Indexable turning insert

Abstract

The application discloses a kind of indexable turning inserts, including center line, upper surface, lower surface and multiple side surfaces connecting upper surface and lower surface, two adjacent side surfaces are connected by circular arc surface, the height of each relative reference surface of circular arc cutting edge and main cutting edge is consistent, the height of each relative reference surface of transition cutting edge gradually reduces along the direction away from circular arc surface, the height of each of auxiliary cutting edge is consistent with the lowest point of transition cutting edge;The height of first protruding portion top surface, second protruding portion top surface and mounting positioning surface relative reference surface increases in turn;Upper surface is provided with third protruding portion symmetrically distributed about angle bisector, third protruding portion is located on third rake surface and is connected with second protruding portion.The present indexable turning insert has the advantages of facilitating to guide chip lateral curling, considering the edge strength of nose region, controllable chip shape and chip flow direction, reducing friction, avoiding chip blocking or chip holding and the like.

Description

Technical Field

[0001] This invention relates to the field of metal cutting technology, and more specifically to an indexable turning insert. Background Technology

[0002] In the field of metal turning, machining is generally classified into finishing, semi-finishing, and roughing based on the range of cutting parameters applicable to the turning inserts. Roughing typically uses a larger depth of cut and feed rate to quickly remove most of the machining allowance and achieve the approximate shape and contour of the workpiece. Semi-finishing typically uses a medium depth of cut and feed rate to improve the dimensional accuracy and surface quality of the workpiece. Finishing typically uses a smaller depth of cut and feed rate to achieve the final dimensional accuracy and surface quality requirements of the workpiece.

[0003] Currently, most turning inserts on the market can only perform a single finishing, semi-finishing, or roughing process. However, a part typically requires two to three processes—roughing, semi-finishing, and finishing—to meet its quality requirements. Therefore, machining a part usually necessitates tool changes and tool repositioning, making the process relatively cumbersome and inefficient. To meet the actual machining needs of parts, expanding the range of cutting parameters for inserts has become a pressing issue in the field of metal turning.

[0004] Chinese patent document CN104858460A discloses a turning insert that uses a chip-breaking groove composed of a large elliptical convex ball, two small elliptical convex balls, and herringbone-shaped bosses at the center of the tip to meet the chip control requirements for finishing and semi-finishing. However, this structure still has certain shortcomings in controlling chip curling and chip flow direction under conditions of small cutting depth and feed rate.

[0005] US Patent document US10220448B2 discloses a turning insert with a first protrusion, a second protrusion, and a third protrusion sequentially arranged on its upper surface along a direction extending from a flat upper end towards a corner. The upper height of the second and third protrusions gradually decreases towards the corner. This insert can stably control chips under conditions of small cutting depth and feed rate. However, as the cutting depth and feed rate increase, the forced curling effect of the chip breaker on the chips intensifies, resulting in a certain risk of chip clogging or chip trapping.

[0006] Most turning inserts on the market today control the forced curling of chips by setting a raised chip breaker on the rake face of the insert. Especially under conditions of large cutting depth and feed rate, the chips undergo excessive bending deformation after colliding with the chip breaker, resulting in intense friction between the chips and the insert, which can easily lead to chip clogging and accelerate the rapid wear and failure of the insert. Summary of the Invention

[0007] The technical problem to be solved by the present invention is to overcome the shortcomings of the prior art and provide an indexable turning tool that is conducive to guiding the chips to curl laterally, while taking into account the cutting edge strength in the tool tip area, making the chip shape and chip flow direction controllable, reducing friction, and avoiding chip clogging or chip blockage.

