Cutting tool with cutting head and cutting head driver

Abstract

The invention relates to a cutting tool (2) for machining workpieces, comprising a cutting head (10) and a cutting head driver (12) which can be connected to the cutting head (10). The cutting head (10) and the cutting head driver (12) have respective main parts (14, 24), from the end face of which a protruding section (16, 26) that has an undercut in the axial direction protrudes axially, each protruding section having a torque-transmitting surface (18, 28) which are designed to complement each other, are positioned in a preferably axial manner, and rest against each other in the connected state, wherein the protruding sections (16, 26) are dimensioned such that the end face (20) of the protruding section (16) of the cutting head (10) rests against the end face (32) of the main part (24) of the cutting head driver (12) in the axial direction in the connected state.

Description

[0001] Cutting tool with cutting head and cutting head driver

[0002] Description

[0003] Technical area

[0004] The present disclosure relates to a cutting tool for machining workpieces, in particular a shank tool, such as a milling cutter or a drill. The cutting tool comprises a cutting head, preferably made of hard metal, and a cutting head driver, preferably made of steel. The cutting head and the cutting head driver can be connected to one another via a type of bayonet lock / bayonet connection, in particular in a torque-transmitting and axially fixed manner.

[0005] Such multi-part cutting tools, which can be connected to one another in a bayonet-like manner for torque transmission and axial connection, are already known from the prior art. For example, DE 10 2017 214 165 B4 discloses a rotary tool with a carrier and a cutting insert, in which the carrier can be inserted into a seat of the cutting insert and, when inserted, rests with its side surfaces against the respective side surfaces of the cutting insert.

[0006] The cutting head and the cutting head driver can be made of different materials, the same material group, preferably steel, or different material groups, preferably hard metal and steel, in order to optimize the cutting tool depending on the requirements in terms of wear resistance, strength and costs.

[0007] A disadvantage of known cutting tools, however, is that the lever-like effect on the bayonet connection between the cutting head and the cutting head driver induces a bending stress, which must not be too high in order to avoid damage, particularly if the cutting head and the cutting head driver are made of different materials in the area of ​​the cutting head or a component of the cutting tool made of hard metal.

[0008] Furthermore, DE 102013205 889 B3, DE 10 2012 200 690 B4, EP 0 984 841 B2, and DE 697 34 937 T2 each disclose a cutting tool comprising a cutting head driver and a cutting head, which can be connected to one another via coupling sections on the cutting head side and the cutting head driver side. In the connected state, the coupling sections each engage in recesses in the cutting head or cutting head driver that are set back on the end face, i.e., opposite the end face of the coupling sections, and bear against one another on complementarily designed torque transmission surfaces for torque transmission / stop surfaces and fastening surfaces / clamping surfaces for centering, fastening, and / or clamping.

[0009] In the cutting tool known from DE 10 2013 205 889 B3 or DE 10 2012 200 690 B4, the coupling sections on the cutting head side are formed by a coupling pin that extends diametrically continuously but not to the outer tool radius, and the coupling sections on the cutting head driver side are formed by diametrically opposed, spaced-apart / individual webs / protrusions that are essentially annular in cross-section. In the connected state, the coupling sections on the cutting head driver side surround the coupling sections on the cutting head side radially outward. The coupling pin on the cutting head has an approximately rectangular basic shape, in which the longitudinal sections and transverse sections merge into one another via transition sections designed as rounded corner sections, whereby the longitudinal sections form the torque transmission surfaces / stop surfaces and the transverse sections form the fastening surfaces / clamping surfaces.For axial securing, the longitudinal sections and / or transverse sections are axially undercut, for example, in the manner of a dovetail joint. When connected, the coupling sections on the cutting head driver side rest axially against the recessed recesses of the cutting head, while the coupling sections on the cutting head side are axially spaced from the recessed recesses of the cutting head driver.

[0010] In the cutting tool known from EP 0 984 841 B2, the cutting-head-side coupling sections are formed by a diametrically continuously extending web on the cutting head, and the cutting-head driver-side coupling sections are formed by diametrically opposed, spaced-apart / individual projections. The torque transmission surfaces are axially inclined and extend substantially in the radial direction. The fastening surfaces extend circumferentially concentrically to the rotation axis. In the connected state, the cutting-head driver-side coupling sections axially bear against the recessed recesses of the cutting head, while the cutting-head-side coupling sections are axially spaced from the recessed recesses of the cutting head driver.

[0011] In the cutting tool known from DE 697 34 937 T2, the coupling sections on the cutting head side are formed by a coupling pin extending diametrically continuously up to the outer tool radius, and the coupling sections on the cutting head driver side are formed by diametrically opposed, spaced-apart / individual webs / protrusions with a cross-section essentially shaped like an annular segment. The fastening surfaces extend in the circumferential direction concentrically to the axis of rotation and are axially adjusted for axial securing, in particular oriented radially inward and longitudinally rearward, so that a dovetail-like cross-section is produced in the region of the fastening surfaces. The torque transmission surfaces extend in the radial direction and are aligned parallel to the axis of rotation, i.e., not axially adjusted.When connected, the coupling sections on the cutting head side rest axially against the recessed recesses of the cutting head driver, while the coupling sections on the cutting head driver side are axially spaced from the recessed recesses of the cutting head. However, the disadvantage of these rotary tools is that they have weak points with regard to material failure and are not suitable for transmitting particularly high torques. Furthermore, the geometry of the coupling pin and the dovetail-like outer geometry are complex to produce, for example, through subsequent milling.

[0012] It is therefore the object of the present disclosure to avoid the aforementioned disadvantages of known cutting tools and to provide a multi-part cutting tool that can withstand high forces without having to accept the risk of damage or premature wear of its individual components.

[0013] The object of the present disclosure is achieved by a cutting tool having the features of patent claim 1. Advantageous further developments are the subject of the subclaims.

[0014] The cutting head and the cutting head driver each have a main body, from the end face of which a projection section that is undercut in the axial direction projects axially. This means that the projection section of the cutting head projects from the (axial) end face of the main body of the cutting head in the axial direction towards the cutting head driver. The projection section of the cutting head is designed to be undercut, in particular in an axial direction directed away from the cutting head driver. This also means that the projection section of the cutting head driver projects from the (axial) end face of the main body of the cutting head driver in the axial direction towards the cutting head. The projection section of the cutting head driver is designed to be undercut, in particular in an axial direction directed away from the cutting head.In other words, the cutting head and the cutting head driver each have opposing, stepped end faces, with the axially outermost (or outermost) part of the end face being formed by the end face of the corresponding projection portion, and the axially recessed / inner part of the end face being formed by the end face of the corresponding main body. The projection portions each undercut the end face of the corresponding main body in opposite axial directions.

[0015] The projection portion of the cutting head and the projection portion of the cutting head driver can be positively connected to one another / brought into positive engagement by rotating the cutting head counter to a cutting direction of the cutting tool. By rotating the cutting head in the cutting direction, the projection portion of the cutting head and the projection portion of the cutting head driver can be released from one another / brought out of positive engagement. This means that the bayonet lock / bayonet connection is formed by the axially undercut projection portions such that the cutting head and the cutting head driver can be connected to one another by mutual rotation relative to one another and can be released from one another by mutual rotation relative to one another. The projection portions serve in particular as coupling portions for connecting the cutting head and the cutting head driver.

[0016] The projection section of the cutting head and the projection section of the cutting head driver each have mutually complementary, axially undercut, preferably axially adjusted, torque transmission surfaces, which, when the cutting head and the cutting head driver are connected, bear against one another, in particular flatly. This means that the projection section of the cutting head is wedge-shaped or has a wedge-shaped section that forms the torque transmission surface / undercut surface of the projection section. The torque transmission surface of the projection section of the cutting head can preferably be aligned substantially in the radial direction, i.e., perpendicular to the tangential direction, of the cutting tool in order to be able to positively absorb a torque to be transmitted from the cutting head driver to the cutting head.This also means that the projection portion of the cutting head driver is wedge-shaped or has a wedge-shaped portion that forms the torque transmission surface / undercut surface of the projection portion. The torque transmission surface of the projection portion of the cutting head driver can preferably be aligned substantially in the radial direction, i.e., perpendicular to the tangential direction, of the cutting tool in order to be able to positively transmit a torque to be transmitted from the cutting head driver to the cutting head. In other words, the cutting head and the cutting head driver are substantially Z-shaped / stepped in the region of their (bayonet) connection.

