JPH034430Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a degassing device in a mold cavity and a casting sleeve in an injection molding machine such as a die casting machine.

[Prior Art] In injection molding methods such as die casting, cavities are generated in the cast product due to gas in the cavity during injection, and it is necessary to remove the cavities.

Conventionally, degassing devices for injection molding machines have been designed to close an on-off valve attached to a degassing hole led from the mold cavity depending on the flow rate of the molten metal (see Japanese Patent Publication No. 59-309). ), one in which a temperature-sensitive element is placed on the valve head as a molten metal detector (see Japanese Patent Application Laid-open No. 59-130670), and one in which molten metal is detected and the actuator is operated by the signal (Japanese Unexamined Patent Publication No. 1983-130670). 61-195853) etc. are known.

[Problems to be solved by the invention] In general, when a gas vent path is introduced from the cavity, the flow of molten metal in the gas vent path is caused by (a) molten metal scattering while filling the cavity; In some cases, the metal is discharged as a small lump of molten metal into the gas vent passage.
(b) After filling the cavity, the gas may proceed continuously through the gas vent path; (c) The gas may proceed intermittently.
Particularly when injection molding is performed at high speeds, if the molten metal splashes into the gas vent path and adheres to the valve seat of the on-off valve, the on-off valve will not operate smoothly afterwards.
As a result, it becomes inoperable. Therefore, it is necessary to instantly react to such high-speed molten metal splashes and close the gas vent valve to prevent the molten metal from reaching the downstream side of the on-off valve.

However, conventional degassing devices detect the flow of molten metal using inertia of the molten metal, molten metal pressure, heat sensors, molten metal detection sensors, etc. I can't do it,
Therefore, responsiveness regarding the closing operation of the on-off valve is not good. As a result, problems such as molten metal adhering to the on-off valve tend to occur, the on-off valve may not be seated properly, gas may not be vented completely, and the opening/closing operation of the on-off valve may be hindered. Issues such as the number of people living in the country remained unresolved.

Therefore, the present invention provides an electrical connection between the sensing rod and the electronic circuit that is activated in response to the first contact by the instantaneous contact of the molten metal with the sensing rod, regardless of the flow of the molten metal in the degassing channel. By connecting the valve and closing the valve instantaneously, the gas inside the cavity can be reliably removed during injection, making it suitable for degassing devices of injection molding machines with faster injection conditions. To provide a gas venting device for an injection molding machine that is capable of casting high-quality castings without voids, and is suitable for extracting a large amount of gas.

[Means for Solving the Problems] That is, in the present invention, a gas venting passage is introduced into the mold 1 forming the cavity 5, one end of the gas venting passage is communicated with the cavity 5, and the other end of the gas venting passage is connected to the mold 1 forming the cavity 5. In a gas venting device for an injection molding machine having an on-off valve 9 attached to the end thereof, a valve actuating piston 12f and a valve actuating piston 12f are operatively connected to the on-off valve to open and close the on-off valve. A valve driving mechanism 12 having a solenoid valve 12a to be driven; detects the molten metal by instantaneous contact with the conductive molten metal filled in the cavity 5 and installed in the gas vent passage, and generates a molten metal detection signal. Detection rod 10 that generates
, an electric circuit 20 that outputs a molten metal detection start signal 11c and a reset signal 11d, and the detection rod 10.
and a flip-flop circuit electrically connected between the electromagnetic valve 12a and the electric circuit and capable of detecting an edge of the molten metal detection signal,
The flip-flop circuit becomes operable upon input of the molten metal detection start signal 11c, switches the solenoid valve to the first position at the first rising pulse signal of the molten metal detection signal, and switches the valve actuating piston 1 to the first position.
2f to the first position to close the on-off valve 9, and by inputting the reset signal 11d, switch the solenoid valve to the second position and move the valve operating piston 12f to the second position. The above-mentioned problem has been solved by providing a gas venting device for an injection molding machine, which is characterized by at least opening the on-off valve 9.

[Operation] When the first molten metal or its droplets, which are energized by the injection molding pressure, first contact the detection rod, a molten metal detection signal is sent to the flip-flop circuit, and the flip-flop circuit responds to this molten metal detection signal and immediately turns on an electromagnetic element. Outputs an activation signal to the valve. For example, when a known flip-flop circuit is used, when the first molten metal detection signal from the detection rod is input, the voltage level at its Q terminal changes from low level to high level, and the detection result is held. Retention of detection results from this first molten metal detection (maintaining high level)
Based on this, the solenoid valve is activated instantaneously, actuating the valve actuating piston and closing the on-off valve. It is unavoidable that there will be a delay in the closing time of the on-off valve depending on the capabilities of the solenoid valve and the valve actuating piston. However, in the present invention, even if the molten metal detection signal is in the form of a pulse, the flip-flop circuit performs edge detection based on the first molten metal detection signal, and that signal can be used to send a drive signal to the solenoid valve. In that it is possible,
It is particularly important that the closing timing of the on-off valve is better than in conventional devices.