[0008] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: An indexable turning insert includes a centerline, an upper surface, a lower surface, and multiple side surfaces connecting the upper and lower surfaces. Adjacent side surfaces are connected by an arc surface, and the included angle between adjacent side surfaces is the tool tip angle. The upper surface, the arc surface, and the two adjacent side surfaces intersect to form an arc cutting edge. The upper surface and the side surfaces intersect to form a main cutting edge, a transition cutting edge, and an auxiliary cutting edge connected sequentially in the direction away from the arc surface. The arc cutting edge is connected to the main cutting edge. A plane perpendicular to the centerline and located below the auxiliary cutting edge is taken as a reference plane. The height of the arc cutting edge and the main cutting edge relative to the reference plane is the same at all points. The height of the transition cutting edge relative to the reference plane gradually decreases in the direction away from the arc surface. The height of the auxiliary cutting edge is the same as the lowest point of the transition cutting edge. The upper surface is provided with a first protrusion, a second protrusion, a connecting surface, and a mounting positioning surface in sequence along the angle bisector from the arc cutting edge to the center line. The heights of the top surface of the first protrusion, the top surface of the second protrusion, and the mounting positioning surface relative to the reference surface increase sequentially. The second protrusion is smoothly connected to the mounting positioning surface through the connecting surface. The upper surface is provided with a third protrusion symmetrically distributed about the angle bisector, and the third protrusion is connected to the second protrusion.

[0009] As a further improvement to the above technical solution: The length of the main cutting edge is L1, 0.2mm≤L1≤0.8mm; the transition cutting edge is an arc with radius R, 10mm≤R≤60mm; the auxiliary cutting edge is tangent to the transition cutting edge, and the height difference between the auxiliary cutting edge and the main cutting edge relative to the reference surface is H1, 0.1mm≤H1≤0.3mm.

[0010] The third protrusion extends in the direction from the second protrusion to the transition cutting edge, and the angle formed by the centerline of the top surface of the third protrusion and the projection of the opposite main cutting edge onto the mounting and positioning surface is α, where 0≤α≤15°.

[0011] The angle bisector intersects the circular arc cutting edge at point P1, and the centerline intersects the transition cutting edge at point P2. The distance between points P1 and P2 in the extension direction of the main cutting edge is L2, where 0.5mm ≤ L2 ≤ 2mm.

[0012] The width of the third protrusion gradually decreases in the direction from the second protrusion to the transition cutting edge, and the maximum width of the third protrusion is W, 0.3mm≤W≤1mm.

[0013] The top surface of the third protrusion is an inclined plane, and the angle between the top surface of the third protrusion and the mounting positioning surface is β, where 10°≤β≤18°.

[0014] The width of the first protrusion remains constant along the angle bisector; the width of the second protrusion gradually increases along the angle bisector from the arc surface to the center line.

[0015] The second protrusion includes a second protrusion side surface, a second protrusion guide surface, and a second protrusion top surface connected sequentially from the arc surface to the center line. The second protrusion side surface and the second protrusion guide surface are both inclined planes extending along the angle bisector. The angle between the second protrusion side surface and the mounting positioning surface is θ1, 15°≤θ1≤30°, and the angle between the second protrusion guide surface and the mounting positioning surface is θ2, 5°≤θ2≤15°. The second protrusion top surface is a convex curved surface that is higher in the middle and lower at the front and back relative to the reference surface. The first protrusion side surface is an inclined plane extending along the angle bisector, and the angle between it and the mounting positioning surface is θ3, where θ2<θ3<θ1, 10°≤θ3≤20°. The first protrusion top surface is a plane parallel to the mounting positioning surface, and the height of the first protrusion top surface relative to the reference surface is lower than that of the arc cutting edge.

[0016] The length of the top surface of the first protrusion along the angle bisector is greater than the length of the side surface of the first protrusion along the angle bisector; the length of the side surface of the second protrusion along the angle bisector is greater than the length of the guide surface of the second protrusion along the angle bisector, but less than the length of the top surface of the second protrusion along the angle bisector.

[0017] The upper surface and the side surface are connected by a rake face. The rake faces on the upper surface are symmetrically distributed about the angle bisector of the included angle of the tool tip. The rake face includes a first rake face, a second rake face, a transition rake face, and a third rake face that are connected in sequence to form a smooth curved surface. The rake angle of the first rake face is equal. The rake angle of the second rake face gradually increases along the direction away from the arc surface and reaches its maximum at the connection with the transition rake face. The rake angle of the third rake face gradually decreases along the direction away from the arc surface.

[0018] The maximum vertical distance between the top surface of the third protrusion and the third front blade surface is H2, where 0.02mm ≤ H2 ≤ 0.1mm.

[0019] The connecting surface is a concave curved surface.

