Rotatable chip-removing tool

Abstract

Rotary-driven cutting tool (1) with a holder (10) extending along an axis of rotation (2) and a cutting head (20) held coaxially on the holder (10) by screwing it to a threaded sleeve (13) arranged in the holder (10), wherein the threaded sleeve (13) is arranged in the holder (10) in a rotationally fixed manner and is axially supported at least in the direction of the cutting head (20), and the cutting head (20) is axially clamped against the holder (10) by means of a threaded spindle (30) screwed into the threaded sleeve (13), characterized in that the threaded spindle (30) has a differential thread with opposing thread sections (30a, 30b) which are screwed into a threaded bore (13e) in the threaded sleeve (13) and a threaded bore (20c) in the cutting head (20).

Description

[0001] The invention relates to a rotary-driven cutting tool, in particular a ball track milling cutter, with a holder extending along an axis of rotation and a cutting head held coaxially on the holder by screwing it to a threaded sleeve arranged in the holder.

[0002] Such a tool is known from WO 2008 / 116 446 A1. WO 2008 / 116 446 A1 discloses and describes in particular a tool system (tool) with an HSK tool holder (holder) for coupling to a machine tool spindle and a ball track milling cutter (cutting head). The ball track milling cutter consists of a solid carbide milling head to which a shank is integrally attached and which carries four cutting inserts made of a hard material, e.g., CBN or PCD. The shank is shrink-fitted into a bore in a steel intermediate piece. The ball track milling cutter and intermediate piece are thus integrally connected. The intermediate piece has a threaded extension that is screwed into a sleeve-shaped component with an internal thread (threaded sleeve), which is axially fixed with lateral play in a bore in the tool holder.To attach the ball track milling cutter (cutting head with intermediate piece) to the tool holder, the sleeve-shaped component is screwed onto the pin extension of the intermediate piece using a hex key inserted into an internal hexagon socket in the sleeve-shaped component via the HSK shank of the tool holder. This draws the pin extension into the tool holder, bringing an annular flat surface on the intermediate piece into contact with a corresponding end-face flat surface on the tool holder. The tool described in WO 2008 / 116446 A1 also has a coolant / lubricant supply system with a main channel extending centrally along the axis of rotation through the tool holder, the intermediate piece, and the shank into the milling head. Within the milling head, this main channel branches into several secondary channels, each leading to a cutting edge of the milling head.

[0003] In the tool described in WO 2008 / 116446 A1, the sleeve-shaped component for actuation is only accessible via the HSK shank of the tool holder. This means that changing the milling head is only possible when the tool holder is disconnected from a machine tool spindle. Furthermore, the intermediate piece connecting the milling head to the tool holder increases the number of parts in the tool system and provides connection points to the milling head and tool holder that require special attention during manufacturing to ensure the necessary rigidity for high concentricity.

[0004] Document DE 10 2012 104 606 A1 discloses a rotary-driven cutting tool according to the preamble of claim 1. Documents WO 2003 / 051 564 A1 and DE 10 2009 012 433 A1 disclose further rotary-driven cutting tools.

[0005] Based on DE 10 2012 104 606 A1, the invention aims to create a simply constructed, compact tool, in particular a ball track milling cutter, in which the cutting head can be changed even when the tool is coupled to a machine tool spindle, thereby achieving a reliable, fixed axial clamping of the cutting head against a holder of the tool.

[0006] This problem is solved by a tool having the features of claim 1. The dependent claims relate to advantageous or preferred embodiments of the tool according to the invention, as well as advantageous embodiments of individual elements of the tool according to the invention.

[0007] A rotary-driven cutting tool according to the invention, which in a special embodiment is a ball track milling cutter, has a holder extending along an axis of rotation and a cutting head held coaxially on the holder by screwing it to a threaded sleeve arranged in the holder. It is characterized in that the threaded sleeve is arranged in the holder in a rotationally fixed manner and is axially supported at least in the direction of the cutting head, and the cutting head is axially clamped against the holder by means of a threaded spindle screwed into the threaded sleeve. The threaded spindle has a differential thread with opposing thread sections that are screwed into a threaded bore in the threaded sleeve and a threaded bore in the cutting head.

