Abstract:
The grinding machine ( 1 ), in particular for grinding and/or sharpening of knives, comprises a grinding disc ( 2 ), mounted rotatably around a turning axis (D 1 ) and turnable in direction of rotation (D), with a cylindrically-shaped grinding surface ( 2   a ) comprising abrasive means, as well as comprising a guiding part ( 3 ), which is arranged immediately next to the grinding surface ( 2   a ) of the grinding disc ( 2 ), wherein the guiding part ( 3 ) has a guiding surface ( 3   a ) which extends in such a way that the guiding surface ( 3   a ), together with the grinding surface ( 2   a ), forms a gap (S), which progressively tapers in the direction opposite to the direction of rotation (D) and which runs parallel to the direction of the turning axis (D 1 ), and that an overlay part ( 4 ) with an overlay surface ( 4   a ) running towards the gap (S) is arranged immediately next to the grinding surface ( 2   a ) of the grinding disc ( 2 ).

Description:
FIELD OF THE INVENTION 
       [0001]    The invention concerns a grinding machine. 
       BACKGROUND OF THE INVENTION 
       [0002]    Many grinding machines and grinding apparati are known for grinding or for re-sharpening of cutting devices, such as knives, or rather, their blades. Such grinding machines have the disadvantage that it is difficult to sharpen a blade reproducibly evenly and that, in particular, this is difficult for people who have limited experience with respect to grinding. Thus, it is the problem which this invention seeks to solve to provide a more advantageous grinding machine. 
       SUMMARY OF THE INVENTION 
       [0003]    In particular, the problem is solved by a grinding machine comprising a grinding wheel with a disc-shaped basic body, wherein the disc-shaped basic body has a centre of turning, as well as at least one side surface extending substantially perpendicularly to the centre of turning, and wherein a grinding disc, having a grinding layer is removably fixable to the disc-shaped basic body in such a way that the grinding disc is arranged concentrically with respect to the centre of turning and extensionally along the side surface of the disc-shaped basic body, as well as comprising a support device which forms a guide, wherein the guide is arranged to extend in such a way that at the grinding disc, when this is attached to the basic body, an acute angle γ is formed between the grinding layer and the guide, to form a grinding gap. 
         [0004]    The grinding machine according to the invention has the advantage, amongst others, that easily-replaceable grinding discs are used as grinding means. In a particularly preferred embodiment, conventional grinding discs may be used which provides the advantage that such grinding discs are very cheap. Also grinding discs of varying grain size can be used. 
         [0005]    In a particularly advantageous embodiment, the grinding disc is coupled elastically with the grinding wheel, in particularly in such a way that at least a section of the grinding disc is elastically movable in the direction of extension of the centre of turning, which provides the advantage that a blade that is to be ground lies particularly softly against the grinding disc, since the latter can adapt to the blade. This enables a particularly advantageous blade sharpening. 
         [0006]    In a further advantageous embodiment a grinding disc is arranged on each side of a grinding wheel, such that each side of a blade has its own grinding disc available to it. 
         [0007]    In a particularly advantageous embodiment, the grinding gap is arranged with respect to the centre of turning of the grinding disc such that the grinding disc moves predominantly from bottom to top or alternatively from top to bottom in the area of the grinding gap, which enables a particularly advantageous sharpening of a blade. 
         [0008]    In a further advantageous embodiment, the support device has a rotatable support body, which has the advantage that a blade which is moved along the support device does not get scratched, and that the blade is particularly easily movable along the support device. 
