Title of Invention

A METHOD AND PLANT FOR PROCESSING PRECOMPACTED FLAT CERAMIC BLANKS.

Abstract

Method for pressing precompacted flat blanks comprising the following operative stages: disposing the precompacted blanks spaced apart on a conveyor belt (2); driving said belt to bring that blank to be pressed below a pressing station (4) provided with at least one upper die (7, 8, 9) with which a die plate is associated; measuring the position of said precompacted blank relative to the position of the press die (7, 8, 9) by suitable measurement means (12); comparing the measured values with corresponding preset reference values; on the basis of the result of said comparison, positioning the press die exactly above said blank and with the same orientation as the blank assumes on the conveyor belt; pressing said precompacted blank to obtain a tile.

Full Text

-1- A METHOD AND PLANT FOR PRESSING PRECOMPACTED FLAT CERAMIC BLANKS TECHNICAL FIELD This invention relates to a method and plant for pressing precompacted flat ceramic blanks, and generally to a method and the relative plant for pressing precompacted tiles or slabs of ceramic material. BACKGROUND ART Ceramic tile forming methods are known consisting of preparing a powder mass, precompacted it to obtain a flat blank of consistent powders, decorating said blank with at least a second layer of powders to form a surface decoration, and finally pressing the decorated blank to obtain the formed tile. The flat blank is generally created by pressing the powder mass to a pressure less than 100 kg/cm2, by which the blank is made consistent but fragile. The fragility of the blank makes the operations involved in inserting it into the press cavity difficult. For this purpose insertion devices are known, which mechanically convey the blank to above the lower die of the press. One of these devices is fully described in Italian patent application RE2001A000047 in the name of the same applicant, to which reference should be made for a more complete understanding. Said insertion device operates mechanically at least on one of the sides of the precompacted blank to thrust it above the lower die of the press. It has been found that, in particular in the case of large-dimension blanks, this mechanical thrust action causes damage at the points of contact which ruins the edge of the blank. The object of this invention is to overcome the drawbacks of the known art within the framework of a simple and rational solution, the cost of which is lower than the systems of known type. -2- DISCLOSURE OF THE INVENTION Accordingly, the present invention provides a method for pressing precompacted flat ceramic blanks, said method comprising the following operative stages: (a) disposing the precompacted blanks spaced apart on a conveyor belt; (b) driving said belt to bring that blank to be pressed below a pressing station provided with at least one upper die with which a die plate is associated; (c) measuring the position of said precompacted blank relative to the position of the press die by suitable measurement means; (d) comparing the measured values with corresponding preset reference values; (e) on the basis of the result of said comparison, positioning the press die exactly above said blank and with the same orientation as the blank assumes on the conveyor belt; (f) pressing said precompacted blank to obtain a tile. Preferably, said measurement means are supported by the press die. Preferably, the measurement operation consists of measuring the distance between the measuring means and two spaced apart position of at least one edge of the blank. Preferably, the measurement operation consists of measuring the distance between the measuring means and one position of one edge of the blank and the distance between the measuring means and one position of the edge of the blank adjacent thereto. Preferably, said measurement operation consists of measuring the distance between the measuring means and two spaced apart positions of one edge of the blank and the distance between the measuring means and two spaced apart positions of the edge of the blank adjacent thereto. Preferably, after pressing, the die is left resting on the formed tile whereas the die plate is raised to free its perimeter. Preferably, after raising the die plate the die is also raised and the conveyor belt driven to remove the formed tile from the pressing station. Preferably, said tile is precompacted to a pressure between 10 and 100 kg/cm2. Preferably, said pressing of the precompacted tile takes place at a pressure between 200 and 500 kg/cm2. -2A- The present invention also provides a plant for pressing precompacted flat blanks, comprising a conveyor belt for conveying said blanks to below a pressing station provided with an upper die with which a movable die plate is associated, characterized by comprising means for measuring the position of said precompacted blank relative to said die, means for comparing the data determined by said measurement means with reference values, and means for positioning said die exactly above said blank and with the same orientation as this latter assumes on the conveyor belt. Preferably, the plant for pressing precompacted flat blanks comprises a conveyor belt for conveying said blanks to below a pressing station provided with an upper die with which a movable die plate is associated, characterized by comprising means for measuring the position of said precompacted blank relative to said die, means for comparing the data determined by said measurement means with reference values, and means for positioning said die exactly above said blank and with the same orientation as this latter assumes on the conveyor belt. Preferably, said measurement means are associated with said die plate. Preferably, said measurement means are at least one pair of position sensors or transducers