JPH08318359A - Pressure-casting method and apparatus thereof - Google Patents

Abstract

PURPOSE: To obtain a cast product having excellent strength and toughness without hot-cracking and shrinkage cavity by executing feedback-control to the pressure control of hydraulic cylinder of a squeeze plunger through the actual squeeze pressure and the vibration squeeze pressure. CONSTITUTION: After packing molten metal 13 in a cavity 40 with the plunger tip 39, an intentionally changed metal pressurizing force is previously applied to the molten metal 13 in the cavity 40 by operating a feedback controller 26, servo valve 15, hydraulic cylinder 43 and the squeeze plungers 44, 42. While controlling the hydraulic pressure of a hydraulic cylinder 43, the pressure-casting is executed and the metal pressurizing force is continuously detected by using a pressure detecting device 45 and the feedback control is executed based on this detected force and the metal pressurizing force is controlled to be a prescribed force. In such a way, the inner part of the cast product is formed with only a cubic system and the segregation of solute element is not developed and the casting without hot-cracking and shrinkage cavity can be attained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention casts a molten metal such as an aluminum alloy or a magnesium alloy into a mold cavity, and applies a squeeze pressure to the molten metal cast in the mold to compensate for shrinkage of the molten metal during solidification. The present invention relates to a pressure casting method and apparatus adapted to be added.

[0002]

2. Description of the Related Art Conventionally, when a light metal alloy such as an aluminum alloy is cast into a mold to obtain a cast product, in order to reduce the occurrence of shrinkage cavities and improve the quality, the molten metal is cast into a molten metal. The casting method has been adopted in which the molten metal is continuously pressurized under the condition that a constant high pressure of, for example, 600 kg / cm ² is continuously applied until the solidification is completed. Particularly, when high quality such as pressure resistance and high strength is required such as automobile parts, a method of casting at high pressure has been widely used recently.

As a method of preventing shrinkage cavities in a cast product, for example, as described in Japanese Patent Laid-Open No. 3-124358, a runner portion in front of a cavity is inserted through a gate portion. A method is also known in which a vibration transmission rod is inserted and mechanical vibration or ultrasonic vibration is applied to the vibration transmission rod. Further, as disclosed in Japanese Patent Publication No. 3-71214, a method is known in which a vibrator is attached to the root of the injection plunger to apply vibration to the molten metal.

Further, Japanese Patent Laid-Open No. 2-207960 and U
As described in SP5119866, a method is known in which, when the pressure of the cylinder chamber is changed and the pressure plunger is advanced by time / stroke control, the pressure plunger moves forward while vibrating. . Further, as described in Japanese Patent Laid-Open No. 6-190534, there is also known a method of applying a hydraulic pressure having a constant amplitude and frequency to a hydraulic cylinder attached to a mold in a pulsed manner.

[0005]

In the conventional casting method in which pressurization is always performed at a constant pressure, especially when the pressure is high, the adhesion between the mold cavity surface and the molten metal is improved. ， The heat transfer coefficient becomes large. As a result, the metal structure in the vicinity of the cavity surface becomes fine, but the solidification morphology of the molten metal tends to be a skin formation type solidification morphology in which solidification preferentially progresses from the surface of the molten metal and columnar crystals form on the surface. .

When a columnar crystal in a direction perpendicular to the surface of the molten metal is formed in parallel along the surface in a skin formation type solidification form, the following problems occur. (1) During the solidification process, hot cracking is likely to occur between grain boundaries of columnar crystals or between a large number of parallel dendrites forming each columnar crystal. In particular, many hot cracks tend to occur at the corners.

(2) The solute element discharged between the dendrites is squeezed out to the unsolidified portion at the back of the dendrites in the surface layer by the pressing force, causing large segregation, shrinkage cavities, and strength reduction. Cause of. In addition, since band-shaped segregation continues in the inner part of the dendrite layer, and the segregated portion is a solid mass, it becomes brittle and toughness also deteriorates. (3) Due to the solidification morphology in which the release of crystal nuclei in the molten portion corresponding to the cavity surface of the mold and the formation of the crystal nuclei in the supercooled region near the molten portion hardly both occur, the crystal nuclei are Few, crystal nuclei become coarse,
This will cause a decrease in strength.

In the ordinary pressure casting in which a constant high pressure is applied as described above, the heat transfer coefficient on the wall surface of the die is extremely large due to the high pressure, and the molten metal near the wall surface of the die is rapidly cooled. . For this reason, the higher the pressure of pressure casting, the larger the heat transfer coefficient of the die wall surface, and the crystal release from the mold wall that occurs in gravity casting, for example, is It does not occur during pressurization after filling the melt. That is, in the case of pressure casting, after filling the molten metal,
A stable and solidified shell is quickly formed. Among the crystals that make up the solidified shell, the crystals whose crystal orientation is oriented in the direction in which solidification preferentially grows in the heat flow direction quickly grows into columnar crystals.

As a result, the equiaxed chill crystal zone, which is a stable solidified shell initially formed on the wall surface of the mold, the large grown columnar crystal,
And inside the cooling rate is not as fast as the mold surface,
During the process of filling the cavity with the molten metal, the metal structure becomes an equiaxed crystal that grows with some crystals released from the mold surface as nuclei. Note that the solute element discharged between the dendrites forming the columnar crystal is squeezed out to the non-solidified portion by the pressing force, so that the solute element is concentrated and segregated on the surface portion of the columnar crystal.

The phenomenon described in (1) above is caused by, for example, a magnesium alloy such as MC2, a 7xx series alloy (7000 series duralumin series alloy), AC7A.
It can be seen when an aluminum alloy such as (aluminum alloy containing 5% magnesium) is high pressure cast. Further, the phenomenon described in (2) above becomes a problem in an aluminum alloy having high strength and high toughness such as AC4C, and the phenomenon described in (3) above is, for example, M
It occurs in magnesium alloys such as C2.

On the other hand, in the method disclosed in Japanese Patent Laid-Open No. 3-124358, a vibration transmitting rod is inserted into the runner portion in front of the cavity through the gate portion to give vibration. However, there is a drawback in that the gate part, which is thin and the molten metal is hardened easily, obstructs the vibration of the vibration transmission rod to the molten metal in the cavity. Even if a vibration transmission rod is inserted into a part of the cavity in which shrinkage cavities are likely to occur and vibrates, it gives mechanical vibration or ultrasonic vibration. The vibration transmitting rod, which also acts, causes a positional change with a dimensional amplitude, and is displaced. And the amplitude was extremely small.

[0012] Therefore, a predetermined specific location,
In other words, it was possible to prevent the shrinkage cavity from occurring only around the vibration transmission rod. Further, when performing high pressure casting, the mold clamping force is often set to a considerably large value such as 1500 tons. In such a case,
It is practically impossible to vibrate the entire casting device or the entire mold clamping device. This is also due to the heavy weight of the mold and the device.

Further, in the one disclosed in Japanese Patent Publication No. 3-71214, since the injection plunger itself is vibrated, the thin and narrow gate portion interferes with the inside of the cavity like the above-mentioned one. Vibration is not sufficiently transmitted to the molten metal. Even if the gate portion is formed to be a little thick, the vibrating plunger is separated from the cavity, so that the vibration is not sufficiently transmitted to the molten metal in the cavity.
Of course, also in this case, mechanical vibration is applied, and like the above-described one, position variation having a dimensional amplitude is performed and displacement is performed. And
Its amplitude is also extremely small. Therefore, there is a drawback that the occurrence of shrinkage cavities cannot be sufficiently prevented.

Further, Japanese Patent Laid-Open No. 2-207960 and U
In the one described in SP5209095,
The driving force of the pressurizing plunger is not positively controlled so that the frequency and amplitude are intended, but the P gain and I gain of PI control are appropriately selected and the naturally occurring vibration is used. . Therefore, the frequency and amplitude of the generated vibrations will be in an extremely narrow range under conditions such as cavity volume, pressure plunger weight, and cylinder internal volume, and the gain setting value must be changed for each condition of the cavity and hydraulic equipment. Therefore, it is difficult to manage.

The optimum conditions for sufficiently exhibiting the effect of such a pressure plunger differ depending on the alloy to be injected, and require a considerably large pressure fluctuation. Therefore, it is considered that there are many cases in which sufficient effects cannot be expected with the method described in JP-A-2-207960.

The above-mentioned method is a method of adding vibration to the molten metal to improve the quality of the injection product. In these methods, the frequency or the frequency and the displacement amplitude are adopted as the control parameters. It was not the technical idea of controlling the pressure amplitude of the wave added to the molten metal as a result of the vibration as in the invention.

On the other hand, in the method described in Japanese Patent Laid-Open No. 6-190534, the working fluid pressure from the hydraulic cylinder is applied to the molten metal in the die through the die and the die holding member. The transmission efficiency of hydraulic oil pressure to was not always good. Further, in this method, the hydraulic oil pressure having a predetermined pressure amplitude and frequency is applied, but this is a program control that is merely given as a set value, and is not feedback control like the present invention, It was difficult to always have sufficient hydraulic oil pressure to act sufficiently in all operating regions. Therefore, sufficient results were not always obtained.

