Abstract:
The present invention provides a flanging apparatus for metal sheets for use with metal sheets of the body structure in vehicle manufacturing, with a base frame, with a flanging bed movable up and down, and with flanging jacks movable into the work area of the flanging bed. The invention consists of the fact that a flanging tool has the main, workpiece-specific components, in particular the flanging bed and flanging jacks, and is arranged in the base frame as an exchangeable unit.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    This invention relates generally to forming materials and more particularly to hemming or flanging of metal sheets. A hemming or flanging process forms a flange on the edge of a metal sheet. Folding the formed flange onto the metal sheet conceals the cut edge and completes the hem.  
           [0003]    2. Description of the Related Art  
           [0004]    A device for flanging metal sheets is disclosed in DE 19801561. In this patent, an electro-mechanical operation of the flanging bed for the displacement stroke between the flanging jacks and the operating stroke is proposed. The flanging jacks are placed in a pivoting manner at the machine frame and are moved by means of pneumatic cylinders. For a tool change, the flanging jacks, flanging bed, and hold-down clamps must be individually assembled, disassembled, and adjusted. These operations are very time consuming and lead to very long downtimes when a change is required. Maintenance work requires the same laborious operations and the flanging device remains inoperative during any preventive maintenance procedures.  
           [0005]    Electro-mechanical drives have also been used to improve upon some of the noise characteristics associated with the hydraulic drives of flanging devices. DE 19747291 discloses a device for folding metal sheets that performs the work stroke by means of pneumatic air cushions with the air cushions acting directly on the ram for the folding process. A disadvantage of this design is that the folding device is a component of the drive unit thereby involving the drive unit during a tool change.  
           [0006]    There exists a need for a hemming flanging device that reduces maintenance time and simplifies the flanging tool change procedures.  
         SUMMARY OF THE INVENTION  
         [0007]    Accordingly, the present invention overcomes the problems of the prior art by providing an apparatus for flanging together metal sheets in a manufacturing process. The apparatus comprises a base frame, a flanging bed operative to move from a first position to a second position, and a flange drive operative to move said flanging bed. A flanging jack is disposed upon the flanging bed. The apparatus further includes an exchangeable flanging tool, the tool including the flanging bed and flanging jack, mounted on the base frame as well as a flanging tool base including slidable members therein. The exchangeable flanging tool is disposed on the slidable members such that a first exchangable flanging tool can be slidably removed and replaced by slidably moving a second exchangeable flanging tool into place.  
           [0008]    It is advantage of the current invention to simplify drive maintenance procedures by incorporating the main flanging tool-specific components, especially the flanging bed and the flanging jacks, into the flanging tool and mounting the tool on the base frame as an exchangeable unit.  
           [0009]    Furthermore, it is an advantage of the current invention to establish the flanging tool as an independent, transportable unit. The tool maintains its workpiece specific settings and adjustments regardless of whether it is located in the flanging device. Thus, for tool maintenance and tool change, the flanging tool can be quickly and easily removed from the flanging device and replaced by another flanging tool.  
           [0010]    These and other advantages of the present advantage will become readily apparent in the figures, detailed description, and claims that follow. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0011]    [0011]FIG. 1 is a side cross sectional view of the flanging apparatus according to the present invention.  
         [0012]    [0012]FIG. 2 is a side cross sectional view of a flanging drive with compressed-air cushions according to the present invention.  
         [0013]    [0013]FIG. 3 is a side view of a flanging apparatus according to the invention with change tables.  
         [0014]    [0014]FIGS. 4 a - 4   c  are views of the flanging tool of the present invention during a flanging operation on the upper flanging jacks.  
         [0015]    [0015]FIG. 5 is a top view of a flanging tool of the present invention during a displacement stroke.  
         [0016]    [0016]FIG. 6 is a side view of a flanging tool during the flanging operation on the lower flanging jacks. 
