Double-sided negative cutting inserts and milling tools

Abstract

A double-sided negative cutting insert for use in milling has a square basic shape and eight different working positions. The cutting insert (1) has a peripheral surface (10) extending around the cutting insert between first and second major surfaces (2, 3) and having four major side surfaces (11a-11d). One major cutting edge and one surface-wiping cutting edge are formed at the intersection between each major side surface and the first major surface (2) and the intersection between each major side surface and the second major surface (3). Each major side surface has a first lateral side surface (13), a central side surface (14), and a second lateral side surface (15) alternately arranged between two corner side surfaces (12). The central side surface (14) is located between the first and second lateral side surfaces (13, 15), and the central side surface is slightly recessed relative to the adjacent first and second lateral side surfaces.

Description

[Technical Field]

[0001] The present invention relates to a double-sided negative cutting insert for milling according to the preamble of claim 1. The present invention also relates to a milling tool comprising such a double-sided negative cutting insert.

[0002] The milling tool is a rotary cutting tool that may be provided with one or more cutting inserts removably mounted in respective insert seats of the tool body of the milling tool. One type of cutting insert that may be used in shoulder milling and face milling is a double-sided negative cutting insert having an essentially square basic shape of the type defined in the preamble of claim 1. This type of cutting insert has previously been known from U.S. Pat. No. 6,336,776 and is rotatable into eight different working positions, where four working positions are provided by four different sets of cutting edges formed on the contact surface between the outer peripheral surface of the cutting insert and the first major surface, and four further working positions are provided by four other different sets of cutting edges formed on the contact surface between the outer peripheral surface of the cutting insert and the second major surface, each such set of cutting edges comprising a main cutting edge and a surface-wiping cutting edge with an intermediate curved corner cutting edge. When the cutting edges in one such set of cutting edges are worn, the cutting insert can be repositioned within its insert seat and installed in a new working position with another one of the different sets of cutting edges in the active cutting position.

[0003] The double-sided negative cutting inserts of the type described above offer a number of different working positions and can be manufactured in a relatively simple and cost-effective manner. Because the cutting insert has a negative shape, it must be given a negative axial and radial push-in angle when installed in the insert seat of the tool body of the milling tool, meaning that the cutting insert must be pushed axially forward and radially outward within the tool body to obtain clearance. The negative axial push-in angle is necessary to create a relief behind the active surface-wiping cutting edge, and the negative radial push-in angle is necessary to create a relief behind the active main cutting edge. As a result of the negative axial push-in angle, the cutting process is heavier because the cutting insert is more difficult to cut compared to a corresponding cutting process performed with a cutting insert having a positive axial push-in angle. To counteract the negative effects of the axial push-in angle, each main cutting edge is given a downward slope away from the corner cutting edge that interconnects the main cutting edge with its associated surface-wiping cutting edge. This downward inclination of the main cutting edge, in combination with the negative axial and radial plunge angles, has the effect that the lead angle into the workpiece is always slightly less than 90°. It is desirable to have the lead angle as close to the 90° value as possible. Summary of the Invention

[0004] SUMMARY OF THE INVENTION It is an object of the present invention to provide a double-sided negative cutting insert of the type described above having a new and preferred design.

[0005] According to the invention, this object is achieved by a double-sided negative cutting insert having the features defined in claim 1.

[0006] The double-sided negative cutting insert according to the invention has an essentially square basic shape and is rotatable into eight different working positions; and first and second major surfaces disposed on opposite sides of the cutting insert, the first and second major surfaces serving as top and bottom surfaces of the cutting insert, the cutting insert having a central axis extending between the first and second major surfaces and a median plane extending perpendicular to the central axis and midway between the first and second major surfaces, the cutting insert having 90° rotational symmetry about the central axis; extending substantially perpendicular to the median plane around the cutting insert between the first and second major surfaces; and four major side surfaces, a first pair of the four major side surfaces disposed opposite one another on two opposing sides of the cutting insert and a second pair of the four major side surfaces disposed opposite one another on two other opposing sides of the cutting insert, the cutting insert having a first transverse plane extending midway between the two major side surfaces of the first pair and containing a central axis of the cutting insert, and a second transverse plane extending midway between the two major side surfaces of the second pair and containing the central axis of the cutting insert, each major side surface of the first pair having 180° rotational symmetry about a first imaginary reference axis extending along an intersection line between the median plane and the second transverse plane, and each major side surface of the second pair having 180° rotational symmetry about a second imaginary reference axis extending along an intersection line between the median plane and the first transverse plane; four corner sides, each positioned between two adjacent main sides; and a peripheral surface comprising: four first main cutting edges formed at intersections between respective ones of the four main side surfaces and the first main surface; four second main cutting edges formed at intersections between respective ones of the four main side surfaces and the second main surface; four first surface wiping edges formed at intersections between respective ones of the four major side surfaces and the first major surface; four second surface wiping edges formed at intersections between respective ones of the four major side surfaces and the second major surface; four first curved corner cutting edges formed at intersections between respective ones of the four corner side surfaces and the first main surface, each one of the first curved corner cutting edges being located between one of the first main cutting edges and one of the first surface-wiping edges; four second curved corner cutting edges formed at intersections between respective ones of the four corner side surfaces and the second main surface, each one of the second curved corner cutting edges being located between one of the second main cutting edges and one of the second surface-wiping edges; Equipped with.

[0007] As noted above, the outer peripheral surface extends substantially perpendicular to the median plane between the first and second major surfaces, i.e., perpendicular to within manufacturing tolerances, meaning that each portion of the outer peripheral surface is perpendicular to the median plane within manufacturing tolerances.

[0008] each one of the major sides comprises a central side surface extending between the first and second major faces, a first lateral side surface extending between the first and second major faces and adjacent to one of the four corner side surfaces, and a second lateral side surface extending between the first and second major faces and adjacent to another of the four corner side surfaces, the first lateral side surface, the central side surface, and the second lateral side surface being alternately arranged such that the central side surface is located between the first lateral side surface and the second lateral side surface; one of the first major cutting edges extends along the first lateral side surface and along at least a majority of the central side surface; and one of the first surface-wiping edges extends along at least a portion of the second lateral side surface; one of the second major cutting edges extends along the second lateral side surface and along at least a majority of the central side surface; and One of the second surface wiping edges extends along at least a portion of the first lateral side surface.