[Example] Hereinafter, an example of the present invention will be described based on the drawings.

As shown in FIG. 1, a mold 1 is a fixed mold 2.
and a movable mold 3, and a gas vent passage 6 communicating with a cavity 5 is provided in the dividing surface portion 4 of both the molds 2 and 3. This degassing passage 6 is provided on the opposite side of the gate 7 to the cavity 5, and its outer end is either open to the atmosphere or connected to a vacuum suction device 8 as shown in FIG. The gas inside the cavity 5 can be discharged to the outside of the mold.

The vacuum suction device 8 includes an electromagnetic switching valve 8a, a tank 8b, a vacuum pump 8c, and a motor 8d.

An on-off valve 9 that can freely open and close the gas vent path 6 is provided at the outer end of the gas vent path 6, and a sensor that can detect conductive molten metal to be injected is provided in the middle of the gas vent path 6. A rod 10 is provided. An electronic circuit 11 is electrically connected to the detection rod 10, which is activated only by instantaneous contact with the molten metal to be injected.

The electronic circuit 11 includes a noise removal circuit 11a
and a flip-flop circuit 11b for detecting the edge of the signal from the detection rod 10 and outputting a drive signal for a solenoid valve to be described later.

The flip-flop circuit 11b is electrically connected to an electric circuit 20 (control section after casting) in order to receive a signal 11c for starting molten metal detection and a reset signal 11d.

A valve drive mechanism 12 is electrically connected to the electronic circuit 11 to close the on-off valve 9 based on detection signals from the detection rod 10 and the electronic circuit 11.

The valve drive mechanism 12 includes a solenoid valve 12a, an air source 12b (compressor), and a pressure regulating valve 12.
c and a valve actuation cylinder 12d, which are connected to each other by piping 12e.

The valve actuating cylinder 12d is operated by a valve actuating piston 12f having a stepped portion in a piston front chamber 12.
g, a small-volume piston middle chamber 12h, and a piston rear portion 12i.

The pressure regulating valve 12c is connected midway between the piston middle chamber 12h and the piping 12e of the solenoid valve 12a, so that the locking force for preventing the on-off valve 9 from closing prematurely can be adjusted.

Further, the flip-flop circuit 11b of the electronic circuit 11 is connected to the electromagnetic valve 12a so that the operation of the electronic circuit 11 simultaneously exhausts compressed air from the piston middle chamber 12h and supplies compressed air to the piston front chamber 12g. I've let it happen. As is well known, a flip-flop circuit is a bistable multivibrator in which one of the two active electronic devices remains conductive while the other remains non-conductive until an external pulse is applied. In the present invention, the molten metal detection signal from the detection rod 10 is used as an external pulse to generate a drive signal for driving the electromagnetic valve 12a. Flip-flop circuit 11b can also be called a semiconductor switch, and its operating time is extremely fast. That is, when the molten metal detection signal is input, a drive signal for driving the solenoid valve 12a can be output without time delay. In other words, the time required for memory retention in a flip-flop circuit is almost equal to zero.

The opening/closing valve 9 is connected to the piston 12f, and opens and closes the gas venting path 6 by moving toward and away from a valve seat 12j provided in a part of the gas venting path 6.

Further, the gas vent passage 6 is formed in a net shape with a plurality of baffling protrusions (not shown) provided so that the molten metal to be injected flows with sufficient time, or is formed in a meandering shape.

Furthermore, a casting sleeve 14 that communicates with the runner 13 and is provided with a pouring port 14a is fixed to the fixed mold 2. A plunger 16 is advanced by the injection cylinder 15, and the inside of the casting sleeve 14 is opened from the pouring port 14a. The molten metal injected into the runner 1
3. Fill the cavity 5 from the gate 7.

In the figure, 17 is a striker, 18 is a vacuum limit switch, and 19 is a high speed limit switch.

Next, the operation of the present invention will be explained in detail.

The attached drawings show the state before injection molding begins. In this state, the molten metal to be injected is injected from the pouring port 14a, and the injection cylinder 15 is actuated by the output signal 15a from the electric circuit (control unit 20 of the casting machine) to move the plunger 16 forward.

