RU2375173C2 - Method and press for simultaneous moulding and finishing of ceramic products - Google Patents

Abstract

FIELD: technological processes. ^ SUBSTANCE: invention is related to the field of moulding. Method for simultaneous moulding and finishing of ceramic products, in which the following stages are performed: press is brought into ready condition; frame equipped with elastically deformable membrane is stretched onto the first punch; press is brought into reduced position; ceramic material is loaded into cavity and exposed to pressing; product is withdrawn. System for simultaneous moulding and finishing of ceramic products comprises press, elastically deformable membrane and accessories for membrane stretching. ^ EFFECT: improved quality of manufactured products. ^ 20 cl, 8 dwg

Description

The present invention relates to a method and press for the simultaneous molding and finishing of ceramic products.

In particular, the present invention relates to a method and a press for simultaneously molding and finishing dishes, such as ceramic plates.

State of the art

Ceramic products can be finished using a variety of known methods, such as sliding decalcomania, manual or automatic dyeing, direct silk-screen painting and tampography.

Finishing by means of sliding decalcomania consists in applying drawings (decalcomania) to pressed, cropped, glazed and fired ceramic products. After drawing, the product is re-fired to fix the decalcomania in the glaze. This method allows you to perform multi-color finishes, however, it slows down the process to a certain extent and is very expensive. In addition, finishing by means of sliding decalcomania does not allow after its implementation to apply glaze, which would give the pattern resistance to mechanical damage due to friction.

Finishing by brushing manually or in automatic mode consists mainly in applying a picture to a ceramic product with a brush. This method, which also allows for multi-color finishes, is mainly used for very simple designs or for products such as handicrafts.

Finishing ceramic products by direct silk-screen painting consists in applying a “mesh pattern” to the product being subjected to decoration, the cells of which can be filled with paint only in accordance with the reproduced pattern.

Paint using a squeegee (scraper blade) or other known device is applied to the grid template only in accordance with the figure so as to transfer it directly to the product being finished.

This method can be used to decorate only flat or slightly convex products or flat or repeating parts of the product, which limits the possibility of finishing only the central part or edge (edge) of the plate.

In decorative pad printing, silicone elastic pads are used to transfer a layer of paint from the plate on which the drawing is applied to the surface of the finished product.

This method is very cheap and makes it very easy to perform a single-color finish or apply drawings to commercially available products, even to concave or convex surfaces, such as the surface of dishes, in particular plates. However, difficulties arise when applying this method to polygonal products.

Despite the fact that finishing using tampography significantly reduces the cost of manufacturing decorated products with a significant expansion of the variety of forms suitable for use, in the full cycle of molding decorated ceramic products these advantages appear only at the finishing stage.

It is important that in the known methods of finishing, the finishing stage is carried out in relation to already fired and possibly glazed ceramic products, as a result of which the production time of the finished decorated product is very long, mainly because of the time required to place the product so that it can be It was finished, and also because of the time of the decoration itself.

DE 3446175 discloses a method and apparatus for the manufacture of decorated ceramic elements (moldings), in which case the substance used for decoration is applied to a membrane (diaphragm) for compression. Then, between the pressing membrane and the first part of the mold, a tight connection is created along the edge, as a result of which the substance used for finishing is transferred to the first part of the mold. The pressing membrane is then removed, and a filling chamber is formed between the first part of the mold and the second part of the mold, from which air is evacuated and which is then filled with the ceramic material composition. The composition is subjected to final pressing to form the element onto which the substance used for decoration is transferred.

Disclosure of invention

Thus, there is an urgent need to develop a method and a press for molding and finishing ceramic products, such as to significantly reduce the overall production time of a decorated ceramic product and, in contrast to the limitations imposed by the prior art, to surface any shape with a significant reduction cost.

The aim of the present invention is to provide a method of molding and finishing ceramic products, which would satisfy the above requirements and at the same time would overcome these disadvantages of the prior art, as well as the development of a press for implementing this method.

This goal is achieved by developing a method for simultaneously molding and finishing ceramic products in accordance with paragraph 1 of the claims and a press in accordance with paragraph 13 of the claims.

The dependent claims disclose preferred and particularly advantageous embodiments of the method and press for simultaneously molding and finishing ceramic products in accordance with the invention.

