CA3007862A1

CA3007862A1 - Method and device for laying veneer panels

Info

Publication number: CA3007862A1
Application number: CA3007862A
Authority: CA
Inventors: Josef Hanses
Original assignee: Hanses Sagewerkstechnik & Co KG GmbH
Current assignee: Hanses Sagewerkstechnik & Co KG GmbH
Priority date: 2015-12-30
Filing date: 2016-12-01
Publication date: 2017-07-06
Also published as: DE102015122943A1; WO2017114632A1; EP3397435A1

Abstract

A method for laying veneer panels (14a, 14b) when manufacturing laminated veneer lumber, in which a billet (12) made up of a stack of multiple glued veneer panels is fed on a conveyor (10) to a press (16), and further veneer panels are layed on the billet (12) using at least two manipulators (20, 22), wherein each manipulator (20, 22) is assigned a working region (A, B) for laying the veneer panels on the billet, and the working regions of the manipulators are arranged in succession along the conveyor (10), characterized by an operating mode in which one of the manipulators (20) is used to feed a veneer panel (14b) to a laying location in the working region (B) of the other manipulator (22).

Description

Hanses Sagewerkstechnik, Application No.: PCT/EP2016079502 04.06.2018 Method and device for laying veneer panels The invention relates to a method for laying veneer panels when manufacturing laminated veneer lumber, in which a billet made up of a stack of multiple glue-brushed veneer panels is fed on a conveyor to a press, and further veneer panels are laid on the billet using at least two manipulators, wherein each manipulator is assigned to a working region for laying the veneer panels on the billet, and the working regions of the manipulators are arranged in suc-cession along the conveyor.
DE 10 2008 027 706 Al discloses a method of this type wherein the veneer panels are laid so as to form an endless billet that is supplied continuously or step-wise on the conveyor to a press where the veneer panels are pressed to form a laminated veneer string.
A high transport speed and stroke rate, respectively, of the conveyor, and, accordingly, a high productivity is achieved by simultaneous use of several manipulators.
It is an object of the invention to provide a method that it is less prone malfunction.
According to the invention, this object is achieved by an operating mode in which one of the manipulators is used to fed the veneer panel to a laying location in the working region of the other manipulator.
if, for any reason, an interruption occurs in the operation of one of the manipulators, then, in the mode of operation according to the invention, one of the other manipulators may take-over the task of that manipulator, so that the conveyor and the press need not be stopped.
More specific useful details and further developments of the invention and indicated in the dependent claims.
An independent apparatus claim is directed to an apparatus for carrying out the method.
In one embodiment, the supply of a veneer panel to a laying location in the working region of the other manipulator is achieved by that the manipulator that supplies the veneer panel is

2 Hanses Sagewerkstechnik, Application No.: PCT/EP2016079502 04.06.2018 driven beyond its regular working region into the working region of the other manipulator and, then, directly adds the veneer panel to the billet.
In another embodiment, it is also possible that the veneer panel to be supplied is trans-ferred from one manipulator to the other in a kind of "handshake" maneuver.
This op-eration mode requires, however, that the manipulator at which the interruption of oper-ation occurs is itself still functioning, and the interruption has been caused only by a disturbance in the supply of veneer panels to that manipulator.
In particular, the invention offers the possibility to serve with priority the location which is arranged downstream in the conveying direction of the billet, in order to as-sure that the full number of veneer layers in the string is completed before the billet enters into the press.
In normal operation, the equipment is preferably run such that the manipulators do not work at their capacity limit. That means that the speed or the stroke rate of the con-veyor is adjusted such that each manipulator has more time for laying a veneer panel than the minimum that is required for a full laying cycle. Then, after an interruption of operation, the stroke rate of the manipulators may preliminarily be increased in order to make up for the delay. In this way, a stable and continuous production is possible in spite of occasional interruptions of the operations of individual manipulators.
The larger tolerance towards interruptions of operation facilitates the overall process control and, moreover, opens the possibility for new process variants that could not be implemented in the past.
For example, it has been common practice to check the veneer panels for their quality and discard damaged veneer panels before they were supplied to the manipulators.
Now, the invention opens the possibility to use the manipulators that are installed at the conveyor, anyway, also for excising damaged veneer panels, because the time needed for this operation does not lead to an interruption of the operation sequence.

