JPH0238062B2 - KANAGATAYOGASUNUKISOCHI - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a mold gas venting device for extracting gas from a mold cavity during injection molding using an injection molding device such as a die casting machine or an injection molding machine. be.

[Prior art] Conventionally, in injection molding equipment such as die-casting machines, when molten material is injected and filled into a cavity at high speed and high pressure, the gas in the cavity may not escape completely, resulting in the formation of cavities in the product. .

Therefore, the present applicant developed a degassing device for molds that can remove a large amount of gas in a short period of time.
Publication No. 309) was developed. This degassing device is
A gas vent groove that communicates with the cavity, a valve that slides in the axial direction at its end, and a bypass as a gas exhaust passage that detours from the middle of the gas vent groove to the side of the valve part are installed on the separation surface of the mold. During injection molding, the gas in the cavity is drawn out of the mold through the bypass and the valve body opening, and when the injected molten material fills the cavity and reaches the end of the gas vent groove. In addition, the valve body is pushed up by the action of this large-mass molten material, and this valve body closes the end of the bypass.

However, in this degassing device,
The operation of the valve body is not always satisfactory,
In particular, when the melt reaches the valve element discontinuously at the leading end of the flow, the valve element may not operate satisfactorily. In other words, even if the valve closes once due to the action of the molten material, the next time gas comes, it will open due to the action of the compression spring installed at the rear end of the valve, and then the molten material will come again and close the valve. In this case, since the molten material in front of the valve position that came earlier is about to solidify, the force of the molten material that came later does not act directly on the seed, but acts on the molten material that comes earlier. At this time, since there is frictional resistance between the molten material that was solidifying first and the surrounding mold surface, the force exerted on the valve by the molten material that came later becomes weaker, and the valve does not close fully. As a result, there was a risk that melt entering from the bypass could enter the valve chamber through the valve opening.

Therefore, the present applicant further proposed a degassing device shown in Japanese Patent Publication No. 59-310. This degassing device is equipped with a member such as a tension spring that biases the valve in the closing direction, a compression spring that locks the valve in the open position, and a member such as a ball. The valve is closed against the locking force of the member, and the valve body can be quickly and reliably closed when the first melt reaches the valve body.

[Problems to be Solved by the Invention] However, such conventional gas venting devices are not necessarily satisfactory in terms of maintaining the locking force in the open position of the valve for a long period of time. In other words, when the valve is repeatedly opened and closed during each injection cycle, the ball, leaf spring, and the parts that come into contact with these wear out, and the locking force decreases, causing the valve to close before the melt arrives. There was a risk that it would be impossible to vent the gas. Conversely, if the contact surface of the ball becomes rough or deformed, the locking force at the valve open position will become stronger, and even if molten material comes, the locking force will exceed the collision force and the valve will not close. This may cause the molten material to enter the valve chamber, or the collision force of the molten material acting on the valve is small, so even if the lock is released, it takes time for the valve to close, and the molten material may enter the valve during that time. I had a problem with it.

[Means for Solving the Problems] In order to solve these problems, in the present invention, the end portion of the valve stem on the side opposite to the valve body is slidably fitted into the inner hole of the spool, and A piston having a flange portion at its end is fixed, and the flange portion is configured to close and open between the chamber on the side opposite to the valve body of the flange portion and the chamber on the valve body side of the piston by moving the valve stem back and forth. The ports provided in the three chambers, the chamber opposite to the valve body, the chamber opposite to the valve body of the piston, and the chamber opposite to the valve body of the flange portion, were connected to a pressure fluid source through piping having a switching valve.

