Abstract:
A cutting tool has a tool body and a cutting insert releasably retained in a pocket of the tool body. The cutting insert has first and second rear insert abutment surfaces and a third forward insert abutment surface and the pocket has first and second rear pocket abutment surfaces and a third forward pocket abutment surface. The first and second abutment surfaces are separated from the third abutment surface by a bore. The third forward pocket abutment surface can be either a socket recessed in a pocket base surface or a protrusion protruding from the base surface; and the third forward insert abutment surface can be correspondingly either a protrusion protruding from an inner surface of the insert or a socket recessed in the inner surface.

Description:
FIELD OF THE INVENTION 
       [0001]    The invention relates to cutting tools having a tool body with a replaceable cutting insert mounted therein. 
       BACKGROUND OF THE INVENTION 
       [0002]    Cutting tools used to shape a surface of a work piece in milling, turning or grooving operations may comprise a replaceable cutting insert that is mounted at an end of a relatively long, rod-like tool body or insert holder. The tool body has a cutting portion having an insert pocket for mounting the cutting insert therein and a shank at an end opposite to the cutting portion for securing the cutting tool in a tool holder of a machine tool. 
         [0003]    In a face-shaping or face-grooving operations, a surface at an end of the work piece that is usually substantially perpendicular to the axis about which the work piece rotates is, respectively, shaped and/or formed with a groove. The surface being shaped or grooved may be an internal surface, relatively deep inside the work piece and a groove being formed in a surface may be a relatively deep groove. For such operations, the cutting tool and insert must be appropriately shaped so that the insert can be inserted into the work piece to a sufficient depth to reach the surface being shaped or the groove being formed. Whereas the cutting tool and insert must have substantial reach, it is generally advantageous that they be sufficiently robust so that in use they are not subject to excessive vibration that prevents them from shaping surfaces of acceptable quality. 
         [0004]    However, providing a cutting tool with relatively large reach needed for shaping or grooving an internal surface may affect the robustness of the tool. The cutting tool and/or insert must often be shaped relatively long but having a relatively small cross section. In addition, surfaces of the cutting tool that are close to a curved surface being worked must generally be curved so that they do not contact and interfere with the surface. As a result, it may be difficult for the cutting tool to provide robust mechanical support for the cutting insert near the cutting tool&#39;s cutting edge. 
         [0005]    To meet design constraints of cutting tools used for face-shaping or face-grooving, the cutting insert retained in these tools may be mounted therein using an adapter. The adapter may be shaped to be mounted on an end of the tool body and may be configured to receive the cutting insert in a suitable insert pocket formed in the adapter. The adapter may be configured with various component support structures for stabilizing the cutting tool and reducing its tendency to vibrate during use and may comprise means for clamping the cutting insert in the pocket. The adaptor may also include means for adjusting the position of the cutting insert in the pocket. Typically, various configurations of bolts are used to secure the components of the adapter to the tool body and to provide the clamping and adjustment functions. 
         [0006]    U.S. Pat. No. 5,159,863 describes “an adjustable face-grooving tool holder for holding a cutting insert for cutting circular face grooves having widely differing diameters”. The holding tool comprises a “blade unit” to which a cutting insert is mounted and a “clamping arm” that is mounted on the blade unit using a screw that is tightened to clamp the cutting insert to the blade unit. The blade unit is mounted to the tool body using another screw. 
         [0007]    U.S. Pat. No. 5,709,508 describes a cutting tool assembly having an adaptor that is mounted to a tool block using a pair of bolts. 
         [0008]    U.S. Pat. No. 6,244,789 describes a cutting tool for cutting the walls of small deep holes. The tool comprises a cutting insert secured to a holder, or tool body. The cutting insert has a “stick-shaped” cutting portion that extends away from a planar plate-like base. The cutting portion has a cutting edge at a far end from the base. Near the center of the base is a bolt through hole which is aligned with a tapped hole in the holder. The cutting insert is secured to the holder by bolting the base into an insert pocket in the holder using a fixing bolt which is inserted through the bolt through hole and screwed into the tapped hole. The pocket has a seating surface on which a planar surface of the plate-like base rests and three projections that extend from peripheral surfaces of the pocket to contact a peripheral side surface of the base along three regions of the base peripheral surface. The cutting insert is clamped at four points. In addition to the three-point contact by the three projections, the insert is also clamped by a set bolt which is fitted through a tapped hole to make contact with the base peripheral side surface. When the set bolt in the tool body is screwed down to contact a fourth region of the base peripheral side surface, the insert “is locked at four points by the three projections . . . and the set bolt”. 
