JPH03230856A - Gas venting device for die - Google Patents

Abstract

PURPOSE:To stably enable gas ventilation in product cavity by counting a pulsed electric signal, transmitting the electric signal when the counted value reaches the preset value and shutting a valve with this electric signal. CONSTITUTION:Elastic wave at the time, when molten metal collides with wall face at bending part in a passage for gas venting, is detected with an elastic wave detecting means 19 to recognize passage of the molten metal. By comparing the detected signal level and the reference level, at every time, when the detected signal level exceeds the reference level, the pulsed electric signal having the prescribed length is generated with pulse signal generating means. The pulsed electric signal is counted, and when the counted value reaches the preset value, the electric signal is generated with the pulse counter. A valve 4 is shut with a valve shutting mechanism from this electric signal. By this method, invasion of the molten metal into the gas venting valve can be prevented.

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. It is.

[Conventional technology]

As a prior art similar to the present invention, Japanese Patent Application Laid-Open No. 6360059
There is a technology described in the publication No.

In this technology, the molten metal from the cavity reaches the molten metal detection sensor, which is made up of two electrodes that are insulated from each other, and the molten metal detection sensor is short-circuited, which immediately activates the switching circuit and activates the air solenoid valve or electromagnetic coil. This closes the gas vent valve.

In such conventional technology, when the molten metal from the cavity becomes a lump and moves inside the gas vent passage, the molten metal can be easily detected, and by closing the gas vent valve, the molten metal flows into the gas vent valve. There will be no intrusion. However, during actual casting, it is rare for the molten metal from the cavity to form a lump and move through the gas vent passage.
Generally, it is often flaky or granular. Since the molten metal detection sensor consists of two electrodes that are insulated from each other, it cannot detect these flakes or grains, and therefore the gas vent valve cannot be closed, and the molten metal flakes inside the gas vent valve cannot be detected. As a result, a large amount of molten metal sometimes entered the gas vent valve due to the intrusion of molten metal and particles into the valve seat surface.

In response to this, the invention described in Japanese Patent Application No. 63-299447 was proposed. This invention includes a degassing valve at the end of the degassing passage from the mold cavity, and the passage of the molten metal is recognized by detecting elastic waves generated when the molten metal collides with the wall surface of the passage. A detection means is arranged in the middle of the molten metal passage, the detection signal level is compared with a reference level, and when the detection signal level is higher than the reference level, the valve is closed by an electric signal.

[Problem to be solved by the invention]

In the conventional technology, when the molten metal from the cavity becomes a lump and moves in the gas vent passage, the detection signal level when the molten metal collides with the wall of the passage is sufficiently high, and the reference level is set high. By doing so, the molten metal can be easily detected, and by closing the gas vent valve, the molten metal will not enter the gas vent valve. However, during actual casting, it is rare for the molten metal from the cavity to move in the gas vent passage in the form of a lump, and is generally in the form of flakes or grains. Because the elastic waves generated when these collide with the passage wall are small, they cannot be detected and the gas vent valve cannot be closed, causing them to enter the gas vent valve or hit the valve seat surface. Due to the jamming, a large amount of molten metal sometimes entered the gas vent valve. In addition, if the reference level of elastic waves is made smaller in order to improve the detection accuracy of molten metal, the elastic waves generated inside the sleeve at the start of high-speed injection or during injection and propagated to the gas vent passage will be detected and the gas vent valve will be activated. Because the cavity is closed, the gas inside the cavity may not be sufficiently exhausted.

[Means to solve the problem]

In order to solve such problems, the first aspect of the present invention is to detect the elastic waves generated when the molten metal collides with the wall by disposing it on the wall of the bent part formed in the middle of the degassing passage. The elastic wave detection means recognizes the passage of molten metal by comparing the detection signal level output from the elastic wave detection means with a reference level, and generates a pulse of a predetermined length each time the detection signal level exceeds the reference level. a pulse signal generating means for generating a pulsed electrical signal;
This device includes a pulse counter that generates an electrical signal when a preset count value is reached, and a valve closing mechanism that closes the valve based on the electrical signal from the pulse counter.

Further, the second invention of the present invention provides the elastic wave detector, and the detection signal from the elastic wave detector is compared with a reference signal, and each time the level of the detection signal exceeds the level of the reference signal, a predetermined length of a comparison means for generating a pulsed electrical signal; a timing means for measuring the cumulative output time of the pulsed electrical signal and generating an electrical signal when the cumulative output time reaches a preset time; A valve closing mechanism is provided which closes the gas venting valve according to the output.