[0020] Compared with the prior art, the advantages of the present invention are as follows: The indexable turning insert of the present invention, firstly, comprises a cutting edge consisting of an arc cutting edge, a main cutting edge, a transition cutting edge, and an auxiliary cutting edge. The cutting edge adopts a combination design of horizontal edges (arc cutting edge, main cutting edge, and auxiliary cutting edge) and curved edges (transition cutting edge). The arc cutting edge and the main cutting edge have the same height relative to the reference surface at all points. The height of the transition cutting edge relative to the reference surface at all points gradually decreases in the direction away from the arc surface. The auxiliary cutting edge has the same height as the lowest point of the transition cutting edge and remains unchanged. This is beneficial for guiding the chip to curl laterally, while also taking into account the edge strength of the tool tip area. Secondly, the upper surface is provided with a first protrusion and a second protrusion in sequence from the arc cutting edge to the center line along the angle bisector of the included angle of the tool tip. The third protrusion is symmetrically distributed about the angle bisector of the included angle of the tool tip and is connected to the second protrusion. Under the conditions of small cutting depth and small feed rate, the chip shape is stable and controllable after the chip collides with the first and second protrusions. When the cutting depth is further increased, the third protrusion can effectively support the chip, reduce the friction between the chip and the rake face, and avoid chip clogging or chip jamming, thereby achieving stable chip control of the insert within a large range of cutting parameters. Attached Figure Description

[0021] Figure 1 This is a three-dimensional structural schematic diagram of the indexable turning insert of the present invention.

[0022] Figure 2 This is a top view schematic diagram of the indexable turning insert of the present invention.

[0023] Figure 3 yes Figure 1 A magnified view of a portion of point A in the middle.

[0024] Figure 4 yes Figure 3 A projection perpendicular to the side.

[0025] Figure 5 yes Figure 2 A magnified view of a section at point C.

[0026] Figure 6 yes Figure 5 The cross-sectional view of DD, where DD is a plane perpendicular to the plane passing through the centerline B3 and perpendicular to the reference plane.

[0027] Figure 7 yes Figure 5 The cross-sectional view of EE, where EE is a plane passing through the centerline B3 and perpendicular to the reference plane.

[0028] Figure 8 yes Figure 5 The cross-sectional view of FF, where FF is a plane passing through the center line B2 and perpendicular to the reference plane.

[0029] The labels in the diagram represent: 1. Upper surface; 1a. Mounting and positioning surface; 2. Lower surface; 3. Side surface; 4. Arc surface; 5. Arc cutting edge; 6. Main cutting edge; 7. Transition cutting edge; 8. Auxiliary cutting edge; 9. Groove bottom plane; 10. First protrusion; 10a. Side of first protrusion; 10b. Top surface of first protrusion; 11. Second protrusion; 11a. Side of second protrusion; 11b. Top surface of second protrusion; 11c. Guide surface of second protrusion; 12. Third protrusion; 12a. Side of third protrusion; 12b. Top surface of third protrusion; 13. Rake face; 13a. First rake face; 13b. Second rake face; 13c. Transition rake face; 13d. Third rake face; 14. Inclined transition surface; 15. Connecting surface; B1. Centerline; B2. Angle bisector; B3. Centerline; CE. Cutting edge. Detailed Implementation

[0030] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0031] In the description of this invention, it should be understood that the terms "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0032] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0033] In this invention, unless otherwise explicitly specified and limited, the terms "assembly," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0034] Figures 1 to 8This invention illustrates an embodiment of an indexable turning insert. The indexable turning insert of this embodiment includes a centerline B1 (located at the center of the insert), an upper surface 1, a lower surface 2, and multiple side surfaces 3 connecting the upper surface 1 and the lower surface 2. Adjacent side surfaces 3 are connected by an arc surface 4, and the included angle between adjacent side surfaces 3 is the tool tip angle. The upper surface 1, the arc surface 4, and the two adjacent side surfaces 3 intersect to form an arc cutting edge 5. The upper surface 1 and the side surfaces 3 intersect to form a main cutting edge 6, a transition cutting edge 7, and an auxiliary cutting edge 8 connected sequentially in a direction away from the arc surface 4. The arc cutting edge 5 is connected to the main cutting edge 6. A plane perpendicular to the centerline B1 and located below the auxiliary cutting edge 8 is taken as a reference plane. The heights of the arc cutting edge 5 and the main cutting edge 6 relative to the reference plane are consistent. The heights of the transition cutting edge 7 relative to the reference plane gradually decrease in a direction away from the arc surface 4. The heights of the auxiliary cutting edge 8 are consistent with the lowest point of the transition cutting edge 7. The upper surface 1 is provided with a first protrusion 10, a second protrusion 11, a connecting surface 15, and a mounting and positioning surface 1a in sequence from the arc cutting edge 5 to the center line B1 along the angle bisector B2 of the included angle of the blade tip. The heights of the top surface 10b of the first protrusion, the top surface 11b of the second protrusion, and the mounting and positioning surface 1a relative to the reference surface increase in sequence. The second protrusion 11 and the mounting and positioning surface 1a are smoothly connected through the connecting surface 15. The upper surface 1 is provided with a third protrusion 12 symmetrically distributed with respect to the angle bisector B2 of the blade tip angle, and the third protrusion 12 is connected to the second protrusion 11.

