Abstract:
A tool holder that is adapted to break chips during a cutting operation is disclosed. The tool holder comprises a shank and a head. The shank is adapted to be received by a cutting machine. A head is provided with a pocket for receiving a cutting insert. The head has a flank surface. A chip breaker is provided on the flank surface adjacent the pocket. A clamp is provided for retaining the cutting insert in the pocket. A method for breaking chips comprises the steps of providing a chip breaker on the head of a tool holder adjacent a cutting insert and directing a chip into the chip breaker.

Description:
FIELD OF THE INVENTION 
     This invention generally relates to cutting tools and is specifically concerned with a tool holder that improves chip breaking during cutting operations. 
     BACKGROUND OF THE INVENTION 
     During metal cutting operations, continuous metal shavings are usually produced. These shavings are commonly referred to as chips. Chips can build up, cause deterioration in the finished surface of a work piece, and thus create a quality assurance problem. Build up chips can form a mass that may rotate with the work piece and thus pose problems relating to operational safety. Moreover, chips can cause unpredictable jams in a cutting process, which requires manual disposal of the chips. This ultimately interferes with the automated cutting operations. 
     To this end, it is strongly desirable to have the chips generated in discontinuous forms. Chip breakers have been devised for breaking chips into small pieces. One type of chip breaker includes a combination of grooves and obstacles formed on the rake face of the cutting insert. During cutting operations, the grooves and obstacles function to bend the chip after it has been produced. Often, the grooves and obstacles fail to break the chips. 
     There is a need for a tool holder that improves chip breaking. Ideally, the tool holder would control dispersion of the chips and thus, promote safety, quality assurance, and the automated cutting operations. 
     SUMMARY OF THE INVENTION 
     Generally speaking, the invention is directed towards a tool holder that is adapted to break chips during a cutting operation. The tool holder comprises a shank and a head. The shank is adapted to be received by a cutting machine. A head is provided with a pocket for receiving a cutting insert. The head has a flank surface. A chip breaker is provided on the flank surface adjacent the pocket. A clamp is provided for retaining the cutting insert in the pocket. 
     The invention is also directed to a method for breaking chips comprising the steps of providing a chip breaker on the head of a tool holder adjacent a cutting insert and directing a chip into the chip breaker. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of a cutting tool that includes a pattern of grooves according to the invention; 
     FIG. 2 is an enlarged-scale, elevational view of the cutting tool shown in FIG. 1; 
     FIGS. 3A through 3E are enlarged-scale, elevational views of cutting tools with alternative groove patterns; 
     FIGS. 4A through 4E are enlarged-scale, partial, cross-sectional views of cutting tools with alternative groove patterns; 
     FIG. 5 is an enlarged-scale, elevational view of another cutting tool with a raised surface pattern; 
     FIG. 6 is a partial, cross-sectional view of the cutting tool shown in FIG. 5; 
     FIG. 7 is an enlarged-scale, elevational view of yet another cutting tool with a roughened surface; 
     FIG. 8 is a partial, cross-sectional view of the cutting tool shown in FIG. 7; and 
     FIG. 9 is a partial, cross-sectional view of the cutting tool shown in operation. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     With reference now to FIGS. 1 and 2, wherein like numerals designate like components throughout all of the several figures, the cutting tool is comprised of a tool holder  10  having a top, generally indicated at  12 , and a front end, generally indicated at  14 . The tool holder  10  is comprised of a unitary body including a shank portion  16  and a head portion head  18  joined to the shank  16 . The shank  16  is adapted to be received by a tool magazine of a cutting machine, such as a lathe (not shown). The head  18  is adapted to receive a cutting insert  20 . 
     The head  18  could be any desired shape. However, the shape of the shank  16  is generally dictated by the machine magazine (not shown). The cutting insert  20  can also be any desired shaped. The invention is not limited to the generally triangular-shaped cutting insert  20  shown but instead can be square, rectangular, or some other polygonal shape. 
     As shown in the drawings, the head  18  is provided with a pocket, generally indicated at  22 , for receiving the cutting insert  20 . The pocket  22  is preferably defined by a trihedral recess having a planar lower or bottom surface  24  and intersecting faces or side walls  26   a ,  26   b  (shown in FIG.  9 ). 
     The cutting insert  20  may be formed of tungsten carbide or the like. The cutting insert  20  shown is a unitary body including an upper face or rake  28  (shown in FIG. 9) and a lower face  30  joined by flank surfaces or sides  32 . It is preferred that the cutting insert  20  be indexable. That is to say, each side  32  preferably defines a cutting edge. The cutting edges preferably intersect at their corners to provide a peripheral edge. 