It should be noted that even if vibration having the same fluctuation amplitude in terms of displacement or dimension is applied to the vibration transmission rod or the like, the pressure acting on the molten metal changes, but at the degree of crystallization of the solid phase, that is,
The added pressure fluctuation range changes as the volume of the liquid phase changes. That is, if the displacement is controlled to be a constant value, the solidification of the molten metal progresses and the volume of the liquid phase gradually decreases as time passes. The ratio of the volume of the molten metal that is pushed down by the forward movement and decreases, that is, the amount of strain gradually increases, and the pressure fluctuation width gradually increases accordingly.

For example, a pressure locus as shown in FIG. 13 is drawn. In FIG. 13, on the horizontal axis, immediately after the molten metal is cast into the cavity and almost filled, the elapsed time t (sec) from when the vibration transmission rod or the like is started to move and the metal pressing force is applied to the molten metal is shown. The vertical axis represents the metal pressure P (kg / cm ² ) acting on the molten metal and the movement stroke S (mm) of the vibration transmission rod. The time-metal pressure diagram and the time-stroke diagram are shown. .

Further, due to the change in viscosity caused by the crystallization of the solid phase, the degree of attenuation of the pressure fluctuation width when propagating in the molten metal also changes. In actual casting, due to variations in casting conditions, the solid phase ratio of the molten metal immediately after filling and the degree of increase of the solid phase after that also differ for each shot. In such a situation of actual casting, it is difficult to obtain the intended effect.

Since the pressure locus as shown in FIG. 13 is drawn, first, if a pressure fluctuation amplitude to the extent that a quality improvement effect can be expected is added, the pressure fluctuation increases as the solidification progresses. Passage and hot cracking occurs. On the contrary, if a pressure fluctuation amplitude that does not cause hot cracking is added in the latter period, it is not possible to add a pressure fluctuation sufficient for the effect to appear in the early stage of solidification. In addition, if the addition of vibration is stopped when the pressure fluctuation increases to the level where hot cracking occurs, the effect of quality improvement cannot be expected inside the cast product.

[0022]

In the present invention, in order to solve such a problem and obtain the intended effect, the metal pressing force, that is, the vibration squeeze pressure is feedback-controlled. That is, in a pressure casting method in which a molten metal is cast into a mold cavity and a squeeze pressure is applied to the molten metal in the mold by a squeeze plunger of a hydraulic cylinder so as to compensate for shrinkage of the molten metal when it solidifies,
The squeeze plunger of a hydraulic cylinder is a moving stroke with respect to a predetermined time when the median value of the oscillating stroke at present is estimated from the non-oscillating stroke value obtained by filtering the oscillating stroke value of the squeeze plunger. While moving forward with feedback control so as to gradually increase along the curve of, the pressure converted from the actual vibration squeeze pressure applied to the molten metal so that the median value becomes zero is determined as the number of vibration cycles per second. Predetermined vibration frequency and the value of the difference between the maximum value and the minimum value or the difference between the maximum value and the median value of zero during the vibration cycle over time Amplitude and the median value represented by the amplitude are oscillated so that the median value becomes zero. So as to follow the vibration squeeze pressure pattern or locus had been established to control the pressure to be applied to the hydraulic cylinder with a squeeze plunger,
In this pressure control, the hydraulic cylinder is operated by the actual squeeze pressure and the predetermined locus of the squeeze pressure that represents the vibrating squeeze pressure vibrating according to the predetermined vibrating squeeze pressure pattern over time. The applied squeeze squeeze pressure is feedback controlled.

As another method, when the molten metal is cast into the mold cavity and the squeeze plunger of the hydraulic cylinder is advanced to compensate the shrinkage of the molten metal when it solidifies, a squeeze pressure is applied to the molten metal, In the first short time,
The non-oscillating pressure is added to the molten metal while increasing the plunger stroke to a predetermined value, and then,
A squeeze squeeze pressure pattern or trajectory that causes a periodically changing oscillating squeeze pressure having a predetermined frequency and amplitude to act on the molten metal is followed, and the squeeze plunger of the hydraulic cylinder moves forward while vibrating its moving stroke. Then, the hydraulic cylinder is controlled so as to apply an oscillating squeeze pressure to the molten metal in the mold. When controlling the part to which this oscillating squeeze pressure is applied, the oscillating squeeze pressure that actually acts on the molten metal and the predetermined The vibration squeeze pressure is controlled by feedback based on the vibration squeeze pressure pattern or trajectory.

A pressure casting apparatus for that purpose is as follows:
A mold having a mold cavity, a pouring device for casting molten metal into the mold cavity, a hydraulic cylinder having a squeeze plunger for applying an oscillating squeeze pressure to the molten metal filled in the mold, and a time during solidification contraction of the molten metal. The vibration squeeze pressure setter, which gives a change pattern or locus of the vibration squeeze pressure having a predetermined amplitude and frequency to be applied to the molten metal according to the progress of, the mold or hydraulic cylinder for actual squeeze pressure measurement. A mounted pressure detector, a feedback control device for performing feedback control so that the hydraulic pressure acting on the hydraulic cylinder becomes a vibrating squeeze pressure having a predetermined amplitude and frequency based on the set value and the detected value of the vibrating squeeze pressure. The device was equipped.

[0025]

In the present invention, the molten metal is filled in the mold, and the hydraulic pressure of the hydraulic cylinder for applying a pressing force to the molten metal in the mold is set to a predetermined high pressure and a predetermined pressure relatively smaller than this high pressure. The low pressure and the low pressure are applied by feedback control so that they act cyclically at short intervals alternately, so that the squeeze plunger of the hydraulic cylinder directly acts on the molten metal that solidifies in the mold. A metal pressing force consisting of a pressure and a predetermined low pressure that is relatively small compared to the high pressure is alternately applied periodically and in a wavy manner at short time intervals. Then, the degree of the force of the molten metal being pressed against the mold surface changes strongly, and as a result, the heat transfer coefficient when heat is transferred from the molten metal surface to the mold surface changes periodically, and the amount of heat removed to the mold is reduced. It fluctuates periodically. Then, the solidification form of the molten metal at this time is so-called that not only the molten metal surface facing the cavity surface of the mold but also nuclei are generated in the molten metal and solidification progresses, resulting in the formation of equiaxed crystals. ， It becomes a coagulation form called massy type.

As described in the above item [0008], in the ordinary pressure casting in which a constant high pressure is applied, a columnar crystal zone composed of a large number of dendrites is formed along the surface layer, and the columnar crystal zone is formed inside the zone. It was segregated with equiaxed crystals.

However, when the molten metal is filled and the squeeze pressure is alternately and periodically applied to the molten metal at a short time interval, a high pressure is applied to the molten metal and a low pressure relatively lower than the high pressure is alternately applied. Will be added in a wavy manner. For this reason, when a low pressure is applied, the heat transfer coefficient on the surface of the mold temporarily becomes small, the latent heat generated during solidification is not sufficiently removed from the surface of the mold, and the temperature of the molten metal partially rises. Thus, due to the recalescence near the surface of the mold (brightening heat; temperature rise associated with latent heat release), crystal release and fusing of dendrite branches are released. In addition, due to the pressure applied in a wavy manner, the molten metal flows, and this is also combined to promote crystal release and fusing release of dendrite branches.

Therefore, columnar crystals that are easily generated on the surface cannot be formed, and fine equiaxed crystals are generated on the entire inner surface of the cast product, and only equiaxed crystal zones are formed. In addition, segregation does not occur in the equiaxed zone. As a result, hot cracking does not occur, shrinkage cavities hardly occur, and high-quality cast products with high strength and toughness are obtained. Of course, since the vibration squeeze pressure is feedback-controlled, a very good effect can always be obtained.

[0029]

1, 2 and 6 are a longitudinal sectional view and a control circuit diagram showing different embodiments of an apparatus for carrying out the method of the present invention. In FIG. 1, the section shown in the sectional view shows the main body of a casting machine called a horizontal type vertical vertical casting die casting machine or squeeze casting machine, 36 is a fixed mold, 37 is a movable mold, 38
Is a casting sleeve, 39 is a plunger tip, 40 is a cavity, and 41 is a gate portion. The molten metal 13 is cast into the cavity 40 from the direction of the arrow in the figure, and a casting pressure is applied. A pressure block 42 is slidably provided on a part of the movable mold 37 facing the cavity 40, and the piston rod 44 of the hydraulic cylinder 43 is attached to the pressure block 42.
, And the servo valve 15 was connected to the hydraulic cylinder 43. Here, the piston rod 44 and the pressure block 42 form a squeeze plunger of the hydraulic cylinder 43. This squeeze plunger is used for the mold cavity 40
The squeeze pressure is applied to the molten metal 13 by moving forward so as to compensate for the shrinkage of the molten metal 13 when it is solidified.

Reference numeral 26 is a feedback controller, and 27 is a pressure model section.
A metal pressing force having a predetermined high pressure and a predetermined low pressure that is relatively smaller than the high pressure is alternately and periodically applied to the solidified molten metal 13 in 0 at short time intervals. Therefore, the high pressure, the low pressure, the pressure fluctuation width consisting of an intended constant value, and the pressure fluctuation frequency are set as a time-metal pressure diagram or a numerical value, and an output signal p corresponding thereto is output. Of course, for the purpose of controlling the pressure fluctuation frequency and the pressure fluctuation width so as to change according to the passage of the pressurization time, a time-metal pressure diagram or the like may be set.