[0009] when viewed in cross-section of the cutting insert along the median plane, each one of the major side surfaces is disposed such that a first lateral side surface of the major side surface extends along a first line, a medial side surface of the major side surface extends along a second line, and a second lateral side surface of the major side surface extends along a third line; the second line has a first endpoint, where the second line is adjacent to the first line via the first endpoint, and a second endpoint, where the second line is adjacent to the third line via the second endpoint, and these first and second endpoints are located on an imaginary straight reference line extending between a first point, where the first line is adjacent to a corner side surface adjacent to a first lateral side surface of the major side surface, and a second point, where the third line is adjacent to a corner side surface adjacent to a second lateral side surface of the major side surface; the second line is recessed with respect to the imaginary straight reference line toward the central axis of the cutting insert, and has a deepest portion at a middle portion of the second line; and The depth of the second line relative to the imaginary straight reference line gradually increases when viewed in the direction from the first end point toward the deepest part of the second line and when viewed in the direction from the second end point toward the deepest part of the second line, and the depth of the deepest part of the second line relative to the imaginary straight reference line is 0.01 to 0.15 mm, preferably 0.01 to 0.10 mm.

[0010] It has been found that the above-described design of a double-sided negative cutting insert having a slightly recessed central side surface on each major side means that the lead angle, at least in the majority of commonly used cutting depth intervals, approaches the desired 90° value compared to a corresponding double-sided negative cutting insert having conventional flat major sides.

[0011] As a result of the symmetry of the cutting insert, the deepest portion of the central side surface of each major side is centrally located between the first and second lateral side surfaces of the major side.

[0012] When the double-sided negative cutting insert is in the working position with one of the first surface wiping edges in the active surface wiping position, the inactive first main cutting edge on the same major side as the active first surface wiping edge will be moved closely above the machined workpiece surface leveled by the first surface wiping edge. Correspondingly, when the double-sided negative cutting insert is in the working position with one of the second surface wiping edges in the active surface wiping position, the inactive second main cutting edge on the same major side as the active second surface wiping edge will be moved closely above the machined workpiece surface leveled by the second surface wiping edge. There must be adequate clearance between the inactive first or second main cutting edge and the workpiece surface to prevent small pieces of workpiece material from becoming trapped between the inactive main cutting edge and the workpiece surface, thereby causing minor damage to the inactive main cutting edge. This clearance is slightly improved along the recessed central side surface of the major side facing the workpiece surface, which reduces the risk of damage to the inactive main cutting edge.

[0013] In each working position of the double-sided negative cutting insert, one of the four major side surfaces of the cutting insert abuts against the radial support surface of the insert seat of the tool body of the milling tool, and another of the four major side surfaces of the cutting insert abuts against the axial support surface of the insert seat. The design of the major side surfaces with a recessed central side surface on each major side surface between the first and second lateral side surfaces means that the first and second lateral side surfaces of the major side surfaces facing the radial support surface of the insert seat can jointly function as two spaced-apart radial abutment surfaces of the cutting insert, and the first and second lateral side surfaces of the major side surfaces facing the axial support surface of the insert seat can jointly function as two spaced-apart axial abutment surfaces of the cutting insert, thereby providing good stability of the cutting insert in the radial and axial directions when mounted in the insert seat. The spaced apart radial abutment surfaces with intermediate recessed central side surfaces and the spaced apart axial abutment surfaces with intermediate recessed central side surfaces also have the effect of reducing vulnerability to dust and other small particles that may remain on the major side surfaces of the insert seat facing the radial and axial support surfaces.

[0014] The central axis of the cutting insert extends between the center point of the first major surface and the center point of the second major surface. The center point refers to the center of gravity or geometric center. The cutting insert may be provided with a through hole extending centrally through the cutting insert between the first and second major surfaces, where the central axis of the through hole coincides with the central axis of the cutting insert.

[0015] The double-sided negative cutting insert according to the present invention may have the form of a right-angle shoulder milling insert or a face milling insert.

[0016] Each one of the major side surfaces preferably has a shape such that a central side surface of the major side surface is tangentially connected to a first lateral side surface of the major side surface and tangentially connected to a second lateral side surface of the major side surface, meaning that there is a smooth transition from each lateral side surface to the adjacent central side surface.

[0017] According to one embodiment of the present invention, each of the first pair of major side surfaces preferably has a shape such that, when viewed in a side view of the cutting insert along the first imaginary reference axis toward the first pair of major side surfaces, the medial side surface of the first pair of major side surfaces has a length along the medial plane that corresponds to 35-75%, preferably 45-65%, of the width of the cutting insert measured along the medial plane when viewed in the side view. Due to the symmetry of the cutting insert, the medial side surface of each of the second pair of major side surfaces will have a length that corresponds to the length of the medial side surface of each of the first pair of major side surfaces.

[0018] Another embodiment of the present invention is the first lateral surface of each major side surface has a shape such that at least a portion of the first line protrudes outward from an associated imaginary linear reference line, the height of the highest portion of the first line relative to the associated imaginary linear reference line is 0.001 to 0.02 mm, and the highest portion is located on a convex portion of the associated first lateral surface; The second lateral surface of each major side surface has a shape such that at least a portion of the third line protrudes outward from the associated imaginary straight reference line, the height of the highest part of the third line relative to the associated imaginary straight reference line is 0.001 to 0.02 mm, and this highest part is provided on a convex part of the associated second lateral surface. It is characterized by:

[0019] In this case, the above-mentioned radial and axial abutment surfaces of the cutting insert are formed by the highest portions of the first and second lateral side surfaces of the major side surfaces facing the radial and axial support surfaces of the insert seat. The convexity of these highest portions of the first and second lateral side surfaces reduces the tolerance requirements for the first and second lateral side surfaces of the major side surfaces. The radii of curvature of the convex portions of the first and second lateral side surfaces are advantageously at least 25 mm, preferably 25 to 600 mm, more preferably 40 to 100 mm. Suitable radii of curvature of these convex portions may additionally or alternatively be defined in relation to the size of the cutting insert. In this case, the radius of curvature of the convex portion of the first lateral side surface and the radius of curvature of the convex portion of the second lateral side surface are advantageously 2 to 10 times, preferably 3 to 7 times, the width of the cutting insert, wherein the width of the cutting insert is measured along the median plane in a side view of the cutting insert as seen along the first virtual reference axis.

[0020] Another embodiment of the present invention is a second surface-wiping edge associated with a first lateral side surface of each major side surface extends along at least a portion of the convex portion of the first lateral side surface, preferably beyond the highest portion of the first lateral side surface; and a first surface wiping edge associated with the second lateral side surface of each major side surface extends along at least a portion of the convex portion of the second lateral side surface, and preferably beyond the highest portion of the second lateral side surface; It is characterized by:

[0021] The first and second lateral side surfaces of each major side may alternatively be planar such that the above-mentioned first and third lines are both coplanar with the associated imaginary straight reference line.

