REFERENCE TYPE FLAT CUTTING INSERT HAVING A CENTRAL BODY PORTION AND THREE CIRCUMFERENTIALLY SPACED CUTTING PORTIONS, AND CUTTING TOOL FOR REFERENCE TYPE FLAT CUTTING INSERT

Abstract

In a cutting tool having an indexable flat-lay cutting insert having a central body portion and three circumferentially spaced cutting portions, the cutting insert is removably secured to an elongated retaining portion of an insert holder. Each cutting portion has a cutting edge having a first cutting end point and a second cutting end point, the cutting edge being formed at an intersection of an upward rake face and a radially outward flank face. In a top view of the cutting insert, parallel imaginary first and second vertical planes including the first and second cutting end points intersect the central body portion at first and second body side points located at first and second cutting distances from the first and second cutting end points, respectively. Each of the first and second cutting distances is greater than 25 percent of a first radius of an imaginary first circle circumscribing the cutting insert.

Description

[Technical field]

[0001] The present invention relates to the use of non-rotary cutting tools in machining operations in general, and in particular to cutting tools for broaching operations, and to an indexable lay-down cutting insert for a cutting tool having a central body portion and three circumferentially spaced cutting portions. [Background technology]

[0002] In the field of cutting tools used in non-rotary cutting tool machining operations, there are numerous examples of indexable, flat-mounted cutting inserts that are removably retained within an insert-receiving pocket of a toolholder.

[0003] US 4,755,085 discloses an indexable cutting insert for slot milling. The insert has a triangular basic shape and is provided with three cutting edges. Each cutting edge is arranged on a convex portion, which is at least partially asymmetrically arranged with respect to a line parallel to the working direction of the insert. The insert has good accessibility to workpieces with narrow spaces.

[0004] US 5,931,613 discloses a cutting insert for machining metals forming a tip, which is assembled on a holder. The holding surface of the holder includes at least one rib extending in the longitudinal direction of the holder. The bottom surface of the insert includes at least one groove for receiving the rib of the holder. The side surfaces of the rib and the groove are inclined, so that the insert is supported by these side surfaces. The bottom side of the insert further includes a transverse surface, which extends perpendicular to the groove and fits into engagement with a corresponding transverse surface of the holding surface, and resists longitudinal forces applied to the cutting insert.

[0005] US 6,527,485 discloses a triangular thread-cutting insert having an assembly part whose three sides form a locating surface, the locating surface being located on three sides of an imaginary triangle and having three cutting arms with outer edges for thread cutting. The outer edges of each arm project laterally beyond the sides of the imaginary triangle, leaving a long length of the locating surface. The top surface of the assembly part forms a hexagon, the cutting arms project radially from three of the sides of the hexagon, the other three sides of the hexagon extend parallel to the locating surface of the assembly part. Each locating surface has a height less than the thickness of the insert, and a concave boundary region merges the top and bottom of each locating surface into the top and bottom surfaces of the insert, and merges the horizontally spaced ends of each locating surface into the cutting arms.

[0006] US2020 / 0324345A1 discloses a tool system for machining, comprising a tool body having a first end for connecting to a machine tool and a second end having an end face, on which a seat for an exchangeable cutting insert is formed. The cutting insert has a lower surface formed as an abutment surface, an upper side formed as a rake surface, and a peripheral side surface formed as a flank surface, and a cutting edge is formed at the transition from the upper side to the peripheral side. The cutting insert is arranged on the seat, with the upper side extending perpendicular to the longitudinal axis of the tool body, such that the cutting edge projects radially relative to the longitudinal axis beyond the outer circumferential part of the end face of the tool body, and two usable cutting corners and cutting corner portions adjoin the cutting edge on both sides. Summary of the Invention [Problem to be solved by the invention]

[0007] It is an object of the present invention to provide improved indexable cutting inserts and cutting tools.

[0008] It is also an object of the present invention to provide an indexable flat cutting insert capable of cutting a constant width keyway or passage in a workpiece.

[0009] It is a further object of the present invention to provide a lay-flat indexable cutting insert having coolant grooves positioned to precisely direct cooling fluid to any one of the cutting portions.

[0010] It is yet a further object of the present invention to provide a non-rotary cutting tool having good support for the active cutting portion.

[0011] It is yet a further object of the present invention to provide a non-rotary cutting tool capable of performing internal machining operations on workpieces having a relatively small diameter compared to the size of the cutting insert. [Means for solving the problem]

[0012] According to the present invention, there is provided an indexable flat cutting insert, the indexable flat cutting insert comprising: a central body portion; and three circumferentially spaced apart cutting portions projecting radially from the central body portion; the central body portion having a downwardly facing lower body surface and three circumferentially spaced radially outwardly facing central side surfaces; Each cutting portion has a downwardly facing support surface, an upwardly facing rake surface, a radially outward flank surface extending between the rake surface and the support surface, and a cutting edge formed at an intersection between the rake surface and the flank surface, each cutting edge having a first cutting end point and a second cutting end point; Each cutting part is A virtual bisection plane including the central axis and bisecting the cutting edge at the bisection cutting point; an imaginary first vertical plane and an imaginary second vertical plane that are parallel to the imaginary bisection plane and include the first cutting end point and the second cutting end point of each cutting portion, respectively; the imaginary first vertical plane and the imaginary second vertical plane do not intersect with each other except for including the first cutting end point and the second cutting end point; In the top view of the cutting insert, the imaginary first vertical plane and the imaginary second vertical plane intersect two different central side surfaces of the central body portion adjacent to the respective cutting portions at a first body side point and a second body side point, respectively; the first body side point and the second body side point are located a first cutting distance and a second cutting distance from the first cutting end point and the second cutting end point, respectively; an imaginary first circle having a first radius circumscribes the cutting insert; The first cutting distance and the second cutting distance are each greater than 25 percent of the first radius.