Reference numeral 28 denotes a pressure deviation detector, which outputs an output signal p from the pressure model unit 27 and an output signal from a pressure detection device 45 for detecting a metal pressure applied to the fixed mold 36 via an amplifier 29. The output signal e corresponding to the deviation value is output to the gain setting section 30. In the gain setting unit 30, the output signal e from the pressure deviation detector 28 is input, the corrected output signal v is output to the driver 31, and the driver 3
At 1, the output signal i is output to the solenoid 15a of the supply pressure setting fluctuation device 15 including a servo valve.

In the supply pressure setting fluctuation device 15, the opening of the servo valve 15 is controlled to control the pressure of the hydraulic oil and the hydraulic pressure applied to the hydraulic cylinder 43. Reference numeral 17 is a pump, 32 is a motor, 33 is a relief valve for loading and unloading, 34 is a tank, and 35 is, for example, opening / closing operation of the machine body and start of casting,
It is a command device that issues commands for loading and unloading to the relief valve 33 according to the ending operation or the like.

In the device shown in FIG. 1, the plunger tip 3
After filling the molten metal 13 into the cavity 40 by the action of 9,
By the action of the feedback controller 26, the servo valve 15, the hydraulic cylinder 43, and the squeeze plungers 44, 42, the molten metal 13 in the cavity 40 is subjected to a pre-designed changed metal pressing force. Then, at that time, pressure casting is performed while controlling the hydraulic pressure of the hydraulic cylinder 43, and accordingly, the pressure detection device 45
Is used to continuously detect the metal pressure, and feedback control is performed based on this to perform control so that a predetermined changing metal pressure is obtained.

In the feedback control of the squeeze pressure, the molten metal 13 is cast into the mold cavity 40, and the squeeze plunger 44 of the hydraulic cylinder 43 is moved forward so as to compensate the contraction of the molten metal 13 when the molten metal 13 solidifies. When applying squeeze pressure to, within the first short time,
The non-vibrating pressure is applied to the molten metal 13 by increasing the plunger stroke while increasing the non-vibrating pressure to a predetermined value. Then, the pressure model 27 regularly changes the vibration with the predetermined frequency and amplitude. Squeeze pressure to melt 13
The squeeze plunger 44 of the hydraulic cylinder 43 is moved forward while oscillating its moving stroke so as to apply the oscillating squeeze pressure to the molten metal 13 in the molds 37, 38 while following the vibration squeeze pressure pattern or trajectory acting on When controlling the cylinder 43 and controlling the portion to which the vibration squeeze pressure is applied, the vibration squeeze pressure is feedback-controlled by the vibration squeeze pressure actually acting on the molten metal 13 and the predetermined vibration squeeze pressure pattern or locus. I did it.

In the structure shown in FIG. 1, only the part to which the oscillating squeeze pressure is applied can be feedback-controlled, but normally, the part including the first non-oscillating pressure is also feedback-controlled. That is, at that time, the squeeze pressure actually acting on the molten metal detected by the pressure detection device 45, the pressure rise locus of the predetermined squeeze pressure indicating the non-oscillating portion, and the predetermined vibrating squeeze pressure pattern. Alternatively, the pressure applied to the squeeze plunger of the hydraulic cylinder is feedback-controlled by the trajectory.

FIG. 2 is a view in which the pressurizing device of the present invention is installed in a horizontal die casting machine of the vertical casting type, similar to that shown in FIG. FIG. 2 differs from that of FIG. 1 only in the part of the feedback controller.

In FIG. 2, the feedback controller is incorporated as shown. Reference numeral 46 is a pressure control controller, 47 is a pressure fluctuation width calculator, 48 is an average movement stroke calculator, 49 is a pressure signal generator similar to the pressure model 27, 28 is a pressure deviation detector, and 30 is a gain setter. , 50 shows a forward stroke of a squeeze plunger composed of a piston rod 44 of a hydraulic cylinder 43 and a pressure block 42 as a time-stroke diagram, a stroke signal generator for outputting an output signal s, 51 a stroke deviation detecting portion, 52 Is a stroke gain setter, 53 is a gain adder, and 54 is a signal generator. Further, 55 is an A / D converter for stroke signals, and 56 is an A / D converter for pressure signals.
/ D converter, 57 is a D / A converter, 58 is a stroke signal amplifier, 29 is a pressure signal amplifier, 59 is a stroke detector attached to the piston rod 44, 45 is a pressure detection device, and 31 is The driver 15 is a servo valve.

In the pressure control controller 46 shown in FIG. 2, the stroke signal generator 50 sequentially increases the average value of the vibration stroke of the squeeze plunger along a curve of the moving stroke with respect to a predetermined time. Is set so that the movement stroke of the squeeze plunger is feedback-controlled by the generated signal from the stroke signal generator 50 and the actual movement stroke detection signal of the squeeze plunger detected by the stroke detector 59. .

In the pressure signal generator 49, the pressure is
The predetermined number of vibrations, which is determined as the number of vibration cycles per second, and the difference between the maximum value and the minimum value or the difference between the maximum value and the average value of zero during the vibration cycle over time. The vibration squeeze pressure pattern or locus is set so that the average value expressed by a predetermined amplitude, which is determined as a doubled value, becomes zero, and positive and negative alternately appear over time. The generated signal from the pressure signal generator and the vibration squeeze pressure detection signal converted from the detection value of the actual vibration squeeze pressure applied to the molten metal detected by the pressure detector 45 so that the average value of the detected pressure becomes zero. The vibration squeeze pressure is feedback-controlled by.

In the embodiment shown in FIG. 2, first, the relief valve 33 sends a signal indicating completion of filling from the die casting machine body.
To the on-line of the servo valve 15. During the first one cycle, for example 100 Hz, 0.
During 01 seconds, the spool of the servo valve 15 is opened by an appropriate preset constant signal to advance the piston rod 44 of the hydraulic cylinder 43 and the pressure block 42. At this time, the pressure detector 45 sequentially detects the metal pressing force, and the stroke detector 59 sequentially detects the movement stroke of the pressure block 42 and the piston rod 44.

After one cycle, the stroke values of 10 points sampled at regular intervals from the present time to the previous cycle are averaged, and half of the difference between the current stroke and the stroke one cycle before is added to the average value. The amount of deviation between the value and the preset stroke locus is detected by the stroke deviation detector 51, and the control signal with an appropriate gain is obtained in response to the detection.
This is the signal that controls the average travel distance of the stroke. This is illustrated in FIG. 3, for example. The stroke S changes periodically as indicated by the solid line with time t, but in FIG. 3, S1 is the stroke at the present time A, S2 is the stroke at a certain time before B indicated as T such as one cycle before, S3. Is the average stroke in the meantime, S5 is the stroke S1 at the present time A and B before a fixed time.
With stroke S2, S6 is half the value of S5, S6
4 is the value Xm obtained by adding S6 to S3, and this is the average stroke at the present time A. In the figure, the two-dot chain line M
Indicates an average stroke. When the stroke gradient is smaller than the displacement amplitude, S6 can be ignored.

Next, the pressure values at 10 points sampled by the pressure detector 45 at equal intervals from the present time to one cycle before are averaged, and a value obtained by subtracting the average value from the current pressure value, The pressure deviation detection unit 28 detects a deviation amount between a pressure locus set with an intended cycle and a pressure amplitude in advance with 0 as the center, and receives the deviation amount to obtain a control signal with an appropriate gain. This is the signal that controls the pressure fluctuation range of the vibration squeeze pressure.

The control signal of this pressure fluctuation width was previously obtained.
Feedback control signal for average travel distance of stroke
Addition in the pressure control controller 46 which is also a controller
Then, the servo signal is output via the driver 31 using the obtained output signal.
The amount of opening of the spool of the lube 15 is properly controlled, and S is shown in FIG.
Follows the set stroke trajectory on average as shown by m
However, the intended pressure fluctuation range is realized as shown in Fig. 5.
I do. 4 and 5, t on the horizontal axis is time (seconds) and S is stroke.
Roke (mm) and P are squeeze pressure (kg / cm ² ),
Smax and Smin are the maximum and minimum strokes
The small parts, Pmax and Pmin, are the vibration
The maximum and minimum part of the pressure, Pm is the average of the vibration squeeze pressure
The value part, Pi is also the maximum pressure value of the initial non-oscillating part
Initial value of vibration squeeze pressure, P_A Indicates the pressure amplitude.

In this case, the molten metal 1 is placed in the mold cavity 40.
When 3 is filled, the squeeze pressure is raised to a predetermined value without being vibrated for about 1 second, and then 10
The oscillating squeeze pressure is applied for ~ 20 seconds, but the average value and maximum / minimum value of the oscillating squeeze pressure usually gradually decrease at first and rise after a certain period of time, as shown in FIG. start. This is because if the amplitude P _A is kept constant, the molten metal is still in the liquid state at the beginning, so that the squeeze plunger of the hydraulic cylinder 43 vibrates and moves forward, but the resistance of the molten metal is relatively large. This is because it is small and relatively easy to move, and after a certain amount of time elapses, solidification of the molten metal progresses, the resistance of the molten metal gradually increases, and the squeeze plunger of the hydraulic cylinder 43 gradually becomes difficult to move.

