TECHNICAL FIELD

The invention concerns in general the technical field of a manufacturing of wood products. More particularly, the invention concerns a repairing of ply- wood products.

BACKGROUND

Manufacturing of plywood is a process comprising of a plurality of stages. In a big picture main stages are a preparation of veneer sheets from logs, prepara- tion of plywood from the veneer sheets and a finalization of the plywood. The finalization of the plywood comprises a repairing phase in which a quality of the plywood is inspected and necessary measures to repair defects found dur- ing the inspection are taken. Some non-limiting examples of the defects are knots, knot holes, cracks, splits, color deviations and similar. In prior art solutions the repair of the plywood panels is performed in a produc- tion line type repairing solution. There, the plywood panels are brought with a conveyor line to an inspection device which may e.g. scan the plywood panel in question, analyzes the scanned data and generates a repair command to at least one repair tool. The repair tool(s) performs an applicable repair operation to the defect of the plywood panel when the panel under repair advances in the production line and when the repair is performed the plywood panels may be collected at stacks at the end of the production i.e. repair line. This kind of approach is taken in a prior art document US 4984172.

The drawback of the prior art solutions as described above is that the repairing lines according to prior art are expensive to acquire, but also expensive to use especially if all costs are taken into account. Part of the costs incur due to a need of a large floor area needed for establishing the repairing line. Moreover, an installation of the repairing line is difficult and challenging. Hence, there is need to develop alternative solutions for establishing the repairing of the wood panels which mitigate at least in part the above described drawbacks.

SUMMARY

The following presents a simplified summary in order to provide basic under- standing of some aspects of various invention embodiments. The summary is not an extensive overview of the invention. It is neither intended to identify key or critical elements of the invention nor to delineate the scope of the invention. The following summary merely presents some concepts of the invention in a simplified form as a prelude to a more detailed description of exemplifying em- bodiments of the invention.

An objective of the invention is to present a system and a method for repairing at least one plywood panel.

The objectives of the invention are reached by a system and a method as de- fined by the respective independent claims. According to a first aspect, a system for repairing at least one plywood panel is provided, the system comprising: an input section for inputting plywood panels in the system, an output section for outputting the plywood panels from the system, wherein at least one of the following: the input section, the output sec- tion comprises a support structure for a stack of the plywood panels; the sys- tern further comprising: a detection device for scanning a plywood panel in the system; a repairing device for performing a repair operation for the plywood panel; a transport device for transporting a plywood panel from the input sec- tion to the output section; and a control device for generating a control signal to the repairing device in response to a detection of a defect in the plywood panel on the basis of information obtained with the detection device.

The detection device may be arranged to scan the plywood panel in at least one of the following: in the input section, in the output section. The detection device may be arranged to scan the plywood panel residing at topmost or at bottommost in the stack of the plywood panels.

The detection device may also be arranged to move at least in part over the plywood panel under scanning. Alternatively or in addition, the repairing device may be arranged to perform the repair operation in at least one of the following: in the input section, in the output section.

The repairing device may also be arranged to perform the repair operation to the plywood panel residing at topmost or at bottommost in the stack of the plywood panels.

The repairing device may further be configured to perform the repair operation to the plywood panel at a same position as it is scanned with the detection de- vice.

The transport device may be arranged to travel between the input section and the output selection along rails arranged in a frame structure of the system.

For example, the transport device may comprise a plurality of gripping devices for gripping the plywood panel under transport.

The system may further comprise a holder device for holding the plywood pan- el. Still further, the system may further comprise a hoisting apparatus for adjusting a position of the plywood panel in the system.

Alternatively or in addition, the system may further comprise a conveyor device for conveying a stack of plywood panels to the input section of the system.

