CN112739487B

CN112739487B - Machine tool for machining workpieces

Info

Publication number: CN112739487B
Application number: CN201980059093.6A
Authority: CN
Inventors: S·奥肯富斯; M·彼得拉; W·蒂尔; P·特鲁克塞斯; D·特伦克莱因
Original assignee: Trumpf European Ag
Current assignee: Trumpf European Ag
Priority date: 2018-09-10
Filing date: 2019-07-25
Publication date: 2024-01-09
Anticipated expiration: 2039-07-25
Also published as: WO2020052848A1; CN112739487A; DE102018121968A1

Abstract

The invention relates to a machine tool for machining workpieces, comprising a workpiece carrier, a holding device, a beam capture device, a laser machining device and a first and a second die that delimit an opening of the beam capture device, wherein the workpiece carrier has a first and a second workpiece carrier surface, the holding device clamps at least one workpiece and can move the workpiece relative to the first and the second workpiece carrier surface by means of the holding device, the beam capture device is arranged between the first workpiece carrier surface and the second workpiece carrier surface and extends at least partially with an opening between the first workpiece carrier surface and the second workpiece carrier surface, the laser machining device has a laser machining head that can be moved over the opening of the beam capture device, and a pressing element oriented in the direction of the die of the pressing device is arranged over one of the two dies, wherein the pressing element can be set at least in terms of the distance relative to the carrier surface of the die.

Description

Machine tool for machining workpieces

Technical Field

The invention relates to a machine tool for machining workpieces, in particular plate-shaped workpieces, having a workpiece support, which has a first workpiece support surface and a second workpiece support surface, having a holding device which holds at least one workpiece and moves the workpiece relative to the first and second workpiece support surfaces at least in and against the X-direction, having a beam capture device which is arranged between the first and second workpiece support surfaces, having a laser cutting head which can be moved above the beam capture device at least in the Y-direction, and having a laser machining device which delimits an opening of the beam capture device.

Background

A machine tool for machining plate-shaped workpieces is known from DE 1020116118175 A1. The machine tool also has a punching tool for additionally machining the plate-shaped workpiece.

Furthermore, a machine tool with a punching device and a laser processing device is known from EP 3219429 A1. The laser processing device comprises a laser cutting head, by means of which a laser beam is directed onto a workpiece positioned on a workpiece carrier in the direction of a beam capturing device. In order to shield the machining region of the laser machining beam on the workpiece, a shielding device is provided, which is fastened to the laser machining head. The shielding means comprises an annular or rectangular frame extending around the laser cutting head. The shielding device can also include a hold-down function to prevent the sheet material from rocking during the movement along the plane of the workpiece carrier.

Furthermore, EP 0734304 B1 provides a laser processing device for cutting or welding workpieces. The laser processing device comprises a laser processing head which is surrounded by a substantially fork-shaped or ring-shaped pressing element and is preferably arranged centrally therein. For welding the workpiece, the pressing element is actively pressed against the workpiece. For this purpose, a drive is provided adjacent to the laser cutting head. The cutting of the workpiece, in particular the separation of the parts from the remaining grid, is not possible with such a welding device.

A method for removing a workpiece part, which is formed by separating a plate-like workpiece placed on a workpiece carrier of a workpiece machine, is known from EP 2177493 A1. An annular die with a suction device is arranged in the workpiece carrier. After machining the workpiece, a suction clamp with a vacuum inhaler is positioned relative to the workpiece portion so that the workpiece portion is sucked and can be lifted upwards.

From the company publication "trumate" by the general machine tool company: stanzen und Lasern perfekt kombiniert (document number 0372731_201410_f, month 10 of 2014) is a machine tool for machining plate-like workpieces. The machine tool includes a press working device and a laser working device. The laser processing apparatus has a cutting head that is movable over an opening of the beam capturing device. A shielding device is arranged on the laser processing head, which shielding device has an angled frame, on which a large number of bristles are arranged in the direction towards the workpiece support in order to shield the processing area outwards. The bristles are positioned at a greater distance relative to the laser processing head.

