Reversible square shaped cutting insert and rotary cutting tool

Abstract

In a cutting tool rotatable about a tool axis, a reversible cutting insert is detachably secured in a tool body. The cutting insert has opposite top and bottom end surfaces interconnected by an outer peripheral surface, and a median plane therebetween. The outer peripheral surface includes four side surfaces alternating with four corner surfaces, the side and corner surfaces intersecting the top surface to form top primary cutting edges and top corner cutting edges, respectively. Each side surface has a median surface and a top primary relief surface. Each top primary relief surface forms an acute internal top primary relief angle with the median plane, and the median plane intersects the four median surfaces to define an imaginary median square. In a top end view of the cutting insert, the four top primary cutting edges define an imaginary top primary square that is rotationally offset from the imaginary median square.

Description

Technical Field

[0001] The present invention generally relates to cutting inserts and cutting tools for metal cutting processes, and more particularly to rotatable cutting tools with reversible cutting inserts for milling operations. Background Technology

[0002] Within the field of rotatable cutting tools used in milling operations, there are many examples of reversible cutting inserts that are detachably fixed to the cutting body. In some cases, the cutting insert is a square insert.

[0003] US7,604,441 discloses a fully indexable square cutting insert having four side surfaces connected to two end surfaces. At the intersection of each side surface and the end surface is a primary cutting edge, which extends downward toward a mid-plane along a first side surface from the insert corner. A finishing edge extends upward away from the mid-plane along the adjacent side surface from the same insert corner to rise above the adjacent surface of the associated end surface. The geometry of the cutting insert and the insert groove therein is such that the primary cutting edge has a positive axial angle (helix), while the insert has a total negative axial angle for providing axial clearance and a total negative radial angle for providing radial clearance.

[0004] US8,491,234 discloses a double-sided cutting insert with a plurality of indexable convex cutting edges. The cutting insert has a top face and a bottom face, each face having at least three convex cutting edges connected by at least three tool tip angles, at least three outer peripheral surfaces extending from each face into a virtual mid-plane; and a common lateral seat surface on each outer peripheral surface. Each convex cutting edge has at least a curved cutting edge region and also has a substantially straight main cutting edge region located between the curved cutting edge region and the tool tip angle. Each outer peripheral surface also has a principal plane facet associated with the substantially straight main cutting edge, and each facet is unidirectional in the same direction. Additionally, in various embodiments, the top and bottom faces of the cutting insert may be configured such that they are twisted or rotated relative to each other.

[0005] US8,641,331 discloses a milling insert with a square or triangular cutting surface, which is defined in a plan view by an outer peripheral cutting edge having a linear cutting edge and a curved cutting corner. Each cutting edge includes an inclined region sloping toward the cutting corner, the inclined region extending beyond the tangent point determined by the point where the linear cutting edge transitions to the curved cutting corner, wherein the adjacent cutting edge rises before the point determined by the angle bisector of the cutting corner, wherein the rising region extends to the maximum cutting edge value on the other side of the cutting corner on the adjacent cutting edge, which is linear in the plan view, from which the cutting edge continues, sloping again and downward, resulting in a rotationally symmetric form with cutting edges of the same shape.

[0006] US9,724,770 discloses a double-sided cutting insert for milling, having eight primary cutting edges and eight finishing edges. The cutting insert includes a top face, a bottom face, and four side faces. Each side face includes first and second sub-faces inclined relative to each other. The first sub-face has a primary cutting edge adjacent to the top face and a finishing edge adjacent to the bottom face. The second sub-face has a finishing edge adjacent to the top face and a primary cutting edge adjacent to the bottom face. The finishing edge of the second sub-face is inclined inwards relative to the cutting insert with respect to the primary cutting edge of the first sub-face. The finishing edge of the first sub-face is inclined inwards relative to the cutting insert with respect to the primary cutting edge of the second sub-face.

[0007] One object of the present invention is to provide an improved reversible cutting insert having four main cutting edges on each end surface.

[0008] Another object of the present invention is to provide an improved reversible cutting insert with a robust cutting edge.

[0009] Another object of the present invention is to provide an improved rotatable cutting tool in which the cutting insert is detachably fixed in the tool body with a high level of stability.

[0010] Another object of the present invention is to provide an improved rotatable cutting tool in which an increased number of cutting inserts are circumferentially spaced around the tool body.

[0011] Another object of the present invention is to provide an improved rotatable cutting tool capable of performing square shoulder milling operations. Summary of the Invention

[0012] According to one aspect of the present invention, a reversible cutting insert is provided, comprising:

[0013] The cutting insert consists of opposing top and bottom end surfaces interconnected by continuous outer peripheral surfaces. A mid-plane lies between the top and bottom end surfaces and intersects the outer peripheral surfaces to form the insert boundary line. The insert axis is perpendicular to the mid-plane, and the cutting insert is indexable around this mid-plane.

[0014] The outer peripheral surface includes four side surfaces, which alternate with the four corner surfaces along the circumference.

[0015] The side surface and corner surface intersect the top end surface at the top side edge and top corner edge, respectively. Each top side edge has a top main cutting edge, and each top corner edge has a top corner cutting edge.

[0016] Each side surface includes an intermediate surface and a top master clearance surface adjacent to the corresponding top master cutting edge.

[0017] in:

[0018] In the cross-sectional view taken along one of the top primary cutting edges, the corresponding top primary clearance surface forms an acute angle with the mid-plane, the inner top primary clearance angle, and

[0019] The midplane intersects with the four intermediate surfaces to define an imaginary midsquare, which has an imaginary inscribed midcircle with a mid-diameter and a center coinciding with the blade axis.

[0020] And in the top end view of the cutting blade:

[0021] Four top master cutting edges define an imaginary top master square, which has an imaginary inscribed top master circle having a top master diameter and a center coinciding with the blade axis.

[0022] The imaginary top main square is rotated and offset from the imaginary middle square around the blade axis.

[0023] According to another aspect of the present invention, a cutting tool rotatable about a tool axis in a rotational direction is provided, comprising:

[0024] The tool body extending along the front-to-back direction of the tool axis; and

[0025] At least one reversible cutting insert of the type described above, said reversible cutting insert being detachably fixed in an insert receiving groove of the tool body.