The system may further comprise a conveyor device for conveying a stack of plywood panels from the output section of the system. According to a second aspect, a method for repairing at least one plywood panel is provided, the method comprising: receiving, in an input section of a system, a plurality of plywood panels; transporting the plywood panels, one by one, from the input section to an output section; scanning, by a detection de- vice, a plywood panel in the system; performing, by a repairing device, a repair operation to the plywood panel in response to a receipt of a control signal from a control device configured to generate the control signal to the repairing de- vice in response to a detection of a defect in the plywood panel on the basis of information obtained with the detection device; wherein the method further comprising: handling the plurality of the plywood panels as a stack with a sup- port structure in at least one of the following: the input section of the system, the output section of the system.

The expression "a number of refers herein to any positive integer starting from one, e.g. to one, two, or three.

The expression "a plurality of refers herein to any positive integer starting from two, e.g. to two, three, or four.

Various exemplifying and non-limiting embodiments of the invention both as to constructions and to methods of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific exemplifying and non-limiting embodiments when read in connection with the accompanying drawings.

The verbs“to comprise” and“to include” are used in this document as open limitations that neither exclude nor require the existence of unrecited features. The features recited in dependent claims are mutually freely combinable un- less otherwise explicitly stated. Furthermore, it is to be understood that the use of“a” or“an”, i.e. a singular form, throughout this document does not exclude a plurality.

BRIEF DESCRIPTION OF FIGURES

The embodiments of the invention are illustrated by way of example, and not by way of limitation, in the figures of the accompanying drawings. Figure 1 illustrates schematically a plywood panel repairing system according to an embodiment of the invention.

Figures 2A and 2B illustrate schematically another embodiment of the inven- tion.

Figures 3A and 3B illustrate schematically a still further embodiment of the in- vention.

DESCRIPTION OF THE EXEMPLIFYING EMBODIMENTS

The specific examples provided in the description given below should not be construed as limiting the scope and/or the applicability of the appended claims. Lists and groups of examples provided in the description given below are not exhaustive unless otherwise explicitly stated.

