JPH084870B2 - Ceramic shell manufacturing method - Google Patents

Description

TECHNICAL FIELD The present invention relates to a ceramic shell manufacturing method capable of enhancing strength and reducing the number of coatings and sandings.

[Problems to be Solved by Prior Art and Invention] As is well known, in an investment casting method capable of obtaining a casting product having a good casting surface and a complicated shape, a slurry and a refractory substance are formed by drying. Ceramic shells are widely used as molds.

In this ceramic shell, as disclosed in, for example, Japanese Patent Laid-Open No. 60-49832, a wax tree is formed by attaching a runner, a weir, etc. to a plurality of wax models having substantially the same shape as a casting product. It is obtained by coating the tree with the slurry, further sanding the refractory material, and drying it for a predetermined time to form a layer of the refractory material on the outer periphery of the wax tree, and then melting and removing the wax tree. is there.

The ceramic shell thus formed has relatively low strength, and a portion of the ceramic shell corresponding to a wax model may be broken when pouring molten metal into the ceramic shell. The layer of the refractory material is formed in multiple layers by repeating the sanding and sanding several times to ten times, and the strength of the ceramic shell is ensured by finishing the thickness to about 10 mm.

However, although the ceramic shell formed by this technique has a sufficient strength as a whole, since each layer of the refractory material forming the ceramic shell is relatively fragile, when the wax tree is melted and removed. Or, when the molten metal is poured into this ceramic shell, a part of the innermost layer of this ceramic shell may be damaged, and if casting is performed in the ceramic shell with this damage, the Defects occur.

Further, as described above, a step of drying for a predetermined time is required between the coating and sanding, and when the ceramic shell is manufactured by the line, the line has to be stopped for the predetermined time in the drying step. In addition to being complicated, it usually takes a considerable time to form the ceramic shell. In addition, a large amount of the relatively expensive slurry and refractory material is required between the coating and sanding steps, which are repeated several to ten times. For these reasons the ceramic shell,
And it is very difficult to reduce the cost of casting products using this ceramic shell.

When the casting product is relatively elongated, for example, as disclosed in Japanese Utility Model Publication No. 50-17473, after forming one or more layers of refractory material on the wax tree,
There is a technique for reinforcing the fragile portion of the ceramic shell by connecting, for example, the end portion of the ceramic shell to a wire.

However, even in this prior art, it is difficult to sufficiently reinforce the fragile portion of the ceramic shell, and there is a possibility that casting defects may occur in the cast product.

[Object of the Invention] The present invention has been made in view of the above circumstances, the strength is sufficiently ensured, and as a result, it is possible to relatively reduce the number of times of coating and sanding, and to reduce the cost. It is an object of the present invention to provide a ceramic shell manufacturing method.

[Means for Solving Problems] In the ceramic shell manufacturing method according to the present invention, a wax tree for joining a plurality of wax models is placed in a slurry tank for storing a slurry formed by mixing a refractory binder and refractory fine particles. The wax tree is soaked in a stucco tank in which a slurry film is coated around the wax tree, and a refractory material mixed with fibrous substances is kept in a floating state by blowing compressed air. The refractory material and the fibrous material are sanded around, and then the wax tree is dried by a drying device, and this process is repeated several times to alternately form a slurry layer and a refractory layer around the wax tree. It is characterized by

In the present invention, the slurry layer and the refractory material layer are alternately formed on the surface of the wax tree, and the fibrous material mixed in the refractory material layer holds the refractory material itself, and the fibrous material causes the slurry to be mixed. The adjacent layers of refractory material are fixed with the layers sandwiched therebetween.

Embodiments of the Invention Embodiments of the present invention will be described below with reference to the drawings.

1 to 3 relate to an embodiment of a ceramic shell according to the present invention. FIG. 1 is a sectional view of a wax tree in which a layer of refractory material is formed, and FIG. 2 is a portion A of FIG. FIG. 3 is an enlarged sectional view, and FIG. 3 is a schematic view of a process of forming a ceramic shell.

In these figures, reference numeral 1 is a wax wax tree, and 2
Is a slurry tank and 3 and 4 are stucco tanks.

In the wax tree 1, the wax model 1a has a sprue part.
A plurality of spigots 1c are formed around the runner 1c with a weir 1d.