[0026] in:

[0027] One of the cutting edges at the tip angle of each cutting insert is operated, and

[0028] The one of the top primary cutting edges of each cutting insert that is adjacent to the top corner cutting edge of the operation is the top primary cutting edge of the operation. Attached Figure Description

[0029] For better understanding, the invention will now be described by way of example only with reference to the accompanying drawings, wherein the dashed lines denote the cutoff boundaries of partial views of the components, and wherein:

[0030] Figure 1 This is a perspective view of a cutting blade according to some embodiments of the present invention;

[0031] Figure 2 yes Figure 1 The end view of the cutting blade shown;

[0032] Figure 3 yes Figure 1 The side view of the cutting blade shown;

[0033] Figure 4 yes Figure 2The cross-sectional view of the cutting insert taken along line IV-IV is shown;

[0034] Figure 5 yes Figure 2 The diagram shows a partial cross-section taken along line VV of the cutting blade.

[0035] Figure 6 yes Figure 2 The diagram shows a partial cross-section taken along line VI-VI by the cutting tool.

[0036] Figure 7 This is a perspective view of a cutting tool according to some embodiments of the present invention;

[0037] Figure 8 yes Figure 7 The side view of the cutting tool shown;

[0038] Figure 9 yes Figure 8 First detailed view of the cutting tool shown;

[0039] Figure 10 yes Figure 8 The second detailed view of the cutting tool shown;

[0040] Figure 11 yes Figure 7 The end view of the cutting tool shown;

[0041] Figure 12 yes Figure 11 A detailed view of the cutting tool shown;

[0042] Figure 13 yes Figure 7 The first detailed view of the cutting tool shown shows the cutting insert and fastening screws removed;

[0043] Figure 14 yes Figure 8 The third detailed view of the cutting tool shown shows the cutting insert and fastening screws removed;

[0044] Figure 15 yes Figure 8 The cross-sectional view of the cutting tool along line XV-XV is shown; and

[0045] Figure 16 yes Figure 15 A detailed view of the cutting tool shown. Detailed Implementation

[0046] One aspect of the invention relates to a reversible cutting insert 20, such as Figures 1 to 3As shown, it has opposing top end surface 22 and bottom end surface 122 interconnected by a continuous outer peripheral surface 24, the outer peripheral surface 24 including four circumferentially alternating side surfaces 26 and four corner surfaces 28.

[0047] In some embodiments of the invention, the cutting blade 20 may preferably be manufactured by forming, pressing and sintering a cemented carbide such as tungsten carbide, and may be coated or uncoated.

[0048] like Figure 3 As shown, the cutting insert 20 has a midplane M located between the top and bottom end surfaces 22 and 122 and intersecting with the outer peripheral surface 24 to form the insert boundary line LB.

[0049] In some embodiments of the present invention, the mid-plane M may be located between the top end surface 22 and the bottom end surface 122.

[0050] Furthermore, in some embodiments of the invention, the cutting blade 20 may be configured such that, in the end view, as... Figure 2 As shown, the cutting insert 20 does not extend beyond the insert boundary line LB.

[0051] like Figures 1 to 3 As shown, the cutting insert 20 has a cutting axis AI perpendicular to the mid-plane M, and the cutting insert 20 can be rotated around this axis.

[0052] In some embodiments of the present invention, the through hole 30, which is coaxial with the blade axis AI, may intersect with the top end surface 22 and the bottom end surface 122.

[0053] Furthermore, in some embodiments of the present invention, the cutting blade 20 can be manufactured by directly pressing along the blade axis AI.

[0054] Furthermore, in some embodiments of the invention, the cutting blade 20 may be pressed into its final shape, and the outer peripheral surface 24 may be unground.

[0055] like Figures 1 to 3 As shown, the side surface 26 and the corner surface 28 intersect the top end surface 22 at the top side edge and the top corner edge 32, 34, respectively. Each top side edge 32 has a top main cutting edge 36, and each top corner edge 34 has a top corner cutting edge 38.

[0056] In some embodiments of the invention, each top corner cutting edge 38 may be curved.

[0057] Moreover, in some embodiments of the invention, each top main cutting edge 36 may be tangential to one of the adjacent top corner cutting edges 38.

[0058] like Figure 3 As shown, the four top main cutting edges 36 can be completely contained in the top horizontal plane PH perpendicular to the blade axis AI.

[0059] In some embodiments of the invention, the four top corner cutting edges 38 may be completely contained within the top horizontal plane PH.

[0060] like Figures 1 to 4 As shown, the top end surface 22 may have a top central surface 40, and the top central surface 40 may be located between the mid-plane M and the top horizontal plane PH.

[0061] In some embodiments of the invention, the top central surface 40 may be perpendicular to the blade axis AI.

[0062] Furthermore, in some embodiments of the present invention, the through hole 30 may intersect with the top central surface 40.

[0063] like Figure 1 and Figure 2 As shown, the top end surface 22 may include a forward-tilting surface 42 extending adjacent to the top side edge and top corner edges 32, 34.

[0064] In some embodiments of the invention, the forward tilt surface 42 may surround the top central surface 40.

[0065] like Figures 1 to 3 As shown, each top side edge 32 may include a top secondary cutting edge 44.

[0066] In some embodiments of the invention, the four top secondary cutting edges 44 may be completely contained within the top horizontal plane PH.

[0067] Moreover, in some embodiments of the present invention, the top side edge and the top corner edge 32, 34 can be completely contained within the top horizontal plane PH.

[0068] like Figure 1 and 3 As shown, each side surface 26 includes an intermediate surface 46, and each side surface 26 also includes a top main clearance surface 48 adjacent to the corresponding top main cutting edge 36.

[0069] In some embodiments of the invention, each intermediate surface 46 may be perpendicular to the midplane M.

[0070] Furthermore, in some embodiments of the present invention, each top primary back clearance surface 48 may intersect with the top end surface 22 to form a corresponding top primary cutting edge 36.

[0071] Furthermore, in some embodiments of the invention, each top main rear gap surface 48 may not intersect with the midplane M.

[0072] like Figure 4 As shown, in a cross-sectional view taken along one of the top main cutting edges 36, the corresponding top main back clearance surface 48 forms an acute angle with the mid-plane M, with an internal top main back clearance angle β1.

