Abstract:
The invention relates to a pressing device for pressing a finishing belt against a workpiece surface, including a pressure belt and a pressure belt carrier which supports the pressure belt at two mutually spaced-apart support points, wherein the pressure belt is fastened releasably to the pressure belt carrier, wherein, in order to fix in each case one pressure belt end, provision is made of a fixing device that is provided separately from the pressure belt carrier, and wherein the fixing device is fastened or fastenable releasably to the pressure belt carrier in a state in which one pressure belt end is fixed to the fixing device.

Description:
CROSS-REFERENCE TO PRIOR APPLICATIONS 
       [0001]    This application is a U.S. National Phase application under 35 U.S.C. §371 of International Application No. PCT/EP2015/064372, filed on Jun. 25, 2015, and claims benefit to German Patent Application No. DE 10 2014 213 194.4, filed on Jul. 8, 2014. The International application was published in German on Jan. 14, 2016 as WO 2016/005193 under PCT Article 21(2). 
     
    
     FIELD 
       [0002]    The disclosure relates to a pressing device configured to press a finishing belt against a workpiece surface, including a pressure belt and a pressure belt carrier that supports the pressure belt at two spaced-apart support points, the pressure belt being releasably fastened to the pressure belt carrier. 
       BACKGROUND 
       [0003]    DE 20 2013 005 504 U1 (FIG. 3) and EP 2 212 058 B1 (FIGS. 9 to 11) disclose pressing devices that allow a pressure belt to be secured to a pressure belt carrier. When the pressure belt is fitted on the pressure belt carrier, the pressure belt is positioned by its pressure belt ends on the pressure belt carrier, where is it secured by screws and clamping jaws. DE 20 2013 005 504 U1 discloses clamping jaws that are separate from the pressure belt carrier. EP 2 212 058 B1 discloses clamping jaws that are integral with the pressure belt carrier. 
         [0004]    In the known pressing devices, it has been found that it is very time-consuming to both orient a pressure belt precisely on the pressure belt carrier and, if a pressure belt is damaged, replace the damaged pressure belt for a new pressure belt. This increases the amount of non-productive time that a device for finishing a workpiece requires prior to or while machining a workpiece. 
         [0005]    On this basis, the problem addressed by the present disclosure is that of providing a pressing device by which the non-productive times of a device for finishing a workpiece can be shortened. 
       SUMMARY 
       [0006]    This problem is solved according to the disclosure in that, to secure the pressure belt ends, one securing device, provided separately from the pressure belt carrier, is provided for each pressure belt end and in that, when in a state in which a pressure belt end is secured to the securing device, the securing device is or can be releasably fastened to the pressure belt carrier. 
         [0007]    According to the disclosure, it is possible to handle the ends of the pressure belt at a different location from the pressure belt carrier. For this purpose, securing devices are provided that can be or are releasably fastened to the pressure belt, these securing devices making it possible to secure the pressure belt ends to their respective securing devices, separately from the pressure belt carrier. This makes it possible to connect a pressure belt end to a securing device such that the pressure belt end is secured in the securing device, this operation being carried out spatially outside a device for finishing a workpiece, and the securing device not being fastened to the pressure belt carrier until afterwards. In addition, replacement pressure belts that are already secured to separate securing devices can be kept on hand so that, if a pressure belt is damaged, the damaged pressure belt, together with the securing devices, can be replaced for a new pressure belt that is already secured in two other securing devices. 
         [0008]    Therefore, according to the disclosure, the time-consuming installation operations associated with handling a pressure belt are carried out at a different location from the pressure belt carrier of a device for finishing a workpiece, and so the time-consuming handling operations can be carried out during operation of the finishing apparatus, i.e. during the primary processing time of the finishing device. The non-productive time associated with fitting a pressure belt are thus shortened to a time period required to releasably fasten the securing devices to the pressure belt carrier and to release the securing devices from the pressure belt carrier. 
         [0009]    The pressure belt is secured to the securing device in a particularly reliable manner when the securing device is formed as a clamping device. When the pressure belt is secured to the securing device, the secured end of the pressure belt and the securing device cannot move relative to one another. 