[0017] In the cutting tool, the projection sections of the cutting head and the cutting head driver are dimensioned such that an end face of the projection section of the cutting head, in the connected state, bears against an end face of the main body of the cutting head driver in the axial direction. This means that the projection sections are dimensioned such that, or their tolerances are selected such that, when the torque transmission surfaces of the projection sections bear against one another (and transmit a torque), i.e., when the cutting head and the cutting head driver are connected, the projection section of the cutting head is axially supported on the main body of the cutting head driver. In other words, the wedge-shaped projection section of the cutting head, in the connected state, is received or supported in a wedge-shaped recess formed by the projection section and the main body of the cutting head driver, axially and tangentially.The wedge-shaped section of the cutting head is supported with both wedge sides in the wedge-shaped recess of the cutting head driver.

[0018] This has the advantage that the axial support of the cutting head on the cutting head driver results in a tangential, forced guidance of the cutting head, preferably made of hard metal, which reduces the bending stress, particularly in the transition region between the projection section and the main body of the cutting head. Furthermore, the axial contact between the end face of the main body of the cutting head driver and the end face of the projection section of the cutting head creates a wedge support, which acts in the axial direction toward the cutting head driver and thus generates a frictional force that counteracts the load and thereby also reduces the bending stress, particularly in the transition region between the projection section and the main body of the cutting head.

[0019] Thus, compared to the cutting tools discussed at the beginning from DE 102013205 889 B3, DE 10 2012 200690 B4 and EP 0 984 841 B2, there is the advantage that the coupling sections on the cutting head driver side do not axially abut the recessed recesses of the cutting head (and the coupling sections on the cutting head side are axially spaced from the recessed recesses of the cutting head driver), but that the coupling sections on the cutting head side axially abut the recessed recesses of the cutting head driver. As a result, according to the present disclosure, the spreading resulting from the axial positioning of the torque transmission surfaces or wedge-shaped design of the projection sections occurs (exclusively or predominantly) in the region of the wedge-shaped recess of the cutting head driver and not in the region of the wedge-shaped recess of the cutting head.

[0020] Furthermore, there is the fundamental difference from the cutting tool from DE 697 34 937 T2 discussed at the beginning in that there an axial undercut, in particular in the form of a dovetail, is formed only on the fastening surfaces of the coupling pin which serve exclusively for fastening, in particular for axial securing and centering. Since these fastening surfaces cannot transmit any torque due to their concentric design with respect to the axis of rotation, they do not correspond to the torque transmission surfaces according to the present disclosure. In the cutting tool of DE 697 34 937 T2, the stop surfaces serving as torque transmission surfaces are designed parallel to the axis of rotation, so that the core orThe problem of the present disclosure, namely the torque transmission surfaces undercut in the axial direction, which are converted into axial forces by the cutting forces generated during workpiece machining, and a spreading occurs, is not present in DE 697 34 937 T2. According to a preferred embodiment, an end face of the projection portion of the cutting head driver can be spaced apart from an end face of the main body of the cutting head with axial play in the connected state. In other words, only one end face of the stepped end face of the cutting head bears against the cutting head driver to avoid a double fit. As a result, the wedge-shaped portion of the cutting head driver contacts the wedge-shaped recess in the cutting head only with one wedge side, more precisely with the torque transmission surface, and thus does not spread the wedge-shaped recess in the cutting head.This reduces the load on the transition between the torque transmission surface and the non-contacting face, which has a positive effect on the service life of the cutting head and thus of the cutting tool.

[0021] Generally speaking, according to the invention, in a bayonet-type connection between two sections, preferably made of different materials, e.g. steel and hard metal, alternatively made of materials of the same material group, e.g. steel, with a Z-angle geometry or with two mutually engaging wedge geometries, the loads resulting from the wedge forces are shifted to the section which is the more flexurally elastic, softer or less brittle section in comparison.

[0022] According to a preferred embodiment, the projection section of the cutting head can be longer in the axial direction than the projection section of the cutting head driver. This makes it particularly easy to ensure that, with a complementary design of the torque transmission surfaces, the (minor) difference in the axial extent of the two projection sections means that the cutting head rests with its projection section against the main body of the cutting head driver, while the (shorter) projection section of the cutting head driver remains spaced from the main body of the cutting head. In this way, the contact surfaces, and thus force transmission surfaces, can be clearly defined in terms of design. According to a preferred embodiment, the projection sections can have surfaces or geometries which engage with one another when the cutting head and the cutting head driver are connected.For example, the wedge-shaped projection section of the cutting head and the wedge-shaped recess of the cutting head driver can have surfaces or geometries that interact with each other in a form-fitting manner when the two sections are connected in the direction of rotation, or they can rust together or achieve a locking effect in the direction of rotation. This prevents accidental release. Since the wedge-shaped section is made of a more rigid material and the wedge-shaped recess is made of a more flexible material, the former can elastically spread the latter to prevent the surfaces or geometries from rusting.

[0023] According to a preferred embodiment, the cutting head and the cutting head driver can have complementary geometries, so that the cross section of the cutting head driver and the cross section of the cutting head at their parting plane essentially correspond, and / or a geometric progression of the cutting head driver, in particular a formation of a helix, chip grooves, and / or circumferential cutting edges, is continued by the cutting head. This means that the cutting head and the cutting head driver preferably have complementary geometries, so that the cross section of the cutting head after the stepped parting plane of both parts essentially corresponds to the cross section of the cutting head driver before the stepped parting plane, or the geometric progression (including helix, chip grooves, and circumferential cutting edges) of the cutting head after the connection point continues the geometric progression (including helix, chip grooves, and circumferential cutting edges) of the cutting head driver.

[0024] According to a preferred embodiment, the torque transmission surfaces can be axially adjusted such that the cutting head is pressed axially toward the cutting head driver by the cutting forces acting during workpiece machining. This means that with increasing cutting forces during workpiece machining, the cutting head is attracted more strongly to the cutting head driver due to the interaction between the axially adjusted torque transmission surfaces. This ensures a firm connection between the cutting head and the cutting head driver, especially at high cutting speeds.

[0025] In the cutting tool, the torque transmission surfaces are preferably designed such that a tangential force, which arises from cutting forces acting during workpiece machining, is converted into an axial force, so that the cutting head is pressed axially into contact with the cutting head driver. This has the effect that with increasing cutting forces, i.e., at higher speeds, the tangential force increases and thus also the axial force, which in turn strengthens the connection between the cutting head and the cutting head driver. This allows particularly high cutting forces to be transmitted despite the multi-part design of the cutting tool.

[0026] According to a preferred embodiment, the torque transmission surfaces can be axially set at an axial angle of attack, preferably from 2° to 15°, more preferably from 2° to 10°, particularly preferably from 2° to 5°, and especially from 3°. Such an angle of attack has proven sufficient to create a strong connection that is simultaneously easy to install. Furthermore, the selection of the axial angle of attack keeps the forces acting on the projection section as low as possible.

[0027] Preferably, the torque transmission surface of the cutting head and the torque transmission surface of the cutting head driver can have identical axial angles of attack. This means that the torque transmission surfaces lie flush against each other, preventing the cutting head and the cutting head driver from jamming in the area of ​​the torque transmission surface.

[0028] According to a preferred embodiment, the axial angle of attack can be constant over the entire circumferential extent / circumferential contour, i.e., the entire course in the circumferential direction, of the torque transmission surfaces. This means that the circumferential surfaces of the projection sections have the same axial angle of attack, at least in the region in which the cutting head and the cutting head driver abut one another in the connected state, preferably over the entire extent in the circumferential direction, i.e., also in the non-adjacent region.

[0029] Preferably, the torque transmission surfaces can be seamless in the circumferential direction, i.e., without any kinks. This makes it possible to finish all circumferential surfaces in one workpiece clamping, i.e., without re-clamping, and in particular, with only one machining method.

[0030] According to a preferred embodiment, the axial angle of attack can be constant over the entire axial extent, i.e., the entire course in the axial direction, of the torque transmission surfaces. Preferably, the course of the torque transmission surfaces in the axial direction can be seamless, i.e., without a kink. This means that the axial angle of attack does not change, preferably from the end face of the projection portion (possibly minus a front-end termination region in which a chamfer or the like is formed) to the end face of the main body.

[0031] In particular, the torque transmission surfaces can be formed by a continuous, inclined surface, i.e., without any recesses or steps / elevations. This can be achieved, for example, by grinding wheel machining. The continuous design has the advantage of avoiding edges and thus stress peaks.