[Effect]

In the present invention, when a pulse counter is used, when the count value of the pulse counter reaches a preset value, the gas vent valve is closed by an electric signal generated from the pulse counter.

In addition, when a timer is used, when the cumulative output time of the pulsed electric signal output from the comparison means reaches a preset time, the gas vent valve is closed by the electric signal generated from the timer. .

〔Example〕

FIGS. 2 and 3 show a general mold degassing device and a mold.

Figure 2 shows a mold degassing device and a part of the mold in which it is installed.
It is a sectional view taken along the line mm in the figure.

In FIGS. 2 and 3, 2 is a movable mold, 3 is a fixed mold, 7 is a product cavity, 9 is a molten metal, 10 is an extrusion plate,
Reference numeral 11 denotes an extrusion pin, into which a gas vent valve 1 is fitted into a recessed portion in the upper part of the movable mold 2, and is capable of sliding back and forth together with the movable mold 2.

Further, the product cavity 7 communicates with the gas vent valve 1 via a gas vent groove 8. Molten metal 9 is in the gas vent groove 8.
A detection device 19 is provided that detects the arrival of the molten metal 9 by detecting the magnitude of the amplitude of an elastic wave generated when the molten metal 9 collides with the wall surface. The gas vent valve 1 has a valve body 4.
Valve stem 5. Gas exhaust hole6. Valve seat 12. Gas exhaust chamber 13. Core 20° joint 21. It is composed of a compression coil spring 22 and a solenoid 23, and the core 20 is connected to the rear part of the valve rod 5 via a joint 21, and the valve body 4 is connected to the front part of the valve rod 5.

A solenoid 23 is provided along the circumference of the core 20, and when energized, the core 20 moves to the left in FIG. 2, causing the valve body 4 to separate from the valve seat 12, as shown in FIG. Then, the gas vent valve 1 opens, and by stopping the energization to the solenoid 23, that is, cutting off the electric circuit, the valve body 4 comes into close contact with the valve seat 12 due to the expansion of the compression coil spring 22, and the gas vent valve 1 closes. is formed. The detection device 19 that detects that the molten metal 9 has arrived is a sensor block 24
The data formed by the elastic wave sensor 25 and detected by the detection device 19, that is, the magnitude of the amplitude of the elastic wave generated when the molten metal 9 collides, is a reference value set in advance by the reference elastic wave setting device 17, In other words, the pulse signal generator 26 compares the amplitude of the minimum elastic wave that can detect the arrival of the molten metal 9, which has been determined through experience or testing, and if the above data exceeds the reference value, the molten metal is detected. 9 is reached, and a pulse signal of a predetermined length is sent to a pulse counter, which will be described later. and,
When the count value of this pulse signal is greater than the reference pulse number, a valve closing command signal is output to the solenoid 23.

In addition, core 20. Joint 21. The compression coil spring 22 and the solenoid 23 constitute a valve closing mechanism (29 in FIG. 1),
27 is a pulse counter.

FIG. 1 is a block system showing an embodiment of a mold degassing device according to the present invention. The operation of the device shown in Figure 1 can be explained as follows.
This will be explained using FIG. The sensor block 24 of the elastic wave detection bag holder 19 receives the elastic waves emitted when the molten metal 9 moving straight in the gas vent groove 8 collides with the sensor block 24, and receives the output signal of the received sensor 19 (signal at level Sa). The signal is amplified by the preamplifier 14, passed through the bandpass filter 15, and amplified again by the main amplifier 16 to obtain a signal of level sb, which is then set in advance by the reference acoustic wave setting device 17 and input to the pulse signal generator 26. The level S of the reference signal is
c, each time sb≧Sc, the pulse signal generator 2
6 generates a pulse signal of a predetermined length (for example, 11 msec). This pulse signal is counted by the pulse counter 27, and if the counted pulse number Sd is greater than the set pulse number Se (for example, about 10 to 20 pulses) from the reference pulse number setting device 28, a valve closing signal is output to the valve closing mechanism 29. do.

When the valve close signal is output, the electric circuit of the solenoid 23 is cut off, and the restoring force of the compression coil spring 22 causes the valve body 4 attached to the valve stem 5 to come into close contact with the valve seat 12, and the gas discharge chamber is removed from the gas vent groove 8. The discharge of gas from the gas discharge hole 6 via the gas discharge hole 13 will be stopped. As the pulse signal generator 26, for example, a mono multi-vibrator or the like is used.

