Milling tool body and milling tool

Abstract

A milling tool body (2) for a milling tool (1), the milling tool body (2) comprising: an axial leading face (3), an axial trailing face (4), an outer circumferential mantle surface (10) extending between the axial leading face (3) and the axial trailing face (4), a front end (2a), a rear end (2b) configured for mounting the milling tool (1) to a machine, and at least two insert seats (20) and associated chip pockets provided entirely within the front end (2a), the milling tool body (2) including a cooling duct system (50) extending from at least one coolant inlet (30) located in a first ring-shaped portion (11) of the outer circumferential mantle surface (10) to at least one coolant outlet (40) located in a second ring-shaped portion (12) of the outer circumferential mantle surface, the first and second ring-shaped portions adjoining sealing surfaces formed as surfaces of revolution, preferably cylindrical surfaces.

Description

[Technical Field]

[0001] The present invention relates to a milling tool body according to the preamble of claim 1. The present invention also relates to a milling tool comprising such a milling tool body. [Background technology]

[0002] Manufacturing processes in the metals industry sometimes require hot workpieces to be milled to desired dimensions because the manufacturing steps preceding such milling operations and subsequent steps in the manufacturing process require the workpieces to have high temperatures, typically 600-800°C.

[0003] Cemented carbide tools and inserts can withstand high temperatures, but this reduces tool life. Such thermal loads are particularly detrimental to milling tool bodies carrying replaceable cemented carbide inserts if the milling tool is not cooled.

[0004] As a result of heat transfer, i.e., conduction, convection and radiation, the milling tool body also heats up. When the milling tool body reaches a critical temperature, the material in the milling tool body, which is usually steel, softens and is unable to withstand the mechanical loads generated during the cutting process.

[0005] Therefore, a milling tool can only be used for a short portion of the milling operation before the critical temperature is reached and it must be replaced with another milling tool of the same type. The replaced tool must then be cooled outside the machining zone. Because such a milling operation can take a total of 30 to 50 minutes, several tools of the same type must be available and used alternately, and several tool changes must be made to complete the entire milling operation.

[0006] EP 3587031 A1 discloses a milling tool body having an axial front end face, an axial rear end face, and a longitudinal axis extending between the axial front end face and the axial rear end face. The milling tool body includes at least one coolant inlet and at least one coolant outlet housed in the milling tool body, and a cooling duct system. The cooling duct system extends from the at least one coolant inlet to the at least one coolant outlet and is arranged so that coolant supplied through the at least one coolant inlet flows through the cooling duct system to the at least one coolant outlet without exiting the milling tool body to cool the milling tool. The at least one coolant inlet and at least one coolant outlet are arranged on the axial rear end face. The milling tool body is attachable to a machine via a tool holder that transmits torque from the machine to the milling tool body. The coolant is transmitted to the at least one coolant inlet and returned through the tool holder via the at least one coolant outlet. Each of the at least one coolant inlet ports communicates with an orifice in a coolant supply channel located on the front surface of the tool holder, and each of the at least one coolant outlet ports communicates with an orifice in a coolant return channel within the tool holder. This requires tight tolerances in the manufacture of the milling tool body and tool holder at the interface between the milling tool body and tool holder, and each tool requires a specific tool holder due to the different number of grooves and / or different tool diameters. The axial rear end face of the milling tool and the front surface of the tool holder must be pressed against each other and held in close contact to prevent coolant leakage. Tool bending during use can cause loss of contact between the axial rear end face of the milling tool and the front surface of the tool holder. Furthermore, tool holders, including mounts and stators, are expensive, especially for tools with larger tool diameters.

[0007] [Problem of the Invention] The object of the present invention is to provide a milling tool for sustainable machining of hot workpieces, which has a new and advantageous design and which solves or at least reduces the above-mentioned problems. Summary of the Invention

[0008] According to a first aspect of the present invention, the aforementioned object is achieved by a milling tool body for a milling tool, the milling tool body having the features defined in claim 1.

[0009] A milling tool body for a milling tool is a part of the milling tool that is arranged to carry a cutting edge. The milling tool is attached to the milling machine via the milling tool body, either directly or via a tool holder. The cutting edge may be formed integrally with the milling tool body or may be arranged on an exchangeable cutting insert that can be attached to an insert seat located in the milling tool body. Such an insert seat may be formed in an exchangeable cartridge attached to the milling tool body.

[0010] A milling tool body according to a first aspect of the present invention comprises: an axial front end surface; an axial rear end surface opposite to the axial front end surface; an outer circumferential mantle surface extending between the axially forward end surface and the axially aft end surface; a front end portion extending from an axial front end surface toward an axial rear end surface; a rear end portion extending from a rear end face of the milling tool body toward the front end portion, the rear end portion configured for attachment to a machine; a first central longitudinal axis extending between an axially leading end surface and an axially trailing end surface, the tool body being rotationally rotatable about the first central longitudinal axis; at least two insert seats disposed generally at the front end and distributed circumferentially about the milling tool body, each configured to receive a cutting insert; a chip pocket defined by a chip pocket wall disposed generally at the front end of each of the at least two insert seats and rotationally forward of the at least two insert seats; at least one coolant inlet and at least one coolant outlet are disposed within the milling tool body; A cooling duct system housed in the milling tool body extends from the at least one coolant inlet to the at least one coolant outlet, and the cooling duct system is arranged such that coolant supplied through the at least one coolant inlet flows through the cooling duct system to the at least one coolant outlet without leaving the milling tool body along a path between the at least one coolant inlet and the at least one coolant outlet.

[0011] The chip pockets provided forward of each of the at least two insert seats and the at least two insert seats are generally provided at a front end of the milling tool body, which is defined by an axial front end face and extends toward an axial rear end face, i.e., to the axial ends of the chip pockets of each of the at least two insert seats.

[0012] According to the present invention, at least one coolant inlet is arranged in a first ring-shaped portion of the outer peripheral mantle surface of the milling tool body, and at least one coolant outlet is arranged in a second ring-shaped portion of the outer peripheral mantle surface of the milling tool body. The first and second ring-shaped portions are separated from each other by an intermediate ring-shaped portion of the outer peripheral mantle surface. The first ring-shaped portion is adjacent to a third ring-shaped portion of the outer peripheral mantle surface, such that, when viewed in the direction of the first longitudinal central axis, the first ring-shaped portion is axially located between the intermediate and third ring-shaped portions. The second ring-shaped portion is adjacent to the fourth ring-shaped portion of the outer peripheral mantle surface when viewed along the first longitudinal central axis, thereby positioning the second ring-shaped portion axially between the intermediate and fourth ring-shaped portions. The first, second, third, fourth, and intermediate ring-shaped portions extend between the front end and the axial rear end surface, and each of the third, fourth, and intermediate ring-shaped portions is a surface of revolution generated by 360° rotation of a curved or straight line about the first longitudinal central axis C1 of the milling tool body, and is arranged to be a seal surface and cooperate with the seal ring configuration. A surface of revolution is a surface generated by 360° rotation of a curved or straight line about a rotation axis. Cylindrical surfaces and frusto-conical surfaces are examples of surfaces of revolution. Each of the third, fourth, and intermediate ring-shaped portions preferably has mirror symmetry with respect to a plane perpendicular to the first longitudinal central axis. This arrangement of the third, fourth, and intermediate ring-shaped portions reduces the risk of associated seal ring configurations shifting during use of the milling tool. More preferably, each of the third, fourth, and intermediate ring-shaped portions is cylindrical and has a central axis that coincides with the first longitudinal central axis of the milling tool body. The inventors have observed that this arrangement of the third, fourth, and intermediate ring-shaped portions provides optimal results in terms of the service life of the seal ring configurations and simplifies the manufacture of the milling tool body.

[0013] Such sealing surfaces may be dynamic or static sealing surfaces. Dynamic sealing surfaces mean that there is relative movement between the surface and the associated seal ring arrangement. Dynamic sealing surfaces preferably have surface characteristics to prevent premature wear of the associated seal ring arrangement. 0.05≦Ra≦0.20μm, 0.40≦Rz≦1.60μm, 0.63≦Rmax≦2.50 μm. Such a surface is preferably produced by grinding, honing, polishing, lapping or a similar finishing method.

[0014] A static seal surface means that there is no relative movement between the surface and the associated seal ring arrangement. A static seal surface preferably has surface characteristics Ra≦1.60 μm, Rz≦10.00μm, Rmax≦16.00 μm. Such a surface may be produced by cutting.

[0015] Therefore, each of the third, fourth, and intermediate ring-shaped portions of the outer peripheral mantle surface of the milling tool body, when intended to be a dynamic sealing surface, preferably has surface characteristics 0.05≦Ra≦0.20μm, 0.40≦Rz≦1.60μm, 0.63≦Rmax≦2.50 μm, If it is intended to be a static sealing surface, Ra≦1.60 μm, Rz≦10.00μm, Rmax≦16.00 μm.

[0016] If the dynamic seal surface has surface characteristics of Ra<0.05 μm, Rz<0.40 μm, and Rmax<0.63 μm, the lubrication between the dynamic seal surface and the associated seal ring will be insufficient, resulting in premature wear of the associated seal ring, especially at the higher temperatures typical of the applications in which the milling tool is used. If the dynamic seal surface has surface characteristics of Ra>0.20 μm, Rz>1.60 μm, and Rmax>2.50 μm, the associated seal ring may suffer premature mechanical wear. If the static seal surface has surface characteristics of Ra>1.60 μm, Rz>10.00 μm, and Rmax>16.00 μm, the associated seal ring may suffer premature mechanical wear and failure.

[0017] The milling tool body according to the first aspect of the present invention is part of a milling tool and is arranged to carry a cutting edge. The milling tool body and milling tool are attachable to a milling machine via a rear end of the tool body. The milling tool further comprises: a coolant ring having an outer peripheral surface and an inner peripheral surface, the inner peripheral surface having a first ring-shaped portion, a second ring-shaped portion, a third ring-shaped portion, a fourth ring-shaped portion, and an intermediate ring-shaped portion, each of the third ring-shaped portion, the fourth ring-shaped portion, and the intermediate ring-shaped portion of the inner peripheral surface of the coolant ring being a surface of revolution generated by a 360° rotation of a curved or straight line about a common second longitudinal central axis, and being arranged to be a sealing surface and to cooperate with the seal ring arrangement; a coolant ring attached to the milling tool body such that an inner peripheral surface of the coolant ring surrounds an outer peripheral mantle surface of the milling tool body, and such that a first ring-shaped portion, a second ring-shaped portion, a third ring-shaped portion, a fourth ring-shaped portion, and an intermediate ring-shaped portion of the inner peripheral surface of the coolant ring face the first ring-shaped portion, the second ring-shaped portion, the third ring-shaped portion, the fourth ring-shaped portion, and an intermediate ring-shaped portion of the outer peripheral mantle surface of the milling tool body, respectively; a first seal ring arrangement mounted between and arranged to cooperate with a third ring-shaped portion of the outer peripheral mantle surface of the tool body and a third ring-shaped portion of the inner peripheral surface of the coolant ring; a second seal ring arrangement mounted between and arranged to cooperate with the fourth ring-shaped portion of the outer circumferential mantle surface of the tool body and the fourth ring-shaped portion of the inner circumferential surface of the coolant ring; a third seal ring arrangement mounted between and cooperatively arranged to couple with an intermediate ring-shaped portion of the outer circumferential mantle surface of the tool body and an intermediate ring-shaped portion of the inner circumferential surface of the coolant ring; The coolant ring, the first seal ring arrangement, the second seal ring arrangement, and the third seal ring arrangement, when mounted on the tool body, the second central longitudinal axis is substantially coincident with the first central longitudinal axis; a first annular coolant channel formed between a first ring-shaped portion of the outer circumferential mantle surface and a first ring-shaped portion of the inner circumferential surface of the coolant ring and axially sealed by the first seal ring arrangement and the third seal ring arrangement; a second annular coolant channel is formed between a second ring-shaped portion of the outer circumferential mantle surface and a second ring-shaped portion of the inner circumferential surface of the coolant ring and is axially sealed by the second seal ring arrangement and the third seal ring arrangement; The milling tool body is arranged to be rotatable relative to the coolant ring; The coolant ring comprises at least one coolant transmission channel arranged to communicate with the first annular channel, and the coolant ring further comprises at least one coolant return channel arranged to communicate with the second annular coolant channel, each of the at least one coolant transmission channel extending from a coolant inlet at the outer periphery of the coolant ring to an orifice in the first ring-shaped portion of the inner circumferential surface of the coolant ring, and each of the at least one coolant return channel extending from an orifice in the second ring-shaped portion of the inner circumferential surface of the coolant ring to a coolant outlet at the outer periphery of the coolant ring.

