EP4543655A1 - Calibration method of a powder material feeding assembly and manufacturing system of ceramic articles implementing said method - Google Patents

Calibration method of a powder material feeding assembly and manufacturing system of ceramic articles implementing said method

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Publication number
EP4543655A1
EP4543655A1 EP23741126.9A EP23741126A EP4543655A1 EP 4543655 A1 EP4543655 A1 EP 4543655A1 EP 23741126 A EP23741126 A EP 23741126A EP 4543655 A1 EP4543655 A1 EP 4543655A1
Authority
EP
European Patent Office
Prior art keywords
powder material
feeding
during
feeding assembly
assembly
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
EP23741126.9A
Other languages
German (de)
French (fr)
Inventor
Paolo TESTI
Francesco LA DONNA
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Sacmi Imola SC
Original Assignee
Sacmi Imola SC
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Sacmi Imola SC filed Critical Sacmi Imola SC
Publication of EP4543655A1 publication Critical patent/EP4543655A1/en
Pending legal-status Critical Current

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B28—WORKING CEMENT, CLAY, OR STONE
    • B28B—SHAPING CLAY OR OTHER CERAMIC COMPOSITIONS; SHAPING SLAG; SHAPING MIXTURES CONTAINING CEMENTITIOUS MATERIAL, e.g. PLASTER
    • B28B13/00—Feeding the unshaped material to moulds or apparatus for producing shaped articles; Discharging shaped articles from such moulds or apparatus
    • B28B13/02—Feeding the unshaped material to moulds or apparatus for producing shaped articles
    • B28B13/0295—Treating the surface of the fed layer, e.g. removing material or equalization of the surface
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B28—WORKING CEMENT, CLAY, OR STONE
    • B28B—SHAPING CLAY OR OTHER CERAMIC COMPOSITIONS; SHAPING SLAG; SHAPING MIXTURES CONTAINING CEMENTITIOUS MATERIAL, e.g. PLASTER
    • B28B1/00—Producing shaped prefabricated articles from the material
    • B28B1/005—Devices or processes for obtaining articles having a marble appearance
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B28—WORKING CEMENT, CLAY, OR STONE
    • B28B—SHAPING CLAY OR OTHER CERAMIC COMPOSITIONS; SHAPING SLAG; SHAPING MIXTURES CONTAINING CEMENTITIOUS MATERIAL, e.g. PLASTER
    • B28B13/00—Feeding the unshaped material to moulds or apparatus for producing shaped articles; Discharging shaped articles from such moulds or apparatus
    • B28B13/02—Feeding the unshaped material to moulds or apparatus for producing shaped articles
    • B28B13/0215—Feeding the moulding material in measured quantities from a container or silo
    • B28B13/022—Feeding several successive layers, optionally of different materials
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B28—WORKING CEMENT, CLAY, OR STONE
    • B28B—SHAPING CLAY OR OTHER CERAMIC COMPOSITIONS; SHAPING SLAG; SHAPING MIXTURES CONTAINING CEMENTITIOUS MATERIAL, e.g. PLASTER
    • B28B17/00—Details of, or accessories for, apparatus for shaping the material; Auxiliary measures taken in connection with such shaping
    • B28B17/0063—Control arrangements
    • B28B17/0081—Process control
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B28—WORKING CEMENT, CLAY, OR STONE
    • B28B—SHAPING CLAY OR OTHER CERAMIC COMPOSITIONS; SHAPING SLAG; SHAPING MIXTURES CONTAINING CEMENTITIOUS MATERIAL, e.g. PLASTER
    • B28B5/00—Producing shaped articles from the material in moulds or on moulding surfaces, carried or formed by, in or on conveyors irrespective of the manner of shaping
    • B28B5/02—Producing shaped articles from the material in moulds or on moulding surfaces, carried or formed by, in or on conveyors irrespective of the manner of shaping on conveyors of the endless-belt or chain type
    • B28B5/026—Producing shaped articles from the material in moulds or on moulding surfaces, carried or formed by, in or on conveyors irrespective of the manner of shaping on conveyors of the endless-belt or chain type the shaped articles being of indefinite length
    • B28B5/027—Producing shaped articles from the material in moulds or on moulding surfaces, carried or formed by, in or on conveyors irrespective of the manner of shaping on conveyors of the endless-belt or chain type the shaped articles being of indefinite length the moulding surfaces being of the indefinite length type, e.g. belts, and being continuously fed

Definitions

  • the present invention relates to a calibration method of a powder material feeding assembly; in particular, of powder ceramic material . More particularly, the invention refers to the calibration of a powder material feeding assembly used for the manufacture of ceramic articles ; in particular, of ceramic slabs and tiles .
  • di f ferent aesthetic ef fects are formed by means of feeding assemblies of known type , for example those described in documents W02009118611 and IT1314623 ( of the same Applicant ) which provide a plurality of digital feeding devices , known as printheads , configured to feed di f ferent types of powder material in a controlled manner on a conveyor so as to form a layer of powder ceramic material having the desired decoration (pattern) .
  • Each of said feeding devices comprises a container of powder material , an exit port extending crosswise to the conveyor, a plurality of distribution elements mutually flanked so as to define a build-up plane , which is designed to receive the material exiting from the exit port and is inclined at an angle lower than the friction angle of the powder material so that the material exiting from the exit port can build up on said inclined build-up plane , and a plurality of actuators each configured to operate the movement ( in particular, to vibrate ) the aforementioned distribution elements so that the material built-up on the build-up plane slides towards a falling edge of said plane and falls on the conveyor .
  • these flow rate measurements are carried out by using a calibration tray of known dimensions ( therefore of known surface units ) that is conveyed on a conveyor that extends under the di f ferent feeding devices of the feeding assembly so that the powder material fed by the various feeding devices is collected in the calibration tray, which, once the powder material is received from a feeding device , is weighed .
  • a calibration tray of known dimensions therefore of known surface units
  • the powder material fed by the various feeding devices is collected in the calibration tray, which, once the powder material is received from a feeding device , is weighed .
  • This operation is repeated for each feeding device of the feeding assembly, the di f ferent flow rate values are then compared and, as a function of this comparison, the operating parameters of the feeding assembly are adj usted so that all the feeding devices feed the same amount o f powder material per surface unit .
  • Such adj ustment takes place , for example , by varying the operation of the feeding devices , in terms of time of operation, or of frequency or ampl itude of the electrical signal that sets the various di stribution elements in motion, or by varying the inclination of the distribution elements of the various digital feeding devices etc .
  • This mode of calibration has , however, multiple limitations , among which we mention the following .
  • this is a fairly long calibration methodology as it involves the need to pass the calibration tray below the operation assembly a number of times similar to the number of feeding devices of each feeding assembly, then calculating the flow rate of each of these feeding devices and consequently adj usting the various operating parameters of the feeding assembly .
  • the adj ustment operations are performed substantially manually, with all the disadvantages in terms of precision and slownes s of the operations .
  • Aim of the present invention is to provide a calibration method of a powder material feeding assembly, which allows to overcome , at least in part , the drawbacks of the known art .
  • Figure 1 represents a schematic side view of a manufacturing system of ceramic articles
  • FIGS. 2 and 3 are schematic and perspective views of two di f ferent variants of part of the manufacturing system of ceramic articles of Figure 1 , during the calibration operations of the powder material feeding assembly carried out in accordance with the present invention;
  • FIG. 4 is a schematic side view of the powder material feeding assembly shown in Figures 2 and 3 during the calibration operations of the feeding assembly itsel f ; in particular, this figure shows a detection device that detects one ( the first ) of the fed strips of powder material of the powder material feeding assembly;
  • FIG. 5 is a schematic side view of a feeding device of the feeding as sembly schematically shown in Figures 2 , 3 and 4 while it feeds powder material ;
  • FIGS. 6 and 7 are two views from above and on an enlarged scale of a part of Figures 2 and 3 to better visuali ze the di f ferent transversal positions that the detection device can assume during the calibration operations of the feeding assembly .
  • number 1 denotes as a whole a manufacturing system 1 of ceramic articles T .
  • the ceramic articles T are ceramic slabs or tiles .
  • the manufacturing system 1 of ceramic articles T comprises : a compaction device 2 (per se known and not further described herein) , which is arranged at a compaction station 3 and is configured to compact , preferably substantially continuously, a layer SP of ceramic powder material CP, comprising ceramic powder, in order to obtain a layer of compacted powder KP ; and a conveyor assembly 5 which is configured to transport ( advantageously but not necessarily substantially continuously) the layer SP of powder material CP along a given path P ( schematically represented with a dotted line in Figure 1 ) from a feeding station 6 to the compaction station 3 , and to transport the layer of compacted powder KP from the compaction station 3 to an output station 7 always along the given path P .