DE 102008041774 A1 discloses a device for laser welding, in particular laser micro-welding, a first workpiece and a second workpiece. The laser processing head comprises a holding part and a pressing element which is connected to the holding element on one side by an actuator element in a movable manner. The opposite side of the pressing element is placed on the second workpiece without play by the actuating element. The second workpiece is placed on the first workpiece. The two workpieces are irradiated and welded with a laser beam that passes through a through-hole in the interior of the hold-down element.

A machine tool with a melt cutting device comprising a nozzle on a laser cutting head is known from DE 2933700 A1. The laser cutting head is provided with a pressing mechanism, and the lower side surface of the pressing mechanism is provided with a ball, wherein the pressing mechanism always keeps the nozzle and the converging lens of the laser processing head at the same distance from the surface of the workpiece.

Disclosure of Invention

The object of the present invention is to provide a machine tool for machining workpieces, in particular plate-shaped workpieces, by means of which workpieces, in particular parts, are machined with a laser beam and a high process reliability is achieved.

This object is achieved by a machine tool for machining workpieces, wherein a pressing element of a pressing device, which is oriented in the direction of the mold and can be set at least in terms of the distance from the support surface of the mold, is arranged above one or both molds. The pressing element, which is oriented toward the mold and is directly assigned to the opening of the beam-capturing device, prevents tilting of the workpiece, in particular of the component. Such tipping of the part can be caused by the cutting gas pressure during the machining of the workpiece by means of the laser beam. Such tipping of parts can cause malfunctions in the processing machine. Parts may also be undesirably ejected through the opening of the beam capturing device due to the cutting gas pressure during laser machining. By positioning the pressing element immediately above one and/or both dies, the pressing force can act on the part, so that undesired tilting is reduced or prevented and the process reliability is improved.

Preferably, the pressing element is elongate and is oriented parallel to the opening of the beam capturing device. Only the pressing function of the pressing element, without an additional shielding function of the machining point, is sufficient to increase the process reliability.

The pressing element can have a length equal to or greater than the diameter of the laser cutting head. The pressing element can also extend only partially along the length of the mould or completely along the length of the mould. Pressing elements protruding beyond the ends of the mould are also possible.

A preferred embodiment of the machine tool provides that one or both of the dies can be lowered and/or can be tilted relative to the plane of the workpiece carrier (abklapp bar). In this way, the remaining components and/or workpieces, in particular parts, can be removed simply and quickly. One embodiment provides that one of the two molds is arranged stationary relative to the opening of the beam capture device, while the opposing mold can be lowered and/or can be tilted. A sinking and/or folding mold can be provided on the part shutter.

The pressing element can be adjusted to a distance which is smaller than the thickness of the workpiece to be processed, preferably above the tool which can be folded and/or lowered. In this way, a sufficient pressing force can be achieved which is applied by the pressing element to the workpiece in order to remain against the tool during processing.

A further preferred embodiment of the machine tool provides that the pressing element has a pressing surface acting on the workpiece to be machined and is oriented with a longitudinal edge of the pressing surface parallel to the opening of the beam capture device. This enables the hold-down element to be arranged in the vicinity of the opening of the beam capture device and at the same time enables undisturbed processing of the laser cutting head. Thereby, it is also possible to reliably hold parts whose dimensions extend, for example, from the receiving plane of the mould to the centre of the opening of the beam capturing device.

The mold preferably has a mold edge which points toward the opening of the beam capture device and which is countersunk relative to a support surface of the mold, which surface is arranged in the support plane, in the direction of the beam capture device, wherein a bevel extends between the support surface of the mold and the mold edge. The ramp enables a simple discharge of the scrap portion through the opening of the beam capturing device and prevents the sagging sheet metal part from colliding during its moving movement. A longitudinal edge on the mould is formed between the inclined surface and the bearing surface. The longitudinal edges of the pressing surfaces of the pressing elements can be oriented parallel to or assigned to the longitudinal edges. In this way, a minimum distance between the pressing element and the machining point of the laser cutting head is achieved, so that also dimensionally small workpieces or components are fastened in a contact manner to the support surface of the die. The compression surface can also extend beyond the die in a direction away from the opening of the beam capturing device.

Alternatively, the bearing surface of the mould can be formed by balls, rollers, bearing plates or by brushes. The longitudinal edges of the pressing surfaces of the pressing elements are aligned with or are retracted relative to the highest point of the ball or roller in the direction of the workpiece receiving section. In this alternative configuration of the mould, the same advantages as in the case of a strip-shaped mould can be achieved.

