Turning Inserts for Metal Cutting
Patent Information
- Application Number
- JP2021550187
- Authority / Receiving Office
- JP · JP
- Patent Type
- Patents
- Current Assignee / Owner
- Priority Date
- 2019-02-28
- Filing Date
- 2020-02-03
- Publication Date
- 2025-03-03
- Estimated Expiration
- 2040-02-03
Smart Images
Figure 0007638216000001 
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Abstract
Description
[Technical field]
[0001] The present invention relates to the technical field of metal cutting, more specifically to the field of turning inserts used for metal cutting in machining tools such as computer numerical control (CNC) machines. [Background technology]
[0002] The present invention refers to a turning insert according to the preamble of claim 1, a turning tool including such a turning insert, and a method for machining a metal workpiece using such a turning tool. In other words, the present invention relates to a turning insert. The turning insert comprises a top surface, an opposite bottom surface, a side surface connecting the top surface and the bottom surface, a reference surface located parallel to the top surface and the bottom surface, a central axis extending perpendicularly to the reference surface and intersecting the reference surface, and three nose sections formed symmetrically about the central axis. Each of the nose sections comprises a first cutting edge, a second cutting edge, and a convex nose cutting edge connecting the first cutting edge and the second cutting edge. In a top view, the first cutting edge and the second cutting edge on the same nose section form a nose angle with respect to each other.
[0003] In turning a metal workpiece, the metal workpiece rotates about a central axis. The metal workpiece is clamped at one end by one or more rotatable clamping means such as chucks or jaws. This clamped end of the workpiece can be called the clamping end or driving end. For stable clamping, the clamping end or driving end of the metal workpiece can have a larger diameter than the opposite end of the metal workpiece and / or a portion of the metal workpiece located between the clamping end and the opposite end can have a larger diameter. Alternatively, the metal workpiece can have a constant diameter before the machining operation, i.e., the metal cutting operation. The turning insert is moved with respect to the metal workpiece. This relative motion is called feeding. The movement of the turning insert can be in a direction parallel to the central axis of the metal workpiece. This is commonly called longitudinal feeding or axial feeding. The movement of the turning insert can also be in a direction perpendicular to the central axis of the metal workpiece. This is commonly called radial feeding or facing. Movements at other angles or feed directions are also possible. This is commonly known as copying or copy turning. In copying, the feed has both an axial and a radial component. During the relative movement of the turning inserts, material is removed from the metal workpiece in the form of chips. The chips are preferably short and / or have such a shape or direction of movement as to prevent chip jamming and / or poor surface finish of the machined surface.
[0004] A common shape of turning insert that can be used in a wide range of feed directions is the triangular turning insert. Such an insert has a triangular shape in top view, i.e., on the rake face facing the viewer, with all three sides of equal length and a nose angle of 60°. Each corner of the triangle is in the form of a nose cutting edge, which typically has a radius of curvature ranging from 0.2 mm to 2.0 mm. Examples of such turning inserts are TNMG and TCMT, which are commonly designed according to ISO standards and are generally made at least in part from coated or uncoated sintered carbide, or cubic boron nitride (CBN), or ceramic, or cermet.
[0005] In radial turning, the feed direction is perpendicular to and toward the axis of rotation of the metal workpiece. This is called facing. Radial turning away from the axis of rotation of the metal workpiece is also known as outfacing, and while this can be preferable when machining certain components, using common turning inserts such as TNMG or TCMT presents disadvantages, including poor chip control.
[0006] The turning insert in US4632608 is intended to overcome the drawbacks in outfacing. The insert includes three nose sections. In one embodiment, the nose sections have a circular shape. In the outfacing, a portion of the circular cutting edge is the only effective cutting edge. In a further embodiment, the outer edge of each nose section consists of multiple cambered segments with a nose angle of 60°. For this embodiment, in the outfacing, a portion of the straight cutting edge and a portion of the convexly curved nose cutting edge are the only effective cutting edges in the outfacing. The turning insert in US4632608 can be used to machine two walls forming a 90° outside corner in a metal workpiece, where one wall at a distance farther from the axis of rotation is perpendicular to the axis of rotation and one cylindrical wall at a distance closer to the axis of rotation is parallel to the axis of rotation. Here, the two walls are connected by a circular or curved segment. A 90° outside corner in this context is a 90° corner on or formed on the exterior face or outer surface of a metal workpiece such that a cylindrical wall or surface faces away from the axis of rotation. This is in contrast to any corner that may be on or formed on the interior face or inner surface within a bore concentric with the axis of rotation.
[0007] The circular or curved segment is a shape of a circular arc, a shape of a quarter circle, or a quarter of a substantially circular shape, having the same radius of curvature as the nose cutting edge of the turning insert in a cross section in a plane containing the axis of rotation. The circular or curved segment alternatively has a larger radius of curvature than the nose cutting edge of the turning insert. More specifically, in US4632608, machining two walls forming a 90° outside corner is performed by an axial turning operation followed by an outfacing operation, where the same part of the effective nose part is effective in both operations. The axial turning operation described above is towards the clamping end of the metal workpiece and towards the corner wall perpendicular to the axis of rotation of the metal workpiece.
[0008] In EP 3153260 A1 it is said that chip control is reduced when the turning insert moves closer to the aforementioned walls which extend perpendicular to the axis of rotation and are at a greater distance from the axis of rotation.
