JP3899036B2 - Casting equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a casting apparatus, and more particularly to a casting apparatus that is connected to an air vent hole that opens on the surface of a mold and is filled with a molten metal such as aluminum at a pressure near atmospheric pressure.
[0002]
[Prior art]
There are various types of casting apparatuses such as aluminum. For example, the gravity casting apparatus has many advantages such as good quality of a cast product and simplicity of a mold.
Such a mold is shown in FIG. A mold 100 shown in FIG. 5 is made of metal and is a split mold of a lower mold 102a and an upper mold 102b. The lower mold 102a and the upper mold 102b form a cavity 104 in which a cast product having a desired shape is cast. On the upper surface of the upper mold 102 b, a pouring port 106 for pouring a molten metal such as aluminum is opened, and a feeder part 108 is formed between the pouring port 106 and the cavity 104. The mold 100 is also formed with air vent holes 110, 110... For venting air from the cavity 104 when poured into the cavity 104.
When casting is performed using such a mold 100, the molten metal is poured into the pouring opening 106 opened on the upper surface of the upper mold 102 b to fill the cavity 104 with the molten metal. At this time, the air in the portion of the cavity 104 filled with the molten metal is discharged from the air vent holes 110, 110... And the inside of the cavity 104 is maintained at atmospheric pressure. As described above, according to the mold 100 shown in FIG. 5, the molten metal can be filled in the cavity 104 at a pressure close to the atmospheric pressure.
[0003]
However, in the mold 100 shown in FIG. 5, if the molten metal pouring speed from the pouring port 106 is improved to improve the productivity of the cast product, the air in the cavity 104 is caught in the molten metal, and finally Defects are likely to occur in the resulting cast product.
On the other hand, according to the die casting apparatus proposed in the following Patent Document 1, the molten metal can be filled into the cavity of the mold at high speed.
[0004]
[Patent Document 1]
Japanese Patent Laid-Open No. 2000-84648 (FIG. 1)
[0005]
In the die of the die casting apparatus proposed in Patent Document 1, a cavity having an air vent hole is formed, and a molten metal pouring port is provided below the cavity. One end of a sleeve is connected to the molten metal pouring port, and a plunger is inserted into the sleeve so as to be movable along the sleeve.
A plunger driving device for moving the plunger along the central axis of the sleeve is attached to one end of the plunger, and a pouring port for pouring molten metal into the sleeve is provided in the middle of the sleeve.
[0006]
In this die casting apparatus, the plunger is moved (retracted) to a predetermined position so that a predetermined space is formed between the other end surface of the plunger and the molten metal pouring port of the cavity by the plunger driving device, and the molten metal pouring of the cavity is performed. A predetermined amount of molten metal poured from the pouring port is stored in a sleeve extending from the pouring gate to the other end surface of the plunger.
Next, the plunger is moved (advanced) in the direction of the molten metal pouring port of the cavity by the plunger driving device, and the molten metal stored in the sleeve is press-fitted into the cavity while being filled with high pressure.
Thereafter, the molten metal press-fitted into the cavity at high pressure is cooled and solidified while maintaining the applied high pressure, the mold is opened, and the cast product is taken out.
[0007]
[Problems to be solved by the invention]
According to the die casting apparatus, the filling speed of the molten metal into the cavity of the mold can be made higher than that of the gravity casting apparatus using the mold 100 shown in FIG.
However, in the die casting apparatus, a high pressure is applied to the mold when the molten metal is press-fitted into the cavity. For this reason, a shaping | molding die must be made into a pressure | voltage resistant type | mold, a shaping | molding die enlarges and the magnitude | size of the castable product which can be cast is also restrict | limited.
Furthermore, in order to move the plunger in the direction in which the molten metal is pressed into the cavity at a high pressure, the plunger drive device needs to be able to exert a large driving force, and a hydraulic drive device that enlarges the device must be employed. You may not get.
On the other hand, in the die-casting apparatus, the molten metal is press-fitted into the cavity at a high pressure and filled, so that the air (bubbles) in the cavity is compressed at a high pressure and discharged from the air vent hole. For this reason, when the pressure of the molten metal that is press-fitted into the cavity is lowered, when casting a thin cast product or a complex-shaped cast product, it is easy to retain air in the cavity, and the molten metal that is pressed into the cavity. There is a limit to the pressure drop.
In this regard, in the gravity casting apparatus, the molten metal can be filled into the cavity 104 of the mold 100 with the gravity of the melt itself, that is, a pressure in the vicinity of atmospheric pressure, and the structure of the mold 100 can be simplified. For this reason, if the filling speed of the molten metal into the cavity 104 can be improved, the productivity of the cast product can be improved.