Next, the operation of the mold degassing device having the block system shown in FIG. 1 will be explained. Before the molten metal is injected into the product cavity 7, the solenoid 23 is energized by the pulse counter 27, and its acting force is applied to the compression coil spring 2.
2, the vent valve 1 is open. In this state, the molten metal 9 is injected into the product cavity. Molten metal 9
After almost filling the inside of the product cavity 7, the gas venting groove 8 is opened.
reach. The molten metal 9 traveling straight through the gas vent groove 8 collides with the sensor block 24 . The elastic wave sensor 25 detects the elastic waves generated during this collision and sends the signal to the preamplifier 14.
Bandpass filter 15. It is sent to a pulse signal generator 26 via the main amplifier 16. The pulse signal generator 26 compares the level sb of the signal obtained by amplifying the detection signal of the elastic wave sensor 25 with a predetermined reference level Sc, and determines the level sb.
The pulse signal generator 26 generates a pulse signal of a predetermined length every time the signal exceeds the reference level Sc, and the pulse counter 27 counts the number of pulses. The pulse counter 27 compares the counted pulse number Sd with the set pulse number Se, and cuts off the current to the solenoid 23 when Sd≧Se. As a result, the gas vent valve 1 is activated by the compression coil spring. It closes by the action of 22. By setting the length of the gas vent groove 8 so that the molten metal 9 reaches the gas vent valve 1 after the gas vent valve 1 is closed, the molten metal 9 does not enter the gas vent valve 1.

The mold degassing device configured in the above embodiment can prevent malfunctions by comparing the number of pulses Sd with the set number of pulses Se in the pulse counter 27. The reason for this will be explained below. Elastic waves generated inside the sleeve at the start of high-speed injection or during injection and propagated to the gas venting passage (hereinafter referred to as ``elastic waves generated inside the sleeve, etc. Δyoshi'') do not occur continuously in large numbers, and are rarely one-shot. In consideration of this, the reference level of the elastic wave is lowered so that flaky or granular molten metal can be detected, and the reference pulse number in the reference pulse number setting device 28 is set by the pulse counter 27 using the elastic wave generated in the sleeve inner ring. Set so that the valve close signal will not be output.

By doing so, it is possible to reliably detect elastic waves caused by flaky or granular molten metal without causing malfunction due to elastic waves generated by the inner ring of the sleeve. Furthermore, if the above reference pulse number is set in consideration of the length of the gas vent groove 8 so that the valve 1 is closed before the molten metal reaches the gas vent valve 1, the molten metal can be kept inside the gas vent valve 1. No intrusion.

An example of another mold degassing device is shown in FIG.

In the figure, 31 is an elastic wave detection device, 32 is a sensor block, 33 is a casting port, 34 is a cavity, 35 is a mold, 8 is a gas vent groove, and 3G is a gas vent valve. The gas venting valve 36 is a valve seat type, and when the valve head 36a is lowered and opened as shown in the figure, the gas venting groove 8
The terminal end of the gas vent valve 3 is connected to the vent valve 3 via a bypass 8a which detours and leads to the root part of the valve head 36a which is open from around the valve head 36a and from a part of the outer periphery of the valve head 36a.
It communicates with the gas exhaust hole provided in 6.

When the valve head 36a rises and closes, the passage is blocked and gas and molten metal are prevented from entering the gas vent valve 36.

FIG. 5 is a time chart showing the operation of the HVSC to which the present invention is applied. In the figure, Sl indicates the integrated count value of pulses from the pulse signal generator 26 based on the detection signal of the elastic wave detection device 19, S2 indicates the injection plunger speed, S3 indicates the injection plunger stroke, and S4 indicates the open/closed state of the gas vent valve. shows. In FIG. 5, T1 is the time when the gas vent valve is closed. On the other hand, time T2 is an example of the time when the gas vent valve closes in a conventional mold gas venting device in which the reference level of the elastic wave is reduced in order to improve the detection accuracy of molten metal. As described above, in the above-mentioned conventional gas venting device for a mold, the gas venting valve closes early, and the gas in the cavity may not be sufficiently exhausted.

Next, the HVSC for boat fishing will be explained using FIGS. 6 and 7. FIG. 7 is a sectional view taken along the line ■■ in FIG. 6. In FIGS. 6 and 7, A is a horizontal mold clamping unit, and B is a vertical casting unit.