  • a compaction device 2 per se known and not further described herein
  • the manufacturing system 1 of ceramic articles T further comprises : a powder material CP feeding assembly 8 , which is configured to feed the powder material CP, comprising ceramic powder, to the conveyor assembly 5 ( in particular, above the conveyor assembly 5 ; even more in particular, above a conveyor 50 of the conveyor assembly 5 ) , at the feeding station 6 , so as to generate said layer SP of powder material CP .
  • powder material CP is meant any inconsistent solid material , for example also in granular form, advantageously but not in a limiting manner, comprising ( in particular, consisting of ) ceramic powder, for example containing clays , sands and/or feldspars etc .
  • the conveyor assembly 5 is arranged and configured to support from below the layer SP of powder material CP and the layer of compacted powder KP along the given path P .
  • the conveyor assembly 5 comprises , in turn : an upper conveyor 50 , for example a conveyor belt , which extends at the aforementioned feeding station 6 ; a lower conveyor 50 ' , which is arranged at a lower height than the upper conveyor 50 and extends downstream of the upper conveyor 50 along the given path P and a discharge assembly 50 ' ’ arranged immediately downstream of the upper conveyor 50 and immediately upstream of the lower conveyor 50 ' along the given path P and, advantageously but not in a limiting manner, configured to level out ( i f necessary) the layer SP of powder material CP before unloading it on the lower conveyor 50 ' .
  • the discharge assembly 50 ' ’ (when present ) comprises ( in particular, is defined by) a substantially vertical wall 51 extending perpendicularly to the conveying direction A below the upper conveyor 50 and above the lower conveyor 50 ' and a conveyor belt 51 ' parallel and facing ( i . e . arranged substantially frontally relative to ) the substantially vertical wall 51 and at a given distance from said wall 51 so that between them there remains defined a substantially vertical discharge channel configured to receive the layer SP of powder material CP from the upper conveyor 50 and unload it onto the lower conveyor 50 ' .
  • the given distance at which the wall 51 and the conveyor belt 51 ' are placed and the distance between a lower edge of the conveyor belt 51 ' and the lower conveyor 50 ' are in relation to the ( in particular, define the ) thickness of the layer SP o f powder material CP that is unloaded onto the lower conveyor 50 ' .
  • the discharge assembly 50 ' ’ (when present ) could be formed by two parallel walls , similar to the wall 51 , or by two parallel conveyor belts , similar to conveyor belt 51 ' , arranged at a given distance from each other so that between them there remains defined a substantially vertical discharge channel configured to receive the layer SP of powder material CP from the upper conveyor 50 and unload it on the lower conveyor 50 ' .
  • the conveyor assembly 5 comprises a single conveyor device 50 , for example comprising a conveyor belt, which extends along the given path P in the conveying direction A from the feeding station 6 to the output station 7.
  • the powder material CP feeding assembly 8 comprises a plurality of feeding devices 9, advantageously digital, for feeding a plurality of types of powder material" CP ⁇ (see for example Figures 1, 2, 3 and 4) .
  • the subscript "i" generally indicates the i-th type of powder material fed by one or more of the feeding devices 9 of the powder material CP feeding assembly 8.
  • the powder material CP feeding assembly 8 comprises six feeding devices 9 for feeding onto the conveyor assembly 5, in particular onto the conveyor 50, three different types of powder material denoted as CPi, CP2, CP3.
  • the different types of powder material CPi, CP2, CP3 have different colours from one another.
  • the different types of powder materials CPi, CP2, CP3 have different physical characteristics from one another. Thanks to the use of different types of powder material CPi, CP2, CP3 the powder material CP feeding assembly 8 can be controlled to form a layer SP of powder material CP having a defined pattern. It is understood that one or more of the different types of powder materials CPi, CP2, CP3 may coincide (i.e. be substantially the same) with each other.
  • each feeding device 9 comprises at least one container 10, for example a containment hopper, for containing a respective type of powder material CPi, which container 10 has a respective exit port 11, whose longitudinal extension is transverse (in particular perpendicular) to the conveying direction A, a plurality of distribution elements 12 arranged one after the other along the respective exit port 11 parallel to each other so as to de fine a build-up plane 13 which is inclined at an angle a relative to the hori zontal and is des igned to receive the powder material Cpii coming out of the exit port 11 ( in particular, a defined amount of the powder material Cp ⁇ coming out of the exit port 11 ) .
  • container 10 for example a containment hopper, for containing a respective type of powder material CPi, which container 10 has a respective exit port 11, whose longitudinal extension is transverse (in particular perpendicular) to the conveying direction A, a plurality of distribution elements 12 arranged one after the other along the respective exit port 11 parallel to each other so as to de fine
  • said build-up plane 13 is oriented so as to de fine said angle a with a hypothetical hori zontal plane ( see Figure 5 ) .
  • said angle a is correlated at least to the internal friction angle and/or to the humidity of the powder material CP ⁇ that the relative feeding device is designed to feed .
  • said angle a varies between about 0 ° ( in particular, about 0 . 5 ° ) and about 20 ° ( in particular, about 10 ° ) .
  • each feeding device 9 further comprises a plurality of actuators 14 ( schematically shown in Figure 5 ) , each configured to operate ( in particular, to operate the movement ) a respective distribution element 12 so as to cause the powder material CPi building up on said build-up plane 13 to fall .
  • each actuator 14 is configured to operate the respective distribution element 12 between a first position, in which this ( i . e . the distribution element 12 itsel f ) defines together with the other distribution elements 12 of the relative feeding device 9 the aforementioned build-up plane 13 so as to allow building up the powder material CPi on said build-up plane 13 and a second pos ition, in which the powder material CPi building up on the build-up plane 13 is caused to fall from a falling edge 15 of the build-up plane 13 itsel f .
  • the exit port 11 has a plurality of ( di f ferent ) passage areas arranged one after the other along the longitudinal extension of the exit port 11 , and each of the aforementioned distribution elements 12 is operable ( advantageously but not in a limiting manner independent of the others ) to allow the escape of the powder material CP ⁇ from one of said passage areas .
  • each of the distribution elements 12 comprises ( in particular, is consists of ) a plate 16 , which ( advantageously, at least in the aforementioned first position) is arranged inclined at the aforementioned angle a relative to the hori zontal so as to allow building up on it the respective type of powder material CP ⁇ .
  • each of the actuators 14 has at least one vibrating element 17 (preferably a plurality of vibrating elements 17 ) which can be vibrated to cause the vibration of the respective distribution element 12 ( in particular, of the plate 16 ) so as to cause the powder material CP ⁇ building up on the build-up plane 13 to fall .
  • said vibrating element 17 can be vibrated at least between the aforementioned first position and the aforementioned second position so as to cause the escape of the built-up powder material CP ( in particular, of the amount of the respective type of powder material CP ⁇ built-up ) on the plate 16 itsel f .
  • each of the actuators 14 comprises a portion 18 made of piezoelectric material , advantageously but not in a limiting manner fixed below the aforementioned plates 16 comprised ( i . e . forming) the distribution elements 12 and the aforementioned operation is carried out by transmitting an electrical operating signal to said portion 18 made of piezoelectric material .
  • the powder material CP feeding assembly 8 is as described in patent application W02009118611 ( of the same applicant ) and/or in patent IT1314623 .
  • the manufacturing system 1 of ceramic articles T also comprises a detection device 19 arranged at least at a detection station 20 downstream of the powder material CP feeding assembly 8 along the conveying path P and configured to detect the height of the powder material CP ⁇ fed on the conveyor assembly 5 ; and a control unit CU configured to control at least the operation of the powder material CP feeding assembly 8 , once calibrated as will be explained below, so that , in use , it forms the aforementioned layer SP of powder ceramic material CP having a given pattern .
  • control unit CU is configured to carry out the calibration operations of the calibration method that will be described below before the use of the manufacturing system 1 of ceramic articles T for the formation of such ceramic articles T , i . e . before the powder material CP feeding assembly 8 is operated to form the aforementioned layer SP of powder ceramic material CP .
  • control unit CU is configured to calibrate the powder material CP feeding assembly 8 , in accordance with the calibration method that will be described below, so as to obtain a calibrated powder material CP feeding assembly 8 ( i . e . so as to ensure that , in use , the feeding devices 9 of the powder material CP feeding assembly 8 feed all the same amount of powder material CP per surface unit ) , and to operate calibrated powder material CP feeding assembly 8 so as to obtain the aforementioned layer SP of powder material , which will then be compacted to obtain the aforementioned layer of compacted powder KP .
  • the manufacturing system 1 o f ceramic articles T also comprises a cutting unit 21 (per se known and not described in detail here ) , arranged at a cutting station 22 downstream of the compaction station 3 along the given path P and configured to cut crosswise the layer of compacted powder KP so as to obtain slabs L each of which has a portion of the layer of compacted powder KP and at least one firing kiln 23 for sintering the layer of compacted powder KP of the slabs L so as to obtain the ceramic articles T .
