METHOD OF GLUING STRIPS OF WOOD TO PRODUCE COMPOSITE STRIP BLOCKS AND THE MACHINE SUITED TO PERFORMING THIS METHOD

Abstract: A method of gluing strips of wood to produce composite strip blocks that prescribes: setting a series of strips side by side and one after another, crossways to a straight direction of travel; making the strips advance; distributing an adhesive on the strips; setting a panel on the strips; pressing the strips and panel together. The strips are spaced one after another in sequence along the direction of travel before bonding the panel. The method is performed by a combiner machine (1) comprising a frame (2) holding: a first feed line (3) where the strips (L) are set crossways; a second feed line (5) where the panels are set lengthways; a glue spreader unit (7); a laminating station (8) for panels (P) and strips (L); a pressing station (9). A spacer unit (10) set upline to the laminating station (8) spaces apart the strips (L) along the direction of travel.

Description: METHOD OF GLUING STRIPS OF WOOD TO PRODUCE COMPOSITE STRIP BLOCKS AND THE MACHINE SUITED TO PERFORMING THIS METHOD The invention concerns a method of gluing strips of wood to produce composite strip blocks in general, especially suited for producing parquet strips and the machine suited to performing this method. It is known that the strips that are used for producing parquet are made from a panel of hardwood glued onto a backing that can be made of one or more softwood strips. To produce these strips one of the known methods prescribes that a strip is placed on a work table and is covered with a hardwood panel, after having spread an adhesive substance over the contact surfaces. The composite strip block thus prepared then undergoes the action of a press until the glue has set. In conclusion the strip that constitute the backing is scored crossways with a series of parallel cuts, uniformly spaced along its length that provide the strip with enough flexibility to allow it to adapt to the surface where it is laid. The main inconvenience of this method is that the whole work cycle cannot be performed by continuous throughfeed, since a worker is required to transfer the strip block obtained at the exit of the press to the subsequent milling process. It is clear that this highly labour intensive work involves high production costs and low productivity. An additional inconvenience is that the substantially labour-intensive method described above is not capable of reproducing a constant quality standard of product. Another known method, that partly solves some of the aforesaid inconveniences, prescribes that a series of strips are set in line, one after another and side by side on a flat surface crossways to a selected direction and that they are then uniformly spaced so that, after having applied a coat of glue, the hardwood panel can be bonded to them. A known machine that performs the above method prescribes that the strips are set side by side on a work table and one by one they are picked up using a series of suction cups overhanging each strip. The suction cups first move apart, spacing the actual strips and then lay the strips back on the worktable. Subsequently, after having first covered the contact surfaces with an adhesive substance, the panel of hardwood is applied, thereby obtaining the strip block that is then put under the action of a press until the glue has set. The main inconvenience of the machine described above is that the strip spacing operations, performed by suction cups, have a significant effect on the average time for the work cycle of each individual strip, which duly reflects on production costs. Another inconvenience is that during the process the suction cups sometimes do not ensure a perfect hold on the strips and this results in misalignments between strips and bad spacing, giving rise to manufacturing defects. Another inconvenience is that since this is not a continuous throughfeed work method, but prescribes loading and unloading the machine, performance in terms of production capacity is substantially limited. This invention intends to overcome these inconveniences. In particular a first scope of this invention is to provide a method of gluing strips of wood to produce composite strip blocks that glues strips and hardwood panel together in an automated and continuous throughfeed cycle. Another scope is to provide a method that does not require manual interventions by a worker. Another scope is to produce a combiner machine that allows to perform the method under this invention. An additional scope is for the combiner to allow a reduction in production costs per unit product against known types of combiner machines. Last but not least, a scope is that the combiner invention reproduces a constant standard of finished product. The aforesaid scopes are achieved by a method of gluing strips of wood to produce composite strip blocks that in accordance with the main claim comprises the following operations: - set a series of strips side by side and one after another, crossways to a straight direction of travel; - make said first strips advance along said straight direction of travel; - distribute a uniform coat of adhesive on said strips; - set a panel on the surface of said strips covered by said uniform coat of adhesive; - press said strips and said panel together to obtain said composite strip blocks, which is characterised in that said strips are spaced apart in sequence, one after another by a substantially constant distance along said direction of travel, before bonding them to said panel. The combiner machine for wooden strips, also part of this invention and suited to performing the aforementioned method, comprises a frame that holds: - at least one first feed line having a first conveyor belt creating a straight direction of travel, where a series of strips are set side by side in a crossways direction; - at least one second feed line having a second conveyor belt creating a straight direction of travel, where a series of panels are set one after another in a lengthways direction, said feed lines lying over each other; - at least one glue spreader unit mounted above said first conveyor belt suited to spreading a uniform coat of glue on said strips; - at least one laminating station for bonding said panels to the underlying strips, mounted downline to said spreader unit along the direction of travel, to produce said composite strip block; - at least one pressing station provided with means of pressing suited to pressing said strip block, which is characterised in that it comprises a spacer unit mounted upline to said laminating station and suited to spacing said strips from each other in sequence one after another by a substantially constant distance along said direction of travel. An advantage of the method described above is that it allows to produce parquet strips without any intervention whatsoever from a worker. Another advantage of the method and the machine