JPH035264B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Industrial Application] 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.

[Conventional technology]

Conventionally, in an injection molding apparatus such as a die-casting machine, when a melt is injected and filled into a cavity at high speed and high pressure, the gas in the cavity may not completely escape, 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.
309 Publication), this gas venting device has a gas venting groove that communicates with the cavity, a valve that slides in the axial direction at the end of the gas venting groove, and a gas detour that detours from the middle of the gas venting groove to the side of the valve part. A bypass as a discharge passage is provided on the split surface of the mold, and the gas in the cavity is drawn out of the mold through the bypass and the valve body opening into the injection molding part, and the injected molten material is discharged from the cavity. When the gas reaches the end of the gas vent groove, the valve body is pushed up by the action of the large mass of the molten material, and the 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 body in a discontinuous manner at the leading end of the flow, the valve body 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, the molten material immediately before the valve position that came first is about to solidify, so the force of the molten material that came later does not act directly on the valve, but acts on the molten material that comes before. 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. Melt coming from the bypass may enter the valve chamber through the valve opening.

Therefore, the present applicant further proposed a degassing device disclosed in Japanese Patent Publication No. 59-310. This degassing device is provided with a member such as a tension spring that urges 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 element can be quickly and reliably closed when the first melt reaches the valve element.

[Problem to be solved by the invention]

However, in such conventional mold degassing devices, high-speed injection at a predetermined speed may not be possible due to cases where the shape of the mold or injection conditions are not optimal, or due to galling between the injection plunger tip and the inner circumferential surface of the sleeve. In this case, the molten material that reaches the valve body may become a droplet, or the velocity may be insufficient, causing the valve body to resist the locking force in the closed position. The inability to close the valve allowed melt entering the bypass to enter the valve chamber through the valve opening.

Furthermore, if the valve is repeatedly opened and closed during each injection cycle, the balls, leaf springs, and the members that come into contact with them will wear out, making it impossible to maintain the locking force in the valve closed position for a long period of time. However, due to the decrease in the locking force, the valve would close before the molten material arrived, and there was a risk that degassing would become impossible.

Furthermore, on the contrary, the contact surface of the ball may become rough or deformed, and the locking force at the valve open position may become stronger. The locking force may exceed the valve and prevent it from closing, allowing molten material to enter the valve chamber, or the collision force of the molten material acting on the valve may be small, causing the valve to close even if the lock is released. There was a problem in that it took a long time to complete the process, and during that time, molten material entered the valve chamber.

[Means to solve the problem]

In order to solve such problems, the present invention
This valve body is provided with a valve stem supported in the inner hole of a spool having a gas discharge hole and an open end attached to a spool hole of a mold, and which opens and closes a valve seat at the open end of the spool by moving the valve stem back and forth. In a mold gas venting device that is provided at the tip of a valve stem and discharges gas in the mold cavity from the discharge hole via the open valve seat and the inner hole of the spool, the mold cavity and the valve body are connected to each other. a detection means disposed in a melt passageway between the valve stems to detect passage of the melt, and a valve driving device connected to the detection means and actuated by the melt detection signal, A piston that is slidably fitted into the inner hole of the spool at the body side end and has a flange portion at the valve body side end is fixed,
The side chamber opposite to the valve body of the flange portion is connected to a pressure fluid source, and the space between the side chamber opposite to the valve body of the flange portion and the side chamber of the piston is connected to a pressure fluid source, and the movement of the valve stem driven by the valve driving device moves back and forth. It is constructed so that it can be opened and closed at the flange.

