Milling Tool Bodies and Assemblies

Abstract

The present invention relates to a milling tool body (1) rotatable about a central axis of rotation (R). The milling tool body (1) has a front end face (2) and a rear end face (3). An envelope surface (4) surrounds the central axis of rotation (R) and extends between the rear end face (3) and the front end face (2). A plurality of insert pockets (5) are formed at the transition between the envelope surface (4) and the front end face (2). A first central through hole (6) of constant diameter extends between the rear end face (3) and the front end face (2). The milling tool body (1) includes a locking disc (7) having a second central through hole (8) and a fastening device (9) configured to extend through the second central through hole (8) of the locking disc (7). When the milling tool body (1) is attached to the adapter (10) by means of a fastening device (9) which can be attached to the end (11) of the adapter (10), the locking disc (7) is configured to press against the front end face (2) of the milling tool body (1), and the adapter (10) is insertable into the first central through hole (6) of the milling tool body (1).

Description

[Technical field]

[0001] The present invention relates to a milling tool body rotatable about a central axis of rotation. The milling tool body has a front end face and a rear end face, an envelope surface surrounding the central axis of rotation and extending between the rear end face and the front end face. A number of insert pockets are formed in the transition between the envelope surface and the front end face. The insert pockets are configured to receive cutting inserts for chip removal machining, the milling tool body being configured in particular for face milling and / or shoulder milling operations.

[0002] The invention also relates to an assembly comprising a milling tool body and an adapter for connecting the milling tool body to a milling machine. [Background technology]

[0003] The present invention relates to a problem that can arise in known milling tool bodies that are attached to an adapter used to connect the milling tool body to a milling machine.

[0004] US Patent No. 9,238,273 discloses a known milling tool body which is attached to an adapter (holder) by a screw. The milling tool body has a central through hole which forms a cylindrical seat for the adapter with a relatively small diameter and a cylindrical coolant chamber with a relatively large diameter. An internal shoulder is formed inside the central through hole between the cylindrical seat and the cylindrical coolant chamber, and the milling tool body is attached to the adapter by the screw head pressing against the internal shoulder of the central through hole via a washer.

[0005] U.S. Patent No. 9,623,497 discloses a similar milling tool body having a screw that is used to attach the milling tool body to an adapter inserted into a central through hole in the milling tool body. A concave surface is formed in the front surface of the milling tool body. The concave surface includes a cylindrical surface that extends axially into the front surface of the milling tool body, and an internal shoulder surface (seat surface) for the screw extends radially inwardly of the bottom surface of the concave surface. A coolant cap is further secured by a retaining ring attached to the cylindrical surface of the concave surface, whereby the coolant cap is spaced from the set screw to form a coolant chamber having a concave surface.

[0006] Japanese Patent No. 4349824 discloses another known milling tool body having a central through hole with two different diameters. The milling tool body is attached to an adapter (arbor) inserted into the central through hole by a screw (fastening bolt) that screws the adapter, and abuts against an internal shoulder formed by the different diameters of the central through hole.

[0007] The above-mentioned known milling tool bodies may be subject to vibrations caused by an unbalanced milling tool body, which wobble when rotating about a central rotation axis (during milling), and further, the milling tool body may be subject to axial / radial runout, which causes the cutting inserts mounted in the insert pockets to exhibit deviations in position between their respective cutting edges.

[0008] More precisely, when parts of different diameters are manufactured by separate drilling and / or milling operations performed from the rear end face and the front end face of the milling tool body, respectively, with a central through hole, vibrations caused by an unbalanced rotary milling tool body may occur. Insufficient manufacturing tolerances during these drilling / milling operations may result in non-concentric parts of different diameters. In other words, this may cause the milling tool body to exhibit an uneven distribution of mass around the central rotation axis, which may result in vibrations during the milling operation. Furthermore, since the screw head presses directly (or through a washer) against the internal shoulder surface, whereas the rear end face abuts against the adapter with a relatively large diameter, the fastening force / load applied to the milling tool body when mounting the milling tool body to the adapter is concentrated in the center of the milling tool body. The fastening force applied in the center from the screw head acting on the internal shoulder surface may induce elastic deformation or bending of the milling tool body, which causes axial / radial runout in the mounted cutting insert in the insert pocket. Summary of the Invention

[0009] It is an object of the present invention to provide a milling tool body that has a reduced tendency to vibrate during use and reduces axial / radial runout when the milling tool body is mounted on an adapter, thereby improving the machining accuracy or surface finish of the milled workpiece surface and reducing wear on the cutting inserts mounted in the insert pockets of the milling tool body.

