Milling tool and method for chamfering tooth flank edge of tooth on cylindrical toothed workpiece

Abstract

A milling tool for chamfering a tooth flank edge of a tooth of a cylindrical toothed workpiece includes an elongated tool body (2) having a rear portion (6) configured for attachment to a machine tool, a cutting portion (10), and an elongated shank portion (40) carrying the cutting portion and extending from the cutting portion towards the rear portion. The cutting portion (10) is provided with a first cutting edge (11) facing away from the rear portion (6) and a second cutting edge (12) facing the rear portion, the second cutting edge (12) being positioned closer to the rear portion than the first cutting edge. A distance between the second cutting edge and an axis of rotation (3) of the tool body gradually increases from a rear end (12b) of the cutting edge to a front end (12a) of the cutting edge, and the rear end (12b) is positioned at a further distance from the axis of rotation (3) than a radially outermost portion of an outer peripheral surface (41) of the shank.

Description

Technical Field

[0001] The present invention relates to a milling cutter according to the preamble of claim 1, which is used for chamfering the tooth side edges of internal or external teeth located at the opposite end faces of a cylindrical toothed workpiece. The present invention also relates to a method for chamfering these tooth side edges. Background Art

[0002] External or internal gear teeth or spline teeth can be machined on a cylindrical workpiece by cutting techniques using different types of cutting tools. In this case, after the initial machining operation, the formed teeth on the workpiece will have burrs and sharp edges at the intersection between the tooth side surface of the tooth and the corresponding end face of the workpiece (i.e., at the tooth side edges of the tooth located at the opposite end faces of the workpiece). Therefore, subsequent finishing operations may be required to chamfer the tooth side edges of the tooth located at the opposite end faces of the workpiece, thereby removing the burrs and sharp edges.

[0003] WO 2022 / 013068 A1 discloses a method for chamfering the tooth side edges of teeth on a cylindrical toothed workpiece by means of a milling cutter, wherein the workpiece and the milling cutter rotate with a preset relationship between the rotational speed of the milling cutter and the rotational speed of the workpiece while keeping the rotational axis of the milling cutter parallel to the central axis of the workpiece. In the method according to WO 2022 / 013068 A1, the tooth side edges are chamfered in such a way that the first tooth side edge on the tooth is chamfered in the direction from the tooth tip to the tooth root of the tooth, and subsequently the opposite second tooth side edge on the adjacent tooth is chamfered in the direction from the tooth root to the tooth tip of the tooth. The milling cutter disclosed in WO 2022 / 013068 A1 is configured to move into contact with the forward-facing end face of the workpiece. When the tooth side edges located at the forward-facing first end face of the workpiece have been chamfered, the workpiece must be repositioned in the workpiece holder so that the opposite second end face of the workpiece faces forward towards the milling cutter, and then the chamfering of the tooth side edges located at this second end face of the workpiece is continued. Summary of the Invention

[0004] Object of the Invention

[0005] The object of the present invention is to provide a milling cutter of the above type, which has a novel and advantageous design. Overview of the Invention

[0007] According to a first aspect of the present invention, the above object is achieved by a milling cutter having the features defined in claim 1.

[0008] The milling cutter according to the first aspect of the present invention includes an elongate cutter body having, at its rear end, a structure for attachment to the rear part of a machine tool, and having a cutting portion at a certain distance from the rear part, the cutting portion being provided with cutting edges, wherein the cutter body includes an elongate shank that carries the cutting portion and extends from the cutting portion towards the rear part. The shank has a front end facing the cutting portion, an opposite rear end, and an outer peripheral surface extending around the shank between the rear end and the front end, wherein the shank has a longitudinal central axis that coincides with the rotational axis of the cutter body.

[0009] The cutting portion is provided with at least a pair of cutting edges, the at least a pair of cutting edges including a first cutting edge facing away from the rear part and a second cutting edge facing the rear part, the second cutting edge being positioned closer to the rear part than the first cutting edge, wherein: - The first cutting edge has a rear end and an opposite front end, the rear end of the first cutting edge being positioned closer to the rear part of the cutter body than the front end of the first cutting edge, wherein the front end of the first cutting edge is positioned closer to the rotational axis than the rear end of the first cutting edge, and when viewed in the direction along the first cutting edge from its front end to its rear end, the distance between the first cutting edge and the rotational axis gradually increases, and - The second cutting edge has a front end and an opposite rear end, the rear end of the second cutting edge being positioned closer to the rear part of the cutter body than the front end of the second cutting edge, wherein the rear end of the second cutting edge is positioned at a greater distance from the rotational axis than the radially outermost portion of the outer peripheral surface of the shank, and wherein the rear end of the second cutting edge is positioned closer to the rotational axis than the front end of the second cutting edge, and when viewed in the direction along the second cutting edge from its rear end to its front end, the distance between the second cutting edge and the rotational axis gradually increases.

[0010] Furthermore, the cutting portion has an extension in the axial direction of the cutter body, the extension being restricted to a region between a first plane and a second plane, the first plane extending perpendicular to the rotational axis and intersecting the rear end of the second cutting edge, the second plane extending perpendicular to the rotational axis and intersecting the front end of the first cutting edge. According to a first alternative, the cutting portion constitutes the axially foremost part of the cutter body, i.e., the part of the cutter body that is furthest from the rear part of the cutter body. According to a second alternative, the cutter body includes a front part that projects from the cutting portion on the side of the cutting portion facing away from the rear part, wherein the front end of the first cutting edge is positioned at a greater distance from the rotational axis than the radially outermost portion of the front part.

[0011] The design of the tool body (having an elongated shank between the cutting part and the rear part), the arrangement structure of the first and second cutting edges on the cutting part as described above, and the position of the second cutting edge relative to the outer peripheral surface of the shank mean that the milling cutter can be used to chamfer the tooth side edges of the internal or external teeth on the cylindrical toothed workpiece, which are located at the two end faces of the workpiece, without repositioning the workpiece. The above-mentioned first cutting edge can be used to chamfer the tooth side edges of the teeth on the toothed workpiece, which are located at the end face of the workpiece facing away from the workpiece holder carrying the workpiece, and the above-mentioned second cutting edge can be used to chamfer the tooth side edges of the teeth on the workpiece, which are located at the opposite end face of the workpiece.

[0012] Preferably, the above-mentioned internal or external teeth on the workpiece are gear teeth or spline teeth, preferably having a module of 2 - 12.

[0013] The radial distance between the rear end of the second cutting edge and the radially outermost part of the outer peripheral surface of the shank must be appropriately adjusted according to the tooth depth of the teeth of the toothed workpiece to be machined, and this radial distance is preferably 2 - 40 mm, more preferably 6 - 30 mm. Advantageously, the radial distance is greater than the tooth depth, but as an alternative, considering the radial extension of the second cutting edge, this radial distance can also be slightly less than the tooth depth. In the case where the tool body includes a front part (which protrudes from the cutting part on the side opposite to the rear part), the radial distance between the front end of the first cutting edge and the radially outermost part of the outer peripheral surface of the front part is preferably 2 - 40 mm, more preferably 6 - 30 mm, and preferably but not necessarily, this radial distance is equal to the radial distance between the rear end of the second cutting edge and the radially outermost part of the outer peripheral surface of the shank.

[0014] According to an embodiment of the present invention, the first cutting edge extends substantially linearly in a third plane containing the axis of rotation, and the second cutting edge extends substantially linearly in a fourth plane containing the axis of rotation. The fourth plane may be angularly offset from the third plane on the axis of rotation. However, preferably, the fourth plane coincides with the third plane. The first cutting edge and the second cutting edge have such inclinations in the third plane and the fourth plane respectively that the extension of the first cutting edge forms a first angle with the axis of rotation, and the extension of the second cutting edge forms a second angle with the axis of rotation. The first cutting edge and the second cutting edge may have such inclinations that the first angle and the second angle are different from each other. However, preferably, the first cutting edge and the second cutting edge have such inclinations that the first angle and the second angle are substantially equal. Advantageously, the first angle and the second angle are greater than or equal to 20° and less than 90°, preferably 30° - 80°.

