Abstract:
A loading and unloading unit for sheet metal providing a first tool holder is provided. Therewith, sheet metal processing tools may be passed from a first tool magazine that is attached to a fixed unit of the loading and unloading unit to a second tool holder integrated in a sheet metal processing machine or to a tool fixture of the sheet metal processing machine, and, thus, the number of tools automatically exchangeable in the sheet metal processing machine can be increased to create a more efficient and space-saving manufacturing process.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a continuation of, and claims priority under 35 U.S.C. §120 to, PCT Application No. PCT/EP2009/009253, filed on Dec. 23, 2009, which claimed priority to European Patent Application No. EP 08022326.6, filed on Dec. 22, 2008. The contents of both of these priority applications are hereby incorporated by reference in their entirety. 
     
    
     TECHNICAL FIELD 
       [0002]    The invention relates to loading and unloading units and methods for sheet metal processing. 
       BACKGROUND 
       [0003]    Many punching machines include an integrated magazine for storing punching tools used for executing certain machining steps during production of sheet metal parts. During production of sheet metal parts, which typically includes many different machining steps (e.g. punching different shapes, nibbling, thread forming), a large number of different tools are necessary. The storing capacity of tool magazines that are integrated in punching machines is often insufficient to support the many tools used to execute different machining steps. 
         [0004]    There are different possibilities for providing a larger number of tools than that which may be accommodated in conventional tool magazines that are integrated in punching machines. 
         [0005]    In some cases, tools can be exchanged manually (e.g., by an operator) in the tool magazine during breaks in machining processes. However, such manual methods can cause interruptions in the machining process and schedule, and also require manual effort. Therefore, such methods are generally inefficient. 
         [0006]    Another alternative is to include a separate tool magazine in which punching tools are stored so that the punching tools can be automatically exchanged in the tool magazine that is integrated in the punching machine and picked up from the tool holders to be used for machining. However, such an alternative requires additional components of the punching machine and such components correlate to additional costs and enlarged space requirements of the punching machine. Moreover, due to the substantially high number of different machining steps that a given punching machine can be expected to execute during use, the possible number of tools to be stored is often insufficient to ensure an adequate economic production even when a separate standard tool magazine is used. 
         [0007]    Also, in other types of sheet metal processing machines, namely bending machines, an automatic exchange of the tools is possible. The bending tools are also stored in a tool magazine in the bending machine and they are automatically moved to a position to be used in a bending station. However, due to the large dimensions of the bending tools, the cost associated with the bending tools in or at the machine can be more expensive than that of punching tools. 
         [0008]    Further types of sheet metal processing machines in which an automatic tool exchange can be used include combination machines that combine multiple processing capabilities. Examples of such combination machines include punching/bending machines and punching/laser machines. 
       SUMMARY 
       [0009]    In some aspects of the invention, a handling system is provided which automatically exchanges tools within a sheet metal processing machine without creating considerable additional space requirements or requiring substantially larger capital expenditures to be used. 
         [0010]    In some aspects of the invention, a handling system is provided that allows a sheet metal processing device to use the same assemblies for accomplishing different tasks (e.g., to use a sheet metal workpiece loading and unloading unit as a tool handling system). 
         [0011]    The details of one or more embodiments of the invention are set forth in the accompanying drawings and the description below. Other features, objects, and advantages of the invention will be apparent from the description and drawings, and from the claims. 
     
    
     
       DESCRIPTION OF DRAWINGS 
         [0012]      FIG. 1   a  shows a side view of a loading and unloading unit for a sheet metal workpiece with a tool magazine for punching and forming tools; 
           [0013]      FIG. 1   b  shows an enlarged plan view of a rotatable holder with two tool holders; 
           [0014]      FIG. 1   c  is a schematic side view of a sheet metal picking unit with a tool holder gripping a bending tool positioned in a tool holder; 
           [0015]      FIG. 2  is a perspective view of a punching machine; 
           [0016]      FIG. 3  is a perspective view of a bending machine; 
           [0017]      FIGS. 4   a  through  4   c  illustrate tool exchange procedure for a bending machine. 
       
    
    
     DETAILED DESCRIPTION 
       [0018]      FIG. 1   a  is a side view of a loading and unloading unit  1  of a sheet metal processing machine. The loading and unloading unit  1  includes a fixed unit  2 . The fixed unit  2  includes a frame with two vertical stands  3  and a horizontal linear unit  4 . At a movable portion of the horizontal linear unit  4 , a vertical linear unit  5  is provided which is movable in a vertical direction. At its lower end, the vertical linear unit  5  includes a sheet metal picking unit  6 . The sheet metal picking unit  6  includes devices (e.g., gripping fingers, vacuum nozzles, and/or magnets) for picking up sheet metal plates. 