Figure 1 illustrates schematically a plywood panel repairing system according to an embodiment of the invention. The plywood panel repairing system may refer to an entity comprising necessary devices for determining if a plywood panel input to the system comprises a predetermined defect and necessary devices for performing at least one repair operation to the plywood panel in case there is determined one or more predetermined defects. The system comprises at least two sections: input section (referred with symbol A in Figure 1 ) and output section (referred with symbol B in Figure 1 ). The plywood panels are transported between the sections A, B typically from the input section A to the output section B. The system according to an embodiment of the invention may comprise a frame structure 110 into which at least part of the devices be- longing to system as will be described may be mounted either in a fixed man- ner or movably. In the non-limiting example of the repairing system as sche- matically illustrated in Figure 1 the input section is arranged to be the side in which the repair of the plywood panel may be performed. The repairing of the plywood panel may require that the repairing system comprises a detection device 120 by means of which the plywood panel under repair may be scanned and by analyzing the data obtained by the scanning it may be deter- mined if a repair operation shall be done with respect to the plywood panel in question. A non-limiting example of an applicable detection device 120 may be an image capturing device, such as a camera, or a laser profile sensor. The detection device 120 may be movably arranged in the frame structure 110 so that it may be arranged to travel over a plywood panel under scanning for ob- taining necessary information on the plywood panel. For example, in the non- limiting example as depicted in Figure 1 the detection device 120 may be ar- ranged to travel over the input section A. Furthermore, the system may corn- prise at least one repairing device 130 i.e. the tool by means of which the de- tected defect may be repaired. The repairing device 130 may e.g. comprise a tool for mechanically modifying the detected defect as well as a tool for input- ting a substance to the defect or the modified defect. For example, the repair- ing device 130 may be a puttying device. In other words the repairing system may be configured to operate so that in the input section the plywood panel under repair is scanned with the detection device 120 and the data generated by scanning is analyzed. In response to a detection that there is a predeter- mined defect in the plywood panel, a control signal may be generated to the repairing device 130 for performing the repair operation. The overall control of the repairing system, and, hence, a control of the scanning operation, the analysis and the control of the repairing device 130, may be executed by a control device 140, which may be communicatively, and operatively, coupled to the other entities belonging to the system. The communication between the entities and the control device 140 may be implemented either in a wired man- ner or wirelessly by applying known communication technologies, for example. Still further, in some embodiment the repairing system may comprise one or more holding devices 150 by means of which the plywood panel under repair may be held in place. This is important when the scanning operation is per- formed but also when the control signal for the repairing device 130 is gener- ated in order to achieve the repairing device 130 to perform the repair opera- tion in a correct position of the plywood panel. Moreover, holding the plywood panel in place with the holding device or devices may be necessary during the repair operation. Advantageously both the scanning operation and the repair operation are performed to plywood panel so that the panel remains exactly at the same position during these both operations. Alternatively or in addition, it may be arranged that the system is configured to monitor if the plywood panel moves between the scanning operation and the repair operation and to deter- mine an amount of the motion. In this manner it is possible to take into account the change in position for the generation of the control signals to the repairing device 130. A measurement of the change in position may be performed with any applicable measurement device or system. A non-limiting example of an applicable holding device 150 may be a press foot, which may be arranged to hold the plywood panel under repair under control of the control device 150 and to release the plywood panel e.g. when the repair operation is ready. Still further, the plywood panel repairing system may comprise a transport device 160 for transporting a plywood panel between the input section A and the out- put section B. In the implementation of the system as schematically illustrated in Figure 1 the transport device 160 may be implemented with a device having a plurality of gripping devices by means of which the plywood panel to be transported may be gripped. The gripper devices may be such that they may move in a vertical direction for reaching the plywood panel and have means, such as vacuum suction or vacuum cup, to grip the object in question. Moreo- ver, the implementation of the transport device 160 may be based on rails mounted on the frame structure 110 along which rails the transport device 160 may be caused to travel. The transport device 160 comprises a motion genera- tion device, such as an electric motor, for generating a force causing the mo- tion of the transport device 160 for achieving the transport of the plywood pan- el. In other words, the transport device 160 may be controlled to transport a plywood panel between the input section A and the output section B, typically from the input section A to the output section B and release the transported plywood panel there.

The system according to the present invention allows a processing of the ply- wood panels in a stack at least in one section A, B of the system. In other words the system may be arranged so that it may be configured to receive the plywood panels to be repaired if necessary in a stack 180 in the input section, as illustrated in Figure 1 as a non-limiting example. Flence, the system may be configured to, in the embodiment of Figure 1 , repair the topmost plywood panel in the stack of the plywood panels. Here, the stack refers to a pile comprising a plurality of the plywood panels. When the repair, comprising at least the scan- ning phase and the repair phase, is ready, the transport device 160 may be configured to transport the topmost panel from the input section A to the output section B. The scanning of the next plywood panel in the stack 180 may be ini tiated so that the scanning may be synchronized at least in part concurrently with the transport or it may be initiated when the repaired plywood panel re- sides in the output section. In the embodiment of Figure 1 the plywood panels transported to the output section B may be received by a support structure thus forming a stack from the plywood panels gone through the repair. The support structure may refer to a platform, such as a scissor lift, or to dedicated rack for collecting the plywood panels as non-limiting examples.