[Operation] Until the molten material injected into the cavity reaches the gas vent hole, the chamber on the side of the flange part opposite to the valve body is pressurized, and the space between the chamber on the side of the flange part opposite to the valve body and the side chamber of the piston on the valve body side is closed. Since the fluid pressure is not acting on the valve body side chamber of the piston and the valve is held open, the gas in the cavity flows through the valve opening and the spool inner hole. It is discharged from the discharge hole. During injection, the melt reaches the valve opening and collides with the valve bottom, or fluid pressure acts on the end face of the valve body side chamber of the piston and the piston moves up, causing the valve to move in the closing direction, but the valve closes slightly. However, when it moves, the chamber on the side opposite to the valve body of the flange communicates with the valve body side of the piston, fluid flows into the valve body side of the piston, and fluid pressure acts on the piston. The difference in pressurized areas on both sides generates a large force in the direction of closing the valve, which quickly closes the valve and maintains the valve closed state.

[Example] Figures 1 to 4 show an example in which the mold degassing device according to the present invention is implemented in a die-casting machine. Top view and pneumatic circuit diagram, Figure 3 is a partially cutaway front view of the degassing device and the mold in which it was installed, and Figure 4 corresponds to Figure 1 with the degassing device separated from the mold. FIG. In the figure, a cavity 4 is formed in the dividing surface 3, which is the joint surface between the fixed mold 1 and the movable mold 2, which are shown in a clamped state. Molten metal 7 is injected and filled through the sleeve portion 5 and gate 6. Reference numeral 8 denotes a product extrusion device that extrudes a product obtained by solidifying the molten metal 7 from the cavity 4 of the movable mold 2 after opening the mold. A spool hole 11 that communicates with the cavity 4 through a gas venting path 9 and a gas venting groove 10 is opened to the outside at the upper end of the dividing surface 3 of the molds 1 and 2. A bypass 12 that branches off midway and takes a detour is communicated with the opening of the gas vent groove 10 to the spool hole 11.

Bracket 13 fixed to the top surface of fixed mold 1
At the top, a fluid pressure cylinder 14 is fixed concentrically with the spool hole 11 and the gas vent groove 10, and a flange 15a, which is the working end of a piston rod 15 that moves back and forth using the fluid pressure, is designated by the reference numeral 16 as a whole. A holder 18 that clamps the upper end of a spool 17 of the gas venting device shown is fixed, and the spool 17 is fixed to the holder 18 with a presser foot 19 and a bolt 20. The spool 17 is formed into a cylindrical shape with a bottom, and a stepped portion 17a is provided at the lower end of the spool 17.
The gas venting device 1 is activated by moving the piston rod 15 back and forth.
The step portion 17a engages with the spool hole 11 or separates from the spool hole 11 as the whole 6 moves up and down.

FIG. 5 is a sectional view of the main part of the degassing device,
The gas venting device 16 will be explained below based on FIGS. 1 to 5. The spool 17 is divided into a member 17b and a member 17c, and the flange of the valve guide 21 fitted into the inner hole is held between the members 17b, 17c and the valve guide 21.
1 is integrated. A piston 22 is located above the valve guide 21 and is slidably fitted into the inner hole 17d of the member 17b, and has a central screw fitted into the inner hole 21a of the valve guide 21 so as to be able to move forward and backward. A threaded portion is screwed into and integrated with the valve rod 23, and a valve body 24 is integrally formed at the lower end of the valve rod 23. On the other hand, a valve seat 17e is formed at the lower opening end of the spool 17, and the valve body 2
4 and the valve seat 17e are configured such that when the molten metal 7 rising in the gas vent groove 10 pushes the valve body 24 from the open state shown in FIG. 1, it rises and enters the closed state. In addition, in the illustrated valve open state, the valve body 2
4 engages with and closes the opening step of the gas vent groove 10. What is indicated by the symbol 17f in FIG.
This is a discharge hole for discharging the gas guided to the valve chamber 17g of the spool 17 through the bypass 12 to the outside when the valve is open.