  • a cutting unit 21 per se known and not described in detail here
  • the manufacturing system 1 o f ceramic articles T also comprises a cutting unit 21 (per se known and not described in detail here ) , arranged at a cutting station 22 downstream of the compaction station 3 along the given path P and configured to cut crosswise the layer of compacted powder KP so as to obtain slabs L each of which has a portion of the layer of compacted powder KP and at least one firing kiln 23 for sintering
  • a cal ibration method for calibrating the above- mentioned powder material CP feeding assembly 8 , prior to its use for manufacturing the above-mentioned layer SP of powder material CP .
  • said calibration method comprises : a feeding step, during which each feeding device 9 of the powder material CP feeding assembly 8 is operated for a defined amount of time so as to feed a strip Sj of powder material CP ⁇ onto the conveyor 50 ; a conveying step, which is ( at least partially) simultaneous with the feeding step , during which the conveyor 50 conveys the strips Sj of powder material CP ⁇ fed by the feeding devices 9 during the feeding step along a given path P (which advantageously coincides - or is part - of the aforementioned given path P, as shown in Figure 1 ) in the conveying direction A at least from the aforementioned feeding station 6 to a detection station 20 .
  • the subscript "j" generally denotes the j-th strip of powder material CP ⁇ fed by the j-th feeding device 9 of the powder material CP feeding assembly 8.
  • the powder material CP feeding assembly 8 comprises six feeding devices 9 and in the feeding step each of them feeds a strip Si, S2, S3, S4, S5 and Ss of powder material CPi, CP2, CP3.
  • each feeding device 9 is operated for a certain defined amount of time so that each of them deposits (at the same time as, i.e. simultaneously, with the other feeding devices 9 of the feeding assembly 8) a strip Sj of powder material CPi.
  • said defined amount of time has a variable extension (i.e. a duration) from about 0.01 seconds to about 20 seconds (in particular, to about 10 seconds) .
  • the calibration method also comprises a detection step, which is (at least partially) subsequent to the feeding step and (at least partially) simultaneous with the conveying step, during which a detection device 19, advantageously arranged at the aforementioned detection station 20, detects the height of each of the strips Sj of powder material CPi fed during the feeding step; and an adjustment step, which is (at least partially) subsequent to the detection step, during which the aforementioned control unit CU adjusts, in feedback, at least the inclination angle a of the build-up plane 13 formed (i.e.
  • the various feeding devices 9 of the powder material CP feeding assembly 8 as a function of the data detected during the detection step, so as to minimize the differences between the heights of the strips Sj of powder material CPi fed by the different detection feeding devices 9 of the feeding assembly 8 ; in particular, so that the various feeding devices 9 of the powder material CP feeding assembly 8 feed strips Sj of powder material CP ⁇ having substantially similar heights .
  • the aforementioned control unit CU adj usts , in feedback, the working frequency and/or the feeding voltage and/or pulse type and/or the pulse density per unit space of the various feeding devices 9 of the powder material CP feeding assembly 8 as a function o f the data detected during the detection step so that the various feeding devices 9 of the powder material CP feeding assembly 8 feed strips Sj of powder material CP ⁇ having substantially similar heights , as mentioned above .
  • Such calibration advantageously allows to rapidly and quickly ensure that all the feeding devices 9 of the powder material CP feeding assembly 8 feed the same amount of powder material CP ⁇ per surface unit regardless of the type of powder material CP ⁇ , i . e . of the internal friction angle and/or the flowability of each type of powder material CP ⁇ .
  • the di f ferent feeding devices 9 of the powder material CP feeding assembly 8 are adj usted, optionally in a di f ferent way from each other, for example by varying the inclination angle a of the build-up plane 13 ( therefore increasing or reducing it ) as a function of the friction angle and/or the humidity of the type of powder material CP ⁇ that is designed to be built-up on it , as well as as a function of the internal friction angle of the other types of powder material CP ⁇ so that , in use ( i . e . in the operating step, i . e . when the powder material CP feeding assembly 8 is used to form the aforementioned layer SP of powder material CP ) , all the feeding devices 9 feed the same amount of material CP ⁇ per surface unit .
  • each of the vibrating elements 17 of the aforementioned actuators 14 of each feeding device 9 is operated ( advantageously for a certain amount of time ) to vibrate the respective distribution device 12 , in particular the respective plate 16 , so as to cause the powder material CP ⁇ building up on the build-up plane 13 to fall and form the strips Sj of powder material CP ⁇ on the conveyor 50 .
  • an electric operating signal is applied to the aforementioned portion 18 made of piezoelectric material of each actuator 14 in order to cause the respective distribution element 12 to vibrate according to a given operating cycle so as to cause the fall from the edge 15 of the build-up plane 13 of a certain amount of powder material CP ⁇ onto the conveyor 50 .
  • the control unit CU adj usts in feedback also (in addition to the aforementioned inclination angle a of the build-up plane 13 ) the frequency and/or the vibration time of the aforementioned vibrating elements 17 as a function of the data detected during the detection step .
  • control unit CU also adj usts in feedback (in addition to the aforementioned inclination angle a of the build-up plane 13 and optionally to the time and/or frequency of vibration of vibrating elements 17 ) the electrical operating signal so as to vary said operating cycle as a function of the data detected during said detection step .
  • the detection device 19 used during the detection step comprises ( in particular, being formed by) at least one level sensor 24 , advantageously but not in a limiting manner arranged orthogonal to the conveyor assembly 5 , and during the detection step the detection device 19 , in particular said level sensor 24 , estimates the height of each strip Sj of powder material CP ⁇ by measuring said height in at least one measuring position .
  • the detection device 19 used during the detection step comprises ( in particular, consists of ) a bar 25 comprising ( in particular carrying) a plurality o f level sensors 24 arranged one after the other along a main direction of development of the bar 25 ( in particular, aligned along the extension of the bar 25 itsel f ) .
  • a level sensor 24 comprises ( in particular, is ) an optical sensor or a laser sensor, or a capacitive sensor or an ultrasonic sensor .
  • the detection device 19 used during the detection step comprises ( in particular, consists of ) any level sensor 24 capable of estimating the height of each strip Sj of powder material CP ⁇ with a required accuracy equal to about 0 . 01 mm .
  • the detection step comprises a translation step, during which the detection device 19 moves crosswise to the conveying direction A in order to estimate the height of each strip Sj of powder material CP ⁇ by measuring said height in a plurality of measuring positions arranged one after the other crosswise to the conveying direction A.
  • the detection device 19 is mounted movably above the conveyor 50 and the manufacturing system 1 of ceramic articles T comprises a movement system (not shown) operable , for example by the aforementioned control unit CU, to move the detection device 19 crosswise to the conveying direction A.
  • the detection device 19 used during the detection step comprises ( in particular, consists of ) a profilometer ( of known type and not described in detail here ) arranged on the conveyor assembly 5 , in particular on the conveyor 50 . This allows the height of each strip Sj of powder material CP ⁇ to be detected along the entire length of the strip Sj itsel f with no need to translate the detection device 19 .
  • the manufacturing method of ceramic articles T comprises the following steps : a compaction step, during which a layer SP of powder material , comprising ( in particular consists of ) ceramic powder CP ⁇ is compacted at a compaction station 3 so as to obtain a layer of compacted powder KP ; and a conveying step, during which the powder material CP is conveyed by a conveyor assembly 5 , along a given path P from a feeding station 6 to a compaction station 3 and the layer of compacted powder KP is conveyed, along the same given path P, from the compaction station 3 to an output station 7 .
  • the conveyor assembly 5 transports the layer SP of powder material CP from the feeding station 6 in a conveying direction A.
  • the conveying step is implemented by means of a conveyor assembly 5 made according to one of the variants described above .
  • the manufacturing method of ceramic articles T further comprises a forming step, which is ( at least partially) simultaneous with the conveying step and ( at least partially) prior to the compaction step, during which powder material CP is fed onto the conveyor assembly 5 by means of a feeding assembly 8 ( advantageously already calibrated as explained above ) so as to generate the aforementioned SP of powder material CP .
  • the feeding assembly 8 is analogous to the one described above with reference to the manufacturing system 1 of ceramic articles T , i . e . it compri ses a plurality o f digital feeding devices 9 , each made as explained above , i . e .
  • a container 10 which is designed to contain a respective type of powder material CP ⁇ and has a respective exit port 11 , whose longitudinal extens ion is transverse ( in particular, perpendicular ) to the conveying direction A, a plurality of distribution elements 12 , which are arranged one after the other along the respective exit port 11 so as to define a build-up plane 13 which is inclined at an angle a relative to the hori zontal and a plurality of actuators 14 , each configured to operate the respective distribution element 12 so as to cause said powder material CP ⁇ building up on the build-up plane 13 to fal l through the area of the exit port 11 where the respective distribution element 12 is arranged .