[0009] In EP 3 153 260 A1 it is found that an alternative method of machining two walls forming a 90° outside corner in a metal workpiece is more effective in terms of insert wear and / or chip breaking and / or chip control and that the new turning insert offers a further improvement compared to known turning inserts. Summary of the Invention
[0010] In EP 3 153 260 A1 the inventors found that chip breaking could be improved.
[0011] The object of the present invention is to provide a turning insert including three nose sections suitable for economically machining two walls forming 90° outside corners in metal workpieces, which improves chip breaking when machining with entering angles between 10° and 45°.
[0012] This object is achieved with a turning insert as defined above, characterized in that the first cutting edge comprises a first sub-region and a second sub-region, the distance from the nose cutting edge to the first sub-region is less than the distance from the nose cutting edge to the second sub-region, the distance from the first sub-region to the reference surface is shorter away from the nose cutting edge and the distance from the second sub-region to the reference surface is longer away from the nose cutting edge, and the bottom surface comprises an anti-rotation means.
[0013] The top surface includes a rake surface. The bottom surface includes a seat surface. The reference surface is parallel to the surface on which each of the nose cutting edges is located. Each of the nose cutting edges is preferably the cutting edge located at the furthest distance from the reference surface. Each of the nose cutting edges is located equidistant from the central axis. The central axis passes through the geometric center of the insert. Preferably, the central axis is in the center of the through hole for the clamping screw. Each of the nose sections is formed symmetrically about the central axis, i.e. each of the nose sections forms an angle of 120° with each of the other nose sections. The nose sections are distal sections of the turning insert with respect to the center of the turning insert. At least one portion of one nose section is active during machining, i.e. in contact with the metal workpiece. Each of the nose sections includes a cutting edge at least adjacent to or having a common boundary with the top surface. The turning insert may be double-sided or reversible, i.e. the bottom surface may include a set of cutting edges similar or identical to the top surface. Each nose cutting edge forms the furthest portion of the turning insert. In other words, each nose cutting edge is the part of the cutting insert located at the furthest distance from the central axis of the turning insert. The nose portion is the peripheral portion of the cutting insert. Here, the rake surface is formed on or at the top surface between the first cutting edge, the second cutting edge, and the nose cutting edge. The nose cutting edge preferably has the shape of a portion of an arc or circle having its center between the first cutting edge and the second cutting edge. Here, the circle preferably has a radius of 0.2 mm to 2.0 mm. Alternatively, the nose cutting edge may have the shape of an elliptical arc. Alternatively, the nose cutting edge may have the shape of one or more arcs of a circle, or an elliptical arc, as well as a combination of straight portions. These together form a nose cutting edge that is convex in top view. A top view is a view in which the top surface faces the viewer and the bottom surface does not face the viewer. The first cutting edge and the second cutting edge are preferably straight in a top view.If the first and second cutting edges are not straight in top view, for example slightly convex or slightly concave, the nose angle is measured using a straight line between the respective end points of the first and second cutting edges. If the first and second edges are slightly convex or slightly concave, the radius of curvature for the first and second cutting edges is more than 5 times, preferably more than 10 times, the radius of curvature for the nose cutting edge. Alternatively, a nose angle of 25° to 50° is equivalent to a nose cutting edge having the shape of an arc with an angle of 25° to 50°. All nose cutting edges are preferably located in a common plane parallel to the reference plane. The cutting edge is the edge of the turning insert that separates the rake face and the clearance face, also known as the relief face. The length of the arc of the nose cutting edge is less than the length of both the first and second cutting edges. Preferably, the turning insert is one-sided, with the area of the top surface being larger than that of the bottom surface, such that both the top and bottom areas protrude above the reference plane RP. The turning insert is preferably at least partially made from a piece of coated or uncoated superhard cemented carbide or cermet. Alternatively, the turning insert may be at least partially made from cubic boron nitride (CBN), poly crystalline diamond (PCD), or ceramic. The turning insert is removably mountable in the tool body, for example, by means of a screw or a clamp. Preferably, a through hole extends between the top and bottom surfaces.
[0014] Preferably, the first sub-section is inclined at an angle of 1° to 5°, even more preferably 2° to 4°. The first sub-section is inclined downwards in side view, i.e., towards the reference plane and away from the nose cutting edge. Preferably, the second sub-section is inclined at an angle of 1° to 5°, even more preferably 2° to 4°. The second sub-section is inclined upwards in side view, i.e., away from the reference plane and away from the nose cutting edge.
[0015] Preferably, the length of the first sub-section, as viewed in top view, is between 1.0 mm and 6.0 mm, even more preferably between 1.5 mm and 4.0 mm. Preferably, the length of the second sub-section, as viewed in top view, is between 1.0 mm and 6.0 mm, even more preferably between 1.5 mm and 4.0 mm. Preferably, the length of the first cutting edge, as viewed in top view, is between 2.5 mm and 10.0 mm. Preferably, the length of the first cutting edge, as viewed in top view, is between 10% and 40% of the distance between the two nose cutting edges.
[0016] The bottom surface includes an anti-rotation means. Such a turning insert improves radial turning in opposite directions and / or axial turning in opposite directions when the turning insert is placed in a tool body. Furthermore, the positioning of the insert is improved, which reduces the need for a side surface to act as a contact surface. This improves the versatility of the turning tool with respect to feed direction. The anti-rotation means can be in the form of one or more ridges, grooves, protrusions, or cavities, or a combination of such features. The anti-rotation means is suitable for interaction by contact with a corresponding structure in the tool body, or a shim placed in the tool body, to which the turning insert can be removably clamped. The anti-rotation means prevents or at least reduces rotation or movement of the turning insert in two opposite directions about the central axis of the turning insert.
