Method for dividing a plate-shaped workpiece

Abstract

Method for dividing a plate-shaped workpiece (13) by means of a movable milling tool (21) on a clamping device operated with negative pressure, comprising the following steps: a) placing a plate-shaped workpiece (13) on a support surface (2) of the clamping device provided with a plurality of suction fields (S1 - S12) and generating a negative pressure at all suction fields (S1 - S12) which are completely or partially covered to a certain extent by the workpiece (13); b) separating the plate-shaped workpiece (13) in a first suction field (S12); c) switching off or reducing the negative pressure at the first suction field (S12); d) separating the plate-shaped workpiece (13) in a second suction field (S11), and e) switching off or reducing the negative pressure in the second suction field (S11); f) optionally further steps for successive separation in at least one further suction field (S11 - S1) at which the pressure is subsequently switched off or reduced before the workpiece (13) is separated in a next suction field (S11 - S1), and g) further processing of the separated parts, characterized in that the separation of the plate-shaped workpiece (13) begins in the suction field (S12) which has the greatest distance to a reference point (15) and stop point at which two edges of the workpiece (13) are substantially aligned with two edges of a suction field (S1).

Description

[0001] The present invention relates to a method for dividing a plate-shaped workpiece by means of a movable milling tool on a clamping device operated with negative pressure.

[0002] DE 10 2009 025 817 B4 discloses a device for processing plate-shaped workpieces that can be processed on a belt. For this purpose, sealing strips are provided on the upper side of the belt, forming individual suction fields so that a milling tool can process the plate-shaped workpiece in the area of the individual suction fields. During a cutting process, gaps are created where leakage currents arise, reducing the negative pressure at the individual suction fields and thus also the holding forces. Especially when large-format plates are cut into numerous individual parts, the problem arises that at the end of the cutting process, only low holding forces remain due to the high leakage currents.

[0003] AT 511 536 B1 discloses a machine tool with a vacuum clamping table for securing a plate-shaped workpiece via a movable tool head. The vacuum clamping table is divided into individual sections, each of which is provided with a valve. The valves are coupled to the movement control of the tool head. This is intended to achieve a high negative pressure at the position of the moving tool head. This is intended to increase the holding forces in the area of the tool head. However, the problem of high leakage flows after machining the workpiece remains, which is particularly problematic at the end of machining.

[0004] DE 10 2012 110 453 A1 discloses a method for processing wood-based panels. A recess is first created in the wood-based panel. A drill is then inserted into the recess to create a hole in one of the side walls of the recess. The wood-based panel can then be divided into individual panels, with individual fields on the machine table being able to be switched off.

[0005] It is therefore an object of the present invention to provide a method for dividing a plate-shaped workpiece which can still provide high holding forces even at the end of a machining operation.

[0006] This object is achieved by a method having the features of claim 1.

[0007] In the method according to the invention for dividing a plate-shaped workpiece using a movable milling tool on a clamping device operated with vacuum, a plate-shaped workpiece is first placed on a support surface provided with a plurality of suction fields. Each suction field can be distinguished from a neighboring suction field in that a different pressure can be set at the individual suction fields using valves. For this purpose, each individual suction field can be controlled via a valve, in particular a pneumatic valve with a gate valve. The suction field can then either be activated with a vacuum and is thus connected to the vacuum or vacuum source, or deactivated, which then leads to a disconnection from the vacuum or vacuum source.The suction fields can be separated from one another by sealing strips surrounding the individual suction fields and by suction channels connected to the underside of the support surface. A suction field is thus a specific area on the support surface where a negative pressure can be applied.

[0008] After the plate-shaped workpiece is placed on the workpiece, all suction fields that are either fully or partially covered by the workpiece plate are activated and thus connected to the vacuum source. Once the suction fields are activated, the workpiece is held by the negative pressure with maximum holding force. The cutting process can then begin in the first suction field.

[0009] For the cutting process, the movement of the milling tool can be program-controlled via a control device within the first suction field. After the plate-shaped workpiece has been cut in the first suction field, the negative pressure in the first suction field can be switched off or reduced. The plate-shaped workpiece can then be cut in a second suction field, which is preferably arranged adjacent to or adjacent to the first suction field, before the negative pressure in the second suction field is switched off or reduced. Optionally, a further successive cutting can then take place in at least one further, preferably adjacent, suction field.By separating and subsequently reducing or shutting off the vacuum, the leakage flows in the suction fields already processed are at least reduced. This is because after the separation, the vacuum in one suction field is reduced or shut off, which accordingly reduces or eliminates the leakage flows in that suction field, while high holding forces are provided at the other suction fields with parts that have not yet been separated. This allows a comparatively high vacuum to be maintained at the last suction fields even at the end of a processing or separating process, resulting in high holding forces.