[0022] According to another embodiment of the present invention, the central side surface of each major side surface has at least one recess having a concave shape when viewed in a cross section of the cutting insert along the median plane (MP). The radius of curvature of the recess is advantageously 25 to 200 mm, preferably 50 to 170 mm. The suitable radius of curvature of the recess may additionally or alternatively be defined in relation to the size of the cutting insert. In this case, the radius of curvature of the recess is advantageously 2 to 16 times, preferably 3 to 13 times, the width of the cutting insert, where the width of the cutting insert is measured along the median plane in a side view of the cutting insert as viewed along the first imaginary reference axis.

[0023] Another embodiment of the present invention is each first surface wiping edge extending along at least a majority of an associated second lateral side surface; and each second surface wiping edge extending along at least a majority of an associated first lateral side surface; It is characterized by:

[0024] According to another embodiment of the invention, each of the first pair of major sides comprises: when viewed in a side view of the cutting insert along a first imaginary reference axis toward the major side surface, a first major cutting edge associated with the major side surface is inclined inwardly toward the median plane when viewed in a direction from a first end of the first major cutting edge located at an intersection between a first lateral side surface of the major side surface and the first major surface toward an opposite second end of the first major cutting edge; and When viewed in a side view of the cutting insert along a first imaginary reference axis toward the major side surface, a second major cutting edge associated with the major side surface is inclined inwardly toward the median plane when viewed in a direction from a first end of the second major cutting edge located at an intersection between a second lateral side surface of the major side surface and the second major surface toward an opposite second end of the second major cutting edge. It has a shape like this.

[0025] This downward slope of the first and second major cutting edges counteracts the adverse effects associated with the axial plunge angle required for double-sided negative cutting inserts. Due to the symmetry of the cutting insert, each of the second pair of major sides has a shape corresponding to the shape of each of the first pair of major sides.

[0026] According to another embodiment of the invention, each of the first pair of major sides comprises: When viewed in a side view of the cutting insert along a first imaginary reference axis toward the major side surface, a first major cutting edge associated with the major side surface: When moving in a direction from one of four corner side surfaces adjacent to a first lateral side surface of the main side surface toward one of four corner side surfaces adjacent to a second lateral side surface of the main side surface, medial to the median plane, so as to approach the median plane; along at least a portion of the first major cutting edge formed at an intersection between a first lateral side surface of the major side surface and the first major surface; and / or be inclined along at least a portion of the first major cutting edge formed at an intersection between a central side surface of the major side surface and the first major surface; and When viewed in a side view of the cutting insert along a first imaginary reference axis toward the major side surface, a second major cutting edge associated with the major side surface is: When moving in a direction from one of the four corner side surfaces adjacent to the second lateral side surface of the main side surface toward one of the four corner side surfaces adjacent to the first lateral side surface of the main side surface, medial to the median plane, so as to approach the median plane; along at least a portion of a second major cutting edge formed at an intersection between a second lateral side surface of the major side surface and the second major surface; and / or and a second major cutting edge formed at an intersection between a central side surface of the major side surface and the second major surface, the second major cutting edge being inclined along at least a portion of the second major cutting edge. It has a shape like this.

[0027] This downward slope of the first and second major cutting edges counteracts the adverse effects associated with the axial plunge angle required for double-sided negative cutting inserts. Due to the symmetry of the cutting insert, each of the second pair of major sides has a shape corresponding to the shape of each of the first pair of major sides.

[0028] Another embodiment of the present invention is each one of the first surface wiping edges extending essentially parallel to the median plane; and Each one of the second surface wiping edges extends essentially parallel to the median plane. It is characterized by:

[0029] Thus, each first surface-wiping edge has its extension in a plane essentially parallel to the median plane, and each second surface-wiping edge has its extension in another plane essentially parallel to the median plane.

[0030] Another embodiment of the present invention is the first major surface includes a substantially flat first tangential abutment surface, and each first corner cutting edge, at least a portion of each first surface-wiping edge closest to an adjacent first corner cutting edge, and at least a portion of each first main cutting edge closest to an adjacent first corner cutting edge are located farther from the median plane than the first tangential abutment surface; the second major surface includes a substantially flat second tangential abutment surface, and each second corner cutting edge, at least a portion of each second surface-wiping edge closest to an adjacent second corner cutting edge, and at least a portion of each second main cutting edge closest to an adjacent second corner cutting edge are located farther from the median plane than the second tangential abutment surface; It is characterized by:

[0031] Further advantageous features of the double-sided negative cutting insert according to the present invention will become apparent from the following description.

[0032] The invention also relates to a milling tool comprising at least one double-sided negative cutting insert of the type described above.

[0033] Further advantageous features of the milling tool according to the invention will become apparent from the following description.

[0034] Embodiments of the invention will now be described in greater detail, by way of example, with reference to the accompanying drawings, in which: [Brief explanation of the drawings]

[0035] [Figure 1a] 1 is a perspective view of a double-sided negative cutting insert according to one embodiment of the present invention; FIG. [Figure 1b] 10 is a perspective view of a double-sided negative cutting insert according to an embodiment of the present invention, from another direction. [Figure 1c] 1a and 1b, taken along a first imaginary reference axis; FIG. [Figure 1d] 1a and 1b, taken along a second imaginary reference axis; FIG. [Figure 1e] FIG. 2 is a plan view from above of the cutting insert of FIGS. 1a and 1b. [Figure 1f] FIG. 2 is a plan view from below of the cutting insert of FIGS. 1a and 1b. [Figure 1g] FIG. 1c is a cross-sectional view taken along line Ig-Ig. [Figure 2] 1 is a schematic view of a portion of a double-sided negative cutting insert according to one embodiment of the present invention. [Figure 3] 10 is a schematic view of a portion of a double-sided negative cutting insert according to an alternative embodiment of the present invention. [Figure 4a] FIG. 1B is a perspective view of a shim plate designed for use with the cutting insert of FIGS. 1a-1g. [Figure 4b] FIG. 4b is a side view of the shim plate of FIG. 4a. [Figure 5a] 1a to 1g are perspective views of a milling tool provided with cutting inserts according to the embodiment shown in FIGS. 1a to 1g, with one of the cutting inserts seen removed from its insert seat in the tool body of the milling tool. [Figure 5b] It is a detailed enlarged view of a part of FIG. 5a. [Figure 5c] It is a perspective view of the cutting insert and the shim plate shown in FIG. 5b from another direction. [Figure 5d] It is a plan view of the milling tool of FIG. 5a. [Figure 5e] It is a side view of the milling tool of FIG. 5a. [Figure 5f] It is a detailed enlarged view of a part of FIG. 5e.

Mode for Carrying Out the Invention

[0036] An embodiment of the double-sided negative cutting insert 1 according to the present invention is shown in FIGS. 1a to 1g. The cutting insert 1 is configured to be used for milling, and is configured to be used for a milling tool, for example, a milling tool 50 of the type shown in FIGS. 5a to 5e.

