JPH1170774A - Shaft tube of writing utensil - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the uneven wall thickness of a shaft tube from developing by a method wherein a molding is performed with a mold assembly having hot runners in the state that a valve pin is buried in a molding in a valve gate system. SOLUTION: This shaft tube 1 is molded with a mold assembly 2 having hot runners. Under the condition that a fixed die 3 and a movable die 8 are closed together, a thermoplastic resin flows through a primary nozzle 18 to a primary spool 4 and a runner 5 so as to pass through a gate 19 having a bore of 1.2 mm toward a core pin 12 in order to fill within the mold 14 of a shaft tube main body, resulting in molding the shaft tube main body 13. In order to prevent the uneven wall thickness of the shaft tube main body due to the curving of the core pin caused by the abutting of a resin against the core pin 12 from developing, a back-up pin 20 is attached to the opposite side of a gate 19 to the runner under the condition being pinched with the core pin 12 between in the state that the tip of the back-up pin 20 is abutted against the core pin 12.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a writing implement for forming a two-colored shaping cylinder of a writing implement having a rubber-like non-slip member inserted into a grip portion of a barrel body using a hot runner mold device. Related to the barrel.

[0002]

2. Description of the Related Art Conventionally, there has been known a technique of forming a barrel of a writing instrument in which a rubber-like anti-slip member is inserted into a grip portion of a barrel body by two-color molding. A writing instrument barrel is also provided. In a molded product, a gate residue, which is a trace of a gate, is generated. In a case where the gate residue protrudes, a finger or the like may touch the gate remainder and damage the finger. In order to prevent such a situation, a gate residue is removed in a later step.

Recently, two-color molding using a hot runner mold device has been attempted so as not to require such a post-process and to prevent a protruding gate residue.

[0004]

As shown in FIG. 1, a two-color molding hot runner mold apparatus is used to mold a barrel body, as shown in FIG. The gate 19 is inserted into a mold (space) of the shape of the barrel body formed on the fixed die 3 and the movable die 8 around the gate.
Is formed by flowing the resin. At that time, it has been found that the core pin is curved because the resin vigorously comes into contact with the core pin, thereby causing a problem that the thickness of the wall of the barrel body is uneven.

The present invention has been made to solve the above-mentioned problem. The present invention has been made by using a hot runner mold device to connect a writing instrument barrel having a rubber-like non-slip member inserted into a grip portion of the barrel body.
An object of the present invention is to provide a writing tool barrel in which the wall thickness of the barrel does not have uneven wall thickness formed by color molding.

[0006]

SUMMARY OF THE INVENTION The present invention relates to a writing instrument having a rubber-shaped non-slip member inserted into a grip portion of a barrel body, and a gate for molding the barrel body. A hot runner with a backup pin provided at a position opposite to the grip part and opposite to the gate across the core pin, with the tip abutting the core pin so that the core pin is not displaced by the flow of resin from the gate And a two-color molding using the above-mentioned mold apparatus.

When a hot runner mold apparatus is used to form a valve pin in a state where it is inserted into a molded product by a valve gate method, traces of the gate are recessed, and a gate residue protruding from the surface of the molded product is formed. Does not occur, so that a post-process for removing the remaining gate is not required. Also, in molding the barrel body, the gate is provided at the position of the core pin corresponding to the grip portion of the barrel body, and the backup pin is provided on the opposite side facing the gate, so that the trace of the gate is a rubber-like non-slip member. The through-hole formed in the molded product due to the contact of the tip of the backup pin with the core pin can also be covered with the non-slip member.

The diameter of the backup pin may be any diameter as long as it can support the core pin so as not to bend with respect to the flow pressure of the resin, and may be set appropriately. Further, the position at which the backup pin is provided is not limited to the position facing the gate, but may be any position at which the core pin does not bend with respect to the flow pressure of the resin. Well, it can be determined appropriately.

[0009]

Embodiments of the present invention will be described with reference to the drawings. The barrel 1 of the writing instrument of the present invention is formed by attaching a hot runner mold device 2 having a conventionally known structure to a molding machine (not shown).

As shown in FIG. 1, a heater (not shown) for heating the spool 4 and the runner 5 is provided on the fixed side die 3 on a primary side on the left side and a secondary side on the right side as viewed in the figure. )
Is provided, and the spool 4 and the runner 5 are heated to keep the resin material therein in a fluidized state without solidifying. 7 is a heater section. A rotary unit 10 having an ejector mechanism 9 is rotatably provided between the fixed die 3 and the movable die 8 via a rotary shaft 11 connected to a molding machine. The ejector mechanism 9 has a core pin 12 attached thereto.
The fixed side die 3 and the movable side die 8 form a mold (space portion) 14 having the shape of the barrel body 13 on the primary side. On the secondary side, a state in which the anti-slip member 16 is inserted into the grip portion 15 of the barrel body 13, that is, a mold (space portion) 17 having the shape of the barrel 1 is formed.

