Automated cutting station for wood blanks

Abstract: A station (10) for cutting sheets of wood (13) and in particular packages of blanks comprises first means (12) of positioning a package of sheets under a first cutter (15) so as to sequentially separate parts of the package. Means (14) take the cut part and send it to a second cutter (17) for sequentially cutting of the part along a second direction so as to obtain another division in subparts sequentially and selectively conveyed outside the station. Electronic control means manage operation of the cutters and the positioning and taking means to perform the cuts in accordance with that previously ordered by setting a grid of cuts.

Description: In the known art of cutting packages of wood blanks there is presently used a sequence of different machines to each of which are assigned one or more operators. For example, the structure of a cutting line is generally made up of a first station comprising a first cutter operated by a first operator to make the necessary transverse cuts, a second station comprising a second cutter operated by another operator to make the necessary longitudinal cuts from one side of the blanks, a third station comprising a third cutter operated by a third operator to make the necessary longitudinal cuts on the opposite side of the blanks. Lastly, there is present a last cutter for cutting off the head of the blanks. Said cutter is usually operated by the same operator as the third cutter, who must thus alternate between the two stations. It is clear that both the space occupied by said multitude of stations and the number of operators necessary in addition to those assigned to loading and unloading the blanks make the cutting process very long and costly. In addition the work of the operators is laborious and tiring because of the manual moving of the blank they must necessarily perform. On one hand this reduces production and on the other reduces the safety level, already low, of performance of the cuts. EP-A-151 658 discloses a cutting station in which three in-line conveyors move a package of wood along a rectilinear path between a taking position and an unloading position. A first cutter cuts the package transversely to the path and a second cutter cuts the package parallel to the path only for squaring the edges of the package. Such a station has a complex structure. The general purpose of the present invention is to obviate the above mentioned shortcomings by providing a single cutting station for wood blanks which would perform rapidly and with minimal human assistance all the cutting operations required by packages of blanks while reducing space occupied, management costs and operator fatigue and increasing safety of use. In view of said purpose it is sought to provide in accordance with the present invention a wood sheet cutting station according to claim 1. To further clarify the explanation of the innovative principles of the present invention and its advantages as compared with the known art there are described below with the aid of the annexed drawings possible embodiments as nonlimiting examples applying said principles. In the drawings - FIG. 1 shows a schematic plan view of a cutting station provided in accordance with the present invention, FIG. 2 shows a schematic cross section view along plane of cut II-II of FIG. 1, FIG. 3 shows a schematic cross section view along plane of cut III-III of FIG. 1, FIG. 4 shows a schematic partial cross section view along plane of cut IV-IV of FIG. 5 of a detail of the station of FIG. 1, FIG. 5 shows a schematic partial plan view of the detail of FIG. 4, FIG. 6 shows a schematic view of first cut programming means for the station of FIG. 1, and FIG. 7 shows a schematic view of second cut programming means for the station of FIG. 1. With reference to the figures FIG. 1 shows schematically as a whole and indicated by reference number 10 a station in accordance with the present invention. Said station 10 comprises a supporting table 11 for a package, shown in broken lines and indicated by reference number 13, of blanks to be cut. In said table 11 run first means of positioning or front clamps 12 and rear clamps 14 for movement of the package 13 in a first direction under a first longitudinal cutter 15 cutting along a first cutting line transverse to the first direction. A means for taking and sending the cut part or running conveyor 16, for example the roller type, conveys that which is deposited thereon by means of the clamps 14 along a second direction to a second transverse cutter 17 cutting along a second cutting line transverse to the second direction at the output of which a conveyor belt 18 conveys the cut blanks to unloading. Additional conveyor 19, 20 evacuate the scrap produced by the cutter 15 and the second transverse cutter 17 respectively. As may be seen in FIG. 2, the first longitudinal cutter 15 comprises mobile sorting fins 21 and 22 to turn aside through appropriate channels the scrap from the cutter to the conveyor 19 and initially