DE LAZZARI, Luigino (Via del Borgo, 63/1, Barago Di Maserada, I-31035, IT)
| CLAIMS 1. A method of manufacturing a tile production mold (2) of the type comprising at least one metal body (3, 4) which has at least one imprint (3a, 4a) on its surface, which copies the inverse shape of the front or rear face of the tile to be produced, and wherein such a imprint (3a, 4a) is lined with a covering jacket (5) made of vulcanized rubber or similar material, the method comprising the steps of i) placing a slab (5') made of rubber or other elastomeric polymer inside a seat (3b) specifically made in the surface of said metal body (3, 4) ; ii) closing the seat (3b) with a die-holder cover (6) provided with a die (1) which copies the shape of the front or rear face of the tile to be produced, so that the die (1) substantially abuts against the slab (5') made of rubber or other elastomeric polymer at the bottom of the seat (3b) ; and iii) subjecting the metal body (3, 4), the die- holder cover (6) arranged to close the seat (3b) and the die (1) to a heat vulcanization cycle during which the slab (5') made of rubber or other elastomeric polymer temporarily changes to the semisolid state, adapts to the shape of the die (1) so as to form the imprint (3a, 4a) , and undergoes a number of physical-chemical transformations which result in the vulcanization of the material in the new shape; the method being characterized in that said die (1) consists of a thermosetting resin-based slab (7) of given thickness, which was engraved with the aid of a laser beam so as to obtain a flat plate (1) made of hard, rigid material which copies the shape of the front or rear face of the tile to be produced. 2. A method of manufacturing a tile production mold according to claim 1, characterized in that the thermosetting resin-based slab (7) is a slab made of epoxy and/or phenolic based thermosetting resin. 3. A method of manufacturing a tile production mold according to claim 1 or 2 , characterized in that the thermosetting resin-based slab (7) is a slab made of thermosetting resin which includes inert powders and/or additives and/or reinforcing sheet materials. 4. A method of manufacturing a tile production mold according to claims 2 and 3, characterized in that the thermosetting resin-based slab (7) consists of a stack of kraft-paper sheets soaked in a phenolic and/or epoxy resin matrix. 5. A method of manufacturing a tile production mold according to claims 2 and 3, characterized in that the thermosetting resin-based slab (7) consists of one or more overlaid layers of glass fibres and/or carbon fibres and/or aramid fibres and/or cotton fibres and/or flax fibres and/or hemp fibres and/or fibres of another organic or inorganic material, conveniently overlaid and/or interwoven with one another and soaked in an epoxy and/or phenolic thermosetting resin matrix. 6. A method of manufacturing a tile production mold according to any one of the preceding claims, characterized in that said thermosetting resin-based slab (7) is from 5 to 50 millimeters thick. 7. A method of manufacturing a tile production mold according to any one of the preceding claims, characterized in that it also comprises the step of anchoring the die (1) to the die-holder cover (6) before the step of arranging the die-holder cover (6) to close the seat (3b) on the metal body (3, 4) . 8. A method of manufacturing a tile production mold according to Claim 7, characterized in that the step of anchoring the die (1) to the die-holder cover (6) comprises the step of placing/laying the die (1) to rest on a flat surface (6a) located on the die-holder cover (6) ; and then the step of intaking the air from the gap which is formed between the rear face (Ib) of the die (1) and the flat surface (6a) of said die-holder cover (6) . 9. A process of manufacturing a die (1) for making tile production molds (2) , wherein said die (1) consists of a flat plate (1) made of hard, rigid material which copies the shape of the front or rear face of the tile to be produced, and has a number of surface reliefs and/or veins and/or decorative relief pattern on the front face (Ia) thereof; the manufacturing process being characterized in that it comprises the steps of : - taking a thermosetting resin-based slab (7) of given thickness, and - engraving said thermosetting resin-based slab (7) with the aid of a laser beam, so as to obtain said flat plate (1) which copies the shape of the front or rear face of the tile to be produced, and which has a number of surface reliefs and/or veins and/or relief decorative pattern on the front face (Ia) thereof. 10. A process of manufacturing a die for making tile production molds according to claim 7, characterized in that the thermosetting resin-based slab (7) is a slab made of epoxy and/or phenolic based thermosetting resin. 11. A process of manufacturing a die for making tile production molds according to claim 7 or 8, characterized in that the thermosetting resin-based slab (7) is a slab made of thermosetting resin which comprises inert powders and/or additives and/or reinforcing sheet materials . 