[0073] Similarly, as Figure 4 As shown, the cross-sectional view taken along one of the top main cutting edges 36 may include the blade axis AI.

[0074] It should be understood that the terms “internal angle” and “external angle” as used throughout the specification and claims refer to the angle between two linear features, measured internally and externally, of a member on which at least one linear feature is formed, respectively.

[0075] It should also be understood that each top primary clearance surface 48, also known as the “reverse” clearance surface, typically extends outward from its corresponding top primary cutting edge 36 toward the midplane M (i.e., in a direction away from the insert axis AI) so that each top primary cutting edge 36 is advantageously supported and advantageously robust.

[0076] In some embodiments of the invention, each top main rear gap surface 48 may be planar.

[0077] Furthermore, in some embodiments of the present invention, the top main back gap angle β1 can have a minimum value of 75 degrees and a maximum value of 85 degrees, i.e., 75°≤β1≤85°.

[0078] For embodiments of the invention where the top primary back clearance angle β1 associated with each top primary back clearance surface 48 has a minimum of 75 degrees and a maximum of 85 degrees, it should be understood that each top primary cutting edge 36 is advantageously supported and advantageously robust.

[0079] like Figure 4 As shown, in a cross-sectional view taken along one of the top main cutting edges 36, the corresponding top main back clearance surface 48 can form an acute-angled internal top main forward tilt angle σ1 with the forward tilt angle surface 42.

[0080] In some embodiments of the present invention, the top principal tilt angle σ1 can have a minimum value of 65 degrees and a maximum value of 75 degrees, i.e., 65°≤σ1≤75°.

[0081] like Figure 3 As shown in the side view of the cutting insert 20, the top primary clearance surface 48 (visible in this view) may have a variable top primary clearance width WJ parallel to the insert axis AI, and the top primary clearance width WJ may be increased in the transverse direction SD parallel to the midplane M.

[0082] In some embodiments of the invention, the top master clearance width WJ can be continuously increased in the transverse direction SD along the entire length of the corresponding top master cutting edge 36.

[0083] like Figure 3 As shown, in the side view of the cutting insert 20, the transverse direction SD can be from the top primary cutting edge 36 to the top secondary cutting edge 44 on the same top side edge 32.

[0084] Moreover, such as Figure 3 As shown, each side surface 26 may include a top secondary clearance surface 50 adjacent to the corresponding top secondary cutting edge 44.

[0085] In some embodiments of the invention, each top secondary back clearance surface 50 may intersect with the top end surface 22 to form a corresponding top secondary cutting edge 44.

[0086] like Figure 5 As shown, in a cross-sectional view taken along one of the top secondary cutting edges 44, the corresponding top secondary clearance surface 50 may be perpendicular to the mid-plane M.

[0087] In some embodiments of the invention, each top secondary back clearance surface 50 may be coplanar with its associated intermediate surface 46.

[0088] like Figure 2 As shown, the midplane M intersects with four intermediate surfaces 46 to define an imaginary square SM of an imaginary inscribed midcircle CM, which has a mid-diameter DM.

[0089] In addition, such as Figure 2 As shown, it should be understood that the center of the imaginary inscribed circle CM coincides with the blade axis AI.

[0090] Furthermore, such as Figure 2 As shown, the imaginary square SM can be divided into four identical quadrants Q1, Q2, Q3, Q4 by first and second vertical planes PV1 and PV2 that contain the blade axis AI and intersect the four side surfaces 26 and are perpendicular to each other.

[0091] In some embodiments of the invention, each top primary cutting edge 36 may be located in or span two of the four quadrants Q1, Q2, Q3, Q4.

[0092] Moreover, in some embodiments of the present invention, each top main back gap surface 48 may be located in or span two of the four quadrants Q1, Q2, Q3, Q4.

[0093] Furthermore, in some embodiments of the present invention, each top corner cutting edge 38 may be located in only one of the four quadrants Q1, Q2, Q3, Q4.

[0094] Furthermore, in some embodiments of the present invention, each top secondary cutting edge 44 may be located in only one of the four quadrants Q1, Q2, Q3, Q4.

[0095] like Figure 2 As shown, in the top end view of the cutting insert 20, four top master cutting edges 36 define an imaginary top master square SJ with an imaginary inscribed top master circle CJ having a top master diameter DJ.

[0096] In addition, such as Figure 2 As shown, it should be understood that the imaginary inscribed top principal circle CJ has a center that coincides with the blade axis AI.

[0097] In addition, such as Figure 2 As shown, in the top end view of the cutting insert 20, the imaginary top master square SJ is rotated and offset from the imaginary middle square SM around the insert axis AI. In this application, "rotational offset" means that both squares SJ and SM are centered on the indexing axis AI, but the side of one square is not parallel to the side of the other square.

[0098] In some embodiments of the present invention, the middle diameter DM may be larger than the top main diameter DJ.

[0099] Furthermore, in some embodiments of the present invention, the maximum top main rear clearance width WJ of each top main rear clearance surface 48 MAX It can be greater than 20% of the top main diameter DJ, i.e., WJ MAX >0.20*DJ.

[0100] Furthermore, in some embodiments of the present invention, the maximum top main rear gap width WJ MAX It can be greater than 20% of the median diameter DM, i.e., WJ MAX >0.20*DM.

[0101] For each of the top primary clearance surfaces 48, the maximum top primary clearance width WJ MAX In embodiments of the invention that are greater than 20 percent of the top master diameter DJ, it should be understood that each top master cutting edge 36 is advantageously robust.

[0102] like Figure 1 , 2 As shown in Figures 4 and 5, the through hole 30 has an axial length EA from the top end surface 22 to the bottom end surface 122.

[0103] In some embodiments of the present invention, the axial range EA of the hole can be greater than 40% of the top main diameter DJ, i.e., EA>0.40*DJ.

[0104] Furthermore, in some embodiments of the present invention, the axial range EA of the hole can be greater than 40% of the middle diameter DM, i.e., EA>0.40*DM.

[0105] like Figure 2 As shown, four top sub-cutting edges 44 can define an imaginary top sub-square SN with an imaginary inscribed top sub-circle CN and a top sub-diameter DN.

