PL, PT. RO. RU, SC, SD. HE. SG, SK. SL, SY?.?, ??, ??, For two-lette.r codes and olher abbreviations, referred to the "Guid- TR.? G, TZ, UA .UG. UZ, VC. VN, YU,? ?, ZM, ZW, ARIPO anee Notes on Codes and Abbreviations "appearing to the lite begin- patent (GU GM, ??, LS, MW, ??, SD, SL SZ, TZ, UG, ning of eac regular issue of PCT Gazette, ZM, ZW), Eurasian patent (??. ??, ??, KG, ??. MD, RU, TJ, ??). E ropean patent (??, BE. BG. CU. CY. CZ. DE. DK, EE, ES. Fl, FR, GB, GR, HU, JE, IT. LU, MC, NL. PT, RO, SE , YES, SK. TR). OAPl patent (BF, BJ, CF, CG, CI, CM, GA, GN, GQ, GW, ML, MR, NE, SN, TD, TG) Published: international search repo
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METHOD AND PLANT FOR MAKING CERAMIC TILES
Field of the Invention This invention relates to a method and the relative plant for pressing precompacted tiles or slabs of ceramic material.
BACKGROUND OF THE INVENTION [0002] Ceramic tile formation methods are known which consist of preparing a powder mass, precompacting it to obtain a flat virgin piece of the consistent powders, decorating the virgin piece with at least a second layer of powders to form a surface decoration. and finally pressing the decorated virgin piece to obtain the formed tile. The virgin piece is created in general when pressing the mass of powder at a pressure of less than 100 kg / cm¿, so the virgin piece becomes consistent, but fragile. The fragility of the blank makes the operations included in the insertion of the same in the press cavity difficult. For this purpose, the insertion devices that mechanically transport the virgin piece above the lower die of the press are known. One of these devices is fully described in EP1256427 in the name of the same applicant, to which reference should be made for a more complete understanding. This insertion device operates mechanically on at least one of the sides of the precompacted blank to push it above the lower die of the press. It has been found that, particularly in the case of virgin parts of large dimensions, this mechanical thrust action causes damage at the contact points, which ruins the edge of the blank. The object of this invention is to overcome the disadvantages of the known technique with the system of a simple and rational solution, the cost of which is lower than systems of the known type.
Description of the Invention The invention achieves this object by virtue of the characteristics defined in the claims. Specifically, the method of the invention. consists of placing the virgin pieces, precompacted, flat, separated in a conveyor belt; driving the strip to put the blank to be pressed in a pressing station provided with at least one upper punch with which at least one die plate is associated to measure the position of the precompacted blank relative to the position of the punch. press die by a suitable measuring means; compare the measured values with the corresponding pre-established reference values; based on the result of the comparison, place the press die with the relative die plate exactly above the blank, and with the same orientation as the blank on the conveyor bar assumes; Press the precompacted virgin piece to obtain a tile. According to a preferred embodiment, when measuring the position of the pre-compacted virgin part relative to the press, the position of the precompacted virgin part relative to the press die is measured, or alternatively with respect to the associated die plate. with the die, or in relation to any rigid point with the press. When measuring the position of the blank, the distance between the edge of the blank and the corresponding sensors provided for the measurement is measured on two consecutive sides of the blank. The obtained data are compared, preferably, with pre-established values, the means that places the press die and the relative die plate above the precompacted virgin part that is operated based on the result of this comparison. According to one embodiment of the invention, at least two measurements are taken at two separate positions on each of the two consecutive sides of the blank, the values being compared with the corresponding pre-established reference values. The method of the invention is implemented by a plant for pressing virgin, flat, precompacted pieces, comprising a conveyor belt for transporting the virgin pieces in a pressing station provided with an upper die with which a die, mobile plate is associated , with the pressing station that associates a means to measure the position of the precompacted virgin piece in relation to the die, and a means to place the die exactly above the virgin piece and with the same orientation as the latter assumes the band transporter The measuring means are associated with the die plate or 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 die. the virgin flat piece that is going to be pressed. The measured data is transmitted to a processor that processes and / or compares it with sample data, preset, and then activates the operating medium to place the die exactly above the blank. A first embodiment of the invention comprises four position transducers associated in pairs with two consecutive sides of the die plate. In this way, for each side, two measurements are taken, their value being compared with reference values, pre-established, corresponding. 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 consecutive sides of the first side. In this case, the two transducers placed on the 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, the operating means comprises a series of cylinder-piston units acting on the sides of a moving plate associated with the upper transverse piece of the press, both the die and the die plate associated with the die which are rigid with the moving plate. In a first embodiment, the cylinder-piston units place the die in the direction transverse to the direction of advance of the virgin piece in the band, and they orient the die such that it assumes the same orientation as the virgin piece assumes in the band, while when operating the band itself it is possible to achieve the placement of the virgin piece in the direction of advance of the band. In a different embodiment of the invention, the operating means is capable of accurately positioning the die above the die plate also in the direction of web advance. In order to better clarify the method of the invention and the relative plant, a preferred embodiment thereof is hereinafter described by way of non-limiting example, and is illustrated in the accompanying Figures. Figure 1 is a side view, schematic, partially in section of a press plant according to the invention. Figure 2 is section II-II of Figure 1. Figure 3 shows the cross section III-III of Figure 5 in a first operative position. Figure 4 shows section III-III of Figure 1 in a second operative position. Figure 5 shows the same section as in Figure 2 in a different stage of operation. Figure 6 is section VI -VI of Figure 7 Figure 7 is section VII-VII of Figure 6. These Figures show the press plant 1 for implementing the method of the invention. The plant 1 comprises a conveyor belt 2 for transporting the virgin parts 3, flat, precompacted, separated, above a press 4. The virgin parts 3 are pre-compacted at a pressure between 10 and 100 kg / cm2.