[0035] The indexable turning insert has a firstly, a cutting edge CE consisting of an arc cutting edge 5, a main cutting edge 6, a transition cutting edge 7, and an auxiliary cutting edge 8. The cutting edge CE adopts a combination design of horizontal edges (arc cutting edge 5, main cutting edge 6, and auxiliary cutting edge 8) and curved edges (transition cutting edge 7). The arc cutting edge 5 and the main cutting edge 6 have the same height relative to the reference surface at all points. The height of the transition cutting edge 7 relative to the reference surface at all points gradually decreases in the direction away from the arc surface 4. The auxiliary cutting edge 8 has the same height as the lowest point of the transition cutting edge 7 and remains unchanged. This is beneficial for guiding the chips to curl laterally, while also taking into account the edge strength in the tool tip area. Second, the upper surface 1 is provided with a first protrusion 10 and a second protrusion 11 in sequence from the arc cutting edge 5 to the center line B1 along the angle bisector B2 of the included angle of the tool tip. The third protrusion 12 is symmetrically distributed about the angle bisector B2 of the included angle of the tool tip and is connected to the second protrusion 11. Under the conditions of small cutting depth and small feed rate, the chip shape is stable and controllable after the chip collides with the first protrusion 10 and the second protrusion 12. When the cutting depth is further increased, the third protrusion 12 can effectively support the chip, reduce the friction between the chip and the rake face 13, and avoid chip blockage or chip stagnation, thereby achieving stable chip control of the insert within a large cutting parameter range.

[0036] Specifically, the centerline B1 is located at the center of the insert, the upper surface 1 intersects with the side surface 3 and the arc surface 4 to form the cutting edge CE, and the second rake face 13b and the third rake face 13d are smoothly connected via the transition rake face 13c. The second protrusion 11 is smoothly connected to the mounting and positioning surface 1a via the connecting surface 15.

[0037] Furthermore, such as Figure 4 As shown, in this embodiment, the length of the main cutting edge 6 is L1, 0.2mm≤L1≤0.8mm; the transition cutting edge 7 is an arc with a radius of R, 10mm≤R≤60mm; the auxiliary cutting edge 8 is tangent to the transition cutting edge 7, and the height difference between the auxiliary cutting edge 8 and the main cutting edge 6 relative to the reference surface is H1, 0.1mm≤H1≤0.3mm.

[0038] The main cutting edge 6 and the circular arc cutting edge 5 have the same height. The length of the main cutting edge 6 is L1, 0.2mm≤L1≤0.8mm, preferably L1=0.5mm. The transition cutting edge 7 gradually decreases in height along the direction away from the circular arc surface 4 in a circular arc with radius R, 10mm≤R≤60mm, preferably R=20mm. The auxiliary cutting edge 8 is tangent to the transition cutting edge 7. The height difference between the auxiliary cutting edge 8 and the main cutting edge 6 is H1, 0.1mm≤H1≤0.3mm, preferably H1=0.22mm.

[0039] Furthermore, such as Figure 5 As shown, in this embodiment, the third protrusion 12 extends in the direction from the second protrusion 11 to the transition cutting edge 7. The angle formed by the centerline B3 of the top surface 12b of the third protrusion and the projection of the opposite main cutting edge 6 onto the mounting and positioning surface 1a is α, where 0 ≤ α ≤ 15°. Preferably, α = 10°.