       SUMMARY OF THE INVENTION 
       [0009]    An aspect of an embodiment of the invention, relates to providing a tool body and insert such that when the insert is mounted to the tool body, forces are generated between surfaces of the tool body and the insert that align the insert with the tool body. 
         [0010]    According to an aspect of some embodiments of the invention, the forces generate a torque that presses an abutment surface of the insert against an abutment surface of the tool body thereby substantially fixing the orientation of the insert and its cutting edge relative to the tool body. 
         [0011]    An aspect of an embodiment of the invention relates to providing a tool body and groove-cutting insert for which the insert is mounted directly to the tool body. In an embodiment of the invention, the tool body has a pocket comprising a base surface and a back wall surface formed at a rear end of the pocket. The cutting insert comprises a mounting portion from which a cutting portion having a cutting edge extends. The mounting portion of the cutting insert has an inner surface that corresponds to the base surface of the pocket and a peripheral surface of the mounting portion corresponds to the pocket&#39;s back wall surface. The pocket formed in the tool body is formed having a forward male or female part having a pocket abutment surface and the mounting portion of the insert is formed having a matching forward female or male part respectively that has an insert abutment surface. 
         [0012]    The cutting insert is mounted to the tool body by placing the mounting portion of the insert in the tool body pocket with the male part inserted into the female part and with the inner and peripheral surfaces of the insert mounting portion adjacent to or substantially in contact with, respectively, the base and back wall surfaces of the pocket. The inner surface of the mounting portion of the insert is then forced against the base surface of the pocket optionally using a single threaded bolt to clamp the inner and base surfaces together. In accordance with an embodiment of the invention, the back wall surface of the pocket and the corresponding peripheral surface of the mounting portion of the insert are formed such that when the insert is mounted in the pocket, two abutment surfaces of the back wall surface are brought into forcible contact with two abutment surfaces of the peripheral surface. The abutment surfaces are oriented so that forces between the abutment surfaces generate a torque that causes the cutting insert to be securely retained in the pocket. The single clamping bolt thus securely mounts the cutting insert to, and aligns the insert with, the tool body. 
         [0013]    In a particular application of the invention, the cutting insert is a face-grooving cutting insert configured to cut a circular groove in a face surface of a work piece. The cutting edge of the insert&#39;s cutting portion is substantially perpendicular to a radius of curvature of the groove and is located at a region of the cutting portion farthest from the mounting portion of the insert. The cutting portion is defined at least in part by inner and outer cylindrical surfaces that are closer respectively to walls of the groove having smaller and larger radii of curvature. 
         [0014]    In accordance with the present invention there is provided a cutting tool comprising: a cutting insert comprising a cutting portion and a mounting portion, the mounting portion comprising: 
         [0015]    inner and outer surfaces and a peripheral surface extending therebetween; 
         [0016]    a through bore passing through the inner and outer surfaces; 
         [0017]    first and second insert abutment surfaces located on the peripheral surface, the first and second insert abutment surfaces being situated at a greater distance from the cutting portion than the throughbore; and 
         [0018]    a third insert abutment surface located adjacent the inner surface, spaced apart from the peripheral surface and situated closer to the cutting portion than the throughbore; 
         [0019]    and a tool body having a pocket comprising: 
         [0020]    a base surface; 
         [0021]    a back wall surface oriented transversely to the base surface and forming a partial boundary of the base surface at a rear end thereof; 
         [0022]    first and second pocket abutment surfaces situated on the back wall surface; 
         [0023]    a third pocket abutment surface oriented transversely to the base surface and spaced apart from the back wall surface; and 
         [0024]    a threaded bore in the base surface situated closer to a front surface of the tool body than the first and second pocket abutment surfaces and further from the front surface than the third pocket abutment surface; 
         [0025]    wherein the cutting insert is releasably retained in the pocket by a clamping bolt located in the through bore and threadingly received in the threaded bore and the first second and third insert abutment surfaces abut the first, second and third pocket abutment surfaces, respectively. 
