AT18602U1 - Method for the production of roof tiles using a rapid firing process - Google Patents

Abstract

According to a first aspect, the invention relates to a method for manufacturing a clay roof tile (1), comprising the following steps: providing the moist, unprocessed clay (1); generating an aqueous clay suspension (2); separating an oversize fraction from the suspension (2), wherein the oversize fraction comprises grains whose grain diameter exceeds a defined value; granulating the suspension (2) to produce clay granules (3); introducing the clay granules (3) into a press mold (20); pressing the clay granules (3) in the press mold (20), whereby the clay granules (3) are compacted and formed into a roof tile blank; transferring the roof tile blank into a roller kiln; and firing the roof tile blank in a rapid firing process.

Description

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Description

METHOD FOR THE MANUFACTURING OF ROOF TILES USING THE RAPID FIRING PROCESS

[0001] The invention relates to a method for manufacturing a roof tile, a system for carrying out the method, and a roof tile obtained by the method.

STATE OF THE ART

[0002] Roof tiles are typically manufactured using a wet pressing process. In this process, clay and/or loam are extracted from a pit, then mixed and prepared for pressing. The prepared clay mixture is first extruded into a continuous clay strand using an extrusion press. The clay strand is then cut into so-called slabs. In a rotary press, into which plaster molds are inserted for shaping the top and bottom surfaces of the roof tile, the slab is given a shape corresponding to the roof tile. After pressing, the roof tile preform already exhibits a so-called green strength, which allows it to be removed from the plaster mold, stacked on drying racks, and thus dried. Drying the roof tile preforms serves to reduce the moisture content of the clay before firing; it typically takes place over a period of 24 to 36 hours at a temperature between 80°C and 120°C. Following drying, the roof tile preforms are placed on ceramic firing trays. The preforms, along with the firing trays, are stacked on kiln cars and transported to the tunnel kiln, where they are fired at temperatures between 980°C and 1100°C for at least 24 hours.

[0003] Wet pressing processes have the disadvantage that the water bound in the clay mixture must escape from the clay and the press mold. If this does not happen, the water can leave pores in the fired roof tile, which reduce the weather resistance of the roof tile. The press molds are therefore made of gypsum, which can absorb water due to its hygroscopic properties. In addition, however, it is necessary to equip the gypsum press molds with drainage pipes. The production of the press molds from gypsum is labor-intensive and therefore expensive. Since the gypsum quickly becomes saturated with moisture, the service life of the press molds is short, which leads to frequent production stoppages, as the press molds of the rotary press must be replaced regularly.

[0004] The moisture remaining in the roof tile mold must be further reduced before firing, because otherwise the water evaporating during firing leaves too many pores in the fired roof tile, which reduces the weather resistance of the roof tile. The pressed roof tile molds are therefore transferred to drying frames and placed in the drying process. During transfer, the roof tile molds must not be subjected to mechanical stress, as this can lead to undesirable deformations. The roof tile molds can also warp or develop drying cracks during the drying process. The molds must therefore be handled with appropriate care, which in turn entails additional process engineering effort.

[0005] Energy consumption in roof tile production is very high due to the drying and firing processes and the long duration of these two processes. Since the tunnel kilns are operated with natural gas, high CO emissions are also generated. From an energy perspective, it is also disadvantageous that a large mass of firing aids (firing cassettes and kiln cars) is introduced into the tunnel kiln. The firing aids have a high heat capacity, and significant heat losses occur due to the heating and subsequent cooling of the firing aids.

[0006] To eliminate some of the disadvantages of the wet pressing process, DE 195 26 849 A1 proposes to manufacture roof tiles using the dry pressing process. In this process, the clay coming from the pit is conveyed via feeders, edge runner mills, roller mills and mixers to an intermediate storage area.

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The process involves processing this prepared, opened, earth-moist clay into granules. Thin strands of clay are first extruded, then cut into small shapes after exiting the extruder and coated with dry clay dust, resulting in moist clay granules with an enormous surface area. The aim is to produce a pre-dried, free-flowing, yet still malleable granulate, which is then pressed into a green roof tile. However, this method is very difficult to implement in practice.

[0007] Because the water is removed before the pressing process, most of the shrinkage occurs in the granules themselves and not, as is usual with wet pressing, during the drying of the roof tile molds. Therefore, drying defects that could manifest as warping during firing of the roof tiles no longer occur.