[Effect]

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 chamber on the valve body side of the piston is closed. Since no fluid pressure is acting on the valve body side chamber of the piston and the valve is held open, the gas in the cavity is discharged through the open valve body and the spool inner hole. It is expelled from the hole. When the molten metal filled in the mold cavity passes through the molten metal passage toward the gas vent valve, the detection means detects the molten metal and issues a signal, and the valve drive device operates to raise the piston and close the valve. However, if the valve moves even slightly, the chamber on the side of the flange part opposite to the valve body communicates with the side of the valve body of the piston, and the fluid that was being supplied to the chamber on the side of the flange part opposite to the valve body also flows to the side of the valve body of the piston. inflow,
Since fluid pressure is applied, a large force in the valve closing direction is generated due to the difference in pressurized area between the lower surface of the piston, including the lower surface of the flange, and the upper surface of the flange, causing the valve to rapidly close and maintain the valve closed state. As a result, the intrusion of molten metal into the valve chamber is blocked. In the unlikely event that the detection means makes a detection error due to a break in the electrical wiring, etc., and the gas vent valve does not close despite the signal being issued, the inertia of the molten metal will cause the gas to vent. The valve closes and molten metal does not enter the valve chamber.

〔Example〕

1 to 4 show an example in which a mold degassing device according to the present invention is implemented in a die-casting machine, and FIG. 1 is a partially cutaway front view of the degassing device and a mold in which the degassing device is implemented; Figure 2 is a longitudinal sectional view of the degassing device, Figure 3 is a longitudinal sectional view of the main parts and an air circuit diagram, and Figure 4 shows the degassing device separated from the mold, corresponding to Figure 1. 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. sleeve 5
Molten metal 7 is injected and filled through gate 6 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. At the upper end of the dividing surface 3 of the molds 1 and 2, a spool hole 11 is opened to the outside and communicates with the cavity 4 through a gas venting path 9 and a gas venting groove 10. 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 gas vent groove 10, and a flange 15, which is the active end of a piston rod 15, moves back and forth using the fluid pressure.
A holder 18 is fixed to a for holding the upper end of a spool 17 of a degassing device, which is generally indicated by reference numeral 16, 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 entire degassing device 16 is moved up and down by the forward and backward movements of the gas venting device 5, and the stepped portion 17a engages with the spool hole 11 and separates from the spool hole 11.

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, with an inner hole 1 between them.
The flange of the valve guide 21 fitted to the valve member 7d is clamped, and in this state, the members 17b, 17c and the valve guide 21 are integrated. 22 is located above the valve guide 21 and has an inner hole 17d of the member 17b.
The piston is slidably fitted into the piston, and the threaded portion of the valve rod 23, which is fitted into the inner hole 21a of the valve guide 21 so as to be freely retractable, is screwed into the central threaded hole of the piston. At the lower end of this valve stem 23,
A valve body 24 is integrally formed. On the other hand, a valve seat 17e is formed at the lower open end of the spool 17, and the valve body 24 and the valve seat 17e are arranged so that the molten metal 7 rising through the gas vent groove 10 from the open state shown in FIG. 24 is raised to the closed state. In the illustrated valve open state, the valve body 24 engages with and closes the opening step of the gas vent groove 10. Reference numeral 17f in FIG. 2 is a discharge hole for discharging to the outside the gas that is guided to the valve chamber 17g of the spool 17 through the bypass 12 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 equipped with a switching valve 27 having a solenoid SOL-A and a pressure reducing valve 28.

On the other hand, a flange 2 is provided on the valve body side of the piston 22.
2a is formed, 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 piston 22 are formed on the side opposite to the valve body and the side 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 onto the outer circumference of the upper surface of the rod side auxiliary chamber 32, with the O-ring 33 being prevented from falling off by a dovetail groove. . That is, when the valve is open, the lower surface of the flange 22a is
The rod side main chamber 31 and the rod side subchamber 32 are separated from each other by being pressed against an O-ring 33 fitted in a rod side subchamber 32 provided in the upper part of the rod 1a. The port 34 provided in the main chamber 31 on the rod side is connected to the 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. The port 38 provided in the collateral chamber 32 is connected to a solenoid.
Piping 40 equipped with switching valve 39 having SOL-C
and a compressed air source via the pressure reducing valve 36.