         [0019]    A drive  7  (e.g., an electric motor or actuator) is included in the vertical linear unit  5  for moving the vertical linear unit  5  with the sheet metal picking unit  6  in a first horizontal direction along the horizontal linear unit  5  (X-direction) and for moving in a second horizontal direction (Y-direction). A drive  8  is also included for moving the sheet metal picking unit  6  in a vertical direction. 
         [0020]    Alternatively, one single drive can be included to provide all motion capabilities of the drive  7  and the drive  8 . 
         [0021]    A rotatable holder  9  is provided on the upper side of the sheet metal picking unit  6 . The rotatable holder  9  includes two first tool holders  10  for holding tools  11  used for sheet metal processing (e.g., punching tools). The holder  9  is attached to the sheet metal picking unit  6  so that it is rotatable about a vertical axis  12 . As shown in  FIG. 1   b , when viewed in the direction of the axis  12  (e.g., from the top or the bottom), the tool holders  10  are positioned 90° from each other. However, in some embodiments, the tool holders  10  are positioned at different angles (e.g., 180°) from each other. 
         [0022]    In some embodiments, the rotatable holder  9  includes only one tool holder  10 . In other embodiments, multiple tool holders  10  are positioned side by side in the X-direction along the sheet metal picking unit  6 . In some embodiments, more than two tool holders  10  are included and are arranged around the axis  12  in a revolver-like manner. In some embodiments, in addition to a rotating around the axis  12 , the rotatable holder  9  translates in the Y-direction and/or the first tool holders  10  translate radially relative to the rotatable holder  9 . Also, in some embodiments, tool holders  10  provided side by side at the tool picking unit  6  can translate in the Y-direction. 
         [0023]    Opening and closing movements of the first tool holders  10  to grip tools  11  are typically driven and controlled pneumatically. The rotary movement of the rotatable holder  9  is also typically driven and controlled pneumatically, by a pneumatic rotary drive. Alternatively, in some embodiments, the movements of the tool holders  10  and the rotatable holder  9  are driven and controlled by an electrical drive (e.g. a stepping motor). Such an arrangement can be beneficial when more than two first tool holders  10  are positioned at the rotatable holder  9 . 
         [0024]    In some embodiments, an interface is provided so that the additional weight due to moving the tool holders  10  which are held on the sheet metal picking unit  6  is not always transported during use. This interface can be the joint between the sheet metal picking unit  6  and one of the tool holders  10  or the rotatable holder  9  on which the tool holders  10  are arranged. In some embodiments, multiple interfaces are provided. The interfaces can also be movable in the Y-direction, or movement can be performed by a tool holder fixed to the interface or by the rotatable holder. 
         [0025]    The rotatable holder  9  or the tool holder  10  is fixed at the interface by a magnetic force, a form-fit attachment, or other appropriate techniques. 
         [0026]    A first tool magazine  13  for punching tools is provided between the two vertical stands  3 . Multiple (e.g., six in the illustrated embodiment) second tool holders  14  for punching tools are included in the tool magazine  13 , which are horizontally arranged side by side in the X-direction. As shown in  FIG. 1   a , punching tools  11  are held in the second tool holders  14 . 
         [0027]    In order to provide multiple second tool holders  14 , in some embodiments, the tool magazine  13  includes the second tool holders  14  arranged along several horizontal planes. Alternatively, in some embodiments, the second tool holders  14  are arranged along one horizontal plane and positioned consecutively in the Y-direction. Also, in some embodiments, the second tool holders  14  are arranged side by side in X-direction and Y-direction. 
         [0028]    When used with bending machines, second tool holders  14  suitable for receiving and supporting bending tools are provided, which are also arranged between the two vertical stands  3 . In some embodiments, the first tool magazine  13  for punching tools or the first tool magazine  13  for the bending tools is not integrated in the fixed unit  2 . In such embodiments, the first tool magazine  13  is a separate component of the machine and is arranged in or near the field of motion of the sheet metal picking unit  6 . 
         [0029]    In some embodiments, the first tool magazine  13  is positioned on the sheet picking unit  6 . 
         [0030]    As shown in  FIG. 1   a , a second tool magazine  15  is also included, which will be explained in greater detail below with regards to  FIG. 2 . 