[0010] This object is achieved by a milling tool body according to claim 1. The milling tool body of the invention thus has a front end face and a rear end face, an envelope surface surrounding a central rotation axis and extending between the rear end face and the front end face. The milling tool body comprises a plurality of insert pockets formed in the transition between the envelope surface and the front end face. The milling tool body is characterized in that a first central through hole of constant diameter extends between the rear end face and the front end face, the milling tool body comprises a locking disc having a second central through hole and a fastening device configured to extend through the second central through hole of the locking disc, the locking disc being configured to press against the front end face of the milling tool body when attaching the milling tool body to the adapter by means of the fastening device which can be attached to an end of the adapter, the adapter being insertable into the first central through hole of the milling tool body.

[0011] The constant diameter of the first central through hole does not take into account that the first central through hole has any inner flange or internal shoulder surface for attaching the milling tool body with a fastening device (screw). In this way, the first central through hole can be manufactured in a single drilling operation, for example from only one side of the milling tool body, whereby further drilling or milling from the opposite side is no longer required for the manufacture of the inner flange / internal shoulder surface and the manufacture of the coolant chamber, which is recessed relative to the front end face. This reduces the risk of manufacturing an unbalanced milling tool body, which causes vibrations during milling.

[0012] Furthermore, the locking disk is a load component coupled to the adapter by means of a fastening device, the locking disk being configured to press against the front end face at a more radially outer region of the milling tool body. Thus, the compressive force / load on the milling tool body is distributed more uniformly compared to coupling the milling tool body to the adapter by a screw directly (or via a washer) pressing against the inner shoulder surface of the milling tool body. This results in less elastic deformation or bending of the attached milling tool body, thereby reducing the axial / radial runout of the cutting edge on the cutting insert mounted in the insert pocket of the milling tool body.

[0013] In one embodiment of the milling tool body, the diameter of the locking disc is at least 50% of the maximum diameter of the milling tool body. In this way, the binding force provided by the locking disc is further improved by moving the locking disc radially outward to at least 50% of the maximum diameter of the milling tool body. This allows the locking disc and the adapter at the rear end face to provide opposing and aligned compressive forces, which reduces the elastic deformation or bending of the attached milling tool body, thereby further reducing the axial / radial runout of the milling tool body. The locking disc can also provide distributed forces / loads at the front end face of the milling tool body, which is beneficial for reducing the elastic deformation or bending of the attached milling tool body.

[0014] In a further embodiment of the milling tool body, the diameter of the locking disc is substantially the same as the diameter of the rear end face. This therefore provides the rear end face with a planar mounting surface with essentially the same outer diameter as the outer diameter of the locking disc. Substantially the same diameter does not mean that they are exactly the same diameter. Instead, substantially the same diameter should be understood to also include a deviation of ±10% between the diameter of the locking disc and the rear end face of the milling tool body. In this way, the locking disc and the rear end face present the same diameter, whereby the locking disc and the adapter at the rear end face provide opposite and aligned compression forces, which minimizes the risk of elastic deformation or bending of the attached tool body, thereby further reducing the axial / radial runout of the milling tool body.

[0015] In a further embodiment of the milling tool body, the front end face comprises a plurality of radial coolant grooves for directing coolant from the first central through hole towards the insert pocket, the radial coolant grooves being at least partially covered by the locking disk when the milling tool body is mounted on the adapter. Such coolant grooves are easier to manufacture than internal coolant channels. This facilitates the manufacture of the milling tool body for supplying coolant to the cutting insert mounted in the insert pocket, since there is no need to drill internal coolant channels through the milling tool body or machine large coolant chambers recessed into the front end face. Instead, the radial coolant grooves can be formed in the front end face covered by the locking disk pressing against the front end face of the milling tool body.

