GB2078568A

GB2078568A - Cutting Inserts and Holders

Info

Publication number: GB2078568A
Application number: GB8120252A
Authority: GB
Original assignee: Kennametal Inc
Current assignee: Kennametal Inc
Priority date: 1978-06-02
Filing date: 1979-05-30
Publication date: 1982-01-13
Also published as: SE7904803L; AU4733979A; GB2078569A; NO154217B; ES257022Y; FR2435319A1; IT7923217A0; CH630825A5; CA1104846A; FR2435319B1; ES257022U; FI79960C; DE2922536A1; FI791746A; DE2922536C2; NO791843L; MX149049A; NL7904366A; NO154217C; GB2078569B

Abstract

A cutting insert 24 has straight parallel sides 40 and conveying cutting edges 54 at each end. A clamping notch formed in one or both of top and bottom faces of the insert comprises two diagonal grooves 62 and 64, preferably in an x-shape, to enable the insert to be used in a righthand or a lefthand tool holder, with either end as the cutting end. <IMAGE>

Description

1 I A GB 2 078 568 A 1

SPECIFICATION Cutting Inserts and Holders

5.

0- This invention relates to cutting inserts and to r holders therefor.

Indexable cutting inserts for threading and grooving are known and find a wide variety of use throughout the metalworking industry. Indexable cutting inserts for threading and grooving and the tool holder that receives such inserts should be designed so that the insert is accurately located and rigidly held on the tool holder when performing any work.

The inserts must usually be small and narrow in width and have a portion that overhangs the tool holder to do the threading. Under these conditions, ideal arrangements for such inserts and tool holders are constantly being sought.

While various types of threading and grooving combinations are known, one successful arrangement for such an insert and tool holder is 85 described in applicant's own United States Patent No. 3,7 54,309. Indexable inserts described by the patent have been in the market for several years, have enjoyed success in the marketplace and have become known by most people in the metalworking industry, specifically in the threading and grooving area. The cutting edges of the inserts can take on various complex forms for threading operations while, also being capable of taking a simple form for grooving operations.

Another type of indexable insert on the market, which is usually used for turning, boring and profiling work, but not for threading and grooving operations, is described by applicant's United States Patent No. 3,399,442. These inserts describe an insert that can be used in a negative rake tool holder and yet present positive rake cutting edges to the workpiece. In some instances, as described by the patent, positive rake cutting conditions are preferable to negative 105 rake cutting conditions.

Indexable inserts, should, by their very nature, have as many cutting edges on the insert body as is possible. The threading and grooving indexable inserts described above have only two cutting regions on the body of the insert. It is proposed by this application to make an indexable threading insert similar to the threading and grooving inserts described above, but the threading insert body will have four cutting regions instead of only two cutting regions as was previously possible.

According to one aspect of the invention, there is provided a cutting insert having two end wall 'regions, parallel side walls and parallel top and 55. bottom walls perpendicular to said side walls, said insert being adapted for mounting in a pocket in a holder with one end region exposed, each end wall region comprising: at least two end walls that converge toward one another as they extend that extends along an edge of the relevant wall or walls; and cutting edges provided at the juncture of said outer region or regions with said convergent end walls, each recess means also including an inner region in the form of an abrupt rise leading from the deepest part of said outer region upwardly to the plane of the relevant one of said top and bottom walls, said cutting edges effectively defining a plane that forms an acute included angle with the plane of the relevent one of said top and bottom walls, and clamping notch means being provided in the relevent one of said top and bottom walls for use in clamping said insert in the pocket, said clamping notch means having two grooves extending across the top or bottom wall at an acute angle to said side walls.

Preferably, said clamping notch means is generally x-shaped.

Preferably, said insert is invertable about an axis perpendicular to said side wails.

Preferably, said clamping notch means is provided in each of said top and bottom walls.

Preferably, said outer region has a first portion extending parallel to one of said converging end walls to intersect one side wall and a second portion extending parallel to the other of said converging end walls to intersect the other side wall.

According to a further aspect of the invention, there is provided the combination of a tool holder having an insert pocket with a cutting insert according to said one aspect of the invention inserted in said pocket, which pocket has an end wall area and a side wall and bottom wall and is open on the other three sides, said end wall area comprising two opposing walls extending at right angles to said bottom wall and converging toward one another, all of said bottom wall, side wall and opposing walls contacting the insert, and there being provided a top clamp arranged to engage said notch means for holding the insert in the pocket.