[0008] However, the dry pressing process known from the prior art has the disadvantage that the described granulate production is associated with a high degree of process engineering complexity. In addition, the many individual steps entail high investment and operating costs for the corresponding machines and equipment.

TASK

[0009] The invention is based on the objective of creating a method and a plant for the production of roof tiles, wherein the method has low energy consumption and the lowest possible CO2 emissions, and wherein high-quality roof tiles can be produced with the plant at low manufacturing costs and short production times.

DESCRIPTION OF THE INVENTION

[0010] The main features of the invention are specified in claim 1. Embodiments are the subject of claims 2 to 12.

[0011] According to the invention, the problem is solved by a method for manufacturing a roof tile-

gels dissolved from clay, the process comprising the following steps:

- Providing the moist, untreated clay;

- Creating an aqueous clay suspension;

- Separation of an oversize fraction from the suspension, wherein the oversize fraction comprises grains whose grain diameter exceeds a defined value;

- Granulation of the suspension to produce clay granules;

- Placing the clay granules into a press mold;

- Pressing the clay granules in the press mold, whereby the clay granules are compacted and formed into a roof tile shape,

- Transferring the roof tile mold into a roller kiln and

- Firing of the roof tile mold in a rapid firing process with reduced CO2 emissions.

[0012] In this context, a rapid firing process is understood to be a firing process in which one or more roof tile molds are fired for a maximum of 4 hours at temperatures between 950° and 1100°C. The process according to the invention preferably involves preparing the clay for further processing by dry pressing. Due to the low moisture content of the clay granules, steel molds with long service lives can be used during pressing, thus eliminating the need for time-consuming and energy-intensive drying of the roof tile molds before firing. Since the roof tile molds already exhibit high dimensional stability after pressing, they can be fired in a roller kiln without firing aids. Consequently, the energy losses that occur in tunnel or chamber kilns due to the heating and cooling of firing aids are eliminated. The term “dry pressing” refers to a pressing process step in which the pressed roof tile blank has a moisture content of 20% or less, preferably 10% or less and particularly preferably 4% or less after the pressing process.

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[0013] The clay can be supplied from a single pit (“single source” clay). Due to the lesser importance of plastic properties for the process according to the invention, it is not necessary to adjust the clay mixture from several clays.

[0014] It is conceivable that the step of introducing the clay granules into the mold is followed by the step of removing the excess granules from the mold. Furthermore, it is conceivable that the clay granules are introduced into the mold using a filling frame, and/or that the clay granules are introduced into the mold by blowing the granules into the mold, and/or that the clay granules are introduced into the mold by suction.

[0015] According to the invention, the roof tile blanks are fired in a roller kiln using a so-called rapid firing process, in which the firing times for roof tiles range from one to four hours. The shorter firing times compared to conventional firing processes result in reduced energy consumption and thus a reduction in CO2 emissions. Furthermore, significant time and cost savings are achieved. Due to the small tonnage in the firing chamber, it is also possible to start or stop the firing process at short notice, thus enabling flexible operating times. This makes it possible, for example, to avoid costly production times such as weekends or holidays, because the roller kiln can be quickly ramped up and down.

[0016] Roof tiles are usually fired in tunnel or chamber kilns. In this process, a large number of brick molds are stacked on appropriately heat-resistant cassettes to form a unit and fired in the kiln for a period of at least 16 hours. This process requires a sufficiently large firing chamber, which in turn results in poor heat distribution and also requires a high energy consumption. Furthermore, starting up and shutting down the kiln, i.e., heating and cooling it down, takes a considerable amount of time, which makes flexible use of the kiln difficult. In contrast, a roller kiln uses a single-layer firing process. The firing channel of the kiln is dimensioned as small as possible in order to increase the kiln's firing power and thus fire the material more quickly. At the same time, the firing chamber should be as small as possible in relation to the required output. Only the breaking load of the rollers represents a limiting factor here.

[0017] The use of a roller kiln also has the advantage that roller kilns can be operated in a climate-neutral manner compared to kilns typically used in brickmaking, such as tunnel or chamber kilns. For example, the roller kiln can be operated electrically or with hydrogen. Tunnel kilns are very difficult to operate with hydrogen or electricity.

[0018] It is also conceivable that the process includes a quality control step after the step of pressing the clay granules into roof tile molds. In this step, defective or unsatisfactory molded pieces can be returned to the suspension production process and reprocessed there. The quality control step can be carried out, in particular, on a random sample basis.