associated with at least one side of the die plate. Preferably, said measurement means are at least two pairs of position sensors or transducers associated with two consecutive sides of said die plate. Preferably, said means for comparing the determined data with reference values comprise a processor. Preferably, said die and said die plate are supported by a plate associated with the upper crosspiece of the press. Preferably, said plate can rotate and translate relative to said upper crosspiece. Preferably, said plate is associated with said upper crosspiece by means of two profile bars which support the perimetral edges of two opposing sides of the plate. Preferably, said plate is associated with said crosspiece by means of an L-shaped perimetral frame. Preferably, said operating means act on the edges of said plate. Preferably, said operating means comprise at least two pairs of cylinder-piston units arranged to act on two opposing sides of said plate. Preferably, said operating means comprise eight cylinder-piston units arranged to act in pairs on each side of the plate. Preferably, said operating means also comprise said conveyor belt. -2B- Specifically, the method of the invention consists of disposing the flat precompacted blanks spaced apart on a conveyor belt; driving said belt to bring that blank to be pressed into a pressing station provided with at least one upper die with which at least one die plate is associated; measuring the position of said precompacted blank relative to the position of the press die by suitable measurement means; comparing the measured values with corresponding preset reference values; on the basis of the result of said comparison positioning the press die with the relative die plate exactly above said blank, and with the same orientation as the blank assumes on the conveyor belt; pressing said precompacted blank to obtain a tile. According to a preferred embodiment, in measuring the position of the precompacted blank relative to said press, the position of the precompacted blank is measured relative to the press die, or alternatively relative to the die plate associated with the die, or relative to any point rigid with the press. 3 In measuring the position of the blank, the distance between the edge of the blank and the corresponding sensors provided for said measurement is measured on two consecutive sides of the blank. The data obtained are preferably compared with preset values, the means which position the press die and the relative die plate above the precompacted blank being operated on the basis of the result of this comparison. According to one embodiment of the invention, at least two measurements are taken in two spaced-apart positions on each of the two consecutive sides of the blank, the values being compared with corresponding preset reference values. The method of the invention is implemented by a plant for pressing precompacted flat blanks, comprising a conveyor belt for conveying said blanks into a pressing station provided with an upper die with which a movable die plate is associated, with said pressing station there being associated means for measuring the position of said precompacted blank relative to said die, and means for positioning said die exactly above said blank and with the same orientation as this latter assumes on the conveyor belt. The measurement means are associated with the die plate or with the press die, and comprise at least two position transducers associated with two consecutive sides of the die, each of which measures the distance between the transducer and the corresponding edge of the flat blank to be pressed. The measured data are transmitted to a processor which processes them and/or compares them with preset sample data, and then activates said operating means to position the die exactly above the blank. 4 A first embodiment of the invention comprises four position transducers associated in pairs with two consecutive sides of the die plate. In this manner, for each side two measurements are taken, their value being compared with corresponding preset reference values. In a different embodiment of the invention, two position transducers are associated with a first side of the die plate and a third transducer with one of the sides consecutive to said first side. In this case the two transducers positioned on said first side of the die plate measure the distance of a first side of the blank, and the third measures the distance of one of the consecutive sides. According to the invention said operating means comprise a series of cylinder-piston units which act on the sides of a movable plate associated with the upper crosspiece of the press, both the die and the die plate associated with the die being rigid with said movable plate. In a first embodiment the cylinder-piston units position the die in the direction transverse to the direction of advancement of the blank on the belt, and orientate the die such that it assumes the same orientation as the blank assumes on the belt, whereas the positioning of the blank in the direction of belt advancement can be accomplished by operating the belt itself. In a different embodiment of the invention the operating means are able to position the die exactly above the die plate also in the belt advancement direction. In order to better clarify the method of the invention and the relative plant, a preferred embodiment thereof is described hereinafter by way of non-limiting example and illustrated in the accompanying drawings. 