Abstract:
A tool for chip removing machining includes a holder and at least one cutting insert received in the holder. The holder is provided with at least one insert pocket, in which the cutting insert is intended to be received, and an opening connected to the insert pocket. The insert pocket has a first holding member provided along the periphery of the insert pocket, and the cutting insert has an anchor section and an edge portion connected to the anchor section. A second holding member is provided along the circumference of the anchor section. The first and the second holding members are intended to cooperate when the cutting insert is mounted in the insert pocket. The periphery of the insert pocket, at least partly, is defined by one or more circular arcs with a common center of rotation. The anchor section is provided with a number of holding members distributed along its circumference, and portions of these holding members located furthest away from of the cutting insert center are defined by circular arcs having a common center of rotation. The circular arcs are located at the same distance from the common center of rotation.

Description:
[0001]     The present invention relates to a tool and a cutting insert for chip removing machining.  
         [0002]     It is previously known through U.S. Pat. No. 4,443,136 to provide a tool for cutting machining, wherein a holder forming a part of the tool is provided with a recess with an opening, in which recess a disc-shaped cutting insert forming a part of the tool is intended to be mounted. The recess is generally circular and provided with either positive or negative guiding means that are intended to cooperate with negative or positive guiding means of the cutting insert, wherein the latter guiding means are provided along a part of the circumference of the cutting insert. These guiding means are made of ridges or grooves. The guiding means are provided diametrically with respect to each other both in the recess and on the cutting insert. The cutting insert has such a shape that it can be moved into in the opening of the recess, whereafter the guiding means are brought to cooperate by rotating the cutting insert around a center axis that generally has an extension across the principal plane of the disc-shaped cutting insert. The clamping of the cutting insert in the holder occurs by means of an eccentric locking principle.  
         [0003]     Another known tool, U.S. 2002/0057950 A1, for chip removing machining comprises a holder and a cutting insert mountable in the holder. The holder has a generally cylindrical recess, which is provided with an opening and the cutting insert has a corresponding generally cylindrical section, which is intended to be received by the recess. The cylindrical section is provided with axial ribs, which in mounted state of the cutting insert occupies grooves of the recess. The mounted state of the cutting insert is achieved by rotating the cylindrical section a certain angle around its longitudinal center axis.  
         [0004]     A drawback of the above-discussed prior art is i.a. related to lateral stability of the cutting insert in the holder, i.e. there are tendencies of tilting of the cutting insert, especially during longitudinal turning.  
         [0005]     It is desirable to provide a tool of the type indicated above, wherein the cutting insert is locked with respect to the holder when it is brought to assume its operative position in the holder.  
         [0006]     It is also desirable to provide a tool and an insert where the mounting of the cutting insert in the holder is extraordinarily simple.  
         [0007]     It is also desirable to provide a tool and an insert where the cutting insert obtains an extraordinary rigid mounting in the holder.  
         [0008]     It is also desirable to provide a tool and an insert whereby the user shall obtain an indication when the cutting insert has obtained a correct, operative position in the holder.  
         [0009]     In accordance with an aspect of the present invention, a tool for chip removing machining is provided. The tool comprises a holder and at least one cutting insert received in the holder. The holder comprises at least one insert pocket for receiving the cutting insert and an opening connected to the insert pocket, the insert pocket having a first holding member provided along a periphery of the insert pocket. The cutting insert has an anchor section and an edge portion connected to the anchor section, a second holding member being provided along a periphery of the anchor section. The first and the second holding members are adapted to cooperate when the cutting insert is mounted in the insert pocket. The periphery of the insert pocket, at least partly, is defined by at least one circular arc of the pocket, the at least one pocket arc having a pocket arc center of rotation, and at least a portion of the second holding member located furthest away from a cutting insert center is defined by a circular arc of the insert having an insert arc center of rotation, the insert arc being located at a distance from the insert arc center of rotation.  
