JPH0790345B2 - Mold degassing device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a mold degassing device for extracting gas from a mold cavity during injection molding by an injection molding device such as a die casting machine or an injection molding machine. is there.

[Conventional technology]

As a conventional technique similar to the present invention, there is a technique described in JP-A-63-60059. In this technology, the molten metal from the cavity reaches the molten metal detection sensor composed of two electrodes insulated from each other, and the molten metal detection sensor is short-circuited, which causes the switching circuit to immediately act and the air solenoid valve or the electromagnetic coil to operate. By doing so, the gas vent valve is closed.

[Problems to be Solved by the Invention]

In the above-mentioned prior art, when the molten metal from the cavity moves in the degassing passage as a lump, the molten metal can be easily detected, and the molten metal enters the degassing valve by closing the degassing valve. There is no such thing. However, during actual casting, it is rare that the molten metal from the cavity moves in the form of lumps in the gas vent passage, and in general, it is often flake-like or granular. Since the molten metal detection sensor consists of two electrodes insulated from each other, these flakes and particles cannot be detected, and therefore the degassing valve cannot be closed,
The flakes or particles of the molten metal may enter the gas vent valve, and these may be caught in the seat surface of the valve, so that a large amount of the molten metal may enter the gas vent valve.

[Means for Solving the Problems]

In order to solve such a problem, the first aspect of the present invention is to provide an elastic wave which is disposed in the middle of a gas vent passage and which is generated when the molten metal collides with the wall surface of the gas vent passage. A detection device for detecting and a valve closing mechanism that compares the detection signal level with a reference level and closes the valve with an electrical signal when the detection signal level is higher than the reference level are provided, and the gas vent passage and the mold cavity are connected. The position is provided at the position where the molten metal reaches the end in the mold cavity.

A second invention of the present invention is a detection device which is disposed in the middle of a gas vent passage and detects an elastic wave generated when the molten metal collides with a wall surface of the gas vent passage when the molten metal passes through the detector. The signal level is compared with a reference level, and a valve closing mechanism that closes the valve with an electric signal when the detected signal level is higher than the reference level is provided, and the damping device surrounds the periphery of the detection device.

[Action]

After passing through the mold cavity, the detection device detects the elastic wave generated when the molten metal moving in the gas vent passage toward the gas vent valve collides with the mold wall, and the detection signal level is higher than the reference level. In this case, an electric signal indicating that the molten metal has reached the sound wave detecting device is generated, and the gas vent valve is closed by this electric signal.

〔Example〕

FIG. 1 shows a valve control device in an embodiment of a mold degassing device according to the present invention, wherein 1 is an elastic wave detecting device for outputting a detection signal level S1 signal, 2 is a preamplifier, and 3 is a bandpass filter. Reference numeral 4 is a seed amplifier, 5 is a reference elastic wave setting device that outputs a signal of reference level S2, 6 is a comparator that outputs a valve closing signal when S1 ≧ S2, and 7 is a valve closing mechanism.

2 and 3 are cross-sectional views showing a degassing device and a mold in an embodiment of the degassing device for a mold according to the present invention. In FIG. 2 and FIG. 3, a degassing block 11 is attached to the fixed die or the movable die, or the separation surface of one of the die, and the fluid is placed on the bracket 11a fixed to the upper surface. The pressure cylinder 12 is fixed, and the flange 12b, which is the working end of the piston rod 12a that moves forward and backward by its fluid pressure, has the main body of the mold degassing device indicated by reference numeral 13 and the holder 14 at the upper end. It is fixed by bolting. The main body 13 of the mold degassing device is provided with a bottomed cylindrical spool 15 whose upper end is sandwiched by a holder 14. The lower end small diameter step 15a of this spool 15 is a spool of the degassing block 11. It is removably fitted in the hole 16. Then, at the time of injection molding, the mold cavity 22 is formed by using the main body 13 of the mold degassing device.
When the gas inside is discharged or the valve is closed, the piston rod 12a is advanced so that the small diameter stepped portion 15a and the spool hole 16 are fitted as shown in FIG. 2. After injection, the mold is opened and the valve is opened. When cleaning the head, etc., use the piston rod 12a
Moves backward and the small diameter stepped portion 15a and the spool hole 16 are released,
The small-diameter step portion 15a and the valve head portion are provided so as to be located outside the gas vent block 11. The spool 15 is the upper and lower members 15
It is divided into b and 15c, and the flange of the valve guide 17 fitted in the inner hole 15d is sandwiched between them, and the upper and lower members
15b and 15c are integrated. Reference numeral 18 denotes a piston located above the valve guide 17 and slidably fitted in the inner hole 15d of the member 15b of the spool 15, and has a central screw hole for advancing and retracting to the inner hole 17a of the valve guide 17. The threaded portion of the valve rod 19 that is freely fitted and penetrates the lower end small diameter step portion 15a of the spool 15 is screwed into and integrated with the lower end of the valve rod 19, which will be described in detail later. 20 are integrated.