[0015] Another embodiment of the present invention is characterized in that: - The first cutting edge is formed at the intersection between a first surface on the cutting part and a second surface on the cutting part, wherein the first surface and the second surface are mirror-symmetrical to each other with respect to the above-mentioned third plane; and - The second cutting edge is formed at the intersection between a third surface on the cutting part and a fourth surface on the cutting part, wherein the third surface and the fourth surface are mirror-symmetrical to each other with respect to the above-mentioned fourth plane.

[0016] Therefore, the cutting performance of each cutting edge will be the same in the two rotational directions of the milling cutter. When chamfering is performed by the first cutting edge, when the milling cutter rotates in one rotational direction, the first surface functions as a rake face, and the second surface functions as a clearance face; when the rotational direction changes, the first surface functions as a clearance face, and the second surface functions as a rake face. When chamfering is performed by the second cutting edge, when the milling cutter rotates in one rotational direction, the third surface functions as a rake face, and the fourth surface functions as a clearance face; when the rotational direction changes, the third surface functions as a clearance face, and the fourth surface functions as a rake face.

[0017] Preferably, the first cutting edge and the second cutting edge are mirror-symmetrical to each other with respect to a symmetry plane that extends perpendicular to the axis of rotation at the midpoint between the first cutting edge and the second cutting edge.

[0018] According to another embodiment of the present invention, the cutting portion includes a holder arm that projects beyond the radially outermost portion of the outer peripheral surface of the shank in a radial direction relative to the rotation axis, wherein the holder arm has an inner end (i.e., a radially inner end) facing the rotation axis and an opposite outer end (i.e., a radially outer end), and wherein the first cutting edge and the second cutting edge are disposed at the outer end of the holder arm on the holder arm. As an alternative, the cutting portion may include a disc-shaped holder that projects beyond the radially outermost portion of the outer peripheral surface of the shank in a radial direction relative to the rotation axis, wherein the first cutting edge and the second cutting edge are disposed at the outer periphery of the disc-shaped holder on the disc-shaped holder.

[0019] According to another embodiment of the present invention, the first cutting edge and the second cutting edge form part of a cutting insert that is releasably mounted to a blade seat provided at the outer end of the holder arm or alternatively at the outer periphery of the disc-shaped holder. Thus, when either the first cutting edge or the second cutting edge has worn out, the cutting insert can be easily replaced with a new cutting insert.

[0020] According to another embodiment of the present invention, the cutting portion includes a base that carries the holder arm and is slidably mounted to the shank at the front end of the shank so as to be able to linearly slide relative to the shank perpendicular to the rotation axis and in the longitudinal direction of the holder arm, wherein the base can be locked to the shank at different sliding positions relative to the shank so as to allow adjustment of the radial distance between the first cutting edge and the rotation axis and the radial distance between the second cutting edge and the rotation axis.

[0021] Preferably, the shank is rod-shaped and the shank will be longer than the length of the workpiece, i.e., longer than the axial distance between the two opposite end faces of the workpiece. For example, the length of the shank can be 25 - 500 mm, preferably 50 - 200 mm, more preferably 100 - 150 mm.

[0022] According to another embodiment of the present invention, the cutting portion is detachably mounted to the shank at the front end of the shank. In this case, for example, a plurality of cutting portions can be provided, which have holder arms of different lengths, so that by mounting a cutting portion with a holder arm of a suitable length to the shank, it is allowed to easily adjust the milling cutter according to the tooth depth of the teeth on the toothed workpiece to be machined.

[0023] Other advantageous features of the milling cutter according to the present invention will become apparent from the following description.

[0024] According to a second aspect of the present invention, the object is achieved by a method having the features defined in claim 13.

[0025] The method according to the second aspect of the present invention is a method for chamfering the tooth side edges of internal or external teeth on a cylindrical toothed workpiece, which are located at a first end face of the workpiece and at a second end face opposite to the workpiece, wherein each tooth on the workpiece has a tooth tip, a tooth root, a first tooth side surface extending between the tooth tip and the tooth root on a first side of the tooth, and a second tooth side surface extending between the tooth tip and the tooth root on a second side opposite to the first side of the tooth, a first tooth side edge is formed at the intersection between the first tooth side surface and the first end face of the workpiece, a second tooth side edge is formed at the intersection between the second tooth side surface and the first end face of the workpiece, a third tooth side edge is formed at the intersection between the first tooth side surface and the second end face of the workpiece, and a fourth tooth side edge is formed at the intersection between the second tooth side surface and the second end face of the workpiece, wherein the workpiece is attached to a machine tool, and the workpiece can be rotated by the machine tool about the central axis of the workpiece, and wherein the chamfering is performed by a milling cutter according to the present invention, the milling cutter is attached to the machine tool, and the milling cutter can be rotated by the machine tool about the rotation axis of the tool body, and the milling cutter can be moved by the machine tool relative to the workpiece in the axial direction of the workpiece and in different directions in a plane perpendicular to the central axis of the workpiece, wherein the rotation axis of the tool body is parallel to the central axis of the workpiece, and the method comprises the following steps: a) Positioning the milling cutter in a first preset position relative to the workpiece, wherein the rotation axis of the tool body is parallel to the central axis of the workpiece, and the cutting part of the tool body is adjacent to the first end face of the workpiece, and one of the first cutting edge and the second cutting edge of the at least one pair of cutting edges faces the first end face; b) Rotating the milling cutter about the rotation axis of the tool body, and simultaneously rotating the workpiece about its central axis at a preset relationship between the rotation speed of the milling cutter and the rotation speed of the workpiece, while keeping the rotation axis of the tool body parallel to the central axis of the workpiece, and moving the milling cutter relative to the workpiece along a preset path, so that the cutting edge facing the first end face of the workpiece chamfers the first tooth side edge and the second tooth side edge of the teeth on the workpiece; c) Moving the milling cutter relative to the workpiece so that the cutting edge facing the first end face of the workpiece moves out of contact with the workpiece; d) Move the milling cutter relative to the workpiece to a second preset position, where the rotational axis of the cutter body is parallel to the central axis of the workpiece, and the cutting portion of the cutter body is adjacent to the opposite second end face of the workpiece, and the other cutting edge of the first cutting edge and the second cutting edge in the at least one pair of cutting edges faces the second end face; and e) Rotate the milling cutter about the rotational axis of the cutter body, and simultaneously, rotate the workpiece about its central axis with a preset relationship between the rotational speed of the milling cutter and the rotational speed of the workpiece, while keeping the rotational axis of the cutter body parallel to the central axis of the workpiece, and move the milling cutter relative to the workpiece along a preset path, so that the cutting edge facing the second end face of the workpiece chamfers the third tooth side edge and the fourth tooth side edge of the teeth on the workpiece.

[0026] By using this method, the milling cutter chamfers the tooth side edges located on the two end faces of the internal or external teeth of the cylindrical toothed workpiece without any repositioning of the workpiece. Therefore, during the entire chamfering process, the workpiece can be kept clamped to a suitable workpiece holder of the machine tool in the same orientation, which saves time. The above-mentioned first cutting edge on the milling cutter is used to chamfer the tooth side edge of the tooth on the workpiece at the end face of the workpiece facing away from the workpiece holder that rotatably supports the workpiece, and the above-mentioned second cutting edge on the milling cutter is used to chamfer the tooth side edge of the tooth on the workpiece at the opposite end face of the workpiece. The chamfering process can start from chamfering the tooth side edge at the end face of the workpiece facing away from the workpiece holder, and then continue to chamfer the tooth side edge at the end face of the workpiece facing the workpiece holder. As an alternative, the chamfering process can start from chamfering the tooth side edge at the end face of the workpiece facing the workpiece holder, and then continue to chamfer the tooth side edge at the end face of the workpiece facing away from the workpiece holder.

[0027] According to an embodiment of the present invention, in step b, the preset path for the relative movement of the milling cutter with respect to the workpiece includes at least one portion in which the milling cutter moves in the axial direction of the milling cutter, so that the cutting edge facing the first end face of the workpiece moves in the direction towards the first end face, and / or, in step e, the preset path for the relative movement of the milling cutter with respect to the workpiece includes at least one portion in which the milling cutter moves in the axial direction of the milling cutter, so that the cutting edge facing the second end face of the workpiece moves in the direction towards the second end face.