[0019] The pressing process preferably takes place in a press mold, which may have a first mold half and a second mold half. The mold halves can be designed to be movable relative to each other between a pressing position, in which the mold halves essentially define a receiving space that replicates the shape of the finished roof tile, and a filling position, in which the mold halves are spaced apart from each other and a plastically deformable molding compound can be poured into the first and/or the second mold half. The first mold half and/or the second mold half have at least one recess that replicates a projection of the finished roof tile mold, wherein a first pressure element is provided in and/or on the recess, which is designed to be movable between an initial position, in which the first pressure element is set back with respect to the shape of the finished roof tile mold, and a compaction position, in which the first pressure element partially replicates the surface of the roof tile mold. The process for pressing the roof tile therefore additionally includes the following steps:

- Providing the press mold, with the mold halves in the filling position and at least

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a first pressure element is in the starting position,

- Pouring the clay granules into the recording chamber,

- Moving the mold halves into the pressing position, thereby compacting the clay granules,

- Moving at least one pressure element into the compaction position, compacting the clay granules in the area of the first pressure element.

[0020] Because the first pressure element is moved into its compaction position after the mold is closed, the clay granules are further compacted by the first pressure element in areas where sufficient compaction is not achieved solely by moving the mold halves, for example, in the recesses that form the projections of the finished roof tile. This increases the strength of the roof tile in these areas, resulting in a roof tile with greater strength and resistance to external influences. This further compaction can be achieved mechanically, semi-isostatically, and/or isostatically.

[0021] During compaction, the pressure element presses into the surface of the roof tile mold, thereby embossing the surface of the roof tile in the compacted areas. The embossing gives the roof tile a characteristic appearance and is retained even after firing. Depending on the number, size, and arrangement of the pressure elements used, different embossing patterns are therefore created on the surface of the roof tile.

[0022] The aforementioned projections can be located on the top and/or bottom of the roof tile mold. The roof tile mold can, for example, have a head and side interlock on its top surface and be provided on its bottom surface with hooks, stacking points, batten protectors and stiffening ribs.

[0023] After completion of the pressing process, the first pressure element is preferably moved to its starting position, allowing the pressed roof tile to detach from the respective mold half in the area of the recesses and simplifying demolding. The mold halves are then moved into the filling position and the roof tile is removed from the press mold. This reduces the risk of damage to the pressed roof tile during removal from the press mold due to the roof tile adhering to one of the mold halves.

[0024] Preferably, a guide is provided for the first and/or the second mold half, wherein the guide, together with the mold halves, completely delimits the receiving space in the filling position and in the pressing position. The guide can have several guide parts and can be moved into a demolding position before the mold halves are opened. Clay exhibits a relatively large degree of shrinkage in the dry pressing process. The shrinkage is approximately 0.7% to 1.0%. If the press mold is opened within the guide that laterally delimits the receiving space to remove the pressed roof tile, the pressed roof tile expands and becomes jammed within the guide, which can damage the pressed roof tile or make it more difficult to remove from the press mold. To avoid such problems, the guide is moved laterally, i.e. parallel to the extension direction of the mold halves, into a demolding position spaced apart from the mold halves, in which the pressed roof tile mold cannot touch the guide even if the clay granules expand backwards, so that the roof tile mold can expand in the extension direction essentially parallel to the surface of the mold halves.

[0025] At least one second pressure element can be provided on the surface of the first and/or the second mold half, which is movable between an initial position in which the second pressure element projects forward or is recessed with respect to the shape of the finished roof tile mold, and a compression position in which the second pressure element partially forms the surface of the mold of the roof tile mold, wherein the second pressure element moves to the compression position during or after moving the mold halves into the pressing position or back to the initial position after completion of the pressing process.

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This second pressure element allows, for example, for further compaction of the clay material outside the depressions.

[0026] Preferably, the second pressure element is coupled to a first pressure element provided in the recess. The movement of the second pressure element from the protruding position to the compression position forces the first pressure element from the recessed position into the compression position. In this embodiment, the second pressure element is used to move the first pressure element into the compression position. The second pressure element can be used as a control element. Preferably, however, the first and second pressure elements are hydraulically coupled, so that the pressure acting on the second pressure element moves the first pressure element into the compression position.

