GB2035859A

GB2035859A - Cutting insert

Info

Publication number: GB2035859A
Application number: GB7937381A
Authority: GB
Original assignee: Kennametal Inc
Current assignee: Kennametal Inc
Priority date: 1978-11-17
Filing date: 1979-10-29
Publication date: 1980-06-25
Also published as: GB2035859B; LU81889A1; ES264885Y; CH632174A5; JPS6037205Y2; BE880061A; FI793579A; IE792118L; IT1125685B; DE2946022A1; NO793720L; JPS5590207A; DE2946022C2; NL7908400A; AU522748B2; MX148589A; JPS58173406U; FR2441451B1; CA1101201A; IT7927274A0

Abstract

An indexable, invertable molded cutting insert is disclosed having top and bottom faces 12, 14 and a peripheral wall 16 joining said faces. At least one face has a cutting edge 18 formed at the juncture of the face and the peripheral wall with a cutting edge land 20 extending inwardly of the insert from the cutting edge. A first descending wall portion 22 extends inwardly and downwardly from the cutting edge land and joins an intermediate land area 24 that extends inwardly of the insert. The first descending wall preferably has a planar portion that forms an included angle with the plane of the cutting edge land of the insert that is less than 30 degrees. A second descending wall portion 26 extends from the inner edge of the intermediate land area inwardly and downwardly to a bottom wall area 28 on the insert. The molded insert is preferably formed of a cemented hard metal carbide material. <IMAGE>

Description

SPECIFICATION Cutting insert This invention relates to cutting tools, especially molded cutting inserts, that have a novel configuration on the cutting face that is designed to break chips more efficiently.

Recently, new designs of cutting inserts have emphasized that a molded chipbreaker groove on a cutting insert need not have an inwardly located rising wall structure that obstructs the free flow of the metal being removed from the workpiece.

Rather, it has been found that chips can curl naturally from the cutting insert and strike the workpiece and be broken without the utilization of the obstructing chipbreakers.

Cutting inserts known in the art and described above can be exemplified by a review of McCreery United States Patent No.

3,973,307.

Cutting inserts of the type described by United States Patent No. 3,973,307 are successful in insert cutting applications; however, when subjected to extremes of cutting conditions, are subject to a cratering effect near the junctures of the descending wall of the planar floor that eventually destroy the usefulness of the cutting insert. Also, the crater, as it is being formed, obstructs the free flow of metal and an increase in horsepower is required to remove chips from the workpiece.

It is an object of the present invention to provide a more efficient molded chipbreaker groove configuration for a cutting insert, preferably comprised of a cemented hard metal carbide material.

It is a further object of the present invention to provide a controlled crater area on the insert for impingement by the metal being removed .

It is a further object of the present invention to provide a longer life for the cutting insert with the provision of a controlled chip contact area.

According to the present invention, a cutting tool, especially a molded cutting insert, is described which comprises a polygonal body of cemented hard metal carbide. having top and bottom faces and a peripheral wall joining said top and bottom faces. At least one of the faces has a cutting edge formed at the juncture of the peripheral wall with the face and a cutting edge land extends inwardly from the cutting edge.

A first descending wall portion extends inwardly and downwardly from the cutting edge land area and, preferably, is located in a plane that would form an included angle with the plane of the cutting edge land of less than 30 degrees.

An intermediate land area joins the lower end of the first descending wall portion and extends inwardly from said first portion and joins a second descending wall portion. The second descending wall portion then extends inwardly and downwardly and joins a bottom land area on the insert.

Preferably, the cutting insert according to the present invention has at least two angularly related cutting edges for defining a plane, and all of the land areas are substantially planar and are within 1 5 degrees of being parallel with the plane defined by the cutting edges.

The width of the cutting edge land is preferably from .002 inches to .020 inches wide and the perpendicular distance from the plane of the cutting edges to the intermediate land area is within the range of from .002 inches to .015 inches. The preferable perpendicular distance from the intermediate land area to the bottom land area is in the range of from .005 inches to .030 inches.

The width of the intermediate area is, preferably, a minimum of one and one-half times the width of the cutting land area and, most preferably, is about twice the width of said cutting land area.

Depending upon the cutting conditions, the intermediate land area may have its greatest width as it extends around the corners of the polygonal insert or it may have its greatest width in between the corners of the inserts.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a perspective view of an insert according to the present invention.

Figure 2 is a sectional view taken through line Il-Il of Fig. 1.

Figure 3 is a perspective view of an insert according to the present invention having an intermediate land area wider near the corners of the insert.

Figure 4 is a perspective view of an insert according to the present invention having an intermediate land area wider in between the corners of the insert.

Referring to the drawings somewhat more in detail, shown in Fig. 1 is an indexable insert 10 having a top face 12 and a bottom face 14 with the peripheral wall 16 joining the top face 12 of the bottom face 14. The insert can be made so that it is indexable and invertable in a toolholder (not shown).

