Method for chamfering side edges of teeth on a cylindrical toothed workpiece

Abstract

A method for chamfering side edges (61, 62) of teeth of a cylindrical toothed workpiece (8) at an end face (9a) of the workpiece (8) by means of at least one milling tool (1), wherein the workpiece (8) and milling tool (1) are rotated with a predetermined relationship between the rotational speed of the milling tool and the rotational speed of the workpiece and such that the rotational axis of the milling tool is parallel to the central axis (4) of the workpiece, and the milling tool is moved along a predetermined path relative to the workpiece such that each of the side edges (61, 62) of this first end face (9a) of the workpiece (8) is chamfered in the machining direction from the root to the tip of the associated tooth.

Description

[Technical Field]

[0001] The present invention relates to a method for chamfering the side edges of the internal or external teeth of a cylindrical toothed workpiece on at least one of two opposite end faces of the workpiece.

[0002] External or internal teeth or splined teeth may be machined on a cylindrical workpiece by cutting techniques using different types of cutting tools. In such cases, the resulting teeth on the workpiece have burrs and sharp edges at the intersections of the tooth flanks with the respective end faces of the workpiece following the initial machining operation, i.e., at the side edges of the teeth on the opposite end faces of the workpiece. Therefore, a subsequent finishing operation may be required to chamfer the side edges of the teeth on the opposite end faces of the workpiece, thereby removing the burrs and sharp edges.

[0003] WO 2022 / 013068 discloses a method for chamfering side edges of teeth on a cylindrical toothed workpiece at an end surface of the workpiece using a milling tool, where the workpiece and milling tool are rotated at a predetermined relationship between the rotational speed of the milling tool and the rotational speed of the workpiece while maintaining the rotational axis of the milling tool parallel to the central axis of the workpiece. In the method according to WO 2022 / 013068, the side edges are chamfered such that a first side edge of the tooth is chamfered in a direction from the tip to the root of the tooth, and as a result, a second opposite side edge of the adjacent tooth is chamfered in a direction from the root to the tip of the tooth. The milling tool disclosed in WO 2022 / 013068 is configured to move into contact with the forward-facing end surface of the workpiece. If the side edge of the first, forward-facing end face of the workpiece is being chamfered, the workpiece must be repositioned in the workpiece holder so that the opposite, second end face of the workpiece faces forward toward the milling tool before proceeding with the chamfering of the side edge of this second end face of the workpiece.

[0004] Problem to be solved by the invention The object of the present invention is to achieve a further development of the above-mentioned type of method for chamfering the side edges of teeth on a cylindrical toothed workpiece, to provide an improved method at least in some aspects. Summary of the Invention

[0005] According to a first aspect of the invention, the object is achieved by a method having the features defined in claim 1.

[0006] A first aspect of the present invention provides a method for chamfering side edges of internal or external teeth on a cylindrical toothed workpiece on at least one of two opposing end faces of the workpiece, each tooth having a tip, a root, a first tooth flank extending between the tip and the root on a first side of the tooth, and a second tooth flank extending between the tip and the root on an opposite second side of the tooth, the first side edge being formed at an intersection of the first tooth flank and a first one of the two end faces of the workpiece, the second side edge being formed at an intersection of the second tooth flank and a first tooth flank of the two end faces of the workpiece, a third side edge being formed at an intersection of the first tooth flank and a second tooth flank of the two end faces of the workpiece, and a fourth side edge being formed at an intersection of the second tooth flank and a and the second tooth flanks of the two end faces of the workpiece, the workpiece is rotatable by a machine about a central axis of the workpiece, the chamfering is performed by one or more milling tools, each of the one or more milling tools includes a tool body and one or more cutting edges provided on the tool body, each of the one or more milling tools is rotatable by the machine about a rotation axis of the tool body and is movable relative to the workpiece in an axial direction of the workpiece, and is movable by the machine relative to the workpiece in different directions in a plane perpendicular to the central axis of the workpiece such that the rotation axis of the tool body is parallel to the central axis of the workpiece, and the method comprises: a) rotating the workpiece in a rotational direction about a central axis of the workpiece, with the second tooth flank as a leading tooth flank and the first tooth flank as a trailing tooth flank, with a predetermined relationship between the rotational speed of the milling tool and the rotational speed of the workpiece, in the same rotational direction as the workpiece when the tooth is an internal tooth on the workpiece, or in a rotational direction opposite to the rotational direction when the tooth is an external tooth on the workpiece, and simultaneously rotating one of the one or more milling tools about the rotational axis of the tool body, while maintaining the rotational axis of the tool body parallel to the central axis of the workpiece, moving the milling tool along a predetermined path relative to the workpiece so that at least one of the one or more cutting edges of the milling tool faces a first of two end faces of the workpiece, whereby the at least one cutting edge chamfers a first side edge of each tooth in a machining direction from the root to the tip of the tooth; b) rotating the workpiece in a rotational direction with the first tooth flank as a leading tooth flank and the second tooth flank as a trailing tooth flank, with a predetermined relationship between the rotational speed of the milling tool and the rotational speed of the workpiece, in the same rotational direction as the workpiece when the tooth is an internal tooth on the workpiece, or in a rotational direction opposite to the rotational direction when the tooth is an external tooth on the workpiece, and simultaneously rotating one of the one or more milling tools about the rotational axis of the tool body, and while maintaining the rotational axis of the tool body parallel to the central axis of the workpiece, moving the milling tool along a predetermined path relative to the workpiece so that at least one of the one or more cutting edges of the milling tool faces a first of two end faces of the workpiece, whereby the at least one cutting edge chamfers the second side edge of the tooth in a machining direction from the root to the tip of each tooth.

[0007] Thus, the chamfering of each of the first and second side edges on the aforementioned first end face of the workpiece begins at the deepest part of the gap between the two teeth, i.e., the so-called bottom land or root surface of the tooth, and ends at the tip of the associated tooth. It has been found that chamfering the side edges in the machining direction from the tooth tip to the root can result in burrs in the root area, especially on cutting edges that have begun to wear after extended use. It has also been found that chamfering the side edges in the opposite machining direction from the root to the tooth tip can prevent such burrs from occurring. Therefore, chamfering each side edge on the first end face of the workpiece in the machining direction from the root to the tip of the associated tooth improves the quality of the chamfers produced on these side edges.

[0008] In this specification and in the claims that follow, the expression "leading tooth flank" refers to the tooth flank that faces in the direction of rotation, i.e., forward, as the toothed workpiece rotates about its central axis, and the expression "trailing tooth flank" refers to the tooth flank that faces in the opposite direction, i.e., backward, as the toothed workpiece rotates about its central axis.

[0009] According to one embodiment of the present invention, the predetermined path for the movement of the milling tool relative to the workpiece in step a includes at least one portion in which the milling tool moves in its axial direction, thereby moving one or more cutting edges facing a first of the two end faces of the workpiece in a direction towards this end face, and / or the predetermined path for the movement of the milling tool relative to the workpiece in step b includes at least one portion in which the milling tool moves in its axial direction, thereby moving one or more cutting edges facing a first of the two end faces of the workpiece in a direction towards this end face.

[0010] According to another embodiment of the present invention, the predetermined path for movement of the milling tool relative to the workpiece in step a includes at least one portion where the distance between the rotation axis of the tool body and the central axis of the workpiece is changed, and / or the predetermined path for movement of the milling tool relative to the workpiece in step b includes at least one portion where the distance between the rotation axis of the tool body and the central axis of the workpiece is changed. The change in the distance between the rotation axis of the tool body and the central axis of the workpiece can be achieved by moving the milling tool in a direction perpendicular to the rotation axis of the tool body and / or by moving the workpiece in a direction perpendicular to the central axis of the workpiece.

[0011] The predetermined path for the movement of the milling tool relative to the workpiece in step a and / or step b may of course also include one or more parts in which the distance between the rotation axis of the tool body and the central axis of the workpiece is changed while the milling tool is moved in its axial direction.