4 In the horizontal mold clamping unit A, 41 is a fixed plate, 42 is a movable plate, 43 is a fixed mold, 44 is a movable mold, 45 is a trouble ring mechanism for opening the mold clamping mold, 46 is a product extrusion device, and 47 is a column. , 48 is a machine base, and 49 is a key for connecting the fixed mold 43 and the movable mold 44 to the fixed platen 41 and the movable platen 42, respectively, and is movable by the operation of a normal mold clamping cylinder (not shown). The plate 42 and the movable mold 44 are connected to the sixth
In the figure, the mold can be moved left and right to open the mold. Note that the casting force acts on the molds 43, 44 from a direction perpendicular to the operating direction of the mold clamping force, but during casting, the molds 43, 44 and the stationary plate 41. Since the space between the movable plates 42 is pressed down by the mold clamping force, the holding force of the key 49 may be about one-tenth of the mold clamping force.

50 is the cavity of the molds 43 and 44, and 51 is the mold 43.
44 is a vertical dividing surface, 52 is a constriction at the bottom of the cavity 50, 53 is a relatively large vertical hole to be connected, and 55 is a casting sleeve. The upper wall surface of the vertical hole 53 around the constriction 52 is designed to prevent the shell, which is a thin film-like solidified portion of the molten metal formed along the inner wall surface of the casting sleeve 55, from entering the cavity 5°. The shell intrusion prevention part 69 is approximately horizontal. 70 is a shell reservoir.

In the vertical casting unit B, 56 is an injection plunger;
7 is an injection cylinder, and 58 is a ladle for hot water supply. The lower end of the injection plunger 56 is connected to a piston rod 57a of an injection cylinder 57.

The casting sleeve 55 is vertically removably provided in the vertical hole 53 at the bottom of the mold 4344 when the mold is clamped, and when the injection plunger 56 is inserted into the casting sleeve 55,
A casting sleeve 55 separated from the lower surfaces of the molds 43 and 44 is provided so as to be movable laterally.

The lower surface of the vertical hole 53 of the molds 43 and 44 and the casting sleeve 5
The upper end surface of 5 is formed into a socket so as to be a removable container. The lower end of the casting sleeve 55 is integrated with a block 60 forming a cylinder 59. A ram 61 fixed to the upper part of the injection cylinder 57 is disposed inside the cylinder 59, and the operation of the cylinder 59 and the ram 61 is This allows the casting sleeve 55 to be moved up and down. cylinder 59
and the ram 61 are connected to the piston rod 57 of the injection cylinder 57.
The lower end of the block 60 is provided in parallel with the piston rod 57a, and the lower end portion of the block 60 is also provided to be slidable relative to the piston rod 57a. Injection cylinder 5
7 has a structure capable of tilting around a shaft 62, is operated by a tilting cylinder 63, and the injection position is regulated by a stopper 64.

The casting sleeve 55 and the injection cylinder 57 are supported by several support rods 66 perpendicular to the casting frame 65 which is slidably held by a shaft 62, and the upper end of the support rod 66 is connected to the lower column 47.
attached to. A bracket 67 is attached to the middle of the support rod 66, and the main body of the tilting cylinder 63 is attached to the bracket 67 so as to be swingable around a shaft 68. Note that in FIGS. 6 and 7, 71 is a gas vent valve built into the elastic wave detection device.

Next, the operation of the HVSC shown in FIGS. 6 and 7 will be explained. With the injection plunger 56 inserted into the casting sleeve 55, the casting sleeve 55 is placed in the position shown by the two-dot chain line in FIG. 67, and the molten metal is poured into the casting sleeve 55 using a ladle 58. Next, the tilting cylinder 63
, rotates around the shaft 62, and vertical casting unit B
Raise it to a vertical position. Further, the cylinder 59 and the piston rod 57a are operated simultaneously, and the casting sleeve 55 is
The injection plunger 56 is raised to the position shown by the solid line in FIG. 6, and the casting sleeve 55 is moved to the mold 43. ．．
44 to the lower surface of the dividing surface 51.