         [0031]      FIG. 1   c  shows a schematic side view of a sheet metal picking unit  6  with a fourth tool holder (e.g., a vacuum nozzle)  39  arranged on the lower side of the sheet metal picking unit  6 . The first tool magazine  13  with the second tool holders  14  and bending tools  11  positioned in the tool holders  14  are also shown in  FIG. 1   c . In some embodiments, multiple fourth tool holders  39  are included on the sheet metal picking unit  6 . The fourth tool holders  39 , while described as vacuum nozzles, can alternatively or additionally be gripping fingers and/or magnets. During use, these multiple fourth tool holders  39  can be used for picking up sheet-metal plates as well as for picking up tools designed in a suitable manner. When using vacuum nozzles or magnets as tool holders, it has been found favorable to use tools having at least one larger flat portion to allow for proper engagement with the tool holder. Including larger flat portions on tools can be especially beneficial when bending tools  11  are used. 
         [0032]      FIG. 2  shows a sheet metal processing machine in the form of a punching machine  21  that is used with or includes the loading and unloading unit  1 . The punching machine  21  includes a C-frame  22  that consists of a torsionally stiff, steel-welded construction. At a rear region of the C-frame  22 , a hydraulic power unit  23  is positioned, by which a ram  25  is hydraulically driven by a ram drive. 
         [0033]    At the lower inside region of the C-frame  22 , a lower tool fixture  24  is positioned for receiving and holding a lower part of a punching tool  11 . The lower part of the tool is rotatable up to 360° using a rotary drive and can be locked and fixed at any desired angular position. 
         [0034]    At the upper inside region of the C-frame  22 , a ram  25  is provided. The ram  25  includes an upper tool fixture to receive and hold an upper part of a punching tool  11  in a form-fit and backlash-free manner. The ram  25  is also rotatable up to 360° and can be locked in any desired angular position. To provide rotation to the ram  25 , a second rotary drive is provided. 
         [0035]    The rotary drives as well as the driving devices  7 ,  8  of the loading and unloading unit  1  are controlled by a machine controller, which is provided in a separate control cabinet. The machine controller also controls a ram controller as well as all of the linear drives for moving a sheet metal plate  26  and actuators for special functions (e.g., to move the part flap  27  up and down). The machine controller includes a keyboard to enable a user to input information and a monitor that can output data to be viewed by the user. The control functions of the drives and actuators are controlled by microprocessors, and machining programs and operation parameters are stored electronically in a storage device of the machine controller. 
         [0036]    At the lower inside region of the C-frame  22 , a table  28  is arranged that includes a cross rail  29  with a linear magazine (i.e., the second tool magazine  25 ). Clamping claws  30  for retaining the sheet-metal plate  26  are arranged along the cross rail  29 . The clamping claws  30  can be arranged at, or relocated to, suitable locations along the cross rail  29  so that the sheet metal plate  26  is safely retained but is not gripped at positions where machining shall be conducted. Multiple (e.g., three in the illustrated embodiment) third tool holders  31  for receiving multiple (e.g., two in the illustrated embodiment) punching tools  11  are included along the linear magazine  15 . In front of the lower tool fixture  24 , the part flap  27  is arranged centrally for transferring outward smaller sheet metal parts. 
         [0037]    During punching operations, the table  28  travels along a programmed range of positions in the Y-direction together with the cross rail  29  on which the clamping claws  30  are arranged to hold the sheet metal plate  26 . The cross rail  29 , along with the clamping claws  30  and sheet metal plate  26 , travels along a programmed range of positions in X-direction, whereby the sheet metal plate  26  slides over the table  28 . Then, with the sheet metal plate  26  in a desired position, a punching stroke is performed by the ram  25 . Subsequently, the sheet metal plate  26  is moved to the next punching position and a subsequent punching stroke can be performed. 
         [0038]    During use, the punching tools  11  are automatically exchanged based on the punching operation to be executed, such exchange being controlled by the machine controller. For exchanging the tools  11  from the second tool magazine  15 , the cross rail  29  is driven by a linear drive along the X-direction so that the position of the tool  11  to be exchanged in the X-direction corresponds to the position of the lower tool fixture  24  in the X-direction. Then, the cross rail  29  travels together with the table  28  in the Y-direction so that a central axis of the punching tool  11  is aligned with a central axis of the lower tool fixture  24  and the ram  25 , so that the punching tool  11  can be held in the lower tool fixture  24  and in the ram  25 . If a tool is positioned in the ram  25  and in the lower tool fixture  24 , this tool is dispensed to a free space in the linear magazine  15  before the next tool is brought to the ram  25  and the lower tool holder  24 . 