With this configuration, solenoid SOL-A is in an excited state, and SOL-B and
When SOL-C is in the demagnetized state, compressed air flows into the head side chamber 25 from ports 26b and 26c and pushes down the piston 22, opening the valve seat 17e and causing the piston 22 to move as shown in FIGS. 2 and 5. Its lower surface is pressed against the O-ring 33. In this state, energize solenoid SOL-B and then
Demagnetize SOL-A. In this state, compressed air flows into the rod side main chamber 31 and the piston 2
Although some compressed air may leak into the head side chamber 25 through the gap between the selector valve 2 and the inner hole 17d of the member 17b, this leaks through the switching valve 2 without almost any piping resistance.
7 into the atmosphere, the head side chamber 25 is at approximately atmospheric pressure. On the other hand, Rod's collateral chamber 3
Compressed air does not flow into the valve rod 23 from the rod side main chamber 31, and the compressed air in the rod side sub chamber 32 that was present before the valve closing operation flows through the valve stem 23 and the valve guide 2.
The inside of the rod side auxiliary chamber 32 is also at atmospheric pressure because it leaks through the gap with the inner hole 21a of the rod.

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, so the diameter of the valve stem ₂₃ is now d. ₁ , the diameter of the upper part of the piston 22 is d ₂ , the diameter of the seal between the bottom surface of the piston 22 and the O-ring 33 is d ₃ , and the pressure of the compressed air acting on the main chamber 31 on the rod side is P. The force F ₁ in the valve opening direction is expressed by the following equation.

F ₁ = 1/4π (d ₃ ² − d ₂ ² )×P When compressed air is applied to the piston-side main chamber 31 in this way, the lower surface of the piston 22 is exposed to the O-ring 3.
3, and the valve is kept open by the force _F1 that holds the valve 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 enter the rod side auxiliary chamber through this gap, causing F ₁ = 1/4π(d ₃ ² − d ₁ ² )×P force is newly applied to the lower surface of the piston 22, so F ₂ −F ₁ = 1/4π(d ₃ ² − _{d 1} ² )×P>0 As a result, the piston 22 rises rapidly. Therefore, the valve seat 17e closes quickly and the valve is 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 force pushes the valve upward, and the valve closes and remains closed.

In such a gas venting device for a mold, a gas venting groove 1 following the gas venting path 9 of the fixed mold 1 is provided.
A pair of electrodes 41A and 41B serving as melt detection means facing the entrance of 0 are spaced apart from each other by a small distance,
For example, it is disposed and covered with a heat-resistant insulating material 42 such as ceramic. And electrodes 41A, 4
1B is electrically connected to the solenoid SOL-C, and when the molten metal 7 passes through the gas vent groove 10 after filling the cavity 4, the electrodes 41A and 41B detect this and energize the solenoid SOL-C. 24 is configured to close. In addition, each of the above solenoids SOL-A, SOL-B, SOL-
In addition to demagnetizing solenoid SOL-C by electrodes 41A and 41B, the energization and de-energization of C is generally performed by stroke detection using a limit switch or a magnetic scale provided during the stroke of the piston rod of the injection cylinder.

The operation of the mold degassing device configured as above will be explained. After the molds 1 and 2 have been clamped, the fluid pressure cylinder 14 is activated from the state shown in FIG. Hole 1
Fits into 1. Then, as mentioned above, solenoid SOL-A is energized, solenoid SOL-B,
After SOL-C is demagnetized and the piston 22 descends, SOL-B is further energized, SOL-A is demagnetized, and the lower surface of the piston 22 is pressed against the O-ring 33. As a result, the valve body 24 and the valve seat 17e maintain the open state as shown in FIGS. 2 and 3. 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 inlet 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, hits the lower end of the valve body 24, passes through the bypass 12 and the valve chamber 17g, and then reaches the exhaust hole 1.
It is discharged from 7f. At this time, the flange 2 of the piston 22 is
A valve opening holding force represented by F ₁ is determined based on the size of 2a, the set pressure of the pressure reducing valve 36, etc.
After the molten metal 7 is completely filled into the cavity 4, 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, and a large inertial force acts on the lower surface of the valve body 24, so that the valve body 24 is flipped upward. At the same time, the electrode 41
Since A and 41B are short-circuited by the molten metal 7, the solenoid SOL-C electrically connected thereto is energized, and compressed air enters from the port 38 and acts on the lower surface of the flange 22a, so that the valve body 24 is securely is jumped up. In this case, the valve body 24 moves upward even slightly and the flange 22a of the piston 22
When the lower surface separates from the O-ring 33, the compressed air in the rod-side main chamber 31 enters the rod-side sub-chamber 32 through the gap between the lower surface of the flange 22a and the O-ring 33, and is expressed as F ₂ - F ₁ described above. The force applied to flange 2
2a, causing the piston 22 to rise 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 cooled under pressure for a predetermined time with the valve body 22 closing the gas vent groove 10 and the bypass 12, as shown in FIG. When the entire valve 16 is raised, the valve body 24 separates from the solidified material 7A in the cavity 4, the gas vent groove 10, and the bypass 12, but at this time, the valve body 24 is prevented from moving upward, and the spool 17 is The valve body 24 opens later than the rise, and is maintained in the open state by the action of the air pressure. After cooling, the product in the cavity 4 is opened and extruded by a product extrusion device 8. Figure 4 shows the solenoid SOL after this.
-A is demagnetized, solenoids SOL-B and SOL-C are energized, and the valve body 24 is closed.

