JPS583785B2 - Packing method and equipment for ceramic shell molds - Google Patents

Description

[Detailed Description of the Invention] When casting various castings using a ceramic shell mold, the present invention reliably backs up the mold, prevents "scallops" that are likely to occur especially when pouring, and impairs shape and dimensional accuracy. This invention relates to something that makes it easy to obtain flawless precision casting.

The use of ceramic shell molds as precision casting molds is well known, but due to the characteristics of shell molds, backup during casting is important.

Conventionally, it has been known to back up this type of shell mold by filling the area around the shell mold housed in a flask with dry sand, but even if the entire mold is supported by a layer of dry sand, It is difficult to prevent the mold from lifting due to the pressure of the molten metal (1), especially the "sticking" phenomenon in which the outer wall of the mold bulges outward, causing the mold to bulge. This phenomenon depends on the size of the cast product, but such "sticking" phenomenon can occur. This tends to cause changes in the shape, dimensions, and accuracy of the cast product, making it unsuitable for the purpose of precision casting.

The present invention utilizes ceramic shell mold backup using dry sand and reliably prevents the occurrence of the above-mentioned "stickiness" phenomenon, thereby making it possible to easily obtain cast products with excellent dimensional accuracy. This is achieved by supporting the ceramic shell mold in a fluidized bed sand layer, and by facing the mold outer wall so that a plate for preventing "stickiness" disposed in the sand layer can move toward and away from the outside wall of the mold. The main feature of this product is that it has a casting flask that houses a ceramic shell mold,
A fluidized bed sand layer is filled in the flask to surround the mold and into which pressurized air can be blown, and a fluidized bed sand layer is disposed in the fluidized bed sand layer so as to be able to approach and separate from the outside wall of the mold. It consists of a "sticky" prevention plate.

The present invention will be described in detail below with reference to the illustrated embodiments. Fig. 1 is a longitudinal sectional side view of an embodiment of the packing arrangement according to the invention;
The figure is a longitudinal sectional front view of the same, and in the same figure, 1 is the ceramic shell mold that is the object of the present invention, and 2 is the same mold 1.
It is a casting flask (metal frame, etc.) that houses and backs up the metal inside the mold and performs casting through in-mold pouring.As shown in the figure, it is box-shaped, and the bottom of the mold 1 is equipped with a ceramic filter. A ventilation bed 5 is provided, and pressurized air can be freely supplied into the flask 1 through the ventilation bed 5 by a pressurized air supply pipe 6 from the outside.

3. A "sticker" facing the outer wall 1a of the ceramic shell mold 1 and provided so as to be able to approach and separate from the outer wall 1a.
These are prevention plates, and in the illustrated example, they are provided as a pair of ceramic shell molds 1 for casting castings such as blades, corresponding to the outer walls 1a forming both sides of the blade, and are equipped with a forward and backward drive mechanism such as a cylinder mechanism. The respective plates 3, 3 are provided so as to be able to move toward and away from both sides of the outer wall 1a via 4, 4, 4a is the driving rod thereof, 8 is the rod connecting portion, and 9 is the pivot portion of the plate 3. However, the design of this is of course changed depending on the shape of the cast product, and the key point is that it can move toward and away from the outer wall 1a of the mold 1, and has a width that can cover almost the entire outer wall 1a of the mold 1. The plate 3 may have any shape, and 1b is the riser part of the mold 1.

7 shows a drum sand which backs up the mold 1 as a fluidized bed sand layer.

When backing up the ceramic shell mold 1 according to the present invention, first a predetermined amount of dry sand 7 is placed in the flask 1, and then pressurized through the ventilation bed 5 with the pressurized air supply pipe 6. By pumping air into the flask 1,
The dry sand 7 is suspended in the flask, and after this fluidized bed sand layer is formed, the “scallop” prevention plate 3,
3 is opened so as to be moved from side to side in FIG. The open plates 3, 3 are then charged in a buried manner within the layer and between the plates 3, 3, and then the open plates 3, 3 are reversed to a position as close as possible to the outer wall 1a of the mold 1 while being supplied with pressurized air. Then, the supply of pressurized air is stopped, and the casting is started by pouring the metal into the mold 1 as required, with the backup of the dry sand 7 and the outer wall 1a backed up by the "scallop" prevention plate 3.3. will be carried out.

The mold disassembly for taking out the product after casting can be easily done by opening the plates 3, 3 for preventing "scallops" which turn the backup dry sand 7 into a fluidized bed by supplying pressurized air. .

According to the present invention, by converting the backup layer of dry sand 7 into a fluidized bed sand layer by blowing pressurized air,
By opening and closing the shell mold 1, it is extremely easy to set and reset the shell mold 1 in the flask 2, and the pressure of the molten metal immediately after pouring ensures that the outer wall 1a of the mold 1 is stretched, that is, the "scallop" phenomenon is ensured. It is possible to prevent the distortion of the thickness and dimensional accuracy of the cast product due to the absence of mold tension, and it is possible to improve the shape and dimensional accuracy of the cast product such as a blade.

Furthermore, setting of the plates 3, 3 for preventing "chilling" is easy due to the fluidized bed sand layering, and when performing precision casting using a ceramic shell mold, setting and resetting of the mold 1 can be done quickly and labor-savingly.

For example, if its weight is 500Kg, c. p. When casting a c-blade using a conventional ceramic shell mold and a backup sand layer (without a fluidized bed structure), the
The tension caused by the "Harike" phenomenon ranges from 5 to 15 mm.
The work time for setting the mold and resetting the mold is 20 to 30 hours.
minutes x 2 people x 2 times, whereas when using the method of the present invention,
The mold tension due to the "hardening" phenomenon is limited to about 1 to 2 mm, and the work time for setting and resetting the mold is about 5 to 2 mm.
It has been confirmed that it is highly effective in preventing "breakouts" and improving productivity, as it only takes 10 minutes x 2 people x 2 times.

In practicing the present invention, it has been found that it is easy to heat the fluidized bed sand layer, and that if such temperature control is also used, the dimensional accuracy of the cast product can be further improved.

As described above, the present invention is used as a backup during casting of ceramic shell molds, unlike conventional methods, by forming the dry sand 7 into a fluidized bed sand layer and protecting the "scallop" prevention plate 3 from proximal to the outer wall surface of the mold. It is excellent in preventing the "scallop" phenomenon and making it extremely easy to install and remove the mold, and is excellent in improving product quality, productivity, and workability. ．． P. C
It is extremely suitable for use in casting blades, Kaplan runner blades, Francis runner blades, turbine blades, and large, heavy precision castings.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional side view of an example of an apparatus for carrying out the method of the present invention, and FIG. 2 is a longitudinal sectional front view of the same. 1...Ceramic shell mold, 2...
Casting flask, 3... Plate for preventing "scallops", 4.
...Advance/retreat drive mechanism, 5...Vent floor, 6.
... Pressurized air supply pipe, 7 ... Dry sand.

Claims (1)

[Scope of Claims] 1. A device for backing up a ceramic shell mold during casting, which supports the ceramic shell mold within a fluidized bed sand layer and includes a “stickiness” prevention plate disposed within the sand layer. A method for packing a ceramic shell mold, characterized in that the mold is backed up by facing the outer wall of the mold so as to be able to approach and separate from the mold. 2 A flask that accommodates a ceramic shell mold; A fluidized bed sand layer filled in the flask to surround the mold and into which pressurized air can be blown; A packing device for a ceramic shell mold, characterized by comprising a plate for preventing "scalloping" which is disposed facing the outer wall of the mold so as to be able to approach and move away from it.