Cutting tool with cutting head and cutting head driver

Abstract

A cutting tool (2) for cutting a workpiece, comprising a cutting head (10) and a cutting head driver (12) connectable to the cutting head (10), the cutting head (10) and the cutting head driver (12) each having a body (14, 24) from whose end faces axially undercut projections (16, 26) project in the axial direction, the projections (16, 26) each having torque transmission faces (18, 28) designed to be complementary to one another, axially undercut, preferably axially angled, and adjacent to one another in a connected state, the projections (16, 26) being dimensioned such that in a connected state an end face (20) of the projection (16) of the cutting head (10) is axially adjacent to an end face (32) of the body (24) of the cutting head driver (12).

Description

[Technical field]

[0001] The present disclosure relates to cutting tools for machining workpieces, in particular shank tools such as milling cutters or drills. [Background technology]

[0002] The cutting tool preferably has a cutting head made of cemented carbide and a cutting head driver, preferably made of steel, which can be connected to one another in particular via a kind of bayonet lock / bayonet connection, which is axially fixed in a torque-transmitting manner.

[0003] Such multi-part cutting tools, which can be connected to one another in a bayonet 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 the seat of the cutting insert and in the inserted state its lateral surface abuts against the respective lateral surface of the cutting insert.

[0004] In this case, the cutting head and the cutting head driver can be made of different raw materials / materials of the same material group, preferably steel, or different raw materials / materials of different material groups, preferably cemented carbide and steel, in order to optimize the cutting tool according to requirements such as wear resistance, strength, cost, etc.

[0005] However, a disadvantage of the known cutting tools is that the leverage effect in the bayonet connection between the cutting head and the cutting head driver induces bending stresses which should not be too high, in particular when the cutting head and the cutting head driver are made of different materials in the area of ​​the cutting head or of the parts of the cutting tool made of cemented carbide in order to avoid damage.

[0006] Furthermore, DE 10 2013 205 889 B3, DE 10 2012 200 690 B4, EP 0 984 841 B2 and DE 697 34 937 T2 each disclose cutting tools consisting of a cutting head driver and a cutting head, which can be connected to one another via coupling parts on the cutting head side and on the cutting head driver side, respectively, where in the connected state the coupling parts engage at their end faces in recesses of the cutting head or the cutting head driver, i.e. recesses recessed relative to the end faces of the coupling parts, and face each other with complementary torque transmission surfaces for torque transmission / stopping surfaces and fastening / clamping surfaces for centering, fastening and / or clamping.

[0007] In the cutting tools known from DE 10 2013 205 889 B3 or DE 10 2012 200 690 B4, the coupling on the cutting head side is formed by a coupling pin which is diametrically continuous but does not extend outside the tool radius, and the coupling on the cutting head driver side is formed by diametrically opposed, spaced apart / separate, substantially annular in cross section, webs / projections. In the connected state, the coupling on the cutting head driver side surrounds the coupling on the cutting head side radially outward. The coupling pin on the cutting head has an approximately rectangular basic shape, with longitudinal and transverse parts transitioning into one another via transitions designed as rounded corners, the longitudinal parts forming the torque transmission / stopping surfaces and the transverse parts forming the fastening / clamping surfaces. For the axial fixation, the longitudinal and / or transverse parts are axially undercut, for example in the form of a dovetail connection. In the connected state, the coupling portion on the cutting head driver side is axially adjacent to the recess in the cutting head, and the coupling portion on the cutting head side is axially spaced from the recess in the cutting head driver.

[0008] In the cutting tool known from EP 0 984 841 B2, the coupling on the cutting head side is formed by a diametrically continuous web on the cutting head and the coupling on the cutting head driver side is formed by diametrically opposed spaced apart / individual projections. The torque transmission surfaces are arranged axially and extend substantially radially. The fastening surfaces extend circumferentially and concentrically with the axis of rotation. In the connected state, the coupling on the cutting head driver side is axially adjacent to the recess of the cutting head and the coupling on the cutting head side is axially spaced from the recess of the cutting head driver.

[0009] In the cutting tool known from DE 697 34 937 T2, the coupling on the cutting head side is formed by a coupling pin which extends diametrically continuous to the outer tool radius, and the coupling on the cutting head driver side is formed by diametrically opposed, spaced apart / individual, substantially annular cross-section webs / projections. The fastening surfaces extend circumferentially concentrically with the rotation axis and are positioned axially for axial fixing, in particular radially inward and longitudinally rearward, so that a dovetail-like cross-section is formed in the region of the fastening surfaces. The torque transmission surfaces extend radially and are arranged parallel to the rotation axis, i.e. not axially. In the connected state, the coupling on the cutting head side is axially adjacent to the recess of the cutting head driver, and the coupling on the cutting head driver side is axially spaced from the recess of the cutting head. Summary of the Invention [Problem to be solved by the invention]

[0010] However, the disadvantage of such rotary tools is that they have weak points in terms of material breakage and are not particularly suitable for transmitting high torques. Moreover, the shape of the coupling pin or the outer dovetail shape is complicated to manufacture, for example by subsequent milling.

[0011] It is therefore an object of the present disclosure to provide a multi-component cutting tool that avoids the aforementioned drawbacks of known cutting tools and is able to withstand large forces without accepting the risk of damage or premature wear of the individual components. [Means for solving the problem]

[0012] The problem of the disclosure is solved by a cutting tool having the features of claim 1. Advantageous further embodiments are the subject matter of the dependent claims.

[0013] The cutting head and the cutting head driver each have a body from whose end face an axially undercut protrusion projects in the axial direction. That is, the protrusion of the cutting head projects in the axial direction from the (axial) end face of the body of the cutting head towards the cutting head driver. Here, the protrusion of the cutting head is undercut in particular in the axial direction away from the cutting head driver. This also means that the protrusion of the cutting head driver projects in the axial direction from the (axial) end face of the body of the cutting head driver towards the cutting head. Here, the protrusion of the cutting head driver is undercut in particular in the axial direction away from the cutting head. In other words, the cutting head and the cutting head driver each have mutually facing stepped end faces, the axially outer (or outermost) part of the end face is formed by the end face of the corresponding protrusion, and the axially recessed / inner part of the end face is formed by the end face of the corresponding body. Here, the protrusions each undercut the end face of the corresponding body in axially opposite directions.

[0014] By rotating the cutting head against the cutting direction of the cutting tool, the protrusions of the cutting head and the protrusions of the cutting head driver can be matingly connected / mattingly engaged with each other. Also, by rotating the cutting head in the cutting direction, the protrusions of the cutting head and the protrusions of the cutting head driver can be released / disengaged from the mating engagement. That is to say, the bayonet lock / bayonet connection is formed by the axially undercut protrusions in such a way that the cutting head and the cutting head driver can be connected to each other by twisting towards each other and can be disengaged from each other by twisting towards each other in the opposite direction. The protrusions in particular serve as couplings for connecting the cutting head and the cutting head driver.

[0015] The protrusions of the cutting head and the protrusions of the cutting head driver each have complementary torque transmission surfaces, axially undercut, preferably axially angled, which face each other, in particular in a plane, in the connected state of the cutting head and the cutting head driver. This means that the protrusions of the cutting head are wedge-shaped or have wedge-shaped portions forming the torque transmission / undercut surfaces of the protrusions. The torque transmission surfaces of the protrusions of the cutting head can preferably be essentially aligned perpendicular to the radial direction, i.e. the tangential direction, of the cutting tool, so that the torque to be transmitted from the cutting head driver to the cutting head can be absorbed in a telescopic manner. This also means that the protrusions of the cutting head driver are wedge-shaped or have wedge-shaped portions forming the torque transmission / undercut surfaces of the protrusions. The torque transmission surfaces of the protrusions of the cutting head driver can preferably be essentially aligned perpendicular to the radial direction, i.e. the tangential direction, of the cutting tool, so that the torque to be transmitted from the cutting head driver to the cutting head can be telescopically transmitted. In other words, the cutting head and cutting head driver are essentially Z-shaped / stepped at their (bayonet) connection areas.