[0040] Furthermore, such as Figure 5 As shown, in this embodiment, the angle bisector B2 of the blade tip angle intersects the circular arc cutting edge 5 at point P1, and the centerline B3 intersects the transition cutting edge 7 at point P2. The distance between points P1 and P2 in the extension direction of the main cutting edge 6 is L2, where 0.5mm ≤ L2 ≤ 2mm. Preferably, L2 = 1.4mm.

[0041] Furthermore, such as Figure 5 and Figure 6 As shown, in this embodiment, the width of the third protrusion 12 (the width in the direction perpendicular to the center line B3, i.e., the width direction is perpendicular to the center line B3) gradually decreases in the direction from the second protrusion 11 to the transition cutting edge 7, and the maximum width of the third protrusion 12 is W, 0.3mm≤W≤1mm. Preferably, W=0.5mm.

[0042] The positional constraint of the third protrusion 12 ensures that the cutting tool can effectively support the chips within a wide cutting depth range, preventing excessive chip curling.

[0043] Furthermore, such as Figure 7 As shown, in this embodiment, the top surface 12b of the third protrusion is an inclined plane, and the angle between the top surface 12b of the third protrusion and the mounting positioning surface 1a is β, where 10°≤β≤18°. Preferably, β=12°. The end of the top surface 12b of the third protrusion near the transition cutting edge 7 (the top of the side surface 3) is higher than the other end, and the top surface 12b of the third protrusion is located below the corresponding point on the transition cutting edge 7 [the intersection of EE (the plane passing through the center line B3 and perpendicular to the reference surface) and the transition cutting edge 7]. The lower height and inclined top surface design of the third protrusion 12b are mainly to reduce the friction between the chips and the cutting tool, while avoiding excessive chip curling and deformation that could lead to chip clogging.

[0044] Furthermore, in this embodiment, the width of the first protrusion 10 remains unchanged along the angle bisector B2; the width of the second protrusion 11 gradually increases along the angle bisector B2 from the arc surface 4 to the center line B1.

[0045] Furthermore, such as Figure 5 As shown, in this embodiment, the radius of the arc cutting edge 5 is rξ, the foremost end of the first protrusion 10 faces the arc cutting edge 5, and the distance between it and the arc cutting edge 5 is less than rξ.

[0046] When machining with a small cutting depth, the first protrusion 10 first acts as a chip breaker, and the chip contacts the first protrusion 10 and bends along the first rake face 13a and the second rake face 13b.

[0047] Furthermore, in this embodiment, the second protrusion 11 includes a second protrusion side surface 11a, a second protrusion guide surface 11c, and a second protrusion top surface 11b, which are sequentially connected from the arc surface 4 to the center line B1. The second protrusion side surface 11a and the second protrusion guide surface 11c are both inclined planes extending along the angle bisector B2. The angle between the second protrusion side surface 11a and the mounting positioning surface 1a is θ1, where 15°≤θ1≤30°. The second protrusion guide surface 11c and the mounting positioning surface 1a... The included angle between a and a is θ2, 5°≤θ2≤15°; the top surface 11b of the second protrusion is a convex curved surface that is higher in the middle and lower at the front and back relative to the reference surface; the side surface 10a of the first protrusion extends along the angle bisector B2 and is an inclined plane, and the included angle between it and the mounting positioning surface 1a is θ3, where θ2<θ3<θ1, 10°≤θ3≤20°; the top surface 10b of the first protrusion is a plane parallel to the mounting positioning surface 1a, and the height of the top surface 10b of the first protrusion relative to the reference surface is lower than that of the arc cutting edge 5.

[0048] The top surface 11b of the second protrusion is a convex surface, and has a maximum height from the lower surface 2 or the reference surface at a certain position in the middle of the convex surface. The structure of the convex surface can reduce the friction between the chips and the top surface 11b of the second protrusion when machining with a large cutting depth, thereby reducing the cutting force and cutting temperature.

[0049] Furthermore, in this embodiment, the length of the top surface 10b of the first protrusion extending along the angle bisector B2 is greater than the length of the side surface 10a of the first protrusion extending along the angle bisector B2; the length of the side surface 11a of the second protrusion extending along the angle bisector B2 is greater than the length of the guide surface 11c of the second protrusion extending along the angle bisector B2, and less than the length of the top surface 11b of the second protrusion extending along the angle bisector B2.

