Cutting tools and the use of cutting inserts therein

Abstract

A cutting tool (100) for cutting, comprising: a base portion (1) having a rotation axis (R) about which the tool rotates during operation; at least one mounting seat (2) formed on the base portion (1) for accommodating a replaceable cutting insert (3); a fixing screw (5) for fixing the cutting insert (3) to the mounting seat (3); and the cutting insert (3) fixed to the mounting seat (2). The mounting seat (2) has a base surface (21) for placing the lower surface (33) of the cutting insert, a first lateral abutment surface (22) for abutting against a first side surface (37) of the cutting insert (3) that supports the cutting insert (3) radially inward, and a second lateral abutment surface (23) for abutting against a second side surface (38) of the cutting insert (3) that supports the cutting insert (3) axially and radially outward, and further has one hole (4) formed in the base surface (21) for accommodating a fixing screw (5).

Description

[Technical field]

[0001] The present invention relates to a cutting tool and to the use of a cutting insert therein.

[0002] In particular in the machining of metallic materials and increasingly of composite materials, the cutting edges which engage with the workpiece are formed on replaceable cutting inserts which are made of a hard, wear-resistant material and which are arranged in seats provided for this purpose on a base part which is made of a highly tough material, in particular tool steel. These replaceable cutting inserts are often formed as so-called indexable tips or indexable cutting inserts which have a number of cutting edges which are successively brought into the active cutting position of the base part when the cutting edge which was used before them is worn down. In this case, these cutting inserts can generally be made of hard metals (hard alloys), cermets or cutting tool ceramics.

[0003] In tools designed for cutting by milling, the base part has an axis of rotation around which it rotates during the operation of the tool. The base part may, for example, only have one seating for receiving an exchangeable cutting insert. However, as a rule, several such seats are provided, distributed around the circumference of the tool. In order to increase productivity when cutting with such tools, there is a tendency to configure tools suitable for the material as so-called high-speed milling cutters or high-speed cutters, which are operated at increasingly high speeds, often with speeds of several tens of thousands of revolutions per minute.

[0004] When such tools are operated at very high rotational speeds, in addition to the generally occurring cutting forces acting mainly in the tangential and axial directions, there is also the problem of centrifugal forces acting on the cutting insert as a result of the particularly high rotational speeds. In the following description, where the terms radial, axial and tangential are used, they each refer to the axis of rotation of the base part of the tool, unless otherwise specified by the specific context.

[0005] For example, if the cutting insert is fixed to the mounting seat by a fixing screw, the large centrifugal force can change the position of the cutting insert in the mounting seat of the base part and, in extreme cases, can damage the fixing screw, which can result in the cutting insert being dislodged from the mounting seat. If this occurs during cutting, it can cause damage to the workpiece being machined and also pose a safety risk.

[0006] Patent document 1 describes a cutting tool for high-speed machining, in which a mounting seat for accommodating a replaceable cutting insert is provided with a shape that can be fitted and coupled to the underside of the cutting insert with a certain degree of certainty. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] European Patent Application Publication No. 1083017A1 Summary of the Invention [Problem to be solved by the invention]

[0008] The object of the present invention is to provide an improved tool for cutting at high rotational speeds, an improved use of a cutting insert, and an improved method for fixing a cutting insert, in which the cutting insert is reliably supported against the acting centrifugal forces in a manner that is not influenced by manufacturing tolerances, and in which the clamping force for clamping the cutting insert in a mounting seat can be predefined within narrower limits. [Means for solving the problem]

[0009] This problem is solved by a cutting tool according to claim 1. Advantageous developments are given in the dependent claims.

[0010] The tool has a base part having an axis of rotation about which the tool rotates during operation, at least one mounting seat formed on the base part for receiving an exchangeable cutting insert, a fixing screw for fixing the cutting insert to the mounting seat, and one cutting insert fixed to the mounting seat. The mounting seat has a base surface for receiving the lower surface of the cutting insert, a first lateral abutment surface for abutting a first side surface of the cutting insert that supports the cutting insert radially inward, and a second lateral abutment surface for abutting a second side surface of the cutting insert that supports the cutting insert axially and radially outward. The base surface is formed with a hole for receiving the fixing screw. The hole has a threaded hole portion remote from the base surface and an unthreaded hole portion closer to the base surface. The fixing screw has a threaded portion for engaging with the threaded hole portion, a head portion for support in the through hole of the cutting insert, and an unthreaded shank portion between the threaded portion and the head, the unthreaded shank portion having a cross section smaller than the unthreaded hole portion. The cutting insert is fixed to the mounting seat as follows: the head of the fixing screw is supported in the through hole of the cutting insert, the threaded portion of the fixing screw engages with the threaded hole portion, and the head of the fixing screw is elastically deflected so that the unthreaded shank is supported in the unthreaded hole portion in a second quadrant located radially outward and axially toward the free end of the tool in a line of sight perpendicular to the base surface.