[0012] According to another embodiment of the present invention, the method comprises: c) rotating the workpiece about its central axis in a rotational direction with the second tooth flank as a leading tooth flank and the first tooth flank as a trailing tooth flank, in the same rotational direction as the workpiece when the tooth is an internal tooth on the workpiece, or in the opposite rotational direction when the tooth is an external tooth on the workpiece; simultaneously rotating one or more milling tools about the rotational axis of the tool body with a predetermined relationship between the rotational speed of the milling tool and the rotational speed of the workpiece; and simultaneously rotating one of the one or more milling tools about the rotational axis of the tool body, while maintaining the rotational axis of the tool body parallel to the central axis of the workpiece, moving the milling tool along a predetermined path relative to the workpiece so that at least one of the one or more cutting edges of the milling tool faces a second of the two end faces of the workpiece, whereby the at least one cutting edge chamfers a third side edge of the tooth in a machining direction from the root to the tip of each tooth; d) rotating the workpiece in a rotational direction with the first tooth flank as a leading tooth flank and the second tooth flank as a trailing tooth flank, with a predetermined relationship between the rotational speed of the milling tool and the rotational speed of the workpiece, in the same rotational direction as the workpiece when the tooth is an internal tooth on the workpiece, or in a rotational direction opposite to the rotational direction when the tooth is an external tooth on the workpiece, and simultaneously rotating one of the one or more milling tools about the rotational axis of the tool body, and while maintaining the rotational axis of the tool body parallel to the central axis of the workpiece, moving the milling tool along a predetermined path relative to the workpiece so that at least one of the one or more cutting edges of the milling tool faces a second of the two end faces of the workpiece, whereby the at least one cutting edge chamfers a fourth side edge of the tooth in a machining direction from the root to the tip of each tooth.

[0013] This causes each side edge of the second end face of the workpiece to also be chamfered in the machining direction from the root to the tip of the associated tooth, thereby improving the quality of the chamfer produced on these side edges.

[0014] According to another embodiment of the present invention, the workpiece is rotated in a first rotational direction in step a, and in step b, rotated in a second rotational direction opposite to the first rotational direction, while maintaining the same orientation as in step a, so that the first and second side edges of the first end face of the workpiece are chamfered in the machining direction from the root to the tip of the tooth in steps a and b, without requiring repositioning of the workpiece between these steps.

[0015] According to another embodiment of the present invention, The chamfering in step a and the chamfering in step b are performed by one and the same milling tool, the milling tool including at least one first cutting edge facing a first end face of two end faces of the workpiece, chamfering the first and second side edges of the tooth in steps a and b, and a tool body of the milling tool at a rear end has a rear portion configured for attachment to a machine; At least one first cutting edge extends substantially linearly in a plane including the rotation axis of the tool body of the milling tool and is formed at the intersection of a first surface and a second surface on a cutting insert releasably mounted in an insert seat provided in the tool body, the first surface functioning as a rake surface and the second surface functioning as a clearance surface when the milling tool is rotated in one direction about the rotation axis of the tool body and a chamfer is performed by the at least one first cutting edge, while the second surface functioning as a rake surface when the milling tool is rotated in another opposite rotation direction about the rotation axis of the tool body and a chamfer is performed by the at least one first cutting edge.

[0016] The chamfering of the first side edge in step a and the chamfering of the second side edge in step b are preferably performed by one and the same milling tool, however, it would alternatively be possible to perform the chamfering of the first side edge in step a using a first milling tool with cutting edges adapted for milling in only one rotational direction, and the chamfering of the second side edge in step b using a second milling tool with cutting edges adapted for milling in only the opposite rotational direction.

[0017] According to another embodiment of the invention, the first and second surfaces are mirror images of each other with respect to a plane in which the at least one first cutting edge extends, so that the cutting performance of this first cutting edge is the same in both rotation directions of the milling tool.

[0018] According to another embodiment of the present invention, at least one first cutting edge has a leading end and an opposite trailing end, the trailing end of the at least one first cutting edge being located closer to the rear of the tool body than the leading end of the at least one first cutting edge, the leading end of the at least one first cutting edge being located closer to the axis of rotation of the tool body than the trailing end of the at least one first cutting edge, and the distance between the at least one first cutting edge and the axis of rotation of the tool body gradually increases from the leading end to the trailing end as viewed in a direction along the at least one first cutting edge. The at least one first cutting edge preferably has an inclination in a plane extending such that an extension of the at least one first cutting edge forms an angle with the axis of rotation of the tool body of 20° to 90°, preferably 30 to 80°.

[0019] According to another embodiment of the present invention, The chamfering in step c and the chamfering in step d are performed by the same milling tool as the chamfering in steps a and b; the milling tool includes at least one second cutting edge facing a second end surface of the two end surfaces of the workpiece, and chamfers the third and fourth side edges of the tooth in steps c and d; the at least one first cutting edge faces in a direction away from a rear portion of the tool body, and the at least one second cutting edge faces the rear portion of the tool body and is located closer to the rear than the at least one first cutting edge; at least one second cutting edge extends substantially linearly in a plane including the rotation axis of the tool body and is formed at an intersection of the third surface and the fourth surface on the cutting insert, the third surface acting as a rake surface and the fourth surface acting as a clearance surface when the milling tool is rotated in one rotational direction about the rotation axis of the tool body and a chamfer is performed by the at least one second cutting edge, while the third surface acting as a rake surface and the fourth surface acting as a clearance surface when the milling tool is rotated in another opposite rotational direction about the rotation axis of the tool body and a chamfer is performed by the at least one second cutting edge; the tool body includes a cutting portion located away from the rear portion, an elongated shank portion supporting the cutting portion and extending from the cutting portion toward the rear portion and having a front end facing the cutting portion, an opposite rear end, and a circumferential surface extending around the shank portion between the rear ends, the shank portion having a central longitudinal axis coincident with a rotational axis of the tool body; At least one second cutting edge is arranged so as to be farther away from the rotation axis of the tool body than the radially outermost portion of the circumferential surface of the shank portion.

[0020] According to a first alternative, the cutting part constitutes the axially frontmost part of the tool body, i.e. the part of the tool body furthest from the rear part of the tool body. According to a second alternative, the tool body comprises a front part projecting from the cutting part on a side facing away from the rear part, the front end of the first cutting edge being located at a greater distance from the axis of rotation than the radially outermost part of this front part.

[0021] The design of the tool body with an elongated shank portion between the cutting portion and the rear portion, the arrangement of the first and second cutting edges on the cutting portion as defined above, and the position of the second cutting edge relative to the circumferential surface of the shank portion as defined above mean that the milling tool can be used to chamfer the side edges of internal or external teeth on a cylindrical toothed workpiece at both end faces of the workpiece without the need to reposition the workpiece. Thus, the workpiece remains clamped in the appropriate workpiece holder of the machine in one and the same orientation during the entire chamfering process, saving time. The first cutting edge may be used to chamfer the side edges of the teeth of the toothed workpiece on the end face of the workpiece opposite the workpiece holder carrying the workpiece, and the second cutting edge may be used to chamfer the side edges of the teeth of the workpiece on the opposite end face of the workpiece. The chamfering process can begin with chamfering the side edge on the end face of the workpiece facing away from the workpiece holder, and then proceed to chamfering the side edge on the end face of the workpiece facing the workpiece holder.Alternatively, the chamfering process can begin with chamfering the side edge on the end face of the workpiece facing the workpiece holder, and then proceed to chamfering the side edge on the end face of the workpiece facing away from the workpiece holder.

[0022] The plane in which the second cutting edge extends may be angularly offset relative to the axis of rotation from the plane in which the first cutting edge extends, but preferably the plane in which the second cutting edge extends coincides with the plane in which the first cutting edge extends.