[0016] In a further embodiment of the milling tool body, the radial coolant grooves of the front end face extend between the first central through hole and the insert pocket. In other words, the radial coolant grooves extend entirely between the first central through hole and the insert pocket. In this way, the coolant is guided to the insert pocket only inside the coolant grooves. This simplifies manufacturing compared to having an internal coolant channel in the milling tool body.

[0017] In another embodiment of the milling tool body, the radial coolant grooves on the front face are connected to the internal coolant channels of the milling tool body, which extend between the radial coolant grooves and the insert pocket. Each internal coolant channel is thus drilled in the outer part of the milling tool body and communicates with each radial coolant groove. In this way, the direction of the coolant can be optimized so that it reaches the insert pocket at a desired angle. Furthermore, the radial coolant grooves are preferably connected to the internal coolant channels at a position located radially inside the diameter of the locking disk. Thereby, the locking disk completely covers the radial coolant grooves, which turn into internal coolant channels at a position located inside the locking disk.

[0018] In one embodiment of the milling tool body, the front end face forms an annular relief surface, which surrounds the central rotation axis and is configured to provide an axial clearance for the locking disc, and the front end face forms an abutment surface, which surrounds the annular relief surface and which contacts the locking disc when the milling tool body is mounted on the adapter. The annular relief surface ensures that the contact between the locking disc and the front end face is provided radially outward in the area of ​​the abutment surface surrounding the annular relief surface. Preferably, the abutment surface is provided in the outer annular area of ​​the locking disc (slightly inside the maximum diameter of the locking disc). This achieves a defined / controlled contact between the locking disc and the front end face. Furthermore, the locking disc can bend somewhat when mounting the milling tool body on the adapter, and the annular relief surface ensures that the bent locking disc does not impede the supply of coolant from the outlet at the end of the adapter.

[0019] In the aforementioned embodiment, when viewed in a longitudinal section including the central rotation axis of the milling tool body, the annular relief surface can form a conical relief surface extending at an acute angle θ to the central rotation axis. In this way, the gap formed between the locking disc and the front end face increases in the radially inward direction, whereby the gap is larger in the inner area (around the second central through hole and the fastening device), where the bending of the locking disc exhibits the highest deflection. The acute angle θ of the conical relief surface can be in the range of 89.5°≦θ≦86°. In other words, the conical relief surface forms a rather small inclination (0.5°-4°) with a perpendicular horizontal plane relative to the rotation axis or the plane of the locking disc. The purpose of the relief surface is merely to provide a small axial clearance in order to ensure, on the one hand, that the locking disc contacts the abutment surface in a defined outer radial area and, on the other hand, that a potential bending of the locking disc does not impede the supply of coolant from the adapter in the inner radial area of ​​the front end face of the milling tool body.

[0020] In yet another embodiment, when viewed in a longitudinal section including the central rotation axis of the milling tool body, the abutment surface forms a convex abutment surface for contacting the locking disk when the milling tool body is mounted on the adapter. The convex abutment surface ensures a defined (circle / line) contact between the locking disk and the abutment surface surrounding the annular relief surface. The convex abutment surface provides high pressure to the circle / line contact between the locking disk and the convex abutment surface to prevent leakage of coolant around the locking disk, whereby the coolant passes instead through the coolant grooves (and internal coolant channels) of the milling tool body.

[0021] In another embodiment, the locking disc comprises a ring-shaped contact surface on its outer part, which, when viewed in a longitudinal section containing the central rotation axis of the milling tool body, forms a convex contact surface for contacting the front end face when the milling tool body is mounted on the adapter, which is an alternative solution to having a convex abutment surface on the front end face of the milling tool body.

