JPH0976293A - Stringing preventing structure for nozzle unit in injection molding machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the generation of a stringing phenomenon upon the separation of a thermosetting resin in the injection port of a nozzle from the tip end of a spool runner. SOLUTION: A plurality of branch holes 28, allowing a cylinder 1 to communicate with a nozzle 3, are bored on the same radius of a flange 22, pinched between the cylinder 1 and the nozzle 3, while a conical projection 27, having a predetermined angle, is projected at the cylinder side of the center of the flange unit and an inserting body 21, having an axial pin 23, whose tip end is aligned with the opening end of the injection port, is interposed at the nozzle side of the center of the flange unit along the axial center of the injection port 4 of the nozzle 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resin injection molding machine, and more particularly to a threading prevention structure for a nozzle portion.

[0002]

2. Description of the Related Art Conventionally, in a resin injection molding machine of this type, as shown in FIG. 6, a thermoplastic resin 2 which is a synthetic resin material which is pressure-fed from an injection molding machine (not shown) through a cylinder 1 is It is attached to the tip of the cylinder 1 and is poured into the cavity from the sprue runner portion 6 of the mold 5 through the spout 4 through the nozzle 3. In addition, the tip of the nozzle 3 and the die 5 are provided in the abutting portion 7 so as to come into contact with a dense pressure without causing resin leakage and to be separated from each other. However, in this conventional nozzle 3, as shown in FIG. 7, the tip of the sprue runner 9 that has been cooled and solidified when the molded product 8 is released from the thermoplastic resin 2 in the nozzle spout 4 is poorly separated, and therefore, the drawing is omitted. As described above, a considerably long fine line-shaped or fibrous thread-drawing portion 10 is generated from the tip of the sprue runner 9 of the molded product 8, and this thread-drawing portion 10 causes the nozzle contact portion 7 of the die 5 or the parting. There is a problem that causes damage such as damage to the die 5 due to adhesion to the surface or clogging of the molded product 8 and occurrence of product defects.

To solve this stringing phenomenon, there are Japanese Utility Model Publication No. 5-332 and Japanese Patent Application Laid-Open No. 7-9493. As disclosed in the former publication, as shown in FIGS. 8 and 9, the partition plate 11 interposed between the tip of the nozzle 3 and the sprue runner portion 6 of the mold 5 has an outer surface 12a of the mold. 5 is formed in a convex surface shape that is in close contact with the contact portion 7 and the inner surface 12b is formed in a concave surface shape that is in close contact with the tip of the nozzle 3. Hole 13 of the same is provided in this hole 13.
A partition 14 for dividing the 3 into two is provided.
The fitting member 15 is formed so as to extend to the inner surface 12b side, and the fitting member 15 is detachably fitted into the spout 4 of the nozzle 3 to attach the partition plate 11. By attaching the partition plate 11 formed in this way to the tip of the nozzle 3 at the spout 4 via the fitting member 15,
After the thermoplastic resin 2 is poured into the mold 5, it is cooled and solidified when the molded product 8 is released from the mold, and the tip of the sprue runner 9 of the molded product 8 and the thermoplastic resin 2 of the spout 4 of the nozzle 3 are separated from each other. 14
The surface area of the resin 2 is increased by being divided by, and the resin 2 is rapidly cooled and solidified by the action of the surrounding cooling atmosphere, and the tip of the sprue runner 9 and the spout 4 are immediately cut to prevent the stringing phenomenon. It is the one.

In the latter publication, as shown in FIGS. 10 and 11, a metal plate 17 is mounted on the tip side of the spout 4 of the nozzle 3 in parallel with the resin flow direction. In the latter case, the same action as that of the former case is exerted to prevent the stringing phenomenon.

[0005]

However, in the former configuration in which the partition plate 11 is mounted, when the nozzle 3 is retracted, the partition plate 11 falls off and must be set each time. Further, since it is sandwiched between the die 5 and the nozzle 3, there is a problem that it is damaged or deformed when the nozzle is touched. In the latter case, since the nozzle 3 and the metal plate 17 are integrated, if the spout 4 is clogged with foreign matter or solidified resin, there is a problem that maintenance becomes difficult. The present invention has been made to solve the above problems, and can prevent the stringing phenomenon of the resin, facilitate maintenance, and reduce the resin flow resistance due to the nozzle. An object of the present invention is to provide a yarn pulling prevention structure for a nozzle portion in an injection molding machine.