[0016] In the cutting tool, the cutting head and the protrusion of the cutting head driver of the cutting tool are dimensioned such that, in the connected state, the end face of the protrusion of the cutting head is axially adjacent to the end face of the body of the cutting head driver. This means that the protrusion is dimensioned or its dimensional tolerances are selected such that when the torque transmission faces of the protrusion are adjacent to each other (and transmit torque), i.e., in the connected state of the cutting head and the cutting head driver, the protrusion of the cutting head is supported in axial tension against the body of the cutting head driver. In other words, in the connected state, the wedge-shaped protrusion of the cutting head is received in axial and tangential abutment in the wedge-shaped cavity formed by the protrusion and the body of the cutting head driver, or the wedge-shaped protrusion of the cutting head is supported by both wedge sides in the wedge-shaped cavity of the cutting head driver.

[0017] This has the advantage that the axial support of the cutting head on the cutting head driver results in a forced tangential guidance of the cutting head, preferably made of cemented carbide, which reduces bending stresses, particularly in the region of the transition between the projection of the cutting head and the body. Furthermore, the axial contact between the end face of the body of the cutting head driver and the end face of the projection of the cutting head forms a wedge support, which acts axially towards the cutting head driver and thus generates a friction force against the load, which also reduces bending stresses, particularly in the region of the transition between the projection of the cutting head and the body.

[0018] Thus, compared to the cutting tools of DE 10 2013 205 889 B3, DE 10 2012 200 690 B4 and EP 0 984 841 B2 discussed at the outset, there is the advantage that precisely the coupling on the cutting head driver side is not axially adjacent to the recess of the cutting head (and the coupling on the cutting head side is not axially spaced from the recess of the cutting head driver), but rather the coupling on the cutting head side is axially adjacent to the recess of the cutting head driver, so that according to the present disclosure any widening due to the axial angulation of the torque transmission surfaces or the wedge-shaped shape of the projections takes place (exclusively or mainly) in the region of the wedge-shaped cavity of the cutting head driver and not in the region of the wedge-shaped cavity of the cutting head.

[0019] Furthermore, there is a fundamental difference with respect to the cutting tool of DE 697 34 937 T2 mentioned at the outset in that there, in particular the dovetail-shaped axial undercuts are formed only on the fastening surfaces of the connecting pin, which serve exclusively for fastening, in particular for axial fixing and centering. These fastening surfaces are not torque transmission surfaces according to the present disclosure, since they are designed concentrically to the axis of rotation and therefore cannot transmit torque. In the cutting tool of DE 697 34 937 T2, the stop surfaces which serve as torque transmission surfaces are formed parallel to the axis of rotation, so that the essence or problem of the present disclosure, i.e. that the axially undercut torque transmission surfaces are transformed by the cutting forces occurring during machining of the workpiece into axial forces and thus widening, does not exist in DE 697 34 937 T2.

[0020] According to a preferred embodiment, the end face of the projection of the cutting head driver can be spaced from the end face of the body of the cutting head with axial play in the connected state. In other words, in order to avoid double fitting, only one end face of the stepped end face of the cutting head contacts the cutting head driver. As a result, the wedge-shaped part of the cutting head driver does not widen the wedge-shaped cavity of the cutting head, since it only contacts the wedge-shaped cavity of the cutting head with one wedge side, more precisely the torque transmission surface. This reduces the load of the transition between the torque transmission surface and the non-contact end face, which has a beneficial effect on the life of the cutting head and thus of the cutting tool.

[0021] Generally, according to the invention, in the case of a bayonet-type connection between two parts, preferably made of different materials, e.g. steel and cemented carbide, alternatively made of materials of the same material group, e.g. steel, having a Z-angle shape or two mutually engaging wedges, the load resulting from the wedge force is transferred to the part which is in comparison more flexible, softer or less brittle.

[0022] According to a preferred embodiment, the projection of the cutting head can be axially longer than the projection of the cutting head driver, which ensures in a particularly simple way that, if the torque transmission surfaces are designed to complement each other, the (slight) difference in the axial extension of the two projections ensures that the cutting head adjoins the body of the cutting head driver at the projection, while the (shorter) projection of the cutting head driver remains at a distance from the body of the cutting head. In this way, the contact surfaces, and thus the force transmission surfaces, can be clearly defined by design.

[0023] According to a preferred embodiment, the protrusions can have surfaces or shapes that interlock with each other when the cutting head and the cutting head driver are connected. For example, the wedge-shaped protrusions of the cutting head and the wedge-shaped recesses of the cutting head driver can have surfaces or shapes that telescopically interact with each other or interlock with each other or achieve a locking effect in the rotational direction when the two parts are rotationally connected. This prevents unintentional release. The wedge-shaped parts are made of a more rigid material and the wedge-shaped recesses are made of a more flexible material, so that the former can flexibly expand the latter for the interlocking of the surfaces or shapes.

[0024] According to a preferred embodiment, the cutting head and the cutting head driver can have a complementary shape, so that the cross section of the cutting head driver and the cross section of the cutting head essentially correspond at their interface and / or the shape of the cutting head driver, in particular the spiral formation of the chip flute and / or the peripheral cutting edge, is continued by the cutting head, i.e. the cutting head and the cutting head driver preferably have a complementary shape, so that the cross section of the cutting head after the stepped interface of the two parts essentially corresponds to the cross section of the cutting head driver before the stepped interface, or the shape of the cutting head after the connection point (including the spiral, the chip flute and the peripheral cutting edge) continues the shape of the cutting head driver (including the spiral, the chip flute and the peripheral cutting edge).

[0025] According to a preferred embodiment, the torque transmission surfaces can be angled axially such that the cutting head is axially pressed towards the cutting head driver by the cutting forces acting during machining of the workpiece. This means that due to the interaction between the axially angled torque transmission surfaces, the cutting head is attracted more strongly to the cutting head driver as the cutting forces increase during machining of the workpiece. This ensures a tight connection between the cutting head and the cutting head driver, especially at high cutting speeds.

[0026] The torque transmission surface of the cutting tool is preferably designed in such a way that the tangential forces generated by the cutting forces acting during machining of the workpiece are converted into axial forces such that the cutting head is pushed axially into contact with the cutting head driver. This has the effect that as the cutting forces increase, i.e. as the rotational speed increases, the tangential forces and therefore the axial forces also increase, resulting in a stronger connection between the cutting head and the cutting head driver. As a result, particularly high cutting forces can be transmitted despite the multi-part design of the cutting tool.

[0027] According to a preferred embodiment, the torque transmission surface can be axially set at an axial angle of attack of preferably 2° to 15°, more preferably 2° to 10°, particularly preferably 2° to 5°, and particularly preferably 3°. Such angles of attack have proven sufficient to create a strong connection that is also easy to install. Furthermore, by selecting an axial angle of attack, the forces acting on the projections can be kept as low as possible.

[0028] Preferably, the torque transmission surfaces of the cutting head and the cutting head driver can have the same axial angle of attack, meaning that the torque transmission surfaces are in plane contact with each other so that the cutting head and the cutting head driver do not get stuck in the area of ​​the torque transmission surfaces.

[0029] According to a preferred embodiment, the axial angle of attack can be constant over the entire circumferential extent / circumferential contour of the torque transmission surface, i.e. over the entire circumferential range. This means that the circumferential surface of the projection has the same axial angle of attack at least in the region where the cutting head and the cutting head driver are in contact in the connected state, preferably over the entire circumferential extent, i.e. also in the non-contact region. Preferably, the range of the torque transmission surface can be seamless in the circumferential direction, i.e. without breaks. This allows the entire circumferential surface to be finished with one workpiece clamping, i.e. without re-clamping, in particular with only one type of machining.

