Abstract:
The invention relates to a method for distributed control of a machining tool ( 24 ), in particular a laser machining tool, which comprises a machining area ( 31 ) which is surrounded by a protective housing ( 22 ) and has at least one area ( 27, 28 ) for access to the machining area ( 31 ) which is monitored, and comprising a control which is operated by at least one operator panel ( 21 ) to start the machining tool ( 24 ), wherein the machining tool is controlled by means of one or more multifunction keys ( 16 ), and at least one multifunction key ( 16 ) is associated with the at least one access area ( 27, 28 ), and when the respective multifunction key is pressed, ( 16 ) a work step of an operating sequence for the machining tool ( 24 ) is actuated which is next in a repetitive sequence of consecutive work steps of the operating sequence.

Description:
TECHNICAL FIELD 
       [0001]    The invention relates to a method for decentralized control of a machine tool, particularly a laser machine tool. 
       BACKGROUND 
       [0002]    A machine tool of this kind, particularly a laser machine tool, is known from the machine tool Lasercell 1005 from Trumpf, Inc. A machine tool of this kind has a machining compartment which is surrounded by a protective housing. The protective housing contains at least one access region for the machining compartment, which is monitored. Arranged outside the protective housing is a main control panel which allows the machine tool to be controlled. This main control panel comprises a Teachpanel, which can be used to input both basic functions and auxiliary functions. Provided in decentralized fashion with respect to the main control panel, for the purposes of opening and closing protective doors, are individual control elements which comprise individual control keys in line with the assignment of the regions. For example, an automatic protective door for an access region is provided with a control key for opening the door, a control key for closing the door, a control key for operating a light in a protective housing, a control key for an emergency off function and a control key for acknowledging a loaded workpiece transporting apparatus in the machining compartment outside the protective housing. 
         [0003]    Such machine tools are loaded and unloaded with workpieces by means of workpiece transporting apparatuses, the workpieces moving from the machining compartment through a separate access region out of a loading compartment outside the machine tool into the machining compartment inside the protective housing. This access region in turn has a further control element associated with it which, in contrast to the aforementioned control element, comprises other control keys. 
         [0004]    These known control elements allow all the functions for controlling a machine tool. However, the machine operator needs to select a control key and operate a respective control element for each requisite work step at the location of the work step which is to be performed. This arrangement of the control elements requires a specific instruction on each control element on the basis of the state of the machine tool. Furthermore, the machine operator needs to initiate the individual control steps at the respective location of what is happening. 
       SUMMARY 
       [0005]    The invention is therefore based on the object of providing a method for the decentralized control of a machine tool in which the actuation is simplified and the control elements for the decentralized control are harmonized. 
         [0006]    The invention achieves the object by means of a method for the decentralized control of a machine tool in accordance with the features of claim  1 . Further advantageous refinements and developments of the invention are specified in the further dependent claims. 
         [0007]    The method according to the invention has the advantage that for the decentralized control of a machine tool a standard multifunction pushbutton is provided on the access region(s) of the machine tool, so that it is a simple matter for consecutive work steps to be actuated by the multifunction pushbutton. In this case, the respective operation of the multifunction pushbutton involves a work step in the control cycle for the machine tool being actuated which is next in line in a repetitive sequence of consecutive work steps in the control cycle. This executes a chain of consecutive work steps. Furthermore, the standard configuration of the multifunction pushbutton also allows actuation of an access region which is provided remotely but in visible range of the machine operator. This can allow reduced process times on the basis of faster control. 
         [0008]    The multifunction key can successively actuate the consecutive work steps of a control cycle which is stipulated for each mode of operation of the machine tool. This means that the typical or regularly recurring work steps control a specific control cycle for every mode of operation. The machine tool is preferably controlled in the modes of operation “machining a workpiece” and “setting up a machine tool” by means of the multifunction pushbutton. 
         [0009]    In one embodiment of the method, in the “machining a workpiece” mode of operation a machining program is interrupted by operating the multifunction pushbutton. It is no longer necessary to identify a current work state for the machine tool during the interruption of the work process and, as a result, for the machine operator to actuate or operate an appropriate control element to return to the work process and continue it. 
         [0010]    So that the machine operator is informed about the current state of the machine tool in the control cycle, the multifunction pushbutton can take the current operating state of the machine tool as a basis for outputting a state signal, such as a steady light, a flashing light or a plurality of flashing lights at different frequencies, or extinction of the steady light. This allows the machine operator to identify a current work step in the control cycle or the current operating state of the machine tool. The one or more multifunction pushbutton(s) can indicate(s) the machining of a workpiece in the “machining a workpiece” mode of operation by means of a first state signal, the first state signal preferably being in the form of a steady light. 
