Cutting insert having two upper cutting edges and one lower central protrusion with four abutment walls defining an imaginary quadrilateral, and rotary cutting tool

Abstract

A cutting insert has opposite upper and lower surfaces interconnected by peripheral side surfaces, an insert axis passing through the upper and lower surfaces, and first and second upper cutting edges formed at intersections of the upper surface and the peripheral side surfaces. A lower central protuberance having first, second, third, and fourth land walls extends downwardly from the lower surface. In a cross section taken in a first horizontal plane perpendicular to the insert axis and intersecting the lower central protuberance, the first, second, third, and fourth land walls define an imaginary quadrilateral having first and third diagonally opposite interior angles that are equal to each other, and second and fourth diagonally opposite interior angles that are unequal to each other. The two cutting inserts are removably secured in a rotary cutting tool.

Description

Technical Field

[0001] This invention relates to a rotary cutting tool and a cutting insert having two upper cutting edges and a lower central projection having four base walls defining an imaginary quadrilateral. Rotary cutting tools are commonly used for milling operations, particularly in the form of ball end mills for template and contour operations. Background Technology

[0002] In the field of cutting tools used in milling operations, there are some examples of cutting inserts that have two upper cutting edges and a lower central projection with four base walls defining an imaginary quadrilateral.

[0003] US6,536,996 discloses a cutting tool including a tool body and two cutting inserts mounted therein. The tool body has an insert receiving recess with a recess bottom wall. A notch leading to the recess bottom wall has a lower wall defined by first, second, third, and fourth side walls. The cutting inserts have insert bottom walls. A protrusion extends downward from the insert bottom wall and has a lower wall defined by first, second, third, and fourth outer side walls. The insert bottom wall abuts against the recess bottom wall, a first lateral wall abuts against the first side wall, a third lateral wall abuts against the third side wall, the first outer side wall is a first distance from a centerline, and a cutting edge near the centerline is a second distance from it, wherein the first distance is at least three times the second distance, and wherein the retraction face of the cutting insert is disengaged from the insert receiving recess.

[0004] US9,573,204 discloses a cutting tool and a cutting insert, each of which includes a bottom surface and an adjacent anti-slip device. The anti-slip device of the cutting insert includes an insert actuator surface and non-parallel first and second insert abutment surfaces formed on a single protrusion in a central region of the insert bottom surface. The tool's anti-slip device includes first and second insert abutment surfaces recessed into the tool bottom surface, and a clamp including the insert actuator surface. The cutting insert is mounted on the cutting tool via engagement of its bottom surface, and the clamp is operable to bias the actuator surfaces relative to each other, thereby forcing the first and second abutment surfaces to abut against each other to prevent the cutting insert from sliding along the tool bottom surface.

[0005] One object of the present invention is to provide an improved cutting insert with an optimized peripheral shape.

[0006] Another object of the present invention is to provide an improved rotary cutting tool having two identical cutting inserts detachably fixed therein.

[0007] Another object of the present invention is to provide an improved rotary cutting tool that can perform cutting operations by advancing axially along the tool axis without leaving an uncut "center leg" in the workpiece.

[0008] Another object of the present invention is to provide an improved rotary cutting tool in which two cutting inserts have different operating cutting edges, and wherein the two insert receiving recesses provide them with equivalent horizontal radial and axial support.

[0009] Another object of the present invention is to provide an improved rotary cutting, wherein each cutting blade can only be detachably fixed in either of two blade receiving recesses in a single mounting position. Summary of the Invention

[0010] According to the present invention, a cutting insert is provided, comprising: opposing upper and lower surfaces connected to each other by peripheral side surfaces, and a cutting insert axis passing through the upper and lower surfaces.

[0011] At the upper peripheral edge where the upper surface and the peripheral side surface intersect, the upper peripheral edge has first and second upper cutting edges, and

[0012] A lower central protrusion extends downward from the lower surface away from the upper surface. The lower central protrusion includes first, second, third, and fourth abutment walls transverse to the lower surface. The first, second, third, and fourth abutment walls are sequentially arranged on an envelope extending around the periphery of the lower central protrusion.

[0013] In the cross-section taken from the first horizontal plane perpendicular to the blade axis and intersecting the envelope plane, the first, second, third, and fourth abutment walls define an imaginary quadrilateral with diagonally opposite first and third interior angles and diagonally opposite second and fourth interior angles.

[0014] The imaginary quadrilateral has first, second, third, and fourth sides respectively associated with the first, second, third, and fourth abutment walls; a first interior angle is formed between the first and second sides; a second interior angle is formed between the second and third sides; a third interior angle is formed between the third and fourth sides; and a fourth interior angle is formed between the fourth and first sides.

[0015] The first and third interior angles are equal, while the second and fourth interior angles are not equal.

