JPH07186240A - Extruder of ink-containing pipe for writing implement - Google Patents

Abstract

PURPOSE:To prevent a residue of thermal decomposition of a resin from being stuck on the surface of a torpedo during extrusion and to prevent a vertical flaw from being generated on the inner wall surface of a molded ink-containing pipe by performing a surface treatment for the conical part of the torpedo and the cylindrical part of the tip by a fluoeoresin. CONSTITUTION:A surface treatment (f) of a fluoeoresin is performed in the whole length of the conical part 2b of a torpedo 2 and the cylindrical part 2c of the tip thereof. A residue of resin is easily stuck extremely in the part shown in the shaped portion. On one side, silicon oil Si is sent into a passage 5 of silicon oil and allowed to flow out through an outflow port 6 during extrusion. When resin (r) is extruded by an extrusion screw 4 and passed through the mandrel part 2a of the torpedo 2, silicon oil S1i flows from a boundary part 2d together with resin (r) while covering the surface of the torpedo 2. Resin (r) smoothly flows on the surface of the torpedo 2 by silicon oil Si.

Description

Detailed Description of the Invention

[0001]

[Application field] An extrusion molding device for an ink storage tube of a writing instrument.

[0002]

2. Description of the Related Art Conventionally, a writing instrument manufactured by extrusion molding, for example, an ink container 9 (FIG. 4) of a ball-point pen, often has vertical scratches 9 on its inner wall surface. The reason for this will be described below with reference to FIGS. 1, 2, 3 and 4. That is, when the resin r extruded by the extruding screw 4 receives pressure in the extrusion molding machine 1 and heat is applied, pyrolytic debris is generated, and the debris adheres to the conical portion 2b and the tip cylindrical portion 2c of the toe bead 2. Tend. The reason for this is considered to be that, after passing through the mandrel portion 2a of the toe bead 2, in the conical portion 2b, the diameter of the cylindrical resin is reduced and the heating temperature is increased, so that pyrolytic debris is generated. Then, the dust attached to the conical portion 2b and the tip cylindrical portion 2c forms a vertical scratch 9 on the inner wall surface of the ink containing tube 9.

[0003]

[PROBLEMS TO BE SOLVED] To eliminate vertical scratches 9 that have conventionally occurred on the inner wall surface of an ink containing tube 9 of a writing instrument that is extruded.

[0004]

[Technical Means] The surface of the conical portion 2b following the mandrel portion 2a of the toe bead 2 of the extrusion molding machine 1 and the surface of the tip end cylindrical portion 2c are treated with a fluororesin surface f, and silicon is applied to the boundary portion 2d between the conical portion 2b and the mandrel portion 2a. An extrusion molding device for an ink storage tube of a writing instrument in which the oil outlet 6 is opened and the silicone oil outlet 6 communicates with the silicone oil passage 5.

[0005]

Since the surfaces of the conical portion 2b and the tip end cylindrical portion 2c of the toe bead 2 are treated with a fluororesin, the pyrolysis residue of the extruded resin r does not adhere to the surface of the toe bead 2. Further, the silicone oil Si coats the fluororesin-treated surface f to smoothen the flow of the resin r.

[0006]

EXAMPLES Examples of the present invention will be described below. 1 and 2, 1 is an extrusion molding machine, 2 is a tobeed,
It comprises a mandrel portion 2a, a conical portion 2b, a tip cylindrical portion 2c, and a boundary portion 2d between the mandrel portion 2a and the conical portion 2b. Reference numeral 3 is a breaker, 4 is an extrusion screw, 5 is a passage for the silicon oil Si, and 6 is an outlet for the silicon oil Si opened at the boundary 2d.

Reference numeral f denotes a fluororesin-treated surface, which is formed by coating a fluororesin or by welding a fluororesin film on the surface of the toe bead 2. The fluororesin-treated surface f is formed over the entire length of the conical portion 2b and the tip cylindrical portion 2c. The fluororesins used are shown in Table 1.

[Table 1] PTFE and PFA in the fluororesin shown in Table 1 are particularly preferable, and prevent the residue from adhering to the surface of the toe bead even when the extruded resin has a high temperature.

In FIGS. 3, 4 and 5, 7 is a chip,
Reference numeral 8 is a ball, and 9 is an ink container, which is made of polyethylene, polypropylene or the like. Reference numeral 9a is a vertical flaw in the ink containing tube. S is a slit between the tip 7 and the ink containing tube 9.

The operation will be described below. The conical portion 2b and the tip cylindrical portion 2c of the toe bead 2 are subjected to fluororesin surface treatment f over their entire length. This is because resin dust is most likely to adhere to the shaded portion of FIG. 1 from the conventional experience.

On the other hand, the silicone oil Si is fed into the silicone oil passage 5, and the silicone oil Si is extruded from the outlet 6 during the extrusion molding. Then, the resin r is extruded by the extruding screw 4, and the mandrel portion 2 of the toe bead 2 is extruded.
After passing through a, the silicon oil Si flows from the boundary 2d together with the resin r while covering the surface of the toe bead 2. Thus, the resin r smoothly flows on the surface of the toe bead 2 by the silicon oil Si.

Even when the resin r comes into contact with the surface of the toe bead 2, the fluororesin surface treatment section 4 prevents the residue from adhering to the surface of the toe bead 2. Therefore, the molded ink containing tube 9 does not cause vertical scratches 9a on its inner wall surface.

[0012]

EFFECTS OF THE INVENTION (a) Since the conical portion 2b and the tip cylindrical portion 2c of the toe bead 2 are surface-treated with a fluororesin, the resin r
No thermal decomposition residue adheres to the surface of the toe bead 2 during extrusion molding. Therefore, vertical scratches 9a do not occur on the inner wall surface of the molded ink containing tube 9.

(B) Silicon oil Si is applied to the boundary portion 2d
Since the resin r is made to flow out from it, the flow of the resin r is smoothed, and adhesion of dust to the surface of the toe bead 2 due to thermal decomposition of the resin is prevented.

[Brief description of drawings]

FIG. 1 is a sectional view of the device of the present invention,

FIG. 2 is a side view of the toe bead 2,

FIG. 3 is a cross-sectional view of the ink containing tube 9,

FIG. 4 is a perspective view of the ink containing tube 9,

FIG. 5 is a sectional view of a slit S portion,

[Explanation of symbols]

1: Extruder, 2: Toe bead, 2a: Mandrel part, 2b: Conical part, 2c: Tip cylindrical part, 2d: Boundary part,
3: Breaker, 4: Extrusion screw, 5: Silicon oil passage, 6: Silicon oil outlet, 7: Chip,
8: Ball, 9: Ink storage tube, 9a: Vertical scratch, i: Ink, Si: Silicon oil, r: Resin, S: Slit.

Claims (1)

[Claims] 1. A surface of a conical portion 2b following a mandrel portion 2a of a toe bead 2 of an extrusion molding machine 1 and a surface of a tip end cylindrical portion 2c are treated with a fluororesin surface f, and silicon is applied to a boundary portion 2d between the conical portion 2b and the mandrel portion 2a. An extrusion molding device for an ink container of a writing instrument, wherein the oil outlet 6 is opened, and the silicone oil outlet 6 communicates with the silicone oil passage 5.