On the other hand, the mold clamping operation of the horizontal mold clamping unit A has been completed before this operation, and after the pressing of the casting sleeve 55 is completed, pressure oil is immediately introduced to the injection cylinder 57, and the molds 43 and 44 are vertically closed. The molten metal is injected into the molds 43 and 44 from directly below the dividing surface 51. In this case, before the molten metal is injected, a portion of the molten metal along the inner peripheral wall surface of the casting sleeve 55 solidifies inside the casting sleeve 55, producing so-called dead molten metal and scum. A thin solidified material called a perfectly cylindrical shell formed on the outer peripheral surface of the mold cavity 50 forms a step formed between the constriction 8 at the bottom of the mold cavity 50 and the vertical hole 53 during injection of the molten metal. That is, the shells accumulate in the shell reservoir section 70 immediately below the shell intrusion prevention section 69. The shell is thin and completely cylindrical in shape, and when the injection plunger 56 advances, the shell maintains its cylindrical shape and rises along the side wall surface, hits the shell intrusion prevention part 69, and is compressed into a bellows shape. The biscuit remains completely near the tip of the injection plunger 56. On the other hand, the molten metal is sequentially fed from the part farthest from the shell, ie, the high temperature part at the upper center, into the large direction of the constriction part 52 and into the cavity 50. In this way, the molten metal filling method follows the ideal form. Therefore, these solidified materials are not injected into the cavity 50, and only clean molten metal is injected from the high-temperature part at the upper center, resulting in a good quality cast product. When the injection is completed and the product is cooled, the casting sleeve 55 is inserted into the mold 4.
344 and open the movable mold 44 to remove the product. The product and feeder portion are not extruded by the product extrusion device 46.

On the other hand, as described above, the injection plunger 56 descends,
Due to the operation of the cylinder 59, the casting sleeve 55 is also lowered at the same time. When the lowering of both is completed, the tilting cylinder 63 is activated, and the vertical casting hot water B is tilted to the hot water supply position shown by the two-dot chain line, completing one cycle.

Note that the gas vent valves 1 and 36 of the mold gas venting device shown in Figs. 2 and 4 are applicable not only to HVSC (horizontal clamping vertical casting type die-casting machine) but also to general horizontal clamping horizontal casting type die-casting machine. It can also be used for vertical clamping vertical casting die casting machines (■SC).

FIG. 8 is a block system showing another embodiment of the mold degassing device according to the present invention.

The operation of the apparatus shown in FIG. 8 will be explained using FIGS. 2, 3, and 9. The sensor block 24 of the elastic wave detection device 19 receives the elastic waves generated when the molten metal 9 traveling straight through the gas vent groove 8 collides with the sensor block 24 disposed on the wall of the bending portion, and the sensor block 24 of the elastic wave detection device 19 receives the elastic waves. The output signal (signal at level Sa) is amplified by the preamplifier 14, passed through the bandpass filter 15, and amplified again by the main amplifier 16, resulting in a signal of 0 bell Sb (see Figure 9 (a)). After that, the reference signal level Sc (9th
In comparison with the figure (see al), when sb≧Sc, the pulse signal generation circuit 26a generates the pulse signal Sda. This pulse signal Sda is at the rHJ level for a predetermined time Tr every time the detection signal level sb exceeds the reference level Sc, and when the detection signal level exceeds the reference level within this predetermined time Tr, from that point onwards, the pulse signal Sda is maintained at rHJ level for a predetermined time Tr. Only r
In order to continue HJ, rHJ rehe level will continue. In other words, the pulse signal generating circuit 26a satisfies sb≧Sc
This is a circuit that is retriggered by the signal. For example, a retriggerable multivibrator or the like is used.

The magnitude of the level Sc of the reference signal output from the reference elastic wave setting device 17 is based on the minimum magnitude of the elastic wave that can detect the arrival of the molten metal 9, which has been determined in advance through experience or testing. This is the level shown.

1 The time comparison circuit 27a inputs the pulse signal of the signal Sda and the reference time signal Sea from the reference time setting device 28a, and compares the cumulative generation time of the molten metal detection pulse of the signal Sda with the time indicated by the reference time signal Sea. However, when the cumulative output time TR of the molten metal detection pulse signal of the signal Sda exceeds a reference time TS which is longer than the predetermined time Tr, a close signal Sf is output to the solenoid 23 to close the valve closing mechanism 29.

