diameter to a desired diameter. In this method, the top surface of a columnar protrusion 4 extending vertically in the center of the base plate 3 is left, a hollow hole 5 is penetrated therein, and a large number of holes 6 are arranged and drilled in multiple layers on the top surface. At the same time, a large number of holes 6 are arranged and bored in at least one layer on the base plate 3 located at the outer layer of the proximal end of the columnar protrusion 4 to form a ring-shaped part. An outer cylindrical mold 11 having a columnar hole 10 penetrating the outer edge of the nozzle portion 9 for forming an annular portion is inserted into the inner mold 2 in which the nozzle portion 9 for forming the annular portion is formed, and the columnar protrusion 4 is concentrically inserted therein. For forming the annular portion, a molding die 1 is connected to form an annular three-dimensional space 12 between the outer circumferential wall of the columnar protrusion 4 and the inner circumferential wall of the outer cylindrical mold 11. The molten resin introduced from each hole 6 of the nozzle part 9 is brought into close contact with each other in the annular three-dimensional space part 12, and is discharged as a close-packed, substantially non-porous annular fused body, and the protruding piece contact with the base ends of the protruding pieces 13 that are discharged from the forming nozzle part 8 and are fused and formed with each other;
A method for manufacturing a plastic pen body, which is characterized in that the body is formed while being fused. 2. A method of manufacturing a plastic pen body according to claim 1, using a molding die 1 in which a large number of fine unevenness lines 15 in the axial direction are formed on the outer peripheral wall of the columnar projection 4.