[0028] According to another embodiment of the present invention, in step b, the preset path for the milling cutter to move relative to the workpiece includes at least one portion in which the distance between the rotational axis of the cutter body and the central axis of the workpiece changes, and / or, in step e, the preset path for the milling cutter to move relative to the workpiece includes at least one portion in which the distance between the rotational axis of the cutter body and the central axis of the workpiece changes. The change in the distance between the rotational axis of the cutter body and the central axis of the workpiece can be achieved by moving the milling cutter in a direction perpendicular to the rotational axis of the cutter body, and / or by moving the workpiece in a direction perpendicular to the central axis of the workpiece.

[0029] In step b and / or step e, the preset path for the milling cutter to move relative to the workpiece may of course also include one or more portions in which, while the distance between the rotational axis of the cutter body and the central axis of the workpiece changes, the milling cutter moves in the axial direction of the milling cutter.

[0030] According to another embodiment of the present invention: - In step b, the first flank edge and the second flank edge of the teeth on the workpiece are each chamfered in the machining direction from the tooth root to the tooth tip of the associated tooth, and - In step e, the third flank edge and the fourth flank edge of the teeth on the workpiece are each chamfered in the machining direction from the tooth root to the tooth tip of the associated tooth.

[0031] Therefore, the chamfering of each flank edge starts from the deepest part of the gap between two teeth (i.e., the so-called bottom land or tooth root surface) and ends at the tooth tip of the associated tooth. It has been found that when chamfering the flank edge in the machining direction from the tooth tip to the tooth root, especially when the cutting edge has been used for some time and begins to wear, burr formation may occur in the tooth root area. It has also been found that when chamfering the flank edge in the opposite machining direction from the tooth root to the tooth tip, this burr formation can be avoided. Therefore, chamfering each flank edge of the teeth on the workpiece in the machining direction from the tooth root to the tooth tip improves the quality of the chamfer produced on the flank edge.

[0032] According to another embodiment, in order to achieve chamfering of each of the first flank edge and the second flank edge of the teeth on the workpiece in the machining direction from the tooth root to the tooth tip, step b includes the following sub-steps: b1) Chamfer the first flank edge of the teeth on the workpiece while rotating the workpiece about its central axis in a first rotational direction, where the second flank surface is the front flank surface and the first flank surface is the rear flank surface, and simultaneously, when the first flank edge being chamfered is the flank edge of an internal tooth on the workpiece, rotate the milling cutter about the rotational axis of the tool body in the same rotational direction as the workpiece, or when the first flank edge being chamfered is the flank edge of an external tooth on the workpiece, rotate the milling cutter about the rotational axis of the tool body in the opposite rotational direction, and b2) Chamfer the second flank edge of the teeth on the workpiece while rotating the workpiece about its central axis in a second rotational direction opposite to the first rotational direction, and simultaneously, when the second flank edge being chamfered is the flank edge of an internal tooth on the workpiece, rotate the milling cutter about the rotational axis of the tool body in the same rotational direction as the workpiece, or when the second flank edge being chamfered is the flank edge of an external tooth on the workpiece, rotate the milling cutter about the rotational axis of the tool body in the rotational direction opposite to the workpiece.

[0033] In this specification and the subsequent claims, the expression "front flank surface" refers to the flank surface that faces the rotational direction (i.e., faces forward) when the toothed workpiece rotates about its central axis, while the expression "rear flank surface" refers to the flank surface that faces the opposite direction (i.e., faces backward) when the toothed workpiece rotates about its central axis.

[0034] According to another embodiment of the present invention, in order to achieve chamfering each of the third flank edge and the fourth flank edge of the teeth on the workpiece in the machining direction from the tooth root to the tooth tip, step e includes the following sub-steps: e1) Chamfer the third flank edge of the teeth on the workpiece while rotating the workpiece about its central axis in a first rotational direction, and simultaneously, when the third flank edge being chamfered is the flank edge of an internal tooth on the workpiece, rotate the milling cutter about the rotational axis of the tool body in the same rotational direction as the workpiece, or when the third flank edge being chamfered is the flank edge of an external tooth on the workpiece, rotate the milling cutter about the rotational axis of the tool body in the rotational direction opposite to the workpiece, and e2) Chamfer the fourth flank edge of the teeth on the workpiece, while rotating the workpiece about its central axis in a second rotational direction, and simultaneously, when the flank edge of the internal teeth on the workpiece at the fourth flank edge being chamfered, rotate the milling cutter about the rotational axis of the tool body in the same rotational direction as the workpiece, or when the fourth flank edge being chamfered is the flank edge of the external teeth on the workpiece, rotate the milling cutter about the rotational axis of the tool body in a rotational direction opposite to that of the workpiece.

[0035] Preferably, the above sub-steps are performed in the following order: b1 - b2 - e1 - e2, wherein between sub-steps b1 and b2 and between sub-steps e1 and e2, the rotational directions of the milling cutter and the workpiece are reversed. However, as an alternative, these sub-steps may also be performed in the following order: b1 - e1 - e2 - b2, wherein the rotational directions of the milling cutter and the workpiece are reversed only between sub-steps e1 and e2.

[0036] According to a third aspect of the present invention, the present invention relates to a computer-based program having instructions which, when executed by a CNC machine tool, cause the CNC machine tool to perform the steps according to any one of the above methods. The computer program or computer program product may be included in a CAM software product (i.e., software for computer-aided manufacturing). The computer program may be in the form of a computer-readable medium, such as a USB stick, a CD-ROM or a data stream.

[0037] Other advantageous features of the method according to the present invention will become apparent from the following description. Description of the Drawings

[0038] With reference to the accompanying drawings, the following is a detailed description of embodiments of the present invention cited as examples. In the drawings:

[0039] Figure 1 is a perspective view of a milling cutter according to an embodiment of the present invention,

[0040] Figure 2 is Figure 1 a side view of the milling cutter,

[0041] Figure 3 is Figure 1 a front view of the milling cutter,

[0042] Figure 4a and 4b is Figure 1 an exploded perspective view of a part of the milling cutter from different directions,

[0043] Figure 5 is included inFigure 1 Rear view of the cutting part in a milling cutter

[0044] Figure 6 is Figure 5 Side view of the cutting part

[0045] Figure 7 is Figure 5 Perspective view of the cutting part

[0046] Figure 8 is Figure 5 Plan view of the cutting part

[0047] Figure 9a is observed when the milling cutter is in a position for chamfering the tooth flank edge at the first end face of the workpiece Figure 1 Perspective view of the milling cutter and the workpiece with internal teeth

[0048] Figure 9b is Figure 9a Front view of the milling cutter and the workpiece

[0049] Figure 10a and 10b is observed when the milling cutter is in a position for chamfering the tooth flank edge at the opposite second end face of the workpiece Figure 9a Perspective views of the milling cutter and the workpiece from different directions

[0050] Figure 10c is Figure 10a and Figure 10b Front view of the milling cutter and the workpiece

[0051] Figure 11 is Figure 9a Enlarged perspective view of a part of the workpiece with internal teeth

[0052] Figure 12 is Figure 9a Enlarged front view of a part of the workpiece with internal teeth

[0053] Figure 13 is Figure 9a Partial sectional side view of a part of the milling cutter and the workpiece

[0054] Figure 14a - 14e is a diagram of different stages during the process of chamfering the tooth flank edge on the workpiece with internal teeth by means of Figure 1 the milling cutter

[0055] Figure 15a is observed when the milling cutter is in a position for chamfering the tooth flank edge at the first end face of the workpieceFigure 1 Perspective view of a milling cutter and a toothed workpiece with external teeth

[0056] Figure 15b is Figure 15a Front view of the milling cutter and the workpiece

[0057] Figure 16a and 16b are observed when the milling cutter is in a position for chamfering the flank edges located at the opposite second end faces of the workpiece, Figure 15a Perspective views of the milling cutter and the workpiece from different directions

[0058] Figure 16c is Figure 16a and 16b Front view of the milling cutter and the workpiece

[0059] Figure 17 Side view of a milling cutter according to an alternative embodiment of the present invention Detailed description

[0060] Figures 1 - 8 Illustrates an embodiment of a milling cutter 1 according to the present invention. The milling cutter 1 is for chamfering the flank edges of internal or external teeth on a cylindrical toothed workpiece, which are located at the opposite end faces of the workpiece. The milling cutter 1 includes an elongated cutter body 2, which is configured to rotate about a rotational axis 3. The cutter body 2 has a front end 2a and an opposite rear end 2b. In the illustrated embodiment, a collar 5 is provided on the cutter body 2. The rear portion 6 of the cutter body 2 is located between the collar 5 and the rear end 2b and forms a connecting member through which the cutter body 2 can be directly or via an intermediate tool holder mounted to the rotating spindle or a similar component of a machine tool (such as a milling machine). In the embodiment shown in the figure, the rear portion 6 is a Coromant Capto® of size C8. Other available sizes of Coromant Capto® are C3 - C10. The rear portion 6 can also be any other connecting member suitable for such purposes, such as HSK.