12. A process of manufacturing a die for making tile production molds according to claims 8 and 9, characterized in that the thermosetting resin-based slab (7) consists of a stack of kraft-paper sheets soaked in a phenolic and/or epoxy resin matrix. 13. A process of manufacturing a die for making tile production molds according to claims 8 and 9, characterized in that the thermosetting resin-based slab (7) consists of one or more overlaid layers of glass fibres and/or carbon fibres and/or aramid fibres and/or cotton fibres and/or flax fibres and/or hemp fibres and/or fibres of another organic or inorganic material, conveniently overlaid and/or interwoven with one another and soaked in an epoxy and/or phenolic thermosetting resin matrix. 14. A process of manufacturing a die for making tile production molds according to any one of the claims from 7 to 11, characterized in that said thermosetting resin-based slab (7) is from 5 to 50 millimeters thick. 15. A die (1) for making tile production molds (2), comprising a flat plate (1) made of hard, rigid material which copies the shape of the front or rear face of the tile to be produced, and has a number of surface reliefs and/or veins and/or decorative relief pattern on the front face (Ia) thereof; the die (1) being characterized in that the flat plate (1) made of hard, rigid material consists of a thermosetting resin-based slab (7) of given thickness, and in that the shape of the die (1) is directly obtained on the thermosetting resin-based slab (7) by laser engraving. 16. A die according to claim 13, characterized in that the thermosetting resin-based slab (7) is a slab made of epoxy and/or phenolic based thermosetting resin. 17. A die according to claim 13 or 14, characterized in that the thermosetting resin-based slab (7) is a slab made of thermosetting resin which includes inert powders and/or additives and/or reinforcing sheet materials. 18. A die according to claims 14 and 15, characterized in that the thermosetting resin-based slab (7) consists of a stack of kraft-paper sheets soaked in a phenolic and/or epoxy resin matrix. 19. A die according to claims 14 and 15, characterized in that the thermosetting resin-based slab (7) consists of one or more overlaid layers of glass fibres and/or carbon fibres and/or aramid fibres and/or cotton fibres and/or flax fibres and/or hemp fibres and/or fibres of another organic or inorganic material, conveniently overlaid and/or interwoven with one another and soaked in an epoxy and/or phenolic thermosetting resin matrix. |
TECHNICAL FIELD
The present invention relates to a die for construction of tile production molds and to the corresponding manufacturing and use processes.
More specifically, the present invention relates to a die for the construction of ceramic- or terracotta- tile production molds and to the corresponding manufacturing and use processes; use to which the following description refers purely by way of example without implying any loss of generality.
BACKGROUND ART
As known, some types of ceramic or terracotta tiles are made with the aid of molds which copy the inverse shape of the tile to be produced, by following a production process which envisages
to fill the cavity of the mold which copies the inverse shape of the tile to be produced, with a given amount of semisolid mixture (e.g. kaolin) with appropriate grain composition, granulometric distribution, and grain shape,- to compact the semisolid mixture inside the mold so as to form a raw tile;
to remove the raw tile from the mold; and to subjecting the raw tile to one or more consecutive, thermal cooking cycles during which the mixture solidifies, thus transforming into the ceramic or terracotta tile.
Instead the molds used in the production of ceramic or terracotta tiles are usually made up of two metal bodies, traditionally referred to as half-molds, which are intended to be coupled with each other, and are structured so as to form, in the middle of the coupling surface between the bodies, a closed cavity which is shaped so as to copy the inverse shape of the tile to be produced.
More specifically, the two metal bodies are usually structured to be arranged one above the other, and the upper metal body has an imprint in the middle of the coupling surface, which copies the inverse shape of the front or "visible" face of the tile; whereas the lower metal body has an imprint (again in the middle of the coupling surface) which copies the inverse shape of the rear face of the tile.
In order to avoid accumulation of powders and other waste which could compromise the quality and surface finishing of the front face of the tile, the imprint on the upper metal body is completely covered by a coating sheath or jacket made of rubber or other elastomeric polymer, which is directly made inside the upper metal body via a vulcanization process.
