JPS6321578B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a mold making method suitable for molding a main mold using molding sand containing a binder.
Conventionally, when molding sand containing a binder is used to mold the main mold, these molding sands have poor fluidity due to the binder, making it difficult to fill the molding sand to the desired state. However, especially in the case of large frames, it is difficult to implement equipment, and currently the sand compaction work is done manually, which causes various problems such as forcing workers to perform harsh labor. Ta.

In view of the above-mentioned circumstances, the present invention provides a mold making method for a main mold, which allows molding sand containing a binder to be quickly and reliably filled into every corner of the flask, thereby allowing accurate molding. The purpose is to provide the following. The configuration of the present invention will be explained below based on examples.

Reference numeral 1 denotes a model stand 5 having a decompression chamber 2 inside and a plurality of ventilation holes 4 at appropriate locations on an upper plate 3 communicating with the decompression chamber 2, and a model mounted on the upper surface of the model stand 5. A casting flask 7 is placed on the upper surface of the model plate 1, positioned by a fitting pin (not shown). Further, a pent plug 8 is embedded in the vent hole 4 to prevent casting sand from being discharged. The space defined by the model plate 1 and the flask 7 is filled with molding sand 9 containing a binder, and the upper surface of the molding sand 9 is filled with flexible A film sheet 10 is covered in an airtight manner.

The decompression chamber 2 is connected to a vacuum pump (not shown) via a suction pipe 11, and the inside of the flask 7 is made to have a negative pressure by the operation of the vacuum pump.

In addition, FIG. 3 shows a gas vent hole 13 in the side wall of the flask 12.
This is an embodiment in which air leakage occurs due to a gap between the model plate 5 and the flask 12, and the flask 12 is surrounded by a flexible It is covered with a film sheet 14.

In the structure configured in this way, the model plate 1
A casting flask 7 is placed on the upper surface, molding sand containing a binder is poured into the space defined by the model plate 1 and the flask 7, and the upper surface of the flask 7 is covered with a film sheet 10. In the covered state shown in FIG. 1, a vacuum pump (not shown) connected to the suction pipe 11 is operated,
When the inside of the flask 7 is made negative pressure through the decompression chamber 2, the vent hole 4, and the vent plug 8, the molding sand 9 inside the flask 7 is suctioned and compressed downward and passes through the film sheet 10 to a point in FIG. Suction pressure is squeezed to the state shown by the chain line. In addition, when stronger mold hardness is required, as shown in Figure 2, a small amount of molding sand 9 is put in, pressure squeezed with a film sheet 10, and then more molding sand is added on top of that and the above operation is repeated. By squeezing, stronger mold hardness can be obtained.

Further, as shown in FIG. 3, if a gas vent hole 13 is formed in the side wall of the flask 12 or if there is a gap between the flask 12 and the model plate 3, the film sheet 14 is inserted into the flask 12. When the outer periphery is covered and the inside of the flask 12 is made negative pressure, the molding sand 9 in the flask 12 is sucked and squeezed through the film sheet 14 as shown by the dashed line. A film sheet 14 is closely attached to the outer periphery of the flask 12 to prevent air leakage and effectively squeeze the molding sand 9 in the flask 12 by suction.

As described above, the present invention involves superimposing a casting flask on the upper surface of a model plate which is provided with a vacuum chamber inside and has a plurality of vent holes communicating with the vacuum chamber on the top surface, and by combining the casting flask with the model plate. Molding sand containing a binder is poured into the space defined by the flask, a flexible film sheet is airtightly covered over the top of the flask, and then a suction device connected to the vacuum chamber is activated. Then, the inside of the flask is made negative pressure through the ventilation hole, a negative pressure is applied to the molding sand in the flask, and the molding sand is squeezed by suction through the film sheet. Even when molding the main mold using molding sand containing binder, the molding sand will surely fill every corner of the flask and a good mold can be expected. It has a variety of effects, such as instantly filling the frame to a high degree and improving productivity.

[Brief explanation of the drawing]

Fig. 1 is a sectional view showing an embodiment of the present invention, Fig. 2 is a sectional view showing another embodiment of the invention, and Fig. 3 is a sectional view showing another embodiment of the invention.
The figure is a sectional view showing another embodiment of the present invention. 1: Model board, 2: Decompression chamber, 4: Ventilation hole, 7,1
2: Casting flask, 8: Vent plug, 9: Foundry sand, 1
0,14: Film sheet.

Claims (1)

[Claims] 1. A step of superimposing a casting flask on the upper surface of a model plate which is provided with a decompression chamber inside and has a plurality of vent holes communicating with the vacuum chamber on the upper surface, and a mold formed by the model plate and the flask. casting sand containing a binder into the space, and then covering the upper surface of the flask with a flexible film sheet in an airtight manner, and activating a suction device connected to the decompression chamber. A mold making method comprising the steps of creating negative pressure in the flask through the ventilation hole, exerting negative pressure on the molding sand in the flask, and squeezing the molding sand by suction through the film sheet. .