JPH0347854Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention relates to a runnerless injection molding device for window frame structures such as TV frames and picture frames.

[Conventional technology]

Generally, a window opening frame structure has an L-shaped bent part formed on the outer periphery, so a structure without a sprue runner cannot be created using a high-precision synthetic resin injection molding machine, so the so-called Currently, it is widely used as a runner injection molding device.

[Problem that the invention attempts to solve]

However, this type of conventional synthetic resin injection molding equipment wastes an extremely large amount of sprue runners compared to the molded product, which is not only uneconomical, but also wastes raw materials, making it unsuitable for so-called resource saving. A serious problem arose.

[Means for solving problems]

This idea was made by focusing on the points mentioned above, and by forming a runner for molten resin in the movable mold, the uninjected molten resin can be kept in the runner in the movable mold even when the mold is released. Solve the above problem by temporarily storing it,
This prevents the sprue runner from deriving.

That is, this invention creates a cavity capable of forming a window frame structure by using a fixed mold having a recess having a substantially U-shaped cross section and a movable mold that engages with this recess and can be moved in and out. The movable mold is passed through the center of the fixed mold, and the movable mold is provided with a runner connected to the injection mechanism and through which the molten resin flows, and two or more runners are provided laterally. The hot runner section is divided to form facing hot runner sections, and a gate provided at the tip of the hot runner section is opened in the side of the cavity.

[Effect]

The molten resin extruded by the injection mechanism in the required amount at a time passes through a runner of a movable mold, passes through a hot runner section divided into two or more parts, and is injected into the cavity from a gate.

The molten resin injected into the cavity with both molds closed is immediately cooled down, and after a certain period of time, the mold is opened in a solidified state.The movable mold moves relative to the fixed mold, and the process The window frame structure molded in the cavity is released from the movable mold and taken out as a product.

Since the raw material resin in the movable mold is kept warm, it is kept in a molten state without being cooled and solidified, and is stored on standby until the next molding operation.

When the mold is in a clamped state again and the injection mechanism operates, the molten resin in the movable mold passes through the runner and the hot runner section to the cavity and continues to repeat the same injection molding operation.

〔Example〕

An embodiment of this invention will be described below with reference to the drawings.

Reference numeral 1 denotes a fixed mold, in which a recess 2 having a substantially U-shaped cross section is formed in the center. Reference numeral 3 designates a movable mold that can fit into the recess 2 and form a window-shaped cavity 4 that can form a window frame structure. 5 is a hole drilled on the central axis of the fixed mold 1, and the movable mold 3
A protruding portion 6 protruding from the center axis of the tube is inserted through the protruding portion 6, and a runner 7 is bored vertically through the protruding portion 6. 8
is a manifold disposed in front of the runner 7, in which branch passages 7a of two or more runners 7 facing the side of the movable mold 3 are provided;
A hot runner portion 9 is formed in front of a, and a gate 10 is opened toward the circumferential surface of the cavity 4. Reference numeral 11 denotes a heating source such as a plurality of cartridge heaters disposed within the movable mold 3, which constantly prevents the molten resin from cooling and solidifying.

Reference numeral 12 designates a nozzle touch portion of the protruding portion 6, which is configured to allow contact with a nozzle portion N of an auxiliary device (not shown) such as an injection mechanism of a conventionally known injection molding apparatus. Reference numeral 13 indicates a movable plate of the movable mold 3, in which a guide rod 14 and a mold release rod 15 provided on both sides protrude toward the fixed mold 1 through an intermediate plate 16, with a base provided on the support rod 16a. Particularly, the mold release rod 15 uses a stopper rod 18 with a built-in spring 17 to automatically extrude the molded product P that attaches to the movable mold 3 and separates from the fixed mold 1 during the mold release operation. It is made so that it can be taken out. 19
is the fixed plate of the fixed mold 1, 20 is the guide rod 1
4 guide hole is shown. 21 is the hot runner part 8
The hot runner chip body is installed vertically inside the hot runner section 9 and has a built-in heater to heat the raw resin in the hot runner section 9 to prevent the resin from cooling and solidifying. Moreover, this hot runner chip body 21 has its tip 21a.
An intermittent heating element capable of performing a heating operation is provided each time an injection molding operation is performed to completely prevent a dripping phenomenon in which molten resin flows out from the gate 10 when taking out a molded product. I can do it.

