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(11) | EP 1 547 742 A2 |
| (12) | EUROPEAN PATENT APPLICATION |
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| (54) | Mold for pressing ceramic tiles |
| (57) A mold for pressing ceramic tiles, intended to cope with the waste of time and higher
costs that occur when the mold is to be replaced in the press in order to produce
tiles having a format and/or contour that is different from the one for which it was
built, wherein each mold part is divided into two components: the framework (1, 16)
for coupling to the press and the active element (2), which can be interchanged in
the framework without disassembling the mold, which is provided with at least one
impression divided by means of an interchangeable diaphragm (9, 10) or an integrated
diaphragm (10a) or is otherwise surrounded also by strips (4, 30, 31); the mold is
used in the ceramic industry to produce tiles, particularly tiles having variable
formats and/or contours. |
[0001] The present invention relates to a mold for pressing ceramic tiles, particularly according to batches having variable shapes and/or contours, i.e., to a mechanical device that is provided with one or more impressions for molding ceramic tiles from a powdered earthy mass, which is divided into an upper mold part and a lower mold part, which are fixed so as to be mutually opposite within the working area of the press, wherein each one of said mold parts must be made suitable for molding tiles having a shape and/or contour that differ partially or completely from the ones provided initially; the parts of such a mold are also the subject of a patent application.
[0002] In the background art, if it is necessary to change the format and/or contour of the tiles produced by a given mold, said mold is replaced completely with another one; however, this is done with a high cost both due to the structure of the new mold, which is partly repetitive, and especially due to the waste of time entailed by the need to disassemble, replace and assemble, with a long interruption in production on the part of the press. There are also molds which are provided with one or more large or full-size impressions and are suitable, if necessary, to include vertically movable blades in order to divide the earth poured into each large impression into two or four portions, in order to obtain a corresponding number of tiles of smaller size, for example with at least two sides that are submultiples of the side of the large impression.
[0003] However, according to this method of dividing the format by cutting, since the thickness of the blade must necessarily be very low, drawbacks occur which limit considerably its durability, with the consequent need to replace it frequently after disassembling at least the corresponding mold part, and this operation is economically very onerous owing to the consequent forced interruption of production; moreover, the use of the blade during the pressing operation, due to the displacement of earth produced by the penetration of the blade therein, causes uneven compression in the cutting area with respect to the other regions, and such unevenness is well-known to be detrimental; moreover, it is difficult to shape the blending of the edge of the two or more tiles in the cutting area owing to the technological need to use a thin blade, which moreover has a sharp reduction in cross-section located in the section where the blade is attached to the tang; finally, when dividing the impression by cutting by means of a blade it does not seem possible or convenient to obtain a reduction in format to produce tiles that have a different contour, for example hexagonal or octagonal tiles or tiles having an otherwise undulated or generally curved or circular or mixed contour, due to the complexity of the configuration of the structure of the blades.
[0004] Moreover, using division by means of a blade prevents the use of the mold for tiles having a different thickness, since in the case of a thinner tile the blade would penetrate into the opposite mold part or plug, unless said blade were to be replaced with a shallower one, but with a corresponding cost increase mostly due to the halting of production, since it is necessary to disassemble the mold and take at least the affected mold part to the workshop.
[0005] Moreover, there is also the drawback, in case of division by cutting with a blade, of having to start from a mold that has impressions with maximum or otherwise large dimensions, and the method is not at all suitable for starting from a mold that has minimum- or medium-size impressions to reach a larger format, unless the blade is eliminated, with a consequent cost increase.
[0006] This background art is susceptible of numerous improvements as regards the possibility to eliminate or otherwise reduce significantly the drawbacks cited above.
[0007] The aim of the present invention is to solve the problem of finding a mold and/or mold parts that are adapted, in each instance, to form ceramic tiles that have a different format, even a multiple or submultiple of the initial one, or in any case a multiple or submultiple of one of the formats that coexist in said mold, and/or having contours that are different from the usual rectangular or square ones, such as a broken-line or otherwise curvilinear or mixed contour, advantageously without having to disassemble the mold completely, i.e., rapidly, cheaply and for any possible variation in format and/or contour, even without making a distinction in terms of mold type, be it of the so-called mirror plate type, or of the loose powder transfer type or of the so-called retracting type.
