Abstract:
A sharpening device for manually sharpening the cutting teeth of saw chains for chain saws has a frame, which has two head parts (spaced apart from one another and two pairs of guide rods which are, in each case, arranged parallel to one another and to a longitudinal axis and rigidly connect the head parts to one another. Parallel to the longitudinal axis, round files and two file faces are held without play, but exchangeably in the head parts. The pairs of guide rods and the respective associated round files and the respective file faces are arranged rotationally symmetrically with respect to the longitudinal axis.

Description:
FIELD OF THE INVENTION 
       [0001]    The invention relates to a sharpening device for manually sharpening the cutting teeth of saw chains for chain saws. 
       BACKGROUND OF THE INVENTION 
       [0002]    Chain saws, so that their optimal cutting performance is retained, have to be sharpened at regular intervals. In chain saws with improperly sharpened cutting teeth of the saw chains, the saw chains run erratically, the cutting performance decreases and in the worst cases, the saw chain may even tear which can in turn lead to serious accidents. The aforementioned drawbacks also lead to a high level of wear and failures of the drive machine of the chain saw. 
         [0003]    A sharpening tool of the general type is known from DE 29 33 293 B1 (corresponding to U.S. Pat. No. 4,427,605), having a frame, which is substantially formed by two end pieces or head parts, which are connected to one another by two mutually parallel guide rods. A handle is additionally fastened to one end piece. A round file and a square file are exchangeably mounted in the end pieces or head parts. The round file is provided with a file helve which is simultaneously used as a handle of the sharpening device. Each second cutting tooth of the saw chain is filed in an arrangement of the round file and square file. To file the respective second other cutting tooth, the square file and the round file are removed from their mounting in the head parts and inserted in the opposite direction in the frame. The file helve is also removed here from one respective head part and during the changing over of the round file, inserted in the other head part and is then used as the handle of the sharpening tool. The respectively required conversion of the sharpening device is laborious. 
         [0004]    By increasing filing off of the tooth front with the cutting face, the cutting edge changes its position perpendicular to the cutting direction, and in fact comes closer and closer to the actual saw chain, as the free face of each cutting tooth has a relief angle relative to the cutting direction, so the tooth back limited by the free face does not grind or rub on the wood to be cut. Since the guide rods rest on the free faces of two adjacent cutting teeth, the profile of the cutting face and the tooth front are displaced parallel to the free face when sharpening the cutting edge by filing the cutting face and the tooth front. The depth limiter is also filed off simultaneously, so the cutting depth, i.e. the spacing between the cutting edge and depth limiter, always remains constant perpendicular to the cutting direction. 
         [0005]    The invention is based on the object of providing a sharpening device of the general type, which allows alternate sharpening of the respective alternating different teeth of a saw chain without conversion of the sharpening device. 
         [0006]    This object is achieved according to the invention in a sharpening device for manually sharpening the cutting teeth of saw chains for chain saws,
       with a longitudinal axis,   with a frame, which has
           a first head part and a second head part arranged at a spacing from one another and   two pairs of, in each case, two guide rods, which are arranged parallel to one another and to the longitudinal axis and rigidly connect the first and the second head part to one another,   
           with in each case one round file associated with each pair of guide rods and arranged parallel to the longitudinal axis,
           which round files are held in the first and the second head part without play in the longitudinal direction and transverse thereto, but exchangeably in round file receivers,   
           with two mutually parallel file faces on one flat file, which is held without play in the longitudinal direction and transverse thereto, but exchangeably in flat file receivers,   wherein the pairs of guide rods and the respectively associated round files and the file faces are rotationally symmetrically arranged with respect to the longitudinal axis.       
 
         [0015]    It is achieved by the measures according to the invention that the cutting device only has to be rotated about its longitudinal axis if a change is to be made from one type of cutting tooth to the other cutting tooth. The two file faces for filing the two different types of depth limiters have different file directions. 
         [0016]    The configuration according to  FIG. 2  is particularly advantageous as all the files can be changed in a very simple manner according to wear. During the use of the sharpening device, on the other hand, a removal and reinsertion of the unworn files is not necessary. 