[0061] The tool body 2 includes a cutting part 10 which is positioned at a certain distance from the rear part 6 and is provided with cutting edges 11, 12. The tool body 2 also includes an elongated shank 40 which carries the cutting part 10 and extends from the cutting part 10 towards the rear part 6. The shank 40 has a front end 40a facing the cutting part 10 and an opposite rear end 40b facing the collar 5 and the rear part 6. The cutting part 10 is mounted to the shank 40 at the front end 40a of the shank 40. The shank 40 has an outer peripheral surface 41 which extends around the shank 40 between the rear end 40b and the front end 40a of the shank. The shank 40 has a longitudinal central axis which coincides with the rotational axis 3 of the tool body 2.

[0062] The cutting part 10 is provided with a pair of cutting edges which consists of a first cutting edge 11 facing away from the rear part 6 of the tool body and a second cutting edge 12 facing the rear part 6 of the tool body, and the second cutting edge 12 is positioned closer to the rear part 6 than the first cutting edge 11. Therefore, the first cutting edge 11 is farther from the rear part 6 of the tool body than the second cutting edge 12. Each of the first cutting edge 11 and the second cutting edge 12 has a front end 11a, 12a and an opposite rear end 11b, 12b. The rear end 11b of the first cutting edge 11 is positioned closer to the rear part 6 of the tool body than the front end 11a of the first cutting edge 11, and the rear end 12b of the second cutting edge 12 is positioned closer to the rear part 6 of the tool body than the front end 12a of the second cutting edge 12. As Figure 2 and Figure 6 shown, the front end 11a of the first cutting edge 11 is positioned closer to the rotational axis 3 than the rear end 11b of the first cutting edge 11, and when observed in the direction along the first cutting edge 11 from its front end 11a to its rear end 11b, the distance between the first cutting edge 11 and the rotational axis 3 gradually increases. The rear end 12b of the second cutting edge 12 is positioned closer to the rotational axis 3 than the front end 12a of the second cutting edge 12, and when observed in the direction along the second cutting edge 12 from its rear end 12b to its front end 12a, the distance between the second cutting edge 12 and the rotational axis 3 gradually increases. In addition, the rear end 12b of the second cutting edge 12 is positioned at a farther distance from the rotational axis 3 than the radially outermost part of the outer peripheral surface 41 of the shank 40.

[0063] The cutting part 10 may also be provided with two or more pairs of cutting edges 11, 12 of the above type.

[0064] The cutting part 10 has an extension in the axial direction of the tool body 2, and the extension is restricted to the region between a first plane P1 (see Figure 2 ) and a second plane P2, the first plane P1 extending perpendicular to the rotational axis 3 and intersecting the rear end 12b of the second cutting edge 12, and the second plane P2 extending perpendicular to the rotational axis 3 and intersecting the front end 11a of the first cutting edge 11. InFigures 1 - 8 In the illustrated embodiment, no part of the tool body 2 extends axially beyond the cutting part 10. Thus, in this example, the cutting part 10 forms the axially foremost part of the tool body 2, i.e., the part of the tool body 2 that is furthest from the rear part 6. As an alternative, the tool body 2 may further include a front part 7 that is connected to and projects from the cutting part 10 on the side of the cutting part 10 facing away from the rear part 6, as Figure 17 illustrated. In this example, the front end 11a of the first cutting edge 11 will be positioned at a greater distance from the rotational axis 3 than the radially outermost part of the outer circumferential surface of the front part 7.

[0065] The radial distance r between the rear end 12b of the second cutting edge 12 and the radially outermost part of the outer circumferential surface 41 of the shank 40 is preferably 2 - 40 mm, more preferably 6 - 30 mm. In Figure 17 the illustrated embodiment, the radial distance r between the front end 11a of the first cutting edge 11 and the radially outermost part of the outer circumferential surface of the front part 7 2 is preferably 2 - 40 mm, more preferably 6 - 30 mm.

[0066] In the illustrated embodiment, the shank 40 is rod-shaped and has the shape of a regular cylinder. However, the shank 40 may also have any other suitable shape. The length L of the shank 40 is 25 - 500 mm, preferably 50 - 200 mm, more preferably 100 - 150 mm.

[0067] The cutting part 10 may be permanently fixed to the shank 40. However, in Figures 1 - 8 the illustrated embodiment, the cutting part 10 is detachably mounted to the shank 40 at the front end 40a of the shank 40 by means of fastening elements 42 (in the form of two screws) that extend through corresponding through holes 13 in the cutting part 10 and engage in corresponding threaded holes 43 provided in the front end face 44 of the shank 40 (see Figure 4a ).

[0068] In the illustrated embodiment, the cutting part 10 includes a base 14 and a holder arm 15. The cutting part 10 is mounted to the shank 40 by the base 14, and the holder arm 15 is fixed to the base 14 and projects radially beyond the outermost radial surface 41 of the shank 40 from the base 40 in a radial direction relative to the axis of rotation 3. The holder arm 15 has an inner end 15a facing the axis of rotation 3 and an opposite outer end 15b. The holder arm 15 is fixed to the base 14 at its inner end 15a, and a first cutting edge 11 and a second cutting edge 12 are arranged on the holder arm 15 at the outer end 15b of the holder arm 15. In the illustrated embodiment, the first cutting edge 11 and the second cutting edge 12 form part of a cutting insert 16 that is releasably mounted to a blade seat 17 provided at the outer end 15b of the holder arm 15. The illustrated cutting insert 16 is releasably fixed to the blade seat 17 by a fastening element 18 in the form of a screw that extends through a through hole 19 in the cutting insert 16 and engages in a threaded hole 20 in a support surface 21 in the blade seat 17 (see Figure 4a ). Advantageously, the support surface 21 is provided with splines 22 or a similar structure that is configured for positive mechanical engagement with corresponding splines 23 on the underside of the cutting insert 16 to ensure correct positioning of the cutting insert 16 in the blade seat 17 and prevent movement of the cutting insert 16 relative to the support surface 21 when the cutting insert is correctly mounted to the blade seat 17.

[0069] Advantageously, the base 14 and the shank 40 are formed as separate components, where the base 14 can be detachably mounted to the shank 40. However, as an alternative, the base 14 and the shank 40 can also be formed as a single piece. In a corresponding manner, the front part 7 and the base 14 included in the milling cutter 1 shown in Figure 17 can be formed as a single piece or can be formed as separate components that are mounted to each other.

[0070] In Figures 1 - 8In the illustrated embodiment, the base 14 is slidably mounted to the shank 40 at the front end 40a of the shank 40 so as to be able to linearly slide relative to the shank 40 perpendicular to the axis of rotation 3 and in the longitudinal direction of the holder arm 15, wherein the base 14 can be locked to the shank 40 at different sliding positions relative to the shank 40, thereby allowing adjustment of the radial distance between the first cutting edge 11 and the axis of rotation 3 and the radial distance between the second cutting edge 12 and the axis of rotation 3. Therefore, by adjusting the position of the base 14 relative to the shank 40, the above-mentioned radial distance r between the rear end 12b of the second cutting edge 12 and the radially outermost portion of the outer peripheral surface 41 of the shank 40 can be adjusted. In the illustrated example, the rear surface 14a of the base 14 is provided with splines 25 that are parallel to each other, and these splines 25 extend parallel to the longitudinal axis of the holder arm 15, and these splines 25 can be slidably engaged with corresponding splines 45 provided on the front end face 44 of the shank 40 so as to allow the base 14 to slide relative to the shank 40 in the desired direction during adjustment of the sliding position of the base 14 relative to the shank 40.