         [0010]    The pressure belt being secured to the securing device is particularly effectively if the securing device includes a clamping slot, delimited by two clamping surfaces, for receiving a pressure belt end. 
         [0011]    Handling the pressure belt when fitting a pressure belt end on the securing device is made even simpler when the securing device includes delimiting elements for laterally delimiting the clamping slot. 
         [0012]    Particularly preferably, two securing devices form, together with the pressure belt, a fitting unit that can be fitted as a whole on the pressure belt carrier and is releasable from the pressure belt carrier. In a fitting unit of this type, each end of the pressure belt is secured to or within its securing device, in such a way that relative movement between the pressure belt end and the securing device is not possible in the connection region between the pressure belt end and the securing device. The securing devices can still change position or location relative to one another, i.e. by the pressure belt being elastically deformed. This makes it simpler to fit the fitting unit on the pressure belt carrier and to remove the fitting unit from the pressure belt carrier. 
         [0013]    Preferably, a plug-in connection is provided for releasably connecting the securing device to the pressure belt carrier. This allows a securing device to be fitted on the pressure belt carrier in a particularly quick and simple manner. 
         [0014]    The plug-in connection preferably includes a plug in the form of a bearing pin and a socket in the form of a bearing pin receptacle. As a result, a sturdy plug-in connection having a simple design can be provided. 
         [0015]    Particularly preferably, the bearing pin and the bearing pin receptacle form a pivot bearing. The connection portions for connecting the securing device and the pressure belt carrier thus perform an additional function that makes it possible to pivotally mount a securing device to the pressure belt carrier. This ability to pivot is advantageous in that a pressure belt can be arranged on the pressure belt carrier so as to at least be as tension-free as possible. 
         [0016]    Particularly preferably, the axis of the pivot bearing extends perpendicularly to an axis of rotation of a workpiece to be machined. This ensures that the pressure belt and a finishing belt which is pressed against a workpiece surface to be machined by the pressure belt can be oriented precisely relative to the workpiece surface to be machined, without stresses occurring within the pressure belt while the workpiece surface is being machined. This improves the surface quality to be achieved when a workpiece is being finished, and increases the service life of a pressure belt. 
         [0017]    A pressing device having a particularly simple design is produced if the bearing pin is formed on the pressure belt carrier and if the bearing pin receptacle is formed in the securing device. 
         [0018]    To allow a securing device to be fitted on the pressure belt carrier in a particularly simple manner, it is proposed that the bearing pin receptacle includes an opening along a periphery of its bearing pin receptacle surface, that the bearing pin has a taper, based on a cylindrical shape, along a periphery of its bearing pin surface, and that the taper and the opening can be joined together. This makes it possible to join the securing device and the pressure belt carrier in a direction lateral to an insertion axis. This can thus reduce the amount a pressure belt elastically deforms while the securing devices are being fitted on and removed from the pressure belt carrier. 
         [0019]    It is possible for the pressure belt carrier to be formed in one piece. In a preferred embodiment, however, the pressure belt carrier is in multiple parts and includes a main carrier for releasably securing the securing devices and an additional element that is movably mounted on the main carrier and by which the support points are provided. This thus provides another degree of freedom, which allows the pressure belt to be arranged on the pressure belt carrier in a tension-free manner. 
         [0020]    Particularly preferably, the additional element is mounted on the main carrier so as to be pivotable about an additional-element pivot axis. In this way, the support points can be pivoted relative to the main carrier. 
