JPH0361007A - Cast molding method for slurry and manufacture for calcined product of ceramic - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a method for manufacturing a hollow cylindrical ceramic molded body using plaster cast formability, and a hollow cylinder with good dimensional accuracy using the ceramic shaped body. The present invention relates to a method for manufacturing ceramic fired products.

[Conventional technology]

A cylindrical water absorption mold (typically a gypsum mold) is placed horizontally on a turning roller, and while rotating around its horizontal axis, slurry is injected into the mold and the inner peripheral surface of the mold is Centrifugal casting, in which plaster is deposited on a ceramic body, is widely used as a method for producing hollow cylindrical ceramic molded bodies. In Figure 7,
(1) is a water absorption mold, and (3) is a cooling roller. The water-absorbing mold (1) includes a water-absorbing sleeve (11) and a donut-shaped water-absorbing lid part (1, 2,
12), and is fitted and fixed into the metal mold (2) and placed horizontally on the turning roller (3) in order to prevent damage during rotation and to stabilize rotational interlocking.
2) rotates in one direction. (4) is water absorption mold (1)
This is a hopper that injects slurry into the tank.

From the hopper (4) to the Glj filling hole (
The slurry (S) injected through the central hole (03) of the lid part 12 spreads on the inner circumferential surface of the water absorption mold (1) due to the action of centrifugal force under high-speed rotation of the water absorption mold (1). As shown in Fig. 8, as shown in Fig. 8, the hollow cylinder has a layer thickness of 100 mm, and as shown in Fig. shaped ceramic body (8°
) is formed.

In the centrifugal slurry casting method, water absorption mold (
1) Since the plaster is attached under the action of a radial force (centrifugal force) on the inner circumferential surface, the resulting hollow cylindrical molded product has little distortion and The wall thickness can be adjusted as desired depending on the amount of plaster cast, and it is possible to obtain thin-walled products (for example, wall thickness 3 mm or less) that are impossible with other molding methods, such as extrusion molding.・
It is also easy to mold long products.

The centrifugally formed compact is demolded from the water-absorbing mold (1), dried, degreased, and then fired to form the desired hollow cylindrical fired product.

[Problems to be Solved by the Invention] According to the centrifugal slurry casting method, it is possible to mold large-diameter and long-sized molded products, and it is easy to mold thin-walled products, but Since the molded body is soft,
Deformation is likely to occur during demolding from a water-absorbing mold or during the handling process from subsequent drying and degreasing to firing.

Furthermore, deformation due to its own weight is unavoidable during the firing process.

Needless to say, the thinner the product, the larger the diameter and the longer the culm, the more likely this deformation will occur.

As a countermeasure against this problem, a method is used in which the molded body is formed into a thick wall in consideration of the amount of deformation required to reach the final product, and in the final stage, the inner and outer surfaces are machined to finish it to a predetermined size. However, this method does not avoid disadvantages such as an increase in the time required for inlaying in plaster casting, an increase in the weight of the molded body which makes it difficult to handle, and an increase in firing time and heat consumption.

The present invention provides an improved slurry casting method for solving the above-mentioned problems regarding the production of hollow cylindrical ceramic molded bodies and fired products thereof, and a method for manufacturing fired products using the molded bodies. be.

[Means and effects for solving the problem] The method for manufacturing a hollow cylindrical ceramic molded body of the present invention is to rotate the water absorption mold around its horizontal axis as the rotation center, and to remove the mud cast into the water absorption mold. In centrifugal mud casting, in which the material is deposited under the action of centrifugal force, a deposit layer of a predetermined thickness is formed on the inner circumference of the sleeve of the water-absorbing mold, and then the rotational speed of the water-absorbing mold is lowered to remove any undeposited white material. A portion of the mud is adsorbed to the lid surface in a donut shape at both ends of the sleeve by the suction force of the lid, and as the slurry rotates at a low speed, the unattached white mud is deposited to form a donut disc at both end edges. The present invention is characterized by forming a hollow cylindrical ceramic molded body having an inwardly projecting edge portion.

According to the present invention, during the thickening process of the slurry (S) cast into the water absorption mold (1), the centrifugal force acting on the slurry is adjusted. Of course, the adjustment is made by changing the rotational speed of the water absorption mold (1).