[0013] According to the present invention there is also provided a cutting tool comprising an insert holder and a cutting insert of the above-mentioned kind held in the insert holder, the insert holder has an elongated retaining portion extending away from the shank portion along the tool axis in a forward direction, the retaining portion having a seating surface transverse to the tool axis at a forward end of the retaining portion; the retaining portion has a major sub-retaining portion and a minor sub-retaining portion extending in a longitudinal direction, and the seating surface has a major sub-seat surface and a minor sub-seat surface associated with the major sub-retaining portion and the minor sub-retaining portion, respectively; The cutting insert is removably secured to the retaining portion at one of three indexing positions by a fastening member; At each indexing position, exactly one cutting portion is active and two cutting portions are inactive, the active cutting portion having an active cutting edge; The support surfaces of the two non-effective cutting parts are in clamping contact with the large counter bearing surface, The bearing surface of the effective cutting portion is in clamping contact with a small counterseat surface.

[0014] For a better understanding, the invention will now be described, purely by way of example, with reference to the accompanying drawings, in which dashed lines represent cut boundaries of partial views of elements, in which: [Brief description of the drawings]

[0015] [Figure 1] 1A-1C are perspective views of a cutting insert according to some embodiments of the present invention. [Diagram 2] FIG. 2 is a top view of the cutting insert shown in FIG. 1. [Diagram 3] FIG. 3 is a detailed view of the cutting insert shown in FIG. 2. [Figure 4] FIG. 2 is a bottom view of the cutting insert shown in FIG. 1. [Diagram 5] FIG. 2 is a side view of the cutting insert shown in FIG. [Figure 6] FIG. 6 is a cross-sectional view of the cutting insert shown in FIG. 2 taken along line VI-VI. [Figure 7] FIG. 7 is a cross-sectional view of the cutting insert shown in FIG. 2 taken along line VII-VII. [Figure 8] 1 is a perspective view of a cutting tool according to some embodiments of the present invention. [Figure 9] FIG. 9 is an exploded view of the cutting tool shown in FIG. 8. [Figure 10] FIG. 9 is a side view of the cutting tool shown in FIG. 8. [Figure 11] FIG. 9 is an end view of the cutting tool shown in FIG. [Figure 12] FIG. 12 is a cross-sectional view of the cutting insert shown in FIG. 11 taken along line XII-XII. [Figure 13] FIG. 9 is an end view of the cutting tool shown in FIG. 8 during a machining operation in a workpiece. [Figure 14] FIG. 9 is an end view of the cutting tool shown in FIG. 8 after a machining operation in a workpiece. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] Attention is first directed to Figures 1-5, which show an indexable cutting insert 20. The indexable cutting insert 20 may be manufactured by forming, pressing and sintering a cemented carbide, such as tungsten carbide, and may be coated or uncoated.

[0017] One aspect of the present invention relates to a cutting insert 20 having an upper surface 22 and a lower surface 24, a continuous peripheral side surface 26 extending between the upper surface 22 and the lower surface 24, and a central axis A1 extending through the upper surface 22 and the lower surface 24, the central axis A1 defining an upward direction DU-downward direction DD.

[0018] In some embodiments of the present invention, the cutting insert 20 may be indexable about the central axis A1.

[0019] Additionally, in some embodiments of the present invention, a through hole 28 coaxial with the central axis A1 may intersect the upper surface 22 and the lower surface 24.

[0020] As shown in Figures 1 to 5, the cutting insert 20 includes a central body portion 30 and three circumferentially spaced cutting portions 32, which protrude radially from the central body portion 30 relative to a central axis A1.

[0021] In some embodiments of the present invention, the cutting insert 20 may have exactly three circumferentially spaced cutting portions 32 .

[0022] Additionally, in some embodiments of the present invention, the cutting insert 20 may exhibit three-fold rotational symmetry about the central axis A1.

[0023] As shown in FIGS. 1-5, the central body portion 30 has a lower body surface 34 facing downwardly in the DD direction and three circumferentially spaced apart, radially outwardly facing central side surfaces 36. As shown in FIG.

[0024] Also, as shown in Figures 1 to 5, each cutting portion 32 has a support surface 38 facing in the downward direction DD, a cutting face 40 facing in the upward direction DU, a radially outward flank surface 42 extending between the cutting face 40 and the support surface 38, and a cutting edge 44 formed at the intersection line between the cutting face 40 and the flank surface 42, and each cutting edge 44 has a first cutting end point NE1 and a second cutting end point NE2.

[0025] It should be appreciated that because of the underbody surface 34 of the central body portion facing in the downward direction DD, and the rake face 40 of each cutting portion facing in the upward direction DU, the cutting insert 20 may be described as a lay-flat cutting insert 20 .

[0026] In some embodiments of the present invention, the three cutting edges 44 may define an imaginary first (upper) horizontal plane PH1 that is perpendicular to the central axis A1.

[0027] As shown in FIG. 5, no portion of the cutting insert 20 is located axially forward of the imaginary first horizontal plane PH1.

[0028] In some embodiments of the invention, the lower surface 24 may define an imaginary second (lower) horizontal plane PH2 that is perpendicular to the central axis A1.

[0029] As shown in FIG. 5, no portion of the cutting insert 20 is located axially rearward of the imaginary second horizontal plane PH2.

[0030] In some embodiments of the present invention, each central side 36 may be located between two circumferentially spaced cutting portions 32 .

[0031] It should be appreciated that in some embodiments of the present invention, the three central sides 36 and the three flank sides 42 may be minor surfaces of the peripheral side 26 .

[0032] It should also be appreciated that in some embodiments of the present invention, the body lower surface 34 and the three support surfaces 38 may be minor surfaces of the lower surface 24 .

[0033] 2 and 3, each cutting portion 32 further includes an imaginary bisection plane PB that includes the central axis A1 and bisects the cutting edge 44 at a bisection cutting point NBC. The imaginary bisection plane PB may be perpendicular to the cutting edge 44 of each cutting portion 32 at the bisection cutting point NBC.

[0034] It should be understood that throughout the specification and claims, each imaginary bisection plane PB does not necessarily divide each cutting edge 44 into two identical cutting edge portions.

[0035] In some embodiments of the present invention, as shown in FIG. 5, the three bisecting cutting points NBC may be contained within an imaginary first horizontal plane PH1.

[0036] Also, in some embodiments of the present invention, as shown in FIG. 5, the first cutting end point NE1 and the second cutting end point NE2 of each cutting edge 44 may be located axially rearward of the imaginary first horizontal plane PH1.