[0018] The coolant ring includes a fastening means for fastening the coolant ring to the exterior of the machine when the milling tool is attached to the machine to prevent movement and rotation of the coolant ring. Thus, the coolant ring is a stationary coolant ring when the tool is attached to the machine and when the coolant ring is fastened to the exterior of the machine via the fastening means of the coolant ring, and the milling tool body can rotate inside the coolant ring when torque from the machine is applied.

[0019] The milling tool body design described above means that tight tolerances are not required for the interface between the milling tool body and the tool holder, since the coolant can be transferred to the coolant duct system, through the outer mantle surface, via the coolant ring, and then returned from the coolant duct system. Because the first, second, third, fourth, and intermediate ring-shaped portions extend between the front end and the axial rear end face, coolant can be supplied to and returned from a portion of the outer mantle surface without interfering with the cutting process or chip evacuation, and without limiting the possibility of mounting the milling tool body in a standardized manner, either directly on the machine or via a tool holder. Special tool holders are not required, and the same tool holder can be used for tools with different numbers of cutting inserts.

[0020] The first ring-shaped portion is adjacent to the third ring-shaped portion on one axial side and adjacent to the intermediate ring-shaped portion on the other axial side, the second ring-shaped portion is adjacent to the fourth ring-shaped portion on one axial side and adjacent to the intermediate ring-shaped portion on the other axial side, and each of the third, fourth, and intermediate ring-shaped portions of the outer peripheral mantle surface of the milling tool body is a surface of revolution, has a central axis coincident with the first longitudinal central axis of the milling tool body, is a sealing surface, and is arranged to cooperate with the sealing ring arrangement so that coolant can be transmitted to and returned from the coolant duct system without leakage. Such an arrangement also means that the system is insensitive to increases in tool diameter, tool bending, and different numbers of cutting inserts.

[0021] According to one embodiment of the present invention, the at least one coolant inlet is disposed in a first groove in the milling tool body between the third ring-shaped portion and the intermediate ring-shaped portion, the first groove preferably being a first annular groove; and / or The at least one coolant outlet is disposed in a second groove in the milling tool body disposed between the fourth ring-shaped portion and the intermediate ring-shaped portion, the second groove preferably being a second annular groove. This can increase the flow of coolant in a first annular coolant channel formed between the first ring-shaped portion of the outer peripheral mantle surface and the first ring-shaped portion of the inner peripheral surface of the coolant ring, thereby increasing the volume of the first annular coolant channel, and / or can increase the flow of coolant in a second annular channel formed between the second ring-shaped portion of the outer peripheral mantle surface and the second ring-shaped portion of the inner peripheral surface of the coolant ring, thereby increasing the volume of the second annular coolant channel. This also facilitates manufacturing of the coolant ring.

[0022] According to another embodiment of the invention, the coolant duct system extends partially within the front end of the milling tool body and intersects a first plane, preferably perpendicular to the first longitudinal axis of rotation, with each chip pocket in front of each of the at least two insert seats and / or with each of the at least two insert seats, thereby achieving more efficient cooling of the front end of the milling tool body.

[0023] According to a further embodiment of the present invention, the third, fourth, and intermediate ring-shaped portions of the outer peripheral mantle surface of the milling tool body are each cylindrical and have substantially the same diameter. This arrangement makes it easier to manufacture the milling tool body and to achieve the concentricity and tolerance requirements of the third, fourth, and intermediate ring-shaped portions of the outer peripheral mantle surface of the milling tool body. The third, fourth, and intermediate ring-shaped portions are substantially arranged on a first common imaginary cylinder, i.e., the third, fourth, and intermediate ring-shaped portions are arranged on the first common imaginary cylinder within the tolerance. Preferably, the milling tool body is further arranged such that the first common imaginary cylinder completely surrounds the milling tool body in a region from the axial rear end surface to one of the third and fourth ring-shaped portions, which is arranged farther from the axial rear end surface than the other of the third and fourth ring-shaped portions. Therefore, no part of the milling tool body protrudes radially outward from the first common imaginary cylinder in a region from the axial rear end face to one of the third and fourth ring-shaped portions, which is located farther from the axial rear end face than the other of the third and fourth ring-shaped portions. This allows the coolant ring to be formed integrally and easily attached to the milling tool body. Alternatively or additionally, the first common imaginary cylinder may completely surround the milling tool body in a region from the axial front end face to one of the third and fourth ring-shaped portions, which is located farther from the axial front end face than the other of the third and fourth ring-shaped portions.

[0024] According to another embodiment of the present invention, the at least one coolant inlet is a plurality of coolant inlets, the at least one coolant outlet is a plurality of coolant outlets, and the coolant duct system comprises a plurality of coolant channels. Each coolant channel of the plurality of coolant channels extends from a single coolant inlet of the plurality of coolant inlets to a single coolant outlet of the plurality of coolant outlets. The coolant inlets of the plurality of coolant inlets are preferably uniformly or preferably substantially uniformly distributed in the circumferential direction of the milling tool body. The coolant outlets of the plurality of coolant outlets are preferably uniformly or preferably substantially uniformly distributed in the circumferential direction of the milling tool body. The coolant channels of the plurality of coolant channels are preferably uniformly or preferably substantially uniformly distributed in the circumferential direction of the milling tool body. The number of coolant channels in the plurality of coolant channels may be equal to the number of at least two insert seats. In an alternative embodiment, the number of coolant channels in the plurality of coolant channels is equal to half the number of at least two insert seats.

[0025] According to a second aspect of the present invention, the above-mentioned object is achieved by a milling tool comprising a milling tool body according to the first aspect of the present invention, the milling tool further comprising: a coolant ring having an outer circumferential surface and an inner circumferential surface, the inner circumferential surface comprising a first ring-shaped portion, a second ring-shaped portion, a third ring-shaped portion, a fourth ring-shaped portion, and an intermediate ring-shaped portion, each of the third ring-shaped portion, the fourth ring-shaped portion, and the intermediate ring-shaped portion being a surface of revolution generated by a 360° rotation of a curved or straight line about a common second longitudinal central axis, the third ring-shaped portion, the fourth ring-shaped portion, and the intermediate ring-shaped portion being arranged to be a sealing surface and to cooperate with a sealing ring arrangement; a coolant ring attached to the milling tool body such that an inner peripheral surface of the coolant ring surrounds an outer peripheral mantle surface of the milling tool body, and such that a first ring-shaped portion, a second ring-shaped portion, a third ring-shaped portion, a fourth ring-shaped portion, and an intermediate ring-shaped portion of the inner peripheral surface of the coolant ring face the first ring-shaped portion, the second ring-shaped portion, the third ring-shaped portion, the fourth ring-shaped portion, and an intermediate ring-shaped portion of the outer peripheral mantle surface of the milling tool body, respectively; a first seal ring arrangement mounted between and arranged to cooperate with a third ring-shaped portion of the outer peripheral mantle surface of the tool body and a third ring-shaped portion of the inner peripheral surface of the coolant ring; a second seal ring arrangement mounted between and arranged to cooperate with the fourth ring-shaped portion of the outer circumferential mantle surface of the tool body and the fourth ring-shaped portion of the inner circumferential surface of the coolant ring; a third seal ring arrangement mounted between and cooperatively arranged to couple with an intermediate ring-shaped portion of the outer circumferential mantle surface of the tool body and an intermediate ring-shaped portion of the inner circumferential surface of the coolant ring; The coolant ring, the first seal ring arrangement, the second seal ring arrangement, and the third seal ring arrangement, when mounted on the tool body, the second central longitudinal axis is substantially coincident with the first central longitudinal axis; a first annular coolant channel formed between a first ring-shaped portion of the outer circumferential mantle surface and a first ring-shaped portion of the inner circumferential surface of the coolant ring and axially sealed by the first seal ring arrangement and the third seal ring arrangement; a second annular coolant channel is formed between a second ring-shaped portion of the outer circumferential mantle surface and a second ring-shaped portion of the inner circumferential surface of the coolant ring and is axially sealed by the second seal ring arrangement and the third seal ring arrangement; The milling tool body is arranged to be rotatable relative to the coolant ring; The coolant ring comprises at least one coolant transmission channel arranged to communicate with the first annular channel, and the coolant ring further comprises at least one coolant return channel arranged to communicate with the second annular coolant channel, each of the at least one coolant transmission channel extending from a coolant inlet at the outer periphery of the coolant ring to an orifice in the first ring-shaped portion of the inner circumferential surface of the coolant ring, and each of the at least one coolant return channel extending from an orifice in the second ring-shaped portion of the inner circumferential surface of the coolant ring to a coolant outlet at the outer periphery of the coolant ring.

[0026] The coolant ring includes a fastening means for fastening the coolant ring to the exterior of the machine when the milling tool is attached to the machine to prevent movement and rotation of the coolant ring. Thus, the coolant ring is a stationary coolant ring when the tool is attached to the machine and when the coolant ring is fastened to the exterior of the machine via the fastening means of the coolant ring, and the milling tool body can rotate inside the coolant ring when torque from the machine is applied.

[0027] The second central longitudinal axis is a common central longitudinal axis of the third ring-shaped portion, the fourth ring-shaped portion and the middle ring-shaped portion of the inner circumferential surface of the coolant ring.

[0028] The third, fourth, and intermediate ring-shaped portions of the inner circumferential surface of the coolant ring preferably have mirror symmetry with respect to a plane perpendicular to the second longitudinal central axis. This arrangement of the third, fourth, and intermediate ring-shaped portions of the inner circumferential surface of the coolant ring reduces the risk of associated seal ring configurations shifting during use of the milling tool. More preferably, the third, fourth, and intermediate ring-shaped portions of the inner circumferential surface of the coolant ring are cylindrical and have a central axis that coincides with the second longitudinal central axis. The inventors have observed that this arrangement of the third, fourth, and intermediate ring-shaped portions of the inner circumferential surface of the coolant ring provides optimal results in terms of the service life of the seal ring configurations and simplifies the manufacture of the coolant rings.

[0029] Each of the third ring-shaped portion, the fourth ring-shaped portion, and the intermediate ring-shaped portion of the inner peripheral surface of the coolant ring, when intended to be a dynamic sealing surface, preferably has a surface characteristic 0.05≦Ra≦0.20μm, 0.40≦Rz≦1.60μm, 0.63≦Rmax≦2.50 μm, If it is intended to be a static sealing surface, Ra≦1.60 μm, Rz≦10.00μm, Rmax≦16.00 μm.

[0030] The first seal ring arrangement is mounted between and arranged to cooperate with the third ring-shaped portion of the outer peripheral mantle surface of the tool body and the third ring-shaped portion of the inner peripheral surface of the coolant ring, wherein one of the third ring-shaped portion of the outer peripheral mantle surface of the tool body and the third ring-shaped portion of the inner peripheral surface of the coolant ring is preferably a static seal surface and the other is a dynamic seal surface.

[0031] The second seal ring arrangement is mounted between and arranged to cooperate with the fourth ring-shaped portion of the outer peripheral mantle surface of the tool body and the fourth ring-shaped portion of the inner peripheral surface of the coolant ring, wherein one of the fourth ring-shaped portion of the outer peripheral mantle surface of the tool body and the fourth ring-shaped portion of the inner peripheral surface of the coolant ring is preferably a static seal surface and the other is a dynamic seal surface.