  • the same considerations as set out above apply with reference to the system 1 for feeding ceramic articles T .
  • the method further comprises a calibration step to calibrate the feeding assembly 8 , which is prior to the forming step, and during which the steps of the cal ibration method described above are carried out so as to calibrate the feeding assembly 8 before operating it to form the aforementioned layer SP of powder material to be fed to the compaction station 3 .
  • the manufacturing method o f ceramic articles T also comprises a further detection step, which is ( at least partial ly) subsequent to the forming step and ( at least partially) simultaneous with the conveying step, during which a detection unit , which advantageously is comprised ( in particular, coincides ) with the detection device 19 (used during the detection step of the abovedescribed calibration method) , detects the height of the layer SP of powder material layer CP ; a height correction step, which is ( at least partial ly) simultaneous with the forming step and ( at least partially) subsequent to the further detection step, during which at least one of the feeding devices 9 of the feeding assembly 8 is operated so as to change the height of the layer SP of powder material CP crosswise to said conveying direction A, as a function of the data detected during said further detection step in order to make the height of the layer SP of material more constant crosswise to the conveying direction A.
  • a detection unit which advantageously is comprised ( in particular, coincides ) with the detection device 19 (used during the detection step of the abovedescribed calibration method
  • the same detection device 19 is used in the detection step of the calibration method to adj ust the various feeding devices 9 of the feeding assembly and in the operating step to detect any unevenness in the layer SP of powder material CP fed by the feeding assembly 8 and correct them .
  • the height correction step could also be carried out by means of any height correction system .
  • a correction device which could be for example a suction device operable to suck di f ferent amounts of powder material CP crosswise to the conveying direction A as a function of the data detected in the abovedescribed further detection step, or even another device for precise deposition of powder material crosswise to the conveying direction A as a function of the data detected in the above-described further detection step .
  • the calibration method of a feeding assembly 8 o f the present invention has numerous advantages including the following ones .
  • the calibration method of the invention allows the feeding assembly 8 to be calibrated quickly and precisely, ensuring that all the feeding devices 9 of said feeding assembly 8 feed the same amount of powder material CP ⁇ per surface unit regardless of the type ( i . e . the flowability and the internal friction angle of the di f ferent types of powder material CP ⁇ ) with no need for long periods of plant downtime and without the manual operations required in the traditional calibration methods (for example to arrange the various calibration tray, optionally to weigh it etc . ) .
  • the calibration method of the present invention thanks to the introduction of the detection device 19 , allows to detect the thickness of the various feeding devices 9 in a single detection step as the aforementioned strips Sj of powder material CP ⁇ are conveyed along the given path P on the conveyor 50 .
  • the adj ustment in feedback is automatic and contextual to the detection, which makes the calibration operation much faster than the known art methods .

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Ceramic Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Manufacturing & Machinery (AREA)
  • Automation & Control Theory (AREA)
  • Devices For Post-Treatments, Processing, Supply, Discharge, And Other Processes (AREA)
  • Filling Or Emptying Of Bunkers, Hoppers, And Tanks (AREA)

Abstract

Calibration method of a powder material (CP) feeding assembly (8) comprising a plurality of feeding devices (9), each having a plurality of operable distribution elements (12) along its exit port (11), inclined at an angle (α) to the horizontal. The calibration method comprises: a feeding step, during which each feeding device (9) feeds a strip (SJ) of powder material (CPi) onto a conveyor (50); a conveying step of the strips of powder material to a detection station (20); a detection step, during which a detection device (19) detects the height of the strips of powder material; and an adjustment step, in which, as a function of the data detected during the detection step, at least the inclination angle (α) of the distribution elements (12) is adjusted, so that all the strips (SJ) of powder material (CPi) fed by the feeding devices (9) have the same height. A manufacturing system (1) of ceramic articles (T) implementing this calibration method is also claimed.

Description

CALIBRATION METHOD OF A POWDER MATERIAL FEEDING ASSEMBLY AND MANUFACTURING SYSTEM OF CERAMIC ARTICLES IMPLEMENTING SAID METHOD
Cross-Reference to Related Applications
This patent application is related to Italian Patent Application No . 102022000013330 fi led on June 23 , 2022 , the entire disclosure of which is incorporated herein by reference .
Field Of The Art
The present invention relates to a calibration method of a powder material feeding assembly; in particular, of powder ceramic material . More particularly, the invention refers to the calibration of a powder material feeding assembly used for the manufacture of ceramic articles ; in particular, of ceramic slabs and tiles .
Background of the Invention
In the field of the production of ceramic articles it is increasingly felt the need to make ceramic articles , such as ceramic slabs and tiles , whose aesthetic appearance reproduces a certain pattern, for example the appearance of natural stones , such as marbles , granites etc . by feeding a main background colour and the formation of a series of streaks/veins of di f ferent colour and shape that develop with random course within the thickness of the background colour ; or by making designs and/or gradient ef fects by controlled feeding of a mixture of ceramic powder material of di f ferent colour etc . .
These di f ferent aesthetic ef fects are formed by means of feeding assemblies of known type , for example those described in documents W02009118611 and IT1314623 ( of the same Applicant ) which provide a plurality of digital feeding devices , known as printheads , configured to feed di f ferent types of powder material in a controlled manner on a conveyor so as to form a layer of powder ceramic material having the desired decoration (pattern) .
Each of said feeding devices comprises a container of powder material , an exit port extending crosswise to the conveyor, a plurality of distribution elements mutually flanked so as to define a build-up plane , which is designed to receive the material exiting from the exit port and is inclined at an angle lower than the friction angle of the powder material so that the material exiting from the exit port can build up on said inclined build-up plane , and a plurality of actuators each configured to operate the movement ( in particular, to vibrate ) the aforementioned distribution elements so that the material built-up on the build-up plane slides towards a falling edge of said plane and falls on the conveyor .
In order to guarantee optimal results , in terms of homogeneity of distribution of the layer of powder material , and therefore of quality of the pattern created through the feeding assembly described above , but also to avoid the risk of distortion of the pattern present on the layer o f powder material while it is conveyed through the various workstations ( for example during its passage through one or more discharge devices ) it is necessary that the various feeding devices of the feeding assembly feed all the same amount ( flow rate ) of powder material per surface unit , regardless of the type of powder material that they feed; in particular, regardless of the friction angle ( i . e . the flowability or fluidity) of the di f ferent types of powder material that the various feeding devices are designed to feed .
Precisely for this reason it is important that the feeding assembly used to manufacture and/or decorate the ceramic articles is calibrated appropriately . To date , such calibration takes place by carrying out measurements of weight of the powder material that each feeding device feeds in the unit of time , so as to estimate the flow rate of powder material fed by each feeding device and adj ust the various feeding devices accordingly .
In detail , these flow rate measurements are carried out by using a calibration tray of known dimensions ( therefore of known surface units ) that is conveyed on a conveyor that extends under the di f ferent feeding devices of the feeding assembly so that the powder material fed by the various feeding devices is collected in the calibration tray, which, once the powder material is received from a feeding device , is weighed . In this way, given the dimensions of the calibration tray and the weight of the powder material collected therein, it is possible to determine the flow rate of powder material fed by the feeding device per surface unit . This operation is repeated for each feeding device of the feeding assembly, the di f ferent flow rate values are then compared and, as a function of this comparison, the operating parameters of the feeding assembly are adj usted so that all the feeding devices feed the same amount o f powder material per surface unit . Such adj ustment takes place , for example , by varying the operation of the feeding devices , in terms of time of operation, or of frequency or ampl itude of the electrical signal that sets the various di stribution elements in motion, or by varying the inclination of the distribution elements of the various digital feeding devices etc .
An example of such a calibration method is described, for example , in document ITRE20110061 .
This mode of calibration has , however, multiple limitations , among which we mention the following .
Firstly, this is a fairly long calibration methodology as it involves the need to pass the calibration tray below the operation assembly a number of times similar to the number of feeding devices of each feeding assembly, then calculating the flow rate of each of these feeding devices and consequently adj usting the various operating parameters of the feeding assembly . In addition, the adj ustment operations are performed substantially manually, with all the disadvantages in terms of precision and slownes s of the operations .
Aim of the present invention is to provide a calibration method of a powder material feeding assembly, which allows to overcome , at least in part , the drawbacks of the known art .
Summary
In accordance with the present invention there is proposed a calibration method of a powder material feeding assembly, in particular of a powder ceramic material , according to what is mentioned in the appended independent claims , and preferably, in any one of the claims directly or indirectly dependent on the mentioned independent claims .
The claims describe preferred embodiments of the present invention forming an integral part of the present disclosure .