[0037] Furthermore, in some embodiments of the present invention, as shown in FIGS. 2-4, each cutting portion 32 may exhibit mirror symmetry about an imaginary bisecting plane PB of each cutting portion 32.

[0038] As shown in FIG. 6, in a cross-sectional view of the cutting insert 20 taken at one of the imaginary bisecting planes PB, each flank surface 42 may be inclined in a downward direction DD toward the central axis A1.

[0039] As shown in FIGS. 1 to 5, each cutting portion 32 may include a pair of lateral relief surfaces 46a, 46b located on either side of an imaginary bisecting plane PB of the cutting portion 32. As shown in FIG.

[0040] In some embodiments of the present invention, each lateral clearance 46 a , 46 b may extend from the clearance 42 associated with the lateral clearance 46 a , 46 b to one of the central side surfaces 36 .

[0041] It should be appreciated that in some embodiments of the present invention, three pairs of lateral relief surfaces 46a, 46b may be minor surfaces of the peripheral side surface 26.

[0042] As shown in Figures 2 and 3, each cutting portion 32 further includes an imaginary first vertical plane PV1 and an imaginary second vertical plane PV2 parallel to the imaginary bisection plane PB of the cutting portion 32, and the imaginary first vertical plane PV1 and the imaginary second vertical plane PV2 include a first cutting end point NE1 and a second cutting end point NE2, respectively.

[0043] Besides including the first cutting end point NE1 and the second cutting end point NE2, the imaginary first vertical plane PV1 and the imaginary second vertical plane PV2 do not intersect the respective cutting portion 32, and each cutting portion 32 has a cutting width WCT defined by the distance between the imaginary first vertical plane PV1 and the imaginary second vertical plane PV2 of the cutting portion 32. Thus, the imaginary first vertical plane PV1 and the imaginary second vertical plane PV2 may be referred to as the imaginary first vertical relief plane PV1 and the imaginary second vertical relief plane PV2. It should be understood that the cutting insert 20 may be technically capable of cutting a keyway or passageway having a constant passageway width equal to the cutting width WCT in a workpiece (not shown).

[0044] In some embodiments of the present invention, the cutting width WCT may be greater than 40 percent of the first radius R1, ie, WCT>0.40×R1.

[0045] As shown in Figures 2 and 3, in the top view of the cutting insert 20, the imaginary first vertical plane PV1 and the imaginary second vertical plane PV2 intersect two different central side surfaces 36 of the central body portion 30 adjacent to the respective cutting portions 32 at the first body side point NB1 and the second body side point NB2, respectively, which are located at a first cutting distance DC1 and a second cutting distance DC2 from the first cutting end point NE1 and the second cutting end point NE2, respectively.

[0046] It should be appreciated that for embodiments of the present invention in which each cutting portion 32 exhibits mirror symmetry about an imaginary bisecting plane PB of the cutting portion 32, the first distance DC1 and the second distance DC2 are equal.

[0047] In some embodiments of the present invention, each of the first cutting distance DC1 and the second cutting distance DC2 may be greater than 25 percent of the first radius R1, ie, DC1>0.25×R1 and DC2>0.25×R1.

[0048] For embodiments of the present invention in which the first cutting distance DC1 and the second cutting distance DC2 are each greater than 25 percent of the first radius R1, it should be appreciated that the cutting insert 20 may be technically capable of cutting a keyway or passage in a workpiece (not shown) having a passage width equal to the shortest distance between the first cutting distance DC1 and the second cutting distance DC2, and thus advantageously greater than 25 percent of the first radius R1. It should be appreciated that for such embodiments, said keyway or passage may have a constant passage width equal to the cutting width WCT.

[0049] As shown in FIG. 2, in a top view of the cutting insert 20, an imaginary first circle CC1 having a first radius R1 circumscribes the cutting insert 20.

[0050] It should also be appreciated that the imaginary first circle CC1 is defined by the three cutting edges 44 of the cutting insert, as shown in FIG.

[0051] In some embodiments of the present invention, the imaginary first circle CC1 may have a center that coincides with the central axis A1.

[0052] Also, in some embodiments of the present invention, as shown in FIG. 2, two spaced apart radially outermost cutting points NRC1, NRC2 of each cutting edge 44 may be located on an imaginary first circle CC1.

[0053] Furthermore, in some embodiments of the present invention, the three bisecting cutting points NBC may be located inside the imaginary first circle CC1.

[0054] As shown in Figures 2 and 3, in a top view of the cutting insert 20, at least a portion of each cutting edge 44 extending between the two radially outermost cutting points NRC1 and NRC2 may be linear and perpendicular to the respective imaginary bisection plane PB.

[0055] In some embodiments of the present invention, as shown in FIG. 3, the first cutting end point NE1 and the second cutting end point NE2 of each cutting edge 44 may not coincide with the two radially outermost cutting points NRC1, NRC2 of the same cutting edge 44, but may be located inside the imaginary first circle CC1.

[0056] In an embodiment of the present invention in which the first cutting end point NE1 and the second cutting end point NE2 of each cutting portion 32 are located inside the imaginary first circle CC1, each cutting edge 44 may have two curved end portions 48a, 48b.

[0057] As shown in FIG. 2, in the top view of the cutting insert 20, no part of the cutting insert 20 is located outside the imaginary first circle CC1.

[0058] Also, as shown in FIG. 2, the three bisecting cutting points NBC define three corner points of an imaginary equilateral triangle T1.

[0059] In some embodiments of the present invention, in a top view of the cutting insert 20, as shown in FIG. 2, each imaginary bisection plane PB may intersect one of the central sides 36 at a third body side point NB3 opposite the central axis A1 from the associated cutting portion 32.

[0060] Also, in some embodiments of the present invention, the three third body side points NB3 may be located outside the imaginary equilateral triangle T1.

[0061] In an embodiment of the present invention in which the three third body side points NB3 are located outside the imaginary isosceles triangle T1, in a top view of the cutting insert 20, each of the central side surfaces 36 may be convex and the central body portion 30 may have an approximately circular shape.

[0062] As shown in FIGS. 4 and 5, each support surface 38 may include male or female support elements 50. As shown in FIG.

