CUTTING TOOL

Abstract

A cutting tool includes a cutting insert having an anti-rotation stopping indent formed in a transition between a bottom surface and a side surface thereof and includes a first stop surface. The insert seat has at least one anti-rotation stop, which protrudes with respect to a side wall of the insert seat and includes a second stop surface. The anti-rotation stop is arranged to inhibit rotation of the cutting insert in the insert seat by contact between the first and second stop surfaces. The second stop surface is completely located within the anti-rotation stopping indent when the cutting insert is mounted. As seen in a section perpendicular to a common central axis, an angle of less than 180° is formed between a tangent to the second stop surface and a tangent to the first duct at a transition between the two.

Claims

1. A cutting tool for chip removing machining of workpieces, the cutting tool comprising: a body; and at least one cutting insert arranged to be mounted in an insert seat of the body, the cutting insert and the insert seat sharing a common central axis when the cutting insert is mounted in the insert seat, wherein the cutting insert has a circular basic shape and comprises: a rake surface, a bottom surface opposite to the rake surface, a side surface extending between the rake surface and the bottom surface, a cutting edge formed in a transition between the side surface and the rake surface, and at least one anti-rotation stopping indent formed in a transition between the bottom surface and the side surface and including a first stop surface, wherein the insert seat of the body comprises: a bottom support surface configured to abut and support the bottom surface of the cutting insert, a side wall including at least one side support surface configured to abut and support the side surface of the cutting insert, at least one anti-rotation stop protruding with respect to the side wall and comprising a second stop surface, and a concavely curved first duct separating the second stop surface from the side wall, wherein the at least one anti-rotation stop is arranged to inhibit rotation of the cutting insert in the insert seat about the common central axis by contact between the first stop surface and the second stop surface, wherein the second stop surface is completely located within the anti-rotation stopping indent when the cutting insert is mounted in the insert seat, and, when seen in a section taken perpendicularly to the common central axis, an angle of less than 180° is formed between a tangent to the second stop surface and a tangent to the first duct at a transition between the second stop surface and the first duct.

2. The cutting tool according to claim 1, wherein the second stop surface and the first stop surface are symmetric with respect to an axial plane containing the common central axis and intersecting the anti-rotation stopping indent.

3. The cutting tool according to claim 1, wherein the first duct is indented with respect to the side wall.

4. The cutting tool according to claim 1, wherein the second stop surface is convexly curved when seen in a section taken perpendicularly to the common central axis.

5. The cutting tool according to claim 1, wherein the first stop surface is concavely curved when seen in a section taken perpendicularly to the common central axis.

6. The cutting tool according to claim 1, wherein the second stop surface intersects an axial plane containing the common central axis along a first line, the first line being obliquely inclined with respect to the bottom support surface.

7. The cutting tool according to claim 1, wherein the at least one anti-rotation stopping indent has a cross sectional area that decreases in an upward axial direction from the bottom surface.

8. The cutting tool according to claim 1, wherein the first stop surface and the second stop surface are configured so that the contact occurring between the first stop surface and the second stop surface upon rotation of the cutting insert about the common central axis is a line contact.

9. The cutting tool according to claim 1, wherein the insert seat further includes a concavely curved second duct extending between the second stop surface and the bottom support surface.

10. The cutting tool according to claim 1, wherein the at least one anti-rotation stopping indent has an axial extension along the common central axis, which axial extension is between 30-60% of a total axial extension of the at least one cutting insert.

11. The cutting tool according to claim 1, wherein the second stop surface includes a pair of planar surface portions adjacent to the first duct.

12. The cutting tool according to claim 1, wherein the at least one side support surface of the insert seat includes two side support surfaces provided on opposite sides of the anti-rotation stop.

13. The cutting tool according to claim 1, wherein the anti-rotation stop and the anti-rotation stopping indent are configured so that the contact between the first stop surface and the second stop surface occurs at least partially on the transition between the second stop surface and the first duct.

14. The cutting tool according to claim 1, wherein the body is a tool body having a front end arranged for cutting engagement with a workpiece and a rear end arranged for mounting the cutting tool to a tool holder, wherein the insert seat is provided in the front end of the body.

