JPH06198390A - Method and device for molding - Google Patents

Abstract

PURPOSE:To provide molding method and its device by vacuum suction capable of producing a sound casting with low vibration, low noise and low equipment cost. CONSTITUTION:In the condition a molding flask 6 is placed on a pattern board 4 having a vent hole 4a fixed on a squeeze table 2, the process, which closes a stop valve arranged in a communicating hole 2c between a tight closure part 7, having as side surface the sliding surface between the squeeze table 2, and a base board 1 connected slidable therewith and the process, which widens the tight closure 7 by elevating the squeeze table 2 and traveling the squeeze table 2 against the base board 1 to make the inside vacuum, are arranged. Further, the process, which charges molding sand in a molding flask 6 and the process, which opens the stop valve 8 after charging molding sand or together with charging, sucks in air in the tight closure part 7 through the molding flask 6, vent hole 4a and sucks/fills molding sand together with the air, are included as well.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mold making method and apparatus, and more particularly, to a mold making method for increasing the packing density of the mold by sucking the molding sand put into the flask toward the model surface plate by vacuum. It relates to the device.

[0002]

2. Description of the Related Art In recent years, from the standpoint of environmental issues such as vibration and noise, the green mold making apparatus has replaced the conventional Jolt squeeze method, and first, the casting force in the casting frame is utilized by utilizing the impact force of compressed air. A method of increasing the packing density of sand and then finishing it by squeeze is being adopted.

The following is an example of such a mold making apparatus. That is, a space for compressed air filling is formed on the model surface plate, the casting frame placed on the model surface plate, and the molding sand that is placed on the molding frame in a stacked manner and filled in the casting frame. A cover member, a squeeze cylinder fixed to the upper surface of the cover member and having a squeeze plate extending up and down in the space, and a table forming an exhaust chamber by airtightly supporting the model surface plate from below. It is a mold making device.

In the above-mentioned molding apparatus, after filling the molding sand with the molding sand, the cover member is placed on the molding flask, and the compressed air is supplied from the surge tank into the space above the molding sand through the air supply valve. Supply shockingly. The compressed air passes through the gap between the sand particles while applying pressure to the filled molding sand particles, and is discharged from the vent hole provided in the model surface plate through the exhaust chamber. Then, the squeeze plate is lowered to squeeze the foundry sand from above.

Another example is as follows. Using a model surface plate similar to the above example, after filling the molding sand into the pressure tank, compressed air is introduced into this pressure tank to transfer the molding sand in the tank into the flask, and at the same time, it is provided separately. There is a method of decompressing the inside of the flask from below through the vent hole with a vacuum pump, suction-filling the molding sand toward the model surface plate, and then squeezing.

[0006]

However, the former type of mold making apparatus has the following problems. In this device, the compressed air stored in the surge tank is instantaneously and impactly introduced into the space formed by the cover member above the molding sand in the flask to increase the packing density of the molding sand. For this reason, it is necessary to shorten the pressurization time of the air in the flask and the cover member as much as possible, which makes the surge tank larger and the device for increasing the opening speed of the air supply valve larger and the valve structure complicated. Inevitability is unavoidable. In addition, the introduced compressed air is discharged to the outside from the vent hole through the exhaust chamber, which further increases the packing density of the foundry sand near the model surface plate, but the backside of the foundry sand added from above. Due to the impact force, the molding sand may cause a bridging phenomenon between the inner wall of the mold and the upper surface of the model or the upper surface between the models, resulting in poor filling. further,
Due to the excessive force acting on the model surface due to the shock wave of compressed air and the premature wear of the model surface, the model that was previously used cannot be used, and it is necessary to remanufacture the model in order to increase the strength and prevent wear. However, there is also a drawback that the unit price of casting is increased.

Further, the latter molding method has the following problems. First, the molding sand transferred from the pressure tank by compressed air has a directionality along the flow of air, and it is difficult to uniformly fill the molding sand with a complicated model shape, resulting in large variations in mold strength. And causes local wear on the model. Further, it is necessary to install a dedicated vacuum pump facility for depressurization, which causes an increase in facility cost and running cost, and troublesome maintenance due to wear of the pump due to mixing of molding sand into the vacuum pump.

