JPH05154636A - Suction casting apparatus - Google Patents

Abstract

PURPOSE:To powerfully, uniformly and effectively execute mold holding by evacuating the inside of a casting flask and utilizing force with the negative pressure to the mold pressing force. CONSTITUTION:The lower end peripheral edge part of the casting flask 4 is held with sealing materials 7a, 7b at outside and inside to hold air-tightness. The upper surface of the mold 10 jointing a cope 1 and a drag 2 is abutted on the upper wall of the casting flask 4 with the differential pressure between the inner part and the outer part of the casting flask 4 by evacuating the inside of the casting flask 4 through an evacuating hole 5, and a force adding a dead wt of the casting flask 4 to the force multiplying the surface area of the casting flask and the differential pressure becomes the pressing force to the mold 10.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a casting apparatus, and more particularly to a suction casting apparatus for depressurizing a mold to pour molten metal into a cavity.

[0002]

2. Description of the Related Art Conventionally, a suction casting method has been used as an apparatus for manufacturing a cylinder block, an aluminum foil and the like which are automobile parts. This suction casting method, as compared with the general gravity casting method, the cavity in the mold is depressurized and the molten metal is poured, so that the circumference of the molten metal is good, and since the molten metal is gently poured from below, This has the advantage that the gas entrainment in the cavity is small. When applying this suction casting device to mass production, put the mold in a flask that keeps the secret,
A method of indirectly reducing the pressure of the mold by reducing the pressure inside the flask is used. However, when decompressing the inside of the casting flask, a pressure difference is generated between the outside of the casting mold inside the casting flask and the inside of the casting cavity, and the atmospheric pressure in the cavity may be higher than that outside the casting mold inside the casting flask. If the pressure inside the cavity is completely the same as the outside of the mold in the flask, the cycle time will be too long, and the pouring will be performed when the pressure inside the cavity drops below a certain level. is doing. In this state, due to the pressure difference between the inside and outside of the mold, a force in the direction of opening from the parting surface was applied to the mold, the molten metal was inserted into the opening parting surface, and processing defects such as hot water leaks and burrs could occur. .. Therefore, as a technique for preventing the mold from opening when the mold is depressurized, for example, an apparatus disclosed in Japanese Utility Model Laid-Open No. 60-60140 is used. The conventional technique will be described below with reference to FIG. FIG. 3 is a diagram showing the structure of a suction casting apparatus of the prior art, in which 1 is an upper mold, 2 is a lower mold having a sprue 11 at the bottom, and molds 10 are formed by being matched with each other. A cavity 9 is formed on the contact surface side of both the molds 1 and 2. An upper flask 17 having a flange portion 18 and a lower flask 19 having a flange portion 20 corresponding to the upper flask 17 are arranged outside the mold 10 and surround the mold 10. . The upper flask 17 and the lower flask 19 are
The flange portion 18 and the flange portion 20 are matched with each other via a seal member 21, and an airtight chamber 26 is formed between the casting frames 17 and 19 and the mold 10. A sprue opening 12 is formed in the lower portion of the lower flask 19, and the sprue 1 is formed in the spout opening 12.
1 is protruding. The gate 11 communicates with a stalk (not shown), and the tip of the stalk is immersed in the molten metal in a melting furnace (not shown). Further, the lower flask 19 is provided with a pressure reducing conduit 25, which communicates with a vacuum pump (not shown). Further, on the upper surface of the upper flask 17, the opening 2
2 is provided above the outer peripheral portion of the opening 22.
7 is provided with a metal bellows 23, and a crimping member 24 that is crimped to the upper mold 1 is provided at the tip of the metal bellows 23. The metal bellows 23 and the crimping member 24 constitute a pressing member 27 for pressing the mold.

The operation of the conventional technique having such a configuration will be described. The sprue opening 12 and the sprue 1 in the lower flask 19
1 is aligned and the mold 10 is placed. Then, the upper flask 17 and the lower flask 19 are connected to the flange portion 18 and the flange portion 2.
The molds are matched with 0 and sealed with a clamp device (not shown).
Next, a vacuum pump (not shown) is operated to depressurize the airtight chamber 26 composed of the upper flask 17 and the lower flask 19 and indirectly depressurize the mold 10 to remove the pressure from a melting furnace (not shown). The molten metal is introduced into the cavity 9 in the mold 10 through a stalk (not shown) and the sprue 11. At that time, a pressure difference is generated between the outside of the mold 10 inside the airtight chamber 26 and the inside of the cavity 9, so that the air pressure inside the cavity 9 becomes higher than that outside the mold 10 inside the airtight chamber 26. As a result, a force is applied to the mold 10 in the direction of opening from the parting surface, but the pressing member 27 provided on the upper casting frame 17 expands due to the pressure difference between the atmospheric pressure and the atmospheric pressure in the airtight chamber 26, and A pressing force stronger than the opening force of the mold 10 was applied to prevent the mold 10 from opening.