Therefore, an object of the present invention is a casting apparatus that fills molten metal at a pressure close to atmospheric pressure in a cavity connected to an air vent hole that opens on the surface of a molding die, and can improve the filling speed. Is to provide.
[0008]
[Means for Solving the Problems]
As a result of repeated studies to solve the above problems, the present inventor poured molten metal from above the cavity of the mold shown in FIG. 5 at a pressure close to atmospheric pressure, thereby pouring the molten metal from above the cavity. As a result, the present inventors have found that the filling rate of the molten metal into the cavity can be improved as compared with the case where the present invention is performed.
That is, the present invention relates to a casting apparatus in which a molten metal such as aluminum is filled in a cavity connected to an air vent hole opened on the surface of the mold at a pressure close to atmospheric pressure and is solidified. A sleeve having one end connected to a molten metal pouring port provided in the sleeve, and a plunger that is movably inserted from the other end of the sleeve and fills the molten metal stored in the sleeve by pouring from below the cavity And a plunger device that moves the plunger along the sleeve, and a hot water feeding means for feeding the molten metal into the sleeve, and a predetermined amount of the molten metal is stored in the sleeve. when in, and emits a signal for pouring the molten metal in the sleeve by moving the plunger in the cavity in the plunger driver, and the cavity As the molten metal is filled at a filling rate in response to changes in the cavity cross-sectional area of the molten metal liquid surface near filled in the I, wherein the control unit for controlling the moving speed of the plunger is provided Found in casting equipment.
[0009]
According the present invention smell Te, as feed water means and Okuyu pump provided in the holding furnace for holding molten metal, it constitutes a conduit for sending the molten metal from the Okuyu pump to the sleeve, as the Okuyu pump cavity A predetermined amount of molten metal can be easily stored in the sleeve by employing a fixed amount hot water pump that feeds the amount of molten metal corresponding to the amount of filling into the sleeve into the sleeve.
[0010]
In the casting apparatus according to the present invention, molten metal can be poured from below into a cavity connected to an air vent hole that opens on the surface of the mold at a pressure close to atmospheric pressure. For this reason, the air in the cavity is easier to escape than when pouring from above the cavity of the mold, and the air flow that escapes upward in the passage from the gate to the cavity contacts the molten metal flow that flows down to the cavity. Thus, air can be prevented from being caught in the molten metal flow.
In addition, the plunger moving speed can be controlled so that the molten metal is filled at a filling speed according to the change in the cavity cross-sectional area near the melt surface filled in the cavity, and air can be discharged even in a cavity with a complicated shape. Entrainment can be prevented.
Therefore, in a casting apparatus that fills the molten metal at a pressure near the atmospheric pressure into the cavity connected to the air vent hole that opens on the surface of the mold, the molten metal is poured from above the cavity at a filling speed of the molten metal. Even if it improves compared with the case, a favorable casting can be obtained.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
A schematic diagram illustrating an example of a casting apparatus according to the present invention is shown in FIG. The casting apparatus shown in FIG. 1 is an aluminum casting apparatus, and a holding furnace 10 that holds molten aluminum is provided with a hot water feed pump 12 that sends out the molten metal. The hot water supply pump 12 sends out the molten metal by a hot water supply driving device 14 such as a motor.
The conduit 16 for guiding the molten metal sent out from the hot water supply pump 12 is connected to the sleeve 22 of the plunger device 20 provided in the mold 30.
As shown in FIG. 2, the plunger device 20 has one end side of the sleeve 22 connected to a molten metal pouring port 34 provided on the side surface below the cavity 32 formed in the mold 30. For this reason, the plunger 24 is inserted into the sleeve 22 from the other end side of the sleeve 22, and the plunger 24 moves along the sleeve 22 by a plunger driving device 26 such as a motor or an air cylinder device.
[0012]
The mold 30 shown in FIG. 2 to which the plunger device 20 is attached is a split mold in which the mold 30 is divided into a left mold and a right mold in a direction perpendicular to the drawing, and both molds are closed. A cavity 32 is formed in the mold 30.
As shown in FIG. 2, the formed cavity 32 is connected to an air vent hole 36 opened on the surface of the mold 30. For this reason, the molten metal can be filled in the cavity 32 at a pressure in the vicinity of the atmospheric pressure by the plunger device 20 attached to the molten metal pouring port 34 provided on the side surface below the cavity 32.
Therefore, in the casting apparatus shown in FIGS. 1 and 2, it is not necessary that the plunger device 20 and the molding die 30 have a pressure-resistant structure as used in the die casting apparatus.