[0071] Figures 1 - 8The milling cutter 1 shown includes an adjusting mechanism 50 by means of which the sliding position of the base 14 relative to the shank 40 can be adjusted. Thus, the precise position of the base 14 along the spline 45 on the front face 44 of the shank 40 can be adjusted by means of the adjusting mechanism 50. In the illustrated embodiment, the adjusting mechanism 50 includes an adjusting element 51 which is configured to act between the base 14 and the shank 40. This adjusting element 51 includes a pin 52 and a head 53, the pin 52 being rotatably received in a hole 46 provided in the front face 44 of the shank 40, the head 53 being fixed to the pin 52 and being rotatably received in a recess 26 provided in the rear surface 14a of the base 14. The axis of rotation of the pin 52 is parallel to the axis of rotation of the head 53 but offset relative to the axis of rotation of the head 53 such that rotation of the head 53 within the recess 26 will effect a sliding movement of the base 14 in the longitudinal direction of the splines 25, 45. A socket 54 designed to releasably engage a torque tool (not shown) is provided in the front face of the head 53 so as to allow the torque tool to be connected to the head 53 when the head 53 needs to be rotated so as to move the base 14 in the longitudinal direction of the splines 25, 45. The socket 54 can be accessed through a hole 27 in the base 14. The above-described through holes 13 for the fastening elements 42 are provided in the base 14. Each of these through holes 13 has an elongated cross-sectional shape with the longer axis extending substantially in the longitudinal direction of the spline 25, thereby allowing the base 14 to move perpendicular to the axis 42a of the fastening element 42 in the longitudinal direction of the spline 45 located on the front face 44 of the shank 40. By tightening the fastening element 42, the base 14 can be locked to the shank 40 in the desired sliding position relative to the shank 40. Of course, the adjusting mechanism 50 can also be designed in any other suitable form.

[0072] In Figures 1 - 8 the illustrated embodiment, the first cutting edge 11 extends substantially linearly in a third plane P3 (see Figure 8 ), which contains the axis of rotation 3, and the second cutting edge 12 extends substantially linearly in a fourth plane P4 which contains the axis of rotation 3. Preferably, the fourth plane P4 coincides with the third plane P3, as Figure 8 shown, but as an alternative, the third plane P3 and the fourth plane P4 can also be offset angularly from each other relative to the axis of rotation 3 of the tool body 2. The first cutting edge 11 has such an inclination within the third plane P3 that the extension of the first cutting edge 11 forms a first angle α 1 (see Figure 2 ), with the axis of rotation 3, and the second cutting edge 12 has such an inclination within the fourth plane P4 that the extension of the second cutting edge 12 forms a second angle α 2 with the axis of rotation 3. Preferably, the first angle α1 and a second angle α 2 are equal or at least substantially equal. The first angle α 1 and the second angle α 2 is greater than or equal to 20° and less than 90°, preferably 30° - 80°. In the illustrated embodiment, the first angle α 1 and the second angle α 2 are both approximately 45°.

[0073] In Figures 1 - 8 the illustrated embodiment, the first cutting edge 11 is formed at the intersection between a first surface 31 and a second surface 32 on the cutting insert 16, and the second cutting edge 12 is formed at the intersection between a third surface 33 and a fourth surface 34 on the cutting insert 16, wherein the first surface 31 and the second surface 32 are mirror-symmetrical to each other with respect to a third plane P3, and the third surface 33 and the fourth surface 34 are mirror-symmetrical to each other with respect to a fourth plane P4. In addition, the first cutting edge 11 and the second cutting edge 12 are mirror-symmetrical to each other here with respect to a symmetry plane PS (see Figure 8 ), which symmetry plane PS extends perpendicular to the rotational axis 3 of the tool body 2 at the midpoint between the first cutting edge 11 and the second cutting edge 12. The first surface 31 and the second surface 32 are inclined with respect to each other and diverge from each other in a direction from the first cutting edge 11 towards the rotational axis 3, wherein the first surface 31 and the second surface 32 form a first tip-like projection 35a on the cutting insert 16. In a corresponding manner, the third surface 33 and the fourth surface 34 are inclined with respect to each other and diverge from each other in a direction from the second cutting edge 12 towards the rotational axis 3, wherein the third surface 33 and the fourth surface 34 form a second tip-like projection 35b on the cutting insert 16. A first projection 36a is provided on a first side of the holder arm 15 and is located at the outer end 15b of the holder arm 15 so as to form a support for the first tip-like projection 35a on the cutting insert 16, and a second projection 36b is provided on a second opposite side of the holder arm 15 and is located at the outer end 15b of the holder arm 15 so as to form a support for the second tip-like projection 35b on the cutting insert 16.

[0074] As described above, the milling cutter 1 is used to chamfer the tooth flank edges 61 - 64 of the internal or external teeth 60 on the cylindrical toothed workpiece 8, which are located at the first end face 9a of the workpiece and at the opposite second end face 9b of the workpiece. Each tooth 60 on the workpiece 8 has a tooth tip 65, a tooth root 66, a first tooth flank surface 67a, and a second tooth flank surface 67b. The first tooth flank surface 67a extends between the tooth tip 65 and the tooth root 66 on the first side of the tooth, and the second tooth flank surface 67b extends between the tooth tip 65 and the tooth root 66 on the opposite second side of the tooth. The first tooth flank edge 61 is formed at the intersection between the first tooth flank surface 67a and the first end face 9a of the workpiece 8, the second tooth flank edge 62 is formed at the intersection between the second tooth flank surface 67b and the first end face 9a of the workpiece 8, the third tooth flank edge 63 is formed at the intersection between the first tooth flank surface 67a and the second end face 9b of the workpiece 8, and the fourth tooth flank edge 64 is formed at the intersection between the second tooth flank surface 67b and the second end face 9b of the workpiece 8. A tooth space surface 68 is provided between the tooth roots 66 of every two adjacent teeth 60, and a tooth top 69 is provided at the tooth tip 65 of each tooth 60.

[0075] Before chamfering the tooth flank edges 61 - 64 with the milling cutter 1, the edges 70 at the junctions between the tooth tops 69 of each tooth 60 on the workpiece 8 and the corresponding end faces 9a, 9b of the workpiece are usually chamfered in a separate machining operation.

[0076] During the chamfering operation using the milling cutter 1, the workpiece 8 is attached to a rotatable workpiece holder (not shown) of the machine tool and can be rotated by the machine tool about the central axis 4 of the workpiece 8, wherein the milling cutter 1 is attached to a rotatable tool holder (not shown) of the machine tool and can be rotated about the rotational axis 3 of the tool body 2 and can be moved by the machine tool relative to the workpiece 8 in the axial direction z of the workpiece 8 and in different directions in the planes x, y perpendicular to the central axis 4 of the workpiece 8, wherein the rotational axis 3 of the tool body 2 is parallel to the central axis 4 of the workpiece 8. The rotational speed of the workpiece 8, the rotational speed of the milling cutter 1, and the movement of the milling cutter 1 relative to the workpiece 8 are controlled in a program-controlled manner by an electronic control device (not shown).

[0077] The workpiece holder and the tool holder of the machine tool are usually positioned relative to each other such that the tool holder faces the workpiece holder. In the examples shown in FIGS. 9 - 10 and FIGS. 15 - 16, the end face of the workpiece 8 referred to as the first end face 9a faces the workpiece holder of the machine tool, wherein the opposite second end face 9b of the workpiece 8 faces the tool holder of the machine tool.

[0078] The workpiece 8 can rotate about its central axis 4 in a first rotational direction R1, where the second flank surface 67b of the tooth 60 on the workpiece serves as the front flank surface, and the first flank surface 67a of the tooth 60 on the workpiece serves as the rear flank surface, and the workpiece 8 can rotate about its central axis 4 in an opposite second rotational direction R2, where the first flank surface 67a of the tooth 60 on the workpiece serves as the front flank surface, and the second flank surface 67b of the tooth 60 on the workpiece serves as the rear flank surface.