15. The cutting tool according to claim 1, wherein the cutting tool is a milling tool.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Embodiments of the present invention will hereinafter be further explained by means of non-limiting examples with reference to the appended drawings, wherein:

[0047] FIG. 1 is a perspective view of a milling tool according to a first embodiment of the invention,

[0048] FIG. 2 is an exploded view of a part of the milling tool shown in FIG. 1,

[0049] FIG. 3 is an end view of the part in FIG. 2,

[0050] FIG. 4 is a sectional view along the line IV-IV in FIG. 3,

[0051] FIG. 5 is a sectional view along the line V-V in FIG. 4,

[0052] FIG. 6 is a sectional view along the line VI-VI in FIG. 4,

[0053] FIG. 7 is an exploded view of a part of a milling tool according to a second embodiment,

[0054] FIG. 8 is a sectional view of the milling tool shown in FIG. 7 along the line VIII-VIII and corresponding to the view in FIG. 4,

[0055] FIG. 9 is a sectional view of the milling tool shown in FIG. 7 along the line IX-IX and corresponding to the view in FIG. 5,

[0056] FIG. 10 is a sectional view of the milling tool shown in FIG. 7 along the line X-X and corresponding to the view in FIG. 6,

[0057] FIG. 11 is a partial view of an insert seat of the milling tool in FIG. 7,

[0058] FIG. 12 is an exploded view of a part of a milling tool according to a third embodiment,

[0059] FIG. 13 is an exploded view of a part of a milling tool according to a fourth embodiment,

[0060] FIG. 14 is a sectional view of the milling tool shown in FIG. 13 corresponding to the view in FIG. 4, and

[0061] FIG. 15 is a sectional view of the milling tool shown in FIG. 13 along the line XV-XV and corresponding to the view in FIG. 5.

[0062] It should be noted that the appended drawings are schematic and that individual components are not necessarily drawn to scale and that the dimensions of some features of the present invention may have been exaggerated for the sake of clarity.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0063] A cutting tool 1 in the form of a milling tool according to a first embodiment of the invention is shown in FIGS. 1-6. Parts of a cutting tool according to second, third and fourth embodiments are shown in FIGS. 7-11, 12 and 13-15, respectively. In the following, common features of all four embodiments will first be described, and specific features of each embodiment will thereafter be described separately.

[0064] The cutting tool 1 comprises a body 100 having a front end 101, a rear end 102, and a peripheral side surface 103 extending between the front end 101 and the rear end 102. Eight insert seats 104 are provided at the front end 101, formed in a transition between the front end 101 and the peripheral side surface 103. The cutting tool 1 is configured to be rotated about a central axis C.sub.2 in a direction of rotation R. In front of each insert seat 104 in the direction of rotation R, a chip pocket 105 is provided.

[0065] The body 100 is configured to receive eight cutting inserts 200, each cutting insert 200 being mounted in one of the insert seats 104. Each cutting insert 200 has a positive cutting geometry and a circular basic shape with an upper rake surface 201, a bottom surface 202 opposite to the rake surface, and a frusto-conical side surface 203 extending between the rake surface 201 and the bottom surface 202 at an angle β of 75° (clearance angle) with respect to the bottom surface 202. In a transition between the rake surface 201 and the side surface 203, a circular cutting edge 204 is formed. The cutting insert 200 has a central axis, which forms a common central axis C.sub.1 of the insert seat 104 and the cutting insert 200 when the cutting insert 200 is mounted in the insert seat 104 by means of a screw 300. The cutting insert 200 comprises a through hole, which is centered on the common central axis C.sub.1 and which is configured to receive the screw 300. The through hole in the cutting insert 200 comprises a funnel shaped part adjacent to the upper rake surface 201. The funnel shaped part of the through hole is arranged for reception of a head of the screw 300. A central axis C.sub.3 of a threaded hole within the insert seat 104, however, does not coincide with the common central axis C.sub.1 and there is a displacement between the common central axis C.sub.1 and the central axis C.sub.3 of the threaded hole within the insert seat. The displacement is arranged such that the screw bends slightly during the mounting of the cutting insert 200 in order to press the cutting insert against the side wall 107 and hold it in place in the insert seat. The common central axis C.sub.1 and the central axis C.sub.3 of the threaded hole are preferably, but not necessarily, parallel to each other.