3 Hanses Sagewerkstechnik, Application No.: PCT/EP2016079502 04.06.2018 Conversely, it is also possible that veneer panels with particular high quality are pre-liminarily excised by means of the manipulators and are held ready in an intermediate store so that they can be used for the top and bottom cover layers of a veneer string, thereby to give the laminated veneer lumber a perfect outer surface.
An embodiment example will now described in conjunction with drawings, wherein:
Fig. 1 is plan view of a laying device according to the invention;
Fig. 2 is a side view of the device shown in Fig. 1;
Fig. 3 is a front view of the device as seen in the direction of arrows III-III
in Fig. 2;
Fig. 4 is a side view of a part of the device during a regular laying opera-tion; and Fig. 5 is a side view of the part of the device during a laying operation in a mode according to the invention.
Fig. 1 shows, in plan view, a conveyor 10 which serves for supplying an endless billet 12 of glue-brushed veneer panels 14, which abut each other and are laminated in sev-eral layers, continuously or step-wise to a press 16 where the veneer layers are pressed to form a laminated veneer lumber. The conveyor 10 is superstructed by a frame 18 in which two portal shaped manipulators 20, 22 are arranged to be movable on rails 24 in longitudinal direction of the conveyor 10. Each manipulator has assigned to it a supply line 26 and 28, respectively, on which the veneer panels 14 are supplied by means of a conveyor or unstacker which has not been shown.
Each supply line 26, 28 has a conveyor 30 to which the veneer panels are supplied from the bottom edge in Fig. I and on which they are moved-on to a respective fetch location 32 where there are taken over from the corresponding manipulator 20 or 22.

4 Hanses Sagewerkstechnik, Application No.: PCT/EP2016079502 04.06.2018 The fetch location is configured such that the veneer panels are mechanically aligned at their front and longitudinal edges. In example shown, a defect scanner 34 is in-stalled above and entry side of each conveyor 30, and a movable adhesive applicator 36 is arranged further downstream. The conveyors 30 and the fetch locations 32 as well as a storage shelf 38 are installed on a common rack 40 and are approximately level with the conveyer 10. In the storage shelf, the individual veneer panels are placed separately from each other in order to prevent them from being glued together.
The shelf is configured like a drawer system, so that each shelf panel may be served and emptied individually.
The two manipulators 20 and 22 have the same construction and each have a cross bar 42 that extends transversely across the conveyor 10 and has its opposite ends held movably in the rails 24. A respective manipulator head 24 is mounted on the cross bar 42 and is movable between a position above the conveyor 10 and a position above the fetch locations 32. As can be seen more clearly in Fig. 2, each manipulator head 44 has, at its bottom side, a guide rail 46 that extends in longitudinal direction of the con-veyor 10 and along which a carriage 48 is movable. A suction gripper 50 is mounted rotatably and height-adjustably on the carriage 48 and has suction heads with which a veneer panel 14 can be lifted, held and laid down in a desired position.
The cross bars 42 of the two manipulators 20 and 22 are guided in a common guide track 52 of the rails 24.
In a normal mode, the device operates as follows.
Veneer panels 14 are supplied to the conveyors 30 on the two parallel supply lines 26, 28 and are oriented such that their longitudinal direction is at right angles to the transport direction of the conveyor 10. The defect scanners 34 are used for an opto-electronic scan of the veneer panels, and the positions and shapes of defects relative to the contours of the veneer panels are stored electronically.