[0037] The cutting insert 1 has an essentially square basic shape and is rotatable within eight different working positions. The cutting insert 1 includes a first main surface 2 and a second main surface 3 that function as the top and bottom surfaces of the cutting insert and are disposed on opposite sides of the cutting insert. The first and second main surfaces 2 and 3 have an essentially square shape when viewed in a plan view of the cutting insert 1. The cutting insert has a central axis C extending between the first and second main surfaces 2 and 3. A median plane MP that constitutes a virtual plane extends perpendicular to the central axis C and in the middle between the first and second main surfaces 2 and 3 as shown in FIGS. 1c and 1d. The first and second main surfaces 2 and 3 are identical to each other within manufacturing tolerances.

[0038] In the illustrated embodiment, the cutting insert 1 is provided with a through hole 5 extending centrally through the cutting insert between the first and second major surfaces 2, 3. The through hole 5 is configured to receive a fastening element 6, for example in the form of a screw (see FIGS. 5a-5c), by which the cutting insert may be removably secured to an insert seat 54 of a milling tool 50. The central axis C of the cutting insert 1 coincides with the central axis of the through hole 5. The cutting insert 1 may alternatively lack the through hole 5, in which case the cutting insert is configured to be removably secured to an insert seat of a milling tool by suitable clamping means.

[0039] The outer peripheral surface 10 extends around the cutting insert 1 between the first and second major surfaces 2, 3 perpendicular to the median plane MP. The outer peripheral surface 10 includes four major side surfaces 11a-11d and four corner side surfaces 12, with each corner side surface 12 located between two adjacent major side surfaces 11a-11d. The major side surfaces include a first pair of major side surfaces 11a, 11c located opposite each other on two opposing sides of the cutting insert 1, and a second pair of major side surfaces 11b, 11d located opposite each other on two other opposing sides of the cutting insert. Thus, the two major side surfaces 11a, 11c of the first pair are located opposite each other on opposite sides of the central axis C of the cutting insert 1. Correspondingly, the two major side surfaces 11b, 11d of the second pair are located opposite each other on opposite sides of the central axis C of the cutting insert 1. The four major side surfaces 11a to 11d are identical to one another within manufacturing tolerances.

[0040] A first transverse plane TP1 constituting an imaginary plane extends midway between the two major side surfaces 11 a, 11 c of the first pair and includes the central axis C of the cutting insert 1. A second transverse plane TP2 further constituting an imaginary plane extends midway between the two major side surfaces 11 b, 11 d of the second pair and includes the central axis C of the cutting insert 1. The first and second transverse planes TP1, TP2 extend perpendicular to each other and intersect each other along the central axis C of the cutting insert 1. Each of the first pair of major sides 11a, 11c has 180° rotational symmetry about a first imaginary reference axis A1 (see FIG. 1c) extending along the intersection between the median plane MP and the second transverse plane TP2, and each of the second pair of major sides 11b, 11d has 180° rotational symmetry about a second imaginary reference axis A2 (see FIG. 1d) extending along the intersection between the median plane MP and the first transverse plane TP1.

[0041] The cutting insert 1 has the following cutting edge: four first main cutting edges 21 formed at intersections between the first main surface 2 and each of the four main side surfaces 11a to 11d; four second main cutting edges 31 formed at intersections between the second main surface 3 and each of the four main side surfaces 11a to 11d; four first surface wiping edges 22 formed at intersections between the first main surface 2 and each of the four main side surfaces 11a to 11d; four second surface wiping edges 32 formed at intersections between the second main surface 3 and each of the four main side surfaces 11a to 11d; four first curved corner cutting edges 23 formed at the intersections between respective ones of the four corner side surfaces 12 and the first main surface 2, each first curved corner cutting edge 23 being located between one of the first main cutting edges 21 and one of the first surface-wiping edges 22; four second curved corner cutting edges 33 formed at the intersection between a respective one of the four corner side surfaces 12 and the second main surface 3, each second curved corner cutting edge 33 being located between one of the second main cutting edges 31 and one of the second surface-wiping edges 32; Equipped with.

[0042] The cutting edges 21, 22, 23 located along the outer edge of the first major side 2 form four different first sets of cutting edges, each such first set of cutting edges comprising one first main cutting edge 21, one first curved corner cutting edge 23 located adjacent to the first main cutting edge, and one first surface-wiping cutting edge 22 located adjacent to the first curved corner cutting edge. The cutting edges 31, 32, 33 located along the outer edge of the second major side 3 form four different second sets of cutting edges, each such second set of cutting edges comprising one second main cutting edge 31, one second curved corner cutting edge 33 located adjacent to the second main cutting edge, and one second surface-wiping cutting edge 32 located adjacent to the second curved corner cutting edge. The cutting insert 1 is therefore provided with a total of eight different sets of cutting edges, each of which comprises a main cutting edge 21, 31 and a surface-wiping cutting edge 22, 32 with an intermediate curved corner cutting edge 23, 33. In each one of the different working positions of the cutting insert 1, one cutting edge of the eight different sets of cutting edges constitutes the active cutting edge of the cutting insert.

[0043] Each of the main side surfaces 11a-11d has a central side surface 14 extending between the first and second main surfaces 2, 3, a first lateral side surface 13 extending between the first and second main surfaces 2, 3 and adjacent to one of the four corner side surfaces 12, and a second lateral side surface 15 extending between the first and second main surfaces 2, 3 and adjacent to another of the four corner side surfaces 12, the first lateral side surface 13, the central side surface 14, and the second lateral side surface 15 being alternately arranged such that the central side surface 14 is located between the first lateral side surface 13 and the second lateral side surface 15. The central side surface 14 is adjacent to the first lateral side surface 13 at a first end and adjacent to the second lateral side surface 15 at an opposite second end. One of the first main cutting edges 21 extends along the first lateral side surface 13 and along at least a majority of the adjacent central side surface 14, one of the first surface wiping edges 22 extends along at least a portion of the second lateral side surface 15, one of the second main cutting edges 31 extends along the second lateral side surface 15 and along at least a majority of the adjacent central side surface 14, and one of the second surface wiping edges 32 extends along at least a portion of the first lateral side surface 13.

[0044] Each first major cutting edge 21 and each second major cutting edge 31 may extend along the entire associated central side surface 14 .

[0045] Each first surface-wiping edge 22 and each second surface-wiping edge 32 preferably extends along at least a majority of the associated second lateral side surface 15 and first lateral side surface 13, respectively, and may extend along the entire associated second lateral side surface 15 and first lateral side surface 13, respectively. In the embodiment shown in Figures 1a-1g, each one of the first surface-wiping edges 22 and each one of the second surface-wiping edges 32 extends parallel to, or at least essentially parallel to, the median plane MP.