[0050] To ensure stable chip control of the cutting tool even under shallow cutting depths, the length of the top surface 10b of the first protrusion (the top surface of the first protrusion 10) along the angle bisector B2 toward the center line B1 (the direction of extension along the angle bisector B2) is greater than the length of the side surface 10a of the first protrusion.

[0051] In addition, such as Figure 8 As shown, the top surface 10b of the first protrusion is a horizontal surface with a height lower than the arc cutting edge 5. The width of the first protrusion 10 is the same along the angle bisector B2 towards the center line B1 (extending along the angle bisector B2). The side surface 10a of the first protrusion is an inclined plane along the angle bisector B2 towards the center line B1, and the angle between it and the mounting positioning surface 1a is θ3, 10°≤θ3≤20°, preferably θ3=15°. Under conditions of small cutting depth, the chips are prone to deformation. The relatively low height of the top surface 10b of the first protrusion and the inclined plane design with a small angle can reduce the friction between the chips and the cutting tool, ensuring stable and controllable chip cutting, while also taking into account strength to prevent the first protrusion 10 from being worn quickly.

[0052] The side surface 11a of the second protrusion is an inclined plane along the angle bisector B2 toward the center line B1, and the angle between it and the mounting positioning surface 1a is θ1, where 15°≤θ1≤30°, preferably θ1=20°. The guide surface 11c of the second protrusion (the guide surface of the second protrusion 11) is an inclined plane along the angle bisector B2 toward the center line B1, and the angle between it and the mounting positioning surface 1a is θ2, where θ2<θ3<θ1, 5°≤θ2≤15°, preferably θ1=8°.

[0053] Furthermore, in this embodiment, the inclination angle of the second protrusion side 11a (the side of the second protrusion 11 facing the arc surface 4) along the angle bisector B2 towards the center line B1 is greater than the inclination angle of the first protrusion side 10a, ensuring that the cutting tool has sufficient strength when performing machining with moderate depth of cut and feed rate. The guide surface is mainly designed to guide the directional flow of chips under moderate depth of cut and feed rate conditions, reducing excessive obstruction to chip flow, while also reducing friction between the chips and the second protrusion 11 and preventing excessive chip curling. The width of the second protrusion 11 gradually increases along the angle bisector B2 towards the center line B1, ensuring that the cutting tool maintains sufficient strength as the depth of cut and feed rate gradually increase.

[0054] Specifically, the end of the second protrusion side 11a, the first protrusion side 10a, and the second protrusion guide surface 11c facing the arc surface 4 is lower than the other end.

[0055] Furthermore, in this embodiment, the rake face 13 distributed inward along the cutting edge CE adopts a single rake angle and variable rake angle design. The upper surface 1 and the side surface 3 are connected by the rake face 13. The rake faces 13 on the upper surface 1 are symmetrically distributed about the angle bisector B2 of the included angle with respect to the tool tip. The rake face 13 includes a first rake face 13a, a second rake face 13b, a transition rake face 13c, and a third rake face 13d connected in sequence to form a smooth curved surface. The rake angle of the first rake face 13a is equal, the rake angle of the second rake face 13b gradually increases in the direction away from the arc surface 4, and reaches its maximum at the connection with the transition rake face 13c. The rake angle of the third rake face 13d gradually decreases in the direction away from the arc surface 4. This unique matching design of the cutting edge and variable rake angle allows the insert to maintain sharpness at a large cutting depth, guides the chip to curl in a specific direction, reduces cutting resistance, and also takes into account the cutting edge strength of the insert.

[0056] Furthermore, in this embodiment, the maximum vertical distance between the top surface 12b of the third protrusion (the top surface of the third protrusion 12) and the third rake face 13d is H2, where 0.02mm ≤ H2 ≤ 0.1mm. Preferably, H2 = 0.05mm. This design allows the chip to collide with the side surface 12a of the third protrusion earlier and generate stable bending deformation when the cutting depth is large and the feed rate is small (i.e., the chip is relatively thin). When the feed rate is further increased, chip deformation becomes more difficult, and the chip flows through the top surface 12b of the third protrusion and contacts the second protrusion 11, causing bending deformation.

[0057] Furthermore, in this embodiment, the third protrusion 12 is located on the third rake face 13d.