[0030] According to a preferred embodiment, the axial angle of attack can be constant over the entire axial extent, i.e. over the entire axial range, of the torque transmission surface. Preferably, the axial range of the torque transmission surface can be seamless, i.e. without breaks. This preferably means that the axial angle of attack does not change from the end face of the protrusion (possibly minus the end area on the end face side where a chamfer or the like is formed) to the end face of the body.

[0031] In particular, the torque transmission surface can be formed by a continuous inclined surface, i.e. in particular a surface without depressions or steps / heights. This can be achieved, for example, by grinding. A continuous design has the advantage that edges and therefore stress peaks are avoided.

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

[0033] In particular, the Z-shape may result from the fact that the cutting head and the cutting head driver 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 the torque transmission surfaces connecting each of the pair of end faces to each other each extend substantially continuously, i.e. obliquely to the axial direction, between each of the end faces of the pair of end faces, except for the transition region between the end faces and the torque transmission surfaces.

[0034] According to a preferred embodiment, the axially outer end face of the pair of end faces can transition to the torque transmission face via a chamfer. This means that the essentially wedge-shaped projection is rounded or linearly chamfered at its end face / wedge angle. In other words, instead of the tip of the wedge-shaped projection (which arises from the intersection of the axially outer end face and the torque transmission face), a chamfered surface is present. This not only simplifies the insertion of the projection, but also prevents forces from being applied deep into the wedge-shaped cavity, which would otherwise cause local notch stress peaks.

[0035] According to a preferred embodiment, the axially inner end face of the pair of end faces can transition to the torque transmission face via a circular section. This means that the essentially wedge-shaped cavity is rounded at its wedge corners. In other words, instead of a wedge-shaped cavity (resulting from the intersection of the axially inner end face and the torque transmission face), there is a rounded face. This reduces the stresses in the material and makes the manufacturing of the shape possible (for example by grinding).

[0036] According to a preferred embodiment, the torque transmission surface can be designed as a continuous inclined surface between the chamfer and the rounded portion, i.e., the torque transmission surface is designed as a flat surface, i.e., without depressions, steps or elevations, except for the respective transition areas to the pair of end faces, which ensures torque transmission and simplifies the production of the torque transmission surface.

[0037] According to a preferred embodiment, the torque transmission surfaces between the chamfer and the rounded portion can be continuously adjacent to one another, which means that the wedge-shaped projections or torque transmission surfaces are in planar contact with one another over their entire extent, apart from the respective transition areas to the pair of end faces, which allows a particularly high torque to be transmitted.

[0038] Furthermore, the axial end faces of the opposing cutting head and cutting head driver may be axially stepped by respective protrusions, resulting in a Z-shaped profile.

[0039] Such a Z-shaped profile has proven to be particularly advantageous in terms of functionality and manufacturability.

[0040] 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 shank-side cooling channel section formed in the cutting head driver. This means that the cooling channel for supplying the cutting edge of the cutting tool with cooling lubricant runs through the entire cutting tool and is supplied to the shank-side boundary surface in the region of the cutting head driver, for example in the form of a cooling lubricant inlet, and is discharged again to the workpiece-side boundary surface in the region of the cutting head, for example in the form of a cooling lubricant outlet. In this way, the cutting edge can be sufficiently cooled during machining of the workpiece.

[0041] According to a further development of the preferred embodiment, the shank-side cooling pipe section in the region of the end face of the body of the cutting head driver can be transitioned to the workpiece-side cooling pipe section in the region of the end face of the protrusion of the cutting head. This means that the transfer of the cooling lubricant takes place in the axial contact area between the cutting head and the cutting head driver in order to allow a lateral sealed transfer of the cooling lubricant. Due to the design of the torque transmission surface, the end face of the protrusion of the cutting head is pressed by leverage against the end face of the body of the cutting head driver, so that a leak-proof sealed transition of the cooling lubricant can be formed between the cutting head and the cutting head driver, preferably without the use of separate sealing parts or sealants. As a result, an efficient supply of the cooling lubricant is ensured.

[0042] According to a further development of the preferred embodiment, the cutting head can have at least one leading cutting edge and a flank adjacent to the leading cutting edge, and the cooling channel leaves the cutting tool in the region of the flank. In other words, the cooling lubricant leaves the end face of the cutting tool facing the workpiece. Preferably, each leading cutting edge can be provided with an individual cooling channel in order to be able to supply the cooling lubricant to the high-load areas of the cutting tool in a targeted manner.

[0043] According to a preferred embodiment, the cutting tool can have at least one peripheral cutting edge extending in a spiral manner. Preferably, the peripheral cutting edge can start from the edge angle of at least one front cutting edge. In particular, the number of peripheral cutting edges can correspond to the number of front cutting edges.

[0044] According to a further development of the preferred embodiment, the at least one peripheral cutting edge can be formed in the cutting head and the cutting head driver. This means that the peripheral cutting edge is not formed only by the cutting head or the cutting head driver, but is axially continuous over the extent of the cutting head and the cutting head driver. The helix of the at least one peripheral cutting edge is therefore not interrupted or changed by the multi-part design with the cutting head and the cutting head driver. The peripheral cutting edge is thus partially formed in the axial direction by the cutting head and partially formed in the axial direction by the cutting head driver. Similarly, the chip discharge groove adjacent to the at least one peripheral cutting edge can also be formed axially continuously over the extent of the cutting head and the cutting head driver, i.e. partially axially by the cutting head and partially axially by the cutting head driver.

[0045] According to a further development of the preferred embodiment, the cutting tool can have a number of peripheral cutting edges, preferably two peripheral cutting edges. According to a further development of the preferred embodiment, the cutting head and the cutting head driver can each have a number of protrusions corresponding to the number of peripheral cutting edges. Thus, in the case of two peripheral cutting edges, an angular range of 180° is formed in which two protrusions and a free space large enough to allow the cutting head and the cutting head driver to twist towards each other are arranged. This has the advantage that protrusions can be formed that are large enough to transmit forces while ensuring that the protrusions can be twisted.

[0046] According to a preferred embodiment, the cutting head driver can have two diametrically opposed protrusions, which are formed by a web that extends over the entire diameter of the cutting tool. This means that the two protrusions of the cutting head driver are connected to each other via a central part. In particular, the web can have a central part and a protrusion part that extends radially outward from it, for example formed in the shape of a wing.

[0047] According to a preferred embodiment, the cutting head can have two radially opposed protrusions designed as radially spaced / separate / separate pins, which means that a central recess is formed between the two protrusions of the cutting head, in which the central part of the cutting head driver can engage.

[0048] According to a preferred embodiment, the cutting head can have two diametrically opposed projections, which are formed by a web that runs over the entire diameter of the cutting tool. This means that the two projections of the cutting head are connected to each other via a central part. In particular, the web can have a central part and projections formed, for example, wing-like, that extend radially outward from it, for example in the shape of a fan.

[0049] According to a preferred embodiment, the cutting head driver can have two radially opposed protrusions designed as radially spaced / separate / individual pins, which means that between the two protrusions of the cutting head driver a central recess is formed, in which the central part of the cutting head can engage.

[0050] According to a preferred embodiment, the axial contact surface between the cutting head and the cutting head driver can have a central portion and wings extending radially outward from the central portion, for example in the form of a fan. That is to say, the axial contact surface is preferably formed on the axis of rotation, in particular on a web extending over the entire diameter of the cutting tool. This provides a sufficient axial contact surface. In particular, the transition of the cooling line between the cutting head and the cutting head driver is also arranged on the axial contact surface.

[0051] According to a further development of the preferred embodiment, the wings can initially taper from the center, in particular on both circumferential sides, and then widen again, in particular on both circumferential sides. This means that the wings each have a waisted, i.e. essentially hourglass, shape. In particular, the wings can have a substantially concave lateral ridge on at least one side, which lateral ridge is arranged on the contact surface for the cutting head or the cutting head driver. Preferably, the wings can have a substantially concave lateral ridge on both sides, where one of the concave lateral ridges is part of the chip groove and the other of the concave lateral ridge is part of the contact surface for the cutting head or the cutting head driver. Such a concave shape allows a particularly favorable shape in terms of torque transmission and centering to be realized in the contact in the circumferential / cutting direction between the cutting head and the cutting head driver.

