RU2707373C1 - Disc mill for processing of narrow slots and cutting plate for it with wear-resistant coating - Google Patents

Abstract

FIELD: technological processes.SUBSTANCE: group of inventions relates to a composite cutting tool and can be used for processing of narrow slots with disk mills. Cutting plate body comprises at least three structural elements radially arranged and symmetrically spaced apart in circle with alternation with base sectors, lower and upper surfaces between which a side surface is located. It includes tangentially and radially located rear and front surfaces, at the intersection of which cutting edges are formed. Wear-resistant non-uniform thickness coating is applied on upper, side and at least part of lower surface, which thickness in cross sections on rear and front surfaces is more than thickness on lower base surface located closer to middle plane passing through middle of cutting plate in its side view. Thickness of wear-resistant coating on upper and lower surfaces is proportional to distance in radial direction from axis of symmetry of cutting plate to its side surface, and on upper surface at equal distances from side surface it is more than on lower base surface.EFFECT: higher durability of disk cutters.9 cl, 12 dwg

Description

The field of technology.

The present invention includes a group of inventions and relates to the field of processing materials by cutting, in particular to a prefabricated cutting tool, namely, disk mills for processing narrow grooves and cutting inserts thereto.

The level of technology.

Details of modern aircraft contain narrow grooves, which, as a rule, have a wide range of widths and angular radial curves made at their bottom. For productive milling of these grooves, disk milling cutters are used with mechanical fastening of replaceable cutting inserts having different radius curves of the corner cutting edges and thickness.

In addition to technological requirements due to the shape and size of narrow grooves, the considered mills are subject to increased requirements for the mechanical strength of their bodies and cutting inserts having a small thickness, which significantly affects the strength of the plates and the conditions for their fastening in the slots of the mill body.

During the milling of narrow grooves, especially in products made of difficult to process materials, for example, titanium alloys, the cutting inserts are subjected to enhanced thermomechanical action, which leads to a complex stress-strain state of the cutting edges and the cutting inserts themselves. This must be taken into account in the design of both the nests for fixing the inserts and the cutting inserts themselves. At the same time, in conditions of limited overall dimensions of the cutting inserts and their attachment points, it is necessary to ensure the mechanical strength of these structural elements and the reliability of the attachment of the inserts, while maintaining the maximum number of their cutting edges and effective cutting angles.

It is also important to ensure the possibility of using cutting inserts with different radius of curvature of the corner cutting edges with one housing of the disk cutter.

Known designs of disk cutters and cutting inserts for them (RU 2354510, RU 2313878, WO 2005/053888, B23C 5/08, 2005)), containing a housing in the form of a disk, on the periphery of which indexed tangential cutting inserts are installed in the nests. In this case, adjacent cutting inserts are placed in the nests on opposite end faces of the housing, and their main cutting edges are overlapped. Each nest has side base surfaces and a base, which is the base surface. A protrusion of a round or rectangular shape with a threaded hole can be made on it. This protrusion enters the recess of the insert. In this case, the cutting insert in each socket is fixed with a fixing screw through a mounting hole made in the central part of the socket and passing through the said protrusion.

The indicated design of disk cutters cannot be effectively used for milling grooves with a width of less than 4 mm. This is due to the fact that for milling these grooves, the milling cutters must have a thin body and cutting inserts, which significantly limits the size of the plate attachment site. At the same time, the thickness of the wall of the socket, in which a threaded hole is made for the screw securing the cutting insert, is substantially reduced. To eliminate this drawback in known designs, these threaded holes are performed, for example, in a special cylindrical or rectangular protrusion located at the bottom of the socket, which can additionally cause a decrease in the thickness of its bottom and, as a result, a decrease in the rigidity of the part of the housing adjacent to the base of the socket for cutting plate. Moreover, this protrusion should be included in the recess of the cutting insert, the thickness and overall dimensions of which are also limited. In addition, the base of the cutting inserts on the protruding parts of their U-shape, covering the protrusions on the bottom of the nests in the body of the cutters, significantly increases the load on the cutting inserts in the area of their mounting holes, which with a small thickness of the cutting inserts can cause their destruction.

Reducing the body width of the milling cutters also imposes restrictions on the dimensions of the lateral base surfaces of the nests for attaching the cutting inserts. This is due to the fact that, firstly, due to the reduction in the width of the cutter body, the width of the side base surfaces of the nests decreases, and secondly, with the usual rectangular design of the cutting inserts, it is necessary to reduce the dimensions of the cutting inserts to ensure effective cutting angles. This additionally reduces the dimensions of the lateral base surfaces of the nests and, thereby, reduces the strength of the body and the rigidity of the fixing of the cutting inserts, which significantly affects the performance of the cutters as a whole.