[0008] The holder is designed for coupling to a machine tool spindle, as in the tool known from WO 2008 / 116 446 A1. For this purpose, it has a suitable shank, e.g., a known HSK shank. The cutting head has one or more cutting edges. It can be formed in one piece, e.g., from solid carbide or a hard material. In an advantageous embodiment, however, the cutting head is formed from a carrier body, preferably made of steel or solid carbide, and one or more cutting elements attached to the carrier body, e.g., indexable inserts, preferably made of a hard material, in particular CBN or PCD, or with a hard material coating, in particular CBN or PCD. The cutting elements can be bonded to the carrier body by a material connection, e.g., by brazing or bonding.

[0009] In contrast to the tool known from WO 2008 / 116 446 A1, in a tool according to the invention the threaded sleeve is arranged in the holder in a rotationally fixed manner and the cutting head is fastened to the holder by a rotary actuation of the threaded spindle relative to the threaded sleeve which is arranged in the holder in a rotationally fixed manner.

[0010] Since the threaded spindle is not screwed directly to the holder but to the threaded sleeve integrated within the holder, the threaded sleeve can be manufactured from a tough, elastic material suitable for thread production, particularly high-speed steel (HSS), regardless of the holder's material. HSS materials are characterized by high hardness, wear resistance, and heat resistance. Compared to cemented carbides, they are less susceptible to fracture from impacts and vibrations. This ensures the thread strength required for the axial clamping of the cutting head against the holder.

[0011] A threaded spindle according to the invention is suitable for smaller cutting head diameters due to the lack of a larger diameter head. Furthermore, the cutting edges of the cutting head can be extended towards the center (the axis of rotation). The opposing thread sections ensure that a reliable, firm axial clamping of the cutting head against the holder is achieved with just a few turns of the threaded spindle.

[0012] The cutting head is clamped axially against the holder by a rotary actuator of the threaded spindle. For this purpose, the threaded sleeve is fixedly arranged in the holder and supported axially, at least in the direction of the cutting head. Additional axial support of the threaded sleeve towards the holder is advantageous to generate an axial ejection force when the screw connection is loosened, which drives the cutting head away from the holder. Appropriate stops can be provided in the holder for the axial support of the threaded sleeve. The stops can be designed so that the threaded sleeve is fixed axially in the holder. Alternatively, the stops can be designed so that the threaded sleeve is allowed limited axial movement within the holder.

[0013] The threaded sleeve is advantageously arranged with a defined clearance fit in an axial bore in the holder and is rotationally fixed to the holder by means of one or more connecting elements that interact with the threaded sleeve and the holder in a form-fit and / or force-fit manner. The connecting element(s) can, for example, be designed as a connecting pin in the manner of a pin connection known from shaft-hub connections, each extending in a corresponding radial transverse bore that is received in a form-fit and / or force-fit manner from the holder into the threaded sleeve. Such a pin connection allows the threaded sleeve to be fixed not only in a rotationally fixed position within the holder, but also in the axial direction.

[0014] Alternatively, a rotationally fixed connection between the threaded sleeve received in the holder with a clearance fit and the holder can be achieved directly (i.e. without an additional connecting element) by a positive locking between the threaded sleeve and the holder, for example by means of positively interlocking cross-sectional profiles, as is known in principle from shaft-hub connections, or indirectly by means of known drive structures (drive grooves, drive blocks) that effect a positive locking between the threaded sleeve and the holder.

[0015] An axial support of the threaded sleeve in the direction of the cutting head can be achieved, for example, by the threaded sleeve having a flange-like radial projection at its holder-side end, which is axially supported in the direction of the cutting head on a radial shoulder formed in the holder, which forms an axial stop.

[0016] The design according to the invention offers the possibility of constructing the holder modularly in such a way that the threaded sleeve is arranged interchangeably within the holder. The holder can thus be formed from a base body and a receiving part, which is fixed to the base body in a rotationally and axially fixed manner and which receives the threaded sleeve in a rotationally fixed manner. The threaded sleeve can be arranged fixed or with limited axial displacement between the receiving part and the base body. The receiving part can, in particular, be formed from a hollow cylindrical bushing and received in an axial bore in the base body by means of an interference fit, e.g., by shrink fitting. The fixed connection between the receiving part and the base body can be released again by heating the base body. To achieve high tool rigidity, the receiving part is advantageously made of a hard metal material.The receiving part thus provides a solid basis for the formation of the contact surfaces between the cutting head and holder discussed above.