[0032] The third seal ring arrangement is mounted between and arranged to cooperate with an intermediate ring-shaped portion of the outer peripheral mantle surface of the tool body and an intermediate ring-shaped portion of the inner peripheral surface of the coolant ring, one of which is preferably a static seal surface and the other is a dynamic seal surface.

[0033] Preferably, but not necessarily, the third, fourth and intermediate ring-shaped portions of the inner circumferential surface of the coolant ring are of the same type, i.e., either static or dynamic sealing surfaces.

[0034] Preferably, but not necessarily, the third, fourth and intermediate ring-shaped portions of the outer peripheral mantle surface of the milling tool body are of the same type, i.e., either static or dynamic sealing surfaces, and preferably of a different type compared to the third, fourth and intermediate ring-shaped portions of the inner peripheral surface of the coolant ring.

[0035] According to another embodiment, the coolant ring is disposed with a first annular groove, a second annular groove, and a third annular groove in its inner circumferential surface, the first annular groove, the second annular groove, and the third annular groove being arranged to accommodate the first seal ring arrangement, the second seal ring arrangement, and the third seal ring arrangement, respectively, when the coolant ring, the first seal ring arrangement, the second seal ring arrangement, and the third seal ring arrangement are attached to the tool body. In this manner, tool assembly is facilitated. The first seal ring arrangement, the second seal ring arrangement, and the third seal ring arrangement may be disposed in the first annular groove, the second annular groove, and the third seal ring arrangement, respectively, in the inner circumferential surface of the coolant ring, and the coolant ring, together with the first seal ring arrangement, the second seal ring arrangement, and the third seal ring arrangement, are attached to the milling tool body in a next step. When the first, second, and third seal ring configurations are disposed in the first, second, and third annular grooves, respectively, in the inner circumferential surface of the coolant ring, each of the first, second, and third seal ring configurations protrudes radially inward from its associated annular groove toward the second longitudinal central axis to cooperate with the third, fourth, and intermediate ring-shaped portions, respectively, in the outer circumferential mantle surface of the tool body when the tool is assembled. In this embodiment, each of the first, second, and third annular grooves in the inner circumferential surface of the coolant ring has a bottom wall and two side walls. At least a portion of the bottom wall of the first annular groove constitutes the third ring-shaped portion in the inner circumferential surface of the coolant ring. At least a portion of the bottom wall of the second annular groove constitutes the fourth ring-shaped portion in the inner circumferential surface of the coolant ring. At least a portion of the bottom wall of the third annular groove defines an intermediate ring-shaped portion of the inner circumferential surface of the coolant ring. Each of the third ring-shaped portion, the fourth ring-shaped portion, and the intermediate ring-shaped portion of the inner circumferential surface of the coolant ring preferably has a surface characteristic Ra≦1.60 μm, Rz≦10.00μm, Rmax≦16.00 μm, The side walls of each of the first, second, and third annular grooves in the inner circumferential surface of the coolant ring also preferably have these surface characteristics. The bottom walls of each of the first, second, and third annular grooves in the inner circumferential surface of the coolant ring also preferably have these surface characteristics. The third, fourth, and intermediate ring-shaped portions of the outer circumferential mantle surface of the tool body each preferably have the surface characteristics. 0.05≦Ra≦0.20μm, 0.40≦Rz≦1.60μm, 0.63≦Rmax≦2.50 μm, It is intended to be a dynamic sealing surface. In this embodiment, each of the first, second, and third seal ring arrangements is static, just like the coolant ring when the milling tool is in use.

[0036] In an alternative embodiment, the milling tool body is configured with a third annular groove, a fourth annular groove, and a fifth annular groove in the outer peripheral mantle surface, the third annular groove, the fourth annular groove, and the fifth annular groove in the outer peripheral mantle surface of the milling tool body being arranged to accommodate the first seal ring arrangement, the second seal ring arrangement, and the third seal ring arrangement, respectively, when the coolant ring, the first seal ring arrangement, the second seal ring arrangement, and the third seal ring arrangement are attached to the tool body. In this manner, tool assembly is facilitated. The first seal ring arrangement, the second seal ring arrangement, and the third seal ring arrangement can be disposed in the third annular groove, the fourth annular groove, and the fifth annular groove, respectively, in the outer peripheral mantle surface of the milling tool body, and in a subsequent step, the coolant ring is disposed on the milling tool body to which the first, second, and third coolant ring arrangements are already attached. When the first, second, and third seal ring configurations are disposed in the third, fourth, and fifth annular grooves, respectively, in the outer circumferential mantle surface of the milling tool body, each of the first, second, and third seal ring configurations protrudes radially outward from its associated annular groove in the outer circumferential mantle surface of the milling tool body, away from the first longitudinal axis of the milling tool body, to contact and cooperate with the third, fourth, and middle ring-shaped portions, respectively, in the inner circumferential surface of the coolant ring when the tool is assembled. In this embodiment, each of the third, fourth, and fifth annular grooves in the outer circumferential mantle surface of the milling tool body has a bottom wall and two side walls. At least a portion of the bottom wall of the third annular groove constitutes the third ring-shaped portion in the outer circumferential mantle surface of the milling tool body. At least a portion of the bottom wall of the second annular groove constitutes a fourth ring-shaped portion of the outer peripheral mantle surface of the milling tool body. At least a portion of the bottom wall of the third annular groove constitutes an intermediate ring-shaped portion of the outer peripheral mantle surface of the milling tool body. Each of the third ring-shaped portion, the fourth ring-shaped portion, and the intermediate ring-shaped portion of the outer peripheral mantle surface of the milling tool body preferably has a surface characteristic Ra≦1.60 μm, Rz≦10.00μm, Rmax≦16.00 μm, The third, fourth, and fifth annular side walls in the outer peripheral mantle surface of the milling tool body also preferably have these surface characteristics. The entire bottom walls of the third, fourth, and fifth annular sections in the outer peripheral mantle surface of the milling tool body also preferably have these surface characteristics. Each of the third, fourth, and intermediate ring-shaped portions of the inner peripheral surface of the coolant ring preferably have the surface characteristics. 0.05≦Ra≦0.20μm, 0.40≦Rz≦1.60μm, 0.63≦Rmax≦2.50 μm, It is intended to be a dynamic seal surface. In this embodiment, each of the first seal ring, second seal ring, and third seal ring arrangements rotates with the milling tool body when the milling tool is in use.

[0037] According to another embodiment, each of the first seal ring arrangement, the second seal ring arrangement, and the third seal ring arrangement includes a first seal ring and a second seal ring, and the first and second seal rings of each of the first, second, and third seal ring arrangements are concentric with one another such that, when the coolant ring, the first seal ring arrangement, the second seal ring arrangement, and the third seal ring arrangement are mounted on the milling tool body, one of the first and second seal rings has a smaller diameter and is positioned radially inward from the other and closer to the first longitudinal central axis.

[0038] According to a further embodiment, the first seal ring of each of the first, second and third seal ring configurations is made of a hard plastic, preferably polytetrafluoroethylene PTFE, and the second seal ring of each of the first, second and third seal ring configurations is made of an elastomer, preferably fluorinated propylene monomer FPM.

[0039] According to a further embodiment of the milling tool, the coolant ring is arranged with first, second and third annular grooves in its inner circumferential surface, the first, second and third annular grooves being arranged to accommodate the first, second and third seal ring arrangements, respectively, when the coolant ring, the first, second and third seal ring arrangements are mounted on the tool body, and the first and second seal rings of each of the first, second and third seal ring arrangements have a smaller diameter than the second seal ring and are arranged to contact and cooperate with an outer circumferential mantle surface of the milling tool body when the coolant ring, the first, second and third seal ring arrangements are mounted on the tool body. The first seal ring of each of the first, second and third seal rings is made of a hard plastic, preferably polytetrafluoroethylene PTFE, and the second seal ring of each of the first, second and third seal rings is made of an elastomer, preferably fluorinated propylene monomer FPM.

[0040] When the milling tool is assembled, the first and second seal rings of the first seal ring arrangement are received in a first annular groove in the inner circumferential surface of the coolant ring such that the second seal ring is sandwiched between the bottom wall of the first annular groove of the coolant ring and the first seal ring. The first seal ring protrudes radially inward from the first annular groove toward the second longitudinal axis and cooperates with a third ring-shaped portion of the outer circumferential mantle surface of the tool body. The first seal ring is sandwiched between the second seal ring and the third ring-shaped portion of the outer circumferential mantle surface of the tool body. The second seal ring is compressed by the first seal ring during assembly of the milling tool and applies a bias to the first seal ring when the milling tool is assembled.

[0041] When the milling tool is assembled, the first and second seal rings of the second seal ring arrangement are received in a second annular groove in the inner circumferential surface of the coolant ring such that the second seal ring is sandwiched between the bottom wall of the second annular groove of the coolant ring and the first seal ring. The first seal ring protrudes radially inward from the second annular groove toward the second longitudinal axis and cooperates with a fourth ring-shaped portion of the outer circumferential mantle surface of the tool body. The first seal ring is sandwiched between the second seal ring and the fourth ring-shaped portion of the outer circumferential mantle surface of the tool body. The second seal ring is compressed by the first seal ring during assembly of the milling tool and applies a bias to the first seal ring when the milling tool is assembled.

[0042] When the milling tool is assembled, the first and second seal rings of the third seal ring arrangement are received in a third annular groove in the inner circumferential surface of the coolant ring such that the second seal ring is sandwiched between the bottom wall of the third annular groove of the coolant ring and the first seal ring. The first seal ring protrudes radially inward from the third annular groove toward the second longitudinal axis and cooperates with an intermediate ring-shaped portion of the outer circumferential mantle surface of the tool body. The first seal ring is sandwiched between the second seal ring and the intermediate ring-shaped portion of the outer circumferential mantle surface of the tool body. The second seal ring is compressed by the first seal ring during assembly of the milling tool and applies a bias to the first seal ring when the milling tool is assembled.

[0043] In this way, tool assembly is facilitated and the seal ring configurations have a long service life. The second rings of the first, second, and third seal ring configurations are made of elastomer and may be compressed during installation. Furthermore, the first seal rings of the first, second, and third seal ring configurations are made of hard plastic, preferably polytetrafluoroethylene (PTFE), which has good durability and low friction.

[0044] Regarding the service life and coolant pressure that the first seal ring configuration, the second seal ring configuration, and the third seal ring configuration can withstand, when the first seal ring of each of the first seal ring configuration, the second seal ring configuration, and the third seal ring configuration is made of hard plastic, particularly polytetrafluoroethylene PTFE, when the second seal ring of each of the first seal ring configuration, the second seal ring configuration, and the third seal ring configuration is made of elastomer, particularly fluorinated propylene monomer FPM, and when the first seal ring of each of the first seal ring configuration, the second seal ring configuration, and the third seal ring configuration has surface characteristics 0.05≦Ra≦0.20μm, 0.40≦Rz≦1.60μm, When cooperating with a dynamic sealing surface having 0.63≦Rmax≦2.50 μm, and wherein the second seal ring of each of the first, second, and third seal ring configurations has a surface characteristic Ra≦1.60 μm, Rz≦10.00μm, It has been observed that best performance is achieved when working with a static seal face having an Rmax≦16.00 μm.

[0045] When assembling the milling tool, the first seal ring arrangement, the second seal ring arrangement, and the third seal ring arrangement may be disposed in the first annular groove, the second annular groove, and the third annular groove, respectively, in the inner peripheral surface of the coolant ring, and the coolant ring together with the first seal ring arrangement, the second seal ring arrangement, and the third seal ring arrangement may be disposed on the milling tool body in the next step. Between these two steps, the first seal ring of one or two or each of the first seal ring arrangement, the second seal ring arrangement, and the third seal ring arrangement may be machined, i.e., adjusted to have a predetermined inner diameter.

