GB2078570A

GB2078570A - Cutting Insert Holders

Info

Publication number: GB2078570A
Application number: GB8120254A
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 tool holder 10 has an insert receiving pocket 12 defined by an end wall area 18, a side wall 14, and a bottom wall 16, with the other three sides open. The end wall area comprises two opposing walls at right angles to the bottom wall 16 and converging towards one another. A top clamp 26 is provided to hold an insert 24 in the pocket with all of said bottom wall 16, side wall 14 and opposing walls contacting the insert. <IMAGE>

Description

1 GB 2 078 570 A 1

SPECIFICATION Cutting Insert Holders

1 45 This invention relates to holders for cutting i n se rts.

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 described in applicant's own United States Patent No. 3,754,309. 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, 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 110 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 115 regions on the body of the insert. It is proposed by this 5pplication to make an indexable threading insert similar to the threading and grooving inserts described above, but the threading insert clamp for holding an insert in said pocket with all of said bottom wall, side wall and opposing walls contacting the insert.

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

Preferably, said top clamp is arranged to engage in a notch provided in the upper surface of an insert held in said pocket.

Where a cutting insert is held in said pocket, said insert preferably has two end wall regions, parallel side walls and parallel top and bottom walls perpendicular to said side walls, said insert being mounted in said pocket with one end region exposed, and 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 a clamping notch being provided in the relevant one of said top and bottom walls for use in clamping said insert in the pocket.

Preferably, said insert in invertable about an axis perpendicular to said side walls and a said clamping notch 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.

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 suitable for the holder of figure 1; Figure 3 is a side view of the insert of figure 2; Figure 4 is a side view of a further insert body will have four cutting regions instead of only 120 suitable for a holder of the kind shown in figure 1; two cutting regions as was previously possible.

According to the invention, there is provided a tool holder having an insert pocket formed therein, said pocket having an end wall area and a side wall and bottom wall and open on the other 125 three sides wherein said end wall area comprises two opposing walls extending at right angles to said bottom wall and converging toward one another, the holder further comprising a top Figure 5 is a top view of another insert suitable for a holder of the kind shown in figure 1; Figure 6 is a top view of a yet further insert suitable for a holder of the kind shown in figure 1; Figure 7 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; and GB 2 078 570 A 2 Figure 8 is a top view of the tool holder and insert.

Referring to the drawings in somewhat more detail, what is shown in figure 1 is a tool holder 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 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 75 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 80 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 rounded nose portion 32 which engages the top of insert 24. A clamp screw 34 extends through a hole in the clamp 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, preferably 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.

Shown in figure 2, the insert 24 has a rounded centre portion 48, a circular depression 60 which receives nose portion 32 of clamp member 26.

The central depression 60 is shown in figure 3.

Referring now to figure 4, what is shown 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 forms an acute included angle with the Riane of corresponding top or bottom wall 42. - Shown extending from side wall to side wall in top or bottom wall 42 is diagonal notch 62 which can also receive nose portion 32 of clamp member 26. A diagonal notch 62 is used to hold the insert 24 in the 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.

When, as shown in figure 2, the central depression 60 is used, the clamp member 26 may be aligned such that the slot 30 is behind the end wall area 20 of pocket 12 and the insert will then be held against four walls of the pocket, the four walls being side wall 14, the bottom wall 16 and opposing walls 20 and 22. When done in this manner, the insert may then be used in either righthand or lefthand tool holders for threading operations.

Shown in figure 5 is an insert 24 having two diagonal grooves 62 and 64 extending across one wall 42 of the insert in an x-shape so that the insert can also be used in a righthand or lefthand tool holder.

Shown in figure 6 is an insert 24, again, has a clamping notch in the form of a central recessed portion 66 which is noncircular and has four planar side walls 68 and 70 each at an acute l 00 angle to the top and bottom walls and appearing as a parallelogram in plan view. A nose 32 of clamp member 26 will engage the depressed portion and hold the insert 24 in tool holder 10.

Referring to figure 8, shown therein is tool holder 10 having an insert, as shown in figure 2, that utilises a central depression 60 to accept the nose 32 of the clamp member 26. Insert 24 is thus held in the tool holder by the four walls mentioned above.

Referring to figure 7, a workpiece 72 is being threaded by a cutting insert 24. 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 inihe 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 angled to the plane of one of the respective top or bottom wail 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.

Z1 1 4 GB 2 078 570 A 3 Thus a tool holder is disclosed for receiving an 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 sides and adapted for mounting in the pocket of the 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 or 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 one or both of the top and bottom walls of the insert.

Preferably, the notch is a diagonal groove extending between the parallel sides of the insert. 85 The notch may comprise, however, a circular depression near a centre portion of either one of the top or bottom walls.

The insert is received in the insert receiving pocket of the 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 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 plane of the side wall.

The 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. If the notch in the insert is similar to a circular depression, then the clamp member may extend over the longitudinal length of the insert, thereby eliminating the need to select a righthand or lefthand insert.

Claims

1. A tool holder having an insert pocket formed therein, said pocket having an end wall area and a side wall and bottom wall and open on the other 115 three sides wherein said end wall area comprises two opposing walls extending at right angles to said bottom wall and converging toward one another, the holder further comprising a top clamp for holding an insert in said pocket with all of said bottom wall, side wall and opposing walls contacting the insert.

2. A tool holder according to claim 1 wherein said end wall opposite said side wall converges toward the plane of said side wall.

3. A tool holder according to claim 1 or 2 wherein said top clamp is arranged to engage in a notch provided in the upper surface of an insert held in said pocket.

4. A tool holder according to any one of claims 1 to 3 wherein a cutting insert is held in said insert pocket. 75

5. A tool holder according to claim 4 wherein said cutting insert has two end wall regions, parallel side walls and parallel top and bottom walls perpendicular to said side walls, said insert being mounted in said pocket with one end region exposed, and 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 a clamping notch being provided in the relevant one of said top and bottom walls for use in clamping said insert in the pocket.

6. A tool holder according to claim 5 wherein said insert is invertable about an axis perpendicular to said side walls and a said clamping notch is provided in each of said top and bottom walls.

7. A tool holder according to claim 5 or 6 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.

8. A tool holder substantially as hereinbefore described with reference 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.