Abstract:
A machine tool for machining workpieces comprising a support structure, a punching device mounted on the support structure, and a laser machining device mounted on the support structure. The machine tool includes a suspension device provided between the punching device and the laser machining device to reduce the laser machining device from being stimulated to move unintentionally due to the operation of the punching device. The suspension device has a spring rate which can be adjusted by a laser positioning device. The laser positioning device can move the laser machining device relative to the workpiece into a functional position and also into a position remote from the functional position. The spring rate of the suspension device is adjusted such that the functional position of the laser machining device is assigned a higher spring rate than that assigned to the position of the laser machining device remote from the functional position.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims priority under 35 U.S.C. §119(a) to European Application No. 15 180 878.9, filed on Aug. 13, 2015, the entire contents of which are incorporated herein by reference. 
       TECHNICAL FIELD 
       [0002]    The invention relates to a machine tools for machining workpieces, such as metal sheets. 
       BACKGROUND 
       [0003]    On certain combination punching and laser machines, the punching and the laser machining of workpieces are carried out successively. During the punching operation, the laser machining device is moved by a laser positioning device into a parked position away from the punched workpiece. For laser machining the workpiece, the laser machining device is transferred into a functional position near the workpiece by the laser positioning device. 
         [0004]    Due to the punching device and the laser machining device both being fastened to the machine frame, there is a risk that shocks and impacts occurring during the punching operation of the machine tool will be transferred to the laser machining device arranged in the parked position. In order to prevent the laser machining device from being affected by punching of the workpiece, special design precautions are taken in the prior art. 
         [0005]    On a machine tool, which is provided by TRUMPF (address: Johann-Maus-Straβe 2, 71254 Ditzingen, Germany) under the name “TruMatic® 6000 fiber”, the laser machining device is mounted together with the laser positioning device on a base plate which is in turn, in the parked position of the laser machining device, resiliently mounted on the machine frame which is also equipped with the punching device. The suspension of the TruMatic® 6000 fiber provides an advanced system that ensures that the shocks and impacts associated with the punching operation of the machine are not transferred unfiltered to the laser machining device. If a workpiece is being laser-machined and the laser machining device is thus positioned in the functional position near the workpiece, the resilient mounting of the base plate equipped with the laser machining device is deactivated by means of a device provided solely for this purpose and the laser machining device is rigidly connected to the machine frame of the generic machine tool by means of the base plate. As a result of the rigid connection of the laser machining device to the machine frame, the workpiece can be laser-machined with the required precision. 
       SUMMARY 
       [0006]    Various embodiments disclosed herein provide machine tools for machining workpieces. The machine tool includes a support structure. The machine tool includes a punching device mounted on the support structure and configured to punch an aperture in a workpiece. The machine tool includes a laser machining device mounted on the support structure. The laser machining device is configured to laser-machine the workpiece. The laser machining device and the punching device are connected to one another by the support structure. The machine tool includes a laser positioning device configured to position the laser machining device with respect to the workpiece. The laser positioning device is configured to move the laser machining device by an activation movement into a functional position for laser machining. The laser positioning device is configured to move the laser machining device into a position remote from the functional position. The machine tool includes a suspension device having a spring rate. The suspension device is configured to support the laser machining device on the support structure so as to reduce movement of the laser machining device caused by an operation of the punching device. The laser positioning device is configured to adjust the spring rate of the suspension device such that the suspension device has a higher spring rate when the laser machining device is positioned in the functional position than the spring rate of the suspension device when the laser machining device is positioned in the position remote from the functional position. 
         [0007]    Accordingly, in the case of various embodiments of the invention, the laser positioning device is used not only to transfer the laser machining device into the functional position and into a position remote from the functional position, in particular a position remote from the workpiece, for example into a parked position, but also to adapt the mounting of the laser machining device on the support structure to variable operating situations. If the laser machining device is in the functional position and if the laser machining device is intended to be used for laser machining a workpiece, the laser positioning device ensures a high spring rate of the suspension device by means of which the laser machining device is connected to the support structure of the machine tool according to the invention. In certain implementations, the laser machining device transferred into the functional position can be rigidly connected to the support structure by means of the laser positioning device. The laser machining, for example laser cutting or laser welding the relevant workpiece, can be carried out with high precision due to the increased spring rate of the suspension device. If the laser machining device is not used for machining workpieces and the machine tool according to various embodiment the invention is in the punching mode, the spring rate of the suspension device is reduced by means of the laser positioning device. As a result, the suspension device is capable of absorbing shocks and impacts occurring due to the punching operation, and thereby preventing adverse effects of the punching operation on the laser machining device. The dual function consequently carried out by the laser positioning device advantageously results in a simple structural design of the machine tool according to embodiments of the invention. 