[0046] According to another embodiment of the present invention, a milling tool body is arranged with third, fourth, and fifth annular grooves in the outer peripheral mantle surface, the third, fourth, and fifth annular grooves being arranged to accommodate the first, second, and third seal ring configurations, respectively, when the coolant ring, the first, second, and third seal ring configurations are mounted on the tool body, and the first and second seal rings of each of the first, second, and third seal ring configurations are arranged such that the first seal ring has a larger diameter than the second seal ring and is in contact with and cooperates with an inner peripheral surface of the coolant ring when the coolant ring, the first, second, and third seal ring configurations are mounted on the tool body.

[0047] When the milling tool is assembled, the first and second seal rings of the first seal ring arrangement are received in a third annular groove in the milling tool body such that the second seal ring is sandwiched between the bottom wall of the third annular groove and the first seal ring. The first seal ring protrudes from the third annular groove radially outward from the first longitudinal axis and cooperates with a third ring-shaped portion of the inner circumferential surface of the coolant ring. The first seal ring is sandwiched between the second seal ring and the third ring-shaped portion of the inner circumferential surface of the coolant ring. The second seal ring is compressed by the first seal ring during assembly of the milling tool, applying a bias to the first seal ring when the milling tool is assembled.

[0048] When the milling tool is assembled, the first and second seal rings of the second seal ring arrangement are received in a fourth annular groove in the milling tool body such that the second seal ring is sandwiched between the bottom wall of the fourth annular groove and the first seal ring. The first seal ring protrudes from the fourth annular groove in the milling tool body radially outward from the first longitudinal axis and cooperates with a fourth ring-shaped portion of the inner circumferential surface of the coolant ring. The first seal ring is sandwiched between the second seal ring and the fourth ring-shaped portion of the inner circumferential surface of the coolant ring. The second seal ring is compressed by the first seal ring during assembly of the milling tool and applies a bias to the first seal ring when the milling tool is assembled.

[0049] When the milling tool is assembled, the first and second seal rings of the third seal ring arrangement are received in a fifth annular groove in the milling tool body such that the second seal ring is sandwiched between the bottom wall of the fifth annular groove and the first seal ring. The first seal ring protrudes radially outward from the fifth annular groove of the milling tool body from the first longitudinal axis and cooperates with an intermediate ring-shaped portion of the inner circumferential surface of the coolant ring. The first seal ring is sandwiched between the second seal ring and the intermediate ring-shaped portion of the inner circumferential surface of the coolant ring. The second seal ring is compressed by the first seal ring during assembly of the milling tool, applying a bias to the first seal ring when the milling tool is assembled.

[0050] In this way, tool assembly is facilitated and the seal ring configurations have a long service life. The second rings of each of the first, second, and third seal ring configurations are made of elastomer and may be compressed during installation. Furthermore, the first seal rings of each of the first, second, and third seal ring configurations are made of hard plastic, preferably polytetrafluoroethylene (PTFE), which has good durability and low friction.

[0051] When assembling the milling tool, the first seal ring arrangement, the second seal ring arrangement, and the third seal ring arrangement may be disposed in the third annular groove, the fourth annular groove, and the fifth annular groove, respectively, on the outer peripheral mantle surface of the milling tool body. The coolant ring is disposed on the milling tool body in the next step. Between these two steps, the first seal ring of one or two or each of the first seal ring arrangement, the second seal ring arrangement, and the third seal ring arrangement may be machined, i.e., adjusted to have a predetermined outer diameter.

[0052] According to another embodiment of the present invention, the coolant ring includes an annular surface at an axial end of the coolant ring, the annular surface being positioned to abut against an annular surface on the milling tool body to facilitate correct longitudinal, i.e., axial, mounting of the coolant ring on the milling tool body when the coolant ring, first seal ring arrangement, second seal ring arrangement, and third seal ring arrangement are mounted on the tool body. The annular surface on the milling tool body has a center point substantially located on the first longitudinal central axis, and the annular surface on the coolant ring has a center point substantially located on the second longitudinal central axis. The annular surface of the coolant ring may be an axial end surface of the coolant ring. The annular surface may also be a surface on a flange on the coolant ring.

[0053] According to one embodiment, the coolant ring, the first seal ring arrangement, the second seal ring arrangement, and the third seal ring arrangement are positioned such that the coolant ring is centered relative to the milling tool body by the first seal ring arrangement, the second seal ring arrangement, and the third seal ring arrangement, such that when the coolant ring, the first seal ring arrangement, the second seal ring arrangement, and the third seal ring arrangement are attached to the tool body, the second central longitudinal axis is substantially aligned with the first central longitudinal axis. This simplifies the design of the milling tool body and the coolant ring. In this manner, each of the first seal ring arrangement, the second seal ring arrangement, and the third seal ring arrangement is more uniformly compressed between the milling tool body and the coolant ring within each angular segment of the milling tool body.

[0054] According to a further embodiment, when the coolant ring, the first seal ring arrangement, the second seal ring arrangement, and the third seal ring arrangement are attached to the tool body, the first seal ring arrangement, the second seal ring arrangement, and the third seal ring arrangement provide a bearing function between the coolant ring and the milling tool body during rotational movement of the milling tool body inside the coolant ring. This simplifies the design of the milling tool body and the coolant ring. Because no additional bearings are required, the coolant ring and the milling tool body can be given a more compact design and shorter length.

[0055] According to one embodiment, the coolant ring has a lower density than the milling tool body.

[0056] According to a third aspect of the present invention, the above object is achieved by a system for transmitting a coolant, the system comprising a milling tool connected to the system according to the present invention, the system further comprising a coolant transmission unit connected to the milling tool via a coolant inlet of at least one coolant transmission channel, and the system comprises a coolant return unit connected to the milling tool via a coolant outlet of at least one coolant return channel.

[0057] Hereinafter, with reference to the accompanying drawings, embodiments of the present invention given as examples will be specifically described.

Brief Description of the Drawings

[0058] [Figure 1a] It is a perspective view of a milling tool from different directions according to an embodiment of the present invention. [Figure 1b] It is a perspective view of a milling tool from different directions according to an embodiment of the present invention. [Figure 2] It is a side view of the milling tools of FIGS. 1a and 1b. [Figure 3] It is an exploded side view of the milling tools of FIGS. 1a and 1b with a cross-sectional view of the coolant ring. [Figure 4a] It is an exploded perspective view of the milling tool of FIG. 1a from different directions. [Figure 4b] It is an exploded perspective view of the milling tool of FIG. 1b from different directions. [Figure 5] It is a side view of the milling tools of FIGS. 1a and 1b. [Figure 5a] It is a sectional view taken along line Va-Va of FIG. 5. [Figure 5b] It is a sectional view taken along line Vb-Vb of FIG. 5. [Figure 5c] It is a sectional view taken along line Vc-Vc of FIG. 5. [Figure 6] It is a plan view of the milling tools of FIGS. 1a and 1b. [Figure 6a] It is a sectional view taken along line VIa-VIa of FIG. 6. [Figure 6b] It is a sectional view taken along line VIb-VIb of FIG. 6. [Figure 7] It is an enlarged partial view of the cut portion of FIG. 6b. [Figure 8] It is an exploded view of a partial part of FIG. 7. [Figure 9] It is a detailed enlarged view of a part of FIG. 1b, in which a cartridge, a cutting insert, and a wedge for fixing the cartridge are shown separated from the milling tool body. [Figure 10] 10 is an exploded view of the cartridge, cutting insert, and wedge for securing the cartridge shown in FIG. 9. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0059] One embodiment of a milling tool 1 according to the present invention is shown in Figures 1-9. Milling tool 1 comprises a milling tool body 2, a coolant ring 58, and three coolant ring arrangements 71, 72, and 73 (Figure 3). Figures 3-4 show milling tool 1 when milling tool body 2, coolant ring 58, and three coolant ring arrangements 71, 72, and 73 are separated from one another, while Figures 1-2 show milling tool 1 when assembled. Figures 6-7 show the relative positions of milling tool body 2, coolant ring 58, and three coolant ring arrangements 71, 72, and 73 when the milling tool is assembled.

[0060] The milling tool body 2 has an axially leading end face 3, an axially trailing end face 4 opposite the axially leading end face 3, an outer peripheral mantle surface 10 extending between the axially leading end face 3 and the axially trailing end face 4, and a first longitudinal central axis C1 extending between the axially leading end face 3 and the axially trailing end face 4. The milling tool body 2 is rotatable about the axis C1 in a rotational direction R. The first longitudinal central axis C1 is also the rotational axis of the milling tool body 2, and the rotational direction R is also the intended rotational direction of the milling tool body 2 when the milling tool 1 is in use.

[0061] The milling tool body has a front end 2a and a rear end 2b. The front end 2a extends from an axial front face 3 toward an axial rear end face 4. The rear end 2b extends from the axial rear end face 4 toward the front end 2a and is configured to mount the milling tool 1 to a rotating spindle of a machine, such as a milling machine, either directly or via an intermediate tool holder. The rear end face 4 is a plane that abuts the rotating spindle, or possibly an intermediate tool holder if the milling tool is mounted to the spindle via a tool holder, and determines the axial position of the milling tool relative to the machine. The rear end face 4 is perpendicular to the first longitudinal axis C1.

[0062] In the illustrated example, the milling tool body 2 is provided with a drive slot 5 or keyway 5 recessed relative to the rear end face 4, as best seen in FIGS. 1a and 4a. The drive slot 5 is arranged to cooperate with a corresponding drive key of the spindle or a corresponding drive key of the tool holder to transmit torque from the machine to the milling tool body 2. The milling tool body includes a central cylindrical through-hole 6. The central through-hole 6 cooperates with a cylindrical shaft portion of the spindle or tool holder to center the milling tool body relative to the spindle. The milling tool 1 is fastened to the spindle by screws (not shown) inserted through the holes 7. The illustrated embodiment has four holes 7 evenly distributed around the first longitudinal central axis C1. The aforementioned screws cooperate with threaded holes in the spindle or tool holder. The milling tool may also be fastened by screws passing through the central through-hole 6, which is more preferable when the milling tool has a smaller diameter.

[0063] The illustrated embodiment has 20 insert seats distributed circumferentially around the milling tool body. Each of these 20 insert seats is configured to receive a cutting insert 21. A chip pocket 22 is provided in front of each of the insert seats 20 in the direction of rotation R and is defined by a chip pocket wall 23 (FIG. 9). The insert seats 20, chip pockets 22, and chip pocket walls 23 are provided over the entire front end 2a of the milling tool body 2. The front end 2a of the milling tool body therefore functions to support the cutting edges arranged on the cutting inserts 21. The front end 2a also serves as a chip ejection area.

[0064] As best seen in FIGS. 9 and 10 , at least each of the insert seats 20 is formed in an exchangeable cartridge 24 that is attached to the milling tool body 2 by a clamping wedge 25 and a clamping screw 26. The clamping screw 26 has dual threads and cooperates with a threaded hole 25a in the cartridge 24 and a threaded hole 27 in the milling tool body 2. Such clamping wedges and clamping screws, and their functions, are known in the art. The cutting insert 21 is fastened within the insert seat 20 by an insert screw 28. The cartridge 24 is axially adjustable within the milling tool body 2 by an adjustment screw 29. Each threaded hole 27 extends through ( FIGS. 6 a-b ).

[0065] The milling tool body 2 is provided with a cooling duct system 50 for cooling the milling tool body 2 and the milling tool 1. The cooling duct system 50 is housed within the milling tool body and extends from the at least one coolant inlet 30 to the at least one coolant outlet 40. The coolant duct system 50 is arranged such that coolant supplied via the at least one coolant inlet 30 flows through the cooling duct system 50 to the at least one coolant outlet 40 without exiting the milling tool body 2 through this path.

