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(11) | EP 1 086 915 A2 |
| (12) | EUROPEAN PATENT APPLICATION |
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| (54) | Method for obtaining a continuous wooden sheet in roll form |
| (57) A method for obtaining a continuous wooden sheet (50) in roll form (9), comprising
the preparation of semifinished sheets (1) starting from individual sheets of veneer
in flitches by arranging them side by side and splicing them laterally with glue.
The method further comprises a step for sequentially positioning, along a longitudinal
axis, multiple semifinished sheets on a backing (2) which is pre-glued with thermosetting
adhesive and is unrolled continuously, with arrangement, on the splice, of a first
tear-preventing insert, and with insertion of a second locator insert for optical
reading. Hot and cold pressing of the sequentially arranged sheets is then performed,
followed by a step for rolling, unrolling and sizing the sheet thus obtained and for
re-rolling and trimming the resulting roll. |
[0001] The present invention relates to a method for obtaining a continuous wooden sheet in roll form.
[0002] Currently, the known art in the field of industrial processing of wood allows to produce a spliced veneer in roll form with roll widths up to approximately 350 mm.
[0003] This size is dictated by the difficulty in keeping straight the veneer, which is appropriately prepared beforehand in terms of width by arranging side by side various sub-sheets of veneer which are spliced laterally.
[0004] Wood is in fact a natural product which is subject to settling and therefore to "living" tensioning behaviors which cannot be predicted but can only be controlled and managed up to the size, universally agreed by those skilled in the art, of approximately 320-350 mm.
[0005] There is also the difficulty of producing a specific device suitable to perform butt-splicing, coupling with various kinds of support, sizing and finishing of the produced roll.
[0006] The aim of the present invention is to solve the above-mentioned problems, eliminating the drawbacks of the known art, by providing a method, which allows to manufacture a roll of veneer, selected by the customer, which has a much larger width, even approximately 1300 mm, and a considerable length, for example up to 500 m.
[0007] Within the scope of this aim, an object of the present invention is to devise a method which provides a product having good mechanical characteristics, in order to withstand the deformations produced for example in so-called postforming (veneering of a part after it has been shaped).
[0008] Another object is to devise a method which provides a product having a high quality level, with high-level aesthetic characteristics, and suitable to be used for continuous veneering of flat and postformed elements.
[0009] This aim cannot be achieved by the known art for obtaining a roll from a non-rolled wood veneer, since although this conventional technology allows to obtain a product which has no butt splices and significant natural tensions, the achievable result is highly dependent on the quality and state of the log used, and each roll differs from the preceding one in this aspect and does not allow an aesthetic configuration which is continuous over time, qualitatively appreciable, and usable for furniture lamination.
[0010] Another object is to provide a product which is structurally simple and has low manufacturing costs.
[0011] These and other objects which will become better apparent hereinafter are achieved by a method for obtaining a continuous wood sheet in roll form according to the present invention, comprising a first step for preparing individual veneer sheets in flitches (strips cut from a same log), a second step for composing sheets of said veneer by arranging them side by side and splicing them laterally by way of glue so as to obtain a single semifinished sheet, and a third step for trimming and squaring said single semifinished sheet, characterized in that it comprises:
a fourth step for sequentially positioning, along a longitudinal axis, a plurality of single semifinished sheets on a backing which is pre-glued with thermosetting adhesive and is unrolled continuously, with arrangement, on the splice, of a first tear-preventing insert, with insertion of a second locator insert for optical reading;
a fifth step of hot and cold pressing of said sequentially arranged sheets;
a sixth step for rolling, unrolling and sizing said sheet thus obtained and for re-rolling and trimming the resulting roll.