In such a degassing operation, even if the valve body 24 is not closed by the signal due to an error in detecting the molten metal 7 by the electrodes 41A, 41B or a disconnection of the electrical wiring, as described above, the molten metal 7 will not be closed. Since the valve body 24 closes due to inertial force, there is no problem.

6, 7, and 8 are sectional views of the vicinity of a gas vent groove provided with a molten metal detection device showing other embodiments of the present invention. First, in the one shown in FIG. 6, a space 43 and a space 44 are opposite to the fixed mold 1 and the movable mold 2, respectively, on both sides of the entrance of the gas vent groove 10 following the gas vent path 9. An ultrasonic transmitter 45 and an ultrasonic receiver 46 are provided in the spaces 43 and 44, respectively. By doing this, when the molten metal 7 enters the gas vent groove 10, the ultrasonic waves emitted from the ultrasonic wave transmitter 45 are attenuated, and the ultrasonic wave receiver 46 receives the molten metal. is detected and the valve body 24 closes.

Next, in what is shown in FIG. 7, a primary coil 47 and a secondary coil 48 are provided on both sides of the entrance of the gas vent groove 10 in the fixed mold 1 and the movable mold 2, respectively. Furthermore, each coil 4
Heat-resistant materials 49 and 5 made of a non-magnetic material such as ceramic are placed on the side surfaces of gas vent grooves 10 of 7 and 48.
0 are placed respectively, and the magnetic flux is applied to molds 1 and 2.
It is designed to avoid being led to the side. By doing this, when the molten metal 7 enters the gas vent groove 10, the molten metal 7 blocks the magnetic flux and the voltage induced in the secondary coil 48 changes, detecting the passage of the molten metal 7 and closing the valve body 24. let

Furthermore, in the one shown in FIG. 8, a sensor coil 51 is arranged on the fixed mold 1 side facing the entrance of the gas vent groove 10, and the sensor coil 51 is arranged with the gas vent groove 10 side protected by a heat-resistant material 52 made of a non-magnetic material. Along with being there,
A high frequency current is supplied to the sensor coil 51. By doing this, when the molten metal 7 enters the gas vent groove 10 and the magnetic flux interlinks, an eddy current is generated on the surface of the molten metal that cancels the magnetic flux, and the impedance of the sensor coil changes to prevent the molten metal 7 from passing. The detection causes the valve body 24 to close.

In addition, in each of the above embodiments, the spool 17
The gas exhaust hole 17f provided in the cavity 4 is exposed to the atmosphere.
It is also possible to keep the interior in a vacuum state and close the valve body 24.

Furthermore, although this embodiment shows an example in which the electromagnetic coupling device according to the present invention is applied to an electromagnetic clutch, it can also be similarly applied to an electromagnetic brake, and the same effects can be obtained.

