NL2036211A - Process for manufacturing roof tiles using the quick-fire method - Google Patents

Abstract

Main illustration: Fig. 1 According to a first aspect, the invention relates to a method for the production of a roof tile from clay (1), which comprises the following steps: providing the moist, unprocessed clay (1); producing an aqueous clay suspension (2); separating an excessively large fraction from the suspension (2), wherein the excessively large fraction consists of grains whose grain diameter is larger than a defined value; granulating the suspension (2) to produce a clay granulate (3); placing the clay granulate (3) in a press mold (14); pressing the clay granulate into the pressing mold (14), whereby the clay granulate (3) is compressed and formed into a roof tile shape; place the roof tile mold in a roof oven; and quickly bake the roof tile shape. According to another aspect, the invention relates to an installation (10) for the production of a roof tile and to a roof tile. 15

Description

Process for manufacturing roof tiles using the quick-fire method

The invention relates to a method for producing a roof tile, an installation for carrying out the method and a roof tile obtained by the method.

State of the art

Roof tiles are usually manufactured using a wet pressing process. In this process, clay and/or loam is extracted from a quarry, then mixed and prepared for the pressing process. An endless clay column is first extruded from the prepared clay mixture via an extrusion press. The clay string is then cut into so-called chunks. In a revolver press, in which plaster molds are placed to form the top and bottom of the roof tile, the lump is then given a shape that corresponds to the roof tile.

After the pressing process, the roof tile shape already has a so-called green strength, which means that the roof tile shape can be removed from the plaster press mold, stacked on drying frames and thus dried. Drying of the roof tile molds serves to reduce the moisture content of the clay for the firing process and usually takes place over a period of 24 hours to 36 hours at a temperature between 80°C and 120°C. After drying, the roof tile molds are placed on ceramic baking cassettes. The roof tile molds are stacked on oven trolleys together with the baking cassettes and transferred to the tunnel oven, where the roof tile molds are fired at temperatures between 980°C and 1100°C for a period of at least 24 hours.

Wet pressing has the disadvantage that the water bound in the clay mixture must escape from the clay and from the pressing mould. If this is not done, the water can leave pores in the fired roof tile that reduce the weather resistance of the roof tile. The molds are therefore made of plaster, which can absorb water due to its hygroscopic properties. However, it is also necessary to equip the plaster molds with drainage pipes. The production of plaster molds is labor intensive and therefore expensive. Because the plaster soaks quickly, the life of the molds is short, leading to frequent production stops because the turret press molds must be replaced regularly.

The moisture remaining in the roof tile mold must be further reduced before the baking process, because otherwise the water that evaporates during the baking process will leave 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 transferred to the drying process. The roof tile molds must not be mechanically loaded during transfer, as this can lead to unwanted deformation. The roof tile molds can also warp during the drying process or drying cracks can appear. The formed roof tiles must therefore be treated with the necessary care, which in turn requires a lot of process engineering.

The energy consumption in the production of roof tiles is very high due to the drying and baking process and the long duration of these two processes. Since the tunnel ovens run on natural gas, they also produce high CO emissions. Another energetic disadvantage is that a large mass of oven furniture (baking cassettes and oven trolleys) is brought into the tunnel oven. The oven furniture has a high heat capacity and heating and then cooling the oven furniture leads to significant heat losses.

To eliminate some of the disadvantages of the wet pressing process, DE 195 26 849 A1 proposes to produce roof tiles using the dry pressing process. In this process, the clay coming from the quarry is fed to an intermediate warehouse via feeders, tile bakers, rolling machines and mixers. This prepared, digested, earth-moist clay is then made into a granule by first extruding thin strings of clay, which, after leaving the extruder, are cut into small moldings and covered with dry clay grit to produce a moist clay granule with an extremely large surface area. In this way, a pre-dried, free-flowing but still plastic, malleable granulate is produced, which is pressed in a press into a green roof tile. However, this theory is very difficult to realize in practice.

