RU2285609C1 - Mold set - Google Patents

Abstract

FIELD: ceramics, in particular, manufacture of large-sized products from quartz ceramics and other materials by aqueous slip casting in gypsum molds.

SUBSTANCE: mold set comprises moisture absorbing mold, passive core with supporting flange, feeding reservoirs located on core flange, and pouring pipe connection. Detachable chamber having volume making 0.1-0.5% the volume of slip in mold is additionally mounted within lower part of mold. Detachable chamber is separated from article blank by means of conical fluoroplastic bushing and netting having 1-2 mm sized meshes. One feeding reservoir is made from transparent material and equipped with measurement divisions. Average value of total sectional area of feeding reservoir is commensurable with sectional area of article to be produced in slip feeding zone. Volume of reservoir is V_r=kV_m+Sh, where k is slip shrinkage coefficient during setting-up of blank; h is critical height of gravitational stratification of slip during setting-up of blank; V_m is volume of slip in mold; S is average value of total sectional area of feeding reservoirs.

EFFECT: simplified process of molding high-quality articles having uniform properties and produced from quartz ceramics and other ceramic materials by aqueous slip casting process.

2 dwg, 3 tbl

Description

The invention relates to the ceramic industry, and more specifically to a technique for the production of ceramic products by the method of water slip casting in gypsum forms, and can be used in the manufacture of large-sized products from quartz ceramics and other materials.

Known mold kit for casting quartz steel pouring glasses ("Refractories", No. 11, p. 7-11, 1973), including a gypsum mold, a passive core and a feed tank for filling the slip in the mold and feeding slip form in the process of recruitment. As the slip leaves the feed tank into the mold, the tank is filled with fresh slip. The process of stratification of the slip in the form and make-up capacity is not controlled, topping up the slip is carried out repeatedly. This is one of the reasons for the great diversity of the material in the products (up to 4 abs.%) And complicates the technology of production of products.

More perfect seems to be a mold kit for forming large-sized conical, animated and other products by the method of water slip casting according to the patent of the Russian Federation No. 2137599, Device for forming ceramic products from water slip, class. 28 B 1/26, 1999, including a gypsum mold consisting of a perforated metal frame and a gypsum layer formed on the profile of the outer surface of the product, a passive core with a removable support flange and centering elements. On top, on the supporting flange of the core, four make-up tanks are fixed, connected to the cavity by the holes in the core flange. The slip is fed into the mold and feed tanks from below, for which a filling nozzle is connected to the lower flange of the mold. The slip of the profitable containers after collecting the workpiece is carried out by turning the mold set using a special tilter. The proposed mold kit provides large-sized ceramic products with a uniform wall thickness over the cross section due to the coaxial installation of the core in the mold.

The disadvantage of the mold kit, as well as the previous design, is the following:

- the design and volume of profitable containers are not indicated, which leads to the deposition of the slip on horizontal surfaces, a change in the rheological properties of the slip entering the mold;

- there is no way to control the completion of a set of blanks except for using a stylus, which often violates the integrity of the product;

- there is no possibility of control and neutralization of the gravitational stratification of the slip when obtaining high-quality workpieces.

The closest in functionality and technical essence is the mold kit according to the patent of the Russian Federation No. 2236938. Mold kit for casting ceramic products from water slips, cl. B 28 V 7/34, 2004, including a moisture-absorbing gypsum mold, a passive core with a support flange, make-up containers mounted on the core flange, a filling nozzle, characterized in that, in order to obtain high-quality products with high uniformity of product height properties due to the control of the parameters of the slip entering the mold, and the discharge of the spent, exfoliated slip. Make-up containers in the lower part are equipped with tubes with a stem with a sealing cuff and are made conical.

The disadvantage of the prototype is the complexity of the technology of forming products associated with the need for periodic monitoring of the parameters of the slip in the feed tank, the operation of draining the spent slip and filling the tanks with a fresh slip. In addition, in the prototype and analogues there is no structural element that allows the selection of gravity sediment in the lower part of the mold, separating it from the molded product. Gravity sediment adversely affects the quality of products. There are also no structural elements for monitoring the end of the set of blanks, shrinkage of the slip during the set of blanks.