Brief Description of the Drawings
The invention is now described with reference to the accompanying drawings , which show some non-limiting examples of embodiments , wherein :
Figure 1 represents a schematic side view of a manufacturing system of ceramic articles ;
- Figures 2 and 3 are schematic and perspective views of two di f ferent variants of part of the manufacturing system of ceramic articles of Figure 1 , during the calibration operations of the powder material feeding assembly carried out in accordance with the present invention;
- Figure 4 is a schematic side view of the powder material feeding assembly shown in Figures 2 and 3 during the calibration operations of the feeding assembly itsel f ; in particular, this figure shows a detection device that detects one ( the first ) of the fed strips of powder material of the powder material feeding assembly;
- Figure 5 is a schematic side view of a feeding device of the feeding as sembly schematically shown in Figures 2 , 3 and 4 while it feeds powder material ; and
- Figures 6 and 7 are two views from above and on an enlarged scale of a part of Figures 2 and 3 to better visuali ze the di f ferent transversal positions that the detection device can assume during the calibration operations of the feeding assembly .
Detailed Description
In the accompanying figures , number 1 denotes as a whole a manufacturing system 1 of ceramic articles T . In particular, the ceramic articles T are ceramic slabs or tiles .
With particular reference to Figure 1 , the manufacturing system 1 of ceramic articles T comprises : a compaction device 2 (per se known and not further described herein) , which is arranged at a compaction station 3 and is configured to compact , preferably substantially continuously, a layer SP of ceramic powder material CP, comprising ceramic powder, in order to obtain a layer of compacted powder KP ; and a conveyor assembly 5 which is configured to transport ( advantageously but not necessarily substantially continuously) the layer SP of powder material CP along a given path P ( schematically represented with a dotted line in Figure 1 ) from a feeding station 6 to the compaction station 3 , and to transport the layer of compacted powder KP from the compaction station 3 to an output station 7 always along the given path P .
The manufacturing system 1 of ceramic articles T further comprises : a powder material CP feeding assembly 8 , which is configured to feed the powder material CP, comprising ceramic powder, to the conveyor assembly 5 ( in particular, above the conveyor assembly 5 ; even more in particular, above a conveyor 50 of the conveyor assembly 5 ) , at the feeding station 6 , so as to generate said layer SP of powder material CP . By the term "powder material CP" is meant any inconsistent solid material , for example also in granular form, advantageously but not in a limiting manner, comprising ( in particular, consisting of ) ceramic powder, for example containing clays , sands and/or feldspars etc .
Advantageously but not in a limiting manner, the conveyor assembly 5 is arranged and configured to support from below the layer SP of powder material CP and the layer of compacted powder KP along the given path P . Even more in detail , according to some advantageous but not exclusive embodiments such as the ones shown in Figures 1 and 2 , the conveyor assembly 5 comprises , in turn : an upper conveyor 50 , for example a conveyor belt , which extends at the aforementioned feeding station 6 ; a lower conveyor 50 ' , which is arranged at a lower height than the upper conveyor 50 and extends downstream of the upper conveyor 50 along the given path P and a discharge assembly 50 ' ’ arranged immediately downstream of the upper conveyor 50 and immediately upstream of the lower conveyor 50 ' along the given path P and, advantageously but not in a limiting manner, configured to level out ( i f necessary) the layer SP of powder material CP before unloading it on the lower conveyor 50 ' . Advantageously but not in a limiting manner, the discharge assembly 50 ' ’ (when present ) comprises ( in particular, is defined by) a substantially vertical wall 51 extending perpendicularly to the conveying direction A below the upper conveyor 50 and above the lower conveyor 50 ' and a conveyor belt 51 ' parallel and facing ( i . e . arranged substantially frontally relative to ) the substantially vertical wall 51 and at a given distance from said wall 51 so that between them there remains defined a substantially vertical discharge channel configured to receive the layer SP of powder material CP from the upper conveyor 50 and unload it onto the lower conveyor 50 ' . Even more particularly, the given distance at which the wall 51 and the conveyor belt 51 ' are placed and the distance between a lower edge of the conveyor belt 51 ' and the lower conveyor 50 ' are in relation to the ( in particular, define the ) thickness of the layer SP o f powder material CP that is unloaded onto the lower conveyor 50 ' . It is understood that according to other embodiments not shown the discharge assembly 50 ' ’ (when present ) could be formed by two parallel walls , similar to the wall 51 , or by two parallel conveyor belts , similar to conveyor belt 51 ' , arranged at a given distance from each other so that between them there remains defined a substantially vertical discharge channel configured to receive the layer SP of powder material CP from the upper conveyor 50 and unload it on the lower conveyor 50 ' .
According to other non-limiting embodiments ( such as the one shown in Figure 3 ) , the conveyor assembly 5 comprises a single conveyor device 50 , for example comprising a conveyor belt, which extends along the given path P in the conveying direction A from the feeding station 6 to the output station 7.
Advantageously, the powder material CP feeding assembly 8 comprises a plurality of feeding devices 9, advantageously digital, for feeding a plurality of types of powder material" CP± (see for example Figures 1, 2, 3 and 4) . The subscript "i" generally indicates the i-th type of powder material fed by one or more of the feeding devices 9 of the powder material CP feeding assembly 8. In particular, in the non-limiting embodiments shown in Figures 2, 3 and 4, the powder material CP feeding assembly 8 comprises six feeding devices 9 for feeding onto the conveyor assembly 5, in particular onto the conveyor 50, three different types of powder material denoted as CPi, CP2, CP3. The different types of powder material CPi, CP2, CP3 have different colours from one another. Alternatively or in addition, the different types of powder materials CPi, CP2, CP3 have different physical characteristics from one another. Thanks to the use of different types of powder material CPi, CP2, CP3 the powder material CP feeding assembly 8 can be controlled to form a layer SP of powder material CP having a defined pattern. It is understood that one or more of the different types of powder materials CPi, CP2, CP3 may coincide (i.e. be substantially the same) with each other.
According to some advantageous but non-limiting embodiments (such as the one shown in Figure 5) , each feeding device 9 comprises at least one container 10, for example a containment hopper, for containing a respective type of powder material CPi, which container 10 has a respective exit port 11, whose longitudinal extension is transverse (in particular perpendicular) to the conveying direction A, a plurality of distribution elements 12 arranged one after the other along the respective exit port 11 parallel to each other so as to de fine a build-up plane 13 which is inclined at an angle a relative to the hori zontal and is des igned to receive the powder material Cpii coming out of the exit port 11 ( in particular, a defined amount of the powder material Cp± coming out of the exit port 11 ) . In particular ( advantageously but not in a limiting manner ) said build-up plane 13 is oriented so as to de fine said angle a with a hypothetical hori zontal plane ( see Figure 5 ) . Advantageously but not in a limiting manner, said angle a is correlated at least to the internal friction angle and/or to the humidity of the powder material CP± that the relative feeding device is designed to feed . Even more advantageously but not in a limiting manner, said angle a varies between about 0 ° ( in particular, about 0 . 5 ° ) and about 20 ° ( in particular, about 10 ° ) .
Advantageously, each feeding device 9 further comprises a plurality of actuators 14 ( schematically shown in Figure 5 ) , each configured to operate ( in particular, to operate the movement ) a respective distribution element 12 so as to cause the powder material CPi building up on said build-up plane 13 to fall .
In detail , advantageously but not in a limiting manner, each actuator 14 is configured to operate the respective distribution element 12 between a first position, in which this ( i . e . the distribution element 12 itsel f ) defines together with the other distribution elements 12 of the relative feeding device 9 the aforementioned build-up plane 13 so as to allow building up the powder material CPi on said build-up plane 13 and a second pos ition, in which the powder material CPi building up on the build-up plane 13 is caused to fall from a falling edge 15 of the build-up plane 13 itsel f . Even more in detail , advantageously but not in a limiting manner in the second position there is defined an opening through which it is possible the passage ( in particular the escape ) of the respective type of powder material CP± towards the conveyor assembly 5 ; in particular, towards the conveyor 50 . Even more advantageously but not in a limiting manner, in this second position the build-up plane 13 ( in particular, each distribution element 12 ) is inclined at an angle greater than the static friction angle of the powder material CP± causing it to fall from the aforementioned edge 15 . Alternatively or in combination ( advantageously but not in a limiting manner ) , in the first position there is also defined a further opening . In this case , advantageously but not in a limiting manner, this further opening has a smaller extension than the aforementioned opening defined in the second position .
According to some non-limiting embodiments , the exit port 11 has a plurality of ( di f ferent ) passage areas arranged one after the other along the longitudinal extension of the exit port 11 , and each of the aforementioned distribution elements 12 is operable ( advantageously but not in a limiting manner independent of the others ) to allow the escape of the powder material CP± from one of said passage areas .