That is, as shown in FIG. 9(b), the pulse signal Sda becomes rHJ for a predetermined time Tr when the detection signal sb becomes sb≧Sc at time a (see FIG. 9(a)). . After the pulse signal Sda reaches rLJ, a certain period of time T
During time d, rHJ does not occur even if the detection signal sb becomes sb≧Sc as at time b. In addition to the true impact elastic waves, there are reflected waves that are reflected internally and detected late.
In order to avoid the influence of this reflected wave, a certain dead time is provided. At the next point C, the detection signal sb becomes s
Since b≧Sc, the pulse signal Sda becomes rHJ, and since no signal is continuously input, it becomes rLJ 2 after Tr. Furthermore, at time d, the pulse signal S
When da becomes rHJ and the detection signal sb becomes sb≧Sc at time e before Tr has elapsed, the trigger is retriggered and Tr is further extended. Then, before Tr elapses, the detection signal sb becomes sb≧Sc at time f and time g.
Then, the pulse signal Sda continues rHJ and its cumulative output time becomes TR.

The time comparison circuit 27a outputs a valve closing signal sr (FIG. 9(C)) when the time TR during which the pulse signal Sda is continuously at the "H" level exceeds the reference time Ts, and 29 is closed.

In this example, Tr was 64.128 or 256 μsec and TS was 10-20 msec.

The timing at which the gas vent valve 1 is closed can be adjusted by the predetermined time Tr, the reference time Ts, the length of the gas vent groove 8, and the like.

A pulse counter is provided in place of the time comparison circuit 27a,
In the method of simply counting the pulse signal Sda and comparing it with the standard number of pulses, if sb≧Sc holds true in a period shorter than the predetermined time Tr, the signal Sd
Only the pulse width of a becomes longer, the number of counts does not increase,
It is not possible to detect that the molten metal has collided with the sensor block 24,
In this case, the molten metal will flow into the gas vent valve 1.

Such a problem does not occur in the method of comparing with the reference time described above.

Due to the output of the closing signal Sf, the electric circuit of the solenoid 23 is cut off, and the restoring force of the compression coil spring 22 causes the valve body 4 attached to the valve stem 5 to come into close contact with the valve seat 12, and gas is discharged from the gas vent groove 8. The gas discharge from the gas discharge hole 6 via the chamber 13 is stopped.

In this embodiment, the pulse signal generating circuit has been described as generating a positive logic pulse when detecting molten metal, but it may also generate a negative logic pulse.

In addition, the embodiment shown in FIG. 9 (dl) outputs a valve closing signal when the predetermined time Tr and the noise dead time Td continue, and the cumulative output time exceeds the reference time Ts. .

FIG. 10 shows a state in which a water stream 33a from a nozzle 33 impinges on a sensor block 32 equipped with an elastic wave detector 31 for recognizing the passage of molten metal in the gas vent passage.

FIG. 11 shows a state in which the sensor block 32 is attached to a mold and placed on a die-casting machine (not shown).

FIG. 12 shows FFT analysis results of elastic waves detected in various cases. FIG. 13 shows the equipment configuration at this time.

In FIG. 13, 31 is an elastic wave detector, 33 is a preamplifier, 34 is a main amplifier, and 35 is a waveform analyzer.

In Fig. 12, Fig. 12 (a) shows the case with a sensor block alone and no water flow, and Fig. 12 (C) shows the case with a sensor block only with water flow (4.2 m/s). )
Figure 12(d) shows the sensor block installed in the mold, DC machine is running, 5 The mold opens, and there is no water flow, Figure 12(e) ) is sensor block built into the mold, DC machine stopped, mold opened, water flow (2
, 0m/s), Fig. 12 (f) shows the sensor block installed in the mold, DC machine running, mold closed, and without water flow, Fig. 12 1g) shows the sensor block installed in the mold, DC machine stopped, This is the case with mold closing and water flow (2.0 m/s).

Figure 12 (In GL, the water flow was received from outside the mold and collided with the sensor block. Figure 12 1g) and (b)
From this, it can be seen that in the case of a single sensor block, there is a difference of 40 dB in the actual value of the detected elastic waves depending on the presence or absence of water flow, and that this method of detecting water flow is sufficiently practical.

It can be seen from FIGS. 12(d) and (f) that when the die-casting machine is operated, the effective value becomes large in a relatively low frequency region. Also, from Figure 12 (gl), it can be seen that water flow can be detected even when the mold is closed. Generally, the density of molten metal is greater than water, so the difference in the effective value of elastic waves depending on whether or not there is collision of molten metal is In addition, it can be seen that the passage of the molten metal can be detected with high accuracy by using a high-pass filter with a frequency of about 100 kHz to 200 kHz.Also, the elastic waves detected when the molten metal collides Since the effective value of is quite small, it is more appropriate to use a linear amplifier than a log amplifier in order to improve the detection accuracy of molten metal.