[0011] In the line of sight perpendicular to the base surface, the hole has four quadrants, two of which (quadrant 3 and quadrant 4) are located radially inward, i.e. closer to the axis of rotation of the base, and two of which (quadrant 1 and quadrant 2) are located radially outward, i.e. further away from the axis of rotation of the base. Quadrant 3, which is one of the quadrants located radially inward of the hole, and quadrant 2, which is one of the quadrants located radially outward, are each located axially in the direction of the free end of the tool, which will be referred to below as "axially forward". Quadrant 4, which is the other radially inward quadrant, and quadrant 1, which is the other radially outward quadrant, are each located opposite the free end of the tool, i.e. in the direction of the tool attachment, which will be referred to below as "axially rearward". Thus, when viewed in a clockwise direction, there is a first quadrant radially outward and axially opposite the free end, a second quadrant radially outward and axially toward the free end, a third quadrant radially inward and axially toward the free end, and a fourth quadrant radially inward and axially opposite the free end.

[0012] The second lateral abutment surface is provided to abut against the second side surface of the cutting insert and supports the cutting insert axially and radially outward, and the fastening screw is elastically deflected so that the unthreaded shank is supported in the unthreaded bore in the second quadrant located radially outward and axially toward the free end of the tool, so that the cutting insert is supported against centrifugal forces in two spatially separated positions, so that displacement of the cutting insert from the mounting seat is reliably prevented even during high speed rotation of the tool. Since the support of the unthreaded shank in the unthreaded bore is achieved by elastic deflection of the head and the unthreaded shank of the fastening screw, the manufacturing tolerances of the first and second lateral abutment surfaces, the bore and the fastening screw can be reliably compensated for by elastic deformation of the fastening screw. Furthermore, the clamping force with which the cutting insert is clamped in the mounting seat can be predetermined by the elastic properties of the fastening screw.

[0013] According to one development, in the fourth quadrant, which lies radially inward and opposite the free end of the tool, the unthreaded shank is arranged at a distance from the unthreaded bore, i.e. the unthreaded bore has a corresponding excess dimension with respect to the unthreaded shank of the fastening screw, so that the unthreaded shank can be elastically deflected without hindrance until it abuts against the unthreaded bore in this quadrant, which lies radially outward and towards the free end of the tool. In this way, the tolerances of the cutting insert and the lateral abutment surfaces can be compensated particularly well. It is also preferable that the unthreaded shank is also spaced from the unthreaded bore in the first and third quadrants.

[0014] When the head of the fixing screw is elastically deflected radially outward and axially towards the free end of the tool, the cutting insert is clamped particularly securely against both the first and the second lateral abutment surfaces.

[0015] According to one development, the first and second lateral abutment surfaces form an angle with respect to one another in a line of sight perpendicular to the base surface that is greater than 75°. In this case, the cutting insert is particularly securely fixed in a mating manner and is therefore protected against the centrifugal forces acting thereon. Preferably, this angle is greater than 65°. In this case, the angle formed by the first and second lateral abutment surfaces is preferably greater than 35°, more preferably greater than 40°, in order to securely fix the cutting insert in the mounting seat.

[0016] According to one development, the head of the fastening screw has a maximum cross-section perpendicular to the axis of the fastening screw, which is greater than the minimum cross-section of the through-hole, in other words, the head of the fastening screw cannot pass through the through-hole of the cutting insert, which is then particularly securely fixed to the mounting seat in a mating manner.

[0017] According to one embodiment, the longitudinal axis of the screw hole is offset in the direction toward the first transverse abutment surface and in the direction toward the second transverse abutment surface with respect to the longitudinal axis of the through hole at the contact surface between the head of the fastening screw and the through hole of the cutting insert, in which case the cutting insert is securely clamped in the direction of the first transverse abutment surface and in the direction of the second transverse abutment surface, and the unthreaded shank of the fastening screw is securely abutted against the unthreaded hole by elastic deflection.