[0017] For rotary actuation of the threaded spindle, the tool according to the invention offers the possibility of actuating the threaded spindle from the holder side and / or from the cutting head side. In a preferred embodiment of the tool according to the invention, the threaded spindle can be actuated from the end face of the cutting head furthest from the holder via an axial through-reach in the cutting head. This embodiment allows the cutting head to be changed even when the holder is coupled to a machine tool spindle.

[0018] To attach the cutting head to the holder, one or more contact surfaces can be provided on the holder, against which the cutting head comes into contact during axial clamping.

[0019] For high concentricity, the cutting head can have an axial projection at its holder-side end, inserted into an axial receiving opening in the holder. The axial projection and the receiving opening can each be cylindrical, at least in sections, such that when the cutting head is axially clamped against the holder, the axial projection (cutting head) is axially guided in the receiving opening (holder). For this purpose, the axial projection can be received in the receiving opening with a tight clearance fit. Alternatively, the axial projection and the receiving opening can be conical, at least in sections, i.e., the axial projection has an external cone and the receiving opening a corresponding internal cone, such that when the cutting head is axially clamped against the holder, the axial projection (cutting head) is centered in the receiving opening (holder).Unlike the simpler cylindrical surface, which always has some play (albeit slight), the conical surface contact provides a play-free surface contact between the axial projection and the mounting opening, resulting in automatic centering of the cutting head on the holder. This ensures high concentricity of the tool.

[0020] Additionally, the cutting head can have an annular end face surrounding the axial projection at its holder-side end. When the cutting head is axially clamped against the holder, this annular end face comes into contact with a corresponding annular end face on the holder. The annular end face on the cutting head and the corresponding annular end face on the holder can each be a flat surface lying in a radial plane. Alternatively, they can each be a conical surface. This contact between the cutting head-side end face and the holder-side end face creates a connection between the cutting head and holder characterized by high rigidity and resulting in high concentricity.In conjunction with the conical surface contact between the axial projection and the receiving opening discussed above, the end surface contact results in a total of two surface contact between the cutting head and the holder, which ensures high concentricity and high tool rigidity.

[0021] In a preferred embodiment, the cutting head can have an axial through-hole open at its end face, allowing access to the threaded spindle screwed into the cutting head for rotary actuation. To prevent the ingress of chips, dirt particles, etc., the axial through-hole can be closed at its end face by means of a removable sealing element. The sealing element can, for example, be a sealing screw screwed into the axial through-hole.

[0022] In an advantageous embodiment, the tool according to the invention further comprises a coolant / lubricant channel extending centrally along the axis of rotation through the holder (optionally the base body and the receiving part of the holder), the threaded sleeve, and the threaded spindle into the cutting head for supplying the cutting head with coolant / lubricant supplied from the holder. If the cutting head has the aforementioned axial through-passage, this can form part of the coolant / lubricant channel. In this case, the tool according to the invention can supply the cutting head with coolant / lubricant, for example, by allowing it to exit through the axial through-passage at the end face and distribute itself around the cutting head at the cutting point.

[0023] At least one branch channel can branch off from the central coolant / lubricant channel in the cutting head, leading to at least one associated cutting edge on the cutting head. In this case, it may be advantageous to close any existing axial passage in the cutting head with the aforementioned sealing element to ensure that the coolant / lubricant flows to the at least one associated cutting edge only via the at least one branch channel.

[0024] The following describes an embodiment of a rotary-driven cutting tool according to the invention, using the ball track milling cutter shown in the accompanying drawings as an example. The drawings show: Fig. 1a a side view of the ball track cutter; Fig. 1b a front view of the ball track cutter; Fig. 1c an exploded view of the ball track cutter in perspective view; Fig. 2a a half section (longitudinal) of a holder of the ball track cutter; Fig. 2b a front view of the holder; Fig. 3a a half section (longitudinal) of a basic body of the holder; Fig. 3b a front view of the basic body; Fig. 4a a full section (longitudinal) of a receiving part of the holder; Fig. 4b a front view of the recording part; Fig. 5 a half section (longitudinal) of a threaded sleeve held in the receiving part; Fig. 6a a side view of a milling head with threaded spindle; Fig. 6b a front view of the milling head; Fig. 6c a scaled-down full section (longitudinal) of the milling head with threaded spindle; Fig. 7a a half section (longitudinal) of the threaded spindle; Fig. 7b a front view of the threaded spindle; and Fig. 7c a rear view of the threaded spindle.