[0004]

However, in reality,
At the time of pouring, a pressure (hereinafter referred to as a surge pressure) at which the molten metal collides with the mold 10 is applied, and the sum of the force for opening the mold 10 due to the differential pressure and the surge pressure is applied in the direction of opening the mold 10. It is necessary to widen the pressing area of the member 27 and increase the pressing force. In addition, in the case of molding a large part, the mold 10 is naturally enlarged, so that it is necessary to increase the number of pressing members 27 and widen the total pressing area. is there. Further, since the pressing member 27 partially presses the mold 10, the pressing member 27 must be symmetrically arranged on the upper surface of the mold 10.
The pressing force is biased to one side, the non-pressed portion side is likely to open, and effective pressing of the mold 10 cannot be performed. By the above,
The pressing area and the number of pressing members 27 must be set in consideration of the force (the sum of the surge pressure and the force due to the differential pressure) to open the mold 10, and the balance of the pressing parts of the mold 10 must be set. It is necessary to set the pressing portion in consideration of the above, which requires a great deal of labor and manufacturing cost.

Therefore, according to the present invention, a mold is provided so as to be movable in the mold pressing direction, and the mold is pressed by the mold main body by utilizing a differential pressure, so that the mold is strong and is evenly and uniformly effective. The purpose is to hold down.

[0006]

In the suction casting apparatus of the present invention, a plurality of molds are matched with each other, and at that time,
A mold in which a cavity is formed on the mold matching surface side, a casting frame provided so as to surround the outer peripheral portion of the mold, an upper plate provided to mount the mold and the casting frame, and In a suction casting device which is connected to a depressurization port provided in a casting frame and comprises a depressurizing device for depressurizing the inside of the casting frame, an elastic support of the casting frame is provided at a contact portion between the upper plate and the casting frame. Means are provided.

[0007]

The pressure reducing device is operated to reduce the pressure in the flask through the pressure reducing port. As a result, the outside of the flask is at atmospheric pressure, while the inside of the flask is decompressed, so a pressure difference is generated between the outside and the inside of the flask, and this pressure difference causes the flask to Receives pressure in the direction. Further, since the flask is elastically supported on the upper plate, it is moved in the direction of the mold by this pressure, and the mold is pressed by the frame main body. As a result, the mold receives a pressing force, which is the product of the differential pressure and the surface area of the mold pressing surface of the flask, multiplied by the dead weight of the flask, on the upper surface of the mold.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. 1 and 2 are diagrams showing the configuration of the present invention. A mold 10 is configured by combining an upper mold 1 and a lower mold 2, and a cavity 9 is formed inside. The lower mold 2 is provided with a sprue 11 which is a passage for introducing the molten metal into the cavity 9 during pouring. The mold 10 is mounted on the upper plate 6, and the spout opening 12 formed in the upper plate 6 and the sprue 11 of the lower mold 2 are
Positioned for communication. This spout opening 1
2 has a stalk 3 installed.
The front end of the is immersed in a molten metal in a melting furnace (not shown). Grooves 8 are formed in the upper plate 6 around the circumference of the mold 10, and the air holes 1 penetrating the upper plate 6 are formed in the grooves 8.
3 is drilled. On the inner side wall 14 and the outer side wall 15 of the groove 8, an inner seal material 7a and an outer seal material 7b, each having a trapezoidal cross section, are provided over the circumference of the groove 8 so as to face each other. Reference numeral 4 denotes a casting frame, which is provided so as to cover the outer periphery of the mold 10. The lower end peripheral portion of the casting frame 4 is sandwiched between the inner sealing material 7a and the outer sealing material 7b. The inside of the frame 4 is kept airtight. The flask 4 is provided with a decompression port 5 and communicates with a decompression device (not shown). Further, a casting frame clamp device 16 for clamping the casting frame 4 is installed on the upper surface of the casting frame 4, and is vertically movable by an actuator (not shown). The operation of the suction casting apparatus configured as described above will be described below.