         [0026]    In accordance with one embodiment, the third insert abutment surface is situated in a socket recessed in the inner surface of the mounting portion of the cutting insert and the third pocket abutment surface is located on a protuberance protruding from the pocket base surface. 
         [0027]    In accordance with another embodiment, the third insert abutment surface is situated on a protuberance protruding from the inner surface of the mounting portion of the cutting insert and the third pocket abutment surface is situated in a socket recessed in the pocket base surface. 
     
    
     
       BRIEF DESCRIPTION OF FIGURES 
         [0028]    The invention will be more clearly understood by reference to the following description of exemplary embodiments thereof read in conjunction with figures attached hereto. In the figures, identical structures, elements or parts that appear in more than one figure are generally labeled with a same numeral in all the figures in which they appear. Dimensions of components and features shown in the figures are chosen for convenience and clarity of presentation and are not necessarily shown to scale. The figures are listed below. 
           [0029]      FIG. 1A  schematically shows an exploded perspective of a cutting tool, in accordance with an embodiment of the invention; 
           [0030]      FIG. 1B  schematically shows an exploded perspective view of the cutting tool shown in  FIG. 1A  from a substantially opposite direction; 
           [0031]      FIG. 1C  schematically shows a perspective view of the cutting insert shown in  FIGS. 1A and 1B , in accordance with an embodiment of the invention; 
           [0032]      FIG. 2A  schematically shows a perspective view of the assembled cutting tool shown in  FIGS. 1A and 1B ; 
           [0033]      FIG. 2B  schematically shows a side view of the assembled cutting tool shown in  2 A; 
           [0034]      FIG. 2C  schematically shows an end view of the assembled cutting tool shown in  FIG. 2A ; 
           [0035]      FIG. 2D  shows a schematic cross section view taken in a plane perpendicular to the cutting tool&#39;s longitudinal axis A indicated by a line IID-IID in  FIG. 2A ; 
           [0036]      FIG. 3A  schematically shows an exploded perspective of a cutting tool, in accordance with another embodiment of the invention; 
           [0037]      FIG. 3B  schematically shows an exploded perspective view of the cutting tool shown in  FIG. 3A  from a substantially opposite direction; 
           [0038]      FIG. 3C  schematically shows a perspective view of the cutting insert retained in the cutting tool shown in  FIGS. 3A and 3B , in accordance with an embodiment of the invention; 
           [0039]      FIG. 3D  schematically shows a perspective assembled view of the cutting tool shown in  FIGS. 3A and 3B ; 
           [0040]      FIG. 4A  schematically shows an exploded view of a cutting insert comprising a blade configured to receive a replaceable cutting tip, in accordance with an embodiment of the invention; and 
           [0041]      FIG. 4B  schematically shows an assembled view of the cutting insert shown in  FIG. 4A . 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0042]      FIGS. 1A to 2C  schematically show perspective exploded views of a cutting tool  20  comprising a tool body  30  and a cutting insert  50 , in accordance with an embodiment of the invention. The tool body  30  may be made of a first hard material and the cutting insert  50  of a second hard material that is harder than the first hard material. For example, the tool body  30  may be made of steel and the cutting insert  50  may be made of a hard metal such as, for example, a cemented carbide. The tool body  30  may have a circularly cylindrical cross section.  FIGS. 1A and 1B  respectively show cutting tool  20  from a side of tool body  30  on which cutting insert  50  is mounted and from a side of the tool body opposite to that on which the cutting insert is mounted. By way of example, cutting insert  50  may be a face-grooving insert. The cutting tool  20  has a longitudinal axis A defining a front to rear direction of the cutting tool  20 . The longitudinal axis A may be an axis of rotation of the cutting tool if it is used in rotating cutting operations. 