5 Figure 1 is a partly sectional schematic side view of the pressing plant according to the invention. Figure 2 is the section II-II of Figure 1. Figure 3 shows the section Ill-Ill of Figure 1 in a first operative position. Figure 4 shows the section Ill-Ill of Figure 1 in a second operative position. Figure 5 shows the same section as Figure 2 in a different stage of operation. Figure 6 is the section VI-VI of Figure 7. Figure 7 is the section VII-VII of Figure 6. Said figures show the pressing plant 1 for implementing the method of the invention. The plant 1 comprises a conveyor belt 2 for conveying the spaced-apart precompacted flat blanks 3 to below a press 4. The blanks 3 are precompacted to a pressure between 10 and 100 kg/cm2. As can be seen from Figure 1, below the conveyor belt 2, in correspondence with the press 4, a plate 100 is present to act as an "anvil" during pressing. The press 4 comprises an upper movable crosspiece 5 provided on two opposing sides with two L-shaped profile bars 6 for supporting a plate 7. The upper die 8 with an associated movable die plate 9 are rigid with the plate 7. In this respect, the die plate 9 can translate in height relative to the upper crosspiece 5, it being secured to the plate 7 by four cylinder-piston units 10. With reference to Figures 3 and 4 the plate 7 can rotate relative to the upper crosspiece 5 of the press 1 and translate in a direction transverse to 6 the direction of advancement of the belt 2 by virtue of two hydraulic cylinder-piston units 11 associated with the profile bars 6 which support the plate 7. Each of the cylinder-piston units 11 comprises a cylinder 110 which is inserted into a matching hole in the profile bar 6, and in the interior of which there slides a movable piston 111 carrying a piston rod 112, one end of which emerges from the cylinder 110 to act against an outer side of the plate 7. The operation of said cylinder-piston units 11 is controlled on the basis of the position of the precompacted blank 3 relative to the upper die 8 or to the press die plate 9 associated with the die 8. The position of the precompacted blank 3 is measured by measurement means 12 associated with the press. In the illustrated embodiment, the measurement means 12 are associated with the press die plate 9 to measure the distance of the closest edge of the precompacted blank. Said means 12 comprise four devices 13, 14 and 15, 16, of which the devices 13 and 14 are disposed on the said side of the die plate 9, and the devices 15 and 16 on one of the consecutive sides. The devices 13 and 14 measure, with reference to the advancement direction of the belt 2, the distance between each device and the front edge of the blank to be pressed, whereas the devices 15 and 16 measure the distance of each device from one of the side edges of the blank. Two measurements are therefore taken for each side, at points spaced apart. The measured values are fed to a processor, not shown, which processes them and compares them with corresponding preset reference values. 7 It should be noted that the processor calculates the average value of the measurements taken by the devices 13 and 14 and compares this average value with a reference value. Consequently the belt 2 is made to advance until the average value calculated by the processor coincides with the reference value. When the belt has stopped, the processor acquires the readings from the transducers 15 and 16, compares them with the corresponding reference value, and then controls the operation of the cylinder-piston units 11 on the basis of the result of this comparison. The purpose of the cylinder-piston units 11 is to rotate the die in order to orientate it in the same direction as the blank on the belt 2, and to cause the die to translate in a direction transverse to the advancement direction of the belt 2 until it is brought exactly above the precompacted blank. Any required positioning of the die in the belt advancement direction is instead achieved by operating the belt 2. Pressing then takes place at a pressure between 200 and 500 kg/cm2. The method of the invention is apparent from the plant description. Specifically, it consists of disposing the precompacted blanks spaced apart on a conveyor belt; driving said belt to bring that blank to be pressed to below a pressing station provided with at least one upper die with which a die plate is associated; measuring the position of said precompacted blank relative to the position of the press die by suitable measurement means; comparing the measured values with corresponding preset reference values; on the basis of the result of said comparison, positioning the press die exactly above said blank, and with the same orientation as 8 the blank assumes on the conveyor belt; then pressing said precompacted blank to obtain a tile. According to the method of the invention, on termination of pressing the die remains resting on the tile while the die plate is raised to free its periphery. The die is then also raised and the conveyor belt conveys the thus formed tile to the outside of the pressing station. Figures 6 and 7 show a variant of the invention which differs from the aforedescribed embodiment essentially with regard to the means for positioning the die and its associated die plate. These figures use the same reference numerals for those components identical to and already described in the first embodiment of the invention. Said figures show that the plate 7 is supported by an L-shaped perimetral frame 20 with which the positioning means for said plate are associated. Specifically, said means comprise eight hydraulic cylinder-piston units 21 associated in pairs with each side of the perimetral frame 20. This enables the die 8 to be positioned above the blank to be pressed both in the direction transverse to the advancement direction of the belt 2 and in the same direction as the belt. In addition, by means of said cylinder-piston units the die can be positioned exactly with the same orientation as the blank assumes on the belt. Finally, in the illustrated embodiment of the invention the means 12 for measuring the position of the blank comprise four devices 13, 14 and 15, 16, of which the devices 13 and 14 are disposed