         [0010]     In accordance with another aspect of the present invention, a cutting insert intended to form part of a tool for chip removing machining is provided. The cutting insert comprises an anchor section and a holding member provided along the periphery of the anchor section. At least a portion of the holding member located furthest away from a cutting insert center is defined by a circular arc of the insert having an insert arc center of rotation, the insert arc being located at a distance from the insert arc center of rotation. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0011]     Below embodiments of the present invention will be described with reference to the enclosed drawings, wherein:  
         [0012]      FIG. 1  shows a side view of a holder forming a part of the tool;  
         [0013]      FIG. 2  shows a right-hand view of the holder according to  FIG. 1 ;  
         [0014]      FIG. 3  shows a side view of a cutting insert forming a part of the tool;  
         [0015]      FIG. 4  shows a right-hand view of the cutting insert according to  FIG. 3 ;  
         [0016]      FIG. 5  shows a side view during mounting of the cutting insert in the holder;  
         [0017]      FIG. 6  shows a perspective view during mounting of the cutting insert in the holder;  
         [0018]      FIG. 7  shows a side view of when the cutting insert is mounted in the holder;  
         [0019]      FIG. 8  shows a perspective view obliquely from the front when the cutting insert is mounted in the holder;  
         [0020]      FIG. 9  shows a cross-section along the line IX-IX in  FIG. 7 ;  
         [0021]      FIG. 10  shows a side view of a holder forming a part of the tool at a first alternative embodiment according to the present invention;  
         [0022]      FIG. 11  shows a right-hand view of the holder according to  FIG. 10 ;  
         [0023]      FIG. 12  shows a side view of a cutting insert forming a part of the tool according to the first alternative embodiment;  
         [0024]      FIG. 13  shows a right-hand view of the cutting insert according to  FIG. 12 ;  
         [0025]      FIG. 14  shows a side view during mounting of the cutting insert in the holder;  
         [0026]      FIG. 15  shows a perspective view obliquely from the front during mounting of the cutting insert in the holder;  
         [0027]      FIG. 16  shows a side view of when the cutting insert is mounted in the holder;  
         [0028]      FIG. 17  shows a perspective view obliquely from the front when the cutting insert is mounted in the holder;  
         [0029]      FIG. 18  shows a cross-section along the line XVIII-XVIII in  FIG. 16 ;  
         [0030]      FIG. 19  shows a side view of a holder forming a part of the tool of a second alternative embodiment according to the present invention;  
         [0031]      FIG. 20  shows a right-hand view of the holder according to  FIG. 19 ;  
         [0032]      FIG. 21  shows a side view of a cutting insert forming a part of the tool according to the second alternative embodiment;  
         [0033]      FIG. 22  shows a right-hand view of the cutting insert according to  FIG. 21 ;  
         [0034]      FIG. 23  shows a side view during mounting of the cutting insert in the holder;  
         [0035]      FIG. 24  shows a perspective view obliquely from the front during mounting of the cutting insert in the holder;  
         [0036]      FIG. 25  shows a side view of when the cutting insert is mounted in the holder;  
         [0037]      FIG. 26  shows a perspective view obliquely from the front when the cutting insert is mounted in the holder;  
         [0038]      FIG. 27  shows a cross-section along the line XXVII-XXVII in  FIG. 25 ;  
         [0039]      FIG. 28  shows a side view of a holder forming a part of the tool at a third alternative embodiment according to the present invention;  
         [0040]      FIG. 29  shows a right-hand view of the holder according to  FIG. 28 ;  
         [0041]      FIG. 30  shows a side view of a cutting insert forming a part of the tool according to the third alternative embodiment;  
         [0042]      FIG. 31  shows a right-hand view of the cutting insert according to  FIG. 30 ;  
         [0043]      FIG. 32  shows a side view during mounting of the cutting insert in holder;  
         [0044]      FIG. 33  shows a side view of when the cutting insert is mounted in the holder; and  
         [0045]      FIG. 34  shows a perspective view obliquely from the front when the cutting insert is mounted in the holder. 