[0023] The shank is preferably rod-shaped and is longer than the length of the workpiece, i.e., longer than the axial distance between two opposing end faces of the workpiece. The shank may have a length of, for example, 25 to 500 mm, preferably 50 to 200 mm, and more preferably 100 to 150 mm.

[0024] According to another embodiment of the invention, the third and fourth surfaces are mirror images of each other with respect to a plane in which the at least one second cutting edge extends, so that the cutting performance of this second cutting edge is the same in both rotation directions of the milling tool.

[0025] According to another embodiment of the present invention, at least one second cutting edge has a leading end and an opposite trailing end, the trailing end of the at least one second cutting edge being located closer to the rear of the tool body than the leading end of the at least one second cutting edge, the trailing end of the at least one second cutting edge being located closer to the rotation axis of the tool body than the leading end of the at least one second cutting edge, and the distance between the at least one second cutting edge and the rotation axis of the tool body gradually increases from the trailing end to the leading end, as viewed in a direction along the at least one second cutting edge. The at least one second cutting edge preferably has an inclination in a plane extending such that the extension of the second cutting edge forms an angle with the rotation axis of the tool body of 20° or more and less than 90°, preferably 30 to 80°. The radial distance between the trailing end of the second cutting edge and the radially outermost portion of the circumferential surface of the shank portion should be appropriately adapted to the tooth depth of the teeth on the toothed workpiece to be machined, and is preferably 2 to 40 mm, preferably 6 to 30 mm. The radial distance has the advantage of being greater than the tooth depth, but alternatively may be somewhat less than the tooth depth, taking into account the radial extension of the second cutting edge.If the tool body includes a forward portion projecting from the cutting part opposite the rear portion, the radial distance between the front end of the first cutting edge and the radially outermost part of the circumferential surface of this forward portion is preferably 2 to 40 mm, more preferably 6 to 30 mm, and is preferably, although not necessarily, equal to the radial distance between the rear end of the second cutting edge and the radially outermost part of the circumferential surface of the shank portion.

[0026] The first cutting edge and the second cutting edge are preferably mirror images of each other with respect to a plane of symmetry that extends midway between the first cutting edge and the second cutting edge perpendicular to the axis of rotation of the tool body.

[0027] The above-mentioned internal or external teeth on the workpiece are preferably gear teeth or spline teeth with modules 2-12.

[0028] According to a second aspect, the present invention relates to a computer-based program having instructions which, when executed by a CNC machine, cause the CNC machine to perform the steps of any of the methods described above. 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.

[0029] Further advantages of the method of the present invention will become apparent from the following description.

[0030] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. [Brief explanation of the drawings]

[0031] [Figure 1] FIG. 1 is a perspective view of a milling tool suitable for use in a method according to an embodiment of the present invention. [Figure 2] FIG. 2 is a side view of the milling tool of FIG. 1. [Figure 3] FIG. 2 is a front view of the milling tool of FIG. 1. [Figure 4a] 2 is an exploded perspective view of a portion of the milling tool of FIG. 1 from a different direction. [Figure 4b] 2 is an exploded perspective view of a portion of the milling tool of FIG. 1 from a different direction. [Figure 5] FIG. 2 is a rear view of a cutting component included in the milling tool of FIG. 1. [Figure 6] FIG. 6 is a side view of the cutting component of FIG. 5. [Figure 7] FIG. 6 is a perspective view of the cutting component of FIG. 5. [Figure 8] FIG. 6 is a plan view of the cutting part of FIG. 5. [Figure 9a]2 is a perspective view of the milling tool and internally toothed workpiece of FIG. 1 when the milling tool is in a position to chamfer a side edge at a first end face of the workpiece; FIG. [Figure 9b] 2 is another perspective view of the milling tool and internally toothed workpiece of FIG. 1 when the milling tool is in position to chamfer a side edge at a first end face of the workpiece; FIG. [Figure 9c] FIG. 9C is a front view of the milling tool and workpiece of FIGS. 9a and 9b. [Figure 10a] 9a-9c, respectively, when the milling tool is in a position for chamfering a side edge at an opposite second end surface of the workpiece according to a first variant. [Figure 10b] FIG. 10b is a front view of the milling tool and workpiece of FIG. 10a. [Figure 11a] 9a-9c , a perspective view from one direction of the milling tool and workpiece when the milling tool is in a position for chamfering the side edge of the second end face of the workpiece according to an alternative second modification; [Figure 11b] 9a to 9c are perspective views from another direction of the milling tool and workpiece when the milling tool is in a position for chamfering the side edge of the second end face of the workpiece according to an alternative second variant. [Figure 11c] FIG. 11B is a front view of the milling tool and workpiece of FIGS. 11a and 11b. [Figure 12] FIG. 12 is an enlarged perspective view of a portion of the internally toothed workpiece of FIGS. 9 to 11. [Figure 13] FIG. 12 is an enlarged front view of a portion of the internally toothed workpiece of FIGS. 9 to 11. [Figure 14a] 12 is a partial cutaway side view of the milling tool and a portion of the workpiece of FIGS. 9-11 when the milling tool is in the position shown in FIGS. 9a-9c. [Figure 14b] 12 is a partial cutaway side view of a portion of the milling tool and workpiece of FIGS. 9-11 when the milling tool is in the position shown in FIGS. 10a and 10b. FIG. [Figure 15a] 2A-2C are diagrams of stages in the process of chamfering side edges on an internally toothed workpiece using the milling tool of FIG. 1; [Figure 15b] 2A-2C are diagrams of stages in the process of chamfering side edges on an internally toothed workpiece using the milling tool of FIG. 1; [Figure 15c] 2A-2C are diagrams of stages in the process of chamfering side edges on an internally toothed workpiece using the milling tool of FIG. 1; [Figure 15d] 2A-2C are diagrams of stages in the process of chamfering side edges on an internally toothed workpiece using the milling tool of FIG. 1; [Figure 15e] 2A-2C are diagrams of different stages in the process of chamfering a side edge on an internally toothed workpiece using the milling tool of FIG. 1; [Figure 16a] 2 is a perspective view of the milling tool and externally toothed workpiece of FIG. 1 when the milling tool is in a position to chamfer a side edge at a first end face of the workpiece; FIG. [Figure 16b] 2 is another perspective view of the milling tool and externally toothed workpiece of FIG. 1 when the milling tool is in position to chamfer a side edge at a first end face of the workpiece. FIG. [Figure 16c] FIG. 16c is a front view of the milling tool and workpiece of FIGS. 16a and 16b. [Figure 17a] 16a-16c when the milling tool is in position to chamfer a side edge at an opposite second end surface of the workpiece. FIG. [Figure 17b] FIG. 17b is a front view of the milling tool and workpiece of FIG. 17a. [Figure 18] FIG. 10 is a side view of a milling tool according to an alternative modification. DETAILED DESCRIPTION OF THE INVENTION

[0032] An embodiment of a milling tool 1 suitable for use in the method according to the present invention is shown in FIGS. 1-8. The milling tool 1 is intended for use in chamfering the lateral edges of internal or external teeth on a cylindrical toothed workpiece at the opposite end faces of the workpiece. The milling tool 1 includes an elongated tool body 2 configured to rotate about a rotation axis 3. The tool body 2 has a front end 2a and an opposite rear end 2b. In the illustrated embodiment, the tool body 2 is provided with a collar 5. A rear portion 6 of the tool body 2, located between the collar 5 and the rear end 2b, forms a connecting member through which the tool body 2 can be attached, either directly or via an intermediate tool holder, to a rotating spindle or the like of a machine, such as a milling machine. In the illustrated embodiment, the rear portion 6 is Coromant Capto®, size C8. Other Coromant Capto® sizes that can be used are sizes C3-C10. The rear portion 6 may also be any other connecting member suitable for such purposes, such as an HSK.

