High-feed turning tool assembly

Abstract

A two-directional high-feed turning tool assembly includes a tool holder, a cutting insert and a clamping element securing the cutting insert to the tool holder. The cutting insert includes an active cutting edge having a centrally located forwardmost edge portion and first and second main edge portions extending rearwardly from the forwardmost edge portion, as well as sideways to an extent further than flank tool sides of the tool holder. The first and second main edge portions also can each have a relatively small immersion angle facilitating high-feed turning in two sideways directions.

Claims

1. A two-directional high-feed turning tool assembly comprising: a tool holder, a cutting insert, and a clamping element; the tool holder comprising: opposite front and rear tool ends defining a longitudinal direction including a forward direction (D.sub.F) towards the front tool end and a rearward direction opposite thereto; opposite upper and lower tool sides defining a vertical direction including an upward direction towards the upper tool side and a downward direction opposite thereto; opposite first and second flank tool sides defining a sideways direction including a first side direction towards the first flank tool side and a second side direction opposite thereto; a vertical bisector plane (P.sub.V) extending parallel to the longitudinal and vertical directions, and bisecting the first and second flank tool sides adjacent to the front tool end; a shank portion; a head portion extending from the shank portion; and an insert pocket formed at an intersection of the front tool end and upper tool side of the head portion, the insert pocket comprising a pocket base surface; the cutting insert is secured to the insert pocket via the clamping element; the cutting insert comprising: opposite top and bottom surfaces, and an insert flank surface connecting the top and bottom surfaces; and a peripheral cutting edge formed along at least a portion of an intersection of the insert flank surface and the top surface, the peripheral cutting edge comprising at least one active cutting edge; the active cutting edge comprising: a forwardmost edge portion located forward of the front tool end, extending further in the forward direction than the remainder of the active cutting edge, and having a lateral edge length measurable parallel to the sideways direction; a first main edge portion extending from the forwardmost edge in both the first side and rearward directions to a location further in the first side direction than the first flank tool side adjacent the front tool end, the first main edge portion having a first edge length measurable parallel to the sideways direction and a first edge depth measurable parallel to the longitudinal direction; a second main edge portion extending from the forwardmost edge in both the second side and rearward directions to a location further in the second side direction than the second flank tool side adjacent the front tool end, the second main edge portion having a second edge length measurable parallel to the sideways direction and a second edge depth measurable parallel to the longitudinal direction; the first edge length being larger than each of the first edge depth and the lateral edge length; and the second edge length being larger than each of the second edge depth and the lateral edge length; wherein: the tool assembly is configured for machining in a forward direction (D.sub.F) and also machining in two opposite side directions (D.sub.S1, D.sub.S2), both of which side directions are perpendicular to the forward direction (D.sub.F).

2. The tool assembly according to claim 1, wherein the first and second main edge portions define first and second immersion angles K1, K2 relative to the sideways direction, fulfilling the condition: 6K1, K230.

3. The tool assembly according to claim 2, wherein the first and second main edge portions define first and second immersion angles K1, K2 and the first and second immersion angles K1, K2 are equal in value.

4. The tool assembly according to claim 1, wherein the cutting insert further comprises a flank insert abutment surface adjacent to the insert bottom surface and the pocket base surface further comprises a flank pocket abutment surface; and the flank insert abutment surface abuts the flank pocket abutment surface.

5. The tool assembly according to claim 4, wherein the flank insert abutment surface is provided on an internal recess in the insert bottom surface and the flank pocket abutment surface is provided on a protuberance formed on the pocket base surface.

6. The tool assembly according to claim 5, wherein said protuberance extends further in one of the first and second sideways directions than in the other of the first and second sideways directions.

7. The tool assembly according to claim 5, wherein the internal recess is shorter on one side in one of the first or second sideways directions.

8. The tool assembly according to claim 4, wherein the flank insert abutment surface is the closest abutment surface of the cutting insert to the active cutting edge.