[0025] The in Fig. 1a and Fig. The rotary-driven cutting tool shown in Figure 1b is designed as a ball-track milling cutter 1 with a holder 10 extending along a rotary axis 2 and a cutting head in the form of a milling head 20 held on the holder 10. For fastening to the holder 10, the milling head 20 is axially screwed to the holder 10 by means of a threaded spindle 30, as shown in Figure 1b. Fig. 1c is shown. Fig. Figure 1c further shows a closure element in the form of a closure screw 40, which closes an axial passage in the milling head 20.

[0026] Holder 10 is detailed in the Fig. 2a to 5 illustrate how, in particular, Fig. 2a shows that the holder 10 is modularly constructed from a base body 11, a receiving part 12 held coaxially on the base body 11 and a threaded sleeve 13 arranged coaxially in the receiving part 12.

[0027] The steel base body 11 has on its in Fig. 2a On the right side, a shaft in the form of a hollow shaft cone (HSK) 11a for coupling the ball track milling cutter 1 to, for example, a machine tool spindle. On the in Fig. On the left side, the base body 11 has a central axial bore 11b. The axial bore 11b is separated from the axial inner recess of the hollow shaft cone 11a by a radial partition 11c. An axial through-hole 11d is formed centrally in the radial partition 11c, allowing the passage of a wrench. The radial partition 11c limits the depth of the axial bore 11b and forms an axial end stop for the receiving part 12 and the threaded sleeve 13.

[0028] The details in Fig. 4a and Fig. The receiving part 12 shown in Figure 4b is formed from a hollow cylindrical bushing made of a hard metal material and is press-fitted into the axial bore 11b in the base body 11, i.e., integrated into the base body 11 in a rotationally and axially fixed manner. To achieve high connection stiffness, the receiving part 12 is made of a suitable hard metal material. The receiving part 12 has an axial bore 12a in its central longitudinal section, which receives the threaded sleeve 13 described later. On the Fig. 4a On the right side, a blind hole 12b with an increased diameter adjoins the axial bore 12a, which is in Fig. 4a is bounded to the left by a radial step 12c. The radial step 12c forms a contact surface on which a Fig. The flange-like radial projection 13a of the threaded sleeve 13, visible in Figure 5, is axially supported. In the area of ​​the longitudinal section of the blind hole bore 12b, the receiving part 12 further has a transverse bore 12d, which is for receiving a Fig. The connecting pin 14 shown in 2a serves to connect the threaded sleeve 13 to the receiving part 12, which is shrunk into the base body 12, in a rotationally fixed manner. The axial bore 12a opens into Fig. 4a to the left into a Fig. 4a Conical receiving opening 12e, increasing in diameter to the left. A transition section 12f connects the inner cone of the receiving opening 12e to the axial bore 12a. The conical receiving opening 12e serves to receive a Fig. 6a and Fig. 6c recognizable conical axial projection 20b (outer cone) of the milling head 20.

[0029] The tubular threaded sleeve 13, which is to be arranged in the axial bore 12a of the receiving part 12, is made of an HSS material and, as shown in Fig. 5, which is essentially T-shaped. It points to the Fig. 5 on the right side the aforementioned flange-like radial projection 13a, which is located at its Fig. 5 left annular end face comes into axial contact with the radial contact surface formed by the radial step 12c when the threaded sleeve 13 in Fig. 4a is inserted into the receiving part 12 from the right. The axial length of the radial projection 13a is ideally greater than or equal to the axial depth of the blind hole bore 12b of the receiving part 12. In the Fig. In the state shown in Figure 2a, the threaded sleeve 13 and the receiving part 12 rest against the end face of the radial partition 11c on the milling head side, i.e., at the bottom of the axial bore 11b. In this case, the threaded sleeve 13 is axially supported both towards the milling head 20 and towards the holder 10, without being able to move axially. Furthermore, the threaded sleeve 13 has a transverse bore 13b in the longitudinal section of the radial projection 13a, which is located in the Fig. The state shown in Figure 2a, in which the threaded sleeve 13 is inserted into the receiving part 12 until the radial projection 13a abuts the radial step 12c, is aligned with the transverse bore 12d of the receiving part 12. The Fig. 2a The connecting pin 14 shown is inserted into the two transverse bores 12d, 13b, thereby providing a rotationally and axially fixed connection between the threaded sleeve 13 and the receiving part 12 or generally between the threaded sleeve 13 and the holder 10.

