Abstract:
A cutting insert includes an upper, lower and side surfaces and at least one cutting edge formed at an intersection of the upper surface with the side surface. A rake face of the insert is formed with one or more undulated chip forming grooves extending along the cutting edge and comprising a succession of alternating depressed and raised portions. Each depressed and raised portion is radially aligned with a central axis of the insert along the entire width of the chip forming groove.

Description:
FIELD OF THE INVENTION 
     The present invention pertains to a cutting insert to be used in cutting tools for chip-forming machining operations. More particularly, the present invention relates to a cutting insert having a top and bottom surfaces with radially aligned chip forming grooves for effective chip control. 
     BACKGROUND OF THE INVENTION 
     It is well known that in the design of cutting inserts and their mounting in a cutting tool, the provision of suitable cutting rake and relief clearance angles so as to ensure effective cutting with minimal energy consumption have to be balanced against undue weakening of the cutting edge. At the same time, provision must always be made for the effective removal of the chips generated in the cutting process. This latter requirement is particularly vital where the cutting tool operates in a very confined space, such as in a drilling operation. 
     The effective removal of the generated chips is to a large extent is dependant on the design of effective chip control to ensure that the generated chips are diverted from the cutting area by being deformed, split or broken into relatively short chips with minimal energy consumption and with effective heat dissipation. 
     To this end, it is well known to provide an insert with suitably formed depressions or grooves or with protrusions near the cutting edge which is designed to deform, split or break the chip with minimal energy consumption and with effective heat dissipation. 
     For example, U.S. Pat. No. 4,215,957 discloses a substantially flat rake surface of an insert which has a succession of depressions spaced along the cutting edge by substantially wide intermediate portions of the rake surface. 
     In U.S. Pat. No. 5,695,303, there is disclosed a cutting insert with undulating concave chip forming grooves comprising a succession of alternating depressed and raised portions extending in a direction perpendicular to the cutting edge along the entire width of the chip forming groove. 
     However, an effective control of chip orientation to a great extend depends on the positioning of the insert in the tool due to the specific shape of the chip forming groove and the smooth transitions between different portions thereof. 
     Thus, it may very often happen, particularly with cutting inserts positioned in a cutting tool at negative rake angles, that the chips cut by the cutting edge will be deflected in the direction towards, rather than away from a workpiece. Consequently, damage to the workpiece and tool chattering is possible. Thus, it would be desirable to provide an indexable cutting insert having a chip forming groove for providing effective chip control. 
     SUMMARY OF THE INVENTION 
     An object of the invention is to provide a cutting insert for use in a cutting tool having a chip forming groove for providing effective chip control. 
     It is another object of the invention to provide a double-sided indexable cutting insert having a chip forming groove enabling an effective chip control. 
     In one aspect of the invention, a cutting insert includes an upper surface, a lower surface and side surfaces. The cutting insert comprises at least one cutting edge formed at an intersection between the upper surface and one side surface. The at least one cutting edge extends between two adjacent cutting corners of the insert. The cutting insert also comprises at least one rake face adjacent the at least one cutting edge. The at least one rake face being formed with a first undulated chip forming groove extending along the at least one cutting edge and comprises alternating depressed and raised portions smoothly merging with one another. Each depressed and raised portion of the first chip forming groove is radially aligned with a central axis of the insert. 
     In another aspect of the invention, a cutting insert has an upper surface, a lower surface and side surfaces. The cutting insert comprises at least one cutting edge formed at an intersection between the upper surface and one side surface, at least one rake face adjacent the at least one cutting edge, a first undulated chip forming groove being formed on the at least one rake face and extending along the at least one cutting edge, a seating surface projecting above the cutting corners of the insert, and a second undulated chip forming groove extending along said seating surface. The first and second undulated chip forming grooves comprise alternating depressed and raised portions smoothly merging with one another, wherein each depressed and raised portion of the first and second chip forming grooves is radially aligned with a central axis of the insert. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     While various embodiments of the invention are illustrated, the particular embodiments shown should not be construed to limit the claims. It is anticipated that various changes and modifications may be made without departing from the scope of this invention. 
     FIG. 1 is a perspective view of a cutting insert in accordance with the invention. 
     FIG. 2 is a top plan view of the cutting insert in accordance with the invention. 
     FIG. 3 is a side elevational view of the cutting insert in accordance with the invention. 
     FIG. 4 is a cross section view of the cutting insert taken along line  4 — 4  of FIG.  2 . 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     One embodiment of a cutting insert  10  having a chip forming groove enabling an effective chip control is shown in FIGS. 1-3. The cutting insert  10  has generally an upper surface  12 , a lower surface  14  and side surfaces  16 . Four cutting edges  18  are formed at the intersection between the upper surface  12  or the lower surface  14  with the side surface  16 . In addition, four cutting corners  20  are formed at the intersection between two adjacent cutting edges  18 . Each of the upper and lower cutting edges  18  can be indexed into an active position and effectively utilized in a cutting tool (not shown). 
     The cutting insert  10  is of a generally equilateral parallelogram having an 80° diamond configuration. In other words, one side surface  16  has an angle, α, of approximately 10° with respect to an adjacent side surface  16 , as best shown in FIG.  2 . 
     The upper and lower surfaces  12 ,  14  of the insert  10  are formed with a centrally disposed, substantially planar seating surface  22  which projects above the cutting corners  20  by a height which is preferably in the range of 0.05 mm to 0.40 mm. The seating surface  22  serves as an insert support seating surface when the insert  10  is positioned in the cutting tool. 