[0016] Furthermore, according to the present invention, a rotary cutting tool is provided that can rotate about a tool axis in a rotational direction, the rotary cutting tool comprising a tool body having first and second blade receiving recesses, and a cutting blade of the type described above that is detachably fixed in each of the first and second blade receiving recesses. Attached Figure Description

[0017] 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:

[0018] Figure 1 This is a top perspective view of a cutting blade according to some embodiments of the present invention;

[0019] Figure 2 yes Figure 1 The lower perspective view of the cutting blade shown;

[0020] Figure 3 yes Figure 1 A top view of the cutting blade shown;

[0021] Figure 4 yes Figure 1 The bottom view of the cutting blade shown;

[0022] Figure 5 yes Figure 1 The side view of the cutting blade shown;

[0023] Figure 6 yes Figure 5 The cross-sectional view of the cutting blade taken along line VI-VI;

[0024] Figure 7 This is a side view of the tool body according to some embodiments of the present invention;

[0025] Figure 8 yes Figure 7 A top view of the first blade receiving recess of the tool body shown;

[0026] Figure 9 yes Figure 7 A top view of the second blade receiving recess of the tool body shown;

[0027] Figure 10 This is a perspective view of a cutting tool according to some embodiments of the present invention;

[0028] Figure 11 yes Figure 10 The first side view of the cutting tool shown;

[0029] Figure 12 yes Figure 10 The second side view of the cutting tool shown;

[0030] Figure 13 yes Figure 10 The end view of the cutting tool shown;

[0031] Figure 14 yes Figure 10A cross-sectional view of the cutting tool associated with the first insert receiving recess;

[0032] Figure 15 yes Figure 14 The cross-sectional view taken along line XV-XV by the cutting tool shown;

[0033] Figure 16 yes Figure 10 A cross-sectional view of the cutting tool associated with the second insert receiving recess; and

[0034] Figure 17 yes Figure 16 The cross-sectional view taken along line XVII-XVII of the cutting tool shown. Detailed Implementation

[0035] like Figures 1 to 6 As shown, one aspect of the invention relates to a cutting blade 20 having opposing upper surfaces 22 and lower surfaces 24 connected to each other by peripheral side surfaces 26, and a blade axis A1 passing through the upper surfaces 22 and lower surfaces 24 (or more precisely, passing through the plane defined by the upper and lower surfaces).

[0036] In some embodiments of the present invention, the lower surface 24 may be planar.

[0037] Furthermore, in some embodiments of the present invention, the through hole 28 may extend along the blade axis A1.

[0038] Furthermore, 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.

[0039] like Figure 1 and 3 As shown, the upper surface 22 may include a flat upper central region 27.

[0040] In some embodiments of the present invention, the through hole 28 may intersect with the upper central region 27.

[0041] like Figure 1 and Figure 3 As shown, a continuous upper peripheral edge 30 is formed at the intersection of the upper surface 22 and the peripheral side surface 26, and the upper peripheral edge 30 has first and second upper cutting edges 32 and 34.

[0042] In some embodiments of the invention, the upper outer periphery 30 may not exhibit rotational symmetry about the blade axis A1.

[0043] Furthermore, in some embodiments of the present invention, the first and second upper cutting edges 32 and 34 may be different.

[0044] Furthermore, in some embodiments of the present invention, the first and second upper cutting edges 32, 34 may be spaced apart by opposing first and second nose edges 33, 35.

[0045] like Figure 1 and Figure 3 As shown, the first upper cutting edge 32 may include a first main cutting edge portion 36a and a first secondary cutting edge portion 36b, while the second upper cutting edge 34 may include a second main cutting edge portion 38a and a second secondary cutting edge portion 38b.

[0046] In some embodiments of the present invention, in a top view of the cutting blade 20, such as Figure 3 As shown, each of the first primary cutting edge portion 36a and the second primary cutting edge portion 38a may have an outwardly convex shape, while each of the first secondary cutting edge portion 36b and the second secondary cutting edge portion 38b may be straight.

[0047] Furthermore, in some embodiments of the present invention, in the side view of the cutting blade 20, as shown... Figure 5 As shown, each of the first and second main cutting edge portions 36a and 38a may have an upwardly convex shape.

[0048] like Figure 1 and 3 As shown, the first nose edge 33 may extend between the first main cutting edge portion 36a and the second secondary cutting edge portion 38b, while the second nose edge 35 may extend between the second main cutting edge portion 38a and the first secondary cutting edge portion 36b.

[0049] like Figure 2 , 4 As shown in Figure 5, the lower central protrusion 40 extends downward from the lower surface 24 and away from the upper surface 22, and the lower central protrusion 40 includes first, second, third and fourth abutment walls 42a, 42b, 42c and 42d transverse to the lower surface 24.

[0050] The first, second, third, and fourth basement walls 42a, 42b, 42c, and 42d are arranged sequentially on the envelope surface 43 extending around the lower central protrusion 40.

[0051] In some embodiments of the invention, the lower central protrusion 40 may have a bottom surface 44, and the envelope surface 43 may extend from the lower surface 24 to the bottom surface 44.

[0052] Furthermore, in some embodiments of the present invention, the through hole 28 may intersect with the bottom surface 44.

[0053] like Figure 2As shown, a continuous lower peripheral edge 46 is formed at the intersection of the lower surface 22 and the peripheral side surface 26.

[0054] In some embodiments of the present invention, the lower peripheral edge 46 may not have a cutting edge.

[0055] In some embodiments, the cutting blade 20 is one-sided (or “irreversible”) due to the lower central protrusion 40, meaning it cannot be rotated by inverting.

[0056] like Figure 4 As shown in the bottom view of the cutting blade 20, each of the first, second, third, and fourth base walls 42a, 42b, 42c, and 42d can be located inside the lower peripheral edge 46.