According to some advantageous but non-limiting embodiments , each of the distribution elements 12 comprises ( in particular, is consists of ) a plate 16 , which ( advantageously, at least in the aforementioned first position) is arranged inclined at the aforementioned angle a relative to the hori zontal so as to allow building up on it the respective type of powder material CP± .
According to some advantageous but non-limiting embodiments , each of the actuators 14 has at least one vibrating element 17 (preferably a plurality of vibrating elements 17 ) which can be vibrated to cause the vibration of the respective distribution element 12 ( in particular, of the plate 16 ) so as to cause the powder material CP± building up on the build-up plane 13 to fall . Even more in detail , advantageously but not in a limiting manner, said vibrating element 17 can be vibrated at least between the aforementioned first position and the aforementioned second position so as to cause the escape of the built-up powder material CP ( in particular, of the amount of the respective type of powder material CP± built-up ) on the plate 16 itsel f . Even more particularly, advantageously but not in a limiting manner, each of the actuators 14 comprises a portion 18 made of piezoelectric material , advantageously but not in a limiting manner fixed below the aforementioned plates 16 comprised ( i . e . forming) the distribution elements 12 and the aforementioned operation is carried out by transmitting an electrical operating signal to said portion 18 made of piezoelectric material . In other words , in these cases , the vibration trans ferred from the vibrating element 17 to each distribution element 12 causes the progressive sliding of the powder material CP bui lding up on the build-up plane 13 towards the falling edge 15 , from which, by gravity, said powder material CP± falls downwards , thus being unloaded onto the conveyor assembly 5 , even more in particular onto the conveyor 50 . As the powder material CPi falls from the falling edge 15 , other powder material CPi escapes from the exit port 11 and builds up on the build-up plane 13 , so as to be able to have a continuous flow with no interruptions of powder material CPi .
According to some non-limiting embodiments ( such as the ones shown in the accompanying figures ) , the powder material CP feeding assembly 8 is as described in patent application W02009118611 ( of the same applicant ) and/or in patent IT1314623 .
Advantageously but not necessarily, the manufacturing system 1 of ceramic articles T also comprises a detection device 19 arranged at least at a detection station 20 downstream of the powder material CP feeding assembly 8 along the conveying path P and configured to detect the height of the powder material CP± fed on the conveyor assembly 5 ; and a control unit CU configured to control at least the operation of the powder material CP feeding assembly 8 , once calibrated as will be explained below, so that , in use , it forms the aforementioned layer SP of powder ceramic material CP having a given pattern .
In other words ( advantageously but not in a limiting manner ) the control unit CU is configured to carry out the calibration operations of the calibration method that will be described below before the use of the manufacturing system 1 of ceramic articles T for the formation of such ceramic articles T , i . e . before the powder material CP feeding assembly 8 is operated to form the aforementioned layer SP of powder ceramic material CP .
Advantageously but not in a limiting manner, the control unit CU is configured to calibrate the powder material CP feeding assembly 8 , in accordance with the calibration method that will be described below, so as to obtain a calibrated powder material CP feeding assembly 8 ( i . e . so as to ensure that , in use , the feeding devices 9 of the powder material CP feeding assembly 8 feed all the same amount of powder material CP per surface unit ) , and to operate calibrated powder material CP feeding assembly 8 so as to obtain the aforementioned layer SP of powder material , which will then be compacted to obtain the aforementioned layer of compacted powder KP .
According to some non-limiting embodiments ( such as the one shown in Figure 1 ) the manufacturing system 1 o f ceramic articles T also comprises a cutting unit 21 (per se known and not described in detail here ) , arranged at a cutting station 22 downstream of the compaction station 3 along the given path P and configured to cut crosswise the layer of compacted powder KP so as to obtain slabs L each of which has a portion of the layer of compacted powder KP and at least one firing kiln 23 for sintering the layer of compacted powder KP of the slabs L so as to obtain the ceramic articles T .
According to one aspect of the present invention, there is proposed a cal ibration method for calibrating the above- mentioned powder material CP feeding assembly 8 , prior to its use for manufacturing the above-mentioned layer SP of powder material CP .
With particular reference to Figures 2 , 3 and 4 , advantageously, said calibration method comprises : a feeding step, during which each feeding device 9 of the powder material CP feeding assembly 8 is operated for a defined amount of time so as to feed a strip Sj of powder material CP± onto the conveyor 50 ; a conveying step, which is ( at least partially) simultaneous with the feeding step , during which the conveyor 50 conveys the strips Sj of powder material CP± fed by the feeding devices 9 during the feeding step along a given path P (which advantageously coincides - or is part - of the aforementioned given path P, as shown in Figure 1 ) in the conveying direction A at least from the aforementioned feeding station 6 to a detection station 20 . The subscript "j" generally denotes the j-th strip of powder material CP± fed by the j-th feeding device 9 of the powder material CP feeding assembly 8. In particular, in the nonlimiting embodiments shown in Figures 2, 3 and 4, the powder material CP feeding assembly 8 comprises six feeding devices 9 and in the feeding step each of them feeds a strip Si, S2, S3, S4, S5 and Ss of powder material CPi, CP2, CP3.
Advantageously but not in a limiting manner, during the feeding step each feeding device 9 is operated for a certain defined amount of time so that each of them deposits (at the same time as, i.e. simultaneously, with the other feeding devices 9 of the feeding assembly 8) a strip Sj of powder material CPi. Advantageously but not in a limiting manner, said defined amount of time has a variable extension (i.e. a duration) from about 0.01 seconds to about 20 seconds (in particular, to about 10 seconds) .
Advantageously, the calibration method also comprises a detection step, which is (at least partially) subsequent to the feeding step and (at least partially) simultaneous with the conveying step, during which a detection device 19, advantageously arranged at the aforementioned detection station 20, detects the height of each of the strips Sj of powder material CPi fed during the feeding step; and an adjustment step, which is (at least partially) subsequent to the detection step, during which the aforementioned control unit CU adjusts, in feedback, at least the inclination angle a of the build-up plane 13 formed (i.e. defined) of the various feeding devices 9 of the powder material CP feeding assembly 8 as a function of the data detected during the detection step, so as to minimize the differences between the heights of the strips Sj of powder material CPi fed by the different detection feeding devices 9 of the feeding assembly 8 ; in particular, so that the various feeding devices 9 of the powder material CP feeding assembly 8 feed strips Sj of powder material CP± having substantially similar heights . Alternatively or additionally, according to some advantageous but non-limiting embodiments , during the adj ustment step the aforementioned control unit CU adj usts , in feedback, the working frequency and/or the feeding voltage and/or pulse type and/or the pulse density per unit space of the various feeding devices 9 of the powder material CP feeding assembly 8 as a function o f the data detected during the detection step so that the various feeding devices 9 of the powder material CP feeding assembly 8 feed strips Sj of powder material CP± having substantially similar heights , as mentioned above .
Such calibration advantageously allows to rapidly and quickly ensure that all the feeding devices 9 of the powder material CP feeding assembly 8 feed the same amount of powder material CP± per surface unit regardless of the type of powder material CP±, i . e . of the internal friction angle and/or the flowability of each type of powder material CP± . Even more in detail , precisely to take into account the possible di f ferences between the various types of powder material CP± the di f ferent feeding devices 9 of the powder material CP feeding assembly 8 are adj usted, optionally in a di f ferent way from each other, for example by varying the inclination angle a of the build-up plane 13 ( therefore increasing or reducing it ) as a function of the friction angle and/or the humidity of the type of powder material CP± that is designed to be built-up on it , as well as as a function of the internal friction angle of the other types of powder material CP± so that , in use ( i . e . in the operating step, i . e . when the powder material CP feeding assembly 8 is used to form the aforementioned layer SP of powder material CP ) , all the feeding devices 9 feed the same amount of material CP± per surface unit .
According to some advantageous but non-limiting embodiments (when the aforementioned actuators 14 of the feeding device 9 comprise the aforementioned vibrating elements 17 ) , during the feeding step each of the vibrating elements 17 of the aforementioned actuators 14 of each feeding device 9 is operated ( advantageously for a certain amount of time ) to vibrate the respective distribution device 12 , in particular the respective plate 16 , so as to cause the powder material CP± building up on the build-up plane 13 to fall and form the strips Sj of powder material CP± on the conveyor 50 .
Even more in detail , according to some advantageous but non-limiting embodiments , during the feeding step an electric operating signal is applied to the aforementioned portion 18 made of piezoelectric material of each actuator 14 in order to cause the respective distribution element 12 to vibrate according to a given operating cycle so as to cause the fall from the edge 15 of the build-up plane 13 of a certain amount of powder material CP± onto the conveyor 50 .
According to some advantageous but non-limiting embodiments , during the adj ustment step, the control unit CU adj usts in feedback also ( in addition to the aforementioned inclination angle a of the build-up plane 13 ) the frequency and/or the vibration time of the aforementioned vibrating elements 17 as a function of the data detected during the detection step .