         [0008]    In particular embodiments of the invention, the spring rate of the suspension device provided for mounting the laser machining device is modified by the laser positioning device changing the length of a spring of the suspension device. In a certain spring design, this measure provides a simple option for varying the “rigidity” of the mounting of the laser machining device on the support structure of the machine tool according to the invention. In particular embodiments the spring includes, for example, helical springs, leaf springs and disc spring. The springs can include elastomer springs and pneumatic springs. 
         [0009]    In particular embodiments of the invention, a support structure-side device stop of the machine tool according to the invention ensures substantially zero-backlash support of the laser machining device, moved into the functional position, in the direction of the activation movement. In the opposite direction, the laser machining device is supported on the support structure by means of the spring of the suspension device, the spring of the suspension device being compressed by means of the laser positioning device. Overall, this results in a substantially rigid mounting of the laser machining device, both in the direction of the activation movement of the laser machining device and in the opposite direction, as is essential for carrying out high-precision laser machining of a workpiece. 
         [0010]    Certain embodiments of the invention relates to the detailed structural implementation of the mounting system. The laser positioning device can include a support structure-side drive element that is assigned to the support structure of the machine tool and a device-side drive element that is connected for movement to the laser machining device and that is movable relative to the support structure. The support structure-side drive element of the laser positioning device is supported on the support structure of the machine tool according to embodiments of the invention in the opposite direction to the activation movement of the laser machining device and is therefore resiliently mounted in said direction when the laser machining device is in a position remote from the functional position. The resilient mounting of the support structure-side drive element causes a corresponding resilient mounting of the device-side drive element that interacts with the support structure-side drive element and, via said device-side drive element, also causes a corresponding resilient mounting of the laser machining device that is connected for movement to the device-side drive element. Proceeding from the position remote from the functional position, the laser machining device is transferred into the functional position by means of an activation movement, as a result of a movement of the device-side drive element relative to the support structure-side drive element. In the functional position, the laser machining device is supported in the direction of the activation movement by means of the support structure-side device stop and is therefore prevented from moving further in the direction of the activation movement. Continued actuation of the laser positioning device now leads to the support structure-side drive element being displaced relative to the device-side drive element in the opposite direction to the drive movement of the laser machining device, and the spring of the suspension device thus compressing and the spring rate of the suspension device increasing, which suspension device is provided for supporting the laser machining device in the opposite direction to the activation movement of the laser machining device. 
         [0011]    Linear movements of the device-side drive element and of the support structure-side drive element of the laser positioning device along a laser positioning axis can be achieved, according to particular embodiments. For example, in certain embodiments, the laser machining device is configured to be moved along a laser positioning axis via the laser positioning device into the functional position by the activation movement and also, in the opposite direction to the activation movement, into the position remote from the functional position. The device-side drive element of the laser positioning device is configured to move relative to the support structure-side drive element of the laser positioning device. The support structure-side drive element and, via the support structure-side drive element, the device-side drive element, and the laser machining device are supported on the support structure along the laser positioning axis in the opposite direction to the activation movement of the laser machining device by the spring of the suspension device. The support structure-side drive element is configured to be moved relative to the device-side drive element along the laser positioning axis in the opposite direction to the activation movement so as to compress the spring of the suspension device, with the laser machining device supported in the functional position on the support structure-side device stop. 
         [0012]    In particular embodiments, of the machine tool, a laser positioning device provided as a piston-cylinder unit. In such embodiments, the cylinder of the piston-cylinder unit is provided as the device-side drive element and the piston of the piston-cylinder unit is provided as the support structure-side drive element of the laser positioning device. 
         [0013]    In particular embodiments, of the machine tool the laser positioning device of the machine tool is provided in the form of a pneumatic piston-cylinder unit. Owing to the compressibility of the compressed air present in the cylinder of the pneumatic piston-cylinder unit, the piston can be resiliently moved inside the cylinder. In combination with a spring of the suspension device for the laser machining device, a pneumatic piston-cylinder unit forms a spring-damper system. 
