Abstract:
A holder for a cutting tool for processing of workpieces has a first part for holding a cutting tool ( 150 ), a second part ( 120 ) to which the first part is fastened, and a fastening element ( 140 ). An adjustment element adjusts the position of the first part in relation to the second part. The first and second parts have a first bore and a second bore for receiving the fastening element and a recess ( 118, 128 ) for receiving the adjustment element. The first part has an abutment surface ( 115 ) placed onto a contact surface ( 122 ) of the second part, such that the central axes (A-A) for the first and second bores become parallel. The abutment surface of the first part and the contact surface of the second part are inclined in relation to the feeding axis (G-G) of the work piece towards the cutting tool ( 150 ).

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a National Stage of PCT International application no. PCT/SE2013/050501, filed 6 May  2013 , which claimed priority in Swedish Patent application no. 1250460-1, filed 7 May  2012 , the contents of these applications being incorporated herein by reference. 
     
    
     TECHNICAL FIELD 
       [0002]    The following invention belongs to the field of holders for cutting tools. It is especially related to a holder for cutting tools for processing of workpieces where the position of the cutting tool is adjustable. 
       BACKGROUND 
       [0003]    Holders for cutting tools for lathes are known in the field. In recent years, lathes with sockets for cutting tools with round shafts for horizontal processing of workpieces have become more and more common, such as machines for turning along. During turning along, the workpiece is held in place by means of a clamping sleeve in the same way as during traditional turning. 
         [0004]    Flatbed lathes have also become more common. It is often common for all of these machine types which are adapted for mass production to have axially mounted and often round holders fixed in a height direction. Tools that are to machine towards a center of the workpiece need in most cases to be adjusted with an accuracy of 0.01 mm in order to achieve the best product and the longest wear time. 
         [0005]    Regardless of turning technology, it is very important to be able to position the cutting tool in a machine as simply and as accurately as possible in relation to the workpiece. For that purpose, holders for cutting tools have been developed which comprise one or more pieces that are movable and adjustable. Adjustment of the position of the cutting tool is often performed via adjustment of a part of the holder by means of adjustment screws and fixed by one or more locking screws. 
         [0006]    An adjustable plate is most commonly used which can be attached to a corresponding fixed plate where one or two screws move one plate vertically or radially in relation to the longitudinal axis of the workpiece, while four or even more screws are used as locking screws in order to attach the plate to the fixed plate. The problem with such solutions is their complexity, making the adjustment of the position of the cutting tool time consuming. Moreover, such holders are expensive to produce and result in lower stability and precision. 
         [0007]    Another solution is shown in U.S Published patent application number US 2006/0230890 where a holder is composed of a detachable part to which a cutting tool can be attached and a fixed part. The detachable and the fixed part have a bore through which a locking screw can pass and thus lock the first part against the second part. The cutting tool can in that case only be adjusted in the radial direction, but not in the height direction. Even if this solution uses considerably less components than the solutions described earlier, the options for accurate adjustment of the position of the cutting tool are limited. 
         [0008]    It would thus be desirable to find a solution which simplifies the adjustment of the position of the cutting tool in a holder and which moreover achieves a more accurate adjustment of that position. It would also be desirable to apply such a solution to older machines where the position of the cutting tool needs to be adjusted in the height direction. 
       SUMMARY OF THE INVENTION 
       [0009]    The present invention aims at solving at least some of the problems with previously known technology. 
         [0010]    One solution is achieved by a holder for a cutting tool for processing workpieces, comprising a first part with a device for holding a cutting tool, and a second part to which the first part is adapted to be fastened. A fastening element is provided to fasten the first to the second part. An adjustment element is provided to adjust the position of the first part in relation to the second part, where the first and second parts have at least a first bore in the first part for receiving the fastening element and a second bore in the second part, and a recess for receiving the adjustment element. The first part further has an abutment surface adapted to be placed onto a contact surface of the second part, such that central axes for the first and the second bore become parallel. Further, the abutment surface for the first part and the contact surface for the second part are inclined with respect to a feeding axis of the workpiece toward the cutting tool. A central height of the cutting tool is adjusted by the adjustment element which is configured to define a distance between the adjustment element and the recess in the second part by turning the adjustment element. The fastening element is configured to move the first part in the direction of the central axis towards the second part and towards the adjustment element by turning. 
