High sheer, ultra light duty insert

Abstract: A polygonal lay down indexable cutting insert for boring, finish turning and backfacing. The insert has a positive land surface and particularly useful at moderate to high cutting speeds and at low range of feed rates and depths of cut.

Description: The present invention relates to a polygonal, lay down indexable cutting insert of the type as indicated in the precharacterising portion of claim 1. Such a cutting insert is known from US-A-4,787,784. At that conventional cutting insert, the sectional view of the intersection of the floor surface and the ascending backwall is the intersection of two straight lines forming an angle. From EP-A-0222317, there is known a throwaway cutting insert having a concave rake surface which is composed of three separate surfaces. Said conventional throwaway cutting insert has a descending inclined surface which intersects the ascending chip breaker surface provided with a plurality of projections. It is an object of the present invention to provide an improved indexable cutting insert providing excellent chip control and minimal contact between the cutting edge and a work piece. The above object is achieved by the subject matter of claim 1. The inventive indexable cutting inserts permits turning ductile material like steel at moderate to high cutting speeds and at low ranges of feed and depth of cut. In particular, the inventive cutting insert is a high sheer, low force throwaway cutting insert which is a positive insert and is useful for boring, back facing and finish turning operations. Preferred embodiments and further improvements of the subject matter of claim 1 are defined in depending subclaims. Indeed the application feed rate range for the insert of the present invention is preferably from about 0.0508 to 0.3048mm per revolution (0.002 to 0.012 inches per revolution (IPR)) and the depth of cut range is preferably from about 0.127 to 2.032mm (0.005 to 0.080 inches). The insert has a cutting edge and a positive land surface. The chip breaker groove is of a concave radius shape, and, at the corners of the insert, the nose projections of the island form a convex radius shaped ascending backwall for chip control. A central aperture is provided and a recessed pad center surrounds the central aperture to allow for better seating within a tool holder pocket, and reduces overall production costs due to grinding and raw material required to form the insert. Brief Description of the Drawings Figure 1 is a top perspective view of the insert of the present invention. Figure 2 is a side view of the insert of the present invention Figure 3 is a top plan view of the insert of the present invention. Figure 4 is a sectional view of the insert of Figure 3 taken along line 2 - 2. Detailed Description of the preferred Embodiment Turning now to the drawings, and particularly to Figures 1 through 3, wherein like numerals depict like structures, polygonal, lay down indexable insert 10 is comprised of a top surface 12 and a bottom surface 14 which are substantially identical and parallel to each other, and side wall 16 extending substantially perpendicular thereto and unbroken therebetween to define a body 22. The sidewall is comprised of side flanks 20, which extend from corner to corner of the insert and are substantially planar. The insert is further equipped with a central aperture 26 extending through the body and an island 24 on the top and bottom surface of the insert. The island has nose projections 28 at each corner 18 of the insert. The nose projections are comprised of a main ridge 30, and side ridges 32 extending equidistant and located opposite to each other. Thus, on each side flank of the insert, there will necessarily be two nose portions comprised of a main ridge and two side ridges, one on either side of the main ridge. Accordingly, it can be seen that where two side ridges approach each other along any flank, there is formed a hook 46 which is useful for backfacing operations. At each hook, there is formed a flat, planar chip breaker bottom 44. Turning now to Figure 4, there is depicted therein a sectional view taken along line 4 - 4 of the insert of Figure 3. Cutting edge 34 is formed by the intersection of the sidewall and the top surface. Rearward of the cutting edge is positive land surface 36. Preferably, the land surface is inclined at about 16 to 18 degrees. The land surface is planar and of uniform width around the entire perimeter 37 of the insert. At each corner, the positive land intersects concave radius shaped chipbreaker groove 38. The groove is preferably of about 0.127 mm (0.005 inches) radius and descends 0.2032 mm (0.008 inches) from the cutting edge. The groove intersects the main ridge of the nose portion of the island which has a convex radius shape and functions as a convex radius ascending backwall. Thus, it can be seen that a chip would be strained in one direction in the groove and in another direction on the ascending backwall portion of the main ridge, thereby contributing to excellent chip control. The convex radius shape of the ascending backwall preferably has a 0.767 mm (0.030 inches) radius. It should also be noted that the planar top face 48 of the island is raised above the cutting edge, and preferably is raised 0.3048 mm (0.012 inches) from the chip breaker groove. The insert of the present invention is useful for boring, finish turning and backfacing operations and provides minimal contact between the cutting edge and a workpiece. The configuration of the island aids is profiling and backfacing operations. The insert is particularly useful with a feed rate of about 0.0508 to 0.3048 mm per revolution (0.002 to 0.012 IPR) and at depths of cut of (0.005 to 0.080 inches) 0.127 to 2.032 mm.

Claims: A polygonal, lay down indexable cutting insert (10) for low range of feed and depth of cut, comprising: a top surface (12) and a bottom surface (14) substantially parallel and identical to each other with a side wall (16) substantially perpendicular thereto and extending substantially unbroken therebetween to define a body (22), said side wall comprised of planar side flanks (20) extending from corner (18) to corner (18) of the insert, an island (24) formed on at least the top surface (12) of the insert, said island having a nose projection (28) at each corner of the insert, said nose projections comprised of a main ridge (30) and two side ridges (32) on either side of the main ridge, said side ridges extending equidistant and opposite to each other, a cutting edge (34) formed by the intersection of the sidewall (16) and the top surface (12), said cutting edge (34) extending along the periphery of the insert, a planar, descending positive land surface (36) extending rearward of the cutting edge, and a planar chip breaker bottom surface (44) along the flanks of the insert, said island (24) having a planar top face (48) which is raised above the cutting edge of the insert, characterized by a concave radius shaped chip breaker groove (38) extending parallel to the cutting edge (34) merging with an ascending convex radius shaped backwall (40) in a cross section through the main ridge (30) of the nose portion of the island at the corners of the insert. The insert of claim 1, wherein said positive land surface is inclined from about 16 to 18 degrees. The insert of claim 1, wherein said convex radius ascending backwall (40) has a radius of about 0.767mm (0.030 inches). The insert of claim 1, wherein said concave radius groove (38) has a radius of about 0.127mm (0.005 inches). The insert of claim 1, wherein said groove (38) descends about 0.2032mm (0.008 inches) from said cutting edge (34). The insert of claim 1, wherein said island top face (48) is raised about 0.3048mm (0.012 inches) from said chip breaker groove (38). The insert of claim 1, wherein said depth of cut is about 0.127 to 2.032mm (0.005 to 0.080 inches) and said feed rate is about 0.0508 to 0.3048mm per revolution (0.002 to 0.012 inches per revolution).

Inventors: KATBI KARL, LOWE TONY M, KATBI, KARL, LOWE, TONY M.
Applicants: VALENITE INC, VALENITE INC.
Application year: 1993
Main classification: B23B27
IPC codes: B23B27