On the other hand, the degassing block 11 and the mold 21 to which it is joined and fixed are divided into a front side and a paper back side with the plane of the drawing as a boundary, and a cavity 22 is formed in the mold 21. . The gas vent block 11 and the mold 21 are formed with a gas vent groove 23 continuous to the cavity 22, and between the gas vent groove 23 and the spool hole 16 in which the spool 15 is fitted, A stepped cylindrical valve chamber 24 is provided with a large diameter hole 24a and a small diameter hole 24b. The valve head 20
Is a cylindrical large-diameter portion 20a slidably fitted in the hole 24b of the small-diameter portion of the valve chamber 24, and a tapered small-diameter portion 20b protruding from the large-diameter portion 20a toward the gas vent groove 23. Is integrally formed in a stepped manner, and a conical hole 20c having a diameter larger than the width of the gas vent groove 23 is provided on the end face side of the central portion. On the outer periphery of the upper end of the base end flange portion 20d of the valve head 20, the spool 1
A tapered portion 20e that forms a valve opening / closing portion is formed by the valve seat 15e formed on the inner surface of the lower end of the valve 5. And cavity 2
By tapping the valve head 20 with the molten metal from 2, the taper part 2
The valve 0e is pressed by the valve seat 15e to close the valve. The valve opens when air or oil is sent to the chamber above the piston 18 in response to a command from the controller, but illustration and detailed description thereof are omitted. Further, the piston 18 can be configured to forcibly close the valve by supplying air or oil to the lower chamber. Further, if air or oil is made to act in the room where the flange at the bottom of the piston 18 is located, if the piston 18 floats up even a little due to the closing operation, the air or oil in the room also acts on the lower side of the piston 18. Therefore, the addition of this force causes the piston 18 to rise more quickly, and thus the valve closing operation to be performed faster.

A gas vent passage 25, which can be called a bypass following the gas vent groove 23, is formed along the end surface and the peripheral surface of the tapered small diameter portion 20b of the valve head 20 and communicates with the gas vent groove 23. The valve seat 15 emanates from the passage 25a and the side surface of the small diameter portion 20b.
It is formed by a pair of bypass passages 25b communicating with the valve chamber 24 immediately before e. In the embodiment shown in FIG. 2, the bypass passage 25b moves slightly laterally and then downwards, then laterally outwards, then upwards, and finally inwardly laterally toward the valve seat 15e. Has reached just before. However, this may have another shape as long as it has a necessary and sufficient length. An exhaust hole 15f is opened in the inner hole 15d of the spool 15, so that the gas in the cavity 22 has a large venting groove 23, a passage 25a, a bypass passage 25b, and an upper side of the valve chamber 24 when the valve is open. It is configured such that it enters the inner hole 15d of the spool 15 through the hole 24a of the diameter portion and is discharged to the outside from the exhaust hole 15f.

In FIG. 2, the thickness of the large diameter portion 20a of the valve head 20 slidably provided on the inner surface of the hole 24b of the small diameter portion of the valve chamber 24 is the valve opening dimension, that is, the valve seat 15e in the valve open state. The thickness is made thicker than the axial distance between the tapered portion 20e and the tapered portion 20e so that the molten metal does not pass directly through the outer periphery of the large diameter portion 20a to the hole 24a of the large diameter portion of the valve chamber 24 when the valve is closed.

Further, the axial length of the tapered small diameter portion 20b of the valve head 20 is longer than the width of the bypass passage 25b in the portion extending laterally from the root of the small diameter portion 20b when the valve is open. .
If possible, the length of the small diameter portion 20b in the axial direction should be the bypass passage 2
It is preferable to make the width more than twice the width of 5b or longer than the width of the bypass passage 25b plus the valve opening size. This is to prevent the molten metal that has entered the lateral direction of the end surface of the valve head 20 from the gas vent groove 23 from easily advancing into the bypass passage 25b.