The system according to the embodiment of Figure 1 may comprise further en- tities, such as one or more conveyor devices 200, by means of which the ply- wood panels may be conveyed to and from the system. A non-limiting example of an applicable conveyor device 200 may be a chain conveyor as schemati- cally illustrated in Figure 1. The plywood panels may be transported at least in one direction (i.e. either to the system or from the system or both) in a stack as illustrated in the non-limiting example according to Figure 1. Moreover, the sys- tem may further comprise one or more hoisting devices 210 in either the input section or in the output section. The hoisting machines may be configured to receive the plywood panel or the stack of the plywood panels and adjust a height of it at least in vertical direction so that the repair operation as described may be performed. In other words, the height may be adjusted so that the scanning and the repair operation may be performed. Moreover, the adjust- ment of height may be controlled so that the height is adjusted continuously in response to a change of height of the stack. In other words, an upper layer of the stack may be maintained approximately at the same level. In order to achieve this, there may be arranged sensors e.g. in the frame structure for ob- taining data from which the level of the upper surface of the stack of plywood panels may be determined. In the embodiment of the invention as schematically illustrated in Figure 1 the repair i.e. the scanning operation and the repair operation are arranged in the input section of the repair system. However, the present invention may also be implemented so that the scanning and the repair, and, thus, the detection de- vice 120 and the repairing device 130 may be arranged in the output section of the system. In such an embodiment the plywood panel may be conveyed from the input section to the output section wherein the repair is performed by per- forming the scanning operation and the repair operation as described. Natural- ly, necessary holding devices may be arranged in the output section. In the embodiment, the plywood panels may be collected at the output section in a stack for transporting the plywood panels in a stack out from the system. Moreover, the input section may be implemented in a similar way as in the embodiment of Figure 1 in which the plywood panels to be repaired are brought in a stack to the system. Alternatively, it may be arranged that the ply- wood panels are input to the system with a conveyor device so that the transport device of the system grips the input plywood panel and conveys it to the output section for repair.

The input of the stack of plywood panels 180 in the embodiment of Figure 1 is arranged underneath an operational level of the system i.e. the level where the devices involved in the repair are operable. In the embodiment the height may be adjusted with the hoisting device 180. According to another embodiment the input of the plywood panels for repair may also arranged so that plywood panels are input above the operational level of the system e.g. in such a man- ner that the stack of plywood panels are hoisted above the operational level and the bottommost plywood panel is taken for repair. In such an embodiment the scanning device 120 as well as the repairing device 130 may be positioned so that they may perform the scanning operation as well as the repair opera- tion to the bottommost plywood panel in the stack. For example, the position- ing may be implemented so that they are upside down with respect to the em- bodiment of Figure 1. A structure of the hoisting device 210 may advanta- geously be such that the stack of plywood panels, and especially their bottom surface is accessible by the devices being involved in the repair. Furthermore, the transport device 170 may be implemented so that it may release the bot- tommost plywood panel from the stack 180 and to transport it to the output section. Similarly, if the system is implemented so that the repair is to be done in the output section, the necessary devices, such as 120 and 130, may be positioned there in the same manner as described above in order to repair the bottommost plywood panel collected therein. In such an embodiment the out- put section is configured so that there is arranged a hoisting machine which adjusts a height of the plywood panel residing in the support structure in the output section so that the transported plywood panel may be positioned as the bottommost plywood panel in the stack in the output section.

In the embodiment as illustrated in Figure 1 the conveyor devices 200 are ar- ranged to convey the stack of plywood panels 180 from the side of the system i.e. a direction of the motion of the conveyor devices 200 is transversal to a di- rection of the motion of the transport device 160 of the system. However, the present invention is not only limited to such an arrangement but at least one conveyor device 200 may be arranged to convey the stack of the plywood panels to or from the system from the end of the frame structure 110. Then, the directions of the motions of the conveyor device 200 and the transport de- vice 160 are parallel to each other. As already mentioned the present invention may be applied in a plurality of implementations of the repair system. A further example on the implementation is schematically illustrated in Figures 2A and 2B which illustrate an embodiment of the invention from two perspectives. Fig- ure 2A illustrates a side view of the embodiment whereas Figure 2B provides a bird-eye view to the same embodiment. The embodiment as schematically il- lustrated is such that the repair is performed in the first section A. The plywood panels may be input as a stack 180 conveyed to a hoisting device 210 with a conveyor device 200 wherein the topmost plywood panel is scanned with a de- tection device 120 and a repairing operation, if any, is performed with repairing device 130. In response to the repair the plywood panel is transported to the output section B with a transport device 160 configured to move along the frame structure 110 of the system. In the embodiment as schematically illus trated in Figures 2A and 2B the repaired plywood panels are taken out from the system with a second conveyor device 220. Hence, the transport device 160 may be configured to transport the plywood panel in question from the in- put section A to the output section B and release the plywood panel in the out- put section so that it lays down to the conveyor device 220, e.g. on a belt of the conveyor device 220.