[0033] The tool body 2 includes a cutting portion 10 located away from the rear portion 6 and provided with cutting edges 11, 12. The tool body 2 further includes an elongated shank portion 40 supporting the cutting portion 10 and extending from the cutting portion 10 toward the rear portion 6. The shank portion 40 has a front end 40a facing the cutting portion 10 and an opposite rear end 40b facing the collar 5 and the rear portion 6. The cutting portion 10 is attached to the shank portion 40 at its front end 40a. The shank portion 40 has a peripheral surface 41 extending around the shank portion 40 between its rear end 40b and the front end 40a. The shank portion 40 has a longitudinal center axis that coincides with the rotation axis 3 of the tool body 2.

[0034] The cutting portion 10 is provided with a pair of cutting edges, including a first cutting edge 11 facing away from the rear portion 6 of the tool body and a second cutting edge 12 facing the rear portion 6 of the tool body and positioned closer to the rear portion 6 than the first cutting edge 11. Therefore, the first cutting edge 11 is farther from the rear portion 6 of the tool body than the second cutting edge 12. The first and second cutting edges 11, 12 each have 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 portion 6 of the tool body than the front end 11a of the first cutting edge, 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. As shown in FIGS. 2 and 6 , the leading end 11a of the first cutting edge 11 is located closer to the rotation axis 3 than the trailing end 11b of the first cutting edge 11, and the distance between the first cutting edge 11 and the rotation axis 3 gradually increases from the leading end 11a to the trailing end 11b of the first cutting edge 11, as viewed in a direction along the first cutting edge 11. The trailing end 12b of the second cutting edge 12 is located closer to the rotation axis 3 than the leading end 12a of the second cutting edge 12, and the distance between the second cutting edge 12 and the rotation axis 3 gradually increases from the trailing end 12b to the leading end 12a of the second cutting edge 12, as viewed in a direction along the second cutting edge 12. Furthermore, the trailing end 12b of the second cutting edge 12 is located at a greater distance from the rotation axis 3 than the radially outermost portion of the circumferential surface 41 of the shank portion 40.

[0035] The cutting portion 10 may also include two or more pairs of cutting edges 11, 12 of the type described above.

[0036] The cutting portion 10 has an axial extension of the tool body 2 limited to the region between a first plane P1 (see FIG. 2 ), which extends perpendicular to the rotation axis 3 and intersects the rear end 12b of the second cutting edge 12, and a second plane P2, which extends perpendicular to the rotation axis 3 and intersects the front end 11a of the first cutting edge 11. In the embodiment shown in FIGS. 1 to 8 , the tool body 2 does not have a portion extending axially beyond the cutting portion 10. Therefore, in this case, the cutting portion 10 constitutes the axially frontmost portion of the tool body 2, i.e., the portion furthest from the rear portion 6 of the tool body 2. Alternatively, the tool body 2 may also include a front portion 7, as shown in FIG. 18 , connected to the cutting portion 10 and protruding from the cutting portion on the side opposite the rear portion 6. In this case, the front end 11a of the first cutting edge 11 is located at a greater distance from the rotation axis 3 than the radially outermost portion of the circumferential surface of the front portion 7.

[0037] The radial distance r between the rear end 12b of the second cutting edge 12 and the radially outermost portion of the circumferential surface 41 of the shank portion 40 is preferably 2 to 40 mm, and more preferably 6 to 30 mm. In the embodiment shown in Fig. 18, the radial distance r2 between the front end 11a of the first cutting edge 11 and the radially outermost portion of the circumferential surface of the front portion 7 is preferably 2 to 40 mm, and more preferably 6 to 30 mm.

[0038] In the illustrated embodiment, the shank portion 40 is rod-shaped and has the form of a right circular cylinder. However, the shank portion 40 may also have any other suitable shape. The shank portion 40 has a length L of 25 to 500 mm, preferably 50 to 200 mm, and more preferably 100 to 150 mm.

[0039] The cutting part 10 may be permanently fixed to the shank part 40. However, in the embodiment shown in Figures 1-8, the cutting part 10 is removably attached to the front end 40a of the shank part 40 by fastening elements 42 in the form of two screws that extend through respective through holes 13 in the cutting part 10 and engage with respective threaded holes 43 (see Figure 4a) provided in the front end face 44 of the shank part 40.

[0040] In the illustrated embodiment, the cutting part 10 includes a base 14 to which the cutting part 10 is attached to a shank part 40, and a holder arm 15 fixed to the base 14 and projecting from the base 14 in a radial direction relative to the rotation axis 3 beyond the radially outermost portion of the peripheral surface 41 of the shank part 40. The holder arm 15 has an inner end 15a facing the rotation axis 3 and an opposite outer end 15b. The holder arm 15 is fixed to the base 14 at its inner end 15a, and the first and second cutting edges 11, 12 are disposed on the holder arm 15 at its outer end 15b. The first and second cutting edges 11, 12 form part of a cutting insert 16 that is removably attached to an insert seat 17 provided on the outer end 15b of the holder arm 15. The illustrated cutting insert 16 is releasably secured to the insert 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 with a threaded hole 20 (see FIG. 4 a) in a support surface 21 of the insert seat 17. The support surface 21 is advantageously provided with splines 22 or the like that are configured to securely mechanically engage corresponding splines 23 on the underside of the cutting insert 16 to ensure accurate positioning of the cutting insert 16 in the insert seat 17 and to prevent movement of the cutting insert 16 relative to the support surface 21 when properly mounted in the insert seat 17.

[0041] Advantageously, the base 14 and the shank 40 are formed as separate components, and the base 14 may be removably attached to the shank 40. However, the base 14 and the shank 40 may alternatively be formed integrally. In a corresponding manner, the front portion 7 and the base 14 included in the milling tool 1 shown in FIG. 17 may be formed integrally or as separate components attached to each other.

[0042] 1 to 8 , the base 14 is slidably attached to the front end 40a of the shank 40 and is slidable relative to the shank 40 perpendicular to the rotation axis 3 and linearly in the longitudinal direction of the holder arm 15. The base 14 can be locked to the shank 40 at different sliding positions, thereby enabling adjustment of the radial distance between the first cutting edge 11 and the rotation axis 3 and the radial distance between the second cutting edge 12 and the rotation axis 3. Therefore, by adjusting the position of the base 14 relative to the shank 40, it is possible to adjust the above-mentioned radial distance r between the rear end 12b of the second cutting edge 12 and the radially outermost portion of the circumferential surface 41 of the shank 40. In the illustrated example, the rear surface 14a of the base 14 is provided with mutually parallel splines 25 that extend parallel to the longitudinal axis of the holder arm 15 and slidably engage with corresponding splines 45 provided on the front end surface 44 of the shank portion 40 so that the base 14 can be slid in a desired direction relative to the shank portion 40 during adjustment of the sliding position of the base 14 relative to the shank portion 40.

[0043] The milling tool 1 shown in FIGS. 1-8 includes an adjustment mechanism 50 that allows the sliding position of the base 14 relative to the shank 40 to be adjusted. Thus, the precise positioning of the base 14 along the splines 45 on the front end surface 44 of the shank 40 can be adjusted by the adjustment mechanism 50. In the illustrated embodiment, the adjustment mechanism 50 includes an adjustment element 51 configured to act between the base 14 and the shank 40. The adjustment element 51 includes a pin 52 rotatably received in a hole 46 on the front end surface 44 of the shank 40 and a head 53 secured to the pin 52 and rotatably received in a recess 26 on the rear surface 14a of the base 14. The axis of rotation of the pin 52 is parallel to but offset from the axis of rotation of the head 53 such that rotation of the head 53 within the recess 26 results in sliding movement of the base 14 in the longitudinal direction of the splines 25, 45. A socket 54 designed for releasable engagement with a torque tool (not shown) is provided on the front surface of the head 53, allowing the torque tool to be connected to the head 53 when the head 53 is rotated, thereby moving the base 14 in the longitudinal direction of the splines 25, 45. The socket 54 is accessible through a hole 27 in the base 14. The base 14 is provided with through-holes 13 for the fastening elements 42 described above. Each of these through-holes 13 has an elongated cross-sectional shape with a major axis extending substantially in the longitudinal direction of the splines 25, thereby allowing the base 14 to move perpendicular to the shaft 42a of the fastening element 42 in the longitudinal direction of the splines 45 on the front end surface 44 of the shank 40. The base 14 can be locked to the shank 40 in a desired sliding position relative to the shank 40 by tightening the fastening element 42. Of course, the adjustment mechanism 50 may be designed in any other suitable manner.