The action will be explained based on the above structure.

When both molds 1 and 3 are in the clamped state as shown in Fig. 1, when the required amount of molten resin is extruded from the nozzle part N of the injection molding device by the function of the injection mechanism,
The protrusion 6 from the nozzle touch part 12 of the movable mold 3 and the runner 7 and branch flow path 7 provided in the manifold 8
Molten resin is injected into the cavity 4 from the hot runner section 9 through the gate 10 through the hot runner section a.

During this injection operation, the molten resin is forced into the movable mold 3 in advance, so that the runner 7, the branch flow path 7a, and the hot runner section 9 are sealed.
Needless to say, the molten resin is held within the container so that it can be injected.

After a certain period of time has elapsed, that is, after the injected resin in the cavity 4 has been cooled and solidified, the movable mold 3 is moved to perform a mold opening operation, as shown in FIG.

By the way, since the cavity 4 has a window-opening structure, the molded product P is molded as a window-opening frame structure and is attached to the surface of the movable mold 3 and moves as one, and is released from the mold during the movement process. The rod 15 pushes the opening side _P1 of the molded product P outward, and as a result, the part of the molded product P that communicates with the gate 10 is easily folded under the action of shearing force. As shown in the cutaway diagram, the molded product P is released from the movable mold 3 and taken out to the outside.

Even in such a mold open state, the raw material resin in the movable mold 3 is always in a molten state because it is under the heat retaining action of the heat source 11.

Further, the raw resin facing the nozzle touch portion 12 and the gate 10 is in a semi-solidified state, thereby avoiding the inconvenience of inadvertent leakage to the outside.

Next, the movable mold 3 and the fixed mold 1 are placed in the first
When the state returns to the state shown in the figure and the mold is closed, the injection mechanism operates repeatedly, and the same injection operation as described above is performed to inject the molten resin into the cavity 4 and mold the same molded product P. .

In this manner, the same operation can be repeated to perform continuous runnerless injection molding operations.

In the above embodiment, the nozzle part N of the injection mechanism is
The runner 7 of the movable mold 3 and the nozzle touch part 12 allow the movable mold 3 to come into contact with and separate from the nozzle touch part 1.
2 may be omitted, and the nozzle portion N of the injection mechanism may be constructed integrally with the movable mold 3 so that it can reciprocate.

[Effect of idea]

According to this invention, a runner is provided in a movable mold that penetrates inside the fixed mold and connects to the injection mechanism, and a hot runner section that divides into two or more parts forms a gate facing the circumferential surface of the cavity and a window. In order to form an open frame structure, there is a movable mold inside the mold.
Since the raw material resin is constantly kept warm and in a molten state, it is possible to perform so-called runnerless injection molding, and the mold can be sufficiently miniaturized compared to the size of the aperture frame, resulting in highly efficient molding processing. can be made possible.

Therefore, it is extremely effective for molding various window frame structures such as TV frames and picture frames.

[Brief explanation of the drawing]

Fig. 1 is a longitudinal sectional plan view of essential parts showing an embodiment of a runnerless injection molding device for a window frame structure according to this invention, and Fig. 2 is a cross-sectional explanation showing both the mold clamping and mold opening processes of the same. It is a diagram. 1... Fixed mold having recess 2, 3... Movable mold, 4... Cavity, 7... Runway, 9... Hot runner section, 10... Gate, P... Molded product (window opening) frame structure).

Claims (1)

[Scope of utility model registration request] For fixed molds that have a recess with a roughly U-shaped cross section,
A movable mold that engages with the recess and can be freely moved in and out is provided through the movable mold, and a runner is bored on the central axis of the movable mold to connect with the injection mechanism and flow the molten resin, and a runner is provided laterally. A runnerless injection molding apparatus for a window-opening frame structure, which is divided into the above parts to form a hot runner part, and a gate formed at the tip of the hot runner part faces the side of a cavity of the window-opening structure.