composed of two conveyor belts 23 and 24 upstream and downstream of the cutter. Advantageously the cutter has a pair of blades 26, 25 having opposed cutting edges for performance of a precision cut at the front and rear respectively of the package of blanks. In an innovative manner the pair of blades 25, 26 is placed beneath the cutting table and the corresponding presser 27 is arranged above the blades and is movable vertically to press on the upper surfaces of the package to be cut. Such an original arrangement allows provision in the table 11 with ease slots 28, 29 for the clamp guides 12 and 14. The presser 27 can have bucking edges of metal or plastic such as 'Vulcolan'. In the former case resistance to wear is greater while in the second case cuts are more accurate and this is useful when using sheets cut for splicing without rework. The clamps 12 and 14 are substantially moved together. The group of front clamps 12 and the group of rear clamps 14 are supported each by respective parallelogram frames 29, 30 moving by pistons 35, 36 from an operative position, shown in FIG. 2 for the frame 30, to a nonoperative position, shown in FIG. 2 for the frame 29. The frames 29, 30 comprise guides 31 and 32 each individually powered for horizontal running of a clamp by respective motors 33 and 34 as may be seen in FIG. 3 for the clamps 14. As may be seen in FIG. 3, the transverse cutter 17 comprises two upper blades 37 and 38 always with opposed cutting edges for the precision cuts at the head and tail of the packages with the help of a presser with fixed counterblade 39. In addition the cutter 17 comprises movable sorting fins 40 and 41 to turn aside with appropriate channels the scrap from the cutter to a conveyor 20 initially made up of two conveyor belts 42 and 43 upstream and downstream of the cutter. Operation of the various parts of the above described station is managed by an electronic control device, e.g. with microprocessor, of the known art and therefore not further shown or described since it is readily immaginable by those skilled in the art especially in the light of the following description of its operation. Among the various sensors and devices managed the control device 44 is connected also to photoelectric cell sensors 45 and 46 and to position encoders 47, 48 positioned upstream and downstream of the cutter 17 for purposes which are clarified below. FIGS. 4 and 5 show in greater detail a clamp, e.g. a gripping clamp 12, the clamp 14 being of the same design. As may be seen, the clamp comprises a slide 49 for running on the guide 31, by the above mentioned motor 33, and a head 50 comprising an element with cam sliding by means of a pin 52 in a slot 53 under the effect of a piston 54 to bring one gripping end, advantageously provided like a gripping roller generally in the form of a drum, from a nonoperative position, shown in unbroken lines in FIG. 4, to a gripping position on a package 13, shown in broken lines in FIG. 4, against a lower stop 57. Returning to FIG. 2 the station 10 comprises in addition means 56 sending signals 58 to the device 44 to allow programming of the station along a particular series of cuts on a package. As described in greater detail below said means 56 can be part of a viewing or laser scanning system or the like for automatic, semiautomatic or manual programming of the position of the cutting sequence. In use of the station a package of wood blanks to be cut is fed onto the table 11 manually or by conveyor belt of the known art and therefore not shown. The control system 44 then raises the clamps 12 by operation of the pistons 35 and advances them with the motors 33 until they are even with the edge of the package and then lowers their gripping end 55. In this manner the package is firmly held by the clamps which arrange it under the cut-setting means 56 while advancing. For example, once the control device 44 has received by methods described below the data for the cuts to be performed the clamps advance further to bring the package under the cutter 15 which is then commanded to perform in sequence all the preset longitudinal cuts. Between one cut and the next the clamps can advance independently of each other so as to perform also if necessary mutually oblique cuts. Initially a first trimming cut is performed on the longitudinal edges of the package. For this purpose the blade 26 is used and the scrap obtained is turned aside by movement of the fins 22 onto the belt 24 by which it is sent to the belt 19 to be evacuated from the station. The clamps 14 are raised and advanced to grip the sheared part emerging from the cutter 15. The clamps position the blank and the cutter is commanded to perform the cut. The piece cut downstream from the cutter 15 is then conveyed by the clamps 14 along the first direction as shown by 13' in FIGS. 2 and 3 onto the roller conveyor 16 from which it is conveyed along a second direction to the cutter 17. The photoelectric cell 45 detects the head of the package arriving at the cutter 17 and enables