[0066] In the illustrated embodiment, the milling tool body 2 comprises ten coolant inlets 30 (FIG. 5 a ) and ten coolant outlets 40 (FIG. 5 b ) evenly distributed around the circumference of the milling tool body 2 .

[0067] As best seen in FIG. 3 , the coolant inlet 30 is disposed in the first ring-shaped portion 11 of the outer peripheral mantle surface 10, and the coolant outlet is disposed in the second ring-shaped portion 12 of the outer peripheral mantle surface 10. The first ring-shaped portion 11 and the second ring-shaped portion 12 are separated from each other by an intermediate ring-shaped portion 15 of the outer peripheral mantle surface 10. The first ring-shaped portion 11 is adjacent to the third ring-shaped portion 13 of the outer peripheral mantle surface 10, such that the first ring-shaped portion 11 is axially located between the intermediate ring-shaped portion 15 and the third ring-shaped portion 13 when viewed in the direction of the first longitudinal central axis C1. The second ring-shaped portion 12 is adjacent to the fourth ring-shaped portion 14 of the outer peripheral mantle surface 10, such that the second ring-shaped portion 12 is axially located between the intermediate ring-shaped portion 15 and the fourth ring-shaped portion 14 when viewed in the direction of the first longitudinal central axis C1. The first, second, third, fourth ring-shaped portions 11 , 12 , 13 , 14 and the intermediate ring-shaped portion 15 extend between the front end 2 a and the axial rear end face 4 .

[0068] The third, fourth, and intermediate ring-shaped portions 13, 14, and 15 of the outer peripheral mantle surface 10 of the milling tool body 2 are each a surface of revolution. More specifically, the third, fourth, and intermediate ring-shaped portions 13, 14, and 15 of the outer peripheral mantle surface 10 of the milling tool body 2 are each a cylindrical surface having a central axis coinciding with the first longitudinal central axis C1 of the milling tool body 2. The third, fourth, and intermediate ring-shaped portions 13, 14, and 15 are also dynamic seal surfaces arranged to cooperate with the first, second, and third seal ring arrangements 71, 72, and 73, respectively. The third, fourth, and intermediate ring-shaped portions 13, 14, and 15 have substantially the same diameter, i.e., the same diameter within manufacturing tolerances, and constitute the radially outermost surface of the milling tool body. The third, fourth, and intermediate ring-shaped portions 13, 14, and 15 can be manufactured by grinding, honing, polishing, lapping, or a similar finishing method.

[0069] The coolant ring 58 includes an outer circumferential surface 59 and an inner circumferential surface 60 , with the inner circumferential surface 60 including first, second, third, fourth and intermediate ring-shaped portions 61 , 62 , 63 , 64 , 65 .

[0070] 7 , when the milling tool 1 is assembled, the inner peripheral surface 60 of the coolant ring 58 surrounds the outer peripheral mantle surface 10 of the milling tool body 2 such that the first, second, third, fourth, and intermediate ring-shaped portions 61, 62, 63, 64, and 65 of the inner peripheral surface 60 of the coolant ring 58 face the first, second, third, fourth, and intermediate ring-shaped portions 11, 12, 13, 14, and 15 of the outer peripheral mantle surface 10 of the milling tool body 2, respectively. Each of the third, fourth, and intermediate ring-shaped portions 63, 64, and 65 of the inner peripheral surface 60 of the coolant ring is a surface of revolution. More specifically, each of the third, fourth, and intermediate ring-shaped portions 63, 64, and 65 of the inner peripheral surface 60 of the coolant ring is a cylindrical surface and has a common central longitudinal axis C2. The third, fourth, and intermediate ring-shaped portions 63, 64, 65 are static sealing surfaces and are arranged to cooperate with the first, second, and third sealing ring arrangements 71, 72, 73, respectively. Another name for each of the first, second, and third sealing ring arrangements 71, 72, 73 is a sealing O-ring arrangement.

[0071] The coolant ring 58 is disposed with first, second, and third annular grooves 66, 67, and 68 in its inner circumferential surface 60. The first, second, and third annular grooves 66, 67, and 68 are disposed to accommodate the first, second, and third seal ring arrangements 71, 72, and 73, respectively, when the coolant ring 58 and the first, second, and third seal ring arrangements 71, 72, and 73 are attached to the tool body 2. In this embodiment, the first, second, and third annular grooves 66, 67, and 68 each have a bottom wall and two side walls. At least a portion of the bottom wall of the first annular groove 66 defines a third ring-shaped portion 63 of the inner circumferential surface of the coolant ring. At least a portion of the bottom wall of the second annular groove 67 defines a fourth ring-shaped portion 64 of the inner circumferential surface of the coolant ring. At least a portion of the bottom wall of the third annular groove 68 defines an intermediate ring-shaped portion 65 of the inner circumferential surface of the coolant ring. Each of the third, fourth, and intermediate ring-shaped portions of the inner circumferential surface of the coolant ring has a surface characteristic Ra≦1.60 μm, Rz≦10.00μm, Rmax≦16.00 μm, Produced by rotation. The third, fourth, and intermediate ring-shaped portions 63, 64, 65 are static sealing surfaces and are arranged to cooperate with the first, second, and third seal ring arrangements 71, 72, 73, respectively. The side walls of each of the first, second, and third annular grooves 66, 67, 68 in the inner circumferential surface of the coolant ring also preferably have these surface characteristics. Each of the third, fourth, and intermediate ring-shaped portions of the outer circumferential mantle surface of the tool body preferably have the surface characteristics 0.05≦Ra≦0.20μm, 0.40≦Rz≦1.60μm, 0.63≦Rmax≦2.50 μm, Dynamic seal surfaces. These surfaces are manufactured by grinding and, if necessary, polishing. Each of the first, second, and third seal ring configurations is static, as is the coolant ring.

[0072] The first seal ring arrangement 71 is arranged to contact and cooperate with the third ring-shaped portion 13 of the outer circumferential mantle surface 10 of the tool body 2 and the third ring-shaped portion 63 of the inner circumferential surface 60 of the coolant ring 58. When the milling tool 1 is assembled, the first seal ring arrangement 71 (FIGS. 7-8) is located between and compressed between the third ring-shaped portion 13 of the outer circumferential mantle surface 10 of the tool body 2 and the third ring-shaped portion 63 of the inner circumferential surface 60 of the coolant ring 58.

[0073] The second seal ring arrangement 72 is arranged to contact and cooperate with the fourth ring-shaped portion 14 of the outer circumferential mantle surface 10 of the tool body 2 and the fourth ring-shaped portion 64 of the inner circumferential surface 60 of the coolant ring 58. When the milling tool 1 is assembled, the second seal ring arrangement 72 is located between and compressed between the fourth ring-shaped portion 14 of the outer circumferential mantle surface 10 of the tool body 2 and the fourth ring-shaped portion 64 of the inner circumferential surface 60 of the coolant ring 58.

[0074] The third seal ring arrangement 73 is arranged to contact and cooperate with the intermediate ring-shaped portion 15 of the outer circumferential mantle surface 10 of the tool body 2 and the intermediate ring-shaped portion 65 of the inner circumferential surface 65 of the coolant ring 58. When the milling tool 1 is assembled, the third seal ring arrangement 73 is located between and compressed between the intermediate ring-shaped portion 15 of the outer circumferential mantle surface 10 of the tool body 2 and the intermediate ring-shaped portion 65 of the inner circumferential surface 65 of the coolant ring 58.

[0075] When the milling tool 1 is assembled, the second longitudinal central axis C2 substantially coincides with the first longitudinal central axis C1, i.e., coincides within manufacturing tolerances. Furthermore, a first annular coolant channel 81 is formed between the first ring-shaped portion 11 of the outer peripheral mantle surface 10 and the first ring-shaped portion 61 of the inner peripheral surface 60 of the coolant ring 58 ( FIG. 6 a). The first coolant channel 81 is axially sealed by the first seal ring arrangement 71 and the third seal ring arrangement 73. A second annular coolant channel 82 is formed between the second ring-shaped portion 12 of the outer peripheral mantle surface 10 and the second ring-shaped portion 62 of the inner peripheral surface 60 of the coolant ring 58. The second annular coolant channel 82 is axially sealed by the second seal ring arrangement 72 and the third seal ring arrangement 73.

[0076] The coolant ring 58 is provided with at least one coolant transmission channel 91 arranged to communicate with the first annular channel 81, and the coolant ring 58 is further provided with at least one coolant return channel 92 arranged to communicate with the second annular coolant channel 82 (FIG. 6a). The illustrated example has three coolant transmission channels 91 (FIG. 5a) and three coolant return channels 92 (FIG. 5b). If the coolant transmission channel 91 is not intended to be used for coolant transmission, it may be blocked by a plug 91a. If the coolant return channel 92 is not intended to be used for coolant return, it may be blocked by a plug 92a.

[0077] Each of the coolant transmission channels 91 extends from a coolant inlet 93 in the outer peripheral surface 59 of the coolant ring 58 to an orifice 94 in the first ring-shaped portion 61 of the inner peripheral surface 60 of the coolant ring 58. Each of the coolant return channels 92 extends from an orifice 95 in the second ring-shaped portion 62 of the inner peripheral surface 60 of the coolant ring 58 to a coolant outlet 96 in the outer peripheral surface 59 of the coolant ring 58. In the illustrated example, the coolant inlet 93 and the coolant outlet 96 are provided at the radial outer periphery of the coolant ring.

[0078] The coolant ring includes fastening means 97 for fastening the coolant ring 58 to the exterior of the machine, for example via an intermediate mount, when the milling tool 1 is mounted on the machine, to prevent movement and rotation of the coolant ring 58 during use of the milling tool 1. When the milling tool 1 is mounted on the machine and the coolant ring 58 is fastened to the exterior of the machine, the milling tool body 2 is rotatable relative to the coolant ring 58.

[0079] The coolant transfer channels 91 and their respective coolant inlets 93 are arranged to connect a coolant transfer unit, such as a pump, to the coolant ring 58. The coolant return channels 92 and their respective coolant outlets 96 are arranged to connect a coolant return unit to the coolant ring 58. Preferably, but not necessarily, the coolant transfer unit, the coolant return unit, and the milling tool 2 can form a closed coolant system.

[0080] Therefore, once the milling tool 1 is mounted on the machine, the next step is to secure the coolant ring 58 to the outside of the machine and connect the coolant transmission and return units to the coolant ring 58. When torque is applied, the milling tool body rotates inside the coolant ring. Coolant is supplied to the milling tool through at least one coolant transmission channel 91 and enters the first annular coolant channel 81 formed between the coolant ring 58 and the milling tool body 2. The coolant enters the milling tool body 2 through at least one coolant inlet 30, flows through the cooling duct system 50 to at least one coolant outlet 40, and then to the second annular channel 82. Finally, it exits the second annular channel 82 through at least one coolant return channel 92 connected to the coolant return unit. The third seal ring arrangement 73 prevents coolant leakage between the first annular coolant channel 81 and the second annular coolant channel 82. The first annular seal ring arrangement 71 prevents leakage of coolant from the first annular coolant channel 81 to the environment, and the second seal ring arrangement 72 prevents leakage of coolant from the second annular coolant channel 82 to the environment, resulting in continuous cooling of the milling tool body and the milling tool.

[0081] In the illustrated embodiment, the at least one coolant inlet 30 is arranged in a first groove 31 in the milling tool body 2. The first groove 31 is an annular groove. The first groove 31 is arranged between the third ring-shaped portion 13 and the intermediate portion 15. The first ring-shaped portion 11 of the outer peripheral mantle surface 10 of the milling tool body 2 is therefore at least partially the radial bottom surface of the first groove 31. In this way, the first annular channel 81 is provided with a larger volume, improving the coolant flow. The first groove 31 is a preferred but not essential feature. Alternatively, or as a supplement, the coolant ring 58 may be provided with a groove in the region of the first ring-shaped portion 61 of the inner peripheral surface 60 of the coolant ring 58, and each of the at least one coolant transmission channel 91 has an orifice 94 arranged in the groove in the inner peripheral surface 60 of the coolant ring 58. However, since the first ring-shaped portion 61 of the inner peripheral surface 60 of the coolant ring 58 is given a larger diameter than the first ring-shaped portion 11 of the outer peripheral mantle surface 10 of the milling tool body 2, the first annular channel 81 may be made without a groove in either the milling tool body 2 or the coolant ring 58.