     
    
     DETAILED DESCRIPTION  
       [0017]    [0017]FIG. 1 illustrates the flanging device according to the present invention, comprising two main components: the main base frame  1  and the flanging tool  2 . The main base frame  1  includes a base frame  3  as the central element for receiving flanging lifters  5  for the flanging movement led with slide plates  4 . A service (or maintenance) peg  6  for the flanging lifters  5  allows fixing the flanging lifters  5  during maintenance actions. A bottom plate  7  is designed for attaching the flanging device to the floor. In the upper part of the main base frame  1 , the base frame  3  is closed off with a frame cover plate  8 . The frame cover plate  8  houses tensioning and centering units  9  for the flanging tool  2 . An opening  10  in the frame cover plate  8  is used to load the flanging tool  2  with the workpiece  11 . A piercing tool pickup  12  for the receiving the flanging tool  2  in the main base frame  1  is situated between the base frame  3  and the frame cover plate  8 . Thus, the flanging tool  2  can be pushed in and out of the base frame from any side depending on the tool-exchange time required. As will be described in more detail below, the flanging tool  2  can be tensioned in the base frame as a manual bolted connection, or fully automatically by means of electro-mechanical tensioning elements. Exchange tables are situated in the base frame on one or both sides of the tool pickup to receive the flanging tool during the exchange. There, the flanging tools can be serviced directly, or they can be prepared for further transportation. The devices for the removal or insertion of the flanging tools are also located in the exchange tables.  
         [0018]    The flanging tool  2  consists of a frame comprising a base plate  13 , a cover plate  14 , and spacers  15  located on the four corners of the tool frame. The alignment and the attachment of the flanging tool  2  in the main base frame  1  occur by means of tensioning and centering units  9 . Movable flanging slides  16  include 45° flanging jacks  17  for pre-flanging and 90° flanging jacks  18  for finish-flanging and are placed between the base plate  13  and the cover plate  14 . In its center, the base plate  13  has an aperture  19  of at least the same size as the flanging bed  20  through which the flanging tool can be loaded with the workpiece from above. The flanging bed  20 , which receives the workpiece  11 , is placed loosely in the flanging tool  2  and tightly attached to the flanging lifters  5 . During the flanging process, the workpiece is held onto the flanging bed  20  by a hold-down clamp thereby allowing the hold-down clamps to be built into the flanging tool, or allowing the function of the hold-down clamp to be fully taken over by a robot arm, which also loads the workpiece on to the flanging device. Also during the flanging process, the flanging bed is led by the flanging lifters  5  and also moved by a power stroke device. A flanging drive device  21  acting on the flanging lifters  5  is placed on the bottom plate  7  of the main base frame  1 . The flanging lifter  5  is situated in the base frame  3 , and transmits the propulsion force to the flanging bed  20 , the flanging lifter  5  to be activated hydraulically, pneumatically or electro-mechanically. The flanging bed  20  is tightly connected with the flanging lifter  5 , and the connection is further secured with a threaded connection or an automatic interlock. The flanging bed  20  is centered during the first stroke of the flanging lifter following the installation of the flanging tool.  
         [0019]    An electro-pneumatic drive variant with a spindle stroke device, shown in detail in FIG. 2, is provided for the flanging drive device  2 l. The entire construction of the flanging drive  21  is modular so that flange drive unit  21  can be exchanged within the main base frame  1  easily. To that end, the flanging drive  21  has a flanging drive base plate  22 , which is bolted to the base plate  7  of the main base frame  1 . Compressed-air cushions  24  are disposed between the flanging drive base plate  22  and an operating stroke base plate  23 . The cushions  24  execute the smaller work stroke for the flanging process by lifting the operating stroke base plate  23 . A double post guide  25  is provided for the exact alignment of the flanging drive base plate  22  and the operating stroke base plate  23 . A uniform distance of the two plates in rest position is guaranteed by spacers  26 . In this way, the electrically driven spindle-stroke device provides the large displacement stroke between the flanging jacks. The one or several compressed-air cushions (pads) provides a means for actuating the small work stroke for the flanging process, whereby the spindle stroke device is protected by a locking mechanism during its working stroke against any spindle damage. The spindle jack, resting upon the flanging bed, is a component of the spindle stroke device and the entire spindle stroke device, including its locking mechanism, is placed on the compressed-air cushions and moves along with each work stroke. Since the compressed-air cushions are located on the floor of the base frame, the flanging jack can be of considerable height. The resulting long guide tracks between the flanging lifter and the base frame ensure the guidance of the flanging lifter even during alternating load-application points, due to the workpiece tolerances or different flanging tools.  
         [0020]    The displacement stroke between the flanging jacks  17  is executed through the spindle advance device  29  located on the working stroke base plate  23 . An electric motor  27 , a transmission  28  and a driven spindle  29  cooperatively lift or lower the flanging lifter  5 ″ according to the desired displacement stroke. For the duration of the work stroke, during which great forces are produced, the spindle  29  is locked into a fixed position by a locking mechanism. The locking mechanism consists of two or more spacer blocks  30  mounted in a movable manner on the work stroke plate  23 , which, by means of positioning devices  31  are pushed under the flanging lifter  5 ″ in such a way that they support either an upper shoulder  32  or a lower shoulder  33  of the flanging lifter  5 ″ and thus transmit the main forces of the work stroke. The interface points of the transmission of the drive loads are modular so that the same drives can be used without any changes for various flanging tools.  