9. The tool assembly according to claim 1, wherein the forwardmost edge portion is straight in a top view of the cutting insert.

10. The tool assembly according to claim 1, wherein the first and second main edges are straight in a top view thereof.

11. The tool assembly according to claim 1, wherein the first and second main edge portions are equal in length.

12. The tool assembly according to claim 1, wherein each of the first and second main edges are at least twice the length of the forwardmost edge.

13. The tool assembly according to claim 1, wherein the insert pocket further comprises: a first pocket abutment wall extending upwardly from the pocket base surface and facing both the forward and second flank tool side directions; and a second pocket abutment wall extending upwardly from the pocket base surface and facing both the forward and first flank tool side directions; and the first pocket abutment wall and the second pocket abutment wall both abut the cutting insert's insert flank surface.

14. The tool assembly according to claim 13, wherein, in a top view of the insert pocket, the first pocket abutment wall and the second pocket abutment wall, where they abut the cutting insert, are asymmetric relative to the vertical bisector plane.

15. The tool assembly according to claim 1, wherein: the insert flank surface further comprises: a first insert flank sub-surface which faces both the rearward and second flank tool side directions; and a second insert flank sub-surface which faces both the rearward and first flank tool side directions; the insert's bottom surface further comprises: a flank insert abutment surface which faces the first flank tool side direction; the insert pocket further comprises: a first pocket abutment wall extending upwardly from the pocket base surface and facing both the forward and second flank tool side directions; and a second pocket abutment wall extending upwardly from the pocket base surface and facing both the forward and first flank tool side directions; the pocket base surface further comprises a flank pocket abutment surface facing the second flank tool side direction, the flank pocket abutment surface is located closer to the front tool end than the first and second pocket abutment walls; and wherein the only abutment locations of the insert and insert pocket are: the first insert flank sub-surface abuts the second pocket abutment wall; the second insert flank sub-surface abuts the first pocket abutment wall; the flank insert abutment surface abuts the flank pocket abutment surface; and the bottom surface abuts the pocket base surface.

16. The tool assembly according to claim 15, wherein: the second insert flank sub-surface abuts the first pocket abutment wall further, in the longitudinal direction, from the front tool end, than where the first insert flank sub-surface abuts the second pocket abutment wall.

17. The tool assembly according to claim 16, wherein: the flank pocket abutment surface and the second pocket abutment wall are on the same side of the vertical bisector plane and the first pocket abutment wall is on the other side of the vertical bisector plane.

18. The tool assembly according to claim 1, wherein the cutting insert is a three-way indexable insert.

19. The tool assembly according to claim 1, wherein the cutting insert is a single-sided insert.

20. The tool assembly according to claim 1, wherein the cutting insert is formed with a non-circular screw hole surface configured to direct a clamping force towards a particular insert flank surface location.

21. The tool assembly according to claim 1, wherein the first main edge portion and the second main edge portion extend further in the respective first and second side directions than the first and second flank tool sides, thereby defining a thin portion of the head portion; and the thin portion extends for a length measured in the longitudinal direction at least as long as a longitudinal insert pocket length of the insert pocket which is measured parallel to the longitudinal direction.

22. The tool assembly according to claim 1, wherein the insert bottom surface and the pocket base surface are flat.

23. The tool assembly according to claim 1, wherein the forwardmost edge portion intersects the vertical bisector plane.

24. The tool assembly according to claim 1, wherein: the cutting insert further has (i) a central insert axis; and (ii) an insert vertical plane (P.sub.I) which passes through the insert's top and bottom surfaces, contains the central insert axis and intersects the forwardmost edge portion; and the insert vertical plane (P.sub.I) is aligned with the vertical bisector plane (P.sub.V).