[0006]

SUMMARY OF THE INVENTION In order to solve the above technical problems, a first aspect of the present invention is detachably attached to a tip end portion of a cylinder and is brought into close contact with a sprue runner portion of a mold. In a injection molding machine having a nozzle for pouring a thermoplastic resin into a mold from a pouring port, a flange portion held by the cylinder and the nozzle has a plurality of branch holes communicating the cylinder and the nozzle with the same radius. Penetrate upward, and a conical projection of a conical shape with a predetermined angle is projected on the cylinder side at the center of the flange, and the spout of the nozzle is provided on the nozzle side at the center of the flange. The tip of the sprue runner of the molded product, which is cooled and solidified when the molded product is released from the mold, by inserting an insert body that has a shaft pin that is aligned along the axis and the tip of the spout is aligned with the open end of the spout. And heat in the nozzle spout When the resin is separated from the resin, the pin portion of the shaft pin of the insert inserted in the nozzle is positioned along the axis of the spout of the nozzle, and the tip end is aligned with the opening end of the spout. Therefore, due to the small cross-sectional area of the spout, the large thermal conductivity of the insert, and the increased contact area with the thermoplastic resin, the thermoplastic resin in the inlet rapidly cools and solidifies. Therefore, the occurrence of the stringing phenomenon in the separation between the tip of the sprue runner and the thermoplastic resin in the spout of the nozzle is completely eliminated. Further, since the insert body is detachably attached between the cylinder and the nozzle, even if resin is clogged at the tip of the nozzle, maintenance can be easily performed, and the existing injection molding machine can be used. Can also be attached to. Also, the second invention is
The branch hole is a round hole, a square hole, an elliptical hole, and is configured to penetrate along the angle of the conical protrusion, so that the flow resistance of the resin can be reduced and the injection load of the injection molding machine can be reduced. Can be reduced.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a sectional view of a nozzle in a state where a thread-pulling preventing insert 21 according to the present invention is used, and FIG.
1 is a perspective view of the insertion body 21 seen from the rear end side, and FIG. 3 is a perspective view of the insertion body 21 seen from the rear end side. An insertion body 21 for preventing stringing is attached between and.

The insert body 21 is made of a material having a relatively high thermal conductivity, for example, an alloy material such as aluminum or iron, and has a flange portion 2 fitted into the screw hole diameter portion of the cylinder 1.
An axial pin 23 is formed at the center of one surface of the nozzle 2 along the axial center of the nozzle 3, and the axial pin 23 has a taper portion 24 formed at a predetermined angle from the flange portion 22 toward the axial center of the nozzle 3. In addition, a pin portion 25 is formed from the tapered portion 24 so as to extend between the tapered portion 24 and a position substantially aligned with the end portion of the spout 4. Further, on the other surface of the flange portion 22, a fitting convex portion 26 that fits in the inner diameter portion of the cylinder 2 in a cage shape is formed, and the fitting convex portion 26 has a shaft pin 23.
A conical projection 27 having a predetermined angle is formed so as to be aligned with the center of the conical projection 27, and the bottom circle of the conical projection 27 is formed to have a smaller diameter than the bottom circle of the tapered portion 24 of the shaft pin 23. The conical protrusions 27 are fitted around the base of the tapered portion 24 of the shaft pin 23 at a predetermined angle (for example, a predetermined diameter) at a predetermined angle (an angle substantially matching the conical surface of the conical protrusion 27). A plurality of branch holes 28 are formed so as to penetrate therethrough.

When the flange portion 22 of the insert body 21 thus formed is inserted into the screw portion 1a of the cylinder 1, the fitting convex portion 26 is fitted into the inner diameter portion of the cylinder 1 and the screw portion 3a of the nozzle 3 is screwed. The flange portion 22 becomes the cylinder 1
And the nozzle 3, the shaft pin 23 is aligned with the axis of the nozzle 3 and the tip 25a of the pin 25 is attached.
Is substantially aligned with the open end of the spout 4 of the nozzle 3.

In such a structure in which the insert 21 is interposed between the cylinder 1 and the nozzle 3, the thermoplastic resin 2 is poured into the mold 5 and then cooled and solidified when the molded product 8 is released. The tip of the sprue runner 9 of the molded product 8 and the thermoplastic resin 2 in the spout 4 of the nozzle 3 are separated. In this case, the pin portion 25 of the shaft pin 23 of the insert body 21 inserted in the nozzle 3 is positioned along the axis of the spout 4 of the nozzle 3, and the tip portion 25a is aligned with the opening end of the spout 4. Therefore, the cross-sectional area of the spout 4 is small, and the insertion body 21 has a large thermal conductivity and the contact area with the thermoplastic resin 2 is increased. Since the thermoplastic resin 2 is rapidly cooled and solidified, no stringing phenomenon occurs when the tip of the sprue runner 9 and the thermoplastic resin 2 in the spout 4 of the nozzle 3 are separated.

