Insert for light feed, light depth of cut

Abstract: A polygonal, lay down indexable cutting insert for light feed and light depth of cut application. The insert has intermittent seating pads, chipbreaker pads (24), and stabilizer pads (44) and is configured to allow coolant to be circulated across the body of the insert during cutting operations.

Description: BACKGROUND OF THE INVENTION The present invention relates to a polygonal lay down indexable cutting insert of the type as indicated in the precharacterising portion of claim 1. A cutting insert of this type is known from EP-A-318000. It is an object of the present invention to provide an improved cutting insert for light feed and light depth of cut applications which performs high feed rates and excellent depth of cut. The above object is achieved by the subject matter of claim 1. Further improvements and preferred embodiments are indicated in the depending subclaims. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a top perspective view of the polygonal lay down indexable cutting insert. Figure 2 is a top plan view of the polygonal lay down indexable cutting insert. Figure 3 is an on-side view of the polygonal lay down indexable cutting insert showing the descending arcuate cutting surfaces. Figure 4 is a sectional view of the polygonal lay down indexable cutting insert along line 4-4 of Figure 2. Figure 5 is a cross-sectional view of the polygonal lay down indexable cutting insert along line 5-5 of Figure 2. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Turning now to the drawings wherein like numerals reference like structures, and particularly to Figures 1, 2 and 3, polygonal lay-down indexable cutting insert 10 is comprised of a top surface 12 and bottom surface 14, and sidewall surface 16 which extends substantially unbroken there between to define a body 18 of the insert. The insert is further equipped with a central hole 21 which extends through the body of the insert. The top and bottom surface of the insert are generally planar and are substantially parallel to each other and are equipped with raised island seating pads 20 located on the top and bottom surface of the insert and located opposite each other and separated from each other by the centrally located hole 21. In the corners 28 of the insert, raised chipbreaker pads 24 are disposed. The chipbreaker pads aid in the direction of the chip and break the chip into manageable sizes so that they do not interfere with the insert during cutting. The sidewall is comprised of the component side flanks 26 which are defined as that portion of the sidewall which extends from one corner to another corner of the insert. The insert cutting edge descends from the corners toward the mid-point 32 of the flank in a concave or descending arcuate cutting edge 30. It is preferred that the descending arcuate cutter edge descend from about 0.254 to 0.305 mm (0.010 to 0.012 inches) from the corners of the insert to the mid-point of the flank. The descending arcuate cutting edge lowers the cutting force and aids in chip control. The descending arcuate cutting edge is formed at the meeting of each component side flank at the top and bottom surfaces. Rearward of the cutting edge is a variable width land surface 38. The first variable width land surface is of narrower width at the corners of the inserts than at the flanks of the insert and is radiused at the corners of the insert. Along the flanks of each insert, the first variable width land angle surface has a width of 0.305 mm (0.012 inch) whereas along the flanks, it has a width of approximately 0.254 mm (0.010 inches) at each corner. The first variable width land angle surface has a first variable descending land angle which is a positive rake angle. The first variable descending land angle is greater at each corner of the insert than along the flanks. Indeed, in the present invention, it can be seen that the descending angle at the corners of the inserts is 14 degrees whereas the descending angle along the flanks of the insert is 12 degrees. Those skilled in the art will recognize that the nose and flanks may assume any descending angles, as long as the angle at the nose is greater than the flanks. Along the flanks of the insert is a second descending land angle surface which is adjacent to and rearward of the first variable land angle surface. The second descending land angle surface is planar along the flanks of the insert and is radiused at each corner of each insert. In this regard, as seen in Figure 5, it is contemplated that along the flanks of the insert, the second descending land angle is approximately 27 degrees, whereas in the corners of the insert, the second descending land angle surface is radiused at a radius of 0.254 mm (0.010 inch.) Returning to Figures 1-3, various stabilizer pads 44 are located intermittently along the cutting edge and abut the second variable land surface along each component side flank of the insert. The stabilizer pads as seen in Figure 4, are adjacent the first variable descending angle surface, and abut the secondary descending land angle. The seating pads, chipbreaker pads, and stabilizer pads are all raised from the top or bottom surface and have all ascending surface 46, which is inclined at same angle 48, which may or may not be the same for the seating pads, chipbreaker pads, and/or stabilizer pads. It is preferred that they all rise at a 35° angle. The seating pads are preferably raised higher from the top and bottom surface and function as a seating surface for the insert. Indeed, the seating pads are preferably raised 0.305 mm (0.012 inch) from the top surface and the chipbreaker pads are raised 0.254 mm (0.010 inch) from the top surface and the stabilizer pads are raised 0.0508 to 0.127 mm (0.002 to 0.005 inches) from the top surface. In this regard, surface 50 of the seating pad is planar and adapted to be seated in a tool holder pocket. The chipbreaker pads are designed such that they are shaped roughly as an inverted "T". It is contemplated that the cross bar of the inverted "T" be oriented toward the central hole, whereas the vertical portion of the "T" be oriented toward the corners of the insert. The islands, chipbreakers and stabilizer pads are configured as they are in order to allow coolant to be directed across the top and bottom surface during cutting operations to keep the insert cool and extend tool life. The polygonal lay down indexable cutting insert described herein is adapted to have a feed rate of about 0.152 to 0.406 mm per revolution (0.006 to 0.016 inch per revolution) and a depth of cut of from about 0.254 to 3.175 mm (0.010 to 0.125 inches).