In this feedback control, the actual squeeze pressure is measured by the pressure sensor attached to the mold or the hydraulic cylinder at the sampling time when adjacent time points are short time intervals, and the feedback sensor is attached to the hydraulic cylinder. Pressure value calculated according to the first formula in the pressurization force fluctuation width calculator 47 by using the pressure value detected during the relatively long time interval until the current sampling time by measuring the actual plunger stroke with the stroke sensor. That is, the difference between the tentative average value of the actual squeeze pressure detected at the current sampling time and the actual vibration squeeze pressure at the current sampling time, and the pressure signal generator 49 at the current sampling time predetermine the difference. The pressure deviation detector 28 calculates the first deviation between the vibration shock pressure values obtained from the set vibration shock pressure pattern. In addition, the value calculated by the second equation in the average moving stroke calculator 48 using the stroke value detected during a relatively long time interval up to the current sampling time, that is, the actual vibration at the current sampling time. The stroke deviation detector 51 calculates a second deviation between the tentative average value of the stroke and the stroke value obtained from the non-vibrating stroke locus predetermined by the stroke signal generator 50 at the current sampling time,
In order to convert the first deviation and the second deviation into the first and second control signals, an appropriate gain is added to the first deviation and the second deviation by the gain setters 30 and 52, and the second control is performed. The first control signal is added to the signal by the gain adder 53 to generate the third control signal, and the hydraulic cylinder 43 is generated according to the third control signal.
Controls the pressure exerted on.

When the present invention is carried out, depending on the type of alloy to be cast, the shape and size of the cast product, and the casting conditions, the best high metal pressure, low pressure, pressure fluctuation amplitude, pressure fluctuation frequency. Etc. are somewhat different. However, the experimental results to date have shown that the pressure fluctuation amplitude range of the metal pressure applied in a wavy manner must exceed a certain value.

For example, an alloy with few solute elements and in which columnar crystals are likely to grow, such as a 7xxx alloy, requires a pressure fluctuation range of plus or minus 100 kg / cm ² or more, such as AC7A or MC2. As described above, with respect to an alloy that is likely to form equiaxed crystals, a pressure fluctuation range of about ± 40 kg / cm ² for MC2 and about ± 20 kg / cm ^{2 for} AC7A is effective. However, for alloys such as MC2, etc., where the high temperature strength of the solid phase is extremely low, excessive pressure fluctuations, for example,
In the case of MC2, if pressure fluctuation of plus or minus 100 kg / cm ² or more is applied, conversely, it tends to cause hot cracking. As described above, when the pressure is applied to the molten metal in a wavy manner, it is necessary to control the fluctuation range of the pressure so as to be an appropriate value based on experience and experimental results.

According to our experimental results, if the fluctuation range of the metal pressing force is not more than ± 10 kg / cm ² , it is completely effective even for alloys such as AC7A, MC2, etc. which are originally prone to equiaxed crystals. It is not allowed. In order to reliably obtain the effect, 20 kg / cm ² or more is necessary even for an alloy such as AC7A which is likely to form equiaxed crystals. Of course, the upper limit of the fluctuation range of the metal pressing force is such that hot cracking does not occur depending on the high temperature strength of each alloy, for example, for MC2, plus or minus 100 kg / cm ²
It must be decided for each alloy as follows. An average pressure of 200 kg / cm ² or more is required, but 400 kg is required for cast products that are susceptible to shrinkage cavities.
/ Cm ² or more is preferable.

In high pressure casting, the casting pressure is usually 500
Since a good quality cast product can be obtained at kg / cm ² or more, the maximum value of the vibration squeeze pressure is usually 500 kg / cm ²
Try to be above. Also, this maximum value is usually 10 in consideration of the mechanical durability of the casting equipment and the casting effect.
It should be about 00 kg / cm ² or less. The minimum value of the vibration squeeze pressure can be 0 to 300 kg / cm ² .

With respect to the pressure fluctuation frequency, no effect is recognized at 0.5 Hz or less. Originally, in alloys that tend to form equiaxed crystals, the effect is observed at 2 Hz or higher,
To surely obtain the effect, 5 Hz or higher is preferable. Further, a frequency of 1000 Hz or higher is not necessary, and some effects have been recognized in all the alloys tested so far as long as the frequency is up to 500 Hz. However, in order to realize the frequency of 500 Hz, the pressurizing device has a large capacity, and there is a problem in terms of cost. Generally, a frequency of 200 Hz or less is sufficient. Under such preferable conditions, segregation does not occur, crystal liberation and fusing of dendrites are promoted, fine equiaxed grains are formed on the entire surface of the cast product, quality improvement is performed, and heat No cracks or shrinkage cavities occur.

From the above experimental results and consideration, in the present invention, the vibration squeeze pressure has an average value of 200.
In kg / cm ² or more, the amplitude 20 kg / cm ² or ± 10 kg / cm ² or more, the number of vibrations 2-50
0 Hz. And, preferably, the initial average value is 4
In 00kg / cm ² or more, the amplitude 40~1000kg /
cm ² or plus or minus 20 to 500 kg / cm
² , good frequency is 5 ~ 200Hz. In the present invention, the predetermined frequency and amplitude of the vibration squeeze pressure pattern are normally constant over time, but this may be expressed as a function of time. .

FIG. 6 shows an example in which a device for detecting the hydraulic pressure of the hydraulic cylinder 43 is used instead of the mechanical pressure detecting device 45 in the embodiment shown in FIG. 6, the same parts as those in FIG. 1 are designated by the same reference numerals as those in FIG. 1, and the description thereof will be omitted. In FIG. 6, reference numerals 81 and 81a denote pressure sensors that detect the hydraulic pressures in the head side chamber and the rod side chamber of the hydraulic cylinder 43, and the pressure detection signals detected and output by the pressure sensors 81 and 81a are output by the amplifier 2 respectively.
9 and 29a, the A / D converters 56 and 56a, and the pressure force calculator 82 inputs and calculates the pressure deviation detector 28. Deviation is detected and squeeze pressure is feedback controlled. Reference numeral 80 is a feedback controller.

As shown in FIG. 5, the initial value of the vibration squeeze pressure was 400 kg / cm ² , and the pressure amplitude was 390 k.
FIG. 7 shows the structure of the cast product obtained at g / cm ² and a frequency of 20 Hz. It can be seen from FIG. 7 that the entire surface has a fine crystallographic axis 22. In addition, the change state of the structure in the molten metal at the portion close to the mold surface at this time is shown in Fig. 9 (a).
9 is enlarged and shown in FIG. First, during the first high pressure action, the molten metal 13 is strongly pressed against the surface of the mold 36,
Crystals 24 start to be formed as shown in FIG.

Next, if a relatively low pressure is applied,
The force with which the molten metal 13 is pressed against the surface of the mold 36 is weakened accordingly, and the degree of heat transfer from the molten metal 13 to the mold 36 is also reduced accordingly, resulting in pressure fluctuations as shown in FIG. 9 (b). Occasionally, the crystal 24 is melted and released. Therefore, even if a high pressure is applied next, as shown in FIG. 9C, the crystal 24 remains melted and released, and these become nuclei, and solidification proceeds. As a result, columnar crystals do not occur due to rapid repetition of high pressure and low pressure, and fine equiaxed crystals 22 are formed on the entire surface. Then, segregation is prevented, hot cracking is prevented, and strength is improved by refining crystal grains.

On the other hand, in the conventional method, for example, as shown in FIG. 11, when a constant metal pressure P of 600 kg / cm ² was continuously applied for 20 seconds, the obtained cast product was The organization appeared as shown in FIG. In FIG. 8, columnar crystals 23 appear on the surface and equiaxed crystals 22 appear inside. In addition, alloy composition, pouring temperature, mold temperature, and used molds 36, 37, etc.
The conditions were the same as in FIG.

10 (a) to 10 (c) show the change state of the structure in the molten metal in the portion close to the surface of the mold when a constant pressure is applied. At this time, a constant force always acts,
In addition, the degree of heat transfer from the molten metal 13 to the mold 36 remains large, and segregation occurs and columnar crystals 23 appear on the entire surface, as described in the above paragraphs [0005] to [0009].

In the present invention, depending on how to select the set value in the pressure signal generator 49, for example,
As shown in FIG. 12, the average value or maximum / minimum value of the metal pressing force P, which is also the vibration squeeze pressure, can be made constant over time.

FIG. 14 shows another embodiment of the present invention, in which the partial pressurizing pin 75 for applying the metal pressing force, which is also the vibrating squeeze pressure according to the present invention, to the molten metal 13 in the cavity 40 is used for the mold 36, It is attached to the divided surface portion of 37 and shows an example in which a heat pipe 76 is embedded in the partial pressure pin 75 along the axis. Reference numeral 77 denotes a cooling water passage in the partial pressurizing pin 75, which is used to efficiently cool the thick portion of the cast product. The pressure detection device 45 was attached to the surface of the mold cavity 40.