[0018] Since the surface normal of the first lateral abutment surface has a predominantly radially outward component, this first lateral abutment surface provides a particularly reliable support for the cutting insert against radially inwardly acting forces. In addition to the radially outward component, this surface normal can have numerically smaller axial and / or tangential components.

[0019] According to one development, the surface normal of the second transverse abutment surface has an axial component and a radially inward component, in which case the cutting insert is reliably supported by this second transverse abutment surface against axially acting forces and against centrifugal forces, and the surface normal of this second transverse abutment surface can have a numerically smaller tangential component.

[0020] According to one development, the surface normal of the base surface has a predominantly tangential component, in which case the cutting insert is particularly reliably supported on the mounting seat against cutting forces acting predominantly in the tangential direction, and the surface normal of the base surface can furthermore have numerically smaller radial and / or axial components.

[0021] According to one development, the wall of the unthreaded hole is formed concavely curved on the circumferential hole side at least in a second quadrant which lies radially outward of the hole and axially towards the free end of the tool, in which case the tolerances in the region of the first and second lateral abutment surfaces and the cutting insert engaging therewith are particularly reliably compensated for by the fact that the contact area of ​​the unthreaded shank on the unthreaded hole during elastic deflection of the head can be adjusted within a larger angular range in the second quadrant.

[0022] According to one development, the unthreaded holes have an approximately circular cross section, in which case they can be produced particularly simply and cost-effectively, however, it is also possible to produce unthreaded holes with cross-sectional shapes different from the circular cross section.

[0023] According to one development, the unthreaded hole is formed parallel to the threaded hole, which allows a particularly simple and cost-effective production of both the hole and the fastening screw accommodated therein.Preferably, the unthreaded hole is formed coaxially to the threaded hole.

[0024] According to one development, the tool is a high-speed milling cutter designed for cutting operations at speeds of more than 10,000 revolutions per minute. In particular with such tools designed for machining at high speeds, a reliable support against the centrifugal forces acting is particularly important.

[0025] Said problem is also solved by the use of a cutting insert in such a tool according to claim 14. During this use the advantages mentioned above for the tool are obtained.

[0026] The object is also achieved by a method for fastening a cutting insert according to claim 15.

[0027] A method for fixing a cutting insert to a mounting seat of a base part of a tool, the base part having an axis of rotation about which the tool rotates during operation, the mounting seat having a base surface for receiving an underside of the cutting insert, a first lateral abutment surface for supporting the cutting insert radially inwardly, and a second lateral abutment surface for supporting the cutting insert axially and radially outwardly. A hole for receiving a fixing screw is formed in the base surface, the hole having a threaded hole portion remote from the base surface and an unthreaded hole portion closer to the base surface. The method comprises the following steps: - placing the cutting insert on the mounting seat, so that the lower surface of the cutting insert is supported by the base surface, the first side surface abuts against the first lateral abutment surface, and the second side surface abuts against the second lateral abutment surface; - guiding the threaded portion of the fastening screw through the through hole and the hole of the cutting insert, so that the threaded portion engages with the threaded hole portion and an unthreaded shank portion disposed between the threaded portion and the head of the fastening screw is circumferentially spaced apart within the unthreaded hole portion; a step of screwing in the fastening screw, so that first the head abuts on the radially inner side of the through hole opposite the free end of the base part, and then the head and the unthreaded shank are elastically deflected radially outward and axially toward the free end of the base part, so that the unthreaded shank abuts on a second quadrant located radially outward and axially toward the free end of the unthreaded hole; has.

[0028] The method provides the advantages mentioned above with respect to the tool, and several advantageous developments mentioned with respect to the tool can likewise be used advantageously in the method.

[0029] Further advantages and suitability of the invention will become apparent from the following detailed description of the preferred embodiments with reference to the accompanying drawings, in which: FIG. [Brief description of the drawings]