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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 the pressing. The press 4 comprises a transverse, mobile, upper piece provided on the two opposite sides with two L-shaped profile bars 6 for supporting a plate 7. The upper punch 8 with a mobile, associated die plate 9 is rigid with the plate 7. In this regard, the die plate 9 can be moved in height relative to the upper transverse piece 5, which is 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 transverse piece 5 of the press 1 and move in a direction transverse to the direction of advance of the belt 2 under two hydraulic cylinder units 11 -piston associated with the profile bars 6 that support the plate 7. Each of the cylinder-piston units 11 comprises a cylinder 110 that is inserted into a coupling hole in the profile bar 6, and inside of which a moving piston 111 having a piston rod 112 slides, an end from which the cylinder 110 emerges to act against an outer side of the plate 7. The operation of the cylinder-piston units 11
it is controlled based on the position of the pre-compacted virgin part 3 relative to the upper die 8 or to the die die plate 9 associated with the die 8. The position of the pre-compacted virgin part 3 is measured by the means 12 measuring associated with the press. In the illustrated embodiment, the measuring means 12 is associated with the press die plate 9 to measure the distance of the closest edge of the precompacted blank. These means 12 comprise four devices 13, 14 and 15, 16 of which the devices 13 and 14 are placed on the side of the die plate 9, of the devices 15 and 16 on one of the consecutive sides. The devices 13 and 14 measure, with reference to the direction of advance of the band 2, the distance between each device and the front edge of the blank to be pressed, while the devices 15 and 16 measure the distance of each device from one of the lateral edges of the virgin piece. Therefore, two measurements are taken for each side, at separate points. The measured values are fed to a processor, not shown, which processes them and compares them with corresponding pre-established reference values. It should be noted that the processor calculates the average value of the measurements taken by devices 13 and 14 and compares this average value with a reference value.
Accordingly, band 2 is advanced until the average value calculated by the processor coincides with the reference value. When the band has stopped, the processor acquires the readings of the transducers 15 and 16, compares them with the corresponding reference value, and then controls the operation of the cylinder-piston units 11 based on the result of this comparison. The purpose of the cylinder-piston units 11 is to rotate the die so as to orient it in the same direction as the blank in the band 2, and to cause the die to move in a direction transverse to the direction of travel of the die. band 2 until it is placed exactly above the precompacted virgin part. Any required placement of the die in the direction of advance of the band is achieved instead by operating the band 2. The pressing then takes place at a pressure between 200 and 500 kg / cm2. The method of the invention is evident from the description of the plant. Specifically, it consists of placing the virgin pieces, separated in a conveyor belt; driving the strip to put that blank piece to be pressed below a pressing station provided with at least one upper die with which a die plate is associated; measure the position of the 10
precompacted virgin part relative to the position of the press die by a suitable measuring means; compare the measured values with corresponding pre-established reference values; based on the result of the comparison, place the press die exactly above the virgin part, and with the same orientation as the virgin piece assumes on the conveyor belt; Then press the precompacted virgin piece to obtain a tile. According to the method of the invention, at the end of the pressing, the die remains resting on the tile while the die plate is lifted to release its periphery. Then the die also rises and the conveyor belt transports the tile formed in this way to the outside of the pressing station. Figures 6 and 7 show a variant of the invention that differs from the previously prescribed embodiment, essentially with respect 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. The Figures show that the plate 7 is supported by a circumferential frame 20. This allows the die 8 to be positioned above the blank to be pressed both 11 in the direction transverse to the direction of advance of the strip 2 and in the same direction as the strip. In addition, by means of the cylinder-piston units, the die can be placed exactly in the same orientation as assumed by the blank in the band. Finally, in the illustrated embodiment of the invention, the means 12 for measuring the position of the blank comprises four devices 13, 14 and 15, 16 of which the devices 13 and 14 are placed on the same side of the plate 9 of die, and devices 15 and 16 on one of the consecutive sides. However, only three measuring devices can be used instead, of which two are provided to measure the distance of one side of the blank, and one is provided to measure the distance of one of these two sides of the blank. , consecutive to the precedent.