         [0011]    Advantageous embodiments are described further below. 
         [0012]    According to one aspect of the invention, the solution is achieved by a holder for cutting tools for processing of workpieces. The holder comprises a first part with means for holding a cutting tool and a second part to which the first part is adapted to be attached to. Furthermore, the holder further comprises a fastening element designed to fasten the first part to the second part and also an adjustment element designed to adjust the position of the first part in relation to the second part. The first part and the second part comprise at least a first bore for receiving the fastening element and a second bore and a recess for receiving the adjustment element. The first part further comprises an abutment surface configured to be placed onto a contact surface of the second part, such that the central axes of the first and second part become parallel such that the abutment surface for the first part and the contact surface for the second part are inclined in relation to a feeding axis for the workpiece towards the cutting tool. 
         [0013]    The advantage of this solution is simple assembly, fixing and adjustment of the two parts in the holder, such that as accurate a position as possible is achievable for the cutting tool. At the same time the holder according to the present invention gives a very stable construction such that the cutting forces at the cutting tool are balanced. The holder according to the present invention is also simple to manufacture and thus cost-effective. Finally, the holder is in principle suitable for any machine for processing of workpieces where accuracy of the position of the cutting tool is relevant. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0014]      FIG. 1  shows a cut-away view of one embodiment of the holder for a cutting tool. 
           [0015]      FIG. 2   a  shows a first variant of a first part of the holder for a cutting tool in a front view. 
           [0016]      FIG. 2   b  shows a variant of the bore for a locking screw in the first part of the holder. 
           [0017]      FIG. 2   c  shows another variant of the bore for a locking screw in the first part of the holder. 
           [0018]      FIG. 3  shows a cut-away view of a second variant of the holder. 
           [0019]      FIG. 4  shows the backside of the first part of the holder in  FIGS. 1 and 3 . 
           [0020]      FIG. 5  shows a third variant of the holder in a side view. 
           [0021]      FIG. 6  shows a fourth variant of the holder in a side view. 
           [0022]      FIG. 7  shows a fifth variant of the holder in a side view. 
           [0023]      FIG. 8  shows the backside of the first part of the holder in  FIG. 5 . 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0024]      FIG. 1  shows a holder for a cutting tool  100  according to a first embodiment. The holder  100  comprises a first removable part  110  and a second part  120  to which the first part  110  is adapted to abut. The second part  120  may further comprise a shaft  180  which can be rectangular, cylindrical or have any other shape as long as one can identify a central axis D-D in it. The shaft  180  is adapted to be attached to a machine for processing of different types of workpieces. The advantage of a holder with a removable first part is that it is easy to change the cutting tool once it is worn out. 
         [0025]    The first part  110  of the holder  100  which in this view and this embodiment has a form similar to a golf club head comprises a base portion  111  and an elongated portion  112 . The abutment surface  115  of the elongated portion  112  forms an outer angle β with the axis G-G which defines the feeding direction for the workpiece to be processed. The base portion  111  in the first part  110  comprises a base surface  114  which in the embodiment in  FIG. 1  is plain, but may have any shape. 
         [0026]    Furthermore, the first part  110  comprises a first through bore  116  and a second through bore  117  produced in the elongated portion  112  of the first part  110 . The position of the two through bores  116  and  117  in the first part is however not limited to any specific area on the elongated portion  112 , but may be situated close to the base portion  111  for stability reasons. The two through bores  116  and  117  are adapted to receive a fastening device which in this example is a locking screw  140 . However, other types of fastening devices are also possible, such as bolts, buttons and similar devices. In the embodiment in  FIG. 1 , the first bore hole  116  is somewhat wider than the second bore  117  in order to be able to receive the head of the locking screw, while the second bore  117  in terms of its size is adapted to let the locking screw  140  pass through it. 
