Abstract:
A saw blade is disclosed which comprises a fixing receptacle for fixation on an oscillating drivable drive shaft, having a cutter that is distanced from the fixing receptacle, the cutter extending essentially tangentially or arch-shaped with respect to the fixing receptacle and being provided with a plurality of saw teeth. The cutter comprises at least a first section and a second section, and the saw teeth have at least in the area of one section another spacing or another set of saw teeth than in the other section. The saw blade allows a precise application to the object to be cut and a later continuation of the cutting process with increased feed.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    The invention relates to a saw blade comprising a fixing receptacle for fixation on an oscillatingly drivable drive shaft, with a cutter that is distanced from the fixing receptacle, this cutter extending essentially tangentially or arch-shaped with respect to the fixing receptacle and being provided with a plurality of saw teeth, wherein the cutter comprises at least a first section and a second section.  
           [0002]    Such a saw blade is known from EP 0 881 023 A2.  
           [0003]    The known saw blade comprises a cutter that extends longitudinally with respect to the fixing receptacle and that is additionally, if necessary, slightly angled at two lateral sections with respect to a center section.  
           [0004]    Such cutting tools can be used for special tasks in connection with an oscillating drive with a high frequency in the order of magnitude of approximately 3000-25000 oscillations per minute and with a small pivot angle of approximately 0.5-5°, for instance to facilitate the creation of rectangular recesses on wood, gypsum or the like. Moreover, also circular shaped and circle segment shaped saw blades are known that are also used in connection with oscillating drives for such special cutting tasks.  
           [0005]    In order to be able to achieve cuts as precise as possible, a spacing as small as possible should be chosen, so that the saw blade is provided with a plurality of saw teeth. This results, however, in the disadvantage of a slower operating speed.  
         SUMMARY OF THE INVENTION  
         [0006]    The object of the invention is therefore to improve a saw blade of the kind mentioned at the outset in such a way that cuts as precisely as possible can be achieved and, at the same time, a good feed during the cut is guaranteed.  
           [0007]    According to the invention this object is achieved for a saw blade according to the kind mentioned at the outset by the fact that the saw teeth have at least in the area of the first section another spacing or another set of saw teeth than in the second section.  
           [0008]    The object of the invention is in that way completely achieved.  
           [0009]    In that way, the spacing at one of the two sections can be chosen more finely than at the other section, whereby it is made possible to let the saw blade first, at the beginning of a cut, operate with a fine spacing in order to allow a good application. As soon as the beginning of the cut is performed, the saw blade can be moved in such a way that the other section is used, which is provided with a coarser spacing or with a broader set of saw teeth, so that now it is possible to operate with a higher feed.  
           [0010]    The term “set of saw teeth” shall mean that a saw blade comprises saw teeth, which protrude over both outer surfaces of the saw blade. The saw teeth, which protrude generally alternately over the one outer surface and over the other outer surface, have, thus, lateral edges, the largest distance of which is larger than the thickness of the saw blade. If this set of saw teeth is varied, i.e. the distance of the two planes defined by the saw teeth on the one outer surface and the other outer surface, an easy application and a precise beginning of the cut can also be achieved in this manner, so that, subsequently, in operation with the center section, a larger feed can be achieved.  
           [0011]    This measure can, of course, be combined with a variation of the spacing.  
           [0012]    According to another embodiment of the invention, the cutter is curved in a circular arc-shaped manner and has a center of curvature that coincides with the fixing receptacle. The saw blade may here comprise either a circular or a circle segment shaped basic shape.  
           [0013]    According to an alternative embodiment, the saw blade has basically a longitudinal shape, wherein the fixing receptacle is configured in the region of a first end and the cutter is configured at the opposite second end.  
           [0014]    By means of such a shape of a saw blade, sawing operations can be performed at places that are difficult to access.  
           [0015]    According to another embodiment of the invention, the cutter comprises more than two sections of which at least two have a spacing or set of saw teeth deviating from each other.  
           [0016]    By dividing the cutter into a larger number of sections, an even more favorable adjustment to the cutting process can be guaranteed so that e.g. working can be performed at the beginning of the cut with a particularly fine spacing in order to guarantee a precise start of the cut, subsequently with a spacing that is somewhat coarser, and, finally, in the further cutting process, with a still coarser spacing in order to guarantee a quick feed.  