[0013]
As the hot-water supply pump 12 used in the casting apparatus shown in FIGS. 1 and 2, it is generally preferable to use a known quantitative hot-water supply pump. According to this fixed quantity hot water supply pump, it is possible to adjust so that a molten metal amount corresponding to the filling amount for one filling into the cavity 32 can be supplied, and a predetermined amount of molten metal can be easily stored in the sleeve 22 (such a fixed quantity feed). As the hot water pump, for example, refer to a metered hot water pump described in Japanese Patent Laid-Open Nos. 9-15253 and 2001-219261).
In the casting apparatus shown in FIGS. 1 and 2, when a predetermined amount of molten metal is stored in the sleeve 22 from the hot water supply pump 12 of the holding furnace 10, the plunger 24 is moved in the direction of the molten metal pouring port 34. A control unit 40 is provided that transmits a signal for starting the pouring of the molten metal in the sleeve 22 into the cavity 32 to the plunger driving device 26 by moving forward.
The control unit 40 controls driving and stopping of the hot water supply driving device 14 constituting the plunger driving device 26 and the hot water supply pump 12.
In the control unit 40, when a signal from the plunger driving device 26 is received that the plunger 24 has moved (retracted) in the sleeve 22 to a predetermined position away from the molten metal pouring port 34 of the cavity 32, A signal for driving the hot-water supply driving device 14 of the hot-water supply pump 12 in order to supply the molten metal to the space in the sleeve 22 formed between the molten metal pouring port 34 provided below and the distal end surface of the plunger 24. To send.
Further, when a predetermined amount of molten metal is fed into the sleeve 22 by the hot water supply pump 12, the control unit 40 sends a signal for driving the plunger driving device 26 to advance the plunger 24 to advance the sleeve 22. The molten metal inside is filled from below the cavity 32.
When a fixed amount hot water pump is used as the hot water supply pump 12, the fixed amount hot water pump automatically moves when the molten metal amount corresponding to the filling amount in the cavity 32 is supplied into the sleeve 22. Is set to stop.
[0014]
In the casting apparatus shown in FIGS. 1 and 2, the plunger drive device 26 is adjusted in advance so that the advance speed of the plunger 24 can be filled in the cavity 32 with the molten metal in the sleeve 22 at a pressure close to atmospheric pressure. The molten metal is filled from below the cavity 32 of the mold 30 at a pressure close to atmospheric pressure. For this reason, the air in the cavity 32 is exhausted from the air vent hole 36 which is not a molten metal pouring path.
Therefore, as in the mold 100 shown in FIG. 5, when the molten metal is filled from above the cavity 104, the cavity 32 is compared with the case where the air in the cavity 104 escapes from the pouring channel into which the molten metal is poured. The air inside can be made difficult to get caught in the molten metal. As a result, in the casting apparatus shown in FIGS. 1 and 2, the rate of molten metal pouring into the cavity 32 can be improved.
However, when the shape of the cavity 32 is complicated in order to obtain a cast product having a complicated shape, a wide and narrow portion is formed in the cavity 32, and the filling speed in the portion where the wide and narrow portion does not substantially exist in the cavity 32 is the same. In terms of speed, the air in the wide and narrow portion of the cavity 32 is likely to remain without being sufficiently removed.
[0015]
The sufficient extraction of the air is performed by lowering the filling speed of the molten metal into the cavity 32 than the filling speed of filling the wide area of the cavity 32 with the molten metal when filling the narrow section of the cavity 32 with the molten metal. be able to. By sufficiently discharging such air, it is possible to obtain a cast product having a better appearance shape.
Thus, in order to control the filling speed of the molten metal in the cavity 32, it is preferable to control the forward speed of the plunger 24 by the control unit 40. The forward speed of the plunger 24 is controlled by the control unit 40 so that the molten metal is filled at a filling speed corresponding to a change in the cavity cross-sectional area in the vicinity of the molten metal surface filled in the cavity 32.
Here, for the detection of the melt level filled in the cavity 32, a liquid level detector may be provided in the cavity 32, but the relationship between the stroke length of the plunger 24 and the melt level in the cavity 32 is determined in advance. The liquid surface position can be obtained from the stroke length of the plunger 24 in advance.
[0016]
Further, the filling speed corresponding to the change in the cavity cross-sectional area is obtained in advance for each part of the cavity 32. When obtaining such a filling speed, first, a cavity cross-sectional area is obtained in advance for each predetermined position from below the cavity 32, and a change in the cavity cross-sectional area per unit height at the predetermined position is obtained. Furthermore, the optimum filling speed without air being entrapped experimentally is obtained with respect to the change of the cavity cross-sectional area per unit height at a predetermined position.
According to the control unit 40 in which the optimum filling speed is stored in the storage unit for each predetermined position, the optimum filling rate of the molten metal at the molten liquid surface position of the cavity 32 obtained from the stroke length of the plunger 24 is called from the storage unit. The forward speed of the plunger 24 can be controlled.