According to a preferred embodiment of the pressing device, the pressing device has a holder for fastening the pressing element to the laser cutting head. This configuration has the following advantages: the hold-down element is moved along the opening of the beam capturing device simultaneously with the laser processing head so that a hold-down function is provided directly during the cutting process. Alternatively, it can be provided that the laser processing head is surrounded by a shielding device, and that the pressing device is arranged in the shielding device and fastened to the shielding device or the laser processing head. Such a shielding device forms a closed curtain, in particular consisting of brushes which surround the laser processing head at a large distance. The part cannot thereby be fixed and positioned relative to the mold. For this purpose, a pressing element is additionally provided in the shielding device and adjacent to the laser processing head.

An alternative embodiment of the pressing device provides a holder for fastening the pressing element to the die or to a workpiece support section adjoining the die or to the frame of the machine tool. In this configuration, the pressing element preferably extends completely along the entire length of the mold. Thus, the hold-down element is positioned on one side with respect to the opening of the beam capturing device.

Another alternative embodiment of the pressing device provides a holder for fastening the pressing element to an operating device which is fastened to the machine frame or is located separately from the machine frame. The handling device can comprise one or more gripping elements, for example realized by means of a vacuum inhaler, in order to handle the work piece. The holding-down device can additionally be attached to the operating device.

The positioning of the pressing device can be achieved by means of the shaft of the operating device. This results in a greater degree of freedom in all axial directions.

In a further preferred embodiment of the machine tool, the pressing element can be set and/or can be adjusted in terms of orientation and/or height relative to one or both dies by means of a positioning device or an operating device. The positioning device enables the pressing element to be moved in height relative to the die in order to adapt the pressing element to different material thicknesses of the workpiece to be processed. The positioning means are also able to perform a change of the position of the pressing element along the mould. Such a positioning device is preferably gripped on the holding part. The positioning device can additionally be gripped on the frame of the machine tool and/or in the region adjoining the workpiece support.

Alternatively, provision can be made for the pressing element to be received by the actuating device. This has the following advantages in particular: application-specific activation can be achieved such that, for example, the pressing element is positioned relative to the mold as soon as the part is machined. In the case of further processing, the pressing device can be completely removed from the working area. This also serves to prevent premature wear. The positioning device can also achieve the same function. The positioning device and the actuating device can each be configured to pivot the pressing element into an effective operating position in which the pressing element is oriented toward the mold.

The pressing element is preferably constructed from an indivisible and/or heat-resistant and/or electrically non-conductive and/or low-wear and/or flexible material.

Another preferred embodiment of the pressing device provides the pressing element as an elongated brush element, which comprises a plurality of brushes, in particular aramid brushes, and the free ends of which together form the pressing surface. These brushes are particularly suitable because they form an adequate screen in the case of a side-by-side arrangement on the one hand and on the other hand enable a force transmission to apply a pressing force to a workpiece or part.

Drawings

The invention and further advantageous embodiments and improvements of the invention are further described and illustrated below by way of example in the figures. The features which are evident from the description and the drawings can be used according to the invention individually or in any combination of several. The drawings show:

figure 1 shows a perspective view of a machine tool for machining a plate-like workpiece,

figure 2 shows a schematic cross-section of the exit beam capturing device and the pressing means on the laser cutting head,

figure 3 shows a schematic cross-sectional view of an alternative embodiment of figure 2,

figure 4 shows a schematic cross-sectional view of another alternative embodiment of figure 2,

figure 5 shows a perspective view of an alternative embodiment of the hold-down device on the shielding device,

figure 6 shows a schematic cross-section of an alternative embodiment of a beam capturing device with a hold-down device according to figure 5,

figure 7 shows a perspective view of another alternative embodiment of the compacting apparatus,

figure 8 shows a schematic side view of the pressing device according to figure 7 with a positioning device,

fig. 9 shows a perspective view of the operating device with the pressing device arranged thereon.