The slurry tank 2 stores a predetermined slurry S containing a refractory binder made of colloidal silica, ethyl silicate or the like and fine refractory particles such as zircon, alumina or silica. When the tree 1 is dipped, the slurry S adheres to the outer periphery of the wax tree 1 to coat the slurry film 6.

Further, in the stucco tank 3, an alumina powder 7 such as alumina 7 which is an example of a refractory material and an average diameter of 2.5 to 200 μ,
A fibrous material 8 having a length of about 1 to 20 mm and made of ceramic such as alumina or silica, or stainless steel is put therein. Further, in the stucco tank 4, silica sand 9 such as No. 4 silica sand which is a refractory material, and the stucco tank 3
The same fibrous material 8 as that put in is put.

It is desirable that the fibrous material 8 has a large diameter for a refractory material having a large particle size and a thin diameter for a refractory material having a small particle size. Further, in order to make the mixed state of the fibrous material 8 and the refractory substance uniform, it is desirable to use the fibrous material 8 having substantially the same diameter and length.

A plurality of blowout holes 11 are formed in the bottom of the stucco tanks 3 and 4, and the other end of the blowout holes 11 is an air tank 12.
The compressed air 14 stored in the air tank 12 is ejected from the blowout holes 11 of the stucco tanks 3 and 4 through the blower path 13 so that the compressed air 14 stored in the air tank 12 is connected. ing. When the compressed air is ejected from the blowout hole 11, the alumina powder 7 and the fibrous material 8 contained in the stucco tank 3 or the silica sand 9 contained in the stucco tank 4 are discharged. The fibers 8 and the stucco tanks 3 and 4 are set to be in a floating state.

In addition, a directional control valve 15 and a flow rate control valve 16 at 2 ports and 2 positions, for example, are respectively installed in the air passage 13 to control the compressed air 14 ejected into the stucco tanks 3 and 4. Is configured.

As shown by the process line in FIG. 3, the wax tree 1
Is dipped into the slurry S in the slurry tank 2 to be drained, and is conveyed to the stucco tank 3 in which the alumina particles 7 and the fibrous material 8 are kept in a floating state and dried at the drying position 17. After the step, it is again immersed in the slurry S of the slurry tank, and this time the silica sand 9 and the fibrous material 8 are transported to the stucco tank 4 in a floating state and dried by the drying device 17. The steps are adapted to be repeated as needed.

Next, the operation of the embodiment having the above configuration will be described.
In the slurry S in which the wax tree 1 is stored in the slurry tank 2, the sprue part 1b formed in the wax tree 1 is formed.
It is immersed for a certain time leaving a part of
It is pulled up and drained. Then, the outer periphery of the wax tree 1 is uniformly coated with the slurry film 6 except for a part of the sprue part 1b not immersed in the slurry S.

Next, the wax tree 1 is conveyed to the stucco tank 3. In the stucco tank 3, compressed air 14 stored in an air tank 12 is ejected from a blowout hole 11 formed in the stucco tank 3 under the control of a direction control valve 15 and a flow rate control valve 16. Alumina granules 7 contained in the stucco tank 3 by the compressed air 14
And the fibrous material 8 are kept in a floating state, the alumina particles 7 and the fibrous material 8 are mixed almost uniformly,
Therefore, the alumina particles 7 and the fibrous material 8 are substantially evenly sanded on the slurry film 6 formed on the outer periphery of the wax tree 1 placed in the stucco tank 3. In this case, the alumina particles 7 are attached in a fixed state by the fiber-shaped material, and since the fiber-shaped material 8 is longer than the alumina particle 7, the fiber-shaped material 8 is One part is sandwiched between the alumina granules 7 and the other part is in a state of being projected from the sanded layer of the alumina granules.

Next, the wax tree 1 is taken out from the stucco tank 3 and conveyed to the drying device 17, where it is dried.
By drying the slurry film 6 coated on the outer periphery of the wax tree 1 and the alumina particles 7 and the fibrous material 8 sanded on the slurry film 6, the outer periphery of the wax tree 1 is filled with the refractory material. A layer is formed.