In the above-described embodiment, in order to apply a pressing force to the molten metal in the cavity, it is possible to project into a part of the mold which is in direct contact with the molten metal in the cavity or a part of the mold. An example of using only one movable member that can be projected in a part of the mold or a part of the mold when the provided movable member is moved forward by controlling the hydraulic pressure of the hydraulic cylinder is shown. However, it is also possible to use a plurality of them. In that case, a plurality of movable members may be applied with a metal pressure having the same pressure fluctuation width and the same pressure fluctuation frequency to the molten metal, or a metal having different pressure fluctuation widths or pressure fluctuation frequencies may be applied. You may make it apply a pressing force to a molten metal.

FIG. 15 shows in detail one embodiment of the pressure detecting device 45 shown in FIGS. 1, 2 and 14. In FIG. 15, 36 is a part of the mold, 40 is a cavity, and 74 is a relatively thin circular flexure plate portion provided on a part of the surface of the mold 36 on the cavity 40 side. A slightly deeper hole 65 is provided from the rear side of the rear side. A round bar-shaped bending amount transmission rod 66 is provided on the back side of the central portion of the bending plate portion 74.
The thin circular flexure amount measuring plate 67 is pressed against the rear end face of the flexure amount transmitting rod 66. The tip central portion 66a of the deflection amount transmitting rod 66, which is in contact with the rear surface of the central portion of the flexible plate portion 74, has a tapered central portion such as a spherical shape, a truncated cone shape, or a pointed shape.

If the tip central portion 66a is tapered, the tip central portion of the bending amount transmitting rod 66 is always the first portion of the central portion of the bending plate portion 74 even when an eccentric load is applied to the bending plate portion 74. Since it comes into contact with the back surface of the thin plate portion 74a, the load is always correctly transmitted to the deflection amount transmission rod 66, and as a result,
The correct pressure value can always be obtained. Into the hole 65, a block 61 is inserted, in which a bending amount transmission rod 66 is slidably penetrated through a bush 68 in the center, and the block 61 is inserted.
Is brought into contact with the rear surface of the second thin plate portion 74b on the outer peripheral side of the flexible plate portion 74 with the tip end surface of the ring-shaped convex portion 64 close to the outer periphery thereof by the screw 69 to the rear side of the mold 36. I installed it. There is some space between the front end surface of the central portion of the block 61 and the rear surface of the flexible plate portion 74 so that the flexible plate portion 74 can bend.

A circular hole 7 is provided on the rear end side of the central portion of the block 61.
0 is provided, and a cylindrical holding member 71 for holding the outer peripheral portion of the bending amount measuring plate 67 is attached by a screw 72 in the circular hole 70, and the bending amount measuring plate is operated by the pressing member 71. The central portion of 67 is pressed against the rear end surface of the deflection transmission rod 66 with a predetermined force. Here, the block 61 and the pressing member 71 constitute a holder attached to the mold 36 for supporting the outer peripheral portion of the deflection amount measuring plate 67.
A commercially available strain gauge 73 is attached to the back surface of the flexure amount measuring plate 67, and the strain gauge 73 is connected to a strain amount measuring device main body (not shown).

Due to the action of the pressure of the molten metal 13 in the mold cavity 40, the bending plate portion 74 is bent, and accordingly, the bending amount measuring plate 67 on the rear side is bent via the bending amount transmitting rod 66,
The amount of bending is measured by the strain gauge 73. Of course, when the pressure of the molten metal fluctuates, the fluctuation state is sequentially detected. In this device, since the bending plate portion 74 is connected to the bending amount measuring plate 67 via the bending amount transmitting rod 66, the amount of strain of the bending amount measuring plate 67 bends in proportion to the magnitude of pressure. It corresponds to the amount of distortion of the plate portion 74. Then, in consideration of the thickness of the flexible plate portion 74, the sizes of the inner diameters of the block 61 and the pressing member 71, etc., the pressure acting on the flexible plate portion 74 is always converted immediately from the strain amount of the flexible amount measuring plate 67. Can be accurately determined. The converted pressure can be output as a feedback control signal. Also, the pressure fluctuation state can be known by displaying it as a numerical value or displaying it on a graph. The pressure can be measured even if only small pressure fluctuations are applied.

FIGS. 16, 17, and 18 show other different embodiments of the pressure detecting device 45. In FIG. 16, 37 is a movable mold or a nest fitted in the movable mold 37, 40 is a mold cavity, 61a is a block fitted into a part of the cavity 40 side surface of the mold 37 from the rear side, and 74c is a block. 61a is a relatively thin circular flexible plate portion that is provided by being fitted in a part of the surface of the cavity 40 side, and a relatively deep hole 65a is formed stepwise from the rear side behind the flexible plate portion 74c. It is provided. Since a large force acts on the flexible plate portion 74c only from the cavity 40 side, the flexible plate portion 74c will not come off from the mold 37.

On the back side of the central portion of the bending plate portion 74c, the tip of a round bar-shaped bending amount transmitting rod 66b is placed in contact with it, and a relatively thin flat plate-shaped iron plate is formed on the rear end surface of the bending amount transmitting rod 66b. The central portion of the flexure amount measuring plate 67a manufactured is arranged in a pressed or abutted state. It should be noted that, considering that the contact point with the deflection amount measuring plate 67a and the measurement 0 point are delicately shifted due to the thermal expansion of the deflection amount transmitting rod 66b.
Is made of a material having a small coefficient of thermal expansion and a low thermal conductivity, for example, Si ₃ N ₄ . The deflection amount transmission rod 66b does not have the same cross section over the entire length, and has a large-diameter portion only in the portions close to both ends in the block 61a, and the other has a small-diameter portion, and only this large-diameter portion is provided on the inner surface of the hole 61b of the block 61a. It is slidable so that sliding resistance is reduced.

A stepped cylindrical block 61a is inserted into the hole 65a, and the block 61a is bolted by a bolt 82 in a state where the outer peripheral portion of the front end surface of the block 61a is in contact with the outer peripheral portion of the back surface of the flexible plate portion 74c. , Was attached to the rear side of the mold 37.
A ring-shaped groove 74d is provided from the back surface of the flexible plate portion 74c so as to be easily bent, and a circular relatively thick portion 74e is provided in the central portion. However, the relatively thick portion 74e is configured so that the back surface does not contact the block 61a. The reason why such a shape is adopted is that the flexible plate portion 74c is allowed to finely move and the pressure change acting on the molten metal can be easily measured well.

A thin hole 61b is provided at the center of the shaft center of the block 61a to guide the deflection amount transmitting rod 66b so as to be slidable in the axial direction. The position of the bending amount transmitting rod 66b is not displaced, and the tip of the bending amount transmitting rod 66b is always in contact with the center position of the thick portion 74e of the bending plate portion 74c. The tip portion of the bending amount transmitting rod 66b is formed in a spherical shape so that even if a force is eccentrically applied to the bending plate portion 74c, the tip portion is always one point. On the other hand, the rear end portion of the flexure amount transmission rod 66b is formed into a conical shape or a spherical shape so that point contact is similarly maintained.

At the rear end of the relatively large circular hole 83 provided in the center of the block 61a, a holding plate 84 is fixed with a bolt, and the bending amount measuring plate 67a is placed in the hole 83.
A compression spring 85 that supports the back surface of the outer edge of the flexure amount measuring plate 67a is provided between the holding plate 84 and the holding plate 84 to prevent the flexure amount measuring plate 67a from contacting the block 61a.
The flexure amount measuring plate 67a is slightly pressed.
This compression spring 85 is pressed in contact with the deflection amount measuring plate 67a from the rear side or is brought into contact with the deflection amount transmitting rod 66b to be positioned at a predetermined position, and is extended in the axial direction by the extension of the deflection amount transmitting rod 66b. Any other member or device, for example, an elastic member such as heat resistant hard rubber or a cylinder can be replaced.

A commercially available eddy current type high temperature displacement sensor 86 is provided in the central portion on the rear side of the flexure amount measuring plate 67a made of an iron plate, a little away from the flexure amount measuring plate 67a, to change or output the eddy current. By measuring the change in voltage, the subtle displacement of the flexure amount measuring plate 67a can be measured.
Reference numeral 87 denotes a cylindrical portion provided integrally with the holding plate 84, and adjustment bottles 88 for finely adjusting the lateral position of the displacement sensor 86 are provided at, for example, 3 to 4 positions around the cylindrical portion 87.

The displacement sensor 86 is connected to a strain amount measuring device main body (not shown). In this device, since the bending plate portion 74c is connected to the bending amount measuring plate 67a via the bending amount transmitting rod 66b, the amount of strain of the bending amount measuring plate 67a bends in proportion to the magnitude of pressure. It corresponds to the amount of distortion of the plate portion 74c. Then, in consideration of the thickness, shape and size of the bending plate portion 74c and the size of the bending amount measuring plate 67a,
The pressure acting on the bending plate portion 74c can be converted from the amount of strain of the bending amount measuring plate 67a to be always immediately and accurately obtained. The pressure obtained by the conversion can be displayed as a numerical value or can be displayed on a monitor in a graph to know the pressure fluctuation state.