Known for the design of a tool for milling grooves and a plate for milling grooves for it (RU 2508966). The tool contains a plate for milling grooves mounted on the edge of the holder. The plate includes a first side surface, a second side surface and a plurality of edge surfaces between the first and second side surfaces. Each edge surface intersects with another edge surface in the corner and forms a cutting edge. The first and second side surfaces have a lateral supporting surface of the plate for abutment to the supporting surface of the holder (socket). The plate has mirror symmetry with respect to the central plane, extending through the edge surfaces in the middle between the first and second side surfaces.

The disadvantage of this design is that it does not take into account the asymmetric loading of the main cutting edge of the cutting insert, which forms, together with the angular cutting edge, the bottom of the milled groove with an angular radial rounding. This leads to an additional bending moment on the cutting insert in the area of the mounting hole, reduces their stability, can cause additional vibrations and requires an increase in the mechanical strength of the cutting inserts and the cutter body by increasing the dimensions of the attachment site.

Known designs of disk cutters and cutting inserts for them (US 20137129433 A1, RU 2584625). In this case, the cutting insert contains a housing with a central part where the hole is made. The axis of this hole is the axis of symmetry and rotation of the plate. In this case, the plate body includes at least three radially located and symmetrically spaced around the circle with sequential alternation with the basic sectors and the transition to them of the housing elements. The cutting insert also contains a lower base and upper surface, between which there is a side surface, including tangentially and radially located surfaces for each housing element, at the intersection of which there are cutting edges, including the main and auxiliary cutting edges.

In these structures, disk milling cutters comprise a housing in the form of a disk with a working part located around the axis of rotation, sockets made in the housing and located alternately on one and the other side of the housing. Moreover, each socket has a supporting base surface, side base surfaces and a hole for mounting screws. In the sockets, the cutting inserts described above are mounted and fixed with screws.

These design of disk milling cutters allow you to save a large number of cutting edges with effective cutting front angles with sufficiently large dimensions of the cutting inserts, but do not provide their reliable fastening for narrow, in particular less than 4 mm, mills.

They also do not take into account the asymmetric loading of the main cutting edge of the cutting insert, which forms, together with the corner cutting edge, the bottom of the milled groove with an angular radius curve.

Moreover, since the strength reserves of high-strength materials from which cutting plates and disk mill bodies are made are largely exhausted, there is a need for new design solutions that address the properties of wear-resistant coatings together with the structural elements of the plates and their mounts in the disk mill frame, having residual compressive stresses, according to the principle used to increase the operational characteristics of mill bodies with mechanical fastening of cutting inserts (see, for example, patent RU 2691480).

The present invention is to create a design of cutting inserts with a wear-resistant coating, ensuring their reliable fastening in the case of disk cutters for processing narrow grooves with radial curves, while maintaining effective cutting front angles and the number of cutting edges.

The present invention is also the creation of a design of disk mills for processing narrow grooves with radius curves using the above cutting inserts, providing increased performance mills.

The specified technical result is achieved through a combination of features described in the relevant claims.

Disclosure of the invention.

In accordance with the present invention, the cutting insert comprises a housing with a central part where a hole is made, the axis of which is the axis of symmetry and rotation of the insert.

In this case, the plate body includes at least three radially located and symmetrically spaced around the circle with sequential alternation with the base sectors on which the tangential base surfaces are located, and the transition of the body elements into them.

The housing also includes a lower surface including a lower base and auxiliary surfaces, and an upper surface between which a side surface is located. It includes for each housing element tangentially and radially located surfaces, which are respectively the rear and front surfaces, at the intersection of which the cutting edges are located. They contain angular cutting edges, and a wear-resistant coating having an uneven thickness and containing at least one layer having residual compressive stresses is applied to the upper, lateral and at least part of the lower surface.

According to the invention, the thickness of the wear-resistant coating in its cross sections by a plane on the rear and front surfaces is greater than the thickness of the wear-resistant coating on the lower base surface, located closer to the middle plane M passing through the middle of the insert in its side view, than the upper surface and the auxiliary lower surfaces .

The thickness of the wear-resistant coating on the upper and lower surfaces is proportional to the distance in the radial direction from the symmetry axis of the cutting insert to its side surface, and the thickness of the wear-resistant coating on the upper surface at equal distances from the side surface is greater than on the lower base surface.