Considering that the final shape of the imprint should copy the inverse shape of the front or "visible" face of the tile, the imprint construction on the upper metal body basically envisages
i) to place a slab made of rubber or other elastomeric polymer inside a substantially rectangular seat which is specifically realized in the middle of the coupling surface of the upper metal body, with the addition of possible additives required for the material vulcanization;
ii) to close the seat with a cover which is centrally provided with a die or "template" which exactly copies the shape of the front or "visible" face of the tile to be produced, so that the die or "template" is brought into abutment against the slab made of rubber or other elastomeric polymer located at the bottom of the seat; and finally ϋi) to subject the upper metal body and its cover to a vulcanization thermal cycle during which the slab made of rubber or other elastomeric polymer temporarily changes to the semisolid state, adapts to the shape of the die so as to form the imprint, and undergoes a number of physical- chemical transformations which result in the vulcanization of the material in the new shape. Unfortunately, the coating sheath or jacket made of vulcanized rubber or other vulcanized elastomeric polymer deteriorates very quickly, and has to be completely replaced after the tile-mold has been used for a few thousand of ceramic- or terracotta- tile production cycles.
This rapid deterioration forces the manufacturers of this type of ceramic- or terracotta- tiles to cyclically repeat the vulcanization process of the coating sheath on the upper metal body of the tile production molds, parallelly with the production of the tiles .
The die or "template" which is used in the vulcanization process of the coating sheath or jacket currently consists of a flat plate made of aluminium or aluminium alloy (e.g. Ergal) with a thickness usually ranging from 5 to 50 millimeters, which copies the peripheral tile edge shape or size and has on the front face, i.e. on the face which corresponds to the front face of the tile, a number of reliefs and/or surface veins and/or embossed decorative patterns specific of the tile.
The die is usually made by material removing via a numeric control milling machine which engraves the metal plate so as to point by point remove the material in excess with respect to the desired profile.
Unfortunately, the time required for shaping the metal plate depends on the profile of the side edges and on the complexity of the reliefs and/or surface veins and/or embossed decorative pattern, and it quickly increases as the extension of the die or "template" increases, even greatly exceeding the 12 hours work on the numeric control milling machine for tiles with sides 30 centimeters long.
Obviously, the die production costs are closely related to the time employed by the numeric control milling machine to shape the metal plate, and may also reach values so high to make noncost-effective the production of tiles with particularly elaborate reliefs and/or surface veins and/or embossed decorative pattern.
In fact it happens really often that the amount of tiles to be produced with a particular number of reliefs and/or surface veins and/or relief decorative pattern is so small to not justify the production of a series of ad hoc dies, unless accepting an excessive increase in final tile production costs.
DISCLOSURE OF INVENTION
Aim of the present invention is therefore to realize a die for the construction of ceramic- or terracotta- tile production molds, which is faster and thus more cost-effective to be produced as compared to the current metal dies or "templates".
In compliance with the above aims, according to the present invention a method for the construction of a tile production mold is conceived as specified in Claim 1 and preferably, though not necessarily, in any one of the dependant claims.
According to the present invention, a process for the manufacturing of a die for the construction of tile production molds is also conceived as specified in Claim 9 and preferably, though not necessarily, in any one of the dependant claims.
Finally, in compliance with the above aims, according to the present invention there is provided a die for the construction of tile production molds, as defined in Claim 15 and preferably, though not necessarily, in any one of the dependant claims.
BRIEF DESCRIPTION OF THE DRAWINGS
A non-limiting embodiment of the present invention will now be described, by way of example, with reference to the accompanying drawings, in which:
- Figure 1 is an axonometric view of a die for the construction of tile production molds realized in accordance with the teachings of the present invention,-
- Figure 2 is a section view of a tile production mold realized in accordance with the teachings of the present invention,- Figure 3 schematically shows a step of the manufacturing process of the Figure 1 die;
- Figures 4 and 5 schematically show respective steps of the construction of the Figure 2 tile production mold; whereas
Figure 6 schematically shows, with parts in section and parts removed for clarity, a die-holder cover which is adapted to support the Figure 1 die during the mold vulcanization process shown in Figures 4 and 5.
BEST MODE FOR CARRYING OUT THE INVENTION
With reference to Figures 1 and 2, numeral 1 indicates as a whole a die or "template" specifically structured for being used in the construction of ceramic- or terracotta- or similar tile production molds
2 of the type consisting of two metal bodies or half- molds 3 and 4, which are intended to be coupled with each other, and are structured so as to form, approximately in the middle of the coupling surface between the bodies, at least one closed cavity which is shaped so as to copy the inverse shape of the tile to be produced .