         [0043]    Tool body  30  has a mounting shank  32  for mounting in a tool holder of a machine tool and a pocket  34  for receiving cutting insert  50 . Pocket  34  is formed having an optionally substantially planar base surface  35  and a back wall surface  36  formed at rear end  21  of pocket  34 . Back wall surface  36  is oriented transversely to base surface  35  and optionally comprises a bevel surface  135  adjacent base surface  35 . Therefore, the back wall surface  36  forms a partial boundary of the base surface  35  at the rear end  21  of pocket  34 . Two rear pocket abutment surfaces  138  and  137  are located on the back wall surface  36 . The figures are only schematic and mounting shank  32  may be longer than shown. 
         [0044]    A female part, a socket  37 , having a socket wall surface  38  is optionally formed at a front end  22  of pocket  34  adjacent a front surface  23  of tool body  30  and a threaded bore  39  for receiving a clamping bolt  80  is optionally formed substantially perpendicular to base surface  35  between socket  37  and back wall surface  36 . Threaded bore  39  has a bore axis B. Socket wall surface  38  is optionally bounded along its length by bevel surfaces  139 . A section of the socket wall surface  38  comprises a forward pocket abutment surface  40 . Optionally, tool body  30  is formed having a channel  42  for leading coolant to insert  50  when cutting tool  20  is used to cut a groove in a work piece. Optionally, a shunt hole  43  diverts a portion of the coolant flowing in channel  42  to base surface  35 . Socket  37  opens out to base surface  35  of pocket  34  and may also open out to front surface  23  of tool body  30 . The forward pocket abutment surface  40  is oriented transversely to the base surface  35 . 
         [0045]    Cutting insert  50  is formed having a mounting portion  52  from which a cutting portion  54  comprising a cutting edge  55  extends. As seen in  FIGS. 1A-1C , the cutting insert  50  has unitary integral one-piece construction with the cutting portion  54  constituting a forward portion of the cutting insert  50  and the mounting portion  52  constituting a rearward portion of the cutting insert  50 . Cutting portion  54  optionally has an outside curved surface  153  and an inside curved surface  156 . Inside side surface  156  determines a largest radius groove that the cutting insert  50  can be used to cut and outside curved surface  153  defines a smallest radius groove that the cutting insert  50  can be used to cut. Mounting portion  52  has an inner surface  56  ( FIG. 1B ) and an opposing outer surface  57  ( FIG. 1A ). The inner surface  56  mates with base surface  35  of pocket  34  and is optionally substantially planar. Mounting portion  52  has a peripheral surface  58  that is adjacent to and partially abuts to back wall surface  36  of tool body  30  when the cutting insert is secured to the tool body  30 . First and second rear insert abutment surfaces  157  and  158 , respectively, are located on peripheral surface  58  and correspond to first and second rear pocket abutment surfaces  137  and  138 , respectively. Peripheral surface  58  extends between the inner surface  56  and the outer surface  57 . The peripheral surface  58  is transverse to the inner and outer surfaces  56  and  57 . A reference plane P of cutting tool  20  is defined by longitudinal axis A and bore axis B. Reference plane P may be a median plane of mounting portion  52  of the cutting insert  50 . First and second rear insert abutment surfaces  157  and  158 , respectively, are located on opposite sides of peripheral surface  58  and on opposite sides of reference plane P. First and second rear pocket abutment surfaces  137  and  138  are located on opposite sides of the back wall surface  36  and on opposite sides of reference plane P. 
         [0046]    Optionally, a male part, a protuberance  60 , which substantially matches socket  37  in tool body  30 , protrudes from inner surface  56  of mounting portion  52  of insert  50  near to where cutting portion  54  joins mounting portion  52  of the insert. Protuberance  60  is optionally formed having an insert abutment surface  160  that abuts forward pocket abutment surface  40  of socket  37  when insert  50  is mounted on tool body  30  as described below. Protuberance  60  is optionally formed having a bevel surface  161 . A through bore  62  for receiving bolt  80  is formed transverse to inner surface  56 . The through bore  62  may be formed perpendicular to inner surface  56 . The protuberance  60 , and consequently the insert abutment surface  160 , is located closer to the cutting portion  52  than the through bore  62 . The insert abutment surfaces  157 ,  158  and  160  form first, second and third insert abutment surfaces, respectively, of the cutting insert  50  in accordance with a first embodiment and the pocket abutment surfaces  137 ,  138  and  40  form first, second and third pocket abutment surfaces, respectively, of pocket  34  of the tool body  30  in accordance with the first embodiment. 
