Abstract:
The invention relates to a tilting system which comprises a tilting unit having an actuator. Said actuator has a slide which can be moved to and fro in a direction of displacement. The front of the slide is provided with a tilting molding segment for shaping the flared flange of a metal sheet.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a U.S. National-Stage entry under 35 U.S.C. § 371 based on International Application No. PCT/EP2005/006122, filed Jun. 8, 2005, which was published under PCT Article 21(2) and which claims priority to German Application No. DE 10 2004 031 290.7, filed Jun. 29, 2004. 
     
     BACKGROUND 
       [0002]    The invention relates to the handling of workpieces when carrying out machining processes, in particular when flanging. 
         [0003]    Flanging, also called seaming, comes under the method area of non-cutting shaping technology. This is taken to mean the tilting of a bent edge or a flange portion of an outer metal sheet or a skin over an inner metal sheet or over a frame. The point of flanging is to connect two sheet metal parts or the skin and frame rigidly to one another optionally using adhesive. In automobile construction, the method is generally used on vehicle components, such as the bonnet, door, rear door, boot lid and roof. 
         [0004]    The contour of the component is determined during the flanging. A distinction is made between inner and outer flanging. During outer flanging, the outer contour of the component, such as, for example, bonnet, door, rear wall door and boot lid are established. In the case of inner flanging, the contour of the window cutouts, such as the roof, or door, are established. 
         [0005]    Flanging decisively influences the installation quality of the components in the bodywork with regard to gap dimension and inclination. Flanging is frequently carried out in two to three stages or steps. Tilting, pre-flanging and final flanging are then referred to. 
         [0006]    There are several different flanging systems. In one flanging system, the finished part is moved in a special holding device, the so-called “flanging bed” against a fixed tool. In another flanging system, the production part is located rigidly in a mould and the tools move. In this case, it is also known to carry out flanging using a movable and rotatable roller, this is called “roller flanging.” 
         [0007]    Flanging devices are driven pressing tools in the broader sense. The systems are frequently driven hydraulically, pneumatically or electrically. Because of the necessary contact pressure, the ram, which provides the working lift, is preferably moved hydraulically. Flanging jaws can be moved hydraulically, pneumatically or electrically via servomotors. 
         [0008]    A flanging bed frequently forms the receiving tool for the outer skin and frame. It is the precise three-dimensional shape representation of the outer skin and therefore the basic requisite for the required inclination quality. The bed is regarded as a base or zero reference and needs no subsequent machining or adjustment. 
         [0009]    The flanging jaws or seaming blocks produce an open or else completely closed ring in their working position. The actual shaping takes place at the flanging jaws or seaming blocks, as the flanging positions are installed therein for preflanging and final flanging. The rows of jaws are arranged one above the other in a two-stage flanging device, in a one-stage device, only one row of jaws is assembled either for preflanging or final flanging. The criterion for one or two stages is the clock cycle of the production cell in conjunction with the type of drive of the device. Two-stage flanging devices are frequently used. 
         [0010]    In the case of two-stage systems, preflanging jaws and final flanging jaws are used one after the other. The flanged portion is tilted over at the seaming blocks by the hydraulic lifting of the ram. 
         [0011]    The two components, frame and skin, are positioned with forced position adapters and locating bolts according to the basic alignment bores (ASKF). Holding-down devices can ensure that the frame rests, true to shape, on the outer skin prior to the flanging process. With a holding-down device, the frame is pressed onto the skin and therefore in the shape of the flanging bed before and during the flanging process. Contour errors are thereby minimized and the desired overlapping of the flaring flange over the frame is ensured. 
         [0012]    EP 0 820 822 A1 and WO 97/43165 show machine tools of the type which are used for seaming or flanging of metal sheets. 
         [0013]    In these machine tools, it is a drawback that they are constructed expensively and in a complicated manner. Furthermore, flanging can only take place after a precise adjustment of the different parts of the machine tool so that optimum results are achieved. 
       SUMMARY 
       [0014]    The handling of workpieces when carrying out machining processes is to be simplified and the work result improved with the invention. 
         [0015]    The invention does not provide, for example, a flanging device constructed in a complicated manner or changed holding-down devices, as would be inherently conceivable, in order to achieve a better work result. Rather, a simplification of the previously used tilting devices is provided. For this purpose, at least one standard drive element and a slide, which has a tilting molding jaw on its front side, are used. The flanged portion of a metal sheet is machined thereby. Pneumatic cylinders, hydraulic cylinders, an armature of a coil or else a spindle of an electric drive are used as drive elements. These drive elements may be operated without an additional gearing or without a large articulated lever mechanism being interposed. 