[0022] In one embodiment, the milling tool body is disk-shaped with a rear end surface with a planar mounting surface directly connected to the envelope surface, which extends with a continuously increasing diameter from the planar mounting surface towards the front end surface. Thus, the milling tool body is disk-shaped in the sense that it does not have a cylindrical rear end portion as in conventional milling tool bodies (e.g., as shown in the prior art above). In this way, the disk-shaped milling tool body reduces the distance that the milling tool body extends from the adapter (also known as the tool overhang). The reduction in the distance or tool overhang of the milling tool body further reduces vibrations during milling operations. Furthermore, the disk-shaped tool body also reduces the manufacturing and shipping costs of the milling tool body due to the less material and lighter mass of the milling tool body. The relatively light mass of the milling tool body is also beneficial in reducing vibrations during milling.

[0023] In a further embodiment of the milling tool body, the rear end face further comprises a drive slot recessed relative to the planar mounting surface and the envelope surface connected to the planar mounting surface. In this way, a stable drive connection is achieved without additional equipment on the milling tool body, as compared to known milling tool bodies having a cylindrical rear end portion including a drive slot. This further reduces the mass of the milling tool body, and thus vibrations during milling as well as the manufacturing / transportation costs of the milling tool body.

[0024] In one embodiment of the milling tool body, the fastening device is a screw with a threaded shank and a screw head with a tapered bearing surface towards the threaded shank, and the second central through hole of the locking disk includes a chamfered surface for abutting on the tapered bearing surface of the screw head, so that when the milling tool body is attached to the adapter, the screw head is at least partially countersunk in the second through hole of the locking disk. This reduces the axial protrusion of the screw head from the locking disk, since the tapered bearing surface of the screw head abuts on the chamfered surface located inside the second through hole. This therefore reduces the axial protrusion of the screw head and ensures that the screw head is located axially inside the axially forward most position of the cutting insert attached in the insert pocket. The screw head is preferably a flat head with a tapered bearing surface. A flat screw head therefore results in a relatively short screw head, which further reduces the axial protrusion of the screw head from the locking disk. The chamfered surface of the second central through hole and the tapered bearing surface of the screw head preferably present a conical extension. However, the tapered bearing surface and the chamfered surface may present concave and convex curved extensions, respectively, so that the bearing surface and the chamfered surface therefore present complementary shapes for abutting each other.

[0025] The invention further relates to an assembly comprising the above-mentioned milling tool body and an adapter comprising a cylindrical shaft portion insertable into a first central through-hole of the milling tool body, the fastening device being a screw and an end of the cylindrical shaft portion comprising a central threaded hole. Thus, the assembly comprising the milling tool body with the locking disk and the adapter can be joined by mounting a screw into the central threaded hole at the end of the adapter, whereby the mounted assembly or the rear end portion of the adapter can be connected to a milling machine.

[0026] In one embodiment of the assembly, the adapter comprises at least one internal coolant passage extending parallel to the central threaded hole inside the cylindrical shaft portion, the at least one internal coolant passage having an outlet located radially outside the central threaded hole at the end of the cylindrical shaft portion. In other words, the coolant outlet and the central threaded hole are arranged side by side at the end of the cylindrical shaft portion, the central threaded hole connecting the locking disk to the adapter. In this way, the coolant from the outlet can be directed further radially outward in a coolant groove provided radially outside the central threaded hole and provided between the front end face of the milling tool body and the locking disk. Preferably, the adapter comprises several internal coolant passages extending parallel to the central threaded hole, the internal coolant passages being evenly arranged around the central threaded hole and having outlets evenly arranged around the central threaded hole. This ensures an even distribution of the coolant over the entire circumference of the milling tool body.