Since the embodiment shown in FIG. 17 and FIG. 18 which is an enlarged view of the line AA of FIG. 17 is different from the embodiment shown in FIG. 15 in the mounting method of the deflection amount measuring plate 67 and the strain gauge 74,
Only this different part will be described. The pressing member 71 in the circular hole 70 on the rear end side of the center of the block 61 is provided with a hole 88 having a convex cross section that penetrates the inside in the vertical direction. Further, the pressing member 71 on the side having no projecting hole 88a was cut to a certain width to reduce the height.

One end of a flat plate-shaped flexure amount measuring plate 67c was cantilevered to the machined surface with a holding plate and a bolt 89. The tip of the flexure amount measuring plate 67c has a projecting hole 88a.
The side surface of the tip portion is provided so as to freely move up and down so as not to contact the inner surface of the hole 88a. In addition, here, the block 61, the pressing member 71,
The bolts 89 and the like constitute a holder attached to the mold 36 for cantilever supporting one end of the deflection amount measuring plate 67c.

A commercially available strain gauge 73a is attached to the bottom side of the back surface of the deflection amount measuring plate 67c.
3a is connected to a strain amount measuring device main body (not shown). In this device, since the bending plate portion 74 is connected to the bending amount measuring plate 67c via the bending amount transmitting rod 66,
The strain amount of the bending amount measuring plate 67c corresponds to the strain amount of the bending plate portion 74 that bends in proportion to the magnitude of the pressure. The thickness of the bending plate portion 74, the inner diameters of the block 61 and the pressing member 71, the rear end portion of the bending amount transmission rod 66, and the bending amount measuring plate 67.
In consideration of the distance from the contact position of c to the root of the deflection amount measurement plate 67c, the dimensions of the deflection amount measurement plate, etc., the deflection amount measurement plate 6
The pressure acting on the flexible plate portion 74 can be converted from the strain amount of 7c and can be immediately and accurately obtained. The pressure obtained by the conversion can be displayed as a numerical value or can be displayed on a monitor in a graph to know the pressure fluctuation state.

On the back surface on the tip side of the deflection amount measuring plate 67c,
A strain gauge 73b for temperature compensation was attached. In the cantilevered flexure amount measurement plate 67c, the flexure amount transmission rod 6 is used.
The deflection amount transmitting rod 66
Since it is a non-deformable part that does not deform even if pressed with,
The strain here is only the strain caused by the bending amount measuring plate 67c expanding and contracting due to the temperature change. Therefore, based on the strain measured by the temperature compensating strain gauge 73b, the temperature change is obtained by calculation, or the temperature inside the mold is compensated when calculating the pressure inside the mold, and the pressure inside the mold is obtained more accurately. be able to.

When the strain generated in the strain gauge 73a or in the strain gauge 73a and the temperature compensating strain gauge 73b is obtained, a well-known Wheatstone bridge circuit is used and it is recognized as a change in electric resistance. If this Wheatstone bridge circuit is used, it can be applied even if there are multiple strain gauges. For example, when two strain gauges 73a are used, they can be arranged on the deflection amount measuring plate 67c or can be placed on both front and back surfaces.

Also in the case of the temperature compensating strain gauge 73b, the change amount of the resistance value caused by the temperature change is detected. In this case, the temperature compensating strain gauge 73b functions as a dummy gauge, and strain due to the applied pressure is not picked up. In this case, a bridge circuit known as an active dummy method can be used. It should be noted that in the above-described embodiment, the strain gauges 73a and 73b are connected to the deflection amount measuring plate 67c.
Although an example in which it is attached to the back surface of the above is shown, this can also be attached to the front surface of the deflection amount measuring plate 67c.

FIGS. 19 and 20 show another embodiment of the apparatus for carrying out the method of the present invention. FIG. 19 is a vertical sectional view of a casting portion of a horizontal vertical vertical casting die casting machine. Two
Reference numeral 0 is a sectional view taken along the line BB of FIG. In FIG. 19 and FIG. 20, 36 is a fixed mold, 37 is a movable mold that opens and closes in the horizontal direction, 38 is the lower end of the dividing surface part of the fixed mold 36 and the movable mold 37, and is contacted vertically from below. The injection sleeve is detachably provided below.

In the injection sleeve 38, there is a plunger tip 39 attached to the tip of the injection plunger 39a.
Is provided slidably in the axial direction. These injection sleeves 3
8 and the injection plunger 39a and the plunger tip 39 can be moved up and down by separate hydraulic cylinders. Further, the injection sleeve 38 is provided so as to be tiltable in the lateral direction in order to facilitate the supply of the molten metal after being separated from the molds 36 and 37 downward.

A hole 94 having the same inner diameter as the inner diameter of the injection sleeve 38 is provided below the dividing surface portion of the fixed mold 36 and the movable mold 37.
A relatively wide gate 41 is provided. Gate 41
The upper part of the mold continues to the mold cavity 40 where the molten metal is cast to form an injection product. Gate 41 in movable mold 37
A pressurizing block 42 for pressurizing the molten metal is provided laterally movably in the portion facing to, and the tip end surface of the pressurizing block 42 is provided so that it can be inserted into and removed from the gate 41. The pressurization block 42 is connected to a piston rod 44 of a hydraulic cylinder 43 for pressurization at the rear part thereof.

The plunger tip 39 includes a cylindrical rear member 39c having a chamber 95 therein and a rear piston portion 3a.
9d is formed by a front member 39e that is provided in the chamber 95 of the rear member 39c so as to be movable in the axial direction, and a compression spring 99 that is a pressing member that constantly pushes the front member 39e from the rear is provided in the chamber 95. It was 100 is the piston part 3
9d is a cover attached to the front surface of the rear member 39c so as not to come off.

A ring-shaped groove 101 is provided in the outer circumferential surface between the front member 39e and the rear member 39c, that is, in the constricted portion of the front member 39e to which the cover 100 is attached. 102 is a hole 9 of the fixed mold 36 and the movable mold 37.
4 are slide blocks that can be horizontally inserted into and removed from the portions facing the slide block 1.
02 is connected to the piston rod 104 of the hydraulic cylinder 103 at the rear part.

However, the vertical position of the slide block 102 is such that when the plunger tip 39 is at the upper limit position which is the molten metal filling end position as shown in FIG. The position is set so that it can enter. The slide block 102 is for preventing the plunger tip 39 from retracting when the block 42 for pressurizing the molten metal is made to act. The groove 101 is the groove 10
Since the slide block 102 is inserted in 1 and engaged, it can be said to be a kind of engaging part.

At the center of the front side of the front member 39e of the plunger tip 39, there is provided a projection 96 which can enter the gate 41 in the molds 36 and 37 from below. The inner peripheral surface of the lower end portion of the gate 41 and the outer peripheral surface of the distal end portion of the protrusion 96 are tapered so that the protrusion 96 can be easily taken in and out. Around the protrusion 96, a ring plate-shaped auxiliary biscuit 106
Is provided so that it can be inserted and removed.

On the ceiling of the hole 94, at a portion slightly inward from the outer periphery, a projection 36 having a tapered ring shape is formed downward.
A is provided, and the auxiliary biscuit 106 also has a shape in which the upper surface of the inside is matched with the shape of the ceiling of the hole 94. The upper surface of the auxiliary biscuit 106 on the outer peripheral side is formed into a low flat plate, and a ring-shaped space is provided above the hole 94 on the outer peripheral side of the protrusion 36a so that the solidified material can be accumulated there when the molten metal is cast. .
A pipe 108 is arranged at the axial center of the plunger tip 39 and the injection plunger 39a, and passages 108a and 108b for cooling water are provided inside and outside the pipe 108.

In the case of casting, in FIG. 19, first, with the slide block 102 retracted and the plunger tip 39 lowered, the molten metal 13 is supplied to the upper part of the injection sleeve 38 by a known method. deep. In this state, an injection cylinder (not shown) is actuated to raise the plunger tip 39, and the molten metal 13 is cast into the cavities 40 of the molds 36 and 37 through the gate 41 and filled. At this time, the position of the plunger tip 39 is at the position shown in FIG. It should be noted that, at the time of casting, the solidified layer on the outer peripheral surface of the molten metal enters the space immediately below the outer peripheral portion of the ceiling of the hole 94, and therefore hardly enters the gate or the cavity.

In this state, the hydraulic cylinder 103 is then actuated to move the slide block 102 forward so that the tip of the slide block 102 is inserted into the groove 101. In this way, even if the plunger tip 39 tries to retreat, it retreats until the bottom surface near the outer periphery of the front member 39e hits the slide block 102, but does not retract further below that.

Then, immediately, the hydraulic cylinder 43 is actuated to move the pressurizing block 42 forward to push a part of the molten metal 13 to press the molten metal 13. At this time, the pressurization block 42 sets the preset time-pressure curve and time-
Feedback control is performed such that a predetermined oscillating squeeze pressure is applied to the molten metal 13 along the stroke curve to move forward. Then, the hydraulic cylinder 43, which applies a pressure to the molten metal 13 in the cavity 40 or the gate 41, alternates a predetermined high pressure with a predetermined low pressure which is relatively smaller than the high pressure at short time intervals. To the cavity 4 by controlling it so that it acts periodically and in a wavy manner.
Control is performed so that a metal pressing force having a predetermined high pressure and a predetermined low pressure that is relatively small compared to the high pressure is alternately and periodically applied to the solidified molten metal 13 in 0 at short time intervals. In addition, feedback control is performed so that the fluctuation range and fluctuation frequency of the metal pressing force reach the intended values. In order to effectively transmit the vibration squeeze pressure to the molten metal 13 in the cavity 40, the gate 41 should be as thick as possible.