on the same side of the die plate 9, and the devices 15 and 16 on one of the consecutive sides. However just three measurement devices could instead be used, of which two are provided to measure the distance of one side of the blank, and 9 one is provided to measure the distance of one of those two sides of the blank consecutive to the preceding. -10-WE CLAIM : 1. A method for pressing precompacted flat ceramic blanks, said method comprising the following operative stages: a) disposing the precompacted blanks (3) spaced apart on a conveyor belt (2); b) driving said belt (2) to bring that blank (3) to be pressed below a pressing station (4) provided with at least one upper die (8) with which a die plate (9) is associated; c) measuring the position of said precompacted blank (3) relative to the position of the press die (8) by suitable measurement means (12); d) comparing the measured values with corresponding preset reference values; e) on the basis of the result of said comparison, positioning the press die (8) exactly above said blank (3) and with the same orientation as the blank (3) assumes on the conveyor belt; f) pressing said precompacted blank (3) to obtain a tile. 2. A method as claimed in claim 1, wherein said measurement means (12) are supported by the press die (8). 3. A method as claimed in claim 1, wherein said measurement operation consist of measuring the distance between the measuring means (12) and two spaced apart position of at least one edge of the blank (3). 4. A method as claimed in claim 1, wherein said measurement operation consist of measuring the distance between the measuring means (12) and one position of one edge of the blank (3) and the distance between the measuring means and one position of the edge of the blank (3) adjacent thereto. 5. A method as claimed in claim 1, wherein said measurement operation consist of measuring the distance between the measuring means (12) and two spaced apart positions of one edge of the blank (3) and the distance between the measuring means (12) and two spaced apart positions of the edge of the blank (3) adjacent thereto. -11- 6. A method as claimed in claim 1, wherein after pressing, the die is left resting on the formed tile whereas the die plate (9) is raised to free its perimeter. 7. A method as claimed in claim 6, wherein after raising the die plate (9) the die is also raised and the conveyor belt (2) driven to remove the formed tile from the pressing station. 8. A method as claimed in claim 1, wherein said tile is precompacted to a pressure preferably between 10 and 100 kg/cm2. 9. A method as claimed in claim 1, wherein said pressing of the precompacted tile takes place at a pressure preferably between 200 and 500 kg/cm2. 10. A plant for pressing precompacted flat blanks, comprising a conveyor belt (2) for conveying said blanks (3) to below a pressing station (4) provided with an upper die (8) with which a movable die plate (9) is associated, characterized by comprising means for measuring the position of said precompacted blank (3) relative to said die, means for comparing the data determined by said measurement means (12) with reference values, and means (11) for positioning said die (8) exactly above said blank (3) and with the same orientation as this latter assumes on the conveyor belt (2). 11. A plant as claimed in claim 10, wherein said measurement means are associated with said die plate (9). 12. A plant as claimed in claim 11, wherein said measurement means (12) are at least one pair of position sensors or transducers (13, 14, 15, 16) associated with at least one side of the die plate. 13. A plant as claimed in claim 11, wherein said measurement means (12) are at least two pairs of position sensors or transducers (13, 14, 15, 16) associated with two consecutive sides of said die plate. -12- 14. A plant as claimed in claim 10, wherein said means for comparing the determined data with reference values comprise a processor. 15. A plant as claimed in claim 10, wherein said die (8) and said die plate (9) are supported by a plate (7) associated with the upper crosspiece (5) of the press (4). 16. A plant as claimed in claim 15, wherein said plate (7) can rotate and translate relative to said upper crosspiece (5), 17. A plant as claimed in claim 15, wherein said plate is associated with said upper crosspiece (5) by means of two profile bars (6) which support the perimetral edges of two opposing sides of the plate (7). 18. A plant as claimed in claim 15, wherein said plate (7) is associated with said crosspiece by means of an L-shaped perimetral frame. 19. A plant as claimed in claim 16, wherein said operating means act on the edges of said plate. 20. A plant as claimed in claim 17, wherein said operating means comprise at least two pairs of cylinder-piston units (11) arranged to act on two opposing sides of said plate (7). 21. A plant as claimed in claim 17, wherein said operating means comprise eight cylinder-piston units (11) arranged to act in pairs on each side of the plate (7). 22. A plant as claimed in claim 20, wherein said operating means also comprise said conveyor belt. Method for pressing precompacted flat blanks comprising the following operative stages: disposing the precompacted blanks spaced apart on a conveyor belt (2); driving said belt to bring that blank to be pressed below a pressing station (4) provided with at least one upper die (7, 8, 9) with which a die plate is associated; measuring the position of said precompacted blank relative to the position of the press die (7, 8, 9) by suitable measurement means (12); comparing the measured values with corresponding preset reference values; on the basis of the result of said comparison, positioning the press die exactly above said blank and with the same orientation as the blank assumes on the conveyor belt; pressing said precompacted blank to obtain a tile.