Brief Description of the Drawings

Additional features and advantages of the invention will become apparent after reading the description below, which discloses an example, not limiting the scope of the invention, with reference to the accompanying drawings, where:

1 and 2 show a General view of the press according to the invention, shown in a diluted position;

figure 3 shows a General view of the part of the press shown in figure 2;

figure 4 shows a top view of part of the press shown in figure 2;

figure 5 and 6 schematically shows a vertical section of the press, respectively, in diluted and reduced positions.

An embodiment of the invention

As shown in the drawings, the press for the simultaneous molding and finishing of ceramic products according to this invention is generally indicated by the number 1.

The term "decoration" in the context of this invention refers to any effect that adorns the product and may be a pattern, lines or colors.

Press 1 contains the first stamp 2 and the second stamp 3, made with the possibility of movement in the direction towards each other and from each other, passing from the diluted position (Figure 1-5) to the reduced position (Figure 6) and vice versa. In the example shown, the press contains two pairs of dies, however, the press according to this invention may contain any number of pairs of dies.

As shown in the drawings, the first stamp 2 is fixed (fixed), while the second stamp 3 is movable, while moving in the horizontal direction, however, another variant of mutual movement can be used, for example, stamps made with the possibility of moving in vertical direction.

To simplify the description, the molding and decoration of the plates will be described, however, any other ceramic product, in particular crockery, can be molded. In addition, any other decorated ceramic product, such as tiles, can be made.

According to the present invention, the fixed stamp 2 (shown in the drawings on the left) and the movable stamp 3 (shown in the drawings on the right) comprise molding surfaces suitable for forming a plate, for example a soup plate (a plate with a deep bottom), the concave surface of which faces the fixed stamp 2.

According to the present invention, when the two dies are arranged in a diluted position, the annular frame 5, also called simply a ring, is set so as to be precisely located over the stationary dies 2, and it is generally made of steel or other material and can be clad with plastic and provided with an elastically deformable membrane 6 attached to the ring 5.

The way in which the ring 5 (with the membrane 6) is pulled onto a fixed stamp 2, is selected based on which press is used, and depending on the direction of movement of the movable stamp 3, which can occur in the horizontal or vertical direction. A preferred embodiment is described in more detail below.

The circular rim 2a of the fixed stamp 2 is located below the flat central portion 2b to form a concave surface of the plate, since the membrane 6 is deformed so as to attach to at least the central portion 2b of the stamp 2, while the circular rim 2a of the stamp 2 is attached to the circular part of the membrane 6 near the ring 5 is incomplete.

According to a preferred embodiment of the present invention, in order to achieve complete attachment of the membrane 6 to the fixed die 2, the fixed die 2 is made of partially (selectively) porous material so that a vacuum can be created between the membrane 6 and the die 2 by means of an air suction system.

Thus, when the membrane ring 5 is pulled over the fixed die 2, the air suction system is activated, obtaining the membrane 6 completely attached to the fixed die 2 even at the rim 2a.

Preferably, the fixed die 2 is made of porous rubber of the type that is commonly used for die casting dies and therefore known in the art. In addition to the fact that rubber provides the necessary permeability to create a vacuum through the stamp, it also has the necessary strength to operate at relatively high pressure.

In order to at least partially decorate the inner part of the plate, the material used for decoration is applied to that part of the membrane 6, which is opposite the side directly attached to the fixed stamp 2, that is, to the side that is shown facing to the right in the drawings, and this material in the example is a paint for ceramics, usually in the form of silk-screen paste, which allows you to properly reproduce the picture.

The plate is simultaneously molded and finished by moving the movable stamp 3 in the direction of the fixed stamp 2.

The shape of the movable die 3 corresponds to the shape of the back side of the plate, that is, the side that, in normal use, is located on the table. When the dies are in the reduced position (FIG. 6), a molding cavity 4 is formed between the stationary die 2 (with the membrane 6) and the movable die 3, into which ceramic material is supplied in the form of crushed alumina under pressure or by suction. Filling occurs when the two dies 2 and 3 are brought together to such a distance that a cavity 4 is formed with a thickness exceeding the required thickness of the finished plate by about 1.5 times (Figure 6).