reading of the encoders 47, 48 to ascertain reaching of a predetermined transverse cutting position. Then the blade 38 is operated to trim the head of the blank and the corresponding scrap is evacuated by operation of the fins 40 and the belts 42 and 20. Advance of the blank 13' continues and the encoders and the photoelectric cells 45, 46 allow ascertaining of the position reached in each instant by the blank 13' so that the control device 44 continues to command operation of the cutter 17 to perform all the transverse cuts ascertained for the sheared piece 13'. As the cut subparts emerge from the cutter 17 they are conveyed along the conveyor 18, for example to the storing, packing or similar means of the known art hence not shown. If in the cutting programme there are identified in the wood defects to be eliminated the cut piece containing a defect is evacuated by operation of the fin 41. The last transverse cut is performed by the blade 37 so as to trim the tail of the package of blanks 13' and the scrap is evacuated again by the fin 41. During the above transverse cutting operations of the piece 13' the longitudinal cutter 15 is operated to provide the next programmed cut so as to supply sequentially at the outlet another piece which will be conveyed to the cutter 17 after completion of the cutting of the preceding piece 13'. For this reason, during cutting of the piece 13' the clamps 14 are lowered to translate thereunder and return to the advanced position to grip the part of the package in simultaneous cut under the cutter 15. The cutter operations described proceed then until completion of the longitudinal cuts of the package 13. Any defects in the wood detected during setting of the cuts and which can be eliminated by longitudinal cuts will be removed by cutting the longitudinal strip containing them and sending them to scrap by operation of the fin 40. The last cut will be performed by the blade 25 to trim the second longitudinal edge of the package and the scrap will be eliminated by operation of the fin 21. A new package can then be positioned on the table 11, from which the clamps 12 have withdrawn by operation of the pistons 35, and a new cutting program can be started. It is clear at this point that a station in accordance with the present invention can automatically cut the wood blanks both transversely and longitudinally and supply from the output of the tape 18 a sequence of accurately cut parts and from the belts 19, 20 wood scrap generated. The sequence of cuts to obtain cut parts as desired and to eliminate the parts containing defects can be set on the control device 44 by various procedures, each satisfying a certain type of requirement. For example, FIG. 6 shows schematically a first possible embodiment, indicated by reference number 56', of the means 56 of FIG. 2. The embodiment 56' comprises a telecamera 59 sending the image of the package 13, placed on the table 11, to a processing unit 60 having a screen 61 reproducing the image. The operator can trace the lines 62 representing a cutting grid and adapted to the position of the defects and the shape of the package, for example with a keyboard 63 or another input device such as a mouse or a graphics pad. In addition, again with the same input devices, the operator can indicate which parts of the board are to be scrapped. On the basis of these data the processor 60 sends to the control device 44 the coordinates of the package on which to sequentially perform the various cuts and which parts to scrap by operation of the various fins 21, 22, 40, 41. As is readily immaginable for those skilled in the art, it is also possible to program the processing unit 60 so that it automatically detects in a known manner the position of defects in the wood and independently selects an optimal cutting grid, relieving the operator of this duty also. FIG. 7 shows schematically a second alternate embodiment, indicated by 56'', of the means 56 of FIG. 2. The embodiment 56'' comprises means 65, 66 of controlled laser light emission to trace on the surface of the package to be cut longitudinal and transverse lines respectively. Said means can be for example provided by laser sources with cylindrical lens to project lines on the surface of the package and by powered operations for moving of the lines along the surface thereof. Said laser scanning devices are of the known art and accordingly are not described further since they are readily immaginable by those skilled in the art. Direction of the laser source is controlled by an electronic control device to which arrive setting signals emitted by manual controls 68 for the transverse lines and 69 for the longitudinal lines. To see comfortably the position of the laser lines projected on the package, there is placed thereover obliquely a mirror 70 in which the operator can see the reflected image. In use the operator operates the controls 68 and 69 to position the lines even with the required cuts and send said data to the control device 44 for execution thereof. Depending on