[0044] In the embodiment shown in FIGS. 1-8 , the first cutting edge 11 extends substantially linearly in a third plane P3 (see FIG. 8 ) that includes the rotation axis 3, and the second cutting edge 12 extends substantially linearly in a fourth plane P4 that also includes the rotation axis 3. The fourth plane P4 preferably coincides with the third plane P3 as shown in FIG. 8 , but the third plane P3 and the fourth plane P4 may alternatively be angularly offset from each other with respect to the rotation axis 3 of the tool body 2. The first cutting edge 11 is inclined in the third plane P3 such that an extension of the first cutting edge 11 forms a first angle α1 (see FIG. 2 ) with the rotation axis 3, and the second cutting edge 12 is inclined in the fourth plane P4 such that an extension of the second cutting edge 12 forms a second angle α2 with the rotation axis 3. The first angle α1 and the second angle α2 may be different from each other but are preferably equal or at least substantially equal. The first angle α1 and the second angle α2 are equal to or greater than 20° and less than 90°, preferably 30 to 80°. In the illustrated embodiment, the first angle α1 and the second angle α2 are both approximately 45°.

[0045] 1 to 8, the first cutting edge 11 is formed at the intersection of the first surface 31 and the second surface 32 on the cutting insert 16, and the second cutting edge 12 is formed at the intersection of the third surface 33 and the fourth surface 34 on the cutting insert 16, the first surface 31 and the second surface 32 being mirror-symmetrical to each other with respect to a third plane P3, and the third surface 33 and the fourth surface 34 being mirror-symmetrical to each other with respect to a fourth plane P4. Furthermore, the first cutting edge 11 and the second cutting edge 12 are here mirror-symmetrical to each other with respect to a symmetry plane PS (see FIG. 8), which extends midway between the first cutting edge 11 and the second cutting edge 12 perpendicular to the rotation axis 3 of the tool body 2. The first surface 31 and the second surface 32 are inclined relative to each other and diverge from each other in a direction from the first cutting edge 11 toward the rotation axis 3, so that the first surface 31 and the second surface 32 form a first nose-shaped protrusion 35a on the cutting insert 16. In a corresponding manner, the third surface 33 and the fourth surface 34 are inclined relative to each other and diverge from each other in a direction from the second cutting edge 12 toward the rotation axis 3, so that the third surface 33 and the fourth surface 34 form a second nose-shaped protrusion 35b on the cutting insert 16. The first protrusion 35a is provided on a first side of the holder arm 15 at its outer end 15b to form a support for the first nose-shaped protrusion 36a on the cutting insert 16, and the second protrusion 35b is provided on a second opposite side of the holder arm 15 at its outer end 15b to form a support for the second nose-shaped protrusion 36b on the cutting insert 16.

[0046] As mentioned above, the milling tool 1 is intended to be used to chamfer the side edges 61-64 (see Figures 12 and 13) of internal or external teeth 60 on a cylindrical toothed workpiece 8 at a first end face 9a of the workpiece and an opposite second end face 9b of the workpiece. Each tooth 60 on the workpiece 8 has a tip 65, a root 66, a first tooth flank 67a extending between the tip 65 and the root 66 on a first side of the tooth, and a second tooth flank 67b extending between the tip 65 and the root 66 on an opposite second side of the tooth. A first side edge 61 is formed where the first tooth flank 67a intersects with the first end face 9a of the workpiece 8, a second side edge 62 is formed where the second tooth flank 67b intersects with the first end face 9a of the workpiece 8, a third side edge 63 is formed where the first tooth flank 67a intersects with the second end face 9b of the workpiece 8, and a fourth side edge 64 is formed where the second tooth flank 67b intersects with the second end face 9b of the workpiece 8. A bottom land 68 is provided between the roots 66 of adjacent teeth 60, and a top land 69 is provided at the tip 65 of each tooth 60.

[0047] The edges 70 at the contact surfaces between the top land 69 of each tooth 60 on the workpiece 8 and the respective end faces 9a, 9b of the workpiece are typically chamfered in a separate machining operation before the chamfering of the side edges 61-64 is performed by the milling tool 1.

[0048] During the execution of a chamfering operation using the above-described milling tool 1 or any other milling tool of a suitable type, the workpiece 8 is mounted in a rotatable workpiece holder (not shown) of the machine and is rotatable by the machine about the central axis 4 of the workpiece 8, and the milling tool 1 is mounted in a rotatable tool holder (not shown) of the machine and is rotatable by the machine about the rotation axis 3 of the tool body 2 and is movable relative to the workpiece 8 in the axial direction z of the workpiece 8 and in different directions in the plane x, y perpendicular to the central axis 4 of the workpiece 8, with the rotation axis 3 of the tool body 2 parallel to the central axis 4 of the workpiece 8. The rotational speed of the workpiece 8, the rotational speed of the milling tool 1 and the movement of the milling tool 1 relative to the workpiece 8 are controlled in a programmable manner by an electronic control device (not shown).

[0049] The workpiece holder and tool holder of the machine are typically positioned opposite each other with the tool holder facing the workpiece holder. In the examples shown in Figures 9-10 and 16-17, an end face of the workpiece 8, referred to as the first end face 9a, faces the tool holder of the machine, and an opposite second end face 9b of the workpiece 8 faces the workpiece holder of the machine. In the example shown in Figures 11a-11c, the workpiece 8 is positioned in the machine in an opposite direction, such that the first end face 9a of the workpiece 8 faces the workpiece holder of the machine, and the second end face 9b of the workpiece 8 faces the tool holder of the machine.

[0050] When attached to the workpiece holder of the machine, the workpiece 8 can be rotated by the machine about its central axis 4 in a first rotational direction R1 and an opposite second rotational direction R2. When the workpiece 8 is positioned with the second end surface 9b of the workpiece 8 facing the workpiece holder (as shown in Figures 9-10 and 16-17), when rotated in the first rotational direction R1, the workpiece 8 is rotated so that the second tooth flank 67b of the tooth 60 on the workpiece is the leading tooth flank and the first tooth flank 67a of the tooth 60 on the workpiece is the leading tooth flank, and when rotated in the second rotational direction R2, the workpiece 8 is rotated so that the first tooth flank 67a of the tooth 60 on the workpiece is the leading tooth flank and the second tooth flank 67b of the tooth 60 on the workpiece is the trailing tooth flank. When the workpiece 8 is positioned in the opposite direction with the first end surface 9a of the workpiece 8 facing the workpiece holder (as shown in Figures 11a to 11c), when rotated in a first rotation direction R1, the first tooth flank 67a of the tooth 60 on the workpiece becomes the leading tooth flank and the second tooth flank 67b of the tooth 60 on the workpiece becomes the trailing tooth flank, and when rotated in a second rotation direction R2, the workpiece 8 is rotated with the second tooth flank 67b of the tooth 60 on the workpiece becoming the leading tooth flank and the first tooth flank 67a of the tooth 60 on the workpiece becoming the trailing tooth flank.

