JPH06293048A - Injection molding method - Google Patents

Abstract

PURPOSE:To prevent a problem such as core dragging in an injection molding method using a slide core by an injection method performing injection molding so as to integrate a separate injection-molded part with an injection-molded main body. CONSTITUTION:An injection molding machine consists of the pressure piston 2 moving in a mold clamping cylinder 1, a movable platen 4 to which the pressing force of the pressure piston 2 is applied through a rod 10, a movable mold 5 receiving clamping force by the movable platen 4, a fixed mold 6 constituting a pair of molds along with the movable mold 5, the fixed platen 7 holding the fixed mold 6 and the first direction control valve 11, second direction control valve 12 and relief valve 13 provided to the oil passages between the mold clamping cylinder 1, an oil pressure source 9 and a tank. At a time of the movement of a slide core, mold clamping force is lowered by the first and second direction control valves 11, 12 and the relief valve 13.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an injection method for integrally injection-molding another injection-molded portion on an injection-molded body, and more particularly to an injection molding method using a slide core.

[0002]

2. Description of the Related Art As a recent plastic molding technique, it is often practiced to integrally mold another portion into a main body portion. In the old days, a technique has been proposed in which a part molded by one mold is placed on the other mold and then injection molding is performed to integrate the two. This technique has been infrequently used in recent years in that it requires complicated molding equipment including a mold and requires many procedures. After that, a method has been proposed in which the main body portion and another portion are separately molded, and then a heat source is again applied to the main body portion to fuse them, but this has poor dimensional accuracy and appearance. Further, there is a problem in that it takes man hours.

As a recent proposal, JP-A-59-48135
There is a technique disclosed in the publication. Figure 2
A description will be given based on (a) and (b). First, the hydraulic cylinder is operated to close the fixed mold 25 and the movable mold 26, and the hydraulic piston 22 is operated to project the tip of the slide core 28 into the cavity 27 formed by the fixed mold 25 and the movable mold 26. To mold the cavity 27 of the main body. In this state, the nozzle of the injection cylinder 23 is pressed against the spool push 21 having the main body resin passage 31 to inject the main body resin to mold the main body. Subsequently, the operation of the hydraulic piston 22 is stopped, the slide core 28 is retracted to a predetermined position by the elastic force of the return spring 29, and the resin for another part is injected from the injection cylinder 24 into the space formed by this. And mold another part. After the molding, the hydraulic cylinder is operated to push out the product which is in close contact with the movable mold 26 side and is pushed down by the rod 30 to complete the product.

[0004]

However, even in the proposal disclosed in Japanese Patent Laid-Open No. 59-48135, the slide core is moved while the mold clamping force is applied to the mold. , There was a problem such as core scraping. For this reason, in the conventional injection molding of this kind, in order to prevent core scuffing, it has been dealt with by increasing the clearance of the mold parts, etc. However, with this method, the accuracy of the molded product is lowered and the desired molded product is obtained. There are problems such as difficulty in manufacturing molds to obtain precision

On the other hand, recent molding dies, especially dies having a slide core, are automated, and therefore, it is necessary to satisfy the following conditions. (1) Equipped with a safety device for each part of the mold, and reliably prevent damage to the mold in relation to the operation of the molding machine. (2) The molded product must be released completely and reliably. (3) The mold must have a wide range of molding conditions. (4) Mold temperature is automatically controlled. Among these, the above condition (1) is particularly important. In the mold with the slide core 28, it is the slide core 2
This is because it is necessary to prevent galling between the mold 8 and the mold.
As described above, in consideration of the molding method proposed in Japanese Patent Application Laid-Open No. 59-48135, the above-mentioned conditions for automation, and the like, various improvements must be made.

In order to solve the above-mentioned problems, the present invention alleviates the strain generated in the mold by the mold clamping force, and the movement (rotation, slide, etc.) of the movable parts of the mold components, and the condition width (operating force). ,
It is an object of the present invention to provide an injection molding method using a slide core 28 that can widen the clearance with the other party, the life of parts, etc.).