Ports 26a and 26b are opened in the side chamber of the piston 22 opposite to the valve body, that is, the head side chamber 25 for the member 17b of the spool 17 that forms a cylinder together with the piston 22.
is connected to a compressed air source 30 via a pipe 29 that includes a switching valve 27 having a solenoid SOL-A and a pressure reducing valve 28 . On the other hand, a flange 22a is formed on the valve body side of the piston 22, and a rod side main chamber 31, which is a chamber on the side opposite to the valve body of the flange 22a, and a main chamber 31 on the side opposite to the valve body of the flange 22a and a side opposite to the valve body of the flange 22a, A rod-side auxiliary chamber 32, which is a valve body side chamber, is formed respectively, and an O-ring 33 is fitted on the outer periphery of the upper surface of the rod-side auxiliary chamber 32 by a groove so as not to come off. That is, when the valve is open, the lower surface of the flange 22a is pressed against the O-ring 33 fitted in the rod-side auxiliary chamber 32 provided at the upper part of the valve guide 21a, and the rod-side main chamber 31 and the rod-side main chamber 31 are connected to each other. The collateral chamber 32 is separated. A port 34 provided in the main chamber 31 on the rod side is connected to a compressed air source 30 via a pipe 37 equipped with a switching valve 35 having a solenoid SOL-B and a pressure reducing valve 36. A port 38 provided in the chamber 32 is connected to a pipe 4 equipped with a switching valve 39 having a solenoid SOL-C.
0 and a compressed air source via the pressure reducing valve 36.

With this configuration, when solenoid SOL-A is energized and solenoids SOL-B and SOL-C are demagnetized, compressed air flows to port 2.
When the water flows into the head side chamber 25 from 6b and 26a and pushes down the piston 22, the valve seat 17e opens, and the lower surface of the piston 22 is pressed against the O-ring 33 as shown in FIGS. 2 and 5. In this state, solenoid SOL-B is energized, and then solenoid SOL-
Demagnetize A. In this state, compressed air flows into the rod side main chamber 31, and some compressed air may leak into the head side chamber 25 through the gap between the piston 22 and the inner hole 17d of the member 17b. Since it is discharged into the atmosphere through the switching valve 27 with almost no piping resistance, the head side chamber 25
is approximately atmospheric pressure. On the other hand, compressed air does not flow into the rod side auxiliary chamber 32 from the rod side main chamber 31, and the rod side auxiliary chamber 3, which was present before the valve closing operation,
Since the compressed air in the valve rod 2 leaks through the gap between the valve rod 23 and the inner hole 21a of the valve guide 21, the rod side auxiliary chamber 32 is also at atmospheric pressure.

In this device, as shown in FIG. 5, the lower pressure receiving area S2 of the flange 22a is larger than _the upper pressure receiving area _S1 . In this device, the diameter of the valve stem 23 is d ₁ , the diameter of the upper part of the piston 22 is d ₂ , and the lower surface of the piston 22 and the O-ring 3 are
Let d3 be the diameter of the seal part due to ₃ , and let P be the pressure of the compressed air acting on the rod side main chamber 31, then the force _F1 in the valve opening direction acting on the flange 22a is _F1 = π/4 ( d ₃ ² - _{d 2} ² )×P When compressed air is applied to the main chamber 31 on the piston side, the lower surface of the piston 22 is pressed against the O-ring 33, and due to the action of the force F ₁ that holds the valve open, The valve is kept open. In this state, if the valve body 24 is pushed up slightly in the closing direction by an external force and the lower surface of the piston 22 separates from the O-ring 33 even a little, compressed air will also enter the rod-side auxiliary chamber 32 through this gap. ₂ = π/4 (d ₃ ² - d ₁ ² ) x P is newly applied to the lower surface of the piston 22, so F ₂ - F ₁ = π/4 (d ₂ ² - _{d 1} ² ) x P> 0, and the piston 22 rises rapidly. Therefore, the valve seat 17e is quickly maintained in the closed state.

In addition, the solenoid SOL-
When C is excited, _pressure P by compressed air acts on the lower surface of the piston 22, and the piston ₂₂
The valve is pushed upward by the force of , the valve closes, and the valve remains closed.