[0051] To perform the chamfering of the first and second side edges 61, 62 of the tooth 60 on the workpiece 8 in the desired machining direction, the following steps are performed. a) The workpiece 8 is rotated around its central axis 4 in a rotation direction R1, with the second tooth flank 67b as the leading tooth flank and the first tooth flank 67a as the trailing tooth flank, and simultaneously the milling tool 1 is rotated around the rotation axis 3 of the tool body 2, so that according to a predetermined relationship between the rotation speed of the milling tool 1 and the rotation speed of the workpiece 8, the tooth 60 is rotated in the same rotation direction R1 as the workpiece 8 if it is an internal tooth on the workpiece 8 (see Figures 9a to 9c), or in the same rotation direction R1 as the workpiece 8 if it is an internal tooth on the workpiece 8. while maintaining the rotation axis 3 of the tool body 2 parallel to the central axis 4 of the workpiece 8, the milling tool 1 is moved along a predetermined path relative to the workpiece 8 in the opposite rotation direction R2 (see Figures 16a to 16c) if the teeth are external on the workpiece 8, so that the cutting edge 11 of the milling tool 1 faces the first end face 9a of the workpiece 8 and chamfers the first side edge 61 of the tooth 60 in the machining direction from the root 66 to the tip 65 of each tooth 60; b) rotating the workpiece 8 in the same rotational direction R2 as the workpiece 8 when the teeth 60 are internal teeth on the workpiece 8, or in the opposite rotational direction R1 to the workpiece 8 when the teeth 60 are external teeth on the workpiece 8, with the first tooth flank 67a as the leading tooth flank and the second tooth flank 67b as the trailing tooth flank, with a predetermined relationship between the rotational speed of the milling tool 1 and the rotational speed of the workpiece 8; and simultaneously rotating the milling tool 1 about the rotational axis 3 of the tool body 2, while maintaining the rotational axis 3 of the tool body 2 parallel to the central axis 4 of the workpiece 8, moving the milling tool 1 along a predetermined path relative to the workpiece 8, so that the cutting edge 11 of the milling tool 1 faces the first end face 9a of the workpiece 8 and chamfers the second side edge 62 of the tooth in the machining direction from the root 66 of the tooth 60 to the tip 65 of each tooth 60.

[0052] In the example shown, the chamfering of the first side edge 61 in step a and the chamfering of the second side edge 62 in step b are performed by one and the same milling tool 1. However, it would alternatively be possible to perform the chamfering of the first side edge 61 in step a using a first milling tool with cutting edges adapted for milling in only one rotational direction, and the chamfering of the second side edge 62 in step b using a second milling tool with cutting edges adapted for milling in only the opposite rotational direction.

[0053] In order to also chamfer the third and fourth side edges 63, 64 of the teeth 60 on the workpiece 8 in the desired machining direction, the following additional steps are performed. c) the workpiece 8 is rotated about its central axis 4 in a rotational direction (R1 in Figures 10a, 10b, 17a and 17b and R2 in Figures 11a-11c), with the second tooth flank 67b being the leading tooth flank and the first tooth flank 67a being the trailing tooth flank, and the milling tool 1 is simultaneously rotated about the rotation axis 3 of the tool body 2 with a predetermined relationship between the rotational speed of the milling tool 1 and the rotational speed of the workpiece 8, in the same rotational direction as the workpiece 8 if the tooth 60 is an internal tooth on the workpiece 8 (Figures 10a and 10b and 11a to 11c), or in the opposite rotational direction if the teeth 60 are external teeth on the workpiece 8 (see FIGS. 17a and 17b), while maintaining the rotation axis 3 of the tool body 2 parallel to the central axis 4 of the workpiece 8 and with the active cutting edge of the milling tool 1 facing the second end face 9b of the workpiece 8, moving the milling tool 1 along a predetermined path relative to the workpiece 8, so that the cutting edge chamfers the third side edge 63 of the tooth 60 in the machining direction from the root 66 to the tip 65 of each tooth 60; d) The workpiece 8 is rotated around its central axis 4 in a rotational direction (R2 in FIGS. 10a, 10b, 17a and 17b and R1 in FIGS. 11a to 11c), with the first tooth flank 67a being the leading tooth flank and the second tooth flank 67b being the trailing tooth flank, and the milling tool 1 is rotated around the rotation axis 3 of the tool body 2 in the same direction as the workpiece 8 when the tooth 60 is an internal tooth of the workpiece 8, with a predetermined relationship between the rotational speed of the milling tool 1 and the rotational speed of the workpiece 8. While maintaining the rotation axis 3 of the tool body 2 parallel to the central axis 4 of the workpiece 8, the milling tool 1 is moved along a predetermined path relative to the workpiece 8 so that the active cutting edge of the milling tool 1 faces the second end face 9 b of the workpiece 8, whereby the cutting edge chamfers the fourth side edge 64 of the tooth 60 in the machining direction from the root 66 to the tip 65 of each tooth 60.

[0054] The chamfering of the third and fourth side edges 63, 64 in steps c and d is performed using the second cutting edge 12 of the milling tool 1 as the active cutting edge in the examples shown in FIGS. 10a-b and 17a-b, and using the first cutting edge 11 of the milling tool 1 as the active cutting edge in the example shown in FIGS. 11a-c. If the chamfering of the first and second side edges 61, 62 in steps a and b and the chamfering of the third and fourth side edges 63, 64 in steps c and d are performed using the first cutting edge 11 as the active cutting edge, the workpiece 8 must be repositioned in the workpiece holder after steps a and b are completed and before steps c and d are performed so that the first end face 9a faces forward toward the milling tool 1 during steps a and b, and the opposite second end face 9b faces forward toward the milling tool 1 during steps c and d. In this case, it is of course possible to use a milling tool that includes a first cutting edge 11 of the type described above, but does not include a second cutting edge 12 and a shank portion 40 of the type described above.

[0055] When the chamfering of the first and second side edges 61, 62 in steps a and b is performed with the first cutting edge 11 of the milling tool 1 as the active cutting edge, and the chamfering of the third and fourth side edges 63, 64 in steps c and d is performed with the second cutting edge 12 of the milling tool 1 as the active cutting edge, the workpiece 8 can remain positioned with the first end face 9a facing forward during all of steps a through d. In this case, after steps a and b are completed and before steps c and d are performed, the milling tool 1 must be moved axially relative to the workpiece 8 from the position shown in FIG. 14a where the cutting portion 10 of the tool body 2 is adjacent to the first end face 9a of the workpiece 8 and the first cutting edge 11 faces this first end face 9a to the position shown in FIG. 14b where the cutting portion 10 of the tool body 2 is adjacent to the second end face 9b of the workpiece 8 and the second cutting edge 12 faces this second end face 9b.

[0056] During the chamfering in each of steps a, b, c, and d above, a portion of one of the active first and second cutting edges 11, 12 is rotated into a gap between two adjacent teeth 60 and then moved with this gap in the direction of rotation of the workpiece 8 during part of the rotation of the workpiece 8 while engaging in cutting with at least one portion of one of the side edges located on either side of the gap before being rotated out of the gap, as shown in Figures 15a-15e. As the milling tool 1 continues to rotate, the portion of the active one of the first and second cutting edges 11, 12 rotates into a new gap between two other adjacent teeth 60 on the workpiece 8, and so on. By gradually moving the milling tool 1 relative to the workpiece 8 during continuous rotation of the milling tool 1 and the workpiece 8 so that the distance between the rotation axis 3 of the tool body 2 and the central axis 4 of the workpiece 8 varies, the active cutting edges 11, 12 can be brought into cutting engagement with different portions of each side edge being chamfered at different stages of the chamfering process until these side edges are chamfered along their entire extension.

[0057] Movement of the milling tool 1 relative to the workpiece 8 in each of steps a and b can begin by first moving the milling tool 1 axially, thereby moving the active cutting edge, i.e., first cutting edge 11 in the examples shown in FIGS. 9a-9c and 16a-16c, toward the first end face 9a of the workpiece 8 so that this cutting edge contacts the workpiece 8 as the milling tool 1 rotates. The milling tool 1 then remains in this axial position relative to the workpiece 8 for the remainder of the step, thereby achieving a chamfer of approximately constant width along each side edge being chamfered. However, the milling tool 1 can also be moved axially relative to the workpiece 8 during at least a portion of the remainder of the step, thereby achieving a chamfer of varying width along each side edge being chamfered.