[0027] The embodiment will be described with reference to the drawings. [Brief description of the drawings]

[0028] [Figure 1a] FIG. 1 is a perspective view of an assembly including a milling tool body and an adapter according to an embodiment of the present invention; [Figure 1b] FIG. 1b shows an exploded view towards the rear end of the assembly of FIG. 1a. [Figure 1c] FIG. 1b shows an exploded view towards the front end of the assembly of FIG. 1a. [Diagram 2] FIG. 1b is a longitudinal cross-sectional view of the assembly of FIG. 1a, including the central axis of rotation. [Diagram 3] FIG. 13 is a front end view of the assembly without the locking disc and fasteners. [Figure 4] FIG. 2 is a longitudinal section through the central axis of rotation of a milling tool body without a locking disk and a fastening member. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0029] 1a-1c show a perspective view and two exploded views of an assembly with a milling tool body 1 and an adapter 10 according to an embodiment of the present invention. The milling tool body 1, which is rotatable about a central axis of rotation R, comprises a front end face 2 and a rear end face 3, an envelope face 4 surrounding the central axis of rotation R and extending between the rear end face 3 and the front end face 2. In the transition between the envelope face 4 and the front end face 2, a number of insert pockets 5 are formed. The insert pockets 5 are configured for mounting indexable cutting inserts, which are not disclosed. More precisely, the pockets 5 are thereby configured with support surfaces 5a, 5b for mounting indexable cutting inserts for face milling. The milling tool body is thus adapted for face milling. The support surfaces comprise support surfaces 5a, 5b, which are configured such that the actual main cutting edge of the cutting insert forms an acute angle with respect to a horizontal plane perpendicular to the central axis of rotation R. In other words, the milling tool body is configured for face milling by having the main cutting edges of the indexable cutting inserts extending at an acute inclination angle (45°) relative to the horizontal plane. However, the milling tool body may also be configured for shoulder milling operations by means of a pocket including support surfaces 5a, 5b configured to support cutting inserts having the actual main cutting edges extending parallel to the central axis of rotation (at a 90° inclination angle).

[0030] 2 and 4, a first central through hole 6 of constant diameter extends between the rear end face 3 and the front end face 2, and a cylindrical shaft portion 10a of an adapter 10 is insertable into the first central through hole 6. The milling tool body 1 further comprises a locking disc 7 having a second central through hole 8 and a fastening device 9 in the form of a screw configured to pass through the second central through hole 8 of the locking disc 7. The locking disc 7 is configured to press against the front end face 2 of the milling tool body 1 when the milling tool body 1 is attached to the adapter 10. This is achieved by attaching the fastening device / screw 9 to a central threaded hole 12 of an end 11 of the cylindrical shaft portion 10a inserted into the first central through hole 6 of the milling tool body.

[0031] The milling tool body in the illustrated embodiment is disk-shaped with a rear end face 3 having a flat mounting surface 3a directly connected to an envelope surface 4, which extends with a continuously increasing diameter from the flat mounting surface 3a towards the front end face 2. The envelope surface 4 does not extend with a continuously increasing diameter up to the front end face 2. Instead, the milling tool body 1 thereby has a maximum diameter D at the periphery of the pocket 5. MAX (see FIG. 2 ), and the envelope surface 4 has a maximum diameter D MAX and the front end face 2 .

[0032] The rear end face 3 of the milling tool body further comprises a drive slot 3b or keyway that is recessed relative to the planar mounting surface 3a and the envelope surface 4. The adapter 10 is provided with a corresponding drive key 10b that engages with the drive slot / keyway 3b when the adapter is mounted to the milling tool body. In other words, the milling tool body and the adapter form an arbor mounting for transmitting torque between the adapter and the milling tool body.

[0033] As can be seen in FIG. 2, the locking disc 6 is located at the maximum diameter D MAX A diameter D that is at least 50% of D More precisely, in this embodiment, the locking disc 10 has a diameter D D is approximately 65% ​​of the maximum diameter of the milling tool body. This results in a diameter D D As shown in FIG. 4, the outer diameter D of the flat mounting surface 3a of the rear end surface 3 R corresponds to (is essentially the same as)

[0034] FIG. 3 discloses a front end view towards the front end face 2 of the milling tool body. The front end face 2 includes a number of radial coolant grooves 2a which direct coolant from the first central through hole 6 towards the insert pocket 5. The radial coolant grooves 2a are covered by the lock disk 7 when the milling tool body 1 is mounted on the adapter 10. Each radial coolant groove 2a is further connected to an internal coolant channel 2b in the milling tool body, each internal coolant channel 2b extending between the radial coolant groove 2a and the insert pocket 5. The radial coolant grooves 2a are aligned along a diameter D of the lock disk 7. D 2. The lock disc 7 is connected to the internal coolant channel 2b at a position located radially inside the lock disc 7. As a result, the lock disc 7 completely covers the radial coolant grooves 2a, and the radial coolant grooves 2a turn into internal coolant channels 2b at a radial position located inside the lock disc 7.

