Abstract:
The invention relates to a pull-down fastening device for objects having bores, with a fastening unit which includes a fastening element. A pull-down fastening device should be claimed, with which the various fastening processes can, when necessary, be performed. For this purpose, the pull-down fastening device features a modular interchangeable fastening insert which insert includes a fastening element. Such pull-down fastening devices engage into bores of, for example, pallets or workpieces to be processed, for the purpose of interior fastening.

Description:
[0001]    This application is based on German patent application number DE 10 2007 038 656.9. 
       BACKGROUND OF INVENTION 
       [0002]    1. Technical Field 
         [0003]    The invention relates to a pull-down fastening device for fastening objects having bores, with a fastening unit which includes a fastening element. 
         [0004]    2. Related Art 
         [0005]    These kinds of pull-down fastening devices are used for interior gripping or fastening in bores of objects. For example, pallets or workpieces to be processed can be fastened in this manner. 
         [0006]    German Patent DE 10 2004 006 213 B3 shows this kind of a pull-down fastening device with which objects can be fastened at a defined fixed point or zero-point. For this purpose, the fastening element is directed quite snugly within the fastening unit. There are also, however, pull-down fastening devices by which the fastening elements enable an adjustment, so that the tolerances can be balanced out with the inner bore to be fastened. Some of these kinds of adjustment options are designed to be one-dimensional, so that the fastening element can move in one direction. There are also, however, pull-down fastening elements which enable two-dimensional adjustment. 
         [0007]    The unfortunate aspect of pull-down fastening elements generally is that for the different kinds of fastening-namely, either zero-point fastening, or one- or two-dimensional adjustment-there are different building principles and therewith also dimensions between the individual elements. To correct fastening on the side of or in the workpiece, elements of great dimensions are normally required at the activity site. Through various functioning principles, a uniform design of the fastening bore inside the workpiece is impossible or at least very difficult. 
         [0008]    The underlying problem of the invention is to claim a pull-down fastening device with which the various fastening processes can, when necessary, be performed. 
       SUMMARY OF INVENTION 
       [0009]    The problem with the pull-down fastening device of the above-mentioned type is solved through a modular interchangeable fastening insert, which includes the fastening element. In this way, the same fastening unit with modular interchangeable fastening inserts can be used with the pull-down fastening device with the inventive features. Through the selection of the desired fastening units, the desired fastening technology can be obtained. One receives such a uniform foundational module commensurate with the present element construction size, which module is suitable for a conversion between fixed-point and balancing-point fastening by means of changeable inserts. Only small dimensions at the activity site are required, and it allows a cost-effective fastening ring to be used as a contact element to the workpiece. Further advantages following from the invention are an improved sealing of the system against penetration of filth, and simple maintenance. 
         [0010]    A further improvement of the invention features several varied fastening inserts. Due to these several varied fastening inserts, for every fastening technology, the suitable fastening insert holds itself ready so that the modular switch can take place quickly and comfortably. 
         [0011]    Preferably, the fastening element is firmly connected with the fastening insert. In this way, a fixed position of the fastening site arises simply and surely-the so-named zero-point. 
         [0012]    It is, however, also possible that the fastening element is movably connected with the fastening insert. For example, the fastening element can be swivelably connected with the fastening insert about an axis perpendicular to the fastening direction. In this way there arises simply and functionally an adjustment option for the position of the fastening bore during fastening. 
         [0013]    An advantageous embodiment of the invention features the fastening insert being equipped for replacement or re-positioning into a starting position when the fastening is released. In this manner, an adjustment by fastening is on the one hand possible, whereby the fastening insert is always re-positioned or replaced at the starting position for the arranging of the workpiece on top of the pull-down fastening device. In this manner the arrangement of a workpiece on top of the pull-down fastening device is facilitated. 
         [0014]    Another improvement of the invention features the fastening element including a fastening ring and a tie-rod. Preferably the fastening element includes, in addition to that, a tapered insertable collar, which has a cone or taper corresponding to and designed to interact with the fastening ring. In this way, the fastening ring can, through the pulling down of the tie-rod by means of the cone, be expanded for fastening. In addition to that, it is advantageous when a bushing is designed for the tapered insertable collar. The bushing can, for example, ensure a secure fit of the tapered insertable collar. In this manner, zero-point fastening is advantageously supported. It is however, also possible that the bushing enables an adjustment to the tapered insertable collar. For example, the bushing can enable a one- or two-dimensional adjustment to the tapered insertable collar. In connection with the moving connection between the fastening element and the fastening insert there arises such a simple, effective, yet reliable balancing mechanism with a simultaneous reliable fastening effect. 