Further, a conical projection 27 having a conical shape is provided on the cylinder 1 side of the insert body 21, and the flange portion 22 is provided.
Since the branch hole 28 is provided at an angle substantially matching the conical surface of the conical projection 27, the flow resistance of the resin 2 can be reduced and the injection load of the injection molding machine can be reduced. You can In addition, the insert 21 is the cylinder 1
Since it is configured to be detachably attached between the nozzle and the nozzle 3, maintenance can be easily performed even if resin is clogged at the tip of the nozzle 3, and the nozzle is attached to an existing injection molding machine. be able to.

In the above embodiment, the branch hole 28 formed in the flange portion 22 is illustrated as a circular shape, but the present invention is not limited to this, and for example, as shown in FIGS. The hole 30 or the elliptical hole 31 may be used. Moreover, in order to reduce the flow resistance of the resin 2, FIG.
As shown in (b), it is preferable that the opening ends of the holes 28, 30, 31 on the cylinder 1 side are provided with a C surface or an R surface.

[0013]

As described above, according to the present invention, in the case where the tip of the sprue runner of the molded product which is cooled and solidified when the molded product is released from the thermoplastic resin in the spout of the nozzle is separated by the above-mentioned constitution. In the above, since the pin portion of the shaft pin of the insert inserted in the nozzle is positioned along the axis of the spout 4 of the nozzle, the tip end is aligned with the opening end of the spout,
Due to the small cross-sectional area of the spout and the large thermal conductivity of the insert and the increased contact area with the thermoplastic resin, the thermoplastic resin in the inlet is rapidly cooled and solidified. Therefore, no stringing phenomenon occurs when the tip of the sprue runner is separated from the thermoplastic resin in the spout of the nozzle. In addition, a conical conical projection is provided on the cylinder side of the insert, and a branch hole is provided in the flange at an angle that approximately matches the conical surface of the conical projection. Can be reduced and the injection load of the injection molding machine can be reduced. In addition, since the insert is configured to be detachably attached between the cylinder and the nozzle, even if resin is clogged at the tip of the nozzle,
It can be easily maintained and can be attached to existing injection molding machines.

[Brief description of drawings]

1 is a cross-sectional view of a nozzle using an insert of the present invention.

FIG. 2 is a perspective view of the insert seen from the distal end side.

FIG. 3 is a perspective view of the insert seen from the rear end side.

FIG. 4 is a perspective view showing another embodiment of (a) and (b) branch holes.

5 (a) and 5 (b) are cross-sectional views showing the shape of the opening edge of the branch hole.

FIG. 6 is a cross-sectional view of a state in which a nozzle tip of a conventional injection molding machine is in contact with a mold.

FIG. 7 is a perspective view showing an example of a conventional molded product that has been released.

FIG. 8 is a cross-sectional view of a nozzle provided with a conventional means for preventing the stringing phenomenon.

9 is a perspective view of a partition body which is a means for preventing the stringing phenomenon in FIG.

FIG. 10 is a cross-sectional view of a nozzle provided with another conventional threading phenomenon preventing means.

11 is a front view of the nozzle tip side of FIG.

[Explanation of symbols]

 1 Cylinder 2 Thermoplastic Resin 3 Nozzle 4 Spout 5 Mold 6 Sprue Runner 21 Insert 22 Flange 23 Shaft Pin 24 Taper 25 Pin 27 Conical projection 28, 30, 31 Branch hole

Claims (2)

[Claims] 1. An injection molding machine having a nozzle detachably attached to a tip end portion of a cylinder, which is in close contact with a sprue runner portion of a mold and pours a thermoplastic resin into a mold from a pouring port, A plurality of branch holes that communicate the cylinder and the nozzle are provided through the same radius in the flange portion sandwiched by the cylinder and the nozzle, and a predetermined angle is provided on the cylinder side at the center of the flange portion. A conical projection with a conical shape is projected,
On the nozzle side at the center of the flange portion, there is provided an insert body having a shaft pin along the axis of the spout of the nozzle and having the tip end aligned with the opening end of the spout. Threading prevention structure for the nozzle part of the injection molding machine. 2. The nozzle part in the injection molding machine according to claim 1, wherein the branch hole is a round hole, a square hole, an elliptical hole, and is formed so as to penetrate along the angle of the conical projection. No string pulling structure.