[0106] like Figure 2 As shown, in the top end view of the cutting blade 20, the imaginary top sub-square SN can coincide with the imaginary middle square SM.

[0107] In embodiments of the invention where the imaginary top sub-square SN coincides with the imaginary middle square SM, it should be understood that the middle diameter DM can be equal to the top sub-diameter DN.

[0108] As in Figure 2 In the best view from the top end view, the imaginary top master square SJ is nested within the imaginary top sub-square SN. Therefore, in the end view of the blade 20, the top master cutting edge 36 of a given top side edge 32 is recessed relative to the top sub-cutting edge 44 of the same top side edge 32. Furthermore, in some embodiments, in the top end view, the top master cutting edge 36 is longer than the top sub-cutting edge 44.

[0109] like Figures 1 to 3 As shown, each top corner cutting edge 36 has first and second corner endpoints NC1, NC2.

[0110] In some embodiments of the invention, each first corner endpoint NC1 may coincide with the first secondary endpoint NN1 of one of the top secondary cutting edges 44, and each second corner endpoint NC2 may coincide with the first primary endpoint NJ1 of one of the top primary cutting edges 36.

[0111] like Figure 2 As shown, in the top end view of the cutting insert 20, the top primary cutting edge 36 and the top secondary cutting edge 44 associated with each top corner cutting edge 38 can form an acute-angled inner top corner angle α1.

[0112] In some embodiments of the present invention, the top corner angle α1 can have a value greater than 80 degrees, that is, α1 > 80°.

[0113] like Figures 1 to 3 As shown, each side surface 26 may have a top undercut 52 formed relative to the undercut direction DU parallel to the relevant side of the imaginary square SM.

[0114] It should be understood that the term “undercut” as used throughout the specification and claims refers to a recess, wherein a straight line extending from a given sub-surface of the recess along a particular undercut direction intersects another sub-surface of the same recess.

[0115] In some embodiments of the invention, each top undercut 52 may be recessed relative to the associated top sub-back gap surface 50.

[0116] Furthermore, in some embodiments of the invention, each top main rear clearance surface 48 may be disposed in the top undercut 52 of the corresponding side surface 26.

[0117] like Figures 1 to 3 As shown, each top undercut 52 may include a top engagement surface 54. The top engagement surface 54 may connect the top primary rear clearance surface 48 to the top secondary rear clearance surface 50.

[0118] In some embodiments of the invention, each top engagement surface 54 may intersect with the top end surface 22 at the top engagement edge 56.

[0119] Furthermore, in some embodiments of the invention, each top engagement edge 56 may extend between the top primary cutting edge 36 and the top secondary cutting edge 44 associated with the same top side edge 32.

[0120] Furthermore, in some embodiments of the invention, each top joining edge 56 may be a non-cut edge.

[0121] like Figure 5 and 6 As shown, the first and second imaginary straight lines L1 and L2 extend perpendicularly to the midplane M and intersect one of the first and second corner endpoints NC1 and NC2 of the top corner cutting edge, respectively.

[0122] In some embodiments of the present invention, the first imaginary straight line L1 may intersect with the blade boundary line LB.

[0123] Furthermore, in some embodiments of the present invention, the second imaginary straight line L2 may pass through the midplane M within the blade boundary line LB.

[0124] like Figures 1 to 3 As shown, each corner surface 28 may include a top corner back clearance surface 58 adjacent to the corresponding top corner cutting edge 38.

[0125] For embodiments of the invention where the second imaginary straight line L2 passes through the mid-plane M within the blade boundary line LB, it should be understood that each top corner clearance surface 58 may be partially conical and gradually decrease in size in the direction away from the mid-plane M, such that each top secondary cutting edge 44 is advantageously supported and is advantageously robust and durable.

[0126] In some embodiments of the invention, a third imaginary line L3 extends perpendicularly to the midplane M and intersects one of the top main cutting edges 36 at any point along its length. The third imaginary line L3 may pass through the midplane M within the blade boundary line LB.

[0127] In some embodiments, the top end surface and the bottom end surface 22, 122 may be the same.

[0128] For embodiments of the invention where the top and bottom end surfaces 22 and 122 are identical, it should be understood that throughout the drawings, description and claims, all features associated with the bottom end surface 122 have been assigned the same reference numerals as the corresponding features associated with the top end surface 22, except that they will be preceded by an additional "hundreds" digit.

[0129] In some embodiments of the invention, the cutting blade 20 may exhibit double rotational symmetry about a first axis A1 formed at the intersection of the first vertical plane PV1 and the mid-plane M.

[0130] Furthermore, in some embodiments of the invention, the cutting blade 20 may exhibit double rotational symmetry about a second axis A2 formed at the intersection of the second vertical plane PV2 and the mid-plane M.

[0131] Furthermore, in some embodiments of the present invention, the cutting blade 20 may exhibit fourfold rotational symmetry about the blade axis AI.

[0132] like Figures 7 to 12 As shown, another aspect of the invention relates to a cutting tool 60 that is rotatable about a tool axis AT in the rotational direction RD. The cutting tool 60 has a tool body 62 extending along the tool axis AT in the front-rear directions DF, DR, and at least one reversible cutting insert 20 removably fixed in an insert receiving groove 64 of the tool body 62.

[0133] In some embodiments of the present invention, the cutting tool 60 may have N cutting blades 20, which are removably fixed in N blade receiving slots 64 spaced circumferentially around the tool body 62, where N is a positive integer greater than one.

[0134] It should be understood that, throughout the specification and claims, since N is a specific integer greater than one, the number of cutting blades 20 is equal to the number of blade receiving slots 64.

[0135] like Figure 7 and 8 As shown, the tool body 62 may have a front body end 66 and a rear body end 68 that are axially opposite.

[0136] In some embodiments of the invention, each blade receiving slot 64 may be opened outward to the front body end 66.

[0137] Furthermore, in some embodiments of the present invention, the cutting tool 60 may exhibit N-fold rotational symmetry about the tool axis AT.

[0138] like Figure 13 and 14 As shown, each blade receiving slot 64 may have a seat surface 70, which has axial and radial support walls 72, 74 transverse to the seat surface.