[0030] In an alternative embodiment, the axial length of the radial projection 13a of the threaded sleeve 13 can be smaller than the axial depth of the blind hole bore 12b of the receiving part, whereby the threaded sleeve 13 is inserted into the Fig. The clamping state shown in 1a would be arranged to the right at a small axial distance to the radial partition 11c of the base body 11. This design allows a limited axial displacement of the threaded sleeve 13 in the holder 10, for example, if the threaded sleeve 13 has an axial longitudinal groove instead of the transverse bore 12d, into which the connecting pin 14 engages.

[0031] The radial projection 13a is followed by Fig. 5 to the left, a cylindrical section 13c is attached. The outer diameter of the cylindrical section 13c is smaller than the inner diameter of the axial bore 12a of the receiving part 12. Furthermore, the outer diameter of the radial projection 13a is smaller than the inner diameter of the blind hole 12b of the receiving part 12. The threaded sleeve 13 can thus be inserted with a defined lateral clearance into Fig. Insert part 4a from the right into the receiving part 12 until the radial projection 13a comes to rest against the radial step 12c of the receiving part 12. In this state, the two transverse bores 13b, 12d are aligned with each other (or, in the alternative embodiment, the transverse bore 13b is aligned with the axial longitudinal groove in the threaded sleeve 13).

[0032] The threaded sleeve 13 further indicates on its Fig. 5 on the left side a threaded bore 13e into which a transition section 13f Fig. 5 to the left, an axial bore 13d runs centrally through the threaded sleeve 13. The differential thread screw 30 mentioned above is screwed into this threaded bore 13e to clamp the milling head 20 against the holder 10.

[0033] As it is in Fig. As shown in Figure 2a, the length of the threaded sleeve 13 is shorter than the length of the receiving part 12 such that the threaded sleeve 13 ends before the conical receiving opening 12e, so as not to impede the axial insertion of a later described conical axial projection 20b of the milling head 20 into the conical receiving opening 12e of the receiving part 12. In the Fig. In the state shown in 2a, the threaded sleeve 13 ends at the interface between the axial bore 12a and the transition section 12f.

[0034] The milling head 20 is according to Fig. 6a to Fig. 6c is formed from a carrier body 20a made of steel or solid carbide and a plurality of plate-shaped cutting elements 21, e.g., indexable or replaceable inserts, made of hard material, in particular CBN or PCD, or with a hard material coating, in particular CBN or PCD, distributed around the axis of rotation 2. The cutting elements 21 can be bonded to the carrier body 20a, e.g., by brazing or bonding. Alternatively, the milling head 20 can be formed in one piece, e.g., from solid carbide or hard material.

[0035] The milling head 20 has on its in Fig. 6a on the right side a conical axial projection 20b, which is to be inserted into the conical receiving opening 12e of the receiving part 12 for fastening the milling head 20 to the holder 10. As shown in Fig. As shown in Figure 1a, in the assembled state of the ball track cutter 1, a holder-side end face 20e of the milling head 20, which surrounds the axial projection 20b in a ring-like manner, can be located at a small axial distance from an opposing annular end face 12g on the receiving part 12. The annular end face 20e on the milling head 20, like the opposing annular end face 12g on the receiving part 12, is formed by a radial planar surface. The outer cone formed by the axial projection 20b of the milling head 20 and the inner cone formed by the receiving opening 12e of the receiving part 12 are located in the Fig. The ball track milling cutter 1 shown in Figure 1a is therefore designed such that, when the differential thread screw 30 is rotated, the milling head 20 is only retracted into the holder 10 to the extent that the end face 20e on the milling head 20 does not come into contact with the end face 12g on the mounting part 12. The milling head 20 is centered on the holder 10 by the conical surface contact between the axial projection 20b and the mounting opening 12e in the mounting part 12.