In Figures 3A and 3B are schematically illustrated such an embodiment in which the scanning and repairing operations are performed in the output sec- tion B. As schematically illustrated in Figures 3A and 3B the plywood panel under repair may be held above a stack of plywood panels already entered to the output section B and gone through the repair. In other words, the repair may be performed when the plywood panel under repair is held above the stack and in response the repair is finalized the plywood panel in question is laid to the stack as the topmost plywood panel. This kind of arrangement has an advantage that it is possible to arrange time for a substance used in the re- pair of the previous plywood panel to set, such as to dry, before the next ply- wood panel is positioned on top of it. In the embodiments as disclosed in Fig- ures 3A and 3B the output of the plywood panels from the system is thus per- formed in a stack. The same arrangement may be done with a system in which the plywood panels are output from the system with a conveyor device (cf. Figure 2A and 2B). In such an embodiment the conveyor device is stopped so that the scanning and the repairing operations may be performed to a halted plywood panel.

In some embodiment the repair shall be performed on both sides of a plywood panel in question. In order to achieve this the system may further comprise a stack rotation device, which may be configured to receive the stack of the re- paired plywood panels as an input, which stack is turned around and the turned around stack of the plywood panels may be input to the input section for repairing.

The system as described above may, thus, be configured to perform a method for repairing at least one plywood panel in which method in which a plurality of plywood panels is received in an input section A of a system. The plurality of the plywood panels may e.g. be received as a stack or via a conveyor device one by one. In the method, the plywood panels may be transported, one by one, from the input section A to an output section B. Moreover, in the method at least one plywood panel, typically all the plywood panels entering the sys- tem, may be scanned with a detection device 120 in the system and a repair operation may be performed, with a repairing device 130, to a plywood panel in response to a receipt of a control signal from a control device 140, which is configured to generate the control signal to the repairing device 120 in re- sponse to a detection of a defect in the plywood panel. The detection of the defect may be performed on the basis of information obtained with the detec- tion device 120 e.g. through analyzing the obtained information. The method further comprises that the plurality of plywood panels is handled as a stack in at least one of the following: the input section (A) of the system, the output section (B) of the system. The handling of the plywood panels as the stack may e.g. refer to that the panels enter the system in the stack wherein at least some on the mentioned steps are performed to the plywood panels. Alterna- tively or in addition, the stack may be established in the output section e.g. by utilizing a support structure therein. For sake of clarity the steps disclosed in the method may be performed either in the input section A or in the output sec- tion B. Hence, the mutual order of the repair, the transport and the handling in stack is not strictly limited by the present invention. Further aspects relating to the method may have been described in the description of the system.

As becomes clear from the description above the present invention relates to a system by means of which it is possible to repair plywood panels. The repair comprises at least a detection operation and a repairing operation. The system is based on an inventive idea that in at least one section of the system, where- in the section refers to a sub-part of the whole system, the plywood panels un- der repair are handled in a stack of plywood panels. The section may either be an input section or an output section, wherein the plywood panels are trans- ported between the mentioned sections. The system comprises necessary en- tities, such as devices and/or functionalities to perform the repairing. Even if the entity configured to perform the repairing is called as a system in the de- scription herein it may also be understood as a device comprising necessary elements and entities, as described, for performing the repairing of the ply- wood panels.

The specific examples provided in the description given above should not be construed as limiting the applicability and/or the interpretation of the appended claims. Lists and groups of examples provided in the description given above are not exhaustive unless otherwise explicitly stated.