[0082] In the illustrated embodiment, the at least one coolant outlet 40 is arranged in a second groove 41 of the milling tool body 2. The second groove 41 is an annular groove (FIG. 3). The second groove 41 is arranged between the fourth ring-shaped portion 14 and the intermediate portion 15. The second ring-shaped portion 12 of the outer peripheral mantle surface 10 of the milling tool body 2 is therefore at least partially the radial bottom surface of the second groove 41. In this way, the second annular channel 82 is given a larger volume, improving the coolant flow. The second groove 41 is a preferred but not essential feature. Alternatively, or as a supplement, the coolant ring 58 may be provided with a groove in the region of the second ring-shaped portion 62 of the inner peripheral surface 60 of the coolant ring 58, so that each of the at least one coolant return channels 92 has an orifice 95 arranged in the aforementioned groove in the inner peripheral surface 60 of the coolant ring 58. However, since the second ring-shaped portion 62 of the inner peripheral surface 60 of the coolant ring 58 is given a larger diameter than the second ring-shaped portion 12 of the outer peripheral mantle surface 10 of the milling tool body 2, the second annular channel 82 may be made without a groove in either the milling tool body 2 or the coolant ring 58.

[0083] 5c and 7, the coolant duct system 50 extends partially within the front end 2a of the milling tool body 2 and intersects a first plane P1 perpendicular to the first longitudinal central axis of rotation C1. The first plane P1 intersects each chip pocket 22 provided in front of each of the at least two insert seats 20. The first plane P1 may also be located closer to the axial front end face 3 so as to intersect each of the at least two insert seats.

[0084] As can be seen in Figure 3, the third, fourth and intermediate ring-shaped portions 13, 14, 15 have substantially the same diameter, i.e., have the same diameter within manufacturing tolerances. This arrangement is beneficial because the third, fourth and intermediate ring-shaped portions 13, 14, 15 can be more easily manufactured to the required tolerances, both in terms of diameter measurement and the surface quality of the third, fourth and intermediate ring-shaped portions 13, 14, 15.

[0085] As described above, the third, fourth, and intermediate ring-shaped portions 13, 14, and 15 are arranged substantially on a first common imaginary cylinder. In the illustrated embodiment, the first common imaginary cylinder completely surrounds the milling tool body 2 in the region from the axial rear end face 4 to the fourth ring-shaped portion 14. Therefore, no part of the milling tool body 2 protrudes radially outward from the first common imaginary cylinder in the region from the axial rear end face 4 to the fourth ring-shaped portion 14. As a result, the coolant ring 58 may be integrally formed and easily attached to the milling tool body in a first step by arranging the coolant ring so that its first axial end face 59 a faces the axial rear end face 4 of the milling tool body 2, and then, in a second step, by arranging the coolant ring 58 on the milling tool body in the direction of the first longitudinal central axis C1 so that the second seal ring arrangement 72 enters the third ring-shaped portion 13 of the milling tool body 2. As the coolant ring is pressed further in the direction of the first central longitudinal axis C1, in a third step, the second seal ring arrangement 72 slides over and passes the third ring-shaped portion 13. As the coolant ring is pressed further in the direction of the first central longitudinal axis C1, in a fourth step, the second seal ring arrangement 72 enters the intermediate ring-shaped portion 15 of the milling tool body 2 and the third seal ring arrangement 73 enters the third ring-shaped portion 13 of the milling tool body. As the coolant ring is pressed further in the direction of the first central longitudinal axis C1, in a fifth step, the second and third seal ring arrangements 72, 73 slide over and pass the intermediate and third ring-shaped portions 15, 13, respectively. In a sixth step, the coolant ring is pressed further in the direction of the first central longitudinal axis C1, so that the first seal ring arrangement 71 enters the third ring-shaped portion 13 of the milling tool body, the third seal ring arrangement 73 enters the intermediate ring-shaped portion 15, and the second seal ring arrangement 72 enters the fourth ring-shaped portion 14 of the milling tool body, until the coolant ring 58 has the correct axial position relative to the milling tool body 2. The coolant ring 58 has an axial end 69 in the form of a flange 69 that facilitates mounting the coolant ring 58 in the correct axial position relative to the milling tool body 2.The flange 69 has an annular surface 69a that abuts the annular surface 8 of the milling tool body 2 when the coolant ring is placed on the milling tool body 2 and has a correct axial position relative to the milling tool body 2. In the illustrated embodiment, the first common imaginary cylinder completely surrounds the milling tool body 2 from the axial front end face 3 to the axial rear end face 4.

[0086] As best seen in FIG. 7 , a first frustoconical transition surface is provided between the third ring-shaped portion 13 of the outer peripheral surface 10 of the milling tool body 2 and the annular surface 8 of the milling tool body 2. The first frustoconical transition surface connects to the third ring-shaped portion 13 via a convex radius-shaped surface having a 1 mm radius of curvature. The first frustoconical transition surface connects to the annular surface 8 via a convex radius-shaped surface having a 1 mm radius of curvature. This facilitates installation of the coolant ring 58 on the milling tool body because the second, third, and fourth seal ring configurations can more easily enter the third ring-shaped portion 13 during the second, fourth, and sixth steps of installing the coolant ring, respectively. This reduces the risk of damaging the third and fourth seal ring configurations during installation. A second frustoconical transition surface is provided between the third ring-shaped portion 13 of the milling tool body and the first annular groove 31. The second frusto-conical transition surface connects to the third ring-shaped portion 13 via a convex radius-shaped surface having a radius of curvature of 1 mm. The second frusto-conical transition surface connects to the first annular groove 31 via a convex radius-shaped surface having a radius of curvature of 1 mm. This reduces the risk of damage to the second and third seal ring arrangements in the third and fifth steps of installing the coolant ring when the second and third seal ring arrangements slide over and over the third ring-shaped portion 13. Similarly, a third frusto-conical transition surface is provided between the intermediate ring-shaped portion 15 of the milling tool body 2 and the first annular groove 31. The third frusto-conical transition surface connects to the first annular groove 31 via a convex radius-shaped surface having a radius of curvature of 1 mm, and the third frusto-conical transition surface connects to the intermediate ring-shaped portion 15 via a convex radius-shaped surface having a radius of curvature of 1 mm. A fourth frusto-conical transition surface is provided between the intermediate ring-shaped portion 15 of the milling tool body 2 and the second annular groove 41. The fourth frusto-conical transition surface connects to the second annular groove 41 via a convex radius shaped surface having a radius of curvature of 1 mm, and the fourth frusto-conical transition surface connects to the intermediate ring-shaped portion 15 via a convex radius shaped surface having a radius of curvature of 1 mm. A fifth frusto-conical transition surface is provided between the fourth ring-shaped portion 14 and the second annular groove 41.The fifth frusto-conical transition surface connects to the second annular groove 41 via a convex radius shaped surface having a radius of curvature of 1 mm, and the fifth frusto-conical transition surface connects to the fourth ring-shaped portion 14 via a convex radius shaped surface having a radius of curvature of 1 mm. Each of the first, second, third, fourth and fifth frusto-conical transition surfaces and associated convex radius shaped surfaces preferably have the same surface characteristics as the third, fourth and intermediate ring-shaped portions 13, 14, 15 and are manufactured in the same way, i.e., by grinding and possibly polishing.

[0087] Each of the first, second, third, fourth and fifth frusto-conical transition surfaces establishes an interior angle with the associated ring-shaped portion of the outer peripheral surface 10 of the milling tool body 2. The interior angle, measured in the material of the milling tool body 2, is between 5 and 25°, preferably between 10 and 20°. Each of the aforementioned convex radius-shaped surfaces can have a radius of curvature having another value different from 1 mm.

[0088] The milling tool body 2 may, for example, be arranged so that the intermediate ring-shaped portion 15 has a larger diameter than the third ring-shaped portion 13, and so that the fourth ring-shaped portion 14 has a larger diameter than the intermediate ring-shaped portion 15. This makes it easier to attach the coolant ring 58 to the milling tool body.

[0089] As seen in FIGS. 5a-5c, the milling tool body 2 has ten coolant inlets 30 and ten coolant outlets 40. The coolant duct system 50 also includes ten coolant channels 51, two of which are visible in FIG. 6b. Each of these ten coolant channels 51 extends from exactly one of the ten coolant inlets 30 to exactly one of the ten coolant outlets 40. Thus, each of these ten coolant channels 51 is an individual channel that does not intersect with any of the other nine coolant channels 51. Each of these ten coolant channels 51 includes a first coolant subchannel 51a that extends slightly radially inward of the milling tool body 2 from the coolant inlet 30 to a second subchannel 51b of the coolant channel 51 (FIG. 5a). The first coolant subchannel 51a in the illustrated embodiment is a straight channel that may be created by drilling. This second coolant subchannel 51b extends from the first coolant subchannel 51a through the milling tool body 2 toward the front end 2a of the milling tool body 2, substantially in the axial direction of the milling tool body 2 (FIG. 6b). The second coolant subchannel 51b is created by drilling the axial rear face of the milling tool body 2, and is plugged by a plug 52 at the axial end of the second coolant subchannel 51b where it intersects the axial rear face. The second coolant subchannel 51b is a straight channel and extends to a third coolant subchannel 51c of the aforementioned coolant channel 51. The third coolant subchannel 51c is created by drilling the axial front end face 3 and extends slightly axially rearward and radially outward within the milling tool body to a fourth coolant subchannel 51d (FIG. 5b). At the end of the third coolant sub-channel 51c that intersects with the axial front face 3, the third coolant sub-channel 51c is blocked by a plug 53. A fourth coolant sub-channel 51d extends from the third coolant sub-channel 51c to the coolant outlet 40.The first, second, third and fourth coolant sub-channels 51 a, 51 b, 51 c, 51 d are in fluid communication with one another, and the second and third coolant sub-channels are blocked by plugs 52, 53, respectively, so that coolant supplied via the coolant inlet 30 flows through the coolant channels 51 to the coolant outlet 40 without exiting the milling tool body 2. The milling tool body 2, or parts thereof, may also be manufactured by additive manufacturing to produce the coolant duct system 50.

[0090] As explained above, the coolant ring 58 is disposed with first, second, and third annular grooves 66, 67, 68 in the coolant ring inner circumferential surface 60. The first, second, and third annular grooves 66, 67, 68 in the coolant ring inner circumferential surface 60 are disposed to accommodate the first, second, and third seal ring arrangements 71, 72, 73, respectively, when the coolant ring 58 and the first, second, and third seal ring arrangements 71, 72, 73 are mounted on the tool body 2. In the illustrated example, the first, second, and third annular grooves 66, 67, 68 in the coolant ring inner circumferential surface 60 have the same diameter and the same width.

[0091] The first seal ring arrangement 71 comprises a first seal ring 71 a, i.e., first seal O-ring 71 a, and a second seal ring 71 b, i.e., second seal O-ring 71 b. In the illustrated example, the aforementioned first seal ring 71 a contacts and cooperates with the third ring-shaped portion 13 of the outer circumferential mantle surface 10 of the milling tool body 2, and the aforementioned second seal ring 71 b contacts and cooperates with the third ring-shaped portion 63 of the inner circumferential surface 60 of the coolant ring 58.

[0092] The second seal ring arrangement 72 comprises a first seal ring 72 a, i.e., first seal O-ring 72 a, and a second seal ring 72 b, i.e., second seal O-ring 72 b. In the illustrated example, the aforementioned first seal ring 72 a contacts and cooperates with the fourth ring-shaped portion 14 of the outer circumferential mantle surface 10 of the milling tool body 2, and the aforementioned second seal ring 72 b contacts and cooperates with the fourth ring-shaped portion 64 of the inner circumferential surface 60 of the coolant ring 58.

