DE102010050004A1 - Method for producing perforated articles from ceramics and pourable materials, involves hardening pourable mass in mold, and demolding tied and hardened article from mold such that article is dried and sintered - Google Patents

Abstract

The method involves recasting a model with perforations (15) using a plastic curable mass to obtain a certain model that matches with a casting mold. The inserts are removed from the model and the mold. The removed inserts are again fitted into the perforations of the mold. Pourable mass is cast into the mold until desired wall thickness of a perforated article (10) is reached, where excess pourable mass is discharged, so that the pourable mass is tied and hardened in the mold. The tied and hardened article is demolded from the mold, so that the article is dried and sintered. The method enables utilizing a porous plaster mold and a dummy as a model, where the dummy is made of wood, plastic, glass, plasticine and modeling clay. The porous plaster mold is made of polymeric material.

Description

The invention relates to a method for producing perforations having articles such as ceramic o. The like. From castable masses, wherein the perforations are produced prior to sintering during molding during casting. Accordingly, the present invention relates to a method for producing a slip-cast article having a perforated surface as well as to a perforated-surface ceramic article.

State of the art

Perforated articles, in particular, cast iron articles, for example, have heretofore been produced by compression molding a powder material, for example, ceramics, cold isostatic pressing of the resulting molded material, binder roasting the resulting formed material, a drying process to form perforations, and finally firing or machining to form perforations after firing. In the latter case, perforation formation is performed by the use of a drill, an ultrasonic wave, a laser beam or the like. The EP 1 454 725 A2 . US 4 900 491 A and US 5 173 229 A disclose other methods of making ceramic pieces with perforations. The GB 278,097 discloses a method of making ceramic material-produced plates having fine perforations. The method uses steel needles that are inserted into the plastic material and removed from the material prior to firing.

All these known solutions have the common drawback that perforations such as holes, recesses, recesses or the like are produced by mechanical working on the already formed plastic mass before or after firing. On the one hand, this post-processing requires considerable expenditure of machinery, labor and costs, on the other hand, only perforations with a straight-line penetration pattern in the ceramic walls can be produced. The processing of the ceramic can also lead to undesirable tolerance deviations in the location and the shape of the perforations, resulting in quality losses in the finished product.

task

In this prior art, the present invention seeks to provide a method for producing perforations having articles of pourable masses, with the different, different in position and shape perforations before firing in high accuracy and at the same time saving machines, material and Costs are safely generated.

This object is achieved by a method of the type mentioned above with the features of claims 1 and 11.

Advantageous embodiments of the method can be taken from the subclaims.

Typically, slip casting is a process for powder-based molding of the components that has been used for a long time in the traditional pottery industry. The slip casting method is a filtration process in which a powder suspension, usually a water-based suspension, is poured into a plaster mold which, through its porosity, generates capillary forces and removes liquid from the liquid (silt). When the liquid (filtrate) is sucked into the plaster mold, the powder articles are pressed against the walls of the plaster mold and gradually a compacted layer (filter cake) is formed. As soon as a desired layer thickness is reached, the casting process is stopped and the excess slip surplus is removed. After a certain drying time, the molded piece can be removed from the plaster mold for further drying and firing.

In the die casting process, the slip is pressurized in a space between two or more moldings, i. H. into the mold cavity, poured. Instead of the plaster molds, molds made of polymeric materials are typically used. These have a larger porosity that does not produce the same capillary forces but requires an external pressure to drive the filtration process. As higher pressures (<40 bar or 4.0 MPa) are used, this results in a much faster casting cycle compared to slip casting in which the capillary forces correspond to a pressure of 1-2 bar (0.1-0.2 MPa). Furthermore, the high pressure allows the immediate demolding of the dry castings from the mold and a new casting cycle can begin. The typically used polymeric material has much greater fatigue strength than gypsum and it is possible to produce cast products with more accurate dimensional tolerances.