         [0016]    It has been found that the invention facilitates and improves the tilting, in which only “critical regions” are machined on a separate tilting device (first stage). The preflanging and final flanging only take place afterwards on the actual flanging press (second and third stage) and machines the complete flanged portion of the outer contour. 
         [0017]    “Critical regions” may be present in part sections with very small radii, large aperture angles (greater than about 116°) and also in parts, in which the flanged portion has to be flanged differently from a predetermined flange position. An undesired material advance in the flanging press is avoided with the invention. 
         [0018]    In addition, in the case of radii or flanged portion angle positions of less than about 116° and in the case of an unfavorable shape course at the contour, even depending on the position of the component in the flanging bed, there is the possibility that there is no joining of the frame to the skin by means of an “overhead” or robot. It has also proven successful to tilt according to the invention in such areas. 
         [0019]    The invention avoids tilting units which are constructed in a complicated manner and which contain expensive weld constructions rotated in three axes. These constructions require very expensive constructions and CAD investigations and have not proven successful. 
         [0020]    According to the invention, brackets for holding the tilting unit are provided and are a component of the flanging bed. Cast-on brackets have proven particularly successful, in this case. Guides for the slides can already be produced in a clamping mechanism, in this case, during the shaping of the flanging bed. Tilting devices which are particularly simple to produce can be provided with the invention and are substantially more economical than those of the prior art. A cost saving of up to 40% per tilting device can be counted on. 
         [0021]    This is particularly noticeable because numerous tilting units, frequently between six and ten, are to be provided on many tilting devices. In the protruding tilting devices of the prior art, this number could frequently not be provided due to lack of space, so a poor result with less tilting devices had to be accepted. 
         [0022]    The invention is also implemented in a machine tool configured as a machining device, which has the tilting unit according to the invention. Using the tilting unit, a flanging edge of a sheet metal skin is locally bent over, for example at a point, which would cant in an unintended direction during subsequent flanging. Furthermore, a tilting unit according to the invention is provided at a point, at which particularly small bending radii are to be produced. 
         [0023]    The invention allows a favorable and not very expensive overall construction. A standardization of the tilting units within a tilting system is possible with the invention. The systems are no longer component-dependent and are the same from model to model. 
         [0024]    Using the tilting system according to the invention, the skin is tilted in a simple manner in the region of the flanged portion, and a desired overlapping of the flanged portion, for example, over the frame, is thus ensured. 
         [0025]    The tilting systems according to the invention are provided on mechanically not very complex constructions. The mechanical construction specifications allow a low overall construction height and width. The assembly is very simple owing to the small size of the system. Tilting drives, which are assembled on a holding frame projecting for a long way over the flanging device, no longer need to be provided. 
         [0026]    Using the tilting system according to the invention, the skin is tilted in a simple manner in the region of the flanged portion, and a desired overlapping of the flanged portion, for example over the frame is thus ensured. 
         [0027]    A conceivable flanging process using a tilting device according to the invention is described below. 
         [0028]    All the tilting units of the tilting device are in the basic position, i.e. in the rear end position. 
         [0029]    The two components, frame and skin, are inserted and positioned with forced position adapters, positioning and marking bolts, according to the basic alignment bores (ASKF). The frame is pressed into the skin and therefore also into the bed of the tilting device by means of clamps. In the critical regions, holding-down devices pivot, true to position, into the roots of the flanged edge of the outer skin and hold them in the sense of a tilting jaw. By means of the pneumatic cylinder, the slide with the molding jaw placed thereon is then moved against the flanged portion up to the end position. The necessary dimension adjustment takes place via a threaded spindle at the piston rod. The pneumatic cylinder, the holding-down device and centring devices move back into the basic position. The tilting process is thus completed and the part is taken out of the device and inserted in the flanging press for further machining. 
     
     
       BRIEF DESCRIPTION OF THE DRAWINGS  
         [0030]    The present invention will hereinafter be described in conjunction with the following drawing figures, wherein like numerals denote like elements, and 
           [0031]      FIG. 1  shows a side view of a part region of a tilting device according to the invention, 
           [0032]      FIG. 2  shows a part region of a steel sheet to be flanged, and 
           [0033]      FIG. 3  shows a further part region of the tilting unit according to the invention from  FIG. 1 . 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0034]    The following detailed description of the invention is merely exemplary in nature and is not intended to limit the invention or the application and uses of the invention. Furthermore, there is no intention to be bound by any theory presented in the preceding background of the invention or the following detailed description of the invention. 