[0032] Furthermore, the cutting head and the cutting head driver can be Z-shaped in the area of ​​their bayonet connection.

[0033] In particular, the Z-shape can be achieved by the cutting head and the cutting head driver each having a pair of end faces consisting of two end faces that extend perpendicular to the axial direction and are spaced apart from one another in the axial direction, and wherein the torque transmission surfaces that connect the respective end faces of a pair of end faces to one another each extend essentially continuously, i.e., apart from a transition region between the end faces and the torque transmission surfaces, obliquely to the axial direction between the end faces of the respective pair of end faces. According to a preferred embodiment, an axially outer end face of the pair of end faces can transition into the torque transmission surface via a chamfer. This means that the essentially wedge-shaped projection sections are bluntly or rectilinearly chamfered on their end face / wedge corner.In other words, instead of a point (created by the convergence of the axially outer end face and the torque transmission surface), the wedge-shaped projection sections have a beveled surface. This not only simplifies the insertion of the projection sections, but also prevents force from being introduced deep into the wedge-shaped recess and local stress concentration peaks.

[0034] According to a preferred embodiment, an axially inner end face of the end face pair can transition into the torque transmission surface via a radius. This means that the essentially wedge-shaped recesses are rounded at their wedge corners. In other words, instead of a point (created by the convergence of the axially inner end face and the torque transmission surface), the wedge-shaped recesses have a rounded surface. This reduces material stresses and enables the geometry to be manufactured (for example, by grinding).

[0035] According to a preferred embodiment, the torque transmission surface can be formed as a continuously inclined surface between the chamfer and the radius. This means that the torque transmission surfaces, apart from their respective transition areas to the end face pair, are formed as flat surfaces, i.e., without depressions, steps, or elevations. This ensures torque transmission and simplifies the manufacture of the torque transmission surfaces.

[0036] According to a preferred embodiment, the torque transmission surfaces can be in continuous contact with one another between the chamfer and the radius. This means that the wedge-shaped projection sections or the torque transmission surfaces—except for their respective transition areas to the end face pair—are flush with one another over their entire extent. This allows for particularly high torques to be transmitted.

[0037] Furthermore, the mutually facing axial end faces of the cutting head and cutting head driver can each be axially stepped by their respective projection section, so that a Z-shaped contour is produced in each case.

[0038] Such a Z-shaped contour has proven to be particularly advantageous in terms of its functionality and manufacturability.

[0039] According to a preferred embodiment, the cutting tool can have at least one cooling channel formed by a workpiece-side cooling channel section formed in the cutting head and a shaft-side cooling channel section formed in the cutting head driver. This means that a cooling channel for supplying cutting edges of the cutting tool with cooling lubricant extends through the entire cutting tool, is supplied at a shaft-side interface, for example in the form of a cooling lubricant supply, in the region of the cutting head driver, and is discharged again at a workpiece-side interface, for example in the form of a cooling lubricant outlet opening, in the region of the cutting head. Thus, the cutting edges can be sufficiently cooled during machining of the workpieces.

[0040] According to a further development of the preferred embodiment, the shaft-side cooling channel section in the region of the end face of the main body of the cutting head driver can merge / open into the workpiece-side cooling channel section in the region of the end face of the projection section of the cutting head. This means that the transfer of the cooling lubricant takes place in the region of the axial contact between the cutting head and the cutting head driver in order to enable a tight, particularly laterally, transfer of the cooling lubricant.Because the end face of the projection portion of the cutting head is pressed toward the end face of the main body of the cutting head driver in a lever-like manner due to the design of the torque transmission surface, a tight transition for the cooling lubricant can be created between the cutting head and the cutting head driver, preferably without separate sealing components or sealing means, at which no cooling lubricant leaks. Consequently, an efficient cooling lubricant supply can be ensured.

[0041] According to a further development of the preferred embodiment, the cutting head can have at least one end cutting edge and a flank adjacent to the end cutting edge, with the cooling channel exiting the cutting tool in the region of the flank. In other words, the cooling lubricant exits at a workpiece-side end face of the cutting tool. Preferably, a separate cooling channel can be provided for each end cutting edge in order to be able to supply the cooling lubricant in a targeted manner to the highly stressed areas of the cutting tool.

[0042] According to a preferred embodiment, the cutting tool can have at least one helically extending circumferential cutting edge. The circumferential cutting edge can preferably extend from a cutting edge corner of the at least one end cutting edge. In particular, the number of circumferential cutting edges can correspond to the number of end cutting edges.

[0043] According to a further development of the preferred embodiment, the at least one circumferential cutting edge can be formed on the cutting head and the cutting head driver. This means that the circumferential cutting edge is not formed exclusively by the cutting head or the cutting head driver, but rather is axially continuous over the extension of the cutting head and the cutting head driver. A spiral of the at least one circumferential cutting edge is therefore not interrupted or changed by the multi-part design with cutting head and cutting head driver. The circumferential cutting edge is thus formed in axial sections by the cutting head and in axial sections by the cutting head driver. Accordingly, a chip groove adjacent to the at least one circumferential cutting edge can also be axially continuous over the extension of the cutting head and the cutting head driver, i.e. in axial sections by the cutting head and in axial sections by the cutting head driver.According to a further development of the preferred embodiment, the cutting tool can have a plurality of circumferential cutting edges, preferably two circumferential cutting edges. According to the further development of the preferred embodiment, the cutting head and the cutting head driver can each have a number of projection sections corresponding to the number of circumferential cutting edges. Accordingly, with two circumferential cutting edges, an angular range of 180° is formed, within which the two projection sections and a sufficiently large space to enable the mutual rotation of the cutting head and the cutting head driver are arranged. This has the advantage that the projection sections are sufficiently large for force transmission while ensuring rotatability.

[0044] According to a preferred embodiment, the cutting head driver can have two diametrically opposed projection sections formed by a web extending across the entire cutting tool diameter. This means that the two projection sections of the cutting head driver are connected to each other via a central section. In particular, the web can have the central section and the projection sections extending radially outward therefrom, for example, wing-shaped.

[0045] According to a preferred embodiment, the cutting head can have two diametrically opposed projection portions that are radially spaced from each other / are formed individually / as individual pins. This means that a central recess is formed between the two projection portions of the cutting head, into which the central portion of the cutting head driver can engage.

[0046] According to a preferred embodiment, the cutting head can have two diametrically opposed projection sections formed by a web extending over the entire cutting tool diameter. This means that the two projection sections of the cutting head are connected to one another via a central section. In particular, the web can have the central section and the projection sections extending radially outward therefrom, for example in a fan-like manner, for example in a wing-like configuration. According to a preferred embodiment, the cutting head driver can have two diametrically opposed projection sections which are spaced apart from one another in the radial direction / are individual / are formed as individual pins. This means that a central recess is formed between the two projection sections of the cutting head driver, into which the central section of the cutting head can engage.

[0047] According to a preferred embodiment, an axial contact surface between the cutting head and the cutting head driver can have a central section and wing sections extending radially outward from it, for example, in a fan-like manner. This means that the axial contact surface is preferably formed on the web extending over the axis of rotation, in particular extending over the entire cutting tool diameter. This provides a sufficient axial support surface. In particular, a transition of the cooling channels between the cutting head and the cutting head driver is also arranged in the axial contact surface.

[0048] According to a further development of the preferred embodiment, the wing sections can initially taper starting from the central section, in particular on both sides in the circumferential direction, and then widen again, in particular on both sides in the circumferential direction. This means that the wing sections are each waisted, i.e. have a substantially hourglass shape. In particular, the wing sections can have a substantially concave side edge on at least one side, which is arranged on the contact surface for the cutting head or cutting head driver. Preferably, the wing sections can have substantially concave side edges on both sides. One of the concave side edges is part of the chip groove and the other of the concave side edges is part of the contact surface for the cutting head or cutting head driver.Such a concave shape allows for a geometry particularly suitable for contact in the circumferential direction / cutting direction between the cutting head and the cutting head driver with regard to torque transmission and centering. According to a further development of the preferred embodiment, the axial contact surface can be designed with a substantially double waist. Such a double waist allows for a geometry particularly suitable for torque transmission and centering.