         [0014]    In particular embodiments, the laser machining device is resiliently mounted on the support structure of the machine tool both in the direction of the activation movement and in the opposite direction to the activation movement. Associated therewith is a comprehensive protection of the laser machining device against impairment by shocks and impacts that occur during the punching operation of the machine tool. 
         [0015]    In the interest of a structure having a particularly simple design, it is provided in the case of the machine tool according to the invention for the same component to support the laser machining device positioned in the functional position in the direction of the activation movement and to support the spring of the suspension device for the laser machining device in the opposite direction. 
         [0016]    In particular embodiments of the machine tool, the support structure, on which both the punching device and the laser machining device of the machine tool are mounted, can move conjointly with the punching device and the laser machining device in the transverse direction of the activation movement, in particular in a direction perpendicular to a laser positioning axis. Travel movements of this kind can be used for positioning the punching device and/or the laser machining device relative to a workpiece to be machined, but can also be carried out as working movements. In any case, the same drive can be used to both produce the movements of the punching device and to produce the movements of the laser machining device. As a result, machine tools according to embodiments of the invention are particularly energy and cost-efficient. 
         [0017]    The invention will be described in more detail in the following with respect to schematic drawings given by way of example, in which: 
     
    
     
       DESCRIPTION OF DRAWINGS 
         [0018]      FIG. 1  is a partial view of a punch-laser combination machine comprising a punching device and a laser machining device on a common support structure, 
           [0019]      FIG. 2  shows the laser machining device according to  FIG. 1  in a parked position on the support structure and comprising a functional suspension device between the support structure and the laser machining device, 
           [0020]      FIG. 3  shows the laser machining device according to  FIGS. 1 and 2  in a functional position on the support structure when the suspension device is functional, and 
           [0021]      FIG. 4  shows the laser machining device according to  FIGS. 1 to 3  in the functional position on the support structure when the suspension device is deactivated. 
       
    
    
     DETAILED DESCRIPTION 
       [0022]    According to  FIG. 1 , a machine tool  1  designed as a punch-laser combination machine comprises a machine frame  2 . A support structure  3  can be moved on the machine frame  2  perpendicularly to the plane of the drawing of  FIG. 1 . The support structure  3  mounts a punching device  4  and a laser machining device in the form of a laser cutting head  5 . Both the punching device  4  and the laser cutting head  5  are conventionally designed. 
         [0023]    The punching device  4  comprises, a ram  6  which has a tool holder  7  in which a punch can be introduced. By means of drive devices (not shown in detail), the ram  6 , together with the tool holder  7  and a punch introduced into the tool holder  7 , can be moved along a punch-stroke axis  8  by a working stroke and by a return stroke following the working stroke, and can be rotationally adjusted about the punch-stroke axis  8 . The laser cutting head  5  can be positioned along a laser positioning axis  9  in the manner described in more detail in the following. Both the punching device  4  and the laser cutting head  5  of the machine tool  1  are used for machining a metal sheet  10 , which is indicated in  FIGS. 1, 3 and 4  and is supported during machining by a conventional workpiece support (not shown for reasons of simplicity). 
         [0024]    In  FIG. 1 , the laser cutting head  5  is moved along the laser positioning axis  9  into a functional position near the workpiece. If the laser cutting head  5  is in the functional position, the metal sheet  10  can be cut by a laser beam directed from the laser cutting head  5  onto the metal sheet  10 . Relative movements of the laser cutting head  5  and metal sheet  10  that are to be carried out for cutting metal sheets are produced, on the one hand, by movements of the support structure  3 , which mounts the laser cutting head  5 , that are perpendicular to the plane of the drawing of  FIG. 1  and, on the other hand, by horizontal movements of the metal sheet  10  that are perpendicular to the movements of the support structure  3 , a superimposition of the movements carried out in both axial directions being possible. In order that the metal sheet  10  can be cut with the precision required, the laser cutting head  5  positioned in the functional position must be connected as rigidly as possible to the support structure  3  which is, in turn, guided on the machine frame  2  so as to have zero backlash. 
         [0025]    The punching device  4  is shutdown during the cutting operation of the machine tool  1 . In this case, as can be seen in  FIG. 1 , the ram  6 , together with the tool holder  7 , is withdrawn from the metal sheet  10  along the punch-stroke axis  8 . 