         [0035]      FIG. 1  shows a side view of a tilting device  1  according to the invention. The tilting device  1  is composed of a flanging bed  2  with a cast-on bracket  17  for a slide  7 , in a weld construction  3  for receiving a pneumatic cylinder  5 , a molding piece  9 , a guide  4  and a piston rod with an adjustment unit  6 . 
         [0036]    A steel sheet skin  14  is placed on the flanging bed  2 . The weld construction  3  is a holder for the pneumatic cylinder  5  and is fastened on the bracket  17  configured as a gating. 
         [0037]    A machined upper side  13  of the bracket  17  is used in this case as a support for the guide  4  of the slide  7 , which is connected to the piston rod  6  of the pneumatic cylinder  5 . A molding jaw  9  is provided on the front side of the slide  7 . 
         [0038]      FIG. 2  and  FIG. 3  illustrate the shaping of a flanged portion  10  of the steel sheet skin  14 . 
         [0039]    As is seen in  FIG. 2 , the flanged portion  10  of the steel sheet skin  14  is bent to an angle of more than 116° prior to actuating the tilting unit  1 . After the tilting process, the flanged portion  10  is further bent down, specifically to an acute angle of about 70°. This state is shown by a dashed line. 
         [0040]      FIG. 3  illustrates, in this case, the effect of the molding jaw  9  during a displacement along the displacement direction  8 . As can be seen particularly well in  FIG. 3 , the front side of the molding jaw is machined such that the desired angle position of the flanged portion  10  is achieved after a lift of the molding jaw  9 . In this case, the holding-down device  11  not shown in  FIG. 1  contributes to an optimum flanging result. 
         [0041]    Sliding force-amplifying articulated levers on any actuators are dispensed with the invention, so the tilting unit  1  according to the invention, can be implemented in a particularly small installation space and with a direct action of force. 
         [0042]    The machine tool according to the invention can be produced particularly simply. 
         [0043]    Assembly faces for guiding the slide  9  are cast on the flanging bed  2  cast from steel in the region of the tilting devices or tilting units to be provided, according to the number of “critical regions” of the steel sheet skin  14 . The number of tilting units is to be determined, in each case, depending on the component. These assembly faces are also machined simultaneously during the shaping of the flanging bed  2  which only entails a slight additional expenditure in relation to the previous production. Guide strips with emergency running properties are assembled on these assembly faces. Screw-on faces for the weld construction for receiving the pneumatic cylinder are also simultaneously machined to the gating or the bracket  17 . The slide  9  and the holding-down device  11  are produced according to CAD/CAM data. 
         [0044]    Tilting forces of more than 4,500 N can be produced in a simple manner with the pneumatic cylinder  5  shown in  FIG. 1 . The necessary transverse force is determined depending on the component. In this case, the smallest possible adjustment angle of the flanged portion  10  is aimed for. An exact adjustment or tilting is ensured with the flanging device according to the invention, so a more precise flanging edge course is produced. For this purpose, a molded piece in the form of a holding-down device  11  is pressed into the so-called “root”  12 . 
         [0045]    In the root  12 , this holding-down device  11  prevents the undesired rolling in or pulling in of the steel sheet skin during the tilting process, so the development of bulges is counteracted. The holding-down device  11  can be operated with a pivoting clamping cylinder, not shown here, with a hydraulic cylinder, with a pneumatic cylinder, electrically or with any type of mechanical actuation. The corresponding pressing force is determined according to the respective requirements. The installation of the holding-down devices may be both inside and outside the flanging bed  2 . It is also conceivable to simultaneously also incorporate the pivot point or the fastening point of the holding-down device  11  in the casting mould of the flanging bed  2 . Finally, a weld construction is also conceivable as the carrying component of the holding-down device drive. 
         [0046]    While at least one exemplary embodiment has been presented in the foregoing detailed description of the invention, it should be appreciated that a vast number of variations exist. It should also be appreciated that the exemplary embodiment or exemplary embodiments are only examples, and are not intended to limit the scope, applicability, or configuration of the invention in any way. Rather, the foregoing detailed description will provide those skilled in the art with a convenient road map for implementing an exemplary embodiment of the invention, it being understood that various changes may be made in the function and arrangement of elements described in an exemplary embodiment without departing from the scope of the invention as set forth in the appended claims and their legal equivalents.