     
    
     DETAILED DESCRIPTION  
       [0046]     The holder  1  shown schematically in  FIGS. 1 and 2  comprises an insert pocket  3 , which at its upper part is defined by a clamping arm  4  and at its lower part is defined by a support section  6 . The insert pocket  3  is provided with an opening  5 . First holding means are provided on the periphery  2  of the insert pocket  3  in the shape of ridges  7 ,  7 ′, which in the shown embodiment are three pieces. The portions of the ridges  7 ,  7 ′located closest to a first center C 1  of the insert pocket  3  are in a side view generally defined by a circular arc. Said circular arc is generated by rotating a first radius R 1  around the first center C 1 . The height of the ridges  7 ,  7 ′ is 5-25% of the radius R 1 .  
         [0047]     As shown in  FIG. 1  the ridges  7  are spaced by two first recesses  9 , which have a depth in principle corresponding to the height of the ridges  7 . The partition between adjacent recesses  9  is 90°. In the view shown in  FIG. 1  the recesses  9  have a rounded shape. The topmost located ridge  7 ′ in  FIG. 1  is provided with a second recess  10 , which has a smaller depth than the first recess  9 . Also the second recess  10  has a rounded shape in the view shown in  FIG. 1 . The second recess  10  is shorter than the first recess  9  in the lateral direction of the holder  1 .  
         [0048]     The cutting insert  11  shown in  FIGS. 3 and 4  is generally disc-shaped and has an anchor section  12 , which in a side view generally has the shape of a circular arc. The cutting insert  11  is provided with a central hole  13 , which in the shown embodiment is provided with radial cut-outs. The cutting insert  11  also comprises a radially protruding cutting edge section  15 , a cutting edge  16  for grooving or parting being provided on its radially outermost located portion, relative to the center C 2  of the hole  13 .  
         [0049]     In the shown embodiment the anchor section  12  along its circumference is provided with three lip pairs  17  protruding from the circumference  14 , wherein the partition between adjacent lip pairs  17  is 90°. The lip pairs  17  have in a side view a rounded shape and in terms of dimensions they are adapted to recesses  10  along the periphery of the holder  1 . Each lip pair comprises two lips  17   a ,  17   b , which have a V-shaped groove  18  in-between. The groove  18  constitutes a second holding means. Every single one of the V-shaped grooves  18  has a certain extension along the circumference  14  of the anchor section  12 . Normally the grooves  18  have the same extension along the circumference  14  as the associated lips  17 . The V-shaped bottom of the grooves  18  is located centrally on the envelope surface of the anchor section  12 , seen in the thickness direction of the anchor section  12 . In a side view, as illustrated by  FIG. 3 , the groove  18  is defined by a circular arc, which is generated by a second radius R 2  being rotated around a second center point C 2 .  
         [0050]     When mounting the cutting insert  11  in the holder  1 , this is done from the side. At the initial position the holder  1  and the cutting insert  11  are positioned parallel to each other and the anchor section  12  of the cutting insert  11  is located right in front of the insert pocket  3 , wherein the holder  1  and the cutting insert  11  in principle have the orientation with respect to each other as shown in  FIG. 5 . Subsequently the holder  1  and the cutting insert  11  are displaced with respect to each other, wherein the holder  1  and the cutting insert  11  still are parallel to each other, until the cutting insert  11  is received by the insert pocket  3 . Thereby two of the lip pairs  17  will be received by the first recesses  9  while the third lip pair  17  is located in connection with the opening  5  of the holder  1 . When the holder  1  and the cutting insert  11  are located in a common plane the cutting insert  11  is rotated with respect to the holder  1 , from the position shown in  FIGS. 5 and 6  to the position shown in  FIGS. 7 and 8 . Thereby the ridges  7 ,  7 ′ of the insert pocket  3  will be received by the V-shaped grooves  18  of the respective lip pair  17 . As shown in  FIGS. 7, 8  and  9  the cutting insert  11  will thus be guided by the holder  1  at six points, two in each lip pair  17 , along the periphery of the insert pocket  3 . This guarantees that the cutting insert  11  obtains an extraordinarily rigid anchorage in the holder  1 .  