         [0027]    The bores  116  and  117  in the first part  110  and the second part  120  may be made to be round or oval shaped. They may also be somewhat greater than the head of the locking screw  140  in order to allow for play when adjusting the position of the first part  110 . It is also possible to have an embodiment where one part or one half of the bore  116  is exposed. This is shown by the dotted line  119  in  FIG. 2   a . The advantage of such an embodiment of the bore  116  is that a greater play for the locking screw  140  is allowed and thus also a greater adjustment interval for the first part  110  in relation to the second part  120 . One other advantageous effect can be reached by designing the bore  116  such that it is somewhat inclined in relation to the central axis A-A for the bore  117  (see the bore  119 ′ in  FIG. 2   b ) or that a part of the bore  116  to the left of the central axis for the bore  117  is inclined in relation to the part of the bore  116  located to the right of the same bore as shown in  FIG. 2   b.    
         [0028]    In the embodiments shown in  FIGS. 2   b  and  2   c , the head of the locking screw  140 , during turning of the locking screw  140 , earlier reaches the bottom of the side of the bore  119 ′,  119 ″ located higher up. Moreover, the tensile force during turning the locking screw  140  is concentrated towards the middle of the backside (see  FIG. 6 ) of the first part  110 . 
         [0029]    The first part  110  also has a recess  113  for receiving a cutting tool  150 . The cutting tool  150  may have any shape as long as it can be contained and fixed in the recess  113 . The function of the cutting tool is processing of a workpiece (not shown) for example in a turning lathe or any other machine with a cutting function. As already mentioned earlier, the workpiece is fed to the cutting tool  150  in the direction of the G-G axis. 
         [0030]    In  FIG. 1 , the first part  110  also has a third through bore  118  at an end of the elongated portion  112  adapted to receive an adjustment device that, in this embodiment is made up of an adjustment screw  130 . The first part  110  is shown in more detail in  FIG. 2   a . The adjustment screw  130  is made such that its turning defines the interval within which the first part  110  may be adjusted in relation to the second part  120 . This will be explained in more detail further below. The third through bore  118  and the adjustment screw  130  in  FIG. 1  may advantageously be threaded. 
         [0031]    The second part  120  in turn has a first bore  126  adapted to receive the locking screw  140  that is to pass through the through bores  116  and  117  in the first part when the first part  110  is to be attached to the second part  120 . The first bore  126  is advantageously threaded when the attachment device is a threaded screw. 
         [0032]    Moreover, the second part  120  has a recess  128  with a flat bottom  129  adapted to receive the adjustment device  130  which also passes through the third bore  118  in the first part  110 . 
         [0033]    In this embodiment, the first part  120  has two plain side surfaces  123  and  124  and a chamfered and inclined portion  122 . The inclined portion  122  forms a contact surface for the abutment surface  115  of the first part when the first part  110  is to be attached to the second part  120  with the help of the locking screw  140 . Moreover, the inclined portion  122  forms an inner angle γ with the feeding axis G-G of the workpiece. 
         [0034]    In the following text, an explanation is given about how the removable first part  110  is fastened to the fixed second part  120 . 
         [0035]    As already mentioned earlier in the text, the abutment surface  115  of the elongated portion  112  forms an outer angle β with the axis G-G along which a workpiece is fed to the cutting tool  150  in the holder  100 . The abutment surface  115  is adapted to abut the contact surface  122  of the second part. The inclined or leaning surfaces  115 ,  122  give an extended abutment and thus greater stability than the plain or vertical or horizontal surfaces described earlier. 
         [0036]    Moreover, the inclined abutment surface  115  in the first part  110  and the contact surface  122  in the second part  120  provide a short distance to the lower side of the cutting tool  150 . 
         [0037]    If one wishes to adjust the central height of a cutting tool such as the central height for the cutting tool  150  in  FIG. 2   a , this may be done using the adjustment screw  130 . A turning of the adjustment screw  130  defines the distance between the adjustment screw and the bottom  129  of the recess  128  in the second part  120 . When turning the locking screw  140 , the first part is moved towards the second part  120  in the direction of the second part  120  along the tapered plane and towards the adjustment screw  130 . At the same time the adjustment screw is dragged towards the bottom  129  of the recess  128  in the second part  120 . The final fastening of the first part  120  to the second part  120  is achieved by the locking screw  140  passing the through bores  116 ,  117  in the first part  110  and into the bore  126  in the second part  120  through turning of the locking screw  140  until the lower side of the adjustment screw  130  reaches the bottom  129  of the recess  128 . 
