Abstract:
A cutting tool having a plurality of cutting inserts mounted about the periphery of a cutter body. The insert has radially extending projections each including a front cutting edge and rear cutting edge. Front and rear cutting edges from different adjacent projections together define an individual cutting side of the insert. The cutter body has a pocket for each insert. The insert engages the pocket side wall at multiple locations using only the front teeth from two or more projections. This permits a single cutter body and pocket design to be used with different inserts and allows the inserts&#39; radial rake angle to be varied from one insert to the next by varying the front tooth height.

Description:
CROSS-REFERENCE TO RELATED APPLICATION  
       [0001]    This application claims the priority of U.S. Application No. 60/474,112, filed May 29, 2003, the complete disclosure of which is hereby incorporated by reference. 
     
    
     
       TECHNICAL FIELD  
         [0002]    This invention relates generally to cutting tools, and more particularly to rotary cutting tools having cutting inserts mounted about the periphery of a cutter body.  
         BACKGROUND OF THE INVENTION  
         [0003]    Typically, machines for milling, turning, boring, and the like, have a rotating spindle that drives a cutter body for rotation. The cutter body includes one or more cutting inserts for machining material that are commonly constructed from carbide and may be coated depending on the material being machined. Typically, the cutting inserts are releasably attached to the cutter body about its periphery and can be removed from the cutter body when they become worn. Generally, when the inserts become worn, they are removed from the cutter body and discarded or reground and new inserts are installed on the cutter body. To maximize the useful life of an insert, it is known to provide a multi-sided insert having at least one cutting edge on two or more of the sides, as disclosed in U.S. Pat. No. 5,209,611. When the cutting edge on one side of the insert becomes worn, the insert can be repositioned to present an unused cutting edge in a cutting position.  
         SUMMARY OF THE INVENTION  
         [0004]    In accordance with one aspect of the invention there is provided a cutting tool insert which comprises an insert body having upper and lower surfaces with an opening passing through the body in an axial direction from the upper surface to the lower surface. The insert body includes a plurality of radially outwardly extending projections located at a periphery of the insert body between the upper and lower surfaces. Each of the projections has a pair of adjacent cutting edges, each of which is spaced circumferentially from the other by a recess extending inwardly toward the opening. The cutting edges and recesses each extend at least generally in the axial direction. Preferably, each of the pair of cutting edges includes a front cutting edge and a rear cutting edge, with the front and rear cutting edges being arranged in alternating sequence about the circumference of the insert such that one of the front cutting edges from one projection and one of the rear cutting edges on an adjacent projection together comprise a cutting side of the insert.  
           [0005]    In accordance with another aspect of the invention, there is provided a cutting tool comprising (i) a cutter body having a plurality of pockets located about its periphery, (ii) a plurality of cutting inserts, and (iii) a plurality of fasteners attaching each insert within one of the pockets. Each insert has a number of cutting sides, each of which has a front cutting tooth and a rear cutting tooth. The pockets in the cutter body are each defined at least in part by a recessed surface and side wall which is complementary in shape to the inserts. Each pocket can receive one of the inserts such that two of the front teeth of the insert abut the side wall of the pocket with at least one interposed rear tooth that is spaced from the side wall. This arrangement permits a single pocket design to accommodate different inserts with different front tooth heights so that the radial rake angle of the teeth can be varied from one application to the next using the same cutter body. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0006]    A preferred exemplary embodiment of the invention will hereinafter be described in conjunction with the appended drawings, wherein like designations denote like elements, and wherein:  
         [0007]    [0007]FIG. 1 is a front view of a cutting tool having a cutter body and cutting inserts attached thereto and;  
         [0008]    [0008]FIG. 2 is a side view of the cutting tool of FIG. 1 showing some of the inserts and their corresponding pockets within the cutter body;  
         [0009]    [0009]FIG. 3 is a rear view of the cutting tool of FIG. 1;  
         [0010]    [0010]FIG. 4 is a perspective view of one of the cutting inserts of FIG.1;  
         [0011]    [0011]FIG. 5 is a plan view of the cutting insert of FIG. 4;  
         [0012]    [0012]FIG. 6 is a side view of the cutting insert of FIG. 4;  
         [0013]    [0013]FIG. 7 is an enlarged fragmentary view of one of the inserts shown properly oriented and assembled in a pocket of the cutter body of FIG. 1; and  
         [0014]    [0014]FIG. 8 is a view similar to FIG. 7 with an insert shown improperly oriented in a pocket of the cutter body of FIG. 1. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0015]    Referring in more detail to the drawings, FIGS. 1 and 2 illustrate a cutting tool  10  that includes a cutter body  16  and a plurality of cutting inserts  12  mounted within complementary pockets  14  provided adjacent to a periphery  22  of the cutter body  16 . As will be described in greater detail below, the cutting inserts  12  and the pockets  14  are shaped such that the inserts  12  may only be assembled within the pockets  14  while in their proper orientation. As will be described further below in connection with FIG. 8, if the inserts  12  are inserted within the pockets  14  in an improper orientation, such as inverted or upside down, the inserts  12  cannot be fully received or secured within the pockets  14 . This ensures that cutting features on each insert are properly oriented relative to a workpiece to be machined.  