[0058] In a corresponding manner, movement of the milling tool 1 relative to the workpiece 8 in each of steps c and d can begin by first moving the milling tool 1 axially, thereby moving the active cutting edge, i.e., the first cutting edge 11 in the example shown in FIGS. 11a-11c and the second cutting edge 12 in the examples shown in FIGS. 10a-10b and 17a-17b, toward the second end face 9b of the workpiece 8 so that this cutting edge contacts the workpiece 8 as the milling tool 1 rotates. The milling tool 1 then remains in this axial position relative to the workpiece 8 during the remainder of step o, thereby achieving a chamfer of substantially constant width along each chamfered side edge. However, the milling tool 1 can also be moved axially relative to the workpiece 8 during at least part of the remainder of the step, thereby achieving a chamfer of varying width along each chamfered side edge.

[0059] The relationship between the rotational speed of the milling tool 1 and the rotational speed of the workpiece 8 should be adapted so that a portion of the active cutting edges 11, 12 enters the gaps between all of the teeth 60 on the workpiece 8 after a certain number of revolutions of the workpiece 8. To enable the active cutting edges to move in the same direction as the gaps between two adjacent teeth 60 on the workpiece 8, with the portion of the cutting edge accepted in the gap in question, the milling tool 1 must be rotated about the rotation axis 3 of the tool body 2 in the same rotational direction as the workpiece 8 when the side edges 61-64 of the internal teeth 60 on the workpiece are being chamfered, and in the opposite rotational direction to the workpiece 8 when the side edges 61-64 of the external teeth 60 on the workpiece are being chamfered.

[0060] Of course, the present invention is in no way limited to the above-described embodiments, but 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 invention as defined in the appended claims.

Claims

1. A method for chamfering side edges of internal or external teeth (60) on a cylindrical toothed workpiece (8) on at least one of two opposing end faces (9a, 9b) of said workpiece (8), wherein each of said teeth (60) has a tip (65), a root (66), a first tooth flank (67a) extending between said tip (65) and said root (66) on a first side of said tooth, and a second tooth flank (67b) extending between said tip (65) and said root (66) on an opposite second side of said tooth, A side edge (61) is formed at the intersection of the first tooth flank (67a) and a first end face (9a) of the two end faces of the workpiece (8), a second side edge (62) is formed at the intersection of the second tooth flank (67b) and the first tooth flank (9a) of the two end faces of the workpiece (8), a third side edge (63) is formed at the intersection of the first tooth flank (67a) and a second tooth flank (9b) of the two end faces of the workpiece (8), and a fourth side edge (64) is formed at the intersection of the second tooth flank (67b) and the second tooth flank (9a) of the two end faces of the workpiece (8). The chamfering is performed by one or more milling tools (1), each of which includes a tool body (2) and one or more cutting edges (11, 12) provided on the tool body, and the one or more milling tools (1) are configured to rotate around a central axis (4) of the workpiece (8) by a machine, and the ... and the one or more milling tools (1) are configured to rotate around a central axis (4) of the workpiece (8) by a machine, and the one or more milling tools (1) are configured to rotate around a central axis (4) of the workpiece (8) by a machine, and the one or more milling tools (1) are configured to rotate around a central axis (4) of Each of the tools (1) is rotatable by the machine about a rotation axis (3) of the tool body (2) and movable relative to the workpiece (8) in an axial direction (z) of the workpiece (8), and is movable by the machine relative to the workpiece (8) in different directions in a plane (x, y) perpendicular to the central axis (4) of the workpiece (8) so that the rotation axis (3) of the tool body (2) is parallel to the central axis (4) of the workpiece (8), and the method comprises: a) rotating the workpiece (8) in the same rotational direction (R1) as the workpiece (8) when the teeth (60) are internal teeth on the workpiece (8) or in the opposite rotational direction (R2) when the teeth (60) are external teeth on the workpiece (8) in a predetermined relationship between the rotational speed of the milling tool (1) and the rotational speed of the workpiece (8) in a rotational direction (R1) with the second tooth flank (67b) as a leading tooth flank and the first tooth flank (67a) as a trailing tooth flank, about the central axis (4) of the workpiece (8); and simultaneously rotating the one or more milling tools (1) in the same rotational direction (R1) as the workpiece (8) when the teeth (60) are external teeth on the workpiece (8) in a rotational direction opposite to the rotational direction (R2) with the second tooth flank (67b) as a leading tooth flank and the first tooth flank (67a) as a trailing tooth flank, about the rotational axis (3) of the tool body (2). rotating one of the milling tools (1) and maintaining the rotation axis (3) of the tool body (2) parallel to the central axis (4) of the workpiece (8), while moving the milling tool (1) along a predetermined path relative to the workpiece (8) so that at least one of the one or more cutting edges (11, 12) of the milling tool (1) faces the first end face (9 a) of the two end faces of the workpiece (8), whereby the at least one cutting edge chamfers the first side edge (61) of each tooth (60) in the machining direction from the root (66) to the tip (65) of the tooth; b) rotating the workpiece (8) in the same rotational direction (R2) as the workpiece (8) when the teeth (60) are internal teeth on the workpiece (8) or in the opposite rotational direction (R1) when the teeth (60) are external teeth on the workpiece (8) in a predetermined relationship between the rotational speed of the milling tool (1) and the rotational speed of the workpiece (8) around the central axis (4), with the first tooth flank (67a) as a leading tooth flank and the second tooth flank (67b) as a trailing tooth flank, and simultaneously rotating the one or more milling tools (1) around the rotational axis (3) of the tool body (2) in the same rotational direction (R2) as the workpiece (8) when the teeth (60) are external teeth on the workpiece (8) in the opposite rotational direction (R1) and rotating one of the milling tools (1) and maintaining the rotation axis (3) of the tool body (2) parallel to the central axis (4) of the workpiece (8), while moving the milling tool (1) along a predetermined path relative to the workpiece (8) so that at least one of the one or more cutting edges (11, 12) of the milling tool (1) faces the first end face (9 a) of the two end faces of the workpiece (8), whereby the at least one cutting edge chamfers the second side edge (62) of the tooth (60) in a machining direction from the root (66) to the tip (65) of each tooth (60). A method comprising:

2. 2. The method according to claim 1, wherein the predetermined path for the movement of the milling tool (1) relative to the workpiece (8) in step a includes at least one portion in which the milling tool (1) is moved in its axial direction, thereby moving the one or more cutting edges facing the first end face (9 a) of the two end faces of the workpiece (8) in a direction toward this end face (9 a).

3. 3. The method according to claim 1, wherein the predetermined path for the movement of the milling tool (1) relative to the workpiece (8) in step a) includes at least one portion in which the distance between the rotation axis (3) of the tool body (2) and the central axis (4) of the workpiece (8) is changed.

4. 4. The method according to claim 1, wherein the predetermined path for the movement of the milling tool (1) relative to the workpiece (8) in step b includes at least one portion in which the milling tool (1) is moved in the axial direction of the milling tool (1), thereby moving the one or more cutting edges facing the first end face (9 a) of the two end faces of the workpiece (8) in a direction toward this end face (9 a).

5. 5. The method according to claim 1, wherein the predetermined path for the movement of the milling tool (1) relative to the workpiece (8) in step b includes at least one portion in which the distance between the rotation axis (3) of the tool body (2) and the central axis (4) of the workpiece (8) is changed.