[0017] According to one embodiment, the first cutting edge includes a third sub-region, the third sub-region being between the first sub-region and the second sub-region, the third sub-region being concave in side view.
[0018] According to one embodiment, the third sub-section is the lowest section of the first cutting edge in side view.
[0019] In other words, the distance from the reference surface to the third sub-portion is less than the distance from the reference surface to all other portions of the first cutting edge.
[0020] According to one embodiment, the anti-rotation means is in the form of three grooves, each having a main extension along a bisector located between adjacent first and second cutting edges.
[0021] Such turning inserts allow the insert to be indexed in three positions in the same insert seat. The orientation of the grooves is symmetrically oriented with respect to the first and second cutting edges so as to fully prevent rotation in both axial turning in opposite directions and radial turning (facing and outfacing) in opposite directions. In other words, for each of the nose sections, the bisector located between the first and second cutting edges has the same extension as the main extension of the grooves in the bottom surface of the insert in the same nose section. As a result, all three grooves have their main extension in a direction towards the central axis of the turning insert. Preferably, the angle between pairs of grooves is 120° when viewed in a bottom view with the reference plane perpendicular to the viewer's point of view.
[0022] According to one embodiment, the first cutting edge and the second cutting edge are linear or straight in a top view.
[0023] With such turning inserts, the direction of the cutting forces and / or the direction of the chip flow become less dependent on the cutting depth, i.e. the depth of cut. In this context, a concave or convex radius of curvature of more than 200 mm is considered to be straight or linear.
[0024] According to one embodiment, each bisector extends equidistantly from each pair of first and second cutting edges. Each bisector intersects the central axis. The first and second cutting edges are symmetrical or substantially symmetrical with respect to each bisector in their respective side views.
[0025] Such turning inserts reduce the risk of interference from ineffective nose cutting edges when machining in two directions, which may be perpendicular. Such turning inserts allow the inserts to be used on metal workpieces clamped at opposite ends. In other words, the first and second cutting edges on or formed on the same nose part are equidistant from the bisector. Thus, the bisector is located between the first and second cutting edges. The first and second cutting edges are located on or on opposite sides of the bisector. Each bisector forms an angle of 120° with any other bisector. Each bisector intersects with the central axis. Each bisector intersects with the center of the nose cutting edge on or formed on the same nose part as the first and second cutting edges.
[0026] The first cutting edge and the second cutting edge are symmetrical or substantially symmetrical with respect to a bisector in each side view. In other words, the first cutting edge and the second cutting edge are symmetrical with respect to a bisector. Preferably, the nose section is symmetrical with respect to a bisector. Such turning inserts allow the inserts to be used in right and left tools. Thus, mixing of turning inserts can be reduced.
[0027] According to one embodiment, each bisector extends equidistantly from each of the pair of first and second cutting edges. Each bisector intersects the central axis. The top surface includes a protrusion having an extension along the bisector. The protrusion includes a first chip breaker wall opposite the first cutting edge and a second chip breaker wall opposite the second cutting edge.
[0028] Such turning inserts further improve chip breaking and / or chip control. One additional advantage is a reduced risk of chips hitting the machined surface, which may impair the surface quality of the machined metal workpiece, i.e., component. The protrusions may extend farther from the reference surface than the periphery of the top surface. A rake surface is formed between the protrusions and the cutting edge.
[0029] Preferably, the upper surface of the turning insert is recessed between the first cutting edge and the first chip breaker wall. In other words, the upper surface of the turning insert, which is between the first cutting edge and the first chip breaker wall, is located at a closer distance from the reference plane compared to the adjacent portion of the first cutting edge and the first chip breaker wall. The adjacent portion in this context should be understood as the portion along a line perpendicular to the first cutting edge in a top view.
[0030] The top surface includes a protrusion having an extension along at least one of the bisectors.
[0031] According to one embodiment, the upper surface includes a second protrusion having an extension along the bisector. The second protrusion is between the nose cutting edge and the protrusion. In a side view, the upper surface of the second protrusion is lower than the upper surface of the protrusion.
[0032] Such turning inserts further improve chip breaking, especially at shallow depths of cut, such as when only the nose cutting edge is effective.
[0033] The second projection has an extension along the bisector, in other words, the second projection intersects the bisector in a top view, and includes a first chip breaker wall facing the first cutting edge and a second chip breaker wall facing the second cutting edge.
[0034] The distance from the top surface of the second projection to the reference surface is less than the distance from the top surface of the projection to the reference surface.
[0035] Preferably, the distance from the nose cutting edge to the reference surface is less than the distance from the top surface of the second projection to the reference surface.
[0036] Preferably, the second projection is U-shaped in top view, where the convex portion of the second projection faces the nose cutting edge, and the concave portion is therefore arc-shaped or arc-like in top view, the arc being between 150° and 220°.
[0037] According to one embodiment, the distance between the top surface of the protrusion and the lowest point of the first cutting edge, measured in a plane perpendicular to the reference plane, is between 0.36 mm and 0.7 mm.
[0038] Such turning inserts further improve chip breaking and / or chip control.
[0039] The distance is in a side view. Preferably, the distance 61 is 0.40 mm to 0.55 mm. The distance is measured to the top surface of the projection, preferably the highest point of the turning insert as viewed in a side view.