[0139] In some embodiments of the present invention, the seat surface 70 may face the rotation direction RD.

[0140] Furthermore, in some embodiments of the present invention, the seat surface 70 may be planar.

[0141] Furthermore, in some embodiments of the present invention, the axial support wall 72 may face axially forward, and the radial support wall 74 may face radially outward.

[0142] With at least one reversible cutting blade 20 in its fixed state within its respective blade receiving groove 64:

[0143] The bottom end surface 122 can be clamped and contacted with the seat surface 70.

[0144] The first of the four side surfaces, 26a, can clamp into contact with the axial support wall 72, and

[0145] The second of the four side surfaces, 26b, can be clamped into contact with the radial support wall 74.

[0146] In an embodiment of the invention where the top end surface 22 and the bottom end surface 122 are the same, the bottom end surface 122 may have a bottom central surface 140, and the bottom central surface 140 may be in clamping contact with the seat surface 70.

[0147] like Figure 7 and 13 As shown, the fastening screw 76 extends through the through hole 30 and is threaded into the screw hole 78 in the seat surface 70 having the hole axis AB.

[0148] In some embodiments of the present invention, the blade axis AI may be offset from the hole axis AB.

[0149] For embodiments of the invention where the blade axis AI deviates from the hole axis AB, it should be understood that when tightening the fastening screw 76, clamping contact is ensured between the first and second side surfaces 26a, 26b of the cutting blade and the axial and radial support walls 72, 74 of the blade receiving groove, respectively.

[0150] like Figure 15 and 16As shown in the cross-sectional view taken from the first tool plane PT1, which is perpendicular to the tool axis AT and intersects with at least one seat surface 70, the second tool plane PT2 includes the tool axis AT and the radial outermost seat point NO of one of the seat surfaces 70.

[0151] In some embodiments of the present invention, the seat surface 70 may form an acute internal radial groove angle τ1 with the second tool plane PT2.

[0152] Furthermore, in some embodiments of the present invention, it should be understood that, relative to the tool axis AT, the radial outermost seat point NO is not only the radial outermost point of the seat surface 70 in the cross-sectional view taken in the first tool plane PT1, but also the absolute radial outermost point of the seat surface 70.

[0153] For an embodiment of the invention in which each seat surface 70 faces the rotation direction RD and the radial slot angle τ1 is an internal angle rather than an external angle, it should be understood that a reduction in the circumferential spacing between adjacent blade receiving slots 64 can be achieved while successfully orienting each fastening screw 76 and threading it through the through hole 30 of the corresponding cutting blade into the screw hole 78 of the corresponding blade receiving slot without being obstructed by the adjacent rotational guide portion of the tool body 62.

[0154] In some embodiments of the present invention, the radial slot angle τ1 may have a value greater than 3 degrees, i.e., τ1>3°.

[0155] like Figure 15 As shown, the N radially outermost seat points NO of the N seat surfaces 70 define the area with the maximum seat diameter DS. MAX The hypothetical circular CS.

[0156] In some embodiments of the present invention, it should be understood that the imaginary race CS may have a center that coincides with the tool axis AT.

[0157] In some embodiments of the invention, with at least one reversible cutting blade 20 in a fixed state, the bottom end surface 122 of each cutting blade 20 can contact the corresponding radial outermost seat point NO.

[0158] Furthermore, in some embodiments of the invention, with at least one reversible cutting blade 20 in a fixed state, the bottom central surface 140 of each cutting blade 20 can contact the corresponding radial outermost seat point NO.

[0159] like Figure 9 and 16 As shown, the top main rear clearance surface 48 of the first side surface 26a can be clamped in contact with the axial support wall 72, and the middle surface 46 of the second side surface 26b can be clamped in contact with the radial support wall 74.

[0160] like Figure 14 As shown, the axial support wall 72 can form an acute external axial support angle φ1 with the seat surface 70.

[0161] In embodiments of the present invention in which the axial support wall 72 forms an acute external axial support angle φ1 with the seat surface 70, it should be understood that the axial support wall 72 is configured to provide a "dovetail" clamping.

[0162] In some embodiments of the present invention, the acute axial support angle φ1 may have a value less than or equal to 85 degrees, i.e., φ1≤85°.

[0163] Furthermore, in some embodiments of the present invention, the acute axial support angle φ1 may correspond to the top main back clearance angle β1.

[0164] In an embodiment of the present invention where the acute axial support angle φ1 corresponds to the top main rear clearance angle β1, it should be understood that a dovetail-type clamping contact can occur between the axial support wall 72 and the top main rear clearance surface 48 of the first side surface 26a.

[0165] Furthermore, in embodiments of the invention where a dovetail-shaped clamping contact occurs between the axial support wall 72 and the top main clearance surface 48 of the first side surface 26a, it should be understood that the cutting blade 20 can be detachably fixed to its respective blade receiving groove 64 with a high level of stability.

[0166] like Figure 16 As shown, the radial support wall 74 can be perpendicular to the seat surface 70.

[0167] In some embodiments of the present invention, the radial support wall 74 may include two radial support sub-walls 74a, 74b that are axially spaced apart from the tool axis AT.

[0168] like Figures 7 to 12 As shown, one of the top corner cutting edges 38 of each cutting insert 20 is operational, and one of the top main cutting edges 36 of each cutting insert 20 adjacent to the operational top corner cutting edge 38 is operational.

[0169] It should be understood that, throughout the specification and claims, the cutting insert 20 may have four indexing positions on the top end surface 22, and at each indexing position, a different one of the different top angle cutting edges 38 is operational, and a different one of the top main cutting edges 36 is operational.

[0170] It should also be understood that the cutting blade 20 is reversible and can also be described as “double-sided” or “double-ended”, such that in its fixed state in its respective blade receiving groove 64, the top end surface 22 can contact the seat surface 70, and for embodiments in which the top and bottom end surfaces 22, 122 are identical, the bottom end surface 122 may have four bottom main cutting edges 136, one of which is operative, and four bottom corner cutting edges 138, one of which is operative.

[0171] like Figure 9 and 10 As shown, the top primary clearance width WJ of the top primary clearance surface 48 associated with the operating top primary cutting edge 36 can be increased in the transverse direction SD away from the operating top corner cutting edge 38.