[0030] [Figure 1] FIG. 1 is a perspective view of a tool according to one embodiment. [Diagram 2] FIG. 2 is an enlarged view of the mounting seat in the circled area B of FIG. 1, in which a cutting insert is disposed, but there is no fixing screw. [Diagram 3] FIG. 3 is an auxiliary view corresponding to FIG. 2 but without the cutting insert. [Figure 4] FIG. 4 is a schematic diagram of a fixing screw in this embodiment. [Diagram 5] FIG. 2 is a schematic cross-sectional view in a plane including the longitudinal axis of the screw hole, in which a cutting insert is arranged in the area of ​​the mounting seat, but there is no fixing screw. [Figure 6] FIG. 2 is a schematic perspective view of the cutting insert in this embodiment. [Figure 7] FIG. 6 is a cross-sectional view of the fixing screw corresponding to FIG. 5, but in a state where the fixing screw is not screwed in. [Figure 8] FIG. 8 is a cross-sectional view corresponding to FIG. 7, but showing a state in which the fixing screw has been screwed in. [Figure 9] FIG. 2 is a schematic cross-sectional view perpendicular to the longitudinal axis of the hole in the region of the unthreaded hole when the fixing screw is not screwed in. [Figure 10] 10 is a schematic cross-sectional view corresponding to FIG. 9 with the fixing screw screwed in. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0031] An embodiment will be described in more detail below with reference to the drawings.

[0032] In this specifically shown embodiment, the tool 100 for cutting is a milling tool, in particular a high-speed milling tool designed for machining at speeds of up to several tens of thousands of revolutions per minute.

[0033] The tool 100 comprises a base part 1, which may be made, for example, of tool steel, tungsten heavy metal or hard metal such as Densimet®. The base part 1 has a first end 11 provided with an interface for indirect or direct connection to a drive spindle of a processing machine (not shown) and a free end 12 opposite the first end 11. The base part 1 has an axis of rotation R, about which the tool 100 rotates during operation, i.e. during cutting.

[0034] As shown in FIG. 1, the base part 1 is provided in the region of the free end 12 with a number of mounting seats 2 for receiving a number of replaceable cutting inserts 3. These mounting seats 2 are distributed over the circumference of the base part 1. In the specifically illustrated embodiment, the base part 1 is shown with a total of four mounting seats 2 for receiving the replaceable cutting inserts 3, but it is also possible to provide fewer, but at least one or more than four such mounting seats 2. The mounting seats 2 are arranged in such a way that the cutting inserts 3 arranged in the respective mounting seats each have a minor cutting edge 31 that projects axially beyond the free end 12 of the base part 1 and a major cutting edge 32 that projects radially beyond the base part 1. The mounting seats 2 are designed for so-called radial clamping of the cutting inserts 3, in which the main spreading surfaces of the cutting inserts 3 fixed in the respective mounting seats 2 each extend approximately radially and the longitudinal axes of the fixing screws 5, which fix the cutting inserts 3 to the mounting seats, extend mainly tangentially. These mounting seats 2 are of approximately identical configuration to each other, and the cutting inserts placed thereon are also at least approximately identical to each other, so below we will only provide a detailed description of the fixation of one mounting seat 2 and one cutting insert 3 placed thereon.

[0035] The cutting insert 3 has a generally polygonal basic shape and, in particular, as shown in FIG. 6, has a lower surface 33 and an upper surface 34 formed as a rake surface facing the lower surface 33. The lower surface 33 and the upper surface 34 are joined to each other by a plurality of side surfaces. A through-hole 36 extends from the upper surface 34 to the lower surface 33 through the cutting insert 3. A secondary cutting edge 31 and a main cutting edge 32 are formed along the transition portion from the upper surface 34 to the plurality of side surfaces and are joined to each other by a corner cutting edge 35. In this specifically illustrated embodiment, since the cutting insert 3 has two-fold rotational symmetry with respect to the longitudinal axis of the through-hole 36, there are two cutting edge portions, each of which includes one main cutting edge and one secondary cutting edge joined to the main cutting edge via the corner cutting edge 35. As shown in FIG. 1, in the state where the cutting insert 3 is assembled to the base portion 1, one of the two cutting edge portions is located in the active position, in which the main cutting edge 32 protrudes radially beyond the base portion 1 and the secondary cutting edge 31 protrudes axially beyond the base portion 1, and the other of the two cutting edge portions is located in the non-active position.

[0036] In this specifically illustrated embodiment, the cutting insert 3 is shown in which a plurality of cutting edge portions are provided only at the transition portion from the upper surface 34 to the plurality of side surfaces. However, in a modified example, a double-sided configuration of the cutting insert in which a plurality of cutting edge portions are also provided at the transition portion from the lower surface 33 to the plurality of side surfaces is also possible.