[0008]

In order to solve the above-mentioned problems, the method of molding a mold according to the present invention is a method for molding a mold by sucking the molding sand put into the flask toward the model surface plate by vacuum. In a mold making method for increasing the packing density, the squeeze table and the squeeze table can be slidable while the casting frame is placed on a model surface plate having a vent hole that is fixed to the upper surface of the squeeze table and vertically penetrates. A step of closing an opening / closing valve provided in a communication hole between a closed portion formed with a sliding surface with an engaging base as a side surface and a vent hole of the model surface plate, and the squeeze table at a predetermined position. Up to the base to move the squeeze table with respect to the base to widen the sealed portion to create a vacuum inside, and a step of charging molding sand into the flask. After the casting sand is charged or in parallel with the charging, the on-off valve is opened and air is sucked into the hermetically sealed part through the casting frame and the vent hole. And a process of sucking and filling toward the upper surface of the mold.

In the mold making apparatus according to the present invention, a squeeze table slidably engaged with a base and supported by a squeeze cylinder so as to be able to move up and down, and a squeeze table fixed on the upper surface of the squeeze table to vertically penetrate therethrough. In a mold making apparatus including a model surface plate having a vent hole and a casting frame placed on the upper surface of the model surface plate, the squeeze table is hermetically sealed with a guide portion integrally set up on the base. Has a piston part that can be slid up and down by being fitted to the end face of the piston part and the end face of the guide part, and the sliding surface of the piston part and the guide part is the side face The squeeze table is provided with a communication hole that communicates between the vent hole and the sealed portion, and the communication hole is provided with an opening / closing valve. After raising the quiz table to a predetermined position by the squeeze cylinder and moving the piston portion with respect to the guide portion, the sealed portion is expanded to make the inside of the vacuum state, and then casting sand is put into the flask. Or, in parallel with charging, the on-off valve is opened and air is sucked into the hermetically sealed part through the flask and the vent hole, and the molding sand that has been charged together with this air is directed toward the upper surface of the model surface plate. A mold making apparatus characterized by suction and filling.

The mold molded by the mold molding method or apparatus of the present invention can be finished by squeezing from at least one of the upper direction and the lower direction by a known method.

[0011]

The function and effect of the mold making method and apparatus according to the present invention are, as described above, formed by using the model surface plate having the vent hole and the sliding surface between the squeeze table and the base as side surfaces. This is the result of the connection between the closed portion and the on-off valve that is provided in the communication hole of the squeeze table and that connects or disconnects the vent hole and the closed portion. That is, by raising the squeeze table with the on-off valve closed, the sealed part is expanded to make the inside a vacuum, and then the molding sand is charged into the flask, or the on-off valve is opened in parallel with the charging. Air is sucked into the sealed portion through the casting frame and the vent hole, and the molding sand is sucked and filled with the air toward the upper surface of the model surface plate. In this case, since the vent hole and the closed portion are located very close to each other above and below the on-off valve, pressure loss and suction time required when the on-off valve is opened are small, and the molding sand in the casting frame can be efficiently and quickly blown at once. It can be filled by suction. Therefore, there is no risk of bridging of foundry sand due to impact force from the back side,
In addition, no special consideration is required for strengthening and wearing the model surface plate. Moreover, it is not necessary to install equipment such as a large surge tank and a vacuum pump.

[0012]