[0008] The above aim is achieved by adopting a mold that provides, directly at manufacture, the splitting of the body of the mold part into at least two components: one constituted by an active element, which has at least one cavity that constitutes the receptacle for the impression that is designed to receive the earth, or means that otherwise cooperate with at least that impression to form the tile, the other component being constituted by a framework or base, in which the active element, constituted in any manner, with impressions that are identical or otherwise different for any division and/or contour variation, can be inserted and fixed removably and interchangeably, even if the mold part remains fixed to the press; at least one of said active element cavities encloses an impression that is provided with at least one diaphragm that divides said impression into a plurality of impressions and/or elements for forming the tile contour with any shape: broken line, curvilinear or mixed.
[0010] The possibility to use the framework of each mold part in order to introduce and fix in each instance therein, detachably and interchangeably, the active element that is adapted to form tiles having certain formats and/or contours according to a program, replacing it when necessary with another element provided with different formats and/or contours in order to change the production program, and so forth.
[0011] Each mold part, originally fitted in the work area of the press, is provided with the suitable active element, intended either to produce large tile formats or to produce small tile formats; in any case, it is possible to provide, or otherwise add subsequently, one or more active elements for each mold part, said elements being manufactured in the workshop and available in the ceramic facility in order to replace them rapidly in the cavities of the frameworks of the mold parts when necessary, without having to disconnect and reassemble said frameworks with respect to the press.
[0012] Finally, the possibility to use the slider mold, already devised for semiautomatic replacement of plates, also for dividing the formats as well as to vary the contour of the tiles, and in order to be able to have impressions that are adapted to obtain tiles even having considerably different thicknesses.
[0014] Some ways of carrying out the invention are shown, merely by way of example, in the accompanying drawings, wherein:
Figure 1 is a bottom view of an upper mold part according to the invention, i.e., provided with a base structure or framework and with an active element, with a corresponding underlying vertical longitudinal cross-section; the active element, in this particular case, uses the base structure disclosed in EPA-04017862.6 by this same Applicant, which however relates only to the semiautomatic presetting of the replacement of the strips by means of an extractable slide locked by a transverse bar; said active element can be provided for example with cavities with interchangeable strips that delimit an impression for a large tile, but is provided mainly with at least one other impression obtained like the first one, but divided into two smaller impressions by means of an interchangeable diaphragm, and with a third impression that is divided for example in four by a cross-shaped diaphragm, which is also interchangeable;
Figure 2 is a top view of the corresponding lower mold part, with a corresponding vertical longitudinal section shown above;
Figure 3 is a bottom view of an active element that can be inserted in the upper mold part and is provided with two cavities that are separated by ribs, interchangeable contour strips being inserted in said cavities, but most of all is a view of the diaphragms, which are interchangeable in order to obtain, from the large impression, two, three or four smaller impressions: said strips and said diaphragms being able to rest on bottom ribs (shown in broken lines);
Figure 4 is a vertical and longitudinal sectional view taken along the line IV-IV of Figure 3;
Figures 5 and 6 are respectively vertical transverse sectional views, taken along the lines V-V and VI-VI of Figure 3, with the corresponding diaphragms shown in exploded view;
Figures 7, 8, 9, 10, respectively similar to Figures 3, 4, 5, 6, relate to the active element that is instead intended for the lower mold part and is likewise interchangeable therein;
Figure 11 is a transverse sectional view of the working area of the press occupied by the two mold parts according to the invention during closure, i.e., while the tiles are being formed;
Figure 12 is a partial enlarged-scale sectional view of Figure 11, illustrating the molding in the dividing region and the locking of the strips and diaphragms;
Figures 13a, 13b, 13c, 13d are partial views of particular couplings of the mold of Figures 11 and 12 respectively during the steps for loading earth, closing, transfer and pressing, and expelling, in the case indeed of the loose powder transfer mold;
Figure 14 is a bottom view of the upper mold part, with a corresponding vertical transverse sectional view, in the case in which an active element without strips and with integrated diaphragms rested on ribs is inserted in its framework, said element being advantageously usable for example in the case of an impression divided into curvilinear formats;
Figure 15 likewise is a plan view of the integral active element inserted in the lower mold part;
Figures 16 and 17 are similar to Figures 14 and 15 but with a division for polygonal formats, with strips and diaphragms, which are also monolithic with strips that are in any case interchangeable only after unscrewing the means for fixing to the bottom of the respective cavity;
Figures 18 and 19 are plan views of other embodiments of division of the large impressions, for example into four formats, two square ones and two rectangular ones, or into circular formats: the active element, in the case of Figure 18, being provided for example with interchangeable strips and diaphragms in the framework.