[0037] This cutting insert 3 has a first side surface 37 by which the cutting insert 3 is supported by the mounting seat 2 toward the radially inner side. This first side surface 37 is formed on the side opposite to the main cutting edge 32 in the active position of the cutting insert 3. Due to the above-described two-fold rotational symmetry, there is also another first side surface 37 below the main relief surface of the active main cutting edge 32, which is associated with the opposing non-active main cutting edge 32.

[0038] The cutting insert 3 further has a second side surface 38 by which the cutting insert 3 is supported axially and radially outwardly on the mounting seat 2. The second side surface 38 is formed on the side of the cutting insert 3 opposite the minor cutting edge 31 in the active position. Due to the above-mentioned two-way rotational symmetry, there is also another second side surface 38 on the side of the active minor cutting edge 31, which is associated with the opposite inactive minor cutting edge 31.

[0039] The mounting seat 2 for holding the cutting insert 3 will be described in detail below with reference to FIG.

[0040] This mounting seat 2 has a base surface 21 on which the lower surface 33 of the cutting insert 3 is placed, a first lateral abutment surface 22 that abuts against the first side surface 37 of the cutting insert 3, and a second lateral abutment surface 23 that abuts against the second side surface 38 of the cutting insert 3.

[0041] The surface normal of the base surface 21 has a main tangential component. In addition, the surface normal of the base surface 21 may further have a numerically smaller axial component and / or radial component.

[0042] The first lateral abutment surface 22 supports the cutting insert 3 radially inward. This first lateral abutment surface 22 can be formed, for example, as one continuous surface. However, it is also possible for this first lateral abutment surface 22 to have a number of separate partial surfaces for radially inward support, as shown, for example, in FIG. 3. To achieve radially inward support, the surface normal of the first lateral abutment surface 22 has a predominantly radially outward directional component. In this case, the surface normal of this first lateral abutment surface 22 can, for example, only have a radially outward directional component or can additionally have numerically smaller tangential and / or axial components.

[0043] The second transverse abutment surface 23 supports the cutting insert 3 on the side facing away from the free end 12 of the base part 1 both in the axial direction and radially outward. To achieve this, the surface normal of the second transverse abutment surface 23 has both an axial component in the direction of the free end 12 of the base part 1 and a radially inward component. Besides this, the surface normal of the second transverse abutment surface 23 may also have a small tangential component, for example as in the second transverse abutment surface 23 shown in FIG.

[0044] As shown in FIG. 3, the first transverse abutment surface 22 and the second transverse abutment surface 23 form an interior angle α with each other, as viewed perpendicularly to the base surface 21, which interior angle is less than 75°, preferably less than 65°. In this specifically illustrated embodiment, the interior angle α is about 60°. The first transverse abutment surface 22 and the base surface 21 form an interior angle of 90° or more. Similarly, the second transverse abutment surface 23 and the base surface form an interior angle of 90° or more. In this specifically illustrated embodiment, the interior angle between the base surface 21 and the first transverse abutment surface 22 may be slightly larger than 90°, for example about 100°. Similarly, the interior angle between the base surface 21 and the second transverse abutment surface 22 may be slightly larger than 90°, for example about 100°. In the case of a double-sided cutting insert 3 in which a cutting edge is also formed at the transition from the underside 33 to the side surface, it is preferable that the interior angle between the base surface 21 and the lateral abutment surfaces 22, 23 is 90° in each case.

[0045] As shown in Figures 3 and 5, the base surface 21 of the mounting seat 2 is provided with a hole 4. The hole 4 extends from the base surface 21 into the material of the base part 1 and, in an area remote from the base surface 21, has a threaded hole 41 with an internal thread for engaging with a corresponding external thread of the fixing screw 5, as will be explained in more detail below. Between the threaded hole 41 and the opening of the hole 4 in the base surface 21, an unthreaded hole 42 is provided. In this specifically illustrated embodiment, the unthreaded hole 42 has a circular cross section and extends coaxially to the threaded hole 41. However, it is also possible for the unthreaded hole 42 to have a different cross-sectional shape.