In accordance with one preferred embodiment of the cutting insert, its cutting edges comprise first and second sections, the lengths and angles of inclination of which to the middle plane M are not equal to each other, and the inclination of the first section is less than the angle of inclination of the second section.

In accordance with another preferred embodiment of the cutting insert, the wear-resistant coating comprises at least one layer that contains a phase with at least one of the elements V, Cr, Nb, Ti, Ta, Zr, Hf, B, Al, Si, C, N , Oh, while the thickness of the wear-resistant coating on the front and rear surfaces is selected from the range of 1.5 ... 4.5 microns.

In accordance with another preferred embodiment of the cutting insert, the auxiliary lower surfaces smoothly mate with the lower base surface.

In accordance with another preferred embodiment of the cutting insert, the mating surfaces are made as part of the lateral surface of imaginary truncated cones whose vertices coincide with the corresponding auxiliary lower surfaces.

In accordance with another preferred embodiment of the cutting insert in the housing elements from the side of the lower auxiliary surfaces, recesses are made, the side walls of which are part of the surface of the imaginary truncated cone, the reverse direction of the surface of the imaginary truncated cones of the mating surfaces of the auxiliary surfaces with the lower base surface.

In accordance with another preferred embodiment of the cutting insert, a portion of the lower base surface located around the mounting hole does not have a wear-resistant coating.

In accordance with another preferred embodiment of the cutting insert, recesses are made in the radial direction on the upper surface opposite the base sectors.

In accordance with the invention, a disk mill for processing narrow grooves is provided. It contains a housing in the form of a disk with a working part located around the axis of rotation. On the one and the other side of the housing, sockets for fixing the cutting inserts made according to one of the above versions are arranged and arranged alternately. Moreover, each socket has a supporting surface, side base surfaces and an opening for mounting screws.

The lower base surfaces of the cutting inserts are in contact with the supporting surfaces of the nests, made in the form of sectors alternating with recesses, which include the lower parts of the housing elements of the cutting plates protruding relative to the lower base surfaces.

A brief description of the drawings.

For a better understanding, but only as an example, the invention will be described with reference to the attached drawings, which depict a disk mill for processing narrow grooves and a cutting insert for it. Wherein:

in FIG. 1 shows a perspective view of a cutting insert;

in FIG. 2 shows a top view of the insert shown in FIG. one;

in FIG. 3 shows a side view of the insert shown in FIG. one;

in FIG. 4 shows a bottom view of the insert shown in FIG. one;

in FIG. 5 shows a section along the line I-I of the insert shown in FIG. 2;

in FIG. 5a shows cross-sectional views of a fragment of a wear insert coated insert shown in FIG. 5, along lines III-III, IV-IV, V-V and VI-VI;

in FIG. 6 is a fragment of view II of the insert shown in FIG. 2;

in FIG. 7 shows a fragment of section II-II of the insert shown in FIG. 3

in FIG. 8 shows cross-sectional views of a fragment of a cutting insert with a wear-resistant coating depicted in FIG. 7, along lines VII-VII and VIII-VIII;

in FIG. 9 shows a side view of a disk mill for machining narrow grooves with the cutting insert shown in FIG. one;

in FIG. 10 is a perspective view of a socket in a disk cutter body for mounting the insert shown in FIG. one;

in FIG. 11 shows a housing slot of a disk cutter with a cutting insert fixed in it, shown in FIG. one;

in FIG. 12 shows a section along the line AA of the socket of the disk cutter body with the cutting insert fixed in it, shown in FIG. one.

DETAILED DESCRIPTION OF THE INVENTION

Consider the proposed design of the wear plate 10 with a wear-resistant coating depicted in FIG. 1-8. It contains a housing 12 with a central part 14, where the hole 16 is made. The axis 18 of this hole is the axis of symmetry and rotation of the plate.

In this case, the plate body 12 includes at least three radially spaced and symmetrically spaced around the circle with sequential alternation with the base sectors 22, on which the tangential base surfaces 22a are located, and the case elements 20 transition into them.

The housing 12 also includes a lower surface including a lower base 24 and auxiliary surfaces 24a, and an upper surface 26, between which a side surface 28 is located.

It includes for each housing element 20 tangentially and radially spaced surfaces, which are respectively the rear 30 and front 32 surfaces. At the intersection of these surfaces, cutting edges 36 are located. They have angular cutting edges 36a. Moreover, a wear-resistant coating 42 is applied to the upper 26, lateral 28, and at least part of the lower base surface 24. It has an uneven thickness and contains at least one layer having residual compressive stresses.