On the upper plate 6, the sprue 11 and the sprue opening 12 are positioned and the mold 10 is placed. Then, an actuator (not shown) is actuated, and the flask clamping device 1
The casting frame 4 clamped to 6 is lowered, the lower end peripheral portion of the casting frame 4 is inserted into the facing portion of the inner sealing material 7a and the outer sealing material 7b, and the lower end peripheral portion of the casting frame 4 is inserted from the bottom surface of the groove 8. A certain distance (a little longer than the stroke of the flask),
The inner peripheral sealing member 7a and the outer sealing member 7b sandwich the lower end peripheral portion of the casting frame 4 to keep the inside of the casting frame 4 airtight. At this time,
In order to reduce the insertion resistance of the casting frame 4, the inner seal material 7a and the outer seal material 7b are trapezoidal in cross section. When the casting flask 4 is sandwiched between the inner sealing material 7a and the outer sealing material 7b, the clamp of the casting flask clamping device is opened. Next, a vacuum pump, which is a depressurizing device (not shown), is operated to depressurize the inside of the casting flask 4 via the depressurizing port 5. As a result, a differential pressure is generated between the inside of the casting frame 4 and the outside of the casting frame 4, and the differential pressure causes the casting frame 4 to oppose the sandwiching force between the inner sealing material 7a and the outer sealing material 7b, and to move toward the mold 10 direction. Move to. At this time, since the air hole 13 is formed in the groove 8, the air accumulated in the groove 8 is discharged from the air hole 13. The moved casting flask 4 contacts the casting mold 10, and a pressure obtained by adding the weight of the casting flask 4 to the force obtained by multiplying the surface area of the casting flask 4 by the differential pressure is applied to the casting mold 10 as a pressing force.

As a result, the mold 10 is pressed by the upper surface of the casting frame 4 itself, so that the total pressing area of the mold 10 can be widened, a strong pressing force can be obtained, and the molten metal is inserted into the mold parting surface. Processing defects can be prevented. Further, since it is not necessary to provide a pressing member and setting of a pressing portion is not necessary, labor can be saved, productivity can be improved, and manufacturing cost can be reduced. Furthermore, since the casting flask 4 is provided close to the mold 10, the volume for depressurizing is small, so that the depressurizing speed can be increased, the vacuum pump can be downsized, and the equipment cost can be reduced. Table 1 shows the results of an experiment in which the presence or absence of the molten metal was tested by the difference in the pressing area of the mold 10 in such a suction casting apparatus.

[0011]

[Table 1]

From the above experimental results, in the prior art, the molten metal was inserted due to the surge pressure due to the increase in the suction speed, but in the present invention, the molten metal can be held by the mold 10 having a significantly large pressing area. Can be prevented from being inserted.

[0013]

As described above, the casting frame is provided so as to be movable in the pressing direction of the casting mold, and the casting pressure is applied to the casting mold body by using the differential pressure, so that the total pressing area of the casting mold is widened. Therefore, it is possible to hold down the mold strongly, and prevent defective machining due to the molten metal being inserted into the parting surface of the mold. Further, since it is not necessary to provide a pressing member and setting of a pressing portion is not necessary, labor can be saved, productivity can be improved, and manufacturing cost can be reduced.

[Brief description of drawings]

FIG. 1 is a front view showing the configuration of the present invention.

FIG. 2 is an enlarged view of part A in FIG.

FIG. 3 is a front view showing a configuration of a conventional technique.

[Explanation of symbols]

 1 ... Upper mold 2 ... Lower mold 3 ... Stoke 4 ... Casting frame 5 ... Decompression port 6 ... Upper plate 7a ... Inner sealing member 7b ... Outer sealing member 8・ ・ ・ Groove 9 ・ ・ ・ Cavity 10 ・ ・ ・ Mold 11 ・ ・ ・ Gate 12 ・ ・ ・ Gate opening 13 ・ ・ ・ Air hole 14 ・ ・ ・ Inner side wall 15 ・ ・ ・ Outer side wall 16 ・ ・ ・Casting frame clamp device 17 ... Upper casting frame 18 ... Flange portion 19 ... Lower casting frame 20 ... Flange portion 21 ... Seal member 22 ... Opening portion 23 ... Metal bellows 24. ..Crimping member 25 ... Decompression conduit 26 ... Airtight chamber 27 ... Pressing member

Claims (1)

[Claims] 1. A mold in which a plurality of molds are matched with each other, and a cavity is formed on the mold matching surface side at that time, a casting frame provided so as to surround an outer peripheral portion of the mold, and the mold. And a suction board provided with an upper plate provided to mount the casting frame, and a decompression device communicating with a decompression port provided in the casting frame and decompressing the inside of the casting frame, A suction casting apparatus, wherein elastic support means for the casting frame is provided at a contact portion between the upper plate and the casting frame.