[0057] In some embodiments of the invention, in a bottom view of the cutting blade 20, the entire lower central protrusion 40 may be located inside the lower peripheral edge 46.

[0058] With first, second, third, and fourth base walls 42a, 42b, 42c, and 42d, the lower central protrusion 40 can be used to detachably fix the cutting insert 20 to the radial and axial support surfaces of the cutting tool.

[0059] Therefore, it should be understood that the peripheral side surface 26 of the insert can be completely spaced apart from the surface of the cutting tool, such that the shapes of the first and second upper cutting edges 32, 34 and portions of the peripheral side surface 26 that provide clearance for the first and second cutting edges 32, 34 can be optimized without the geometric constraints associated with detachably securing the cutting insert 20 to the cutting tool.

[0060] like Figure 6 As shown, in a cross section taken along a first horizontal plane PH1 perpendicular to the blade axis A1 and intersecting with the envelope plane 43, the first, second, third, and fourth abutment walls 42a, 42b, 42c, and 42d define an imaginary quadrilateral QI with diagonally opposite first and third interior angles α1 and α3 and diagonally opposite second and fourth interior angles α2 and α4.

[0061] In addition, such as Figure 6 As shown, the imaginary quadrilateral QI has first, second, third, and fourth sides S1, S2, S3, and S4 respectively associated with the first, second, third, and fourth base walls 42a, 42b, 42c, and 42d; a first interior angle α1 formed between the first and second sides S1 and S2; a second interior angle α2 formed between the second and third sides S2 and S3; a third interior angle α3 formed between the third and fourth sides S3 and S4; and a fourth interior angle α4 formed between the fourth side and the first side S4 and S1.

[0062] In some embodiments of the present invention, in a cross-section taken along the first horizontal plane PH1, each of the first, second, third, and fourth abutment walls 42a, 42b, 42c, and 42d can be straight.

[0063] Furthermore, in some embodiments of the present invention, each of the first, second, third, and fourth base walls 42a, 42b, 42c, and 42d may be planar.

[0064] Furthermore, in some embodiments of the present invention, each of the first, second, third, and fourth base walls 42a, 42b, 42c, 42d may be parallel to the blade axis A1.

[0065] like Figure 2 and 4 As shown, the envelope surface 43 may include first, second, third and fourth corner surfaces 45a, 45b, 45c and 45d, wherein the first corner surface 45a is disposed between the first and second base walls 42a and 42b, the second corner surface 45b is disposed between the second and third base walls 42b and 42c, the third corner surface 45c is disposed between the third and fourth base walls 42c and 42d, and the fourth corner surface 45d is disposed between the fourth and first base walls 42d and 42a.

[0066] like Figure 6 As shown, in the cross-section taken along the first horizontal plane PH1, the first corner surface 45a can be concave, the second and third corner surfaces 45b and 45c can be straight, and the fourth corner surface 45d can be convex.

[0067] In some embodiments of the present invention, in a cross-section taken along the first horizontal plane PH1, the first, second, third and fourth corner surfaces 45a, 45b, 45c and 45d may be located inside the imaginary quadrilateral QI.

[0068] like Figure 4 As shown, the first base wall 42a may include two spaced-apart first sub-walls 42a' and 42a'', while the third base wall 42c may include two spaced-apart third sub-walls 42c' and 42c''.

[0069] In some embodiments of the present invention, such as Figure 6 As shown, in the cross-section taken along the first horizontal plane PH1, the two first sub-walls 42a' and 42a'' can be collinear, while the two third sub-walls 42c' and 42c'' can be collinear.

[0070] like Figure 4 and 6As shown, the two first sub-walls 42a' and 42a'' can be separated by the first protrusion 47a, and the two third sub-walls 42c' and 42c'' can be separated by the third protrusion 47c.

[0071] In some embodiments of the present invention, in a cross-section taken along the first horizontal plane PH1, the first and third protrusions 47a and 47c may be located outside the imaginary quadrilateral QI.

[0072] Furthermore, in some embodiments of the present invention, a first radial plane PR1 containing the blade axis A1 and perpendicular to the first side S1 may intersect with the first protrusion 47a, and a third radial plane PR3 containing the blade axis A1 and perpendicular to the third side S3 may intersect with the third protrusion 47c.

[0073] like Figure 6 As shown, in the cross-section taken along the first horizontal plane PH1, the through hole 28 can be completely located inside the imaginary quadrilateral QI.

[0074] In an embodiment of the invention where the through hole 28 extends along the blade axis A1 and is entirely within the imaginary quadrilateral QI, it should be understood that the first and third protrusions 47a, 47c advantageously provide the lower central protrusion 40 with an increased minimum wall thickness adjacent to the through hole 28, thereby increasing the strength of the cutting blade 20.

[0075] According to the present invention, the first and third interior angles α1 and α3 are equal to each other, while the second and fourth interior angles α2 and α4 are not equal to each other. Therefore, the imaginary quadrilateral Qi can be described as an irregular quadrilateral.

[0076] In some embodiments of the present invention, the second and fourth interior angles α2 and α4 can be different from the first and third interior angles α1 and α3.

[0077] Furthermore, in some embodiments of the present invention, the second interior angle α2 may be an acute angle, while the fourth interior angle α4 may be an obtuse angle.