     As shown in the drawings, the sides  32  of the cutting insert  20  match the configuration of the pocket  22  so that the cutting insert  20  cooperates with the pocket  22  so that one cutting edge extends at least slightly beyond the extent of the pocket  22  to engage a work piece. 
     A shim  35  can be provided between the lower face  30  of the cutting insert  20  and the bottom surface  24  of the pocket  22 . The shim  35  can be provided for adjusting the height of various cutting inserts relative to the pocket  22 . 
     As shown in the drawings, the cutting insert  20  is retained in the pocket  22  by a clamp  36 . The clamp  36  may be any suitable configuration for retaining the cutting insert  20  in the pocket  22 . The clamp  36  shown includes a first end  38  and a second end  40 . The first end  38  is in the form of a sleeve that is adapted to be secured to the head  18  of the tool holder  10 . This is preferably accomplished by providing the head  18  with a threaded hole (not shown) which is adapted to align with a passage  42  (shown in FIG. 9) in the first end  38  of the clamp  36 . A screw, such as the hollow head screw  44  shown in FIG. 9, is adapted to pass through the passage  42  and threadably engage the threaded hole in the head  18 . 
     The second end  40  is in the form of a leg or claw. The screw  44  can be loosened to permit the second end  40  of the clamp  36  to be free to pivot over the cutting insert  20  or out of its way. With the second end  40  of the clamp  36  over the cutting insert  20 , the screw  44  can be tightened to urge the second end  40  into contact with at least a portion of the cutting insert  20 . This urges the lower face  30  of the cutting insert  20  into contact with the bottom surface  24  of the pocket  22 . 
     The head  18  may further be provided with a recess within which the clamp  36  can seat when the second end  40  of the clamp  36  is in tight contact with the cutting insert  20 . This is to reduce the risk of the clamp  36  moving when in tight contact with the cutting insert  20 . If such a recess is provided, it is preferred that the pocket be deeper than the clamp recess. 
     It is also preferred that the head  18  be provided with an aperture (not shown) into which a dowel rod or locator pin  46  (shown in FIG. 9) is press fit. The pin  46  is adapted to be received by an opening  48  (also shown in FIG. 9) in the cutting insert  20 . It is preferred that the opening  48  be provided in the center of an indexable cutting insert to permit the cutting insert to be rotated to expose a new cutting edge. The pin  46  is provided to prevent the cutting insert  20  from moving, for example, in a lateral direction, out of the pocket  22 . 
     In accordance with the present invention, the head  18  is further provided with a chip breaker, as generally indicated at  50 . In the drawings, the chip breaker  50  is provided on a face or flank surface  51  of the head  18  below or adjacent the pocket  22 . A flank surface  51  is provided on opposing sides of the head  18 . The chip breaker  51  may be provided on one or both flank surfaces. One chip breaker  51  is suitable for turning operations and other chip breaker  51  is suitable for facing operations. 
     In FIGS. 1 and 2, the chip breaker  50  is comprised of a plurality of generally parallel V-shaped grooves  52 . The grooves  52  extend substantially parallel relative to the central axis of the shank  16 . The grooves  52  are spaced substantially equidistantly apart from the pocket  22  and from each other. 
     The grooves  52  are formed by two surfaces  54   a ,  54   b . A first surface  54   a  extends inwardly and downwardly relative to the flank surface  51  of the head  18  at an obtuse angle relative to the flank surface  51 . A second surface  54   b  extends inwardly and upwardly relative to the flank surface  51  at an obtuse angle relative to the flank surface  51 . The first surface  54   a  has a greater depth than the second surface  54   b  and the two surfaces  54   a ,  54   b  intersect at an included angle that is between about 70 and 80 degrees. 
     It should be understood that the grooves  52  could be any suitable shape. However, the shape may be dictated by certain factors, such as the composition of the work piece, and the feed rate of the work piece, and the depth or width of a cut. Examples of alternative groove patterns are shown in FIGS. 3A through 3E. It should be understood that any number of grooves (including a single groove, as shown in FIG. 3E) could be provided on the flank surface  51  of the head  18 . The distance between grooves can be the same or different. Moreover, grooves need not be arranged parallel to one another. For example, grooves  56  may extend transversely relative to one another, as shown in FIG.  3 C. 
