JPH0644656Y2 - Injection molding nozzle device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to a nozzle device used for injecting a molten synthetic resin and a pressurized fluid into a mold to injection-mold a hollow mold of the synthetic resin or the like. Regarding

(Prior Art) Conventionally, as a nozzle device used to inject a molten synthetic resin and a pressurized fluid into a mold and injection-mold a hollow molded product of the synthetic resin, for example, a nozzle hole is provided at the tip. It is known that a fluid injection nozzle tube is inserted into the molten resin passage of the nozzle cylinder. In such a nozzle device, a fluid injection nozzle pipe is connected to a pressurized fluid source via a pipe, a jet port of the nozzle pipe is directed to a nozzle hole of a nozzle cylinder, and the nozzle is attached to a tip discharge port of an injection cylinder. Used.

(Problems to be Solved by the Invention) However, in the injection molding nozzle device as in the above-mentioned conventional technique, when a fluid such as a gas close to room temperature is injected, the fluid injection nozzle tube is cooled by the fluid and is injected. The molten resin around the nozzle solidifies by cooling and the molten resin passage in front of the tip of the nozzle tube is blocked. Even if the molten resin discharge pressure is increased, it does not flow and the nozzle device is damaged by the internal pressure. I was afraid to do it.

The present invention has been made to solve the above problems, and an object of the present invention is to provide an injection molding nozzle device capable of gas injection molding without resin solidification and clogging in front of the tip of a nozzle tube. To provide.

(Means for Solving the Problem) The injection molding nozzle device of the present invention is an injection molding nozzle device in which a fluid injection nozzle pipe is inserted into a molten resin passage of a nozzle cylinder. The inner surface and / or the outer surface of is covered with a heat insulating material layer.

The synthetic resin used in the present invention is a thermoplastic resin used in general injection molding or extrusion molding, but a thermosetting resin can also be used if necessary.

Further, as the fluid used in the present invention, for example, those which can become a gaseous substance at room temperature such as nitrogen gas, carbon dioxide gas, and air are preferably used, but a liquid foaming agent or the like may be used.

The heat insulating material layer in the present invention is preferably a material having excellent heat resistance, for example, a material coated with a heat resistant resin such as polytetrafluoroethylene or polyimide having a melting temperature higher than that of the resin used for molding, or alumina. It may also be formed by coating ceramic powder such as zirconia or magnesia by thermal spraying.

(Operation) With the above-described structure of the injection molding nozzle device of the present invention, even if a fluid such as a gas near room temperature is ejected from the fluid injection nozzle pipe, the surface of the fluid injection nozzle pipe that contacts the molten resin is cooled by the heat insulating material layer. Therefore, the molten resin around the fluid injection nozzle tube in the molten resin passage, and in particular, the front portion of the front end of the nozzle tube is not cooled and solidified.

(Embodiment) An embodiment of the injection molding nozzle device of the present invention will be described with reference to the drawings.

In FIG. 1, reference numeral 1 denotes a nozzle cylinder, a molten resin passage 2 is provided therein, a nozzle ring 11 having a nozzle hole 3 at a tip thereof, a cylinder body 12, and a mounting base portion 13.
The mounting base 13 is inserted into the discharge port of an injection cylinder (not shown).

Reference numeral 4 denotes a fluid injection nozzle tube in which a fluid passage 5 is provided. The fluid injection nozzle tube 4 is composed of a nozzle tube 6 having an ejection port 8 at its tip and a bridge-shaped support portion 7. It is attached by fixing the support portion 7 to the cylinder main body 12 toward 3. A pipe 9 connected to a pressurized fluid source (not shown) is attached to the support portion 7, and the fluid passage 5 of the support portion 7 and the hole of the pipe 9 communicate with each other. As shown in FIG. 2, the fluid injection nozzle pipe 4 is provided with a heat insulating material layer 41 on the inner surface which becomes the fluid passage 5, and also on the outer surface on the molten resin passage 2 side, a heat insulating material layer 42 is provided. Has been.

Reference numeral 10 is a needle valve for opening and closing the reduced diameter portion 21 in the middle of the molten resin passage 2, and is provided in the mounting base 13.

The operation of the injection molding nozzle device in the above embodiment will be described with reference to the drawings.

In advance, the molten resin is plasticized and stored in an injection cylinder (not shown). Next, in order to inject the resin into the mold, when a predetermined injection pressure is applied to the molten and plasticized resin in the injection cylinder, the needle valve 10 opens and the molten resin is reduced in diameter.
It flows out from 21 through the molten resin passage 2 to the nozzle hole 3, and is injected into the mold cavity.

Next, when a predetermined amount of resin is injected into the mold, the resin pressure in the injection cylinder is released and the needle valve 10 is closed. In this open / closed state, when nitrogen gas at normal temperature is supplied from the pressurized fluid source, it is ejected from the ejection port 8 of the fluid injection nozzle pipe 4 toward the nozzle hole 3. The jetted fluid is injected into the resin of the cavity of the die through the nozzle hole 3 to form a hollow die.

In the above embodiment, the nozzle cylinder 1 comprises a nozzle ring 11 having a nozzle hole 3, a cylinder body 12 for mounting and holding a fluid injection nozzle tube 4, and a mounting base 13 having a needle valve 10. It consisted of things,
The present invention is not limited to this, and for example, the fluid injection nozzle pipe 4 can be moved forward and backward by utilizing an elastic body such as a compression spring mounted in the cylinder body 12 and injection pressure to open and close the nozzle hole 3. The attachment base portion 13 and the needle valve 10 may be omitted as long as they function as a valve body that operates.

Although the heat insulating material layer is provided on the inner and outer surfaces of the fluid injection nozzle tube 4 in the above embodiment, it may be provided on only one of the inner surface and the outer surface.

(Effect of the Invention) The injection molding nozzle device of the present invention is an injection molding nozzle device in which a fluid injection nozzle tube is inserted into a molten resin passage of a nozzle cylinder, and the inner surface of the fluid injection nozzle tube or And since the outer surface is covered with the heat insulating material layer, even if the fluid at room temperature is ejected from the fluid injection nozzle pipe,
The molten resin around the fluid injection nozzle tube is not cooled and solidified, and the molten resin passage is not clogged with the solidified resin and blocked. Therefore, it is possible to continue the molding production in a good flow state without increasing the discharge pressure of the molten resin from the injection cylinder, and there is no fear that the nozzle device will be damaged.

[Brief description of drawings]

FIG. 1 is a longitudinal sectional view showing an embodiment of the injection molding nozzle device of the present invention, and FIG. 2 is a sectional view of a fluid injection nozzle tube used in the injection molding nozzle device of the present invention. Explanation of symbols 1 ... Nozzle cylinder, 2 ... Molten resin passage, 3 ...
Nozzle hole, 4 ... Fluid injection nozzle pipe, 41, 42 ... Insulation material layer, 5 ... Fluid passage, 8 ... Jet port.

Claims (1)

[Scope of utility model registration request] 1. A nozzle device for injection molding, comprising a fluid injection nozzle tube inserted into a molten resin passage of a nozzle cylinder, wherein an inner surface and / or an outer surface of the fluid injection nozzle tube is covered with a heat insulating material layer. An injection molding nozzle device.