[0063] In some embodiments of the present invention, each support element 50 may be in the form of an elongated ridge 52 extending radially relative to the insert axis A1.

[0064] Also, in some embodiments of the present invention, each support element 50 may be located partially on the body lower surface 34 .

[0065] As shown in FIGS. 4 and 5, the lower body surface 34 may include a central boss 54 that protrudes from the lower body surface 34 .

[0066] In a bottom view of the cutting insert 20, as shown in FIG. 4, the central boss 54 may have a generally circular shape.

[0067] For embodiments of the present invention in which each support element 50 is in the form of a radially extending elongated ridge 52 , each elongated ridge 52 may intersect a central boss 54 .

[0068] 4, the three elongated ridges 52 may merge with a central boss 54 to form a unitary structural member that extends to the radially outermost extents of the three support surfaces 38. This unitary structural member improves the rigidity of the cutting insert 20, advantageously reducing the susceptibility of the cutting insert 20 to breakage or deformation during clamping and machining operations.

[0069] Also, in some embodiments of the present invention, as shown in FIG. 5, the central boss 54 may have a raised boss end surface 56 that is coplanar with an imaginary second horizontal plane PH2.

[0070] In some embodiments of the present invention, the through hole 28 may intersect the raised boss end face 56 .

[0071] As shown in FIG. 5, the cutting insert 20 may have an insert height IH defined by the distance between an imaginary first horizontal plane PH1 and an imaginary second horizontal plane PH2.

[0072] In some embodiments of the present invention, the insert height IH may be less than the first radius R1, i.e., IH < R1.

[0073] As shown in FIG. 6, the through hole 28 may include a first hole portion 28a and a second hole portion 28b having different first hole diameters DB1 and second hole diameters DB2 in a virtual third horizontal plane PH3 and a virtual fourth horizontal plane PH4 that are each orthogonal to the central axis A1.

[0074] Also, as shown in FIG. 6, the virtual third horizontal plane PH3 may be located axially above the virtual fourth horizontal plane PH4, and the first hole diameter DB1 may be larger than the second hole diameter DB2, i.e., DB1 > DB2.

[0075] In some embodiments of the present invention, the first hole diameter DB1 may be at least 25 percent larger than the second hole diameter DB2, i.e., DB1 > DB2 × 1.25.

[0076] Also, in some embodiments of the present invention, the first hole diameter DB1 may be larger than half of the first radius R1, i.e., DB1 > 0.50 × R1.

[0077] Furthermore, in some embodiments of the present invention, the first hole diameter DB1 may be larger than the insert height IH, i.e., DB1 > IH.

[0078] As shown in FIG. 6, both the virtual third horizontal plane PH3 and the virtual fourth horizontal plane PH4 may be located closer to the virtual second horizontal plane PH2 than the virtual first horizontal plane PH1.

[0079] In some embodiments of the present invention, the second hole portion 28b may intersect the raised boss end face 56.

[0080] As shown in FIG. 4, each support element 50 may include a pair of support rib surfaces 58a, 58b that extend in parallel.

[0081] In some embodiments of the present invention, each pair of support flank surfaces 58a, 58b may intersect the flank surface 42 of the respective cutting portion.

[0082] Also, in some embodiments of the present invention, each support side surface 58a, 58b may be flat.

[0083] Additionally, in some embodiments of the present invention, each pair of support flank surfaces 58 a , 58 b may be spaced apart by an intermediate surface 60 .

[0084] Furthermore, in some embodiments of the present invention, each intermediate surface 60 may be flat.

[0085] For embodiments of the invention in which each support element 50 is in the form of a radially extending elongated ridge 52, the mid-surface 60 of each elongated ridge 52 may be contained within an imaginary second horizontal plane PH2.

[0086] As shown in FIG. 7, in a cross-sectional view of the cutting insert 20 taken on an imaginary third vertical plane PV3 perpendicular to one of the imaginary bisecting planes PB and intersecting the associated support element 50, each pair of support side surfaces 58a, 58b may form a V-shape.

[0087] In some embodiments of the present invention, an imaginary third vertical plane PV3 may be parallel to the central axis A1.

[0088] It should be appreciated that each pair of support flank surfaces 58a, 58b may be configured to form a V-shape in cross section to stably clamp the cutting insert 20 to the mating body.

[0089] As shown in FIGS. 1-5, the upper surface 22 may include three linearly extending coolant grooves 62.

[0090] In some embodiments of the present invention, each coolant groove 62 may extend along a groove axis A2 that is perpendicular to the central axis A1.

[0091] Also, in some embodiments of the present invention, each coolant groove 62 may cross two other coolant grooves 62 such that coolant fluid flowing along any one of the coolant grooves 62 crosses the other two coolant grooves 62.

[0092] Additionally, in some embodiments of the present invention, as shown in FIG. 2, each coolant groove 62 may be interrupted by a through hole 28 .

[0093] In some embodiments of the present invention, each coolant groove 62 may be interrupted by a through hole 28, however, it should be appreciated that in embodiments in which the imaginary third horizontal plane PH3 and the imaginary fourth horizontal plane PH4 are both located closer to the imaginary second horizontal plane PH2 than the imaginary first horizontal plane PH1, the fastening member 76 may advantageously occupy the through hole 28 without interrupting the coolant fluid flow along the entire length of each coolant groove 62.

[0094] As shown in Figures 2 and 6, each coolant groove 62 may intersect one of the three cutting portions 32 at a first groove end region NG1.

[0095] For embodiments of the present invention in which each of the three coolant grooves 62 intersects one of the three cutting portions 32, it should be understood that the coolant fluid may be directed to precisely any of the three cutting portions 32.

[0096] In some embodiments of the present invention, each coolant groove 62 may taper along a groove axis A2 of the coolant groove 62 toward a first groove end region NG1 of the coolant groove 62.

[0097] Also, in some embodiments of the present invention, an inclined surface 63 may be located between each first groove end region NG1 and the rake face 40 of the associated cutting portion.

[0098] As shown in Figures 2 and 6, each coolant groove 62 can intersect one of the central sides 36 at a second groove end region NG2 that is distal from the central axis A1 and on the opposite side of the central axis A1 from the first groove end region NG1.

