JPH07290189A - Device and method for molding core - Google Patents

Abstract

PURPOSE:To provide a core such as a shell core with high density capable of being applied to the squeeze casting. CONSTITUTION:A base table 1 which is elastically supported by a spring 10, a mold 19 for the shell mold to be held by the base table 1, an exciter 12 to give vibration to the mold 19, and a blowing device 3 provided with a blow head 32 having a blow nozzle 37 are used. A shell core which is substantially solid is molded by executing the blowing operation to blow the coated sand to the cavity C of the mold 19 and the exciting operation to give vibration to the mold 19. In the curing process, the temperature of the mold 19 is risen, and kept for five minutes or more to promote the hardening of the shell core. The blow nozzle 37 is made of rubber. A protective cap 39 is mounted on the tip surface of the blow nozzle 37.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a core molding apparatus and a core molding method capable of molding a core having a high density. The present invention can be applied to the shell mold method, warm box method, and cold box method. The invention is particularly suitable for the production of cores used in high pressure casting processes.

[0002]

2. Description of the Related Art The prior art will be described by taking a case of molding a shell core as an example. That is, when molding a shell core, generally, a molding step of loading the coated sand into the cavity by blowing the coated sand into the cavity of the molding mold in a high temperature state with compressed air is performed. The inversion step of removing the uncured coated sand by inversion to form a shell and the curing step of curing the shell at 300 to 350 ° C are to be performed.

When the coated sand is blown into the cavity of the molding die, a molding die having a blow opening opening to the outer surface and a cavity is used, and the blow nozzle of the blow head is attached to the blow opening of the molding die. Coated sand is to be blown into the mold cavity from the blow nozzle by compressed air. Moreover, in molding a gas-curable core, Japanese Patent Publication Sho 62
As disclosed in Japanese Patent Publication No. 39058-A, a molding die having a blow opening and a cavity opened to an outer surface is used, and a blow nozzle of a blow head is attached to the blow opening of the molding die. Gas-curable molding sand will be blown into the cavity with compressed air.

[0004]

In the above-mentioned technique, the blow nozzle of the blow head is mounted on the blow opening of the molding die as described above, and the coated sand or the gas-hardening molding sand is inserted from the blow nozzle into the cavity of the molding die. I will blow it with compressed air. The core molded in this manner does not cause any problem when used in a normal casting method, but the packing density of the core is not always sufficient when used in a high pressure casting method. In particular, when the core has a complicated shape, a region where the packing density decreases in the core is likely to occur. Therefore, when it is applied to the high pressure casting method, the core is easily deformed by the casting pressure, resulting in defective casting.

The present invention has been made in view of the above situation, and the object of each claim is to obtain a core having a high packing density even when the core has a complicated shape.
Therefore, it is an object of the present invention to provide a core molding apparatus and a core molding method capable of suppressing deformation and damage of a core due to casting pressure even when applied to a high pressure casting method, and suppressing casting defects.

According to the second aspect of the present invention, by forming the blow nozzle using rubber as a base material, it is possible to suppress the transmission of vibration from the molding die to the blow head when the molding die is vibrated. To provide a molding apparatus. The object of claim 3 is to equip the tip surface of the blow nozzle with a heat-resistant protective plate, so that when the molding die is heated, it is possible to suppress heat transfer from the molding die in a high temperature state to the blow head, An object of the present invention is to provide a core molding device capable of protecting the head.

According to a fourth aspect of the present invention, it is possible to mold a high-density shell core. Therefore, even when the core is applied to a high-pressure casting method, deformation of the core due to casting pressure can be suppressed and casting defects can be prevented. An object of the present invention is to provide a core molding method that can be suppressed.

[0008]

According to a first aspect of the present invention, there is provided a core molding device, comprising a base for holding a molding mold having a blow opening opening to an outer surface and a core molding cavity communicating with the blow opening, and a base. Equipped with a shaker that applies vibration to the mold held on the table, and a blow head that has a blow nozzle that is attached to the blow opening of the mold. Compress the molding sand from the blow nozzle of the blow head to the mold cavity. And a blowing device for blowing with air.