[0078] like Figure 6 As shown, in the cross-section taken along the first horizontal plane PH1, the sum of the second and fourth interior angles α2 and α4 can be twice the value of the first interior angle α1 or the third interior angle α3.

[0079] Therefore, in some embodiments of the present invention, the first and third interior angles α1 and α3 can both be right angles.

[0080] Since the diagonally opposite second and fourth interior angles α2 and α4 are not equal to each other, the hypothetical quadrilateral QI may lack rotational symmetry about the insert axis A1 (at any angle less than 360°). In this case, even if the first and second upper cutting edges 32 and 34 are rotationally symmetrical about the insert axis A1 (at an angle less than 360°), the cutting insert 20 as a whole will lack rotational symmetry.

[0081] like Figure 6 As shown, the imaginary quadrilateral QI has first, second, third, and fourth corner points NC1, NC2, NC3, and NC4, which are respectively associated with the first, second, third, and fourth interior angles α1, α2, α3, and α4.

[0082] In some embodiments of the present invention, the first and third corner points NC1 and NC3 may be located at first and third distances d1 and d3 from the blade axis A1, respectively, and the first and third distances d1 and d3 may be equal to each other.

[0083] like Figure 6 As shown, in the cross-section taken along the first horizontal plane PH1, the first, second, third and fourth corner points NC1, NC2, NC3 and NC4 can be located outside the lower central protrusion 40.

[0084] In some embodiments of the present invention, in a cross-section taken along the first horizontal plane PH1, at least one of the first and third corner points NC1 and NC3 may be located outside the lower peripheral edge 46.

[0085] like Figure 6 As shown, each of the first side S1 and the third side S3 can be longer than each of the second side S2 and the fourth side S4.

[0086] In some embodiments of the present invention, the first side S1 and the third side S3 may not be parallel, and the second side S2 and the fourth side S4 may not be parallel.

[0087] like Figure 3 and Figure 6 As shown, the first vertical surface PV1 containing the first side S1 can intersect with the first and second main cutting edge portions 36a and 38a, while the third vertical surface PV3 containing the third side S3 can intersect with the first and second main cutting edge portions 36a and 38a.

[0088] Similarly, Figure 3 and 6 As shown, the second vertical plane PV2, which includes the second side S2, can intersect with the second main cutting edge portion 38a and the first secondary cutting edge portion 36b, while the fourth vertical plane PV4, which includes the fourth side S4, can intersect with the first main cutting edge portion 36a and the second secondary cutting edge portion 38b.

[0089] In addition, such as Figure 3 As shown, the first nose edge 33 can be completely located in one of the four spatial regions defined by the intersection of the first and fourth vertical planes PV1 and PV4, while the second nose edge 35 can be completely located in one of the four spatial regions defined by the intersection of the second and third vertical planes PV2 and PV3.

[0090] In some embodiments of the present invention, the first, second, third and fourth vertical planes PV1, PV2, PV3 and PV4 may be parallel to the blade axis A1.

[0091] like Figures 7 to 13 As shown, another aspect of the invention relates to a rotary cutting tool 48 that can rotate about the tool axis AT in the rotation direction RT.

[0092] The rotary cutting tool 48 includes a tool body 50 having first and second blade receiving recesses 52, 54, and one of the aforementioned cutting blades 20 detachably fixed in each of the first and second blade receiving recesses 52, 54.

[0093] In some embodiments of the invention, the tool body 50 may have an outer peripheral surface 56 interrupted by first and second cuts 58, 60, and first and second blade receiving recesses 52, 54 may be formed in the first and second cuts 58, 60, respectively.

[0094] Furthermore, in some embodiments of the present invention, the first and second cuts 58, 60 may be formed at the axial front end 61 of the tool body 50.

[0095] Furthermore, in some embodiments of the present invention, the first and second cuts 58 and 60 may be interconnected.

[0096] However, further, in some embodiments of the present invention, the first and second cuts 58 and 60 may respectively include the first and second chip grooves 62 and 64.

[0097] like Figure 7 As shown, the first and second blade receiving recesses 52 and 54 may each have first and second seat surfaces 66 and 68 facing the rotation direction RT.

[0098] It should be understood that Figure 7 The second blade receiving recess 54 and its associated features are shown in concealed detail.

[0099] In some embodiments of the present invention, the first and second seat surfaces 66, 68 may intersect with the circumferential outer peripheral surface 56.

[0100] Furthermore, in some embodiments of the present invention, each of the first and second seat surfaces 66, 68 may be planar.

[0101] like Figure 12 As shown, in the side view of the cutting tool 48, the second seat surface 68 can be tilted at an acute angle β1 relative to the tool axis AT, thereby the axial rear portion of the second seat surface is rotatably positioned in front of the axial front portion of the second seat surface.

[0102] In some embodiments of the invention, the first seat surface 66 may also be inclined relative to the tool axis AT, thereby rotatably displacing the axial rear portion of the first seat surface in front of the axial front portion of the first seat surface.

[0103] like Figure 12 and 13 As shown, the lower surface 24 of the first of the two cutting blades 20' can face the first seat surface 66, while the lower surface 24 of the second of the two cutting blades 20'' can face the second seat surface 68.