The operation of the mold degassing device configured as above will be explained. After the molds 1 and 2 are clamped, the fluid pressure cylinder 14 is operated to lower the entire degassing device 16, and the stepped portion 17a of the spool 17 is fitted into the spool hole 11 as shown in FIG. Then, as described above, after the solenoid SOL-A is energized and the solenoids SOL-B and SOL-C are demagnetized to lower the piston 22, the solenoid SOL-B is further energized and the solenoid SOL-A is demagnetized. In this state, the lower surface of the piston 22 is pressed against the O-ring 33, and the valve body 24 and valve seat 17e maintain the open state as shown in FIGS. 1 and 2. At this time, the lower surface of the valve body 24 closes the upper end opening of the gas vent groove 10, and the gas vent groove 10 and the spool valve chamber 17g are communicated through the bypass 12 and the valve opening. In this state, when the molten metal is injected into the injection port of the injection sleeve and the plunger of the injection cylinder is advanced, the molten metal 7 is injected and filled into the cavity 4 through the fixed sleeve portion 5 and the gate 6. Accordingly, the gas in the cavity 4 passes through the gas vent path 9 and the gas vent groove 10 to the valve body 2.
4, and is discharged from the discharge hole 17f via the bypass 12 and the valve chamber 17g. At this time, the piston 22 is
The valve opening holding force represented by F ₁ is determined based on the size of the flange 22a, the set pressure of the pressure reducing valve 36, etc. Then, the molten metal 7 is
After the gas is almost filled, it rises in the gas vent groove 10 and hits the lower surface of the valve body 24 together with the gas. At this time, the mass of the molten metal 7 is much larger than the mass of the gas,
Since a large inertial force acts on the lower surface of the valve body 24,
The valve body 24 is flipped upward. In this way, if the valve body 24 moves upward even slightly, the piston 22
When the lower surface of the flange 22a separates from the O-ring 33, the compressed air in the main chamber 31 on the rod side flows into the piston 2.
The rod enters the sub-chamber 32 on the rod side through the gap between the lower surface of the piston 22 and the O-ring 33, and the force expressed by F ₂ - _{F 1} as described above acts on the lower surface of the piston 22, causing the piston 2
2 rises rapidly. As a result, the valve seat 17e is closed by the valve body 24 and the valve is maintained in the closed state, so that movement of the molten metal 7 is blocked at the position of the valve body 24.

After the molten metal 7 is pressurized and cooled for a predetermined time with the valve body 24 closing the gas vent groove 10 and the bypass 12, gas is vented by the fluid pressure cylinder 14 as shown in FIG. When the entire device 16 is raised, the cavity 4, the gas vent groove 10,
The valve body 24 separates from the solidified material 41 that has solidified in the bypass 12, but at this time, the valve body 24 is prevented from moving upward due to separation resistance between the valve body 24 and the solidified material 41, and the spool 17 is raised. The valve body 24 opens later than that, and is maintained in the open state by the action of the compressed air pressure. After cooling, the product in the cavity 4 is opened and pressed by a product extrusion device 8. Figure 4 shows the solenoid
Demagnetize SOL-A and solenoid SOL-B, SOL-
The valve body 24 is shown closed by energizing C.

