WO2018074080A1

WO2018074080A1 - Nozzle for injection molding machine

Info

Publication number: WO2018074080A1
Application number: PCT/JP2017/031583
Authority: WO
Inventors: 信二後藤
Original assignee: Nok株式会社
Priority date: 2016-10-18
Filing date: 2017-09-01
Publication date: 2018-04-26
Also published as: CN109414855A; CN109414855B; JPWO2018074080A1; JP6732036B2

Abstract

In order to achieve a reduction in curing of a molding material and the accumulation of a cured product in a nozzle (2) for an injection molding machine, a synthetic resin nozzle head (21) is provided, said nozzle head being attached to the tip end of a cylinder (3) of an injection molding machine that injects a thermosetting liquid molding material into a metal mold (1), and being capable of abutting against a nozzle abutting surface (1b) of the metal mold (1), said nozzle abutting surface opening to a sprue (1a). Furthermore, a metal sleeve (22) is provided, said sleeve being inserted into an inner peripheral hole (21a) of the nozzle head (21), abutting against the cylinder (3), which is held at a low temperature, and corresponding to a flow channel of the liquid molding material.

Description

Nozzle for injection molding machine

The present invention relates to an injection molding machine nozzle, and more particularly to an injection molding machine nozzle suitable for molding with a liquid thermosetting rubber or thermosetting resin.

As a molding apparatus for performing primary vulcanization using thermosetting liquid rubber as a molding material, there has been conventionally known a molding apparatus as shown in FIG. In the molding apparatus shown in FIG. 4, reference numeral 100 is a mold in which a cavity (not shown) that is a shaping space for liquid rubber, a sprue 101 that leads to the cavity, and a nozzle contact surface 102 at the end of the opening are formed. is there. Reference numeral 200 is a nozzle of an injection molding machine that injects and fills thermosetting liquid rubber into the cavity of the mold 100 through the sprue 101.

In this type of molding apparatus, when thermosetting liquid rubber is used as a molding material, the mold 100 is usually kept at a high temperature necessary for vulcanization (curing) of the liquid rubber, while the nozzle of an injection molding machine. No. 200 is kept at a low temperature so that the liquid rubber does not cure inside.

However, if the temperature of the tip of the nozzle 200 rises above a certain temperature due to heat conduction from the mold 100 when it contacts the nozzle contact surface 102 of the mold 100, the opening end 201 of the nozzle 200. In this case, the curing of the liquid rubber is promoted. In particular, when the liquid rubber contains an adhesive component, an adhesive reaction proceeds by heating, and therefore, a hardened rubber is easily accumulated in the opening end 201 of the nozzle 200. When such a cured product is sent into the mold 100 together with the liquid molding material, clogging of the gate occurs or the cured product is mixed into the product portion, thereby causing molding defects.

Therefore, measures such as discharging the cured product in the opening end 201 of the nozzle 200 or cleaning the nozzle 200 are taken. However, in order to thoroughly prevent molding defects due to the inclusion of cured products, it is necessary to frequently discharge such cured products and clean the contact portion between the mold and the nozzle, and there is room for improvement. .

JP-A-8-25415

The technical problem of the present invention is to reduce the curing of the molding material and the accumulation of the cured product in the nozzle for the injection molding machine.

One aspect of the nozzle for an injection molding machine according to the present invention is a nozzle contact surface of the mold that is attached to the tip of a cylinder of an injection molding machine that injects a thermosetting liquid molding material into the mold and has an open sprue. A nozzle head made of a synthetic resin that can be in contact with the sleeve, a metal sleeve that is inserted into an inner peripheral hole of the nozzle head and is held at a low temperature, and serves as a flow path for the liquid molding material; Is provided.

According to the present invention, since the nozzle head that contacts the nozzle contact surface of the mold is made of synthetic resin, heat conduction from the mold is suppressed, and the nozzle head is inserted into the inner peripheral hole of the nozzle head. The metal sleeve that forms the flow path of the thermosetting liquid molding material has high thermal conductivity and is cooled by contact with a low-temperature cylinder, so the liquid molding material is cured in the nozzle and the cured product is accumulated. As a result, it is possible to prevent molding defects due to mixing of the cured product, and it is possible to reduce the frequency of discharging the cured product and cleaning the contact portion between the mold and the nozzle. Further, when the molding material contains an adhesive component, the adhesive component has high reactivity with the synthetic resin, and therefore the flow path of the molding material in the nozzle is made of a metal sleeve. As a result, the progress of the adhesion reaction can be avoided.