[0035] The front end face 2 further forms an annular relief surface 2c surrounding the central axis of rotation R, which is configured to provide an axial gap A for the locking disc 7. The axial gap A between the locking disc 7 and the annular relief surface 2c is thus very small and is barely visible in FIG. 3. The axial gap A is provided by the annular relief surface 2c, which, when viewed in a longitudinal section through the central axis of rotation R of the milling tool body, forms a conical relief surface extending at an acute angle θ to the central axis of rotation R (see FIG. 4). The acute angle θ on the relief surface 2c is thus relatively large and can be in the range of 89.5°≦θ≦86°. In the illustrated embodiment, the acute angle θ of the relief surface 2c is 89° to the central axis of rotation R, providing the locking disc 7 with said axial gap A.

[0036] The front end face 2 further forms an abutment surface 2d surrounding the annular relief surface 2c, which is configured to come into contact with the locking disc 7 when the milling tool body 1 is mounted on the adapter 10. The abutment surface 2d in the illustrated embodiment forms a convex abutment surface 2d, as seen in the longitudinal section in FIG. 4, which ensures a defined (circle / line) contact in an outer annular area between the locking disc 7 and the convex abutment surface 2d when the milling tool body 1 is mounted on the adapter 10. Alternatively, the locking disc 7 may be provided with a ring-shaped contact surface on its outer part, which, when seen in a longitudinal section including the central rotation axis R, forms a convex contact surface for contacting the flat annular portion of the front end face 2 when the milling tool body 1 is mounted on the adapter 10. This achieves the same effect of the above-mentioned defined (circle / line) contact in an outer annular area between the convex contact surface of the locking disc and the flat annular portion of the front end face.

[0037] The fastening device is a screw 9 having a threaded shank 9a and a screw head 9b with a tapered bearing surface 9c towards the threaded shank 9a, and the second central through hole 8 of the locking disk 7 includes a chamfered surface 8a for abutting against the tapered bearing surface 9c of the screw head 9b, so that when the milling tool body 1 is attached to the adapter 10, the screw head 9b is at least partially countersunk in the second through hole 8 of the locking disk 7. This reduces the axial projection of the screw head 9b from the locking disk 7, as can be seen in FIG. 3, and the tapered bearing surface 9c of the screw head 9b abuts against the chamfered surface 8a located inside the second through hole 8, reducing the axial projection of the screw head 9b. Furthermore, as can be seen, the screw head 9b is located axially inside the axially most forward position of the insert pocket. Furthermore, the screw head 9b is a flat head with a tapered bearing surface 9c in order to provide a relatively short screw head and further reduce the axial projection of the screw head 9b from the locking disk 7. The chamfered surface 8a of the second central through hole 8 and the tapered bearing surface 9c of the screw head 9b further present corresponding conical extensions for abutting against the inside of the second central through hole 8.

[0038] As can be seen in Figs. 1-3, the adapter 10 comprises a cylindrical shaft portion 10a, which is inserted into the first central through hole 6 of the milling tool body. The fastening device is a screw 9, and the end 11 of the cylindrical shaft portion 10a comprises a central threaded hole 12 for mounting the screw 9, whereby the locking disk 7 presses against the front end face 2 with a convex abutment surface 2d. The adapter 10 comprises a plurality (four) of internal coolant passages 13 extending parallel to the central threaded hole 12 inside the cylindrical shaft portion 10a, each internal coolant passage 13 having an outlet 13a located radially outside the central threaded hole 12 at the end 11 of the cylindrical shaft portion 10a. The internal coolant passages 13 have four outlets 13a, which are evenly (spaced) around the central threaded hole 12 to ensure an even distribution of the coolant around the entire circumference of the milling tool body 1.