         [0038]    Depending on how great the distance is between the lower side of the adjustment screw  130  and the lower side  129  of the recess which has been adjusted by turning the adjustment screw  130 , the position of the first part  110  may be adjusted to the desired accuracy in relation to the second part  120  in the direction of the arrow C. In  FIG. 2   a , the bore  118  is plain. When turning the locking screw  140  this means that the inclined surface  122  in the second part  120  concentrates the tensile force towards the center of the abutment surface  115  in the first part  110 , giving a stable fastening of the first part  110  towards the second part  120  of the holder  100 . 
         [0039]    In the embodiment with an inclined bore  116  in relation to the center axis A-A (see  FIG. 2   b ) of the bore  117 , movement of the first part  110  towards the adjustment screw  130  is achieved at the same time as the tensile force is concentrated towards the center of the inclined portion  115  in the first part  110 . A similar effect is achieved when one half of the bore  116  is inclined in relation to the center axis A-A of the bore  117  (see  FIG. 2   c ). The concentration of the tensile force towards the center of the back side of the first part  110  may also be achieved by exposing a part of the wall of the bore  116 , but in this case the forces during the turning of the locking screw are directed in the direction of the central axis A-A. 
         [0040]    The above described variant of the first part  110  and the second part  120  achieves a very simple construction of the holder  100  with only one fastening device  140  in the form of a locking screw and an adjustment device in the form of an adjustment screw  130 . 
         [0041]      FIG. 2   a  shows the second part  110  in a front view. It is worth pointing out here that the central axis A-A for both bores  116  and  117  does not necessarily need to be aligned with the central axis C-C for the bore  126  in the second part  120  when the fastening device  140  is turned. It is also conceivable that they form a blunt angle or are parallel. The through bore  117  formed in the elongated portion  112  may for the sake of stability be placed near or slightly above the center of the inclined plane  115  in the first part in order to be able to compensate as effectively as possible for the cutting forces which the cutting tool  112  is encountering. 
         [0042]      FIG. 3  illustrates another embodiment of the invention where the angle α between the plane PA in which the abutment surface  115  is located and the central axis A-A for both bores  116 ,  117  in the first part and the bore  126  in the second part  120  is located, is less than 90 degrees. Besides this difference, the embodiment of the holder  100  is very similar to the one presented in  FIG. 1  earlier on. The inclined abutting surfaces have as earlier explained the advantage of an extended abutment surface and thus better stability. 
         [0043]    Moreover, the angle α&lt;90 degrees between the central axis A-A of the through bores  116 ,  117  in the first part  110  and the plane PA have the advantage of a different type of fastening of the first part  110  to the second part  120 . During fastening, the locking screw  140  moves the first part  110  towards the adjustment screw  130  and the second part  120 . Moreover, during turning of the locking screw  140 , the first part also moves the adjustment screw  130  towards the bottom of the recess  129  as shown in  FIG. 1 . The difference here however is that the locking screw  140  during turning is locked at the adjustment screw  130  due to the inclined position of the bores  116 ,  117  and bore  326 . 
         [0044]      FIG. 4  illustrates the back of the first part  110  of the holder  100  in a front view with the through bore  117  visible. In this embodiment, the first part  110  has been equipped with a corrugated abutment surface  416 . The abutment surface  122  of the second part may advantageously also be corrugated, such that movement of the first part in relation to the second part in the tapered plane is minimized. The backside may instead of the corrugated structure also have two or more grooves which are movable in corresponding protrusions on the contact surface of the second part (not shown). 
         [0045]      FIG. 5  illustrates a third embodiment of the holder  100  where a modified adjustment device  500  is used along with a spring loaded piston  510  located inside the second part  120 . 