         [0021]    In particular, it is preferable for the additional-element pivot axis to extend in parallel with an axis of rotation of a workpiece to be machined. This allows workpieces of different diameters to be machined using the same pressing device, the additional element orienting itself on the main carrier about the additional-element pivot axis according to the diameter of a workpiece to be machined. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0022]    The present disclosure will be described in even greater detail below based on the exemplary figures. The disclosure is not limited to the exemplary embodiments. Other features and advantages of various embodiments of the present disclosure will become apparent by reading the following detailed description with reference to the attached drawings which illustrate the following: 
           [0023]      FIG. 1  is a side view of an embodiment of an apparatus for finishing a workpiece, comprising two pressing devices; 
           [0024]      FIG. 2  shows the pressing devices according to  FIG. 1  finishing a workpiece having a smaller diameter; 
           [0025]      FIG. 3  is a view corresponding to  FIG. 2 , showing a workpiece having a larger diameter being finished; 
           [0026]      FIG. 4  is a side view of an embodiment of a pressing device; 
           [0027]      FIG. 5  is a front view of the pressing device according to  FIG. 4 ; 
           [0028]      FIG. 6  is a side view of an embodiment of a pressure belt; 
           [0029]      FIG. 7  is a front view of the pressing belt according to  FIG. 6 ; 
           [0030]      FIG. 8  is a side view of an embodiment of a fitting unit of the pressing device; 
           [0031]      FIG. 9  is a front view of the fitting unit according to  FIG. 8 ; 
           [0032]      FIG. 10  is a perspective view of the pressing device according to  FIGS. 4 and 5 , the fitting unit according to  FIGS. 8 and 9  being shown in a first fitting state; 
           [0033]      FIG. 11  is a view corresponding to  FIG. 10 , the fitting unit being shown in a second fitting state; and 
           [0034]      FIG. 12  is a view corresponding to  FIG. 10 , the fitting unit being shown in a third fitting state. 
       
    
    
     DETAILED DESCRIPTION 
       [0035]      FIG. 1  shows an apparatus  10  for finishing a workpiece  12 . The workpiece  12  is, for example, a crankshaft that rotates about an axis of rotation  14  while it is being finished. The workpiece surface  16  to be machined is, for example, a main bearing surface or a conrod bearing surface. 
         [0036]    To machine the surface  16 , a finishing belt  18  is provided, which is taken from a supply  20  and guided by a first guide device  22  of a first pressing device  24  and a deflection point  26 . From the deflection point  26 , the finishing belt  18  is guided to a second pressing device  28  and a second guide device  30 , and lastly to a collector  32 . 
         [0037]    The pressing devices  24  and  28  are held on opposite sides of the workpiece  12  on respective pivot arms  34 ,  36  that can pivot about respective retaining-arm pivot axes  38 ,  40 . The retaining-arm pivot axes  38 ,  40  are fixed with respect to a frame part  42 . The frame part  42  is also used for arranging a drive device  44 , which is known per se and thus only portions thereof are shown. The drive device  44  is used to press the jaw-like retaining arms  34 ,  36 , each having their particular pressing device  24  and  28  retained thereon, towards the workpiece  12 . 
         [0038]    While the workpiece  12  is being machined, it rotates about the axis of rotation  14 . The finishing belt  18  is pressed against the workpiece surface  16  to be machined at the height of each pressing device  24 ,  28 . At the same time, an oscillating linear movement is superposed on the rotational movement of the workpiece  12  about the axis of rotation  14 . In this respect, the workpiece  12  oscillates along the axis of rotation  14  relative to the finishing belt  18 . This makes it possible to drive the workpiece  12  and/or the finishing belt  18  in an oscillating manner. By this oscillating movement, a cross-grinding structure typical of a finishing process is produced. 
         [0039]    The design of the pressing devices  24 ,  28  and the connection thereof to the retaining arms  34 ,  36  will be explained below with reference to  FIG. 2 . The retaining arms  34 ,  36  comprise free ends  46 ,  48 , to each of which a main carrier  50  of a pressing device  24 ,  28  is fastened, respectively, by a screw connection  51 . 
         [0040]    The main carrier  50  comprises a base  52  and arms  54  and  56  protruding from the base  52 . A clearance that extends along the base  52  and is used to arrange a bearing bracket  58  is formed between the arms  54  and  56 . 
         [0041]    The bearing bracket  58  is used for pivotally mounting a V-shaped additional element  60 . Accordingly, the additional element  60  is mounted on the main carrier  50  of the pressing device  24 ,  28  so as to be pivotable about an additional-element pivot axis  62 . 