[0079] To chamfer all the flank edges 61 - 64 of the tooth 60 on the workpiece 8 by means of the milling cutter 1, the following steps are performed: a) Position the milling cutter 1 at a first preset position relative to the workpiece 8, where the rotational axis 3 of the cutter body 2 is parallel to the central axis 4 of the workpiece 8, and the cutting part 10 of the cutter body 2 is adjacent to the first end face 9a of the workpiece 8, and the second cutting edge 12 faces this first end face 9a, as Figure 9a and Figure 15a shown in; b) Thereafter, rotate the milling cutter 1 about the rotational axis 3 of the cutter body 2, and simultaneously, rotate the workpiece 8 about its central axis 4 with a preset relationship between the rotational speed of the milling cutter 1 and the rotational speed of the workpiece 8, while keeping the rotational axis 3 of the cutter body 2 parallel to the central axis 4 of the workpiece 8, and move the milling cutter 1 relative to the workpiece 8 along a preset path, so that the second cutting edge 12 chamfers the first flank edge 61 and the second flank edge 62 of the tooth 60 on the workpiece 8; c) Thereafter, move the milling cutter 1 relative to the workpiece 8 so that the second cutting edge 12 moves out of contact with the workpiece 8; d) Thereafter, move and position the milling cutter 1 relative to the workpiece 8 at a second preset position relative to the workpiece, where the rotational axis 3 of the cutter body 2 is parallel to the central axis 4 of the workpiece 8, and the cutting part 10 of the cutter body 2 is adjacent to the second end face 9b of the workpiece 8, and the first cutting edge 11 faces this second end face 9b, as Figure 10a and Figure 16a shown in; and e) Thereafter, rotate the milling cutter 1 about the rotational axis 3 of the cutter body 2, and simultaneously, rotate the workpiece 8 about its central axis 4 with a preset relationship between the rotational speed of the milling cutter 1 and the rotational speed of the workpiece 8, while keeping the rotational axis 3 of the cutter body 2 parallel to the central axis 4 of the workpiece 8, and move the milling cutter 1 relative to the workpiece 8 along a preset path, so that the first cutting edge 11 chamfers the third flank edge 63 and the fourth flank edge 64 of the tooth 60 on the workpiece 8.

[0080] During the chamfering process in steps b and e described above, a part of the working cutting edge among the first cutting edge 11 and the second cutting edge 12 rotates into the gap between two adjacent teeth 60, and thereafter, during a part of one revolution of the workpiece 8, this part of the working cutting edge moves in the rotational direction of the workpiece 8 together with this gap, while performing cutting engagement with at least one section of one of the flank edges located on opposite sides of this gap, and then this part rotates out of this gap, as Figures 14a - 14e shown in. As the milling cutter 1 continues to rotate, a part of the working cutting edge among the first cutting edge 11 and the second cutting edge 12 rotates into a new gap between another two adjacent teeth 60 on the workpiece 8, and so on. During the continuous rotation of the milling cutter 1 and the workpiece 8, by gradually moving the milling cutter 1 relative to the workpiece 8, thereby changing the distance between the rotational axis 3 of the cutter body 2 and the central axis 4 of the workpiece 8, the working cutting edges 11, 12 can perform cutting engagement with different sections of each flank edge being chamfered at different stages of the chamfering process until these flank edges have been chamfered along their entire extensions.

[0081] In step b, the movement of the milling cutter 1 relative to the workpiece 8 can be started by first moving the milling cutter 1 in its axial direction, so that the second cutting edge 12 moves in the direction towards the first end face 9a of the workpiece 8, so that when the milling cutter 1 rotates, the second cutting edge 12 contacts the workpiece 8. Thereafter, during the remaining stages of step b, the milling cutter 1 can be maintained at this axial position relative to the workpiece 8, so as to achieve a chamfer with a substantially constant width along each flank edge being chamfered. However, during at least a part of the remaining stages of step b, the milling cutter 1 can also move in its axial direction relative to the workpiece 8, so as to achieve a chamfer with a varying width along each flank edge being chamfered.

[0082] In a corresponding manner, in step e, the movement of the milling cutter 1 relative to the workpiece 8 can be started by first moving the milling cutter 1 in its axial direction, so that the first cutting edge 11 moves in the direction towards the second end face 9b of the workpiece 8, so that when the milling cutter 1 rotates, the first cutting edge 11 contacts the workpiece 8. Thereafter, during the remaining stages of step e, the milling cutter 1 can be maintained at this axial position relative to the workpiece 8, so as to achieve a chamfer with a substantially constant width along each flank edge being chamfered. However, during at least a part of the remaining stages of step e, the milling cutter 1 can also move in its axial direction relative to the workpiece 8, so as to achieve a chamfer with a varying width along each flank edge being chamfered.

[0083] The relationship between the rotational speed of the milling cutter 1 and the rotational speed of the workpiece 8 is to be adjusted such that after a certain number of revolutions of the workpiece 8, a part of the working cutting edges 11, 12 has entered the gaps between all the teeth 60 located on the workpiece 8. To allow the working cutting edge to move in the same direction as the gap between two adjacent teeth 60 on the workpiece 8 when a part of the cutting edge is received in the relevant gap, when chamfering the flank edges 61 - 64 of the internal teeth 60 on the workpiece, the milling cutter 1 must rotate about the rotational axis 3 of the tool body 2 in the same rotational direction as the workpiece 8, and when chamfering the flank edges 61 - 64 of the external teeth 60 on the workpiece, the milling cutter 1 must rotate about the rotational axis 3 of the tool body 2 in a rotational direction opposite to the rotational direction of the workpiece 8.

[0084] Preferably, all the flank edges 61 - 64 are chamfered in the machining direction from the tooth root 66 to the tooth tip 65 of the associated tooth 60.

[0085] To achieve chamfering of each of the first flank edge 61 and the second flank edge 62 of the tooth 60 on the workpiece 8 in the machining direction from the tooth root 66 to the tooth tip 65, the above step b includes the following sub - steps: b1) Chamfer the first flank edge 61 of the tooth 60 on the workpiece 8 while rotating the workpiece about its central axis 4 in the above - mentioned first rotational direction R1, and at the same time, when the first flank edge 61 being chamfered is the flank edge of an internal tooth 60 on the workpiece 8, rotate the milling cutter 1 about the rotational axis 3 of the tool body 2 in the same rotational direction R1 as the workpiece 8, or when the first flank edge 61 being chamfered is the flank edge of an external tooth 60 on the workpiece 8, rotate the milling cutter 1 about the rotational axis 3 of the tool body 2 in the opposite rotational direction R2; and b2) Chamfer the second flank edge 62 of the tooth 60 on the workpiece 8 while rotating the workpiece about its central axis 4 in the above - mentioned second rotational direction R2 opposite to the first rotational direction R1, and at the same time, when the second flank edge 62 being chamfered is the flank edge of an internal tooth 60 on the workpiece 8, rotate the milling cutter 1 about the rotational axis 3 of the tool body 2 in the same rotational direction R2 as the workpiece 8, or when the second flank edge 62 being chamfered is the flank edge of an external tooth 60 on the workpiece 8, rotate the milling cutter 1 about the rotational axis 3 of the tool body 2 in the rotational direction opposite to R1.

[0086] To achieve chamfering of each of the third flank edge 63 and the fourth flank edge 64 of the tooth 60 on the workpiece 8 in the machining direction from the tooth root 66 to the tooth tip 65, the above step e includes the following sub - steps: e1) Chamfer the third flank edge 63 of the tooth 60 on the workpiece 8 while rotating the workpiece about its central axis 4 in a first rotational direction R1, and simultaneously, when the third flank edge 63 being chamfered is the flank edge of the internal tooth 60 on the workpiece 8, rotate the milling cutter 1 about the rotational axis 3 of the tool body 2 in the same rotational direction R1 as the workpiece 8, or when the third flank edge 63 being chamfered is the flank edge of the external tooth 60 on the workpiece 8, rotate the milling cutter 1 about the rotational axis 3 of the tool body 2 in the opposite rotational direction R2; and e2) Chamfer the fourth flank edge 64 of the tooth 60 on the workpiece 8 while rotating the workpiece about its central axis 4 in a second rotational direction R2, and when the fourth flank edge 64 being chamfered is the flank edge of the internal tooth 60 on the workpiece 8, rotate the milling cutter 1 about the rotational axis 3 of the tool body 2 in the same rotational direction R2 as the workpiece 8, or when the fourth flank edge 64 being chamfered is the flank edge of the external tooth 60 on the workpiece 8, rotate the milling cutter 1 about the rotational axis 3 of the tool body 2 in the opposite rotational direction R1.

