JPH06190810A - Mold for slip casting provided with a non-water absorbing part and slip casting molding method using the same - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a method for producing a large-sized, thick-walled and complex-shaped ceramic molded body without causing a shrinkage cavity or the like. [Structure] A slip 6 is injected into a cavity 4 of a slip casting mold 1 in which a non-water-absorbing member 5 for delaying the inking of slips is disposed in an inlet region 4b of the mold cavity, and a slip 6 is injected into the ceramic molded part. A slip-casting molding method in which the non-carved slip inside the molded body is not substantially blocked from the slip in the inlet region 4b by the carburized layer until the carburization of the slip in 4a is completed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a slip casting molding method and a slip casting molding die used therefor, and more particularly to a slip casting molding method for producing a large-sized, thick-walled and ceramic-shaped molded body without a shrinkage cavity or the like. , And a slip casting mold used therefor.

[0002]

2. Description of the Related Art A typical method for manufacturing a ceramic molded body is a slip casting molding method. In this slip casting molding method, a mold made of a material having a water absorption property such as gypsum is usually used, and moisture is absorbed from the slip (suspension of ceramic powder) injected into the cavity of the mold to solidify the slip. It is done by doing. The obtained molded body is degreased and then fired to obtain a final ceramic member. This method is generally suitable for producing a large-sized and relatively thin-walled molded product or a molded product having a complicated shape.

This slip casting molding method is
Since it is possible to relatively easily produce a homogenous formed body, an attempt has been made to apply it to the production of a formed body (green) for a ceramic product that requires high shape and dimension accuracy, for example, a GT engine rotor. There is.

However, according to the conventional slip casting molding method, it is difficult to manufacture a large-sized thick ceramic molded body to be used or a large-sized thick molded body having a complicated shape without causing shrinkage cavities. This is for the following reasons. In slip casting, the inking is usually completed from the part where the cavity has a narrow interval. Therefore, for example, as shown in Fig. 3 (a), when manufacturing a molded product with a narrow cavity The slip 13 injected into the cavity 12 of the mold 11 is
From the inlet region 12a of the above, the inking is completed, and the slip remains at the center of the molded body portion. Since this residual slip portion 15 is not in communication with the slip 13a of the inlet portion 14 of the molding die 11 (is blocked), shrinkage cavities occur as water is absorbed.

This tendency is remarkable especially in the case of large-sized thick products. This is because in the case of a large thick product, the dehydration of the central part of the molded product is significantly delayed.

In order to prevent the unsolidified slip portion from being left in the center of the molded body, it is conceivable to expand the diameter of the cavity inlet as shown in FIG. 3 (b). There is a problem that the post-processing step of deleting becomes complicated.

Therefore, an object of the present invention is to provide a slip casting mold for manufacturing a large-sized, thick-walled, and ceramic-shaped compact having a complicated shape without causing a shrinkage cavity or the like.

Another object of the present invention is to provide a method for manufacturing a large-sized, thick-walled and complex-shaped ceramic molded body without causing shrinkage cavities or the like.

[0009]

As a result of earnest research in view of the above object, the present inventors have found that, in slip casting, the slip in the inlet region of the cavity is solidified first, so that the inside of the molded body is not solidified. It has been found that, when the slip of the carcass is cut off from the outside, the supply of new slip to the center of the molded product is stopped, and a shrinkage cavity occurs as the carcass solidifies. Therefore, the inventors of the present invention, if a non-water-absorbing member is provided in order to delay the solidification of the slip in the inlet region of the cavity, the slip of the slip in the inlet region of the molded body is prevented until the slip in the center portion of the molded body is solidified. It has been found that it is possible to prevent solidification of flesh and thereby prevent shrinkage cavities. The present invention has been made based on the above findings.

That is, the mold for slip casting of the present invention is for a large-sized and thick ceramic molded body, and a non-water-absorbing member for delaying the inking of slip is arranged in the inlet region of the cavity of the mold. It is characterized in that the non-wetting slip inside the shaped body is not substantially shielded from the slip in the inlet region by means of the inking layer until the inking of the slip in the ceramic shaped body part is completed.

Further, the slip casting molding method of the present invention is to inject the slip into the cavity of the slip casting mold so as to allow the slip to be thickened, and the slip is thickened in the ceramic molded body portion. Until completion, the non-meated slip inside the shaped body is not substantially blocked from the slip in the inlet region by the inking layer.