[0099] In some embodiments of the present invention, each groove axis A2 may be contained within an imaginary bisecting plane PB of the associated cutting portion 32.

[0100] Also, in some embodiments of the present invention, in a top view of the cutting insert 20, as shown in FIG. 2, the three second groove end regions NG2 may be located outside the imaginary equilateral triangle T1.

[0101] It should be appreciated that for embodiments of the present invention in which the three second groove end regions NG2 are located outside the imaginary isosceles triangle T1, each coolant groove 62 may have a significant groove extent on the opposite side of the central axis A1 from the first groove end region NG1.

[0102] In some embodiments of the present invention, each third body point NB3 may be located in one of the second groove end regions NG2.

[0103] As shown in FIG. 2, in a top view of the cutting insert 20, each coolant groove 62 has a groove width WG.

[0104] In some embodiments of the present invention, the groove width WG of each coolant groove 62 may decrease along the groove axis A2 of the coolant groove 62 toward the first groove end region NG1 of the coolant groove 62.

[0105] Also, in some embodiments of the present invention, the groove width WG of each coolant groove 62 may decrease continuously from the second groove end region NG2 of the coolant groove 62 to the first groove end region NG1 of the coolant groove 62.

[0106] As shown in FIG. 6, in a cross-sectional view of the cutting insert 20 taken at one of the imaginary bisecting planes PB, the associated coolant groove 62 has a groove depth DG.

[0107] In some embodiments of the present invention, the groove depth DG may decrease along the groove axis A2 of the coolant groove 62 toward the first groove end region NG1 of the coolant groove 62.

[0108] Also, in some embodiments of the present invention, the groove depth DG may decrease continuously from the second groove end region NG2 of the coolant groove 62 to the first groove end region NG1 of the coolant groove 62.

[0109] 8-11, which illustrate a cutting tool 64 according to another embodiment of the present invention. The cutting tool 64 includes an insert holder 66 and the cutting insert 20 described above held within the insert holder 66.

[0110] The insert holder 66 has an elongated retaining portion 68 extending away from a shank portion 70 along the tool axis AT in a forward direction DF, the retaining portion 68 having a seat surface 72 at a front end 74 of the retaining portion 68 perpendicular to the tool axis AT.

[0111] In some embodiments of the present invention, exactly one cutting insert 20 may be removably secured to the retaining portion 68 .

[0112] Additionally, in some embodiments of the present invention, the central axis A1 may be parallel to the tool axis AT.

[0113] As shown in Figures 8-11, the cutting insert 20 is removably secured to the retaining portion 68 in any one of three indexing positions by fasteners 76, with the lower surface 24 of the insert in clamping contact with the seat surface 72 of the retaining portion, and exactly one cutting portion 32 is active in each indexing position.

[0114] In some embodiments of the present invention, the cutting tool 64 may be configured to perform machining operations without rotation about the tool axis AT, and may therefore be described as a non-rotating cutting tool 64.

[0115] As shown in FIG. 10, the retaining portion 68 has a retaining length HL along the tool axis AT.

[0116] In some embodiments of the present invention, the retention length HL may be three times greater than the first radius R1, ie, HL>R1×3.

[0117] As shown in Figures 8-10, the retaining portion 68 may have a large secondary retaining portion 68a and a small secondary retaining portion 68b extending in the longitudinal direction, and the seating surface 72 may have a large secondary seating surface 72a and a small secondary seating surface 72b associated with the large secondary retaining portion 68a and the small secondary retaining portion 68b, respectively.

[0118] In some embodiments of the present invention, the fastener 76 may be in the form of a clamping screw 78 that passes through the through hole 28 of the cutting insert and threadably engages a threaded hole 80 in the large secondary seat 72a.

[0119] Additionally, in some embodiments of the present invention, the threaded hole 80 may have a threaded axis A3 that is coaxial with the central axis A1.

[0120] Further, in some embodiments of the present invention, as shown in FIG. 12, the locking screw 78 may be located completely axially rearward of the single effective cutting edge 44 of the cutting insert along the tool axis AT.

[0121] Furthermore, in some embodiments of the present invention, the clamping screw 78 may be located completely axially rearward of the three coolant grooves 62 of the cutting insert along the tool axis AT.

[0122] In some embodiments of the present invention, each coolant groove 62 may be interrupted by a through hole 28, however, it should be understood that in embodiments in which the clamping screw 78 is located completely axially rearward of the three coolant grooves 62 of the cutting insert, the clamping screw 78 may advantageously occupy the through hole 28 without interrupting the coolant fluid flow along the entire length of each coolant groove 62.

[0123] As shown in FIG. 9, the fastening screw 78 can have a head portion 78a and an elongated, threaded shank portion 78b extending from the head portion 78a.

[0124] In some embodiments of the invention, as shown in FIG. 12, a head portion 78a of the clamping screw may occupy a first bore portion 28a of the through hole, and a portion of a shank portion 78b of the clamping screw may occupy a second bore portion 28b of the through hole.

[0125] As shown in FIG. 11, in an end view of the cutting tool 64, an imaginary first vertical plane PV1 and an imaginary second vertical plane PV2 of the single effective cutting portion 32 intersect the large sub-holding portion 68a at a first large holding point NH1 and a second large holding point NH2, respectively.

[0126] In some embodiments of the present invention, the imaginary first vertical plane PV1 and the imaginary second vertical plane PV2 of the single effective cutting portion 32 do not intersect the small secondary retaining portion 68b of the insert holder.

[0127] As shown in FIG. 11, in an end view of the cutting tool 64, the single effective cutting portion 32 has a maximum cutting width DC MAX Maximum cutting width DC MAX is defined as the shortest distance between either the associated first cutting end point NE1 or the second cutting end point NE2 and the first large holding point NH1 or the second large holding point NH2, respectively.

[0128] In some embodiments of the present invention, the maximum cutting depth DC MAX is greater than 20 percent of the first radius R1, i.e., DC MAX It can be >0.20×R1.