[0172] like Figure 9 As shown, the top primary cutting edge 36 of each cutting insert 20 may have a negative axial forward tilt angle λ1.

[0173] In some embodiments of the present invention, the negative axis forward tilt angle λ1 may have a value greater than 3 degrees.

[0174] Furthermore, in some embodiments of the invention, one of the adjacent operating top corner cutting edges 38 in the top secondary cutting edge 44 of each cutting insert 20 may be operational.

[0175] like Figure 11 and 12 As shown, the top secondary cutting edge 44 of each cutting insert 20 may have a negative radial tilt angle δ1.

[0176] In some embodiments of the present invention, the negative radial pitch angle δ1 may be greater than the radial slot angle τ1, and it should be understood that increasing the radial slot angle τ1 results in an increased negative radial pitch angle δ1.

[0177] Furthermore, in some embodiments of the present invention, the negative radial tilt angle δ1 may have a value greater than 10 degrees.

[0178] For embodiments of the invention where the radial pitch angle δ1 is negative, particularly for embodiments where the negative radial pitch angle δ1 has a value greater than 10 degrees, it should be understood that the cutting load on the top secondary cutting edge 44 can be uniformly distributed along it, thereby reducing the risk of edge breakage.

[0179] In some embodiments of the invention, the radial clearance angle (not shown) between the top primary clearance surface 48 of each cutting insert 20 and the workpiece 80 can have a value between 5 and 10 degrees.

[0180] Although it should be from Figure 15 and 16In general understanding, increasing the radial slot angle τ1 will result in an increased radial clearance angle. Since the top main back clearance surface 48 is configured as an "inverted" back clearance surface, a higher radial slot angle τ1 value can be achieved while maintaining the optimal value of the radial clearance angle, for example, between 5 and 10 degrees.

[0181] like Figure 16 As shown, the cutting force FC acting on the top main cutting edge 36 of each cutting insert 20 is directed in the tangential force direction FD, and can form an acute radial inclination angle ε1 between the tangential force direction FD and the seat surface 70.

[0182] In some embodiments of the present invention, the radial tilt angle ε1 may have a value between 70 degrees and 80 degrees, i.e., 70°<ε1<80°.

[0183] from Figure 15 and 16 It should be generally understood that increasing the radial flute angle τ1 leads to a decrease in the radial tilt angle ε1, which is typically associated with reduced clamping stability. However, due to the dovetail clamping contact between the axial support wall 72 and the top primary clearance surface 48 of the first side surface 26a of the corresponding cutting insert 20, a higher radial flute angle τ1 can be achieved while maintaining a high level of clamping stability.

[0184] like Figure 11 and 15 As shown, the top primary cutting edge 36 of each cutting insert 20 can limit the tool cutting diameter DTC.

[0185] It is known in the art that the number N of cutting inserts 20 circumferentially spaced around the tool body 62 and the number N of insert receiving slots 64 can be substantially proportional to the tool cutting diameter DTC. In embodiments of the invention where the radial slot angle τ1 is an internal angle opposite to the external angle, a reduced circumferential spacing between adjacent insert receiving slots 64 can be achieved while successfully orienting each fastening screw 76 and threading it through the through-hole 30 of the corresponding cutting insert into the threaded hole 78 of the corresponding insert receiving slot without obstruction by adjacent rotational guide portions of the tool body 62, such that for a given tool cutting diameter DTC, the number N of insert receiving slots 64 and the number N of cutting inserts 20 can be increased.

[0186] In some embodiments of the present invention, N multiplied by the slot spacing coefficient FP can be equal to the tool cutting diameter DTC, i.e., N*FP=DTC, and the slot spacing coefficient FP can be equal to or less than 8.5, i.e., FP<8.5.

[0187] Furthermore, in some embodiments of the present invention, the slot spacing coefficient FP can be equal to or less than 8, i.e., FP<8.

[0188] It should be understood that throughout the specification and claims, the slot spacing factor FP is in millimeters, and the ratio of N to the tool cutting diameter DTC applies when the tool cutting diameter DTC is measured in millimeters.

[0189] In embodiments of the present invention, N multiplied by the slot spacing coefficient FP equals the tool cutting diameter DTC, i.e., N*FP=DTC, as shown below. Figure 11 As shown, it should be understood that the angular spacing range ES (in degrees) between circumferentially adjacent blade receiving slots 64 is equal to 360° / (DTC / FP), that is, ES = 360° / (DTC / FP).

[0190] like Figure 15 and 16 As shown, the cutting diameter DTC of the tool and the maximum seat diameter DS MAX Half of the difference between them defines the first radial range ER1.

[0191] In some embodiments of the present invention, the first radial range ER1 may be less than 25 percent of the top main diameter DJ, i.e., ER1 < 0.25 * DJ.

[0192] For embodiments of the invention in which the first radial range ER1 is less than 25 percent of the top main diameter DJ, it should be understood that the radial overturning moment (not shown) of the cutting force FC about its respective radial outermost seat point NO is advantageously reduced.

[0193] like Figure 16 As shown, the imaginary base circle CS intersects the top end surface 22 of each cutting blade 20 at the top intersection point NI.

[0194] In some embodiments of the present invention, the top intersection point NI of the same cutting insert 20 and the operating top angle cutting edge 38 can be located in the same one of the four quadrants Q1, Q2, Q3, Q4 of the insert, so the operating top angle cutting edge 38 can be well supported by the seat surface 70.

[0195] like Figure 8 and 10 As shown, the cutting tool 60 has a cutting depth DC measured parallel to the tool axis AT.

[0196] In some embodiments of the present invention, the maximum cutting depth DC of the cutting tool 60 in the forward direction DF along the tool axis AT is... MAX It can be greater than half the top master diameter DJ of each blade, i.e., DC. MAX DJ / 2.

[0197] Furthermore, in some embodiments of the present invention, the maximum cutting depth DC MAXIt can be greater than half the median diameter DM of each blade, i.e., DC. MAX >DM / 2.