the characteristics of the means 65 and 66 selected, projection can be performed to obtain a single transverse line and a single longitudinal line at a time, representing two cuts during selection, or see the lines of the two cuts during selection and the lines corresponding to the cuts already selected. As an alternative there can be used a means 65 projecting a fixed longitudinal line and the controls 69 can control the position of the clamps 12 to rotate and translate the package under the line. To identify which cut parts are to be eliminated the operator can for example use a keyboard indicating device or the like or control the scrap in real time during cutting. It can also be immagined to use in place of the mirror a telecamera and a screen, e.g. as already shown in FIG. 6. In this manner it is also possible to indicate on the screen the parts to be scrapped similarly to that which was described with reference to the embodiment of FIG. 6. It is clear at this point that it is possible to provide a system for setting the cuts to be made. Naturally the above description of an embodiment applying the innovative principles of the present invention is given merely by way of example and therefore is not to be taken as a limitation of the patent right claimed here. For example the structure of the station can be modified depending on the general dimensions of the packages it is desired to process. The clamps 14 can also be provided running on fixed guides while giving up optimization of the processing times obtained by rapid return of the clamps 14 and the resulting performance of a new longitudinal cut while the transverse cuts on a piece 13' are being performed. Although it is preferable that the clamps 12 be retractable and disappearing in the table 11 so as to allow loading without obstacles of a package on the table 11, they too can be provided running on fixed guides. In addition, the cut presetting systems can be varied and even combined with each other compared with the above description as is readily immaginable to those skilled in the art. For example, the telecamera 59 can be of the linear type and hence moving to scan the entire surface of the package, or with matrix. Viewing on the viewer can be total or divided in a sequence of partial images to save memory in the processing unit 60.

Claims: Wood sheet cutting station (10) and in particular for packages of blanks (13) comprising in combination first means (12, 14) of positioning a package of sheets under a first cutter (15) cutting along a first cutting line and operated to separate sequentially parts of the package, means (16) of taking the cut part and sending them to a second cutter (17) for sequential cutting of the part along a second cutting line, substantially normal to the first, to obtain another division in subparts sequentially and selectively conveyed to an outlet position (18) outside the station, electronic control means (44) being connected to the means of positioning (12, 14), to the means of taking (16) and to the cutters (15, 17) to control their operation in positioning and performing cuts on the package in programmed positions by setting a grid of cuts, the first positioning means (12, 14) moving the package along a first path (28, 29) normal to the first cutting line, characterised in that the taking and sending means (16) moves the cut parts of the package sequentially along a second path (16) towards the outlet position (18) at the output side of said second transverse cutter (17), said second path (16) being normal to both the said first path (28, 29) and the said second cutting line. Station in accordance with claim 1 characterized in that there are provided first selection means (21, 22) selectively starting in a scrap path parts cut by the first cutter (15). Station in accordance with claim 1 characterized in that there are provided second selection means (40, 41) selectively starting in a scrap path subparts cut by the second cutter (17). Station in accordance with claim 2 characterized in that the first selection means comprise opening fins (21, 22) commanded toward the unloading path of running tables (23, 24) of the cut parts. Station in accordance with claim 3 characterized in that the second selection means comprise opening fins (40, 41) commanded toward the unloading path of running tables (42, 43) for the cut subparts. Station in accordance with claims 2 and 3 characterized in that the unloading paths comprise conveyor belts (23, 24, and 42, 43) Station in accordance with claim 1 characterized in that the first positioning means (13, 14) comprise first clamps (12) for gripping on one side of the package and commanded to run along guides (28) between a non-operative position and a position for positioning of the package under the first cutter (15). Station in accordance with claim 1 characterized in that the taking means (16) comprises a powered conveyor such as a roller conveyor (16) leading to the second cutter (17) and second gripping clamps (14) commanded to run along guides (29) between a gripping position on one side of a cut part in said first cutter and a position of release thereof on said powered conveyor (16). Station in accordance with claim 7 characterized in that the guides (28) of the first gripping clamps (12) are movable by moving means between an operative or gripping position bearing the clamps even with a running table (11) for the package and a nonoperative position bearing the clamps (12) outside said table (11). Station in accordance with claim 9 characterized in that the moving means comprise an articulated parallelogram (29) lift arranged under the package running table (11). Station in accordance with claim 7 characterized in that each clamp (12) comprises an element (51) running with a pin & cam (52) in a slot (53) under the effect of a linear drive between a position bearing one gripping clamp end (55) at a corresponding stop (57) for blocking therebetween the package and a release position with said gripping end (55) withdrawn from said stop (57). Station in accordance with claim 11 characterized in that the gripping end comprises a gripping roller (55) shaped generally like a barrel. Station in accordance with claim 8 characterized in that the guides of the second gripping clamps (14) are movable by moving means (36) between an operative or gripping position bearing the clamps even with a running table (11) for the cut parts and a nonoperative position bearing the clamps outside said table (11). Station in accordance with claim 13 characterized in that the moving means comprise an articulated parallelogram (30) lift arranged under the running table (11) of the cut parts. Station in accordance with claim 8 characterized in that each clamp (14) comprises an element (51) running with a cam pin (52) in a slot (53) under the effect of a linear drive between a position bearing its clamping end (55) drawing near to a corresponding stop (57) for blocking therebetween the cut part and a release position with said gripping end (55) withdrawn from said stop (57). Station in accordance with claim 15 characterized in that the gripping end comprises a gripping roller (55) shaped generally like a barrel. Station in accordance with claim 1 characterized in that the first cutter (15) comprises cutting blades (25, 26) beneath the cutting table and a mobile bucking presser (27) therefor arranged above said cutting table. Station in accordance with claim 1 characterized in that the first cutter (15) comprises two selectively operated parallel blades (25, 26) with cutting edges sharpened in opposing directions. Station in accordance with claim 1 characterized in that the second cutter (17) comprises two selectively operated parallel blades (37, 38) with cutting edge sharpened in opposing directions. Station in accordance with claim 1 characterized in that the setting means comprises a telecamera (59) for picturing the surface of the package and said telecamera is connected to devices (60) for processing the image taken. Station in accordance with claim 20 characterized in that said processing devices (60) for the image comprise systems for identification of the plan form of the package and defects in the wood and means of calculation of a cutting grid isolating in parts and subparts of the package said defects and said processing devices sending coordinates for the cuts belonging to said grid to said electronic control means. Station in accordance with claim 1 characterized in that the setting means comprise directional light sources (65, 66) projecting upon manual command luminous lines on the package to visualize thereby the required cutting lines. Station in accordance with claim 22 characterized in that the setup means comprise directional sensors for said sources (65, 66) for sensing the relative positions of the luminous lines on the package and said setup means send to the electronic control means signals for coordinates corresponding to said positions as cutting coordinates. Station in accordance with claims 20 and 22 characterized in that the image processing devices detect the relative positions of said luminous lines on the image filmed and send to the electronic control means signals for coordinates corresponding to said positions as cutting coordinates. Station in accordance with claim 20 characterized in that the image processing devices comprise manual means (63, 64) for tracing lines on said screen identifying a corresponding cutting grid to be executed. Station in accordance with claim 25 characterized in that the manual tracing means comprise an input keyboard for position commands of said lines on the screen. Station in accordance with claim 1 characterized in that the electronic control means (44) comprises sensors (45, 46, 47, 48) for sensing the position of a cut part approaching the second cutter.

Inventors: CREMONA LORENZO, CREMONA, LORENZO
Applicants: CREMONA ANGELO & FIGLIO, ANGELO CREMONA & FIGLIO S.P.A.
Application year: 1992
Main classification: B27L5
IPC codes: B26D7, B23D47, B26D5, B26D1, B27B1, B27G1, B27L5