         [0046]    The modified adjustment device  500  which in this example is an adjustment screw  500  consists of a plain portion  502  and an inclined portion  504 . The purpose of the inclined portion  504  is to receive an end of the spring loaded piston  510  that via a compression spring  512  pushes the adjustment screw  500  towards the lower part of the recess  128  in the second part  120 . During turning of the locking screw  140 , the first part  110  is moved towards the second part  120  and the locking screw  500 . Moreover, the movement of the first part  110  also moves the adjustment screw  500  towards the bottom of the recess  128  as described earlier. Moreover, the spring loaded piston  510  presses the first part  110  and the adjustment screw  500  towards the second part  120 . When the first part  110  has been locked to the second part  120  of the holder  100 , the spring loaded piston  510  keeps the modified adjustment screw  500  in place and has a stabilizing effect on it. In  FIG. 5  the central axis E-E for the spring loaded piston  510  and the central axis F-F for the third through hole in the first part  110  and the recess  128  in the second part  120  form an angle δ. The angle may advantageously be selected such that it has a maximum effect when fastening the first part  110  to the second part  120 . 
         [0047]    The inclined portion  504  may also be formed as a spherical protrusion, such that a spherical end of the spring loaded piston  510  may be held in such a recess of the adjustment screw (not shown). 
         [0048]      FIG. 6  illustrates a fourth variant of the holder  100  in a cut-away view. In this case, the first part  100  has been equipped with a recess  102  adapted to receive a spring loaded sphere  164  which in turn is located in a fourth bore  160  in the lower portion of the second part  120 . The spring loaded sphere is held in place by a second locking screw  170 . Besides the stability advantages given by the spring loaded piston in  FIG. 4 , this variant is somewhat simpler to manufacture than the embodiment in  FIG. 5  and the spring force is concentrated towards the first part  110  instead of the adjustment screw  500  in the solution in  FIG. 5 . 
         [0049]    The central axis H-H for the fourth bore  160  may advantageously be chosen such that the angle θ between the central axis H-H and the plane PA gives maximum stability during turning of the second locking screw  170 . The same is true for the angle φ between the central axis I-I of the second locking screw  170  and the plane PA. 
         [0050]      FIG. 7  illustrates a fifth variant of the holder where only the second part  120  is shown. The first part  110  is still equipped with a recess (not shown) which in terms of its size is adjusted to receive the sphere  164 . The difference to the embodiment in  FIG. 6  is that the locking of the spring loaded sphere  164  is effected by a locking pin in the second part  120 . The rest of the construction in  FIG. 7  is very similar to the one in  FIG. 6  having the same advantages as the latter. 
         [0051]      FIG. 8  illustrates the backside  700  of the first part  110  from the embodiment in  FIG. 7 . The backside is analogous to the backside in  FIG. 4  being corrugated  720  in order to be able to move against the abutment surface  122  in the second part which in turn is corrugated in a corresponding way to facilitate movement of the first part  110  in the second part  120  in the direction of the arrow C (see the arrow C in  FIG. 1 ). 
         [0052]    Moreover, the backside  700  comprises an elliptical through bore  117  through which the locking screw  140  is adapted to pass. Also, the backside  700  has a recess  102  which, similar to previous explanations, is adapted to receive a spring loaded sphere  164 . Additionally, the backside  700  in the first part  110  comprises a recess  104  for receiving a locking pin from  FIG. 7  which locks the movement of the sphere  164  inside the first part  110 . 
         [0053]    It is worth pointing out that the embodiments described earlier constitute only examples of the present invention and should not be construed as limitations of the present invention. 
         [0054]    Even if the present invention is mentioned in the context of cutting tools for turning lathes, the holder as such is adapted to hold any type of cutting tool where the stability of the cutting tool is of importance. Thus the holder according to the present invention can be used to hold cutting tools for processing of small and elongated workpieces, but also bigger workpieces of in principle arbitrary size. 
         [0055]    It is moreover worth stressing that even if the second part  120  in all the illustrated embodiments is connected to a shaft  180  of one or other shape, the invention works even without the presence of a shaft  180 . The backside  124  of the second part  120  may itself be fixed in a machine for machining of workpieces without being connected to a shaft. 
         [0056]    A skilled person may after reading of the detailed description together with the accompanying drawings realize that there exist more than the earlier described two embodiments of the present invention. 
         [0057]    Ultimately, the scope of the invention is only limited by the scope of the patent claims.