Preferably, said end wall opposite said side wall converges towards the plane of said side wall.

For a better understanding of the invention, and to show how the same may be carried into effect, reference will now be made, by way of example to the accompanying drawings in which:

Figure 1 is a perspective view of a tool holder and insert; Figure 2 is a top view of an insert; Figure 3 is a side view of the insert of Figure 2; Figure 4 is a side view of a further insert; and Figure 5 is an insert and tool holder being presented to a workpiece so that near zero rake is presented to the workpiece and yet clearance is provided for the additional cutting edges on the insert.

away from the centre of the insert with the line of 125 Referring to the drawings in somewhat more intersection of said converging walls perpendicular to said top and bottom walls; recess means provided on at least one of said top and bottom walls and including an outer region detail, what is shown in Figure 1 is a tool holder 10 having an insert receiving pocket 12 at its forward end. The insert receiving pocket 12 has a side wall 14, bottom wall 16 and end wall area 2 GB 2 078 568 A 2 18, and is open on the other three sides. The end wall area 18 has opposing walls 20 and 22 that converge toward one another as they extend away from the front end of the tool holder.

Preferably, the opposing wall 20 which is opposite side wall 14 converges toward the plane of side wall 14. Cutting insert 24 is shown and is adapted to be received in pocket 12 of tool holder 10.

Clamp member 26 is shown and has a leg 28 which is adapted to be received in a slot 30 formed in the top of the tool holder 10. Clamp member 26 has a nose portion 32 which engages the top of insert 24. A clamp screw 34 extends through a hole in theclamp member 26 and into a threaded hole 36 provided in the top of tool holder 10. The insert 24 has end wall regions 38 as shown in Figure 1 and parallel side walls 40 as shown in Figure 2.

Shown in Figure 3, the insert also has parallel top and bottom walls 42 perpendicular to the side walls 40 and the insert is invertable about an axis perpendicular to the side walls 40. The insert 24 sits in pocket 12 and has one end region exposed for cutting a thread in a workpiece, and the clamp member holds the insert against side wall 14, bottom wall 16 and opposing wall 20.

End regions 38 of the cutting insert 24 comprise at least two end walls 44 and 46 which converge toward one another as they extend from the centre portion of the insert indicated at 48. A recess means 50 is formed on at least one of the top and bottom walls, Preferablv on both.

Each recess means 50 comprises an outer region 52 having two portions which extend along the outer edge of the top or bottom wall _parallel to respective converging end walls 44 and 46 and intersect respective side walls 40. Cutting edges 54 are formed at the junctures of the outer region 52 with the convergent end walls 44 and 46. The recess means 50 also includes an inner region 56 in the form of an abrupt rise that leads from the lowermost part of the outer region 52 upwardly to the plane of one of the top or bottom walls.

In Figure 3, the cutting edges 54 are shown on both end regions 38 of the cutting insert 24. The cutting edges 54 being on both end walls 44 and 46 effectively define a plane that forms an acute included angle to the plane of the corresponding top or bottom wall. The angle is preferably small and preferably anywhere from 5 to 7 degrees, depending upon the type of holder in which the insert will be seated. - As is shown in Figure 2, the insert 24 has two diagonal grooves 62 and 64 extending across wall 42 of the insert in an x-shape so that the insert can also be used in a righthand or lefthand tool holder.

Referring now to Figure 4, what is shown 125 therein is, again, cutting edges 54 on end regions 38 of cutting insert 24. The cutting edges 54 are slightly modified from those of Figure 3. The cutting edges 54 are shown being curved; however, they still effectively define a plane that 130 forms an acute included angle with the plane of corresponding top or bottom wall 42.

Shown extending from side wall to side w4ill in top or bottom wall 42 is again an x-shaped notch 62 which can also receive nose portion 32 of clamp member 26 to hold the insert 24 in tha. pocket 12. The clamp member must be angled to the direction of the pocket 12 so as to urge the insert against the three walls.

Referring to Figure 5, a workpiece 72 is being threaded by a cutting insert 24, in this case the insert of Figure 4. End region 38 is part of a peripheral surface of the insert 24 and is provided with a front clearance angle A from the surface of the workpiece being cut. This angle A may be from 5 to 10 degrees, depending upon the particular material and depth of cut being taken and other factors.

The insert has a recess means 50 in the upper face extending along the outer edge of the top or bottom wall and cutting edges 54 are formed at the juncture of the walls of the end region and the recess means.