         [0011]    According to one refinement of the method according to the invention, operating the multifunction pushbutton during the machining of the workpiece in the “machining a workpiece” mode of operation interrupts the machining program and preferably stops the machining unit by slowing down linear axles, turns off a laser beam and activates a feed inhibit. 
         [0012]    The interruption of the machining program can be indicated on the multifunction pushbutton by a change in the first state signal. This allows the machine operator to identify a current work step in the control cycle or the current operating state of the machine tool. 
         [0013]    Since the machining compartment of the machine tool is normally protected for safety reasons, provision can be made for operation of the multifunction pushbutton to involve the machining compartment being rendered accessible in addition to the machining program being interrupted. In the case of manual protective doors, a lock on the protective doors is unlocked on the protective housing, or in the case of automatic protective doors, the protective doors are opened on the protective housing, or the in the case of monitoring of the access region, for example by light barriers, the monitoring is deactivated. These work steps are executed in succession and represent a control cycle to render the machining compartment of a machine tool accessible and to check the cause of the initiated interruption. 
         [0014]    In one refinement of the method, the access region of the machine tool is protected by automatic protective doors or monitoring by light barriers or a light curtain. An interruption of the machining program and the accessibility of the machining compartment are indicated to the machine operator preferably by extinction of the first state signal, preferably the steady light, on the multifunction pushbutton. This informs the machine operator that the consecutive work steps for interrupting the machining program have been executed and the machining compartment is accessible without risk. 
         [0015]    When the cause of the interruption to the machining program has been checked and cleared up, provision can be made for operation of the multifunction pushbutton to initiate a work step in order to return to the interrupted machining program, wherein automatic closure of the automatic protective doors or locking of the manual protective doors or activation of the monitoring of the access region is actuated. 
         [0016]    This successfully performed work step can be indicated by a second state signal, which can be in the form of a flashing light, on the multifunction pushbutton. This simultaneously ensures a check for the completely executed work step. 
         [0017]    In one refinement of the method, the access region of the machine tool is protected by manual protective doors. The interruption of the machining program and the unlocking of the manual protective doors are preferably indicated by a second state signal from the multifunction pushbutton, particularly a flashing light. The second state signal from the multifunction pushbutton is extinguished when at least one manual protective door is opened, so that the machine operator knows that the machining compartment is accessible. 
         [0018]    To continue the machining program, the at least one opened manual protective door is closed and then the manual protective doors are locked by operating the multifunction pushbutton. 
         [0019]    The multifunction pushbutton indicates the locking of the manual protective doors by means of the second state signal, particularly the flashing light. This allows the machine operator to identify the current work step in a control cycle or the current operating state of the machine tool. 
         [0020]    After a flashing light is indicated on the multifunction pushbutton, the machine tool can be activated by operating the multifunction pushbutton again to continue the machining program. The machining program continues its further machining at the point at which the interruption of the machining program was initiated. 
         [0021]    From the time at which the continuation of the machining program was initiated onward, the flashing light on the multifunction pushbutton can be transformed into a steady light. This indicates that the machining program is being executed routinely. 
         [0022]    After one or more workpieces positioned in the machining compartment have been machined completely, a change of workpiece is required. This change of workpiece is a machine step within the machining program in the “machining the workpiece” mode of operation or can be performed manually by the machine operator. 
         [0023]    In accordance with one refinement of the method, the change of workpiece in the machining compartment is indicated on the multifunction pushbutton by a change in the first state signal, for example, extinction of the steady light. This again notifies the machine operator about the current status. 
         [0024]    Workpieces can be loaded and unloaded by means of a workpiece transporting apparatus. The workpiece is changed by virtue of at least one access region of the machine tool being enabled, so that the workpiece transporting apparatus is moved from a loading compartment into the machining compartment. If two loading compartments are provided, a workpiece transporting apparatus is moved from the machining compartment into a first loading compartment and a workpiece transporting apparatus is moved from a second loading compartment into the machining compartment, for example. When the workpiece transporting apparatus has been moved, the access region is activated. Subsequently, the as yet unmachined workpieces can be machined again. 
         [0025]    During the change of workpiece, operating the multifunction pushbutton can allow the at least one workpiece transporting apparatus to be stopped and operating the multifunction pushbutton again can allow it to be restarted. 