         [0039]    For exchanging a tool  11  from the first tool magazine  13  with a tool in the upper tool fixture  25  and the lower tool fixture  24 , first, the necessary punching tool  11  is taken from the first tool magazine  13 . The sheet metal picking unit  6  travels in the X-direction such that the axis  12  of the rotatable holder  9  is aligned with a central axis  17  of the desired punching tool  11 . Subsequently, the sheet metal picking unit  6  travels in the Y-direction so far backwards that the first tool holder  10  may grip the punching tool  11  (i.e., an orifice  16  (referring to  FIG. 1   a ) of the first tool holder  10  can grip the punching tool  11  in a form-fit manner). Then, a closing movement of the first tool holder  10  is performed and the punching tool  11  is removed from the second tool holder  14  of the first tool magazine  13  of the sheet-metal picking unit  6  and moved in the opposite Y-direction by a forward movement. Then, the sheet-metal picking unit  6  travels in X-direction until the central axis  17  of the punching tool is aligned with the central axis of the upper tool fixture  25  and lower tool fixture  24  and, subsequently, the sheet-metal picking unit  6  analogously travels in the Y-direction. Thereafter, the punching tool  11  is received and retained by the tool fixtures  24 ,  25  in a conventional manner. When used in this manner, it is necessary that a free space is available in front of the lower tool fixture  24  because the movement for exchanging tools is typically horizontal. For creating the free space in front of the lower tool fixture  24 , the part flap  27  is moved downward vertically. However, to hinge the part flap  27  to move only downward is insufficient because in this case, the hinge axis of the part flap  27  remains unchanged in the region of collision with the tools to be exchanged in the tool fixtures  24 ,  25 . 
         [0040]    As an alternative to moving the sheet metal picking unit  6  in the Y-direction, in some embodiments, only the first tool holder  10  or the rotary holder  9  travels in Y-direction. 
         [0041]    The first tool holder  10  is typically moved in the Y-direction, however, the movement of the first tool holder  10  is selected such that it moves in relation to the second tool holder  14  so that the punching tool  11  can be taken out of the second tool holder  14  or the punching tool  11  can be delivered to the second tool holder  14 . 
         [0042]    In addition to the respective described methods for changing punching tools  11  of the first tool magazine  13  and the second tool magazine  15  in and out of the tool fixtures  24 ,  25 , other methods for exchanging the punching tools  11  are possible. 
         [0043]    In some embodiments, the punching tool  11  to be exchanged in the second tool magazine  15  is removed from the first tool magazine  13  by one of the first tool holders  10  and then passed to a third tool holder  31  in the second tool magazine  15  in the same manner that a punching tool  11  is placed in the upper tool fixture  25  and the lower tool fixture  24 . When a punching tool  11  is already present in the third tool holder  31  in which the punching tool  11  is to be placed from the first tool holder  10 , the rotatable holder  9  is rotated approximately 90° or the sheet metal picking unit  6  is moved in the X-direction such that another of the first tool holders  10  is positioned to remove the punching tool  11  present in this third tool holder  31 . Subsequently, the rotatable holder  9  is rotated in the opposite direction, here approximately 90°, or the sheet metal picking unit  6  is moved in the opposite X-direction in order to pass the punching tool  11  to be exchanged to this third tool holder  31 . The punching tool  11  that was removed from the second tool magazine  15  can then be either moved to the first tool magazine  13  or it can be inserted in the upper tool fixture  25  and the lower tool fixture  24 . 
         [0044]    Using similar techniques, the punching tools  11  may be removed from the second tool magazine  15  and moved directly to the first tool magazine  13 . 
         [0045]    In some embodiments, in which two or more of the first tool holders  10  are arranged side by side on the sheet metal picking unit  6 , multiple punching tools  11  can be removed from the first tool magazine  13  and moved to the second tool magazine  15  (or removed from the second tool magazine  15  and moved to the first tool magazine  13 ) at the same time. 
         [0046]    Further, depending on the number of the first tool holders  10  arranged side by side on the sheet metal picking unit  6  or the number of the tool holders included on the rotatable holder  9 , several punching tools  11  may be used and positioned in other first tool holders  10 . 