It is principal part sectional drawing which shows preferable 1st embodiment of the nozzle for injection molding machines which concerns on this invention with a part of metal mold | die. It is principal part sectional drawing which shows preferable 2nd embodiment of the nozzle for injection molding machines which concerns on this invention with a part of metal mold | die. It is principal part sectional drawing which shows preferable 3rd embodiment of the nozzle for injection molding machines which concerns on this invention with a part of metal mold | die. It is a fragmentary sectional view which shows the nozzle for conventional injection molding machines with a part of metal mold | die.

Hereinafter, a preferred embodiment in which the nozzle for an injection molding machine according to the present invention is applied to a nozzle for LIM (Liquid Injection Molding) using a thermosetting liquid rubber as a molding material will be described with reference to the drawings. FIG. 1 shows a first embodiment together with a part of a mold.

In FIG. 1, reference numeral 1 is a mold. The mold 1 includes a cavity (not shown) that is a shaping space for thermosetting liquid rubber, a sprue 1a that is a passage of liquid rubber to the cavity, and a spherical surface that is positioned on the outer periphery of the opening end of the sprue 1a. The nozzle contact surface 1b which makes a concave shape is formed. The mold 1 includes a plurality of divided molds, and is heated to a temperature required for vulcanization (curing) of the liquid rubber, for example, about 150 ° C. by a heater (not shown). Reference numeral 11 is a locating ring that is concentrically disposed on the outer peripheral side of the opening end of the sprue 1 a and is fixed to the mold 1 with a plurality of bolts 12.

In FIG. 1, reference numeral 2 is a nozzle of an injection molding machine that injects and fills liquid rubber into the cavity of the mold 1 through the sprue 1a. The nozzle 2 is attached to the cylinder 3 of the injection molding machine, and a nozzle head 21 whose tip can be brought into contact with the nozzle contact surface 1 b of the mold 1 and a sleeve inserted into the inner peripheral hole 21 a of the nozzle head 21. 22.

Specifically, the nozzle head 21 in the nozzle 2 is made of a synthetic resin having high heat resistance such as PPS (polyphenylene sulfide), MC nylon (polyamide), PEEK (polyetheretherketone). The nozzle head 21 has a molding material injection hole 3 b opened at the tip of the cylinder 3 of the injection molding machine and an inner peripheral hole 21 a concentric with the sprue 1 a of the mold 1. The nozzle head 21 is attached by screwing a female screw hole 21b having an enlarged diameter at one end of the inner peripheral hole 21a into a male screw portion 3a on the outer periphery of the tip of the cylinder 3 of the injection molding machine. The tip surface 21c of the nozzle head 21 is opposed to the nozzle contact surface 1b of the mold 1 so as to be able to contact. The tip surface 21c is a spherical convex surface having a smaller radius of curvature than the nozzle contact surface 1b.

The sleeve 22 is made of a metal having good thermal conductivity such as steel. The sleeve 22 is developed into a disk shape from a cylindrical sleeve main body portion 22 a inserted into the inner peripheral hole 21 a of the nozzle head 21, and an end portion of the sleeve main body portion 22 a opposite to the mold 1. An outwardly facing flange portion 22b sandwiched between the surface 3c and the bottom surface 21d of the female screw hole 21b of the nozzle head 21 is provided.

In the state where the sleeve main body portion 22 a is inserted into the inner peripheral hole 21 a of the nozzle head 21, the sleeve 22 is screwed into the male screw portion 3 a of the cylinder 3 by screwing the female screw hole 21 b of the nozzle head 21. It can be clamped and fixed between the cylinder 3 and the nozzle head 21.

The sleeve 22 may be integrated with the nozzle head 21 in advance. That is, the nozzle 2 can be formed by integrally molding a nozzle head 21 made of synthetic resin and a sleeve 22 made of metal. In this case, the outward flange portion 22 b of the sleeve 22 is exposed from the bottom surface 21 d of the female screw hole 21 b of the nozzle head 21, and when the nozzle 2 is assembled into the cylinder 3, the outward flange portion 22 b becomes the male screw of the cylinder 3. It is made to contact with the front end surface 3c of the part 3a.