[0066] In a transition between the side surface 203 and the bottom surface 202 of the cutting insert 200, eight anti-rotation stopping indents 205 are formed, evenly spaced apart around a periphery of the cutting insert 200. The indents 205, which may alternatively be referred to as recesses, are formed as discrete indents in the side surface 203, i.e. the side surface 203 extends all the way to the bottom surface 202 between each two indents 205. The indents 205 are thus spaced from each other and completely delimited by the side surface 203 and the bottom surface 202. Each indent 205 comprises a first stop surface 206, wherein the first stop surface 206 is delimited by the side surface 203 and the bottom surface 202. The first stop surface 206 thus intersects and is adjacent to the side surface 203 of the cutting insert 200. The first stop surface 206 is preferably adjacent to and intersects the bottom surface 202 of the insert. Preferably, the at least one anti-rotation stopping indent 205 is completely defined by the first stop surface 206.

[0067] Each insert seat 104 has a bottom support surface 106 configured to abut and support the bottom surface 202 of the cutting insert 200. It further has a side wall 107, configured to face the side surface 203 of the cutting insert 200. In all shown embodiments, two side support surfaces 113, 114 configured to abut and support the side surface 203 of the cutting insert 200 are provided in the side wall 107. The side support surfaces 113, 114 and the bottom support surface 106 are configured for positioning of the cutting insert 200 in the insert seat 104 when the cutting insert 200 is mounted by means of e.g. a screw 300 or another fastening member.

[0068] In the insert seat 104, an anti-rotation stop 108 is provided, which is configured to limit rotation of the cutting insert 200 in both directions about the common central axis C.sub.1 to 1-2°, such as to 1.3°, when the cutting insert is mounted in the insert seat 104. The anti-rotation stop 108 protrudes with respect to the side wall 107 and comprises a second stop surface 109, protruding with respect to the side wall 107. A concavely curved first duct 110, extending between the second stop surface 109 and the side wall 107, separates the second stop surface 109 from the side wall 107. The first duct 110 is in the shown embodiments indented with respect to the side wall 107, but it is also possible to have a first duct which is not indented with respect to the side wall. The concave curvature of the first duct 110 can be seen in a section perpendicular to the common central axis C.sub.1 and intersecting the anti-rotation stop 108, as shown in FIGS. 5, 9 and 15.

[0069] In the shown embodiments, the insert seat 104 further comprises a concavely curved second duct 115, whose concave curvature can be seen in an axial plane P.sub.1 containing the common central axis C.sub.1, as shown in FIGS. 4, 8 and 14. The second duct 115 extends between the second stop surface 109 and the bottom support surface 106, thus separating the second stop surface 109 from the bottom support surface 106. The second stop surface 109 is thereby delimited by on one hand the first duct 110 and on the other hand the second duct 115. The second duct 115 is in the shown embodiments indented with respect to the bottom support surface 106 and with respect to the second stop surface 109. The second stop surface 109 is completely positioned above the bottom support surface 106.

[0070] The second stop surface 109 is adapted to be completely located within the anti-rotation stopping indent 205 when the cutting insert 200 is mounted in the insert seat 104. In other words, when the cutting insert 200 is mounted in the insert seat 104, a shortest distance between any point on the second stop surface 109 and the common central axis C.sub.1 is shorter than a shortest distance between the side surface 203 and the common central axis C.sub.1 at a corresponding axial level (i.e. in a section perpendicular to the central axis C.sub.1). The first duct 110 ensures that a clearance is provided around the second stop surface 109. During machining, the portions of the side walls 107 of the insert seat 104 that are adjacent to the anti-rotation stop 108 are therefore prevented from coming into contact with the cutting insert 200.