         [0042]    At each of its free ends, the V-shaped additional element  60  comprises rounded support points  64 ,  66  that are used to support the rear face of a pressure belt  68 . The pressure belt  68  is slidingly mounted in the region of the support points  64 ,  66   
         [0043]    By its front face, the pressure belt  68  applies a contact pressure to the rear face of the finishing belt  18 , and so the front face thereof is pressed against the workpiece surface  16  of the workpiece  12 . 
         [0044]    Pivotally mounting the additional element  60  makes it possible to compensate for different opening angles of the retaining arms  34 ,  36  for workpieces  12  of different sizes (cf.  FIGS. 2 and 3 ), and so a finishing portion  70  of the finishing belt  18  is oriented centrally between the support points  64 ,  66  in each case. This is also possible because the additional-element pivot axis  62  extends in parallel with the axis of rotation  14  of the workpiece  12 . 
         [0045]    The design of a pressing device  24 ,  28  will be described in the following using the example of the pressing device  24  and with reference to  FIGS. 5 to 12 . 
         [0046]    To pivotally mount the additional part  60  on the main carrier  50 , a pivot pin  72  is provided. The pivot pin  72  interacts with a securing screw  72 , which secures the additional part  60  to the pivot pin  72 . The additional element  60 , the pivot pin  72  and the securing screw  74  thus form a pivoting unit that can pivot as a whole about the additional-element pivot axis  62 . 
         [0047]    Together, the additional element  60  and the main carrier  50  form a pressure belt carrier  76 . 
         [0048]    To secure the pressure belt  68  to the pressure belt carrier  76 , two preferably identical securing devices  78 ,  80  are provided and are used to secure one pressure belt end  82 ,  84  of the pressure belt  68 , respectively. 
         [0049]    The securing devices  78 ,  80  are designed as clamping devices and each comprises a clamping slot  86  for receiving a pressure belt end  82  and  84 , respectively. The pressure belt ends  82 ,  84  comprise a hole  88  for passing through a clamping screw  90 . The clamping screw  90  is used to move material portions  92  and  94 , arranged on either side of the clamping slot  86 , of a securing device  78 ,  80  towards one another in order to narrow the clamping slot  86  such that surfaces of the material portions  92 ,  94  facing the pressure belt ends  82  and  84 , respectively, form clamping surfaces. 
         [0050]    To delimit the clamping slot  86  sideways, delimiting elements  96  are provided and are, for example, screwed to the material portion  94 . 
         [0051]    The material portions  92  and  94  are integral with a further material portion  98  of a securing device  78 ,  80 . 
         [0052]    Whereas the material portions  92  and  94  are used for securing a pressure belt end  82 ,  84 , the material portion  98  is provided to enable a releasable connection to the pressure belt carrier  76 , which will be described below. 
         [0053]    In particular, the releasable connection between a securing device  78  and  80  and the pressure belt carrier  76  is in the form of a plug-in connection  100 . The plug-in connection  100  comprises a plug in the form of a bearing pin  102 , which is preferably arranged on each arm  54 ,  56  of the pressure belt carrier  76 . The bearing pin  102  interacts with a socket in the form of a bearing pin receptacle  104 , which is formed by the material portion  98  of the securing device  78 ,  80 . The bearing pin  102  and the bearing pin receptacle  104  together form a pivot bearing  106  having an axis  108  that extends orthogonally to the axis of rotation  14  of the workpiece  12 . 
         [0054]    To fit the pressure belt  68  on the pressure belt carrier  76 , a pre-shaped pressure belt (cf.  FIGS. 6 and 7 ) is first connected to two securing devices  78 ,  80  by the pressure belt ends  82  and  84  being firmly clamped in respective clamping slots  86  in the securing devices  78 ,  80 . This produces a fitting unit  110 , consisting of a pressure belt  68  and two securing devices  78 ,  80  (cf.  FIG. 8 ). 
         [0055]    It is possible for the bearing pin receptacle  104  to be hollow-cylindrical and for the bearing pin  102  to be cylindrical in order together to form a plug-in connection  100 . 