[0036] In an advantageous embodiment, the outer cone formed by the axial projection 20b of the milling head 20 and the inner cone formed by the receiving opening 12e of the receiving part 12 are designed such that, when the differential thread screw 30 is rotated, the milling head 20 is drawn into the holder 10 to such an extent that the end face 20e on the milling head 20 comes into contact with the end face 12g on the receiving part 12, i.e., in the clamped state, the end face 20e of the milling head 20 rests flat against the opposite end face 12g of the receiving part 12 without any axial gap, while at the same time the milling head 20 is arranged in a centered position on the holder 10 by the conical surface contact between the axial projection 20b and the receiving opening 12e in the receiving part 12.

[0037] As it is in Fig. As shown in Figure 6c, the milling head 20 has a threaded bore 20c running centrally through the axial projection 20b, into which the differential thread screw 30 is screwed. The threaded bore 20c extends into Fig. 6c transitions to the left into a threaded bore 20d with a reduced diameter, into which the sealing screw 40 is screwed. The threaded bore 20d forms an axially open through-hole, allowing access to the differential threaded screw 30 for its rotary actuation. To prevent the ingress of chips, dirt particles, etc., and to prevent axial leakage of coolant / lubricant, which is supplied to the cutting elements 21 via a coolant / lubricant supply system described later, a sealing screw 40 is located in the threaded bore 20d, sealing the bore 20d fluid-tight.

[0038] The threaded spindle designed as a differential thread screw 30 is in detail in Fig. 7a to Fig. Figure 7c shows the differential thread screw 30 having two opposing thread sections 30a, 30b, which are screwed into the threaded bore 20c in the milling head 20 and into the threaded bore 13e in the threaded sleeve 13, respectively, to fasten the milling head 20 to the holder 10. For rotary actuation, the threaded spindle 30 has two end-face hexagon socket openings, which are connected to each other via a central connecting bore 30e.

[0039] The ball track milling cutter 1 further has an internal cooling / lubricating agent supply system 50, which essentially consists of a cooling / lubricating agent channel 50a running centrally along the axis of rotation 2 through the holder 10 (the base body 11 and the receiving part 12), the threaded sleeve 13 and the threaded spindle 30 into the cutting head 20, as well as a plurality of branch channels 50b branching off from the central cooling / lubricating agent channel 50a in the area of ​​the threaded bore 20c of the milling head 20 and each leading to one of the cutting elements 21 on the milling head 20. The centrally running coolant / lubricant channel 50a leads through the axial bore 13d, the transition section 13f and the threaded bore 13e of the threaded sleeve 13 as well as the internal hexagon 30d, the connecting bore 30e and the internal hexagon 30c of the differential thread screw 30 into the threaded bore 20c and the threaded bore 20d of the milling head 20 to the sealing screw 40.The coolant / lubricant is supplied via a (not shown) feed point on the machine tool side into the axial bore 13d of the threaded sleeve. Fig. 1a, Fig. 1c and Fig. 6a shows the outlet opening of one of the branch channels 50b, while Fig. Figure 6c shows the entrance opening of one of the branch channels 50b.

[0040] To assemble the ball track cutter 1, the following is used: Fig.The milling head 20, shown in Figure 6c, with the differential thread screw 30 already pre-assembled, is first inserted axially into the conical receiving opening 12e of the receiving part 12, i.e., the holder 10, which is held on the base body 11. By turning the differential thread screw 30, it is then screwed into the threaded sleeve 13 already arranged in the receiving part 12, with the result that the milling head 20 is axially clamped against the holder 10. Centering of the milling head 20 is automatically achieved via the conical surface contact between the outer cone of the axial projection 20b of the milling head 20 and the inner cone 12e of the receiving part 12. In the advantageous embodiment mentioned above, a flat surface contact is additionally achieved between the end face of the milling head and the end face of the holder 10. The threaded sleeve 13 is, as mentioned above, arranged in the holder 10 in a rotationally fixed manner and axially supported in the direction of the milling head 20.To drive the differential threaded screw 30, the ball track milling cutter 1 offers the possibility of inserting a suitable hex key via the HSK shank 11a, the axial through-hole 11d in the radial partition 11c, and the axial bore 13d in the threaded sleeve 13 into the internal hexagon 30d, or alternatively via the threaded bore 20d in the milling head 20, if necessary after first removing the sealing screw 40, into the internal hexagon 30c. A suitable hex key can therefore be inserted from the holder side or from the milling head side. After clamping the milling head 20 to the holder 10, the threaded bore 20d in the milling head 20 can be sealed fluid-tight using the sealing screw 40. In the assembled state, the ball track milling cutter 1 can be coupled to a machine tool spindle (not shown). Reference symbol list 1 ball track cutter (tool) 2. Axis of rotation 10 holders 11 Basic shapes 11a Hollow shank cone (HSK shank) 11b Axial bore 11c radial partition 11d axial penetration 12 Recording section 12a Axial bore 12b Blind hole drilling 12c radial step 12d cross-drilling 12e Intake opening (inner cone) 12f Transition section 12g frontal area 13 Threaded sleeve 13a Radial lead 13b Cross bore 13c Cylinder section 13d axial bore 13e Threaded hole 13f Transition section 14 Connecting pin 20 Milling head (cutting head) 20a Carrier body 20b Axial projection 20c threaded hole 20d Threaded hole (axial through-hole) 20e Front surface 21 Cutting element 30 Differential thread screw (threaded spindle) 30a Thread section 30b thread section 30c Allen key 30d internal hexagon 30e connection hole 40 Locking screw (locking element) 50 Cooling / lubricant supply system 50a central cooling / lubricant channel 50b branch channel