FIGS. 1 to 4 schematically show the process of attaching plaster in a water-absorbing mold in the method of the present invention. Figure 1 shows
Figure 2 shows the state of adhesion of slurry (S) during high-speed rotation of the water-absorbing mold (1) immediately after pouring slurry. However, when a certain amount of unattached white malt (S) remains, Figure 3 shows the rotation of the water-absorbing malt (1).
Figure 4 shows the state after switching from the previous WH; speed QII to low speed rotation, and the state in which the entire amount of slurry has been deposited while maintaining the same low speed rotation as described in 2. It shows.

However, in the centrifugal slurry casting molding of the present invention, from the time when the slurry (5) is cast into the water absorption mold (1), the ink layer (a) of the slurry has a predetermined layer thickness. Until this happens, as in normal centrifugal slurry casting, the high-speed rotation of the water absorption mold (1) causes the slurry (S) to undergo a strong centrifugal force (a force multiplied by gravity on the inner peripheral surface of the water absorption mold). : Approximately 35G or more" 2) is applied. As shown in FIGS. 1 and 2, the slurry (S) during the high-speed rotation process forms a layer thickness of - like that over the entire axial direction and forms a layer on the sleeve (11) of the water absorption mold (1). The adhesive layer (a) which is pressed against the inner circumferential surface and which is formed in the process also has a substantially constant thickness throughout the axial direction.

As shown in FIG. 8, the molded body formed by continuing to rotate the water absorption mold (1) at high speed and depositing the entire amount of slurry has a shape of 4 [4] throughout the axial direction. In the present invention, the molded body having one wall thickness and the other is the molded body with a thickness of 1/2'. 2/3), the rotational speed of the water absorption mold (1) is lowered to relieve the centrifugal force on the slurry.

With the relaxation of the centrifugal force, the unattached mud (S)
At both end regions of the sleeve (11), the lid portions (12, 12
), the lid part (12,
12) Generates a donut-shaped spread (S2) along the surface. FIG. 5 shows that part in an enlarged manner. In high-speed rotation, the centrifugal force (Y) is large and the effect of the suction force (X) of the lid part 02) on the mud is substantially canceled, but due to the relaxation of the centrifugal force as the rotation speed decreases, ,
The influence of the suction force on the slurry (S) appears, and the slurry (S) becomes stuck in a donut shape on the surface of the lid (12) as shown in the figure. It goes without saying that if the rotational speed is extremely reduced, the slurry will drip down, making it impossible to obtain a molded product having a predetermined wall thickness. As is clear from the above description, low-speed rotation as used in the present invention means that unattached mud is maintained in a state where it is pressed against the entire circumferential direction with a layer thickness of approximately -, and the lid portion Due to the adsorption force of (12, 12), the slurry (S) spreads like a donut (S) on the surface of the lid (12, 12).
It is easily understood that 2) means the rotational speed within the range in which the rotation speed is formed. Strictly speaking, the low rotation speed varies depending on the quality of the mud to be cast, the +A quality of the lid (12, 12), etc., but in actual operation - Good results can be obtained by setting the force (weight multiple) to be in the range of about 1O to 20G.

By inking the entire amount of the undeposited slurry (S) under the above-mentioned low-speed rotation, the hollow body (
A hollow cylindrical ceramic molded body (
A) is formed.

Hollow cylindrical ceramic and molded body (A')
, inside the donut disc-shaped inwardly protruding walls at both ends of the body (AZ,
Since A2) acts as a reinforcing member (rib), unlike the simple hollow cylindrical molded body formed by the conventional molding method shown in FIG. 8, the demolding operation from the water absorption mold (1), Or the resistance to deformation and damage during the subsequent handling process has deteriorated.

The hollow cylindrical ceramic rod (A) is dried and degreased according to a conventional method, and then subjected to a predetermined firing treatment. Even during the firing process, deformation due to its own weight is minimized due to the reinforcing effect within the inwardly protruding meridians. After finishing the firing process, as shown in FIG.
) by cutting and removing the body part (A
I) is obtained as a hollow cylindrical fired product.