[0010] Preferably, the workpiece is separated in such a way that parts that are only partially positioned in one suction field, in particular less than 15% or less than 10% of the surface, are only processed when separating in another suction field. This ensures that parts that are predominantly arranged with their surface in another suction field are also only processed when the suction field with the predominant surface portion is processed. It is therefore not necessary for all separating cuts that are arranged in one suction field to also be made when processing this suction field. Furthermore, it is possible for a part that completely covers a suction field to only be separated out when processing in other suction fields, i.e. the completely covered suction field is skipped when separating the workpiece.

[0011] The suction fields to be machined are preferably arranged next to one another in rows and / or columns. A corner region of the support surface preferably serves as a reference point and stop point for the workpiece plate. The cutting of the plate-shaped workpiece begins in the suction field that is furthest away from the reference point, at which two edges of the workpiece are essentially aligned with two edges of a suction field. This makes it possible to keep leakage losses to a minimum, since the last suction field is then the suction field adjacent to the reference point, at which two edges of the suction field are essentially aligned with two edges of the workpiece, thus ensuring a seal through sealing strips. The first suction field to be machined is therefore the suction field in a corner region that is diagonally opposite the reference and stop point.This has the advantage that any raw plate dimensions that are smaller than the table and clamping surface mean that suction surfaces that may not be completely covered by the workpiece are machined first, thus reducing the existing leakage area.

[0012] The separation of the workpiece in a suction field is preferably carried out in such a way that, if there are multiple parts that lie entirely within a suction field, the smallest part is separated first, followed by the next largest part. A defined sequence allows the program sequence for separating the individual parts from the plate-shaped workpiece to be fully automated.

[0013] The parts can preferably be machined on four sides when they are cut out of the sheet-like workpiece. Optionally, the workpiece can also be machined on one side, i.e., on five or six sides. Machining can be performed, for example, by drilling holes or by surface finishing.

[0014] The device for dividing a plate-shaped workpiece on a vacuum-operated clamping device comprises a support surface with a plurality of suction fields, a movable separating device, and a switching device for switching the vacuum at the individual suction fields, as well as a control system for the switching device and the movement of the separating device. The control system allows the workpiece to be separated successively in the area of individual suction fields. After the separation in the area of a suction field, this can be switched off via the switching device, or the vacuum can be reduced there, which reduces leakage flows during the separation of the workpiece. Thus, comparatively high holding forces can be provided even at the end of a separation process.

[0015] The control system preferably includes a device for assigning the parts to be separated to the individual suction fields. This allows the workpiece to be divided automatically.

[0016] Preferably, between 4 and 40, in particular 6 to 20, suction fields are provided on the support surface, each of which can be operated with a different negative pressure via the switching device. The suction fields can be essentially the same size.

[0017] In order to distribute the negative pressure evenly across a suction field, a plurality of channels can be provided on the support surface, extending in a grid-like manner within a suction field. Each suction field can optionally be sealed with a gasket that protrudes slightly above the support surface. An air-permeable sacrificial plate can optionally be arranged on the channels of the clamping device, forming the support surface of the clamping device. This allows the sacrificial plate to be replaced if it becomes damaged during dividing the plate or subsequent processing. Optionally, the sacrificial plate can also be omitted, so that the machine table forms the support surface; this can be made of aluminum or a plastic plate, for example.

[0018] The invention will be explained in more detail below using an exemplary embodiment with reference to the accompanying drawings. Fig. 1 a schematic view of a clamping device for a plate-shaped workpiece; Fig. 2 a sectional side view of the clamping device of the Fig. 1; Fig. 3 a view of the clamping device with a workpiece placed on it; Fig. 4 a view of the clamping device with the workpiece with the individual parts assigned to the suction fields; Fig. 5 the clamping device of the Fig. 1 with a modified clamping device, and Fig. 6 a sectional side view of the clamping device of the Fig. 5.

[0019] A device 1 for dividing a plate-shaped workpiece comprises a support surface 2 on which a plurality of suction fields S1 to S12 are provided. The number of suction fields S1 to S12 can be selected depending on the size of the support surface 2 and the subdivision into individual suction fields S1 to S12, with preferably between 6 and 20 suction fields being provided. A suction connection 5 is provided on each suction field S1 to S12, by means of which a negative pressure can be generated at the corresponding suction field S1 to S12. The magnitude of the negative pressure can be changed via a switching device; in particular, the suction connection 5 of a suction field S1 to S12 can be switched off or reduced independently of the negative pressure present at the other suction fields S1 to S12. The negative pressure can, for example, be between 0.01 bar and 0.5 bar and can be provided by a negative pressure or vacuum pump.