[0087] Of course, the present invention is in no way limited to the above-described embodiments. On the contrary, for those of ordinary skill in the art, many possibilities for modifying the present invention will be apparent without departing from the basic idea of the present invention as defined in, for example, the claims.

Claims

1. A milling cutter for chamfering the flank edges (61 - 64) of internal or external teeth (60) on a cylindrical toothed workpiece (8) located at opposite end faces (9a, 9b) of the workpiece (8), the milling cutter (1) comprising an elongate cutter body (2), the cutter body (2) having a rear part (6) at the rear end (2b), the rear part (6) being configured for attachment to a machine tool, and the cutter body (2) having a cutting part (10) at a certain distance from the rear part (6), the cutting part (10) being provided with cutting edges (11, 12). It is characterized in that: - The cutter body (2) comprises an elongate shank (40), the shank (40) carrying the cutting part (10) and extending from the cutting part (10) towards the rear part (6), the shank (40) having a front end (40a) facing the cutting part (10), an opposite rear end (40b), and an outer peripheral surface (41) extending around the shank (40) between the rear end (40b) and the front end (40a) of the shank, wherein the shank (40) has a longitudinal central axis coinciding with the rotational axis (3) of the cutter body (2); and - The cutting part (10) is provided with at least one pair of cutting edges, the at least one pair of cutting edges comprising a first cutting edge (11) facing away from the rear part (6) and a second cutting edge (12) facing the rear part (6), the second cutting edge (12) being positioned closer to the rear part (6) than the first cutting edge (11), wherein: • The first cutting edge (11) has a rear end (11b) and an opposite front end (11a), the rear end (11b) of the first cutting edge (11) being positioned closer to the rear part (6) of the cutter body than the front end (11a) of the first cutting edge (11), wherein the front end (11a) of the first cutting edge (11) is positioned closer to the rotational axis (3) than the rear end (11b) of the first cutting edge (11), and when viewed in a direction along the first cutting edge (11) from the front end (11a) of the first cutting edge to the rear end (11b) of the first cutting edge, the distance between the first cutting edge (11) and the rotational axis (3) gradually increases, and • The second cutting edge (12) has a front end (12a) and an opposite rear end (12b), and the rear end (12b) of the second cutting edge (12) is positioned closer to the rear portion (6) of the tool body than the front end (12a) of the second cutting edge (12), wherein the rear end (12b) of the second cutting edge (12) is positioned at a greater distance from the rotational axis (3) than the radially outermost portion of the outer peripheral surface (41) of the shank (40), and wherein the rear end (12b) of the second cutting edge (12) is positioned closer to the rotational axis (3) than the front end (12a) of the second cutting edge (12), and the distance between the second cutting edge (12) and the rotational axis (3) gradually increases when viewed in the direction along the second cutting edge (12) from the rear end (12b) of the second cutting edge to the front end (12a) of the second cutting edge; - The cutting portion (10) has an extension in the axial direction of the tool body (2), and the extension is restricted to a region located between a first plane (P1) and a second plane (P2), the first plane (P1) extending perpendicular to the rotational axis (3) and intersecting the rear end (12b) of the second cutting edge (12), and the second plane (P2) extending perpendicular to the rotational axis (3) and intersecting the front end (11a) of the first cutting edge (11); and - The cutting portion (10) constitutes the axially foremost portion of the tool body (2), or the tool body (2) includes a front portion (7) that projects from the cutting portion (10) on the side of the cutting portion (10) facing away from the rear portion (6), wherein the front end (11a) of the first cutting edge (11) is positioned at a greater distance from the rotational axis (3) than the radially outermost portion of the front portion (7).

2. The milling cutter according to claim 1, characterized in that: - The first cutting edge (11) extends substantially linearly in a third plane (P3) containing the rotational axis; and - The second cutting edge (12) extends substantially linearly within a fourth plane (P4) containing the rotational axis (3), and preferably, the fourth plane (P4) coincides with the third plane (P3).

3. The milling cutter according to claim 2, characterized in that: - The first cutting edge (11) has an inclination in the third plane (P3) such that the extension of the first cutting edge (11) forms a first angle (α 1 ) with the rotational axis (3), the first angle (α 1 ) being greater than or equal to 20° and less than 90°, preferably 30° - 80°; and - The second cutting edge (12) has an inclination in the fourth plane (P4) such that the extension of the second cutting edge (12) forms a second angle (α 2 ) with the rotation axis (3), the second angle (α 2 ) being greater than or equal to 20° and less than 90°, preferably 30° - 80°, wherein preferably, the first angle (α 1 ) and the second angle (α 2 ) are substantially equal.

4. The milling cutter according to any one of claims 1 to 3, characterized in that: - The first cutting edge (11) is formed at the intersection between a first surface (31) on the cutting portion (10) and a second surface (32) on the cutting portion (10), wherein the first surface (31) and the second surface (32) are mirror-symmetrical to each other with respect to the third plane (P3); and - The second cutting edge (12) is formed at the intersection between a third surface (33) on the cutting portion (10) and a fourth surface (34) on the cutting portion (10), wherein the third surface (33) and the fourth surface (34) are mirror-symmetrical to each other with respect to the fourth plane (P4).

5. The milling cutter according to any one of claims 1 to 4, characterized in that the first cutting edge (11) and the second cutting edge (12) are mirror-symmetrical to each other with respect to a symmetry plane (PS) that extends perpendicular to the rotational axis (3) midway between the first cutting edge (11) and the second cutting edge (12).

6. The milling cutter according to any one of claims 1 to 5, characterized in that the radial distance (r) between the rear end (12b) of the second cutting edge (12) and the radially outermost part of the outer peripheral surface (41) of the shank (40) is 2 - 40 mm, preferably 6 - 30 mm.

7. The milling cutter according to any one of claims 1 to 6, characterized in that the cutting portion (10) includes a retainer arm (15) that projects radially beyond the radially outermost part of the outer peripheral surface (41) of the shank (40) relative to the rotational axis (3), wherein the retainer arm (15) has an inner end (15a) facing the rotational axis (3) and an opposite outer end (15b), and wherein the first cutting edge (11) and the second cutting edge (12) are arranged at the outer end (15b) of the retainer arm (15).

8. The milling cutter according to claim 7, characterized in that the first cutting edge (11) and the second cutting edge (12) form part of a cutting insert (16) that is releasably mounted to a blade seat (17) provided at the outer end (15b) of the retainer arm (15).

9. The milling cutter according to claim 7 or 8, characterized in that the cutting portion (10) includes a base (14) that carries the retainer arm (15) and is slidably mounted to the shank (40) at the front end (40a) of the shank (40) so as to be able to linearly slide relative to the shank (40) perpendicular to the rotational axis (3) and in the longitudinal direction of the retainer arm (15), wherein the base (14) can be locked to the shank (40) at different sliding positions relative to the shank (40), thereby allowing adjustment of the radial distance between the first cutting edge (11) and the rotational axis (3) and the radial distance between the second cutting edge (12) and the rotational axis (3).

10. The milling cutter according to any one of claims 1 to 9, characterized in that the shank (40) is rod-shaped.

11. The milling cutter according to any one of claims 1 to 10, It is characterized in that the length (L) of the shank (40) is 25 - 500 mm, preferably 50 - 200 mm, more preferably 100 - 150 mm.

12. The milling cutter according to any one of claims 1 to 11, It is characterized in that the cutting part (10) is detachably mounted to the shank (40) at the front end (40a) of the shank (40).