[0046] The central side surface 14 of each major side surface 11a-11d is slightly recessed relative to the adjacent first and second lateral side surfaces 13, 15 of the same major side surface, which means that the central side surface 14 of each of the first pair of major side surfaces 11a, 11c is located closer to the first transverse plane TP1 than the first and second lateral side surfaces 13, 15 of the same major side surface, and the central side surface 14 of each of the second pair of major side surfaces 11b, 11d is located closer to the second transverse plane TP2 than the first and second lateral side surfaces 13, 15 of the same major side surface.

[0047] Each of the major side surfaces 11a to 11d has a shape such that, when viewed in cross section of the cutting insert 1 along the median plane MP, a first lateral side surface 13 of the major side surface extends along a first line L1, a central side surface 14 of the major side surface extends along a second line L2, and a second lateral side surface 15 of the major side surface extends along a third line L3, as shown in Figures 1g, 2, and 3.

[0048] The profile of one of the major side surfaces 11a-11d of a cutting insert 1 according to two alternative embodiments of the present invention, as viewed in cross section of the cutting insert along the median plane MP, is shown very diagrammatically in Figures 2 and 3. To more clearly show the unique shape of the major side surface, the scale of the vertical profile in Figures 2 and 3 has been greatly exaggerated relative to the scale of the horizontal profile in Figures 2 and 3.

[0049] The second line L2 has a first endpoint E1, where the second line L2 is adjacent to the first line L1 via the first endpoint E1, and a second endpoint E2, where the second line L2 is adjacent to the third line L3 via the second endpoint E2, and these first and second endpoints E1, E2 are located on an imaginary straight reference line RL extending between a first point P1, where the first line L1 is adjacent to one of the corner side surfaces 12 located adjacent to the first lateral side surface 13 of the major side surface, and a second point P2, where the third line L3 is adjacent to one of the corner side surfaces 12 located adjacent to the second lateral side surface 15 of the major side surface. The second line L2 is recessed with respect to the imaginary straight reference line RL toward the central axis C of the cutting insert, and has a deepest portion 16 at its intermediate portion. The depth d of the second line L2 relative to the imaginary straight reference line RL gradually increases when viewed in the direction from the first endpoint E1 toward the deepest part 16 of the second line L2, and also gradually increases when viewed in the direction from the second endpoint E2 toward the deepest part 16 of the second line L2, and the depth d of the deepest part 16 of the second line L2 relative to the imaginary straight reference line RL is 0.01 to 0.15 mm, preferably 0.01 to 0.10 mm.

[0050] Each of the first pair of main sides 11a, 11c described above has a shape such that, when viewed in a side view of the cutting insert 1 along the first imaginary reference axis A1 toward this main side, the central side surface 14 of this main side has a length L along the median plane MP that corresponds to 35 to 75%, preferably 45 to 65%, of the width w of the cutting insert 1 measured along the median plane MP when viewed in this side view.

[0051] Each one of the major sides 11a-11d preferably has a shape such that a central side surface 14 of the major side is tangentially connected to a first lateral side surface 13 of the same major side and tangentially connected to a second lateral side surface 15 of the same major side.

[0052] The first and second lateral side surfaces 13, 15 of each major side surface 11a-11d may be formed as flat surfaces lying essentially in the same plane, where the above-mentioned first and second lines L1, L3 are both coplanar with an associated imaginary straight reference line RL, as shown schematically in Figure 3. However, the first and second lateral side surfaces 13, 15 of each major side surface 11a-11d are advantageously curved along at least a part of their extension when viewed in a cross-section of the cutting insert along the median plane MP, as shown schematically in Figure 2. In this case, the first lateral side surface 13 of each major side surface 11a-11d has a shape such that at least a portion of the first line L1 and at least a portion of the third line L3 project outward from an associated imaginary straight reference line RL, the height h of the highest portion 17 of the first line L1 and the height h of the highest portion 17 of the third line L3 relative to the associated imaginary straight reference line RL being 0.001 to 0.02 mm, and the highest portions 17 are provided on convex portions 18 (see Figures 1c and 1d) of the first lateral side surface 13 and the second lateral side surface 15, respectively. The second surface wiping edge 32 associated with the first lateral side surface 13 extends along at least a portion of the convex portion 18 of the first lateral side surface 13, preferably beyond the highest portion 17 of the first lateral side surface. In a corresponding manner, the first surface wiping edge 22 associated with the second lateral side surface 15 extends along at least a portion of the convex portion 18 of the second lateral side surface 15, and preferably beyond the highest portion 17 of the second lateral side surface.

[0053] The radius of curvature of the convex portion 18 of the first and second lateral side surfaces 13, 15 is at least 25 mm, preferably 25 to 600 mm, more preferably 40 to 100 mm, and / or It is 2 to 10 times, preferably 3 to 7 times, the width w of the cutting insert 1, the width w of the cutting insert being measured along the median plane MP in a side view of the cutting insert 1 as seen along the first imaginary reference axis A1.

[0054] The central side surface 14 of each of the major side surfaces 11a to 11d has at least one recess 19 (see FIGS. 1c and 1d) that is concave when viewed in a cross section of the cutting insert 1 along the median plane MP, and the radius of curvature of this at least one recess 19 is 25 to 200 mm, preferably 50 to 170 mm, and / or It is 2 to 16 times, preferably 3 to 13 times, the width w of the cutting insert measured along the median plane MP in a side view of the cutting insert 1 seen along the first imaginary reference axis A1.

[0055] In the embodiment shown in Figures 1a-1g, the central portion 20 of the central side surface 14 of each major side surface 11a-11d is flat or at least essentially flat, and this flat central portion 20 is adjacent to two recesses 19 in the central side surface 14 located on either side of the central portion 20.

[0056] Each of the first and second major cutting edges 21, 31 is preferably inclined toward the median plane MP as shown in Figures 1c and 1d. In this case, each of the first pair of major side surfaces 11a, 11c is When viewed in a side view of the cutting insert 1 along the first imaginary reference axis A1 toward this major side surface (i.e., in the side view shown in FIG. 1c), the first main cutting edge 21 on this major side surface is inclined inwardly toward the median plane MP when viewed in a direction from a first end of this first main cutting edge 21 located at the intersection between the first lateral side surface 13 of this major side surface and the first main face 2 toward an opposite second end of this first main cutting edge 21; and When viewed in a side view of the cutting insert 1 along the first imaginary reference axis A1 toward this major side surface, the second major cutting edge 31 associated with this major side surface is inclined inwardly toward the median plane MP when viewed in a direction from a first end of this second major cutting edge 31 located at the intersection between the second lateral side surface 15 of this major side surface and the second major surface 3 toward an opposite second end of this second major cutting edge 31. It has a shape like this.