[0007]

In an injection molding machine of a direct pressure type mold clamping mechanism equipped with a mold containing a slide core, a mold clamping side hydraulic chamber in a mold clamping cylinder is hydraulically operated via a second directional control valve. A circuit for connecting the mold opening-side hydraulic chamber to a conduit for communicating with the tank and a circuit for connecting the mold opening-side hydraulic chamber to the conduit for communicating with the tank, and connecting the mold-closing hydraulic chamber with the mold-opening hydraulic chamber in the second direction. A first directional control valve having three circuits, that is, a circuit connected to a pipeline communicating with a hydraulic pressure source via a control valve and a circuit connecting both the mold clamping side and the mold opening side hydraulic chambers to a tank is provided. , A circuit that connects the mold clamping side hydraulic chamber or the mold opening side hydraulic chamber to the hydraulic pressure source, and two circuits that connect the mold clamping side hydraulic chamber or the mold opening side hydraulic chamber to the relief valve in the mold clamping cylinder A second directional control valve having a The mold opening side hydraulic chamber forms a circuit that connects to the tank and clamps the mold, and when the slide core moves, the mold clamping side hydraulic chamber is connected to the relief valve for a set time according to the moving time, and the mold opening side hydraulic pressure is Form a circuit to connect the chamber to the tank, and to form a circuit to connect the mold clamping side hydraulic chamber to the hydraulic source and the mold opening side hydraulic chamber to the tank again when injecting after moving the slide core. Is characterized by.

[0008]

[Operation] According to the present invention, the first directional control valve 11, the second
The directional control valve 12 supplies high-pressure oil from the hydraulic source 9 to the mold clamping cylinder 1, and the clamping force is directly applied to the movable mold 5 and the fixed mold 6 via the pressure piston 2 and the rod 10. In this state, the main body is injection-molded. Next, switching to the first directional control valve 11 and the second directional control valve 12 resulted in a low value,
The mold clamping force of the mold is maintained so that the slide core 28 and the mold do not cause galling. In this state, the slide core 28 is moved by a predetermined distance, and the cavity 27 for another part other than the main body is
To form. Next, the high-pressure oil from the hydraulic pressure source 9 is switched by the first directional control valve 11 and the second directional control valve 12 to be supplied to the mold clamping cylinder 1 to the movable mold 5, the fixed mold 6, and the pressurizing piston. 2. A mold clamping force is directly applied via the rod 10. In this state, another part is integrally molded with the main body.

[0009]

Embodiments of the present invention will now be described in detail with reference to the drawings. 1A and 1B are configuration diagrams of a direct pressure mold clamping device according to an embodiment of the present invention. FIG. 1A shows a mold clamping state, and FIG. 1B shows a mold clamping force relaxing state.

The direct pressure type mold clamping device includes a mold clamping cylinder 1, a pressure piston 2 moving in the mold clamping cylinder 1, a movable platen 4 to which a pressure force of the pressure piston 2 is applied via a rod 10, and a movable platen 4. A movable mold 5 to which a clamping force is applied by the platen 4, a fixed mold 6 that forms a pair of molds with the movable mold 5, a fixed platen 7 that holds the fixed mold 6, a mold clamping cylinder 1 and hydraulic pressure. It comprises a first directional control valve 11, a second directional control valve 12, and a relief valve 13 provided in an oil passage between the source 9 and the tank.

Next, this operation will be described. First, pressure oil from the high-pressure hydraulic power source 9 is added to the oil passage c side of the mold clamping cylinder 1 so that the clamping force acts on the pressure piston 2. The hydraulic circuit at this time is as shown in FIG. At this time, the movable mold 5 and the fixed mold 6 are clamped at a predetermined high pressure. In the movable mold 5 and the fixed mold 6, a resin corresponding to the main body is used as a cavity 27 for resin injection molding.