Next, a water injection experiment was conducted using a horizontal die-casting machine. FIG. 14 shows the method.

In FIG. 14, 31 is an elastic wave detector, 36 is a detection signal processing device (for example, a linear amplifier with a gain of 20 dB bypass filter), 37 is a die-casting machine speed displacement converter, 3
8 is a recorder, 39 is a rubber plate, 40 is a mold gas vent valve, 41 is a load cell, and 42 is a DC amplifier. The load cell 41 shown in the figure determines the timing when water collides with the gas vent valve 40.

Further, FIG. 15 shows the configuration of the detection signal processing device in FIG. 14. In FIG. 15, 31 is an elastic wave detector, 33 is a preamplifier, 34 is a main amplifier, 43 is a frequency filter, 4
4 is a pulse generator, and 45 is a reference signal setter.

The pulse generator 44 in the same figure operates in the same way as the pulse signal generating circuit in FIG.
Generates a pulsed electrical signal of r. This pulse generator 44 also has a dead time for noise removal of Td after the pulse time TrO as described above. The collision generates an elastic wave and at the same time some reflected waves. The time it takes for this reflected wave to reach the sensor varies depending on the reflection route, with some being faster and others being slower. The reflected waves that arrive between the Tr are not felt by the sensor, but the reflected waves that arrive after the Tr are sensed. Therefore, the next wave is not detected until the reflected wave stops coming.

Therefore, the time obtained by adding Tr and Td is set to be longer than the arrival time of the slowest reflected wave.

Moreover, a 100kHz bypass filter was used as the frequency filter 43.

Figure 16 shows the data for low speed injection, and Figure 17 shows the data for high 8 speed injection. Figure 16 and 1
In Figure 7, Sll is the load cell load, S12 is the injection plunger displacement, S13 is the injection plunger speed, and 314
is a waveform indicating the cumulative value of pulse counts input from the detection signal processing device 36 to the recorder 38. Low speed injection/
In any case of high-speed injection, the cumulative pulse count value increases rapidly just before the load is applied to the load cell, and this method can be used to recognize the passage of water in the gas vent passage during injection operation in a die-casting machine. was confirmed. It can also be seen that no pulse is generated at the start of low-speed and high-speed injections. This is the frequency filter 43
The mechanical noise generated during injection is separated by the use of If you do not use a frequency filter,
Many pulses were output at the beginning of low and high speed injections.

In addition, as shown in FIG. 14, when the cross-sectional area of the portion connecting the mold cavity to the gas venting passage, that is, the vent gate portion, was changed by the rubber plate 39 and similar measurements were performed, the cross-sectional area of the vent gate was 9 smaller. It was found that the number of pulses generated increased as the number of pulses increased.

From this, it was found that by reducing the cross-sectional area of the vent gate within a range that does not impair the ability to exhaust gas in the mold cavity, the number of pulses generated increases, which is advantageous in recognizing the passage of molten metal.

Figure 18 Tb+ and (bl, (C)) show the injection stroke (characteristic line 521) and pulse count (characteristic line 522) when aluminum alloy is injected at low speed using a horizontal clamping vertical injection die casting machine (HV SC). The temporal changes and the FFT analysis results of the detected elastic waves are shown. Fig. 18 Tb) shows the FFT analysis result at time Tll, and (C1 shows the FFT analysis result at time T12.
From Figure (a), it can be seen that the pulse count increases rapidly just before the injection is completed.

Figure 18 (The pulse count at time T11 at 810 is the detection of the elastic wave generated by slight galling of the plunger tip.The timing at which the pulse count increases rapidly is when the molten metal completely fills the inside of the mold cavity. The pulse count at time T12 in FIG. 18 (al) is due to the elastic wave when the molten metal collides with the sensor block.

〔Effect of the invention〕

As explained above, the first invention of the present invention is arranged in the middle of a molten metal passage to detect the elastic waves generated when the molten metal passes and collides with the wall surface of the molten metal passage, and the detection signal level is set as a reference. Every time the level is exceeded, a pulse-like electrical signal of a predetermined length is generated 7, the pulse-like electrical signals are counted, and when the counted value reaches a preset count value, an electrical signal is generated, and this electrical signal By closing the valve, the reference level of the elastic wave is lowered so that flaky or granular molten metal can be detected, and the preset count value is output as a valve closing signal by the elastic wave generated in the inner ring of the sleeve. If set to a value without , the gas venting valve will not close prematurely due to the elastic waves generated in the inner ring of the sleeve, and the molten metal will not enter the venting valve, and the gas venting inside the product cavity will always be stable. There is an effect that can be done.

