JPH04123858A - Method and device for degassing injection molding machine - Google Patents

Abstract

PURPOSE:To prevent the misrun or the air involution and to prevent the generation of fault of appearance or cast cavity by releasing the degassing path to the atomosphere before the start of evacuation with the evacuating device on degassing for the injection molding machine. CONSTITUTION:Because the degassing path 29 is released to the atomosphere before starting evacuation with a evacuating device 33, so the tightly sealed state is not generated, the increase in pressure is prevented, the fluid resistance for the injection molten substance is reduced and an intrusion of air into the injection molten substance is eliminated. On this device for degassing, a change- over means 103 is set on the 2nd side of the degassing path 29, the degassing path 29 is released to the atomosphere by shutting off between the degassing path 29 and the evacuating device 33 before starting evacuation with the evacuating device 33, at a same time of starting evacuation, the degassing path 29 and the evacuating device 33 are communicated, and the release of the degassing path 29 to the atomosphere is sopped.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to a degassing method and a degassing device for an injection molding machine such as a die casting machine, and in particular, the present invention relates to a degassing method and a degassing device for an injection molding machine such as a die casting machine. The present invention relates to a device that eliminates a sealed state until evacuation is started, thereby preventing a pressure increase and, therefore, air being drawn into the molten material to be injected.

(Prior art) As an injection molding machine, for example, JP-A-63-313F
There is one as shown in Publication No. 34.5. This will be explained with reference to FIG.

Figure 4 is a cross-sectional view, not showing the structure of the injection molding machine.
A fixed mold 1 and a movable mold 3 are arranged.

A runner 5 is formed between the fixed mold 1 and the movable mold 3, and above the runner 5 in the figure,
A cavity 9 is formed through the gate 7.

A casting sleeve 11 is inserted into the lower part of the fixed mold 1 in the figure and communicates with the runner 5.

A pouring port 13 is formed on the side surface of the right end of the casting sleeve 11 in the figure, and the molten material to be injected is poured through the pouring port 13.

A plunger 15 is housed within the casting sleeve 11 so as to be slidable in the left and right directions in the figure.

This plunger 15 is connected to an injection cylinder 19 via a plunger rod 17.
By appropriately driving 9, it slides within the casting sleeve 11.

A striker 21 is attached to the end of the injection cylinder 19 on the plunger 15 side, and a vacuum start limit switch 23 and a high speed limit switch 25 are arranged at predetermined positions along the path of movement of the striker 21. There is.

The upper end of the cavity 9 in the drawing is a dividing surface portion 27, and a gas vent passage 29 is formed above the dividing surface portion 27 in the drawing. A vacuum suction device 33 is connected to the gas vent passage 29 via a pipe 31. This vacuum suction device 33 includes an electromagnetic switching valve 35, a tank 37, a vacuum pump 39, and a drive motor 41.

The electromagnetic switching valve 35 has switching positions 35a and 35b, and when switched to the switching position 35a, the gas vent passage 29 and the vacuum suction device 33 are communicated with each other.

An on-off valve 43 is inserted into the gas vent passage 29 . This on-off valve 43 is opened and closed by a valve drive mechanism 45. That is, the on-off valve 43
7 and a shaft 49, and the shaft 49 is connected to a piston 53 that is slidably housed in a cylinder 51.

On the other hand, a compressor 55 is installed, and the compressed air from this compressor 55 is transferred to an electromagnetic switching valve 57, a pipe 5
9.61 into the front chamber 63 or rear chamber 65 of the cylinder 51, respectively. Thereby, the piston 53 is slid to either the left or right in the drawing, and the valve body 47 is moved toward and away from the seat portion 67, thereby opening and closing the valve. The electromagnetic switching valve 57 has switching positions 57a and 57b, and compressed air is supplied to the front chamber 63 or the rear chamber 65 by switching to either position.

Further, a detection rod 69 is installed in the gas vent passage 29.

The detection rod 69 detects the molten material to be injected pushed up, and controls the on/off of the electromagnetic switching valve and the opening/closing of the on-off valve 43 via an electric circuit (not shown).

The operation will be explained based on the above configuration.

First, with the on-off valve 43 open, the molten material to be injected is poured from the pouring port 13. At the same time, the injection cylinder 19 is driven to slide the plunger 15 to the left in the figure.