         [0015]    In another embodiment of the invention, the fastening unit has a drive piston, in particular, a hydraulic drive piston. Utilization of this kind of drive piston can generate a large amount of reliable and simple fastening strength. In one improvement, the drive piston is arranged parallel to the fastening insert. Since in this case the piston movement and the fastening movement of the fastening insert are parallel, an especially thin structure can be obtained. It is, in addition, advantageous when the drive piston is mechanically coupled with the fastening insert, in particular, when the drive piston is positively coupled therewith. Thereby, a good coupling and a solid power transmission can be obtained. Advantageously, the drive piston can be coupled with the fastening insert by means of a pin. A coupling of this kind can be easily disassembled, and after the change of the fastening insert, put firmly back together. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0016]    Following, examples of embodiments of the invention will be explained in more detail, wherein: 
           [0017]      FIG. 1  depicts a perspective top view and a front view of a pull-down fastening device with the inventive features; 
           [0018]      FIG. 2  depicts the cross-section A-A of  FIG. 1  and a detailed presentation of the fastening insert from  FIG. 1 ; 
           [0019]      FIG. 3  depicts a second example of an embodiment, similar to  FIG. 2 ; and 
           [0020]      FIG. 4  depicts a further example of an embodiment, similar to  FIG. 2 . 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0021]      FIG. 1  shows in the upper part a perspective top view of a pull-down fastening device  10  as a first example of an embodiment with the inventive features. In the lower part,  FIG. 1  shows a front view of the pull-down fastening device  10 . As can be inferred from the figure, the pull-down fastening device  10  includes a fastening unit  11  with a fastening element  12  arranged therein. The fastening element  12  has a tie-rod  13  on to which a nut  14  is screwed. On the underside of the nut  14  a fastening ring  15  is arranged, which engages with a tapered insertable collar  16  for the purpose of fastening. The tapered insertable collar  16  is in turn arranged in a bushing  17  for the purpose of fastening. In the figure, a bored hole  18  is indicated by broken lines in a workpiece represented from farther away. For the purpose of fastening inside of the bored hole  18 , the tie-rod  13  is moved downward in the figure, in a known way. When the tapered insertable collar  16  is hit inside of the bushing  17 , the tapered insertable collar  16  and the fastening ring  15  are forced apart. Through the separation of the fastening ring  15  inside of the bore  18 , the workpiece is then firmly fastened. 
         [0022]      FIG. 2  shows the cross-section A-A from  FIG. 1 . In addition, in the upper part of  FIG. 2  the fastening element  12  is depicted in a detailed presentation. As can be inferred from the figure, the fastening element  12  is fashioned as a part of a fastening insert  19 . In the detailed depiction of the fastening insert  19 , it should also be recognized that the tapered insertable collar  16  facing the fastening ring  15  includes a cone  20  for the purpose of spreading apart the fastening ring  15 . In addition, an O-ring  21  is arranged in a groove of the tapered insertable collar  16 , surrounding the tapered insertable collar  16 . 
         [0023]    The fastening insert  19  also includes a fastening body  22  with a body-threaded portion  23 , which threadably engages the tie-rod-threaded portion  24  on the end of the tie-rod  13  being spaced away from and not facing the nut  14 . In particular, the tie-rod  13  is by means of the threaded portions  23 ,  24  firmly connected with the fastening body  22 . In can further be inferred from  FIG. 2  that the fastening body  22  includes a bore  25  perpendicular to the tie-rod  13 . 
         [0024]    As can be inferred from the portrayed cross-section A-A at the bottom of  FIG. 2 , a drive piston  26  is arranged in the fastening unit  11 , which can be pressurized with a hydraulic liquid. The drive piston  26  is arranged parallel to the fastening insert  19  and is connected with the fastening body  22 . In particular, the drive piston  26  is mechanically, especially positively, connected with the fastening body  22 . As can be inferred from the Figure the drive piston  26  is connected to the fastening body  22  by means of a pin  27 . 