Embodiment An embodiment of the present invention will be described below with reference to FIG. A mold making apparatus according to the present invention is a base 1 having a guide portion 1a that is integrally erected, and a bottomed cylindrical type that is airtightly fitted to an outer surface of the guide portion 1a and is vertically slidable. A squeeze table 2 having a piston portion 2a and a table portion 2b integrally formed on the upper end of the piston portion, and a base 1
A plurality of squeeze cylinders 3 fixed to the squeeze table 2 to support the squeeze table 2 so that the squeeze table 2 can be moved up and down
A model surface plate 4 which is fixed to the upper surface of the model and has a vent hole 4a penetrating vertically and which opens downward, and a caster which is supported immediately above the model surface plate 4 and which is mounted on a pedestal (not shown). And a frame 6. The bottom surface of the piston portion 2a of the squeeze table 2 serves as the upper end surface, the upper end surface of the guide portion 1a of the base 1 serves as the lower end surface, and the piston portion 2
A hermetically sealed portion 7 whose side surface is the inner peripheral surface of the sliding portion a of the a with respect to the guide portion 1 a is formed between the base 1 and the squeeze table 2. A communication hole 2c that vertically penetrates the table portion 2b of the squeeze table 2 and connects the closed portion 7 and the opening of the model surface plate is formed. The table portion 2 is provided at the upper end of the communication hole.
An on-off valve 8 that can be seated airtight on a valve seat 2d provided on the upper surface of b
This on-off valve can be moved up and down by a piston of a cylinder 8a fixed to the table portion 2b. The guide portion 1a of the base 1 is provided with a through hole 1b for communicating the closed portion 7 with the outside air, and the switching valve 9 connects and disconnects the closed portion 7 with the outside air.

The method of making a mold by the mold making apparatus of the present invention will be described below. FIG. 1 shows a state before the start of molding work, in which the on-off valve 8 is pulled down by a cylinder 8a and seated on a valve seat 2d provided on the squeeze table 2 in an airtight manner. The switching valve 9 is closed and the sealing portion 7 is closed.
Between the outside and the outside air. FIG. 2A shows a state in which the squeeze table 2 is lifted and stopped by the squeeze cylinder 3, the casting flask 6 is lifted by the model surface plate 4, and this is separated from the roller 5. In this case, the rise of the piston portion 2a of the squeeze table 2 expands the volume of the hermetically sealed portion 7 that is shielded from the outside air and becomes a vacuum state. FIG. 2B shows a state in which the molding sand 10 is charged into the molding flask 6 by a molding sand charging device (not shown). A step of sucking into the sealing portion 7 through the vent hole 4a provided in the casting frame 6 and the model surface plate 4 and, together with this air, sucking in the foundry sand 10 toward the upper surface of the model surface plate 4 for filling. Indicates. FIG. 2C shows that after the suction and filling of the molding sand 10 are completed, the squeeze head 11 is carried directly above the casting frame 6 by a moving device (not shown), and the squeeze table 2 is further raised by the squeeze cylinder 3 to raise the casting. Sand 10
A step of squeezing from below by a known method will be described.
FIG. 2D shows that the squeeze table 2, the model surface plate 4, and the casting frame 6 are lowered by lowering the squeeze cylinder 3, and the lower surface of the casting frame 6 is abutted against and supported by the roller 5 during the lowering.
The process in which die cutting is performed is shown. After the die cutting, the squeeze table 2 and the model surface plate 4 are lowered to a predetermined position to complete the molding process. The switching valve 9 opens simultaneously with the descent of the squeeze table 2 after the squeeze is completed, and prevents pressure increase in the sealed portion 7.

As is clear from the above description, in the mold making apparatus of the present invention, the squeeze table 2 is provided with the communication hole 2c for connecting the vent hole 4a of the model surface plate 4 and the sealing portion 7 to each other. An opening / closing valve 8 is provided in the hole. Therefore, since the vent hole 4a and the closed portion 7 are located very close to each other, the pressure loss and the time required for suction when the opening / closing valve 8 is opened are small, and the molding sand 10 in the casting frame 6 is small.
Can be efficiently sucked and filled all at once. As described above, in the method and apparatus of the present invention, since the molding sand 10 is directly sucked from the surface side of the model surface plate 4, the bridge of the molding sand generated on the upper surface of the model by the impact force of the air from the back side. No phenomenon occurs, and no special consideration is required for measures such as strengthening the model surface plate against excessive force acting on the model surface and anti-wear measures. In addition, since equipment such as a large surge tank for giving a shock wave of air and a vacuum pump for sucking foundry sand is not required, the equipment cost can be kept low.