13. A method for chamfering the tooth flank edges (61 - 64) of internal or external teeth (60) on a cylindrical toothed workpiece (8) located at the first end face (9a) of the workpiece (8) and at the opposite second end face (9b) of the workpiece (8), wherein each tooth (60) on the workpiece (8) has a tooth tip (65), a tooth root (66), a first tooth flank surface (67a) extending between the tooth tip (65) and the tooth root (66) on the first side of the tooth, and a second tooth flank surface (67b) extending between the tooth tip (65) and the tooth root (66) on the opposite second side of the tooth, a first tooth flank edge (61) is formed at the intersection between the first tooth flank surface (67a) and the first end face (9a) of the workpiece (8), a second tooth flank edge (62) is formed at the intersection between the second tooth flank surface (67b) and the first end face (9a) of the workpiece (8), a third tooth flank edge (63) is formed at the intersection between the first tooth flank surface (67a) and the second end face (9b) of the workpiece (8), and a fourth tooth flank edge (64) is formed at the intersection between the second tooth flank surface (67b) and the second end face (9b) of the workpiece (8), wherein the workpiece (8) is attached to a machine tool, and the workpiece (8) can be rotated about the central axis (4) of the workpiece (8) by the machine tool, and wherein the chamfering is carried out by means of the milling cutter (1) according to any one of claims 1 to 12, the milling cutter (1) is attached to the machine tool, and the milling cutter (1) can be rotated about the rotation axis (3) of the tool body (2) by the machine tool, and the milling cutter (1) can be moved by the machine tool relative to the workpiece (8) in the axial direction (z) of the workpiece (8) and in different directions in a plane (x, y) perpendicular to the central axis (4) of the workpiece (8), wherein the rotation axis (3) of the tool body (2) is parallel to the central axis (4) of the workpiece (8), the method comprises the following steps: a) Position the milling cutter (1) in a first preset position relative to the workpiece (8), where the rotational axis (3) of the cutter body (2) is parallel to the central axis (4) of the workpiece (8), and the cutting portion (10) of the cutter body (2) is adjacent to the first end face (9a) of the workpiece (8), and one of the first cutting edge (11) and the second cutting edge (12) of the at least one pair of cutting edges faces the first end face (9a); b) Rotate the milling cutter (1) about the rotational axis (3) of the cutter body (2), and simultaneously, rotate the workpiece (8) about the central axis (4) of the workpiece at a preset relationship between the rotational speed of the milling cutter (1) and the rotational speed of the workpiece (8), while maintaining the rotational axis (3) of the cutter body (2) parallel to the central axis (4) of the workpiece (8), and move the milling cutter (1) relative to the workpiece (8) along a preset path, so that the cutting edge facing the first end face (9a) of the workpiece (8) chamfers the first tooth side edge (61) and the second tooth side edge (62) of the tooth (60) on the workpiece (8); c) Move the milling cutter (1) relative to the workpiece (8) so that the cutting edge facing the first end face (9a) of the workpiece (8) moves out of contact with the workpiece (8); d) Move the milling cutter (1) relative to the workpiece (8) to a second preset position, where the rotational axis (3) of the cutter body (2) is parallel to the central axis (4) of the workpiece (8), and the cutting portion (10) of the cutter body (2) is adjacent to the opposite second end face (9b) of the workpiece (8), and the other of the first cutting edge (11) and the second cutting edge (12) of the at least one pair of cutting edges faces the second end face (9b); and e) Rotate the milling cutter (1) about the rotational axis (3) of the cutter body (2), and simultaneously, rotate the workpiece (8) about the central axis (4) of the workpiece at a preset relationship between the rotational speed of the milling cutter (1) and the rotational speed of the workpiece (8), while maintaining the rotational axis (3) of the cutter body (2) parallel to the central axis (4) of the workpiece (8), and move the milling cutter (1) relative to the workpiece (8) along a preset path, so that the cutting edge facing the second end face (9b) of the workpiece (8) chamfers the third tooth side edge (63) and the fourth tooth side edge (64) of the tooth (60) on the workpiece (8).

14. The method according to claim 13, wherein in step b, the preset path for the milling cutter (1) to move relative to the workpiece (8) includes at least one portion in which the milling cutter (1) moves in the axial direction of the milling cutter, so that the cutting edge facing the first end face (9a) of the workpiece (8) moves in the direction towards the first end face (9a), and / or wherein in step e, the preset path for the milling cutter (1) to move relative to the workpiece (8) includes at least one portion in which the milling cutter (1) moves in the axial direction of the milling cutter, so that the cutting edge facing the second end face (9b) of the workpiece (8) moves in the direction towards the second end face (9b).

15. The method according to claim 13 or 14, wherein in step b, the preset path for the milling cutter (1) to move relative to the workpiece (8) includes at least one portion in which the distance between the rotational axis (3) of the tool body (2) and the central axis (4) of the workpiece (8) changes, and / or wherein in step e, the preset path for the milling cutter (1) to move relative to the workpiece (8) includes at least one portion in which the distance between the rotational axis (3) of the tool body (2) and the central axis (4) of the workpiece (8) changes.

16. The method according to any one of claims 13 to 15, wherein: - in step b, the first tooth side edge (61) and the second tooth side edge (62) of the tooth (60) on the workpiece (8) are each chamfered in the machining direction from the tooth root (66) to the tooth tip (65) of the associated tooth (60), and - in step e, the third tooth side edge (63) and the fourth tooth side edge (64) of the tooth (60) on the workpiece (8) are each chamfered in the machining direction from the tooth root (66) to the tooth tip (65) of the associated tooth (60).

17. The method according to claim 16, wherein step b includes the following sub-steps: b1) Chamfer the first flank edge (61) of the tooth (60) on the workpiece (8) while rotating the workpiece (8) about the central axis (4) of the workpiece in a first rotational direction (R1), wherein the second flank surface (67b) is the front flank surface and the first flank surface (67a) is the rear flank surface, and simultaneously, when the first flank edge (61) being chamfered is the flank edge of an internal tooth (60) on the workpiece (8), rotate the milling cutter (1) about the rotational axis (3) of the tool body (2) in the same rotational direction (R1) as the workpiece (8), or when the first flank edge (61) being chamfered is the flank edge of an external tooth (60) on the workpiece (8), rotate the milling cutter (1) about the rotational axis (3) of the tool body (2) in a rotational direction (R2) opposite thereto, and b2) Chamfer the second flank edge (62) of the tooth (60) on the workpiece (8) while rotating the workpiece (8) about the central axis (4) of the workpiece in a second rotational direction (R2) opposite to the first rotational direction (R1), and simultaneously, when the second flank edge (62) being chamfered is the flank edge of an internal tooth (60) on the workpiece (8), rotate the milling cutter (1) about the rotational axis (3) of the tool body (2) in the same rotational direction (R2) as the workpiece (8), or when the second flank edge (62) being chamfered is the flank edge of an external tooth (60) on the workpiece (8), rotate the milling cutter (1) about the rotational axis (3) of the tool body (2) in a rotational direction (R1) opposite thereto.

18. The method according to claim 17, wherein step e comprises the following sub-steps: e1) Chamfer the third flank edge (63) of the tooth (60) on the workpiece (8) while rotating the workpiece (8) about the central axis (4) of the workpiece in the first rotational direction (R1), and simultaneously, when the third flank edge (63) being chamfered is the flank edge of an internal tooth (60) on the workpiece (8), rotate the milling cutter (1) about the rotational axis (3) of the tool body (2) in the same rotational direction (R1) as the workpiece (8), or when the third flank edge (63) being chamfered is the flank edge of an external tooth (60) on the workpiece (8), rotate the milling cutter (1) about the rotational axis (3) of the tool body (2) in a rotational direction (R2) opposite thereto, and e2) Chamfer the fourth flank edge (64) of the tooth (60) on the workpiece (8), while rotating the workpiece (8) about the central axis (4) of the workpiece in the second rotational direction (R2), and simultaneously, when the fourth flank edge (64) being chamfered is the flank edge of an internal tooth (60) on the workpiece (8), rotate the milling cutter (1) about the rotational axis (3) of the tool body (2) in the same rotational direction (R2) as the workpiece (8), or when the fourth flank edge (64) being chamfered is the flank edge of an external tooth (60) on the workpiece (8), rotate the milling cutter (1) about the rotational axis (3) of the tool body (2) in the opposite rotational direction (R1).

19. A computer program having instructions which, when executed by a CNC machine tool, cause the CNC machine tool to perform the steps according to any one of claims 13 to 18.

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