[0104] In some embodiments of the present invention, the lower surface 24 of the first cutting blade 20' can contact the first seat surface 66, while the lower surface 24 of the second cutting blade 20'' can contact the second seat surface 68.

[0105] like Figures 10 to 13 As shown, the first upper cutting edge 32 of the first cutting insert 20' can be used, and the second upper cutting edge 34 of the second cutting insert 20'' can be used.

[0106] In some embodiments of the invention, the first and second nose edges 33, 35 may not be configured to perform cutting operations, so the first nose edge 33 of the first cutting blade 20' and the second nose edge 35 of the second cutting blade 20'' may not engage the workpiece (not shown).

[0107] In some embodiments of the present invention, the rotary cutting tool 48 can be used for milling operations.

[0108] Furthermore, in some embodiments of the present invention, the rotary cutting tool 48 may be in the form of a ball end mill for template and contouring operations.

[0109] For some embodiments of the present invention, it should be understood that a large portion of the usable second upper cutting edge 34 of the second cutting insert 20'' can rotate around the tool axis AT to coincide with the usable first upper cutting edge 32 of the first cutting insert 20'.

[0110] like Figure 13 As shown, the first upper cutting edge 32 of the first cutting insert 20' can intersect with the tool axis AT.

[0111] In embodiments of the invention, where the first usable upper cutting edge 32 of the first cutting insert 20' intersects the tool axis AT, it should be understood that the cutting tool 48 can advantageously perform cutting operations by advancing axially along the tool axis AT without leaving an uncut “center leg” (not shown) in the workpiece, which would otherwise require additional cutting operations to remove and could inadvertently damage the cutting edge.

[0112] It should be understood that, in order to improve visual clarity, Figures 10 to 12 The tool axis AT is shown as being unobstructed by the tool body 50.

[0113] like Figures 7 to 9 As shown, the first and second blade receiving recesses 52 and 54 may be included in the first and second grooves 70 and 72 in the first and second seat surfaces 66 and 68, respectively.

[0114] In some embodiments of the present invention, the first and second grooves 70, 72 may not intersect with the outer peripheral surface 56.

[0115] Furthermore, in some embodiments of the present invention, the first groove 70 may be circumferentially surrounded by the first seat surface 66, and the second groove 72 may be circumferentially surrounded by the second seat surface 68.

[0116] Furthermore, in some embodiments of the present invention, the lower center protrusion 40 of the first cutting blade 20' may occupy the first groove 70, while the lower center protrusion 40 of the second cutting blade 20'' may occupy the second groove 72.

[0117] like Figures 7 to 9 As shown, the first groove 70 may include spaced-apart first radial and first axial support surfaces 74 and 76, while the second groove 72 may include spaced-apart second radial and second axial support surfaces 78 and 80.

[0118] In some embodiments of the present invention, such as Figure 14 and 16 As shown, the first and second base walls 42a and 42b of the first cutting blade 20' can contact the first radial and first axial support surfaces 74 and 76, respectively, while the third and fourth base walls 42c and 42d of the second cutting blade 20'' can contact the second radial and second axial support surfaces 78 and 80, respectively.

[0119] It should be understood that Figure 14 and Figure 16 This is a detailed cross-sectional view of the cutting tool 48, taken parallel to the first and second seat surfaces 66 and 68 of the first and second blade receiving recesses 52 and 54, respectively.

[0120] Since the first interior angle α1 is associated with the first and second base walls 42a, 42b, and the third interior angle α3 is associated with the third and fourth base walls 42c, 42d, and the first and third interior angles α1 and α3 are equal, it should be understood that the first radial and first axial support surfaces 74, 76 of the first groove 70 may have a configuration corresponding to the second radial and second axial support surfaces 78, 80 of the second groove 72, such that the first and second cutting blades 20', 20'' can be detachably fixed in their respective first and second blade receiving recesses 52, 54 with a correspondingly high level of stability.

[0121] In some embodiments of the present invention, the lower central protrusion 40 of the first cutting blade 20' may occupy the first groove 70 only in a single mounting position, wherein the first and second base walls 42a and 42b face the first radial and first axial support surfaces 74 and 76, respectively, while the lower central protrusion 40 of the second cutting blade 20'' may occupy the second groove 72 only in a single mounting position, wherein the third and fourth base walls 42c and 42d face the second radial and second axial support surfaces 78 and 80, respectively.

[0122] In such embodiments of the invention, it should be understood that when the usable first upper cutting edge 32 of the first cutting insert 20' is worn or used, the first cutting insert 20' will not inadvertently "rotate" in the first groove 70 of the first insert receiving recess 52. Similarly, when the usable second upper cutting edge 34 of the second cutting insert 20'' is worn or used, the second cutting insert 20' will not inadvertently "rotate" in the second groove 72 of the second insert receiving recess 54. This "foolproof" arrangement prevents incorrect assembly of the cutting tool 48.

[0123] It should be understood that the term “indexing” used in the preceding paragraph refers to removing, rotating about 180° around the blade axis A1, and attempting to replace the first and second blades 20', 20'' in their respective first and second blade receiving recesses 52, 54.