Alternatively or additionally, advantageously but not in a limiting manner, during said adj ustment step said control unit CU also adj usts in feedback ( in addition to the aforementioned inclination angle a of the build-up plane 13 and optionally to the time and/or frequency of vibration of vibrating elements 17 ) the electrical operating signal so as to vary said operating cycle as a function of the data detected during said detection step .
According to some advantageous but not exclusive embodiments , the detection device 19 used during the detection step comprises ( in particular, being formed by) at least one level sensor 24 , advantageously but not in a limiting manner arranged orthogonal to the conveyor assembly 5 , and during the detection step the detection device 19 , in particular said level sensor 24 , estimates the height of each strip Sj of powder material CP± by measuring said height in at least one measuring position .
According to some advantageous but not exclusive embodiments such as the ones shown in Figures 2 and 3 , the detection device 19 used during the detection step comprises ( in particular, consists of ) a bar 25 comprising ( in particular carrying) a plurality o f level sensors 24 arranged one after the other along a main direction of development of the bar 25 ( in particular, aligned along the extension of the bar 25 itsel f ) . Alternatively or in combination, advantageously but not in a limiting manner, such a level sensor 24 comprises ( in particular, is ) an optical sensor or a laser sensor, or a capacitive sensor or an ultrasonic sensor . Even more advantageously but not in a limiting manner, the detection device 19 used during the detection step comprises ( in particular, consists of ) any level sensor 24 capable of estimating the height of each strip Sj of powder material CP± with a required accuracy equal to about 0 . 01 mm . With particular reference to Figures 6 and 7 , advantageously but not in a limiting manner, the detection step comprises a translation step, during which the detection device 19 moves crosswise to the conveying direction A in order to estimate the height of each strip Sj of powder material CP± by measuring said height in a plurality of measuring positions arranged one after the other crosswise to the conveying direction A. This allows the height of each strip Sj of powder material CP± to be more accurately estimated by making level measurements along the entire length of the strip, as can be seen in Figures 6 and 7 . In these cases , advantageously but not in a limiting manner, the detection device 19 is mounted movably above the conveyor 50 and the manufacturing system 1 of ceramic articles T comprises a movement system (not shown) operable , for example by the aforementioned control unit CU, to move the detection device 19 crosswise to the conveying direction A.
According to yet other advantageous but not exclusive embodiments not shown, the detection device 19 used during the detection step comprises ( in particular, consists of ) a profilometer ( of known type and not described in detail here ) arranged on the conveyor assembly 5 , in particular on the conveyor 50 . This allows the height of each strip Sj of powder material CP± to be detected along the entire length of the strip Sj itsel f with no need to translate the detection device 19 .
According to a further aspect of the present invention, there is proposed a manufacturing method of ceramic articles T , in particular ceramic slabs or tiles .
The manufacturing method of ceramic articles T comprises the following steps : a compaction step, during which a layer SP of powder material , comprising ( in particular consists of ) ceramic powder CP± is compacted at a compaction station 3 so as to obtain a layer of compacted powder KP ; and a conveying step, during which the powder material CP is conveyed by a conveyor assembly 5 , along a given path P from a feeding station 6 to a compaction station 3 and the layer of compacted powder KP is conveyed, along the same given path P, from the compaction station 3 to an output station 7 .
Advantageously, but not in a limiting manner, during such a conveying step, the conveyor assembly 5 transports the layer SP of powder material CP from the feeding station 6 in a conveying direction A.
Even more particularly, in an advantageous but not in a limiting way, the conveying step is implemented by means of a conveyor assembly 5 made according to one of the variants described above .
Advantageously, the manufacturing method of ceramic articles T further comprises a forming step, which is ( at least partially) simultaneous with the conveying step and ( at least partially) prior to the compaction step, during which powder material CP is fed onto the conveyor assembly 5 by means of a feeding assembly 8 ( advantageously already calibrated as explained above ) so as to generate the aforementioned SP of powder material CP .
Advantageously but not in a limiting manner, the feeding assembly 8 is analogous to the one described above with reference to the manufacturing system 1 of ceramic articles T , i . e . it compri ses a plurality o f digital feeding devices 9 , each made as explained above , i . e . comprising at least one container 10 , which is designed to contain a respective type of powder material CP± and has a respective exit port 11 , whose longitudinal extens ion is transverse ( in particular, perpendicular ) to the conveying direction A, a plurality of distribution elements 12 , which are arranged one after the other along the respective exit port 11 so as to define a build-up plane 13 which is inclined at an angle a relative to the hori zontal and a plurality of actuators 14 , each configured to operate the respective distribution element 12 so as to cause said powder material CP± building up on the build-up plane 13 to fal l through the area of the exit port 11 where the respective distribution element 12 is arranged . In detail , for such feeding devices 9 the same considerations as set out above apply with reference to the system 1 for feeding ceramic articles T .
The method further comprises a calibration step to calibrate the feeding assembly 8 , which is prior to the forming step, and during which the steps of the cal ibration method described above are carried out so as to calibrate the feeding assembly 8 before operating it to form the aforementioned layer SP of powder material to be fed to the compaction station 3 .
Furthermore , according to some advantageous but nonlimiting embodiments , the manufacturing method o f ceramic articles T also comprises a further detection step, which is ( at least partial ly) subsequent to the forming step and ( at least partially) simultaneous with the conveying step, during which a detection unit , which advantageously is comprised ( in particular, coincides ) with the detection device 19 (used during the detection step of the abovedescribed calibration method) , detects the height of the layer SP of powder material layer CP ; a height correction step, which is ( at least partial ly) simultaneous with the forming step and ( at least partially) subsequent to the further detection step, during which at least one of the feeding devices 9 of the feeding assembly 8 is operated so as to change the height of the layer SP of powder material CP crosswise to said conveying direction A, as a function of the data detected during said further detection step in order to make the height of the layer SP of material more constant crosswise to the conveying direction A.
This allows , advantageously but not in a limiting manner, with a single detection device 19 to carry out the above-described calibration operations but also to keep the operation of the feeding assembly 8 monitored in the operating step . In other words , the same detection device 19 is used in the detection step of the calibration method to adj ust the various feeding devices 9 of the feeding assembly and in the operating step to detect any unevenness in the layer SP of powder material CP fed by the feeding assembly 8 and correct them .
It is understood that the height correction step could also be carried out by means of any height correction system . In other words , during the above mentioned height correction step instead of acting in feedback on one of the feeding devices 9 of the feeding assembly 8 one could, for example , operate a special correction device (not shown) . In this case the above-described manufacturing system of ceramic articles 1 also comprises a correction device , which could be for example a suction device operable to suck di f ferent amounts of powder material CP crosswise to the conveying direction A as a function of the data detected in the abovedescribed further detection step, or even another device for precise deposition of powder material crosswise to the conveying direction A as a function of the data detected in the above-described further detection step .
The calibration method of a feeding assembly 8 o f the present invention has numerous advantages including the following ones .
The calibration method of the invention allows the feeding assembly 8 to be calibrated quickly and precisely, ensuring that all the feeding devices 9 of said feeding assembly 8 feed the same amount of powder material CP± per surface unit regardless of the type ( i . e . the flowability and the internal friction angle of the di f ferent types of powder material CP± ) with no need for long periods of plant downtime and without the manual operations required in the traditional calibration methods ( for example to arrange the various calibration tray, optionally to weigh it etc . ) .
Furthermore , the calibration method of the present invention, thanks to the introduction of the detection device 19 , allows to detect the thickness of the various feeding devices 9 in a single detection step as the aforementioned strips Sj of powder material CP± are conveyed along the given path P on the conveyor 50 . In this way the adj ustment in feedback is automatic and contextual to the detection, which makes the calibration operation much faster than the known art methods .

Claims

C L A I M S
1. A calibration method of a powder material (CP) feeding assembly (8) , said powder material (CP) feeding assembly (8) comprises a plurality of feeding devices (9) , each comprising, in turn, a container (10) designed to contain a type of powder material (CP±) , an exit port (11) , a plurality of distribution elements (12) arranged one after the other along the exit port (11) so as to define a buildup plane (13) , which is inclined at an angle (a) relative to the horizontal and is intended to receive, resting on it, the powder material (CP±) coming out of said exit port (11) , and a plurality of actuators (14) , each configured to operate the respective distribution element (12) so as to cause said powder material (CP±) building up on said build-up plane (13) to fall; the calibration method of a powder material (CP) feeding assembly (8) comprises the following steps: a feeding step, during which each feeding device (9) of said powder material (CP) feeding assembly (8) is operated for a defined amount of time so as to feed a strip (Sj) of powder material (CPi) onto a conveyor (50) ; a conveying step, which is at least partially simultaneous with said feeding step and during which said conveyor (50) conveys the strips (Sj) of powder material (CPi) fed by the feeding devices (9) during said feeding step along a given path (P) in a conveying direction (A) from a feeding station (6) to a detection station (20) ; a detection step, which is at least partially subsequent to said feeding step and at least partially simultaneous with said conveying step and during which a detection device (19) detects the height of each one of said strips (Sj) of powder material (CPi) ; and an adjustment step, which is at least partially subsequent to said detection step and during which a control unit (CU) adjusts at least said inclination angle (a) of said build-up plane (13) formed by said feeding devices (9) of said powder material (CP) feeding assembly (8) as a function of the data detected during said detection step, so as to minimize the differences between the heights of the strips (Sj) of powder material (CP±) fed by the different feeding devices of said feeding assembly.