The sliding of the plunger 15 closes the pouring port 13, and the striker 21 operates the vacuum start limit switch 23. In response to the operation of the start limit switch 23, the electromagnetic switching valve 35 is switched to the switching position 35a via an electric circuit (not shown). By the operation of the electromagnetic switching valve 35, the gas vent passage 29 and the vacuum suction device 33 are communicated, and the gas in the casting sleeve 11, the runner 5, and the cavity 9 is transferred to the gas vent passage 29 and the piping 3.
It is sucked in and discharged through 1.

When the plunger 15 further slides to the left in the figure, the cavity 9 is filled with the molten material to be injected, and the gas vent passage 2
The molten material to be injected comes into contact with the detection rod 69 . In response to the detection signal from the detection rod 69, the electromagnetic switching valve 57 is switched to the switching position 57a via an electric circuit (not shown).

By the operation of the electromagnetic switching valve 57, the compressor 55
Compressed air is supplied into the front chamber 63 of the cylinder 51, and the piston 53 retreats to the right in the figure. piston 5
When the valve body 47 is retracted to the third predetermined position, the valve body 47 is moved back to the seat part 67.
When the valve is seated, the valve becomes closed. By closing the on-off valve 43, the gas vent path 29 is shut off, and the evacuation by the vacuum suction device 33 is stopped.

(Problem to be solved by the invention) The conventional configuration described above has the following problems.

That is, there is some time after the plunger 15 moves forward and closes the pouring port 13 until the striker 21 activates the vacuum start limit switch 23 and the vacuum suction device 33 starts evacuation. During this period, the insides of the casting sleeve 11, runner 5, cavity 9, and gas vent passage 29 are completely sealed.

Therefore, the air within the casting sleeve 11, runner 5, and cavity θ is compressed, and the air pressure increases. The situation is shown in FIG. FIG. 5 is a characteristic diagram showing the change in air pressure within the pipe 31 over time. As shown in the figure, pouring port 13
The pressure begins to rise after the is closed, and the rising trend is maintained until vacuuming begins.

When air pressure increases in this way, air becomes more likely to get caught up in the molten material to be injected, causing internal defects such as cavities after molding, and resulting in lower product quality. be.

The present invention has been made based on the above points, and its purpose is to suppress the pressure increase from the time when the pouring port is closed until the start of evacuation, thereby preventing the formation of cavities, etc. It is an object of the present invention to provide a degassing method and a degassing device for an injection molding machine, which can prevent internal defects from occurring and improve product quality.

(Means for Solving the Problems) In order to achieve the above object, in the present invention, the molten material to be injected into the cavity through the pouring spout while the on-off valve inserted in the gas vent path is opened. At the same time, the molten material to be injected is extruded by a plunger driven by an injection cylinder, and after a predetermined time the pouring port is closed by the plunger, it is evacuated through a gas vent passage by a vacuum suction device, and then opened and closed. In a degassing method for an injection molding machine in which evacuation is stopped by closing a valve, the degassing path is kept open to the atmosphere until evacuation by a vacuum suction device is started. Provides a method for degassing a molding machine.

Furthermore, with the on-off valve inserted in the gas vent passage open, the molten material to be injected is injected into the cavity through the pouring port, and the molten material to be injected is injected into the cavity by the plunger driven by the injection cylinder. An injection molding machine that extrudes, and after a predetermined period of time after the pouring port is closed by a plunger, a vacuum is drawn through a gas vent passage by a vacuum suction device, and then the vacuum is stopped by closing an on-off valve. In the gas venting device, a switching means is provided on the secondary side of the gas venting path, and the gas venting path and the vacuum suction device are shut off until the vacuum suction device starts to draw a vacuum. Provided is a degassing device for an injection molding machine, in which the degassing path is opened to the atmosphere, and the degassing path and the vacuum suction device are communicated with each other at the same time as the vacuum suction device starts evacuation, thereby stopping the degassing path from being opened to the atmosphere. do.

(Function) The method for degassing an injection molding machine according to the present invention is such that the degassing path is opened to the atmosphere until the vacuum suction device starts evacuation.

That is, conventionally, after the pouring port is closed by the plunger until the evacuation is started by the vacuum suction device, the mold is in a sealed state, which poses a problem of pressure increase due to compression.