• a Ausbilden eines an die Form und Gestalt des gewünschten Artikels angepassten Modells mit Perforationen,
• b Einpassen von Einsätzen in die Perforationen des Modells,
• c Umgießen des Modells mit einer plastischen Masse, um eine mit dem Modell übereinstimmende Gussform zu erhalten,
• d Entfernen der Einsätze aus dem Modell und des Modells aus der Gussform,
• e Einpassen der aus dem Modell entnommenen Einsätze in die Perforationen der Gussform,
• f Gießen der gießfähigen Masse in die Gussform bis die gewünschte Wandstärke des Artikels erreicht ist, Ablassen der überschüssigen gießfähigen Masse aus sowie Abbinden und Aushärten in der Gussform sowie Abbinden und Aushärten des Schlicker in der Gussform,
• g Entformen des abgebundenen und ausgehärteten Artikels aus der Gussform und
• h Trockenen und anschließendes Brennen bzw. Sintern des Artikels.

The solution according to the invention is based on the knowledge that the perforations o. The like. Before sintering during molding during casting to produce. This is achieved by the following steps:

• a forming a model adapted to the shape and shape of the desired article with perforations,
• b fitting inserts into the perforations of the model,
• c casting the model with a plastic mass to obtain a mold conforming to the model,
• d removing the inserts from the model and the model from the mold,
• e fitting the inserts removed from the model into the perforations of the mold,
• f pouring the pourable mass into the mold until the desired wall thickness of the article is reached, draining the excess pourable mass from and setting and curing in the mold and setting and curing of the slip in the mold,
• g demolding the set and cured article from the mold and
• Dry and then burn or sinter the article.

In a preferred embodiment of the present invention is preferably used as pourable mass water-based slip.

According to one embodiment of the present invention, the method of producing slip cast articles using a porous plaster mold in a pressureless slip casting process may be used.

According to another embodiment of the present invention, the articles may be manufactured using a pressure slip casting or a die casting process.

In a further embodiment of the present invention, the plastic materials used are materials which have the ability to form a soft, plastic, liquid-absorbent casting compound with short curing times without loss of shape. Gypsum compounds or water-absorbing resins are particularly preferably suitable.

A further preferred embodiment of the invention provides that inserts of water-repellent materials, preferably silicone, plastic, sealed plaster, glazed ceramics or other suitable materials are used, which are also water-repellent or at least partially provided with water-repellent coatings. Furthermore, the inserts can be either flexible or rigid. They may have any desired shape depending on the shape of the desired perforation in the final article. The shape of the insert must match the shape of the opening in the model so that the inserts can not be pushed through the opening during the casting process. This is achieved in that the inserts have a conical or cylindrical shape.

In a further preferred embodiment of the method according to the invention, the mold may be provided with openings having any desired angle, the inserts being insertable at any desired angle to form an angled perforation in the final article. The perforations can therefore take any shape and position in the mold.

• a Ausbilden einer wasserabsorbierenden Gussform, in welcher eine oder mehrere wasserundurchlässige Flächen auf der inneren Oberfläche der Form aufgebracht werden, die den gewünschten Perforationen des Artikels in Lage und Form entsprechen,
• b Abscheiden eines Schlickermaterials auf der inneren Oberfläche der Gussform bis die gewünschte Wandstärke des Artikels erreicht ist sowie Abbinden und Aushärten des abgeschiedenen Schlicker in der Gussform,
• c Entformen des abgebundenen und ausgehärteten Artikels aus der Gussform und
• d Trocknen und anschließendes Brennen bzw. Sintern des entformten Artikels.

The object is further achieved by a method comprising the following steps

• a forming a water-absorbent mold in which one or more water-impermeable surfaces are applied to the inner surface of the mold, corresponding to the desired perforations of the article in position and shape,
• b depositing a slip material on the inner surface of the mold until the desired wall thickness of the article is reached, and setting and curing the deposited slip in the mold;
• c demolding the set and hardened article from the mold and
• d drying and subsequent firing or sintering of the demolded article.

In a further preferred embodiment of this variant of the method according to the invention, the water-impermeable surfaces are produced by applying a water-impermeable seal or a water-impermeable resin on the inner surface of the casting mold. The application of the water-impermeable surfaces takes place up to a height which corresponds to the wall thickness of the desired article. Furthermore, these surfaces can take any shape and position, so that the perforations in the final article are also variable.