According to the invention, the thickness of the wear-resistant coating 42 in its cross sections by a plane on the rear 30 and front 32 surfaces is greater than the thickness of the wear-resistant coating 42 on the lower base surface 24 located closer to the middle plane M passing through the middle of the cutting insert 10 in its side view, than the upper surface 26 and the auxiliary lower surfaces 24a.

In particular, in FIG. 5 and 5a show cross sections of the wear-resistant coating 42 along lines III-III, IV-IV, V-V and VI-VI, respectively, of the upper surface 26, the rear surface 30, the lower base surface 24 and the auxiliary lower surface 24a. In FIG. 7 and 8 show cross-sections of the wear-resistant coating 42 along the lines VII-VII and VIII-VIII of the rear surface 30 and the front surface 32 of the cutting insert 10.

Moreover, from FIG. 5a that the thickness of the wear-resistant coating 42 on the rear surface 30 h4 and the front surface 32 h7 and h8 (Fig. 8) is greater than the thickness of the wear-resistant coating h5 of the lower base surface 24.

These design features of the proposed cutting insert allow to obtain the planned technical result. Due to the fact that the wear-resistant coating applied to the surface of the cutting insert has residual compressive mechanical stresses, compression forces act on the cutting insert. In this case, the stress-strain state of the cutting insert until it is fixed in the slots of the disk cutter for processing narrow grooves will depend on the shape and size of its individual structural elements and their relative position, and on the thickness of the wear-resistant coating on these elements.

In turn, when choosing the thickness of the wear-resistant coating applied to individual elements of the cutting insert, it is necessary to take into account, on the one hand, the features of loading of the working surfaces of the insert that are subject to contact loads that occur during cutting, and on the other hand, the loads that occur when the cutting insert is fixed in the nests disk mills.

So in this design, the front 32 and rear 30 surfaces are part of the side surface of the cutting insert and in this case are subject to the greatest contact loads and wear that occur during the cutting process. Therefore, on these surfaces the largest thickness of the wear-resistant coating is required. In this case, the compressive forces arising on the side surfaces of the cutting inserts contribute to increasing their rigidity.

At the same time, since the cutting edges 36 of the inserts 10 have angular cutting edges 36a, the casing 12 and its casing elements 20 located cantilever are subjected to additional loads, which cause tensile forces on the upper surface 26 and are compressive on the lower base surface 24 of the cutting plates. Thus, the upper 26 and lower surface 24 of the cutting insert 10 have different loads.

Such features of the loading of the cutting insert are taken into account in the proposed design as follows. The thickness of the wear-resistant coating 42 on the upper 26 and lower base 24 surfaces is proportional to the distance in the radial direction from the axis of symmetry 18 of the cutting insert 10 to its side surface 28, and the thickness of the wear-resistant coating 42 on the upper surface 26 at equal distances from the side surface 28 is greater than lower base surface 24.

The different thicknesses of the wear-resistant coating 42 h3 and h5, respectively, on the upper 26 and lower base 24 surfaces are visible in FIG. 5 and 5a, with h3> h5.

This also makes it possible to increase the rigidity of the cutting insert due to a certain compensation of the action of tensile forces on the upper surface. Moreover, this is especially effective provided that the lower base surface 24 is located closer to the middle plane M passing through the middle of the cutting insert 10 in its side view than the upper surface 26 and the auxiliary lower surfaces 24a.

In this case, unlike analogues of cutting inserts, where they have, for example, a U-shaped design that significantly affects the strength of the inserts when they are fixed in the slots of the cutter body, in the proposed design, the inserts are based directly on the lower base surface 24 located directly in the area of the mounting holes 16, which makes it possible to use plates with a minimum thickness.

The residual compressive stresses in the wear-resistant coating largely depend on its elemental composition, therefore, in accordance with one of the preferred versions of the cutting insert, the wear-resistant coating contains at least one layer that contains a phase with at least one of the elements V, Cr, Nb, Ti , Ta, Zr, Hf, B, Al, Si, C, N, O, while the thickness of the wear-resistant coating on the front and rear surfaces is selected from the range of 1.5 ... 4.5 microns.

The minimum and maximum value of the specified thickness range is due to the need to ensure the strength of the coating and create sufficient compression forces.