Therefore, until the vacuum suction device starts evacuation, the gas vent path is opened to the atmosphere to eliminate the occurrence of the above-mentioned sealed state, prevent pressure rise, and prevent air from flowing into the molten material to be injected. This is to prevent the intrusion of foreigners.

The degassing device for an injection molding machine according to the present invention is intended to carry out the degassing method for the injection molding machine described above, and is provided with a switching means on the secondary side of the degassing passage, and by this switching means, the vacuum suction device The degassing path and the vacuum suction device are shut off and the degassing path is left open to the atmosphere until the evacuation by the vacuum suction device starts. This is to stop the gas vent passage from being opened to the atmosphere.

(Example) Hereinafter, a first example of the present invention will be described with reference to FIGS. 1 and 2.

Incidentally, the same parts as in the prior art are denoted by the same reference numerals, and the explanation thereof will be omitted.

As shown in FIG. 1, another pipe 101 is branched and connected to the pipe 31, and an electromagnetic switching valve 103 as a switching means is connected to this pipe 101. This electromagnetic switching valve 103 includes switching positions 103a and 103b,
By switching to the switching position 103a, the piping 101 is opened to the atmosphere, and by switching to the switching position 103b,
This is to close the pipe 101.

Further, the electromagnetic switching valve 103 is normally switched to a switching position 103b by a compression coil spring 105. On the other hand, when the solenoid 109 is excited by the electric circuit 107, it is switched to the switching position 103a.

The operation will be explained based on the above configuration.

First, with the on-off valve 43 open, the molten material to be injected is poured from the pouring port 13. At the same time, the injection cylinder 19 is driven to slide the plunger 15 to the left in the figure.

When the injection cylinder 19 is driven, the solenoid 109 of the electromagnetic switching valve 103 is
is excited. By energizing the solenoid 09, the electromagnetic switching valve 103 is switched to the switching position 103a. In other words, the pipe 101 and, in turn, the gas vent passage 29 are opened to the atmosphere.

The sliding of the plunger 15 closes the pouring port 13, and the striker 21 operates the vacuum start limit switch 23. In the conventional case, the state was completely sealed from the time when the pouring port 13 was closed until the start of evacuation, but in the case of this embodiment, as mentioned above, the The casting sleeve 11, runner 5, and cavity 9 are exposed to the atmosphere.
, the air in the gas vent passage 29 is not compressed.

Then, due to the operation of the vacuum start limit switch 23, the electromagnetic switching valve 35 is switched to the switching position 35a via the electric circuit 107, and the solenoid 109 of the electromagnetic switching valve 103 becomes de-energized. By the operation of the electromagnetic switching valve 35, the gas vent passage 29 and the vacuum suction device 3 are connected to each other.
3 are in communication with each other, and the gas in the casting sleeve 11, the runner 5, and the cavity θ is sucked and discharged through the gas vent passage 29 and the piping 31. Further, the electromagnetic switching valve 103 is switched to the switching position 103b, and the pipe 10] is closed.

The subsequent operations are the same as before. That is, when the plunger 15 further slides to the left in the figure, the cavity 9 is filled with the molten material to be injected, and the melt is further pushed out into the gas vent passage 29. Thereby, the molten material to be injected comes into contact with the detection rod 69. Thereby, the electromagnetic switching valve 57 is switched to the switching position 57a via an electric circuit (not shown).

By the operation of the electromagnetic switching valve 57, the compressor 55
Compressed air is supplied into the front chamber 63 of the cylinder 51, and the piston 53 retreats to the right in the figure. Thereby, the valve body 47 is seated on the seat portion 67, and the valve is in the closed state. By closing the on-off valve 43, the gas vent passage 29 is shut off.

According to this embodiment, the following effects can be achieved.

First, it is possible to eliminate the pressure increase from the time when the pouring port 13 is closed by the plunger 15 until the evacuation is started. This is because the operation of the injection cylinder 19 excites the solenoid 109 of the electromagnetic switching valve 103 via the electric circuit 107 and switches it to the switching position 103a, thereby opening the piping 101 and the gas vent passage 29 to the atmosphere. This is because he did so.

The situation is shown in Figure 2. FIG. 2 is a characteristic diagram showing the change in air pressure within the pipe 31 over time. As shown in FIG. 2, there is no pressure increase after the pouring port 13 is closed, and the pressure remains at atmospheric pressure.