[0049] According to a preferred embodiment, a circumferential contact surface between the cutting head and the cutting head driver can be curved in the radial direction. This means that the contact surface at which the cutting head and the cutting head driver abut each other in the circumferential direction / cutting direction is not aligned linearly or exactly or substantially in the radial direction. In particular, the circumferential contact surface formed on the cutting head or on the continuous web is substantially concavely curved, and the complementary circumferential contact surface formed on the cutting head driver or on the individual pins is substantially convexly curved. With such a design, the circumferential contact surface can serve both for torque transmission between the cutting head and the cutting head driver and for the centered alignment of the cutting head to the cutting head driver.At the same time, stress peaks in the material are avoided.

[0050] According to a further development of the preferred embodiment, the circumferential contact surface can have a radially inner section and a radially outer section (relative to the radially inner section), which serve as the torque transmission surfaces. This means that the radially inner section extends in a region radially inwardly spaced from the tool diameter, and the radially outer section extends in a region radially outwardly spaced from the axis of rotation. In this way, a surface extending particularly long in the radial direction can be used for torque transmission. The radially inner section and the radially outer section of the circumferential contact surface can serve predominantly or exclusively / solely for torque transmission. Alternatively, there can be further surfaces that contribute to the torque transmission between the cutting head and the cutting head driver.

[0051] According to a further development of the preferred embodiment, the radially outer section can extend (as viewed in the radial direction) to the tool diameter. The radially outer arrangement of the radially outer section ensures the transmission of particularly high torques.

[0052] According to a further development of the preferred embodiment, the radially inner section can extend (as viewed in the radial direction) to the axis of rotation. Thus, the radially inner region can also be used for torque transmission.

[0053] According to a further development of the preferred embodiment, the radially inner section of the circumferential contact surface formed on the cutting head or on the continuous web can be substantially convexly curved in the radial direction, and the radially inner section of the complementary circumferential contact surface formed on the cutting head driver or on the individual pins can be substantially concavely curved in the radial direction. In particular, the radially inner section can be arranged in the region of the central section of the axial contact surface.

[0054] According to a further development of the preferred embodiment, the radially outer section of the circumferential contact surface, which is formed on the cutting head or on the continuous web, can be substantially concavely curved in the radial direction, and the radially outer section of the complementary circumferential contact surface, which is formed on the cutting head driver or on the individual pins, can be substantially convexly curved in the radial direction. In particular, the radially outer section can be arranged in the region of the wing section, in particular in the widening region of the wing section, of the axial contact surface. According to a further development of the preferred embodiment, the radially inner section and the radially outer section can each have a radius of curvature that is eccentric to the axis of rotation, i.e. not concentric to the axis of rotation.This ensures that the torques acting during workpiece machining can be transmitted between the cutting head and the cutting head driver.

[0055] According to a further development of the preferred embodiment, the circumferential contact surface can have a clamping section located in the radial direction between the radially inner section and the radially outer section, which serves primarily or exclusively as a clamping surface. This means that the radially inner section and the radially outer section are spaced apart from each other in the radial direction. The clamping section located therebetween can be designed such that it serves / contributes little or nothing to torque transmission.

[0056] According to a further development of the preferred embodiment, the torque transmission surfaces formed by the radially inner section and the radially outer section can extend in the axial direction over a maximum of half the axial extent of the projection sections. This means that the chamfer and the radius, over which the torque transmission surfaces transition into the end faces of the projection section or main body, occupy a large part of the axial extent of the respective projection sections.

[0057] Preferably, the projection portion of the cutting head can have a substantially oval cross-section. In particular, the projection portion of the cutting head can have two substantially semicircular or C-shaped circumferential portions opposite in the circumferential direction, as well as two substantially rectilinear circumferential portions opposite in the circumferential direction. In each case, one of the semicircular or C-shaped circumferential portions merges into one of the rectilinear circumferential portions. This means that the rectilinear circumferential portions adjoin the semicircular or C-shaped circumferential portions tangentially. In particular, the torque transmission surface of the cutting head can be formed by (outer) circumferential surfaces (alternatively by (inner) circumferential surfaces) of the projection portion of the cutting head.Accordingly, the torque transmission surface of the cutting head driver can be formed by (inner) circumferential surfaces (alternatively by (outer) circumferential surfaces) of the projection portion of the cutting head driver. The torque transmission surfaces of the cutting head and the cutting head driver are, in particular, those circumferential surfaces on which the cutting head and the cutting head driver abut each other in the connected state.

[0058] According to a preferred embodiment, the torque transmission surfaces can be formed by curved sections with different radii. This means that the substantially semicircular or C-shaped circumferential sections are in turn formed by individual curved sections, so that the curvature changes over the curved course of the circumferential sections. The curved sections can preferably be designed such that they merge into one another over the circumferential contour, i.e., the course in the circumferential direction / the circumferential extension. This means that the transition between the different radii occurs without a kink or visible edge / seam.

[0059] According to a preferred embodiment, the torque transmission surfaces can have at least a first curved section and a second curved section located directly behind it in the cutting direction, wherein the second curved section has a smaller radius than the first curved section. This guides or facilitates the insertion of the cutting head into the cutting head driver and / or provides a gentle stop. According to an alternative embodiment, the first curved section can have a smaller radius than the second curved section.

[0060] According to a further development of the preferred embodiment, the radius of the first curved section and the radius of the second curved section can have different center points. This has the advantage of allowing a seamless transition between the two curved sections.

[0061] According to a further development of the preferred embodiment, the center point of the second curved section can be located behind the center point of the first curved section in the cutting direction, preferably by a small amount, in particular by 0.1 mm to 0.4 mm. According to an alternative development of the preferred embodiment, the center point of the second curved section can be located in front of the center point of the first curved section in the cutting direction, preferably by a small amount, in particular by 0.1 mm to 0.4 mm. The slight offset of the center points allows for an edge-free transition between the two curved sections.

[0062] According to a preferred embodiment, the torque transmission surfaces can have a third curved section located in the cutting direction, in particular directly behind the second curved section, whose radius is significantly larger than the radius of the first and / or second curved section. For example, the third curved section can be configured to be almost straight. This facilitates the insertion of the cutting head into the cutting head driver.

[0063] According to a preferred embodiment, a circumferential surface of the cutting head can be substantially convexly curved in the region of the circumferential contour in which it rests against the cutting head driver in the connected state, and substantially concavely curved in the region of the circumferential contour in which it does not rest against the cutting head driver in the connected state.

[0064] According to a preferred embodiment, the cutting head can have a centering projection, preferably circular in cross-section and / or preferably concentrically aligned with the rotational axis of the cutting tool, which protrudes axially from the end face of the projection portion of the cutting head. This guides the cutting head during axial insertion into the cutting head driver, while simultaneously allowing rotation for engaging the bayonet lock.

[0065] According to a further development of the preferred embodiment, the torque transmission surface of the cutting head can have an axial extension substantially twice as large as the centering projection. This ensures sufficient centering when inserting the cutting head.

[0066] Short description of the characters

[0067] Fig. 1 is a perspective view of a portion of a cutting tool having a cutting head and a cutting head driver according to a first embodiment of the present disclosure;

[0068] Fig. 2 is a perspective view of the cutting tool in an unconnected state of the cutting head and the cutting head driver;

[0069] Fig. 3 is a side view of the cutting tool in the unconnected state;

[0070] Fig. 4 is a side view of the cutting tool in a connected state of the cutting head and the cutting head driver;

[0071] Fig. 5 is a side view of the cutting tool in the connected state, rotated about a longitudinal axis of the cutting tool relative to Fig. 4;

[0072] Fig. 6 is an enlarged view of a detail from Fig. 5;

[0073] Fig. 7 is a bottom view of the cutting head;

[0074] Fig. 8 is a top view of the cutting head driver; Fig. 9 is a perspective view of a portion of the cutting tool according to a second embodiment of the present disclosure;

[0075] Fig. 10 is a perspective view of the cutting tool in an unconnected state of the cutting head and the cutting head driver;

[0076] Fig. 11 is a side view of the cutting tool in the unconnected state;

[0077] Figs. 12 and 12A are side views of the cutting tool in a connected state of the cutting head and the cutting head driver;

[0078] Fig. 13 is a side view of the cutting tool in the connected state, rotated about a longitudinal axis of the cutting tool relative to Figs. 12 and 12A;

[0079] Fig. 14 is an enlarged view of a detail from Fig. 12A;

[0080] Fig. 15 is a bottom view of the cutting head;

[0081] Fig. 16 is a top view of the cutting head driver;

[0082] Figs. 17 and 18 are perspective views of the cutting head and the cutting head driver;

[0083] Figs. 19 and 20 are perspective views of the cutting head according to a third embodiment of the present disclosure;

[0084] Fig. 21 is a bottom view of the cutting head;

[0085] Figs. 22 and 23 are side views of the cutting head;

[0086] Fig. 24 is a perspective view of the cutting head driver according to the second embodiment of the present disclosure; Fig. 25 is a top view of the cutting head driver;

[0087] Fig. 26 is a longitudinal sectional view of the cutting head driver;

[0088] Fig. 27 is a diagram showing the principle of a cutting tool of the prior art; and

[0089] Fig. 28 is a diagram illustrating the principle of the cutting tool according to the present disclosure.