Further advantages and details will become apparent from the following description with reference to the accompanying drawings.

embodiment

In order to understand the above-disclosed subject matter of the invention and to see how it may be practiced, the invention will be described in more detail by way of non-limitative example with reference to the accompanying drawings.

Show it

1A a perforated article formed in accordance with an embodiment of the presently disclosed article of the invention, and 1B a section along the line AA in 1A ;

2 a flow chart of Schlickergußverfahrens according to an embodiment of the present invention;

3A a side view of a model of the desired shape according to an embodiment of the present invention and 3B a section along the line AA in 3A ;

4A and 4B the model of 3A and 3B in which inserts are fitted according to an embodiment of the present invention;

5A and 5B the model with the inserts after the 4A and 4B with plaster cast around the model according to an embodiment of the present invention;

6 a representation of the plaster mold according to the embodiment according to 5A ;

7A a representation of a plaster mold, in the openings inserts are fitted according to an embodiment of the present invention, and 7B a section along the line AA the 7A showing the step of slip casting;

8th a representation of the step for removing the excess slurry from the mold;

9A the mold with cast in slip and free of inserts as well 9B a section along the line AA in 9A ;

10 the step of demoulding the mold from the casting according to an embodiment of the present invention;

11A to 11C Cross-sections of a part of three forms, each of which is provided with an insert, which is coated with a water-repellent layer, which is made of a material having water-repellent properties and one at an angle inserted into the mold insert, which has water-repellent properties according to an embodiment of the present invention;

12A a mold according to another embodiment of the present invention, 12B a section along the line AA in 12A and 12C a cross section of the article, the shape of the 12A - 12B is formulated.

Detailed description of the designs

The term "rubber" used below denotes a model of the desired article.

The term "gypsum" is in the following statements for a plastic material, such as gypsum material of various kinds for the production of Schlickergußformen such as alabaster gypsum.

The 1 is an illustration of a perforated article made according to the invention and in general with 10 is designated. The item 10 according to this example, a hollow frustoconical shape has perforations 15 which pass through the article.

The 2 FIG. 12 shows a flow chart of a slip casting process according to the presently disclosed subject matter of the invention. FIG. According to an example - how 3 shows - a substantially solid rubber molded of the article to produce a molded article, from its surface - as in 1 shown - has continuous / penetrating perforations or openings.

The Dummi has on its outer surface there holes corresponding to the desired perforations in the final article.

In the holes of Dummi inserts are fitted. The inserts should be of sufficient length to fill the hole in the rubber and protrude from this. Alternatively, the rubber may be a hollow article provided with holes on its surface. The holes accordingly require consistently configured inserts such that at least a portion of them project outwardly from the surface.

The above step of the process results from forming a plaster mold around the rubber with the inserts extending through the plaster mold (i.e., the inserts rise from the outer surface of the plaster mold). The plaster is allowed to dry and harden. Then the rubber is removed from the plaster mold. Depending on the shape of the rubber and the shape, the inserts may be removed before or after this step, resulting in a perforated shape.

The inserts are then fitted into the perforations of the mold so that they protrude from the inner and upper surfaces of the mold (i.e., extend through the thickness of the material of the mold). The height at which each insert protrudes into the mold should be greater than the desired thickness of the final article. The mold is at least provided with a slurry opening through which the slurry is poured into the cavity of the mold. According to one example, one of the perforations may also be the slip opening.

The slurry is then prepared for casting and poured through the slurry opening into the mold. The casting process may be a conventional slip casting process or a die casting process. If the conventional slip casting method is used, the slurry is allowed to set and, once a desired layer thickness is achieved, the casting process is terminated by removing the excess slurry. After a period of drying, the molded piece can be removed from the mold for further drying and firing (sintering).

If optional die casting is to be used, the slurry is poured under pressure into the cavity of the mold. Instead of plaster molds, molds made of materials having suitable properties such as water filtration and resistance to mechanical pressure, such as polymeric materials, may be used. The remainder of the process is substantially similar to that of the slip casting process. One difference is z. Example, in the need to prevent the movement or the unwanted ejection of the inserts in the case of die casting, which is achieved by attaching the inserts to the mold during the casting process.