The passage 25a formed along the end surface and the peripheral surface of the tapered small-diameter portion 20b of the valve head 20 when the valve is open is a passage 25a that is appropriately narrowed so that the gas exhaust capacity is sufficient. Moreover, the size of the molten metal was set so that it could be kept in a difficult state to advance. That is, in the passage 25a, the portion along the end face of the valve head 20 has a taper surface on the lower side so that the flow of the molten metal can be narrowed near the outer periphery of the end face of the valve head 20. However, this throttling portion works effectively at the moment when the molten metal collides with the valve head 20 when the valve is open, but once the valve begins to close, the space here rapidly expands and the throttling effect fades away immediately. I will end up. On the other hand, if the passage 25a provided on the outer periphery of the tapered small-diameter portion 20b of the valve head 20 is narrowed within a range in which gas can be sufficiently discharged, the throttling effect can be obtained even when the valve starts to close. There is almost no change, and the valve head 20 maintains the squeezed state even when it moves in the axial direction. Since these throttle portions are provided along the end surface and the peripheral surface of the small diameter portion 20b of the valve head 20, the molten metal does not easily go through even if the gas easily passes therethrough. The small-diameter portion 20b may not necessarily be tapered but may be formed in a columnar shape.However, if the small-diameter portion 20b is gently tapered, not only has a throttling effect, but also when the valve head 20 is extracted from the solidified metal portion after injection. There is also an effect that works smoothly.

On the other hand, from the end face of the valve head 20 toward the inside, a conical hole 20c is provided, and at that time, the diameter of the inlet of the conical hole 20c was made larger than the width of the degassing groove 23. Gas vent groove
This is to ensure that the first portion of the molten metal that rushes straight from 23 enters into this conical hole 20c and that the valve is closed quickly before the molten metal attempts to reach the passage 25a. Furthermore, the reason why the hole 20c is provided in the valve head 20 is that the valve head 20 itself is lightened so that the valve head 20 can be pushed down with a lighter force. The conical hole 20c is used because it has a draft and it is not necessary to reduce the strength of the valve head 20 itself more than necessary.

As shown in FIG. 3, the mold 21 includes an elastic wave detecting device 1, an elastic wave sensor 1a, a cavity 22, a degassing passage 23, and a damping material.
28 and. The molten metal 10 is shown in the cavity 22. Further, 29 is a plunger. The damping material 28 is a sensor for the elastic wave propagating through the mold 21 as shown by the arrow BR.
In order to prevent detection by 1a, it is formed so as to surround the periphery of the sensor 1a, and its material is, for example, Fe-
3% C-2% Si, Fe-12% Cr-3% Al, etc. Further, in FIG. 2, reference numeral 26 is an electromagnetic coil and 27 is a core, which control the vertical movement of the valve head 20.

In FIG. 3, the connection position P between the gas vent groove 23 and the cavity 22 is set as shown in FIG.
This is because 10 is considered to move as shown by the arrow AR, and the position where the molten metal 10 reaches the latest at this time is considered to be P.

The operation of the die degassing device configured as described above will be described. There are two operations of this mold degassing device: inertial operation and electrical operation. Inertial motion is the valve head 20
The molten metal 10 is used to push up the molten metal, and the electrical operation is to control the opening and closing of the valve by energizing and de-energizing the electromagnetic coil 26.

First, the inertial motion will be described. When the main body 13 of the die degassing device is set in the state shown in FIG. 2 and the molten metal 10 is injected into the cavity 22 of the die 21 with the valve open, the gas in the cavity 22 becomes Passage through the gas vent groove 23
25a, split into both bypass passages 25b, then bypasses and enters the spool 15 from the valve opening immediately before the valve seat 15e, and the exhaust hole 1
It is discharged from 5f to the outside. In this case, the cross-sectional area of the passage 25a is set to an extent necessary for discharging the gas, and the relatively wide bypass passage 25b is in communication therewith, so that the passage of gas is easy. Exhaust capacity is large. The gas may be released into the atmosphere through the exhaust hole 15f,
In many cases, an electromagnetic switching valve (not shown) and a vacuum device are connected to the exhaust hole 15f to suction the gas under vacuum.

When the molten metal 10 fills the cavity 22, the molten metal 10 vigorously rises into the degassing groove 23 and reliably acts on the end surface of the small diameter portion 20b of the valve head 20 before entering the passage 25a. 2
0 rises, the taper portion 20e comes into close contact with the valve seat 15e, and the valve is completely closed. After this, the molten metal 10 proceeds to the bypass passage 25b via the passage 25a, so that the molten metal entering the bypass passage 25 or the solidified material in the form of droplets or small particles may get stuck in the valve opening / closing portion or enter the spool 15. Absent.