[0052] According to a further development of the preferred embodiment, the axial contact surface can be essentially configured as doubly waisted, which makes it possible to realize a geometry that is particularly favorable in terms of torque transmission and centering.

[0053] According to a preferred embodiment, the circumferential contact surface between the cutting head and the cutting head driver can be curved in the radial direction. This means that the contact surfaces where the cutting head and the cutting head driver meet each other in the circumferential / cutting direction are not linearly or exactly or essentially aligned in the radial direction. In particular, the circumferential contact surface formed on the cutting head or on the continuous web is essentially concavely curved, and the complementary circumferential contact surface formed on the cutting head driver or on the individual pins is essentially convexly curved. With such a design, the circumferential contact surface can be used both for torque transmission between the cutting head and the cutting head driver and for centering the cutting head and the cutting head driver. At the same time, stress peaks in the material are avoided.

[0054] According to a further development of the preferred embodiment, the circumferential contact surface can have a radially inner part and a radially outer part (opposite the radially inner part) which function as torque transmission surfaces. That is, the radially inner part extends in an area spaced radially inward with respect to the tool diameter, and the radially outer part extends in an area spaced radially outward with respect to the rotation axis. In this way, a particularly long radially extending surface can be utilized for torque transmission. The radially inner part and the radially outer part of the circumferential contact surface can be used mainly or exclusively / only for torque transmission. Alternatively, there may be other surfaces that contribute to the torque transmission between the cutting head and the cutting head driver.

[0055] According to a further development of the preferred embodiment, the radially outer part can extend up to the tool diameter (viewed in the radial direction). The radially outward arrangement of the radially outer part can ensure the transmission of particularly high torques.

[0056] According to a further development of the preferred embodiment, the radially inner part can extend up to the axis of rotation (viewed radially), so that the radially inner area can also be used for torque transmission.

[0057] According to a further development of the preferred embodiment, the radially inner part of the circumferential contact surface formed on the cutting head or on the continuous web can be curved substantially convexly in the radial direction, and the complementary radially inner part of the circumferential contact surface formed on the cutting head driver or on the individual pin can be curved substantially concavely in the radial direction. In particular, the radially inner part can be arranged in the region of the center of the axial contact surface.

[0058] According to a further development of the preferred embodiment, the radially outer part of the circumferential contact surface formed on the cutting head or on the continuous web can be curved substantially concavely in the radial direction, and the complementary radially outer part of the circumferential contact surface formed on the cutting head driver or on the individual pin can be curved substantially convexly in the radial direction. In particular, the radially outer part can be arranged in the region of the wings of the axial contact surface, in particular in the region of the widening of the wings.

[0059] According to a further development of the preferred embodiment, the radially inner part and the radially outer part can each have a radius of curvature that is eccentric to the axis of rotation, i.e. not concentric with the axis of rotation, so that the torque acting during machining of the workpiece can be transmitted reliably between the cutting head and the cutting head driver.

[0060] According to a further development of the preferred embodiment, the circumferential contact surface can have a clamping portion located radially between the radially inner and the radially outer portions, which clamping portion functions primarily or exclusively as a clamping surface, i.e. the radially inner and the radially outer portions are radially spaced apart from one another, whereby the clamping portion located therebetween can be designed to make little or no contribution to the torque transmission.

[0061] According to a further development of the preferred embodiment, the torque transmission surface formed by the radially inner and outer portions can extend in the axial direction over at most half the axial extent of the projection, which means that the chamfers and the rounded portions, through which the torque transmission surface transitions to the end face of the projection or body, occupy a major part of the axial extent of the respective projection.

[0062] Preferably, the projection of the cutting head can have an essentially elliptical cross section. In particular, the projection of the cutting head can have two essentially semicircular or C-shaped circumferential parts facing each other in the circumferential direction and two essentially straight circumferential parts facing each other in the circumferential direction, where one of each semicircular or C-shaped circumferential part is connected to one of each straight circumferential part. That is, the straight circumferential parts are abuttingly connected to the semicircular or C-shaped circumferential parts.

[0063] In particular, the torque transmission surface of the cutting head may be formed by the (outer) circumferential surface (alternatively the (inner) circumferential surface) of the protrusion of the cutting head. Similarly, the torque transmission surface of the cutting head driver may be formed by the (inner) circumferential surface (alternatively the (outer) circumferential surface) of the protrusion of the cutting head driver. The torque transmission surfaces of the cutting head and the cutting head driver are in particular circumferential surfaces which come into contact with each other in the connected state of the cutting head and the cutting head driver.

[0064] According to a preferred embodiment, the torque transmission surface can be formed by curvatures with different radii. This means that an essentially semicircular or C-shaped circumferential surface is on the other hand formed by individual curvatures, the curvature of which changes over the curved extent of the circumference. Preferably, the curvatures can be formed to interpenetrate over the circumferential contour, i.e. over the circumferential / circumferential extent. This means that the transition between the different radii is made without breaks or visible ridges / seams.

[0065] According to a preferred embodiment, the torque transmission surface can have at least a first curvature and a second curvature located in the cutting direction, in particular directly behind it, where the second curvature has a smaller radius than the first curvature, thereby guiding or facilitating the insertion of the cutting head into the cutting head driver and / or providing a soft stop. According to an alternative embodiment, the first curvature can have a smaller radius than the second curvature.

[0066] According to a further development of the preferred embodiment, the radius of the first curvature and the radius of the second curvature can have different centre points, which has the advantage that a seamless transition between the two curvatures can be achieved.

[0067] According to a further development of the preferred embodiment, the center point of the second curved part can be located in the cutting direction, preferably by a small amount, in particular by 0.1 mm to 0.4 mm, further back than the center point of the first curved part. According to an alternative further development of the preferred embodiment, the center point of the second curved part can be located in the cutting direction, preferably by a small amount, in particular by 0.1 mm to 0.4 mm, further forward than the center point of the first curved part. The small displacement of the center point can create a ridgeless transition between the two curved parts.

[0068] According to a preferred embodiment, the torque transmission surface may have a third curvature located in the cutting direction, in particular directly behind the second curvature, the radius of which is significantly larger than the radius of the first and / or second curvature. For example, the third curvature may be substantially straight. This facilitates the insertion of the cutting head into the cutting head driver.

[0069] According to a preferred embodiment, the circumferential surface of the cutting head may be substantially convexly curved in the region of its circumferential contour which contacts the cutting head driver in the connected state, and substantially concavely curved in the region of its circumferential contour which does not contact the cutting head driver in the connected state.

[0070] According to a preferred embodiment, the cutting head can have a centering projection, preferably circular in cross section and / or preferably arranged concentrically with the axis of rotation of the cutting tool, which projection protrudes axially from the end face of the projection of the cutting head, so that the cutting head is guided during axial insertion into the cutting head driver and at the same time the rotatability for engaging the bayonet lock is maintained.