6. The method comprises: c) rotating the workpiece (8) in the same rotational direction (R1) as the workpiece (8) when the teeth (60) are internal teeth on the workpiece (8) or in the opposite rotational direction (R2) when the teeth (60) are external teeth on the workpiece (8) in a predetermined relationship between the rotational speed of the milling tool (1) and the rotational speed of the workpiece (8), with the second tooth flank (67b) as the leading tooth flank and the first tooth flank (67a) as the trailing tooth flank, about the central axis (4); and simultaneously rotating the one or more milling tools (1) about the rotational axis (3) of the tool body (2). and rotating one of the milling tools (1) and maintaining the rotation axis (3) of the tool body (2) parallel to the central axis (4) of the workpiece (8), while moving the milling tool (1) along a predetermined path relative to the workpiece (8) so that at least one of the one or more cutting edges (11, 12) of the milling tool (1) faces a second end face (9b) of the two end faces of the workpiece (8), whereby the at least one cutting edge chamfers the third side edge (63) of the tooth (60) in a machining direction from the root (66) to the tip (65) of each tooth (60). d) rotating the workpiece (8) in the same rotational direction (R2) as the workpiece (8) when the teeth (60) are internal teeth on the workpiece (8) or in the opposite rotational direction (R1) when the teeth (60) are external teeth on the workpiece (8) in a predetermined relationship between the rotational speed of the milling tool (1) and the rotational speed of the workpiece (8) around the central axis (4), with the first tooth flank (67a) as a leading tooth flank and the second tooth flank (67b) as a trailing tooth flank, and simultaneously rotating one of the one or more milling tools (1) around the rotational axis (3) of the tool body (2) and, while maintaining the rotation axis (3) of the tool body (2) parallel to the central axis (4) of the workpiece (8), moving the milling tool (1) along a predetermined path relative to the workpiece (8) so that at least one of the one or more cutting edges (11, 12) of the milling tool (1) faces the second end face (9b) of the two end faces of the workpiece (8), whereby the at least one cutting edge chamfers the fourth side edge (64) of the tooth (60) in a machining direction from the root (66) to the tip (65) of each tooth (60); 6. The method of claim 1, further comprising:

7. 7. The method according to any one of claims 1 to 6, wherein in step a the workpiece (8) is rotated in a first rotational direction (R1), and in step b the workpiece (8) is rotated in a second rotational direction (R2) opposite to the first rotational direction (R1) while being maintained in the same orientation as in step a.

8. the chamfering in step a and the chamfering in step b are performed by one and the same milling tool (1), the milling tool (1) comprising at least one first cutting edge (11) facing the first end face (9a) of the two end faces of the workpiece (8), chamfering the first and second side edges (61, 62) of the tooth (60) in steps a and b, the tool body (2) of this milling tool (1) at its rear end (2b) having a rear part (6) configured for attachment to the machine, The at least one first cutting edge (11) extends substantially linearly in a plane (P3) including the rotation axis (3) of the tool body (2) of the milling tool (1), and is formed at an intersection of a first surface (31) and a second surface (32) on a cutting insert (16) releasably mounted in an insert seat (17) provided in the tool body (2), the first surface (31) functioning as a rake face, and the second surface (32) on the milling tool (1) the first surface (31) functions as a clearance surface when the milling tool (1) rotates around the rotation axis (3) of the tool body (2) in one direction and a chamfering is performed by the at least one first cutting edge (11), and the second surface (32) functions as a rake surface when the milling tool (1) rotates around the rotation axis (3) of the tool body (2) in another opposite rotation direction and a chamfering is performed by the at least one first cutting edge (11). The method of claim 7.

9. 9. The method of claim 8, wherein the first surface (31) and the second surface (32) are mirror images of each other with respect to the plane (P3).

10. 10. The method according to claim 8 or 9, wherein the at least one first cutting edge (11) has a front end (11a) and an opposite rear end (11b), the rear end (11b) of the at least one first cutting edge (11) being located closer to the rear end (6) of the tool body than the front end (11a) of the at least one first cutting edge (11), the front end (11a) of the at least one first cutting edge (11) being located closer to the rotation axis (3) of the tool body (2) than the rear end (11b) of the at least one first cutting edge (11), and the distance between the at least one first cutting edge (11) and the rotation axis (3) of the tool body (2) gradually increases from the front end (11a) to the rear end (11b) when viewed in a direction along the at least one first cutting edge (11).

11. The at least one first cutting edge (11) has an extension of the first cutting edge (11) that forms an angle (α) of 20° or more and less than 90°, preferably 30 to 80°, with respect to the rotation axis (3) of the tool body (2). １ 11. The method according to claim 10, wherein the surface has a slope in said plane (P3) so as to form a

12. The chamfering in step c and the chamfering in step d are performed by the same milling tool (1) as the chamfering in steps a and b; the milling tool (1) includes at least one second cutting edge (12) facing the second end face (9b) of the two end faces of the workpiece (8), and in steps c and d, the third and fourth side edges (63, 64) of the tooth (60) are chamfered; the at least one first cutting edge (11) faces in a direction away from the rear portion (6) of the tool body (2), and the at least one second cutting edge (12) faces the rear portion (6) of the tool body (2) and is located closer to the rear portion (6) than the at least one first cutting edge (11); the at least one second cutting edge (12) extends substantially linearly in a plane (P4) containing the rotation axis (3) of the tool body (2) and is formed at the intersection of a third surface (33) and a fourth surface (34) on the cutting insert (16), the third surface (33) functioning as a rake surface and the fourth surface (34) functioning as a clearance surface when the milling tool (1) is rotated in one rotation direction about the rotation axis (3) of the tool body (2) and a chamfer is performed by the at least one second cutting edge (12), while the third surface (33) functioning as a rake surface and the fourth surface (34) functioning as a rake surface when the milling tool (1) is rotated in another opposite rotation direction about the rotation axis (3) of the tool body (2) and a chamfer is performed by the at least one second cutting edge (12); the tool body (2) includes a cutting portion (10) located away from the rear portion (6), and an elongated shank portion (40) supporting the cutting portion (10) and extending from the cutting portion (10) toward the rear portion (6) and having a front end (40a) facing the cutting portion (10), an opposite rear end (40b), and a peripheral surface (41) extending around the shank portion (40) between the rear end (40b) and the rear end (40a), the shank portion (40) having a longitudinal central axis coinciding with the rotation axis (3) of the tool body (2); the at least one second cutting edge (12) is disposed so as to be farther from the rotation axis (3) of the tool body (2) than the radially outermost portion of the circumferential surface (41) of the shank portion (40); 12. The method according to any one of claims 8 to 11 in combination with claim 6, wherein the cutting portion (10) constitutes the axially frontmost part of the tool body (2) or the tool body (2) comprises a front portion (7) protruding from the cutting portion (10) on a side of the tool body (2) facing away from the rear portion (6), and wherein the at least one first cutting edge (11) is arranged at a distance from the rotation axis (3) of the tool body (2) that is greater than the radially outermost part of this front portion (7).

13. 13. The method according to claim 12, wherein the third surface (33) and the fourth surface (34) are mirror images of each other with respect to the plane (P4) in which the at least one second cutting edge (12) extends.

14. 14. The method according to claim 12 or 13, wherein the at least one second cutting edge has a leading end (12a) and an opposite trailing end (12b), the trailing end (12b) of the at least one second cutting edge (12) being located closer to the trailing end (6) of the tool body than the leading end (12a) of the at least one second cutting edge (12), the trailing end (12b) of the at least one second cutting edge being located closer to the rotation axis (3) of the tool body (2) than the leading end (12a) of the at least one second cutting edge (12), and the distance between the at least one second cutting edge (12) and the rotation axis (3) of the tool body (2) gradually increases from the trailing end (12b) to the leading end (12a) of the at least one second cutting edge (12) as viewed in a direction along the at least one second cutting edge (12).

15. The at least one second cutting edge (12) has an extension of the second cutting edge (12) that forms an angle (α) with the rotation axis (3) of the tool body (2) of 20° or more and less than 90°, preferably 30 to 80°. ２ 15. The method according to claim 14, wherein the plane (P4) extends to form a slope.

16. A computer program having instructions which, when executed by a CNC machine, cause the CNC machine to perform the steps of any one of claims 1 to 15.

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