[0020] To distribute the negative pressure across a suction field S1 to S12, grooves 6 and transverse grooves 7 extending perpendicularly thereto can be provided on each suction field. These grooves form a grid structure and can create a flat negative pressure within a suction field S1 to S12. The individual suction fields S1 to S12 are separated from one another by sealing strips 9, so that each suction field S1 to S12 can be individually switched or controlled with respect to the applied negative pressure.

[0021] Furthermore, stops 10 or stop elements are provided on the support surface 2, which enable the workpiece to be aligned with the support surface 2. The stops 10 can be designed as bolts, rulers, or other shaped bodies.

[0022] In Fig. 2 is a section through the clamping device of the Fig. 1. The support surface 2 has a suction connection 5, which is connected to the grooves 6 and the transverse grooves 7, which are open at the top. The grooves 6 and transverse grooves 7 as well as the suction connection 5 are arranged in a machine table, wherein sealing strips 9 are provided to divide the machine table 8 into individual suction fields S1 to S12, which sealing strips separate a grid structure in one suction field from a grid structure of an adjacent suction field. On the upper side of the machine table 8, a sacrificial plate 3 made of an air-permeable material, in particular a wood-based material, is provided, which forms a support surface 2 for the plate-shaped workpiece 13.

[0023] The plate-shaped workpiece 13 is preferably made of a wood material and has dimensions of at least 1m by 2m, in particular at least 1.5m by 2.5m, preferably an area of more than 2m 2The thickness of the plate-shaped workpiece 13 can vary between 1 mm and 60 mm, in particular 15 mm to 40 mm. In order to divide the plate-shaped workpiece 13 into individual parts, a separating device 21 in the form of a milling tool is provided, which is movable via a tool head in order to separate the large-format workpiece 13 into individual parts. A finger milling tool is preferably used as the milling tool. The separating device 21 creates joints 20 through which air can flow, as schematically shown by the arrows. The air flows through the joints 20 into the sacrificial plate 3 and from there into the suction connection 5.

[0024] In Fig. Figure 3 shows the clamping device with the support surface 2, on which a plate-shaped workpiece 13 is placed. The plate-shaped workpiece 13 at least partially covers all 12 suction fields S1 to S12. A longitudinal side 12 rests against stops 10, and a transverse side 11 of the plate-shaped workpiece 13 rests against another stop 10, which can optionally also be pneumatically operated. A reference point 15 is provided in the corner area, which serves as the zero point for the allocation of the parts within the raw plate and for subsequent machining of the workpiece 13.

[0025] In Fig. Figure 4 shows the workpiece 13 as it will appear after being divided. The plate-shaped workpiece 13 is divided into 14 parts T1 to T14, each of which can subsequently be further processed into furniture panels. To separate the individual parts T1 to T14 from the large-format workpiece 13, the cutting device 21 is moved and the vacuum is switched on at the suction fields S1 to S12 as follows: The cutting process begins in the suction field S12 which is furthest away from the reference point 15 by a distance 17 and in which the upper right corner area of the workpiece 13 is located in this case. Adjacent to the suction field S12 are two uncovered suction surfaces 16 which are part of the suction field S12 but are not covered by the workpiece 13 because the size of the workpiece 13 does not exactly correspond to the size of the multiple suction fields S1 to S12 in a row or column.

[0026] The cutting device initially moves the tool only around part 14 within the first suction field S12. This separates part T14 from the suction field S12. After all separation processes in the area of the suction field S12 have been completed, the vacuum in this suction field S12 can be reduced or the vacuum can be completely switched off to reduce or prevent leakage. Part T14 is then separated from the suction field S11.

[0027] Subsequently, all suction fields S11 to S1 are machined, starting with those suction fields located in the edge area of the workpiece 13 and directly adjacent to the uncovered suction surface 16. This reduces any leakage caused by the uncovered suction surface 16. The machining sequence is then such that the adjacent suction field is machined, which, with corner point 19, is furthest away from the zero point 15 and borders the uncovered suction surface 16.

[0028] When a part T1 to T14 is separated, it is always completely separated, i.e., separated on all four sides. By specifying the separation fields and the position of parts T1 to T14, as well as the separation rule, according to which if less than 15% or 10% of the area lies in a suction field S1 to S12, the separation process is moved to the next suction field S1 to S12 in which a larger area of a part T1 to T14 is present. Therefore, for example, part T2 is also separated in suction field S1 because it is located with an area of more than 15% in suction field S1.

[0029] After the suction field S12, the plate-shaped workpiece 13 is cut in the suction field S11. After processing within the suction field S11, the suction field is shut down or the vacuum is reduced, so that processing can then be carried out in the suction field S10. These steps are repeated successively until processing in the last suction field S1 is completed.

[0030] When separating the workpiece 13 into individual parts T1 to T14, a program-controlled movement of the separating device 21 can take place in such a way that parts that completely cover a suction field are skipped during processing or are only switched off at the very end of the separating process.