         [0017]    Further advantages, features and details of the invention emerge from the following description of an embodiment with the aid of the drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0018]      FIG. 1  shows a side longitudinal view of a part piece of a saw chain to be sharpened, 
           [0019]      FIG. 2  shows a plan view of the saw chain according to  FIG. 1  in accordance with the viewing arrow II in  FIG. 1 , 
           [0020]      FIG. 3  shows a side longitudinal view of a sharpening device according to the invention, 
           [0021]      FIG. 4  shows a cross-section through the sharpening device according to  FIG. 3  in accordance with the cutting line IV-IV in  FIG. 3 , 
           [0022]      FIG. 5  shows a longitudinal section through the sharpening device in accordance with the cutting line V-V in  FIG. 4 , 
           [0023]      FIG. 6  shows a perspective exploded view of the sharpening device with the round files removed and the flat file removed, 
           [0024]      FIG. 7  shows a sharpening device in sharpening use on a saw chain, in a double view in accordance with the two sharpening uses and 
           [0025]      FIG. 8  shows a partial detail of a flat file to be used in the sharpening device according to the invention. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0026]    To facilitate understanding, a saw chain  1  shown in  FIGS. 1 and 2  for saw chains will firstly be described. The saw chain  1  has cutting teeth  2 ,  2 ′, which are always alternating with one another and are configured mirror-symmetrically with respect to one another, in other words cutting alternately to the left and right and which are connected by means of rivets  3  to normal chain members  4  to form an articulated saw chain  1 . A pair of chain members  4  is arranged downstream and upstream of each cutting tooth  2  or  2 ′, only then followed again by a further cutting tooth  2 ′ or  2 . Arranged centrally, in each case, between the pair of chain members  4  or between a cutting tooth  2  or  2 ′ and an associated chain member  4  are connecting members  5 , which are in each case provided with a tooth  6  to engage in a drive wheel of a chain saw. The chain saw  1  and therefore the cutting teeth  2 ,  2 ′ are moved to cut wood in the cutting direction  7 . The cutting teeth  2 ,  2 ′ in each case have a cutting face  8  or  8 ′ and a free face  9  or  9 ′. The cutting edge  10  or  10 ′ formed by the penetration line of the cutting face  8  or  8 ′ and free face  9  or  9 ′ has a sharpening angle α of 30 to 35°, which is formed into a line extending perpendicular to the cutting direction  7 . A sharpening angle α or α′ of this type, which does not equal zero, is used to produce a so-called drawing cut. Mounted in front of the tooth front  11  or  11 ′ is a depth limiter  12  or  12 ′, which fixes the cutting depth a. The free face  9  or  9 ′ forms a relief angle β with respect to the cutting direction  7  of a few degrees, so the free face  9  or  9 ′ is free of the wood to be cut behind the cutting point on the blade  10  or  10 ′. 
         [0027]    The sharpening device shown in the drawing has a frame  13  for mounting and guiding two round files  14 ,  15  and a flat file  16 . The frame  13  consists of two head parts  17 ,  18  and four guide rods  19 ,  19 ′ and  20 ,  20 ′ arranged parallel to one another and connecting these two head parts  17 ,  18 . Configured in the head part  17  are three receivers  21 ,  22 ,  23  for the round files  14 ,  15  and the flat file  16 , which in each case have a base being used as a stop or abutment  24 ,  25 ,  26  to support the round files  14 ,  15  and the flat file  16  against displacement in their longitudinal direction. The receivers  21 ,  22 ,  23  are adapted cross-sectionally to the found files  14 ,  15  or the flat file  16  in such a way that the files  14 ,  15  are mounted substantially free of play transverse to their longitudinal direction. The insertion or removal of the round files  14 ,  15  and the flat file  16  takes place by means of the head part  18 . For this purpose, the head part  18  is provided with a loading flap  27 , which can be opened or closed about a pivot pin  28 , as can be inferred, in particular, from  FIG. 6 . The head part  18  has receivers  29 ,  30 ,  31  also cross-sectionally adapted to the files  14 ,  15 ,  16  for the round files  14 ,  15  and the flat file  16 , in which the files  14 ,  15 ,  16  are mounted substantially free of play transverse to their longitudinal direction. Configured on the loading flap  27  are also three stops being used as abutments  32 ,  33 ,  34  for the files  14 ,  15 ,  16 , against which the files  14 ,  15 ,  16  non-displaceably rest in their longitudinal direction. These abutments  32 ,  33 ,  34  are loaded by a spring element arranged in the loading flap  27  in the longitudinal direction of the files  14 ,  15 ,  16 , so, overall, a support that is free of play of the files  14 ,  15 ,  16  is achieved in their longitudinal direction in the frame  13 . The loading flap  27  is locked, in the closed state, to the head part  18  by means of a latching fastener  36 . 
         [0028]    As can be inferred, in particular from  FIG. 4 , one pair of guide rods  19 ,  19 ′ is allocated to the round file  14  and the other pair of guide rods  20 ,  20 ′ is allocated to the other round file  15 , the guide rod  19  being arranged very close to the round file  14 , while the guide rod  19 ′ is provided remote from this. The same applies to the guide rods  20 ,  20 ′ in relation to the round file  15 . The reason for this is that the guide rod  19  or  20  adjacent to the respective round file  14  or  15  is placed on the free face  9  or  9 ′ of the cutting tooth  2  or  2 ′, which is to be sharpened with the adjacent round file  14  or  15 . The respective other guide rod  19 ′ or  20 ′ is placed on the corresponding free face  9 ′ or  9  of the respective adjacent cutting tooth  2 ′ or  2 . 