under this invention is that they allow to reduce the work cycle time for producing each single parquet strip, permitting to diminish production costs and therefore the sales price of the finished product. Said scopes and advantages will be better explained during the description of a preferred form of execution of the invention given as a guideline but not a limitation and illustrated in the attached diagrams, where: - fig. 1 illustrates a side view of the combiner machine invention that performs the gluing method under this invention; - fig. 2 illustrates an enlarged side view of part of the machine in fig. 1 ; - fig. 3 illustrates an enlarged side view of some components in fig. 2; - fig. 4 illustrates a plan view of part of the machine in fig. 1 ; - fig.'s 5 to 7 illustrate three stages of processing of the machine under this invention. The method of gluing strips of wood to produce composite strip blocks under this invention comprises the following operations: - set a series of strips side by side and one after another, crossways to a straight direction of travel; - make said first strips advance along said straight direction of travel; - spread a uniform coat of adhesive over said strips; - set a panel over the surface of said strips covered with said uniform coat of adhesive; - press said strips and said panel together to obtain said composite strip block. The strips are spaced in sequence, one after another, by a substantially constant distance along the direction of travel, before laying the panel over them and after having spread the adhesive. Speeding up each strip in the direction of travel from the next one upline, the strips are spaced from each other by a constant distance, proportional to their increase in speed. Likewise each strip can be spaced by slowing down each strip with respect to those upline, again with reference to the direction of travel. According to a preferred form of execution the combiner machine for wood strips under this invention is illustrated in fig. 1. It comprises a frame 2 that holds a first feed line 3 having a first conveyor belt 4 that creates a straight direction of travel 11 for the strips L, which are set crossways, side by side to each other, and a second feed line 5 having a second conveyor belt 6 that creates a second straight direction of travel 110 for a series of hardwood panels P, set lengthways, one after another. The frame also holds a glue spreader unit 7 mounted above the first conveyor belt 4, a laminating station 8 where the overlying feed lines 5 and 3 converge together to bond the panels P onto the underlying strips L producing the strip block S and a pressing station, generally indicated by 9, equipped with means of pressing, not illustrated, suited to pressing the strip block S. The invention prescribes that the combiner machine 1 comprises a spacer unit 10, suited to spacing the strips L in sequence one after another by a substantially constant distance along the direction of travel 11 , mounted upline to the laminating station 8. In particular the spacer unit 10 is mounted upline to the spreader unit 7 and comprises, as illustrated in detail in figures 2 to 4, means of propulsion for advancing the strips L, generally indicated by 12, which are followed by a slideway 30 suited to feeding the pair of drag belts 14 shown in detail in fig. 3. The drag belts 14 are facing each other and separated by a distance 15 basically equal to the length of the strips L and are suited to rubbing against the ends of the actual strips L to speed them up along the direction of travel 11 , spacing them by a substantially constant distance 16. With regards to the means of propulsion 12, they comprise a pair of spur gears 17 facing each other, where one can be seen in detail in fig.'s 3 and 4 positioned downline to the first conveyor belt 4 with their axis of rotation 18 being basically horizontal and set crossways to the direction of travel 11. Each spur gear 17 has thrust teeth 17a protruding from the surface defined by the first conveyor belt 4, which work with backstop devices 20 mounted above said thrust teeth to withhold/push the strips L along the direction of travel 11. Said shaped backstop devices 20 comprise a plate 21 with an essentially longitudinal construction with one end elastically pivoted to the frame 2 by a pin 22 and an elastic device comprising a spring 24. The plate 21 also has a cavity 23 suited to receiving, as will be seen below, the strip L to hold it along the direction of travel 11. With regards to the glue spreader unit 7, it comprises an adhesive reservoir 7a that feeds a spreader 7b, suited to depositing a uniform coat of glue onto the strips L. The laminating station 8 comprises means of combining, not illustrated, suited to joining the strips L and the panels P together after their are laid over each other, thereby producing the composite strip block S. From a functional standpoint the combiner machine 1 prescribes that the strips L supplied by a feed unit, not illustrated, travel along direction 11 carried by the conveyor belt 4 to feed the spacer unit 10 while meantime the second conveyor belt 6 converges the hardwood panels P towards the means of laminating 8. As can be seen in fig.'s 5 and 6 the tooth 17a of the spur gear 17 lifts the strip La pushing it towards the cavity 23 in the plate 21 which flexes to adapt to the thickness of the strip by rocking on the pivot 22. The spur gear 17 continues to travel and drops the strip La, as illustrated in fig. 7, in the well created by the space between the two consecutive teeth 17a and 17b thereby allowing tooth 17b to push the strip La towards the slideway 30 and thereby making all the strips found downline advance by a step. In this way the machine provides a fine, precise control over the speed of feeding first the glue spreader unit 7 and then the pair of drag belts 14 which uniformly space each strip L. The strips L spaced accordingly are collected by an outlet conveyor belt 31 that feeds the laminating station 8 which produces the strip block S that is pressed in the following pressing station 9 after which the parquet strip T has been solidified and is ready for storage. It is important to note that the distance between each tooth on the spur gear 17 constitutes the maximum limit in the width of strips L that can be processed by the combiner machine 1. After the means of propulsion 12 the strips L advance along the slideway 30, set perfectly side by side and crossways to the direction of travel thereby forming a uniform surface to receive the adhesive that is deposited by the spreader unit. It is equally important to note that the strips L are stopped and released by the plate 21 thereby ensuring continuity in the surface that receives the adhesive. It should also be noted that the two spur gears 17 are set towards the ends of the strips L and parallel to each other in order to ensure the strips L are in a perpendicular position to the direction of travel.