[0124] While the cutting insert 20 may not be indexed and returned to the same insert receiving recesses 52, 54, it can be placed in another insert receiving recess 54, 52. In other words, once the usable upper cutting edges 32, 34 of a pair of inserts used in the same tool body are worn, the inserts can be switched. This allows the use of the same insert in two insert recesses, each with a different usable cutting edge. The upper cutting edges 32, 34 may be numbered and / or equipped with wear indicators to help the operator keep track of which cutting edge has been used.

[0125] like Figures 7 to 9As shown, at least a portion of the first radial support surface 74 and at least a portion of the second radial support surface 78 can rotatably coincide about the tool axis AT.

[0126] In some embodiments of the invention, the aforementioned portions of the first radial support surface 74 and the aforementioned portions of the second radial support surface 78 may exhibit double rotational symmetry about the tool axis AT.

[0127] like Figures 7 to 9 As shown, at least a portion of the first axial support surface 76 and at least a portion of the second axial support surface 80 can rotatably coincide about the tool axis AT.

[0128] In some embodiments of the present invention, the aforementioned portions of the first axial support surface 76 and the aforementioned portions of the second axial support surface 80 may exhibit double rotational symmetry about the tool axis AT.

[0129] In embodiments of the present invention, wherein at least a portion of the first radial support surface 74 and at least a portion of the second radial support surface 78 are rotatably coincident about the tool axis AT, and at least a portion of the first axial support surface 76 and at least a portion of the second axial support surface 80 are rotatably coincident about the tool axis AT, it should be understood that the first and second grooves 70, 72 of the first and second insert receiving recesses 52, 54 can provide radial and axial support of equivalent level for the first and second cutting inserts 20', 20''.

[0130] Furthermore, in embodiments of the present invention, at least a portion of the first radial support surface 74 and at least a portion of the second radial support surface 78 are rotated to coincide about the tool axis AT, and at least a portion of the first axial support surface 76 and at least a portion of the second axial support surface 80 are rotated to coincide about the tool axis AT. However, it should be understood that alternative cutting tool assemblies may be configured in which two identical cutting inserts having double rotational symmetry (as described in US6,536,996 above) are detachably fixed in the first and second insert receiving recesses 52, 54 of the tool body 50.

[0131] like Figures 7 to 9 As shown, the first groove 70 may include a first radial stop wall 82 facing the first radial support surface 74, while the second groove 72 may include a second radial stop wall 84 facing the second radial support surface 78.

[0132] In some embodiments of the present invention, the third and fourth base walls 42c and 42d of the first cutting blade 20' may not contact the first groove 70, while the first and second base walls 42a and 42b of the second cutting blade 20'' may not contact the second groove 72.

[0133] Therefore, it should be understood that in some embodiments of the present invention, such as Figure 15 and 17 As shown, the first radial stop wall 82 can be spaced apart from the third base wall 42c of the first cutting blade 20', while the second radial stop wall 84 can be spaced apart from the first base wall 42a of the second cutting blade 20''.

[0134] In an embodiment of the present invention, the first radial stop wall 82 is spaced apart from the third base wall 42c of the first cutting blade 20', and the second radial stop wall 84 is spaced apart from the first base wall 42a of the second cutting blade 20''. However, it should be understood that the presence and position of the first radial stop wall 82 in the first groove 70 physically prevents the first cutting blade 20' from being accidentally "displaced" therein, and the presence and position of the second radial stop wall 84 in the second groove 72 physically prevents the second cutting blade 20'' from being accidentally "displaced" therein.

[0135] It should also be understood that the presence and position of the first radial stop wall 82 in the first groove 70 physically prevents any cutting blade 20 from being installed therein and oriented such that its second upper cutting edge 34 is usable, while the presence and position of the second radial stop wall 84 in the second groove 72 physically prevents any cutting blade 20 from being installed therein and oriented such that its first upper cutting edge 32 is usable.

[0136] In some embodiments of the present invention, in addition to the first and second base walls 42a and 42b of the first cutting blade 20' contacting the first radial and first axial support surfaces 74 and 76 respectively, other surfaces of the envelope surface 43 of the first cutting blade can contact the first groove 70, and in addition to the third and fourth base walls 42c and 42d of the second cutting blade 20'' contacting the second radial and second axial support surfaces 78 and 80 respectively, other surfaces of the envelope surface 43 of the second cutting blade can contact the second groove 72.

[0137] like Figure 8 and 9 As shown, the first groove 70 may include a first surface 86 having a first threaded hole 88 therein, while the second groove 72 may include a second surface 90 having a second threaded hole 92 therein.

[0138] like Figure 15 and 17 As shown, the bottom surface 44 of the lower central protrusion 40 of the first cutting blade 20' can be spaced apart from the first base plate surface 86, while the bottom surface 44 of the lower central protrusion 40 of the second cutting blade 20'' can be spaced apart from the second base plate surface 90.

[0139] In some embodiments of the present invention, a first clamping screw 94' may pass through a through hole 28 of a first cutting blade 20' and be threaded into a first threaded hole 88, while a second clamping screw 94'' may pass through a through hole 28 of a second cutting blade 20' and be threaded into a second threaded hole 92.

[0140] It should be understood that the first clamping screw 94' and the second clamping screw 94'' can be the same.