         [0026]    In addition, provision can be made for the work steps of moving the workpiece carrier apparatus from the loading compartment into the machining compartment or moving it from the machining compartment into the loading compartment to be controlled in the “setting of a machine tool” mode of operation by operation of the multifunction pushbutton. 
         [0027]    As additional work steps, provision can be made for opening and closure of the access region to be controlled by operating the multifunction pushbutton. This provides consecutive work steps for the control cycle which allows there to be good accessibility to the machining compartment by the machine operator for the purpose of setting up the machine tool. 
         [0028]    For the purpose of simple and ergonomic operation of a machine tool of this kind, provision can also be made for the individual consecutive work steps, which are initiated in decentralized fashion by one or more multifunction pushbuttons or centrally on the main control panel, to be synchronized to one another, so that the same step is actuated on each multifunction pushbutton and the main control panel upon request. Such synchronization provides the machine operator with a free selection for operating one of a plurality of multifunction pushbuttons provided for the machine tool. 
         [0029]    The invention and further advantageous embodiments and developments thereof are described and explained in more detail below using the examples illustrated in the drawings. The features which can be found in the description and in the drawings can be applied individually on their own or severally in any combination, in line with the invention. 
     
    
     
       DESCRIPTION OF DRAWINGS 
         [0030]      FIG. 1  is a schematic view of a decentralized control element, 
           [0031]      FIG. 2  is a perspective view of a machine tool with a protective housing and manual protective doors, 
           [0032]      FIG. 3  is a perspective view of a machine tool with automatic protective doors and a pallet changer as a workpiece transporting apparatus, and 
           [0033]      FIG. 4  is a perspective view of a machine tool with a rotary changer as a workpiece transporting apparatus. 
       
    
    
     DETAILED DESCRIPTION 
       [0034]      FIG. 1  shows a schematic view of a control element  12  which comprises a housing or at least one mounting plate  14 . This mounting plate  14  contains a multifunction pushbutton  16 , an emergency off switch  17  and an acknowledgement pushbutton  18 . These three pushbuttons  16 ,  17 ,  18  can be designed to be of different colors. The emergency off switch  17  is in the form of a red switch with a yellow background, the acknowledgement pushbutton  18  is in the form of a green pushbutton and the multifunction pushbutton  16  is in the form of a blue illuminated pushbutton. 
         [0035]      FIG. 2  shows a machine tool  24  with a protective housing  22 , wherein the protective housing  22  is accessible by an access region  27 . The access region  27  is formed by manually movable protective doors  29 , which are shown in the closed state in  FIG. 2 . A control element  12  is arranged in decentralized fashion with respect to a main control panel  21  on the protective housing  22  of the machine tool  24 . If the control element  12  is provided as a built-in component, this comprises an mounting plate  14  which is fitted flush with the protective housing  22 . Alternatively, a housing which is attached to the protective housing  22  may also be provided. 
         [0036]    In one embodiment of a machine tool  24 , provision may be made for only one control element  12  to be associated with the access region  27 . In the case of such an embodiment, the protective doors  29  are designed for opening and closing manually. However, the proactive doors  29  are unlocked and locked automatically, and this is monitored. 
         [0037]    The method according to the invention for the decentralized control of the machine tool is described in more detail below with reference to a machine tool as shown in  FIG. 3 . 
         [0038]      FIG. 3  shows a machine tool  24  with automatic protective doors  29  and automation of the loading and unloading processes for the workpieces. The machine tool  24  is in the form of a laser machine tool and comprises a machining compartment  31  which is surrounded by the protective housing  22 . The access region  27  is formed by two automatically movable protective doors  29 , which are depicted in the open state in  FIG. 3 . Each automatically movable protective door  29  has an associated control element  12  with a multifunction pushbutton  16 . The control elements  12  are integrated in upright columns  30  which are arranged in front of the protective doors  29 . 
         [0039]    The machining compartment  31  has a workpiece transporting apparatus  33  positioned in it which is in the form of a pallet changer for the purpose of automating the loading and unloading processes for the workpieces. The workpiece transporting apparatus  33  is a workbench for holding workpieces, with the touch of a button prompting the workbench to be moved between a loading and unloading position outside the protective housing  22  and a machine position within the protective housing  22 . The machine tool  24  comprises a first loading compartment  34 , which is arranged on a front of the protective housing  22 , and a second loading compartment  35 , which is arranged on a side of the protective housing  22 . This arrangement allows a machine operator to unload a workpiece whose machining is finished in the loading compartment  34 ,  35  and to load an unmachined workpiece onto the workpiece transporting apparatus  33  while the workpiece  32  is being machined in the machining compartment  31 . 