[0040] Preferably, the height of the projection decreases in a direction toward the nose cutting edge.
[0041] According to one embodiment, in top view, the distance from the second sub-section to the first chip breaker wall decreases further away from the nose cutting edge.
[0042] Such turning inserts further improve chip breaking and / or chip control.
[0043] In a differently formed one, the distance from the upper boundary line of the first chip breaker wall to the second sub-region decreases in a direction away from the nose cutting edge, the distance being measured in a direction perpendicular to the second sub-region in a top view. Preferably, and in a top view, the angle formed between the upper boundary line of the first chip breaker wall and the second sub-region is between 2° and 20°, even more preferably between 5° and 15°. The angle is measured in a top view.
[0044] According to one embodiment, the distance between the nose cutting edge and the lowest point of the first cutting edge, measured in a plane perpendicular to the reference plane, is between 0.05 mm and 0.4 mm.
[0045] Such turning inserts further improve chip breaking and / or chip control.
[0046] The distance is in a side view. Preferably, the distance is 0.08 mm to 0.25 mm. The distance is measured to the top surface of the projection, preferably the highest point of the turning insert as viewed in a side view.
[0047] According to one embodiment of the invention, the top and bottom surfaces are identical. The anti-rotation means are in the form of a set of surfaces. The surfaces each extend in a plane forming an angle between 5° and 60° with respect to a reference plane.
[0048] Such a configuration allows the turning insert to be double-sided and include an anti-rotation means that the turning insert can be used with the front bottom surface as the rake face.
[0049] According to one embodiment of the invention, a turning tool includes a turning insert according to the invention and a tool body having a front end, an opposite rear end, a main extension along a longitudinal axis A2 extending from the front end to the rear end, and an insert seat formed at the front end in which the turning insert can be seated such that a bisector of the effective nose portion forms an angle θ of 35° to 55° with respect to the longitudinal axis A2 of the tool body.
[0050] With such a turning tool, the turning insert is positioned or positioned to allow a wider range of feed directions. With such a turning tool, for the same nose section, a first cutting edge can be used for axial turning and a second cutting edge can be used for outfacing, with one section of the nose cutting edge being ineffective, i.e., wear-free, for both operations, i.e., for both feed directions. With such a turning tool, the cut angle of the first cutting edge during axial turning away from the clamping end of the metal workpiece is less than 45°, at least less than 10°. The inventors have found that such a cut angle reduces wear on the insert during axial turning, where the insert moves in a direction away from the clamping end of the metal workpiece. With such a turning tool, the cut angle of the second cutting edge during outfacing, i.e., feeding perpendicularly away from the rotation axis of the metal workpiece, is less than 45°, at least less than 10°. The inventors have found that such a cutting angle reduces wear of the insert during outfacing. The effective nose section is the nose section that includes a nose cutting edge that is the part of the turning insert that, in a top view, in a rested state, is furthest away from the rear end of the tool body and from the longitudinal axis of the tool body. The angle that the first cutting edge of the effective nose section forms with the longitudinal axis of the tool body is greater than the angle that the second cutting edge of the effective nose section forms with the longitudinal axis of the tool body. The longitudinal axis of the tool body is preferably perpendicular to the axis of rotation of the metal workpiece. The central axis of the turning insert in the rested state is substantially perpendicular (70° to 110°) with respect to the longitudinal axis of the tool body. The insert seat of the tool body preferably includes insert rotation means that correspond to the insert rotation means formed on the bottom surface of the turning insert. The rear end of the tool body is the part of the tool body that is furthest away from the effective nose cutting edge.
[0051] According to one embodiment of the present invention, the sum of the angle θ and half the angle α is greater than or equal to 50° and less than or equal to 70°, in other words, 50°≦θ+(α / 2)≦70°.
[0052] With such a turning tool, chip breaking and / or chip control is further improved during outfacing and during axial turning away from the clamping end of the metal workpiece. With such a turning tool, a 90° outside corner can be machined in the metal workpiece, where one wall of the corner is perpendicular to the rotation axis of the metal workpiece and one wall of the corner is parallel to the rotation axis of the metal workpiece. The two walls are connected by a surface having the same radius of curvature as the nose cutting edge of the turning insert. With such a turning tool, the leading angle of the first cutting edge is between 20° and 40° during axial turning away from the clamping end of the metal workpiece. The inventors have found that such leading angle reduces wear of the insert. With such a turning tool, the leading angle of the second cutting edge is between 20° and 40° during outfacing. The inventors have found that such a leading edge angle reduces wear on the insert.
[0053] According to one embodiment of the invention, a method for machining a metal workpiece is performed using a turning insert according to the invention. The method includes clamping the metal workpiece at a first end, rotating the metal workpiece about a rotation axis A3, positioning a first cutting edge of the active nose portion such that the first cutting edge forms an angle with respect to the rotation axis A3 of the metal workpiece that is smaller than the angle formed by the second cutting edge with respect to the rotation axis of the metal workpiece, and moving the turning insert in a direction perpendicular to the rotation axis A3 away from the rotation axis A3 so that the second cutting edge is active. The active nose portion is a nose portion that is positioned such that during cutting, the nose portion includes at least one cutting edge that cuts chips from the metal workpiece. The active nose portion is located closer to the rotation axis of the metal workpiece and closer to the first end of the metal workpiece than the other, i.e. inactive, nose portion. The expression "the second cutting edge is active" means that the second cutting edge cuts chips from the metal workpiece. Additionally, a portion of the nose cutting edge adjacent to the active second cutting edge is active. A first cutting edge formed on or in the same nose portion as the second cutting edge is inactive at the same time the second cutting edge is active. Moving the turning insert is generally known as feeding, or alternatively as outfacing. The second cutting edge is active at a second cutting angle κ2 preferably between 20° and 40°. If the cutting angle is less than 20°, the chip width may be too wide, leading to poor chip control and increased risk of vibration. If the cutting angle is more than 40°, the insert may experience increased wear.