Documents:

00354-kolnp-2005-abstract.pdf

00354-kolnp-2005-assignment.pdf

00354-kolnp-2005-claims.pdf

00354-kolnp-2005-correspondence.pdf

00354-kolnp-2005-description(complete).pdf

00354-kolnp-2005-drawings.pdf

00354-kolnp-2005-form-1.pdf

00354-kolnp-2005-form-18.pdf

00354-kolnp-2005-form-3.pdf

00354-kolnp-2005-form-5.pdf

00354-kolnp-2005-g.p.a.pdf

00354-kolnp-2005-letters patent.pdf

00354-kolnp-2005-priority document.pdf

00354-kolnp-2005-reply f.e.r.pdf

354-kolnp-2005-granted-abstract.pdf

354-kolnp-2005-granted-assignment.pdf

354-kolnp-2005-granted-claims.pdf

354-kolnp-2005-granted-correspondence.pdf

354-kolnp-2005-granted-description (complete).pdf

354-kolnp-2005-granted-drawings.pdf

354-kolnp-2005-granted-form 1.pdf

354-kolnp-2005-granted-form 3.pdf

354-kolnp-2005-granted-form 5.pdf

354-kolnp-2005-granted-gpa.pdf

354-kolnp-2005-granted-letter patent.pdf

354-kolnp-2005-granted-reply to examination report.pdf

354-kolnp-2005-granted-specification.pdf

354-kolnp-2005-granted-translated copy of priority document.pdf