25. A two-directional high-feed turning tool assembly comprising: a tool holder, a cutting insert, and a clamping element; the tool holder comprising: opposite front and rear tool ends defining a longitudinal direction including a forward direction towards the front tool end and a rearward direction opposite thereto; opposite upper and lower tool sides defining a vertical direction including an upward direction towards the upper tool side and a downward direction opposite thereto; opposite first and second flank tool sides defining a sideways direction including a first side direction towards the first flank tool side and a second side direction opposite thereto; a vertical bisector plane extending parallel to the longitudinal and vertical directions, and bisecting the first and second flank tool sides adjacent to the front tool end; a shank portion; a head portion extending from the shank portion; and an insert pocket formed at an intersection of the front tool end and upper tool side of the head portion, the insert pocket comprising: a pocket base surface; a first pocket abutment wall extending upwardly from the pocket base surface and facing both the forward and second flank tool side directions; and a second pocket abutment wall extending upwardly from the pocket base surface and facing both the forward and first flank tool side directions; wherein: the first pocket abutment wall and the second pocket abutment wall both abut the cutting insert's insert flank surface; and in a top view of the insert pocket, the first pocket abutment wall and the second pocket abutment wall, where they abut the cutting insert, are asymmetric relative to the vertical bisector plane; the cutting insert is secured to the insert pocket via the clamping element; the cutting insert comprising: opposite top and bottom surfaces, and an insert flank surface connecting the top and bottom surfaces; and a peripheral cutting edge formed along at least a portion of an intersection of the insert flank surface and the top surface, the peripheral cutting edge comprising at least one active cutting edge; the active cutting edge comprising: a forwardmost edge portion located forward of the front tool end, extending further in the forward direction than the remainder of the active cutting edge, and having a lateral edge length measurable parallel to the sideways direction; a first main edge portion extending from the forwardmost edge in both the first side and rearward directions to a location further in the first side direction than the first flank tool side adjacent the front tool end, the first main edge portion having a first edge length measurable parallel to the sideways direction and a first edge depth measurable parallel to the longitudinal direction; a second main edge portion extending from the forwardmost edge in both the second side and rearward directions to a location further in the second side direction than the second flank tool side adjacent the front tool end, the second main edge portion having a second edge length measurable parallel to the sideways direction and a second edge depth measurable parallel to the longitudinal direction; the first edge length being larger than each of the first edge depth and the lateral edge length; and the second edge length being larger than each of the second edge depth and the lateral edge length.

26. A two-directional high-feed turning tool assembly comprising: a tool holder, a cutting insert, and a clamping element; the tool holder comprising: opposite front and rear tool ends defining a longitudinal direction including a forward direction towards the front tool end and a rearward direction opposite thereto; opposite upper and lower tool sides defining a vertical direction including an upward direction towards the upper tool side and a downward direction opposite thereto; opposite first and second flank tool sides defining a sideways direction including a first side direction towards the first flank tool side and a second side direction opposite thereto; a vertical bisector plane extending parallel to the longitudinal and vertical directions, and bisecting the first and second flank tool sides adjacent to the front tool end; a shank portion; a head portion extending from the shank portion; and an insert pocket formed at an intersection of the front tool end and upper tool side of the head portion, the insert pocket comprising: a pocket base surface comprising a flank pocket abutment surface facing the second flank tool side direction; a first pocket abutment wall extending upwardly from the pocket base surface and facing both the forward and second flank tool side directions; and a second pocket abutment wall extending upwardly from the pocket base surface and facing both the forward and first flank tool side directions; wherein the flank pocket abutment surface is located closer to the front tool end than the first and second pocket abutment walls; the cutting insert is secured to the insert pocket via the clamping element; the cutting insert comprising: opposite top and bottom surfaces, and an insert flank surface connecting the top and bottom surfaces, the insert bottom surface comprising: a flank insert abutment surface which faces the first flank tool side direction; the insert flank surface comprising: a first insert flank sub-surface which faces both the rearward and second flank tool side directions; and a second insert flank sub-surface which faces both the rearward and first flank tool side directions; and a peripheral cutting edge formed along at least a portion of an intersection of the insert flank surface and the top surface, the peripheral cutting edge comprising at least one active cutting edge; the active cutting edge comprising: a forwardmost edge portion located forward of the front tool end, extending further in the forward direction than the remainder of the active cutting edge, and having a lateral edge length measurable parallel to the sideways direction; a first main edge portion extending from the forwardmost edge in both the first side and rearward directions to a location further in the first side direction than the first flank tool side adjacent the front tool end, the first main edge portion having a first edge length measurable parallel to the sideways direction and a first edge depth measurable parallel to the longitudinal direction; a second main edge portion extending from the forwardmost edge in both the second side and rearward directions to a location further in the second side direction than the second flank tool side adjacent the front tool end, the second main edge portion having a second edge length measurable parallel to the sideways direction and a second edge depth measurable parallel to the longitudinal direction; the first edge length being larger than each of the first edge depth and the lateral edge length; and the second edge length being larger than each of the second edge depth and the lateral edge length; wherein the only abutment locations of the insert and insert pocket are: the first insert flank sub-surface abuts the second pocket abutment wall; the second insert flank sub-surface abuts the first pocket abutment wall; the flank insert abutment surface abuts the flank pocket abutment surface; and the bottom surface abuts the pocket base surface.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) For a better understanding of the subject matter of the present application, and to show how the same may be carried out in practice, reference will now be made to the accompanying drawings, in which:

(2) FIG. 1A is a top view of an example high-feed tool assembly according to the subject matter of the present application with a schematic portion of a workpiece shown;

(3) FIG. 1B is a side view of the tool assembly in FIG. 1A;

(4) FIG. 1C is a perspective view of the tool assembly in FIG. 1A;

(5) FIG. 1D is a front view of the tool assembly in FIG. 1A;

(6) FIG. 2A is a top view of the insert in FIG. 1A with a schematic portion of a workpiece shown;

(7) FIG. 2B is a side view of the insert in FIG. 2A;

(8) FIG. 2C is a bottom view of the insert in FIG. 2A;

(9) FIG. 3A is a top view of the tool holder in FIG. 1A;

(10) FIG. 3B is a side view of the tool holder in FIG. 3A;

(11) FIG. 3C is a perspective view of the tool holder in FIG. 3A;

(12) FIG. 3D is a front view of the tool holder in FIG. 3A;

(13) FIG. 4A is an enlarged view of the insert pocket of the tool holder in FIG. 3A;

(14) FIG. 4B is an enlarged side perspective view of the insert pocket in FIG. 4A, shown in a similar view to the insert pocket in FIG. 3C;

(15) FIG. 5A is a top view of another example high-feed tool assembly according to the subject matter of the present application;

(16) FIG. 5B is a side view of the tool assembly in FIG. 5A;

(17) FIG. 5C is a perspective view of the tool assembly in FIG. 5A;

(18) FIG. 5D is a front view of the tool assembly in FIG. 5A;

(19) FIG. 6A is a top view of the insert in FIG. 5A;

(20) FIG. 6B is a side view of the insert in FIG. 6A;

(21) FIG. 6C is a bottom view of the insert in FIG. 6A;

(22) FIG. 7A is a top view of the tool holder in FIG. 5A;

(23) FIG. 7B is a side view of the tool holder in FIG. 7A;

(24) FIG. 7C is a perspective view of the tool holder in FIG. 7A; and

(25) FIG. 7D is a front view of the tool holder in FIG. 7A.

DETAILED DESCRIPTION

(26) Referring to FIGS. 1A to 1D, illustrated is a high-feed tool assembly 10 comprising a three-way indexable insert 12, a tool holder 14 and a screw 16 securing the insert 12 to the tool holder 14.

(27) To describe the cutting insert 12 in more detail, attention is drawn to FIGS. 2A to 2C.

(28) The insert 12 comprises opposite top and bottom surfaces 18, 20 and an insert flank surface 22 connecting the top and bottom surfaces 18, 20.