         [0016]    As shown in FIG. 2, the cutter body  16  has first and second sides or faces  19 ,  20  extending to the periphery  22  which, in the embodiment shown, has a necked down or reduced diameter portion  24 . As best shown in FIG. 3, the back side  19  is constructed for attachment to a spindle of a machine (not shown). This side  19  preferably has at least one, and shown here as a pair of keyways  26  formed in its surface. The keyways  26  receive keys extending from the spindle to connect the cutter body  16  with the spindle. For mounting purposes, the cutter body  16  has a plurality of slotted openings  28  passing therethrough. The slotted openings  28  have enlarged portions  29  enabling the cutter body to fit over the heads of fasteners attached to the spindle (not shown), and narrow portions  30  so that the cutter body  16  can be rotated to dispose the shank of the fasteners in the narrow portions  30  of each opening  28  with the cutter body  16  trapped between the enlarged fastener heads and the spindle. It should be recognized that the narrow portions  30  are preferably recessed within the front side  20  so that the heads of the fasteners securing the cutter body  16  to the spindle are not unduly projected from and may be flush with the face  20 . As is known, the cutter body  16  has at least one and shown here as a pair of threaded openings  32  to facilitate removal of the cutter body  16  from the spindle when desired.  
         [0017]    The pockets  14  are formed in one face  20  adjacent to the necked down portion  24  of the periphery  22  (FIGS. 1 and 2). As best shown in FIGS. 7 and 8, the pockets  14  are generally complementarily shaped to the cutting tool inserts  12 , but slightly larger than the inserts  12  so that the inserts  12  may be received in the pockets  14 . Each pocket  14  has a recessed surface  34  and a threaded blind bore  36 . Preferably, the bore  36  is located within the pocket  14  so that when the cutting tool insert  12  is fully received within the pocket  14  it may be secured in the pocket  14  by way of a fastener  38 . When secured in this manner, the insert  12  is assured of being in its proper orientation and not improperly installed within the pocket  14 . In addition, a wall  40  defining at least in part the pocket  14  includes a plurality of surfaces  42  disposed at various orientations and distances relative to the bore  36  to closely receive adjacent portions of a cutting tool insert  12  when the insert  12  is properly orientated in the pocket.  
         [0018]    As shown in FIG. 4, the cutting tool insert  12  has an insert body  44  with upper and lower surfaces  45 ,  46  and a central opening or through hole  48  extending generally along an axis  49  of the body  44  from one face  45  to the other face  46 . As best shown in FIG. 5, the insert body  44  has at least a pair and shown here as five radially outwardly extending projections  50  providing the cutting insert  12  with a generally pentagonal shape as viewed along the axis  49 . Each projection  50  has a pair of respective separate rear and front cutting edges  51 ,  52  located at the leading edges of generally flat cutting teeth  53 . Thus, each projection  50  includes a rear tooth  53  having a rear cutting edge  51 , and a front tooth  53  having a front cutting edge  52 . Adjacent teeth  53  on the same projection  50  are inclined relative to each other so that they are not parallel or mirror images of each other. A recess  54  preferably extends radially inwardly toward the opening  48  between the cutting edges  51 ,  52  of the same projection  50 . The rear and front cutting edges  51 ,  52  extend generally axially and preferably lie within a plane that is parallel to the axis  49 . The front cutting edges  52  and rear cutting edges  51  of the teeth  53  have a predefined radial rake angle (A and B, respectively) shown in FIG. 7. The rake angles A, B are defined by an included angle between a radius (r) of the cutter body  16  and respective projections of surfaces  55 ,  57  that extend radially inwardly from the outer surface of each front and rear tooth  53 . Desirably, the front cutting edges  52  have a first rake angle (A) and the rear cutting edges  51  have a second rake angle (B) with the first rake angle A being more negative than the second rake angle B. As one example, the radial rake angle A can be −8.8° and radial rake angle B can be −4.9°.  