[0141] Furthermore, in some embodiments of the present invention, the first threaded hole 88 may extend along the first threaded hole axis B1, and the blade axis A1 of the first cutting blade 20' may be coaxial with the first threaded hole axis B1, while the second threaded hole 92 may extend along the second threaded hole axis B2, and the blade axis A1 of the second cutting blade 20'' may be coaxial with the second threaded hole axis B2.

[0142] In such embodiments of the invention, the through hole 28 of the first cutting insert 20' may be eccentric relative to the first threaded hole 88, and the through hole 28 of the second cutting insert 20'' may be eccentric relative to the second threaded hole 92.

[0143] It should be understood that the eccentric relationship between the through hole 28 and the first threaded hole 88 of the first cutting insert 20' facilitates the contact between the first and second base walls 42a, 42b of the first cutting insert 20' and the first radial and first axial support surfaces 74, 76, respectively, when the first clamping screw 94' is tightened.

[0144] It should also be understood that the eccentric relationship between the through hole 28 and the second threaded hole 92 of the second cutting insert 20'' facilitates the contact between the third and fourth base walls 42c and 42d of the second cutting insert 20'' and the second radial and second axial support surfaces 78 and 80, respectively, when the second clamping screw 94'' is tightened.

[0145] Although the invention has been described to a certain degree of specificity, it should be understood that various changes and modifications can be made without departing from the spirit or scope of the invention as claimed.

Claims

1. A single-sided cutting insert (20), comprising: Opposite upper surfaces (22) and lower surfaces (24) interconnected by peripheral side surfaces (26), and blade axis (A1) passing through said upper surfaces (22) and lower surfaces (24). At the intersection of the upper surface (22) and the peripheral side surface (26), the upper peripheral edge (30) has first and second upper cutting edges (32, 34), and A lower central protrusion (40) extending downward from the lower surface (24) and away from the upper surface (22) includes first, second, third, and fourth abutment walls (42a, 42c, 42b, 42d) transverse to the lower surface (24), the first, second, third, and fourth abutment walls (42a, 42c, 42b, 42d) being arranged sequentially on an envelope surface (43) extending around the periphery of the lower central protrusion (40). In a cross section taken along a first horizontal plane (PH1) perpendicular to the blade axis (A1) and intersecting the envelope plane (43), the first, second, third, and fourth abutment walls (42a, 42b, 42c, 42d) define an imaginary quadrilateral (QI) with diagonally opposite first and third interior angles (α1, α3) and diagonally opposite second and fourth interior angles (α2, α4). The imaginary quadrilateral (QI) has first, second, third, and fourth sides (S1, S2, S3, S4) respectively associated with the first, second, third, and fourth base walls (42a, 42b, 42c, 42d). A first interior angle (α1) is formed between the first and second sides (S1, S2), a second interior angle (α2) is formed between the second and third sides (S2, S3), a third interior angle (α3) is formed between the third and fourth sides (S3, S4), and a fourth interior angle (α4) is formed between the fourth side and the first side (S4, S1). Among them, the first and third interior angles (α1, α3) are equal to each other, while the second and fourth interior angles (α2, α4) are not equal to each other.

2. The single-sided cutting blade (20) according to claim 1, wherein, The upper outer edge (30) lacks rotational symmetry about the blade axis (A1).

3. The single-sided cutting insert (20) according to claim 1, wherein, The first and second upper cutting edges (32, 34) are not the same.

4. The single-sided cutting blade (20) according to claim 1, wherein, In the cross-section taken along the first horizontal plane (PH1), each of the first, second, third, and fourth abutment walls (42a, 42b, 42c, 42d) is straight.

5. The single-sided cutting insert (20) according to claim 1, wherein, The through hole (28) extends along the blade axis (A1).

6. The single-sided cutting insert (20) according to claim 5, wherein, In a cross-section taken along the first horizontal plane (PH1), the through hole (28) is completely located within the imaginary quadrilateral (QI).

7. The single-sided cutting blade (20) according to claim 1, wherein, The second interior angle (α2) is an acute angle, while the fourth interior angle (α4) is an obtuse angle.

8. The single-sided cutting insert (20) according to claim 1, wherein, The first and third interior angles (α1, α3) are both right angles.

9. The single-sided cutting insert (20) according to claim 1, wherein: The lower outer edge (46) is formed at the intersection of the lower surface (24) and the outer side surface (26), and In the bottom view of the single-sided cutting blade (20), each of the first, second, third and fourth base walls (42a, 42b, 42c, 42d) is located inside the lower peripheral edge (46).

10. The single-sided cutting insert (20) according to claim 1, wherein: Each of the first and third sides (S1, S3) is longer than each of the second and fourth sides (S2, S4).

11. The single-sided cutting insert (20) according to claim 1, wherein: The first upper cutting edge (32) includes a first main cutting edge portion (36a) and a first secondary cutting edge portion (36b). The second upper cutting edge (34) includes a second primary cutting edge portion (38a) and a second secondary cutting edge portion (38b), and In the top view of the single-sided cutting blade (20); Each of the first and second main cutting edge portions (36a, 38a) has an outwardly convex shape, and Each of the first and second secondary cutting edge portions (36b, 38b) is straight.

12. The single-sided cutting insert (20) according to claim 11, wherein: The first vertical plane (PV1) including the first side (S1) intersects with the first and second main cutting edge portions (36a, 38a), and The third vertical plane (PV3) containing the third side (S3) intersects with the first and second main cutting edge portions (36a, 38a).