         [0056]    In a preferred embodiment, however, a bearing pin receptacle surface  112  of the bearing pin receptacle  104  comprises an opening  114  when viewed in the peripheral direction (cf.  FIG. 9 ). This opening  114  is used for allowing the bearing pin  104  to be inserted into the bearing pin receptacle  104  from a lateral direction too. For this purpose, the bearing pin  102  has a taper  118 , based on a cylindrical shape, along a periphery of its bearing pin surface  116  (cf.  FIGS. 10 to 12 ). 
         [0057]    To releasably fasten the fitting unit  110  to the pressure belt carrier  76 , the assembly  110  is positioned relative to the pressure belt carrier  76  in such a way that a first securing device  80  can be joined to a first bearing pin  102  by its bearing pin receptacle  104 . For this purpose, the opening  114  in the bearing pin receptacle  104  in the first securing device  80  is oriented such that said device can be placed on the taper  118  of a first bearing pin  102 . In this way, the first securing device  80  is releasably fastened to the pressure belt carrier  76  (cf.  FIGS. 10 and 11 ). 
         [0058]    The second securing device  78  can then be joined to the pressure belt carrier  76  by the fitting unit  110  being pivoted by 180° about the pivot axis  108  of the first securing device  80  (cf.  FIGS. 11 and 12 ). In this way, the opening  114  in the bearing pin receptacle  104  in the first securing device  78  can be brought into the joining position with the second bearing pin  102  of the pressure belt carrier  76  (cf.  FIG. 12 ). From here, the second bearing pin  102  and the bearing pin receptacle  104  of the second securing device  78  can be joined together, as indicated by the dashed arrow in  FIG. 12 . 
         [0059]    Starting from a state in which the securing devices  78  and  80  are each releasably fastened to the pressure belt carrier  76 , and in which the bearing pins  102  are received in the respective bearing pin receptacles  104 , the fitting unit  110  can be pivoted by 90° about the axis  108  in order to complete the fitting, as indicated by a dashed pivot arrow in  FIG. 12 . This produces the completely fitted pressing device  24  shown in  FIG. 4 . 
         [0060]    As the pressure belt  68  pivots from the intermediate fitted position shown in  FIG. 12  to the completely fitted position shown in  FIG. 4 , inner, concave belt portions  120  of the pressure belt  68  come to abut the corresponding convex bearing surfaces in the form of the support points  64  and  66 . 
         [0061]    While the securing devices  78 ,  80  are mounted on the pressure belt carrier  76 , the pressure belt  68  is deformed, in particular is bent and/or twisted, from its force-free initial shape (cf.  FIGS. 6 and 7 ). This is elastic deformation. 
         [0062]    While the disclosure has been illustrated and described in detail in the drawings and foregoing description, such illustration and description are to be considered illustrative or exemplary and not restrictive. It will be understood that changes and modifications may be made by those of ordinary skill within the scope of the following claims. In particular, the present disclosure covers further embodiments with any combination of features from different embodiments described above and below. Additionally, statements made herein characterizing the disclosure refer to an embodiment of the disclosure and not necessarily all embodiments. 
         [0063]    The terms used in the claims should be construed to have the broadest reasonable interpretation consistent with the foregoing description. For example, the use of the article “a” or “the” in introducing an element should not be interpreted as being exclusive of a plurality of elements. Likewise, the recitation of “or” should be interpreted as being inclusive, such that the recitation of “A or B” is not exclusive of “A and B,” unless it is clear from the context or the foregoing description that only one of A and B is intended. Further, the recitation of “at least one of A, B and C” should be interpreted as one or more of a group of elements consisting of A, B and C, and should not be interpreted as requiring at least one of each of the listed elements A, B and C, regardless of whether A, B and C are related as categories or otherwise. Moreover, the recitation of “A, B and/or C” or “at least one of A, B or C” should be interpreted as including any singular entity from the listed elements, e.g., A, any subset from the listed elements, e.g., A and B, or the entire list of elements A, B and C.