         [0009]    In the following, the invention is explained by means of an embodiment example. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWING 
         [0010]      FIG. 1  a perspective view of a grinding wheel; 
           [0011]      FIG. 2  the grinding wheel shown in  FIG. 1  in elevation; 
           [0012]      FIG. 3  a longitudinal cross-section through the grinding wheel shown in  FIGS. 1 and 2 ; 
           [0013]      FIG. 4  a perspective view of a grinding wheel basic body; 
           [0014]      FIG. 5  a perspective view of a grinding disc; 
           [0015]      FIG. 6  a perspective view of a grinding machine from the front; 
           [0016]      FIG. 7  the grinding machine shown in  FIG. 6  in elevation; 
           [0017]      FIG. 8  a detail view of the front of the grinding machine shown in  FIG. 7 ; 
           [0018]      FIG. 9  a further perspective view of the grinding machine from behind; 
           [0019]      FIG. 10  a view of the rear side of the grinding machine; 
           [0020]      FIG. 11  a view of the grinding machine from above, in partial cross-section; 
           [0021]      FIG. 12  a support device in elevation; 
           [0022]      FIG. 13  a cross-section through the support device shown in  FIG. 12  along the line A-A; 
           [0023]      FIG. 14  a perspective view of the support device; 
           [0024]      FIG. 15  a longitudinal cross-section through a further embodiment of a grinding wheel. 
       
    
    
     DETAILED DESCRIPTION 
       [0025]      FIG. 1  shows a grinding wheel  2  comprising a disc-shaped basic body  2   a , which is fixedly connected with a driveshaft  2   b , and which is rotatably mounted around a turning axis D, or alternatively, a centre of turning D of the basic body  2   a . One grinding disc  3  is fixed on each of the sides of the basic body  2   a , on the left side and on the right. The grinding disc arranged on the left side is shown fully visible and is firmly connected with the driveshaft  2   b  by means of an underlay disc  2   e  and a bolt  2   f.    
         [0026]      FIG. 2  shows the grinding wheel  2  shown in  FIG. 1  in elevation, to which one grinding disc  3  is fixed on each of the two sides. In the depicted embodiment example, an elastic ring  2   d  is arranged between the basic body  2   a  and the grinding disc  3 , in order to enable elastic mobility in the direction extending essentially in the direction of the turning axis D for sections of the grinding disc  3 , in particular for sections arranged in the vicinity of the elastic ring  2   d.    
         [0027]      FIG. 3  shows a cross-sectional through the grinding wheel  2  shown in  FIG. 2  along line B-B. The disc-shaped basic body  2   a  is firmly connected with the driveshaft  2   b . The grinding wheel  2  has a side surface  2   g ,  2   h  on each side, in the outer end section of which, there is a groove extending circumferentially, in which an elastic means  2   d , such as an elastic O-ring is held. 
         [0028]    In the depicted embodiment example, the grinding disc  3  comprises an outer grinding disc part  3   a  with a grinding layer  3   a  and a preferably metallic fixation part  3   b , which firmly fixed with the outer grinding disc part  3   a . The fixation part  3   b  has a hole  3   c  in the middle. The grinding disc  3  can be formed in the most varied of ways such that it has a grinding layer  3   a . For example, a plastic or a metal disc-shaped basic body could be used, onto which a grinding layer  3   a  has been put. The grinding layer  3   a  may, for example, have a plurality of grinding grains. The width of the usable grinding layer  3   a  may, for example, extend over a width  3   d . In a preferred embodiment, the two grinding discs  3  are arranged, as shown in  FIG. 3 , such that they are firmly centrally held by an underlay disc  2   e  and a central bolt  2   f , i.e., are firmly held at the fixation part  3   b , as opposed to the grinding discs  3  which extend from the centre at a distance to the sides  2   g ,  2   h  and outwards lie against the elastic O-ring  2   d . This embodiment has the advantage that, in particular, surfaces of at least section of the grinding layer  3   a  can yield in the direction of extension of the turning axis D, such that the surfaces of the grinding layer  3   a  behave relatively softly and, for instance, can adapt to a blade to be sharpened. 
         [0029]      FIG. 4  shows a perspective view of the grinding wheel basic body  2   a  with side surfaces  2   g ,  2   h  and a central overlay  2   i . On the right there is a grinding disc  3 . At least side surface  2   g , and when using two grinding discs, also side surface  2   h , extends substantially perpendicularly to the turning axis D. ‘Substantially perpendicularly to the turning axis’ means, on the one hand, that, in a particularly preferred embodiment, the side surfaces  2   g ,  2   h  are perpendicular, i.e., exactly perpendicular, to the turning axis D. On the other hand, this means that in a further advantageous embodiment, the side surfaces  2   g ,  2   h  can also extend at a slight angle to the turning axis, such as, for example conically or crooked. 