         [0019]    The front cutting edges  52  extend radially outwardly from the center hole  48  of the insert farther than the rear cutting edges  51 . This can be seen in FIG. 5 by the dashed circle that extends through the rear cutting edges  51  and which is located radially inwardly from the front cutting edges  52 . Each projection  50  and its associated pair of cutting edges  51 ,  52  is circumferentially spaced from a pair of adjacent projections  50  and their associated cutting edges  51 ,  52  by recesses  56  extending radially inwardly toward the through hole  48 . The recesses  56  separating each projection extend radially inwardly farther than the recesses  54  that separate the front and rear cutting edges of each projection  50 . Each cutting edge  51 ,  52  extends generally between the faces  45 ,  46  of the insert  12  and preferably terminates at chamfers  58 ,  59 , wherein the chamfers  58 ,  59  form a transition between the cutting edges  51 ,  52  and the faces  45 ,  46  (FIG. 6). Preferably, the through hole  48  has a countersunk chamfer  60  in one face  45  for receiving a mating head  62  of the fastener  38  so that the head  62  is generally flush with the face  45  of the insert body  44  upon assembly.  
         [0020]    So constructed and arranged, the cutting insert has five potentially active cutting sides  63  that may be separately presented to machine a workpiece. Each active cutting side  63  includes two cutting teeth  53 , and more particularly, an active cutting side  63  includes one rear cutting edge  51  from one projection  50  on one side of a recess  56  and another immediately adjacent front cutting edge  52  from another projection  50  on the other side of the same recess  56 . In this embodiment, the cutting edges  51  and  52  on the same projection  50  are not part of the same active cutting side  63 , and thus, do not coact to cut or machine a workpiece at the same time.  
         [0021]    Even though the front cutting edges  52  extend radially beyond the other rear cutting edges  51  relative to the through hole  48  of the respective insert  12 , the pockets  14  are oriented so that when a cutting tool insert  12  is properly positioned within a pocket  14 , the cutting edges  51  and  52  of the exposed active cutting side  63  extend generally radially outwardly by the same distance relative to the reduced diameter portion  24  of the cutter body  16 . As such, the active or working cutting side  63  presents one front cutting edge  52  and one rear cutting edge  51  on immediately adjacent projections  50  to perform the cutting action generally simultaneously, while the remaining cutting edges  51 ,  52  remain idle and in a non-cutting position. Once the active cutting edges  51 ,  52  become worn, the cutting edges  51 ,  52  in any of the non-cutting positions can be readily advance or rotated, as needed, to the active cutting position by removing the insert from its pocket, rotating it, and re-installing it into the pocket.  
         [0022]    As shown in FIG. 7, when the cutting tool insert  12  is properly assembled within the generally complementary shaped pocket  14  of the cutter body  16 , at least one and preferably a pair of the front teeth  53  abut a pair of complementary surfaces  42  within the pocket  14 . Desirably, the pocket  14  is constructed relative to the insert  12  such that the two front teeth  53  immediately clockwise from the active cutting side will rest against two of the surfaces when the insert is fastened in place within the pocket. Accordingly, two of the pocket surfaces  42  most directly opposing the cutting forces imparted on the insert  12  are positioned to counteract the cutting forces, thereby positively maintaining the insert  12  in its mounted position against rotation or movement while in use. Accordingly, in addition to the fastener  38  securing the cutting tool insert  12  against movement within the pocket  14 , the insert  12  is further inhibited from rotational or translational movement within the pocket  14  by the engagement of the front teeth against the surfaces  42  of the wall  40 . It should be recognized that, although a pair of surfaces  42  are shown here engaging a pair of front teeth, more or fewer surfaces  42  could abut the front teeth.  