Because the water has already been removed before the pressing process, a large part of the shrinkage already takes place in the granulate and not, as is usual with wet pressing, during the drying of the roof tile shapes. This means that there are no more drying errors that can cause deformation when the roof tiles are fired.

However, the dry pressing process known from the current state of the art has the disadvantage that the granulate production described there requires a lot of process engineering. In addition, the many individual steps entail high investment and operating costs for the associated machines and systems.

Goal

The invention is based on the aim of developing a process and a system for the production of roof tiles, where the process requires low energy consumption and the lowest possible

CO: emissions and the system can be used to produce high quality roof tiles at low production costs and short production times.

Description of the invention

The main features of the invention are set out in claims 1, 14 and 15.

Embodiments are the subject of claims 2 to 13.

According to the invention, the problem is solved by a method for producing a clay roof tile, the method comprising the following steps: - Providing the moist, untreated clay; — Generation of an aqueous clay suspension; — Separating an excess grain fraction from the suspension, wherein the excess fraction comprises grains whose grain diameter is greater than a defined value; — Granulation of the suspension to produce a clay granulate; — Applying the clay granulate in a pressing mould; — Pressing the clay granulate into the press mold, whereby the clay granulate is compressed and formed into a roof tile shape, — Transferring the roof tile shapes to a roller oven and — Baking the roof tile shapes in a fast baking process with reduced CO: emissions.

For the purposes of this disclosure, a rapid baking process is defined as a baking process in which one or more roof tile shapes are baked for a maximum of 4 hours at temperatures between 950 °C and 1100 °C. The method according to the invention preferably provides for clay preparation for further processing in a dry pressing process. The low moisture content of the clay granulate allows long-life steel molds to be used during pressing, making the time-consuming and energy-intensive drying of the roof tile molds before firing unnecessary. Because the roof tile shapes already have a high degree of dimensional stability after pressing, they can be baked in a roller oven without oven furniture. This means that the energy losses that occur in tunnel or chamber ovens due to the heating and cooling of the oven furniture can be avoided. The term "dry pressing" should be understood as a pressing step in which the pressed roof tile shape has a moisture content of 20% or less, preferably 10% or less and especially preferably 4% or less after the pressing process.

The clay can come from one well ("single source" clay). Coordination of the clay mixture from different clay types is not necessary due to the low importance of plastic properties for the process according to the invention.

According to the invention, the roof tile shapes are baked in a roller oven according to the so-called rapid baking process, whereby the baking times for roof tiles are between one hour and four hours. The shorter baking times compared to conventional baking processes lead to a lower energy requirement and therefore to a reduction in CO emissions. There are also significant time and cost savings. The low tonnage in the combustion chamber also makes it possible to start and stop the burning process at short notice, allowing for flexible operating times. This makes it possible, for example, to avoid cost-intensive production times such as weekends or holidays because the roller kiln can be quickly shut down and started up.

Roof tiles are usually fired in tunnel or chamber kilns. A large number of brick shapes are stacked on the appropriate cassettes to form a unit and baked in the kiln for at least 16 hours. This process requires a sufficiently large combustion chamber, which in turn leads to poor heat distribution and also costs a lot of energy.

In addition, starting and shutting down the oven, i.e. heating up and cooling down, takes a lot of time, which makes it difficult to use the oven flexibly. The roller oven, on the other hand, is baked in a single layer. The kiln's fire channel is designed to be as small as possible to increase the kiln's burning power and thus bake the material faster.

At the same time, the combustion chamber should be as small as possible in relation to the required output. The only limiting factor here is the breaking load of the rollers.

The use of a roller kiln also has the advantage that the roller kiln can be used in a climate-neutral manner compared to ovens that are normally used in brick kilns, such as tunnel kilns or chamber kilns. For example, the roller oven can operate electrically or on hydrogen.

Tunnel ovens are very difficult to operate with hydrogen or electricity.

It is also conceivable that the process includes a quality inspection step after pressing the clay granulate into roof tile shapes. Here, defective or unsatisfactory molded products can be returned to the suspension production process and reprocessed there. In particular, the quality inspection step can be carried out on a random basis.

The pressing process preferably takes place in a pressing mold, which can have a first mold half and a second mold half. The mold halves can be designed so that they can move relative to each other between a pressing position, in which the mold halves essentially define a receiving space that reproduces the shape of the finished roof tile, and a filling position, in which the mold halves are spaced apart and a plastically deformable molding mass can be filled into the first and/or second mold half. The first mold half and/or the second mold half have at least one cavity that reproduces a protrusion of the finished roof tile casting, in which a first pressure element is arranged in and/or on the cavity, which is designed to move between a home position in which the first pressure element is reset relative to the shape of the finished roof tile casting, and a compaction position, wherein the first pressure element reproduces the surface of the roof tile casting in portions. Accordingly, the method for pressing the roof tile additionally comprises the following steps: - Providing the pressing mold, wherein the mold halves are in the filling position and the at least one first pressing element is in the starting position, - Filling the clay granulate into the collection chamber, — Bring the mold halves into the pressing position, whereby the clay granulate is compressed, — Bring the at least one pressure element into the compaction position, whereby the clay granulate is compacted in the area of the first pressing element.

Because the first pressure element is brought into the compaction position after the pressing mold has been closed, the first pressure element ensures that the clay granulate is re-compacted in places where sufficient compaction is not achieved by simply moving the mold halves, for example in the recesses that support the protrusions of the to form a finished roof tile shape. This can increase the strength of the roof tile shape in these places, so that the roof tile shape is stronger and more resistant to external influences.

During compaction, the pressure element presses itself into the surface of the roof tile shape, providing relief to the surface of the roof tile in the post-compacted areas. The relief gives the roof tile a characteristic appearance that is retained even after the baking process.

Depending on the number, size and arrangement of the pressure elements used, different relief patterns are created on the surface of the roof tile.

The above-mentioned protrusions can be located at the top and/or bottom of the roof tile shape. For example, the roof tile shape can have a top and side seam at the top and be provided with suspension eyes, stacking points, slat protectors and stiffening ribs at the bottom.

Once the pressing process is completed, the first pressing element is preferably moved to the starting position, causing the pressed roof tile shape to release from the respective mold half in the area of the notches and facilitating demoulding. The mold halves are then brought into the filling position and the roof tile mold is removed from the press mold. This reduces the risk of damage to the pressed roof tile when it is removed from the press mold because the roof tile sticks to one mold half.

Preferably there is a guide for the first and/or the second mold half, whereby the guide together with the mold halves completely demarcates the collection space in the filling and pressing position. The guide can consist of several guide parts and can be brought into a demoulding position before the mold halves are opened. In the dry pressing process, clay shows a relatively high degree of back-expansion of the pressed clay granulate. The back expansion is about 0.7% to 1%. When the press mold is opened to remove the pressed tile shape within the guide that laterally defines the receiving area, the pressed tile shape expands and becomes wedged in the guide, which may damage the pressed tile shape 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 direction in which the mold halves extend, to a demoulding position at a distance from the mold halves, in which the pressed tile shape cannot rest against the guide, even if it expands clay granules back , so that the roof tile shape can expand in the direction of expansion that is essentially parallel to the surface of the shape halves.

At least one second pressure element may be provided on the surface of the first and/or second mold half, which is designed to be movable between a home position in which the second pressure element extends or is recessed relative to the shape of the finished roof tile mould, and a compaction position, wherein the second pressing element reproduces the surface of the shape of the roof tile mold in portions, wherein the second pressing element is moved into the compacting position during or after moving the mold halves to the pressing position or back to the starting position after completion of the pressing process . This second pressure element makes it possible, for example, to recompact the clay material outside the recesses.

Preferably, however, the second pressure element is coupled to a first pressure element in the recess. The first pressure element is pushed from the recessed position into the compaction position by the movement of the second pressure element from the projecting position to the compaction position. In this embodiment the second pressure element is used to move the first pressure element into the compaction position. The second pressure element can be used as an operating 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 compaction position.

Coupling the first and second pressure elements makes it easier to control the movement of the first and second pressure elements between the respective home position and the respective compaction position. By moving the mold halves into the pressing position, the clay material exerts pressure on the second pressing element, causing the second pressing element to move into the compaction position. The movement of the second pressure element to the compaction position also moves the first pressure element coupled to the second pressure element to the compaction position, so that no separate operation is required for the first pressure element.

In addition, the roof tile mold can be easily removed from the pressing mold. For example, the second pressure element extends from the starting position over the shape of the finished roof tile mold and is brought into the compaction position by the increasing pressure when the mold halves are brought into the pressing position. By coupling the first and second pressure elements, the first pressure element is brought into the compaction position. When the press mold is opened, i.e. when the mold halves are moved to the filling position, the pressure on the second pressing elements is reduced so that they can move back to the protruding position, causing the pressed roof tile shape to be lifted and released from the surface of the press mold. The first pressure element coupled to the second pressure element is simultaneously moved back to the starting position, which has been reset relative to the shape of the roof tile, which also allows the roof tile shape to detach from the respective mold half in the area of the notch. Overall, the roof tile does not or hardly adhere to the respective mold half, so that the risk of damage when removing the roof tile can be reduced.

Preferably, a number of first pressure elements and/or a number of second pressure elements are present, 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 multiple, preferably small-scale pressing elements are used, the compaction can be better controlled or the pressing process can be controlled in such a way that the compaction always takes place in a defined area with a defined pressure on the clay material.

Preferably, the pressure elements are designed in such a way that they can be used to achieve a compaction of the clay granulate of approximately 2:1. This means that the original volume of the clay granulate can be reduced by half using the preferred pressure elements. For this purpose, the pressure elements can be made of a correspondingly hard and resilient 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.

After the clay granulate has been filled, the mold halves can be placed in a venting position between the filling position and the pressing position, whereby the air in the receiving space can escape from the receiving space.

When preparing the suspension and therefore at the beginning of the process according to the invention, it can also be determined that the separation of the undersized fraction and the oversized fraction is carried out using a sieve or a filter. In particular, it is being considered to carry out the separation using a wet sieving process. A wet sieving process makes it possible to remove unwanted grain sizes from the suspension without having to dry the suspension first. Wet sieving can also prevent clogging of the sieve meshes, which can occur with small grain sizes in dry sieving processes. Alternatively, the separation can be performed using a centrifuge or a cyclone separator.

Another aspect of the invention is an installation for the production of roof tiles according to the method of the invention. In particular, the installation includes a raw clay feeding device, a mill for producing a suspension, a granulating device for producing clay granules, a pressing mold for dry pressing the clay granules into a roof tile shape and a roller oven for carrying out a rapid baking process .

There may also be a crushing installation to pre-crush the raw clay material into clay pieces of a certain size, whereby the crushing installation can be connected before the mill or can also be part of the mill. The mill can be a crank mill, a roller bowl mill or a rudder ball mill. Optionally, the mill can have a sorting device for separating excess material (e.g. undersized and oversized fractions), where the sorting device can mainly consist of a sieve.

Preferably, the system also includes a vitrification device suitable for processing the surfaces of the roof tile shapes. The shaped roof tiles can, for example, be glazed, embossed, coated or engraved in the vitrification device.

According to a further aspect, the invention relates to a clay roof tile produced according to the method described herein.

Figure description

Further features, details and advantages of the invention appear from the wording of the claims and from the following description of the embodiments with reference to the drawings. This shows:

Fig. 1 is a schematic representation of an installation for the production of a clay roof tile;

Fig. 2: a flowchart of a method for the production of a clay roof tile according to a first example of an embodiment;

Fig. 3 shows a flow diagram of a method for the production of a clay roof tile according to an example of a second embodiment;

Fig. 4a shows a pressing mold for manufacturing a roof tile according to a preferred embodiment in a filling position;

Fig. 4b shows the pressing mold of Fig. 4a in closed pressing position.

Fig. 1 shows a schematic representation of an installation 10 for the production of clay roof tiles 1. The installation 10 shown is particularly suitable for carrying out the process according to the invention. The example installation 10 in Fig. 1 consists of a feeding device 11, which feeds the untreated clay to a mill 12. A suspension 2 is made from the clay in the mill 12. According to the process described here, the undersized and oversized fractions can also be removed in the mill.

The prepared suspension 2 is then fed to the granulating machine 13, which converts the suspension 2 into a clay granulate 3 with a certain moisture content. As in Fig. 1, the granulating device 13 can be, for example, a spray dryer.

The installation 10 of Fig. 1 also includes an intermediate storage 14, which is designed to store and dry the clay granulate 3. Preferably, the intermediate storage 14 consists of one or more silos.

As a further machine part, the installation 10 comprises a pressing mold 14 for dry pressing the clay granulate 3 into a roof tile shape. Finally, the pressed roof tile shapes are transferred to a roller oven 16, which is suitable for baking the roof tile shapes in a rapid baking process, i.e. in less than 4 hours.

As shown in Fig. 1, the installation 10 may also include a glazing apparatus 15. There, the molds can, for example, be glazed, embossed, coated or printed (for example "digital printing") and/or provided with engob before they are fired in the roller kiln 16.

Fig. 2 shows in a flow chart steps S1-S8 of the method according to the invention for the production of a clay roof tile 1 according to an example of the first embodiment.

First step S1 is performed: Providing the moist, unprocessed clay 1. The clay 1 is preferably supplied to the installation 10 from a nearby well. In this way, long transport routes and the associated costs can be avoided or reduced. Coordination of the clay mixture from different clay types is not necessary due to the minor importance of the plastic properties.

Once in the installation 10, the untreated quarry clay 1 can be processed directly into an aqueous suspension 2 in the mill 12 according to step S2. Among other things, the suspension 2 can be homogenized better than dry clay granulate 3. In addition, the subsequent separation processes can also be carried out better compared to conventional processes if the clay 1 is available as an aqueous suspension 2. The conditioning of the starting material into a suspension 2 is preferably carried out by adding water and using unloaders and agitators, which can be integrated into the mill 12. At the end of step S2, the suspension 2 preferably has a solids content of 55% to 65%.

This is followed by step S3: separation of an oversized grain fraction from the suspension 2, wherein the oversize fraction comprises grains whose grain diameter is greater than a defined value. Ideally, the grain size of the next granule 3 is between 120 µm and 1000 µm. To achieve this, grains with a diameter of more than 1000 µm are removed from the suspension 2. In a next step S3.1 (see Fig. 3), grains with a diameter of less than 120 µm can also be removed from the suspension 2.

After separating the oversized and/or undersized grain fraction from the suspension 2, step S4 follows: granulating the suspension 2 into a clay granule 3. To achieve the best possible pressing result, the clay granule 3 must have a residual moisture content of 2% to 6%. %. This prevents the roof tile shapes from shrinking during the pressing process. The granulation process S2 can be carried out, for example, by spray or atomization drying in a suitable granulation machine 13.

Step S5 then follows: The clay granulate 3 is placed in a press mold 14. To produce the roof tile shapes, the clay granulate 3, obtained from step S4, is preferably injected under pressure into the press mold 14 of the system. This is immediately followed by step

S6: Pressing the clay granulate 3 into the pressing mold 14, whereby the clay granulate 3 is compacted and formed into a roof tile shape. As soon as the desired amount of clay granules 3 has been placed in the pressing mold 14, the mold halves of the pressing mold 14 are moved from the filling position to the pressing position, whereby the pressing mold 14 forms the shape of the finished roof tile.

The next step S7 comprises the following: Transferring the roof tile shape to a roller oven 16 for baking the roof tile shape. In the final step S8, the roof tile mold is then fired to form a roof tile using the quick baking process. The baking process according to S8 is preferably carried out in a setting method with one layer.