[0054] According to one embodiment of the invention, a method for machining a metal workpiece is performed using a turning insert according to the invention. The method includes clamping the metal workpiece at a first end, rotating the metal workpiece about an axis of rotation, positioning a first cutting edge of the active nose portion such that the first cutting edge forms an angle with respect to the axis of rotation A3 of the metal workpiece that is smaller than the angle formed by the second cutting edge with respect to the axis of rotation of the metal workpiece, and moving the turning insert in a direction parallel to the axis of rotation A3 away from the first end so that the first cutting edge is active. The active nose portion is a nose portion that is positioned such that during cutting, the nose portion includes at least one cutting edge that cuts chips from the metal workpiece. The active nose portion is located closer to the axis of rotation of the metal workpiece and closer to the first end of the metal workpiece than the other, i.e. inactive, nose portions. The expression "the first cutting edge is active" means that the first cutting edge cuts chips from the metal workpiece. Furthermore, a portion of the nose cutting edge proximate to the active first cutting edge is active. A second cutting edge formed on or at the same nose portion as the first cutting edge is inactive at the same time as the first cutting edge is active. The movement of the turning insert is a longitudinal turning operation. The first cutting edge is active at a first cut angle κ1 preferably between 20° and 40°. If the cut is less than 20°, the chip width may be too wide, leading to poor chip control and an increased risk of vibration. If the cut angle is more than 40°, the insert may experience increased wear.
[0055] The invention will be described in more detail below with reference to various embodiments of the invention and the accompanying drawings. [Brief description of the drawings]
[0056] [Figure 1] FIG. 1 is a perspective view showing a turning insert according to a first embodiment. [Diagram 2]FIG. 2 is a perspective view of a nose portion of the turning insert shown in FIG. [Diagram 3] FIG. 3 is a top or front view of the turning insert of FIG. [Figure 4] FIG. 4 is a cross-sectional view taken along line BB in FIG. [Diagram 5] FIG. 5 is a cross-sectional view taken along line CC in FIG. [Figure 6] FIG. 6 is a side view of the turning insert of FIG. [Figure 7] FIG. 7 is a schematic diagram showing turning of a cylindrical surface with a turning insert. [Figure 8] FIG. 8 is a perspective view of a tool body for the turning insert of FIG. [Figure 9a] FIG. 9a is a perspective view showing the bottom surface of the turning insert of FIG. [Figure 9b] FIG. 9b is a further perspective view showing the bottom surface of the turning insert of FIG. [Figure 10] FIG. 10 is a chip chart showing chips from turning using the turning insert of FIG. [Figure 11] FIG. 11 is a chip chart showing chips from turning using the modern turning insert.
[0057] All turning insert drawings are drawn to scale. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0058] A turning insert 1 according to a first embodiment will be described with reference to Figs. 1 to 3, 6, 9a and 9b. The turning insert 1 includes a top surface 8 including a rake surface and an opposite bottom surface 9 functioning as a seat surface. A reference surface RP is located between the top surface 8 and the bottom surface 9 in parallel. A central axis A1 extends perpendicular to the reference surface RP and intersects with the reference surface RP, the top surface 8 and the bottom surface 9. A hole for a screw, having openings in the top surface 8 and the bottom surface 9, is concentric with the central axis A1. The turning insert 1 includes a side surface 13 that functions as a clearance surface and connects the top surface 8 and the bottom surface 9.
[0059] The three nose sections 15, 15', 15'' are formed symmetrically or centered about the central axis A1. The nose sections 15, 15', 15'' are identical. Each of the nose sections 15, 15', 15'' includes a first cutting edge 11, a second cutting edge 12, and a convex nose cutting edge 10 connecting the first cutting edge 11 and the second cutting edge 12. The nose cutting edge 10, 10', 10'' is located at the furthest distance from the central axis A1, i.e., at a farther distance from the central axis A1 than all other parts of the turning insert. In the top view seen in FIG. 3, the first cutting edge 11 and the second cutting edge 12 on or at the same nose section 15 form a nose angle α of 25° to 50° with respect to each other. In FIG. 3, the nose angle α is 35°.
[0060] The first and second cutting edges 11, 12 are linear or straight or substantially linear or straight in top view as seen in FIG. 3. Each bisector 7 extends equidistantly from each pair of first cutting edges 11, 11', 11'' and second cutting edges 12, 12', 12''. Each bisector 7 intersects with the central axis A1. Each indentation 17, 17', 17'' is formed between each pair of nose cutting edges 10, 10', 10''. The first cutting edge 11 includes a first subregion 111, a second subregion 112, and a third subregion 113 between and connecting the first subregion 111 and the second subregion 112. The first subregion 111 abuts the nose cutting edge 10. The distance from the nose cutting edge 10 to the first subregion 111 is shorter than the distance from the nose cutting edge 10 to the second subregion 112. As can be seen in FIG. 6, the distance from the first subregion 111 to the reference plane RP decreases the further away from the nose cutting edge 10. In other words, the first subregion 111 slopes downwards away from the nose cutting edge 10 in the side view. The distance from the second subregion 112 to the reference plane RP increases the further away from the nose cutting edge 10. In other words, the second subregion 112 slopes upwards away from the nose cutting edge 10 in the side view. The third subregion 113 is concave in the side view, as in FIG. 6. The third subregion 113 is the lowest region of the first cutting edge 11 in the side view. The first and second cutting edges 11, 12 are symmetrical with respect to the bisector 7. The second cutting edge 12 therefore includes corresponding sub-portions as described for the first cutting edge 11 .