According to a second aspect of the present invention, there is provided a core molding apparatus according to the first aspect, wherein the blow nozzle is made of rubber as a base material, and the nozzle hole of the blow nozzle is partitioned by the rubber as a base material. To do. According to a third aspect of the present invention, in the core molding apparatus according to the first or second aspect, the blow nozzle has a tip end surface provided with a heat-resistant protective plate facing the blow opening of the molding die. Is.

According to a fourth aspect of the present invention, in a core molding method, a base for holding a mold having a blow opening opened to an outer surface and a shell core molding cavity communicating with the blow opening, and a base held for holding the mold. In addition to using a vibration exciter that applies vibration to the molding die, a blow head having a blow nozzle attached to the blow opening of the molding die is provided, and the coated sand is compressed from the blow nozzle of the blow head to the cavity of the molding die. Using a blowing device for blowing with air, by performing a blowing operation for blowing coated sand into the cavity of the molding die, and a vibration operation for applying vibration to the molding die,
A molding step of loading coated sand into the cavity of the molding die to mold a substantially solid shell core, and a curing step of hardening the shell core to a deep part in the molding die after the molding step. It is characterized in that they are carried out in order. The curing time can be appropriately changed depending on the mold temperature and the thickness of the shell core. For example, it can be 5 minutes or more.

[0011]

According to the invention of claim 1, when the molding sand is loaded into the cavity of the molding mold, vibration can be applied to the molding mold by the vibration exciter, so that the shape of the core is complicated. Also, a high-density and high-strength core can be obtained.
Therefore, even if the core is applied to high pressure casting, it is easy to avoid deformation and damage of the core.

According to the second aspect of the invention, since the blow nozzle is made of rubber as a base material, it is possible to reduce or avoid transmission of vibration of the molding die to the blow head.
Therefore, the protection of the blow head is improved. Further, since the nozzle hole of the blow nozzle is partitioned by using rubber as a base material, the inner wall surface itself of the nozzle hole can be expected to be deformed. If the inner wall surface itself is deformed in this way, it is advantageous for dropping the molding sand or the like adhering to the inner wall surface of the nozzle hole. Therefore, the amount of molding sand or the like attached to the inner wall surface of the nozzle hole of the blow nozzle can be reduced, which is advantageous for ensuring the opening area of the nozzle hole, and the blowing property from the nozzle hole is ensured.

According to the third aspect of the present invention, the blow nozzle has a heat-resistant protective plate facing the blow opening of the mold, so that the mold temperature is high. However, the blow nozzle made of rubber as a base material can be protected from heat and abrasion, and the protection property of the blow nozzle can be improved. According to the curing step of the fourth aspect of the present invention, heat can be sufficiently transmitted to the deep portion even with the densified shell core, and thus the coated sand forming the shell core can be hardened. Therefore, it is suitable for molding a shell core used in a high pressure casting method.

[0014]

Embodiments of the present invention will be described with reference to the drawings. This example is applied to the molding of a shell core. In FIG. 1, a base 1 is a coiled spring 1 on a floor surface F.
Three-dimensional through 0 (up-down direction, left-right direction, front-back direction)
It is elastically supported so that it can swing. The base 1 has a base 1
A vibration exciter 12 that rocks or vibrates is installed. The shaker 12 can employ, for example, a mechanism that causes an unbalanced mechanism to be operated by a motor to vibrate the base 1, or a mechanism that strikes the base 1 with a cam that is operated by a motor to vibrate the base 1. A rail 14 is arranged on the rail surface 1f of the base 1. The base 1 is equipped with a total of four claw-shaped clamps 16 that are moved up and down by a hydraulic cylinder 16x (which may be an air cylinder). A mold carriage 2 is mounted on the base 1. The mold carriage 2 is equipped with wheels 2r. The wheels 2r are guided along the rails 14, and the mold carriage 2 is movable along the rails 14.