[0031] The sequence of parts T1 to T14 being processed in a suction field S1 to S12 can be configured depending on their size and area. Preferably, the parts are sorted from small to large, meaning that small parts are removed first before the next larger part is removed.

[0032] In addition, there are numerous parts that are not entirely assigned to a suction field S1 to S12, but are arranged across multiple suction fields S1 to S12. Then, the common area with the respective suction field S1 to S12 can be determined. If this area does not exceed a certain size that can be set in the programming system, for example, 100 cm 2 , or 10% of the total area of the part, this part is ignored during the cutting process. The respective part can then only be processed when one of the next suction fields is processed. For example, part T9 can be ignored when processing in suction field S1 because the overlap with suction field S1 is small. Part T9 is then only cut out when processing takes place in suction field S5. The setting as of which overlap with a suction field S1 to S12 separation occurs is preferably adjustable.

[0033] The parts T1 to T14 thus separated can be removed from the support surface 2 after division and further processed. The utilization rate of the clamping device can be increased by machining individual parts T1 to T14 with milling tools, drills, or other tools in order to be able to perform five-sided and, if necessary, six-sided machining.

[0034] In Fig. Figure 5 shows a modified embodiment of a clamping device, which is designed as in the previous embodiment, with additional suction clamping elements 23 being provided, which can fix the individual parts T1 after they have been divided. These suction clamping elements 23 can be arranged on the sacrificial plate 3, as shown in Fig.6. As a result, part T1 is positioned at an elevated position and can also be machined on the underside by a milling head 22, for example, to produce a recess or a groove. The elevated position of part T1 enables six-sided machining.

[0035] In the illustrated embodiment, a sacrificial plate 3 is provided in each case, forming a support surface. Another design of the clamping surface can have a perforated plate instead of the grid-grooved plate, in which the vacuum is guided and distributed in a suction box. A clamping surface can also be designed as a perforated plate provided with a plurality of openings and arranged below the suction box. The negative pressure in the suction boxes can be controlled individually for each suction field.

[0036] In the illustrated embodiment, the workpiece is a wood-based panel. The machine can also be used for applications other than woodworking, for example, for processing plastic or aluminum panels. List of reference symbols 1 device 2 support surface 3 sacrificial plate 5 Suction connection 6 grooves 7 Cross groove 8 Machine table 9 Sealing strip 10 stops 11 short side 12 Long side 13 Workpiece 15 Reference point 16 Uncovered suction surface 17 Distance from reference point 19 Corner point of a workpiece 20 Fugue 21 Separating device 22 milling head 23 Suction clamping element S1 - S12 suction field T1 - T14 part

Claims

[1] Method for dividing a plate-shaped workpiece (13) by means of a movable milling tool (21) on a clamping device operated with negative pressure, comprising the following steps: a) placing a plate-shaped workpiece (13) on a support surface (2) of the clamping device provided with a plurality of suction fields (S1 - S12) and generating a negative pressure at all suction fields (S1 - S12) which are completely or partially covered to a certain extent by the workpiece (13); b) separating the plate-shaped workpiece (13) in a first suction field (S12); c) switching off or reducing the negative pressure at the first suction field (S12); d) separating the plate-shaped workpiece (13) in a second suction field (S11), and e) switching off or reducing the negative pressure in the second suction field (S11); f) optionally further steps for successive separation in at least one further suction field (S11 - S1) at which the pressure is subsequently switched off or reduced before the workpiece (13) is separated in a next suction field (S11 - S1), and g) further processing of the separated parts, characterized by that the separation of the plate-shaped workpiece (13) begins in the suction field (S12) which has the greatest distance to a reference point (15) and stop point at which two edges of the workpiece (13) are substantially aligned with two edges of a suction field (S1). [2] Method according to claim 1, characterized by that the separation of the workpiece (13) takes place in such a way that parts (T1 - T14) which are only positioned to a small extent in a suction field (S1 - S12), in particular less than 15%, preferably less than 10% of their area, are only processed during separation at another suction field (S1 - S12). [3] Method according to claim 1 or 2, characterized by that a control system assigns the parts to be separated to the suction fields, and if a part (T12) completely covers a suction field (S7), the suction field (S7) is skipped during processing without separating the workpiece (13). [4] Method according to one of the preceding claims, characterized by that the first suction field (S12) is separated in a corner area of the support surface (2). [5] Method according to one of the preceding claims, characterized by that the separation of the workpiece (13) takes place in such a way that, in the case of several parts (T1 - T14) which lie completely in a suction field (S1 - S12), the smallest part is separated out first and then the next largest part in this suction field is separated out. [6] Method according to one of the preceding claims, characterized bythat the workpiece or the cut-out parts are machined by tools on at least 5 sides, preferably on 6 sides.

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