     The regions of the upper and lower surface  12 ,  14  and the side surface  16  adjacent each cutting edge  18  constitute rake faces  24  and relief flanks  26  of the insert  10 , respectively. Each relief flank  26  is preferably planar. Each rake face  24  is formed with a first chip forming groove  28  extending along the cutting edges  18  and a second chip forming groove  30  extending along the seating surface  22  separated from the first chip forming groove  28  by an intermediate portion  32 . The chip forming grooves  28  and  30  may have a width, W, which may vary in the direction along the cutting edges  18  and the seating surface  22 . In illustrated embodiment, the width of the chip forming grooves  28  and  30  are in the range of about 0.001 inches to 0.25 inches. 
     The chip forming grooves  28  and  30  are undulated along the direction of the cutting edges  18  and seating surface  22 , respectively. Specifically, the undulations of the first chip forming groove  28  comprise a succession of depressed portions  34  merging smoothly and spaced from one another by raised portions  36  to form a serrated cutting edge  18 . Similarly, the undulations of the second chip forming groove  30  comprise a succession of depressed portions  38  merging smoothly and spaced from one another by raised portions  40 . Preferably, the depressed and raised portions  34 ,  36 ,  38  and  40  extend outwardly in radial alignment with a central axis, A, of the insert  10 , as indicated by the dashed lines in FIG.  2 . By extending the depressed and raised portions  34 ,  36 ,  38  and  40  in radial alignment with the central axis, A, chip removal is greatly facilitated as compared to conventional cutting inserts in which the depressed and raised portions are substantially perpendicular to the cutting edge. 
     In the illustrated embodiment, the insert  10  has six depressed and raised portions  34 ,  36  along each cutting edge  18  having a length of about 0.50 inches. However, the number (frequency) of depressed and raised portions  34 ,  36 ,  38  and  40  of the first and second chip forming grooves  28  and  30  may vary depending on the length along each cutting edge  18 . In other words, a cutting insert having a longer cutting edge would have a greater number of depressed and raised portions than a cutting insert having a shorter cutting edge. Thus, the insert  10  can have as few as one (1) and as many as thirty (30) depressed and raised portions  34 ,  36 ,  38  and  40  along each cutting edge  18 . 
     In the illustration embodiment, the depressed portions  34  and  38  have a radius of approximately 0.060 inches and the raised portions  36 ,  40  have a radius of approximately 0.075 inches. However, the number of depressed and raised portions  34 ,  36 ,  38  and  40  of the first and second chip forming grooves  28  and  30  may also vary depending on the radius (amplitude) of the depressed and raised portions  34 ,  36 ,  38  and  40 . In other words, a cutting insert with a larger radius for the raised and/or depressed portions will have a fewer number of depressed and raised portions along the length of each cutting edge than a cutting insert with a smaller radius for the raised and/or depressed portions. Thus, the radius of the depressed and raise portions  34 ,  36 ,  38  and  40  of the insert  10  can be within the range of approximately 0.020 to 0.188 inches. 
     Referring now to FIG. 4, the cross-sectional shape of the seating surface  22 , the chip forming groove  30 , the intermediate portion  32 , a first ramp portion  42 , a second ramp portion  44 , and the cutting corner  20  is shown. It can be seen that the depth of the of the chip forming groove  30  with respect to the cutting corner  20  is preferably in the range of 0.001 inches to 0.075 inches. It will be noted that the profile for the chip forming groove  28  is similar to the chip forming groove  30 . 
     The intermediate portion  32  preferably has a profile which is generally tear drop in shape with a gradual increase in height from the second chip forming groove  30  to approximately the same height as the cutting corner  20 . The tear drop shape of the intermediate portion  32  facilitates in the chip breakage and removal of the insert  10 . However, it will be appreciated that the intermediate portion  32  may have any desired profile shape. In the illustrated embodiment, the intermediate portion  32  reaches a height of approximately 0.001 inches lower than the height of the cutting corner  20 . 
     In the illustrated embodiment, the first ramp portion  42  also has a profile which is tear drop in shape to facilitate chip breakage and removal, similar to the intermediate portion  32 . However, it will be appreciated that the first ramp portion  42  may have any desired profile shape. The second ramp portion  44  has a substantially linear profile that increases in height from the first ramp portion  42  to the cutting corner  20 . Preferably, the linear profile of the second ramp portion  44  forms an angle, β, of about 18 degrees which respect to a horizontal axis, H, of the insert  10 .  10 . However, it will be appreciated that the invention is not limited by the angle, β, and that the invention can be practiced with any desired angle. 
     As shown in FIG. 4, the seating surface  22  is higher in elevation than the cutting edges  18  and the cutting corner  20 . In the illustrated embodiment, the seating surface  22  is in the range of approximately 0.005 inches to 0.006 inches higher in elevation than the cutting edges  18  and the cutting corner  20 . 
     It should be noted that the shape of the chip forming grooves  28  and  30  can vary in the direction along the cutting edge  18 . In addition, the specific shape and dimensions of the insert  10  may vary depending on materials to be machined. Thus, the insert  10  can have a shape other than the parallelogram shape of the illustrated embodiment. For example, the insert may be square, trigon, octagon, and any other desired shape. Further, the insert  10  may be single-sided and/or have relief flank geometry of any suitable type. 
     The patents and publications referred to herein are hereby incorporated by reference. 
     Having described presently preferred embodiments the invention may be otherwise embodied within the scope of the appended claims.