A mold 19 as a molding mold is placed on the mold holding surface 2x of the mold carriage 2 and divided molds 19a and 19b.
It is composed of. A heater is built in the mold 19. The mold 19 has a concave blow opening 19 that opens on the outer surface.
x and the molding cavity C communicating with the blow opening 19x
With and. The blowing device 3 includes a blow tank 30 for accumulating air, a three-way valve 31, a blow head 32, an air lifting cylinder 33, an intake / exhaust pipe 34, and a sand feeding pipe 35 for feeding coated sand. I have it. The coated sand is sand particles coated with a curing resin, and the average particle size thereof can be appropriately selected. For example, the AFS particle size index can be 40 to 80.

The blow head 32 has a hollow chamber in which the coated sand is accommodated. The blow head 32 is mounted on the tip of the cylinder rod 33i of the lifting cylinder 33. When the coated sand is blown, the three-way valve 31 is opened. As a result, compressed air is sent from the blow tank 30 to the blow head 32. When the coated sand blowing is completed, the three-way valve 31 is closed.

As shown in FIG. 3, a baffle plate 36 is arranged opposite to the through hole 32n on the bottom side of the blow head 32. Further, at a position facing the baffle plate 36 and the through hole 32n,
A rubber blow nozzle 37 having a relatively thick cylindrical shape
Is held on the blow head 32 by the holder 38. Specifically, with the collar portion 37 c of the blow nozzle 37 being pressed against the recess 38 c of the holder 38, the holder 38
Is screwed to the blow head 32, whereby the blow nozzle 37 is held by the blow head 32. The nozzle hole 37e of the blow nozzle 37 is partitioned by rubber. On the tip surface of the blow nozzle 37, a flat plate-shaped protection plate 39 having heat resistance is held by vulcanization adhesion or the like. The protective plate 39 has a through hole 39n. Although the protective plate 39 is made of metal, it may be made of ceramics (for example, alumina, silicon nitride, silicon carbide, etc.) in order to enhance the heat insulating property and protect the blow nozzle 37.

When the elevating cylinder 33 operates and the cylinder rod 33i descends, the blow head 32 descends and the blow nozzle 37 causes the blow opening 19x of the mold 19.
And the protective plate 39 is pressure-bonded to the mounting surface 19i having a bottom shape of the blow opening 19x. As shown in FIG. 2, a fixed base 5 is installed adjacent to the base 1. The fixed base 5 serves as a mold splitting or core removal position. A second rail 54 is arranged on the rail surface 5 f of the fixed base 5 in parallel with the rail 14.

The following usage patterns will be described. Mold temperature 20
A mold 19 of about 0 to 250 ° C. (may be brought close to the mold temperature of the mold 19 in the curing step, or may be substantially isothermal to the mold temperature of the mold 19 in the curing step) It is held by the mold carriage 2. As shown in FIG. 2, the mold carriage 2 is mounted on the second rail 54 of the fixed base 5. By operating the drive cylinder, the die carriage 2 is moved from the second rail 54 to the rail 14 and is moved from the fixed base 5 to the base 1. Next, the clamp 16
Is operated to press the mold 19 with the clamp 16. Next, the elevating cylinder 33 operates, the cylinder rod 33i descends, and the blow head 32 descends in the arrow Y1 direction. As a result, the blow nozzle 37 is fitted into the blow opening 19x, and the protective plate 39 of the blow nozzle 37 is pressed against the bottom surface-shaped mounting surface 19i of the blow opening 19x of the mold 19.
At this time, even if a shock or the like occurs, the shock or the like can be absorbed by the elastic deformation of the blow nozzle 37 made of rubber.

Next, blow the first coated sand
To do. That is, by operating the blowing device 3,
Compressed air sent from trachea 34 (pressure 2-10 kg /
cm ²) Together with the sand feeding pipe 35 from the coated sand
Is fed to the blow opening 19x. This is coated
The sand is filled almost completely in the cavity C of the mold 19.
Be done. After filling, the blowing device 3 is stopped. Such a first
When the first coated sand was blown, the shaker 12
Although not activated, it may be activated in some cases.

