Cutting insert with recessed corners

1. Field of the Invention

The present invention relates, in general, to a cutting insert used in metalworking operations and, more particularly, to chip flow control features on a cutting insert.

2. Description of Related Art

Cutting inserts are well known and a large percentage of them are of the throw away design. Such inserts are detachably clamped on a toolholder and then are discarded when they become dull or chipped. Throw away inserts are usually indexable and/or invertable so that an insert can be provided with at least two cutting edges for selective presentation to the cutting position. An indexable and/or invertable insert having multiple cutting edges is more economical because when one edge has been used, the insert may simply be indexed or inverted to the next usable edge. Such a feature is especially important when considering the high cost of materials from which inserts are produced.

The main object of metalworking is the shaping of a new work surface. Much attention is paid to the formation of the chip during the machining process, even though the chip is a waste product, because the consumption of energy occurs mainly in the formation and movement of the chip. Thus, an essential feature of any metalworking operation is effective chip flow. U.S. Pat. No. 6,769,844 entitled “Cutting Insert and Method of Making the Same” teaches a cutting insert with a convex wiper cutting edge with a chamfered corner provided between the cutting edges. This patent is assigned to the Assignee of the present application and is hereby incorporated by reference.

Because chip flow control is an important consideration in metal cutting operations, it has been a long standing objective in the art of metal cutting to develop improved chip flow control surfaces for use with cutting inserts.

The present invention is directed to a cutting insert comprising a rake face, a seating surface and a plurality of flank faces extending between the rake face and the seating surface. The intersection of the rake face and the plurality of flank faces define a plurality of side cutting edges. The rake face of the body has a plurality of corner regions formed at the intersection of side cutting edges to define corner cutting edges. The corner cutting edge in at least one corner region has a recessed profile when viewed from the side of the insert. The recessed profile has a concave shape and extends inwardly from the cutting edge. At the cutting edge, the recess has a conical shape to define a conical portion and further inward from the cutting edge the recess may have a cylindrical shape to define a cylindrical portion.

These and other features and characteristics of the present invention, as well as the methods of operation and functions of the related elements of structures and the combination of parts and economies of manufacture, will become more apparent upon consideration of the following description and the appended claims with reference to the accompanying drawings, all of which form a part of this specification, wherein like reference numerals designate corresponding parts in the various figures. As used in the specification and the claims, the singular form of “a”, “an”, and “the” include plural referents unless the context clearly dictates otherwise.

FIG. 1 is a perspective view of a cutting insert in accordance with the present invention;

FIG. 2A is an enlarged perspective view of the corner region when viewed along arrow “ 2 ” in FIG. 1 ;

FIG. 2B is a top plan view of the corner highlighted in FIG. 2A ;

FIG. 3 is a cross-sectional view of the cutting insert taken along line 3 - 3 of FIG. 2B

FIG. 4 is a top plan view of the cutting insert of FIG. 1 ;

FIG. 5 is side elevational view of the cutting insert of FIG. 1 viewed from a corner;

FIG. 6 is a side elevational view of the cutting insert of FIG. 1 viewed from a side;

FIG. 7 is a cross-sectional view of the cutting insert taken along line 3 - 3 of FIG. 2B but presenting another embodiment whereby the insert has a land adjacent to the cutting edge;

FIG. 8 is a perspective view of a rotating toolholder utilizing the cutting insert in accordance with the present invention to machine a workpiece; and

FIG. 9 is a perspective view of a cutting insert similar to that insert shown in FIG. 1 but, wherein the rake face has a convex profile.

For purposes of the description hereinafter, the terms “upper”, “lower”, “right”, “left”, “vertical”, “horizontal”, “top”, “bottom”, “lateral”, “longitudinal” and derivatives thereof shall relate to the invention as it is oriented in the drawing figures. However, it is to be understood that the invention may assume various alternative variations, except where expressly specified to the contrary. It is also to be understood that the specific devices illustrated in the attached drawings, and described in the following specification, are simply exemplary embodiments of the invention. Hence, specific dimensions and other physical characteristics related to the embodiments disclosed herein are not to be considered as limiting.

Directing attention to FIG. 1 , a cutting insert 10 has a body 15 , comprised of a rake face 20 and a seating surface 25 . A plurality of flank surfaces 30 a - 30 d extends between the rake face 20 and the seating surface 25 . A plurality of side cutting edges 35 a - 35 d are defined by the intersection of the rake face 20 and the plurality of flank faces 30 a - 30 d . The rake face 20 has a plurality of corner regions 40 a - 40 d -formed at the intersection of the side cutting edges 35 a - 35 d to define corner cutting edges 45 a - 45 d.

As illustrated in FIG. 1 , the body 15 has a substantially square shape. However, this is not to be construed as limiting as a variety of other cutting geometries for cutting insert 10 have been envisioned, including octagonal and pentagonal. It should further be appreciated that each of the cutting edges described herein can be indexed into a working or active position and effectively utilized in a cutting tool of a type well know in the art. One particular use for this cutting insert 10 may be with a plunge milling cutter.