(29) The insert 12 further comprises a peripheral cutting edge 35 formed at an intersection of the top surface 18 and the insert flank surface 22. The peripheral cutting edge 35 comprises first, second and third active cutting edges 24A, 24B, 24C. Each of the first second and third active cutting edges 24A, 24B, 24C is formed on a different side of the three-way indexable insert 12 (i.e. a different one of the active cutting edges is presented when the cutting insert 12 is rotated 120 degrees about a centrally located insert axis A.sub.I).

(30) As seen in FIG. 2A, the first active cutting edge 24A, comprises a forwardmost edge portion 34, a first main edge portion 36A, and a second main edge portion 36B. Each active cutting edge is called so because it is the portion of the peripheral cutting edge 35 which is active in machining a workpiece 35 when mounted to the tool holder 14. After the cutting insert 12 is indexed a different active cutting edge is active. As seen in FIG. 2A the first active cutting edge 24A participates in cutting the workpiece 25. The cutting insert has an insert vertical plane P.sub.I which passes through the insert's top and bottom surfaces, contains the central insert axis A.sub.I and intersects the forwardmost edge portion 34.

(31) Since all three sides of the insert are rotationally identical, the description will only relate to one of the three symmetric sets of features.

(32) While the first active cutting edge 24A is shown at the bottom of FIG. 2A, for describing abutment or mounting of the insert 12, for ease of explanation the first active cutting edge 24A is located at the right-side of the bottom view in FIG. 2C.

(33) The bottom surface 20 comprises an internal recess 26 which in turn comprises a flat flank insert abutment surface 28 at one side thereof and which faces the second sideways direction D.sub.S2.

(34) When mounted to the tool holder 14, as described below, the flank insert abutment surface 28 provides abutment relative to a distally located first insert flank sub-surface 30A and second insert flank sub-surface 30B.

(35) The insert 12 is a positive insert with the lower portion 32 thereof relieved inwardly relative to the peripheral cutting edge 35, as shown in FIG. 2B.

(36) As shown best in FIG. 2A, the forwardmost edge portion 34 has a lateral edge length L.sub.F measurable parallel to the sideways direction D.sub.S. The forwardmost edge portion 34 is preferably straight in a top view of the insert 12.

(37) The first main edge portion 36A extends from the forwardmost edge portion 34 in both the first side direction D.sub.S1 and rearward direction D.sub.R and has a first edge length L.sub.E1 and a first edge depth L.sub.D1 (which in this case is identical to the value designated a.sub.p).

(38) The second main edge portion 36B extends from the forwardmost edge portion 34 in both the second side direction D.sub.E2 and rearward direction D.sub.R and has a second edge length L.sub.E2 and a second edge depth L.sub.E2 (which in this case is identical to the value designated a.sub.p).

(39) As stated above, the first and second main edges 36A, 36B are preferably straight in a top view thereof (i.e. FIG. 2A). It is noted that these edges can even remove material until halfway through a radius corner 36C, 36D thereof as shown. The half radius corners 36C, 36D are included in the above-mentioned lengths. It will be understood that all of the three active cutting edges, i.e. the first, second and third active cutting edges 24A, 24B, 24C, meet at corners. Since the majority of the main edge portions are straight (except for a small inevitable corner portion), the main edge portions are considered straight.

(40) As shown, each of the first and second main edge portions 36A, 36B extend a significantly greater length in the sideways direction D.sub.S than in the longitudinal direction D.sub.L.

(41) Accordingly, the first and second immersion angles K1, K2, which in this preferred embodiment are both 15, which are relatively small angles.

(42) This geometry is also relevant to the distance R, explained below.

(43) Reverting to the description of the top surface 18 (also known as a rake surface), in the example shown, there is an identical chip-former arrangement 37 formed along the entire peripheral cutting edge 35.

(44) Referring to FIG. 2C, even though usually an imaginary circumscribing circle I.sub.C of the peripheral cutting edge 35 located along an upper surface would typically be drawn on FIG. 2A, for ease of visibility it is shown in FIG. 2C. Since the exemplified insert 12 is a so-called positive insert, the peripheral cutting edge 35 is visible in the bottom view.