         [0047]    Cutting tool  20  is assembled by aligning mounting portion  52  of cutting insert  50  with pocket  34 , inserting the mounting portion into the pocket  34 , placing the clamping bolt  80  in the through bore  62  and screwing clamping bolt  80  into threaded bore  39  so that the clamping bolt secures the mounting portion into the pocket  34 .  FIGS. 2A and 2B  schematically show perspective and side views of cutting tool  20  assembled. First and second rear insert abutment surfaces  157 ,  158  are oriented at an acute angle to each other and converge rearwardly, that is, in a direction away from the cutting edge  55  (see,  FIG. 2B ). Similarly, first and second rear pocket abutment surfaces  137 ,  138  are oriented at an acute angle to each other and converge rearwardly, that is, a direction away from the front surface  23  of the tool body  30 . 
         [0048]    In accordance with an embodiment of the invention, peripheral surface  58  of cutting insert  50  and back wall  36  of pocket  34  are configured so that when cutting insert  50  is mounted in pocket  34 , the peripheral surface  58  contacts tool body  30  substantially only at rear pocket abutment surfaces  137  and  138  of pocket  34 . Regions of the cutting insert peripheral surface  58  that contact rear pocket abutment surfaces  137  and  138  of pocket  34  are respectively rear insert abutment surfaces  157  and  158  of the cutting insert  50 . Contact between first rear abutment surfaces  137  and  157  generates a force on cutting insert  50  schematically represented by block arrow  91 . Contact between second rear abutment surfaces  138  and  158  generates a force on the cutting insert schematically represented by block arrow  92 . Forces  91  and  92  generate a torque represented by circular block arrow  93 . In an embodiment of the invention, torque  93  operates to rotate cutting insert  50  and forcibly press insert abutment surface  160  of the cutting insert on forward pocket abutment surface  40  of the tool body as shown in  FIG. 2C  which schematically shows a front end view of cutting tool  20  from a direction indicated by a block arrow  95  in  FIG. 2A  in which insert abutment surface  160  of protuberance  60  abuts forward pocket abutment surface  40  of socket  37 . As a result, when clamping bolt  80  clamps cutting insert  50  in pocket  34  the cutting insert  50  is stably mounted in the pocket  34  and accurately positioned relative to tool body  30  by base surface  35  of the pocket  34  and by contact with three surfaces, pocket abutment surfaces  137 ,  138  and  40 . 
         [0049]    In some embodiments of the invention, rear abutment surfaces  137 ,  138 ,  157  and  158  are configured so that as clamping bolt  80  is screwed into threaded bore  39 , forces  91  and  92  between the abutment surfaces of the cutting insert and the tool body increase. For example, the abutment surfaces might be angled relative to an axis (for example, axis B) about which clamping bolt  80  is rotated in order to screw the clamping bolt into threaded bore  39  to provide forces that increase as the bolt is screwed into hole  39  and cutting insert is mounted more tightly to tool body  50 . 
         [0050]      FIG. 2D  shows a schematic cross section view of cutting tool  20  in accordance with some embodiments. As can be seen, rear abutment surfaces  137 ,  138 ,  157  and  158  are radially outwardly angled so that forces  91  and  92  increase as cutting insert is clamped more tightly into pocket  37 . For convenience of presentation, cutting insert  50  is shown not completely inserted into the pocket. As can be seen in  FIG. 2D , in the plane of the cross section, each of the rear pocket abutment surfaces  137 ,  138  forms an obtuse external angle with base surface  35 . Similarly, each rear pocket abutment surface  157 ,  158  forms a corresponding obtuse internal angle with inner surface  56 . 
         [0051]      FIGS. 3A to 3D  schematically show perspective, exploded views of a face grooving cutting tool  220 , in accordance with an embodiment of the invention, that is a variation of the cutting tool  20  shown in  FIGS. 1A to 2C . 