         [0030]      FIG. 5  shows a perspective view of a grinding disc  3  with grinding layer  3   a , fixation part  3   b  and hole  3   c .  FIG. 5  also shows the preferred grinding area  3   g , which extends between a horizontal line  3   f  that runs through the hole  3  and an upper horizontal line  3   e , which preferably runs at a distance of about 1 cm to 2 cm away from the horizontal line  3   f , such that the height  3   h  can preferably be up to 2 cm. 
         [0031]      FIG. 6  shows a perspective view of an embodiment of a grinding machine  1 . This comprises a rotatably-mounted grinding disc  3  with a grinding layer  3   a , which is arranged in a housing  8  with a cover  7  and a front cover  9 . A support device  5 ,  6  is arranged on the left and on the right, each of which is provided with a magnet  14 . Also, there is a sideways guide  10 . The grinding machine  1  is fixed to a ground plate  4  and comprises an extraction unit  12  via which air may be extracted from inside the housing  8 . 
         [0032]      FIG. 7  shows the grinding machine shown in  FIG. 6  in elevation and  FIG. 8  an enlargement of the elevation shown in  FIG. 7 . The support device  5  with guide  5   a , shown on the left, as well as the grinding disc  3  with grinding layer  3   a , arranged on the left, form a grinding gap S with opening angle γ, wherein the gap S at its bottom, ends in a gap line S 1 , as shown in  FIG. 8 . As shown in  FIG. 7 , the gap line preferably runs perpendicularly towards the rear. In mirrored arrangement to this, the support device  6  with guide  6   a , shown on the right, as well as the grinding disc  3  with grinding layer  3   a , arranged on the right, form a grinding gap S with opening angle γ and gap line S 1 . Since the grinding layer  3   a  can yield slightly in the direction of extension of the turning axis D, in particular in dependence on the force exerted on the grinding layer  3   a  by the blade to be sharpened, the opening angle γ and the gap line S 1  can alter slightly, which allows particularly ‘soft’ grinding. The support devices  5 ,  6  can be arranged in a fixed manner. A blade to be sharpened can be laid into the grinding gap S and be moved to and fro in the direction of extension of the gap line S 1 , in order to sharpen the blade on the rotating grinding layer  3   a . In a particularly preferred embodiment, the support devices  5 ,  6  are pivotally arranged in such a way that the opening angle γ may be adjusted and that the support devices  5 ,  6  can be fixed in the currently desired position. In a preferred embodiment, the adjustable opening angle γ is adjustable across a range of angles between 15° and 35°. In a preferred embodiment, the gap line S 1  is arranged at a vertical distance from the centre of turning D of the driveshaft  2   b  by in the range of between 0 cm and 2 cm, preferably between 2 mm and 12 mm. This provides the advantage, as shown in  FIG. 5 , that the grinding layer  3   a  is moving predominantly in the vertical direction in the area of the gap line S 1 , since the grinding disc turns in direction R or counter to R, which, in particular, provides the advantage that only a small force is exerted acting in the direction of extension of the gap line S 1 . Due to this, the blade can be particularly easily ground with limited exertion of force. 