         [0051]     The rotation of the cutting insert  11  is suitably done with a key (not shown) that is placed in the hole  13 , wherein the key may be of the type Torx® (registrered trade mark of Camcar Textron).  
         [0052]     By studying  FIGS. 5 and 7  it is obvious that when the cutting insert  11  has been rotated to the position shown in  FIG. 7  the topmost lip  17  will come to engagement with the second recess  10 , wherein the topmost lip  17  snaps into the second recess  10 . The rotation of the cutting insert  11  from the position shown in  FIGS. 5 and 6  to the position shown in  FIGS. 7 and 8  will be done during deflection of the clamping arm  4 . By the lip  17  snapping into the second recess  10  an indication is obtained that the cutting insert  11  has obtained its operative, correct position. A portion of the support section  6  at the opening  5  will preferably be struck by a straight portion of the lower portion of the cutting insert  11  in connection with the lip  17  snapping into the second recess  10 , to support the cutting insert during machining. Since the cutting edge section  15  of the cutting insert  11  normally is not subjected to any upwardly directed force the cooperating position between holder  1  and the cutting insert  11  as is shown in  FIGS. 7 and 8  will function excellently in normal cases.  
         [0053]     In  FIGS. 10-18  a first alternative embodiment of a tool according to the invention is shown. The holder  101  forming a part of the tool comprises an insert pocket  103 , which at its upper part is defined by a clamping arm  104  and at its lower part is defined by a support section  106 . In a side view the insert pocket  103  generally has the shape of a circular arc. An opening  105  is connected to the insert pocket  103 . A clear principal difference in relation to the holder  1  in the above-described embodiment is that the insert pocket  103  along its periphery is provided with first holding means in the shape of a groove  107  extending along its periphery, which generally has a V-shaped cross-section. The bottom of the groove  107  defines the periphery  102  of the insert pocket  103 , which has the shape of a circular arc. This circular arc is generated by a first radius R 1  being rotated around a first center point C 1 . The holder  101  is provided with a first recess pair  109  and a second recess pair  110  in the area of the upper part of the holder  101  in  FIGS. 10 and 11 , wherein these pair recesses  109 ,  110  have an extension lateral to the principle plane of the holder  101 . The recesses  109 ,  110  cut through the side faces of the holder  101 . Preferably both recess pairs  109 ,  110  are identical.  
         [0054]     The cutting insert  111  forming a part of the tool is generally disc-shaped and has an anchor section  112 , the circumference  114  of which in a side view is generally defined by a circular arc, wherein this circular arc is generated by a second radius R 2  being rotated around a second center point C 2 . The cutting insert  111  is provided with a central hole  113 . The cutting insert  111  also comprises a radially protruding cutting edge section  115 , a cutting edge  116  for grooving or parting being provided on its radially outermost located portion, relative to the center of the hole  13 . The anchor section  112  is along its circumference  114  provided with a continuous ridge  118 , which generally has V-shaped cross-section and constitutes second holding means of the cutting insert  111 . The tip of the ridge  118  coincides with the circumference of the anchor section  112 . The cutting insert  111  also has a lip pair  117 A,  117 B in the area of the upper part of the anchor section  112  in  FIGS. 12 and 13 , wherein each of the lips  117 A,  117 B has a surface that coincides with the adjoining side surface of the cutting insert  111 . The lips  117 A,  117 B of each pair are located, in a side view, right in front of each other, on each side of the ridge  118 , and they have identical dimensions. The dimensions of the lips  117 A,  117 B are also adapted to the dimensions of the recess pairs  109  and  110 , which will be illustrated below.  