[0090] Description of the embodiments

[0091] Figs. 1 to 8 show different representations of a cutting tool 2 according to a first embodiment of the present disclosure, or sections and individual components thereof. The cutting tool 2 is used for machining workpieces. The cutting tool 2 is designed as a shank tool, such as a milling cutter or a drill.

[0092] The cutting tool 2 has at least one end cutting edge, preferably several, in the illustrated embodiment two, end cutting edges 4, which are formed on one end face of the cutting tool 2. A (main) flank 6 is adjacent to each end cutting edge 4.

[0093] The cutting tool 2 has at least one circumferential cutting edge, preferably several, in the illustrated embodiment two, circumferential cutting edges 8. The circumferential cutting edges 8 extend helically over an outer side of the cutting tool 2. In particular, each circumferential cutting edge 8 can originate from a cutting edge corner of one of the end cutting edges 4.

[0094] The cutting tool 2 is constructed in several parts and has a cutting head 10 (cutting attachment) and a cutting head driver 12 (carrier). The cutting head 10 and the cutting head driver 12 adjoin one another in the axial direction of the cutting tool 2, with the cutting head 10 forming a workpiece-side section and the cutting head driver 12 forming a shaft-side section. The cutting head 10 and the cutting head driver 12 can be (removably) connected to one another via a type of bayonet lock / bayonet connection. In a connected state, the cutting head 10 and the cutting head driver 12 are connected / attached to one another in a torque-transmitting and axially fixed manner. By mutual rotation in a first direction of rotation, for example by rotating the cutting head 10 against a cutting direction of the cutting tool 2, the cutting head 10 and the cutting head driver 12 can be connected to one another in a form-fitting manner.By mutually rotating them in a second direction of rotation (opposite to the first direction of rotation), for example by rotating the cutting head 10 in a cutting direction of the cutting tool 2, the cutting head 10 and the cutting head driver 12 can be detached from each other.

[0095] The end cutting edges 4 of the cutting tool 2 are formed on the cutting head 10. The peripheral cutting edges 8 of the cutting tool 2 are formed both (in sections) on the cutting head 10 and (in sections) on the cutting head driver 12. Thus, the peripheral cutting edges 8 extend continuously in the axial direction, i.e., also over the connection between the cutting head 10 and the cutting head driver 12. Consequently, the bayonet connection, via which the cutting head 10 and the cutting head driver 12 can be connected, is arranged within a cutting section of the cutting tool 2.

[0096] The cutting head 10 and the cutting head driver 12 can be made of different materials. Preferably, the cutting head 10 can be made of hard metal. Preferably, the cutting head driver 12 can be made of steel.

[0097] Furthermore, as an alternative to the described embodiment, the cutting head 10 and the cutting head driver 12 can both be made of the same material Z material group, e.g. both of steel, as long as their material properties differ and it is ensured that in the bayonet-like connection between sections of the cutting head 10 and the cutting head driver 12 with a Z-angle geometry or with two mutually engaging wedge geometries, the loads resulting from the wedge forces are shifted to the section which is the more flexurally elastic, softer or less brittle section in comparison.

[0098] The cutting head 10 has a main body 14, from the end face of which a projection portion 16 projects axially. The projection portion 16 projects in the direction of the cutting head driver 12 and is used for bayonet-like attachment to the cutting head driver 12. The projection portion 16 is undercut in the axial direction and has a torque transmission surface 18, which is preferably inclined in the axial direction. The torque transmission surface 18 is preferably formed substantially in the radial direction, i.e. perpendicular to the tangential direction, in order to be able to transmit a torque. Due to the projection portion 16, an end face of the cutting head 10 (facing the cutting head driver 12 / facing away from the workpiece) is axially stepped, resulting in a substantially Z-shaped contour.The Z-shaped contour is formed by an axial end face 20 of the projection portion 16, the axially positioned torque transmission surface 18 of the projection portion 16, and an axial end face 22 of the main body 14. The axial end face 20 of the projection portion 16 transitions into the torque transmission surface 18 via a chamfer 19. The torque transmission surface 18 transitions into the axial end face 22 of the main body 14 via a radius 21.

[0099] The cutting head 10 has a number of projection sections 16 corresponding to the number of circumferential cutting edges 8. This means that the cutting head 10, in the illustrated embodiment, has two projection sections 16. The two projection sections 16 are arranged diametrically opposite one another. The projection sections 16 of the cutting head 10 are spaced apart from one another in the radial direction / are formed individually. This means that they are separated from one another by a central recess / are not continuously connected to one another across the cutting tool diameter. Alternatively, the projection sections 16 (with a corresponding design of the cutting head driver 12) can also be formed by a web extending continuously across the cutting tool diameter.

[0100] The cutting head driver 12 has a main body 24, from the end face of which a projection portion 26 projects axially. The projection portion 26 projects in the direction of the cutting head 10 and is used for bayonet-like attachment to the cutting head 10. The projection portion 26 is undercut in the axial direction and has a torque transmission surface 28, which is preferably inclined in the axial direction. The torque transmission surface 28 is preferably formed substantially in the radial direction, i.e. perpendicular to the tangential direction, in order to be able to transmit a torque. Due to the projection portion 26, an end face of the cutting head driver 12 (facing the cutting head 10 / facing away from the shaft) is axially stepped, resulting in a substantially Z-shaped contour.The Z-shaped contour is formed by an axial end face 30 of the projection portion 26, the axially angled torque transmission surface 28 of the projection portion 26, and an axial end face 32 of the main body 24. The axial end face 30 of the projection portion 26 transitions into the torque transmission surface 28 via a chamfer 29. The torque transmission surface 28 transitions into the axial end face 32 of the main body 24 via a radius 31.

[0101] The cutting head driver 12 has a number of projection sections 26 corresponding to the number of circumferential cutting edges 8. This means that the cutting head driver 12, in the illustrated embodiment, has two projection sections 26. The two projection sections 26 are arranged diametrically opposite one another. The two projection sections 26 are formed by a web extending across the entire cutting tool diameter. This means that the projection sections 26 are continuously connected to one another across the cutting tool diameter. Alternatively, the projection sections 26 (with a corresponding design of the cutting head 10) can also be spaced apart from one another in the radial direction / be formed individually.

[0102] The torque transmission surface 18 of the cutting head 10 and the torque transmission surface 28 of the cutting head driver 12 are designed to complement each other, so that they rest flat against each other when connected. Due to the angled design / inclination of the torque transmission surfaces 18, 28 and the resulting leverage, the cutting head 10 and the cutting head driver 12 are axially pressed toward each other / axially clamped when connected.

[0103] According to the present disclosure, the projection portions 16, 26 of the cutting head 10 and the cutting head driver 12 are dimensioned such that the end face 20 of the projection portion 16 of the cutting head 10, in the connected state, abuts the end face 32 of the main body 24 of the cutting head driver 12 in the axial direction. Thus, the projection portion 16 of the cutting head 10 is supported on the main body 24 of the cutting head driver 12.

[0104] In addition, the end face 30 of the projection portion 26 of the cutting head driver 12 is spaced apart from the end face 22 of the main body 14 of the cutting head 10 with axial clearance when connected. Thus, the main body 14 of the cutting head 10 is not supported on the projection portion 26 of the cutting head driver 12.

[0105] Preferably, the projection portion 16 of the cutting head 10 can be (slightly) longer in the axial direction than the projection portion 26 of the cutting head driver 12.

[0106] Furthermore, the cutting tool 2 has at least one cooling channel, preferably several, in the illustrated embodiment two cooling channels 34. The cooling channels 34 serve to supply cooling lubricant to stressed areas of the cutting tool 2, in particular to the cutting edges, such as the end cutting edges 4. In particular, the cooling channels 34 can exit the cutting tool 2 in the region of the flank surfaces 6.

[0107] The cooling channels 34 are each formed by a workpiece-side cooling channel section 36 formed in the cutting head 10 and a shaft-side cooling channel section 38 formed in the cutting head driver 12. Preferably, the cooling lubricant can be supplied centrally and distributed to the shaft-side cooling channel sections 38.