[0027] The coupling of the first and second pressure elements enables simpler control of the movement of the first and second pressure elements between their respective starting positions and their respective compression positions. When the mold halves are moved into the pressing position, the clay material exerts pressure on the second pressure element, which moves the second pressure element into the compression position. The movement of the second pressure element into the compression position also moves the first pressure element, which is coupled to the second pressure element, into the compression position, so that no separate control is required for the first pressure element.

[0028] Furthermore, the roof tile preform can be easily demolded from the mold. For example, in its initial position, the second pressure element protrudes above the mold of the finished roof tile preform and is moved into the compression position by the increasing pressure when the mold halves are moved into the pressing position. The coupling of the first and second pressure elements moves the first pressure element into the compression position. When the mold is opened, i.e., when the mold halves are moved into the filling position, the pressure on the second pressure elements is reduced, allowing them to move back into their protruding position. This lifts the pressed roof tile preform and releases it from the surface of the mold. Simultaneously, the first pressure element, coupled to the second pressure element, is moved back into its initial position, which is set back relative to the shape of the roof tile. This allows the roof tile preform to detach from the respective mold half, even in the area of the recess. Overall, the roof tile then adheres not at all or only minimally to the respective mold half, thus reducing the risk of damage when removing the roof tile.

[0029] Preferably, several first pressure elements and/or several second pressure elements are provided, wherein the first pressure elements and/or the second pressure elements are coupled to each other and/or to each other. Sufficient compaction of the clay material can be achieved with one pressure element. If several, preferably small-area, pressure elements are used, the compaction can be better controlled, or the pressing process can be controlled such that the compaction takes place in a defined area with a defined pressure on the clay material.

[0030] According to a preferred embodiment, the pressure elements are designed such that a compaction of the clay granules of approximately 2:1 can be achieved. This means that the initial volume of the clay granules can be reduced by half using the pressure elements preferred here. For this purpose, the pressure elements can be made of a correspondingly hard and durable material, which should also have the same expansion properties as the material of the mold halves. Preferably, the pressure elements can be made of steel, for example.

[0031] After the clay granules have been poured in, the mold halves can be moved into a venting position between the filling position and the pressing position, in which air contained in the receiving chamber can escape from the receiving chamber.

[0032] In the preparation of the suspension and thus at the beginning of the process according to the invention-

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The process may also include the separation of the undersized and oversized fractions using a sieve or filter. Specifically, it is intended that this separation is carried out using a wet sieving process. A wet sieving process allows unwanted particle sizes to be removed from the suspension without the need for prior drying. Furthermore, wet sieving prevents clogging of the sieve mesh, which can occur with dry sieving processes when dealing with small particle sizes. Alternatively, separation can be carried out using a centrifuge or a cyclone separator.

[0033] According to a further aspect of the invention, a plant for the production of a roof tile using the method according to the invention is provided. The plant comprises in particular a feeding device for supplying unprocessed clay, a mill for producing a suspension, a granulating device for producing clay granules, a press for dry-pressing the clay granules into a roof tile form, and a roller kiln for carrying out a rapid firing process.

[0034] A crushing device can also be provided for pre-crushing the unprocessed clay material into clay pieces of a defined size, wherein the crushing device can be located upstream of the mill or can also be part of the mill. The mill can be a pendulum mill, a roller mill, or a stirred ball mill. Optionally, the mill can have a sorting device for separating excess material (for example, undersized and oversized fractions), wherein the sorting device can primarily comprise a screen.

[0035] Preferably, the system also includes a glazing unit suitable for processing the surfaces of the roof tile molds. The molds can thus be glazed, embossed, coated, or engobed in the glazing unit.

[0036] According to another aspect, the invention relates to a clay roof tile which has been produced using the method described herein.

FIGURE DESCRIPTION

[0037] Further features, details and advantages of the invention will become apparent from the wording of the claims and from the following description of exemplary embodiments with reference to the drawings. The drawings show:

[0038] Fig. 1 shows a schematic representation of a system for the production of a clay roof tile;

[0039] Fig. 2 shows a flow diagram of a method for producing a clay roof tile according to a first embodiment;

[0040] Fig. 3 shows a flow diagram of a method for producing a clay roof tile according to a second embodiment;

[0041] Fig. 4a shows a press mold for producing a roof tile according to a preferred embodiment in a filling position;

[0042] Fig. 49 shows the press mold from Fig. 4a in the closed press position.