13. The single-sided cutting insert (20) according to claim 11, wherein: The second vertical plane (PV2) containing the second side (S2) intersects with the second main cutting edge portion (38a) and the first secondary cutting edge portion (36b), and The fourth vertical plane (PV4) containing the fourth side (S4) intersects with the first primary cutting edge portion (36a) and the second secondary cutting edge portion (38b).

14. A rotary cutting tool (48) rotatable about a tool axis (AT) in a rotational direction (RT), comprising: A tool body (50) having first and second blade receiving recesses (52, 54); as well as A single-sided cutting blade (20) according to claim 1, which is detachably fixed in each of the first and second blade receiving recesses (52, 54).

15. The rotary cutting tool (48) according to claim 14, wherein: The first and second blade receiving recesses (52, 54) respectively have first and second seat surfaces (66, 68) facing the rotation direction (RT), and The lower surface (24) of the first cutting blade (20') of the two single-sided cutting blades faces the first seat surface (66), while the lower surface (24) of the second cutting blade (20'') of the two single-sided cutting blades faces the second seat surface (68).

16. The rotary cutting tool (48) according to claim 15, wherein: The first upper cutting edge (32) of the first cutting insert (20') is usable, and The second upper cutting edge (34) of the second cutting insert (20'') is usable.

17. The rotary cutting tool (48) according to claim 16, wherein, The first upper cutting edge (32) of the first cutting insert (20') intersects the tool axis (AT).

18. The rotary cutting tool (48) according to claim 15, wherein: The first and second blade receiving recesses (52, 54) respectively include first and second grooves (70, 72) in the first and second seat surfaces (66, 68), and The lower center protrusion (40) of the first cutting blade (20') occupies the first groove (70), and The lower center protrusion (40) of the second cutting blade (20'') occupies the second groove (72).

19. The rotary cutting tool (48) according to claim 18, wherein: The first groove (70) includes spaced-apart first radial and first axial support surfaces (74, 76), while the second groove (72) includes spaced-apart second radial and second axial support surfaces (78, 80), and The first and second base walls (42a, 42b) of the first cutting blade (20') are in contact with the first radial and first axial support surfaces (74, 76), respectively, while the third and fourth base walls (42c, 42d) of the second cutting blade (20'') are in contact with the second radial and second axial support surfaces, respectively.

20. The rotary cutting tool (48) according to claim 19, wherein: At least a portion of the first radial support surface (74) and at least a portion of the second radial support surface (78) are rotatably coincident about the tool axis (AT).

21. The rotary cutting tool (48) according to claim 19, wherein: At least a portion of the first axial support surface (76) and at least a portion of the second axial support surface (80) rotate around the tool axis (AT).

22. The rotary cutting tool (48) according to claim 19, wherein: The third and fourth base walls (42c, 42d) of the first cutting blade (20') do not contact the first groove (70), and The first and second base walls (42a, 42b) of the second cutting blade (20'') do not contact the second groove (72).

23. The rotary cutting tool (48) according to claim 19, wherein: The lower central protrusion (40) of the first cutting blade (20') can only occupy the first groove (70) in a single mounting position, wherein the first and second base walls (42a, 42b) face the first radial and first axial support surfaces (74, 76), respectively. The lower center protrusion (40) of the second cutting blade (20'') can only occupy the second groove (72) in a single mounting position, wherein the third and fourth base walls (42c, 42d) face the second radial and second axial support surfaces (78, 80), respectively.

24. A single-sided cutting insert (20), comprising: Opposite upper surfaces (22) and lower surfaces (24) interconnected by peripheral side surfaces (26), and blade axis (A1) passing through said upper surfaces (22) and lower surfaces (24). A through hole (28) extends along the blade axis (A1) and connects the upper surface (22) and the lower surface (24). At the intersection of the upper surface (22) and the peripheral side surface (26), the upper peripheral edge (30) has first and second upper cutting edges (32, 34), which are spaced apart from each other by opposing first and second nose edges (33, 35), and A lower central protrusion (40) extending downward from the lower surface (24) and away from the upper surface (22), the lower central protrusion (40) having an envelope (43) extending around its periphery and including first, second, third and fourth abutment walls (42a, 42c, 42b, 42d) arranged sequentially transverse to the lower surface (24), wherein: In a cross section taken along a first horizontal plane (PH1) perpendicular to the blade axis (A1) and intersecting the envelope plane (43), the first, second, third, and fourth abutment walls (42a, 42b, 42c, 42d) define an imaginary quadrilateral (QI) through which the blade axis (A1) passes. The imaginary quadrilateral (QI) lacks rotational symmetry about the blade axis (A1); The first and second upper cutting edges (32, 34) lack rotational symmetry about the blade axis (A1); and The through hole (28) is completely located within the imaginary quadrilateral (QI).

25. The single-sided cutting insert (20) according to claim 24, wherein, The imaginary quadrilateral (QI) includes: The first and third interior angles (α1, α3) are diagonally opposite each other, and the first and third interior angles are equal to each other. The second and fourth interior angles (α2, α4) are diagonally opposite each other. The second and fourth interior angles are not equal to each other, nor are they equal to the first and third interior angles (α1, α3).

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