[0046] As shown in FIG. 4, the fastening screw 5 has a threaded portion 51 adapted to engage with the threaded hole 41, a head 53 and an unthreaded shank 52 arranged between the head 53 and the threaded portion 51. In this specifically illustrated embodiment, a constriction is provided between the threaded portion 51 and the unthreaded shank 52, which advantageously provides for a relative elastic deflection of the head 53 with respect to the threaded portion 51 in a direction perpendicular to the longitudinal axis of the fastening screw 5. The head 53 of the fastening screw 5 is designed to engage with the through hole 36 of the cutting insert 3. The head 53 has a maximum cross-section that is greater than the minimum inner cross-section of the through hole 36, so that the head 53 cannot pass completely through the through hole 36. The head 53 is adapted to the shape of the through hole 36 so that the head 53 can be supported in the through hole 36, particularly preferably in an annular manner. The cross-section of the unthreaded shank 52 of the fastening screw 5 is significantly smaller than the cross-section of the unthreaded hole 42 of the hole 4. In other words, unthreaded bore 42 has an overdimension all around its periphery relative to unthreaded shank 52 that is significantly greater than the normal manufacturing tolerances that would allow for a snug fit.

[0047] As shown in FIG. 3 in particular, the unthreaded hole 42 has four quadrants Q1, Q2, Q3, and Q4, numbered in a clockwise direction in this case. The first quadrant Q1 of the unthreaded hole 42 is opposite the free end 12 of the base portion 1 and is radially outside the unthreaded hole 42. The second quadrant Q2 is on the side of the free end 12 and is radially outside. The third quadrant Q3 is also on the side of the free end 12, but is radially inside. The fourth quadrant Q4 is on the side of the free end 12 and is radially inside. In other words, the first quadrant Q1 is in the range of "12 o'clock to 3 o'clock", the second quadrant Q2 is in the range of "3 o'clock to 6 o'clock", the third quadrant Q3 is in the range of "6 o'clock to 9 o'clock", and the fourth quadrant Q4 is in the range of "9 o'clock to 12 o'clock", starting from the direction parallel to the rotation axis R.

[0048] In the following, how the cutting insert 3 is held on the mounting seat 2 by the fixing screw 5 will be explained in more detail with reference to FIGS.

[0049] First, the next state will be described with reference to Figures 7 and 9. That is, a state will be described in which the cutting insert 3 is disposed on the mounting seat 2, and the threaded portion 51 of the fixing screw 5 is inserted through the through hole 36 of the cutting insert 3, so that the threaded portion 51 engages with the threaded hole portion 41, and the unthreaded shank portion 52 is disposed in the unthreaded hole portion 42, but the fixing screw 5 has not yet been screwed in. In this state, the unthreaded shank portion 52 is disposed away from the unthreaded hole portion 42 having an excessive dimension in all directions, as shown in particular in Figure 9. In other words, in this state, the unthreaded shank portion 52 is disposed away from the unthreaded hole portion 42 in the first quadrant Q1, the second quadrant Q2, the third quadrant Q3, and the fourth quadrant Q4. The vertical axis Z of the threaded hole portion 41 is slightly offset with respect to the vertical axis W of the through hole 36 of the cutting insert 3, as shown in Figure 5, for example, in the direction of the first lateral abutment surface 23 and the direction of the second lateral abutment surface 23. This direction is shown diagrammatically (not to scale) by arrow P in Figure 2, where the longitudinal axis Z of the threaded hole 41 is offset with respect to the longitudinal axis W of the through hole 36. It can be seen that this direction extends at an angle β with respect to the axial direction, so that it has a radially inward directional component and an axially rearward directional component, i.e. towards the first end 11 of the base 1. In the specifically illustrated example, the angle β is, for example, between 50° and 70°.

