JPH09108775A - Method and device for filling sand in lost foam pattern casing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a method and device for filling sand by which molding sand is moved/filled in an unfilled part of a narrow space part and upward facing space part and can fill well even in the case of a complicated lost foam pattern. SOLUTION: A sand filling method, which buries a lost foam pattern for lost foam pattern casting in molding sand, consists of a process to position a lost foam pattern 2 in a molding flask box 1 and to charge a molding sand 3, a process to evacuate the inside of the molding flask 1 after an upper opening of the molding flask box 1 is closed by a molding flask box cover 4 and a process to introduce air from a topside of the molding sand 3 charged at one time or plural times.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sand filling method and apparatus for burying a lost model for casting a lost model in foundry sand.

[0002]

2. Description of the Related Art Conventionally, in order to simplify molding work, omit cores or reduce casting burrs, it is necessary to bury a disappeared model such as expanded polystyrene in molding sand and take out the disappeared model from the mold sand. Disappearance model casting is widely used in which casting is performed by pouring molten metal as it is and replacing the disappearance model with the molten metal. In addition, vanishing model casting is also used in which the vanishing model is depressurized at the time of pouring to remove gas generated during burning of the vanishing model (for example, Japanese Patent Laid-Open No. Sho 48/1978)
7822). In this vanishing model casting, various sand filling methods have been proposed, such as a method using vibration (Japanese Patent Laid-Open No. 97841/1982) in order to bring the foundry sand into close contact with the periphery of the vanishing model.

However, the conventional method is not sufficient to bring the foundry sand into close contact with the disappearing model having a complicated shape. In particular, in the production of single or large items such as press dies, since the vanishing model shape has a complicated rib structure, casting sand moves to the narrow space of the vanishing model or to the unfilled part of the upward space. Difficult to do and sand filling was not enough. Therefore, with respect to the casting product obtained by pouring the molten metal, the dimensional accuracy may be low, or a casting surface defect such as seizure may occur.

[0004]

SUMMARY OF THE INVENTION The object of the present invention is to solve these problems. Even if the vanishing model has a complicated shape, the foundry sand is used in a narrow space of the vanishing model or in an unfilled portion of the upward space. It is an object of the present invention to provide a sand filling method and device which are mobile-filled and well filled.

[0005]

In order to achieve the above object, the method of filling sand in vanishing model casting according to the present invention comprises a step of positioning the vanishing model in a casting box and introducing casting sand, and the casting frame. The method comprises: a step of decompressing the inside of the flask after closing the upper opening of the box with a flask cover; and a step of introducing air once or a plurality of times from above the input molding sand. And Further, in order to achieve the above object, the sand filling device in the vanishing model casting in the present invention is a casting frame box for positioning the vanishing model and receiving casting sand, and closing the upper opening of the casting frame box. Frame box lid, casting box box lid moving means for moving the casting box box cover, pressure reducing means for depressurizing the closed casting box box by a vacuum pump, and communicating with the closed casting box box And an atmosphere introducing means provided with an atmosphere introducing valve.

[0006]

Embodiment 1 of the present invention will be described in detail below with reference to the drawings. FIG. 1 is a schematic view of a sand filling device in vanishing model casting. After the vanishing model 2 is positioned in the flask 1, the molding sand 3 is put into the flask 1, and then the flask box lid 4 is used. 1 shows the closed state.

A casting frame box lid 4 is movably provided on the upper portion of the casting frame box 1. By the operation of an elevating cylinder as the casting box box lid moving means 5, the casting box box lid 4 is moved. The mold box 1 can be closed by the mold box lid 4. Further, a pressure reducing means is provided in the flask cover 4, and one end of the pressure reducing means can communicate with the unsanded portion of the upper part of the flask 1 and the other end is connected via a vacuum valve 6. And communicates with the vacuum pump 7. The vacuum valve 6
With this operation, the inside of the flask 1 can be depressurized to 2 to 100 Torr. Further, an atmosphere introducing means is integrally formed at another position of the flask cover 4, and the atmosphere introducing means is an atmosphere introducing valve 8
And the atmosphere can be introduced into the flask 1.

The operation of the sand filling device constructed as above will be described below. In FIG. 1, after a suitable amount of casting sand 3 is put into the flask 1 by sand feeding means (not shown), the vanishing model 2 is positioned in the flask 1 and the casting sand 3 is additionally fed. The casting of the molding sand 3 may be performed after the vanishing model 2 is positioned. Then, the operation of the casting box lid moving means 5 closes the upper part of the casting box 1 by the casting box lid 4, and then the pressure in the casting box 1 is reduced to 2 to 100 Torr.

After that, the atmosphere is rapidly introduced from the atmosphere introducing means provided in the flask 4 lid at the upper part of the flask 1. This atmosphere instantaneously acts as impact pressure on the upper portion of the foundry sand.
The pressure rising rate is preferably 50-600 kg / cm ² / sec. More preferably, 200-400 kg / cm
² / sec is preferred. Due to this impact pressure, the foundry sand moves to a narrow space of the model or an unfilled portion of the upward space. If the filling is not completed by the above operation once, the depressurizing step and the air introducing step are repeated a plurality of times, or the molding sand is divided into a plurality of feeding amounts and the sand feeding step, the depressurizing step, and the air introducing step are performed a plurality of times. Can be repeated. In addition, when sand is divided into small parts, it is effective for large objects and tall vanishing models. After the casting sand box 3 is completely filled with the molding sand 3 and the molding is completed, pouring is performed to replace the disappeared model with the molten metal. After the pouring is completed, it is cooled and the casting and the casting sand 3 are separated. The above steps are repeated.