3 and 4 show a modification of the mold making apparatus according to the present invention. In FIG. 3, the guide portion 1a of the base 1 of the above-described embodiment has a bottomed cylindrical shape to form an outer cylinder portion 1c, which is slidably and airtightly fitted to the outer peripheral surface of the piston portion 2a of the squeeze table 2. Further, the piston portion 2a of the squeeze table 2 has a bottomed cylindrical shape, and the cylinder 1d integrally provided on the base 1 inside the outer cylinder portion 1c of the base 1 and the inner peripheral surface of the piston portion 2a are airtight. It is equipped with a partition piston 1e which is fitted and slidable up and down by the cylinder 1d. By doing so, the volume of the hermetically sealed portion 7 is partitioned by the partition piston 1e.
It is possible to further increase the suction effect by lowering. Further, in FIG. 4, the guide portion 1a of the base 1 has a bottomed cylindrical shape to form an outer cylinder portion 1c, which is slidably and airtightly fitted on the outer peripheral surface of the piston portion 2a of the squeeze table 2. The closed portion 7'is formed such that the lower end surface of the piston portion 2a is the upper end surface and the bottom surface of the outer tubular portion 1c is the lower end surface, and is communicated with the communication hole 2c by the through hole 2e. If the diameter of the through hole 2e is increased, the increase in resistance to air due to the provision of the through hole 2e can be ignored. Other configurations, operations and effects of these modified examples are similar to those of the first embodiment, and detailed description thereof will be omitted.

[Brief description of drawings]

FIG. 1 is a schematic vertical sectional view of a mold making apparatus according to the present invention in an assembled state.

FIG. 2 is a schematic vertical cross-sectional view of an apparatus showing each step of a molding method by the mold molding apparatus of FIG.

FIG. 3 is a schematic vertical sectional view of a modified example of the mold making apparatus according to the present invention in an assembled state.

FIG. 4 is a schematic vertical sectional view of another modified example of the mold making apparatus according to the present invention in an assembled state.

[Explanation of symbols]

 1 base 2 squeeze table 3 squeeze cylinder 4 model surface plate 6 casting frame 7 sealing part 8 on-off valve 10 casting sand

Claims (2)

[Claims] 1. In a mold making method for increasing the packing density of a mold by sucking foundry sand put into a flask toward a model surface plate by vacuum, a vent fixed vertically to the upper surface of a squeeze table and penetrating vertically. In a state in which a casting frame is placed on a model surface plate having holes, a sealing portion formed with a sliding surface between the squeeze table and a base slidably engaged with the squeeze table as a side surface and the model. Closing the on-off valve provided in the communication hole with the vent hole of the surface plate; and raising the squeeze table to a predetermined position to move the squeeze table with respect to the base to close the sealing portion. A step of expanding this to make a vacuum inside it, a step of charging molding sand into the molding flask, and after charging the molding sand, or in parallel with charging, opening the on-off valve to blow air into the molding flask and A method of molding a mold, comprising a step of sucking through the vent hole into the hermetically sealed portion, and sucking and filling the cast sand with the air toward the upper surface of the model surface plate. 2. A squeeze table slidably engaged with a base and supported by a squeeze cylinder so as to be able to move up and down, and a model surface plate fixed to the upper surface of the squeeze table and having a vent hole vertically extending therethrough. In a mold making apparatus provided with a casting frame placed on the upper surface of the model surface plate, the squeeze table is fitted in an airtight manner with a guide portion integrally set up on the base and slides up and down. A movable piston part, and an end face of the piston part and an end face of the guide part, respectively, and end faces of the piston part and the sliding part of the guide part. The squeeze table is provided with a communication hole that communicates between the vent hole and the sealed portion, and an opening / closing valve is provided in the communication hole. And moving the piston part with respect to the guide part to widen the sealed part to create a vacuum inside the mold, and after charging the molding sand into the molding frame, or in parallel with the charging. Then, the on-off valve is opened and air is sucked into the closed portion through the casting frame and the vent hole, and the casting sand that has been input together with this air is sucked and filled toward the upper surface of the model surface plate. Mold making apparatus characterized by: