WO2005090034A1

WO2005090034A1 - Method and plant for preparing a layer of powders to be pressed to obtain ceramic tiles

Info

Publication number: WO2005090034A1
Application number: PCT/EP2005/002117
Authority: WO
Inventors: Claudio Ricci; Silvano Valli
Original assignee: Sacmi Cooperativa Meccanici Imola Societa' Cooperativa
Priority date: 2004-03-10
Filing date: 2005-02-25
Publication date: 2005-09-29
Also published as: ITRE20040017A1

Abstract

Method for preparing a layer of powders to be pressed to obtain ceramic tiles consists at least of depositing on a translating surface a continuous constant thickness layer of powders; removing at least one strip of powders within said layer to form a channel of random path; sucking off the removed material; filling said at least one channel with powders having at least one different characteristic.

Description

DESCRIPTION

METHOD AND PLANT FOR PREPARING A LAYER OF POWDERS TO BE PRESSED TO OBTAIN CERAMIC TILES

5 TECHNICAL FIELD The present invention relates to a prearrangement method and plant for forming ceramic tiles and slabs.

BACKGROUND ART 10 Research in the ceramic sector is currently aimed at obtaining products imitating natural stone, such as marble and granite. Slabs of these materials generally present at least two different types of veining. A first type of veining appears in the form of variable width strips of a colour little different from the background colour. The edges of this veining are 15 generally hazy and poorly defined as they represent a chromatic mixing between the background colours and those of the veining. A second type of veining encountered in said natural slabs appears instead in the form of thin strips of random pattern which extend irregularly over the entire surface. This veining is characterised by a colour in strong contrast with 20 the background colour and has well defined edges. Essentially there is no material mixing with the background colour at the edges. A known method for producing ceramic tiles or slabs imitating natural stone consists of depositing a virtually constant-thickness layer of powders on a translating belt, and incising the surface of said layer to create 25 channels of irregular path on the surface which are then filled with powders of colour different from the background colour. The layer of powders is incised by an incisor means movable in a plane parallel to the plane in which the layer lies. During translation of the conveyor belt the incisor means presents a lower portion which interacts with the powders of the layer deposited on the belt, to create said channel which is then filled with powders of different colour.

The described method is hence able to form veining of colour different from the background colour, however it presents certain drawbacks which limit the chromatic effect substantially to veining of the aforedeschbed first type. In this respect, with this method the material removed from the layer to create the channel is displaced onto the channel sides. Hence the layer with the veining presents an irregular upper surface which generates problems of both technical and aesthetic character during pressing for producing the tile. In particular during pressing, it happens that the material forming the channel sides becomes redistributed to partly cover the veining, which hence appears with edges not well defined and delineated. Moreover the material excess at the sides introduces local density differences which can give rise to problems during pressing and during the subsequent drying and firing stage. The object of the present invention is to overcome the drawbacks of the known art within the framework of a rational and reliable solution.

DISCLOSURE OF THE INVENTION

The invention attains said object by providing a method for preparing a layer of powders to be then pressed to obtain ceramic tiles or slabs presenting .variously distributed over the surface, veining the edges of which are sharp and well defined against the background of the slab. Specifically the method of the invention comprises the following operative steps:

- depositing on a translating surface a continuous constant-thickness layer of powders,

- removing at least one strip of powders in said layer to form a channel of random path,

- sucking off the removed material,

- filling said at least one channel with powders having at least one different characteristic. According to the invention, said at least one strip of powders can be removed to form said at least one channel either by sucking off the powders, or by interaction between an incisor element, or furrower, and the powders of said layer, or by a localized air blowing action on the layer of powders by an air jet. If the channel is formed by interaction between a furrower and the powders of said layer, the suck-off step of the method of the invention must be localized at least along the sides of the channel formed by said incisor. The formed channel can also be of variable width and depth on the layer surface and must be filled with a second type of powders having at least one different characteristic chosen from powder nature, colour, particle size, etc.

According to a further aspect, the present invention provides a ceramic tile or slab forming plant having structural and functional characteristics such as to obviate the said drawbacks of the known art, in accordance with claim 9.

Specifically, the plant of the invention comprises a translating surface, distributor means positioned above said translating surface to create thereon a continuous constant-thickness layer of soft material, means to create within said layer at least one channel, and means for filling said channel with powders having at least one characteristic different from those powders which form said layer, the means for creating said at least one channel comprising pneumatic means. According to the invention, said means to create at least one channel within said layer, said means for filling said channel with powders having at least one characteristic different from those powders which form said layer and said pneumatic means are supported by at least one unit comprising a support frame movable in a plane parallel to said translating surface. Said support frame is moved by a known positioning system. In a first embodiment of the invention, said pneumatic means create said channel by sucking off the powders.

In a different embodiment of the invention, said pneumatic means create said at least one channel by a device which blows a pressurized air jet. The powder lifted by the air jet is sucked off by a suction device associated with said blower device.

In a further embodiment of the invention, said means for creating said at least one channel comprise a furrower which by interference with the layer material creates said at least one channel. In this case two banks of powder form on the sides of the channel and are removed by said pneumatic means which in this case comprise a suction device acting in a localized region about said banks.

In a variant of this latte embodiment of the invention, said furrower comprises two vertical parallel blades which isolate a portion of powders from said layer. Said portion is then removed by suck-off by said pneumatic means, to create the channel which is then filled by the filling means with powders having at least one characteristic different from those powders which form the layer.

This variant offers the advantage that during channel creation, the blades lightly compact the lateral walls thereof, making them more stable. Claims from 10 to 37 define preferred and particularly advantageous embodiments of the method and plant of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS Further characteristics and advantages of the invention will become apparent on reading the ensuing description provided by way of non- limiting example, with the aid of the figures shown in the accompanying drawings, in which:

Figure 1 is a schematic side view of a plant in accordance with the present invention.

Figure 2 is a schematic view of the plant of Figure 1 from above.

Figure 3 is a schematic perspective view of a first embodiment of the unit with which the invention is provided.

Figure 4 shows a variant of Figure 3. Figure 5 is a schematic perspective view of a second embodiment of the unit with which the invention is provided. Figure 6 shows a variant of Figure 5.

Figure 7 is the section VII-VII indicated in Figure 5.

Figure 8 is the section VII-VII indicated in Figure 5.

Figure 9 is a schematic perspective view of a third embodiment of the unit with which the invention is provided.

Figure 10 is a vertical section through Figure 9 taken in correspondence with the unit.

Figures 11 , 12 and 13 are schematic sections through three variants of the unit of the third embodiment of the invention. Figure 14 is a schematic perspective view of a fourth embodiment of the unit with which the invention is provided.

Figure 15 is a vertical section through Figure 14 taken in correspondence with the unit.

Figure 16 is a schematic perspective view of a variant of the fourth embodiment of the unit with which the invention is provided.

Figure 17 is a vertical section through Figure 16 taken in correspondence with the unit.

Figure 18 is a schematic horizontal section through the unit of the variant of the fourth embodiment of invention. Figure 19 is the section XIX-XIX of Figure 18.

Figure 20 is the section XX-XX of Figure 18.

Figure 21 is the section XXI-XXI of Figure 19.

Figure 22 is a schematic perspective view of a third embodiment of the unit with which the invention is provided.

BEST MODE FOR CARRYING OUT THE INVENTION Figure 1 shows the plant 1 , comprising a translating surface 2 which in the illustrated embodiment is a conveyor belt.

Above the translating surface 2 there are positioned distributor means 3, in the current example a hopper, to create on the translating surface a continuous constant-thickness layer 4 of soft material.

Downstream of said hopper there are positioned four identical units 5 each of which is provided to create veining 40 within the layer 4 (Figure 2). The units 5 are positioned parallel to each other, each of them being able to translate in a plane parallel to the translating surface 2, the translation of each device being controlled by a positioning system, pre-settable by the operator, which is not shown as it is of known type. Each unit 5 is supported and can slide, via wheels 50, on a rectilinear support guide 6, which is disposed perpendicular to the advancement direction of the translating surface 2. Each unit 5 carries, rigid with a support frame 51 , means 7 for creating at least one channel within said layer, and means 8 for filling said channel with powders having at least one characteristic different from those powders which form said layer. In particular, said means for creating at least one channel within said layer also comprise pneumatic means 3, the function of which will be clarified hereinafter.

The means 7, 8 and 9 can be in the form of different embodiments described hereinafter, for which the same reference numerals will be used to identify identical components common to all the embodiments. Figure 3 shows a first embodiment of the units 5, in which the pneumatic means 9 comprise a suction device 10 provided with a tubular element 11 the operative mouth 12 of which is positioned in proximity to the layer surface, and presents an elongate cross-section. The function of the suction device 10 is to create a channel 100 in the layer of powders 4 during advancement of the translating surface 2. The channel 100 is then filled with powders having at least one characteristic different from those powders which form said layer 4, using the filing means 8 which in the illustrated embodiment comprise a hopper 80, the discharge mouth of which is positioned flush with the upper surface of the layer 4. In this manner each unit 5 forms, in the layer 4, veining 40 such as that shown in Figure 2.

It should be noted that the depth and width of the channel 100 in the layer 4 can be varied by varying the suction force generated by the suction device 10. The tubular element 11 is also associated with means, not shown, for rotating it about its axis in order to vary the orientation of the delivery mouth.

This enables the channel width to be varied while maintaining constant the suction force exerted by the suction device. Figure 4 shows a first variant of the first embodiment of the invention in which the unit 5 supports not only the hopper 80 but also a second hopper 81 positioned between the hopper 80 and the tubular element 11. The hopper 81 is provided with a mouth 82 which is partially inserted into the channel 100 formed by the suction device 10 in order to feed into the channel a first deposit of powders which is then completed by the hopper 80, the bottom of which is positioned flush with the layer 4. In this case the powder deposited by the hopper 80 preferably consists of a mixture of powders which become translucent or transparent after the formed tile has been filed.

Figures 5, 6, 7 and 8 show a second embodiment of the units 5, in which the means for creating the channel 100 comprise a furrower 15 which creates the channel by interference with the powders of the layer 4. The action exerted by the furrower on the powders of the layer 4 causes the powders to shift laterally and form banks 101 on the channel 100. These banks project from the surface of the layer 4 and are removed by the action of the pneumatic means 9. These latter comprise a suction device 16, identical to the already described device 10, and provided with a tubular element 17 of rectangular cross-section positioned immediately upstream of the furrower 15. The tubular element 17 exerts a localized suction action at least on the two lateral banks 101 created by the action of the furrower. Means 8 for filling the channel 100 with a mixture of powders having at least one characteristic different from the powders forming the layer 4 are present downstream of the tubular element 17. Said filing means 8 comprise the already described hopper 80. The furrower 15 (Figures 7 and 8) consists of two plates 150 hinged together at one end by a pin 18 and having an opening angle which can be adjusted by suitable adjustment means. In the illustrated embodiment said adjustment means comprise a hydraulic or pneumatic cylinder-piston unit 10, or an electromechanical linear actuator, the rod of which carries, hinged thereto, two identical connection rods 20, each of which is connected to one of the two plates 150. The cylinder-piston unit 19, together with the pin 18, also performs the function of supporting the furrower 15 on the overlying support frame 51 of the unit 5. With reference to Figures 7 and 8, operating the cylinder-piston unit 19 modifies the opening angle between the plates. This advantageously enables the channel width to be varied. The frame 51 is also connected to means, not shown, to translate it in height in order to vary the position of the furrower relative to the layer and hence vary the depth of the channel 100. Figure 6 shows a variant of the second embodiment of the invention in which the channel filling means 8 comprise the already described hoppers 80 and 81.

Figures 9 and 10 show a third embodiment of the invention. This embodiment uses a furrower 24 which combines means 7 for creating at least one channel within said layer with means 8 for filling said channel 100 with powders having at least one characteristic different from those powders which form said layer 4.

The furrower 24 is in the form of a hollow tube, the outer surface of which performs the function of creating the channel 100, the powders for filling the channel 100 being present in its interior.

At its lower end the furrower 24 has, facing the channel 100, an aperture 240 (Figure 10) through which the channel filling powders emerge. The pneumatic means 9 are present immediately upstream of the furrower and comprise a tubular element 17, of rectangular cross-section, connected to the suction device 16 to suck off the powders lifted by the furrower 24 during creation of the channel 100. Figures 11 , 12 and 13 show some variants of the third embodiment of the invention. In particular, said variants differ from the described embodiment with regard to the form and position of the pneumatic suction means 9. With reference to Figure 11 , said pneumatic means 9 comprise a conduit 25 connected to the suction device 16.

The internally hollow conduit 25 presents a circular cross-section and is provided with a centrally holed base wall 26 through which the furrower 24 is inserted, its lower end emerging from said wall 26 to interact with the powders of the layer 4. The base wall 26 presents a circular sector- shaped aperture 260 through which the powders lifted by the furrower during the creation of the channel 100 are sucked. Figure 12 differs from the variant shown in Figure 11 with regard to the shape of the suction aperture in the conduit 25. In this case the powders lifted by the furrower 24 during creation of the channel 100 are sucked though a plurality of holes 261 positioned above the surface of the furrower which creates the channel.

Figure 13 differs from the variant shown in Figure 12 in that the powders lifted by the furrower 24 during creation of the channel 100 are sucked through a plurality of holes 262 positioned in proximity to the lower end of the conduit 25, in this case the base wall 27 of the conduit 25 being free of powder suction apertures.