[0198] For embodiments in which the top primary cutting edge 36 and top secondary cutting edge 44 associated with each top corner cutting edge 38 form an acute-angled inner top corner angle α1 and / or each side surface 26 includes a top undercut 52 relative to the undercut direction DU, it should be understood that a portion of the cutting insert 20 located axially rear of the operating top primary cutting edge 36 relative to the tool axis AT can extend radially beyond the tool cutting diameter DTC, thereby increasing the maximum depth of cut DC. MAX Limit the value to less than the top master diameter DJ of the blade.

[0199] Despite the maximum cutting depth DC MAX It may be limited to a value smaller than the top master diameter DJ of the blade, such as Figure 8 and 10 As shown, the cutting tool 60 can be used for milling operations, whereby each cutting insert 20 is oriented in its respective insert receiving groove 64 to cut a precise ninety-degree or square shoulder in the workpiece 80.

[0200] like Figures 10 to 12 As shown, each cutting insert 20 has an axial foremost cutting point NF, and the N axial foremost cutting points NF of the N cutting inserts 20 define an imaginary end face circle CF with an end face cutting diameter DFC.

[0201] In some embodiments of the present invention, it should be understood that the imaginary end face circle CF may have a center that coincides with the tool axis AT.

[0202] like Figure 12 As shown, half of the difference between the tool cutting diameter DTC and the end face cutting diameter DFC defines the second radial range ER2.

[0203] In some embodiments of the present invention, the second radial range ER2 may be less than 20 percent of the top main diameter DJ, i.e., ER2 < 0.20 * DJ.

[0204] In an embodiment of the invention where the cutting tool 60 has N cutting inserts 20 and N insert receiving slots 64, it should be understood that multiple axial foremost insert points NF may be contained in a third tool plane PT3 (also referred to as "face milling plane PT3") perpendicular to the tool axis AT.

[0205] In some embodiments of the invention, each axially foremost blade point NF may be included in the top angle cutting edge 38 of its associated operation.

[0206] Furthermore, in some embodiments of the invention, the foremost cutting edge point NF of each axial direction may coincide with the first corner endpoint NC1 of the top corner cutting edge 38 of its associated operation, and the top secondary cutting edge 44 of the operation may be substantially parallel to the third tool plane PT3.

[0207] For embodiments of the invention where the end face cutting diameter DFC is relatively large and the second radial range ER2 is less than 20 percent of the top main diameter DJ, it should be understood that the cutting tool 60 can be advantageously used for end face milling operations to maximize the horizontal machining range of the workpiece 80.

[0208] Furthermore, in embodiments of the invention where the cutting tool 60 is used for milling operations such as face milling, it should be understood that the cutting path length of each cutting insert 20 in the workpiece 80, for each rotation of the cutting tool 60, can be proportional to the tool cutting diameter DTC, and the thermal load generated by the cutting action of each cutting insert 20 can increase with the increase of the tool cutting diameter DTC.

[0209] Although it is known in the art that increasing the size and mass of the cutting inserts can help dissipate the heat load generated by their cutting action, and the median diameter DM of each cutting insert 20 may be related to the tool cutting diameter DTC, for embodiments of the invention in which the cutting inserts 20 are robustly configured with an “inverted” clearance surface adjacent to the top primary cutting edge 36, the size of the cutting inserts 20 relative to the tool cutting diameter DTC can be reduced.

[0210] In some embodiments of the present invention, the medium diameter DM multiplied by the blade size factor FI can be equal to the tool cutting diameter DTC, i.e., DM*FI=DTC, and the blade size factor FI can be greater than 12, i.e. FI>12.

[0211] For embodiments of the invention where the insert size factor FI is greater than 12, it should be understood that reducing the amount of carbide required to produce smaller cutting inserts 20 results in lower manufacturing costs. Furthermore, smaller cutting inserts 20 help to reduce the circumferential spacing between adjacent insert receiving slots 64.

[0212] This invention considers rotary cutting tools with a cutting diameter DTC of less than 100 mm and an insert size factor FI greater than 12. While the aforementioned insert size factor FI greater than 12 can theoretically be applied to cutting tools 60 with a cutting diameter DTC of less than 100 mm, it is generally accepted that practical factors related to the use of secondary diameter fastening screws 76 to detachably secure the smaller cutting insert 20 to the correspondingly sized insert receiving groove 64 may pose challenges in such a configuration.

[0213] It should be understood that throughout the specification and claims, the insert size factor FI has no unit, and the ratio of the insert diameter DM to the tool cutting diameter DTC applies when both the insert diameter DM and the tool cutting diameter DTC are measured in the same unit (e.g., millimeters).

[0214] Although the invention has been described in particular to a certain extent, it should be understood that various changes and modifications may be made without departing from the spirit or scope of the invention as claimed below.

Claims

1. A reversible cutting insert (20), comprising: The opposing top and bottom end surfaces (22, 122) are interconnected by continuous outer peripheral surfaces (24). A mid-plane (M) lies between the top and bottom end surfaces (22, 122) and intersects the outer peripheral surface (24) to form the blade boundary line (LB). The blade axis (AI) is perpendicular to the mid-plane (M). The cutting blade (20) is indexable about the blade axis. The outer peripheral surface (24) includes four side surfaces (26) that alternate circumferentially with the four corner surfaces (28). The side surfaces and corner surfaces (26, 28) intersect the top end surface (22) at the top side edge and the top corner edge (32, 34), respectively. Each top side edge (32) has a top main cutting edge (36), and each top corner edge (34) has a top corner cutting edge (38). Each side surface (26) includes an intermediate surface (46) and a top main clearance surface (48) adjacent to the corresponding top main cutting edge (36). in: In a cross-sectional view taken along one of the top primary cutting edges (36), the corresponding top primary clearance surface (48) forms an acute-angled internal top primary clearance angle (β1) with the mid-plane (M), and The midplane (M) intersects with four intermediate surfaces (46) to define an imaginary central square (SM) having an imaginary inscribed midcircle (CM) having a mid-diameter (DM) and a center coinciding with the blade axis (AI). In the top end view of the cutting blade (20): Four top master cutting edges (36) define an imaginary top master square (SJ) having an imaginary inscribed top master circle (CJ) having a top master diameter (DJ) and a center coinciding with the insert axis (AI), and The imaginary top master square (SJ) is rotated and offset from the imaginary middle square (SM) around the blade axis (AI), and In the end view of the cutting insert (20), no part of the cutting insert (20) extends beyond the insert boundary line (LB).