[0015] With reference to the figures, the reference numeral 1 designates a framework of the upper mold part, which is provided for example with an extractable slider or carriage 2, which in this case acts as an active element (both in the upper mold part and in the lower mold part), which encloses cavities 3 lined by hardened strips 4, which delimit peripherally the walls of tile impressions 5 and partially delimit smaller impressions 6 and 7; the reference numeral 8 designates a transverse bar for locking the active element 2; the reference numerals 9 and 10 designate diaphragms with a tapering right-angled cross-section, the last one being divided for example into a central cross 11 (Figure 3), and four segments 12 for dividing large impressions such as 5, or even an integral diaphragm 10a; the reference numeral 13 designates cup-shaped elements, in which the bottom acts as a flange for fixing not only the strips but also the diaphragms to the active element 2 by means of axial through screws 14 (Figure 4); the reference numeral 15 designates screws for fixing the active element 2 to the bottom of the structure 1 of the mold part; the reference numeral 16 designates the framework of the lower mold part, which is provided with diaphragms 17 and 18, which correspond to the one of the upper mold part but have a constant cross-section (i.e., a non-tapering cross-section), since they do not form the tile, as they merely contain the loose powder that is loaded and is designed to be transferred to the upper mold part in order to form the tile therein; the reference numerals 19 and 20 are exemplifying views of plugs or punches with suitable conventional functions; the reference numeral 21 (Figure 11) designates a base with peripheral columns of the lower mold part having the framework 16, for example with an expulsion block 22 that supports a magnetic shoe 23, to which the plugs 19 that form the marking of the tile are coupled, said plugs being arranged opposite the upper plugs, which are applied to an (upper) expulsion block 24; the reference numeral 25 designates an upper plate of the upper mold part provided with the framework 1, which is provided with hydraulic circuits, is fixed in an upper region and is connected to the structure that delimits the work area of the press; the reference numeral 26 designates the earth for forming a tile 27; the reference numerals 28 and 29 (Figures 14 and 15) designate upper and lower integral bodies that can be interchanged in the frameworks of the respective mold parts, such as for example the frameworks 1 and 16, in order to form for example curvilinear tiles, said frameworks being monolithic here with the diaphragms and without strips; the reference numerals 30 and 31 (Figures 16 and 17) designate coordinated series of strips and/or diaphragms that can be interchanged by unscrewing in order to cooperate in delimiting the impressions, for example in the formation of tiles having a polygonal contour: each contour being delimited by strips and/or strips connected by a diaphragm in the mutually adjacent impression regions; the reference numerals 32 and 33 (Figures 18 and 19) designate hollow supporting bodies on which, by means of the screws 15, the frameworks of the active elements 2 are screwed, in order to constitute interchangeable units in the cavities of the frameworks of the mold parts according to the invention: each one of said hollow bodies constituting a support for an active element that is detachably fixed therein.
[0016] In the practical embodiment, the materials, the dimensions, the constructive details may be different from the ones described, but technically equivalent thereto, without abandoning the scope of the appended claims.
[0017] The disclosures in Italian Patent Application No. MO2003A000357 from which this application claims priority are incorporated herein by reference.
[0018] Where technical features mentioned in any claim are followed by reference signs, those reference signs have been included for the sole purpose of increasing the intelligibility of the claims and accordingly, such reference signs do not have any limiting effect on the interpretation of each element identified by way of example by such reference signs.