[0061] The bottom surface 9 seen in figures 9a and 9b includes anti-rotation means. The purpose is to reduce the tendency of the turning insert 1 to rotate around the central axis A1 during cutting. This configuration is three grooves 40, 40', 40''. Each groove 40, 40', 40'' has a main extension in the same direction as the bisector 7 located adjacent to the nearest first cutting edge 11 and second cutting edge 12. Each groove 40, 40', 40'' includes two seating surfaces, preferably at an obtuse angle of 100° to 160° with respect to each other. The turning insert 1 is intended to be securely clamped by clamping means such as a screw or a top clamp to an insert seat 4 located at the front end of the tool body 2, as seen in figure 7. The contact between the insert seat 4 and the turning insert 1 is explained with reference to the shaded areas in figures 8, 9a and 9b. The effective nose cutting area 15 is the part of the insert in which the groove 40 in figure 9b is located. The two seating surfaces of the groove 40 contact two surfaces of a ridge 90 at the bottom of the insert seat 4. One surface of each of the other grooves 40', 40'', which is the surface located the furthest distance from the effective nose cutting edge 10, contacts bottom surfaces 93, 94 at the bottom of the insert seat 4. At least some portions of the side surfaces 13 located the furthest distance from the effective nose cutting edge 10 may contact rear seating surfaces 91, 92 formed at the rear end of the insert seat 4.
[0062] The upper surface includes a protrusion 30. The protrusion 30 includes a first chip breaker wall 34 facing the first cutting edge 11 and a second chip breaker wall 35 facing the second cutting edge 12. The upper surface 8 includes a second protrusion 50 having an extension along the bisector 7, where the second protrusion 50 is between the nose cutting edge and the protrusion 30. In a side view as seen in FIG. 6, the upper surface of the second protrusion is lower than the upper surface of the protrusion 30. For example, as seen in FIG. 2, the second protrusion includes a first chip breaker wall facing the first cutting edge 11 and a second chip breaker wall facing the second cutting edge 12.
[0063] In a side view as seen in Fig. 6, a distance 61 can be defined between the upper surface of the projection 30 and the lowest point of the first cutting edge 11, measured in a plane perpendicular to the reference plane RP, the distance 61 being 0.36 mm to 0.7 mm. A distance 60 can be defined between the nose cutting edge 10 and the lowest point of the first cutting edge 11, measured in a plane perpendicular to the reference plane RP, the distance 60 being 0.05 mm to 0.4 mm.
[0064] The reference plane RP is located between and equidistant from the top and bottom surfaces 9. Although the top and bottom surfaces are not flat, the reference plane RP can be positioned such that it is juxtaposed to a plane that intersects the three nose cutting edges 10.
[0065] 3, the distance from the second sub-region 112 to the first chip breaker wall 34 decreases the further away from the nose cutting edge 10. The angle λ formed between the upper boundary of the first chip breaker wall 34 and the second sub-region 112 is between 2° and 20°, and even more preferably between 5° and 15°.
[0066] Side surfaces 13 connect the top surface and the bottom surface 9. Figures 4 and 5 show cross-sectional views along lines BB and CC, respectively, in Figure 3. Cross-section CC is perpendicular to the second cutting edge 12'', in a plane perpendicular to the reference plane RP.
[0067] Indentations 17, 17', 17'' are formed in the side surfaces 13 between each pair of nose cutting edges 10, 10', 10'', respectively.
[0068] Please refer to FIG. 7. This shows a turning operation using a turning tool including a turning insert 17. A metal workpiece 50 is clamped by a clamping means (not shown) connected to a machine (not shown) including a motor (not shown), such as a CNC machine or a lathe. The clamping means preferably presses the metal workpiece 50 at a first end 54, or clamping end, on its outer surface. The opposite second end 55 of the metal workpiece 50 is the free end. The metal workpiece rotates about a rotation axis A3. The turning insert, seen in a top view, is securely and removably clamped by means of a screw 6 in an insert seat or pocket in the tool body 2. The tool body 2 has a longitudinal axis A2 extending between its rear end and its front end 44, where the insert seat or pocket is located. In FIG. 7, the feed is as axial as possible, which is also called longitudinal feed. That is to say, the feed direction is parallel to the rotation axis A3. In this way, an outer cylindrical surface 53 is formed. Just before each cutting infeed, or axial feed, the feed has a radial component such that the turning insert moves along the arc of a circle.