More specifically, metal body 3 has, more or less in the middle of the coupling surface, at least one imprint 3a which copies the inverse shape of the front or "visible" face of the tile to be produced; whereas metal body 4 has, again more or less in the middle of the coupling surface, at least one imprint 4a which copies the inverse shape of the rear face of the tile to be produced. Metal bodies 3 and 4 are also structured so as to arrange, during the coupling step, the respective imprints 3a and 4a facing each other, so that the imprints form the closed cavity which is shaped so as to copy the inverse shape of the tile to be produced.
In particular, in the example shown, mold 2 is preferably, but not necessarily, structured so that the metal body 3 is placed above the metal body 4.
In order to avoid the accumulation of powders and other waste which could compromise the surface quality and finish of the front face of the tile to be produced, imprint 3a of the metal body 3 is completely covered by a covering sheath or jacket 5 made of vulcanized rubber or other vulcanized elastomeric polymer, which is directly made inside the metal body 3 through a vulcanization process which includes using die 1.
With reference to figure 1, die 1 essentially consists of a flat plate 1 made of hard, rigid material preferably, but not necessarily, rectangular or square in shape, which copies the shape of the front or "visible" face of the tile to be produced, and has a number of surface reliefs and/or veins and/or relief decorative pattern on its front face Ia (i.e. the face corresponding to the front face of the tile to be produced) . On the other hand, the rear face Ib of the plate is structured to be firmly fixed to a die-holder cover 6 (see figures 3 and 4) , normally employed in the vulcanization process of the covering sheath or jacket 5 on the metal body 3.
In particular, in the example shown, the surface reliefs and/or veins and/or relief decorative pattern occupy the whole surface of the front plate face Ia, but they could also occupy an area having a smaller extension than the whole surface of the front face Ia.
Unlike currently known dies or templates, flat plate 1 made of hard, rigid material consists of a monolithic slab 7 made of epoxy and/or phenolic based thermosetting resin, and preferably but not necessarily, of thickness from 5 to 50 millimeters, which may possibly include inert powders and/or additives and/or reinforcing sheet materials , such as for example fabrics or paper sheets; and the shape of the whole die 1 is directly obtained on slab 7 by laser engraving.
The thickness of slab 7 obviously depends on the shape of the die-holder cover 6 and on the overall thickness of the ceramic or terracotta tile to be produced.
More specifically, in the example shown, the thermosetting resin-based slab 7 preferably, but not necessarily, consists of a stack of kraft-paper sheets soaked in a phenolic and/or epoxy resin matrix so as to form a flat plate 1 of high rigidity and hardness, after the polymerization of the resin, which preferably but not necessarily has a nominal thickness from 5 to 30 millimeters .
Moreover, in a different embodiment, the thermosetting resin-based slab 7 may consist of one or more overlaid layers of glass fibres and/or carbon fibres and/or aramid fibres and/or cotton fibres and/or flax fibres and/or hemp fibres and/or fibres of another organic or inorganic material, conveniently overlaid and/or interwoven with one another and soaked in an epoxy and/or phenolic thermosetting resin matrix so as to form, after the resin polymerization, a flat plate 1 of high rigidity and hardness, which preferably but not necessarily, has a nominal thickness from 5 to 30 millimeters .
Die 1 is obtained from a flat, thermosetting resin- based slab 7 of appropriate size, by directly engraving the profile of the whole die 1 (preferably but not necessarily including the side edges) on one of the two faces of slab 7 with the aid of a laser beam which causes the localized ablation/vaporization/disintegration of the material which forms slab 7, to obtain the desired profile. With reference to figure 3, in the example shown, die or template 1 may be produced with the aid of a normal CNC laser engraving machine 11 which preferably, but not necessarily, comprises:
- a horizontal work surface 12 on which the thermosetting resin-based slab 7 is adapted to be laid;
- an engraving head 13 which is movable above the work surface 12 along two directrixes which are orthogonal to each other and parallel to the work surface 12, and which is able to generate and project a laser beam L towards the underneath work surface 12, which in turn is able to engrave the thermosetting resin-based slab 7 thus causing the localized vaporization of the material forming the surface thereof; and
- a control unit (not shown) which is able to move the engraving head 13 above the work surface 12 , and to adjust the intensity and focus of the laser beam L generated by the engraving head 13 , so as to directly engrave the profile of die 1 on the thermosetting resin- based slab 7 in a completely autonomous manner.