Claims

[1] Rotary cutting tool (1) with a holder (10) extending along an axis of rotation (2) and a cutting head (20) held coaxially on the holder (10) by screwing it to a threaded sleeve (13) arranged in the holder (10), wherein the threaded sleeve (13) is arranged in the holder (10) in a rotationally fixed manner and is axially supported at least in the direction of the cutting head (20), and the cutting head (20) is axially clamped against the holder (10) by means of a threaded spindle (30) screwed into the threaded sleeve (13), characterized by , that the threaded spindle (30) has a differential thread with opposing thread sections (30a, 30b) which are screwed into a threaded bore (13e) in the threaded sleeve (13) and a threaded bore (20c) in the cutting head (20). [2] Tool (1) according to claim 1, characterized by, that the cutting head (20) has an axial projection (20b) at its holder-side end inserted in an axial receiving opening (12e) in the holder (10). [3] Tool (1) according to claim 2, characterized by , that the axial projection (20b) and the receiving opening (12e) are each conically shaped. [4] Tool (1) according to claim 2 or 3, characterized by , that the cutting head (20) has at its holder-side end a front surface (20e) surrounding the axial projection (20b) in a ring shape, which rests against an opposite front surface (12g) on ​​the holder (10). [5] Tool (1) according to any one of claims 1 to 4, characterized by , that the holder (10) is formed from a base body (11) and a receiving part (12) which is held rotationally and axially fixed on the base body (11) and in which the threaded sleeve (13) is arranged. [6] Tool (1) according to claim 5, characterized by , that the receiving part (12) is force-fitted into the base body (11). [7] Tool (1) according to any one of claims 1 to 6, characterized by , that the threaded sleeve (13) arranged in the holder (10) is axially supported in the direction of the cutting head (20) via a flange-like radial projection (13a) on a radial step (12c) formed in the holder (10). [8] Tool (1) according to any one of claims 1 to 7, characterized by , that the threaded spindle (30) is accessible via an axial through-pass (20d) open at the end face in the cutting head (20). [9] Tool (1) according to claim 8, characterized by a removable locking element (40) arranged in the axial passage (20d) which closes the axial passage (20d). [10] Tool (1) according to any one of claims 1 to 9, characterized bya coolant / lubricant channel (50a) running along the axis of rotation (2) centrally through the holder (10) and the threaded spindle (30) into the cutting head (20) for supplying the cutting head (20) with a coolant / lubricant supplied from the holder side. [11] Tool (1) according to claim 10, characterized by , that the central cooling / lubricating channel (50a) in the cutting head (20) branches into at least one branch channel (50b) which leads to at least one associated cutting edge on the cutting head (20). [12] Tool (1) according to any one of claims 1 to 11, characterized by , that the threaded sleeve (13) is received in the holder (10) with a clearance fit and is connected to the holder (10) at least in a rotationally fixed manner. [13] Tool (1) according to any one of claims 1 to 12, characterized by , that the cutting head (20) is formed from a carrier body (20a) and one or more cutting elements (21) attached to the carrier body (20a).

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