[0050] When the fastening screw 5 is tightened, the threaded portion 51 is screwed deeper into the threaded hole portion, so that the head 53 of the fastening screw 5 abuts against the through hole 36 of the cutting insert 3. Due to the above-mentioned offset between the longitudinal axis W of the through hole 36 and the longitudinal axis Z of the threaded hole portion 41, the head 53 first abuts against the side of the mounting seat 2 between the first transverse abutment surface 22 and the second transverse abutment surface 23 in the region of the through hole 36. This presses the cutting insert 3 in the direction between the first transverse abutment surface 22 and the second transverse abutment surface 23. Due to this abutment against the through hole 36, the head 53 of the fastening screw 5, and therewith the unthreaded shank 52, are elastically deflected radially outward of the base portion 1 and in the direction of the free end 12, so that the unthreaded shank 52 is bent towards the second quadrant Q2 of the unthreaded hole portion 42. In this case, this elastic deflection takes place until the unthreaded shank 52 abuts against the unthreaded hole 42 in the second quadrant Q2 of the unthreaded hole 42. This state is shown in Fig. 8 and Fig. 10. In Fig. 10, the resulting offset of the longitudinal axis Y of the fastening screw 5 with respect to the longitudinal axis Z of the threaded hole 41 in the region of the unthreaded shank 52 is shown diagrammatically. In addition to the radially outward support by the second transverse abutment surface 23, the cutting insert 3 is interlockingly supported radially outward in another position by this cooperation of the unthreaded shank 52 with the unthreaded hole 42, so that the cutting insert 3 is particularly reliably supported against the centrifugal forces acting during the cutting operation. Since this support takes place at the unthreaded shank 52, the shear forces acting on the fastening screw 5 due to the centrifugal forces act on the more stable unthreaded shank 52 and not on the weaker threaded portion 51 of the fastening screw 5, so that the risk of material damage to the fastening screw 5 is reduced. As a result of the elastic deformation of the fastening screw 5, the head 53 of the fastening screw 5 comes into mating contact with the through hole 36. In this case, due to cooperation between the larger head 53 of the fastening screw 5 and the smaller through hole 36 of the cutting insert 3, the cutting insert 3 is securely clamped in the direction of the base surface 21 and securely matingly fixed against lifting from the base surface 21.

[0051] In the first quadrant Q1, the third quadrant Q3 and the fourth quadrant 4 of the unthreaded hole 42, as shown in particular in Fig. 10, the unthreaded shank 52 of the unthreaded hole 42 does not abut due to the overdimension of the unthreaded hole 42 when the fastening screw 5 is screwed in. Due to the elastic deformation of the fastening screw 5 until the unthreaded shank 52 abuts the unthreaded hole 42, the manufacturing tolerances of the cutting insert 3 and of the first and second lateral abutment surfaces 22, 23 can be compensated without problems over a comparatively large range. The position and orientation tolerances of the first and second lateral abutment surfaces 22, 23 relative to one another are compensated in this case by the unthreaded shank 52 in the second quadrant Q2 of the unthreaded hole 42 moving further in the direction of the free end 12 or further in the radially outward direction. The shape of the wall of the unthreaded hole 42 in the second quadrant Q2 is concave towards the hole in the circumferential direction, so that in this case problem-free orientation of the unthreaded shank 52 in this direction is possible. In the illustrated embodiment, a circular cross-sectional shape of the unthreaded hole 42 is shown, which can be realized particularly simply and inexpensively in terms of manufacturing technology, but the cross-sectional shape of the unthreaded hole 42 is not limited to this circular shape, other cross-sectional shapes are also possible. However, the wall of the unthreaded hole 42 should be curved concavely in the circumferential direction at least in the second quadrant.

Claims

1. A cutting tool (100), comprising: a base part (1) having an axis of rotation (R) about which said tool rotates during operation; at least one mounting seat (2) formed on said base portion (1) for receiving an exchangeable cutting insert (3); A fixing screw (5) for fixing the cutting insert (3) to the mounting seat (2); A cutting insert (3) fixed to the mounting seat (2); In a tool (100) having the mounting seat (2) has a base surface (21) for placing a lower surface (33) of the cutting insert, a first lateral abutment surface (22) for abutting a first side surface (37) of the cutting insert (3) and supporting the cutting insert (3) radially inward, and a second lateral abutment surface (23) for abutting a second side surface (38) of the cutting insert (3) and supporting the cutting insert (3) axially and radially outward, and further, a hole (4) for accommodating the fixing screw (5) is formed in the base surface (21); The hole (4) has a threaded hole portion (41) away from the base surface (21) and an unthreaded hole portion (42) closer to the base surface (21), the hole (4) has four quadrants when viewed from a direction perpendicular to the base surface (21), two of which (the third and fourth quadrants) are located on the radially inner side, i.e., on the side closer to the rotation axis of the base part (1), and the other two (the first and second quadrants) are located on the radially outer side, i.e., on the side farther from the rotation axis of the base part (1), and one of the quadrants located on the radially inner side (the third quadrant) and one of the quadrants located on the radially outer side (the second quadrant) are each axially located in the direction of the free end of the tool; the fixing screw (5) has a threaded portion (51) for engaging with the threaded hole portion (41), a head portion (53) for supporting in the through hole (36) of the cutting insert (3), and an unthreaded shank portion (52) between the threaded portion (51) and the head portion (53), the unthreaded shank portion (52) having a cross section smaller than the unthreaded hole portion (42); The cutting insert (3) is fixed to the mounting seat (2) as follows: the head (53) of the fixing screw (5) is supported in the through hole (36) of the cutting insert (3), the threaded portion (51) of the fixing screw (5) is engaged with the threaded hole portion (41), and the head (53) of the fixing screw (3) is elastically deflected such that the unthreaded shank portion (52) is supported in the unthreaded hole portion (42) in the second quadrant (Q2) located radially outward and axially toward the free end (12) of the tool. Tools (100).