The 3a to 10 show the steps in a slip casting process for molding the articles according to 1A ,

The 3A and 3B show a rubber, generally with 30 designated. The rubber has the shape of a frustoconical body of substantially solid material such as wood, plastic, glass, clay, model clay, etc. A surface 34 of the dumbbell 30 with holes 32 (please refer 3A and 3B ), which can be formed by any suitable means such as drilling, CNC machining, stereolithography, etc. Im in 4A - 4B shown step in the holes 32 Calls 35 placed, which protrude from the rubber with a part to the outside. The surface 34 of the dumbbell 30 and the stakes 35 according to this example are not porous, so that prevents gypsum from the filters enters the pores. If the wooden dumpling sponge is any other fluid-absorbent material, it must be coated with shellac or isolated with another material to close the pores, if necessary.

The inserts according to this example are conical and made of a material that has water-repellent properties. However, the insert may have any desired shape and be made of a material whose outer surface is either water-repellent or coated with a material whose at least outer layer has such a property.

The plastic material 36 becomes the dumbbell 30 (please refer 5A - 5B ) and ties around the rubber 30 and the missions 35 accordingly. The cavity 40 (please refer 6 ) and the cavities 42 The inserts formed in the plastic material after removal of the rubber are identical in size to those of the original rubber 30 and the inserts 35 , Once the plastic material has reached the desired hardness, ie the molded form is upright, the inserts and the rubber are removed from the latter. The plaster mold is rearranged to form a molded cavity therein 40 to form and the inserts 35 be in the perforations 42 placed in the body 36 the plaster mold are formed. The stakes 35 are then fitted so that in the cavity 40 the shape (as in 7B to watch). Alternatively, the stakes 35 on the plaster mold 36 be attached and removed with this, if the shape of the rubber allows it.

According to the example illustrated in the figures, the plaster mold is formed from two pieces. However, it is also conceivable that the plaster mold may also consist of any other number of pieces, wherein the pieces can be held together by any known means of the prior art. One type of arrangement that is designed to hold the pieces of the mold together is in 6 shown. According to this example is one of the two parts 36a the form 36 with a protruding element 46a provided and parallel to this in the other part 36b the shape of a receiving bore 46b provided so that once the two parts 36a and 36b connected, the protruding element engages in the receiving element (see 7B ).

The arrangements are carried out to prepare the plaster mold so that an opening is provided, in which the slurry can be filled during the casting process.

Alternatively, such opening may be through one of the openings provided for use 42 be formed. In such a case, one of the inserts will not be put in place in the plaster mold. The plaster mold according to the present invention has a sufficient total volume to easily absorb moisture from the slurry during the casting process.

After the inserts are reinserted into the protruding part of the plaster mold, slip is poured 50 in the cavity 40 within the plaster mold (see 7B ) through the opening 48 poured until it is full. The casting process is then interrupted for a certain time. For the In the event that a pressure slip casting is carried out, the casting slip becomes 50 with pressure in the cavity 40 pressed. When the casting has reached the desired thickness, the excess, liquid cast slip is released from the mold (see 8th ) and a silt structure left on the inner mold surface. The casting is allowed to reach a substantially leathery consistency (stage). The inserts are then made from the plaster mold and, as a result, the casting (see 9A and 9B ) and the cast / article 10 is removed from the mold (see 10 ). It should be noted that the inserts can be removed at any stage after removal of the excess casting slip. Alternatively, the plaster mold and inserts may be removed at the same time, as long as the shape of the molded article permits. The molded casting / article may then be processed by any technique desired to achieve a final state of the article. For example, the article can be cleaned, cleaned, decorated and sintered.

The method of the invention can be used to make articles of conventional ceramics, complex ceramics, clay, etc. Optionally, the method according to the invention can be used in conjunction with any other known casting technique.