[0069] The turning insert comprises an active nose section 15, which comprises an active nose cutting edge 10. The active nose section 15 further comprises an active first cutting edge having a leading angle κ1 during axial turning parallel to the axis of rotation A3, selected in the range of 10° to 45°, preferably 20° to 40°. The first cutting edge, which is the main cutting edge during operation, is in front of the nose cutting edge 10 in the axial feed direction. In other words, the first cutting edge is a leading edge. A second cutting edge formed on or in the active nose section 15 is a secondary cutting edge or a trailing edge. When the feed direction is radial, such as vertically away from the axis of rotation A3, the second cutting edge is active with a leading angle κ2. A bisector 7 is defined by the first cutting edge and the second cutting edge. In other words, the bisector is formed between the first cutting edge and the second cutting edge. The first cutting edge and the second cutting edge converge at a point on the outside of the turning insert. A bisector of the effective nose section 15 forms an angle θ of 40° to 50° with respect to the longitudinal axis A2. The turning insert includes two ineffective nose sections including two ineffective nose cutting edges 10′, 10″. In an axial turning operation, all parts of the turning insert are in front of the effective nose cutting edge 10 in the feed direction. In an axial turning operation, chips can be directed away from the metal workpiece without any trouble. In a machining step, the turning insert 1 cuts into the metal workpiece 50 such that the nose cutting edge 10 moves along an arc of a circle. The turning insert 1 cuts into or enters the metal workpiece 50 such that the thickness of the chips during the cut is constant or substantially constant. In the cut, the depth of cut increases from a zero depth of cut. Such a preferred infeed reduces wear on the insert, particularly at the nose cutting edge 10. The chip thickness is defined as the feed rate multiplied by the infeed angle. Thus, by selecting and / or varying the feed rate and the movement and / or direction of the turning insert during the infeed, the chip thickness can be made constant or substantially constant.The feed rate during the cut is preferably less than or equal to 0.50 mm / rev. The chip thickness during the cut is preferably less than or equal to the chip thickness during the subsequent cutting or machining.
[0070] The cylindrical surface 53, or reasonably symmetrical surface, at least partially created or formed by the nose cutting edge of Figures 1 and 2 has a corrugation profile with low peaks and valleys. The corrugation profile is at least partially affected by the radius of curvature of the nose and the feed rate. The height of the corrugations is less than 0.10 mm, preferably less than 0.05 mm. In this case, the cylindrical surface 53 has no thread profile.
[0071] The turning insert in figure 7 is the turning insert shown in EP 3153260 A1, but the turning insert according to the invention can be used analogously.
[0072] Figures 10 and 11 show chip charts from turning, more specifically from longitudinal turning. Here, the first cutting edge has a 30° leading angle, as shown in Figure 7, but there is no arc-shaped leading edge of the cut. The chip charts are made under the same conditions. Here, the workpiece material is a carbon manganese steel of type S355J2 according to European standard EN10025-2. In Figure 10, the turning insert is according to the invention, as seen in Figures 1 to 3, Figure 6, Figures 9a and 9b. In Figure 11, the turning insert is a modern one, similar or identical to the insert shown in Figures 16a to 16d of EP3153260A1.
[0073] The chip charts show chips from 20 different cutting conditions, respectively. Shown horizontally is the feed rate in mm per revolution. From left to right: 0.1, 0.2, 0.3, 0.4, 0.5. Shown vertically is the depth of cut in mm, i.e. cutting depth. From bottom to top: 0.5, 1, 2, 3. As can be seen when comparing chips from corresponding conditions, the chips in FIG. 10 are typically shorter or more suitably shaped compared to the chips in FIG. 11.
[0074] According to a second embodiment (not shown), the top and bottom surfaces are identical. This means that in the initial position, the top surface 8 serves as a rake surface, and when the insert is turned over, the same surface now serves as a seat surface. A reference surface is located parallel between the top and bottom surfaces. A central axis extends perpendicular to the reference surface and intersects the reference surface, the top surface 8 and the bottom surface. A hole for the screw, with openings in the top and bottom surfaces, is concentric with the central axis. The turning insert comprises a side surface which serves as a clearance surface and connects the top and bottom surfaces. The three nose sections are formed symmetrically with respect to or around the central axis. The nose sections are identical. Each of the nose sections comprises a first cutting edge, a second cutting edge and a convex nose cutting edge which connects the first cutting edge and the second cutting edge. The nose cutting edge is located at the furthest distance from the central axis, i.e. at a distance farther from the central axis than all other parts of the turning insert. In top view, the first and second cutting edges on or at the same nose section form a nose angle of 25° to 50° relative to each other. In side view, the first and second cutting edges are formed to correspond to the turning insert according to the first embodiment. The first and second cutting edges are linear or straight or substantially linear or straight in top view. Each bisector extends equidistantly from each pair of first and second cutting edges. Each bisector intersects with the central axis. The turning insert comprises an anti-rotation means in the form of a set of surfaces, where each surface extends in a plane that forms an angle of 5° to 60° with respect to a reference plane. Each set of surfaces is preferably formed as part of a central ring-shaped projection, preferably extending around a central axis, as shown in Figures 13a to 13d of EP 3153260 A1. Such a configuration allows the turning insert to be double-sided or reversible, expanding the possibilities for use.
[0075] The invention is not limited to these disclosed embodiments, but is capable of variation and modification within the scope of the claims set forth below.