Claims: A polygonal lay down indexable cutting insert (10) for light feed and light depth of cut applications of the type comprising: a top surface (12), a bottom surface (14) and a sidewall (16) extending substantially unbroken therebetween to define a body (18) of the insert, a centrally located hole (21) being provided in the top surface and extending through said insert body (18); chipbreaking pad (24) located at each corner (28) of the insert; said bottom surface (14) substantially parallel to said top surface (12) and having a plurality of islands and chipbreaking pads of the same configuration and location as said islands and chipbreaker pads of the top surface; said sidewall (16) comprised of a plurality of component side flanks (26) which extend from corner to corner of the insert, said component side flanks (26) descending arcuately from each corner (28) of the insert towards the midpoint (32) of each component side flank; a cutting edge formed at the meeting of each component side flank (26) and the top and bottom surfaces; said top surface (12) having a plurality of raised islands which act as seating pads (20) dispersed about said centrally located hole (21); a variable width land surface (38) extending rearwardly from said cutting edge (30); characterised by said variable width land surface (38) being of narrower width at the corners (28) than at the flanks of the insert and radiused at the corners of the insert; said variable width land surface having a first variable descending land angle; said first variable descending land angle being greater at each corner of the insert than along the side flanks; a second descending land angle surface (40) adjacent to and rearward of said first variable land angle surface (34), said second descending land angle surface (40) being planar along the flanks of the insert and radiused (36,42) at each corner of the insert; and stabilizer pads (44), wherein said stabilizer pads (44) are located intermittently along the cutting edge (30) and adjacent to said first variable descending land surface (34) along each component side flank (26) of the insert (10). The polygonal lay down indexable cutting insert (10) of claim 1, wherein said first variable descending land angle is 12° along the flank (26) of the insert and 14° at the corners (28) of the insert. The polygonal lay down indexable cutting insert (10) of claim 1, wherein said second variable descending land angle is 27° along the flanks (26) of the insert and radiused 0.254 mm (0.010 inches) at the corners (28) of the insert. The polygonal lay down indexable cutting insert (10) of claim 1, wherein the cutting edge (30) descends from each corner of the insert toward the midpoint (32) of each flank from about 0.254 to 0.305mm (0.010 to 0.012 inches). The polygonal lay down indexable cutting insert (10) of claim 1, wherein the chipbreaker pads (24) are designed such that they are shaped roughly as an inverted "T" wherein the cross bar of the inverted "T" is oriented toward the central hole (21) whereas the vertical portion of the "T" is oriented toward the corners (28) of the insert, thereby allowing coolant to be directed across insert top and bottom surfaces during cutting, whereby the insert is adapted to perform at a feed rate of about 0.152 to 0.406mm per revolution (0.006 to 0.016 IPR) and at a depth of cut which is 0.254 to 3.175mm (0.010 to 0.125 inches). The polygonal lay down indexable cutting insert (10) of claim 1, wherein said variable width land surface (38) is radiused at the corners (28) of the insert and has a width of 0.254mm (0.010 inches) at each corner of the insert and 0.305mm (0.012 inches) along the flank (26) of the insert. The polygonal lay down indexable cutting insert (10) of claim 1, wherein said first variable descending angle is a positive rake angle. The polygonal lay down indexable cutting insert (10) of claim 1, wherein there are two stabilizer pads (44) along each cutting edge. The polygonal lay down indexable cutting insert (10) of claim 1, wherein said seating pads (20) are opposite each other and separated from each other by said centrally located hole (21). The polygonal lay down indexable cutting insert (10) of claim 1, wherein said seating pads (20) are raised 0.305mm (0.012 inches) from the top surface (12) of the insert and said chipbreaker pads (24) are raised 0.254mm (0.010 inches) from the top surface and said stabilizer pads (44) are raised 0.0508 to 0.127mm (0.002 to 0.005 inches) from the top surface. The polygonal lay down indexable cutting insert (10) of claim 1, wherein said seating pads (20), chipbreaker pads (24) and stabilizer pads (44) have an ascending angle surface (46) inclined at about 35°.

Inventors: BERNADIC THOMAS J, KATBI KARL, LOWE TONY M, PATTERSON JOHN H, BERNADIC, THOMAS J., KATBI, KARL, LOWE, TONY M., PATTERSON, JOHN H.
Applicants: VALENITE INC, VALENITE INC.
Application year: 1993
Main classification: B23B27
IPC codes: B23B27