〔Effect of the invention〕

As is clear from the above description, according to the present invention, the valve stem is supported by the inner hole of the spool, which is provided with a gas discharge hole and whose open end is attached to the spool hole of the mold, and the valve stem moves back and forth. For molds in which a valve element for opening and closing a valve seat at the opening end of the spool is provided at the tip of the valve stem, and gas in the mold cavity is discharged from the discharge hole via the opened valve seat and the inner hole of the spool. The degassing device includes a detection means arranged in a melt passage between a mold cavity and a valve body to detect passage of the melt, and a valve connected to the detection means and actuated by the melt detection signal. A driving device is provided, and the piston is slidably fitted into the inner hole of the spool to the end of the valve stem opposite to the valve body to fix a piston having a flange at the end of the valve body. The valve body side chamber is connected to a pressure fluid source, and the flange portion can open and close between the opposite valve body side chamber of the flange portion and the valve body side chamber of the piston by forward and backward movement of a valve rod driven by the valve driving device. With this configuration, the valve is kept open during degassing, and when the melt that fills the mold cavity and moves toward the valve opening passes through the melt passage, the detection means detects this. A signal is generated, and the valve driving device operated by this signal moves the valve body in the valve closing direction.If the valve body moves even slightly, a large force is generated in the valve closing direction due to the movement of compressed air, causing a rapid and Since the valve body can be closed reliably, there is no risk of the locking part wearing out unlike with conventional locking devices using balls, etc., and the valve holding force in both open and closed positions can be reliably maintained for a long period of time. This greatly improves durability and reliability. In addition, when injecting and filling molten metal, the intrusion of molten metal into the valve chamber is reliably prevented, and the molten metal does not spray out into the mold or damage the vacuum device in devices equipped with a vacuum device, resulting in safety. and durability is improved. moreover,
Since the molten metal is detected by a detection device and the valve body is moved by a fluid pressure device, the number of parts is reduced compared to a mechanical method, making maintenance easier and making it easier to operate the valve at the open position. The holding force can be adjusted only by adjusting the fluid pressure, making adjustment easy.

[Brief explanation of the drawing]

1 to 8 show an embodiment of the gas venting device for a mold according to the present invention, FIG. 1 is a partially cutaway front view of the gas venting device and a mold in which the device is installed,
The figure is a longitudinal sectional view of the degassing device, Figure 3 is a longitudinal sectional view of the main parts and an air circuit diagram, and Figure 4 shows the degassing device separated from the mold, corresponding to Figure 1. FIG. 5 is a longitudinal sectional view of the main part of a gas venting device for molds, and FIGS. 6, 7, and 8 are gas diagrams equipped with a molten metal detection device showing other embodiments of the present invention. FIG. 3 is a cross-sectional view of the vicinity of the punching groove. 1... Fixed mold, 2... Movable mold, 4... Cavity, 7... Molten metal, 9... Gas vent path, 10...
... Gas vent groove, 11... Spool hole, 16... Gas venting device for mold, 17... Spool, 17d...
...Inner hole, 17e... Valve seat, 17f... Discharge hole, 2
2... Piston, 22a... Flange, 23...
Valve stem, 24... Valve body, 30... Compressed air source, 31
... Main room on the rod side, 32 ... Secondary room on the rod side, 41
A, 41B...electrode, 51...sensor coil,
SOL-A, SOL-B, SOL-C... Solenoid.

Claims (1)

[Claims] 1. A valve body that opens and closes a valve seat at the open end of the spool by supporting a valve stem in the inner hole of a spool having a gas discharge hole and having an open end attached to a spool hole of a mold, and moving the valve stem back and forth. In the mold gas venting device that is provided at the tip of the valve stem and discharges gas in the mold cavity from the discharge hole via the open valve seat and the inner hole of the spool, the mold cavity and the valve body a detection means disposed in a melt passage between the valve stem and the valve rod for detecting the passage of the melt, and a valve driving device connected to the detection means and actuated by the melt detection signal. A piston is slidably fitted into the inner hole of the spool at the end on the valve body side to fix a piston having a flange portion at the end on the valve body side, and a chamber on the side of the flange portion opposite to the valve body is connected to a pressure fluid source. , characterized in that the flange portion is configured to open and close between the opposite-valve body side chamber of the flange portion and the valve body side chamber of the piston by forward and backward movement of the valve stem driven by the valve driving device. Gas venting device for molds.