[0043] Fig. 1 shows a schematic representation of a plant 10 for the production of a roof tile from clay 1. The plant 10 shown is particularly suitable for carrying out the process according to the invention. The exemplary plant 10 from Fig. 1 comprises a feeding device 11, which supplies the untreated pit clay to a mill 12. In the mill 12, a suspension 2 is produced from the clay. According to the process described here, the undersized and oversized fractions can also be removed in the mill.

[0044] The processed suspension 2 is then fed to the granulation device 13, which converts the suspension 2 into clay granules 3 with a defined moisture content. As shown in Fig. 1, the granulation device 13 can, for example, be a spray dryer.

[0045] The system 10 from Fig. 1 also includes an intermediate storage unit 14, which is used for spoke-

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The intermediate storage facility 14 is designed for the drying and drying of the clay granules 3. Preferably, the intermediate storage facility 14 is one or more silos.

[0046] As a further machine section, the system 10 includes a press 20 for dry-pressing the clay granules 3 into a roof tile mold. Finally, the pressed roof tile molds are transferred to a roller kiln 16, which is suitable for firing the tile molds in a rapid firing process, i.e., in less than 4 hours.

[0047] As shown in Fig. 1, the system 10 can also include a glazing unit 15. There, the molded parts can be glazed, embossed, coated or printed (e.g. “digital printing”) and/or engobed before being fired in the roller kiln 16.

[0048] Fig. 2 shows in a flowchart the steps S1-S8 of the inventive method for producing a roof tile from clay 1 according to a first embodiment.

[0049] First, step S1 is carried out: providing the moist, unprocessed clay 1. Advantageously, the clay 1 is delivered to the plant 10 from a nearby pit. In this way, long transport routes and the associated costs can be avoided or reduced. Due to the minor importance of plastic properties, it is not necessary to adjust the clay mixture from several clays.

[0050] Upon arrival at plant 10, the untreated pit clay 1 can be directly processed into an aqueous suspension 2 in mill 12 according to step S2. Among other advantages, the suspension 2 is easier to homogenize than dry clay granules 3. Furthermore, the subsequent sorting processes are also easier to carry out compared to conventional methods when the clay 1 is in the form of an aqueous suspension 2. The conditioning of the starting material to a suspension 2 is preferably carried out by adding water and using solvents and agitators, which can be integrated into mill 12. At the end of step S2, the suspension 2 preferably has a solids content of 55% to 65%.

[0051] Following this, step S3 is carried out: separating an oversize fraction from the suspension 2, wherein the oversize fraction comprises grains whose grain diameter exceeds a defined value. Ideally, the grain size of the subsequent granules 3 should be between 120 µm and 1000 µm. To ensure this, grains with a diameter greater than 1000 µm are separated from the suspension 2. In a further step S3.1 (see Fig. 3), grains with a diameter smaller than 120 µm can also be separated from the suspension 2.

[0052] After separating oversized and/or undersized particles from the suspension 2, step S4 follows: granulating the suspension 2 to produce clay granules 3. To obtain the best possible pressing result, the clay granules 3 should have a residual moisture content of 2% to 6%. This prevents shrinkage of the roof tile molds during the pressing process. The granulation process S2 can be carried out, for example, by spray drying or atomization in a suitable granulation device 13.

[0053] Next comes step S5: introducing the clay granules 3 into a press mold 20. To produce the roof tile blanks, the clay granules 3 obtained from step S4 are preferably injected under pressure into the press mold 20 of the system. Immediately following this, step S6 takes place: pressing the clay granules 3 in the press mold 20, whereby the clay granules 3 are compacted and formed into a roof tile blank. Once the desired quantity of clay granules 3 has been introduced into the press mold 20, the mold halves of the press mold 20 are moved from the filling position to the pressing position, in which the press mold 20 forms the shape of the finished roof tile.

[0054] The next step S7 comprises the following: transferring the roof tile preform into a roller kiln 16 for firing the roof tile preform. In the last step S8, the roof tile preform is then fired into a roof tile using a rapid firing process. The firing process according to S8 is preferably carried out in a single-layer firing manner. This allows the highest possible proportion of the radiant energy from the kiln 16 to be used for heat transfer to the roof tiles.

7115

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[0055] Fig. 3 shows a flowchart comprising steps S1-S8 of the method for producing a roof tile from clay 1 according to a second embodiment. The method shown in Fig. 3 differs from the method shown in Fig. 2 in that the method according to Fig. 3 includes the additional intermediate steps S1.1, S2.1, S3.1 and S4.1.