(45) The insert's circumscribing circle I.sub.C allows calculation of a diameter Dc.

(46) It will be understood that a similar sized circular insert would have a cutting edge matching the circumscribing circle I.sub.C shown in FIG. 2C, yet the high-feed cutting edge is recessed therefrom, for example as shown by distance R in FIG. 2C (with respect to a different active cutting edge than the one described so far as an example, but symmetric thereto).

(47) Referring to FIG. 2C, the flank insert abutment surface 28 is closer to the first active cutting edge 24A than the first and second flank insert abutment sub-surfaces 30A, 30B. Alternatively stated, the flank insert abutment surface 28 is closer to the first active cutting edge 24A than the second and third active cutting edges 24B, 24C.

(48) To describe the tool holder 14 in more detail, attention is drawn to FIGS. 1A-1D and 3A to 3D.

(49) The tool holder 14 comprises opposite front and rear tool ends 38, 40 defining a longitudinal direction D.sub.L including a forward direction D.sub.F towards the front tool end 38 and a rearward direction D.sub.R opposite thereto; opposite upper and lower tool sides 42, 44 defining a vertical direction D.sub.V including an upward direction D.sub.U towards the upper tool side and a downward direction D.sub.D opposite thereto; and opposite first and second flank tool sides 46, 48 defining a sideways direction D.sub.S including a first side direction D.sub.S1 towards the first flank tool side 46 and a second side direction D.sub.S2 opposite thereto.

(50) More specifically, the tool holder 14 comprises a shank portion 50 and a head portion 52 extending from the shank portion 50, and an insert pocket 54 formed at an intersection of the front tool end 38 and upper tool side 42 of the head portion 52.

(51) A vertical bisector plane P.sub.V (FIG. 1A) extends parallel to the longitudinal D.sub.L and vertical directions D.sub.V, and bisects the first and second flank tool sides 46, 48 adjacent to the front tool end 38. While in the example shown in FIG. 7A, the vertical bisector plane P.sub.V incidentally also extends through the center of the shank portion 50, the significance of the vertical bisector plane P.sub.V, for the purpose of defining features of the present invention, is only with respect to the tool head portion 52, and not the shank portion 50.

(52) The tool holder 12 can optionally comprise a coolant arrangement, which shows in this preferred example multiple coolant outlets 56A, 56B, 56C, 56D, 56E, 56F (designated in FIG. 3D).

(53) Referring briefly to FIG. 1A, the head portion 52 can have a thin portion, i.e. a head portion width W.sub.H, which is smaller than an insert width W.sub.C portion adjacent the front end. Notably, the insert width W.sub.C is identical to an active cutting edge length, namely the combined length of lateral edge length L.sub.F, and the first and second edge lengths L.sub.E1, L.sub.E2.

(54) A longitudinal insert pocket length L.sub.F, measured in the longitudinal direction is shown in FIG. 3A.

(55) It will be understood that the first main edge portion 36A and the second main edge portion 36B extend further in the respective first and second side directions D.sub.S1, D.sub.S2 than the first and second flank tool sides 46, 48 thereby defining a thin portion (which in this case extends the entire length of the head portion 52). As shown in FIG. 1A, it will be understood the thin portion extends for a length measured in the longitudinal direction at least, and even more than, twice as long as a longitudinal insert pocket length L.sub.IL (FIG. 3A) of the insert pocket 54.

(56) Referring also to FIGS. 4A and 4B, the insert pocket 54 will be described.

(57) The insert pocket 54 comprises a pocket base surface 58, a first pocket abutment wall 60A extending upwardly from the pocket base surface 58 and which faces both the forward and second side direction D.sub.F, D.sub.S2; and a second pocket abutment wall 60B extending upwardly from the pocket base surface 58 and which faces both the forward and first side directions D.sub.F, D.sub.S1.