[0071] When seen in a section taken perpendicularly to the common central axis C.sub.1, an angle α of less than 180° is formed between a tangent T.sub.1 to the second stop surface 109 and a tangent T.sub.2 to the first duct 110 at a transition between the second stop surface 109 and the first duct 110. The transition between the second stop surface 109 and the first duct 110 may be a slightly rounded transition. The angle α may be determined by extending the second stop surface 109 and the first duct 110 in the respective tangential directions as close to the transition as possible, and measure the angle in the intersection between the tangents T.sub.1 and T.sub.2. This is illustrated in FIGS. 5, 9 and 15. When seen in any section taken perpendicularly to the common central axis C.sub.1 and through the transition between the second stop surface 109 and the first duct 110, an angle α of less than 180° is formed between a tangent T.sub.1 to the second stop surface 109 and a tangent T.sub.2 to the first duct 110 at the transition between the second stop surface 109 and the first duct 110.

[0072] When seen in any section perpendicular to the common central axis C.sub.1 and through the transition between the second stop surface 109 and the first duct 110, there is at least one part of the first stop surface 206 which is positioned at a larger distance from the common central axis C.sub.1 than any point of the transition between the second stop surface 109 and the first duct 110, wherein said any point of the transition between the second stop surface 109 and the first duct 110 and the at least one part of the first stop surface 206 are situated at the same side of a line intersecting the common central axis C.sub.1 and the second stop surface 109 in a point of the second stop surface 109 which point is closest to the common central axis C.sub.1 in the section.

[0073] There is also a transition between the second stop surface 109 and the second duct 115. The transition between the second stop surface 109 and the second duct 115 may be arranged as the transition between the second stop surface 109 and the first duct 110.

[0074] In all shown embodiments, each of the anti-rotation stopping indents 205 has a cross sectional area that decreases in an upward axial direction from the bottom surface 202 of the cutting insert 200. The axial extension of the anti-rotation stopping indent 205 along the common central axis C.sub.1 of the cutting insert 200 is about 50% of a total axial extension of the cutting insert 200. In a radial direction of the cutting insert, a distance y measured between a point of the indent 205 closest to the common central axis C.sub.1 and the through hole of the cutting insert is approximately 10% of a largest diameter D of the cutting insert 200. The distance y may preferably be between 10% and 30% of the diameter D.

[0075] The side support surfaces 113, 114 are in the shown embodiments provided on opposite sides of the rotation stop 108. The side support surfaces 113, 114 form part of the side wall 107 and are spaced apart from the anti-rotation stop 108 by portions of the side wall 107 that form clearance surfaces. The insert seat 104 is mirror symmetric with respect to the axial plane P.sub.1 through the rotation stop 108. The central axis C.sub.3 of the threaded hole in the insert seat 104 is positioned closer to the anti-rotation stop 108 than the common central axis C.sub.1 at least along a part of the threaded hole.

[0076] In the first embodiment shown in FIGS. 1-6, the first stop surface 206 of the anti-rotation stopping indent is concavely curved and follows an imaginary circular cylinder with a first diameter d.sub.1 (not shown), extending along a first longitudinal axis A.sub.1 which is inclined with respect to the common central axis C.sub.1. The convexly curved surface 109 of the rotation stop 108 of the insert seat 104 has a corresponding shape and follows an imaginary circular cylinder with a second diameter d.sub.2 (not shown) extending along a second longitudinal axis A.sub.2 which is parallel to the axis A.sub.1, wherein d.sub.1>d.sub.2. In a section taken perpendicularly to the axes A.sub.1 and A.sub.2, the concavely curved surface 206 and the convexly curved surface 109 follow circular arcs. As seen in the axial plane P.sub.1, the second stop surface 109 and the first stop surface 206 form straight lines, which are obliquely oriented with respect to the bottom support surface 106 and the bottom surface 202 and extend along the axes A.sub.1 and A.sub.2 at an angle γ of 50° with respect to the bottom support surface 106. The angle γ may preferably be within the interval 30-75°. Here, the angle γ differs by 25° from the clearance angle β of 75°.