Next, in order to integrally injection-mold another part to the main body part, as shown in FIGS. 2A and 2B, a slide core is formed so as to form a cavity 27 corresponding to the other part. To move. Prior to the movement of the slide core, as shown in FIG. 1B, the second directional control valve 12
Is switched to the pressure set in the relief valve 13. That is, it is dropped into the tank via the second directional control valve 12 and the relief valve 13 in the mold clamping cylinder 1. As a result, the tightening force of the movable mold 5 and the fixed mold 6 is reduced. The slide core 28 is moved while the tightening force is decreasing. After that, when the movement of the slide core 28 is completed, as shown in FIG. 1A, the second directional control valve 12 is switched to apply a tightening force to the movable mold 5 and the fixed mold 6. Then, the resin is injection-molded into the cavity 27 of the moved portion of the slide core 28.

[0013]

[Effect] As described above in detail, according to the present invention, in the injection molding method, the mold clamping force of the mold which is subjected to the predetermined mold clamping force is incorporated into the mold in accordance with the injection order. When the slide core 28 is moved, a step of relaxing the movement of the slide core 28 to such an extent that it moves smoothly and a step of returning the mold clamping force to a predetermined value after moving the slide core 28 to a predetermined position are performed. Therefore, (1) it is possible to prevent galling and deformation between the slide core 28 and the mold. (2) Since the die and the slide core 28 are not damaged, the accuracy of the product can be improved. (3) The life of the mold parts can be extended. (4) The trial and error for determining the clearance is reduced, and the mold production is easy. (5) The molded product can be completely and surely released from the mold. (6) Since mold replacement can be done in a long cycle, maintenance,
It is easy to assemble a line and make a production plan. (7) The injection molding method of the present invention can be easily changed to the conventional injection molding method by simply adding a valve opening / closing control step. (8) Since the slide core 28 is moved after the tightening force is relaxed, the slide core 28 can be moved with a small force.

[0014]

[Brief description of drawings]

FIG. 1 is a configuration diagram of a direct pressure type mold clamping device according to a first embodiment of the present invention.

FIG. 2 is an operation explanatory view of an injection molding machine using a conventional slide core.

[Explanation of symbols]

 1 Clamping Cylinder 2 Pressurizing Piston 4 Movable Platen 5 Movable Die 6 Fixed Die 7 Fixed Platen 9 Hydraulic Source 10 Rod 11 1st Directional Control Valve 12 2nd Directional Control Valve 13 Relief Valve 21 Spool Bush 22 Hydraulic Piston 23 Injection Cylinder 24 Injection cylinder 25 Fixed mold 26 Movable mold 27 Cavity 28 Slide core 29 Return spring 30 Extrusion rod 31 Passage 41 Mold clamping side oil chamber 42 Mold opening side oil chamber

Claims (1)

[Claims] 1. In an injection molding machine having a direct pressure type mold clamping mechanism equipped with a mold having a slide core, a pipe for communicating a mold clamping side hydraulic chamber in a mold clamping cylinder to a hydraulic pressure source via a second directional control valve. Circuit for connecting the mold opening side hydraulic chamber to the pipeline that connects to the tank, and connecting the mold clamping side hydraulic chamber to the pipeline that connects to the tank and connecting the mold opening side hydraulic chamber to the second directional control valve. A directional control valve having three circuits, a circuit connected to a pipeline communicating with a hydraulic pressure source and a circuit connecting both the mold clamping side and mold opening side hydraulic chambers to the tank, and a mold clamping cylinder. A second circuit having a circuit for connecting the mold clamping side hydraulic chamber or the mold opening side hydraulic chamber to a hydraulic pressure source and two circuits for connecting the mold clamping side hydraulic chamber or the mold opening side hydraulic chamber in the mold clamping cylinder to a relief valve. A directional control valve is installed, and the mold clamping side hydraulic chamber serves as the hydraulic source during injection, and also the mold opening side hydraulic pressure. The chamber forms a circuit that connects to the tank and clamps the mold.When the slide core moves, the mold clamping side hydraulic chamber is connected to the relief valve for the set time corresponding to the moving time, and the mold opening side hydraulic chamber is connected to the tank. When the injection after moving the slide core, the mold clamping side hydraulic chamber again forms a circuit connecting to the hydraulic pressure source and the mold opening side hydraulic chamber forms a circuit to connect to the tank. Injection molding method.