         [0055]     When mounting the cutting insert  111  in the holder  101  this is done from the front, i.e. from the right in  FIGS. 10 and 14 . Thereby the cutting insert  111  is orientated with respect to the holder  101  as is shown in  FIGS. 14 and 15 , said lips  117 A,  117 B not interfering with the opening  105  when the cutting insert  111  is brought into the insert pocket  103 . When the lips  117 A,  117 B are received by their first respective recess pair  109  of the holder  101  the first part of the mounting process is finished. In the next part of the mounting process the cutting insert  111  is rotated from the position shown in  FIGS. 14 and 15  to the position shown in  FIGS. 16 and 17 . Thereby, the lips  117 A,  117 B will be transferred from the first recess pair  109  to the second recess pair  110 , whereby this transfer will occur during simultaneous deflection of the clamping arm  104 . When the lips  117 A,  117 B snaps into the second recesses  110  it is an indication that the cutting insert  11  has obtained a correct position in the holder  101 , wherein also the ridge  118  has correctly occupied the groove  107 . A portion of the support section  106  at the opening  105  will preferably be struck by a straight portion of the lower portion of the cutting insert  111  in connection with the lips  117 A and  117 B snapping into the second recess  110 , to support the cutting insert during machining. Especially when it comes the second recess pair  110  and the lips  117 A,  117 B it is important that these have such a mutual dimensional relation that the lips  117 A,  117 B are conveyed a satisfactory support when they are received in the second recess pair  110 .  
         [0056]     In  FIGS. 19-27  a second alternative embodiment of the invention is shown. The holder  201  forming a part of the tool comprises an insert pocket  203 , which at its upper part is defined by a clamping arm  204  and at its lower part is defined by a support section  206 . In a side view the parts of the periphery  202  of the insert pocket  203  that cooperate with the cutting insert  211  are generally defined by circular arcs. An opening  205  is connected to the insert pocket  203 . A clear principal difference in relation to the holder  101  in the above-described first alternative embodiment is that the insert pocket  203  has a clearance  208  in a direction away from the opening  205 . The clearance is formed due to the cutting insert  211  having a special shape, which will be described below. In the corresponding way as in the embodiment according to  FIGS. 10-18  the insert pocket  203  has second holding means extending along the periphery that however are divided into two grooves  207  by the clearance  208 . The grooves  207  generally have V-shaped cross-section and the bottom of the grooves  207  define the periphery  202  of the insert pocket  203 , which has the shape of a circular arc. This circular arc is generated by a first radius R 1  being rotated around a first center point C 1  of the insert pocket  203 .  
         [0057]     The upper part of the holder  201  is provided with a first recess pair  210 A and provided with a second recess pair  210 B at its lower part, wherein these recess pairs  210 A,  210 B have an extension laterally to the principle plane of the holder  201 . With principal plane is meant a plane parallel to the opposite faces of the holder  201 . The recesses  210 A,  210 B cut through the side faces of the holder  201 . Preferably both recess pairs  210 A,  210 B are identical.  
         [0058]     The cutting insert  211  forming a part of the tool is generally disc-shaped and has an anchor section  212 , the circumference  214  of which in a side view is generally defined by a circular arc, wherein this circular arc is generated by a second radius R 2  being rotated around a second center point C 2 . The cutting insert  211  is provided with a central hole  213 . An important principal difference between the cutting insert  211  and the above-described cutting insert  111  is that the cutting insert  211  comprises two radially protruding cutting edge sections  215  with a 180° partition along the circumference. The anchor section  212  is provided with two ridges  218  along its circumference  214 , which generally have V-shaped cross-sections and constitute second holding means of the cutting insert  211 . The tips of the ridges  218  coincide with the circumference  214 . The cutting insert  211  also comprises four lips, which are provided in pairs, lips in each pair being provided on opposed sides on the anchor section  212 , and each lip  217  has a surface that coincides with the adjoining side surface of the cutting insert  211 . The lips  217  are pair wise located right in front of each other in a side view, on each side of the respective ridge  218 , and they have identical dimensions. The dimensions of the lips  117 A,  117 B are also adapted to the dimensions of the recesses  210 A and  210 B, in the corresponding way as in the first alternative embodiment.  