[0129] Maximum cutting depth DC MAX For embodiments of the present invention where R is greater than 20 percent of the first radius R1, the cutting tool 64 may be configured to cut into the workpiece (not shown) at a maximum cutting depth DC MAX It should be appreciated that it may be technically possible to cut a keyway or passageway having a passageway width equal to the cutting width WCT, and thus advantageously greater than twenty percent of the first radius R1. It should be appreciated that in such an embodiment, said keyway or passageway may have a constant passageway width equal to the cutting width WCT.

[0130] In some embodiments of the present invention, as shown in Figures 10, 13 and 14, the cutting tool 64 may be configured to machine a stationary workpiece W along a feed direction F parallel to a tool axis AT.

[0131] For embodiments in which the cutting tool 64 is configured to machine a stationary workpiece W along a feed direction F parallel to the tool axis AT, the cutting tool 64 may advantageously be configured to perform a broaching operation.

[0132] As shown in Figures 8 and 9, the two support surfaces 38 of the two non-effective cutting portions 32 are in clamping contact with the large counter-seat surface 72a, and the support surface 38 of the single effective cutting portion 32 is in clamping contact with the small counter-seat surface 72b.

[0133] It will be appreciated that in the embodiment of the invention in which the single effective cutting portion 32 is in clamping contact with the small secondary seating surface 72b, cutting forces associated with machining operations, e.g. broaching operations, in which the feed direction F is parallel to the tool axis AT, are advantageously absorbed within the insert holder 66 via the small secondary retaining portion 68b, thus providing good support for the single effective cutting portion 32.

[0134] For embodiments of the invention in which each bearing surface 38 includes a male or female type bearing element 50 , a corresponding small female or male bearing element 82 of the small secondary bearing surface 72 b may be in clamping contact with the support element 50 of the single active cutting portion 32 .

[0135] As shown in FIGS. 9 and 12, the small bearing elements 82 may be in the form of small bearing grooves 84 .

[0136] In the embodiment of the present invention in which each bearing surface 38 includes a male or female type bearing element 50, the corresponding large female or male bearing elements 86 of the large secondary bearing surface 72a may be in clamping contact with the support elements 50 of the two non-effective cutting portions 32.

[0137] As shown in FIG. 9, the two large bearing elements 86 may be in the form of two large bearing grooves 88 .

[0138] It will be appreciated that for embodiments of the present invention in which all male or female support elements 50 of the three support surfaces 38 are in clamping contact with corresponding small female or male bearing elements 82 and large female or male bearing elements 86 of the large and small secondary bearing surfaces 72a and 72b, respectively, the cutting tool 64 can advantageously provide a stable clamping configuration for machining operations, including machining operations in which cutting forces are directed transversely to the tool axis AT.

[0139] It should be appreciated that in some embodiments of the present invention, as shown in FIG. 12, the central boss 54 does not contact the seating surface 72 of the retaining portion.

[0140] Additionally, in some embodiments of the present invention, the outer peripheral side 26 of the insert does not contact any portion of the retaining portion 68 .

[0141] It should be appreciated that for embodiments of the present invention in which the outer peripheral side surface 26 of the insert does not contact any portion of the retaining portion 68 and the thread axis A3 is coaxial with the central axis A1, the clamping force associated with tightening the clamping screw 78 may be induced along the central axis A1 and the thread axis A3 without traversing the eccentric clamping component.

[0142] As shown in Figures 8-12, the large secondary retention portion 68a may have a front projection 90 that extends axially forward from the large secondary bearing surface 72a.

[0143] In some embodiments of the present invention, as shown in FIG. 12, the leading projection 90 may be located completely axially rearward of the single effective cutting edge 44 of the cutting insert along the tool axis AT.

[0144] In an embodiment of the present invention in which both the clamping screw 78 and the front protrusion 90 are located completely axially rearward of the single effective cutting edge 44 of the cutting insert along the tool axis AT, the single effective cutting edge 44 may constitute the axially forward most element of the cutting tool 64 along the tool axis AT.

[0145] For such embodiments, the cutting tool 64 may be advantageously configured to perform machining operations in confined spaces, such as broaching the internal keyway of a blind hole. It should also be appreciated that for embodiments in which the central axis A1 is parallel to the tool axis AT and therefore the first horizontal plane PH1 is orthogonal to the tool axis AT, the three cutting edges 44 of the cutting insert may simultaneously constitute the axially frontmost elements of the cutting tool 64 along the tool axis AT.

[0146] In some embodiments of the present invention, as shown in FIG. 12, the front projection 90 may include an upper coolant outlet passage 92 that extends along an upper coolant outlet axis A4 that is transverse to the tool axis AT.

[0147] Additionally, in some embodiments of the present invention, the upper coolant outlet passage 92 may be in communication with the coolant groove 62 associated with the single effective cutting portion 32 .

[0148] Additionally, in some embodiments of the present invention, the upper coolant exit passage 92 may be aligned with the coolant groove 62 associated with the single effective cutting portion 32 .

[0149] As shown in FIGS. 11 and 12, the upper coolant outlet axis A4 may be contained within an imaginary bisecting plane PB associated with the single effective cutting portion 32.

[0150] In some embodiments of the present invention, the front projection 90 may include an upper coolant supply passage 94 that communicates with and extends axially rearward from the upper coolant outlet passage 92 .

[0151] As shown in FIG. 11 , in the end view of the cutting tool 64, the center of an imaginary second circle CC2 having a second radius R2 that is 10 percent greater than the first radius R1, i.e., R2=R1×1.10, is offset from the center of the imaginary first circle CC1 in a direction away from the single effective cutting portion 32 by an offset distance DO.

[0152] In some embodiments of the present invention, the center of the imaginary second circle CC2 is contained within an imaginary bisection plane PB associated with the single effective cutting portion 32.

[0153] Also, in some embodiments of the present invention, the imaginary second circle CC2 may include a large secondary retaining portion 68a of the insert holder.

[0154] As shown in FIG. 11, no part of the large secondary retaining portion 68a of the insert holder extends outside the imaginary second circle CC2.

[0155] In some embodiments of the present invention, the imaginary second circle CC2 may include the central body portion 30 and two non-effective cutting portions 32 of the insert.

[0156] As shown in FIG. 11, the central body portion 30 and the two non-effective cutting portions 32 of the insert do not extend outside the imaginary second circle CC2.