2. The calibration method of a powder material (CP) feeding assembly (8) according to claim 1, wherein: each one of said actuators (14) of each one of said feeding devices (9) has at least one vibrating element (17) ; during said feeding step, each one of said vibrating elements (17) is operated so as to cause the respective distribution device (12) to vibrate, thus casing said powder material (CPi) building up on said build-up plane (13) to fall and to form said strips (Sj) of powder material (CPi) on said conveyor (50) ; and during said adjustment step said control unit (CU) also adjusts the vibration frequency and/or time of said vibrating elements as a function of the data detected during said detection step.
3. The calibration method of a powder material (CP) feeding assembly (8) according to claim 2, wherein: each vibrating element (17) comprises (in particular, consists of) a portion (18) made of a piezoelectric material; during said feeding step, an electric operating signal is applied to said portion (18) made of a piezoelectric material in order cause the respective distribution element (12) to vibrate according to a given operating cycle; and, during said adjustment step, said control unit (CU) also adjusts said electric operating signal so as to change said operating cycle as a function of the data detected during said detection step.
4. The calibration method of a powder material (CP) feeding assembly (8) according to any one of the preceding claims, wherein, during said detection step, said detection device (19) estimates the height of each strip (Sj) of powder material (CP±) by measuring said height in at least one measuring position; the detection device used during said detection step comprising (in particular, consisting of) at least one level sensor.
5. The calibration method of a powder material (CP) feeding assembly (8) according to any one of the preceding claims, wherein said detection step comprises a translation step, during which the detection device (19) moves crosswise to the conveying direction (A) in order to estimate the height of each strip (Sj) of powder material (CP±) by measuring said height in a plurality of measuring positions arranged one after the other crosswise to the conveying direction (A) ; in particular, the detection device (19) used during the detection step comprises (in particular, consists of) a bar (25) comprising a plurality of level sensors (24) arranged one after the other along a main direction of development of said bar (25) .
6. The calibration method of a powder material (CP) feeding assembly (8) according to any one of the preceding claims, wherein said detection device (19) used during said detection step comprises (in particular, is) a profilometer.
7. A manufacturing method of ceramic articles (T) , in particular ceramic slabs or tiles, the manufacturing method of ceramic articles (T) comprises the following steps: a compaction step, during which a layer (SP) of powder material (CP) comprising ceramic powder is compacted at a compaction station (3) so as to obtain a layer of compacted powder (KP) ; a conveying step, during which said layer (SP) of powder material (CP) is conveyed by a conveyor assembly (5) along a given path (P) from a feeding station (6) to the compaction station (3) and said layer of compacted powder (KP) is conveyed, along said given path (P) , from said compaction station (3) to an output station (7) ; a forming step, which is at least partially simultaneous with said conveying step and at least partially prior to said compaction step and during which powder material (CP) is fed onto said conveyor assembly (5) by means of a powder material (CP) feeding assembly (8) so as to form said layer (SP) of said powder material (CP) ; said powder material (CP) feeding assembly (8) comprising a plurality of digital feeding devices (9) , each comprising, in turn, at least one container (10) , which is designed to contain a respective type of powder material (CP±) and has an exit port (11) , whose longitudinal extension is transverse (in particular, perpendicular) to the conveying direction (A) , a plurality of distribution elements (12) , which are arranged one after the other along the exit port (11) so as to define a build-up plane (13) , which is inclined at an angle (a) relative to the horizontal, and a plurality of actuators (14) , each configured to operate the respective distribution element (12) so as to cause said powder material (CP±) building up on said build-up plane (13) to fall through the area of the exit port (11) where the respective distribution element (12) is arranged; said manufacturing method of ceramic articles (T) further comprises a calibration step to calibrate said powder material (CP) feeding assembly (8) , which is prior to said forming step and during which the steps of the calibration method of claims 1 to 5 are carried out.
8. The manufacturing method of ceramic articles (T) according to claim 7, comprising: a further detection step, which is at least partially subsequent to said forming step and at least partially simultaneous with said conveying step and during which a detection unit detects the height of said layer (SP) of said powder material (CP) ; and a height correction step, which is at least partially simultaneous with said forming step and is at least partially subsequent to said further detection step and during which at least one of said feeding devices (9) of said powder material (CP) feeding assembly (8) is operated so as to change the height of said layer (SP) of powder material (CP) crosswise to said conveying direction (A) as a function of the data detected during said further detection step, in order to make the height of the layer (SP) of material more constant crosswise to said conveying direction (A) ; said detection unit being comprised in (in particular, coinciding with) the detection device used during said detection step of said calibration method.
9. A manufacturing system (1) of ceramic articles (T) , in particular ceramic slabs or tiles; said manufacturing system (1) comprises: a compaction device (2) , which is arranged at a compaction station (3) and is configured to compact a layer (SP) of powder material (CP) comprising ceramic powder in order to obtain a layer of compacted powder (KP) ; a conveyor assembly (5) to transport said layer (SP) of powder material (CP) along a given path (P) in a conveying direction (A) from a feeding station (6) to said compaction station (3) and the layer of compacted powder (KP) from the compaction station (3) to an output station (7) ; a powder material (CP) feeding assembly (8) , which is configured to feed the powder material (CP) to said conveyor assembly (5) at the feeding station (6) so as to generate a layer (SP) of said powder material (CP) and comprises a plurality of feeding devices (9) , each feeding device (9) comprising, in turn, at least one container (10) , which is configured to contain a respective type of powder material (CP±) and has a respective exit port (11) , whose longitudinal extension is transverse (in particular, perpendicular) to the conveying direction (A) , a plurality of distribution elements (12) arranged one after the other along the exit port (11) so as to define a build-up plane (13) , which is inclined at an angle (a) relative to the horizontal and is designed to receive, resting on it, the powder material (CP±) coming out of said exit port (11) , and a plurality of actuators (14) , each configured to operate the respective distribution element (12) so as to cause said powder material (CP±) building up on said build-up plane (13) to fall; a detection device (19) arranged downstream of said powder material (CP) feeding assembly (8) along said conveying path (P) and configured to detect the height of the powder material fed onto the conveyor assembly (5) ; and a control unit (CU) to control at least the operation of said powder material (CP) feeding assembly (8) , said control unit (CU) being configured to implement the calibration method of claims 1 to 5 so that, in use, said feeding devices (9) of said powder material (CP) feeding assembly (8) all feed the same quantity of powder material (CP±) per surface unit.
EP23741126.9A 2022-06-23 2023-06-20 Calibration method of a powder material feeding assembly and manufacturing system of ceramic articles implementing said method Pending EP4543655A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
IT102022000013330A IT202200013330A1 (en) 2022-06-23 2022-06-23 METHOD OF CALIBRATION OF A POWDER MATERIAL FEEDING GROUP
PCT/IB2023/056367 WO2023248123A1 (en) 2022-06-23 2023-06-20 Calibration method of a powder material feeding assembly and manufacturing system of ceramic articles implementing said method

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IT1314623B1 (en) * 2000-04-21 2002-12-20 Carlo Antonio Camorani Decorative powder application method, for decorating ceramic tiles according to pattern controlled by computer, includes forming flow of liquid containing colored powdered material, and moving flow towards surface
EP1268148A2 (en) * 2000-03-30 2003-01-02 Algeri, Maris Object decoration
DE102005056260B4 (en) * 2005-11-25 2008-12-18 Prometal Rct Gmbh Method and device for the surface application of flowable material
ITRE20080030A1 (en) 2008-03-25 2009-09-26 Sacmi '' DEVICE AND METHOD FOR THE DELIVERY OF SOLID SOLID MATERIAL ''
ITRE20110061A1 (en) * 2011-08-05 2013-02-06 Ativa "METHOD OF CALIBRATION OF A DEVICE FOR THE DISTRIBUTION OF SOLID SOLID MATERIAL"
WO2020058891A1 (en) * 2018-09-20 2020-03-26 Scg Building Materials Co., Ltd. Apparatus and method for feeding granular material to a plant for the production of slabs or tiles

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