In accordance with one preferred embodiment of the proposed design of the cutting insert, its cutting edges 36 contain first 38 and second 40 sections, the lengths L1 and L2 and the angles of inclination α and β, respectively, which are not equal to the middle plane M (Fig. 6). Moreover, the angle of inclination α of the first section 38 is less than the angle of inclination β of the second section 40.

The specified design feature contributes to the achievement of the planned technical result, and also allows the manufacture of cutting inserts with a wide range of radii of curvature of the corner cutting edges using a single mold, which significantly increases the efficiency of the proposed design.

In accordance with another preferred embodiment of the proposed design of the cutting insert for providing its strength and rigidity necessary to implement the claimed technical result, the auxiliary lower surfaces 24a smoothly mate with the lower base surface 24. These mating surfaces 52 can be made as part of the side surface of imaginary truncated cones whose vertices coincide with the corresponding auxiliary lower surfaces 24a.

Also for this purpose, recesses 54 can be made in the housing elements from the side of the lower auxiliary surfaces, the side walls of which are part of the surface of the imaginary truncated cone, the reverse direction of the surface of the imaginary truncated cones of the mating surfaces 52 of the auxiliary surfaces 24a with the lower base surface 24. This also increases the area of the lower base surface 24, which can be used as a technological base for grinding plates.

According to another preferred embodiment, a part of the lower base surface 24 of the cutting inserts 10 located around the mounting hole 16 does not have a wear-resistant coating. This allows you to increase the effect of the preliminary stress state of the cutting inserts created due to the declared different thickness of the wear-resistant coating 42.

In accordance with another preferred embodiment of the cutting insert 10, recesses 26a are formed on its upper surface 24 in the radial direction opposite the base sectors 22. This allows you to increase the area of the upper surface 26 in the area of the base sectors 22 and thereby increase the effect of using different thicknesses of the wear-resistant coating 42, taking into account the protruding relative to the housing 12 of the housing elements 20.

Next, we consider the design of a disk mill for processing narrow grooves, which uses the cutting insert discussed above.

The disk mill for processing narrow grooves 56 contains a housing 58 in the form of a disk with a working part located around the axis of rotation 60.

Sockets 62 are alternately provided on the casing 58 from one and the other side thereof. Each socket has a supporting surface 64, side base surfaces 66 and an opening 68 for fixing screws 72.

According to the invention, the inserts 10 are mounted and secured with screws 72 on the inserts 10 in one of the above-mentioned versions.

In this case, the lower base surfaces 24 of the cutting inserts 10 are in contact with the supporting surfaces 64 of the sockets 62, made in the form of sectors 74, alternating with recesses 76, which include the lower parts of the housing elements protruding relative to the lower base surfaces 24. This allows a rigid design of the disk cutter for processing narrow grooves.

Features of the invention and a description of its work.

The uneven thickness of the wear-resistant coating on the surfaces of the cutting inserts 10 can, for example, be obtained as follows. When applying a wear-resistant coating on vacuum-arc spraying plants using the PVD method, the cutting inserts are placed in cassettes that perform planetary motion in the volume of the vacuum chamber. In this case, the axis of the holes of the plates should preferably be perpendicular to the axes of the plasma sources located horizontally in the chamber, and the cutting plates themselves additionally perform rotational movements relative to the cartridges.

In this case, the rotation speed of the plates relative to the cartridges performing planetary motion in the volume of the vacuum chamber is selected depending on the required thickness of the wear-resistant coating and the ratio of its thicknesses on the respective surfaces of the cutting plates.

This will ensure the greatest thickness of the wear-resistant coating on the front and rear surfaces and the smallest thickness on the lower base surface of the cutting inserts. Moreover, the thickness of the wear-resistant coating on the upper surface 26 will be less than on the front 32 and rear 30 surfaces, but more than on the lower surface 24. This will create a prestressed state of the cutting insert 10 provided by the present invention.

By changing the position of the cutting inserts relative to the plasma sources, for example, by changing the angle of inclination of the axis of the cutting plates relative to the axis of the plasma sources, it is also possible to change the ratio of the thicknesses of the wear-resistant coatings on the mentioned surfaces of the cutting plates, thereby achieving a change in the magnitude of the prestress of the plates.

Ready-to-use cutting inserts 10 are mounted in the nests 62 of the housings 58 of the milling cutters 56 and secured with screws 72. The tangential base surfaces 22a of the cutting inserts are in contact with the lateral base surfaces 66 of the nests 62 of the housings 58 of the milling cutters, and the lower base surface is in contact with the support the surface 64 of the nests 62, made in the form of sectors 74.