         [0047]    The method for exchanging the punching tools from the first tool magazine  13  may be executed along with the loading the punching machine  21  with a sheet metal plate (i.e., the punching machine can load a sheet metal plate and the desired punching tools at the same time). In this manner, first, the desired punching tools  11  are taken from the first tool magazine  13 , then, the sheet metal plate  26  is removed from a magazine in the region of the fixed unit  2  by gripping devices or vacuum nozzles and the obtained punching tools  11  are moved to the punching machine along with the sheet metal plate  26 . Then, the punching tools  11  are placed in either the second tool magazine  15  or the upper tool fixture  25  and lower tool fixture  24 . The sheet metal plate  26  is placed on the table  28  and moved to a position to be retained by the clamping claws  30 . The unloading of manufactured sheet metal parts may also be executed along with the exchange of punching tools  11  in the first tool magazine  13 . 
         [0048]      FIG. 3  shows a bending machine  33  having a basic structure that is similar to that of the punching machine  21  shown in  FIG. 2  and described above. The bending machine  33  includes an upper tool fixture  34  with a drive  36  and a lower tool fixture  35  as well as a controller. Some machine components (e.g. the tool fixtures  34 ,  35  and the driving device  36 ) are optimized for the bending process using bending tools. As shown in  FIG. 3 , sheet metal  26  is furnished with cut outs  37  which are bent upward using the bending machine to form upwardly bent sheet metal portions  38 . 
         [0049]    The exchanging of additional sheet metal processing tools  11  (e.g., bending tools) from the first tool magazine  13  to the bending machine or out of the bending machine to the first tool magazine  13  may also occur directly in the second tool magazine of the bending machine or directly in the tool fixtures  34 ,  35 . 
         [0050]    In  FIGS. 4   a  to  4   c , the upper tool fixture  34  and the lower tool fixture  35  for bending tools  11  and the sheet metal picking unit  6  with the fourth tool holder  39  (from  FIG. 1   b ) are respectively shown. The bending tools  11  respectively include a lower part (e.g., a 1 , b 1 ) and an upper part (e.g., a 2 , b 2 ). 
         [0051]    A method of exchanging the bending tools out of, and into, the tool fixtures  34 ,  35  is described below. 
         [0052]    As shown in  FIG. 4   a , a bending tool with a lower part a 1  and an upper part a 2  is accommodated in the tool fixtures  34 ,  35 . To begin removing the bending tool, the sheet metal picking unit  6  travels toward the tool holders  34 ,  35  so that the fourth tool holder  39  is located above the lower part al, the fourth holder  39  attaches to the lower part of the tool a 1  (shown in view I), the lower part a 1  is loosened or released from the lower tool fixture  35 , and the fourth holder  39  removes the lower part of the tool a 1  out of the lower tool fixture  35  (shown in view II). 
         [0053]    With the lower part of the tool a 1  removed from the lower tool fixture  35 , a lower part b 1  is inserted in the lower tool fixture  35  using the fourth holder  39  (shown in view III). Once the lower part b 1  is inserted in the lower tool fixture  35 , the lower part b 1  is fixed or fastened in place in the lower tool fixture  35 . 
         [0054]    As shown in  FIG. 4   b , the upper tool fixture  34  having the upper part of the tool a 2  is moved downward to contact the lower part b 1 , which is positioned in the lower tool fixture  35 . Once in contact with the lower part b 1 , the upper part of the tool a 2  is loosened or released from the upper tool fixture  34  so that when the upper tool fixture  34  moves upward and away from the lower tool fixture  35 , the upper part of the tool a 2  remains positioned on the lower part of the tool b 1  (shown in view IV). 
         [0055]    Then, the sheet metal picking unit  6  travels so that the fourth tool holder  39  is located above the upper part of the tool a 2 , which is positioned on the lower part of the tool a 1  picks up the upper part of the tool a 2  (shown in view V). 
         [0056]    With the upper part of the tool a 2  removed from of the machine (shown in view VI), the upper part of the tool b 2  can be moved toward the tool fixture  35  and placed on top of the lower part of the tool b 1  by the sheet metal picking unit  6  and the fourth tool holder  39  (shown in view VII of  FIG. 4   c ). 
         [0057]    To complete the exchange of the bending tool, the upper tool fixture  34  travels downwards and picks up the upper part of the tool b 2  (shown in view VIII). Once the upper tool fixture  34  receives the upper part of the tool b 2 , the upper tool fixture  34  retains the upper part of the tool b 2  and moves back upward (shown in view IX). 
         [0058]    In some cases, the removal of tools from the first tool magazine or the placement of tools into the first tool magazine can be executed in parallel to the production of sheet metal parts. Therefore, while sheet metal is machined in the sheet metal processing machine, a tool can be removed from the first tool magazine or placed in the first tool magazine by the loading and unloading unit  1  for sheet metal workpieces without considerable disturbance of the machining procedure (e.g., punching or bending of the sheet metal). 
         [0059]    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.