Such a ceramic material is known and can, for example, be ceramic, porcelain, vitreous china, etc., ground to a powder. The crushed powder is loaded in a known manner. In the above example, loading is performed through the slot 60 (Fig.6), formed when the dies are in the reduced position. During loading, the cavity 4 is placed under vacuum by means of known suction devices that suck air through two opposing openings 61 made in the ring 5 and in communication with the cavity 4, while the dies are in the reduced position so that vent air from cavity 4.

After loading is complete, the movable die 3, preferably of the isostatic type, pre-compresses at a pressure of about 280-300 bar in order to isolate the cavity 4 and allow the rubber isostatic membrane 7 to adhere to the powders in the cavity 4. During pre-pressing the cavity continues to be under vacuum to remove air present in the powders placed in the cavity. Upon completion of the preliminary pressing, the powders located in the cavity 4, by this time already free of air, are subjected to further pressing, which is carried out by supplying liquid, for example oil, into the space behind the isostatic membrane 7, under pressure, while the membrane exerts pressure on the powders with the same intensity in all directions. Typically, such a final pressing occurs at a total pressure of about 400 bar.

Although an isostatic type stamp is preferred, it is obvious that a non-isostatic stamp can be used.

The pressure applied by the stamp 3 to the powders placed in the cavity 4 by the known method facilitates the transfer of the pattern from the membrane 6 on which it is applied to the inside of the plate, while the pattern partially penetrates the ceramic powders according to the type of marquetry. In this regard, at the end of the process, there are no protruding parts on the decorated surface typical of the finish known from the prior art, since the paints have fully entered the product.

At the end of pressing, the movable die 3 is retracted and the decorated unfired plate is removed (pushed out) and fed to the cutting line, then it is dried or calcined until the final glazing is completed, after which glaze is applied. Thus, the pattern of the finished plate is located completely under the glaze.

According to the present invention and in order to easily obtain visually attractive patterns, paints are applied to the membrane by means of screen printing, this method is already known and therefore is only mentioned in this description.

If described in more detail, the pattern on the membrane is applied by means of successive predetermined passes, performed using known devices for planar screen printing, each passage is designed to transfer a certain ink, which is dried before the next application.

At the end of all the passages required to apply the desired pattern, the membrane 6 is treated with steam, that is, it is exposed to a steam jet, which causes wetting of the silk-screen printing paste present on the membrane 6 and its transition to a liquid state. This allows you to better transfer the pattern during the formation of the plates, as it prevents the situation in which part of the paste for screen printing remains adhered to the membrane 6.

As an alternative to the cold transfer described above, the colored powders may be mixed with heat-melting wax-based carriers. In this case, neither drying after each pass for applying paint is required, nor subsequent steam treatment of the membrane 6 after finishing the paint application and before transferring the pattern to the plate, since the wax contained in the media melting under the action of heat prevents the situation when the powders remain attached to the membrane 6. In addition, the powders melted by the action of heat can be applied continuously on top of each other by silk-screen printing.

Preferably, the membrane 6 is made of flexible silicone or polyurethane.

According to a preferred embodiment of the present invention, in order to further increase the productivity of the press 1, suitable supporting and moving devices, generally indicated by the number 8, are used to move the ring 5 with the membrane 6.

Such devices 8 for supporting and moving, for simplicity, shown for a single press, are a carriage 9, made with the possibility of sliding in the vertical direction on a pair of parallel guides 10 located on two corresponding racks 11, to which are attached two pairs of sliders 12 made with the possibility of sliding in the horizontal direction on two pairs of rails 13 mounted on two pairs of fixed crosses.

Fixed crosses are located horizontally parallel to the direction of movement of the movable die 3 so as to go beyond the general contour of the dies 2, 3.

It is important that the carriage 9 is capable of vertical movements along the guides 10 and horizontal movements along the rails 13.

The carriage 9 supports a pair of upper and lower connecting devices (FIG. 1), each of which connects the ring 5 with the membrane 6 with the possibility of detachment. In the shown example, the connecting devices are made in the form of a magnetic holding system containing two rotating parallel rods 15 and two horizontal elements 16, extending from the carriage 9, each of which at the free end contains a magnet 16.

As an alternative to the support and movement arrangements described above, a gripping system not shown in the drawings may be used in which mechanical clamps are used.

When the device is operated, the support and moving devices 8 operate as follows: a suitable feeding system, not shown for simplification, acting in the example shown above with respect to the dies 2, 3 so as not to interfere, places a ring 5 with a decorated membrane 6 on the upper connecting devices, which by means of magnets 16 attract two opposing gripping elements 50, extending from the edge of the ring 5.