[0071] According to a further development of the preferred embodiment, the torque transmission surface of the cutting head can have an axial extent that is substantially twice as large as the centering projection, which ensures sufficient centering when inserting the cutting head. [Brief description of the drawings]

[0072] [Figure 1] FIG. 1 is a perspective view showing a cross section of a cutting tool having a cutting head and a cutting head driver according to a first embodiment of the present disclosure. [Diagram 2] FIG. 2 is a perspective view of the cutting tool with the cutting head and cutting head driver not connected. [Diagram 3] FIG. 3 is a side view of the cutting tool in an unconnected state. [Figure 4] FIG. 4 is a side view of the cutting tool with the cutting head and the cutting head driver connected. [Diagram 5] FIG. 5 is a side view of the cutting tool in a connected condition rotated about the longitudinal axis of the cutting tool relative to FIG. [Figure 6] FIG. 6 is an enlarged view of a detail of FIG. [Figure 7] FIG. 7 is a bottom view of the cutting head. [Figure 8] FIG. 8 is a top view of the cutting head driver. [Figure 9] FIG. 9 is a perspective view showing a cross section of a cutting tool according to a second embodiment of the present disclosure. [Figure 10]FIG. 10 is a perspective view of the cutting tool with the cutting head and cutting head driver disconnected. [Figure 11] FIG. 11 is a side view of the cutting tool in an unconnected state. [Figure 12] FIG. 12 is a side view of the cutting tool with the cutting head and the cutting head driver connected. [Figure 12A] FIG. 12A is a side view of the cutting tool with the cutting head and cutting head driver connected. [Figure 13] FIG. 13 is a side view of the cutting tool in a connected state, rotated about the longitudinal axis of the cutting tool relative to FIGS. 12 and 12A. [Figure 14] FIG. 14 is an enlarged view of a detail of FIG. 12A. [Figure 15] FIG. 15 is a bottom view of the cutting head. [Figure 16] FIG. 16 is a top view of the cutting head driver. [Figure 17] FIG. 17 is a perspective view of the cutting head and cutting head driver. [Figure 18] FIG. 18 is a perspective view of the cutting head and cutting head driver. [Figure 19] FIG. 19 is a perspective view of a cutting head according to a third embodiment of the present disclosure. [Figure 20] FIG. 20 is a perspective view of a cutting head according to a third embodiment of the present disclosure. [Figure 21] FIG. 21 is a bottom view of the cutting head. [Figure 22] FIG. 22 is a side view of the cutting head. [Diagram 23] FIG. 23 is a side view of the cutting head. [Figure 24] FIG. 24 is a perspective view of a cutting head driver according to a second embodiment of the present disclosure. [Diagram 25] FIG. 25 is a top view of the cutting head driver. [Figure 26] FIG. 26 is a vertical cross-sectional view of the cutting head driver. [Figure 27] FIG. 27 is an explanatory diagram showing the principle of a cutting tool according to the prior art. [Figure 28] FIG. 28 is an explanatory diagram showing the principle of a cutting tool according to the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0073] 1 to 8 show different views of a cutting tool 2 according to a first embodiment of the present disclosure, or parts and individual components thereof. The cutting tool 2 is used for cutting workpieces. The cutting tool 2 is designed as a shank tool, such as a milling cutter or a drill.

[0074] The cutting tool 2 has at least one pre-cutting edge 4, preferably a plurality, in the illustrated embodiment two, of pre-cutting edges 4, which are formed on one end face of the cutting tool 2. The pre-cutting edges 4 each adjoin one (main) clearance face 6.

[0075] The cutting tool 2 has at least one peripheral cutting edge, and preferably a plurality, in the illustrated embodiment two peripheral cutting edges 8. The peripheral cutting edges 8 extend helically along the outer surface of the cutting tool 2. In particular, each peripheral cutting edge 8 can extend from a corner of one of the cutting edges 4.

[0076] The cutting tool 2 is made up of several parts and comprises a cutting head 10 (cutting attachment) and a cutting head driver 12 (carrier). The cutting head 10 and the cutting head driver 12 are connected to each other in the axial direction of the cutting tool 2, the cutting head 10 forming the workpiece-side part and the cutting head driver 12 forming the shank-side part. The cutting head 10 and the cutting head driver 12 can be (detachably) connected to each other via a kind of bayonet lock / bayonet connection. In the connected state, the cutting head 10 and the cutting head driver 12 are connected / attached to each other in a torque-transmitting and axially fixed manner. The cutting head 10 and the cutting head driver 12 can be mated to each other by twisting them in a first rotational direction, for example by rotating the cutting head 10 against the cutting direction of the cutting tool 2. The cutting head 10 and the cutting head driver 12 can be separated from each other by twisting them relative to each other in a second rotational direction (opposite the first rotational direction), for example by rotating the cutting head 10 in the cutting direction of the cutting tool 2.

[0077] The leading cutting edge 4 of the cutting tool 2 is formed on the cutting head 10. The peripheral cutting edge 8 of the cutting tool 2 is formed (partially) on the cutting head 10 and also (partially) on the cutting head driver 12. The peripheral cutting edge 8 therefore runs axially through, i.e. through the connection of the cutting head 10 with the cutting head driver 12. As a result, a bayonet connection, via which the cutting head 10 and the cutting head driver 12 can be connected, is arranged in the cutting part of the cutting tool 2.

[0078] The cutting head 10 and the cutting head driver 12 can be made / designed / manufactured from different sources / materials. Preferably, the cutting head 10 is made of cemented carbide. Preferably, the cutting head driver 12 is made of steel.

[0079] 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 raw material / material group, for example both steel, as long as it is ensured that in a bayonet-like connection between a part of the cutting head 10 and a part of the cutting head driver 12 having different material properties and a Z-angle shape or two mutually engaging wedge shapes, the load resulting from the wedge force is transferred to the part which is in comparison more flexible, softer or less brittle.

[0080] The cutting head 10 has a body 14, from whose end face a projection 16 projects in the axial direction. The projection 16 projects in the direction of the cutting head driver 12 and is used for bayonet-type mounting on the cutting head driver 12. The projection 16 is axially undercut and has a torque transmission surface 18, which is preferably designed to be set in the axial direction. The torque transmission surface 18 is preferably formed substantially radially, i.e. perpendicular to the tangential direction, so as to be able to transmit torque. By means of the projection 16, the end face of the cutting head 10 (facing towards the cutting head driver 12 / away from the workpiece) is stepped in the axial direction, so that a substantially Z-shaped profile is formed. The Z-shaped profile is formed by the axial end face 20 of the projection 16, the axially arranged torque transmission surface 18 of the projection 16 and the axial end face 22 of the body 14. Here, the axial end face 20 of the projection 16 transitions into the torque transmission surface 18 via a chamfer 19. The torque transmission surface 18 transitions into an axial end face 22 of the body 14 via a circular portion 21 .

[0081] The cutting head 10 has a number of protrusions 16 corresponding to the number of peripheral cutting edges 8. That is, in the illustrated embodiment, the cutting head 10 has two protrusions 16, which are arranged diametrically opposite one another. The protrusions 16 of the cutting head 10 are radially spaced apart / discretely arranged, that is, separated from one another by a central recess / are not continuously connected to one another across the diameter of the cutting tool.

[0082] Alternatively, the projections 16 may be formed by a web that extends continuously across the diameter of the cutting tool (if the cutting head driver 12 is designed accordingly).

[0083] The cutting head driver 12 has a body 24, from whose end face a projection 26 projects in the axial direction. The projection 26 projects in the direction of the cutting head 10 and is used for bayonet-type attachment to the cutting head 10. The projection 26 is axially undercut and has a torque transmission face 28, which is preferably designed to be set in the axial direction. The torque transmission face 28 is preferably formed substantially radially, i.e. perpendicular to the tangential direction, so as to be able to transmit torque. By means of the projection 26, the end face of the cutting head driver 12 (facing towards the cutting head 10 / away from the shank) is stepped in the axial direction, so that a substantially Z-shaped profile is formed. The Z-shaped profile is formed by the axial end face 30 of the projection 26, the axially arranged torque transmission face 28 of the projection 26 and the axial end face 32 of the body 24. Here, the axial end face 30 of the projection 26 transitions into the torque transmission face 28 via a chamfer 29. The torque transmission surface 28 transitions to an axial end face 32 of the body 24 via a circular portion 31 .

[0084] The cutting head driver 12 has a number of protrusions 26 corresponding to the number of peripheral cutting edges 8. That is, in the illustrated embodiment, the cutting head driver 12 has two protrusions 26. The two protrusions 26 are arranged diametrically opposite each other. The two protrusions 26 are formed by a web that extends over the entire diameter of the cutting tool. That is, the protrusions 26 are connected to each other continuously over the diameter of the cutting tool.

