JPH0327783Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention relates to an improvement of a valve nozzle for an injection mold.

[Prior art]

Examples of conventional valve nozzles for injection molding molds include those shown in FIGS. 5 to 8. Fifth,
FIG. 6 schematically shows a cross-section of a so-called valve gate mold attached to an injection molding machine, and FIGS. 7 and 8 are partial cross-sectional views of the main parts thereof viewed from another direction. The mechanism is explained below.
First, the movable mold 2 of the mold 1 is attached to a movable platen 4 driven by a mold clamping ram 3, and the fixed mold 5 is
It is attached to a fixed platen 6. A runner 8 introduces the molten resin into the heating cylinder 7 of the injection molding machine.
A valve nozzle 10 is provided at the tip end of the mold, which communicates via a gate G with a cavity 9 formed when the mold is closed (FIG. 6). This valve nozzle 10
consists of a nozzle 11 and a movable valve pin 12 inserted through its shaft, and this valve pin 12 is operated as shown by the arrow A by a driving means such as a hydraulic or pneumatic cylinder 13 or an electric motor. The gate G connecting the runner 8 and the cavity 9 is opened during injection (FIG. 8) and closed when injection is completed (FIG. 7). In the figure, 14 is a piston connected to the valve pin 12, 15 is a lever that moves the piston 14 up and down, and 16 is a pivot pin as a pivot axis of this lever 15. According to this valve nozzle,
Since the gate G is closed by the valve pin 12, the molten resin in the runner 8 can be pressurized and compressed in advance. Therefore, high-speed injection of molten resin is possible when the valve is opened, and the shot cycle can be shortened. In addition, there are various advantages such as the resin can be cut easily at the gate G and the nose sag can be prevented when the mold is opened.

[Problem that the invention attempts to solve]

However, in such a conventional injection molded valve nozzle, when the valve pin 12 operates, it slides on the gate G portion of the nozzle 11 and the bearing portion 18 of the manifold 17. The sliding part with an extremely small clearance may become clogged with minute foreign matter mixed into the molten resin passing through the nozzle 11, or the valve pin may become clogged due to the difference in thermal expansion between the nozzle 11 and the valve pin 12 or the thermal expansion of the manifold 17. There was a problem in that the nozzle 12 could get stuck at the nozzle 11 and become inoperable.

This invention was made by focusing on such conventional problems, and aims to solve the above problems by providing an injection molded valve nozzle that can open and close the gate without sliding. It is an object.

[Means for solving problems]

This invention to achieve the above object is a valve nozzle structure for an injection molding mold equipped with a valve that opens and closes a gate leading to a cavity in response to opening and closing of the mold, the valve having a valve body that self-seals the gate with internal pressure of the nozzle; This is an injection molded valve nozzle structure comprising a movable mold that performs a closing operation and a thrust drive pin that moves the valve body from the gate closed position to the open position.

〔Example〕

This invention will be explained below based on the drawings.

1 and 2 are diagrams showing an embodiment of this invention. Note that the same reference numerals are given to parts that are the same as or corresponding to the conventional ones.

First, the configuration will be described. Reference numeral 20 is a spherical ball valve valve body inserted into the runner 8 of the nozzle 11, and is adapted to cover the inlet of the gate G.
21 is a push-up pin for pushing up this ball valve valve body 20 when the mold is closed to open the gate G. Although it is considerably thinner than the diameter of the gate G, the ball valve body 2
It is thick enough to push up the movable type 2.
It is planted at a position opposite to gate G in .

Next, the action will be explained.

When the movable mold 2 approaches the fixed mold 5 when the mold is closed, the push-up pin 21 fixed to the movable mold 2 pushes up the ball valve body 20 in the nozzle 11, so the gate G of the nozzle 11 opens and injection is possible. .

When the mold is opened after completing a series of steps consisting of injection, pressure holding, and cooling, the movable mold 2 separates from the fixed mold 5, and the push-up pins 21 also come out of the gate G and return. Since there is residual pressure of the molten resin in the nozzle 11, the ball valve valve body 20 is moved toward the gate inlet by the residual pressure and closes the gate G.

Self-sealing due to residual pressure inside the nozzle ensures safe and reliable operation. According to this embodiment, it is possible to attach and detach the push-up pin 21 while the movable mold 2 is attached to the movable platen 4 of the molding machine, and it is possible to quickly respond to breakage of the pin.

FIG. 4 shows another embodiment.

In this embodiment, the push-up pin 31 is not fixed to the movable mold 2, and the ball valve body 30 has a true spherical shape.
It is integrally fixed to. When opening the mold, the third
As shown in the figure, the valve body 30 is seated at the inlet of the gate G and is self-sealed by the internal pressure of the runner 8. The push-up pin 31 projects outward from the gate G. When the mold is closed, the movable mold 2 pushes the valve body 30 through the push-up pin 31.
is pushed up, the nozzle gate G opens, and the molten resin is injected into the cavity 9. When the injection is completed and the mold is opened, the movable mold 2 is separated from the nozzle 11 and the runner 8
The valve body 30 closes the gate G due to the residual pressure inside.

According to this embodiment, the push-up pin 3 is attached to the movable mold 2.
Since no special processing is required to attach 1, conventional molds can be used as is.

In each of the above embodiments, the valve body may be inserted into the nozzle 11 at the time of assembling the manifold 17 (which serves as a hot runner).

[Effect of idea]

As explained above, according to this idea,
A valve that self-seals the gate using molten resin pressure is installed inside the nozzle, and the valve body is operated with a movable closing action to open the gate.Therefore, there is no sliding part when opening and closing the valve, resulting in malfunction of the valve. This provides the advantage of being able to provide a valve nozzle that does not generate.

[Brief explanation of the drawing]

Figures 1 and 2 are sectional views of essential parts of one embodiment of this invention, with Figure 1 in the mold open state, Figure 2 in the mold closed state, and Figures 3 and 4 in other embodiments. 3 is a sectional view of the main parts, FIG. 3 is a mold open state, FIG. 4 is a mold closed state, and FIG. 5 is a cross-sectional schematic diagram of a conventional valve gate mold attached to an injection molding machine, showing the mold open state. FIG. 6 similarly shows the mold closed state. Figures 7 and 8 are partial sectional views showing the main parts enlarged. Figure 7 is the gate closed,
The figure shows a state in which the gate is open. 1... Mold, 2... Movable mold, 9... Cavity,
G...Gate, 11...Nozzle, {20,30}
... Valve body, {21, 31} ... Push-up pin.

Claims (1)

[Scope of utility model registration request] In a valve nozzle structure for an injection molding mold that is equipped with a valve that opens and closes a gate leading to a cavity in response to opening and closing of the mold, the valve is located at the gate inlet and includes a true spherical ball valve valve body that self-seals the gate using internal pressure of the nozzle. , so that the closing operation of the movable type moves the valve body from the gate closed position to the open position, so that the valve body is smaller than the diameter of the gate but thick enough to push up the valve body, and is located opposite to the movable gate. An injection molded valve nozzle structure characterized by a push-up pin fixed to the.