[0108] The shaft-side cooling channel section 38 opens into the workpiece-side cooling channel section 36 in an area in which the cutting head driver 12 rests flush, preferably tightly, against the cutting head 10. In the illustrated embodiment, the cooling channel section 38 merges into the cooling channel section 36 in the area of ​​the end face 32 of the main body 24 of the cutting head driver 12 or in the area of ​​the end face 20 of the projection section 16 of the cutting head 10.

[0109] The cutting tool 2 has a shank portion 40, via which the cutting tool 2 can be clamped into a tool holder and driven in rotation. The shank portion 40 adjoins the cutting head driver 12 in the axial direction on a side facing away from the cutting head 10.

[0110] Figs. 9 to 18 show a second embodiment of the cutting tool 2. The second embodiment has largely the same features as the first embodiment, so that only the differences are explained below.

[0111] The two projection sections 16 of the cutting head 10 are formed by a web extending across the entire cutting tool diameter. This means that the projection sections 16 are continuously connected to one another across the cutting tool diameter. The two projection sections 26 of the cutting head driver 12 are arranged diametrically opposite one another. The projection sections 26 of the cutting head driver 12 are radially spaced from one another / are formed individually. This means that they are separated from one another by a central recess / are not continuously connected to one another across the cutting tool diameter.

[0112] Figs. 17 and 18 show perspective views of the cutting head 10 and the cutting head driver 12, based on which a particularly advantageous embodiment of the projection sections 16, 26 will be explained below. In the perspective views, the contact surfaces where the cutting head 10 and the cutting head driver 12 abut each other are shown hatched.

[0113] An axial contact surface 80 is formed on the axial end face 20 of the continuous web of the projection sections 16 of the cutting head 10 and the complementary surface on the axial end face 32 of the main body 24 or the recess between the projection sections 26 of the cutting head driver 12. The axial contact surface 80 has a central section 82 and two wing sections 84 extending radially outward therefrom, for example, in a fan-like manner. The wing sections 84 are tapered, so that they initially taper from the central section 82 and then widen again.

[0114] A circumferential contact surface 86 is formed on the side surface of the projection sections 16 of the cutting head 10 transverse to the cutting direction and on the complementary surface on the side surface of the projection sections 26 of the cutting head driver 12 transverse to the cutting direction. The circumferential contact surface 86 is curved in the radial direction. The circumferential contact surface 86 formed on the cutting head side is substantially concavely curved, and correspondingly, the circumferential contact surface 86 formed on the cutting head driver side is substantially convexly curved.

[0115] The circumferential contact surface 86 has a radially inner section 88 and a radially outer section 90. The sections 88, 90 serve as the torque transmission surfaces 18, 28. The radially inner section 88 is spaced radially inward relative to the tool diameter. The radially outer section 90 is arranged radially outside the radially inner section 88 and is spaced radially outward relative to the axis of rotation. The radially outer section 90 extends radially up to the tool diameter. The radially inner section 88 extends radially up to the axis of rotation.

[0116] The radially inner section 88 is substantially convexly curved at the circumferential contact surface 86 formed on the cutting head side and, correspondingly, substantially concavely curved at the circumferential contact surface 86 formed on the cutting head receiver side. The radially outer section 90 is substantially concavely curved at the circumferential contact surface 86 formed on the cutting head side and, correspondingly, substantially convexly curved at the circumferential contact surface 86 formed on the cutting head receiver side. The radially inner section 88 and the radially outer section 90 each have a radius of curvature that is eccentric to the axis of rotation, i.e., not concentric to the axis of rotation.

[0117] The circumferential contact surface 86 has a clamping section 92 located radially between the radially inner section 88 and the radially outer section 90, which serves primarily or exclusively as a clamping surface (and preferably serves little or no torque transmission). This means that the radially inner section 88 and the radially outer section 90 are spaced apart from each other radially.

[0118] The torque transmission surfaces 18, 28 formed by the radially inner section 88 and the radially outer section 90 extend in the axial direction over a maximum of half the axial extent of the projection sections 16, 26. This means that the chamfer 19, 29 and the radius 21, 31, via which the torque transmission surfaces 18, 28 merge into the end faces 20, 22, 30, 32 of the projection section 16, 26 or main body 14, 24, take up a large part of the axial extent of the respective projection section 16, 26.

[0119] Figs. 19 to 26 show a third embodiment of the cutting tool 2, on the basis of which a particularly advantageous design of the projection sections 16, 26 and in particular the structural design of the torque transmission surfaces 18, 28 will be explained below.

[0120] Figs. 19 to 23 show various views of the cutting head 10. The cutting head 10 has the main body 14, from the end face of which the axially undercut projection portion 16 projects axially. The projection portion 16 of the cutting head 10 has a substantially oval cross-section. In particular, the projection portion 16 has two opposite first circumferential portions 42 and two opposite second circumferential portions 44, which each merge into one another. The first circumferential portions 42 are convexly curved and have a substantially semicircular or C-shaped contour. The second circumferential portions 44 have a substantially rectilinear or very slightly concave contour.

[0121] The first circumferential sections 42 are each composed of several curved sections 46, 48 with different radii. In particular, the first circumferential sections 42 each have a first curved section 46 and a second curved section 48 located directly behind it in the cutting direction. The first curved section 46 extends approximately over an eighth of a circle. The second curved section 48 extends approximately over a quarter of a circle.

[0122] The second curved section 48 has a smaller radius than the first curved section 46. The radius of the first curved section 46 and the radius of the second curved section 48 have different center points. The center point of the second curved section 48 is located in the cutting direction, preferably by a small amount, in particular by 0.1 mm to 0.4 mm, behind the center point of the first curved section 46.

[0123] The first circumferential sections 42 each transition into the second circumferential sections 44 via a transition section 50. The transition section 50 lies in the cutting direction, in particular directly, behind the second curved section 48. The transition section 50 has a radius that is larger than the radius of the second curved section 48. The transition section 50 is adjoined in the circumferential direction by the second circumferential section 44, which in the illustrated embodiment is formed by a third curved section 52 that is slightly convex. This means that the radius of the third curved section 52 is considerably larger, for example at least 8 times as large as the radius of the second curved section 48. The second circumferential section 44 is in turn adjoined by one of the first circumferential sections 42, with an edge 54 being formed between the two circumferential sections 42, 44.

[0124] Figs. 22 and 23 show side views of the cutting head 10. It can be seen that the projection portion 16 extends directly from the main body 14. This results in the Z-shape formed by the end face of the main body 14, the torque transmission surface 18, and the end face of the projection portion 16.

[0125] The projection portion 16 is substantially trapezoidal in longitudinal section, with the inclined side surfaces of the trapezoid forming the torque transmission surface 18 of the cutting head 10. The torque transmission surface 18 is inclined to the axial direction at an axial angle of attack, preferably from 2° to 5°, in particular from 3°.

[0126] The axial angle of attack is constant at least over the entire circumferential contour of the torque transmission surface, in particular over the entire circumferential contour of the projection section 16, i.e. both in the region of the first circumferential sections 42 and in the region of the second circumferential sections 44. For example, the radii of the different curved sections 46, 48 or of the transition section 50 or of the circumferential sections 42, 44 are intersected. Furthermore, the axial angle of attack is constant over the entire axial extent of the projection section 16. This means that in the region of the torque transmission surface 18 or in the region of the first circumferential sections 42 (and possibly also the second circumferential sections 44), no steps, elevations or depressions are formed in the side surfaces of the projection section 16, but rather the side surfaces are a continuous inclined surface.In other words, the Z-shape of the projection portion 16 is uniform over the entire circumferential contour.

[0127] At its narrowest point, the projection portion 16 is approximately 1.5 to 3 times, preferably approximately twice, as wide as the projection portion 16 extends in the axial direction. The axial dimensioning ensures a sufficiently large axial undercut.

[0128] In addition, the cutting head 10 has a centering projection 56, preferably circular in cross-section and / or preferably concentrically aligned to the rotational axis of the cutting tool 2. The centering projection 56 protrudes in the axial direction from the end face of the projection section 16 of the cutting head 10. When the cutting tool 2 is connected, the centering projection 56 engages in a correspondingly formed recess 58 in the cutting head driver 12. For example, the projection section 16 or the torque transmission surface 18 of the cutting head 10 has an axial extent essentially twice that of the centering projection 56.