According to another variant of the presently disclosed subject matter of the invention, an alternative method of producing articles with perforations may be provided. In its first step, this method comprises pouring a slip into an in-mold 12A shown, water-absorbent form, which in general with 50 is designated, in which a water-impermeable surface 55 on the inner surface 52 is provided at one or more places / s, the location of the perforation in the final article 60 equivalent. In the second step, a slip material on the inner surface 52 the form separated.

The water-impermeable surface 55 stands out against the inner surface of the mold at a height substantially equal to the thickness of the wall of the article 60 corresponds so that when the slurry is poured into the mold, the casting does not over the surface 55 out, but only the area around the surface 55 around, causing the perforation 65 in the article 60 is formed. Therefore, the shape of the water-impermeable surface 55 a form of the perforation 65 equivalent. Such a method may be used in conjunction with methods employing the inserts, for example in producing one or more protruding parts in the final article by coating corresponding parts on the inner side of the mold with water-impermeable material prior to filling the slurry.

In addition, such a method can be used in high pressure slip casting.

The water-impermeable surface may be formed by any suitable method such as applying a water-impermeable seal, applying a water-impermeable resin, etc.

Various changes, variations and modifications of the presently disclosed subject matter of the invention may be made without departing from the scope of the invention.

LIST OF REFERENCE NUMBERS

10

Perforated article

15

Perforation / openings in 10

30

dummi

32

Drilling in 30

34

Surface of 30

35

Bets for 30

36

plaster mold

36a, 36b

Parts of the plaster mold

40

cavity

42

Perforations / openings in 36

46a

Projecting element

46b

location hole

48

Opening for filling

50

Schlicker

52

Inner surface

55

Impermeable surface

60

final article

65

opening

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• EP 1454725 A2 [0002]
• US 4900491 A [0002]
• US 5173229 A [0002]
• GB 278097 [0002]

Claims (13)

A method of making perforated articles such as ceramics or the like from moldable masses, wherein the perforations are produced prior to sintering during molding during casting, comprising the following steps a forming a model adapted to the shape and shape of the desired article with perforations, b fitting inserts into the perforations of the model, c casting the model with a plastic hardenable mass to obtain a mold conforming to the model, d removing the inserts from the model and the model from the mold, e fitting the inserts removed from the model into the perforations of the mold, f pouring the pourable mass into the mold until the desired wall thickness of the article is reached, draining the excess pourable mass from and setting and curing in the mold, g demolding the set and cured article from the mold and h drying and subsequent firing or sintering of the article. A method according to claim 1, characterized in that slip is used as the pourable mass. A method according to claim 1, characterized in that the articles are produced by pressureless slip casting or pressure slip casting. A method according to claim 1, characterized in that as a model Dummi of wood, plastic, glass, clay, modeling clay o. The like. Is used A method according to claim 1, characterized in that a porous plaster mold or a form of polymeric material is used as the mold. A method according to claim 1, characterized in that as plastic mass materials are used which have the ability to form a soft plastic, liquid-absorbent casting compound with short curing times without loss of shape. A method according to claim 6, characterized in that gypsum compounds or water-absorbing resins are used as the casting material. A method according to claim 1, characterized in that inserts of water-repellent materials, preferably silicone, plastic, sealed plaster, glazed ceramics or other suitable materials are used. A method according to claim 1, characterized in that the inserts are flexible or rigid and have a shape which prevents passage of the inserts through the perforation during casting. A method according to claim 1, characterized in that the perforations in the mold can take any shape and position, preferably angular position. A method of making perforated articles such as ceramics or the like from moldable masses, wherein the perforations are formed prior to sintering during molding during casting, comprising the following steps a forming a water-absorbent mold in which one or more water-impermeable surfaces are applied to the inner surface of the mold, corresponding to the desired perforations of the article in position and shape, b depositing a slip material on the inner surface of the mold until the desired wall thickness of the article is reached, and setting and curing the deposited slip in the mold; c demolding the set and hardened article from the mold and d drying and subsequent firing or sintering of the demolded article. A method according to claim 11, characterized in that the water-impermeable surfaces are produced by applying a water-impermeable seal or a water-impermeable resin on the inner surface of the mold. A method according to claim 11, characterized in that the water-impermeable surfaces are applied to a height corresponding to the wall thickness of the desired article.

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