Figures 14 and 15 show a fourth embodiment of the invention. In this embodiment the channel creation means 7 comprise a furrower 30 consisting of two parallel vertical blades 31 joined together at their top by a horizontal wall 32. Said blades 31 have associated with them the pneumatic means 9 for sucking off the powders of the layer 4 displaced by the blades during advancement of the translating surface 2.

In particular, said figures show that the blades 31 and 32 are in the form of an appendix of a vertical conduit 33 connected to the suction device 16, not shown but previously described, the purpose of which is to suck off the powders displaced by the blades 31 in creating the channel 100. With the conduit 33 there are associated the means 8 for filling said channel 100 with powders having at least one characteristic different from those powders forming said layer 4.

Said means 8 comprise, adjacent to the conduit 33, a conduit 34 presenting in its rear in proximity to its lower end an aperture 35 through which the powder for filling the channel 100 flows. Figures 16, 17, 18, 19, 20 and 21 show a variant of the fourth embodiment of the invention which differs in that the means 7 for creating the channel 100 comprise a furrower 36 provided with two vertical parallel blades 37 and 38, the distance apart of which can be adjusted. The figures show a body 39 rigid with the support frame 51 (Figure 21 ), and a block 40 supported by the body 39, which can translate horizontally, being associated with positioned means. The body 39 and block 40 present two mutually facing inclined portions 41 and 42 respectively, their lower edges being spaced apart to define a slit 43, of which the sides of longer length are bounded lowerly by said blades 37 and 38. The block 40 comprises two slots 440 through which pass two parallel superposed stems 44 extending from the body 39, and can translate relative to the body 39, being associated with suitable positioner means 45. Said positioner means 45 comprise a linear actuator 46, the rod of which acts on a rocker arm 47 provided on a lever 48 which acts against a stub 49 branching from the block 40. The translation of the block 40 is controlled by a counteracting spring 53 positioned between the block and the body 39.

Above said inclined portions 41 and 42, the block 40 is provided with a through hole 400 which opens in proximity to the pneumatic means 9. Said pneumatic means 9 comprise a conduit 54 (Figures 19, 20) connected to the suction device 16, not shown, the function of which is to create a channel 100 in the layer 4 by sucking off the powders displaced by the blades 37 and 38.

With reference to Figure 20, on its rear side the block 40 presents a lowerly open profiled recess 55. The recess 55 is closed by an external plate 56 (Figure 18) which together with said recess 55 defines a hopper 57 for filling the channel 100 created by the suction device 16.

The lower mouth of the hopper 57 can be completely or partially closed by a plate 58 (Figure 20) which translates by the action of a cylinder-piston unit 59. In particular, from the figures it can be seen that the plate is supported by a block 60 mounted on a stem 61 of the body 39. Said block is mechanically connected to the cylinder-piston unit 59 which translates it.

In the illustrated embodiment the hopper 57 is provided to effect only a partial filling of the channel 100. Complete filling is achieved by the hopper 80, visible only in Figures 16 and 17. Finally with reference to Figure 21 , it can be seen that the two blades 37 and 38 carry a respective vertically extending perpendicular wall 52 lying at the base wall of the recess 55, its function being to separate the suction region defined by the slit 43 from the filling region bounded by the lower mouth of the hopper 57.

Figure 22 shows a further embodiment of the invention in which the pneumatic means 9 associated with the channel creation means 7 comprise a blower device 63 which generates an air jet by which the channel 100 is created. The blower device is connected to a delivery conduit 64 the delivery mouth of which is positioned just above the layer 4. The delivery conduit 64 is inserted into a second conduit 65, provided with a base plate 66 presenting a plurality of holes 67. The conduit 65 terminates at the suction device 10, the function of which is to suck off the powders lifted by the air jet delivered by the blower device 63 to create the channel 100. The channel 100 is then filled by the hopper 80 with powders having at least one characteristic different from those which form the layer 4.

Claims

1. A method for preparing a layer of powders to be pressed to obtain ceramic tiles, comprising the following operative steps:

a. depositing on a translating surface a continuous constant-thickness layer of powders,

b. removing at least one strip of powders within said layer to form a channel of random path,

c. sucking off the removed material,

d. filling said at least one channel with powders having at least one different characteristic.

2. A method as claimed in claim 1 , characterised in that removal of said at least one strip of powders to form said at least one channel is achieved by sucking out the powders.