In this case, in the valve open state, the passage 25a along the horizontal end surface of the small diameter portion 20b of the valve head 20 is in a state where the outer peripheral side of the valve head 20 is narrowed to some extent, and the small diameter of the valve head 20 is small. Part 20b
Since the outer peripheral surface of is also tapered and the passage 25a along the outer periphery of the small diameter portion 20b is also throttled to some extent, the gas can be sufficiently discharged, but the molten metal can be discharged by the action of these throttles. It is difficult to smoothly flow through the bypass passage 25b. It should be noted that in the valve open state, both the end surface portion and the outer peripheral portion of the small diameter portion 20b are squeezed, but when the valve starts to close, only the outer peripheral portion of the small diameter portion 20b is opened and closed with the small diameter portion 20b.
Even if the action of the throttle portion on the end face side of the is suddenly weakened, there is no problem because the valve is closed at that time.

While making it difficult for the molten metal to reach the passage 25a and the bypass passage 25b in this way, a conical hole 20c is provided from the end face of the valve head 20 to the back to make the valve head 20 itself lighter and push up easily. At the same time, since the diameter of the inlet of the conical hole 20c is made slightly larger than the width of the gas vent groove 23, the gas vent groove 23
Most of the molten metal that has moved straight forward from the first enters the conical hole 20c at the beginning, and easily pushes up the valve head 20.

In this way, by the synergistic effect of the effect of reliably acting the molten metal on the valve head 20 and the throttling effect of the passage 25a that prevents the molten metal from advancing toward the passage 25a and the bypass passage 25b side as much as possible, The valve can be closed surely and quickly every time without clogging the droplets on the valve seat 15 and beyond. With such a structure, not only when a large amount of molten metal solidifies from the gas vent groove 23 and goes straight, but also when a small amount of molten metal comes or a little weak momentum has advanced. The valve can be closed quickly and reliably even when the inertia of the melt is rather weak, as is the case.

When the molten metal is pressurized and cooled, the entire body 13 of the degassing device is raised by the cylinder 12, and the valve head 20 is formed from the solidified metal that is filled and solidified in the degassing passage 25 for performing the degassing groove 23.
After releasing, the mold is opened and the product is taken out.

Next, the electrical operation will be described with reference to FIG. 1, FIG. 2 and FIG. This is to detect the arrival of the molten metal 10 by the elastic wave detecting device 1 by detecting the amplitude of the elastic wave generated when the molten metal 10 collides with the wall of the gas vent groove 23. The data detected by the elastic wave detecting device 1 for detecting the arrival of the molten metal 10, that is, the amplitude S1 of the amplitude of the elastic wave generated when the molten metal 10 collides is set in advance by the reference elastic wave setting device 5. A certain reference value, that is, the minimum amplitude S2 of the elastic wave that can detect the arrival of the molten metal 10 that has been obtained through experience or testing in advance, is compared by the comparator 6, and the data is the reference value. In the above case (in the case of S1 ≧ S2), it is determined that the molten metal 10 has arrived, and outputs a valve closing command signal to the solenoid 26 constituting the valve closing mechanism 7. This allows
The valve head 20 is pulled up and the valve closes. In this way, the valve can be closed by detecting the elastic wave generated in the gas vent groove 23.

Either inertial operation or electrical operation may be selected, but if the molten metal injection speed slows down for some reason,
The valve head 20 is not moved by the molten metal, and the molten metal may enter through the degassing passage 25. In order to avoid this, the injection speed is detected, and when the injection speed is less than or equal to a predetermined value, an electrical operation is performed. When the injection speed is equal to or higher than a predetermined value, only the inertial operation may be performed, or the inertial operation and the electrical operation may be performed in parallel.

FIG. 4 is a block system diagram showing another embodiment of the present invention. The operation of this embodiment will be described. After the output signal (level Sa signal) of the elastic wave detection device 1 that has received the elastic wave is amplified by the preamplifier 2, passes through the bandpass filter 3, and is amplified again by the main amplifier 4 to be a level Sb signal. , A pulse signal generator set in advance by the reference elastic wave setting device 5
Compared with the level Sc of the reference signal input to 31, Sb ≥ Sc
In this case, the pulse signal generator 31 generates a pulse signal.
This pulse signal is counted by the pulse counter 32, and if the counted pulse number Sd is larger than the set pulse number Se from the reference pulse number setting device 33, a valve closing signal is sent to the solenoid 26 of the valve closing mechanism 34.
Output to. This raises the valve head 20 upwards and closes the valve. In this way, the valve can be closed by detecting the elastic wave generated in the gas vent groove 23.