         [0059]     When mounting the cutting insert  211  in the holder  201  this is done in principle in the same way as in the first alternative embodiment of a tool according to the present invention, i.e. from the right in  FIGS. 19 and 23 . Thereby the cutting insert  211  is orientated with respect to the holder  201  as is shown in  FIGS. 23 and 24 , wherein the lips  217  do not interfere with the opening  205  when the cutting insert  211  is brought into the insert pocket  203 . When the cutting insert  211  is wholly inserted into the insert pocket  203 , as illustrated by  FIGS. 23 and 24 , of the holder  201  the first part of the mounting process is finished. Thereby the lip pairs  217  are located beside the recess pairs  210 A and  210 B. In next part of the mounting process the cutting insert  211  is rotated from the position shown in  FIGS. 23 and 24  to the shown situation in  FIGS. 25 and 26 . Thereby each lip pair  217  will be received by the respective recess pair  210 A,  210 B. It is important that the recess pairs  210 A,  210 B and the lip pairs  217  have such a mutual dimensional relation that the lips  217  are conveyed a satisfactory support when they are snapped into the recesses  210 A,  210 B. In connection with the lips  217  being received by the recesses  210 A,  210 B the ridges  218  will also in a satisfactory way be received by the grooves  207 . A portion of the support section  206  at the opening  205  will preferably be struck by a straight portion of the lower portion of the cutting insert  211  in connection with the lips  217  snapping into the second recess  210 A and  210 B, to support the cutting insert during machining. The cutting insert  211  is thereby steadily secured in the holder  201 .  
         [0060]     In  FIGS. 28-34  a third alternative embodiment of the invention is shown. The holder  301  forming a part of the tool comprises an insert pocket  303 , which partly is defined by an engagement portion  304  and partly by a support section  306 . The insert pocket  303  is provided with an opening  305 . First holding means are provided in the shape of ridges  307  on the periphery of the insert pocket  303 , which in the shown the embodiment are three pieces. In a side view the sections of the ridges  307  located closest to a first center C 1  of the insert pocket  303  are generally defined by a circular arc. This circular arc is generated by a first radius R 1  being rotated around the first center C 1 . The height of the ridges  307  is 5-25% of the radius R 1 .  
         [0061]     As shown in  FIG. 28  the ridges  307  are spaced by two first recesses  309 , which have a depth that in principle corresponds to the height of the ridges  307 . The partition between the adjacent recesses  309  is 90°. In the view shown in  FIG. 28  the recesses  309  have a rounded shape.  
         [0062]     The cutting insert  311  shown in  FIGS. 30 and 31  is generally disc-shaped and has an anchor section  312 , which in a side view generally has the shape of a circular arc. The cutting insert  311  is provided with a central hole  313 , which in the shown embodiment is provided with radial cut-outs. The cutting insert  311  also comprises a radially protruding, fingerlike cutting edge section  315 , a cutting edge  316  for grooving or parting being provided on its radially outermost located portion relative to the center C 2  of the hole  313 .  
         [0063]     In the shown embodiment the anchor section  312  along its circumference is provided with three lip pairs  317  protruding from the circumference  314 . The partition between the lips  317  is 90°. The lips  317  have in side view a rounded shape and in terms of dimension they are adapted to the recesses  310  along the periphery of the holder  301 . Each lip pair comprises two lips  317 A,  317 B, which in-between have a V-shaped groove  318 . The groove  318  constitutes a second holding means. Each of the V-shaped grooves  318  has a certain extension along the circumference  314  of the anchor section  312 . Normally the grooves  318  have a corresponding extension along the circumference  314  as the associated lips  317 . The bottom of the V-shaped grooves  318  is located right in the middle of the envelope surface of the anchor section  312 , seen in the thickness direction of the anchor section  312 . In a side view, as illustrated by  FIG. 30 , the groove  318  is defined by a circular arc, which is generated by a second radius R 2  being rotated around a second center point C 2 .  