Laser engraving machine 11 is an equipment already widely known in other fields, and therefore will not be further described.
With reference to figures 4 and 5, the provision of imprint 3a on the metal body 3 when manufacturing mold 2 comprises the following steps:
i) anchoring the thermosetting resin-based die 1 to a die-holder cover 6 of convenient shape (see figure 4) ; ii) placing a slab 5' made of rubber or other elastomeric polymer into a seat 3b preferably, but not necessarily, rectangular or square in shape, specifically obtained more or less in the middle of the coupling surface of the metal body 3, with the addition of possible additives required for the material vulcanization (see figure 4);
iii) arranging the die-holder cover 6 to close the seat 3b on the metal body 3 so that the thermosetting resin-based die 1 is brought into abutment against the slab 5' made of rubber or other elastomeric polymer at the bottom of seat 3b (see figure 5) ; and finally
iv) subjecting the metal body 3 with the die-holder cover 6 arranged to close seat 3b and die 1 integral therewith, to a heat vulcanization cycle with pressures and temperatures depending on the material to be vulcanized, during which the slab 5' made of rubber or other elastomeric polymer temporarily changes to the semisolid state, adapts to the shape of die 1 so as to form the imprint 3a, and undergoes a number of physical- chemical transformations which result in the vulcanization of the material in the new shape (see figure 5) . At the end of the vulcanization process of the slab 5' made of rubber or other elastomeric polymer, the metal body 3 is provided with a imprint 3a which copies the inverse shape of the front face of the tile to be produced. Imprint 3a is directly made inside the metal body 3 , during the vulcanization process by means of which the covering sheath or jacket 5 made of vulcanized rubber or similar is obtained.
On the other hand, with regards to anchoring die 1 to the die-holder cover 6, die 1 (i.e. the thermosetting resin-based slab 7) may be firmly fixed to the die- holder cover 6 which is used during the vulcanization process of the slab 5' made of rubber or other elastomeric polymer, by means of anchoring members of mechanical type, such as through screws and/or clamps; or more conveniently, it may be firmly fixed to cover 6 in a pneumatic manner, by using a suction system which is structured so as to continuously intake the air from the gap formed between the rear face Ib of die 1, i.e. the thermosetting resin-based slab 7, and the surface of the die-holder cover 6.
In other words, the suction system is able to hold die 1, i.e. the thermosetting resin-based slab 7, in abutment against the die-holder cover 6 by keeping the rear face Ib of die 1 under vacuum (i.e. at a lower pressure than ambient pressure) . More specifically, with reference to figure 6, unlike the currently known die-holder covers, die-holder cover 6 on which the rear face Ib of die 1 is intended to rest on, is made of high-resistance metal material, and is provided with a flat surface 6a having a number of surface grooves 21 of small depth, which are conveniently distributed along the whole portion of the flat surface 6a intended to be covered by the rear face Ib of die 1.
In particular, in the example shown, the surface grooves 21 preferably, but not necessarily, have a substantially V- or U-shaped profile, and are preferably, but not necessarily, distributed along two directrixes which are orthogonal to each other, so as to reciprocally intersect to form a regular grid which substantially extends below the whole surface of the rear face Ib of die 1.
The die-holder cover 6 is also provided with at least one peripheral annular groove 22 which extends on the flat surface 6a so as to copy the shape of the periphery of die 1 , completely surrounds the set of surface grooves 21, and finally firmly accommodates an annular seal 23 made of elastically deformable material, which in turn is adapted to abut against the rear face Ib of die 1, so as to substantially air-tightly close the periphery of the rear face Ib of the die, thus forming a closed gap.
Finally, with reference to figure 6, die-holder cover 6 comprises a number of internal connecting conduits 24 extending into the body of the die-holder cover 6 so as to connect the surface grooves 21 to an external air-suction circuit 25 which, in turn, communicates with an electrically-activated vacuum pump 26 or the like.