         [0040]    Depending on the size and flexibility of the machine tool  24 , one or more loading compartments  34 ,  35  may be provided. The loading compartments  34 ,  35  are protected by a light barrier, the loading compartments  34 ,  35  being limited by four columns  37  which incorporate the light barriers. The light barriers are activated by means of the acknowledgement pushbutton  18  at the control element  12 . Alternatively, the loading compartments  34 ,  35  may be protected by a light curtain. 
         [0041]    The machining compartment  31  contains, as a machining unit  36 , a laser cutting head or a laser welding head, for example, which can be moved by means of a linear axle system above the workpiece transporting apparatus  33 . 
         [0042]    A machine tool can be operated in various modes of operation. By way of example, these include the modes of operation “machining a workpiece”, “setting up a machine tool”, “maintaining a machine tool” and “diagnosis”. 
         [0043]    A workpiece is machined in line with a machining program in the “machining a workpiece” mode of operation. The machine operator programs the machining program, which sends commands to the machine controller upon starting. In the “machining a workpiece” mode of operation, many commands are produced automatically on the basis of the selected machining program. The function of the multifunction pushbutton  16  is to allow the machining program to be safely interrupted and allow the interruption to be controlled by means of the multifunction pushbutton  16 . 
         [0044]    In the “setting up a machine tool” mode of operation, the machine operator can set up the machine tool for machining. This includes activities such as aligning a laser beam, adjusting an interval control or inserting a workpiece support. 
         [0045]    Workpieces are machined in the “machining a workpiece” mode of operation. To machine the workpiece  32  which is located in the machining compartment  31 , the machining program is started using the main control panel  21 . The multifunction pushbutton  16  uses a steady light to indicate that the machining unit  36  has been activated and the machining program is being executed. 
         [0046]    A lit acknowledgement pushbutton  18  indicates to the machine operator that a change of workpiece is required on the workpiece transporting apparatus  33  which is positioned in the loading compartment  34 . While the workpiece  32  is being machined in the machining compartment  31 , the machine operator changes the workpiece in the loading compartment  34 , a workpiece which has finished being machined is removed from the workpiece transporting apparatus  33  and a new, unmachined workpiece is inserted into the workpiece transporting apparatus  33 . By pushing the acknowledgement pushbutton  18 , the machine operator confirms the change of workpiece in the loading compartment  34 . 
         [0047]    After the workpiece  32  has been machined, the machining unit  36  is stopped and the machining program is terminated. The controller for the machine tool  24  is used to change the workpiece transporting apparatus  33 . The access regions  27 ,  28  are opened, the workpiece transporting apparatus  33  is moved out of the machining compartment  31  into the loading compartment  35 , and the workpiece transporting apparatus  33  is moved out of the loading compartment  34  into the machining compartment  31 . Next, the protective doors  29  are closed, so that the access regions  27 ,  28  are sealed, and the machining unit  36  starts to machine the next workpiece as a result of the machining program being started. 
         [0048]    The interruption of the machining to change a workpiece is indicated by the multifunction pushbutton  16  by virtue of the steady light being extinguished. As soon as the machining program is continued after the workpiece has been changed, the multifunction pushbutton  16  indicates a steady light again. 
         [0049]    Should it become necessary to access the machining compartment  31  while the workpiece  32  is being machined, the machining program can be interrupted by operating the multifunction pushbutton  16 . The multifunction pushbutton  16  can be used to actuate consecutive work steps in a control cycle which are required in order to safely interrupt the machining of the workpiece  32  and to subsequently continue the machining. 
         [0050]    By operating the multifunction pushbutton  16 , the machining unit  36  is stopped by slowing down the linear axles, a laser beam is switched off and a feed inhibit is activated. In addition, the protective door  29  associated with the operated multifunction pushbutton  16  is opened. The machine operator can enter the machining compartment  31  and correct the fault. When the fault has been corrected, the open protective door  29  can be closed by operating the multifunction pushbutton  16 . Further operation of the multifunction pushbutton  16  continues the machining program at the point at which the machining program was previously interrupted. 