[0085] Alternatively, the protrusions 26 (if the cutting head 10 is designed accordingly) may be radially spaced / discretely disposed.

[0086] The torque transmission surfaces 18 of the cutting head 10 and the torque transmission surfaces 28 of the cutting head driver 12 are designed to be complementary to each other (in a plane) in the connected state. Due to the leaning 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 / pinched against each other in the connected state.

[0087] In accordance with the present disclosure, the protrusions 16, 26 of the cutting head 10 and the cutting head driver 12 are dimensioned such that, in a connected state, the end face 20 of the protrusion 16 of the cutting head 10 is axially adjacent the end face 32 of the body 24 of the cutting head driver 12. In this manner, the protrusion 16 of the cutting head 10 is supported in tension against the body 24 of the cutting head driver 12.

[0088] In addition, the end surface 30 of the projection 26 of the cutting head driver 12 is separated from the end surface 22 of the body 14 of the cutting head 10 with axial play when connected. Therefore, the body 14 of the cutting head 10 is not supported by the projection 26 of the cutting head driver 12.

[0089] Preferably, the protrusions 16 of the cutting head 10 may be (slightly) longer axially than the protrusions 26 of the cutting head driver 12 .

[0090] Furthermore, the cutting tool 2 comprises at least one cooling channel, preferably several cooling channels, in the embodiment shown two cooling channels 34. The cooling channels 34 are used to supply cooling lubricant to the stressed areas of the cutting tool 2, in particular to the cutting edges such as the leading edge 4. In particular, the cooling channels 34 may be arranged to exit the cutting tool 2 in the area of ​​the flank 6.

[0091] The cooling pipes 34 are each formed by a workpiece-side cooling pipe section 36 formed in the cutting head 10 and a shank-side cooling pipe section 38 formed in the cutting head driver 12. Preferably, the cooling lubricant can be supplied centrally and distributed to the shank-side cooling pipe section 38.

[0092] The shank-side cooling pipe section 38 leads into the workpiece-side cooling pipe section 36 in the area where the cutting head driver 12 rests flush, preferably flush, against the cutting head 10. In the illustrated embodiment, the cooling pipe section 38 merges into the cooling pipe section 36 in the area of ​​the end face 32 of the body 24 of the cutting head driver 12 or in the area of ​​the end face 20 of the projection 16 of the cutting head 10.

[0093] The cutting tool 2 has a shank portion 40, and the cutting tool 2 is fitted into a tool holder via the shank portion 40 so that it can be rotationally driven. The shank portion 40 is adjacent to the cutting head driver 12 on the side remote from the cutting head 10 in the axial direction.

[0094] 9 to 18 show a second embodiment of a cutting tool 2. The second embodiment has almost the same features as the first embodiment, so only the differences will be described below.

[0095] The two protrusions 16 of the cutting head 10 are formed by a web that extends over the entire diameter of the cutting tool, i.e. the protrusions 16 are continuously connected to each other over the diameter of the cutting tool. The two protrusions 26 of the cutting head driver 12 are arranged diametrically opposite each other. The protrusions 26 of the cutting head driver 12 are formed radially spaced apart / individually, i.e. they are separated from each other by a central recess / are not continuously connected to each other over the diameter of the cutting tool.

[0096] 17 and 18 are perspective views of the cutting head 10 and the cutting head driver 12, on the basis of which a particularly advantageous configuration of the projections 16, 26 will be explained below. In the perspective views, the contact surfaces at which the cutting head 10 and the cutting head driver 12 adjoin each other are shown hatched.

[0097] An axial contact surface 80 is formed on the axial end face 20 of the continuous web of the projections 16 of the cutting head 10, with a complementary surface formed on the axial end face 32 of the body 24 or in a recess between the projections 26 of the cutting head driver 12. The axial contact surface 80 has a central portion 82 and two wing portions 84 extending radially outward therefrom, for example in the shape of a fan. The wing portions 84 are formed in a waisted shape, first tapering from the central portion 82 and then widening again.

[0098] The circumferential contact surface 86 is formed on the side surface of the protrusion 16 of the cutting head 10 perpendicular to the cutting direction, and the complementary surface is formed on the side surface of the protrusion 26 of the cutting head driver 12 perpendicular 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.

[0099] The circumferential contact surface 86 has a radially inner portion 88 and a radially outer portion 90, which portions 88, 90 serve as torque transmission surfaces 18, 28. The radially inner portion 88 is spaced radially inward with respect to the tool diameter. The radially outer portion 90 is spaced radially outward with respect to the axis of rotation and is radially outward with respect to the axis of rotation. In a radial view, the radially outer portion 90 extends to the tool diameter. In a radial view, the radially inner portion 88 extends to the axis of rotation.

[0100] The radially inner portion 88 is substantially convexly curved at the circumferential contact surface 86 formed on the cutting head side and substantially concavely curved correspondingly at the circumferential contact surface 86 formed on the cutting head driver side. The radially outer portion 90 is substantially concavely curved at the circumferential contact surface 86 formed on the cutting head side and substantially convexly curved correspondingly at the circumferential contact surface 86 formed on the cutting head driver side. The radially inner portion 88 and the radially outer portion 90 each have a radius of curvature that is eccentric to the axis of rotation, i.e. not concentric with the axis of rotation.

[0101] The circumferential contact surface 86 has a clamping portion 92 located radially between a radially inner portion 88 and a radially outer portion 90, which clamping portion 92 functions primarily or exclusively as a clamping surface (and preferably has little or no function for torque transmission), i.e., the radially inner portion 88 and the radially outer portion 90 are radially spaced apart from one another.

[0102] The torque transmission surface 18, 28 formed by the radially inner portion 88 and the radially outer portion 90 extends axially over a maximum of half the axial extent of the projection 16, 26. This means that the chamfers 19, 29 and the rounded portions 21, 31 where the torque transmission surface 18, 28 transitions to the end faces 20, 22, 30, 32 of the projection 16, 26 or body 14, 24 occupy the majority of the axial extent of the respective projection 16, 26.

[0103] 19 to 26 show a third embodiment of a cutting tool 2, on the basis of which particularly advantageous configurations of the projections 16, 26 or in particular the design configurations of the torque transmission surfaces 18, 28 are explained below.

[0104] 19 to 23 show various views of the cutting head 10. The cutting head 10 has a body 14 from whose end face an axially undercut protrusion 16 projects in the axial direction. The protrusion 16 of the cutting head 10 has an essentially elliptical cross section. In particular, the protrusion 16 has two opposing first circumferential portions 42 and two opposing second circumferential portions 44, which are interdigitated with each other. The first circumferential portion 42 is convexly curved and has a substantially semicircular or C-shaped profile. The second circumferential portion 44 has a substantially straight or very slightly concave profile.

[0105] Each of the first circumferential portions 42 is made up of a number of curved portions 46, 48 having different radii. In particular, each of the first circumferential portions 42 has a first curved portion 46 and a second curved portion 48 located behind, and particularly directly behind, the first curved portion 46 in the cutting direction. The first curved portion 46 extends over approximately one eighth of a circle. The second curved portion 48 extends over approximately one quarter of a circle.

[0106] The second curved portion 48 has a smaller radius than the first curved portion 46. The radius of the first curved portion 46 and the radius of the second curved portion 48 have different centers. Here, the center point of the second curved portion 48 is preferably located a small distance, particularly 0.1 mm to 0.4 mm, rearward from the center point of the first curved portion 46 in the cutting direction.