Claims: CLAIMS 1) Method of gluing strips of wood to produce composite strip blocks comprising the following operations: - set a series of strips side by side and one after another, crossways to a straight direction of travel; - make said strips advance along said straight direction of travel; - distribute a uniform coat of adhesive on said strips; - set a panel on the surface of said strips covered by said uniform coat of adhesive; - press said strips and said panel together to obtain said composite strip block; characterised in that said strips are spaced apart in sequence, one after another by a substantially constant distance along said direction of travel, before bonding them to said panel. 2) Method according to claim 1) characterised in that said strips are spaced apart after having distributed said adhesive. 3) Method according to claim 1) or 2) characterised in that the strips are spaced apart by speeding each of them up with respect to the strip upline in the direction of travel. 4) Method according to claim 1 ) or 2) characterised in that each strip is spaced apart by slowing down the strips upline to it along the direction of travel. 5) Combiner machine (1) for wooden strips suited to performing the method according to claim 1 ) comprising a frame (2) that holds: - at least one first feed line (3) having a first conveyor belt (4) creating a straight direction of travel (1 1 ), where a series of strips (L) are set side by side in a crossways direction; - at least one second feed line (5) having a second conveyor belt (6) creating a straight direction of travel (110), where a series of panels (P) are set one after another in a lengthways direction, said feed lines (3, 5) lying over each other; - at least one glue spreader unit (7) mounted above said first conveyor belt (4) suited to spreading a uniform coat of glue on said strips (L); - at least one laminating station (8) for bonding said panels (P) to the underlying strips (L), mounted downline to said spreader unit (7) along the direction of travel (11) to produce said composite strip block (S); - at least one pressing station (9) provided with means of pressing suited to pressing said strip block (S); characterised in that it comprises a spacer unit (10) mounted upline to said laminating station (8) and suited to spacing said strips (L) from each other in sequence one after another by a substantially constant distance (16) along said direction of travel (11). 6) Combiner machine (1) according to claim 5) characterised in that said spacer unit (10) is mounted downline to said at least one spreader unit (7). 7) Combiner machine (1) according to claim 5) or 6) characterised in that said spacer unit (10) comprises means of propulsion (12) for advancing said strips (L), followed by a slideway (30) suited to feeding at least one pair of drag belts (14) that are facing each other and separated by a distance (15) basically equal to the length of said strips (L) and suited to rubbing against the ends of the actual strips (L) to speed them up along their direction of travel (11). 8) Combiner machine (1) according to claim 7) characterised in that said means of propulsion (12) comprise at least one spur gear (17) positioned downline to said first conveyor belt (4) and with its axis of rotation (18) being basically horizontal and set crossways to said direction of travel (11). 9) Combiner machine (1) according to claim 8) characterised in that said gear (17) has thrust teeth (17a, 17b) protruding from the surface defined by said first conveyor belt (4), said thrust teeth (17a, 17b) being suited to working with shaped backstop devices (20) mounted above them, to withhold said strips (L) along said direction of travel (11). 10) Combiner machine (1) according to claim 9) characterised in that said shaped backstop devices (20) comprise a plate (21) with an essentially longitudinal construction with one end elastically pivoted to said frame (2) by a pin (22) and an elastic device (24), havind a cavity (23) suited to receiving said strips (L) to withhold them along said direction of travel (11).

Inventors: FRANCHIN PIER LUIGI, FRANCHIN, PIER, LUIGI
Applicants: COSTA S P A A, FRANCHIN PIER LUIGI, A. COSTA S.P.A., FRANCHIN, PIER, LUIGI
Application year: 2000
Main classification: B27D
IPC codes: B27G11, B27M3