         [0051]    The multifunction pushbutton  16  indicates the various states of the machine tool  24  during the interruption by means of different state signals. The interruption of the machining program and the opening of the protective door  29  are indicated by virtue of the steady light on the multifunction pushbutton  16  being extinguished. When the fault has been corrected and the protective door  29  has been closed, the multifunction pushbutton  16  indicates a flashing light which signals to the machine operator that further action is required in order to continue the machining. Pushing the multifunction pushbutton  16  again activates the machining unit  36  and continues the machining program, and the multifunction pushbutton  16  changes from the flashing light to a steady light. 
         [0052]    When the machine tool  24  has a protective housing  22  with protective doors  29  which need to be opened manually, it is possible, following an interruption to the machining program as a result of the multifunction pushbutton  16  being operated, for stopping of the machine unit  36  and unlocking of the protective doors  29  to be indicated by a steady light changing to a flashing light on the multifunction pushbutton  16 . This indicates to the machine operator that the machining compartment  31  is accessible. 
         [0053]    In the “setting up a machine tool” mode of operation, a different sequence of repetitive work steps is stored on the multifunction pushbutton  16 . 
         [0054]    The workpiece transporting apparatus  33  may be positioned in the loading compartment  34 ,  35  or in the machining compartment  31 . 
         [0055]    Operating the multifunction pushbutton  16  opens the protective doors  29 , further operation of the multifunction pushbutton  16  moves the workpiece transporting apparatus  33  out of the loading compartment  34 ,  35  into the machining compartment  31  or out of the machining compartment  31  into the loading compartment  34 ,  35 , and further operation of the multifunction pushbutton  16  closes the protective doors  29  again. 
         [0056]    Thus, only operation of the multifunction pushbutton  16  initiates a control cycle of consecutive work steps, which comprises a typical sequence of consecutive work steps, with incorrect operation being prevented. In this case, both the type and number of work steps from interrupting the work process to stopping the machine tool and the type and number of work steps for continuing the interrupted work process may be altered, increased and also configured differently from one another in comparison with the exemplary embodiments. 
         [0057]      FIG. 4  shows a machine tool  24  in similar fashion to  FIG. 3 , the machine tool being distinguished in that the workpiece transporting apparatus  33  is formed by a rotary changer instead of a pallet changer. A rotary changer of this kind has two or more stations in which the workpieces are positioned. The workpiece transporting apparatus  33  shown in  FIG. 4  is a rotary changer having two stations, a loading and unloading station  38  and a machining station  39 . The loading and unloading station  38  is isolated from the machining station  39  by a protective wall  40 . The workpiece whose machining is finished is rotated out of the machining station  39  into the loading and unloading station  38  and can be unloaded in the loading and unloading station  38 . the loading and unloading station  38  is loaded with an unmachined workpiece. Next, the change of workpiece effected in the loading and unloading station  38  is confirmed on the upright column  41  and the exiting of the access region  27  is confirmed by the acknowledgement pushbutton  18 . Alternatively, respective confirmation can be requested for the change of workpiece effected and the exiting of the loading and unloading station  38 . The access region  27  is activated and a machining program is started. 
         [0058]    The actuation of such a workpiece transporting apparatus  33  corresponds, in principle, to the control described for  FIG. 3 . Instead of moving the pallet changer into and out of the loading compartment,  34 ,  35 , there is a rotary movement of the rotary changer in order to allow the workpieces to be transported on from the loading and unloading station  38  to the downstream machining station  39 . 
         [0059]    As an alternative to the access regions  27 ,  28  shown in  FIG. 3 , which are sealed by protective doors  29 , an access region  27  is provided in  FIG. 4  which is protected by means of a light barrier. This light barrier or a light curtain is integrated in upright columns  41 , which likewise hold control elements  12  and are part of the protective housing  22 . 
         [0060]    On the basis of the synchronization of the main control panel  21  with one or more control elements  12  provided in decentralized fashion with respect to the main control panel  21 , the actuation can take place both on the main control panel  21  and on the control elements  12 . 
         [0061]    The control elements  12  for decentralized actuation may be provided on the protective housing  22  or on the separate columns  37 ,  41 . In addition, it is possible for such a control element  12  to be in the form of an autarkic mobile radio which the machine operator carries, so that he can perform actuation regardless of his position relative to the machine tool  24 . 
         [0062]    A machine tool is equipped as standard with a particular method for decentralized control which can be called using the multifunction pushbutton  16  in the “machining a workpiece” and “setting of a machine tool” modes of operation. At the request of a customer, the multifunction pushbutton  16  can also be programmed with an individual sequence of work steps. 
         [0063]    All features described above are each independently fundamental to the invention and can be combined with one another as desired.