[0093] The third seal ring arrangement 73 comprises a first seal ring 73 a, i.e., first seal O-ring 73 a, and a second seal ring 73 b, i.e., second seal O-ring 73 b. In the illustrated example, the said third seal ring 73 a is arranged to contact and cooperate with the intermediate ring-shaped portion 15 of the outer circumferential mantle surface 10 of the milling tool body 2, and the said second seal ring 73 b is arranged to contact and cooperate with the intermediate ring-shaped portion 65 of the inner circumferential surface 60 of the coolant ring 58.

[0094] The first and second seal rings of each of the first, second, and third seal ring configurations 71, 72, and 73 are concentric with one another, with the first seal ring having a smaller diameter than the associated second seal ring. Each of the first seal rings 71a, 72a, and 73a is made of a rigid plastic, more specifically, polytetrafluoroethylene (PTFE). The first seal rings 71a, 72a, and 73a also have substantially the same dimensions, i.e., within manufacturing tolerances. Each of the second seal rings 71b, 72b, and 73b is made of an elastomer, more specifically, fluorinated propylene monomer (FPM). The second seal rings 71b, 72b, and 73b also have substantially the same dimensions, i.e., within manufacturing tolerances, and have a circular cross-section in the uncompressed, i.e., unloaded, state.

[0095] In an alternative embodiment (not shown), instead of providing the first, second, and third annular grooves 66, 67, 68 in the inner circumferential surface 60 of the coolant ring, the milling tool body 2 may include third, fourth, and fifth annular grooves in the outer circumferential mantle surface 10 of the milling tool body 2, which are positioned to receive the first, second, and third seal ring arrangements 71, 72, 73, respectively, when the coolant ring 58 and the first, second, and third seal ring arrangements 71, 72, 73 are attached to the tool body 2. The third, fourth, and fifth annular grooves in the outer circumferential mantle surface 10 of the milling tool body 2 may have the same diameter and width. Each seal ring arrangement 71, 72, 73 may include a first seal ring and a second seal ring. In this embodiment, the first seal ring has a larger diameter than the associated second seal ring and cooperates with the inner peripheral surface 60 of the coolant ring 58 when the coolant ring 58 and the first, second, and third seal ring arrangements 71, 72, 73 are mounted on the tool body 2. Each first seal ring is made of a hard plastic, more specifically, polytetrafluoroethylene (PTFE). The first seal rings may have substantially the same dimensions, i.e., the same dimensions within manufacturing tolerances. Each second seal ring is made of an elastomer, more specifically, fluorinated propylene monomer (FPM), and may have substantially the same dimensions, i.e., the same dimensions within manufacturing tolerances.

[0096] In the illustrated embodiment, the first and second ring-shaped portions 61, 62 of the inner circumferential surface 60 of the coolant ring 59 are arranged on a second common imaginary cylinder. A fifth ring-shaped portion of the inner circumferential surface 60 of the coolant ring 59, which is disposed between the second annular groove 67 and the first axial end face 59 a of the coolant ring, and a sixth ring-shaped portion of the inner circumferential surface 60 of the coolant ring, which is disposed between the first annular groove 66 and the flange 69, are also arranged on the second common imaginary cylinder. This second common imaginary cylinder has a larger diameter than the first common imaginary cylinder on which the third, fourth, and middle ring-shaped portions 13, 14, 15 of the outer circumferential mantle surface 10 of the milling tool body 2 are arranged. Thus, the coolant ring 58 is centered relative to the milling tool body 2 by the first, second, and third seal ring arrangements 71, 72, 73 such that the second longitudinal central axis C2 coincides with the first longitudinal central axis C1 within manufacturing tolerances when the coolant ring 58 and the first, second, and third seal ring arrangements are mounted on the milling tool body 2. Furthermore, when the coolant ring 58 and the first, second, and third seal ring arrangements are mounted on the tool body 2, a bearing function between the coolant ring 58 and the milling tool body 2 during rotational movement of the milling tool body 2 inside the coolant ring 58 is provided by the first, second, and third seal ring arrangements, more specifically the first seal rings 71 a, 72 a, 73 a.

[0097] In the illustrated embodiment, the milling tool 1 includes a retaining ring 100 as a precaution. The retaining ring 100 is not an essential part and serves the purpose of ensuring that the coolant ring 59 does not slip off the milling tool body 2 during transportation of the milling tool 1. The retaining ring 100 is provided with eight through holes 101 and is secured to the milling tool body 2 by eight screws 102 that cooperate with threaded holes 103 in the annular surface 8 of the milling tool body 2 ( FIGS. 4 a-b ). As best seen in FIG. 7 , the retaining ring 100 includes a flange 104 that radially overlaps the coolant ring 59 but is not in contact with the coolant ring 59.

[0098] The cutter body is made from steel, for example 30CrNiMo8, and is gas nitrided. The coolant ring 58 is made from aluminum bronze, for example CuAl10NiFe, which is lightweight and has good resistance to corrosion.

[0099] The cutting insert 21 in the illustrated example is a circular insert. Since each of the at least two insert seats 20 is formed in an exchangeable cartridge 24 attached to the milling tool body 2, the cartridge can be easily replaced with one having a different insert seat, so that other insert shapes can also be used.

[0100] The cutting diameter of the illustrated embodiment is 315 mm. The first common imaginary cylinder on which the third, fourth, and intermediate ring-shaped portions 13, 14, and 15 of the outer peripheral mantle surface 10 of the milling tool body 2 are disposed has a diameter of 350 mm. The second common imaginary cylinder has a diameter of 350.6 mm. The seal ring arrangements 71, 72, and 73 are machined, i.e., cut, to an inner diameter of 349.2 mm. More specifically, the first seal ring is cut to an inner diameter of 349.2 mm after the first, second, and third seal ring arrangements are disposed in the first, second, and third annular grooves, respectively, in the inner peripheral surface of the coolant ring and before the coolant ring together with the seal ring arrangements 71, 72, and 73 are attached to the milling tool body. Once the coolant ring and seal ring arrangements are attached to the milling tool body, a torque of 180 Nm is required to rotate the milling tool body inside the coolant ring. Typical coolant pressures used are 20-50 bar. The arrangement of the milling tool body with the first, second, third, fourth and fifth truncated cone transition surfaces and associated convex radius shaped surfaces facilitates the attachment of the coolant ring to the milling tool body and provides the opportunity to achieve a seal of the first and second annular channels 81, 82 that can withstand higher coolant pressures.

[0101] Any cooling medium in liquid or vapor state can be used, such as water, air, liquid nitrogen, CO2, etc.

[0102] Of course, the present invention is not limited to the above-described embodiment. On the contrary, many possibilities for modification thereof will be apparent to those skilled in the art without departing from the basic concept of the present invention as defined in the appended claims. For example, the coolant ring may be a two-piece coolant ring, consisting of two halves at 180° angles that together form a ring. At the interface between these two halves, the coolant ring may be provided with a sealing gasket. The coolant ring may also be a two-ring configuration, with the first ring functioning for coolant transfer to the first annular channel 81 and the second ring functioning for coolant return from the second annular channel 82.

Claims

1. A milling tool body (2) for a milling tool (1), comprising: an axial front end surface (3); an axial rear end surface (4) opposite to the axial front end surface (3); an outer circumferential mantle surface (10) extending between the axial front end surface (3) and the axial rear end surface (4); a front end portion (2a) extending from the axial front end surface (3) toward the axial rear end surface (4); a rear end portion (2b) extending from the axial rear end surface (4) toward the front end portion (2a) of the milling tool body (2), the rear end portion (2b) being configured to attach the milling tool (1) to a machine; a first longitudinal central axis (C1) extending between the axial front end surface (3) and the axial rear end surface (4), wherein the tool body is rotatable in a rotational direction (R) around the first longitudinal central axis (C1); at least two insert seats (20) provided entirely on the front end (2a) and distributed in the circumferential direction of the milling tool body, each of the at least two insert seats (20) configured to receive a cutting insert (21); a chip pocket (22) provided in front of each of the at least two insert seats (20) in the rotational direction (R) and defined by a chip pocket wall (23) provided entirely at the front end (2a); At least one coolant inlet (30) and at least one coolant outlet (40) are disposed in the milling tool body (2); a cooling duct system (50) housed within the milling tool body (2) extends from the at least one coolant inlet (30) to the at least one coolant outlet (40), and the cooling duct system (50) is arranged such that a coolant supplied via the at least one coolant inlet (30) flows through the cooling duct system (50) to the at least one coolant outlet (40) without exiting the milling tool body (2) along its path between the at least one coolant inlet (30) and the at least one coolant outlet (40); The at least one coolant inlet (30) is arranged in a first ring-shaped portion (11) of the outer circumferential mantle surface (10), the at least one coolant outlet (40) is arranged in a second ring-shaped portion (12) of the outer circumferential mantle surface, the first ring-shaped portion and the second ring-shaped portion are separated from each other by an intermediate ring-shaped portion (15) of the outer circumferential mantle surface (10), the first ring-shaped portion (11) is adjacent to a third ring-shaped portion (13) of the outer circumferential mantle surface (10), so that, when viewed in the direction of the first longitudinal central axis (C1), the first ring-shaped portion (11) is axially located between the intermediate ring-shaped portion (15) and the third ring-shaped portion (13), and the second ring-shaped portion (12) is adjacent to a fourth ring-shaped portion (14) of the outer circumferential mantle surface (10), and wherein, when viewed from the direction of the first longitudinal central axis (C1), the second ring-shaped portion (12) is axially located between the intermediate ring-shaped portion (15) and the fourth ring-shaped portion (14), the first ring-shaped portion, the second ring-shaped portion, the third ring-shaped portion, the fourth ring-shaped portion (11, 12, 13, 14) and the intermediate ring-shaped portion (15) extend between the front end portion (2a) and the axial rear end face (4), and each of the third ring-shaped portion, the fourth ring-shaped portion and the intermediate ring-shaped portion (13, 14, 15) is a surface of revolution generated by a 360° rotation of a curved line or a straight line around the first longitudinal central axis (C1) of the milling tool body (2), and is arranged to be a sealing surface and to cooperate with a seal ring configuration.

2. the at least one coolant inlet (30) is arranged in a first groove (31) of the milling tool body (2) arranged between the third ring-shaped portion (13) and the intermediate ring-shaped portion (15); and / or 2. The milling tool body (2) according to claim 1, characterized in that the at least one coolant outlet (40) is arranged in a second groove (41) of the milling tool body (2) arranged between the fourth ring-shaped portion (14) and the intermediate ring-shaped portion (15).

3. 3. The milling tool body (2) according to claim 2, characterized in that the first groove (31) is a first annular groove (31) and / or the second groove (41) is a second annular groove (41).

4. 4. The milling tool body (2) according to claim 1, wherein a coolant duct system extends partially within the front end (2a) of the milling tool body (2) and intersects a first plane (P1) preferably perpendicular to the first longitudinal central axis of rotation (C1), the first plane (P1) intersecting each chip pocket (22) provided in front of each of the at least two insert seats (20) and / or the first plane (P1) intersecting each of the at least two insert seats (20).

5. The milling tool body (2) according to any one of claims 1 to 4, characterized in that each of the third ring-shaped portion, the fourth ring-shaped portion and the intermediate ring-shaped portion (13, 14, 15) is cylindrical and has substantially the same diameter.