This allows the largest possible part of the radiant energy from oven 16 to be used for heat transfer to the roof tiles.

Fig. 3 shows a flow chart with steps S1-S8 of the method for manufacturing a clay roof tile 1 according to a second embodiment. The method in Fig. 3 differs from the process in Fig. 2 because the process according to Fig. 3 the additional intermediate steps S1.1, S2.1,

Includes S3.1 and S4.1.

Step S1.1 follows step S1 and includes the following: Breaking the clay clods present in the clay 1 into clay pieces, whereby the clay pieces have an average diameter of 5 cm or less. The crushing or grinding of larger clay clods into clay pieces that are on average smaller than 5 cm can, for example, take place in the mill 12 and serve to prepare the raw material from the stock for the next steps.

Step S2.1 follows step S2 and includes the following: Adding additives to the suspension 2. The additives facilitate the homogenization of the suspension 2 and mainly serve to give the roof tiles their desired properties, for example to increase the solids content in the suspension as high as possible.

Step S3.1 follows step S3 and comprises the following: Separating an undersized grain fraction from the suspension 2, wherein the undersized grain fraction consists of grains whose grain diameter exceeds a defined value. Ideally, the grain size of the next granule 3 is between 120 um and 1000 um. 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.

Step S4.1 follows step S4 and comprises the following: Storing the clay granulate 3 in at least one suitable intermediate storage 14, whereby the intermediate storage 14 is preferably a silo. The storage in an intermediate storage 14 contributes to a further homogenization of the clay granulate 3, whereby, for example, small differences in moisture within the clay granulate 3 can be compensated in this phase. The intermediate storage process can take from several hours to several days depending on production requirements.

According to one embodiment, provision is made to advantageously make the combustion channel of the oven as small as possible in order to increase the combustion capacity of the oven and thus enable the material to be fired more quickly. Another advantage of the process described here is that the resulting roof tile shapes can be fired without the usual oven furniture (e.g.

H or U cassettes), because they already have sufficient shape stability from the dry pressing step. The oven furniture can therefore be omitted, which saves space and costs and also increases the burning efficiency of the oven. The use of a roller kiln also has the advantage that roller kilns can be used climate neutrally compared to the ovens normally used in brick ovens. For example, the roller oven can operate electrically or on hydrogen.

In Fig. 4a shows the press mold 14 in a filling position in which the mold halves 22, 24 are spaced apart and a clay material can be filled into the collection space. A filling device 42 is provided for filling the press mold 14, which can inject the clay material into the receiving space 30 by means of compressed air with excess pressure. The injection takes place in an injection direction E that is substantially parallel to the surface 34, 38 of the first or second mold half 22, 24.

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 reception area 30 essentially reproduces the shape of the roof tile 18. One of the mold halves 22, 24 can be fixed in position so that only the other mold half 22, 24 is moved. However, it is also possible that both mold halves 22, 24 can be moved and moved towards each other during the pressing of the roof tile 18. The guide elements 28 can be moved in a removal direction R that is essentially perpendicular to the pressing direction P, to a removal position in which the guide elements 28 are spaced 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 each consists of 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.

A first pressure element 52 is arranged on or in the recess 40, which is formed by a pressure cushion with 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, enters or exits the pressure chamber 58 can flow. The first pressure element 52 has a pressure line 60 through which the pressure medium 56, for example oil, can flow into or out of the pressure chamber 58. The first pressure element 52 is arranged at the base of the recesses 40, i.e. at the transition to the surface 38 of the second mold half 24 opposite the first mold half 22.

Furthermore, a second pressure element 62 is provided on the surface 38 of the second mold half 24, the structure of which largely corresponds to that 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. .

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 second pressure elements 52, 82. Furthermore, the pressure lines 60, 66 are connected to a pressure generator 68, which can supply the pressure medium 56 and/or regulate the pressure in the pressure lines 60, 66 or the pressure elements 52, 62. Preferably, the printing 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 basic body 46 of the second mold half 24 and the coating 50, which is formed as a membrane.