[0057] The first major surface 2 comprises a substantially flat first tangential abutment surface 7a, and the second major surface 3 comprises a substantially flat second tangential abutment surface 7b. In the illustrated embodiment, each first corner cutting edge 23, at least a portion of each first surface-wiping edge 22 closest to an adjacent first corner cutting edge 23, and at least a portion of each first main cutting edge 21 closest to an adjacent first corner cutting edge 23 are positioned further away from the median plane MP than the first tangential abutment surface 7a, and therefore are located at a higher height than the first tangential abutment surface 7a when the cutting insert 1 is positioned with the first major surface 2 facing upward. Correspondingly, each second corner cutting edge 33, at least a portion of each second surface-wiping cutting edge 32 closest to an adjacent second corner cutting edge 33, and at least a portion of each second main cutting edge 31 closest to an adjacent second corner cutting edge 33 are positioned farther from the median plane MP than the second tangential abutment surface 7b, and are therefore located at a higher height than the second tangential abutment surface 7b when the cutting insert 1 is positioned with the second main surface 3 facing upward.

[0058] In the illustrated embodiment, shoulders 8 are provided on the first and second major surfaces 2, 3, with the shoulder 8 on the first major surface 2 located inboard near one of the first surface wiping edges 22 and the shoulder 8 on the second major surface 3 located inboard near one of the second surface wiping edges 32. Each shoulder 8 has a substantially flat top surface 9. The top surfaces 9 of the shoulders 8 on the first major surface 2 lie in a common plane parallel to the median plane MP. The top surfaces 9 of the shoulders 8 on the second major surface 3 also lie in a common plane parallel to the median plane MP. The top surface 9 of the shoulder 8 on the first major surface 2 constitutes the highest portion of the first major surface, i.e., the portion of the first major surface 2 located furthest from the median plane MP. Correspondingly, the top surface 9 of the shoulder 8 on the second main surface 3 constitutes the highest part of the second main surface, i.e., the part of the second main surface 3 that is located furthest from the median plane MP. Thus, in this case, the tangential abutment surfaces 7a, 7b on each one of the first and second main surfaces 2, 3 are located at a lower height than the top surface 9 of the shoulder 8 on the same main surface, i.e., inside an imaginary plane that is coplanar with the top surface 9 of the shoulder 8 on the same main surface.

[0059] 5a-5f show a milling tool 50 in the form of an end mill tool that can be used, for example, for shoulder milling or face milling. The milling tool 50 includes a tool body 51 and is configured to rotate about a rotation axis 52. The tool body 51 has a rear end 51a and an opposite front end 51b. A longitudinal axis 53 of the tool body 51 extends between the rear end 51a and the front end 51b of the tool body, and the longitudinal axis 53 coincides with the rotation axis 52 of the milling tool 50. At the rear end 51a, the tool body 51 is attached, for example, via a tool holder, to a rotating spindle of a milling machine or the like. At the front end 51b, the tool body 51 is provided with an insert seat 54 for receiving a cutting insert 1. In the example shown, the tool body 51 is provided with eight insert seats 54, evenly distributed around the longitudinal axis 53 of the tool body and configured to receive respective cutting inserts 1. However, the tool body 51 may alternatively be provided with any other suitable number of insert seats 54, in particular depending on the diameter of the tool body. A tool body with a small diameter may be provided with, for example, two insert seats, and a tool body with a large diameter may be provided with more than eight insert seats.

[0060] A cutting insert 1 is mounted in each one of the insert seats 54 of the tool body 51. In the embodiment shown in Figures 5a-5f, the milling tool 50 is provided with cutting inserts 1 of the type shown in Figures 1a-1g. Each cutting insert 1 is configured to be removably mounted in its associated insert seat 54. Each insert seat 54 is provided with a flat tangential support surface 56. Each cutting insert 1 may be designed with tangential abutment surfaces on its first and second major faces 2, 3 that are configured to be in direct contact with the tangential support surface 56 of the associated insert seat 54. However, in the illustrated embodiment, a shim plate 40 is disposed between the tangential support surface 56 and the cutting insert 1. This shim plate 40 is removably secured to the tangential support surface 56 by a tubular screw 41 that extends through a through hole 42 in the shim plate 40 and is engaged in a threaded hole 55 in the tangential support surface 56 of the insert seat. In the illustrated embodiment, each cutting insert 1 is fixed to its associated insert seat 54 by a fastening element 6 in the form of a screw, which extends through a through hole 5 in the cutting insert 1 and engages in a threaded hole 43 in a tubular thread 41 of a shim plate 40 mounted in the insert seat. As mentioned above, each cutting insert 1 is provided with a flat tangential abutment surface 7 a, 7 b on each one of its first and second main faces 2, 3, the tangential abutment surface 7 a, 7 b on the main face 2, 3 currently facing the shim plate 40 being configured to abut against a flat tangential support surface 44 on the shim plate 40 when the cutting insert 1 is mounted in its insert seat 54 in one of its working positions.

[0061] Each insert seat 54 is also provided with a radial support surface 57 and an axial support surface 58 .

[0062] In each one of the different working positions of the cutting insert 1, the first and second lateral side surfaces 13, 15 of one of the main side surfaces 11a-11d jointly function as an axial abutment surface of the cutting insert and are configured to abut against the axial support surface 58 of the associated insert seat 54, and at the same time, the first and second lateral side surfaces 13, 15 of another one of the main side surfaces 11a-11d jointly function as a radial abutment surface of the cutting insert and are configured to abut against the radial support surface 57 of the associated insert seat 54.

[0063] FIG. 5f shows a portion of a cutting insert 1 of the type shown in FIGS. 1a-1g mounted in an insert seat 54 of a milling tool 50 in one of its eight working positions. The cutting insert 1 shown in FIG. 5f therefore has a slightly recessed central side surface 14 on each one of the major side surfaces 11a-11d. The approximate location of the active main cutting edge of a corresponding cutting insert having flat major side surfaces is shown in FIG. 5f by the dashed line BL. It can be seen in FIG. 5f that the approach angle α is very close to 90° for the cutting insert 1 of the type shown in FIGS. 1a-1g, while the approach angle α' for a corresponding cutting insert having conventional flat major side surfaces would deviate further from the desired 90° value.

[0064] Of course, the present invention is in no way limited to the above-described embodiments, but on the contrary, many possibilities for modification thereof will be apparent to those skilled in the art without departing from the basic concept of the invention as defined in the appended claims.