[0056] Step S1.1 follows step S1 and comprises the following: breaking up clay slabs contained in clay 1 into clay pieces, wherein the clay pieces have an average diameter of 5 cm or less. Breaking or grinding up larger clay slabs into clay pieces that are on average smaller than 5 cm can, for example, be carried out in the mill 12 and serves to prepare the unprocessed material coming from the stockpile for the subsequent steps.

[0057] Step S2.1 follows step S2 and comprises the following: adding additives to the suspension 2. The additives facilitate the homogenization of the suspension 2 and serve primarily to give the roof tiles their desired properties, for example to keep the solids content in the suspension as high as possible.

[0058] Step S3.1 follows step S3 and comprises the following: separating an undersized fraction from the suspension 2, wherein the undersized fraction comprises grains whose grain diameter exceeds a defined value. Ideally, the grain size of the subsequent granules 3 should be between 120 µm and 1000 µm. To ensure this, grains with a diameter smaller than 120 µm are separated from the suspension 2. Step S3.1 can be performed simultaneously with step S3.

[0059] Step S4.1 follows step S4 and comprises the following: storing the clay granules 3 in at least one suitable intermediate storage facility 14. The intermediate storage facility 14 is preferably a silo. Storage in an intermediate storage facility 14 contributes to further homogenization of the granules 3, whereby, for example, slight moisture differences within the granules 3 can be equalized during this phase. The intermediate storage process can last from a few hours to several days, depending on the production requirements.

[0060] According to one embodiment, the firing channel of the kiln should advantageously be dimensioned as small as possible in order to increase the firing power of the kiln and thus enable faster firing of the material. A further advantage of the described method is that the resulting roof tile blanks can be fired without the usual firing aids (e.g., H- or U-cassettes) because they already possess sufficient dimensional stability from the dry pressing step. Accordingly, firing aids can be dispensed with, leading to space and cost savings, which also increases the firing efficiency of the kiln. The use of a roller kiln also has the advantage that roller kilns can be operated in a climate-neutral manner compared to conventionally used kilns in brickmaking. For example, the roller kiln can be operated electrically or using hydrogen.

[0061] In Fig. 4a, the press mold 20 is shown in a filling position in which the mold halves 22, 24 are spaced apart from each other and a clay material can be filled into the receiving chamber. A filling device 42 is provided for filling the press mold 20, which can inject the clay material into the receiving chamber 30 by means of compressed air under overpressure. The injection takes place in an injection direction E essentially parallel to the surface 34, 38 of the first and second mold halves 22, 24, respectively.

[0062] From the filling position shown in Fig. 4a, the mold halves 22, 24 can be moved towards each other in a pressing direction P to the pressing position shown in Fig. 4b, in which the receiving chamber 30 essentially replicates the shape of the roof tile 18. One of the mold halves 22, 24 can be fixed in place, so that only the other mold half 22, 24 is moved. However, it is also possible for both mold halves 22, 24 to be moved and to be moved towards each other during the pressing process of the roof tile 18. The guide elements 28 are arranged in a removal direction R that is essentially perpendicular to the pressing direction P.

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The removal position is movable, in which the guide elements 28 are spaced apart from the mold halves 22, 24. The mold halves 22, 24 each have a base body 44, 46 made of steel, preferably tool steel. Furthermore, the surfaces 34, 38 each have a coating 48, 50, which in the embodiment shown here is formed from a PU layer. The coating 48, 50 reduces the adhesion of the filled clay material to the surfaces 34, 38 of the mold halves 22, 24.

[0063] A first pressure element 52 is provided in or on the recess 40. This pressure element is formed by a pressure pad that has a pressure chamber 58 filled with an incompressible pressure medium 56. The first pressure element 52 has a pressure line 60 through which the pressure medium 56, for example oil, can flow into and out of the pressure chamber 58. The first pressure element 52 is located at the base of the recesses 40, i.e., at the transition to the surface 38 of the second mold half 24 facing the first mold half 22.

[0064] A second pressure element 62 is further provided on the surface 38 of the second mold half 24, the structure of which essentially corresponds to the structure of the first pressure element 52. The second pressure element 62 has a pressure chamber 64 and a pressure line 66, which are filled with the pressure medium 56.