         [0021]    [0021]FIG. 3 shows a view of the flanging device with change tables  34 . The change tables  34  permit the flanging tools  2  to shift to the right or to the left from the main base frame  1 . While a flanging tool  2  is in the main base frame  1  and the flanging device is operating, a flanging tool  2 ″ located on the change table  34  can be serviced, adjusted or prepared for use. The necessary work on the first flanging tool is performed outside the flanging device, while the flanging device can process a different workpiece with another flanging tool. After the new or repaired flanging tool has been inserted and secured in the base frame, the flanging device is again quickly ready for use.  
         [0022]    [0022]FIGS. 4 a - 4   c  show various work steps in the flanging device  2 . FIG. 4 a  shows the step of pre-flanging of the workpiece  11 . The flanging bed  20  is located at the height of the 45° flanging jacks  17 , located on the flanging slides  16 . By releasing a small flanging stroke, pre-flanging of the workpiece  11  is activated.  
         [0023]    [0023]FIG. 4 b  shows the flanging tool  2  during the displacement stroke. The flanging slides  16  are driven outwardly and thereby all the flanging jacks  17 ,  18  are removed from the work area of the flanging bed  20 . The spindle stroke device lifts the flanging bed  20  to the finish-flanging position, as shown in FIG. 4 c . There, the flanging slides  16  return the flanging jacks  17 ,  18  into the work area of the flanging bed  20 . By executing the work stroke, the workpiece  11  is finish-flanged on the 90° flanging jacks  18 .  
         [0024]    [0024]FIG. 5 shows a top plan view of the flanging sliders and their layout in a flanging tool  35  according to the present invention. Flanging jacks  36 , which follow the contour of the workpiece  11 , can be moved in the operating area of the flanging bed, and are attached to flanging sliders  37 ,  38 . The drives  39  of the flanging jacks  36  are arranged on the sides of the frame cover plate  8  and transmit a compressive force directly onto the flanging tool  35 . For the laterally placed flanging sliders  37 , this driving force can be converted in a direct, straight-line movement in the operating area of the flanging bed  20 . A retrieving mechanism  40  is provided for the return of the flanging jacks  36  that produces the return forces by means of pressure springs, compressed-air cylinders or other. Because of this type of energy transfer, no additional connections between the flanging sliders and the flanging drives are required during the assembly of the flanging tool; the positioning of the flanging tool in the established assembly position in the base frame is sufficient.  
         [0025]    The flanging sliders  38  located on the front side move in a direction perpendicular to the drives  39 . The drives  39  first act on auxiliary sliders  41  which produce the required movement of the flanging sliders  38  in the operating area of the flanging bed  20  via an inclined plane  42 . The retrieving mechanism  40  is provided for the return of the flanging sliders  38 .  
         [0026]    [0026]FIG. 6 shows, for simple service actions on the flanging tool  2 , the flanging bed  20  in service position  43  lowered in the main base frame  1 , and then a flanging tool  2  without the flanging bed  20  being disposed on the change table  34 . A position sunk in the main base frame  1  is provided for the flanging bed  20  for the maintenance of the flanging jacks allowing the flanging tool to be removed from the base frame without the flanging bed. This facilitates the access to the flanging jacks  17 ,  18  and flanging slides  16 , and allows for quick maintenance work. If the flanging tool  2  is again taken in the main base frame  1 , the flanging device is quickly ready for work. As can seen, it is an advantage of the present invention to establish the flanging tool as an independent, transportable unit. The tool maintains its workpiece specific settings and adjustments regardless of whether it is located in the flanging device. Thus, for tool maintenance and tool change, the flanging tool can be quickly and easily removed from the flanging device and replaced by another flanging tool. The necessary work on the first flanging tool is performed outside the flanging device, while the flanging device can process a different workpiece with another flanging tool. After the new or repaired flanging tool has been inserted and secured in the base frame, the flanging device is again quickly ready for use.  
         [0027]    It will be realized, however, that the foregoing specific embodiments have been shown and described for the purposes of illustrating the functional and structural principles of the invention and is subject to change without departure from such principles. Therefore, this invention includes all modifications encompassed within the scope of the following claims.