Detailed Description

In fig. 1, a machine tool 11 is shown in perspective. The machine tool 11 is, for example, a hybrid machine tool. The hybrid machine tool 11 enables both laser processing and press processing of a plate-like workpiece. Alternatively, the machine tool 11 can also be just a laser cutting machine tool. The machine tool 11 has a closed base 14, in particular a circumferential frame, which preferably extends in the Y direction. A workpiece carrier 16 extending in the X-direction traverses the frame 14. The workpiece carrier 16 is provided with a holding device 17 having holding elements 18, 19. The holding elements 18, 19 are preferably designed as clips or clamping jaws. The cut workpiece 34, which is preferably embodied as a plate-shaped workpiece, can be held by the holding elements 18, 19 and moved, for example, in the X direction of the workpiece plane (X/Y plane). For machining the plate-shaped workpiece 34, the laser machining head 20 and/or the press machining head 21 can be actuated in a manner that can be moved along the Y-axis within the frame 14. For this purpose, linear drives which can be actuated independently of one another and are not shown in detail are provided for the laser processing head 20 and the stamping processing head 21, respectively.

The machine tool 11 with the laser processing head 20 has a beam capturing device 24 which extends in the Y-direction and is arranged below the axis of movement of the laser processing head 20.

If the machine tool 11 has a press head 21, a lower tool, in particular a press tool, which can be moved preferably in the Y direction, in response to the press head 21, is arranged below the workpiece support 16.

The machine tool 11 has an operating device 26 on the end face of the frame 14. The operating means are fastened, for example, to the frame 14. The handling device 26 comprises a carrying structure 27 which receives at least one gripping device 28. By means of the handling device 26, at least one gripping device 28 is arranged to be movable over the workpiece carrier 16 in order to guide the workpiece 34, in particular the plate-shaped raw material and/or the cutting element 34, to the machine tool 11 and to be placed on the workpiece carrier 16.

The handling device 26 can furthermore receive and remove processed workpieces from the workpiece carrier 16 and remove them from the machine tool 11 and place them in a magazine, a stack or a container.

The workpiece support 16 has a first workpiece support section 22 and a second workpiece support section 23, which extend in front of and behind the frame 14. A beam capturing device 24 is arranged between the first workpiece support section 22 and the second workpiece support section 23. The beam capturing device 24 preferably extends transversely to the conveying direction of the workpiece 34. The beam capturing device 24 is configured in the Y-direction and advantageously extends over the entire range of movement of the laser processing head 20. The beam capturing device 24 has an opening 25 such that the laser beam emitted from the lower part in the case of processing the workpiece 34 enters the beam capturing device 24 through the opening 25.

In the embodiment represented in fig. 1, the operating device 26 is held on the frame 14 by means of a carrier structure 27. Alternatively, the handling device 26 can be positioned independently of the frame and oriented toward the workpiece carrier 16.

The workpiece 34 to be processed is, for example, a workpiece part which is produced from a sheet-like material, in particular a sheet metal blank. The workpiece 34 can be configured to produce a part therefrom. In this case, the parts can be machined into the workpiece 34 and held in the remaining grid or the remaining workpiece produced in this way, for example, by means of a micro-joint 54 (fig. 5). The part can also be cut directly from the workpiece portion 34.

A schematic cross-sectional view of the beam capturing device 24 is presented in fig. 2. The beam capturing device 24 comprises an opening 25, which is delimited by a first mould 31 and a second mould 36.

The dies 31, 36 are elongate in construction and advantageously extend along the entire opening of the beam capturing device 24. The opening 25 preferably extends over the entire range of movement of the laser processing head 20. In this embodiment of the machine tool 11, it is provided that the first die 31 and the second die 36 are fixedly arranged relative to the plane of the workpiece carrier 16.

The first mold 31 has a receiving surface 41. In the direction of the opening 25, a bevel 42 is connected, which bevel 42 ends in a die edge 43. The mould edge 43 is offset with respect to the support surface 41 downwards in the direction of the beam capture device 24. The second mold 36 preferably has the same cross-sectional geometry as the first mold 31 and is oriented mirror-image with respect to the opening 25 of the beam capturing device 24.