[0012] Further characteristics and advantages of the invention will become better apparent from the following detailed description of a particular embodiment thereof, illustrated only by way of non-limitative example in the accompanying drawings, wherein:
Figure 1 is a schematic view of a production line for obtaining rolls of semifinished product;
Figure 2 is a schematic view of a detail of the splicing of two sheets of semifinished product in a production line for obtaining rolls of semifinished product;
Figure 3 is a schematic view of a production line for sizing the rolls of semifinished product from the production line such as that of Figure 1;
Figure 4 is a schematic view of a second embodiment of the production line for obtaining rolls of semifinished product;
Figure 5 is a schematic view of a detail illustrating in the second embodiment the method for splicing two sheets of semifinished product in a production line for obtaining rolls of semifinished product;
Figure 6 is a schematic view of a production line for sizing the rolls of semifinished product from the production line such as that of Figure 4;
Figure 7 is a schematic view of a detail illustrating in a third embodiment according to the invention, the method for splicing two sheets of semifinished product in a production line for obtaining rolls of veneer;
Figure 8 is a schematic view of the production line, in the third embodiment, for obtaining rolls of veneer;
Figure 9 is a schematic view of a production line for splicing a film of veneer to a backing film and for sizing the rolls of semifinished product related to the splicing method and production line of Figures 7 and 8;
Figure 10 is a schematic view of a fourth embodiment of the production line for obtaining rolls of semifinished product;
Figure 11 is a schematic view of a detail illustrating, in the fourth embodiment according to the invention, the method for splicing two sheets of semifinished product in a production line for obtaining rolls of semifinished product;
Figure 12 is a schematic view of a production line for sizing the rolls of semifinished product from a production line such as that of Figure 10.
[0013] With reference to the above cited figures, 1 designates a semifinished product, obtained from sheets of veneer which have already passed a quality test and checks as regards dimensions and characteristics.
[0014] A first step of the method consists in producing said semifinished sheets 1 starting from single sheets of veneer.
[0015] Said sheets are initially subjected to stretching in a press and to trimming in order to bring them to the sought dimensions.
[0016] Then a second step is performed for laterally splicing the sheets of veneer by using a glue-based system instead of the conventional and more widely used thread system, since this better ensures the coupling between two parts and over time prevents the surfacing of the splicing thread.
[0017] As a third step of the preparation of the semifinished products, squaring is performed, obtaining a semifinished sheet which has a preset length according to the component and type of veneer used and is up to 1300 mm wide.
[0018] With reference to Figure 1, the method for laterally splicing said semifinished sheets 1 entails a fourth step, in which a backing film 2 is unrolled and placed on a conveyor table, designated by the reference numeral 3, and a plurality of semifinished sheets are positioned so as to be perfectly aligned in a longitudinal direction and above said backing film 2, which is appropriately impregnated with thermosetting adhesive.
[0019] In this fourth step, a first splicing insert 4 is also applied beforehand between the contiguous ends and below two contiguous semifinished sheets 1a and 1b; said insert is grid-like, bears thermosetting adhesive and acts as first tear-preventing insert.
[0020] Below said first splicing insert 4 there is provided a second insert made of non-woven fabric, designated by the reference numeral 5, which is aluminum-metallized, bears thermosetting adhesive and is responsive to optical reading for synchronized operation of the system.
[0021] The fifth step of the method consists in the advancement of the component under a hot press, designated by the reference numeral 6, for guiding said semifinished sheet 1 to said backing film 2, with variable pressing according to the adhesive used, and subsequent passage in a cold press 7 in order to stabilize the resulting continuous sheet 50.
[0022] The sixth step entails the use of a first roll-forming and trimming machine, designated by the reference numeral 8, which receives the continuous sheet 50 from said cold press 7, which accelerates the curing of the adhesive and stabilizes the wood veneer, and provides in output a trimmed raw roll 9.
[0023] Finally, said trimmed raw roll 9 is inserted in a coarse sander, designated by the reference numeral 10, for sizing the component, in order to obtain uniform thickness over the entire surface.
[0024] Then the product is sent to a second roll-forming and trimming machine 11 so as to obtain in output a roll of semifinished product, designated by the reference numeral 12, which is ready for the final lacquering process, which occurs according to conventional methods.
[0025] It has thus been observed that the present invention has achieved the intended aim and objects, a method having been provided for obtaining rolls of spliced veneer in roll form up to a width of approximately 1300 mm and a length of approximately 500 meters.
[0026] The invention is of course susceptible of numerous modifications and variations, all of which are within the scope of the same inventive concept.
[0027] In particular, in a second embodiment the following method is applied, as illustrated in Figures 4, 5 and 6.
[0028] Once the semifinished sheets 101 have been obtained according to the above described method, a corresponding number of backing sheets, designated by the reference numeral 113 in Figure 4, already pre-glued and squared, in the same size as said semifinished sheets 101, is prepared.
[0029] Said semifinished sheets 101 are exactly superimposed on said backing sheets 113 and are placed on a conveyor table, designated by the reference numeral 103, which first conveys them into a hot press 106 for mutually gluing said two sheets, then conveys them to a cold press 107 for stabilizing the component, obtaining in output semifinished sheets of veneer thus obtained, designated by the reference numeral 114.