         [0026]    Conversely, during the punching operation of the machine tool  1 , the laser cutting head  5  is raised, relative to the functional position thereof shown in  FIG. 1 , along the laser positioning axis  9  by means of a retracting movement relative to the metal sheet  10  and into a parked position. The direction of the retracting movement of the laser cutting head  5  is illustrated in  FIG. 1  by an arrow  11 .  FIG. 2  shows the laser cutting head  5  in the parked position remote from the workpiece. The metal sheet  10  is not shown in  FIG. 2 . 
         [0027]    There is a gap between the laser cutting head  5  positioned in the parked position and the top of the metal sheet  10 , which gap is dimensioned such that the metal sheet  10  can carry out the movements required for the punching without colliding with the laser cutting head  5 . 
         [0028]    When moving into the parked position and into the functional position, the laser cutting head  5  is guided, by means of a linear guide  12 , along the laser positioning axis  9  on a base plate  13  that is rigidly connected to the support structure  3 . For this purpose, the linear guide  12  comprises a guide rail  14  on the base plate  13  and a guide carriage  15  on the laser cutting head  5 , which guide carriage is arranged on the guide rail  14 . 
         [0029]    Impacts and shocks, which travel from the punching device  4  via the support structure  3  and the base plate  13  to the laser cutting head  5 , occur during the punching operation of the machine tool  1 . 
         [0030]    In order to prevent the laser cutting head  5  from being affected by punching the metal sheet  10  and by the shocks and impacts associated therewith, a suspension device  16  is provided between the punching device  4  and the laser cutting head  5 , in particular between the base plate  13  and the laser cutting head  5 . 
         [0031]    According to  FIG. 2 , the suspension device  16  comprises a lower spring  17  and an upper spring  18 . In the example shown, both the lower spring  17  and the upper spring  18  are designed as helical springs. The spring rate of the upper spring  18  of the suspension device  16  is selected such that the upper spring  18  is only partially compressed under the action of masses, which load said spring in the direction of gravity. 
         [0032]    Both springs  17 ,  18  are positioned on a piston rod  19 , the lower spring  17  being pre-tensioned between a lower spring brace  20  connected to the piston rod  19  and the lower face of a horizontal leg  21  of an brace angle bracket  22 , and the upper spring  18  being pre-tensioned between an upper spring brace  23  on the piston rod  19  and the upper face of the horizontal leg  21  of the brace angle bracket  22 . A vertical leg  24  of the brace angle bracket  22  is rigidly connected to the base plate  13 . The piston rod  19  passes through the horizontal leg  21  of the brace angle bracket  22  such that longitudinal movements of the piston rod  19  relative to the brace angle bracket  22  are possible. 
         [0033]    The piston rod  19  is part of a piston-cylinder unit  25  provided as a laser positioning device, which unit is operated by compressed air in the example shown. The piston-cylinder unit  25  further comprises a cylinder  26  as a device-side drive element that is associated with the laser cutting head  5 , which cylinder, like the piston rod  19 , extends in parallel with the laser positioning axis  9  and which guides a piston on its inside along the laser positioning axis  9 , which piston is attached to the piston rod  19  and is hidden in the drawings. The piston of the piston-cylinder unit  25  forms a support structure-side drive element that is associated with the support structure  3 . 
         [0034]    The cylinder  26  of the piston-cylinder unit  25  is rigidly connected to the laser cutting head  5  by means of a connecting rod  27 . Near the base of the connecting rod  27 , the laser cutting head  5  is equipped with a positioning stop  28  that projects towards the viewer when looking at  FIG. 2 . 
         [0035]    In  FIG. 2 , the suspension device  16  is in the initial state with the laser cutting head  5  in the parked position. Both the lower spring  17  and the upper spring  18  have a relatively low spring rate. Shocks and impacts occurring during the punching operation of the machine tool  1 , which travel from the punching device  4  to the brace angle bracket  22  attached to the base plate  13 , are therefore transferred relatively smoothly to the piston rod  19  of the piston-cylinder unit  25 , by means of the springs  17 ,  18  which are supported on the horizontal leg  21  of the brace angle bracket  22 , along the laser positioning axis  9 . Since the compressed air present inside the cylinder  26  of the piston-cylinder unit  25  can be compressed, the piston-cylinder unit  25  can damp oscillations of the springs  17 ,  18 , occurring as a result of the punching operation, in the manner of a shock absorber. The machining-induced shocks and impacts consequently arrive at most in a highly filtered manner at the laser cutting head  5 , which head optionally carries out compensatory movements along the laser positioning axis  9 , during which the laser cutting head  5  is guided on the base plate  13  by means of the guide carriage  15  that resonates with the laser cutting head  5  and by means of the guide rail  14  of the linear guide  12  fixed to the support structure. In particular, damage to the laser cutting head  5  and/or an undesired shift of optical elements provided on the laser cutting head  5  are effectively prevented in this manner by the suspension device  16 . 