In the process of milling narrow grooves with radial curves, the forces acting on the cutting edges of the cutting inserts create the opposite stresses created during their manufacture. This makes it possible to use the developed design of milling cutters and cutting inserts for them under increased cutting conditions, ensuring reliable fastening of the inserts in the housing of disk milling cutters and maintaining effective cutting front angles and the number of cutting edges.

Although the present invention has been described with a certain degree of detail, it should be understood that its various changes and modifications can be made without departing from the essence and scope of the invention set forth in the claims below.

Claims (9)

1. A cutting insert with a wear-resistant coating (10), comprising a housing (12) with a central part (14) with a hole (16), the axis (18) of which is the axis of symmetry and rotation of the insert, while the insert housing (12) contains basic sectors (22) with tangential base surfaces (22a), at least three body elements (20), radially spaced and symmetrically spaced around the circle with sequential alternation with the base surfaces and transition into them, the lower surface, including the lower base (24) and auxiliary (24a) surfaces the upper surface (26), between which the side surface (28) is located, including for each case element (20) tangentially and radially spaced surfaces, which are respectively the rear (30) and front (32) surfaces, at the intersection of which the cutting edges (36 ) having angular cutting edges (36a), moreover, a wear-resistant coating (42) of uneven thickness, containing at least one layer with residual compressive stresses, is applied to the upper (26), side (28) and at least part of the lower surface characterized in that the thickness of the wear-resistant coating (42) in its cross sections on the rear (30) and front (32) surfaces is greater than the thickness of the wear-resistant coating (42) on the lower base surface (24), located closer to the middle plane ( M) passing through the middle of the cutting insert (10) in its side view than the upper surface (26) and the auxiliary lower surfaces (24a), while the thickness of the wear-resistant coating (42) on the upper (26) and lower (24) surfaces is proportional the distance in the radial direction from the axis of symmetry (18) plate (10) to its side surface (28), and the thickness of the wear-resistant coating (42) at equal distances from the side surface (28) is greater on the upper surface (26) than on the lower base surface (24). 2. The cutting insert (10) according to claim 1, characterized in that the cutting edges (36) contain the first (38) and second (40) sections, the lengths and angles of which are not equal to the middle plane (M), moreover the angle of inclination (α) of the first section (38) is less than the angle of inclination (β) of the second section (40). 3. The cutting insert (10) according to claim 1, characterized in that the wear-resistant coating contains at least one layer that contains a phase with at least one of the elements V, Cr, Nb, Ti, Ta, Zr, Hf, B , Al, Si, C, N, O, while the thickness of the wear-resistant coating on the front and rear surfaces is selected from the range of 1.5-4.5 microns. 4. The cutting insert (10) according to claim 1, characterized in that the auxiliary lower surfaces (24a) smoothly mate with the lower base surface (24). 5. The cutting insert (10) according to claim 4, characterized in that the mating surfaces (52) are made in the form of a part of the side surface of imaginary truncated cones, the vertices of which coincide with the corresponding auxiliary lower surfaces (24a). 6. A cutting insert (10) according to claim 5, characterized in that recesses (54) are made in the housing elements from the side of the lower auxiliary surfaces, the side walls of which are part of the surface of the imaginary truncated cone of the opposite direction of the surface of the imaginary truncated cones of the mating surfaces (52) auxiliary surfaces (24a) with a lower base surface (24). 7. The cutting insert (10) according to one of paragraphs. 1-6, characterized in that the part of the lower base surface (24) located around the mounting hole (16) does not have a wear-resistant coating. 8. The cutting insert (10) according to claim 1, characterized in that on the upper surface (26) opposite the base sectors (22), recesses (26a) are made in the radial direction. 9. A disk mill for processing narrow grooves (56), comprising a housing (58) in the form of a disk with a working part located around the axis of rotation (60), sockets (62) made in the housing (58) and located alternately with one and the other sides of the housing in which cutting inserts are installed by means of fixing screws (72), each socket having a supporting surface (64), side base surfaces (66) and an opening (68) for fixing screws, characterized in that in the sockets (62) mounted and fixed with screws (72) the cutting plates (10) according to one of paragraphs. 1-8, while their lower base surfaces (24) are in contact with the supporting surfaces (64) of the nests (62), made in the form of sectors (74), alternating with recesses (76), which include protruding relative to the lower base surfaces (24) ) the lower parts of the housing elements (20) of the cutting inserts (10).

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