[0039] This allows the first central through hole 6 of constant diameter to be produced by a single drilling / milling operation from either the front end 2 or the rear end 3 of the milling tool body, thereby reducing the risk of producing an unbalanced milling tool body that would cause vibrations during milling. In other words, the milling tool body does not need to be produced with an inner mounting flange / internal shoulder surface (or a large coolant chamber recessed relative to the front end face). Instead, the locking disc 7, with the screw 9 extending through the second central through hole 8, is mounted in a central threaded hole 12 at the end of the adapter 10, whereby the locking disc 7 is fitted to the diameter D of the planar mounting surface 3a at the rear end 3 of the milling tool body. R 2. The front and rear forces acting on the attached milling tool body 1 are thereby directed and aligned in opposite directions to minimize elastic deformation or bending of the milling tool body, and thus minimize axial / radial run-out of the attached milling tool body.

[0040] Furthermore, the conical relief surface 2c along the front end face 2 of the milling tool body 1 provides a small axial clearance A on the one hand to ensure that the locking disc 7 contacts the front end face 2 in a defined outer annular radial area (convex abutment surface 2d) and on the other hand that potential bending of the locking disc 7 does not impede the supply of coolant from the coolant outlet 13a of the adapter 13. The locking disc can be made quite thick / rigid, but can nevertheless bend if the screw 9 is installed with excessive torque in the screw hole 12. The deflection caused by such bending of the locking disc 7 is maximum around the center of the second screw hole 12, and the conical relief surface 2c is configured to provide the locking disc 7 with a maximum axial clearance A to ensure outer contact and flow of coolant from the outlet 13a. Thereby, the coolant leaving the coolant outlet 13a flows along the coolant grooves 2a provided in the front end face 2 into the internal coolant channels 2b, which can further guide the coolant to the insert pocket 5, so that the coolant reaches the insert pocket 5 at a desired angle towards the cutting insert mounted in the insert pocket 5. Furthermore, the radial coolant grooves 2a are aligned along the diameter D of the lock disk 7. D1, the lock disc 7 is connected to the internal coolant channel 2b at a position located radially inside of the first through hole 6, so that the lock disc 7 covers the radial coolant grooves 2a to prevent leakage and provide an effective transfer of coolant to the pocket 5. The convex abutment surface 2d further provides a defined line / circular contact with the lock disc 7 to minimize leakage of coolant around the lock disc 7 and ensure that the coolant is transferred to the internal coolant channel 2b. The same effect can thus be achieved by providing the lock disc 7 with a ring-shaped contact surface at its outer part, which, when viewed in a longitudinal section including the central rotation axis R of the milling tool body 1, forms a convex contact surface for contacting the front end face 2 when the milling tool body 1 is mounted on the adapter 10. Furthermore, the front end face 2 of the milling tool body can alternatively be provided with a coolant groove 2b all the way between the first through hole 6 and the insert pocket 5. This simplifies the manufacture of the milling tool body 1, but may reduce the efficiency of the supply of coolant to the insert pocket 5.

[0041] Of course, the present invention is not limited to the above-described embodiment, and various modifications are possible within the scope of the claims.

Claims

1. A milling tool body (1) rotatable about a central axis of rotation (R) and having a front end face (2) and a rear end face (3), an envelope surface (4) surrounding the central axis of rotation (R) and extending between the rear end face (3) and the front end face (2), a plurality of insert pockets (5) being formed at the transition between the envelope surface (4) and the front end face (2), a first central through hole (6) of constant diameter extending between the rear end face (3) and the front end face (2), the milling tool body (1) being provided with a rotor having a second central through hole (8). a locking disk (7) and a fastening device (9) configured to extend through the second central through hole (8) of the locking disk (7), the locking disk (7) being configured to press against the front end face (2) of the milling tool body (1) when the milling tool body (1) is attached to the adapter (10) by means of the fastening device (9) which may be attached to an end (11) of an adapter (10), the adapter (10) being insertable into the first central through hole (6) of the milling tool body (1); the front end face (2) forms an annular relief surface (2c), the annular relief surface (2c) surrounding the central rotation axis (R) and configured to provide an axial gap (A) to the lock disc (7); the front end face (2) forms an abutment surface (2d), the abutment surface (2d) surrounding the annular relief surface (2c) and coming into contact with the lock disc (7) when the milling tool body (1) is mounted on the adapter (10); the annular relief surface (2c), when viewed in a longitudinal section containing the central axis of rotation (R) of the milling tool body (1), forms a conical relief surface extending at an acute angle θ to the central axis of rotation (R), The milling tool body (1), characterized in that the acute angle θ is in the range of 86°≦θ≦89.5°.