[0129] Figs. 24 to 26 show various views of the cutting head driver 12. The cutting head driver 12 has the main body 24, from the end face of which the undercut projection portion 26 projects axially. The projection portion 26 is formed by two diametrically opposed webs 60, which comprise a recess whose shape corresponds to the shape of the projection portion 16 of the cutting head 10. In the connected state of the cutting tool 2, the projection portion 16 of the cutting head rests with its outer circumferential surfaces, which serve as the torque transmission surface 18 of the cutting head 10, on the inner circumferential surfaces of the projection portion 26 of the cutting head driver 12, which in turn serve as the torque transmission surface 28 of the cutting head driver 12.

[0130] The shape of the inner circumferential surfaces of the cutting head driver 12 corresponds to the shape of the first circumferential sections 42 of the cutting head 10. This means that the inner circumferential surfaces of the cutting head driver 12 or the webs 60 are each composed of several curved sections with different radii. In particular, the webs 60 each have a first curved section 62 and a second curved section 64 located directly behind it in the cutting direction. The first curved section 62 extends approximately over one-eighth of a circle. The second curved section 64 extends approximately over a quarter of a circle.

[0131] The second curved section 64 has a smaller radius than the first curved section 62. The radius of the first curved section 62 and the radius of the second curved section 64 have different center points. The center point of the second curved section 64 lies behind the center point of the first curved section 62 in the cutting direction, preferably by a small amount, in particular by 0.1 mm to 0.4 mm.

[0132] A transition section 66 adjoins the two curved sections 62, 64. The transition section 66 is located in the cutting direction, in particular directly behind the second curved section 64. The transition section 66 has a radius that is considerably larger than the radius of the second curved section 64, so that the transition section 66 is, for example, approximately rectilinear.

[0133] The inner circumferential surfaces of the webs 60 serving as the torque transmission surface 28 are inclined to the axial direction at an axial angle of incidence, preferably from 2° to 5°, in particular 3°. In particular, the axial angle of incidence of the torque transmission surface 28, i.e., the axial angle of incidence of the cutting head driver 12, corresponds to the axial angle of incidence of the torque transmission surface 18, i.e., the axial angle of incidence of the cutting head 10. This means that the cutting head driver 12 and the cutting head 10 are axially angled at the same angle of incidence. The axial angle of incidence is constant over the entire circumferential contour of the torque transmission surface 28. For example, the radii of the different curved sections 62, 64 and the transition section 66 are intersected. Furthermore, the axial angle of incidence is constant over the entire axial extent of the projection section 26.This means that there are no steps, elevations, or depressions in the area of ​​the torque transmission surface 28, but rather the side surfaces are a continuous, inclined surface. In other words, the Z-shape of the webs 60 is uniform over the entire circumferential contour.

[0134] The cutting head driver 12 has a recess 58 into which the centering projection 56 engages when the cutting tool 2 is connected. In the illustrated embodiment, the recess 58 is designed as a through hole. Alternatively, the recess 58 can also be designed as a blind hole, although this is not shown.

[0135] Figures 27 and 28 show representations of the principle of a cutting tool known from the prior art and of the cutting tool 2 according to the present disclosure, based on which a crucial aspect of the cutting tool, which is common to the three embodiments already described, is explained again. Figures 27 and 28 are each sectional views in a plane that is offset parallel to a longitudinal plane containing the axis of rotation.

[0136] As can be seen in Fig. 27, the prior art solution is such that the end face 20 of the projection portion 16 of the cutting head 10 is spaced from the end face 32 of the main body 24 of the cutting head driver 12, and that the end face 22 of the main body 14 of the cutting head 10 bears against the end face 30 of the projection portion 26 of the cutting head driver 12. This means that in the prior art, an axial gap is formed between the free end of the cutting head 10, in particular the portion forming the torque transmission surface 18, namely the wedge-shaped projection portion 16, and the cutting head driver 12. In contrast, the free end of the cutting head driver 12, in particular the section forming the torque transmission surface 28, namely the wedge-shaped projection section 26, rests against the cutting head 10.This creates a lever arm on the cutting head driver 12, which in turn causes a tensile stress in the radius 21, with the stress increasing with increasing lever. This causes the wedge-shaped recess of the cutting head 10 to expand. The resulting stresses in the radius 21 / notch are always present in such a design and can be somewhat reduced by increasing the radius 21.

[0137] As can be seen in Fig. 28, according to the present disclosure, it is solved such that the end face 20 of the projection portion 16 of the cutting head 10 abuts the end face 32 of the main body 24 of the cutting head driver 12, and that the end face 22 of the main body 14 of the cutting head 10 is spaced from the end face 30 of the projection portion 26 of the cutting head driver 12. This means that in the present disclosure, no axial gap is formed between the free end of the cutting head 10, in particular the portion forming the torque transmission surface 18, namely the wedge-shaped projection portion 16, and the cutting head driver 12, but rather the cutting head 10 abuts the end face 20 of the wedge-shaped projection portion 16 against the cutting head driver 12. This has the effect that a wedge support is provided by the axial contact of the cutting head 10 to the cutting head driver 12.The axial support of the cutting head provides tangential guidance, reducing bending stress. Furthermore, the frictional force (created by the axial contact) acts transversely to the axial direction and thus counteracts the load (created by the torque transmission at the torque transmission surface 18), which in turn reduces the bending stress at radius 21 (compared to the prior art solution).

[0138] In other words, a force always acts on the torque transmission surfaces 18, 28 during workpiece machining, which force, due to the axial positioning of the torque transmission surfaces 18, 28, leads to a spreading of the respective wedge-shaped recesses and thus to a tensile stress in the radius 21, 31. In the cutting tool 2 of the present disclosure, however, the wedge support of the cutting head 10, i.e. the axial contact with the cutting head driver 12, induces a frictional force that acts transversely to the axial direction in the direction of the torque transmission surfaces 18, 28. This frictional force thus counteracts the spreading of the cutting head 10 (and not, as in the prior art, a spreading of the cutting head driver 12), which in turn can reduce the bending stress in the region of the radius 21.

Claims

Claims 1. Cutting tool (2) for machining workpieces, comprising a cutting head (10), preferably made of carbide, and a cutting head driver (12), preferably made of steel, which can be connected to the cutting head (10) via a bayonet fitting, wherein the cutting head (10) and the cutting head driver (12) each have a main body (14, 24) from the end face of which an axially undercut projection section (16, 26) projects axially, wherein the projection section (16) of the cutting head (10) and the projection section (26) of the cutting head driver (12) can be positively connected to each other by rotating the cutting head (10) against a cutting direction of the cutting tool (2), and each has complementary, axially undercut, preferably axially inclined torque transmission surfaces (18, 28). exhibiting which, in the connected state, are in contact with each other, characterized in thatthat the projecting sections (16, 26) of the cutting head (10) and the cutting head driver (12) are dimensioned such that an end face (20) of the projecting section (16) of the cutting head (10) rests axially against an end face (32) of the main body (24) of the cutting head driver (12) in the connected state.

2. Cutting tool (2) according to claim 1 , characterized in that an end face (30) of the projecting section (16) of the cutting head driver (12) is spaced apart from an end face (22) of the main body (14) of the cutting head (10) with axial clearance in the connected state.

3. Cutting tool (2) according to claim 1 or 2, characterized in that the projecting section (16) of the cutting head (10) is axially longer than the projecting section (26) of the cutting head driver (12).

4. Cutting tool (2) according to one of claims 1 to 3, characterized in that the projecting sections have surfaces or geometries which interlock when the cutting head and the cutting head driver are connected together.

5. Cutting tool (2) according to one of claims 1 to 4, characterized in that the cutting head and the cutting head driver have complementary geometries, such that the cross-section of the cutting head driver and the cross-section of the cutting head at their parting plane are essentially identical and / or a geometric profile of the cutting head driver, in particular a helical design, flutes and / or circumferential cutting edges, is continued through the cutting head.

6. Cutting tool (2) according to one of claims 1 to 5, characterized in that the torque transmission surfaces are axially positioned such that the cutting head is pressed axially towards the cutting head driver by cutting forces acting during workpiece machining.

7. Cutting tool (2) according to one of claims 1 to 6, characterized in that the torque transmission surfaces are designed such that a tangential force, which arises from cutting forces acting during workpiece machining, is converted into an axial force such that the cutting head is pressed axially into contact with the cutting head driver.