         [0029]    Since—as can be inferred from FIG.  7 —the sharpening device is placed at the sharpening angle α or α′ relative to the longitudinal direction of the saw chain  1  defined by the cutting direction  7 , the centre spacing t′ of the guide rods  19  and  19 ′ or  20  and  20 ′ from one another, in each case, is smaller than the division t of the saw chain  1 . 
         [0030]    The support face  37  or  37 ′ of the guide rods  19 ,  19 ′ resting on a free face  9  or  9 ′ of the corresponding cutting tooth  2  or  2 ′ is inclined in accordance with the incline of the free faces  9 ,  9 ′. The same applies to the support faces  38 ,  38 ′ of the guide rods  20 ,  20 ′. As the free faces  9 ,  9 ′ have an incline transverse to the longitudinal direction of the saw chain  1  predetermined by the cutting direction  7 , a height offset b of the support faces  37 ,  37 ′ and the support faces  38 ,  38 ′ is also produced in each case with respect to one another, as can be seen from  FIG. 4 . 
         [0031]    As emerges from  FIG. 7  on the left, a sharpening of the cutting teeth  2  takes place such that the round file  14  is located in the cutting tooth  2 . The guide rod  19  is located here on the free face  9  of the cutting tooth  2 . The guide rod  19 ′ rests on the free face  9 ′ of the adjacent cutting tooth  2 ′. The flat file  16  rests with its flat file face  39  on the depth limiter  12  of the cutting tooth  2 . As filing always takes place by pressing and not pulling, the sharpening of the cutting tooth  2  takes place in the direction  40  in accordance with the arrows on the head parts  17  and  18 . The sharpening of the cutting teeth  2  thus takes place here in such a way that the operator presses against the head part  18 . If, on the other hand, the cutting teeth  2 ′ are to be sharpened, the file is set in accordance with the view in  FIG. 7  on the right. The pushing or pressing of the sharpening device takes place here in the direction  41  in accordance with the arrows on the respective other side of the head parts  17 ,  18 . In this case, the operator presses against the head part  17 , in other words in the direction toward the head part  18 . The flat file face  39 ′ rests here against the depth limiter  12 ′ of the respective cutting tooth  2 ′. In order to allow the change from sharpening the cutting teeth  2  to the cutting teeth  2 ′, only a rotation of the sharpening device about its longitudinal axis  42 , is necessary, i.e. the direction arrows  41 , which during sharpening of the cutting teeth  2  in accordance with  FIG. 7  on the left, are at the bottom, arrive owing to the longitudinal rotation of the sharpening device about its longitudinal axis  42  at the top, which can be seen from  FIG. 7 . The reverse applies accordingly. 
         [0032]    As emerges, in particularly from  FIG. 4 , the longitudinal axis  42  also forms the centre axis of the flat file  16 . As also emerges, in particular from  FIG. 4 , the sharpening device  1  has centre plane  43  placed through the centre axis  42  and receiving it. Provided perpendicular to this centre plane  43  is also a transverse plane  44 , the cutting line of the centre plane  43  and the transverse plane  44  forming the longitudinal axis  42 . The pair of guide rods  19 ,  19 ′, the associated round file  14  and the associated file face  39  are virtually brought by rotation through  180 ° about the longitudinal axis  42  into the position of the guide rods  20 ,  20 ′ with the associated round file  15  and associated file face  39 ′. The arrangement of these functional units is therefore rotationally symmetrical with respect to the longitudinal axis  42 . The guide rods  19 ,  19 ′, on the one hand, and the guide rods  20 ,  20 ′, on the other hand, and the round files  14 ,  15  and the file faces  39 ,  39 ′ are offset with respect to the centre plane  43 , in each case, in the direction of the transverse plane  44  in such a way, that during filing of a cutting tooth  2  the parts provided for sharpening the cutting tooth  2 ′ do not collide with the saw chain  1 . 
         [0033]    The mutually opposing side faces  45 ,  46  of the head parts  17 ,  18 , in other words the side faces  45 ,  46 , which face the files  14 ,  15 ,  16  and the guide rods  19 ,  19 ′,  20 ,  20 ′ extend parallel to one another and at an angle γ with respect to the longitudinal axis  42  of the sharpening device, which approximately corresponds to the sharpening angle α or α′. To sharpen the cutting teeth  2 ,  2 ′, the sharpening device is set with respect to the longitudinal direction  7  of the saw chain  1  in such a way that the saw chain  1  and the side faces  45 ,  46  extend approximately parallel to one another. 
         [0034]    As the sharpening device is used in accordance with the above description in different working directions corresponding to the direction arrows  40 ,  41 , the file faces  39 ,  39 ′, unlike normal flat files, have file cuts  47 ,  47 ′ or file teeth arranged in a different direction on the two file faces  39 ,  39 ′.