Die-holder cover 6 may obviously form an integral part of the machine for vulcanizing imprint 3a in the metal body 3, or more conveniently, it may be a separate element which is structured so as to be fixed, in turn, to the machine for vulcanizing imprint 3a in the metal body 3 in a rigid and firm, but easily releasable manner.
If the "vacuum" die-locking system is used, anchoring die 1 to die-holder cover 6 includes activating the vacuum pump 26, before or after the thermosetting resin-based die 1 is placed/laid to rest on the flat surface 6a of die-holder cover 6, exactly above the annular seal 23. The pressure difference generated by the vacuum pump 26 kept between the front face Ia and the rear face Ib of the thermosetting resin- based die 1 forces die 1 to rest the rear face Ib on the flat surface 6a of the die-holder cover 6 thus pressing the annular seal 23. In other words, the step of anchoring die 1 to the die-holder cover 6 comprises the step of placing/laying die 1 to rest on the flat surface 6a of die-holder cover 6; and then the step of intaking the air from the gap formed between the rear face Ib of die 1 and the flat surface 6a of die-holder cover 6.
The small depth and convenient spacing of the surface grooves 21 on the flat surface 6a of die-holder cover 6 allow the rear face Ib of die 1 (i.e. the rear face of the thermosetting resin-based slab 7) to uniformly rest on the body of the die-holder cover 6, thus avoiding any possible deformations in the body of slab 7, which could compromise the correct conformation of imprint 3a during the vulcanization process.
The advantages resulting from the particular structure of die or template 1 are significant: the time required for directly laser engraving die 1 in the thermosetting resin-based slab 7 is much less than the time required for milling the aluminium or aluminium alloy plate. Therefore, the production costs of the ceramic or terracotta tile production mold 2 are significantly lower than those of a mold made in the traditional manner.
Due to the use of the thermosetting resin-based slab 7, die 1 further has a significantly lower weight per surface unit than that of a metal die having the same shape, with all the resulting advantages when die 1 should be anchored to the die-holder cover 6.
Moreover, using thermosetting resin-based dies or "templates" 1 permits to drastically reduce the number of die-holder covers to be stored, with all the resulting advantages.
Indeed, rather than firmly fixing each model of die or "template" to a respective die-holder cover (which solution is currently adopted by all tile manufacturers due to the significant weight of the dies or "templates" made of metal material) , the ceramic or terracotta tile manufacturer can now only have a number of die-holder covers 6 at his/her disposal which is equal to the number of sizes of tiles manufactured in the plant (e.g. 10x10 cm, 20x20 cm, 30x30 cm, etc.), by fixing the most suitable die or "template" 1 required to the die-holder cover 6 each time. Each die-holder cover 6 will be obviously structured to receive all the dies 1 having a given size (e.g. all the tiles having 30x30 cm size) .
Considering that the number of tile sizes, and therefore also of dies 1, is much lower than the tile models which may be generally produced and marketed by a manufacturer, using the thermosetting resin-based dies 1 greatly simplifies the management of the dies or "templates" during the production cycle and the logistics within the warehouse. Finally, experimental tests have revealed that making die or "template" 1 with epoxy and/or phenolic based thermosetting resins, permits to produce flat plates 1 made of hard, rigid material which have excellent structural rigidity, high temperature resistance, and heat conductivity to support the process of vulcanizing imprint 3a in the metal body 3, with no deterioration.
Finally, it is apparent that several modifications and variations may be made to die or "template" 1 for making tile production molds, without departing from the scope of the present invention.
For example, die 1 could consist of a flat plate 1 made of hard, rigid material, being circular, elliptical or polygonal in shape .
Moreover, in a different embodiment, die 1 could consist of a flat plate 1 made of hard, rigid material which copies the shape of the rear face of the tile to be produced, and be employed to provide a covering sheath or jacket made of vulcanized rubber or other vulcanized elastomeric polymer which should line the imprint 4a located on the metal body 4. The vulcanization process to produce the imprint 4a on the metal body 4 is the same as already described in the preceding pages for providing the imprint 3a on the metal body 3. Obviously, in this embodiment as well, the flat plate 1 made of hard, rigid material consists of a monolithic slab 7 made of epoxy and/or phenolic based thermosetting resin which may possibly include inert powders and/or additives and/or reinforcing sheet materials, such as for example fabrics or paper sheets,- and the shape of the whole die 1 is directly obtained on slab 7 by laser engraving.
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