8. Cutting tool (2) according to one of claims 1 to 7, characterized in that the torque transmission surfaces (18, 28) are axially inclined with an axial angle of inclination, preferably from 2° to 15°, more preferably from 2° to 10°, particularly preferably from 2° to 5°, in particular from 3°.

9. Cutting tool (2) according to claim 8, characterized in that the torque transmission surface (18) of the cutting head (10) and the torque transmission surface (28) of the cutting head driver (12) have identical axial angles of approach.

10. Cutting tool (2) according to claim 8 or 9, characterized in that the axial angle of attack is constant over the entire circumferential contour of the torque transmission surfaces (18, 28).

11. Cutting tool (2) according to one of claims 8 to 10, characterized in that the axial angle of attack is constant over the entire axial extent of the torque transmission surfaces (18, 28).

12. Cutting tool (2) according to one of claims 1 to 11 , characterized in that the cutting head (10) and the cutting head driver (12) are Z-shaped in the area of ​​their bayonet closure.

13. Cutting tool (2) according to claim 12, characterized in that the Z-shape results from the fact that the cutting head (10) and the cutting head driver (12) each have a pair of end faces consisting of two end faces extending perpendicular to the axial direction and spaced apart from each other in the axial direction, and wherein the torque transmission surfaces (18, 28) connecting the respective end faces of a pair of end faces extend substantially continuously obliquely to the axial direction between the end faces of the respective pair of end faces.

14. Cutting tool (2) according to claim 13, characterized in that an axially outer end face of the end face pair transitions into the torque transmission surface via a chamfer.

15. Cutting tool (2) according to claim 13 or 14, characterized in that an axially inner end face of the end face pair transitions into the torque transmission surface via a radius.

16. Cutting tool (2) according to claims 14 and 15, characterized in that the torque transmission surface (18, 28) is designed as a continuously inclined surface between the chamfer and the radius.

17. Cutting tool (2) according to claim 14 and 15 or according to claim 16, characterized in that the torque transmission surfaces (18, 28) are in continuous contact with each other between the chamfer and the radius.

18. Cutting tool (2) according to one of claims 12 to 17, characterized in that the mutually facing axial end faces of the cutting head (10) and the cutting head driver (12) are each axially stepped by their respective projecting section (16. 26), so that a Z-shaped contour is obtained in each case.

19. Cutting tool (2) according to one of claims 1 to 18, characterized in that the cutting tool (2) has at least one cooling channel (34) which is formed by a workpiece-side cooling channel section (36) formed in the cutting head (10) and a shaft-side cooling channel section (38) formed in the cutting head driver (12), wherein the shaft-side cooling channel section (38) opens into the workpiece-side cooling channel section (36) in the area of ​​the end face (32) of the main body (24) of the cutting head driver (12) in the area of ​​the end face (20) of the projection section (16) of the cutting head (10).

20. Cutting tool (2) according to claim 19, characterized in that the cutting head (10) has at least one end cutting edge (4) and a clearance surface (6) adjacent to the end cutting edge (4), wherein the cooling channel (34) exits the cutting tool (2) in the area of ​​the clearance surface (6).

21. Cutting tool (2) according to one of claims 1 to 20, characterized in that the cutting tool (2) has at least one circumferential cutting edge (8) extending in a spiral shape, which is formed on the cutting head (10) and the cutting head driver (12).

22. Cutting tool (2) according to claim 21, characterized in that the cutting tool (2) has two circumferential cutting edges (8), and the cutting head (10) and the cutting head driver (12) each have a number of projection sections (16, 26) corresponding to the number of circumferential cutting edges (8).

23. Cutting tool (2) according to one of claims 1 to 22, characterized in that the cutting head driver (2) has two diametrically opposed projection sections (26) which are formed by a web extending over the entire diameter of the cutting tool.

24. Cutting tool (2) according to one of claims 1 to 23, characterized in that the cutting head (10) has two diametrically opposed projection sections (16) which are designed as pins / ribs spaced apart from each other in the radial direction.

25. Cutting tool (2) according to one of claims 1 to 22, characterized in that the cutting head (10) has two diametrically opposed projection sections (16) which are formed by a web extending over the entire diameter of the cutting tool.

26. Cutting tool (2) according to one of claims 1 to 22 or claim 25, characterized in that the cutting head driver (12) has two diametrically opposed projection sections (16) which are designed as pins / ribs spaced apart from each other in the radial direction.

27. Cutting tool (2) according to one of claims 1 to 26, characterized in that an axial contact surface (80) between the cutting head (10) and the cutting head driver (12) has a central section (82) and wing sections (84) extending radially outwards from it, wherein the wing sections taper from the central section, in particular on both sides in the circumferential direction, and then widen again, in particular on both sides in the circumferential direction.

28. Cutting tool according to claim 27, characterized in that the axial contact surface (80) is essentially double-wavy.

29. Cutting tool (2) according to one of claims 1 to 28, characterized in that a circumferential contact surface (86) between the cutting head (10) and the cutting head driver (12) is curved in the radial direction.

30. Cutting tool (2) according to claim 29, characterized in that the circumferential contact surface (86) has a radially inner section (88) and a radially outer section (90) which serve as the torque transmission surfaces (18, 28).

31. Cutting tool (2) according to claim 30, characterized in that the radially outer section (90) extends to the tool diameter.

32. Cutting tool (2) according to claim 30 or 31, characterized in that the radially inner section (88) of the circumferential contact surface formed on the cutting head is substantially convex in the radial direction and the radially inner section (88) of the complementary circumferential contact surface formed on the cutting head driver is substantially concave in the radial direction.

33. Cutting tool (2) according to one of claims 30 to 32, characterized in that the radially outer section (90) of the circumferential contact surface formed on the cutting head is substantially concave in the radial direction and the radially outer section (90) of the complementary circumferential contact surface formed on the cutting head driver is substantially convex in the radial direction.

34. Cutting tool (2) according to one of claims 30 to 33, characterized in that the radially inner section (88) and the radially outer section (90) each have a radius of curvature that is eccentric to the axis of rotation.

35. Cutting tool (2) according to one of claims 30 to 34, characterized in that the circumferential contact surface (86) has a clamping section located in the radial direction between the radially inner section and the radially outer section, which serves predominantly or exclusively as a clamping surface.

36. Cutting tool (2) according to one of claims 30 to 35, characterized in that the torque transmission surfaces (18, 28) formed by the radially inner section (88) and the radially outer section (90) extend in the axial direction over a maximum of half the axial extent of the projection sections (16, 26).

37. Cutting tool (2) according to one of claims 1 to 36, characterized in that the torque transmission surfaces (18, 28) are formed by curved sections with different radii, wherein the curved sections are designed such that they merge into one another over the entire circumferential contour of the torque transmission surfaces (18, 28).

38. Cutting tool (2) according to claim 37, characterized in that the torque transmission surfaces (18, 28) have at least a first curvature section (46, 62) and a second curvature section (48, 64) located in the cutting direction, in particular directly behind it, wherein the second curvature section (48, 64) has a smaller radius than the first curvature section (46, 62).

39. Cutting tool (2) according to claim 38, characterized in that the radius of the first curvature section (48, 64) and the radius of the second curvature section (46, 62) have different centers of gravity.

40. Cutting tool (2) according to claim 39, characterized in that the center of the second curvature section (46, 62) is located in the cutting direction, preferably by a small amount, in particular by 0.1 mm to 0.4 mm, behind the center of the first curvature section (48, 64).

41. Cutting tool (2) according to one of claims 38 to 40, characterized in that the torque transmission surfaces (18, 28) have a third curvature section (50, 66) located in the cutting direction, in particular directly, behind the second curvature section (48, 64), the radius of which is significantly larger than the radius of the first curvature section (46, 62) and / or second curvature section (48, 64).

42. Cutting tool (2) according to one of claims 1 to 41, characterized in that a circumferential surface of the cutting head (10) in the area of ​​the circumferential contour in which it rests against the cutting head driver (12) in the connected state is substantially convexly curved and in the area of ​​the circumferential contour in which it does not rest against the cutting head driver (12) in the connected state is substantially concavely curved.

43. Cutting tool (2) according to one of claims 1 to 42, characterized in that the cutting head (10) has a centering projection (56), preferably circular in cross-section and / or preferably aligned concentrically to the axis of rotation of the cutting tool (2), which projects axially from the end face of the projection section (16) of the cutting head (10).

44. Cutting tool (2) according to claim 43, characterized in that the torque transmission surface (18) and / or the projection section (16) of the cutting head (10) has / has an axial extent substantially twice as large as the centering projection (56).

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