3. A method as claimed in claim 1 , characterised in that removal of said at least one strip of powders to form said at least one channel is achieved by interaction between an incisor element or furrower and the powders of said layer.

4. A method as claimed in claim 3, characterised in that suction of the powders removed to form said at least one channel is localized at least along the sides of the channel formed by said incisor or furrower.

5. A method as claimed in claim 1 , characterised in that removal of said at least one strip of powders to form said at least one channel is achieved by an air blowing action on the layer of powders.

6. A method as claimed in claim 1 , characterised in that said at least one channel is of variable width.

7. A method as claimed in claim 1 , characterised in that the depth of said channel is variable within said layer.

8. A method as claimed in claim 1 , characterised in that said at least one different characteristic of the powders filling said at least one channel is chosen from powder nature, colour, and particle size.

9. A plant for preparing a layer of powders to be pressed to obtain ceramic tiles, comprising a translating surface (2), distributor means (3) positioned above said translating surface to create thereon a continuous constant thickness layer (4) of soft material, means (7) to create at least one channel (100) within said layer, and means (8) for filling said channel (100) with powders having at least one characteristic different from those powders which form said layer (4), characterised in that the means (7) for creating said at least one channel comprise pneumatic means (9).

10. A plant as claimed in claim 9, characterised in that said pneumatic means (9) comprise a suction device (10, 16) and a tubular element (11 , 17, 25, 33, 54, 65) provided at one end with an intake mouth.

11. A plant as claimed in claim 10, characterised in that said tubular element is associated with operating means for adjusting the position of the intake mouth of said tubular element.

12. A plant as claimed in claim 10, characterised in that said tubular element is associated with means for rotating it about its axis.

13. A plant as claimed in claim 10, characterised in that said intake mouth is of elongate cross-section.

14. A plant as claimed in claim 10, characterised in that said intake mouth is of square cross-section.

15. A plant as claimed in claim 14, characterised in that the suction action exerted by said suction device creates said channel (100).

16. A plant as claimed in claim 9, characterised in that said pneumatic means (9) comprise at least one device for blowing a pressurized air jet.

17. A plant as claimed in claim 16, characterised in that with said blower device (63) there is associated a suction device (16) to suck off the powders lifted by the air jet produced by the blower device.

18. A plant as claimed in claim 9, characterised in that said means (7) to create at least one channel within said layer comprise at least one furrower for incising said layer to create said channel.

19. A plant as claimed in claim 18, characterised in that pneumatic means (9) comprising a suction device (10, 16) are associated with said furrower.

20. A plant as claimed in claim 19, characterised in that said suction device (10, 16) acts locally at least along the sides of said channel.

21. A plant as claimed in claim 18, characterised in that said furrower comprises the means (8) for filling said channel.

22. A plant as claimed in claim 18, characterised in that said furrower is associated with means for translating it in height to vary the depth of said channel.

23. A plant as claimed in claim 18, characterised in that said furrower is associated with means for rotating it about its vertical axis.

24. A plant as claimed in claim 18, characterised in that said furrower is a hollow tubular element.

25. A plant as claimed in claim 24, characterised in that said hollow tubular element is of elliptical cross-section.

26. A plant as claimed in claim 24, characterised in that said hollow tubular element is of square cross-section.

27. A plant as claimed in claim 18, characterised in that said furrower comprises two plates hinged together at one end to form a V.

28. A plant as claimed in claim 27, characterised in that the opening angle between said plates is adjustable.

29. A plant as claimed in claim 28, characterised in that the opening angle between said plates is determined by positioning means.

30. A plant as claimed in claim 29, characterised in that said positioning means comprise a cylinder-piston unit the piston rod of which is hinged to said plates by two connecting rods.

31. A plant as claimed in claim 18, characterised in that said furrower comprises two spaced-apart blades.

32. A plant as claimed in claim 31 , characterised in that the distance between said blades is adjustable by suitable positioning means.

33. A plant as claimed in claim 11 , characterised in that said means (7) to create at least one channel (100) within said layer and said means (8) for filling said channel (100) are supported by the frame of a single unit

(5).

34. A plant as claimed in claim 33, characterised in that said unit is made to translate within a plane parallel to said translating surface.

35. A plant as claimed in claim 18, characterised by comprising a plurality of mutually parallel units.

36. A plant as claimed in claim 9, characterised in that said means for filling said channel comprise at least one hopper.

37. A plant as claimed in claim 9, characterised in that said means to create at least one channel within said layer, said means for filling said channel with powders having at least one different powder characteristic and said suction means are supported by a single frame movable within a plane parallel to said translating plane.