6. the third ring-shaped portion, the fourth ring-shaped portion and the intermediate ring-shaped portion (13, 14, 15) are arranged substantially on a first common imaginary cylinder; the milling tool body (2) is arranged such that the first common imaginary cylinder completely surrounds the milling tool body (2) in a region from the axial rear end face (4) to one of the third and fourth ring-shaped portions (13, 14), the one being arranged farther from the axial rear end face (4) than the other of the third and fourth ring-shaped portions (13, 14); and / or 6. The milling tool body (2) according to claim 5, characterized in that the milling tool body (2) is arranged such that the first common imaginary cylinder completely surrounds the milling tool body (2) in a region from the axial front end face (3) to one of the third ring-shaped portion and the fourth ring-shaped portion (13, 14), the one being arranged farther from the axial front end face (3) than the other of the third ring-shaped portion and the fourth ring-shaped portion (13, 14).

7. 7. The milling tool body (2) according to claim 1, wherein the at least one coolant inlet (30) is a plurality of coolant inlets (30), the at least one coolant outlet (40) is a plurality of coolant outlets (40), and the coolant duct system (50) comprises a plurality of coolant channels (51), each of the plurality of coolant channels (51) extending from only one coolant inlet (30) of the plurality of coolant inlets (30) to only one coolant outlet (40) of the plurality of coolant outlets (40).

8. The milling tool (1) further comprises: a coolant ring (58), the coolant ring (58) having an outer circumferential portion (59) and an inner circumferential surface (60), the inner circumferential surface (60) having a first ring-shaped portion, a second ring-shaped portion, a third ring-shaped portion, a fourth ring-shaped portion and an intermediate ring-shaped portion (61, 62, 63, 64, 65), each of the third ring-shaped portion, the fourth ring-shaped portion and the intermediate ring-shaped portion (63, 64, 65) being a surface of revolution generated by a 360° rotation of a curved line or a straight line about a common second longitudinal central axis (C2), and arranged to be a sealing surface and to cooperate with a sealing ring arrangement; a coolant ring (58) attached to the milling tool body (2) such that an inner peripheral surface (60) of the coolant ring (58) surrounds the outer peripheral mantle surface (10) of the milling tool body (2) and such that the first ring-shaped portion, the second ring-shaped portion, the third ring-shaped portion, the fourth ring-shaped portion, and the intermediate ring-shaped portion (61, 62, 63, 64, 65) of the inner peripheral surface (60) of the coolant ring (58) face the first ring-shaped portion, the second ring-shaped portion, the third ring-shaped portion, the fourth ring-shaped portion, and the intermediate ring-shaped portion (11, 12, 13, 14, 15) of the outer peripheral mantle surface (10) of the milling tool body (2), respectively; a first seal ring arrangement (71) mounted between and arranged to cooperate with the third ring-shaped portion (13) of the outer circumferential mantle surface (10) of the tool body (2) and the third ring-shaped portion (63) of the inner circumferential surface (60) of the coolant ring (58); a second seal ring arrangement (72) mounted between and arranged to cooperate with the fourth ring-shaped portion (14) of the outer circumferential mantle surface (10) of the tool body (2) and the fourth ring-shaped portion (64) of the inner circumferential surface (60) of the coolant ring (58); a third seal ring arrangement (73) mounted between and arranged to cooperate with the intermediate ring-shaped portion (15) of the outer circumferential mantle surface (10) of the tool body (2) and the intermediate ring-shaped portion (65) of the inner circumferential surface (65) of the coolant ring (58); The coolant ring (58), the first seal ring arrangement, the second seal ring arrangement, and the third seal ring arrangement (71, 72, 73), when mounted on the tool body (2), the second longitudinal central axis (C2) substantially coincides with the first longitudinal central axis (C1); a first annular coolant channel (81) is formed between the first ring-shaped portion (11) of the outer circumferential mantle surface (10) and the first ring-shaped portion (61) of the inner circumferential surface (60) of the coolant ring (58), and is axially sealed by the first seal ring arrangement (71) and the third seal ring arrangement (73); a second annular coolant channel (82) is formed between the second ring-shaped portion (12) of the outer circumferential mantle surface (10) and the second ring-shaped portion (62) of the inner circumferential surface (60) of the coolant ring (58), and is axially sealed by the second seal ring arrangement (72) and the third seal ring arrangement (73); The milling tool body (2) is arranged to be rotatable relative to the coolant ring (58); The coolant ring (58) comprises at least one coolant transmission channel (91) arranged to communicate with the first annular coolant channel (81), and the coolant ring (58) further comprises at least one coolant return channel (92) arranged to communicate with the second annular coolant channel (82), each of the at least one coolant transmission channel (91) extending from a coolant inlet (93) in the outer circumferential portion (59) of the coolant ring (58) to an orifice (94) in the first ring-shaped portion (61) of the inner circumferential surface (60) of the coolant ring (58), and at least one 8. A milling tool (1) comprising the milling tool body (2) according to any one of claims 1 to 7, characterized in that each coolant return channel (92) extends from an orifice (95) in the second ring-shaped portion (62) of the inner circumferential surface (60) of the coolant ring (58) to a coolant outlet (96) in the outer circumferential part (59) of the coolant ring (58), and the coolant ring (58) comprises fastening means (97) for fastening the coolant ring (58) to the outside of a machine when the milling tool (1) is mounted on the machine, in order to prevent the coolant ring (58) from moving and rotating.

9. the coolant ring (58) is arranged with a first annular groove, a second annular groove, and a third annular groove (66, 67, 68) in the inner peripheral surface (60), the first annular groove, the second annular groove, and the third annular groove being arranged to receive the first seal ring arrangement, the second seal ring arrangement, and the third seal ring arrangement (71, 72, 73), respectively, when the coolant ring (58), the first seal ring arrangement, the second seal ring arrangement, and the third seal ring arrangement are attached to the tool body (2); or 9. The milling tool (1) according to claim 8, wherein the milling tool body (2) is arranged with a third annular groove, a fourth annular groove, and a fifth annular groove in the outer circumferential mantle surface (10), the third annular groove, the fourth annular groove, and the fifth annular groove being arranged to accommodate the first seal ring arrangement, the second seal ring arrangement, and the third seal ring arrangement (71, 72, 73), respectively, when the coolant ring (58), the first seal ring arrangement, the second seal ring arrangement, and the third seal ring arrangement (71, 72, 73) are attached to the tool body (2).

10. 10. The milling tool (1) according to claim 8 or 9, characterized in that each of the first, second, and third seal ring arrangements (71, 72, 73) comprises a first seal ring (71 a, 72 a, 73 a) and a second seal ring (71 b, 72 b, 73 b), and the first seal ring and the second seal ring of each of the first, second, and third seal ring arrangements (71, 72, 73) are concentric with one another such that, when the coolant ring (58), the first seal ring arrangement, the second seal ring arrangement, and the third seal ring arrangement (71, 72, 73) are mounted on the milling tool body (2), one of the first seal ring and the second seal ring has a smaller diameter and is positioned radially inward from the other, closer to the first longitudinal central axis (C1).

11. 11. The milling tool (1) according to claim 10, characterized in that the first seal ring (71 a, 72 a, 73 a) of each of the first seal ring arrangement, the second seal ring arrangement and the third seal ring arrangement (71, 72, 73) is made of a hard plastic, preferably polytetrafluoroethylene PTFE, and the second seal ring (71 b, 72 b, 73 b) of each of the first seal ring arrangement, the second seal ring arrangement and the third seal ring arrangement (71, 72, 73) is made of an elastomer, preferably fluorinated propylene monomer FPM.

12. The coolant ring (58) is arranged with a first annular groove, a second annular groove and a third annular groove (66, 67, 68) in the inner peripheral surface (60), and the first annular groove, the second annular groove and the third annular groove (66, 67, 68) are arranged to accommodate the first seal ring arrangement, the second seal ring arrangement and the third seal ring arrangement (71, 72, 73), respectively, when the coolant ring (58), the first seal ring arrangement, the second seal ring arrangement and the third seal ring arrangement (71, 72, 73) are mounted on the tool body (2), and the first seal ring arrangement, the second seal ring arrangement and the third seal ring arrangement (71, 72, 73) are arranged to accommodate the first seal ring arrangement, the second seal ring arrangement and the third seal ring arrangement (71, 72, 73) respectively.

12. The milling tool (1) according to claim 11, characterized in that the first seal ring (71 a, 72 a, 73 a) of each of the first seal ring arrangement (71 a, 72 a, 73 a) and the third seal ring arrangement (71, 72, 73) are arranged such that, when the coolant ring (58), the first seal ring arrangement (71 a, 72 a, 73 a) and the third seal ring arrangement (71 b, 72 b, 73 b) are mounted on the tool body (2), the first seal ring (71 a, 72 a, 73 a) has a smaller diameter than the second seal ring (71 b, 72 b, 73 b) and is in contact with and cooperates with the outer circumferential mantle surface (10) of the milling tool body (2).

13. The milling tool body (2) is arranged with a third annular groove, a fourth annular groove, and a fifth annular groove in the outer circumferential mantle surface (10), the third annular groove, the fourth annular groove, and the fifth annular groove are arranged to accommodate the first seal ring configuration, the second seal ring configuration, and the third seal ring configuration (71, 72, 73), respectively, when the coolant ring (58), the first seal ring configuration, the second seal ring configuration, and the third seal ring configuration (71, 72, 73) are mounted on the tool body (2), and the first seal ring configuration, the second seal ring configuration, and the third seal ring configuration 12. The milling tool (1) according to claim 11, characterized in that the first seal ring (71 a, 72 a, 73 a) of each of the coolant ring (58), the first seal ring arrangement (71 a, 72 a, 73 a) and the third seal ring arrangement (71, 72, 73) are arranged such that, when the coolant ring (58), the first seal ring arrangement (71 a, 72 a, 73 a) and the third seal ring arrangement (71, 72, 73) are mounted on the tool body (2), the first seal ring (71 a, 72 a, 73 a) has a larger diameter than the second seal ring (71 b, 72 b, 73 b) and is in contact with and cooperates with an inner circumferential surface (60) of the coolant ring (58).

14. 14. The milling tool (1) according to claim 8, wherein the coolant ring (58) comprises annular surfaces at axial ends of the coolant ring (58), the annular surfaces being arranged to abut against annular surfaces provided on the milling tool body (2) in order to facilitate mounting the coolant ring (58) in a correct longitudinal position on the milling tool body (2) when the coolant ring (58), the first seal ring arrangement, the second seal ring arrangement, and the third seal ring arrangement (71, 72, 73) are mounted on the tool body, the annular surfaces having a center point substantially located on the first longitudinal central axis (C1), and the annular surfaces provided on the coolant ring (58) having a center point substantially located on the second longitudinal central axis (C2).

15. 15. The milling tool (1) according to any one of claims 8 to 14, wherein the coolant ring (58), the first seal ring arrangement, the second seal ring arrangement, and the third seal ring arrangement (71, 72, 73) are arranged such that the coolant ring (58) is centered relative to the milling tool body (2) by the first seal ring arrangement, the second seal ring arrangement, and the third seal ring arrangement (71, 72, 73), whereby, when the coolant ring (58), the first seal ring arrangement, the second seal ring arrangement, and the third seal ring arrangement (71, 72, 73) are attached to the tool body (2), the second longitudinal central axis (C2) substantially coincides with the first longitudinal central axis (C1).

16. 16. The milling tool (1) according to any one of claims 8 to 15, characterized in that when the coolant ring (58), the first seal ring arrangement, the seal ring arrangement 2 and the third seal ring arrangement are mounted on the tool body (2), a bearing function between the coolant ring (58) and the milling tool body (2) during a rotational movement of the milling tool body (2) inside the coolant ring (58) is provided by the first seal ring arrangement, the second seal ring arrangement and the third seal ring arrangement.

17. Milling tool (1) according to any one of claims 8 to 16, characterized in that the coolant ring (58) has a lower density than the milling tool body (2).

18. 18. A system for transmitting a coolant, the system comprising: a milling tool (1) according to any one of claims 8 to 17 connected to the system; the system further comprising a coolant transmission unit connected to the milling tool (1) via the coolant inlet (93) of the at least one coolant transmission channel (91); and a coolant return unit connected to the milling tool (1) via the coolant outlet (96) of the at least one coolant return channel (92).

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