In the filling position according to Fig. 4a, the second pressure element 62 is bent into a starting position towards the reception space 30, i.e. protrudes outside the shape of the finished roof tile 18 (dotted line). In the filling position, the first pressure element 52 is returned to a starting position relative to the shape of the finished roof tile 18.

The first and second pressure elements 52, 62 are connected to each other by the pressure lines 60, 66 in such a way that the first pressure element 52 is brought into a compaction position by the second pressure element 62, in which the second pressure element 62 represents the shape of the finished roof tile in parts, according to is moved outside by the pressure medium 56 that flows out of the second pressure element 62 and flows into the first pressure element 52 to a compaction position in which the first pressure element 52 also reproduces part of the shape of the roof tile 18 (see Fig. 4b).

The invention is not limited to any of the embodiments described above, but can be adapted in various ways.

All features and advantages arising from the claims, the description and the drawing, including design details, spatial measures and method steps, may be essential to the invention, both individually and in various combinations.

List of reference symbols

No. Step 1 Clay 2 Suspension 3 Clay granulate 10 Installation 11 Feeding equipment 12 Mill 13 Granulating device 14 Interim storage 15 Glazing equipment 16 Roller kiln 18 Roof tiles 20 Press mold 22 First half of the mold 24 Second half of the mold 26 Guide 28 Guide elements 30 Receiving space 34, 38 Surface 40 Floor 42 Filling device 44 46 Basic body 48, 50 Coating 52 First pressure element 56 Pressure medium 58, 64 Pressure chamber 60 Pressure line 62 Second pressure element 70, 72 Recess

Claims (14)

Conclusions A method for manufacturing a clay roof tile (1), comprising the following steps: (81) Providing the moist, raw clay (1); (82) Generation of an aqueous clay suspension (2); (S3) Separating an oversized grain fraction from the suspension (2), wherein the oversized grain fraction comprises grains whose grain diameter is greater than a defined value; (S4) Granulating the suspension (2) to produce a clay granulate (3); (S5) Application of clay granulate (3) in a pressing mold (14); (S6) Pressing the clay granulate into the pressing mold (14), whereby the clay granulate (3) is compressed and formed into a roof tile shape; (S7) Transferring the roof tile shapes to a roller oven and (S8) Baking the roof tile shapes in a quick baking process. Method according to claim 1, characterized in that the method according to step (S1) further comprises the following step: (S1.1) Breaking clay clods in the clay (1) into clay pieces, where the clay pieces have an average diameter of 5 cm. Method according to any 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). Method according to any one of the preceding claims, characterized by the fact that the method further comprises the following step before step (S3): (S3.1) Separation of an undersized grain fraction from the suspension (2), where the undersized grain fraction comprises grains whose grain diameter is smaller than a defined value. Method according to any one of the preceding claims, characterized in that the method according to step (S4) further comprises the following step: (54.1) Store the clay granulate in at least one suitable intermediate storage facility (15), in particular a silo. 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 from 55% to 65%, before granulation. Method according to any of the preceding claims, characterized in that the grains of the oversized fraction each have a grain diameter greater than 1000 µm. Method according to any one of claims 4 to 7, characterized in that the grains of the undersized fraction each have a grain diameter that is smaller than 100 µm. Method according to one of the preceding claims, characterized in that the clay granulate (3) after granulation of the suspension (2) has a moisture content of less than 15%, in particular from 1% to 11%. Method according to any of the preceding claims, characterized in that the pressing of the clay granulate (3) is carried out by dry pressing. Method according to one of claims 4 to 10, characterized in that the separation of the undersized fraction and the oversized fraction always takes place in a sieving process. Method according to any one of the preceding claims, characterized in that step (S1.1) is carried out in a winding mill or in a roller bowl mill. 13. Installation (10) for manufacturing a roof tile according to the method of any of the preceding claims. 14. Clay roof tile, characterized in that the roof tile is produced using a method according to any one of claims 1 to 12. -0-0-0-0-0-0-