The objective of the present invention is to simplify the molding technology of high-quality, with high uniformity of properties, large-sized products from quartz ceramics by the method of water slip casting in gypsum molds. This goal is achieved by the fact that the proposed set containing a moisture-absorbing form, a passive core with a support flange, make-up containers mounted on the core flange, a filling nozzle, characterized in that in the lower part of the form an additional 0.1-0 removable camera is installed, 5% of the volume of the slip in the mold, the removable chamber is separated from the product blank by a conical fluoroplastic sleeve and a mesh with a mesh of 1-2 mm, one make-up tank is made of transparent material with dimensional divisions, the average value e the total cross-sectional area of makeup capacitances commensurate with the area of the cross section of the molded article to fill the area of the slip and their volume is equal to V _f = kV _p + Sh, where a - coefficient of shrinkage of the slip at a set workpiece, h - the critical height of the gravitational separation of the slip in the sprue container during a set of blanks, V _f is the volume of the slip in the mold, S is the total cross-sectional area of the feed tanks in the cylindrical part.

To obtain products that are homogeneous in their properties by the method of water slip casting, it is necessary to maintain stable parameters of the slip in the mold during the entire period of the workpiece recruitment. Due to the fact that suspensions with good casting properties are stratified, stabilization of slip properties in the mold, especially when casting large-sized products, is a difficult task. The authors found that when molding such products, it is possible to achieve stabilization of slip parameters in the mold due to the selection of the design and volume of feed tanks and the removal of gravity sediment beyond the limits of the molded product. As shown by experimental studies, when forming large-sized products, the stratification of the slip occurs in the upper and lower parts, while remaining constant in the middle zone. For example, table 1 shows the depth changes in the properties of the slip, starting from the top layer, in the feed tanks after dialing the blank of a conical shape with a height of 1300 mm and a wall thickness of 18 mm. The initial slip parameters are also given.

Table 1 Slip initial parameters Slip sample height from surface, mm 25 fifty 75 one hundred 125 150 200 300 400 Density 1.88 g / cm ³ 1.85 1.86 1.87 1,875 1.88 1.88 1.88 1.88 1.88 Viscosity 30 s VZ-1 thirty thirty thirty 31 28 26 thirty 28 thirty Humidity 14.4% 15.8 15.4 14.8 14,4 14.3 14.5 14.5 14.3 14,4 Tonine (particles 63-500 microns) 6.4% 4.3 14.9 5,6 6.0 6.3 6.3 6.4 6.4 6.3

It is seen that gravitational separation occurs at a height of up to 100 mm and can be determined experimentally. Then, the slip parameters are stabilized, remaining at the level of properties in the original slip. We took this fact into account when choosing the volume and size of make-up tanks. The slurry shrinkage coefficient is also established experimentally by the selection of the workpiece. For slurries used in the technology for manufacturing products from quartz ceramics, it is in the range of 11–16% and is mainly determined by the moisture content of the suspension. Shrinkage during the collection of products from a slip with a density of 1.87-1.89 g / cm ³ is 13%.

When choosing the volume and height of make-up containers to obtain products that are homogeneous in their properties, these two factors must be taken into account: stratification due to gravity and slip slip into the mold due to its shrinkage during the collection of the workpiece.

The average value of the cross-sectional area of the make-up containers should be commensurate with the cross-sectional area of the molded product in the slip feed zone. This allows you to more clearly track the kinetics of the set of blanks and the completion time of the set of blanks.

The implementation of one of the make-up containers made of transparent material with dimensional divisions greatly simplifies the process of controlling the completion of a set of blanks, eliminates the use of a stylus for these purposes, which eliminates damage to the typed blank.

Table 2 shows the estimated volumes of make-up containers during the molding of large-sized products according to the proposed formula, which ensure high uniformity of molded products made of quartz ceramics depending on their size.

table 2 Slip volume in the form, l Minimum volume of feed tank, l S = 50 cm ² S = 100 cm ² S = 200 cm ² S = 300 cm ² 10 1.8 2,3 3.3 4.3 twenty 3,1 3.6 4.6 5,6 thirty 4.4 4.9 5.9 6.9 40 5.7 6.2 7.2 8.2

The heterogeneity of the products in the lower part is also caused by stratification of the slip and the formation of a gravitational sediment mainly from larger particles. For high-density silica glass slips used in the manufacture of large-sized products by the method of water slip casting, the rate of gravitational deposition of particles is 5-10 times lower than the rate of set of a ceramic crock on a gypsum mold due to the capillary forces of gypsum absorption. In this regard, the magnitude of the gravitational sediment, causing the heterogeneity of the product, is usually 0.1-0.5% of the volume of the product.

In order to exclude the influence of gravitational sediment on the homogeneity of the products, the proposed design of the mold kit provides a removable camera, for example, in the form of a metal pipe, with a volume of 0.1-0.5% of the volume of the slip in the mold.

Figure 1 shows a General view of the inventive molded kit; figure 2 - node I in figure 1.