[0157] In some embodiments of the present invention, the offset distance DO may be greater than 30 percent of the first radius R1, ie, DO>0.30×R1.

[0158] It should be appreciated that for embodiments of the present invention in which the offset distance DO is greater than 30 percent of the first radius R1 and the imaginary second circle CC2 includes the large secondary retaining portion 68a of the insert holder, the central body portion 30 of the insert, and the two non-effective cutting portions 32, the cutting tool 64 may be advantageously configured to perform a broaching operation with a cutting depth of 20 percent or more of the first radius R1. It should be appreciated that for such embodiments, the imaginary first vertical plane PV1 and the imaginary second vertical plane PV2 of the single effective cutting portion 32 do not intersect the small secondary retaining portion 68b of the insert holder.

[0159] As shown in FIG. 11 , in an end view of the cutting tool 64, an imaginary third circle CC3 having a third radius R3 that is 10 percent greater than the first radius R1, i.e., R3=R1×1.10, and a center that coincides with the central axis A1 of the cutting insert, may include the entire retaining portion 68.

[0160] In the end view of the cutting tool 64, in the case of an embodiment of the present invention where the virtual third circle CC3 includes the entire holding portion 68 and the holding length HL is three times as large as the first radius R1, it should be understood that the cutting tool 64 is advantageously small in the radial direction and can be appropriately configured to perform an inner machining operation of the workpiece W.

[0161] As shown in FIGS. 13 and 14, the workpiece W has a workpiece hole 95 having a hole radius RB, and the hole radius RB is relatively small compared to the size of the cutting insert 20.

[0162] In some embodiments of the present invention, the hole radius RB may be larger than the first radius R1 and smaller than the third radius R3, that is, R1 < RB < R3.

[0163] As shown in FIGS. 13 and 14, the cutting tool 64 can perform cutting of the inner passage 79 of the workpiece W having a constant passage width WCH equal to the cutting width WCT and the passage width DCH, and the passage width DCH is the maximum cutting depth DC due to the curvature of the workpiece hole 95 adjacent to the inner passage 79 MAX Slightly smaller.

[0164] As shown in FIGS. 8, 9, and 12, the small sub-holding portion 68b may include a bottom coolant outlet passage 96 extending along the bottom coolant outlet axis A5.

[0165] In some embodiments of the present invention, the bottom coolant outlet axis A5 is included in the virtual bisecting plane PB related to the single effective cutting portion 32 and can branch away from the tool axis AT in the forward direction DF.

[0166] Also, in some embodiments of the present invention, the bottom coolant outlet passage 96 may partially intersect the small sub-seat surface 72b.

[0167] Although the present invention has been described in some detail, it should be understood that various modifications and corrections can be made without departing from the spirit or scope of the present invention claimed below.

Claims

1. A flat-laying cutting insert (20) having an indexable cutting edge, the flat-laying cutting insert (20) comprising: opposed upper and lower surfaces (22, 24), a continuous peripheral side surface (26) extending between said upper and lower surfaces (22, 24), a central axis (A1) extending through said upper and lower surfaces (22, 24), said central axis (A1) defining an upward (DU)-downward (DD) direction; A central body portion (30); and three circumferentially spaced apart cutting portions (32) projecting radially from said central body portion (30); The central body portion (30) has a lower body surface (34) facing in the downward direction (DD) and three circumferentially spaced apart radially outwardly facing central side surfaces (36); Each of the cutting portions (32) has a support surface (38) facing in the downward direction (DD), a rake surface (40) facing in the upward direction (DU), a radially outward flank surface (42) extending between the rake surface (40) and the support surface (38), and a cutting edge (44) formed at an intersection between the rake surface (40) and the flank surface (42); Each of the cutting edges (44) has a first cutting end point (NE1) and a second cutting end point (NE2); Each of the cutting portions (32) is A virtual bisection plane (PB) including the central axis (A1) and bisecting the cutting edge (44) at a bisection cutting point (NBC); an imaginary first vertical plane (PV1) and an imaginary second vertical plane (PV2) that are parallel to the imaginary bisection plane (PB) and include the first cutting end point (NE1) and the second cutting end point (NE2) of each of the cutting portions (32), respectively; the imaginary first vertical plane (PV1) and the imaginary second vertical plane (PV2) do not intersect with the respective cutting portions (32) except for including the first cutting end point (NE1) and the second cutting end point (NE2); In a top view of the cutting insert (20), said imaginary first vertical plane (PV1) and said imaginary second vertical plane (PV2) intersect two different central side surfaces (36) of said central body portion (30) adjacent to respective cutting portions (32) at a first body side point (NB1) and a second body side point (NB2), respectively; the first body side point (NB1) and the second body side point (NB2) are located at a first cutting distance (DC1) and a second cutting distance (DC2) from the first cutting end point (NE1) and the second cutting end point (NE2), respectively; a first imaginary circle (CC1) having a first radius (R1) circumscribes the cutting insert (20); The indexable cutting insert (20), wherein each of the first cutting distance (DC1) and the second cutting distance (DC2) is greater than 25 percent of the first radius (R1).

2. In a top view of the cutting insert (20), The cutting insert (20) according to claim 1, wherein the three bisecting cutting points (NBC) are located inside the imaginary first circle (CC1).

3. In a top view of the cutting insert (20), 2. The cutting insert (20) of claim 1, wherein each of the imaginary bisector planes (PB) intersects one of the central side surfaces (36) at a third body side point (NB3) on an opposite side of the central axis (A1) from an associated cutting portion (32).

4. The three bisecting cutting points (NBC) define three corner points of an imaginary equilateral triangle (T1); The cutting insert (20) according to claim 3, wherein in a top view of the cutting insert (20), the three third body side points (NB3) are located outside the imaginary equilateral triangle (T1).

5. The cutting insert (20) of claim 1, wherein each said support surface (38) includes a male or female support element (50).

6. The cutting insert (20) according to claim 5, wherein each support element (50) is in the form of an elongated ridge (52) extending radially relative to the insert axis (A1).

7. Each of the cutting portions (32) has a cutting width (WCT) defined by the distance between the imaginary first vertical plane (PV1) and the imaginary second vertical plane (PV2); The cutting insert (20) of claim 1, wherein the width of cut (WCT) is greater than 40 percent of the first radius (R1).