[0058] Furthermore, in this embodiment, the connecting surface 15 is a concave curved surface. The concave curved surface design of the connecting surface 15 enables the cutting tool to reduce the friction between the chip and the cutting tool under conditions of large cutting depth and feed rate. Moreover, the concave curved surface structure can increase the contact area between the chip and the air, thereby cooling the chip and reducing the cutting temperature to a certain extent, while preventing excessive chip curling.

[0059] Furthermore, in this embodiment, a groove bottom plane 9 is provided between the front blade surface 13 and the side of the second protrusion.

[0060] Furthermore, in this embodiment, an inclined transition surface 14 is provided between the front blade surface 13 and the end of the second protrusion facing the arc surface 4.

[0061] The length of the side surface 11a of the second protrusion (the side of the second protrusion 11 facing the arc surface 4) along the angle bisector B2 toward the center line B1 (the extension direction of the angle bisector B2) is greater than the length of the guiding surface 11c of the second protrusion, but less than the length of the top surface 11b of the second protrusion. This design allows the second protrusion 11 to guide the chip flow in a reasonable manner, while also ensuring the strength of the cutting tool during medium and large cutting depths, and allowing the chips to curl and bend stably. When the cutting depth and feed rate are further increased, the chips flow through the top surface 12b of the third protrusion (the top surface of the third protrusion 12) and the bottom plane 9 of the groove, and after colliding with the second protrusion 11 and the inclined transition surface 14, they undergo stable bending deformation.

[0062] Furthermore, in this embodiment, a third protrusion 12 is provided on both sides of the angle bisector B2 for each blade tip. Of course, in other embodiments, the number and relative position of the third protrusions 12 can be set according to actual needs.

[0063] Furthermore, a center hole is provided in the middle of the turning insert, and the center line B1 is located at the center of the center hole.

[0064] While the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the invention. Any person skilled in the art can make many possible variations and modifications to the technical solutions of the present invention, or modify them into equivalent embodiments, without departing from the scope of the present invention. Therefore, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention, without departing from the scope of the present invention, should fall within the protection scope of the present invention.

Claims

1. An indexable turning insert, comprising a centerline (B1), an upper surface (1), a lower surface (2), and multiple side surfaces (3) connecting the upper surface (1) and the lower surface (2), wherein adjacent side surfaces (3) are connected by an arc surface (4), the included angle between adjacent side surfaces (3) is the tool tip angle, the upper surface (1), the arc surface (4) and the adjacent side surfaces (3) intersect to form an arc cutting edge (5), the upper surface (1) and the side surfaces (3) intersect to form a main cutting edge (6), a transition cutting edge (7) and an auxiliary cutting edge (8) connected sequentially in a direction away from the arc surface (4), the arc cutting edge (5) being connected to the main cutting edge (6), characterized in that: Take a plane perpendicular to the center line (B1) and located below the auxiliary cutting edge (8) as a reference plane. The height of the circular cutting edge (5) and the main cutting edge (6) relative to the reference plane is the same. The height of the transition cutting edge (7) relative to the reference plane gradually decreases in the direction away from the circular surface (4). The height of the auxiliary cutting edge (8) is the same as the lowest point of the transition cutting edge (7). The upper surface (1) is provided with a first protrusion (10), a second protrusion (11), a connecting surface (15), and a mounting positioning surface (1a) in sequence along the angle bisector (B2) from the arc cutting edge (5) to the center line (B1). The heights of the top surface of the first protrusion (10b), the top surface of the second protrusion (11b), and the mounting positioning surface (1a) relative to the reference surface increase in sequence. The second protrusion (11) and the mounting positioning surface (1a) are smoothly connected through the connecting surface (15). The upper surface (1) is provided with a third protrusion (12) symmetrically distributed about the angle bisector (B2), and the third protrusion (12) is connected to the second protrusion (11).

2. The indexable turning insert according to claim 1, characterized in that: The length of the main cutting edge (6) is L1, 0.2mm≤L1≤0.8mm; the transition cutting edge (7) is an arc with radius R, 10mm≤R≤60mm; the auxiliary cutting edge (8) is tangent to the transition cutting edge (7), and the height difference between the auxiliary cutting edge (8) and the main cutting edge (6) relative to the reference surface is H1, 0.1mm≤H1≤0.3mm.