         [0064]     When mounting the cutting insert  311  in the holder  301  this is done from the side. In the initial position the holder  301  and the cutting insert  311  are positioned parallel to each other and the anchor section  312  of the cutting insert  311  is located right in front of the insert pocket  303 , wherein the holder  301  and the cutting insert  311  in principle have the orientation with respect to each other as shown in  FIG. 32 . Subsequently the holder  311  and the cutting insert  311  are displaced with respect to each other, wherein the holder  301  and the cutting insert  311  still are parallel to each other, until the cutting insert  311  is received by the insert pocket  303 . Thereby the two lip pairs  317  will be received by the first recesses  309 . When the holder  301  and the cutting insert  311  are located in a common plane the cutting insert  311  is rotated with respect to the holder  311 , from the position shown in  FIG. 32  to the position shown in  FIGS. 33 and 34 . Thereby the ridges  307  of the insert pocket  303  will be received by the V-shaped grooves  318  of the respective lip pair  317 . As shown in  FIGS. 33 and 34  the cutting insert  311  will thus be guided by the holder  311  at four points, two in each lip pair  317 , along the periphery of the insert pocket  303 . This guarantees the cutting insert  311  to obtain a rigid anchorage in the holder  301 .  
         [0065]     The rotation of the cutting insert  311  is suitably done with a key (not shown) that is placed in the hole  313 , wherein the key may be of the type Torx®.  
         [0066]     By studying  FIGS. 32 and 33  it is obvious that when the cutting insert  311  has been rotated to the shown position the lower side of the fingerlike cutting edge section  315  will abut against the support section  306  at the opening  305 , to support the cutting insert during machining. Since the cutting edge section  315  of the cutting insert  311  normally is not subjected to any upwardly directed force the cooperating position between the holder  311  and the cutting insert  311  as is shown in  FIGS. 33 and 34  will function excellently in normal cases.  
         [0067]     Generally, in the present invention the circular arc shape of both insert pockets and cutting inserts bring about considerable advantages at production of holders and cutting inserts. Thus, a holder and a cutting insert can be made with an improved exactness in the sense of tolerances. Also generally, the periphery of the insert pocket shall correspond to a circular arc defining a center angle that is greater than 180°. The cutting insert is locked with respect to the holder when it is brought to assume its operative position in the holder. The mounting of the cutting insert in the holder is extraordinarily simple. The cutting insert obtains an extraordinary rigid mounting in the holder. The user will obtain an indication when the cutting insert has obtained a correct, operative position in the holder.  
         [0068]     In the embodiments described above the center hole  13 ;  113 ;  213 ;  313  is provided with a key of the type Torx®. Within the limits of the present invention however one can consider other types of generally occurring keys.  
         [0069]     Generally, in the above-described embodiments the holding means and the anchor sections can be inverted, wherein for example in the case described in  FIGS. 1-9  this means that the holder is provided with grooves while the cutting insert is provided with ridges.  
         [0070]     When it comes to the embodiment described in  FIGS. 19-27  this can be modified so that the cutting insert only has one lip while still the holder is provided with two recesses.  
         [0071]     The cutting insert forming a part of the tool according to the present invention need not be provided with a centrally located key grip. A conceivable alternative is that the cutting insert is provided with two diametrically arranged holes, opposed with regard to the center, wherein pins of a key is brought to cooperate with these holes. This constructive design brings about that high torque more easily can be transferred to the cutting insert in order to bring the same to rotate in the holder.  
         [0072]     The above-described embodiments of the invention relate to tools for grooving or parting. However, the principle according to the present invention for securing cutting inserts in holders can also be used at for example disc milling cutters or other rotary tools (shoulder milling cutters). In that case the holder normally comprises several cutting insert pockets.  
         [0073]     The invention described herein is susceptible to variations, modifications and/or additions other than those specifically described and it is to be understood that the invention includes all such variations, modifications and/or additions which fall within the scope of the claims.  
         [0074]     The disclosures in Swedish patent application No. 0401072-4, from which this application claims priority are incorporated herein by reference.