[0012]

The present invention will be described in detail below with reference to the accompanying drawings. First, the slip casting mold of the present invention will be described.

As shown in FIG. 1, the slip casting mold of the present invention has split mold portions 2 and 3 made of a water-permeable material such as gypsum, and by joining the two,
The cavity 4 having a predetermined shape is formed. Cavity 4
Consists of a region 4a forming a molded body and an inlet region 4b. A removable non-water-absorbing member 5 is attached to the inlet region 4b of the cavity 4. The non-water absorbing member 5 is Teflon,
It is preferably composed of machinable wax, various resins and the like.

When a ceramic molded body is formed by such a slip casting mold 1, first,
Inlet region 4 of mold 1 consisting of split mold parts 2, 3 combined
As shown in FIG. 1 (a), the non-water absorbing member 5 is attached to b. Next, as shown in FIG. 1B, the slip 6 is injected from the open end of the non-water absorbent member 5. Entrance area 4 of cavity 4
By providing the non-water absorbing member 5 in b, the solidification of the slip 6 in the inlet region 4b is delayed. Therefore, the slip inside the molded body is prevented from being substantially blocked from the slip in the inlet region 4b by the inking layer so that the inking progresses and the shrinkage cavity is not generated. The reason why such an effect is obtained will be described in detail below in comparison with the conventional example.

FIG. 2 schematically shows a slip inking line (isochronous inking line) on a slip casting mold, where (a) is a conventional gypsum or the like, and (b) is a molded product. (C) shows the case of the present embodiment when the padded portion is provided in the. In FIG. 2, only the left side of the molding die with respect to the center line XX is shown for convenience of description.

In the case of (a), since the inking proceeds almost uniformly over the entire area of the mold 21, the inking is completed first from the inlet region 21b having a small diameter and the region 21a forming the molded body portion is formed. The central part will solidify last. Because of this, the meat line
22 is the entrance area 21b and intersects with the center line XX twice. That is, the inking layer 23 substantially blocks the slip 24a inside the molded body from the slip 24b in the inlet region 21b. This residual slip portion 24a is
Since it is not in communication with the slip 24b of the inlet area 21b, new slip is not supplied, and as the water is absorbed, a shrinkage cavity occurs.

In the case of (b), since the pad portion 26 is provided in the vicinity of the entrance area 21b of the cavity, the inking speed in the entrance area 21b is somewhat reduced. Therefore, the inking line 22 is less curved than in the case of (a). However, as the fleshing progresses, the fleshing line 22 intersects with the center line XX twice (the non-fleshing slip 24
a is substantially shielded from the slip 24b in the inlet region 21b by the inking layer). As a result, shrinkage cavities still occur. Further, in the case of (b), there is also a problem that the post-processing step of deleting this portion becomes complicated because there is the pad portion 26b.

In the case of (c) which is the embodiment of the present invention, since the non-water-absorbing member 5 is installed in the inlet region 21b, the inlet region
Infiltration of the slip at 21b is significantly delayed. Therefore, the inking proceeds from the area 21a forming the molded body, and the non-inking slip occurs in the inlet area 21b until the inking of the slip in this area is completed.
There is virtually no interruption from 24b. Therefore, there are no shrinkage cavities in the molded body.

In the above embodiment, the non-water absorbing member 5 is
Although the lower end portion has a shape protruding so as to cover a part of the molded body, the non-water absorbent member 5 of the present invention is not limited to such a shape. The position of the lower end of the non-water absorbent member 5 may be appropriately set in consideration of the balance between the above-described shrinkage cavity prevention effect and the molding speed.

The slip casting molding die of the present invention as described above is manufactured by forming a split die having a predetermined shape in advance as in the present embodiment and detachably attaching a non-water absorbing member thereto. You can Alternatively, the non-water-absorbing member 5 may be cast around the split mold when molding the split mold with gypsum or the like.

Next, the slip casting molding method of the present invention using such a slip casting molding die will be described.

The slip casting molding method of the present invention can be applied to slip cast molding of various ceramics. The ceramic raw material to be molded is not particularly limited, and nitride-based, oxide-based, boride-based, and carbide-based materials can be used.

First, if necessary, a binder component, a sintering aid, a dispersant, etc. are added to the above ceramic raw material, and these components are mixed with water as a medium to form a uniform sludge. Prepare.