6 to 10 are sectional views of essential parts of a degassing device, respectively, showing other embodiments of the present invention corresponding to FIG. 5. First, in the one shown in FIG. 6, a labyrinth groove 42 is provided on the circumferential surface of the inner hole 17d of the spool 17 on which the piston 22 slides, and by doing so, leakage of compressed air can be reduced. . Next, the one shown in FIG.
The inner circumferential surface of the rod-side auxiliary chamber 32 into which the rod is fitted is tapered so that the diameter increases downwardly, thereby reducing leakage of compressed air and reducing the It is possible to prevent the ring 33 from coming off. In addition, the O-ring 33
In the case where a piston 22 is provided, it may be fixed to the lower surface side of the piston 22. Furthermore, the valve shown in FIG. 8 does not include an O-ring 33, but has a stepped portion 21b on the valve guide 21, and a flange 17 on this stepped portion 21b.
The outer circumferential surface of a is fitted, and by doing so, the same function can be provided. In addition, the one shown in FIG. 9 has a plate-shaped rubber gasket 44 interposed in place of the O-ring 33 as a sealing member, and this may be a metal gasket made of copper, lead, etc. instead of rubber. Furthermore, the one shown in FIG. 10 does not use an O-ring or packing, but tapers the flange 17a and the inner circumferential surface of the rod-side auxiliary chamber 32 so that they fit together. It is also possible to provide similar functionality.

In addition, although the above-mentioned embodiment shows a case in which the valve body 24 is closed only by the inertia force of the molten metal, in some cases, the valve body 24 may be closed by an electrical command or the like during injection. It can also be done.

Here, each of the solenoids SOL-A, SOL-B,
The control device of SOL-C will be explained. 11th
The figure is a schematic diagram of a control device using a limit switch, a mold, and a gas venting device for the mold. In the figure, the structure of the mold and the mold gas venting device is the same as that shown in FIG. 3, so the same reference numerals are used and the explanation thereof will be omitted. An injection sleeve 50 having a pouring port 50a is fitted into the fixed sleeve portion 5 of the fixed mold 1, and the molten metal 7 is supplied into the injection sleeve 50 from the pouring port 50a.
Reference numeral 51 denotes an injection cylinder provided concentrically with the injection sleeve 50, and a plunger tip 55, which is the head of a plunger 54 connected via a coupling 53 to a piston rod 52 that moves forward and backward with hydraulic pressure, is connected to the injection sleeve 50. It is slidably fitted into the inner hole of 50. Further, 56 is the switching valve 27,
35, 39 solenoids SOL-A, SOL-B,
An electrical command device consisting of a plurality of limit switches (only one shown) or a limit switch and a timer electrically connected between the SOL-C and the power source 57, and fixed to the coupling 52 via the bracket 13 for injection. The solenoid SOL-A is opposed to a striker 58 extending in the axial direction of the cylinder 51, and by opposing a predetermined portion of the striker 58, the solenoid SOL-A is activated at the predetermined timing described above.
SOL-B and SOL-C are configured to be energized and de-energized.

With the above configuration, when the molten metal 7 is supplied from the pouring port 50a and the plunger tip 55 is advanced by the injection cylinder 51, the molten metal 7
is pushed by the plunger tip 55 and is injected and filled into the cavity 4 as described above. At this time, as the plunger 54 moves forward, the striker 5
8 also moves forward, and the plurality of limit switches 56 sequentially face each other at a predetermined position, so that the solenoids SOL-A, SOL-B, and SOL-C are energized and de-energized at the predetermined timing described above, and the molten metal The valve body 24 is reliably closed by cooperation with the pushing up of the valve body 24 by the inertial force of the valve body 7.

Then, one of the limit switches 56 is connected to the solenoid SOL-C so that the molten metal 7 is transferred to the gas vent groove 1.
If the solenoid SOL-C is energized when passing 0, the compressed air will flow into the rod side auxiliary chamber 32 and pressurize the lower surface of the flange 22a, so the inertia of the molten metal 7 will cause the valve body 24 to It is also possible to close the valve body 24 only by compressed air pressure without having to push it up.

In addition, solenoids SOL-A, SOL-B, SOL
-C is excited by another external signal before injection starts,
It can also be de-energized. However, if the valve body 24 is to be closed by a prospective operation during injection, the solenoid SOL-C of the switching valve 39 is energized during injection.