     Grooves may be substantially the same width. Identical width grooves  54 ,  56  are shown, for example, in FIGS. 3B and 3C. Alternatively, the widths of grooves can be different relative to one another. Different width grooves  58   a ,  58   b ,  58   c  and  60   a ,  60   b  are shown, for example, in FIGS. 3A and 3D, respectively. 
     Grooves that differ in width are also illustrated in FIGS. 4A through 4E. It should be noted that the width of each groove in FIGS. 4A through 4E increases from the upper groove to the lower groove. However, other groove patterns may be suitable for carrying out the invention. 
     Grooves may be linear or non-linear in shape. Linear shaped grooves  54 ,  56 ,  58   a ,  58   b ,  58   c  are shown in FIGS. 3A through 3C. Non-linear grooves  60   a ,  60   b  are shown, for example, in FIG.  3 D. 
     The cross-sectional shape of the grooves may differ. For example, grooves  62   a ,  62   b ,  62   c , as shown in FIG. 4A, may be defined by surfaces that intersect at included angles between about 70 and 80 degrees. Such grooves  52  are also shown in FIGS. 1 and 2 and described above. 
     Grooves  70   a ,  70   b ,  70   c  may also be defined at least in part by surfaces that intersect the flank surface  51  of the head  18  at an angle that is substantially 90 degrees, as shown in FIG.  4 B. Another example of grooves  71   a ,  71   b ,  71   c  defined by surfaces that intersect the flank surface  51  of the head  18  at an angle that is substantially 90 degrees is shown in FIG.  4 E. The grooves  71   a ,  71   b ,  71   c  in FIG. 4E are also defined by three surfaces (shown but not referenced) as opposed to the two surfaces defining the grooves  62   a ,  62   b ,  62   c  and  70   a ,  70   b ,  70   c  in FIGS. 4A and 4B. FIGS. 4C and 4D are illustrative of grooves  66   a ,  66   b ,  66   c  and  68   a ,  68   b ,  68   c  that have other cross-sectional shapes than those referenced above. 
     An alternative chip breaker  72  is shown in FIGS. 5 and 6. This chip breaker  72  is comprised of a plurality of nodules or protrusions  74  extending outward from the flank surface  51  of the head  18 , forming annular intersections  75  between the protrusions  74  and the flank surface  51 . The instant invention is not limited to the pattern of protrusions  74  shown in the drawings. The protrusions  74  may take on other shapes than that shown in the drawings. Moreover, a single protrusion may be suitable for carrying out the invention. 
     Yet another chip breaker  76  is shown in FIGS. 7 and 8. The chip breaker  76  is comprised of a roughened surface, indicated generally at  78 . The roughened surface  78  may be a knurled surface or the like cut into the flank surface  51  of the head  18 . Alternatively, a grit material may be applied or formed on the flank surface  51 . 
     The operation of the invention will be explained with reference to the embodiment shown in FIGS. 1 and 2. In operation, the tool holder  10  is received in the magazine of a machine (not shown) so that the cutting insert  20  engages a work piece W. Upon engaging the work piece W, the cutting insert  20  cuts into the work piece W, forming a continuous curled shaving or chip C. As the cutting insert  20  moves from left to right, the chip C curls to the left of the head  18 . The design of the rake surface  28  of the cutting insert  20  imparts the curvature of the chip C in a desired direction. As the chip C engages a groove  52  in the chip breaker  50 , tension increases in the chip C causing it to break. The other embodiments of the chip breaker shown in the other drawings operate in the same manner. 
     Due to the moment and dynamic motion of the chip C, a small amount of force is required to break the chip C. Hence, when the chip C engages a groove, a protrusion, or even a rough surface, and more particularly, an angle or point of intersection defined by the groove, protrusion, or rough surface, the contact force causes the chip C to break. 
     Although the curvature of the chip C may be directed as desired due to the design of the rake surface  28  of the cutting insert  20 , the free end of the chip C randomly engages the flank surface  51  of the head  18 . Hence, it may be desirable to produce as many angular points of intersection on the flank surface  51  as possible. The protrusions  74  (shown in FIGS. 5 and 6) may produce a greater number of intersections than a plurality of V-shaped grooves. Similarly, the roughened surface  78  (shown in FIGS. 7 and 8) may possess a greater number of intersections than the protrusions  74 . For this reason, the roughened surface  78  may be a better chip breaking surface. 
     While this invention has been described with respect to several preferred embodiments, various modifications and additions will become apparent to persons of ordinary skill in the art. All such variations, modifications, and variations are intended to be encompassed within the scope of this patent, which is limited only by the claims appended hereto.