8. The cutting insert (20) of claim 1, wherein each of the cutting portions (32) exhibits mirror symmetry about the imaginary bisector plane (PB).

9. The upper surface (22) includes three linearly extending coolant grooves (62); The cutting insert (20) of claim 1, wherein each said coolant groove (62) intersects two other said coolant grooves (62).

10. Each of the coolant grooves (62) extends along a groove axis (A2) transverse to the central axis (A1); The cutting insert (20) according to claim 9, wherein each of the coolant grooves (62) intersects one of the three cutting portions (32) at a first groove end region (NG1).

11. A through hole (28) coaxial with the central axis (A1) intersects the upper surface (22) and the lower surface (24), The cutting insert (20) of claim 9, wherein each said coolant groove (62) is interrupted by said through hole (28).

12. The three cutting edges (44) define a virtual first horizontal plane (PH1) perpendicular to the central axis (A1); The lower surface (24) defines an imaginary second horizontal plane (PH2) perpendicular to the central axis (A1); The through hole (28) includes a first hole portion (28a) and a second hole portion (28b) having different first hole diameter (DB1) and second hole diameter (DB2) in cross sections taken on an imaginary third horizontal plane (PH3) and an imaginary fourth horizontal plane (PH4) respectively perpendicular to the central axis (A1), The virtual third horizontal plane (PH3) is located axially above the virtual fourth horizontal plane (PH4), the first pore diameter (DB1) is at least 25 percent greater than the second pore diameter (DB2); The cutting insert (20) according to claim 11, wherein the imaginary third horizontal plane (PH3) and the imaginary fourth horizontal plane (PH4) are both located closer to the imaginary second horizontal plane (PH2) than the imaginary first horizontal plane (PH1).

13. The cutting insert (20) of claim 1, wherein the imaginary bisection plane (PB) is perpendicular to the cutting edge (44) at the bisection cutting point (NBC).

14. An insert holder (66); A cutting insert (20) according to claim 1 held within the insert holder (66); A cutting tool (64).

15. The insert holder (66) has an elongated retaining portion (68) extending in a forward direction (DF) along the tool axis (AT) away from a shank portion (70); The retaining portion (68) has a bearing surface (72) transverse to the tool axis (AT) at a front end (74) of the retaining portion (68); The retaining portion (68) has a large sub-retaining portion (68a) and a small sub-retaining portion (68b) extending in the longitudinal direction, the bearing surface (72) having a large minor bearing surface (72a) and a small minor bearing surface (72b) associated with the large minor retaining portion (68a) and the small minor retaining portion (68b), respectively; the cutting insert (20) is removably secured to the retaining portion (68) at one of three indexing positions by a fastener (76); in each said indexing position, exactly one of said cutting portions (32) is active and exactly two of said cutting portions (32) are inactive, the active cutting portion having an active cutting edge (44); The support surfaces (38) of the two non-effective cutting portions (32) are in clamping contact with the large counter bearing surface (72a), 15. The cutting tool (64) of claim 14, wherein the support surface (38) of the effective cutting portion (32) is in clamping contact with the small counter seating surface (70b).

16. Each of said support surfaces (38) includes a male or female support element (50); 16. The cutting tool (64) of claim 15, wherein a corresponding female or male small bearing element (82) of the small counter seating surface (72b) is in clamping contact with the support element (50) of the active cutting portion (32).

17. The cutting tool (64) of claim 15, wherein the outer circumferential side (26) does not contact any portion of the retaining portion (68).

18. A through hole (28) coaxial with the central axis (A1) intersects the upper surface (22) and the lower surface (24) of the insert; the fastener (76) being in the form of a clamping screw (78) passing through the through hole (28) of the cutting insert and engaging a threaded hole (80) in the large minor seating surface (72a); 16. The cutting tool (64) of claim 15, wherein the threaded hole (80) has a threaded axis (A3) coaxial with the central axis (A1).

19. The top surface (22) of the insert includes three linearly extending coolant grooves (62); Each of the coolant grooves (62) extends along a groove axis (A2) transverse to the central axis (A1) and interrupted by the through holes (28); 20. The cutting tool (64) of claim 18, wherein each said coolant groove (62) intersects one of three said cutting portions (32) at a first groove end region (NG1).

20. 20. The cutting tool (64) of claim 19, wherein the clamping screw (78) is located completely axially rearward of the three coolant grooves (62) along the tool axis (AT).

21. The large secondary retaining portion (68a) has a front projection (90) extending axially forward from the large secondary bearing surface (72a), The front projection (90) includes an upper coolant outlet passage (92) extending along an upper coolant outlet axis (A4) transverse to the tool axis (AT); 20. The cutting tool (64) of claim 19, wherein the upper coolant outlet passage (92) communicates with the coolant groove (62) associated with the effective cutting portion (32).

22. 22. The cutting tool (64) of claim 21, wherein the front projection (90) is located completely axially rearward of the effective cutting edge (44) of the effective cutting portion along the tool axis (AT).

23. FIG. 1 is an end view of the cutting tool (64); the center of an imaginary second circle (CC2) having a second radius (R2) that is 10 percent greater than the first radius (R1) is offset from the center of the imaginary first circle (CC1) by an offset distance (DO) in a direction away from the effective cutting portion (32); the imaginary second circle (CC2) includes a large secondary retaining portion (68a) of the insert holder; the imaginary second circle (CC2) further includes a central body portion (30) of the insert and two of the non-effective cutting portions (32); 16. The cutting tool (64) of claim 15, wherein the offset distance (DO) is greater than 30 percent of the first radius (R1).

24. FIG. 1 is an end view of the cutting tool (64); 16. The cutting tool (64) of claim 15, wherein an imaginary third circle (CC3) having a third radius (R3) that is 10 percent greater than the first radius (R1) and a center that coincides with a central axis (A1) of the cutting insert includes the entire retaining portion (68).

25. 16. The cutting tool (64) of claim 15, wherein the imaginary first vertical plane (PV1) and the imaginary second vertical plane (PV2) of the effective cutting portion (32) do not intersect a small secondary retaining portion (68b) of the insert holder.

Images