〔Example〕

Using the centrifugal slurry casting apparatus shown in Fig. 7, casting was performed under the following conditions to form the body (8) as shown in Fig. 4.
A hollow cylindrical molded body (A) having inwardly protruding edge portions (Vtz, 8z) on both end faces was molded.

(1) Using a water absorption mold plaster mold (2) 0 slurry Dispersion medium (water) ... 30 parts by weight (3) Centrifugal molding conditions A predetermined amount of slurry is cast into the water absorption mold and placed on the inner peripheral surface of the mold. Rotate (high-speed rotation) at a rotation speed such that the gravity multiple on the mold's inner circumferential surface is approximately 40G (high-speed rotation), and after approximately 4 minutes, reduce the rotation speed to such that the gravity multiple on the inner peripheral surface of the mold is approximately 15G, and maintain that low-speed rotation for 5 minutes. Thereafter, the rotation was stopped, and the molded article (8) was then removed from the mold.

The molded body (8) has an outer diameter of 100 mm, a body length of 200 mm, and a protrusion thickness of 3 mm. (Eight,
) had a continuous, gently curved taper surface, and its central opening diameter was about 60 mm.

The molded article (A) was dried and degreased according to a conventional method, and then fired in a firing furnace at 1600°C for 2 hours. After the firing process, both ends were cut off as shown in FIG. 6 to obtain a hollow cylindrical ceramic ceramic product. The roundness of the fired product was within 1% of the outer diameter. This value is approximately three times more accurate than the roundness of fired products obtained via conventional centrifugal mud casting.

[Effects of the Invention] The hollow cylindrical ceramic molded product manufactured by the method of the present invention has a reinforcing effect of the inwardly protruding edge portions formed on both ends of the body, making it difficult to remove the mold during demolding and the subsequent handling process. It is less prone to deformation and damage, and is less likely to deform during firing. This effect is remarkable in thin-walled, large-diameter products, and greatly contributes to improving manufacturing yields. In addition, unlike conventional molded bodies, there is no need to make the walls unnecessarily thick in anticipation of the large amount of deformation required to reach the final product, thus reducing the time required for the molded body to be placed inside the lid and reducing the processing time during the firing process. Effects such as time reduction, reduction in heat consumption, and reduction in cutting allowance during finishing machining, improvement in productivity, and cost reduction can also be obtained.

[Brief explanation of drawings]

1 to 4 are explanatory axial cross-sectional diagrams showing the slurry deposition process in the present invention, FIG. The figure is an explanatory diagram of the cutting process of a hollow cylindrical ceramic body according to the present invention after firing treatment, Figure 7 is an axial cross-sectional diagram of centrifugal slurry casting, and Figure 8 is a conventional centrifugal slurry casting molding. FIG. 3 is an axial cross-sectional view showing the shape of the body. 1: water absorption mold, 11 sleeve, 12: lid member. 2: Die mold, 3: Turning roller, S: Mud a: Ink layer, A, A': Hollow cylindrical ceramic molded body, A2: Inward protruding inside.

Claims (1)

[Claims] 1. While rotating a water absorption mold consisting of a sleeve and lids on both ends of the sleeve around its horizontal axis,
In centrifugal casting, the slurry poured into the water absorption mold from the casting hole in the lid is deposited on the water absorption mold under the action of centrifugal force.
After forming a thickening layer of a predetermined thickness on the inner peripheral surface of the sleeve of the water-absorbing mold, the rotational speed of the water-absorbing mold is lowered, and a portion of the undeposited slurry is removed from both ends of the sleeve by the suction force of the lid. By attaching the slurry to the surface of the part in a donut shape and depositing the undeposited slurry while rotating at low speed,
A centrifugal mud casting method comprising forming a hollow cylindrical ceramic molded body having donut-shaped inwardly protruding edge portions at both ends. 2. The hollow cylindrical ceramic molded body obtained by the mud casting method according to claim 1 is dried and degreased, and then subjected to firing treatment, and after the firing treatment, the inwardly protruding edge portions at both ends of the body are A method for producing a fired hollow cylindrical ceramic product, characterized by removing the hollow cylindrical ceramic product.