After this placement of the ring 5 with the membrane 6, the carriage 9 slides down to set the membrane 6 in accordance with the form for stamping. After stopping the vertical movement of the carriage 9, the press 1 operates in such a way that the isostatic movable die 3 moves towards the stationary die 2, forming a cavity into which the ground ceramic material is introduced.

When moving forward, the isostatic movable stamp 3 carries with it a carriage 9, a bearing ring 5, which slides along the rails 13, pulling the membrane 6 onto the stationary stamp 2, while the ring 5 is pulled onto the stationary stamp 2 after disconnecting from the magnets 16.

Alternatively, ring 5 may be mounted by mechanical or pneumatic control means regardless of the movement of the movable die 3.

At this point, a reduced position is reached in which cavity 4 is formed, which is then filled with ground ceramic powders.

In order to optimize the shape of the cavity 4 and thereby improve its subsequent filling with ceramic powders, the membrane 6 is made so that it is completely attached to the fixed stamp 2 by creating a stationary stamp 2 of vacuum through the porous material before loading the ceramic powders.

When the optimum position for loading the cavity is reached, ceramic material is introduced, as is known in the art, to form a decorated plate according to the invention.

Simultaneously with the loading of the mold with ceramic material, the carriage 9 returns the upper connecting devices, not bearing the ring 5 with the membrane 6, to a position above the dies 2, 3 so that they can accept the new ring 5 with the decorated membrane 6, while the lower connecting devices located at cavity level 4.

At the end of loading, the isostatic stamp 3 compresses the powders in the cavity at high pressure until a decorated unfired plate is obtained.

Then the isostatic movable die 3 is diverted from the stationary die 2 and the magnets 16 of the lower connecting devices extract the ring 5 that has just been used, with the membrane 6.

After that, the carriage 9 moves vertically downward, carrying with it a new ring 5 with a decorated membrane 6 corresponding to the form for stamping. At the same time, lower connecting devices moving the ring 5 with the already used membrane 6, which must be disconnected, move down from the dies 2, 3.

To facilitate the detachment of the ring 5 with the membrane 6 from the magnets 16 of the lower connecting devices, a pair of parallel parallel to each other curved ribs 17 located in the bottom so as to interact with a pair of wheels 18 connected to the rods 15 is used to invert the ring 5 with the used membrane 6.

It is important that when the upper connecting devices move the ring 5 with the decorated membrane 6 to the mold, the lower connecting devices move downward until the wheels 18 slide along the ribs 17 so as to rotate the rods 15 of the carriage 9 and turn the ring 5 with the already used membrane 6. The ring 5 with the used membrane 6 is moved using suitable removal devices, not shown in the drawings, which return these elements to the node where the decoration of the membrane is performed, indicated The second unit interacts with the feed system.

The described cycle is repeated for the manufacture of each decorated product. In accordance with the cycle, the upper connecting devices receive the ring 5 with the decorated membrane 6 and move them to the die for stamping, while the lower connecting devices, after the product is molded, take the ring 5 with the used membrane 6 and move them to the removal devices.

The whole production process and related movements can be easily controlled automatically, which reduces the cost of forming and decorating plates.

If the press dies are moved relative to each other in the vertical direction, other devices for supporting and moving are used to move the rings 5 with the membranes 6.

As is clear from the description, the method and press for the simultaneous molding and finishing of ceramic products according to the present invention satisfy the requirements and overcome the disadvantages given in the introduction to this description with respect to the prior art.

In this regard, since the decoration of the side on which the drawing is applied and the molding of the products occur simultaneously, the total production time and, consequently, the cost of the products are significantly reduced.

The method and press of the present invention also allows you to achieve the following:

to perform an aesthetically attractive finish, since the pattern at least partially penetrates the base ceramic material, which allows you to get a smooth pattern and almost the effect of a three-dimensional image,

to finish any surface without restrictions imposed by the shape, which may contain concave and convex sections, and without restrictions in the colors used.

We can not ignore the fact that the patterns (finish) obtained using the method and press of the present invention are characterized by increased wear resistance and resistance to acids, since the pattern is located under the glaze.