1 Furthermore, the second invention of the present invention is arranged in the middle of a degassing passage to detect the elastic waves generated when the molten metal collides with the wall of the passage, and uses the detection signal as a reference. Generates a Hals-like electric signal for a certain period of time each time the level of the detected signal exceeds the level of the reference signal.
The cumulative output time of this pulsed electrical signal is measured, and when the cumulative output time reaches a preset time, an electrical signal is generated, and the gas vent valve is closed by this electrical signal. The same effect as the first invention is achieved.

[Brief explanation of drawings]

FIG. 1 is a block system diagram showing an embodiment of a mold degassing device according to the first invention of the present invention, and FIGS. 2 and 3 show a general mold degassing device and a mold. A cross-sectional view, FIG. 4 is a configuration diagram showing an example of another mold gas venting device, and FIG.
The figure is a time chart for explaining the operation of the HVSC to which the present invention is applied, FIG. 6 is a sectional view showing a general HVSC, FIG. 7 is a sectional view taken along the line ■-■ in FIG. 6, and FIG. A block system diagram showing an embodiment of the mold degassing device according to the second invention of present invention 2, FIG. 9 is a time chart for explaining the operation of the device in FIG. 8, and FIG. 10 is a sensor block. Fig. 11 is an explanatory drawing showing the sensor block attached to a mold and placed on a die-casting machine (not shown); Fig. 12 is an elastic wave FF
A graph showing the T analysis results, Fig. 13 is a block system diagram showing the equipment configuration for FFT analysis, Fig. 14 is a block diagram showing the equipment configuration for water injection experiment, and Fig. 15 is a block diagram showing the equipment configuration for the water injection experiment.
The configuration diagram of the detection signal processing device shown in Figures 16 and 17
The figure is a time chart showing data during low-speed injection and data during high-speed injection, and FIG. 18 is a time chart showing the injection stroke and pulse count when aluminum alloy is injected at low speed. DESCRIPTION OF SYMBOLS 1... Gas vent valve, 2... Movable mold, 3... Fixed mold, 4... Valve body, 5... Valve stem, 6... Gas discharge hole, 7... Product cavity, 8... Gas vent groove, 9
... Molten metal, 14... Preamplifier, ]5... Bandpass filter, 16... Main amplifier 3, 17... Reference sound wave setting device, 19... Sound wave detection device, 20...・Core, 22... Compression coil spring, 2
3... Solenoid, 24... Sensor block, 25
...Sonic wave sensor, 26...Pulse signal generator, 27
... Pulse counter, 28 ... Reference pulse number setting device, 29 ... Valve closing mechanism.

Claims (2)

[Claims] (1) In a mold gas venting device equipped with a gas venting valve at the end of a gas venting passage from a mold cavity, the device is disposed on the wall surface of a bent part formed in the middle of the gas venting passage. an elastic wave detection means that recognizes the passage of the molten metal by detecting elastic waves generated when the molten metal collides with the wall surface, and a detection signal level output from this elastic wave detection means is compared with a reference level. and pulse signal generating means for generating a pulse-like electrical signal of a predetermined length each time the detection signal level exceeds the reference level, and counting the pulse-like electrical signals and when a preset count value is reached. 1. A degassing device for a mold, comprising: a pulse counter that generates an electric signal; and a valve closing mechanism that closes the valve based on the electric signal from the pulse counter. (2) In a mold gas venting device equipped with a gas venting valve at the end of a gas venting passage from a mold cavity, the device is disposed on the wall surface of a bent part formed in the middle of the gas venting passage. an elastic wave detector that recognizes the passage of the molten metal by detecting elastic waves generated when the molten metal collides with the wall surface, and a detection signal from this elastic wave detector is compared with a reference signal, and the detection signal is Comparing means generates a pulsed electrical signal of a predetermined length each time the level of the signal exceeds the level of the reference signal, and the cumulative output time of the pulsed electrical signal is measured and the cumulative output time is set in advance. 1. A degassing device for a mold, comprising: a timer that generates an electric signal when a time has elapsed; and a valve closing mechanism that closes the valve based on the output of the timer.