[0077] The contact occurring between the first stop surface 206 and the second stop surface 109 upon rotation of the cutting insert about the common central axis C.sub.1 is in the first embodiment a limited area contact or a point contact occurring on or close to the transition between the second stop surface 109 and the first duct 110.

[0078] In the second and third embodiments, shown in FIGS. 7-11 and FIG. 12 respectively, the cutting insert 200 is identical to the cutting insert 200 of the first embodiment. However, the convexly curved surface 109 of the rotation stop 108 of the insert seat 104 may in this embodiment be described as an extruded spline extending along the axis A.sub.2. In a section taken perpendicularly to the axis A.sub.2, the convexly curved surface 109 follows a spline, i.e. it comprises portions with different radii of curvature. The second stop surface 109 and the first stop surface 206 form non-parallel straight lines as seen in the axial plane P.sub.1, which straight lines are obliquely oriented with respect to the bottom support surface 106 and the bottom surface 202. As in the first embodiment, the straight line formed by the first stop surface 206 extend at an angle γ of 50° with respect to the bottom support surface 106.

[0079] The second embodiment differs from the third embodiment in that the side support surfaces 113, 114 of the side wall 107 of the insert seat 104 are configured to contact the side surface 203 of the cutting insert 200 only along an upper portion of the side surface 203. A lower portion of the side wall 107 therefore extends at a different angle with respect to the common central axis C.sub.1 than the side support surfaces 113, 114.

[0080] The contact occurring between the first stop surface 206 and the second stop surface 109 upon rotation of the cutting insert about the common central axis C.sub.1 is in the second and third embodiments a line contact extending between a first position on the transition to the first duct 110 or close to the first duct 110, and a second position on the transition to the second duct 115 or close to the second duct 115. This is illustrated in FIG. 11, showing the anti-rotation stop 108 of the second embodiment, wherein the line contact is schematically indicated as a shaded area.

[0081] In the fourth embodiment shown in FIGS. 13-15, the first stop surface 206 of the anti-rotation stopping indent 205 comprises a first pair of planar surface portions 207, 208 positioned on either side of a concavely curved surface portion 209. The second stop surface 109 of the anti-rotation stop 108 correspondingly comprises a second pair of planar surface portions 111, 112 adjacent to the first duct 110 and the second duct 115, extending on either side of a convexly curved surface portion 116. The first planar surface portion 207 is herein parallel to the second planar surface portion 111, but it is also possible for the surface portions to be non-parallel. The second planar surface portions 111, 112 of the anti-rotation stop 108, as well as the convexly curved surface portion 116 thereof, are completely located within the rotation stopping indent 205 as the cutting insert 200 is mounted in the insert seat 104. As in the first embodiment, the second stop surface 109 and the first stop surface 206 form parallel straight lines as seen in the axial plane P.sub.1, which straight lines are obliquely oriented at an angle γ of 50° with respect to the bottom support surface 106 and the bottom surface 202.

[0082] In the fourth embodiment, the contact between the first stop surface 206 and the second stop surface 109 occurring upon rotation of the cutting insert about the common central axis C.sub.1 is between one of the second planar surface portions 111, 112 of the insert seat 104 and a corresponding one of the first planar surface portions 207, 208 of the cutting insert 200, depending on the direction of rotation of the cutting insert 200 in the insert seat 104. With parallel surface portions, an area contact may arise upon rotation of the cutting insert, while as for non-planar surface portions a linear contact may arise.

[0083] The cutting tool may of course comprise a different number of insert seats and cutting inserts than in the above described embodiments. A fastening member other than a screw, for example a clamp, may be used for fastening the cutting insert. The cutting insert may also comprise a different number of anti-rotation stopping indents, depending on e.g. the size of the cutting insert. The cutting tool may also comprise a cassette holding the cutting insert, or a shim plate positioned between the bottom support surface of the insert seat and the bottom surface of the cutting insert.

[0084] Further modifications of the invention within the scope of the appended claims are feasible. As such, the present invention should not be considered as limited by the embodiments and figures described herein. Rather, the full scope of the invention should be determined by the appended claims, with reference to the description and drawings.