2. 2. The tool of claim 1, wherein the unthreaded shank (52) is positioned radially inward and spaced apart from the unthreaded bore (42) in a fourth quadrant (Q4) located opposite the free end (21) of the tool.

3. 3. Tool according to claim 1 or 2, characterized in that the head (53) of the fixing screw (5) is elastically deflected radially outwards and axially towards the free end (12) of the tool.

4. 4. The tool according to claim 1, wherein the angle (α) between the first lateral abutment surface (22) and the second lateral abutment surface (23) in a line of sight perpendicular to the base surface (21) is less than 75°.

5. 5. The tool according to claim 1, wherein the head (53) of the fastening screw (5) has a maximum cross-section perpendicular to the axis of the fastening screw (5), the maximum cross-section being greater than the minimum cross-section of the through hole (36).

6. a longitudinal axis (Z) of the screw hole portion (4) is offset in a direction toward the first lateral abutment surface (22) and in a direction toward the second lateral abutment surface (23) with respect to a longitudinal axis (W) of the through hole (36) at a contact surface between the head (53) of the fixing screw (5) and the through hole (36) of the cutting insert (3); A tool according to any one of claims 1 to 5.

7. The tool of any one of claims 1 to 6, wherein the unthreaded bore (42) has a generally circular cross-section.

8. The tool of any one of claims 1 to 7, wherein the tool (100) is a high speed milling cutter configured for cutting operations at speeds greater than 10,000 revolutions per minute.

9. Use of a cutting insert (3) in a tool (100) according to any one of claims 1 to 8.

10. A method for fixing a cutting insert (3) to a mounting seat (2) of a base portion (1) of a tool (100), comprising the steps of: The base portion (1) has a rotation axis (R), and during operation, the tool (100) rotates around the rotation axis, and the mounting seat (2) has a base surface (21) for receiving a lower surface of the cutting insert (3), a first lateral abutment surface (22) that supports the cutting insert (3) radially inward, and a second lateral abutment surface (23) that supports the cutting insert (3) axially and radially outward, A hole (4) for receiving a fixing screw (5) is formed in the base surface (21), the hole (4) having a threaded hole portion (41) away from the base surface (21) and an unthreaded hole portion (42) closer to the base surface (21); the hole (4) has four quadrants when viewed from a direction perpendicular to the base surface (21), two of which (the third and fourth quadrants) are located on the radially inner side, i.e., on the side closer to the rotation axis of the base part (1), and the other two (the first and second quadrants) are located on the radially outer side, i.e., on the side farther from the rotation axis of the base part (1), and one of the quadrants located on the radially inner side (the third quadrant) and one of the quadrants located on the radially outer side (the second quadrant) are each axially located in the direction of the free end of the tool; The following steps: a step of placing the cutting insert (3) on the mounting seat (2), wherein a lower surface (33) of the cutting insert (3) is supported by the base surface (21), a first side surface (37) of the cutting insert (3) abuts against the first lateral abutment surface (22), and a second side surface (38) of the cutting insert (3) abuts against the second lateral abutment surface (23); a step of guiding a threaded portion (51) of a fixing screw (5) through the through hole (36) and the hole (4) of the cutting insert (3), the threaded portion (51) engaging with the threaded hole portion (41), and an unthreaded shank portion (52) disposed between the threaded portion (51) and a head portion (53) of the fixing screw (5) being disposed in the unthreaded hole portion (42) at a distance therefrom over the entire circumference; a step of screwing in the fixing screw (5), in which the head (53) first abuts on the radially inner side of the through hole (36) opposite the free end (12) of the base part (1), and then the head (53) and the unthreaded shank (52) are elastically deflected radially outward and axially toward the free end (12) of the base part (1) so that the unthreaded shank (52) abuts on a second quadrant (Q2) of the unthreaded hole part (42) on the radially outer side and axially toward the free end (12); The method according to claim 1,

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