Claims

1. A double-sided negative cutting insert for use in milling, wherein the cutting insert (1) has an essentially square basic shape, is rotatable within eight different working positions, and The cutting insert (1) has first and second main surfaces (2, 3) which are arranged on opposing sides of the cutting insert (1) and function as the top and bottom surfaces of the cutting insert, wherein the cutting insert (1) has a central axis (C) extending between the first and second main surfaces (2, 3), and a median plane (MP) extending perpendicular to the central axis (C) to the middle of the first and second main surfaces (2, 3), and the cutting insert (1) has rotational symmetry of 90° about the central axis (C), the first and second main surfaces (2, 3), Extending substantially perpendicular to the median plane (MP) around the cutting insert (1) between the first and second main surfaces (2, 3), and Four main surfaces (11a to 11d), wherein a first pair of the four main surfaces (11a to 11d) is arranged facing each other on two opposing sides of the cutting insert (1), and a second pair of the four main surfaces (11a to 11d) is arranged facing each other on two other opposing sides of the cutting insert (1), and the cutting insert (1) has a first cross section (TP1) that extends midway between the two main surfaces (11a to 11d) of the first pair and encompasses the central axis (C) of the cutting insert, and the two main surfaces (11a to 11d) of the second pair 1d) has a second cross-section (TP2) that extends midway between and encompasses the central axis (C) of the cutting insert, and each of the first pair of main surfaces (11a, 11c) has 180° rotational symmetry about a first virtual reference axis (A1) that extends along the intersection line between the median plane (MP) and the second cross-section (TP2), and each of the second pair of main surfaces (11b, 11d) has 180° rotational symmetry about a second virtual reference axis (A2) that extends along the intersection line between the median plane (MP) and the first cross-section (TP1), and four main surfaces (11a to 11d), and Each of the four corner side surfaces (12) is positioned between two adjacent main side surfaces (11a to 11d). An outer peripheral surface (10) having, Four first main cutting edges (21) are formed at the intersection between each of the four main surfaces (11a to 11d) and the first main surface (2), Four second main cutting edges (31) are formed at the intersection between each of the four main surfaces (11a to 11d) and the second main surface (3), Four first surface wiping cutting blades (22) are formed at the intersection between each of the four main surfaces (11a to 11d) and the first main surface (2), Four second surface wiping cutting blades (32) are formed at the intersection between each of the four main surfaces (11a to 11d) and the second main surface (3), Four first curved corner cutting edges (23) are formed at the intersection between each of the four corner side surfaces (12) and the first main surface (2), wherein each of the four first curved corner cutting edges (23) is located between one of the first main cutting edges (21) and one of the first surface wiping cutting edges (22), Four second curved corner cutting edges (33) are formed at the intersection between each of the four corner side surfaces (12) and the second main surface (3), wherein each of the four second curved corner cutting edges (33) is located between one of the second main cutting edges (31) and one of the second surface wiping cutting edges (32), In a double-sided negative cutting insert, Each of the main surfaces (11a to 11d) comprises a central side surface (14) extending between the first and second main surfaces (2, 3), a first lateral side surface (13) extending between the first and second main surfaces (2, 3) and adjacent to one of the four corner side surfaces (12), and a second lateral side surface (15) extending between the first and second main surfaces (2, 3) and adjacent to another of the four corner side surfaces (12), wherein the first lateral side surface (13), the central side surface (14), and the second lateral side surface (15) are arranged in order such that the central side surface (14) is located between the first lateral side surface (13) and the second lateral side surface (15). One of the first main cutting edges (21) extends along the first lateral surface (13) and along at least a large portion of the central surface (14), One of the first surface wiping cutting blades (22) extends along at least a portion of the second lateral surface (15), One of the second main cutting edges (31) extends along the second lateral surface (15) and along at least a large portion of the central surface (14), and One of the second surface-wiping cutting blades (32) extends along at least a portion of the first lateral surface (13), and When viewed in cross-section along the median plane (MP), each of the main surfaces (11a to 11d) is arranged such that the first lateral surface (13) of the main surface extends along the first line (L1), the central surface (14) of the main surface extends along the second line (L2), and the second lateral surface (15) of the main surface extends along the third line (L3). The second line (L2) has a first endpoint (E1) which is adjacent to the first line (L1) via the first endpoint (E1), and a second endpoint (E2) which is adjacent to the third line (L3) via the second endpoint (E2), and these first and second endpoints (E1, E2) are located on a virtual straight reference line (RL) that extends between the first point (P1) where the first line (L1) is adjacent to the corner surface (12) adjacent to the first lateral surface (13) of the main side surface, and the second point (P2) where the third line (L3) is adjacent to the corner surface (12) adjacent to the second lateral surface (15) of the main side surface. The second line (L2) is recessed relative to the virtual straight reference line (RL) toward the central axis (C) of the cutting insert, and has its deepest part (16) in the middle of the second line (L2), and The depth (d) of the second line (L2) relative to the virtual straight reference line (RL) gradually increases when viewed from the first endpoint (E1) toward the deepest part (16) of the second line (L2), and when viewed from the second endpoint (E2) toward the deepest part (16) of the second line (L2), and the depth (d) of the deepest part (16) of the second line (L2) relative to the virtual straight reference line (RL) is 0.01 to 0.15 mm. A double-sided negative cutting insert characterized by the following features.

2. The double-sided negative cutting insert according to claim 1, characterized in that each of the main sides (11a to 11d) has a shape such that the central side surface (14) of the main side is tangentially connected to the first lateral side surface (13) of the main side and tangentially connected to the second lateral side surface (15) of the main side.

3. The double-sided negative cutting insert according to claim 1, characterized in that each of the first pair of main sides (11a, 11c) has a shape such that, when viewed in a side view of the cutting insert (1) along the first virtual reference axis (A1) toward the main side (11a, 11c), the central side surface (14) of the main side has a length (L) along the median plane (MP) that corresponds to 35 to 75% of the width (w) of the cutting insert (1) measured along the median plane (MP) when viewed in this side view.

4. The first lateral surface (13) of each main side surface (11a to 11d) has a shape such that at least a portion of the first line (L1) protrudes outward from the associated virtual straight reference line (RL), the height (h) of the highest part (17) of the first line (L1) relative to the associated virtual straight reference line (RL) is 0.001 to 0.02 mm, and this highest part (17) is located on a convex portion (18) of the associated first lateral surface (13), and The second lateral surface (15) of each main side surface (11a to 11d) has a shape such that at least a portion of the third line (L3) protrudes outward from the associated virtual straight reference line (RL), the height (h) of the highest part (17) of the third line (L3) relative to the associated virtual straight reference line (RL) is 0.001 to 0.02 mm, and this highest part (17) is located on a convex portion (18) of the associated second lateral surface (15). A double-sided negative cutting insert according to claim 1, characterized by the above.