A pressing device 46 is fastened to the laser processing head 20. The pressing device 46 comprises a holding portion 47 which is preferably releasably fastened to the housing of the laser processing head 20. Oppositely, the holding portion 47 receives the pressing element 48. The pressing element 48 can be adjusted in height relative to the holding portion 47. Alternatively, the holding part 47 can be fixed in terms of height so as to be adjustable with respect to the laser processing head 20.

The pressing element 48 is preferably associated with a first mold 31, which is preferably configured to be able to be lowered and/or folded relative to the plane of the workpiece carrier 16.

The pressing element 48 is preferably elongate, as is exemplary shown in fig. 5. The pressing element 48 is configured as a brush element according to the first embodiment. The free end of the brush forms a compression surface 51. The workpiece 34 is fixed to the receiving surface 41 by the pressing surface 51. In this embodiment, the workpiece 34 is connected by a micro-joint 54 to the remaining grid 56 or to the raw metal plate 57 still to be processed. The micro-joint 54 is cut by the laser processing head 20. The laser beam is surrounded by a cutting gas which likewise acts from the laser processing head 20 in the direction of the beam capturing device 24. Due to the pressure of the cutting gas, tilting forces can act on the section of the workpiece 34 above the opening 25 of the beam capturing device 24 and create a tilting moment. In the case of small workpieces 34, which do not extend beyond the first die 31 or extend only slightly in the direction of the second workpiece support section 23, for example, the cutting gas pressure can tip the workpiece 34 and lead out into the beam capture device 24. The working position of the workpiece 34 can be maintained by a pressing element 48 which can be set at a distance from the support surface 41 of the first die 31 that is smaller than the thickness of the workpiece 34. Tilting of the workpiece 34 is prevented.

The pressing element 48 is preferably oriented with the longitudinal edge 52 adjacent to the opening 25 relative to the first mold 31 in such a way that the longitudinal edge 52 is located in the transition region or edge between the inclined surface 42 and the support surface 41 of the first mold 31 or is located farther away from the opening 25.

The length of the pressing element 48 can for example correspond to or be slightly larger than the diameter of the cutting gas nozzle of the laser processing head 20. At least, the pressing element 48 is in this embodiment constructed much shorter than the length of the first mold 31.

The hold-down element 48 has a plurality of brushes. The brush is preferably heat resistant, nonflammable, non-conductive, indentation-free, low wear and/or flexible. In particular, an aramid brush can also be used. Alternatively, ceramic, other plastic components or composite materials can also be used for the pressing element 48.

In the embodiment represented in fig. 2, the hold-down elements 48 are guided together while the laser processing head 20 is in a moving motion along the opening 25 of the beam capturing device 24. The pressing element 48 thus always acts on the region of the workpiece 34 to be machined.

Fig. 3 shows an alternative embodiment of the machine tool 11, in which, for example, the second die 36 is arranged fixedly relative to the plane of the workpiece support surface. The first die 31 can be lowered and/or flipped downward relative to the plane of the workpiece carrier 16. For example, a sinking device 37 is provided, by means of which the first mold 31 can be sunk and/or can be folded. The sinking means 37 have at least one actuator 38 which receives the first mould 31, for example in a height-adjustable manner. Such an actuator 38 can be constructed from a lift cylinder which is driven pneumatically, hydraulically or electromagnetically. Furthermore, the sinking means 37 has a pivoting assembly 39, which receives the at least one actuator 38, for example. The pivot assembly 39 comprises a pivot arm 40 which in turn can be actuated by means of at least one actuating element 38 in a reversible manner about a pivot axis 44, for example.

Alternatively, the sinking means 37 can have only an actuator 38 for height adjustability or only a pivoting assembly 39, so that the first mould 31 can be folded over.

The first, collapsible mold 31 can also be fastened to a part flap or a pivotable table section. By means of pivotable table sections or component shutters, the workpiece 34 can be guided downwards alongside the beam capturing device 32.

In fig. 4, a further alternative embodiment of the machine tool 11 of fig. 3 is presented. In this embodiment, the two dies 31, 36 can be lowered and/or folded relative to the plane of the workpiece carrier. For example, a sinking device 37 as depicted in fig. 3 can be provided on each mould 31, 36. Alternatives can also be provided. In this embodiment, the two molds 31, 36 can be simultaneously actuated in terms of a sinking movement and/or a folding movement. It is also possible that the moulds 31, 36 are successively lowered and/or turned over.