The mold kit includes a moisture-absorbing form (1), a passive core (2) with a support flange, make-up containers (3) mounted on the core flange, one of which is made of transparent material (glass, polyethylene, etc.) with dimensional divisions. In the lower part of the mold, a removable chamber (4) is installed in the form of a metal pipe for collecting gravitational sediment, a filling nozzle (5). The chamber is separated from the workpiece by a conical fluoroplastic sleeve (6) and a mesh with a mesh of 1-2 mm (7). The grid freely passes a large fraction of the slip into the chamber and facilitates the separation of the workpiece when it is removed from the mold. The conical fluoroplastic sleeve eliminates the adhesion of the casting in the cylindrical hole of the lower flange and also provides high-quality workpieces in the pointed part of the product.

The proposed mold kit works as follows.

They assemble the mold kit on the tilter according to the generally accepted scheme. A conical fluoroplastic sleeve is laid in a cylindrical hole of the lower flange, and a mesh with a mesh of 1-2 mm is placed on the flange. A removable chamber is mounted on the filling nozzle to collect gravity sediment and, using bolts, connect it through a rubber gasket to the mold flange. The filling nozzle is connected to a slip line. Four make-up containers are installed on the surface of the core flange through rubber gaskets, one of which is made of transparent material (glass, polyethylene, etc.) with dimensional divisions on the surface of the cylindrical part of the container. Fill the mold and make-up containers with a slip. A set of blanks (products) is controlled by the loss of the slip in a transparent container. If no slip loss is observed within 5-10 minutes, the workpiece recruitment process is completed and the remaining slip is drained. Dismantling the mold kit is carried out in the reverse order. Removing the product is carried out by spontaneous (under the influence of weight) lowering the product on a wooden stand with a rubber gasket. The product is transported to the basement.

The inventive device is a molded kit for casting ceramic products by water slip casting - provides a homogeneous workpiece in density and porosity, height and circumference. Table 3 shows the values of these parameters for a quartz ceramic product cast from a slip with the following parameters: viscosity 23 sec. According to VZ-1, density 1.87 g / cm ³ , humidity 14.5%, fineness (T = 63-500 microns ) 5.0%, pH 5.7.

Table 3 Height zones 1 generatrix 2 generatrix 3 generatrix 4 generatrix p, g / cm ³ P,% p, g / cm ³ P,% p, g / cm ³ P,% p, g / cm ³ P,% one 1,926 12.85 1,925 12.90 1,928 12.76 1,924 12.94 2 1,923 12,99 1,923 12,99 1,927 12.76 1,925 12.90 3 1,922 12.03 1,928 12.76 1,926 12.85 1,924 12.94 four 1,927 12.81 1,927 12.81 1,931 12.62 1,928 12.76 5 1,929 12.71 1,930 12.65 1,926 12.86 1,929 12.72 6 1,928 12.76 1,929 12.71 1.928 12.76 1,930 12.65 7 1,926 12.85 1,929 12.71 1,925 12.90 1,925 12.90 8 1,930 12.65 1,930 12.67 1,930 12.67 1,928 12.71

Product height 1300 mm, base diameter 450 mm, wall thickness 18 mm.

The volume of 4 gating containers of 6.8 liters.

The slip was not drained and refilled, which greatly simplifies the technology for producing high-quality, uniform properties quartz ceramic products.

The proposed mold kit can be used for molding products from other ceramic materials, such as ceramic glass.

Information sources

1. K.A. Krasotin, D. B. Minkov, T. S. Makarov and others. Production of quartz glasses. “Refractories”, pp. 7-11.1973

2. RF patent No. 2137599, Device for molding ceramic products from aqueous slips. Kl. B28B 1/26, Bull. No. 26, 1999

3. RF patent No. 2236938, Mold kit for casting ceramic products from water slips. Kl. B28 B 7/34, Bull. No. 27, 2004 (prototype).

Claims (1)

A mold kit for molding ceramic products by water slip casting into gypsum molds containing a moisture-absorbing mold, a passive core with a support flange, make-up containers mounted on the core flange, a filling nozzle, characterized in that a removable chamber of volume 0 is additionally installed in the lower part of the mold 1-0.5% of the volume of the slip in the mold, the removable chamber is separated from the product blank by a conical fluoroplastic sleeve and a mesh with a mesh of 1-2 mm, one make-up tank is made of transparent material and with dimensional divisions, the mean value of the total cross-sectional area of makeup capacitances commensurate with the area of the cross section of the molded article in the feeding zone of the slurry, their volume is equal to V _f = kV _p + Sh, where a - coefficient of shrinkage of the slip at a set workpiece, h - the critical height of gravitational separation slip during collection of the workpiece, V _f is the volume of the slip in the form, S is the average value of the total cross-sectional area of the feed tanks.

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