         [0052]    Cutting tool  220  optionally comprises a tool body  230  and a cutting insert  250  that may be secured to the tool body  230  by clamping bolt  80 . The tool body  230  may be made of a first hard material and the cutting insert  250  of a second hard material that is harder than the first hard material. For example, the tool body  230  may be made of steel and the cutting insert  250  may be made of a hard metal such as, for example, a cemented carbide. 
         [0053]    Whereas tool body  30  in cutting tool  20  comprises a female part, socket  37 , that corresponds to a male part, protuberance  60 , in cutting insert  50 , in cutting tool  220  tool body  230  is formed having a male protuberance  235  adjacent a front surface  229  of the tool body  230  and cutting insert  250  is formed having a matching female socket  260 . Cutting insert  250  may have a mounting portion  252  similar to mounting portion  52  of cutting insert  50  of cutting tool  20  and mounting portion  252  may have a peripheral surface  256  similar to peripheral surface  58  of mounting portion  52 . A cutting portion  254 , having a cutting edge  255 , may extend from the mounting portion  252 . The cutting insert  250  has unitary integral one-piece construction with the cutting portion  254  constituting a forward portion of the cutting insert  250  and the mounting portion  252  constituting a rearward portion of the cutting insert  250 . The peripheral surface  256  may extend between an inner surface  286  and an outer surface  287  of the mounting portion  252 . The female socket  260  may be a recess in the inner surface  286 . The female socket  260  may be adjacent the cutting portion  254 . The female socket  260  may open out to the cutting portion  254 . Tool body  230  of cutting tool  220  may have a pocket  234  having a back wall surface  236  similar to back wall surface  36  of tool body  30  of cutting tool  20 . The back wall surface  236  is formed at a rear end  221  of pocket  234 . For cutting tool  220 , cutting insert  250  has rear insert abutment surfaces  257  and  258  on its peripheral surface  256  and corresponding rear pocket abutment surfaces  237  and  238  on the back wall surface  236  of its pocket  234  that are similar to rear insert abutment surfaces  157  and  158  on cutting insert  50  and rear pocket abutment surfaces  137  and  138  on the back wall surface  36  of pocket  34  of tool body  30 , respectively, of cutting tool  20 . Tool body  230  has a forward pocket abutment surface  240  on protuberance  235 . A matching forward insert abutment surface  261  of cutting insert  250  is located in socket  260  of the insert. The insert abutment surfaces  257 ,  258  and  261  form first, second and third insert abutment surfaces, respectively, of the cutting insert  250  in accordance with a second embodiment and the pocket abutment surfaces  237 ,  238  and  240  form first, second and third pocket abutment surfaces, respectively, of pocket  234  of the tool body  230  in accordance with the second embodiment. For cutting tool  220 , as with cutting tool  20 , first and second rear insert abutment surfaces  257 ,  258  are oriented at an acute angle to each other and converge rearwardly, that is, in a direction away from the cutting edge  255 . Similarly, first and second rear pocket abutment surfaces  237 ,  238  are oriented at an acute angle to each other and converge rearwardly, that is, a direction away from the front surface  229  of the tool body  230 . 
         [0054]    When cutting insert  250  is mounted to tool body  230 , forces between first rear abutment surfaces  237  and  257  and between second rear abutment surfaces  238  and  258  generate a torque that rotates the cutting insert so that forward insert abutment surface  261  of socket  260  abuts forward pocket abutment surface  240  of protuberance  235 .  FIG. 3D  schematically shows a perspective end view of cutting tool  220  showing abutment surface  261  abutting forward pocket abutment surface  240 . 