[0030] Said semifinished sheets of veneer 114 are then introduced, by means of said conveyor table 103, into a third gluing press, designated by the reference numeral 115, which butt-splices the semifinished sheets of veneer 114, in the manner shown in Figure 5: two pre-glued metal laminas 116 are placed before pressing above and below the ends of two contiguous butt-spliced sheets.
[0031] The continuous component then enters a first roll-forming and trimming machine 108, from which trimmed raw rolls, designated by the reference numeral 109, are extracted and are then used in a coarse sander 110 which unrolls the resulting film, sizes its thickness and sends it to a first roll-forming and trimming machine 111, which provides in output a roll of semifinished product, designated by the reference numeral 112.
[0032] In a third embodiment the production process, illustrated in Figures 7, 8 and 9, relates to the use of semifinished sheets 201 which have a reinforced saw-tooth splice to join sheets, with a specific second insert 205 made of non-woven fabric and metallized with aluminum with thermosetting adhesive, for optical reading in order to allow subsequent sequential processes with a preset spacing.
[0033] A first grid-like splicing insert 204, also provided with thermosetting adhesive, is simultaneously applied under said second insert 205 made of non-woven fabric.
[0034] Said semifinished sheets 201 are conveyed by means of a conveyor table 203 into a saw-tooth splicing machine, designated by the reference numeral 217, where they are butt-spliced.
[0035] The resulting continuous veneer then enters a roll-forming and trimming machine 208, which provides constant sizing in terms of width and prepares a roll of veneer, designated by the reference numeral 218.
[0036] Said roll of veneer 218 is then used in parallel to a backing roll, designated by the reference numeral 219, which supplies a backing film 202.
[0037] Said backing film 202 is guided through a glue spreading machine, designated by the reference numeral 220, after which the roll of veneer 218 is arranged and is thus unrolled exactly onto the backing film 202, to which adhesive is applied beforehand.
[0038] The result is a semifinished product which, after the drying of the adhesive by means of batteries of infrared lamps, designated by the reference numeral 221, and after pressing by means of a continuous press 222 and a calender press designated by the reference numeral 223, is trimmed in terms of width and then rolled up in a second roll-forming and trimming unit 211.
[0039] In a fourth embodiment, in the method illustrated in Figures 4, 5 and 6, semifinished sheets are used, which have a reinforced saw-tooth splice, similar to the splice used in the third embodiment.
[0040] The method further requires a saw-tooth splicing machine, designated by the reference numeral 317 in Figure 10, to replace the simple press 115 of Figure 4; said machine is to be arranged between the cold press 307 and the first roll-forming and trimming unit 308.
[0041] The materials employed, as well as the dimensions that constitute the individual components of the invention, may of course be the most pertinent according to specific requirements.
[0042] The disclosures in Italian Patent Application No. TV99A000103 from which this application claims priority are incorporated herein by reference.
[0043] 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.
a fourth step for sequentially positioning, along a longitudinal axis, a plurality of single semifinished sheets on a backing which is pre-glued with thermosetting adhesive and is unrolled continuously, with arrangement, on the splice, of a first tear-preventing insert, with insertion of a second locator insert for optical reading;
a fifth step of hot and cold pressing of said sequentially arranged sheets;
a sixth step for rolling, unrolling and sizing said sheet thus obtained and for re-rolling and trimming the resulting roll.
a fourth step for sequentially positioning, along a longitudinal axis, a plurality of individual and separate semifinished sheets on corresponding individual and separate backing sheets, with hot and cold pressing of the resulting sheet pairs, arranged sequentially, and provision of individual and separate semifinished sheets of veneer;
a fifth step for pressing in a third press for the butt-splicing of two contiguous semifinished sheets of veneer, after preliminary positioning, above and below the joint, of two pre-glued metal laminas;
a sixth step for rolling, unrolling and sizing said resulting sheet and for re-rolling and trimming the resulting roll.
a fourth step for sequentially positioning, on a conveyor table and along a longitudinal axis, a plurality of single semifinished sheets, which conveniently have, at their end, a saw-tooth profile, and for positioning on the splice a first tear-preventing insert, with insertion of a second locator insert for optical reading;
a fifth step for butt-splicing, in a saw-tooth splicing machine, two contiguous semifinished sheets, and subsequent rolling so as to obtain a roll of veneer;
a sixth step for unrolling said roll of veneer onto a pre-glued backing film, and subsequent drying;
a seventh step for pressing said sheet thus obtained and for re-rolling and trimming the resulting roll.