           [0017]    According to another embodiment of the invention, the cutter has a first, a second and a third section, wherein the first section is configured as a middle section that is enclosed on both sides by the second and the third section.  
           [0018]    By means of such a form, the saw blade can, at the beginning of the cut, be applied at will from the one or from the other side and, subsequently, it can be worked with the middle section in the cutting process.  
           [0019]    Preferably, the saw teeth of one section have a finer spacing and/or a smaller set than at the second section.  
           [0020]    It is to be understood, further, that it is sufficient to configure merely one of the two sections in comparison to the other section deviating with reference to spacing or set of saw teeth. In this case, the saw blade is always applied from one side, namely, generally, at the section with the finer spacing and/or the narrower set of teeth and, subsequently, is operated with the other region.  
           [0021]    According to another embodiment of the invention, the spacing from one of the sections decreases continuously at least into the direction of one of the other sections.  
           [0022]    Alternatively or additionally to that, the set of saw teeth from one of the sections becomes continuously narrower at least into the direction of one of the other sections.  
           [0023]    In this way, a gradual transition is made possible from operating with a fine spacing and/or with narrow set of saw teeth, i.e. from operating with a relatively slow feed with higher precision, to a subsequent operating with a larger spacing and/or larger set of saw teeth, so that the user of the saw blade is offered an optimal variability.  
           [0024]    By contrast, it is possible, of course, to provide the first section continuously with a different spacing and/or set of saw teeth than one of the other sections.  
           [0025]    In addition, further sections of the cutter may be added, the spacing or the set of saw teeth of which, respectively, are further varied, generally using intermediate values between adjacent sections.  
           [0026]    According to another embodiment of the invention, at least the first section of the cutter extends tangentially with respect to the fixing receptacle.  
           [0027]    By means of such a shape, working in spatially closely limited circumstances is made possible, in order to perform e.g. a sawing operation alongside a wall or a floor surface.  
           [0028]    Herein, the second and a third section can be angled at least partially with respect to the first section, in order to reduce somewhat the vibrations during operation.  
           [0029]    According to another embodiment of the invention, the cutter is configured as a double cutter with two tooth rows being distanced from each other.  
           [0030]    In an improved embodiment of this embodiment, two tooth rows terminate flush with each of the two outer surfaces of the saw blade.  
           [0031]    By means of such an embodiment, a particularly precise cut can be achieved, wherein a chip removal can be guaranteed via a spacing between the two tooth rows.  
           [0032]    In such an embodiment, the distance between the two tooth rows is preferably kept constant and merely the spacing in the center section and/or the lateral sections is adjusted in the desired manner.  
           [0033]    It is to be understood that the features mentioned above and those yet to be explained below can be used not only in the respective combinations indicated, but also in other combinations or in isolation, without leaving the scope of the present invention. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0034]    Further features and advantages of the invention can be taken from the following description of preferred embodiments with reference to the drawings. In the drawings:  
         [0035]    [0035]FIG. 1 shows a view of a first embodiment of a saw blade according to the invention, in the shape of a segment saw blade;  
         [0036]    [0036]FIG. 2 shows a view of another embodiment of a segment saw blade according to the invention;  
         [0037]    [0037]FIG. 3 shows a top view of another embodiment of a saw blade according to the invention having a longitudinal shape;  
         [0038]    [0038]FIG. 4 shows a partial cross section through another embodiment of a saw blade in the region of its teeth;  
         [0039]    [0039]FIG. 5 shows another partial cross section through another variation of a saw blade in the region of its teeth;  
         [0040]    [0040]FIG. 6 shows a top view of a variation of the embodiment according to FIG. 3; and  
         [0041]    [0041]FIG. 7 shows another variation of the saw blade having a circular basic shape in top view.  
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0042]    In FIG. 1, a saw blade according to the invention in the shape of a segment saw blade is shown in top view and designated altogether with the numeral  10 . Saw blade  10  has a fixing receptacle  26  in the shape of an opening, by means of which it can be fixed on an oscillatingly drivable drive shaft of an oscillation drive of known design, e.g. by means of a nut or the like. Saw blade  10  has a cutter  24 , which is configured in a circular arc-shaped manner and the center of curvature of which extends through fixing receptacle  26 . If saw blade  10  is driven, thus, by means of a rotating oscillation drive about fixing receptacle  26  in an oscillating to-and-fro manner, all points on the surface of cutter  24  move on a circular arc, so that an operation with little vibrations is made possible.  