It is also possible to provide a sinking means 37 on one mould 31, 36 which can only be lowered and a sinking means 37 on the other mould 36, 31 which can only be folded.

An alternative embodiment of the hold down device 46 of fig. 2 is presented in fig. 5. This alternative embodiment differs in that the hold-down element 48 is fastened by the holding portion 47 to the shielding device 61 instead of directly to the laser processing head 20. The shielding 61 can be formed by a circular or angular frame that surrounds the laser processing head 20. Brushes are preferably also provided on the frame to shield the machining site outwardly. In this embodiment, the holding portion 47 can be configured without height adjustment, since the shielding device 61 is adjusted to match the height of the workpiece 34 to be processed. The hold-down element 48 is arranged in the shielding device 61 and is positioned such that it is located again above the support surface 41 of the first die 31 in order to hold down the workpiece 34 supported thereon and to be fixed during the cutting operation.

After the workpiece 34 has been cut or the micro-joint 54 has been severed, the first die 31 can be lowered and/or folded down so that the workpiece 34, which was previously clamped or held between the pressing element 48 and the receiving surface 41 of the first die 31 during the cutting process, becomes free and can be discharged downwards.

An alternative configuration of the beam capturing device 24 of fig. 3 is presented in fig. 6. The arrangement of the pressing device 46 relative to the laser processing head 20 corresponds to the embodiment according to fig. 3.

The molds 31, 36 are in this embodiment embodied as rollers or balls. In this configuration, the longitudinal edges 52 of the compression faces 51 of the compression elements 48 are aligned with the highest point of the roller or ball such that the compression elements 48 extend opposite the direction of the opening 25. The longitudinal edges 52 of the pressing surfaces 51 can also be arranged offset outwardly with respect to the respective highest points of the dies 31, 36 in the direction toward the first and second workpiece support sections 22, 23.

An alternative configuration of the compression device of fig. 2 is presented in fig. 7. In this embodiment, the pressing element 48 extends over the entire length of the opening 25 of the first mold 31 or the beam capturing device 24. The holding portions 47 are gripped on the respective outer ends of the pressing elements 48, which holding portions can be fastened to the beam capture device 24, the workpiece carrier 16 or the frame 14. The holding portion 47 is preferably provided with a height adjustment to adjust the pressing element 48 to match the respective thickness of the workpiece 34 to be processed.

The holding-down element 48 is thus fixedly positioned relative to the beam-capturing device 24 or the first mold 31, while the laser processing head 20 can be moved relative to the beam-capturing device 24.

In fig. 8 a schematic side view of an alternative embodiment of fig. 5 is presented. In this embodiment, an actuatable positioning device 64 is provided, which receives the pressing element 48. The positioning device 64 can be, for example, a pneumatic, hydraulic and/or electromagnetic cylinder, or can also be a linear motor or other controllable servomotor. The positioning means 64 can be provided on the frame 14 or can also be provided on a stand arranged separately from the frame 14. The pressing element 48 can be activated by the positioning device 64 in order to transfer it from a position located remote from the first mold 31 into the working position. In the operating position of the pressing element 48, it presses the workpiece 34 against the support surface 41 of the first die 31. Similar can be true for the second mold 36. By means of the displacement movement of the pressing element 48 from the working position into the inactive position, a simplified positioning movement of the plate-shaped material and/or the workpieces 34 for the new cutting position can also be achieved and, if desired, one or more workpieces 34 can be pressed against the first tool 31.

The pivoting movement of the pressing element 48 can also be actuated by the positioning device 64 in order to transfer the pressing element into the operating position.

Another alternative embodiment of the positioning of the hold-down 46 relative to the beam capturing device 24 is presented in fig. 9. The hold-down element 48 can be positioned on the end side of the gripping device 28. Thus, for example, the remaining grille can be held in a fixed manner by the gripping means 28. The workpiece 34 held in the remaining grid, for example by means of at least one micro-joint 54, can then be guided to the opening 25 of the beam capturing device 24, wherein the pressing element 48 in turn fulfills the following functions: the small workpiece 34 can be pressed during the cutting process and held by the pressing element 48 in a fixed manner relative to the first die 31 during processing by the laser beam.