Hanses Sagewerkstechnik, Application No.: PCT/EP2016079502 04.06.2018 The adhesive applicators 36 are used for glueb-brushing the veneer panels. The adhe-sive may be applied in the form of tracks or as a film. The suction heads of the suction grippers 50 engage the glue-brushed veneer surface. In order to prevent failures of the suction heads due to glue and contaminants, a large number of suction nozzles with

5 low flow velocity are used. When a veneer panel is laid down, an additional cleaning action is performed by switching from vacuum to a blow mode.
A separator 52 (Fig. 4) on the bottom side of the suction gripper assures that the ve-neer panel, when it is laid down on the string, is released from the vacuum without delay and is laid down softly. The separator consists of several pressing arms that are pivotably held between the suction heads below the suction gripper. When a veneer panel is taken up, the suction gripper is lowered, so that the free end of the pressing arm engages the veneer panel and is tilted upwards against at least one row of suction heads. The vacuum is switched on, and the pressing arm is held in the lifted position by the suction heads, while other suction heads attracted the veneer panel.
When the veneer panel is laid down, the operation mode is changed from sucking to blowing, so that the pressing arm drops onto the veneer panel and reliably separates the same from the suction nozzles in spite of the adhesive. The air that is blown out causes the press-ing arm to be accelerated further. Only the standard functions "sucking" and "blow-ing" of the suction gripper are needed for controlling the pressing arm.
Another ad-vantage is that, when the veneer panel is taken up and transported, the weight of the pressing arms does compromise the holding force of the suction heads.
When a glue-brushed veneer panel has reached the fetch location 32, it is taken over at that location from the corresponding manipulator 20 or 22. The suction gripper 50 is lowered onto the veneer panel 14 and then lifted again together with the veneer panel and then moves along the cross bar 42 into a position above the conveyor 10.
The suc-tion gripper 50 is rotated 900 about a vertical axis, so that the longitudinal direction of the veneer panel is now in parallel with the transport direction of the conveyor 10.
Then, the manipulator is moved along the rails 24 into a position where the leading edge of the veneer panel is flush with the trailing edge of a veneer panel that has been laid earlier in the same layer of the billet 12. Then, in this position, the veneer panel is

6 Hanses Sagewerkstechnik, Application No.: PCT/EP2016079502 04.06.2018 laid down, by means of the suction gripper, on the conveyor or on a veneer layer that is already present on the conveyor. The positions of the reference edges of the veneer panels have already been detected at the fetch locations and are now tracked electroni-cally on the basis of the movements of the conveyer and the manipulators. When the billet 12 is moved continuously on the conveyer 10, the manipulators may move in synchronism with the conveyor during the laying operation.
During the laying process, as has been shown in Fig. 4, the manipulator 20 moves in a longitudinal direction of the conveyor 10 into a working region A which contains at least the fetch position, where the veneer panels 14 are taken over from the fetch loca-tion 32 of the supply line 26, and the laying position, where the veneer panel is laid down on the moving billet 12. This laying position is located further downwards, when the level of the veneer layer where the panel is laid is higher.
Likewise, the manipulator 22 moves in a working region B between the fetch position where the veneer panel is taken over from the fetch location 32 of the supply line 28, and the respective laying position.
As is shown in Fig. 4, the lower half of the veneer layers of the billet 12 consists of so-called half-books, i.e. staggered stacks of veneer panels that are laid with the manipu-lator 20. Similarly, the manipulator 22 lays half-books that form the upper half of the veneer layers and complete the billet 12. In Fig. 4, the pressing arm of the separator 52 of the manipulator 22 is in the lowered position for laying a veneer panel.
The veneer panels 14 that have been laid by the manipulator 20 have been designated by hatching in Fig. 4.
In case of an interruption in the function, the laying operation may become somewhat delayed. This delay can however be made up for by subsequently accelerating a little the stroke rate with which the manipulators 20 and 22 lay the veneer panels.
It must however be assured that, at the laying position that is the furthest downstream (closest to the press 16) the billet 12 is completed up to the topmost layer before it enters into the press. This can be achieved by temporarily switching into a special mode of opera-