         [0023]    While the insert  12  is arranged within the pocket  14  preferably by having a pair of front teeth in abutment with the surfaces  42  of the wall  40 , the rear teeth containing rear cutting edge  51  remain spaced from the wall  40 . This spacing of certain front and rear teeth  53  is represented generally at  61  for certain locations around in the insert (FIG. 7). As will be appreciated by those skilled in the art, spacing of the rear teeth from the pocket wall  40  allows the rake angles A, B of the insert  12  to be changed from one application to the next without having to modify the pockets  14  of the cutter body. More specifically, the rake angles A, B of the front and rear cutting edges  52 ,  51 , can be set by adjusting the radial projection of the front teeth for a particular application. For example, the height (amount of protrusion) of the front teeth can all be reduced by an equal amount, thereby allowing the cutting insert  12  to rotate proportionately in a clockwise direction within its pocket  14  relative to that shown in FIG. 7, thereby altering and tending to decrease (i.e., increase negatively) the rake angles A, B. The rear teeth could also be adjusted accordingly so that both sets of teeth are aligned as desired along the cutting path shown by the dashed line in FIG. 7. Accordingly, depending on the application, the inserts  12  in combination with the pockets  14  provide a user with an ability to attain a more aggressive cutting attack by maintaining smaller rake angles A, B, thus requiring less overall horsepower to drive the cutting insert  14 , or a less aggressive cutting attack by setting the rake angles A, B to a more negative value.  
         [0024]    In the illustrated embodiment, two point contact is provided between the insert  12  and pocket wall  40 , namely, the two front teeth located at the trailing side of the pocket  14 , with the insert including an interposed rear tooth that is spaced from the wall  40 . However, other arrangements and number of point contacts can be used while still permitting the amount of front tooth projection to affect the radial rake angles. Such variations and modifications with become apparent to those skilled in the art.  
         [0025]    As shown in FIG. 8, if an attempt is made to install an inverted or upside down cutting tool insert  12  in a pocket  14  (i.e. with face  45  adjacent to the recessed surface  34 ), the outer surfaces of teeth  53  or cutting edges  51 ,  52  on certain projections  50  engage the wall  40  and/or some of the surfaces  42  before the insert  12  is fully received in the pocket  14 . This occurs because the cutting edges  52  extend radially beyond and are inclined at different angles relative to the other cutting edges  51  whereby the circumferential positions of the cutting edges  52  change when the insert  12  is inverted. Because the insert  12  cannot be fully received in a pocket  14  when inverted, the hole  48  in the insert will not align with the bore  36  in the cutter body  16  so that the insert  12  cannot be secured in the pocket in this orientation. It should be recognized that though the cutting tool inserts  12  are shown here as having a generally pentagon shape, and thus having five projections  50  and five cutting sides, that any number of other geometries could be used, such as square, rectangular, triangular, hexagonal and the like. It should also be recognized that the pockets  14  within the cutter body  16  would take on a generally complementary geometry of the cutting tool inserts regardless of what their geometry might be.  
         [0026]    It will thus be apparent that there has been provided in accordance with the present invention a cutting tool and cutting insert therefor which achieves the aims and advantages specified herein. It will of course be understood that the foregoing description is of a preferred exemplary embodiment of the invention and that the invention is not limited to the specific embodiment shown. Various changes and modifications will become apparent to those skilled in the art and all such variations and modifications are intended to come within the scope of the appended claims.  
         [0027]    As used in this specification and appended claims, the terms “for example,” “for instance,” and “such as,” and the verbs “comprising,” “having,” “including,” and their other verb forms, when used in conjunction with a listing of one or more components or other items, are each to be construed as open-ended, meaning that the listing is not to be considered as excluding other, additional components or items. Other terms are to be construed using their broadest reasonable meaning unless they are used in a context that requires a different interpretation.