Next, the sludge is poured into the slip casting mold as described above. After the injection, when the slip in the molded body part has solidified, the split mold is separated,
The molded product is taken out with the non-water-absorbing member 5 still attached. At this stage, if the slip in the portion surrounded by the non-water absorbing member 5 is not solidified, it may be left in the atmosphere until the dehydration is completed. After the water in the portion surrounded by the non-water-absorbing member 5 has diffused, the non-water-absorbing member 5 is removed.

The ceramic molded body thus obtained is dried and degreased, cut to a predetermined dimensional accuracy, and then sintered to obtain a final ceramic member.

The present invention will be described in more detail with reference to the following specific examples. Example 1 A split mold having a shape as shown in FIG. 1 (cavity height 180 mm, maximum cavity diameter 190 mm) was manufactured by using gypsum, and a tubular non-water-absorbing member made of machinable wax was attached to the inlet region of the mold. It was used as a casting mold.

2.5% by weight of Y ₂ O ₃ having an average particle size of 5 to 10 μm
And 1.0% by weight of Al ₂ O ₃ powder having an average particle size of 0.3 to 0.5 μm
And 42 parts by weight of water were added to 100 parts by weight of a ceramic mixture composed of α-Si ₃ N ₄ powder having an average particle diameter of 0.4 to 0.5 μm and the rest, and mixed by a ball mill for 40 hours.

The slip thus obtained was poured into the above mold for slip casting and left for 240 minutes. After that, the gypsum mold is released with the non-water absorbing member attached,
Further, after leaving it for 960 minutes, moisture remaining in the portion surrounded by the non-water-absorbing member was diffused and sufficiently solidified, and then the non-water-absorbing member was released from the mold to obtain a molded body.

The molded body thus obtained is cut,
As a result of observing the inside, there were no shrinkage cavities or the like.

[0030]

As described above in detail, in the slip casting mold of the present invention, the non-water-absorbing member is provided in the entrance area of the cavity to delay the solidification of slip in the entrance area. It is possible to prevent the slip inside the body from being blocked from the outside, thereby preventing the formation of a shrinkage cavity. By using the slip casting molding die of the present invention as described above, a large-sized, thick-walled and molded product having a complicated shape can be manufactured by slip casting without causing a shrinkage cavity.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an example of a slip casting molding die of the present invention, in which (a) shows a mounted state of a non-water-absorbing member, and (b) shows a state in which slip is injected.

FIG. 2 is a cross-sectional view showing a slip inking line inside a forming die, (a) showing a inking line in a conventional forming die, and (b) showing a conventional forming die having a pad portion. Fig. 3 shows a meat line, and (c) shows a line for the mold of the present invention.

FIG. 3 is a schematic view showing a conventional slip casting process, in which (a) shows a state in which an unincorporated slip remains inside the molded product, and (b) a molding die in which the inlet region is expanded. Shows the case of using.

[Explanation of symbols]

 1, 11, 21 ... Mold for slip casting 2, 3 ... Split mold 4, 12 ... Cavities 4a, 21a ... Region for forming molded body 4b, 21b ... Inlet region 5. ..Non-water-absorbing member 6 ... Slip 22 ... Inking line 23 ... Inking layer 24a, 24b ... Uninked slip

Continuation of the front page (72) Inventor Jun Koizumi, 1-4-1, Chuo, Wako, Saitama Stock Company Honda R & D Co., Ltd.

Claims (4)

[Claims] 1. A mold for slip casting of a large-sized thick ceramic molded body, wherein a non-water-absorption member for delaying the inking of slip is arranged in the inlet region of the cavity of the mold, whereby the ceramic is provided. A mold for slip casting, characterized in that the uninfiltrated slip inside the molded body is not substantially shielded from the slip in the inlet region by the inlaid layer until the slip has been completely thickened in the molded body part. 2. The mold for slip casting according to claim 1, wherein the non-water-absorbing member is made of Teflon, machinable wax, or resin. 3. Injecting slip into the cavity of the slip casting mold according to claim 1 or 2,
In the slip casting method for inking the slip, the uninfiltrated slip inside the molded body is substantially removed from the slip in the inlet region by the inking layer until the slip inking in the ceramic molded body part is completed. A slip casting molding method, which is characterized in that it is not blocked. 4. The slip casting molding method according to claim 3, wherein the molded body is taken out from the molding die and left to stand still with the non-water-absorbing member mounted at the time when the slip inking in the ceramic molded body portion is completed. Thus, the slip casting molding method is characterized in that the moisture remaining in the portion surrounded by the non-water-absorbing member and the central portion of the molded body is diffused.