2. The cutting insert (20) according to claim 1, wherein, The top master back gap angle (β1) has a minimum of 75 degrees and a maximum of 85 degrees.

3. The cutting insert (20) according to claim 1, wherein the four top main cutting edges (36) are completely contained in a top horizontal plane (PH) perpendicular to the insert axis (AI).

4. The cutting insert (20) according to claim 3, wherein the four top corner cutting edges (38) are completely contained within the top horizontal plane (PH).

5. The cutting blade (20) according to claim 1, wherein each intermediate surface (46) is perpendicular to the mid-plane (M).

6. The cutting insert (20) according to claim 1, wherein: The imaginary central square (SM) is divided into four identical quadrants (Q1, Q2, Q3, Q4) by a first and second vertical plane (PV1, PV2) that contain the blade axis (AI) and intersect the four side surfaces (26) and are mutually perpendicular. Each top primary cutting edge (36) is located in two of the four quadrants (Q1, Q2, Q3, Q4).

7. The cutting insert (20) according to claim 1, wherein the middle diameter (DM) is greater than the top master diameter (DJ).

8. The cutting insert (20) according to claim 1, wherein, In the side view of the cutting insert (20): The top primary clearance surface (48) has a variable top primary clearance width (WJ) parallel to the blade axis (AI), and The width of the top main back gap (WJ) increases in the transverse direction (SD) parallel to the midplane (M).

9. The cutting insert (20) according to claim 8, wherein: Each top side edge (32) also includes a top secondary cutting edge (44), and In the side view of the cutting insert (20), the transverse direction (SD) is from the top primary cutting edge (36) to the top secondary cutting edge (44) on the same top side edge (32).

10. The cutting insert (20) according to claim 9, wherein: Four top secondary cutting edges (44) define an imaginary top secondary square (SN), which has an imaginary inscribed top secondary circle (CN) having a top secondary diameter (DN), and In the top end view of the cutting insert (20), the imaginary top sub-square (SN) coincides with the imaginary middle square (SM).

11. The cutting insert (20) according to claim 9, wherein, In the top end view of the cutting blade (20): The top primary cutting edge and top secondary cutting edge (36, 44) associated with each top corner cutting edge (38) form an acute-angled inner top corner angle (α1).

12. The cutting insert (20) according to claim 1, wherein the third imaginary straight line (L3) extends perpendicularly to the midplane (M) and intersects one of the top main cutting edges (36) at any point along its length, passing through the midplane (M) within the insert boundary line (LB).

13. The cutting insert (20) according to claim 1, wherein, In the top end view of the cutting blade (20): Four top sub-cutting edges (44) define an imaginary top sub-square (SN); The imaginary top main square (SJ) is nested within the imaginary top secondary square (SN); and In each top side edge (32), the top primary cutting edge (36) is recessed relative to the top secondary cutting edge (44) and the top primary cutting edge (36) is longer than the top secondary cutting edge (44).

14. A cutting tool (60) rotatable about a tool axis (AT) in a rotational direction (RD), comprising: The tool body (62) extends along the tool axis (AT) in the front-rear direction (DF, DR); and At least one reversible cutting insert (20) according to claim 1, which is removably fixed in the insert receiving groove (64) of the tool body (62), in: One of the top angle cutting edges (38) of each cutting insert (20) is operational, and The one of the top primary cutting edges (36) of each cutting insert (20) that is adjacent to the operating top corner cutting edge (38) is the operating top primary cutting edge (36).

15. The cutting tool (60) according to claim 14, wherein the top primary cutting edge (36) of each cutting insert (20) defines the tool cutting diameter (DTC).

16. The cutting tool (60) according to claim 15, wherein: N cutting inserts (20) are removably fixed in N insert receiving slots (64) spaced circumferentially around the tool body (62), where N is a positive integer greater than one. The cutting tool (60) exhibits N-fold rotational symmetry about the tool axis (AT).

17. The cutting tool (60) according to claim 16, wherein: The cutting diameter (DTC) of the tool, measured in millimeters, divided by N, is less than 8.

5.

18. The cutting tool (60) according to claim 15, wherein: The axial foremost cutting point (NF) of each cutting insert (20) defines the end face cutting diameter (DFC). Half of the difference between the tool cutting diameter (DTC) and the face cutting diameter (DFC) defines the second radial range (ER2), and The second radial range (ER2) is less than 20 percent of the top master diameter (DJ).

19. The cutting tool (60) according to claim 14, wherein: Each blade receiving slot (64) has a seat surface (70), with axial support walls and radial support walls (72, 74) transverse to the seat surface. The axial support wall (72) faces forward axially, and the radial support wall (74) faces outward radially. The bottom end surface (122) of each cutting blade (20) is clamped in contact with its respective seat surface (70). The first (26a) of the four side surfaces of each cutting insert (20) is clamped in contact with the axial support wall (72), and The second (26b) of the four side surfaces of each cutting insert (20) is in clamping contact with the radial support wall (74).

20. The cutting tool (60) according to claim 19, wherein: The top main rear clearance surface (48) of the first side surface (26a) is clamped in contact with the axial support wall (72), and The middle surface (46) of the second side surface (26b) is in clamping contact with the radial support wall (74).

21. The cutting tool (60) according to claim 20, wherein, The axial support wall (72) forms an acute external axial support angle (φ1) with the seat surface (70).

22. The cutting tool (60) according to claim 19, wherein, A cross-sectional view taken in the first tool plane (PT1) perpendicular to the tool axis (AT) and intersecting with the at least one seat surface (70): The second tool plane (PT2), which includes the tool axis (AT) and the outermost radial point (NO) of one of the seat surfaces (70), forms an acute internal radial groove angle (τ1) with the seat surface (70).

23. The cutting tool (60) according to claim 14, wherein: The maximum depth of cut (DC) of the cutting tool (60) along the tool axis (AT) in the forward direction (DF). MAX It is greater than half the top master diameter (DJ) of each blade.

24. The cutting tool (60) according to claim 14, wherein: Each cutting insert (20) is oriented in its respective insert receiving groove (64) such that during the milling operation, each cutting insert (20) cuts an accurate ninety-degree shoulder in the workpiece (80).

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