Face 12 of the cutting insert 10 has a cutting edge 18 formed at the juncture of the peripheral wall 16 and the top face 12. Cutting edge 18 in the insert 10, as shown, extends completely around the polygonal insert 10. The insert 10 is preferably molded from a cemented hard metal carbide material according to techniques well known within the industry.

Shown in Fig. 2 is the cutting insert 10 having the peripheral wall 16 join the bottom face 14 and the top face 12 of the insert 10.

Top face 12, when viewed in section, is comprised of the cutting edge 18 having a cutting edge land 20 extend inwardly toward the center of the insert. Top face 12 further comprises a first descending wall portion 22 that extends downwardly and inwardly toward the center of the insert from the inner edge of cutting edge land 20 until it joins an intermediate land area 24 of the insert face 12.

The intermediate land area 24 is spaced from the cutting edge 18 on the insert such that metal being removed from a workpiece will impinge upon the land area and curl upwardly therefrom so as to hit the workpiece and be broken thereby.

Comprising a further part of the top face 12 is a second descending wall portion 26 that begins at the inner edge of the intermediate land area 24 and extends downwardly and inwardly toward the center of cutting insert 10 until it joins a bottom land area 28 of the top face 12 of the cutting insert 10.

Preferably, the land areas 20, 24 and 28 are substantially planar surfaces on a cutting insert 10 wherein the cutting edge 18 is made up of angularly related cutting edges, such as 30 and 32. It is preferable that the planar land areas are all within 15 degrees of parallel with the plane defined by the two angularly related cutting edges 30 and 32.

Referring again to Fig. 2, the cutting edge land 20 has a width when measured from the cutting edge toward the center of the insert that is, preferably, within the range of from .002 inches to .020 inches when encountering moderate cutting conditions. The intermediate land area 24, when measured from the bottom of the first descending wall portion 22 to the top of the second descending wall portion, preferably, approximately twice the width of the cutting edge land area 20.

When the land areas 20, 24 and 28 are substantially planar in nature, it is preferable that the perpendicular distance from the plane of the angularly related edges of the cutting insert 10 to the intermediate land is in the range of from .002 inches to .015 inches.

Further, it is preferable that the perpendicular distance from the planar intermediate land area to the planar bottom area be in the range of from .005 inches to .030 inches.

In Fig. 2, viewing the first descending wall portion 22 and the peripheral wall 16, it is most preferable that the planar descending wall portion 22 form an included angle with a section of the planar peripheral wall portion 16 that is more than 60 degrees.

Referring to Fig. 3, what is shown therein is cutting insert 10 having in its top face 12 an intermediate land area 24 that is shown varying in width as it extends around the center of the insert. The intermediate land area 24 is shown widest when approaching the corners 36 of the cutting insert 10.

With reference to Fig. 4, again, the cutting insert 10 is shown with top face 12 having an intermediate land area 24. However, in this case, the intermediate land area is shown being widest in between corners 38 and 40 of the polygonal cutting insert 10.

Modifications may be made within the scope of the appended claims.

Claims

1. A molded cutting insert which comprises a polygonal body of hard wear resistant material, said polygonal body having top and bottom faces and a peripheral wall joining said top and bottom faces, at least one of said faces comprising: a cutting edge formed by the juncture of said peripheral wall with one of said faces; a cutting edge land extending inwardly from said cutting edge; a first descending wall portion forming an included angle with the plane of said cutting edge land of less than 30 degrees and extending inwardly from said cutting edge land, characterized in that an intermediate land area extends inwardly from said first descending wall portion; a second descending wall portion extending inwardly from said intermediate land area; and a bottom land area extending inwardly from said second descending wall portion.

2. A cutting insert according to Claim 1 further characterized in that said insert has at least two angularly related cutting edges defining a plane, all of said land areas being substantially planar and within 15 degrees of parallel with said plane defined by said angularly related cutting edge.

3. A cutting insert according to Claim 1 further characterized in that said cutting edge land is from .002 inches to .020 inches wide.

4. A cutting insert according to Claim 2 further characterized in that the perpendicular distance from the plane of said cutting edges and said intermediate land is in the range of from .002 inches to .015 inches.

5. A cutting insert according to Claim 2 further characterized in that the perpendicular distance from said intermediate land area to said bottom land area is in the range of from .005 inches to .030 inches.

6. A cutting insert according to Claim 1 further characterized in that the width of said intermediate land area is a minimum of one and one-half times the width of said cutting land area.

7. A cutting insert according to Claim 6 further characterized in that the width of said intermediate land is substantially twice the width of said cutting land.

8. A cutting insert according to Claim 1 further characterized in that said cutting edges extend from a corner of said polygonal body and said intermediate land area is widest nearest the corner of said insert.

9. A cutting insert according to Claim 1 further characterized in that said polygonal body has multiple corners thereon from which said cutting edges extend and said intermediate area is widest in between said corners.

10. A cutting insert substantially as hereinbefore described with reference to, and as illustrated in, the accompanying diagrammatic drawing.

11. Any features of novelty, taken singly or in combination, of the cutting insert as hereinbefore described with reference to the accompanying diagrammatic drawing.