[0107] The first circumferential portions 42 each merge into the second circumferential portion 44 via a transition portion 50. The transition portion 50 is located in the cutting direction, in particular directly behind the second curved portion 48. The transition portion 50 has a radius that is greater than the radius of the second curved portion 48. The transition portion 50 is followed in the circumferential direction by the second circumferential portion 44, which in the illustrated embodiment is formed by a third curved portion 52 that is slightly convexly curved. That is to say, the radius of the third curved portion 52 is significantly greater than the radius of the second curved portion 48, for example by at least eight times. The second circumferential portion 44 is in turn followed by one of the first circumferential portions 42, with a ridge 54 being formed between the two circumferential portions 42,44.

[0108] 22 and 23 are side views of the cutting head 10. In the figures, it can be seen that the protrusions 16 extend directly from the body 14. This results in a Z-shape formed by the end face of the body 14, the torque transmission surface 18 and the end face of the protrusions 16.

[0109] The projection 16 is substantially trapezoidal in longitudinal section, the inclined sides of the trapezoid forming a torque transmission surface 18 of the cutting head 10. The torque transmission surface 18 is inclined relative to the axial direction at an angle of attack preferably between 2° and 5°, in particular 3°.

[0110] In this case, 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 protrusion 16, i.e. both in the region of the first circumferential portion 42 and in the region of the second circumferential portion 44. For example, the different curvatures 46, 48 or transitions 50 or radii of the circumferential portions 42, 44 intersect with each other. Moreover, the axial angle of attack is constant over the entire axial extent of the protrusion 16. That is to say, the flanks of the protrusion 16 are free of steps, elevations and depressions in the region of the torque transmission surface 18 or in the region of the first circumferential portion 42 (and possibly also the second circumferential portion 44), but have a continuous inclined surface. In other words, the Z-shape of the protrusion 16 is the same over the entire circumferential contour.

[0111] The width of the projection 16 at its narrowest point is 1.5 to 3 times, and preferably 2 times, the axial extension of the projection 16. This axial dimension ensures a sufficiently large axial undercut.

[0112] Furthermore, the cutting head 10 has a centering projection 56, preferably circular in cross section and / or preferably arranged concentrically with the axis of rotation of the cutting tool 2. The centering projection 56 projects axially from the end face of the projection 16 of the cutting head 10. In the connected state of the cutting tool 2, the centering projection 56 engages in a correspondingly formed recess 58 in the cutting head driver 12. For example, the projection 16 or the torque transmission surface 18 of the cutting head 10 has an axial extent substantially twice as large as the centering projection 56.

[0113] 24 to 26 show various views of the cutting head driver 12. The cutting head driver 12 has a body 24, from whose end face an axially undercut projection 26 projects. The projection 26 is formed by two diametrically opposed webs 60 which surround a recess whose shape corresponds to that of the projection 16 of the cutting head 10. In the connected state of the cutting tool 2, the projection 16 of the cutting head faces with its outer circumferential surface which serves as the torque transmission surface 18 of the cutting head 10 against the inner circumferential surface of the projection 26 of the cutting head driver 12 which in turn serves as the torque transmission surface 28 of the cutting head driver 12.

[0114] The shape of the inner circumferential surface of the cutting head driver 12 corresponds to the shape of the first circumferential portion 42 of the cutting head 10. That is to say, the inner circumferential surface of the cutting head driver 12 or the web 60 is made up of several curved portions, each with a different radius. In particular, each web 60 has a first curved portion 62 and a second curved portion 64 located in the cutting direction, in particular directly behind it. The first curved portion 62 extends over approximately one eighth of a circle. The second curved portion 64 extends over approximately one quarter of a circle.

[0115] The second curved portion 64 has a smaller radius than the first curved portion 62. The radius of the first curved portion 62 and the radius of the second curved portion 64 have different center points. Here, the center point of the second curved portion 64 is preferably located a small distance, particularly 0.1 mm to 0.4 mm, behind the center point of the first curved portion 62 in the cutting direction.

[0116] The transition section 66 is adjacent to 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 significantly larger than the radius of the second curved section 64, so that the transition section 66 is, for example, approximately straight.

[0117] The inner circumferential surface of the web 60, which serves as the torque transmission surface 28, is inclined with respect to the axial direction at an angle of attack, preferably between 2° and 15°, in particular 3°. In particular, the axial angle of attack of the torque transmission surface 28, i.e. the axial setting angle of the cutting head driver 12, corresponds to the axial angle of attack of the torque transmission surface 18, i.e. the axial setting angle of the cutting head 10. This means that the cutting head driver 12 and the cutting head 10 are axially set at the same angle of attack. Here, the axial angle of attack is constant over the entire circumferential contour of the torque transmission surface 28. For example, the radii of the different curvatures 62, 64 or the transitions 66 intersect. Moreover, the axial angle of attack is constant over the entire axial extent of the projection 26. That is to say, no steps, elevations and depressions are formed in the region of the torque transmission surface 28, and the side surface is a continuous inclined surface. In other words, the Z-shape of the web 60 is the same over the entire circumferential contour.

[0118] The cutting head driver 12 is formed with 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 formed as a through hole. Alternatively, although not illustrated, the recess 58 can be formed as a blind hole.

[0119] Figures 27 and 28 show the principle of cutting tools known from the prior art and of the cutting tool 2 according to the present disclosure, on the basis of which a crucial aspect of the cutting tool common to the three embodiments already described will be restated: Figures 27 and 28 each show a cross section in a plane parallel to a longitudinal plane containing the axis of rotation.

[0120] As can be seen in FIG. 27, the solution in the prior art is that the end face 20 of the projection 16 of the cutting head 10 is spaced apart from the end face 32 of the body 24 of the cutting head driver 12, and the end face 22 of the body 14 of the cutting head 10 is in contact with the end face 30 of the projection 26 of the cutting head driver 12. That is, in the prior art, an axial gap is formed between the free end of the cutting head 10, in particular the part that forms the torque transmission surface 18, i.e. the free end of the wedge-shaped projection 16, and the cutting head driver 12. In contrast, the free end of the cutting head driver 12, in particular the part that forms the torque transmission surface 28, i.e. the free end of the wedge-shaped projection 26, is in contact with the cutting head 10. This forms a leverage arm in the cutting head driver 12, which generates tensile stresses in the circular portion 21, the stresses increasing with increasing leverage. Thus, a wedge-shaped gap in the cutting head 10 exists. Here, stresses induced in the circular portion 21 / notch are always present in such designs and can possibly be reduced somewhat by making the circular portion 21 larger.

[0121] In contrast, according to the present disclosure, as shown in FIG. 28, the end face 20 of the projection 16 of the cutting head 10 contacts the end face 32 of the body 24 of the cutting head driver 12, and the end face 22 of the body 14 of the cutting head 10 is spaced from the end face 30 of the projection 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, particularly the part forming the torque transmission surface 18, i.e., the free end of the wedge-shaped projection 16, and the cutting head driver 12, and the cutting head 10 contacts the cutting head driver 12 at the end face 20 of the wedge-shaped projection 16. This has the effect of providing a wedge support due to the axial contact of the cutting head 10 with the cutting head driver 12. The axial support of the cutting head provides a forced tangential guide, thereby reducing bending stress. Furthermore, since the friction forces (resulting from axial contact) act transversely to the axial direction, the loads (resulting from torque transmission at the torque transmission surface 18) are counterbalanced, as a result of which the bending stresses in the circular portion 21 are reduced (compared to prior art solutions).

[0122] In other words, the axial angular setting of the torque transmission surfaces 18, 28 constantly acts on the torque transmission surfaces 18, 28 during machining of the workpiece, resulting in a respective wedge-shaped cavity and thus in tensile stresses in the circular portions 21, 31. However, in the cutting tool 2 of the present disclosure, a frictional force is induced by the wedge support of the cutting head 10, i.e. by the axial contact with the cutting head driver 12, which frictional force acts transversely to the axial direction in the direction of the torque transmission surfaces 18, 28. This frictional force therefore opposes the expansion of the cutting head 10 (and not the expansion of the cutting head driver 12 as in the prior art) and as a result can reduce bending stresses in the region of the circular portion 21.