The sleeve body 22 a of the sleeve 22 has a length that covers almost the entire inner peripheral hole 21 a of the nozzle head 21. However, the end of the sleeve body 22a opposite to the outward flange 22b is in a position slightly retracted inward from the opening end of the inner peripheral hole 21a of the nozzle head 21. For this reason, as shown in the figure, when the tip end surface 21c of the nozzle head 21 and the nozzle contact surface 1b of the mold 1 are in contact, the sleeve 22 is slightly separated from the nozzle contact surface 1b.

The cylinder 3 of the injection molding machine is made of metal. The outer periphery of the cylinder 3 is, for example, about 5 to 20 ° C. via the inlet 31a and the outlet 31b so that the inner peripheral thermosetting liquid rubber is not scorched (prematurely cured) by heat. A cooling jacket 31 is provided for circulating a refrigerant fluid such as cooling water. The cooling jacket 31 maintains the cylinder 3 in a moderately low temperature state. Reference numeral 32 is an open / close needle that is disposed in the cylinder 3 so as to be movable in the axial direction and opens and closes the molding material injection hole 3 b of the cylinder 3.

In the injection molding process using the injection molding machine including the nozzle 2 of the first embodiment described above, the mold 1 is first clamped, and then the nozzle contact surface 1b of the mold 1 and the nozzle in the nozzle 2 The tip surface 21c of the head 21 is brought into contact with each other. Thus, a liquid rubber supply passage is formed in which the molding material injection hole 3b of the cylinder 3, the inner periphery of the sleeve 22 in the nozzle 2, and the sprue 1a of the mold 1 communicate with each other.

The convex tip surface 21c of the nozzle head 21 has a smaller radius of curvature than the concave nozzle contact surface 1b of the mold 1, and the nozzle head 21 is made of a synthetic resin so that it can be appropriately elastically deformed. Therefore, the opening edge of the inner peripheral hole 21a of the nozzle head 21 and the opening edge of the sprue 1a can be brought into a good close state.

Next, the liquid rubber in the cylinder 3 is liquefied from the molding material injection hole 3 b of the cylinder 3, the inner periphery of the sleeve 22 of the nozzle 2, and the sprue 1 a of the mold 1 by opening (raising) the opening / closing needle 32. It is injected into the cavity in the mold 1 through the rubber supply path.

The nozzle head 21 is in contact with the cylinder 3 cooled by the flow of the refrigerant fluid to the cooling jacket 31. Since the nozzle head 21 made of synthetic resin has low thermal conductivity, the cooling effect due to contact with the cylinder 3 is small. In the liquid rubber injection process, as described above, the nozzle head 21 is brought into contact with the nozzle contact surface 1b of the mold 1 heated to about 150 ° C. At this time, the nozzle head 21 has a small contact area (heat transfer area) and a low thermal conductivity because the convex tip surface 21c has a smaller radius of curvature than the concave nozzle contact surface 1b of the mold 1. Therefore, it does not easily reach a high temperature state.

The metal sleeve 22 forming the liquid rubber supply path on the inner periphery of the nozzle head 21 has high thermal conductivity, and is in contact with the cooled cylinder 3 at the outward flange portion 22b. A moderate low temperature state is maintained by heat exchange with the cylinder 3. In addition, since the end of the sleeve 22 opposite to the outward flange 22b is not in contact with the nozzle contact surface 1b of the mold 1, heat transfer from the mold 1 is effectively blocked. Therefore, the liquid rubber in the nozzle 2 can be prevented from being cured by heat.

Therefore, clogging of the gate due to the rubber cured product generated on the nozzle 2 side being supplied into the mold 1 together with the liquid rubber in the injection process and molding defects due to mixing of the cured product into the product portion are prevented. As a result, the frequency of discharging the cured product in the nozzle 2 or cleaning the nozzle 2 can be reduced.

FIG. 2 shows a second embodiment of a nozzle for an injection molding machine according to the present invention together with a part of a mold. In the nozzle 2 of this embodiment, the difference from the first embodiment described above is that the sleeve 22 is a straight tube and the end of the sleeve 22 opposite to the mold 1 is formed of the cylinder 3. The material is in close contact with the material injection hole 3b. Other parts are the same as those of the first embodiment.