At this time, a signal 11c for starting molten metal detection is sent to the electronic circuit 11 from the electric circuit 20 (control unit of the casting machine). (The signal to start molten metal detection may be sent during injection). This start signal 11c makes the flip-flop circuit ready for operation.

After the plunger 16 closes the spout 14a, the striker 17 closes the vacuum limit switch 18.
When the vacuum limit switch 18 comes into contact with the
The electromagnetic valve 8 is controlled by the electric circuit 20 (the control section of the casting machine).
a is activated, and the air and gas present in the sleeve 14 and cavity 5 are discharged to the outside of the mold 1 through the gas vent passage 6 and the on-off valve 9.

Note that if the outer end of the gas vent passage 6 is not connected to the vacuum suction device 8 and is directly exposed to the atmosphere, the air or gas is passed through the on-off valve 9 to the mold 1.
It is naturally discharged outside.

Further, the plunger 16 moves forward, and the striker 1
When the high speed limit switch 7 comes into contact with the high speed limit switch 18 and is activated, the molten metal to be injected is filled into the cavity 5 at high speed.

During filling of the cavity 5 with molten metal, small lumps of molten metal are scattered and discharged into the gas venting path 6, or molten metal to be injected continuously moves through the gas venting path 6 after filling the cavity 5, or intermittently. The advancing molten metal to be injected momentarily contacts a detection rod 10 attached in the middle of the gas vent path 6. This momentary contact alone activates the electronic circuit 11, ie, activates the flip-flop circuit 11b, and immediately sends a solenoid valve drive signal to the solenoid valve 12a, causing the solenoid valve 12a to operate. By the operation of the solenoid valve 12a, compressed air is supplied to the piston front chamber 12g of the valve actuation cylinder 12d, and at the same time, the compressed air that had been supplied to the piston middle chamber 12h to prevent the on-off valve 9 from retreating is discharged. , the on-off valve 9 is seated on the valve seat 12j, and the valve closing operation is completed.

After injection molding, the mold is opened and the burr is removed from the gas vent passage 6 along with the cast product, and the electric circuit 2 is removed.
0 (control unit of the casting machine) sends a reset signal 11d to the electronic circuit 11, the solenoid valve 12a switches and operates, the compressed air from the piston front chamber 12g is discharged, and the compressed air is supplied to the piston middle chamber 12h. The piston 12f moves forward, the opening operation of the on-off valve 9 is completed, and preparations are made for the next injection molding.

Next, the operation timing of the gas venting valve 9 in the gas venting device of the present invention will be compared with that of the conventional gas venting device.
For example, FIG. 2 shows data comparing the operation timing of the gas vent valve of the gas venting device described in Japanese Utility Model Application Publication No. 61-195853 by the present applicant.

A to D1 in FIG. 2 show an example of the conventional gas venting device described above, and B2 to D2 in FIG.
shows an example of the present invention.

A shows the state in which the detection rod 10 detects molten metal, and the pulse-like signals from a1 to a2 are as follows.
This means that the scattered small molten metal lumps are intermittently in contact with the detection rod 10 for a short period of time. Further, a stable signal after a2 means that the molten metal continues to advance through the gas vent path, and as a result, the detection rod constantly detects the molten metal and generates a continuous detection signal. Of course, the waveform of A is the same in the present application.

B1 indicates the excitation timing of the solenoid valve 12a. In conventional devices, a solenoid valve drive signal is supplied to the solenoid valve via an electric circuit that receives a molten metal detection signal. For example, a mechanical switch (mechanical relay) was used as the electric circuit. When such a relay is used, even if the detection rod detects molten metal, the relay cannot operate between a1 and a2 because the signal is a pulse. The relay attempts to start operating for the first time upon receiving continuous molten metal detection signals after a2. However, it takes about 6.8ms for the magnet of the solenoid valve to start energizing in response to the drive signal from the electric circuit, and for the magnetic force to be generated in the coil and for the magnet to work.
15ms to 2 and 6.8ms for magnet to work
The switching operation of the solenoid valve will not be completed for a total of 21.8ms.

C1 indicates the operation timing of the valve actuation cylinder 12d, and the solenoid valve 12 due to the operation of the electric circuit.
It took 12 ms for the air sent from the air source 12b to accumulate in the piston front chamber 12g by the switching operation a to start moving the gas vent valve 9 in the closing direction.

D1 indicates the operation timing of the gas vent valve 9,
It took 4.3 ms for the gas vent valve 9, which was in the open state, to be completely closed.

Therefore, from the first molten metal detection signal a1 until the gas vent valve 9 is completely closed, the total amount of
It took 38.1ms.