[0017]
An example of obtaining the optimum filling speed will be described with reference to FIGS. FIG. 3 is a longitudinal sectional view of the mold 30, and pins 38, 38, 38 are provided in the cavity 32. 3 is a split mold that is split in a direction perpendicular to the drawing.
The change rate of the cavity cross-sectional area per unit height at a predetermined position in the height direction from the bottom surface of the mold 30 is measured, and is indicated by a broken line in FIG.
Next, a filling speed at which air is not entrapped in the molten metal at a plurality of locations in the height direction was obtained experimentally. The results are also shown by solid lines in FIG.
As is clear from FIG. 4, the portion where the change rate of the cavity cross-sectional area per unit height is small is a portion where the wide and narrow portion does not substantially exist in the cavity 32, and the filling speed is increased. On the other hand, there is a wide and narrow portion in the cavity 32 where the change rate of the cavity cross-sectional area per unit height is large, and the filling speed is lower than that where the change rate of the cavity cross-sectional area per unit height is small. To do.
Therefore, in the wide and narrow part of the cavity 32, compared with the part where the narrow and narrow part does not substantially exist in the cavity 32, the filling rate of the molten metal into the cavity 32 is reduced, and the molten metal is expelled while sufficiently expelling the air in that part. Can be filled.
As a result, it is possible to obtain a good cast product in which defects due to air entrainment and the like are eliminated.
[0018]
In the casting apparatus shown in FIGS. 1 and 2, the molten metal is supplied to the sleeve 22 from the hot water supply pump 12 of the holding furnace 10.
However, the space in the sleeve 22 formed between the molten metal pouring port 34 of the cavity 32 and the distal end surface of the plunger 24 is substantially atmospheric pressure.
For this reason, a handle saddle type ladle widely used in normal casting may be used, and the molten metal of the holding furnace 10 may be supplied by the handle saddle type ladle.
[0019]
【The invention's effect】
According to the casting apparatus of the present invention, it is possible to obtain a good cast product even when the filling rate of the molten metal into the cavity of the mold is improved as compared with the case of pouring from above the cavity of the mold. Therefore, the productivity of the cast product can be improved.
Further, the molten metal can be filled in the cavity of the mold at a pressure close to the atmospheric pressure.
Therefore, since it is not necessary to make the mold and the plunger device a pressure-resistant device as used in a die-cast device, the simplification can be achieved.
[Brief description of the drawings]
FIG. 1 is an explanatory view for explaining an outline of a casting apparatus according to the present invention.
FIG. 2 is a longitudinal sectional view for explaining the outline of a forming die and a plunger device constituting a casting apparatus according to the present invention.
FIG. 3 is a longitudinal sectional view for explaining an example of a molding die.
4 shows the change rate of the cavity cross-sectional area per unit height at a predetermined position in the height direction from the bottom surface of the mold shown in FIG. 3, and air is entrained in the molten metal at a plurality of locations in the height direction. It is the graph which calculated | required the filling speed | rate which is not.
FIG. 5 is a longitudinal sectional view for explaining a molding die used in conventional gravity casting.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Holding furnace 12 Hot-water supply pump 14 Hot-water supply drive device 16 Conduit 20 Plunger device 22 Sleeve 24 Plunger 26 Plunger drive device 30 Mold 32 Cavity 34 Molten metal pouring port 36 Air vent hole 38 Pin 40 Control part

Claims (2)

In a casting apparatus that fills and solidifies a molten metal such as aluminum at a pressure close to atmospheric pressure in a cavity connected to an air vent hole that opens on the surface of the mold,
A sleeve having one end connected to a molten metal pouring port provided below the cavity of the mold, and a movably inserted from the other end of the sleeve, and the molten metal stored in the sleeve from below the cavity A plunger device comprising a plunger for pouring and filling, a plunger drive device for moving the plunger along the sleeve, and a hot water feeding means for feeding the molten metal into the sleeve;
When a predetermined amount of molten metal is stored in the sleeve, the plunger is moved to transmit a signal for pouring the molten metal in the sleeve into the cavity to the plunger driving device , and the molten metal filled in the cavity A casting apparatus , comprising: a controller for controlling the moving speed of the plunger so that the molten metal is filled at a filling speed according to a change in the cavity cross-sectional area in the vicinity of the liquid surface . The hot water supply means consists of a hot water pump provided in a holding furnace for holding the molten metal, and a conduit for feeding the molten metal from the hot water pump to the sleeve,
The casting apparatus according to claim 1 , wherein the hot-water supply pump is a fixed-quantity hot-water supply pump that supplies an amount of molten metal corresponding to a filling amount for one filling into the cavity into the sleeve .

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