(58) The pocket base surface 58 comprises an upwardly projecting protuberance 62 which in turn comprises a flat flank pocket abutment surface 64 at one side thereof and which faces the second sideways direction D.sub.S2.

(59) To ensure contact of only the pocket flank abutment surface 64 and not to a pocket flank non-abutment surface 66 located on the opposite side of the protuberance 62, a screw hole axis A.sub.H of the screw hole 68 could be offset from the vertical plane P.sub.V, as shown. Alternatively, the protuberance can be asymmetric about the vertical plane P.sub.V and extends slightly further in the second sideways direction D.sub.S2 (not shown). It will be noted there may be other solutions with similar effect. Nonetheless both solutions (which include asymmetry about the vertical plane P.sub.V) allow the recesses 26 in the insert 12 to be made symmetrically.

(60) Alternatively, the insert pocket 54 can be symmetric and each recess 26 in the insert's bottom surface 20 could be slightly shorter on one side as long as the insert 12 is rotationally symmetric for each recess 26.

(61) Notably, in FIG. 4A, the desired lateral abutment surfaces (i.e. the first pocket abutment wall 60A, second pocket abutment wall 60B and flank pocket abutment surface 64; noting that this statement does not refer to the pocket base surface 58 which provides no lateral support) of the insert pocket 54 are each at different distances, measurable along the longitudinal direction D.sub.L, from the front end 38. While the first and second pocket abutment walls 60A, 60B may, in some embodiments, overlap partially in distance from the front end 38, the term different distances means that they do not have identical extensions in the longitudinal direction D.sub.L. Stated differently, one of the first and second pocket abutment walls 60A, 60B can begin or ends further from the front end 38 than the other.

(62) The flank pocket abutment surface 64 is the closest to the tool holder's front end 38.

(63) The first pocket abutment wall 60A is furthest from the front end and is located further in the first sideways direction than the others.

(64) The second pocket abutment wall 60B is, measurable along the longitudinal direction D.sub.L, located between the flank pocket abutment surface 64 and the first pocket abutment wall 60A, and is located further in the second sideways direction than the others.

(65) It will be understood that regardless of which sideways direction the tool assembly machines a workpiece, the same abutment surfaces are always in contact with the insert 12.

(66) Namely, the first insert flank sub-surface 30A abuts the second pocket abutment wall 60B, the second insert flank sub-surface 30B abuts the first pocket abutment wall 60A, the flank insert abutment surface 28 abuts the flank pocket abutment surface 64; and the insert's bottom surface 20 abuts the pocket base surface 58.

(67) However, the force distribution on the various abutment locations varies according to the direction of machining.

(68) Accordingly, when the tool assembly machines with the cutting insert 14, relatively speaking, moving in the second sideways direction D.sub.S2 (said movement being relative to the workpieceit will be understood the workpiece could be moving in the second sideways direction D.sub.S2 with the insert 14 being stationary, but having the same forces applied thereof as the insert moving in the first sideways direction D.sub.S1 and the workpiece being stationary) there are large forces applied on the flank pocket abutment surface 64. Whereas in the opposite machining direction, the first sideways direction D.sub.S1, there are far less forces applied on the flank pocket abutment surface 64 and significantly more are applied on the second pocket abutment wall 60B. The different distances from the front end 38 of the tool holder help prevent the insert from rotating in the insert pocket.

(69) While the rear portion of the insert pocket appears symmetrical in FIG. 3A, upon closer review of the enlarged insert pocket in FIG. 4A, it is noted this is not the case.

(70) Notably, for constructional strength purposes, the first pocket abutment wall 60A is part of a larger first wall 70A, and the second pocket abutment wall 60B is part of a larger second wall 70B.

(71) To ensure contact at the designated abutment portions, the larger first and second walls 70A, 70B are relieved from the first and second pocket abutment walls 60A, 60B. Such angles being artificially exaggerated for the purpose of understanding only and shown schematically as first second and third relief angles 1, 2 and 3.