[0065] The pressure line 66 of the second pressure element 62 is connected to the pressure line 58 of the first pressure element 52, so that the pressure medium 56 can flow between the first and the second pressure elements 52, 62. Furthermore, the pressure lines 60, 66 are connected to a pressure generating device 68, which can supply the pressure medium 56 and/or adjust the pressure in the pressure lines 60, 66 or the pressure elements 52, 62. Preferably, the pressure medium 56 has an overpressure of approximately 5 Pa to 7 Pa. The pressure elements 52, 62 are each formed by a recess 70, 72 in the base body 46 of the second mold half 24 and the coating 50, which is designed as a membrane.

[0066] In the filling position according to Fig. 4a, the second pressure element 62 is in a starting position inclined towards the receiving space 30, thus projecting beyond the shape of the finished roof tile 18 (dashed line). The first pressure element 52 is in a starting position set back from the shape of the finished roof tile 18 in the filling position.

[0067] The first and the second pressure element 52, 62 are coupled to each other by the pressure lines 60, 66 in such a way that the first pressure element 52 is moved outwards into a compression position by the pressure medium 56 flowing out of the second pressure element 62 and into the first pressure element 52, in which the first pressure element 52 also forms a section of the shape of the finished roof tile (see Fig. 4b).

[0068] The invention is not limited to one of the embodiments described above, but can be modified in many different ways.

[0069] All features and advantages arising from the claims, the description and the drawing, including design details, spatial arrangements and process steps, can be essential to the invention both individually and in various combinations.

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REFERENCE MARK LIST

Sn step n

1 tone

2 Suspension

3 Clay granules

10 Annex

11 Feeding device 12 Mill

13 Granulation unit 14 Intermediate storage

15 Glazing unit 16 Roller kiln

18 roof tiles

20 Press mold

22 First half of the mold 24 Second half of the mold 26 Guidance

28 guide elements 30 recording room

34, 38 surface

40 In-depth study

42 Filling device

44, 46 Basic body

48, 50 coating

52 First printing element 56 Printing medium

58, 64 Printing chamber

60 Pressure line

62 Second printing element

70, 72 recess

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Claims (12)

A hes AT 18 602 U1 2025-12-15 Ss N Claims 1. Method for manufacturing a clay roof tile (1), comprising the following steps: (S1) Providing the moist, untreated clay (1); (S2) Producing an aqueous clay suspension (2); (S3) Separation of an oversize fraction from the suspension (2), wherein the oversize fraction comprises grains whose grain diameter exceeds a defined value; (S4) Granulating the suspension (2) to produce clay granules (3); (S5) Place the clay granules (3) into a press mold (20); (S6) Pressing the clay granules (3) in the press mold (20), wherein the clay granules (3) are compacted and formed into a roof tile mold; (S7) Transferring the roof tile mold to a roller kiln and (S8) Firing of the roof tile preform in a rapid firing process. 2. The method of claim 1, characterized in that the method according to step ($S1) further comprises the following step: ($1.1) Breaking clay slabs contained in the clay (1) into clay pieces, wherein the clay pieces have a mean diameter of 5 cm. 3. Method according to one of the preceding claims, characterized in that the method according to step (S2) further comprises the following step: (S2.1) Addition of additives to the suspension (2). 4. Method according to one of the preceding claims, characterized in that the method prior to step (S3) further comprises the following step: (S$S3.1) separating an undersized fraction from the suspension (2), wherein the undersized fraction comprises grains whose grain diameter falls below a defined value. 5. Method according to one of the preceding claims, characterized in that the method according to step (S4) further comprises the following step: (S4.1) Storing the clay granules in at least one suitable intermediate storage facility (15), in particular a silo. 6. Method according to one of the preceding claims, characterized in that the aqueous suspension (2) has a solids content of 20% to 70%, in particular 55% to 65%, before granulation. 7. Method according to one of the preceding claims, characterized in that the grains of the oversize fraction each have a grain diameter greater than 1000 µm. 8. Method according to one of claims 4 to 7, characterized in that the grains of the undersized fraction each have a grain diameter that is less than 100 µm. 9. Method according to one of the preceding claims, characterized in that the clay granules (3) have a moisture content of less than 15%, in particular of 1% to 11%, after granulation of the suspension (2). 10. Method according to one of the preceding claims, characterized in that the pressing of the clay granules (3) is carried out by dry pressing. 11. Method according to one of claims 4 to 10, characterized in that the separation of the undersized fraction and the oversized fraction is carried out in a sieving process. 12. Method according to one of the preceding claims, characterized in that step (S1.1) is carried out in a pendulum mill or in a roller mill. This includes 4 sheets of drawings.