On the other hand, according to the degassing device of the present invention, the flip-flop circuit 11b can immediately send a solenoid valve driving signal in response to the first molten metal detection signal a1, and the flip-flop circuit 11b can immediately send a solenoid valve drive signal, starting from the time when the first molten metal detection signal is detected. , necessary for the switching operation of the solenoid valve described above.
The switching operation could be completed in a period of only 6.8ms.

C2 indicates the operation timing of the valve drive cylinder 12d, and D2 indicates the operation timing of the gas vent valve 9. Here, 11ms at C2 is C1
corresponds to 12ms in D2, and 4.7ms in D2 corresponds to D
This corresponds to 4.3ms in 1. Differences in these data are due to experimental error.

Considering the above results, in the degassing device of the present invention, from the first molten metal detection signal a1
The gas vent valve was able to close completely after 22.5ms had passed, making it possible to close the gas vent valve in an extremely short time compared to conventional devices. In other words, in the conventional degassing device, from a1 to a
During the period up to 2, the solenoid valve cannot be energized, so droplets of molten metal pass through the gas vent valve that is still open and reach the downstream side of the gas vent valve, and when it cools and solidifies, the gas is released. There was a possibility that a problem would occur in which the vent valve would not be able to close, but with the degassing device of the present invention, it is possible to immediately drive the solenoid valve based on the first molten metal detection signal. This eliminates the inconvenience caused by overheating.

(Effects of the invention) Since the degassing device in the injection molding machine according to the present invention is configured as described above, during injection, the cavity 5 is filled with the molten metal to be injected, and the molten metal to be injected that has entered the gas vent path 6 is detected. A momentary contact with the rod 10 activates the electronic circuit 11, which activates the valve drive mechanism 12 and closes the on-off valve 9, so that the molten metal to be injected continuously enters the gas vent path 6. Even when the injection conditions are higher and the molten metal enters intermittently as small lumps,
By quickly and accurately closing the on-off valve 9, the molten metal to be injected will not reach the on-off valve 9 before the valve is closed, so the molten metal will not be inserted into the on-off valve 9, and furthermore. The gas in the cavity 5 and the casting sleeve 14 can be reliably extracted, a high-quality cast product without cavities can be obtained, and the effect can be applied to extracting a large amount of gas from the cavity 5 of a mold.

[Brief explanation of drawings]

Fig. 1 is a longitudinal side view showing an embodiment of a degassing device for an injection molding machine according to the present invention, and Fig. 2 shows a degassing device using a conventional electric circuit and an electronic circuit of the present invention. It is a comparison diagram of a valve operation timing chart with a gas venting device. 1...Mold, 5...Cavity, 6...Gas vent path, 9...Opening/closing valve, 10...Detection rod, 11...
Electronic circuit, 11b...Flip-flop circuit, 1
2... Valve drive mechanism, 12a... Solenoid valve, 12d...
...Valve actuation cylinder.

Claims (1)

[Claims for Utility Model Registration] A gas vent passage is introduced into the mold 1 forming the cavity 5, one end of the gas vent passage communicates with the cavity 5, and an on-off valve 9 is attached to the other end of the gas vent passage. A degassing device for an injection molding machine, which is operatively connected to the on-off valve to open and close the on-off valve, has a valve actuating piston 12f, and a solenoid valve 12a that drives the valve actuating piston 12f. a valve drive mechanism 12; a detection rod 10 that is disposed in the gas vent path and detects the molten metal filled in the cavity 5 by instantaneous contact with the molten metal to be injected, and generates a molten metal detection signal; a vacuum suction device 8 connected to the cavity 5 through the gas vent passage when the on-off valve is open to suck and exhaust at least the air in the cavity 5 until the initial stage of injection of the molten metal to be injected; Detection start signal 11c and reset signal 1
1d, and a flip-flop circuit 11 which is electrically connected between the detection rod 10 and the electromagnetic valve 12a and is also electrically connected to the insulator electric circuit and capable of detecting the edge of the molten metal detection signal. The flip-flop circuit becomes operable upon input of the molten metal detection start signal 11c, switches the solenoid valve 12a to the first position at the first rising pulse signal of the molten metal detection signal, and turns the valve actuating piston 12f. The opening/closing valve 9 is moved to the first position and the opening/closing valve 9 is closed, and the reset signal 11d is
Gas of an injection molding machine for high-speed injection characterized in that the solenoid valve 12a is switched to the second position and the valve operating piston 12f is moved to the second position to open the on-off valve 9. Extraction device.