The plane defined by the cutting edges 54 is go angled to the plane of one of the respective top or bottom wall and is a small, acute included angle. This provision allows the cutting edges to be presented to the workpiece at substantially zero degrees rake, even though the insert may be sitting in a negative rake tool holder.

Thus, a threading insert and tool holder are disclosed with the insert having parallel sides and parallel top and bottom walls perpendicular to the sides. The insert has end wall regions for cutting with the insert being invertable about an axis perpendicular to the side walls and adapted for mounting in a pocket of a holder with one end region exposed.

The end wall regions comprise at least two end walls that converge toward one another as they extend from the centre portion of the insert, and a recess means is formed on at least one of said top and bottom walls. The recess means has an outer region that extends along the outer edge of said top and bottom wall and cutting edges are formed at the juncture of said outer region with the convergent end walls.

The recess means also includes an inner region in the form of an abrupt rise leading from the lowermost part of the outer region upwardly to the plane of one of said top and bottom walls, the cutting edges defining a plane that forms an acute included angle with the plane of either the top or bottom walls.

A clamping notch is formed in either oneor both of the top and bottom walls of the Insert. The or each notch is formed as a pair of diagonal grooves extending between and at an acute angle to the parallel sides of the insert.

The insert is receivable in an insert receiving pocket of a tool holder. The insert receiving pocket has an end wall area, a side wall and a bottom wall, and is open on the other three sides. The end wall area of the pocket comprises two opposing walls extending at substantially right A.0 1 3 GB 2 078 568 A 3 angles to the bottom wall of the pocket. The opposing walls converge toward one another,,,preferably with the opposing wall opposite the _, side wall of the insert converging toward the 5 plane of the side wall.

A top clamp member on the tool holder is provided for holding the insert in the pocket. Preferably, the clamp member extends angularly to the length of the insert and, when engaged with the notch in the insert, pulls the insert together against the back, bottom and opposing wall of the tool holder pocket.

Claims

1. A cutting insert having two end wall regions, 55 parallel side walls and parallel top and bottom walls perpendicular to said side walls, said insert being adapted for mounting in a pocket in a holder with one end region exposed, each end wall region comprising: at least two end walls that converge toward one another as they extend away from the centre of the insert with the line of intersection of said converging walls perpendicular to said top and bottom walls; recess means provided on at least one of said top and bottom walls and including an outer region that extends along an end edge of the relevant wall or walls; and cutting edges provided at the juncture of said outer region or regions with said convergent end walls, each recess means also including an inner region in the form of an abrupt rise leading from the deepest part of said outer region upwardly to the plane of the relevant one of said top and bottom walls, said cutting edges effectively defining a plane that forms an acute included angle with the plane of the relevant one of said top and bottom walls, and clamping notch means being provided in the relevant one of said top and bottom walls for use in clamping said insert in the pocket, said clamping notch means having two grooves extending across the top or bottom wall at an acute angle to said side walls.

2. A cutting insert according to claim 1 wherein said clamping notch means is generally x- shaped. 45

3. A cutting insert according to claim 1 or 2 wherein said insert is inevitable about an axis perpendicular to said side walls.

4. A cutting insert according to claim 3 wherein said clamping notch means is provided in each of said top and bottom walls.

5. A cutting insert according to any one of claims 1 to 4 wherein said outer region has a first portion extending parallel to one of said converging end walls to intersect one side wall and a second portion extending parallel to the other of said converging end walls to intersect the other side wall.

6. A cutting insert according to claim 1 and substantially as hereinbefore described with reference to, and as illustrated in, the accompanying diagrammatic drawings.

7. The combination of a tool holder having an insert pocket with a cutting insert according to any one of claims 1 to 6 inserted in said pocket, which pocket has an end wall area and a side wall and a bottom wall and is open on the other three sides, said end wall area comprising two opposing walls extending at right angles to said bottom wall and converging toward one another, all of said bottom wall, side wall and opposing walls contacting the insert, and there being provided a top clamp arranged to engage said notch means for holding the insert in the pocket.

8. The combination according to claim 7 wherein said end wall opposite said side wall converges towards the plane of said side wall.

9. The combination of a tool holder having an insert pocket with a cutting insert according to claim 1 substantially as hereinbefore described with referance to, and as illustrated in, the accompanying diagrammatic drawings.

Printed for Her Majesty's Stationery Office by the Courier Press, Leamington Spa, 1982. Published by the Patent Office. 25 Southampton Buildings, London, WC2A 1 AY, from which copies may be obtained.