Further, FIG. 12 is a block diagram of a control device using a magnetic scale, and members given the same reference numerals as in FIG. 11 have the same configurations, so explanations thereof will be omitted. In the figure, a magnetic scale 59 extending in the axial direction of the injection cylinder 51 is fixed to a coupling 53 that communicates the piston rod 52 and the plunger 54, and a magnetic sensor 60 is disposed near the magnetic scale 59. There is. When the magnetic scale 59 moves together with the plunger 54, a pulse signal is extracted from the magnetic sensor 60, and this pulse signal is sent to a comparator 61 for input. On the other hand, a timer (not shown) or a condition setting device 62 for setting at which position in the stroke of the plunger 54 the switching valves 27, 35, 39 are opened is provided, and signals from this are also input to the comparator 61. ing. The comparator 61 is connected to each of the switching valves 27, 35, 39.
It is electrically connected to solenoids SOL-A, SOL-B, and SOL-C of Each solenoid is configured to be energized and de-energized at the predetermined timing mentioned above. In particular, the solenoid SOL-C is energized by a valve opening command from the magnetic sensor 60, and the valve body 24 is closed. 63 is a monitor or recording device, and 64 is a manual switching valve 27, 35, 3.
This is an operation panel that opens and closes 9.

With this configuration, the molten metal 7
When the plunger 54 moves forward for injection and filling, the magnetic scale 59 integrated therewith moves forward, extracts a pulse signal from the magnetic sensor 60, and sends it to the comparator 6.
Enter 1. On the other hand, since the setting signal from the condition setting device 62 is also input to the comparator 61, when these two signals match, a signal is emitted, and the solenoid SOL-C is energized at the predetermined timing mentioned above.
Since it is de-energized, the valve body 24 is reliably closed in cooperation with the pushing up of the valve body 24 by the inertia force of the molten metal 7, or based only on the electric valve opening command signal.

Also in this case, when the molten metal 7 passes through the gas vent groove 10, the condition setting device 62 is configured to operate a solenoid.
If SOL-C is set to be excited, compressed air will flow into the rod side subchamber 32 and the flange 2
Since the lower surface of 2a is pressurized, the valve body 24 can be closed only by compressed air pressure without having to push up the valve body 24 with the inertia force of the molten metal 7.

In addition, when closing the valve body 24 using an electric valve open command signal during injection, the timing of issuing the valve open command signal must be well timed to close the valve body 24.
The gas inside should be sufficiently vented, but it is necessary to prevent the molten metal from entering the gas venting device 16.

Furthermore, as a structure for closing the valve body 24 without pushing up the valve body 24 due to the inertia force of the molten metal 7,
The molten metal 7 is placed at the entrance of the gas vent groove 10 as a molten metal passage.
It is also possible to provide a detection means for detecting the passage of the molten metal, and use the molten metal detection signal to energize the solenoid SOL-C and close the valve body 24. In this case, the means for detecting the molten metal may be, for example, by providing a pair of electrodes and short-circuiting them by the passage of the molten metal 7, or by providing an ultrasonic transmitter and an ultrasonic receiver and by causing the molten metal 7 to pass. By attenuating the transmitted ultrasonic waves, passage of the molten metal 7 can be detected and the valve body 24 can be closed. Further, as a molten metal detection means, a primary coil and a secondary coil whose grooves 10 are demagnetized using a non-magnetic material are provided, and when the molten metal 7 passes, the magnetic flux is blocked and the voltage is changed to detect the passage of the molten metal 7. The body 24 may be closed, or the passage of the molten metal 7 may be detected by supplying a high frequency current to a sensor coil provided in the gas vent groove 10 and changing the impedance of the sensor coil as the molten metal 7 passes. The valve body 24 may be closed.

In the embodiment described above, the gas discharge hole 17f provided in the spool 17 is exposed to the atmosphere.
It is also possible to connect a vacuum suction device to 7f to make the inside of the cavity 4 in a vacuum state, and then inject the molten metal and close the valve body 24.