         [0033]      FIG. 9  shows a perspective view of the grinding machine  1  and  FIG. 10  from behind in elevation.  FIG. 11  shows the grinding machine  1  from above, in partial cross-section. The grinding machine  1  comprising an adjustment device  11  with two rotatable mounted turning axes  11   a ,  11   b , which are connected with the left or respectively the right support device  5 ,  6 , in order to alter and adjust their presentation angle and therewith also the angle γ of the grinding gap S. The grinding machine  1  comprises a movably mounted slider  11   h  with longitudinal slot  11   l  as well as a locking screw  11   i , which allows the slider  11   h  to be released and locked. The slider  11   h  is also connected with an adjustment grip  11   e , wherein the adjustment grip  11   e  engages via a shaft in the longitudinal slot  11   f ,  11   g  of the levers  11   c ,  11   d , and wherein the levers  11   c ,  11   d  are firmly connected at one end with an axis of turning  11   a ,  11   b , such that pushing the adjustment grip  11   e  vertically results in a mirrored pivoting of the two axes of turning  11   a ,  11   b  and thereby also of the support devices  5 ,  6 . The adjustment grip  11   e  can be locked with the help of the locking screw  11   i , thereby also fixing the position of the support devices  5 ,  6 . In an advantageous embodiment, there is an angle scale  11   k  arranged on the rear wall, wherein, based on the positioning of the slider  11   h , the angle size γ of the grinding gap S may be read off and adjusted. In a further advantageous embodiment, the grinding machine  1  is firmly and releasably connectable with a ground plate  4  via a fixing screw  13 . 
         [0034]      FIG. 12  shows an embodiment example of a support device  5  in elevation.  FIG. 13  shows a cross-section along line A-A shown in  FIG. 12  and  FIG. 14  a perspective view of the support device  5 . The support device  5  comprises a basic body  5   a  with recesses  5   b  and releasably-arranged cylinder-shaped pegs  5   c  therein, on which rotatably-mounted support bodies  5   d  are arranged. In the shown embodiment example, the support bodies  5   d  take the form of hollow, cylindrical sleeves. The support bodies  5   d  can take on the most varied of forms, to facilitate a turning surface or guide  5   e  in the direction of extension of the gap line S 1 . In a particularly advantageous embodiment, a Magnet, preferably a permanent magnet, is arranged in the support device  5 ,  6 , as shown in  FIG. 13 , such that a metallic, ferromagnetic blade is pulled against the support bodies  5   d  and lies against them advantageously. This embodiment has the advantage that the blade lies against the support device  5 ,  6  in a defined way, such that the blade which is to be sharpened is at a defined angle to the grinding layer  3   a , which results in it being possible to grind the blade reproducibly with the same angle, even if the blade is only ground, for example, weekly or monthly. The rotatably-mounted support bodies  5   d  also have the advantage that the side of the blade that slides past the support bodies  5   d  does not get scratched or otherwise damaged. 
         [0035]      FIG. 15  shows a longitudinal section that a further embodiment example of a grinding wheel  2 . Differently to the grinding wheel  2  shown in  FIG. 3 , the grinding wheel  2  shown in  FIG. 15  has an elastic means  2   d  stretching out over the whole width  3   d  of the grinding layer  3   a  and on which the grinding disc  3  can lie. Instead of being on the Grinding wheel  2 , the elastic means  2   d  could also be arranged on the rear side of the grinding disc  3 , in particularly in such a way that the elastic means  2   d  forms part of the grinding disc  3 . This embodiment has the advantage that when a grinding disc  3  is replaced, so is the elastic means  2   d , which is thereby as good as new after the replacement. This embodiment has the advantage that the elastic properties of whichever grinding disc  3  is used remain constant or very similar over the long-term. In a preferred embodiment, the grinding wheel  2  is formed such that a conventional and therefore very cheap grinding disc  3  can be used. In addition to this, grinding discs  3  of varying grains could be held in store, such that a grinding disc  3  of appropriate grain can be fixed to the grinding wheel  2  according to particular grinding requirements. The elastic means  2   d  could also be made of such a width in the radial direction that a majority or all of what is shown as a cavity in  FIG. 15  is also filled with elastic means  2   d . The elastic means  2   d  preferably consists of an elastic plastic. The elastic means  2   d  can be formed in a plurality of possible ways, for example as a spring, in particular as a leaf spring. Thus, for example, a disc-shaped leaf spring could be arranged immediately next to the grinding  3  and it could be, for example, secured on the shaft  2   b  immediately next to the grinding disc  2 , wherein the disc-shaped leaf spring has springy properties in the direction of extension of the turning axis D, such that the grinding disc  3 , which is arranged immediately next to the leaf spring, similarly has springy properties in the direction of extension of the turning axis D, due to the leaf spring.