First, in a state where the fixed die 3 and the movable die 8 are closed, a thermoplastic resin flows from the primary nozzle 18 to the primary spool 4 and the runner 5 to reduce the diameter to 1.
The shaft cylinder body 13 is formed by filling the interior of the mold 14 of the barrel body from the 2 mm gate 19 toward the core pin 12. When the resin collides with the core pin 12, the distal end of the core pin 12 contacts the core pin 12 on the opposite side of the gate 19 so as to prevent the core pin 12 from bending and the wall of the barrel body from knitting, so that the core pin 12 is backed up. A pin 20 is provided.

As shown in FIG. 2, a shaft cylinder main body 13 formed on the primary side is set on the secondary side mold. A thermoplastic elastomer or the like flows through the spool 4 and the runner 5 on the side of the cylinder, and a gate 22 having a diameter of 0.8 mm formed at the position of the grip portion 15 of the cylinder body 13 is used to form the mold of the cylinder 1 (actually, The space is filled only in the non-slip member 16) 17 to form the barrel 1 in which the non-slip member 16 is inserted into the grip 15 of the barrel body 13 as shown in FIG.

In molding the non-slip member 16 to be inserted into the grip portion 15 of the primary-side barrel body 13 and the secondary-side barrel body 13, resin is filled from each of the gates 19 and 22. As shown in FIG. 3, the valve pin 24 inside the runner 5 is moved by the valve cylinder 23 attached to the mold 2 of the hot runner, and the tip is moved to each gate 1.
9, 22 and inserted into the dies 14, 17;
The gates 19 and 22 are closed by the valve pins 24 to stop filling and then molded. Therefore, the portion of the grip portion 15 of the barrel body 13 facing each of the gates 19 and 22 and the non-slip member 1
A dent (not shown) occurs as a trace in the portion of No. 6.

Next, as shown in FIG. 4, the rotating shaft 11 which can move back and forth in the direction of the arrow is retracted, and the fixed die 3 and the movable die 8 are opened. The barrel cylinder 1, which is a molded product on the secondary side, is actuated (opened) by the ejector mechanism 9 so that the barrel cylinder 1 can be taken out, and is automatically removed by an automatic machine (not shown). Thereafter, the rotating shaft 11 is moved 18
The rotation unit 10 also rotates by reciprocating rotation of 0 degree, so that the barrel body 13 molded on the primary side is on the secondary side, and the core pin 12 from which the secondary barrel 1 is removed is on the primary side. Rotate and move. Next, the rotating shaft 11 moves forward, the fixed die 3 and the movable die 8 close, and the above-described operation is repeated.
The barrel 1 of the writing implement of the present invention is formed by two-color molding.

[0015]

According to the present invention, as described above, since the writing implement main body and the non-slip member are formed in two colors by shaping the writing implement main body, uneven wall thickness does not occur on the wall of the writing implement main body, and the strength of the shaft cylinder is improved. Is obtained. Therefore, no production failure due to uneven thickness occurs. In addition, since the through-hole formed in the barrel body by providing the backup pin is provided in the grip portion covered with the non-slip member, the through-hole is not exposed to the outside, and in design. There is no adverse effect.

[Brief description of the drawings]

FIG. 1 is a plan cross-sectional view of a mold of a hot runner attached to a molding machine in the manufacture of a barrel for a writing instrument of the present invention, showing a state in which the mold is closed and a resin is filled.

FIG. 2 is an enlarged view of a secondary side portion of a mold of the hot runner in FIG. 1 and is a diagram showing a state before a resin for a non-slip member is filled with resin.

FIG. 3 is an enlarged view of a secondary side portion of a mold of a hot runner, showing a state in which resin for a non-slip member is completely filled (a state in which a gate is closed).

FIG. 4 is a view showing a state in which a mold of the hot runner in FIG. 1 is opened.

[Theory of code]

 DESCRIPTION OF SYMBOLS 1 Shaft barrel of writing implement 2 Mold device of hot runner 4 Spool 5 Runner 12 Core pin 13 Shaft barrel body 15 Handle part 16 Non-slip member 19 Primary gate 20 Backup pin 22 Secondary gate

Claims (1)

[Claims] 1. A shaft barrel of a writing instrument in which a rubber-like anti-slip member is inserted into a grip portion of a barrel body, a gate for molding the barrel body is positioned at a position facing the grip portion of the barrel body. Provided,
Two-color molding using a hot runner mold device with a backup pin with the tip abutting on the core pin so that the core pin is not displaced by the flow of resin from the gate at the position opposite to the gate with the core pin in between A shaft barrel for a writing implement characterized by the following.