(72) Referring to the other example tool assembly 10 shown in FIGS. 5A to 7D, an alternative abutment arrangement is shown. Corresponding elements have the same numeral as those described above with the addition of an apostrophe (').

(73) The high-feed tool assembly 10 comprising a three-way indexable insert 12, a tool holder 14 and a screw 16 securing the insert 12 to the tool holder 14.

(74) Only the differences of significance are noted. While it is clear that there is a different shank portion 50, the main difference is the insert mounting arrangement (noting that even the previously described insert mounting arrangement could be used with this shank portion 50 or vice versa).

(75) Specifically, in tool holder 10, the first and second pocket abutment walls 60A, 60B are symmetrical about the vertical plane P.sub.V.

(76) To ensure an asymmetric force arrangement, the insert's screw hole 74 (FIG. 6A) is non-circular. More precisely, it is provided with three linear screw hole abutment surfaces, namely first, second and third screw hole abutment surfaces 72A, 72B, 72C, one for each of the three indexable positions. Meanwhile, the insert pocket hole 68 (FIG. 7A) has a hole axis A.sub.H which is offset relative to the insert axis A.sub.I. As a consequence, a biasing force F is created, providing a similar asymmetric force distribution effect to the previous example which used differently located first and second pocket abutment walls.

(77) The biasing force F is in the rearward direction D.sub.R and (in this optional example) first sideways direction DS.sub.1.

(78) More precisely, the biasing force F is more towards the rearward direction D.sub.R than towards the first sideways direction D.sub.S1. In other words, a first biasing angle 4 formed between the direction of the biasing force F and the vertical plane P.sub.V in the rearward direction D.sub.R is smaller than a second biasing angle 5 formed between the direction of the force F and the sideways direction D.sub.S. It should be understood that the arrows and angles in the drawings are schematic and not intended for measurement.

(79) This can also be understood from the insert 14 alone, in which the first screw hole abutment surface 72A is not parallel with the insert flank abutment sub-surface adjacent thereto (in this example the first insert flank sub-surface 30A) but is slanted relative thereto.

(80) To describe the slant in a more geometric manner, a first normal direction D.sub.B1 to the screw hole abutment surface 72A is not parallel with a second normal direction D.sub.B2 to the first abutment sub-surface 30A. Stated differently, an imaginary line LI extending from the center of the insert 12 (i.e. through the insert axis A.sub.I) and the center of the first active cutting edge 24A, can form a first acute angle 1 with said first normal direction D.sub.B1 to the screw hole abutment surface 72A, and the imaginary line LI can form a second acute angle 2 with said second normal direction D.sub.B2 of the first abutment sub-surface 30A. The first acute angle 1 being larger than the second acute angle 2. Stated yet differently again, the second normal direction D.sub.B2 can be directed more towards the forwardmost edge portion 34 than the first normal direction D.sub.B1.

(81) Reverting to FIG. 1B, although in common with both embodiments, the forwardmost edge portion 34 is located forward of the front tool end 38, and is located further in the forward direction than the remainder of the active cutting edge, which in this example is the first active cutting edge 24A. The forwardmost edge portion 34 also intersects the vertical bisector plane P.sub.V as best shown in FIG. 1A. In the turning tool assembly, the insert vertical plane P.sub.I is aligned with the vertical bisector plane P.sub.V.

(82) As best shown in FIG. 1A, the first main edge portion 36A extends further in the first side direction than the first flank tool side 46 adjacent the front tool end, and the second main edge portion 36B extends further in the second side direction than the second flank tool side 48 adjacent the front tool end. Thus, the insert 12 (or insert 12) is shown immersed in the workpiece to a depth that would not be possible in the above-described prior art design and can even extend fully within the workpiece 25. While this is a significant advantage, at the present time even a high feed tool holder 12 or tool assembly 10 configured for machining in two opposite sideways directions is not even known, even without such significant advantage (which is therefore an additional benefit to the present invention).