Claims
1. A top surface (8); The bottom surface (9) on the opposite side; A side surface (13) connecting the top surface (8) and the bottom surface (9); A reference plane (RP) located parallel to the top surface (8) and the bottom surface (9); A central axis (A1) extending perpendicularly to the reference plane (RP) and intersecting the reference plane (RP); Three nose portions (15, 15', 15'') formed symmetrically around the central axis (A1); Including, each nose section (15, 15', 15'') comprises a first cutting edge (11, 11', 11''), a second cutting edge (12, 12', 12''), and a convex nose cutting edge (10, 10', 10'') connecting said first cutting edge (11, 11', 11'') and said second cutting edge (12, 12', 12''); A turning insert (1), in which, in a top view, the first cutting edge (11) and the second cutting edge (12) on the same nose part (15) form a nose angle (α) of 25° to 50° with respect to each other, The first cutting edge (11) comprises a first sub-region (111), a second sub-region (112) and a third sub-region (113); the distance from the nose cutting edge (10) to the first sub-region (111) is less than the distance from the nose cutting edge (10) to the second sub-region (112); the distance from said first sub-region (111) to said reference plane (RP) decreases the further away from said nose cutting edge (10); the distance from said second sub-section (112) to said reference plane (RP) increases the further away from said nose cutting edge (10); the third sub-region (113) is between the first sub-region (111) and the second sub-region (112); said third sub-section (113) being concave in side view; said bottom surface (9) includes anti-rotation means (40, 40', 40''); a bisector (7) extends equidistantly from each pair of said first cutting edges (11, 11', 11'') and said second cutting edges (12, 12', 12''); Each of the bisectors (7) intersects with the central axis (A1), said upper surface (8) includes a protrusion (30) and a second protrusion (50) having an extension along said bisector (7); the projection (30) comprises a first chip breaker wall (34) facing the first cutting edge (11) and a second chip breaker wall (35) facing the second cutting edge (12); the second projection (50) is between the nose cutting edge (10) and the projection (30); the second projection (50) includes a third chip breaker wall facing the first cutting edge (11) and a fourth chip breaker wall facing the second cutting edge (12); the second projection (50) is U-shaped when viewed from above, a convex portion of the U-shape facing the nose cutting edge (10) and a concave portion of the U-shape being an arc or arc-like shape; In a side view, the upper surface of the second protrusion is lower than the upper surface of the protrusion (30). Turning insert (1).
2. 2. The turning insert (1) according to claim 1, wherein said third sub-portion (113) is, in a side view, the lowest portion of said first cutting edge (11).
3. said anti-rotation means being in the form of three grooves (40, 40', 40''); each groove (40, 40', 40'') has a main extension along said bisector (7) located between adjacent said first cutting edge (11, 11', 11'') and said second cutting edge (12, 12', 12''); Turning insert (1) according to claim 1 or 2.
4. Turning insert (1) according to any one of claims 1 to 3, wherein the first and second cutting edges (11, 12) are linear or straight in top view.
5. said first and second cutting edges (11, 12) being symmetrical with respect to said bisector (7) in a top view; Turning insert (1) according to claim 3.
6. 2. The turning insert (1) according to claim 1, wherein a distance (61) between the upper surface of the projection (30) and a lowest point of the first cutting edge (11), measured in a direction perpendicular to the reference plane (RP), is between 0.36 mm and 0.7 mm.
7. 2. The turning insert (1) according to claim 1, wherein in a top view, a distance from the second sub-section (112) to the first chip breaker wall (34) decreases going away from the nose cutting edge (10).
8. 7. The turning insert (1) according to claim 6, wherein a distance (60) between the nose cutting edge (10) and the lowest point of the first cutting edge (11), measured in a direction perpendicular to the reference plane (RP), is between 0.05 mm and 0.4 mm.
9. A turning insert (1) according to any one of claims 1 to 8, A tool body (2); A turning tool (3) comprising: The tool body (2) A front end (44); The rear end of the opposite side, a main extension along a longitudinal axis (A2) extending from said front end (44) to said rear end; an insert seat formed at the front end (44) on which the turning insert (1) can be seated such that a bisector (7) of an effective nose section (15) forms an angle θ of 35° to 55° with respect to the longitudinal axis (A2) of the tool body (2); A turning tool (3).
10. 10. The turning tool (3) according to claim 9, wherein the sum of the angle θ and the half angle of the nose angle (α) is greater than or equal to 50° and less than or equal to 70°.
11. A method for machining a metal workpiece (50) using a turning insert (1) according to any one of claims 1 to 8 or a turning tool (3) according to claim 9 or 10, comprising the steps of: clamping the metal workpiece (50) at a first end (54) of the metal workpiece (50); Rotating the metal workpiece (50) about an axis of rotation (A3); positioning the first cutting edge (11) of an effective nose portion (15) such that the first cutting edge (11) forms an angle with respect to the axis of rotation (A3) of the metal workpiece (50) that is smaller than an angle formed by the second cutting edge (12) with respect to the axis of rotation of the metal workpiece (50); moving the turning insert (1) perpendicularly away from the axis of rotation (A3) so that the second cutting edge (12) is active; A method comprising:
12. A method for machining a metal workpiece (50) using a turning insert (1) according to any one of claims 1 to 8 or a turning tool (3) according to claim 9 or 10, comprising the steps of: clamping the metal workpiece (50) at a first end (54) of the metal workpiece (50); Rotating the metal workpiece (50) about an axis of rotation (A3); positioning the first cutting edge (11) of an effective nose portion (15) such that the first cutting edge (11) forms an angle with respect to the axis of rotation (A3) of the metal workpiece (50) that is smaller than an angle formed by the second cutting edge (12) with respect to the axis of rotation of the metal workpiece (50); moving the turning insert (1) in a direction parallel to the axis of rotation (A3) and away from the first end (54) such that the first cutting edge (11) is active; A method comprising:
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