[Effects of the Invention] As is clear from the above description, in the mold degassing device according to the present invention, the valve is slidably fitted into the inner hole of the spool at the end of the valve stem on the side opposite to the valve body. A piston having a flange portion is fixed to the end on the body side, and the flange portion is configured to close and open between the chamber on the side opposite to the valve body and the chamber on the valve body side of the flange portion by moving the valve stem back and forth. 3: anti-valve body side chamber, piston valve body side chamber, flange part anti-valve body side chamber
By connecting each port installed in the chamber and the pressure fluid source with piping with a switching valve, the valve is kept open during degassing, and the valve body is prevented from closing even slightly if the molten metal collides with the valve body. When the piston moves in this direction, fluid pressure acts on the end of the piston on the valve body side, generating a large force in the direction of closing the valve body, allowing the valve body to close quickly and reliably. Unlike other devices, there is no risk of the locking part being worn out, and the holding force in both the open and closed positions can be reliably maintained for a long period of time, greatly improving durability and reliability. Furthermore, since the valve always operates reliably and the gas is reliably discharged during injection, a high-quality, high-strength injection product without voids can always be obtained reliably and easily. Furthermore, compared to mechanically holding the valve in the open position, the number of parts is reduced, maintenance is easier, and the force for holding the valve in the open position can be adjusted only by adjusting fluid pressure. , adjustment becomes easier.

[Brief explanation of drawings]

1 to 12 show an embodiment of the mold degassing device according to the present invention, FIG. 1 is a longitudinal sectional view thereof, FIG. 2 is a longitudinal sectional view of the main parts, a pneumatic circuit diagram, and Figure 3 is a partially cutaway front view of a mold degassing device and a mold in which it is installed, and Figure 4 is a vertical cross-section showing the degassing device separated from the mold, corresponding to Figure 1. 5 are longitudinal sectional views of the main parts of the mold gas venting device, and FIGS. 6 to 10 are longitudinal sectional views of the main parts of the mold gas venting device, respectively, showing other embodiments of the present invention. , Fig. 11 is a schematic configuration diagram of a switching valve control device using a limit switch, a mold, and a degassing device for the mold, and Fig. 12 is a schematic diagram of a switching valve control device using a magnetic scale, a mold, and a gas venting device for the mold. FIG. 2 is a schematic configuration diagram of a degassing device. 1... fixed mold, 2... movable mold, 4... cavity, 11... spool hole, 16... mold gas venting device, 17... spool, 17d... inner hole, 17e... valve Seat, 17f...Drain hole, 22...
...Piston, 22a...Flange, 23...Valve stem, 24...Valve body, 25...Head side chamber (opposite valve body side chamber of piston 22), 26a, 26b, 34,
38...Port, 27, 35, 39...Switching valve,
29, 37, 40... Piping, 30... Compressed air source, 31... Rod side main chamber (chamber on the side opposite to the valve body of the flange 22a portion), 32... Rod side sub chamber (chamber on the valve body side of the piston 22).

Claims (1)

[Claims] 1. A spool that is formed into a cylindrical shape with a bottom and has a gas discharge hole between the inner and outer circumferential surfaces and whose open end is attached to the spool hole of the mold, and a valve rod that is provided inside the spool so as to be able to move forward and backward. , a valve body is provided at the tip of the valve stem and opens and closes the open end of the spool as the valve stem advances and retreats; In a degassing device for a mold configured to discharge gas in a cavity, a flange is fitted to an end of the valve stem on the side opposite to the valve body and slidably fits into the inner hole of the spool, and the end on the side of the valve body is fitted with a flange. A piston having a section is fixed, and a space between a side chamber of the flange section opposite to the valve body and a side chamber of the piston can be closed and opened by the forward and backward movement of the valve stem. A gas for molds, characterized in that ports provided in three chambers, a body side chamber, a valve body side chamber of the piston, and a side chamber opposite to the valve body of the flange portion, and a pressure fluid source are connected by piping having a switching valve. Extraction device.