         [0043]    Saw blade  10  has a plain surface and transits into curved cutter  24 , starting from fixing receptacle  26 , via two concave curved lateral edges  28 ,  30  and adjoining hereto short straight lateral edge sections  32  or  34 , respectively. In the top view according to FIG. 1, saw blade  10  has, thus, approximately the shape of a mushroom.  
         [0044]    Cutter  24 , which consists of a plurality of single saw teeth  22 , has a first middle section  12 , a second section  14  and a third section  16 , which adjoin as lateral sections  14 ,  16  on the one or on the other side of first section  12 , respectively, and end in a first end  18  or in a second end  20 , respectively, at the transition to the straight lateral edge sections  32  or  34 , respectively.  
         [0045]    Alongside second and third sections  14 ,  16 , saw teeth  22  are arranged having a smaller distance to each other, i.e. with a smaller spacing than in first section  12 .  
         [0046]    It is to be understood that the representation in FIG. 1 is merely an example and schematically indicates merely one of the different possible embodiments. The size of teeth  22  shown and also the spacing in first section  12  and in two other sections  14 ,  16  does not necessarily correspond to the real dimensions and can be adjusted to the respective material to be sawed. For example, the spacing of sections  14 ,  16  can become 0, i.e. sections  14 ,  16  are configured as smooth knives or are provided with an undulated grinding.  
         [0047]    For harder and tougher materials, such as metals, in first section  12  as well as in the other two sections  14 ,  16 , smaller teeth  22  and basically smaller spacing will generally be used than e.g. on a saw blade configured for working wood or plastic. Moreover, also the angled regions can, of course, be varied. While, in the embodiment shown in FIG. 1, the first section, starting from fixing receptacle  26 , extends over an angle of approximately 40°, and the two sections each extend over an angle of approximately 20°, these relations can also be adjusted depending on the desired application.  
         [0048]    Further, it is also possible, to configure merely one of the two lateral sections  14 ,  16  deviating from middle section  12  instead of configuring both lateral sections  14 ,  16  deviating from the middle section  12  having a constant spacing or set of saw teeth. This would make sense, if e.g. the saw blade concerned is to be applied always from one side, and, subsequently, the work is to be continued mainly with the remaining region.  
         [0049]    By means of the embodiment shown in FIG. 1, an easy and exact applying and a simple beginning of the cut at one of the two lateral sections  14 ,  16  is made possible, while, subsequently, for the sake of a higher feed, the work is continued with the middle section or with first section  12 .  
         [0050]    It is to be understood that, in addition, instead of a distribution into a middle section and two lateral sections, also further sections can be provided, within same the spacing is further varied, preferably to an intermediate value between adjacent sections.  
         [0051]    When the spacing is determined, also the coarsest spacing is suitably chosen so small that it is smaller than the circular arc spanned by the pivot angle of the oscillation drive of e.g. 0.5-5°.  
         [0052]    In FIG. 2, a variation of the embodiment according to FIG. 2 is shown and altogether designated with the numeral  10   a.    
         [0053]    For corresponding parts, corresponding reference numerals followed by a are used. The outer shape of the embodiment according to FIG. 2 is essentially equal to the embodiment according to FIG. 1.  
         [0054]    A first difference is a modified shape of the receptacle opening  26   a  that is configured as a star-shaped polygon in order to allow a positive engaging with a suitably shaped receptacle socket of a drive shaft of the associated oscillation drive, as it is generally already known.  
         [0055]    Further, cutter  24   a  of saw blade  10   a  differs from saw blade  10  described before by the fact that the spacing of saw teeth  22   a  from the center of first center section  12   a  continuously decreases into the direction of the two ends  18   a  or  20   a , respectively.  
         [0056]    A further modification of a saw blade according to the invention is shown in FIG. 3 and designated altogether with the reference numeral  10   b . For corresponding parts also herein, again, corresponding reference numerals followed by b are used.  
         [0057]    Saw blade  10   b  has a longitudinal shape and has, starting from fixing receptacle  26   b , two lateral edges being parallel to each other, which each, in a front region facing away from fixing receptacle  26   b , form a taper into the direction of the center, and transit into cutter  24   b  via short straight sections  32   b  or  34   b , respectively, that extend inclined outwardly.  