7 Hanses Sagewerkstechnik, Application No.: PCT/EP2016079502 04.06.2018 tion in which the manipulator 22 that is responsible for the most downstream laying position is assisted by the manipulator 20.
This mode of operation has been illustrated in Fig. 5. The manipulator 22 has just laid a veneer panel 14a at the downstream end of the billet 12, and a suction gripper 50, shown in dashed lines in Fig. 5, is in a position above the fetch location 32 of the sup-ply line 28. Meanwhile, the manipulator 20 lays another veneer panel 14b (hatched), which it has fetched from the supply line 26, in the same laying position (except for a small offset of the butting edges) on the veneer panel 14a. If necessary, these opera-tions can be repeated several times, so that the veneer layers are laid alternatingly with the two manipulators 20 and 22. In this way, the billet 12 can be completed in time before it reaches the press.
In Fig. 5, the cross bar 42 and the manipulator head 44 of the manipulator 20 have moved into the working region B of the manipulator 22. However, since the cross bars of both manipulators are guided in the common guide track 52, the manipulator cannot overtake the manipulator 22. This, however, does not hold true for the suction grippers 50 of the two manipulators, because these suction grippers are held by the carriages 48 and are moveable along the guide rails 46. In Fig. 5, the carriage 48 of the manipulator 22 has been shifted to the right side (upstream), so that its suction gripper 50 can be held in a position above the fetch location 32 of the supply line 28 even though the manipulator head of this manipulator assumes a position further down-stream. In contrast, in case of the manipulator 20, the carriage 48 and its suction grip-per 50 have been shifted to the left side (downstream), so that the laying position for the veneer panel 14b can be reached.
In this mode of operation, the build-up of the lower half-book at the upstream end of the billet 12 is temporarily delayed, because the manipulator 20 is busy with other tasks. This delay can however be made up for as soon as the billet has been completed at the downstream end.

8 Hanses Sagewerkstechnik, Application No.: PCT/EP2016079502 04.06.2018 The mode of operation shown in Fig. 5 may also be utilized in other situations, for example in a situation in which the supply of veneer panels on the downstream-side supply line 28 has temporarily stopped and the manipulator 22 cannot continue to op-erate for that reason. Conversely, if an interruption occurs for the upstream side ma-nipulator 20, it is also possible that the manipulator 22 is used for tasks that are nor-mally scheduled for the manipulator 20.
This additional flexibility that is provided by the method according to the invention can be taken advantage of in many ways. If, for example, a newly supplied veneer panel passes the defect scanner 34 and it turns out that this panel is too heavily dam-aged, the gluing of this veneer panel may be skipped, and one of the manipulators 20, 22 may be utilized for transferring this veneer panel from the fetch location 32 into to storage shelf 38, where the damaged panel may then be removed manually while the operation of the device is continued with a fresh supply of veneer panels.
On the other hand, the storage shelf 38 may also be utilized for holding a stock of ve-neer panels without defects and with a particularly high quality that are suitable for the top and bottom cover layers of the billet 12. When the laying of a new half-book starts at the upstream end of the billet 12, the manipulator 20 fetches a defect-free veneer panel from the shelf 38 and placed it on the conveyor 10. When the topmost layer of a half-book is laid with the manipulator 22, this manipulator can also fetch a defect-free veneer panel from the shelf 38.
If it is found, while new veneer panels are supplied on the supply lines 26, 28, that one of these panels has no defects and is therefore suitable for a cover layer, it is also pos-sible to temporarily store this panel on the shelf 38 with one of the manipulators 20, 22.
If possible, it should also be avoided that two veneer panels that have defects that overlap in the billet are laid directly one upon the other. Also in this case the flexibil-ity of the method proposed here permits to buffer one of the two veneer panels in the shelf 38 and to insert it into the billet later and in another position.