In this way, by preventing a pressure increase, it is possible to prevent air from being drawn into the molten material to be injected, and it is possible to improve the quality of the product by eliminating the occurrence of internal defects such as blowholes.

Also, the striker 21 is the vacuum start limit switch 2.
3 is activated to start evacuation, the electromagnetic switching valve 103 is switched to the switching position 103b, and the piping 101 is switched to the switching position 103b.
, so the vacuuming action is not impaired in any way.

Next, a second embodiment will be described with reference to FIG.

In this embodiment, the function of the electromagnetic switching valve 35, 103 in the first embodiment is realized by one electromagnetic switching valve 111 as a switching means.

That is, the electromagnetic switching valve 111 has a switching position 111a,
111b, the injection cylinder 19 is driven, and the striker 21 is activated by the vacuum state limit switch 23.
is switched to the switching position 111a by the compression coil spring 113 until it is activated. In other words, it is always open to the atmosphere.

Then, when the striker 21 operates the vacuum start limit switch 23, the solenoid 115 is excited via the electric circuit 107 and switched to the switching position 111b. As a result, the gas vent passage 29 is brought into communication with the vacuum suction device 33, and a predetermined vacuum is drawn.

Therefore, in this embodiment as well, the same effects as in the first embodiment can be achieved, and the number of parts can be reduced, so that the configuration can be simplified.

(Effects of the Invention) As detailed above, according to the degassing method and degassing device for an injection molding machine according to the present invention, the degassing path is opened to the atmosphere until the evacuation is started. Air entrainment due to pressure increase can be prevented, and internal defects such as blowholes can be prevented from occurring, thereby improving product quality.

[Brief explanation of drawings]

1 and 2 are diagrams showing a first embodiment of the present invention, in which FIG. 1 is a sectional view showing the configuration of an injection molding machine, FIG. 2 is a characteristic diagram showing pressure changes in the exhaust path, and FIG. The figure is a sectional view showing the structure of the main parts of the injection molding machine according to the second embodiment, FIGS. 4 and 5 are views showing the conventional example, and FIG. 4 is a sectional view showing the structure of the injection molding machine. FIG. 5 is a characteristic diagram showing pressure changes in the exhaust path. DESCRIPTION OF SYMBOLS 1... Fixed mold, 3... Movable mold, 9... Cavity, 13... Pouring spout, 15... Plunger, 19
...Injection cylinder, 29...Gas vent passage, 33...
Vacuum suction device, 43... Opening/closing valve, 103... Electromagnetic switching valve (switching means). Agent Patent attorney Hiroshi Kitayo (and 2 others) Procedural amendment December 3, 1991 2゜3゜4゜1990 Patent Application No. 245787 Name of invention Gas venting method and device for injection molding machine Relationship with the case of the person making the amendment Patent applicant Address: 762 Mezakicho, Fuchu City, Hiroshima Name: Ryobi Co., Ltd. Representative: Hiroshi Urakami, President and CEO

Claims (2)

[Claims] (1) With the on-off valve inserted in the gas vent path open, the molten material to be injected is injected into the cavity through the pouring port, and the molten material to be injected is poured into the plunger driven by the injection cylinder. After a predetermined period of time after the pouring port is closed by the plunger, a vacuum is drawn through the gas vent passage by a vacuum suction device, and then the vacuum is stopped by closing the opening/closing valve. A method for degassing an injection molding machine, characterized in that the degassing path is kept open to the atmosphere until the vacuum suction device starts evacuation. (2) With the opening/closing valve inserted in the gas vent passage open, the molten material to be injected is injected into the cavity through the pouring port, and the molten material is poured into the cavity by the plunger driven by the injection cylinder. Extrusion is continued, and after a predetermined period of time after the pouring port is closed by the plunger, a vacuum is drawn through a gas vent passage by a vacuum suction device, and then the vacuum is stopped by closing the opening/closing valve. In the degassing device of the molding machine, a switching means is provided on the secondary side of the degassing path, and the degassing path and the vacuum suction device are shut off until the vacuum suction device starts evacuation. An injection molding machine characterized in that the degassing passage is opened to the atmosphere, and at the same time when the vacuum suction device starts evacuation, the degassing passage and the vacuum suction device are communicated to stop the degassing passage from being opened to the atmosphere. degassing device.