Then, the wax tree 1 is conveyed from the drying device 17 to the slurry tank 2 and is immersed again in the slurry S of the slurry tank 2 to form a layer of coating and sanding integrated on the outer periphery of the wax tree 1. After the new slurry film 6 is coated thereon, the wax tree 1 is transferred to the stucco tank 4. Since the slurry film 6 has a small thickness, the fibrous material 8 sanded in the stucco tank 3 in a state of protruding from the layer of the alumina granules 7 is the slurry film 6 newly coated. It is also in a state of being projected.

As in the above-mentioned stucco tank 3, compressed air 14 is blown out from the blow-out hole 11 in the stucco tank 4, and the silica sand 9 and the fibrous material 8 contained in the stucco tank 4 are compressed by the compressed air. Since it is in a floating state by 14, the silica sand 9 and the fibrous material 8 are sanded on the slurry layer 6 newly coated on the outer periphery of the wax tree 1 transported to the stucco tank 4.

In this case, the fibrous material 8 protruding from the second-layer slurry film 6 and the silica sand 9 adhere to each other, and
Since the fibrous material 8 in the stucco tank 4 adheres to the fibrous material 8 already adhered to the wax tree 1 as if it were entangled with each other, the silica sand 9 and the fibrous material 8 in the stucco tank 4 are different from each other. While being firmly adhered to the layer of refractory material already formed on the wax tree 1, each silica sand 9 is fixed by the fibrous material 8. Further, the silica sand 9 and the fibrous material 8 which are kept in a floating state are fixed.

Next, the wax tree 1 is conveyed to the drying device 17, and is dried by the drying device 17 so that the second refractory material layer is fixed to the first refractory material layer. It is formed. Since the first and second layers of the refractory material are held together by the fibrous material, peeling between the layers of the refractory material is completely prevented.

This wax tree 1 has a slurry tank 2 and a stucco tank 4
A layer of refractory material having a predetermined thickness is formed on the outer periphery of the wax tree 1 by reciprocating between it and the drying device 17 as many times as necessary, and the formed layer of refractory material is the ceramic shell. Used as.

In this embodiment, ceramics such as alumina and silica, stainless steel and the like have an average diameter of 2.5 to 200 μ and a length of 1 to 20 mm.
Although the fibrous substance 8 is formed by forming the fibrous substance to a certain degree, the fibrous substance 8 is limited to this constitution as long as it has a function of holding each refractory substance and between the refractory substance layers. Moreover, the refractory material used in this embodiment is not limited to the alumina granules 7 and silica sand 9.

[Effects of the Invention] As described above, according to the ceramic shell of the present invention, since each refractory material and the interlayer of the refractory material are firmly held by the fibrous material, the ceramic formed by the layer of the refractory material. This has the effect of increasing the strength of the shell and preventing peeling between the layers of the refractory materials.

In addition, since the layer of the refractory material can be reduced by the amount of the increased strength, the time and material consumed for forming the ceramic shell can be saved, and thus the ceramic shell and the ceramic shell can be manufactured. It has an effect that it is possible to realize the cost reduction of the cast product.

Further, in the stucco tank containing the refractory material and the fibrous material, since the refractory material and the fibrous material are kept in a floating state by blowing compressed air, the fibrous material with respect to the refractory material is The fibrous materials can be almost uniformly present in the sanded refractory material layer, so that the uniform strength of the ceramic shell is guaranteed.

[Brief description of drawings]

1 to 3 relate to an embodiment of the present invention. FIG. 1 is a sectional view of a wax tree in which a layer of refractory material is formed, and FIG. 2 is an enlarged sectional view of part A of FIG. FIG. 3 is a schematic view of the process of forming the ceramic shell. 1 ... Wax tree, 1a ... Wax model, 2 ... Slurry tank, 3,4 ... Stucco tank, 6 ... Slurry film, 7,8 ... Fiber material, 9 ... Refractory material, S ... Slurry.

Claims (1)

[Claims] 1. A wax tree for joining a plurality of wax models is dipped in a slurry tank for storing a slurry formed by mixing a refractory binder and refractory fine particles, and a slurry film is coated around the wax tree. Then, the wax tree is loosely inserted into a stucco tank in which the refractory material mixed with the fibrous material is kept in a floating state by blowing compressed air, and the refractory material and the fibrous material are sanded around the wax tree, After that, the wax tree is dried by a drying device, and this process is repeated several times to alternately form a slurry layer and a refractory material layer around the wax tree.