As the foundry sand 3 used in the present invention, silica sand containing no binder is generally suitable. However, molding sand 3 having a slight viscosity may be used.

The disappearance model 2 used in the present invention may be made of any material as long as it is a normally used material such as expanded polystyrene or PMMA.

In the first embodiment of the present invention, the decompression means communicates with the molding box lid 4 by the upper part of the molding box 1. However, in another embodiment of the present invention, the decompression means and the molding box are connected. The communication of 1 is not limited to the case of passing through the upper portion of the flask 1. still,
In the first embodiment of the present invention, since the interior of the flask 1 can be decompressed by the pressure reducing means integrated with the flask cover 4 without directly connecting the pressure reducing means to the flask 1. This has the effect of simplifying the structure of the flask 1.

Further, in vanishing model casting in which the pressure is reduced during pouring, if the pressure reducing means used during pouring is also used during sand filling, it is necessary to depressurize from the flask cover 4 above the flask 1. There is no.

In the first embodiment of the present invention, the atmosphere introducing means is provided with an atmosphere introducing valve 8 and the molding box lid 4 is provided.
However, the mounting position, shape, and size of the atmosphere introducing valve 8 used for the atmosphere introducing means are not limited to those in this embodiment. Further, in the first embodiment of the present invention, the atmosphere introduction valve 8 is used as the atmosphere introduction means, but compressed air may be introduced instead of atmospheric pressure. Maximum pressure of compressed air is 10kg / cm ²
Is suitable, and compressed air from factory piping can be used.

Further, in the first embodiment of the present invention,
The flask cover 4 is configured to be movable up and down by the lifting cylinder which is the flask cover moving means 5, but the container cover 4 can be moved left and right, rotated, or vertically moved. You may close it.

Further, in the first embodiment of the present invention, the pressure-reducing means and the atmosphere introducing means are integrally formed on the molding box lid 4, and the lifting and lowering cylinders as the casting box lid moving means 5 integrally move up and down. Although it is possible, the flask cover 4, the pressure reducing means, and the atmosphere introducing means can be separately configured. Further, at least one of them may be separately configured. For example, when the flask cover 4 is separately configured, the atmosphere introducing means may be provided on the upper side surface of the flask 1.

Further, in the first embodiment of the present invention, the casting frame box 1 is hermetically sealed from above the casting frame box 1 by the elevating cylinder which is the casting frame box lid moving means 5. May be placed on an elevating table provided so as to be relatively connected to or separated from the flask cover 4.

The present invention is particularly effective for the production of a single product or a large product such as a press die, since the casting sand moves to the narrow space of the vanishing model or the unfilled portion of the upward space.

As is apparent from the above description, the present invention is a sand filling method for burying a lost model in casting sand in the lost model casting, in which the lost model is positioned in the flask and the foundry sand is removed. The step of introducing, the step of decompressing the inside of the flask by closing the flask with the flask lid by means of the flask box moving means, and the air once or more times from above the cast sand Since the step of introducing is provided, even if the lost model has a complicated shape, the molding sand moves to a narrow space of the model or to an unfilled part of the upward space, so that the sand filling becomes good. Therefore, a good casting can be manufactured. As described above, the effect of the present invention on the industry is remarkable.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing an embodiment of the present invention.

[Explanation of symbols]

 1 Casting Frame Box 2 Disappearance Model 3 Foundry Sand 4 Casting Frame Box Lid 5 Casting Box Lid Moving Means 6 Vacuum Valve 7 Vacuum Pump 8 Atmosphere Introduction Valve

Claims (7)

[Claims] 1. A sand filling method for burying a disappearing model for casting a disappearing model in foundry sand, the steps of positioning the disappearing model 2 in a casting frame box 1 and charging the foundry sand 3, and the casting frame. The method comprises the steps of closing the upper opening of the box 1 with a flask cover 4 and then depressurizing the inside of the flask 1, and introducing air once or a plurality of times from above the cast molding sand 3. A method for filling sand in vanishing model casting, comprising: 2. The sand filling method in vanishing model casting according to claim 1, wherein the introduced air is at atmospheric pressure. 3. The sand filling method in vanishing model casting according to claim 1, wherein the introduced air is pressurized air. 4. A step of positioning the vanishing model 2 in the casting box 1 and subdividing the casting sand 3 into a plurality of loading amounts into the casting box 1, and an upper portion of the casting box 1. After the step of decompressing the inside of the flask 1 after closing the opening with the flask cover 4 and the step of introducing air once or a plurality of times from above the cast molding sand 3, the subdivided residue Of the molding sand 3 into the flask 1 and after closing the upper opening of the flask 1 with the lid 4 of the flask 1
Step 1 of depressurizing the inside and from above the casting sand 3
The sand filling method in vanishing model casting according to any one of claims 1 to 3, wherein the step of introducing the air once or a plurality of times is performed at least once. 5. A sand filling device for burying a disappearing model for casting a disappearing model in foundry sand, which comprises a casting frame box 1 for positioning the vanishing model 2 and receiving a casting sand 3 therein, and the casting frame box 1 A mold box cover 4 for closing the upper opening of the mold, a mold box cover moving means 5 for moving the mold box cover 4, and a decompression means for decompressing the closed mold box box 1 by a vacuum pump 7. An atmosphere introducing means provided in communication with the closed flask 1 and having an atmosphere introducing valve 8, and a sand filling device in vanishing model casting. 6. The sand filling device for vanishing model casting according to claim 5, wherein the flask cover 4 and the atmosphere introducing means are integrally formed. 7. The sand filling device for vanishing model casting according to any one of claims 5 to 6, wherein the flask cover 4 and the pressure reducing means are integrally formed. .