Claims

1. A cutting tool (2) for cutting a workpiece, comprising a cutting head (10), preferably made of cemented carbide, and a cutting head driver (12), preferably made of steel, connectable to the cutting head (10) via a kind of bayonet lock, The cutting head (10) and the cutting head driver (12) each have a body (14, 24) with an axially undercut projection (16, 26) projecting axially from an end face thereof; The protrusion (16) of the cutting head (10) and the protrusion (26) of the cutting head driver (12) are matingly connectable to each other by rotating the cutting head (10) in a counter-rotating manner with respect to the cutting direction of the cutting tool (2), and each has complementary axially undercut, preferably axially angled, torque transmission surfaces (18, 28) adjacent to each other in the connected state; A cutting tool (2), characterized in that the projections (16, 26) of the cutting head (10) and the cutting head driver (12) are dimensioned such that, in a connected state, an end face (20) of the projection (16) of the cutting head (10) is adjacent to an end face (32) of the body (24) of the cutting head driver (12) in the axial direction.

2. 2. The cutting tool (2) according to claim 1, characterized in that in the connected state, the end face (30) of the projection (16) of the cutting head driver (12) is spaced from the end face (22) of the body (14) of the cutting head (10) with axial play.

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

4. 4. The cutting tool (2) according to claim 1, wherein the protrusions have surfaces or shapes that interlock with each other when the cutting head and the cutting head driver are connected.

5. 5. A cutting tool (2) according to claim 1, characterized in that the cutting head and the cutting head driver have complementary shapes, the cross-section of the cutting head driver and the cross-section of the cutting head essentially correspond at their interface and / or the shape of the cutting head driver, in particular the spiral formation of the chip flute and / or the peripheral cutting edge, is continued by the cutting head.

6. 6. A cutting tool (2) according to claim 1, characterized in that the torque transmission surface is angled axially such that the cutting head is axially pressed in the direction of the cutting head driver by cutting forces acting during machining of a workpiece.

7. 7. A cutting tool (2) according to any one of claims 1 to 6, characterized in that the torque transmission surface is designed in such a way that tangential forces generated by cutting forces acting during machining of a workpiece are converted into axial forces such that the cutting head is pushed axially into contact with the cutting head driver.

8. The cutting tool (2) according to any one of claims 1 to 7, characterized in that the torque transmission surfaces (18, 28) are axially angled at an axial angle of attack of preferably 2° to 15°, more preferably 2° to 10°, particularly preferably 2° to 5°, and particularly preferably 3°.

9. 9. The 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 the same axial angle of attack.

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

11. A cutting tool (2) according to any 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 surface (18, 28).

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

13. The cutting tool (2) according to claim 12, characterized in that the Z-shape is due to 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 each torque transmission surface (18, 28) connecting each of the pair of end faces to each other extends substantially continuously and obliquely with respect to the axial direction between each of the pair of end faces.

14. The cutting tool (2) according to claim 13, characterized in that the axially outer one of the pair of end faces transitions to the torque transmission surface via a chamfered portion.

15. 15. The cutting tool (2) according to claim 13 or 14, characterized in that the axially inner one of the pair of end faces transitions to the torque transmission surface via a circular portion.

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

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

18. 18. A cutting tool (2) according to any one of claims 12 to 17, characterized in that the axial end faces of the opposing cutting head (10) and cutting head driver (12) are axially stepped by respective projections (16, 26) in such a way that a Z-shaped profile is produced in each case.

19. 19. The cutting tool (2) according to claim 1, characterized in that the cutting tool (2) has at least one cooling pipe (34) formed by a workpiece-side cooling pipe section (36) formed in the cutting head (10) and a shank-side cooling pipe section (38) formed in the cutting head driver (12), the shank-side cooling pipe section (38) communicating in the region of an end face (32) of the body (24) of the cutting head driver (12) with the workpiece-side cooling pipe section (36) in the region of an end face (20) of the protrusion (16) of the cutting head (10).

20. 20. The cutting tool (2) according to claim 19, characterized in that the cutting head (10) has at least one leading cutting edge (4) and a clearance (6) adjacent to the leading cutting edge (4), and the cooling channel (34) is adapted to exit the cutting tool (2) in the region of the clearance (6).

21. The cutting tool (2) according to any one of claims 1 to 20, characterized in that the cutting tool (2) has at least one helically extending peripheral cutting edge (8) formed on the cutting head (10) and the cutting head driver (12).

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

23. A cutting tool (2) according to any one of claims 1 to 22, characterized in that the cutting head driver (2) has two diametrically opposed projections (26) formed by a web extending across the entire diameter of the cutting tool.

24. 24. A cutting tool (2) according to any one of claims 1 to 23, characterized in that the cutting head (10) has two diametrically opposed projections (16) designed as pins / webs spaced radially from one another.

25. 23. A cutting tool (2) according to any one of claims 1 to 22, characterized in that the cutting head (10) has two diametrically opposed projections (16) formed by a web extending over the entire diameter of the cutting tool.

26. A cutting tool (2) according to any one of claims 1 to 22 or claim 25, characterized in that the cutting head driver (12) has two diametrically opposed projections (16) designed as pins / webs arranged radially spaced from one another.

27. 27. A cutting tool (2) according to any one of claims 1 to 26, characterized in that the axial contact surface (80) between the cutting head (10) and the cutting head driver (12) has a central portion (82) and wing portions (84) extending radially outward therefrom, said wing portions initially tapering from the central portion, in particular on both circumferential sides, and then widening again, in particular on both circumferential sides.

28. 28. Cutting tool according to claim 27, characterized in that the axial contact surface (80) is substantially doubly waisted.

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

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

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

32. 32. A cutting tool (2) according to claim 30 or 31, characterized in that a radially inner portion (88) of a circumferential contact surface formed on the cutting head is substantially convexly curved in the radial direction and a radially inner portion (88) of a complementary circumferential contact surface formed on the cutting head driver is substantially concavely curved in the radial direction.

33. 33. A cutting tool (2) according to any one of claims 30 to 32, characterized in that a radially outer portion (90) of a circumferential contact surface formed on the cutting head is substantially concavely curved in the radial direction and a radially outer portion (90) of a complementary circumferential contact surface formed on the cutting head driver is substantially convexly curved in the radial direction.

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

35. A cutting tool (2) according to any one of claims 30 to 34, characterized in that the circumferential contact surface (86) has a clamping portion located radially between a radially inner portion and a radially outer portion, which clamping portion functions primarily or exclusively as a clamping surface.

36. 36. A cutting tool (2) according to any one of claims 30 to 35, characterized in that the torque transmission surface (18, 28) formed by the radially inner portion (88) and the radially outer portion (90) extends in the axial direction over a maximum of half the axial extent of the projection (16, 26).

37. 37. A cutting tool (2) according to any one of claims 1 to 36, characterized in that the torque transmission surfaces (18, 28) are formed by curvatures with different radii, said curvatures being designed to interdigitate with one another over the entire circumferential contour of the torque transmission surfaces (18, 28).

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

39. 39. A cutting tool (2) according to claim 38, characterized in that the radius of the first curvature (48, 64) and the radius of the second curvature (46, 62) have different centre points.

40. 40. A cutting tool (2) according to claim 39, characterized in that the centre point of the second curved portion (46, 62) is located rearward, preferably by a small distance, in particular 0.1 mm to 0.4 mm, from the centre point of the first curved portion (48, 64) in the cutting direction.

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

42. A cutting tool (2) according to any one of claims 1 to 41, characterized in that the circumferential surface of the cutting head (10) is substantially convexly curved in a region of its circumferential contour adjacent to the cutting head driver (12) in the connected state and substantially concavely curved in a region of its circumferential contour not adjacent to the cutting head driver (12) in the connected state.

43. A cutting tool (2) according to any 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 arranged concentrically with the axis of rotation of the cutting tool (2), said centering projection protruding axially from an end face of the projection portion (16) of the cutting head (10).

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

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