         [0058]    Cutter  24   b  has a first middle straight section  12   b  that extends tangentially with respect to fixing receptacle  26   b , a second straight section  14   b  adjoining at one side, and a third straight section  16   b  adjoining at the other side, both straight sections transiting in a small angle          of approximately 2-10° into first section  12   b.    
         [0059]    Again, the spacing of saw teeth  22   b  in the region of first section  12   b  is larger than in the region of the two lateral sections  14   b  or  16   b , respectively.  
         [0060]    It is to be understood that instead also first section  12   b  as well as two lateral sections  14   b ,  16   b  can be configured in a continuously linear manner.  
         [0061]    In FIGS. 4 and 5, another alternative is explained for the saw blade according to the invention which utilizes a variation of the set of saw teeth.  
         [0062]    In FIG. 4, a partial section through a saw blade  10   c  according to the invention in the edge region of saw teeth  22   c  is shown. Saw blade  10   c  has two tooth rows  40   c  or  42   c , respectively, which protrude over one outer surface  36   c  or over the other outer surface  38   c , respectively. These two tooth rows  40   c  or  42   c , respectively, define two planes, the distance between which is d 1 , as shown in FIG. 4.  
         [0063]    This dimension d 1  is larger than thickness d of saw blade  10   c . The individual teeth  22   c  of saw blade  10   c  alternately protrude outwardly over one outer plane  38   c  or over other outer plane  36   c , respectively.  
         [0064]    For saw blade  10   c , now the set of saw teeth defined in this way is varied such that in the center area of the saw blade a larger set of saw teeth, i.e. a larger dimension d 1  is used than at the lateral sections.  
         [0065]    By means of a larger set of saw teeth, a stronger cut and a larger feed is made possible, whereas, with a smaller set of saw teeth, a more precise cut with a low feed is made possible. If, thus, the set of saw teeth is smaller in the lateral sections than in the middle section, the saw blade can be applied more easily, whereas, subsequently, it is possible to continue work quicker with the middle section.  
         [0066]    It is to be understood that, in addition to the set of saw teeth, the spacing of teeth  22   c  can be varied at the same time.  
         [0067]    A further alternative of a saw blade according to the invention is shown in FIG. 5 partially cut in the region of the saw teeth and designated altogether with the numeral  10   d.    
         [0068]    Again, corresponding reference numerals followed by d are used for corresponding parts.  
         [0069]    Saw blade  10   d  shown has the special feature that, in deviation of the embodiment shown in FIG. 4, two tooth rows  40   d  or  42   d , respectively, being distanced from each other are provided, between which, in the center, a spacing  44   d  is formed. The two tooth rows  40   d  and  42   d  are configured such that they each terminate outwardly flush with outer surfaces  36   d  or  38   d , respectively.  
         [0070]    In that way, a particularly precise cut is made possible, since distance d 1  of teeth  22   d  corresponds to thickness d of saw blade  10   d.    
         [0071]    In such an embodiment, of course, not the set of saw teeth is varied, but merely the spacing along the cutter.  
         [0072]    A variation of the embodiment according to FIG. 3 is shown in FIG. 6 and designated altogether with the numeral  10   e.    
         [0073]    This saw blade, too, has basically a longitudinal shape having a fixing receptacle  26   e  at the one end and a cutter  24   e  at the other end. Fixing receptacle  26   e , however, is not configured as a polygon opening, but as a circular opening. Cutter  24   e  is circular arc-shaped and has only two sections,  12   e ,  14   e , of which first section  12   e  has a finer spacing than second section  14   e.    
         [0074]    A further variation of the saw blade according to the invention is shown in FIG. 7 and designated altogether with the numeral  10   f.    
         [0075]    Saw blade  10   f  has herein a circular basic shape and is provided with cutter  24   f  at its edge. The cutter has four sections  12   f ,  14   f ,  16   f ,  17   f , which are provided with saw teeth of different spacing. In this embodiment, at section  12   f  with the smallest spacing, a section  14   f  with a somewhat larger spacing adjoins, followed by a section  16   f  with an even larger spacing, at which section  17   f  adjoins with the largest spacing, which adjoins at first section  12   f  of the finest spacing.  
         [0076]    Depending on the material to be worked or on the desired fineness of the cut, respectively, suitable sections  12   f ,  14   f  or  17   f  are used one after another in the working process.