Next, the vibration exciter 12 is operated to vibrate the mold 19 three-dimensionally. The conditions such as the frequency and the amplitude can be appropriately selected, but the frequency can be 30 to 5000 Hz, for example. The amplitude is, for example, 0.3 to at the position of the split mold 19a.
It can be 20 mm. At this time, the base 1 can swing and vibrate favorably via the spring 10. As a result, the coated sand loaded in the cavity C of the mold 19 sinks, so that the coated sand loaded in the cavity C is densified and a cavity is formed above the cavity C. Although the impact or the like when the mold 19 vibrates as described above may be directly transmitted to the blow head 32, the impact or the like can be absorbed by the elastic deformation of the blow nozzle 37 made of rubber. Moreover, since the blow nozzle 37 is fitted in the concave blow opening 19x, the blow nozzle 37 can be prevented from coming off.

Next, the second blowing of the coated sand is performed. That is, the blower 3 is operated again while the vibrator 12 is operated to vibrate the mold 19. This allows
Along with the compressed air sent from the intake / exhaust pipe 34, the coated sand is sent from the sand supply pipe 35 to the blow opening 19x. As a result, the coated sand is filled in the cavity above the cavity C of the mold 19 in a substantially full state.

As described above, the impact or the like when the mold 19 vibrates may be directly transmitted to the blow head 32.
Similar to the above, this impact can be absorbed by the elastic deformation of the blow nozzle 37 made of rubber. The number of times the coated sand is blown can be appropriately selected. Therefore, if necessary, the third or fourth coated sand may be blown.

Next, the elevating cylinder 33 moves backward, the cylinder rod 33i rises, and the blow head 32 rises. Accordingly, the blow nozzle 37 causes the blow opening 19 of the mold 19 to move.
The protective plate 39 of the blow nozzle 37 is removed from the blow opening 19x while being removed from the blow opening 19x. Next, the clamp 16 is released. Next, by operating the drive cylinder, the mold carriage 2 on the rail 14 is moved along the rail 14 and the second rail 54, and is transferred to the fixed base 5. And mold 1
The split molds 19a and 19b of 9 are divided to take out the shell core. The shell core is highly densified and is substantially in a solid state.

A curing step is carried out before taking out the shell core. That is, the amount of heat generated by the heater built in the mold 19 is increased to heat the mold 19 to a higher temperature (generally 300 to 350 ° C.) and sufficiently harden deep inside the shell core. . The shell core thus produced is coated with a coating film. Then, the shell core is placed in a die casting mold casting cavity. In that state, a molten aluminum alloy (generally about 740 to 800 ° C.) is cast under high pressure in a die-casting type casting cavity. The pressure at this time is as high as 200 to 1000 kg / cm ² . Even at such a high pressure, the shell core has a high density and high strength, so the shell core can sufficiently withstand the casting pressure,
The deformation and damage of the shell core are suppressed. After the molten metal is solidified, the die casting mold is released, and the die casting product is taken out.

A test was conducted to examine the deformation of the shell core.
In this test, using the shell core molded in this example,
With the shell core placed in the die-casting type casting cavity, high-pressure casting (350 kg / cm ² ) of molten aluminum alloy was performed in the casting cavity to remove the shell core from the solidified die-casting product. It was carried out by measuring the dimensions of the shell core corresponding region in the cast product. Further, as a comparative example, a shell core produced only by blow blowing and without making the mold 19 vibrate was similarly tested. The test results are shown in FIG. As shown in FIG. 4, when the target value of the dimension is 7.7 mm, the dimension is 7.2 mm when the shell core of this example is used, and when the shell core of the comparative example is used. The dimension was 9.5 mm, which was considerably larger than the target value. It is speculated that this is because the shell core of the comparative example lost the casting pressure and the deformation of the shell core was large.