9 Hanses Sagewerkstechnik, Application No.: PCT/EP2016079502 04.06.2018 The device and the method described here can be modified in various ways.
The manipulators 20, 22 may be movable independently of one another in separate guide tracks, so that they may completely interchange their positions along the con-veyor 10.
Optionally, the veneer panels may be supplied on the supply lines 26, 28 already in the orientation that they will have on the conveyor 10.
It is also possible to combine veneer panels with different dimensions in arbitrary con-figurations.
In another embodiment of the device, three or more parallel supply lines may be pro-vided. The corresponding manipulators should then be configured such that they can also serve the working regions of the respective neighbouring manipulator or manipu-lators. It is also possible to provide an additional supply line that is used specifically for supplying defect-free veneer panels for the cover layers. Then, no particular ma-nipulator is required for this supply line, and instead the manipulators for the other supply lines may be used to fetch the defect-free panels from the additional supply line when required.
Whereas, in the embodiment shown here, the veneer panels are glue-brushed already in the supply line 26, 28, before they are transferred onto the conveyor 10, it is also pos-sible in another embodiment that the veneer panels are glue-brushed only on the con-veyor 10, in which case one or more adhesive applicators are arranged to move over the conveyor 10 independently of the manipulators.

Claims

1. A method for laying veneer panels (14) when manufacturing laminated veneer lum-ber, in which a billet (12) made up of a stack of multiple glue-brushed veneer panels (14) is fed on a conveyor (10) to a press (16), and further veneer panels are laid on the billet (12) using at least two manipulators (20, 22), wherein each manipulator (20, 22) is assigned to a working region (A, B) for laying the veneer panels on the billet, and the working regions of the manipulators are arranged in succession along the conveyor (10), characterized by an operating mode in which one of the manipulators (20) is used to feed a veneer panel (14a) to a laying location in the working region (B) of the other manipulator (22).

2. The method according to claim 1, wherein the veneer panel (14b) supplied by one of the manipulators (20) is added by this manipulator (20) to the billet (12) in the working range (B) of the other manipulator (22).

3. The method according to any of the preceding claims, wherein, when the opera-tion of one of the manipulators (22) is interrupted, another manipulator (20) temporari-ly takes over the tasks of this one manipulator (22).

4. The method according to any of the preceding claims, wherein the laying posi-tion which is closest to the press (16) in longitudinal direction of the billet (12) is ser-viced with priority by at least two manipulators (20, 22).

5. The method according to any of the preceding claims, wherein the transport speed or the stroke rate of the conveyor (10) is so adapted to the cycle time which a single manipulator (20, 22) needs at least for laying a single veneer panel (14), that the time available for laying a single veneer panel is larger than the cycle time.

6. A device for carrying out the method according to any of the preceding claims, comprising a conveyor (10) for supplying a billet (12) of veneer panels to a press (16), and a plurality of manipulators (20, 22) for laying the veneer panels on the conveyor (10), wherein each manipulator (20, 22) has assigned to it a working region (A, B) where the veneer pan-els are added to the billet, and the working regions of the manipulators are arranged in suc-cession along the conveyor (10), characterized in that at least one of the manipulators (20) is configured to feed a veneer panel (14a) location into the working region (B) of another ma-nipulator (22).

7. The device according to claim 6, wherein each manipulator (20, 22) has a cross bar (42) extending in transverse direction of the conveyor (10), a manipulator head (44) being movable along the cross bar, the manipulator head (44) carrying a suction gripper (50) that is movable relative to the manipulator head (44) in longitudinal direc-tion of the conveyor, the cross bars (42) being guided in longitudinal direction of the conveyor in a common guide track (52).

8. The device according to claim 6 or 7, wherein the manipulators (20, 22) are movable in longitudinal direction of the conveyor (10) independently of one another.

9. A device for laying veneer panels (14), in particular according to any of the claims 6 to 8, and the device comprising a suction gripper (50) for attracting the ve-neer panels, characterized in that the suction gripper (50) has a pressing device (52) for pressing the veneer panels away from the suction heads of the suction gripper.

10. The device according to claim 9, wherein the pressing device (52) has a pivot-able pressing arm which, when a veneer panel is taken up, is adapted to be pivoted upwards, by this veneer panel, into a position in which it is attracted and held by suc-tion heads of the suction gripper.

11. The device according to claim 9 or 10, wherein the suction gripper is adapted to be switched between the functions "sucking-in of air" and "blowing-out of air".