When the pressure block 42 is operated, the front side member 39e of the plunger tip 39 is pushed and tries to retreat, but the front side member 39e of the plunger tip 39 does not retract further due to the action of the slide block 102. Therefore, the pressure applied by the pressure block 42 reliably and effectively acts on the molten metal 13 in the cavity 40. The auxiliary biscuit 106 does not retreat even when the front member 39e of the plunger tip 39 retracts when the molten metal is pressurized by the pressure block 42.

The shape of the auxiliary biscuit 106 is such that when the thickness of the biscuit, which is the solidification of the molten metal left in the injection sleeve 38 at the time of casting, is reduced, it is easy to mix in the cavity 40 and prevent the initial solidified layer from mixing. And, it has the effect of reducing the amount of molten metal in the biscuit part, but in addition to that, the following effects are aimed at.

Since the amount of molten metal is not completely constant in actual casting, the stop position of the plunger tip 39 is not always constant. Therefore, a gap of several mm to 1 cm must be provided between the slide block 102 and the expected stop position of the groove 101 of the plunger tip 39.
Slides back a few mm to 1 cm and then slide block 1
It will be fixed at 02. At this time, in order to reduce the amount of molten metal that escapes to the biscuit portion as much as possible, the auxiliary biscuit 106 and the front member 39e, which is convex with a protrusion 96 at the center of the tip and supported by the compression spring 99, are provided on the plunger tip 39. It is used as a part of.

When the molten metal is cast, the molten metal is already solidified in the upper peripheral portion of the auxiliary biscuit 106 in FIG. 19 immediately after the molten metal is filled. Therefore, the plunger tip 3
Even if downward pressure is applied to the upper end surface of the protrusion 96 of 9,
Convex plunger tip 39 supported by compression spring 99
Only the front side member 39e of the above-mentioned retracts, and the auxiliary biscuit 106 whose periphery is solidified does not retract. As a result, less molten metal escapes to the biscuit. In addition, the accuracy of the hot water supply is improved and the stop position of the plunger tip 39 is 2 to 3 m.
Auxiliary biscuits 10 if determined by variation of m or less
6 does not necessarily have to be provided. When the molten metal is pressurized and a predetermined time has passed, and when the molten metal solidifies, the block 42
And the slide block 102 are retracted, the plunger tip 39 is lowered, and then the mold is opened to take out the cast product.

FIG. 21 shows another embodiment of the apparatus for carrying out the method of the present invention. In FIG. 21, 3
6 is a fixed mold, 37 is a movable mold, 38 is an injection sleeve,
39a is an injection plunger, 39 is a normally used integral plunger tip, 106 is an auxiliary biscuit, 9
6 is a protrusion, 94 is a hole, 41 is a gate, 40 is a cavity, 13 is molten metal, 42 is a pressure block, 43 is a hydraulic cylinder, and 108 is a pipe for cooling water in the injection plunger 39a. 107 is a frame integrally attached to the rear side of the injection sleeve 38 via a coupling 109,
110 is a coupling 1 on the rear side of the injection plunger 39a.
11 is a piston rod of an injection cylinder (not shown) that is integrally mounted via 11.

A hook-shaped engaging portion 112 is provided below the outer peripheral portion of the coupling 111, which can be regarded as a part of the injection plunger 39a, and the slide block 102 and the slide block 102 which engage with the engaging portion 112 are provided. The hydraulic cylinder 103 for operation was attached to a part of the side surface of the frame 107. Of course, the mounting position of the slide block 102 is such that when the plunger tip 39 and the injection plunger 39a are at the molten metal filling end position.
Is at a position where it engages with the engaging portion 112. As described above, even when the engaging portion 112 of the slide block 102 is provided in a part of the injection plunger 39a, the engaging portion including the groove 101 is provided in a part of the plunger tip 39 as in the above embodiment. Similar effects are obtained.

In the embodiments shown in FIG. 2 and FIG. 3, the control is performed by using the average value of the vibration stroke of the squeeze plunger. Feedback control can also be performed using the median value of the vibration stroke at the present time estimated from the non-oscillation stroke value obtained by filtering.

Here, one of the objects of the present invention is to convert the actually vibrating pressure data so as to vibrate around 0, and also to convert the high frequency component of the vibrating stroke value of the squeeze plunger. This is to remove and convert to a stroke value that moves smoothly to control the macro movement speed of the stroke. In order to realize this, the averaging process shown in the above embodiment is also one method, but in addition to this, for example, a method of estimating the moving stroke value by linear approximation by the least square method. Alternatively, the stroke value may be passed through a low pass filter to remove high frequency components. Therefore, the filtering includes all these algorithms.

[0096]

As described above, according to the present invention, as described in the claims, the molten metal is cast into the mold cavity, and the contraction of the molten metal when the molten metal is solidified is compensated for by the hydraulic cylinder. When the squeeze plunger is moved forward to apply the squeeze pressure to the molten metal, the oscillating squeeze pressure is feedback-controlled so that the squeeze pressure is applied to the molten metal so that the squeeze pressure that has a predetermined frequency and amplitude changes regularly. The squeeze pressure consisting of a predetermined high pressure and a predetermined low pressure that is relatively small compared to this high pressure is controlled so as to be applied cyclically to the molten metal inside at a short time and alternately. By feedback control, it is possible to control the fluctuation range and fluctuation frequency of the vibration squeeze pressure to the intended values, and as a result, high pressure is applied. When a relatively low pressure is applied immediately after the heat treatment, the heat transfer coefficient of the mold surface temporarily becomes small, the heat generated during solidification is not sufficiently removed from the mold surface, and the melt temperature is partially Ascends, and crystal release and fusing release of dendrite branches occur. Further, due to the pressure of a necessary and sufficient value that is applied in a wavy manner, the molten metal flows, which is also combined to promote crystal release and fusing release of dendrite branches.

As a result, columnar crystals are not formed, only equiaxed crystal zones are formed on the entire inner surface of the cast product, and solute elements are not segregated in the equiaxed crystal zones. Therefore, hot cracking does not occur, shrinkage cavities hardly occur, and a high-quality cast product with high strength and toughness can be reliably and easily obtained. In addition, since feedback control having the contents described in each claim of the claims is performed or a device therefor is used, this feedback control can be favorably performed, and high quality casting is achieved. The embedded product can be obtained reliably and easily.

[Brief description of drawings]

FIG. 1 is a vertical sectional view and a control circuit diagram showing a first embodiment of an apparatus for carrying out the method of the present invention.

FIG. 2 is a vertical sectional view and a control circuit diagram showing a second embodiment of the apparatus for carrying out the method of the present invention.

FIG. 3 is a time-stroke diagram for explaining an example of calculating an average stroke locus of a pressure block (squeeze plunger).

FIG. 4 is a time-stroke diagram showing an example when a squeeze pressure is applied.

FIG. 5 is a time-pressure diagram showing an example when a squeeze pressure is applied.

FIG. 6 is a vertical sectional view and a control circuit diagram showing a third embodiment of the apparatus for carrying out the method of the present invention.

FIG. 7 is a metallographic view showing a solidification morphology state of a partial cross section of a cast product obtained by the method of the present invention.

FIG. 8 is a metallographic view showing a solidified morphological state of a partial cross section of a cast product obtained by a conventional method.

FIG. 9 is an explanatory view showing a crystal growth state according to the method of the present invention.

FIG. 10 is an explanatory view showing a crystal growth state by a conventional method.

FIG. 11 is a diagram showing an example of a time-metal pressure force and a stroke diagram in the conventional method.

FIG. 12 is a diagram schematically showing another example of the time-metal pressing force and stroke diagram in the method of the present invention.

FIG. 13 is a diagram showing another example of time-metal pressure and stroke diagram in the conventional method.

FIG. 14 is a longitudinal sectional view showing a fourth embodiment of the apparatus for carrying out the method of the present invention.

FIG. 15 is a vertical cross-sectional view showing a first embodiment of the pressure detecting device used when carrying out the method of the present invention.

FIG. 16 is a vertical sectional view showing a second embodiment of the pressure detecting device.

FIG. 17 is a vertical cross-sectional view showing a third embodiment of the pressure detecting device.

FIG. 18 is a partially enlarged bottom view of the portion viewed from the line AA in FIG. 17.

FIG. 19 is a longitudinal sectional view showing a fifth embodiment of the apparatus for carrying out the method of the present invention.

20 is a cross-sectional view taken along the line BB of FIG.

FIG. 21 is a vertical sectional view showing a sixth embodiment of the apparatus for carrying out the method of the present invention.