Furthermore, it is alternatively possible to provide that the at least one pressing element 48 is arranged on the operating device 26, which receives only one pressing element 48 or a plurality of pressing elements 48. Thus, the positioning of the hold-down element 48 can be performed independently of the operation on the workpiece 34. Thereby further increasing the flexibility in the use of the hold-down element 48.

Claims

1. A machine tool for machining a workpiece (34) from a sheet-like material has

A workpiece support (16) having a first workpiece support surface and a second workpiece support surface,

a holding device (17) which holds at least one workpiece (34) and by means of which the workpiece (34) can be moved relative to the first and second workpiece support surfaces,

a beam capturing device (24) arranged between the first and second workpiece support surfaces and extending at least partially between the first and second workpiece support surfaces with an opening (25),

-a laser machining device (15) having a laser machining head (20) which is movable over an opening (25) of the beam capturing device (24),

a first mould and a second mould delimiting an opening (25) of the beam capturing device (24),

it is characterized in that the method comprises the steps of,

-a pressing element (48) of a pressing device (46) oriented in the direction of the mould is arranged above one of the two moulds, said pressing element being adjustable at least with respect to the distance from the receiving plane of said one mould (31), wherein during said machining by means of the laser beam the workpiece (34) is fixed with respect to said one mould by means of the pressing element (48) in order to prevent tilting of the workpiece (34) into the beam capturing device (24) with respect to the remaining grid of plate-like material.

2. Machine tool according to claim 1, characterized in that the hold-down element (48) is of elongate construction and is oriented parallel to the opening (25) of the beam capturing device (24).

3. Machine tool according to claim 1 or 2, characterized in that one or both dies can be lowered and/or folded in relation to the plane of the workpiece carrier (16).

4. A machine tool according to claim 3, characterized in that the pressing element (48) above the die can be set to a distance smaller than the thickness of the workpiece (34) to be machined.

5. Machine tool according to claim 1 or 2, characterized in that the pressing element (48) has a pressing surface (51) acting on the workpiece (34) to be machined, wherein a longitudinal edge (52) of the pressing surface (51) is oriented parallel to the opening (25) of the beam capturing device (24).

6. Machine tool according to claim 5, characterized in that the die has a die edge (43) which points towards the opening and which is countersunk relative to a receiving surface (41) of the die which is arranged in the receiving plane in the direction of a housing (32) of the beam capturing device (24), wherein a bevel (42) is provided between the receiving surface (41) and the die edge (43) and a longitudinal edge (52) of the compression surface (51) which points towards the opening (25) of the beam capturing device (24) is positioned in the receiving surface (41) of the die or beyond the die in the direction away from the opening (25).

7. Machine tool according to claim 5, characterized in that the receiving surface (41) of the die is formed by a ball or at least one roller or by a receiving plate or by a brush, and that the longitudinal edges (52) of the pressing surface (51) of the pressing element (48) are aligned with or are retracted relative to the highest point of the ball or the at least one roller in the direction of the first or second workpiece receiving surface.

8. Machine tool according to claim 1 or 2, characterized in that the pressing device (46) has a holder (47) for fastening the pressing element (48) on the laser processing head (20) or on a shielding device (61) surrounding the laser processing head (20).

9. Machine tool according to claim 1 or 2, characterized in that the pressing device (46) has a holding portion (47) for fastening a pressing element (48) on the die or on the first or second workpiece support section or on the frame (14) of the machine tool (11).

10. Machine tool according to claim 1 or 2, characterized in that the pressing device (46) has a holder (47) for fastening a pressing element (48) to an operating device (26) which is fastened to the frame (14) of the machine tool (11) or is located separately from the frame.

11. Machine tool according to claim 10, characterized in that the pressing element (48) can be set and/or adjusted in terms of orientation and/or height relative to the mould by means of a positioning device (64) or by means of an operating device (26).

12. Machine tool according to claim 1 or 2, characterized in that the pressing element (48) is constructed from an indivisible and/or heat-resistant and/or non-conductive and/or wear-resistant and/or flexible material.

13. Machine tool according to claim 5, characterized in that the pressing element (48) is configured as an elongated brush element and that the end of the brush forms a pressing surface (51).