3. The indexable turning insert according to claim 1, characterized in that: The third protrusion (12) extends in the direction from the second protrusion (11) to the transition cutting edge (7), and the angle formed by the center line (B3) of the top surface (12b) of the third protrusion and the projection of the opposite main cutting edge (6) onto the mounting positioning surface (1a) is α, 0≤α≤15°.

4. The indexable turning insert according to claim 3, characterized in that: The angle bisector (B2) intersects the circular arc cutting edge (5) at point P1, the centerline (B3) intersects the transition cutting edge (7) at point P2, and the distance between points P1 and P2 in the extension direction of the main cutting edge (6) is L2, 0.5mm≤L2≤2mm.

5. The indexable turning insert according to claim 3, characterized in that: The width of the third protrusion (12) gradually decreases in the direction from the second protrusion (11) to the transition cutting edge (7), and the maximum width of the third protrusion (12) is W, 0.3mm≤W≤1mm.

6. The indexable turning insert according to any one of claims 1 to 5, characterized in that: The top surface (12b) of the third protrusion is an inclined plane, and the angle between the top surface (12b) of the third protrusion and the mounting positioning surface (1a) is β, 10°≤β≤18°.

7. The indexable turning insert according to any one of claims 1 to 5, characterized in that: The width of the first protrusion (10) remains unchanged along the direction of the angle bisector (B2); the width of the second protrusion (11) gradually increases along the direction of the angle bisector (B2) from the arc surface (4) to the center line (B1).

8. The indexable turning insert according to any one of claims 1 to 5, characterized in that: The second protrusion (11) includes a second protrusion side surface (11a), a second protrusion guide surface (11c), and a second protrusion top surface (11b) connected sequentially from the arc surface (4) to the center line (B1). The second protrusion side surface (11a) and the second protrusion guide surface (11c) are both inclined planes extending along the angle bisector (B2). The angle between the second protrusion side surface (11a) and the mounting positioning surface (1a) is θ1, where 15°≤θ1≤30°. The second protrusion guide surface (11c) and the mounting positioning surface (1a) are also inclined planes. The angle between the two protrusions is θ2, 5°≤θ2≤15°; the top surface (11b) of the second protrusion is a convex curved surface that is higher in the middle and lower at the front and back relative to the reference surface; the side surface (10a) of the first protrusion extends along the angle bisector (B2) and is an inclined plane, and the angle between it and the mounting positioning surface (1a) is θ3, where θ2<θ3<θ1, 10°≤θ3≤20°; the top surface (10b) of the first protrusion is a plane parallel to the mounting positioning surface (1a), and the height of the top surface (10b) of the first protrusion relative to the reference surface is lower than that of the circular arc cutting edge (5).

9. The indexable turning insert according to claim 8, characterized in that: The length of the top surface (10b) of the first protrusion along the angle bisector (B2) is greater than the length of the side surface (10a) of the first protrusion along the angle bisector (B2); the length of the side surface (11a) of the second protrusion along the angle bisector (B2) is greater than the length of the guide surface (11c) of the second protrusion along the angle bisector (B2), and less than the length of the top surface (11b) of the second protrusion along the angle bisector (B2).

10. The indexable turning insert according to any one of claims 1 to 5, characterized in that: The upper surface (1) and the side surface (3) are connected by a rake face (13). The rake faces (13) on the upper surface (1) are symmetrically distributed about the angle bisector (B2) of the included angle of the blade tip. The rake face (13) includes a first rake face (13a), a second rake face (13b), a transition rake face (13c), and a third rake face (13d) that are connected in sequence to form a smooth curved surface. The rake angles of the first rake face (13a) are equal, the rake angle of the second rake face (13b) gradually increases along the direction away from the arc surface (4) and reaches its maximum at the connection with the transition rake face (13c), and the rake angle of the third rake face (13d) gradually decreases along the direction away from the arc surface (4).

11. The indexable turning insert according to claim 10, characterized in that: The maximum vertical distance between the top surface (12b) of the third protrusion and the third front blade surface (13d) is H2, 0.02mm≤H2≤0.1mm.

12. The indexable turning insert according to claim 10, characterized in that: The third protrusion (12) is located on the third rake face (13d).

13. The indexable turning insert according to any one of claims 1 to 5, characterized in that: The connecting surface (15) is a concave curved surface.

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