5. The second surface-wiping cutting edge (32) associated with the first lateral surface (13) of each main side (11a to 11d) extends along at least a portion of the protrusion (18) of the first lateral surface (13), and The first surface-wiping cutting edge (22) associated with the second lateral surface (15) of each main side surface (11a to 11d) extends along at least a portion of the protrusion (18) of the second lateral surface (15). A double-sided negative cutting insert according to claim 4, characterized by the above.

6. The radius of curvature of the protrusion (18) on the first lateral surface (13) is at least 25 mm, and The radius of curvature of the protrusion (18) on the second lateral surface (15) is at least 25 mm. A double-sided negative cutting insert according to claim 4, characterized by the above.

7. The radius of curvature of the protrusion (18) on the first lateral surface (13) is 2 to 10 times the width (w) of the cutting insert (1), and The radius of curvature of the protrusion (18) on the second lateral surface (15) is 2 to 10 times the width (w) of the cutting insert (1). It is characterized by, The width (w) of the cutting insert is measured along the median plane (MP) in the side view of the cutting insert (1) as seen along the first virtual reference axis (A1). The double-sided negative cutting insert according to claim 4.

8. The first lateral surface (13) of each main side (11a to 11d) has a shape such that the first line (L1) is coplanar with the associated virtual straight reference line (RL), and The second lateral surface (15) of each main side surface (11a to 11d) has a shape such that the third line (L3) lies on the same plane as the associated virtual straight reference line (RL). A double-sided negative cutting insert according to claim 1, characterized by the above.

9. The double-sided negative cutting insert according to claim 1, characterized in that the central side surface (14) of each main side surface (11a to 11d) has at least one concave recess (19) when viewed in cross-section of the cutting insert (1) along the median plane (MP).

10. The radius of curvature of the recess (19) is 25–200 mm, and / or The width (w) of the cutting insert (1) measured along the median plane (MP) in the side view of the cutting insert (1) as seen along the first virtual reference axis (A1) is 2 to 16 times the width (w) of the cutting insert (1). A double-sided negative cutting insert according to claim 9, characterized in that

11. Each first surface-wiping cutting edge (22) extends along at least a large portion of the associated second lateral surface (15), and Each second surface-cleaning cutting edge (32) extends along at least a large portion of the associated first lateral surface (13). A double-sided negative cutting insert according to claim 1, characterized by the above.

12. Each of the first pair of main surfaces (11a, 11c) is When viewed in a side view of the cutting insert (1) along the first virtual reference axis (A1) toward the main side surfaces (11a, 11c), the first main cutting edge (21) associated with the main side surface is inclined inward toward the median plane (MP) when viewed from the first end of the first main cutting edge (21) located at the intersection between the first lateral surface (13) of the main side surface and the first main surface (2) toward the second end opposite the first main cutting edge (21), and When viewed in a side view of the cutting insert (1) along the first virtual reference axis (A1) toward the main side surfaces (11a, 11c), the second main cutting edge (31) associated with the main side surface is inclined inward toward the median plane (MP) when viewed from the first end of the second main cutting edge (31) located at the intersection between the second lateral surface (15) of the main side surface and the second main surface (3) toward the second end on the opposite side of the second main cutting edge (31). A double-sided negative cutting insert according to claim 1, characterized by having such a shape.

13. Each of the first pair of main surfaces (11a, 11c) is When viewed in a side view of the cutting insert (1) along the first virtual reference axis (A1) toward these main sides (11a, 11c), the first main cutting edge (21) associated with these main sides is, When transitioning from one of the four corner surfaces (12) adjacent to the first lateral surface (13) of this main surface toward one of the four corner surfaces (12) adjacent to the second lateral surface (15) of this main surface, To approach the median plane (MP), inward toward the median plane (MP), Along at least a portion of this first main cutting edge (21) formed at the intersection between the first lateral surface (13) and the first main surface (2) of this main surface, and / or At least a portion of the first main cutting edge (21) formed at the intersection between the central side surface (14) of the main side surface and the first main surface (2) is inclined along, When viewed in a side view of the cutting insert (1) along the first virtual reference axis (A1) toward these main sides (11a, 11c), the second main cutting edge (31) associated with these main sides is, When transitioning from one of the four corner surfaces (12) adjacent to the second lateral surface (15) of this main surface toward one of the four corner surfaces (12) adjacent to the first lateral surface (13) of this main surface, To approach the median plane (MP), inward toward the median plane (MP), Along at least a portion of this second main cutting edge (31) formed at the intersection between the second lateral surface (15) and the second main surface (3) of this main surface, and / or At least a portion of this second main cutting edge (31) is inclined along the intersection between the central side surface (14) of this main side surface and the second main surface (3). A double-sided negative cutting insert according to claim 1, characterized by having such a shape.

14. Each of the first surface-wiping cutting blades (22) extends essentially parallel to the median plane (MP), and Each of the second surface-wiping cutting blades (32) extends essentially parallel to the median plane (MP). A double-sided negative cutting insert according to claim 1, characterized by the above.

15. The double-sided negative cutting insert according to claim 1, characterized in that the cutting insert (1) is provided with a through hole (5) that extends to the center through the cutting insert between the first and second main surfaces (2, 3), and the central axis of the through hole (5) coincides with the central axis (C) of the cutting insert (1).

16. The first main surface (2) comprises a substantially flat first tangential contact surface (7a), and at least a portion of each first corner cutting edge (23), each first surface-cleaning cutting edge (22) closest to an adjacent first corner cutting edge (23), and at least a portion of each first main cutting edge (21) closest to an adjacent first corner cutting edge (23) are positioned further away from the median plane (MP) than the first tangential contact surface (7a), and The second main surface (3) comprises a substantially flat second tangential contact surface (7b), and at least a portion of each second corner cutting edge (33), each second surface-cleaning cutting edge (32) closest to an adjacent second corner cutting edge (33), and at least a portion of each second main cutting edge (31) closest to an adjacent second corner cutting edge (33) are positioned further away from the median plane (MP) than the second tangential contact surface (7b). A double-sided negative cutting insert according to claim 1, characterized by the above.

17. The double-sided negative cutting insert according to claim 1, characterized in that, at each of the different working positions of the cutting insert (1), one of the first and second lateral surfaces (13, 15) of the main side surfaces (11a to 11d) is configured to function in conjunction as an axial contact surface of the cutting insert (1), and at the same time, another of the first and second lateral surfaces (13, 15) of the main side surfaces (11a to 11d) is configured to function in conjunction as a radial contact surface of the cutting insert (1).

18. The double-sided negative cutting insert according to claim 1, characterized in that the cutting insert (1) is a right-angle shoulder milling insert or a face milling insert.

19. A milling tool comprising at least one double-sided negative cutting insert (1) according to any one of claims 1 to 18.

Images