FIG. 5 is a block system diagram showing still another embodiment of the present invention. The operation of this embodiment will be described. The elastic wave at the time of collision is received by the elastic wave detection device 1, the output signal (signal of level Sa) of the detection device 1 is amplified by the preamplifier 2, passed through the bandpass filter 3, and amplified again by the main amplifier 4. Level
After the signal of Sb is set, it is compared with the level Sc of the reference signal which is preset by the reference elastic wave setting device 5 and input to the pulse signal generator 31, and when Sb ≧ Sc, the pulse signal generator 31
Generates a pulse signal Sd. The pulse signal Sd becomes "H" level for a predetermined time (first predetermined time) each time the detection signal level Sb exceeds the reference level Sc, and continues when the detection signal level exceeds the reference level within the predetermined time. Is a signal that becomes "H" level. That is, the pulse signal generator 31 is a circuit that is retriggered by a signal of Sb ≧ Sc. In addition, the magnitude of the level Sc of the reference signal output from the reference elastic wave setting device 5 is the minimum magnitude of the elastic wave that can be detected when the molten metal 9 reaches, which is obtained in advance through experience or testing. It is the level shown.

The time comparison circuit 32a inputs the pulse signal of the signal Sda and the reference time signal Sea from the reference time setting device 33a, and outputs the signal Sda.
When the total generation time of the molten metal detection pulse and the time indicated by the reference time signal Sea are compared and the total generation time of the molten metal detection pulse signal of the signal Sda exceeds the reference time (second predetermined time) longer than the first predetermined time A closing signal Sf is output to the solenoid 26 to close the valve closing mechanism 34.

〔The invention's effect〕

As described above, the first aspect of the present invention is that the degassing valve provided at the terminal end of the degassing passage from the mold cavity and the passage of the molten metal disposed in the middle of the degassing passage. A detection device that detects elastic waves generated when the molten metal collides with the wall surface of the gas vent passage, and compares the detection signal level with a reference level.If the detection signal level is higher than the reference level, the valve is activated by an electrical signal. With a closing valve closing mechanism,
By providing the connection point between the gas vent passage and the mold cavity at the position where the molten metal reaches the last in the mold cavity, the degassing can be performed most effectively, and the molten metal is introduced into the gas vent valve. There is an effect that the product cavity can be constantly degassed without entering a large amount.

A second aspect of the present invention is a gas vent valve provided at the end of the gas vent passage from the mold cavity, and a melt vent that is disposed in the middle of the gas vent passage to prevent passage of the melt. A detection device that detects the elastic wave generated when it collides with the wall surface of the gas vent passage, and compares the detection signal level with a reference level, and if the detection signal level is higher than the reference level, closes the valve with an electrical signal. Since the detector is equipped with a mechanism and surrounded by a damping material, it is possible to always stably degas the product cavity without a large amount of molten metal entering the degassing valve. This has the effect of preventing malfunction.

[Brief description of drawings]

FIG. 1 is a system diagram showing a valve control device in an embodiment of a die degassing device according to the present invention, and FIGS. 2 and 3 are degassing in an embodiment of a die degassing device according to the present invention. FIG. 4 is a sectional view showing an apparatus and a mold, FIG. 4 is a system diagram showing another embodiment of the present invention, and FIG. 5 is a system diagram showing yet another embodiment of the present invention. 1 ... Elastic wave detection device, 2 ... Preamplifier, 3 ... Band filter, 4 ... Main amplifier, 5 ... Reference elastic wave setting device, 6 ... Comparator, 7 ... Valve closing mechanism, 28 …… Damping material, P
...... Connection position.

Claims (2)

[Claims] 1. A degassing valve provided at a terminal end of a degassing passage from a mold cavity, and a degassing passage disposed in the middle of the degassing passage to allow the molten metal to pass through the degassing passage. A detection device for detecting an elastic wave generated when colliding with a wall surface, and a valve closing mechanism for comparing the detection signal level with a reference level and closing the valve with an electric signal when the detection signal level is higher than the reference level. A mold degassing device, characterized in that a connection point between the gas vent passage and the mold cavity is provided at a position where the molten metal generally reaches the end in the mold cavity. 2. A degassing valve provided at a terminal end of a degassing passage from a mold cavity, and a degassing passage disposed in the middle of the degassing passage so that the molten metal passes through the degassing passage. A detection device for detecting an elastic wave generated when colliding with a wall surface, and a valve closing mechanism for comparing the detection signal level with a reference level and closing the valve with an electric signal when the detection signal level is higher than the reference level. A mold degassing device, characterized in that the detection device is surrounded by a damping material.