2. The diameter (D Ｄ ) is the maximum diameter (D ＭＡＸ 2. The milling tool body of claim 1, wherein the surface roughness is at least 50% of the surface roughness.

3. The diameter (D Ｄ ) is the diameter (D Ｒ 3. The milling tool body according to claim 1, wherein the milling tool body is substantially the same as

4. 4. The milling tool body according to claim 1, wherein the front end face (2) comprises a plurality of radial coolant grooves (2a) for directing coolant from the first central through hole (6) towards the insert pocket (5), the radial coolant grooves (2a) being at least partially covered by the lock disc (7) when the milling tool body (1) is attached to the adapter (10).

5. 5. A milling tool body according to claim 4, wherein the radial coolant groove (2a) of the front end face (2) extends between the first central through hole (6) and the insert pocket (5).

6. 5. The milling tool body according to claim 4, wherein the radial coolant grooves (2a) of the front end face are connected to internal coolant channels (2b) of the milling tool body, the internal coolant channels (2b) extending between the radial coolant grooves (2a) and the insert pocket (5).

7. 2. A milling tool body according to claim 1, wherein the abutment surface (2d), when viewed in a longitudinal section containing the central rotation axis (R) of the milling tool body, forms a convex abutment surface for contacting the lock disc (7) when the milling tool body (1) is mounted on the adapter (10).

8. 7. A milling tool body according to claim 1, wherein the lock disc (7) is provided with a ring-shaped contact surface on an outer portion of the lock disc (7), which, when viewed in a longitudinal section containing the central axis of rotation (R) of the milling tool body (1), forms a convex contact surface for contacting the front end face (2) when the milling tool body (1) is mounted on the adapter (10).

9. 9. A milling tool body according to any one of claims 1 to 8, wherein the milling tool body is disk-shaped by the rear end face (3) having a flat mounting surface (3a) directly connected to the envelope surface (4), the envelope surface (4) extending with a continuously increasing diameter from the flat mounting surface (3a) towards the front end face (2).

10. 10. The milling tool body according to claim 9, wherein the rear end face (3) further comprises a drive slot (3b) recessed with respect to the planar mounting surface (3a) and the envelope surface (4) connected to the planar mounting surface (3a).

11. 11. A milling tool body according to any one of claims 1 to 10, wherein the fastening device (9) is a screw having a threaded shank (9a) and a screw head (9b) including a bearing surface (9c) tapered towards the threaded shank (9a), and the second central through hole (8) of the locking disk (7) includes a chamfered surface (8a) for the tapered bearing surface (9c), whereby the screw head (9b) is at least partially countersunk in the second central through hole (8) of the locking disk (7) when the milling tool body (1) is attached to the adapter (10).

12. 12. An assembly comprising a milling tool body according to any one of claims 1 to 11 and an adapter (10) including a cylindrical shaft portion (10a) insertable into the first central through hole (6) of the milling tool body, wherein the fastening device (9) is a screw and an end (11) of the cylindrical shaft portion (10a) is provided with a central screw hole (12).

13. 13. The assembly of claim 12, wherein the adapter comprises at least one internal coolant passage (13) extending inside the cylindrical shaft portion, the at least one internal coolant passage (13) having an outlet (13a) located radially outside the central threaded hole (12) at the end (11) of the cylindrical shaft portion (10a).

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