For purposes of simplicity, corner region 40 a will hereinafter be discussed with the understanding that such details may be applied to the remaining corner regions 40 b - 40 d of the insert 10 .

Directing attention to FIGS. 2A and 5 , the corner cutting edge 45 a in the corner region 40 a has a recessed profile 50 a when viewed from the side of the body 15 . As illustrated in FIGS. 2A and 5 , the recessed profile 50 a has a concave shape. Directing attention to FIGS. 2A and 2B , the recessed profile 50 a extends inwardly from the corner cutting edge 45 a . The recessed profile 50 a extends inwardly and into the rake face 20 from the corner cutting edge 45 a . As illustrated in FIGS. 2A and 3 , the recessed profile 50 a has a conical shape to define a conical portion 55 a . Briefly directing attention to FIG. 2B , the conical portion 55 a extends inwardly from the corner cutting edge 45 a a distance “A” of about 0.02-0.030 inches and preferably is in the range of about 0.005-0.006 inches. Additionally, directing attention to FIG. 2B , the conical portion 55 a may have a cone angle “B” of between about 5-45 degrees with a preferred angle of about 20 degrees. As illustrated in FIG. 3 , the central axis L of the cone may form an angle “C” with a line 26 parallel with the seating surface 25 of the body 15 of between about 2-30 degrees and preferably between about 5-10 degrees.

As illustrated in FIG. 2B , the recessed profile 50 a extends inwardly over the entire width W of the rake face 20 .

As furthermore illustrated in FIG. 2B , the recessed profile 50 a may include a cylindrical portion 60 a recessed within the rake face 20 and located inwardly of the conical portion 55 a . A blending portion 65 a may connect the conical portion 55 a with the cylindrical portion 60 a to provide for a smooth transition between these portions.

Directing attention to FIGS. 5 and 6 , the cutting edges 35 a , 35 b , for example, adjacent to the corner region 40 a may be straight or convex when viewed from the side as illustrated in FIG. 6 . For example, cutting edge 35 a as illustrated in FIG. 6 may have a radius of curvature R of approximately 8 inches. Briefly directing attention to FIG. 3 , it can be easily envisioned that the rake face 20 may also have a convex profile as it extends inwardly from the cutting edge 35 a.

So far discussed has been a cutting edge 35 a that is directly adjacent to the rake face 20 wherein the rake face has a positive rake face angle such that the cutting edge 35 a is relatively sharp and the edge may be honed to provide a radius thereupon to increase the strength of the cutting edge 35 a . Directing attention to FIG. 7 , it is entirely possible to introduce a land 70 between the cutting edge 35 a and the rake face 20 thereby providing additional strength to the cutting edges such as cutting edge 35 a.

As illustrated in FIG. 7 , the recessed profile 50 a extends inwardly from the corner cutting edge 45 a into the rake face 20 . In particular, the recessed portion 50 a continues inwardly from the cutting edge 45 a with the conical portion 55 a extending into the rake face 20 . Thereafter, the recessed profile 50 a continues to extend inwardly to the blending portion 65 a and into the cylindrical portion 60 a . In operation, the cutting edge 45 a follows the cutting edge 35 and causes the cutting chip to lift and flow away from the workpiece.

Directing attention to FIG. 6 , each flank face, for example flank face 30 d , is substantially flat and forms a clearance angle “F” of between about 0-30 degrees, preferably about 11-20 degrees, with a line perpendicular to the generally planar surface defined by the cutting edges 35 .

FIG. 8 shows the cutting insert 10 mounted within a toolholder and machining a workpiece. In particular, FIG. 8 illustrates the cutting insert 10 mounted within a milling cutter 100 . The milling cutter 100 is comprised of a body 105 which extends along a longitudinal axis 110 and has a first end 115 . A recess 120 extends into the first end 115 and has an insert pocket 125 adapted to receive the cutting insert 10 . The cutting insert 10 may have a bore 80 ( FIG. 4 ) extending therethrough to accommodate a mounting screw 132 which may be threadably engaged within a threaded bore (not shown) extending through a floor in the pocket 125 of the recess 120 . Utilizing this arrangement, the milling cutter 100 may be rotated about longitudinal axis 110 in a clockwise direction such that the cutting insert 10 engages the workpiece 130 to form the workpiece 130 in the desired shape.

FIG. 9 shows a perspective view of a cutting insert 200 similar to insert 10 in FIG. 1 but with a rake face 220 which has a convex profile as it extends away from the cutting edge 235 .

Although the invention has been described in detail for the purpose of illustration based on what is currently considered to be the most practical and preferred embodiments, it is to be understood that such detail is solely for that purpose and that the invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover modifications and equivalent arrangements that are within the spirit and scope of the appended claims. For example, it is to be understood that the present invention contemplates that, to the extent possible, one or more features of any embodiment can be combined with one or more features of any other embodiment.