         [0036]    If a punching process has finished and the metal sheet  10  is intended to be cut by means of the laser cutting head  5 , the punching device  4  is withdrawn from the metal sheet  10  into the position according to  FIG. 1 , and the laser cutting head is lowered, by means of the piston-cylinder unit  25 , out of the parked position according to  FIG. 2  into the functional position by means of an activation movement along the laser positioning axis  9 . The direction of the activation movement of the laser cutting head  5  is shown in  FIG. 2  by an arrow  29 . 
         [0037]    If the piston-cylinder unit  25  is actuated to produce an activation movement of the laser cutting head  5 , the cylinder  26  of the piston-cylinder unit  25  moves downwards relative to the piston rod  19  and to the piston guided inside the cylinder  26  along the laser positioning axis  9 . Together with the cylinder  26 , the laser cutting head  5  connected thereto lowers by means of an activation movement along the laser positioning axis  9 . The suspension device  16  remains at first in the initial state. During the activation movement, the laser cutting head  5  is also guided by the linear guide  12  along the laser positioning axis  9 . 
         [0038]    The activation movement of the laser cutting head  5  ends and the functional position of the laser cutting head  5  is reached as soon as the positioning stop  28  attached to the laser cutting head  5  strikes the brace angle bracket  22  acting as a support structure-side device stop, in particular strikes the horizontal leg  21  thereof, and the conditions according to  FIG. 3  thus result. The laser cutting head  5  is still resiliently supported on the brace angle bracket  22  used as a support structure-side spring brace, and thus on the support structure  3  of the machine tool  1 , by means of the lower spring  17  of the suspension device  16  in the opposite direction (illustrated by the arrow  11 ) to the activation movement of the laser cutting head  5 . 
         [0039]    Due to the support of the laser cutting head  5  by the brace angle bracket  22  acting in the direction  29  of the activation movement, continued actuation of the piston-cylinder unit  25  does not result in further lowering of the laser cutting head  5 , but rather, with the laser cutting head  5  remaining in the functional position, results in the piston rod  19  entering further into the cylinder  26  of the piston-cylinder unit  25  and the piston correspondingly moving inside the cylinder  26  relative thereto in the opposite direction  11  to the activation movement of the laser cutting head  5 . As a result, the lower spring  17 , which is pre-tensioned between the lower face of the horizontal leg  21  of the brace angle bracket  22  on the one hand and the lower spring brace  20  on the piston rod  19  on the other hand, is compressed until the coils of the lower spring  17  lie tightly packed one on top of the other and therefore form a body that is rigid along the laser positioning axis  9  ( FIG. 4 ). 
         [0040]    The laser cutting head  5  is thus mounted on the brace angle bracket  22  so as to have zero backlash along the laser positioning axis  9  and, by means of said brace angle bracket and the base plate  13 , is mounted on the support structure  3  and the machine frame  2  of the machine tool  1 . Consequently, the metal sheet  10  can now be cut in an extremely precise manner using the laser cutting head  5 . 
         [0041]    If cutting the metal sheet has been completed and if further punching is to follow, the piston-cylinder unit  25  is actuated such that first the piston rod  19  moves out of the cylinder  26 , which retains its position along the laser positioning axis, the lower spring  17  thus being extended ( FIG. 3 ), before the cylinder  26  moves upwards, together with the laser cutting head  5 , along the piston rod  19 , and thus transfers the laser cutting head  5  into the parked position remote from the workpiece ( FIG. 2 ). 
         [0042]    A number of embodiments of the invention have been described. Nevertheless, it will be understood that various modifications may be made without departing from the spirit and scope of the invention. Accordingly, other embodiments are within the scope of the following claims.