As described above, according to this embodiment, since the mold 19 is vibrated when the coated sand is loaded into the cavity C of the mold 19, a high-density and high-strength shell core can be obtained. it can. Therefore, even if the molded shell core is applied to high-pressure casting, it is easy to avoid deformation and damage of the shell core. Further, in this embodiment, since the blow nozzle 37 is made of rubber as a base material, it is possible to reduce or avoid the transmission of the vibration of the mold 19 to the blow head 32, thereby improving the protection of the blow head 32. . Further, since the inner wall surface 37k of the nozzle hole 37e of the blow nozzle 37 is partitioned by rubber, it is possible to expect deformation of the inner wall surface 37k itself when vibrating the mold 19. In this way, the inner wall surface 3
If the 7k itself is deformed, it is advantageous to drop the coated sand or the like adhering to the inner wall surface 37k. Therefore, it is possible to reduce the amount of coated sand adhering to the inner wall surface 37k of the nozzle hole 37e of the blow nozzle 37.
It is advantageous to secure the opening area of 7e, and the blowing property from the nozzle hole 37e is secured.

Further, in this embodiment, since the tip surface of the blow nozzle 37 is equipped with a heat-resistant metal protective plate 39 facing the bottom surface 19i of the blow opening 19x of the die 19, the die is Even if the mold temperature of 19 is high, the rubber blow nozzle 37 can be protected from heat and abrasion, and the protection property of the rubber blow nozzle 37 can be improved. According to the curing process of the present embodiment, even a densified shell core can be sufficiently hardened deep inside the shell core. Therefore, a high-strength shell core can be obtained.

(Other Example) In the above example, the blow nozzle 3 is mounted on the mounting surface 19i of the blow concave opening 19x of the mold 19.
However, the present invention is not limited to this, and the protection plate 39 of the blow nozzle 37 may be attached to the flat mounting surface 19i of the mold 19 as shown in FIG.

In the above example, the inner diameter of the nozzle hole 37e substantially corresponds to the through holes 32n and 39n, but the present invention is not limited to this. In the above example, the present invention is applied to the molding of a shell core, but the present invention is not limited to this, and it can also be applied to a core molded with molding sand having a gas-curable binder.

[Brief description of drawings]

FIG. 1 is a front view showing a state before a blow head is attached to a mold on a base.

FIG. 2 is a side view showing a state before a blow head is attached to a die on a base together with a fixing base.

FIG. 3 is an enlarged sectional view showing a state immediately before a blow nozzle of a blow head is fitted into a blow opening of a mold.

FIG. 4 is a graph showing test results.

FIG. 5 is a sectional view according to another example showing a state immediately before the blow nozzle of the blow head is mounted on the mounting surface of the mold.

[Explanation of symbols]

In the drawing, 1 is a base, 10 is a spring, 12 is a vibrator, 19 is a mold, 19x is a blow opening, 2 is a mold carriage, 3 is a blowing device, 32 is a blow head, and 37 is a blow nozzle. .

Claims (4)

[Claims] 1. A base for holding a molding die having a blow opening opening to the outer surface and a core molding cavity communicating with the blow opening, and vibration is applied to the molding die held on the base. A shaker and a blow head having a blow nozzle attached to a blow opening of the molding die, and a blowing device for blowing molding sand from the blow nozzle of the blow head into a cavity of the molding die with compressed air. Core molding equipment. 2. The core molding apparatus according to claim 1, wherein the blow nozzle is made of rubber as a base material, and the nozzle hole of the blow nozzle is partitioned by the base material of rubber. 3. The core molding apparatus according to claim 1, wherein a heat-resistant protective plate facing the blow opening of the molding die is provided on the tip surface of the blow nozzle. 4. A base for holding a molding die having a blow opening open to the outer surface and a shell core molding cavity communicating with the blow opening, and vibration is applied to the molding die held on the base. And a blow head having a blow nozzle attached to a blow opening of the molding die, which is used to blow coated sand from the blow nozzle of the blow head into a cavity of the molding die by compressed air. The apparatus is used to load the coated sand into the cavity of the molding die by performing a blowing operation of blowing the coated sand into the cavity of the molding die and a vibrating operation for applying vibration to the molding die, A molding step of molding a shell core in a substantially solid state, and a curing step of hardening the shell core to a deep part in the molding step after the molding step Core making method characterized by carrying out sequentially.