         [0025]    According to the present embodiment, the tie-rod  13  is firmly connected with the fastening body  22 . Similarly, the tapered insertable collar  16  is firmly mounted inside the bushing  17 , and the tie-rod  13  is directed quite snugly within the tapered insertable collar  16 . In this way, by means of the fastening insert  19  and the bushing  17 , a so-named zero-point fastening is accomplished, by which the bore  18  is snugly fastened in a defined position to the pull-down fastening device  10 . 
         [0026]      FIG. 3  shows a second example of embodiment of the pull-down fastening device  10  with inventive features. The same elements carry the same reference numbers. In the present example of embodiment, into the fastening unit  11  is inserted a fastening insert  28  instead of the fastening insert  19 . The fastening insert  28  can be seen in detail in the upper part of  FIG. 3 . As can be inferred from the Figure, the fastening insert  28  includes a fastening element  29 , similar to the fastening element  12 . The functionality of the fastening element  29  is essentially the same as that of fastening element  12 . But, unlike fastening element  12 , fastening element  29  has a tapered insertable collar  30  similar to the tapered insertable collar  16 , a tie-rod  31  and a fastening body  32 . In this example of embodiment, the tie-rod  31  is movably connected with the fastening body  32 . In particular, the tie-rod  31  is connected with the fastening body  32  by means of a swivel connection. As can further be inferred from the Figure, the fastening unit  11  includes a bushing  34 , similar to the bushing  17 . The bushing  34  is different from the bushing  17  in that an adjustment of the tie-rod  31  is possible for the purpose of fastening. In particular, the connection  33 , and the combination of the tapered insertable collar  30  and the bushing  34 , facilitates a swiveling motion of the tie-rod  31  about an oriented axis in the ambit of the connection  33  transverse to the tie-rod  31 , which is not represented in the figure and lies in the plane of the paper. 
         [0027]      FIG. 4  shows a further example of embodiment of the pull-down fastening device  10  with inventive features. In the bottom part of  FIG. 4  the cross-section A-A can again be seen, while in the above part a fastening insert  35  similar to the fastening inserts  19 ,  28  is shown in detail. The fastening insert  35  is essentially the same as the fastening inserts  19 ,  28 . Unlike these, the fastening insert  35  includes a fastening element  36  with a tapered insertable collar  37  and a tie-rod  38 , said tie-rod being movably connected with a fastening body  39 , by means of a connection  40 . In particular the tie-rod  38  is connected cardanically by means of a gimbals with the fastening body  39 . In this way, an unrestricted swiveling motion of the tie-rod  38  about the axes transverse to the fastening body  39  in the ambit of the connection  40  is enabled. A similar movable connection can, for example, also be obtained through a ball-and-socket joint. As can be inferred from the cross-section A-A in the lower part of  FIG. 4 , the fastening unit  11  has a bushing  41 . The bushing  41  works together with the tapered insertable collar  37  and the tie-rod  38  of the type that an adjustment of the tie-rod  38  is possible, in order to fasten according to the connection  40  in the form of a swiveling motion of the tie-rod  38  in the plane of the paper as well as perpendicular thereto. 
       LIST OF REFERENCE NUMBERS 
       [0000]    
       
           10 . pull-down fastening device 
           11 . fastening unit 
           12 . fastening element 
           13 . tie-rod 
           14 . nut 
           15 . fastening ring 
           16 . tapered insertable collar 
           17 . bushing 
           18 . bore 
           19 . fastening insert 
           20 . cone (or taper) 
           21 . O-ring 
           22 . fastening body 
           23 . body-threaded portion 
           24 . tie-rod-threaded portion 
           25 . bore 
           26 . drive piston 
           27 . pin 
           28 . fastening insert 
           29 . fastening element 
           30 . tapered insertable collar 
           31 . tie-rod 
           32 . fastening body 
           33 . connection 
           34 . bushing 
           35 . fastening insert 
           36 . fastening element 
           37 . tapered insertable collar 
           38 . tie-rod 
           39 . fastening body 
           40 . connection 
           41 . bushing