         [0055]    As described above, cutting tool  220  is similar to cutting tool  20 . The main difference between the two cutting tools being that pocket  34  of cutting tool  20  has socket  37  at its front end, the socket  37  having forward pocket abutment surface  40 , whereas cutting tool  220  has protuberance  235  at its front end, the protuberance  235  having forward pocket abutment surface  240 . Forward pocket abutment surface  40  is adjacent base surface  35  of pocket  34  and forward pocket abutment surface  240  is adjacent base surface  275  of pocket  234 . The main difference between the two abutment surfaces being that forward pocket abutment surface  40  is recessed relative to base surface  35  whereas forward pocket abutment surface  240  protrudes relative to base surface  275 . Correspondingly, in the main difference between cutting insert  50  and cutting insert  250  is that cutting insert  50  has a protuberance  60  adjacent the cutting portion  54  whereas cutting insert  250  has a socket  260  adjacent the cutting portion  254 . 
         [0056]    In the present invention, the pocket abutment surfaces  137 ,  138  and  237 ,  238  in the back walls  36  and  236 , respectively, are situated axially rearward of the threaded bores  39  and  239 . This means that the back walls  36 ,  236  may be terminated axially rearward of the threaded bores  39  and  239 , respectively. Consequently, the base surfaces  35 ,  275  in the region of the threaded bores  39  and  239 , respectively, may extend outward to the peripheral surface of the mounting shanks, thereby leaving a greater area for the mounting portions  52 ,  252  of the cutting inserts  50 ,  250  in regions around the through bores  62 ,  262 , respectively. This results in stronger mounting portions  52 ,  252  whilst still enabling secure clamping of the cutting insert and relatively small diameter cutting tools. If the rear pocket abutment surfaces  137 ,  138  and  237 ,  238  were not situated axially rearward of the threaded bores  39  and  239  then the back walls  36 ,  236  could not be terminated axially rearward of the threaded bores  39  and  239  and in order to use the same size cutting inserts  50 ,  250 , the diameter cutting tools would have to be increased. 
         [0057]    Whereas in the above figures and description cutting inserts  50  and  250  are integrally formed having cutting edges  55  and  255 , respectively, in some embodiments of the invention the cutting inserts  50  and  250  may have cutting edges formed on a relatively easily replaceable cutting tip.  FIGS. 4A and 4B  schematically show an exploded and assembled view of a cutting insert  300  similar to cutting insert  50  but wherein the cutting portion  302  has at its forward end a tip pocket  303  configured to receive a replaceable cutting tip  304  having a cutting edge  305 , in accordance with an embodiment of the invention. The cutting insert  300  may be made of a first material such as steel and the cutting tip  304  may be made of a harder material, such as cemented carbide. Tip pocket  303  optionally comprises an alignment ridge  308  and a mounting seat  306  having a threaded bore  307  formed therein. Replaceable cutting tip  304  is formed having an alignment groove  310  that matches ridge  308  and a mounting extension  312  that matches mounting seat  306  and is formed having a through hole  314 . 
         [0058]    Replaceable cutting tip  304  is mounted to tip pocket  303  by positioning the tip with ridge  308  inserted into groove  310  and optionally clamping mounting extension  312  to mounting seat  306  by passing a suitable bolt through hole  314  and screwing the bolt into threaded bore  307 . 
         [0059]    It is noted that whereas the examples of embodiments of the invention shown in the figures and as described above relate to a cutting tool for cutting grooves, practice of the invention is not limited to groove-cutting tools. For example, cutting tools and tool bodies similar to that shown above may be configured for face-shaping or parting. In addition, whereas tool body  30  is shown as a single integral component a tool body similar to tool body  30  may comprise a plurality of components. For example, a tool body in accordance with an embodiment of the invention may comprise a first component having a pocket such as pocket  34  and be configured to be connected to a shank for mounting to a machine tool. The first component may be mounted to different shanks for mounting to different machine tools. 
         [0060]    In the description and claims of the present application, each of the verbs, “comprise” “include” and “have”, and conjugates thereof, are used to indicate that the object or objects of the verb are not necessarily a complete listing of members, components, elements or parts of the subject or subjects of the verb. 
         [0061]    The present invention has been described using detailed descriptions of embodiments thereof that are provided by way of example and are not intended to limit the scope of the invention. The described embodiments comprise different features, not all of which are required in all embodiments of the invention. Some embodiments of the invention utilize only some of the features or possible combinations of the features. Variations of embodiments of the invention that are described and embodiments of the invention comprising different combinations of features noted in the described embodiments will occur to persons of the art.