[Explanation of symbols]

 13 molten metal 15 servo valve (supply pressure setting fluctuation device) 17 pump 22 equiaxed crystal 23 columnar crystal 26,80 feedback controller 27 pressure model section 28 pressure deviation detector 36 fixed mold 37 movable mold 38 pouring sleeve 39 plunger Tip 39a Casting plunger 40 Mold cavity 41 Gate 42 Pressure block 43, 103 Hydraulic cylinder 45 Pressure detection device 46 Pressure control controller 47 Pressure fluctuation fluctuation calculator 48 Average movement stroke calculator 49 Pressure signal generator 50 Stroke signal Generator 51 Stroke deviation detector 61 Block 66, 66b Bending amount transmitting rod 67, 67a, 67c Bending amount measuring plate 73, 73a, 73b Strain gauge 74, 74c Bending plate portion 75 Partial pressure pin 76 Heat pipe 81, 81a Pressure Sensor 86 Displacement sensor 102 Slide block

Front page continuation (72) Inventor Toru Tono 1980 Okiyama, Obeshi, Ube, Yamaguchi Prefecture Ube Machinery Co., Ltd. (72) Inventor Mitsuru Adachi 1980 Oki, Oji City, Ube, Yamaguchi Prefecture Ube Usan Kikai Seisakusho Co., Ltd.

Claims (14)

[Claims] 1. A pressure casting method in which a molten metal is cast into a mold cavity and a squeeze pressure is applied to the molten metal in the mold by a squeeze plunger of a hydraulic cylinder so as to compensate for shrinkage of the molten metal when it solidifies. For the squeeze plunger of the pressure cylinder, the median value of the oscillating stroke at the present time estimated from the non-oscillating stroke value obtained by filtering the oscillating stroke value of the squeeze plunger The pressure is converted from the actual vibration squeeze pressure applied to the molten metal so that the median value becomes zero and the pressure is converted as the number of vibration cycles per second while moving forward while performing feedback control so as to gradually increase along the curve. The predetermined frequency and the maximum in the vibration cycle over time. Pressure oscillated so that the median value represented by the value of the difference between the large value and the minimum value or the predetermined value determined as the value of the difference between the maximum value and the median value of zero is zero. The pressure applied to the hydraulic cylinder with the squeeze plunger is controlled so as to follow the vibration squeeze pressure pattern or locus, which has been determined in advance to alternate positive and negative. And the locus of the predetermined squeeze pressure that represents the vibration squeeze pressure that oscillates according to the predetermined vibration squeeze pressure pattern over time, so that the vibration squeeze pressure applied to the hydraulic cylinder is feedback controlled. Pressure casting method. 2. When the molten metal is cast into the mold cavity and the squeeze plunger of the hydraulic cylinder is moved forward to apply the squeeze pressure to the molten metal to compensate for the shrinkage of the molten metal when it solidifies, within the first short time. Is applied while increasing the plunger stroke to increase the non-oscillating pressure to the melt to a predetermined value, and then applying a regularly varying vibrating squeeze pressure having a predetermined frequency and amplitude to the melt. The squeeze plunger of the hydraulic cylinder is moved forward while oscillating its moving stroke to control the hydraulic cylinder so as to apply the oscillating squeeze pressure to the molten metal in the mold. When controlling the part to which this vibration squeeze pressure is applied, the vibration squeeze pressure that actually acts on the molten metal and the predetermined The pressure casting method in which the oscillating squeeze pressure is controlled by feedback according to the existing oscillating squeeze pressure pattern or trajectory. 3. When controlling the pressure applied to the hydraulic cylinder, the squeeze pressure that actually acts on the molten metal, a predetermined plunger pressure increase locus indicating a non-oscillating portion, and a predetermined vibrating squeeze. The pressure casting method according to claim 2, wherein the pressure applied to the squeeze plunger of the hydraulic cylinder is feedback-controlled by a pressure pattern or trajectory. 4. The method according to claim 1 or 2, wherein the predetermined frequency and amplitude of the vibration squeeze pressure pattern are constant over time or expressed as a function of time. Pressure casting method. 5. The feedback control measures the actual squeeze pressure with a pressure sensor attached to a mold or a hydraulic cylinder at a plurality of sampling points having a predetermined interval, and determines from a predetermined vibration squeeze pressure pattern. The pressure casting method according to claim 1 or 2, wherein a deviation with respect to the pressure value obtained at the sampling point is calculated, and the calculated deviation is given a predetermined gain to be changed into a control signal. 6. An actual squeeze pressure is measured by a pressure sensor attached to a mold or a hydraulic cylinder at a sampling time when adjacent time points are short time intervals, and a stroke sensor attached to the hydraulic cylinder is used. The pressure value calculated according to the first equation by using the pressure value detected during a relatively long time interval up to the current sampling time by measuring the actual plunger stroke, that is, the actual pressure detected at the current sampling time. Between the squeeze pressure and the tentative average value of the actual vibration squeeze pressure at the current sampling time and the vibration shock pressure value obtained from the predetermined vibration shock pressure pattern at the current sampling time. The second equation is calculated using the stroke value detected during the relatively long time interval up to the current sampling time. The second value between the value calculated according to the above, that is, the temporary average value of the actual vibration stroke at the current sampling time point and the stroke value obtained from the predetermined non-vibration stroke locus at the current sampling time point.
Is calculated, and an appropriate gain is added to the first deviation and the second deviation in order to convert the first deviation and the second deviation into the first and second control signals, respectively. The pressure casting method according to claim 1, wherein the third control signal is generated by adding the first control signal to, and the pressure applied to the hydraulic cylinder is controlled according to the third control signal. 7. The vibration squeeze pressure has a median value of 200 k.
g / cm ² or more, amplitude 20 kg / cm ² or plus or minus 10 kg / cm ² or more, frequency ² to 500
The pressure casting method according to claim 1 or 2, which has a frequency of Hz. 8. A mold having a mold cavity, a pouring device for casting the molten metal into the mold cavity, a hydraulic cylinder having a squeeze plunger for applying an oscillating squeeze pressure to the molten metal filled in the mold, and the molten metal. Viscous squeeze pressure setter that gives a change pattern or locus of vibrating squeeze pressure having a predetermined amplitude and frequency to act on molten metal during solidification contraction of squeeze, mold for actual squeeze pressure measurement Alternatively, a pressure detector attached to the hydraulic cylinder, feedback control is performed so that the hydraulic pressure applied to the hydraulic cylinder becomes a vibrating squeeze pressure having a predetermined amplitude and frequency based on the set value and the detected value of the vibrating squeeze pressure. A pressure casting device equipped with a feedback control device. 9. The pressure preset in the vibration squeeze pressure setter is set so as to include a pressure rising portion having a non-vibration stroke portion in the initial stage of operation and a vibration squeeze pressure pattern portion following the pressure rising portion. 9. The pressure casting device according to claim 8, which is provided with a vibrating squeeze pressure setting device. 10. The time when the median value of the oscillating stroke at the present time estimated from the non-oscillating stroke value obtained by filtering the oscillating stroke value of the squeeze plunger in the pressurizing force control controller is set in advance. The stroke stroke of the squeeze plunger is fed back based on the stroke signal generator set so that it gradually increases along the curve of the movement stroke with respect to time, and the signal generated from this stroke signal generator and the actual movement stroke detection signal of the squeeze plunger. A pressure signal generator provided with a control device for controlling the vibration squeeze pressure, in which the frequency and the amplitude of the vibration squeeze pressure are set so that the median value of the vibration squeeze pressure appears alternately in positive and negative over time. Generated signal from generator and actual vibration applied to molten metal 9. The controller according to claim 8, further comprising a control device portion for feedback-controlling the vibration squeeze pressure by a vibration squeeze pressure detection signal obtained by converting the detected value of the squeeze pressure so that the median of the detected pressure becomes zero. Pressure casting equipment. 11. A vertical pouring type pouring device having a gate portion at a lower portion of the die cavity as a pouring device, wherein a tip portion of a squeeze plunger for applying an oscillating squeeze pressure to the molten metal filled in the die is provided. Claims 8, 9 or 1 provided so as to directly contact the molten metal.
0 pressure casting equipment. 12. A pressure detector is attached to a mold, and a deflection amount transmission rod having a tip contacting the back surface of a deflection plate portion disposed on the surface of the block is disposed, and the deflection amount transmission rod is connected to the block. A flexure amount measuring plate, which is provided inside so that it can be moved slightly in the axial direction and is partially held by a retainer at the rear part of the block, is arranged in a state of being pressed against the rear end face of the flexure amount transmitting rod. The pressure casting device according to claim 8, wherein the pressure casting device has a structure in which a position sensor is engaged with the position sensor. 13. A flexure amount measuring plate provided at the rear part of the block is a flat plate, one end of the flexure amount measuring plate is fixed to a holder in a cantilever shape, and a rear end face of the flexure amount transmitting rod is a flexure amount measuring plate. 13. The pressure casting device according to claim 12, wherein the strain gauge is attached to the deflection amount measuring plate at the base side from the position in contact with the. 14. An engaging portion is provided on an outer peripheral surface of a plunger tip or an injection plunger, and when the plunger tip and the injection plunger are at a molten metal filling end position, a slide block for preventing the plunger tip retracting is engaged with the engaging portion. 12. The pressure casting apparatus according to claim 11, further comprising a squeeze plunger that is provided so as to face the gate or the mold cavity in the mold and that applies a vibrating squeeze pressure.