A person skilled in the art can make numerous modifications and various variations of the described method and press to meet special requirements, all of which, however, will be within the scope of protection of the present invention as defined in the claims below.

Claims (21)

1. A method for the simultaneous molding and finishing of ceramic products, in which the following steps are performed: a) the press (1), containing the first die (2) and the second die (3), made with the possibility of moving from the diluted position to the reduced position, is put in a ready state in which the molding cavity (4) is formed, and vice versa b), a frame (5) is fitted onto the first die (2), provided with an elastically deformable membrane (6), so that it is located in the cavity (4), and the membrane ( b) partially covered with material used for finishing scrap, which is deposited on the side of the membrane that faces the second die (3), c) bring the press (1) into the reduced position, while the frame (5) remains on top of the first die (2), d) is loaded into the cavity (4 ) the ceramic material and is pressed to form the product, while the membrane (6) is located between the first die (2) and the ceramic material so that the material used for finishing is transferred directly from the membrane (6) to the ceramic material, e) the press is returned ( 1) in a divorced position and remove the decorated e ceramic product and frame (5). 2. The method according to claim 1, characterized in that the first stamp (2) is made of porous material. 3. The method according to claim 2, characterized in that prior to performing step c) that side of the membrane (6) that does not contain the material used for finishing is brought into a state of attachment to the first stamp (2) by means of a vacuum created through the first stamp ( 2). 4. The method according to claim 1, characterized in that the second stamp (3) is an isostatic type stamp. 5. The method according to claim 4, characterized in that the second die (3) performs pressing according to step d) by means of a liquid supplied under pressure placed behind an elastic wall. 6. The method according to claim 1, characterized in that the material used for decoration contains paints for ceramics. 7. The method according to claim 6, characterized in that the ceramic inks are applied to the membrane (6) by means of silk-screen printing. 8. The method according to claim 7, characterized in that the ceramic paints applied to the membrane (6) are exposed to a steam jet before the frame (5) is pulled onto the first die (2). 9. The method according to claim 1, characterized in that the ceramic material loaded in stage d) is in the form of a crushed powder. 10. The method according to claim 1, characterized in that during the loading of the ceramic material in step d), the cavity (4) is placed under vacuum, removing the air contained in the ceramic material. 11. The method according to claim 1, characterized in that the ceramic material pressed in stage d) is subjected to a pressure of about 400 bar. 12. The method according to claim 1, characterized in that the decorated ceramic product obtained in stage d) is subjected to final glazing so that the pattern will be located under the glaze. 13. System for the simultaneous molding and finishing of ceramic products, containing a press containing the first stamp (2) and the second stamp (3), made with the possibility of moving from the diluted position to the reduced position in which the forming cavity (4) is formed, and vice versa, elastically deformable membrane (b) and devices for tensioning the membrane (6) on the first die (2), characterized in that the membrane (6) is supported by the frame (5), while the system contains devices for tensioning and holding the frame (5), aligned regarding iju to the first stamp (2) and a second punch (3) when they are in the position information, so that the membrane is positioned in the cavity (4), which is subjected to compressible ceramic material used for forming the decorated article. 14. The system according to item 13, wherein the first stamp (2) is made of porous material. 15. The system according to 14, characterized in that the system for suctioning air is connected with the first stamp (2) and serves to create a vacuum between the stamp and the membrane stretched over it (6). 16. The system according to item 13, wherein the second stamp (3) is an isostatic type stamp. 17. The system according to item 13, wherein the membrane (6) is made of elastic silicone or polyurethane. 18. The system according to item 13, wherein the devices for tensioning the membrane (6) on the first stamp (2) contain a carriage (9), which can slide both in the direction perpendicular to the direction of movement of the stamps (2, 3), and parallel to the direction of their movement, the carriage (9) contains the first and second connecting devices, the first connecting devices being installed in order to receive the decorated membrane (6) and placing it in the molding cavity (4), and the second connecting devices are installed To order to receive the used membrane (6) from the cavity (4) and move it to devices for removal. 19. The system according to p. 18, characterized in that the first and second connecting devices contain a system for capturing the type of magnet (16). 20. The system according to p. 18, characterized in that the second connecting devices are equipped with a pair of wheels (18) located so as to interact with curved ribs (17) so as to turn the membrane (6) before moving it to the removal devices.
Priority on points: 08/02/2004 according to claims 1-20.

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