The sleeve main body 22 a of the sleeve 22 presses the press-fit portion 22 c, which is the end opposite to the mold 1, into the molding material injection hole 3 b of the cylinder 3, and then inserts the female screw hole 21 b of the nozzle head 21 into the cylinder 3. It is inserted into the inner peripheral hole 21a of the nozzle head 21 by being screwed into the male screw portion 3a.

The press-fit portion 22c of the sleeve 22 is formed in a taper shape with an inner peripheral surface having a large diameter on the tip side. As a result, an increase in the flow resistance of the liquid rubber is suppressed.

Also in the second embodiment, the metal sleeve 22 forming the liquid rubber supply path on the inner periphery of the nozzle head 21 is in contact with the cooled molding material injection hole 3b of the cylinder 3 at the press-fit portion 22c. ing. Since the opposite end of the sleeve 22 is not in contact with the nozzle contact surface 1 b of the mold 1, heat transfer from the mold 1 is blocked. As a result, the sleeve 22 is maintained in a moderately low temperature state. Therefore, it is possible to prevent the liquid rubber in the nozzle 2 (sleeve 22) from being cured by heat, so that a cured product of the rubber generated on the nozzle 2 side is contained in the mold 1 together with the liquid rubber in the injection process. Clogging of the gate due to being supplied to the product and molding defects due to mixing of the cured product into the product part are prevented. As a result, the frequency of discharging the cured product in the nozzle 2 or cleaning the nozzle 2 can be reduced.

FIG. 3 shows a third embodiment of the nozzle for an injection molding machine according to the present invention together with a part of a mold. The nozzle 2 of this embodiment is different from the first and second embodiments described above in that the end of the sleeve 22 opposite to the mold 1 is screwed into the molding material injection hole 3b of the cylinder 3. There is in point. Other parts are the same as those in the first and second embodiments.

The sleeve main body portion 22a of the sleeve 22 is formed by screwing a male screw portion 22d formed at the end opposite to the mold 1 into a female screw portion 3d formed in the molding material injection hole 3b of the cylinder 3, and then the nozzle. By inserting the female screw hole 21 b of the head 21 into the male screw portion 3 a of the cylinder 3, the head 21 is inserted into the inner peripheral hole 21 a of the nozzle head 21.

The inner peripheral surface of the male screw portion 22d of the sleeve 22 is formed in a tapered shape having a large diameter on the tip side. As a result, an increase in the flow resistance of the liquid rubber is suppressed.

Also in the third embodiment, the metal sleeve 22 forming the liquid rubber supply path on the inner periphery of the nozzle head 21 is formed by the female screw portion 22d and the female of the molding material injection hole 3b of the cylinder 3 cooled. It is in contact (screwing) with the screw portion 3d. The opposite end of the sleeve 22 is not in contact with the nozzle contact surface 1b of the mold 1 and heat transfer from the mold 1 is blocked. As a result, the sleeve 22 is maintained in a moderately low temperature state. Therefore, it is possible to prevent the liquid rubber in the nozzle 2 (sleeve 22) from being cured by heat, so that a cured product of the rubber generated on the nozzle 2 side is contained in the mold 1 together with the liquid rubber in the injection process. Clogging of the gate due to being supplied to the product and molding defects due to mixing of the cured product into the product part are prevented. As a result, the frequency of discharging the cured product in the nozzle 2 or cleaning the nozzle 2 can be reduced.

DESCRIPTION OF SYMBOLS 1 Mold 1a Sprue 1b Nozzle contact surface 2 Nozzle 21 Nozzle head 21a Inner peripheral hole 22 Sleeve 22a Sleeve main body part 22b Outward flange part 22c Press-fit part 22d Male screw part 3 Cylinder 3b Molding material injection hole 31 Cooling jacket

Claims

A nozzle head made of a synthetic resin, which is attached to the tip of a cylinder of an injection molding machine that injects a thermosetting liquid molding material into the mold and is capable of coming into contact with the nozzle contact surface of the mold in which a sprue is opened;
A metal sleeve which is inserted into the inner peripheral hole of the nozzle head and is in contact with the cylinder held at a low temperature, and serves as a flow path for the liquid molding material;
A nozzle for an injection molding machine.
The nozzle for an injection molding machine according to claim 1, wherein the sleeve is not in contact with the nozzle contact surface in a contact state between the nozzle head and the nozzle contact surface of the mold.