Turning Inserts

Abstract

The present invention relates to a double-sided negative turning insert for metal cutting, comprising a body including an upper surface (1) with a major upper support surface (14), a lower surface (2) with a major lower support surface (15), a peripheral side surface (3) connecting the upper surface (1) and the lower surface (2), and a central plane located between the upper surface (1) and the lower surface (2). The peripheral side surface includes a total of three corner side surfaces (4), each of which is located at a respective corner of an imaginary triangle (10) having three sides when viewed from above. The peripheral side surface includes a total of three major side surfaces (5), each of which extends from a respective associated first corner side surface (4) to a respective associated second corner side surface (4) along a respective associated one of the three sides of the imaginary triangle (10). At least one of the three major side surfaces (5) includes a primary support surface (13). At least one major side surface (5) further comprises a total of a pair of oppositely facing secondary support surfaces (21), each of which extends inward relative to a respective one of the primary support surfaces (13), and each of which extends perpendicular to the central plane.

Description

[Technical Field]

[0001] The present invention relates to a double-sided negative turning insert, a turning tool body for holding such a turning insert, and a turning tool comprising such a turning insert. [Background technology]

[0002] EP3153260B1 discloses a double-sided negative turning insert having a triangular basic shape. The turning insert has two opposing, generally triangular main faces and three side faces connecting the two main faces at each side of the triangle. The turning insert has a nose portion including a cutting edge at each corner of the triangle on each of the main faces. To securely fix the cutting insert in the insert seat of the turning tool body, support surfaces are provided on the main faces and side faces that cooperate with support surfaces in the insert seat of the turning tool body.

[0003] Known turning inserts perform well in many applications, but in some applications the turning insert may shift within the insert seat. Summary of the Invention

[0004] The object of the present invention is to further improve the known turning insert by providing features that allow for a more accurate and secure seating of the turning insert in the insert seat. It is also an object of the present invention to provide a turning tool comprising such a turning insert. This object is achieved according to the present invention by a turning tool as defined in claim 1.

[0005] The inventive double-sided negative turning insert for metal cutting is - an upper surface comprising a main upper support surface; a lower surface comprising a primary lower support surface; - a peripheral side surface connecting the upper surface and the lower surface; - cutting edges formed at the intersections between the upper surface and the side surface and between the lower surface and the side surface; - The midplane between the top and bottom surfaces Equipped with - the peripheral side surface comprises a total of three corner side surfaces, each of which is disposed at a corner of an imaginary triangle having three sides when viewed from above; - the peripheral side comprises a total of three major side surfaces, each of the three major side surfaces extending from a respective associated first corner side to a respective associated second corner side along a respective associated one of the three sides of the imaginary triangle; - at least one of the three major sides comprises a primary support surface; - at least one major side further comprises a total of a pair of oppositely facing secondary support surfaces, each of the secondary support surfaces extending inwardly relative to a respective one of the primary support surfaces, and each of the secondary support surfaces extending perpendicular to the mid-plane.

[0006] According to a second aspect of the present invention there is provided a turning tool body as set forth in claim 14, and according to a third aspect of the present invention there is provided a turning tool as set forth in claim 15.

[0007] Thus, the inventive turning insert includes a pair of secondary support surfaces in addition to the primary support surfaces on the upper and lower surfaces and in at least one of the three major side surfaces. The secondary support surfaces extend inward relative to each of the primary support surfaces, so that their extensions differ from the extensions of the respective primary support surfaces. Thus, when the turning insert is mounted in an insert seat provided with complementary secondary support surfaces, the secondary support surfaces function to support the turning insert in additional directions. The presence of a total pair of secondary support surfaces can reduce or even prevent problems associated with over-settling. This improves the accurate and secure fit of the inventive turning insert compared to prior art turning inserts, making the turning insert less susceptible to slippage within the insert seat.

[0008] The present invention relates to a double-sided negative turning insert. The turning insert is suitable for cutting a metal workpiece, preferably by chip-removing machining. Specifically, the turning insert is suitable for machining a metal workpiece by a turning operation. The turning insert is configured to be removably mounted within a turning tool body to form a turning tool together with the turning tool body. During turning, the workpiece is typically rotated, and the cutting insert is moved perpendicular to the axis of rotation toward the workpiece to remove chips from the rotating workpiece surface. The surface may be an outer or inner surface of the workpiece, for example, the surface of an axially extending hole. In some operations, the turning tool is operated to additionally move along other axes, such as along the axis of rotation of the workpiece.

[0009] The turning insert preferably comprises a wear resistant material such as cemented carbide, cermet, cubic boron nitride (CBN) or polycrystalline diamond (PCD) and may have a suitable coating.

[0010] The turning insert includes a body having an upper surface, a lower surface, and a peripheral side surface connecting the upper and lower surfaces. The turning insert includes a midplane between the upper and lower surfaces. The midplane typically extends midway between the upper and lower surfaces.

[0011] Preferably, the upper and lower surfaces have a triangular basic shape, e.g., with rounded or pointed corners and sides extending inward or outward relative to the center between the corners, or straight or substantially straight. Optionally, the sides are straight and linear, convexly or concavely curved, or have alternating portions of the above. The side surfaces optionally have corresponding shapes in some cross sections when viewed in cross sections parallel to the midplane.

[0012] The top view is a view of the turning insert viewed in a direction normal to the mid-plane, and the bottom view is a view of the turning insert viewed in a direction normal to the mid-plane.

[0013] Cutting edges are formed at the intersections between the top and side surfaces and between the bottom and side surfaces. Optionally, the cutting edges are located at corners and / or along edges. Preferably, the corner cutting edges extend around the corner and are preferably symmetrical about the bisector. The bisector typically passes through the point on the corner cutting edge that is most distal from the center point of the turning insert. This allows the turning insert to be fed in both directions beyond the bisector. The corner cutting edges are optionally convexly rounded or include one or more straight or curved portions that meet at a tip with a radius.

[0014] Cutting edges are formed on both the upper and lower surfaces so that the turning insert is double-sided. The term "double-sided insert" is understood to describe an insert that can be turned so that the upper surface takes the place of the lower surface, or vice versa, and either the cutting edge on the upper surface or the cutting edge on the lower surface is presented. Thus, the turning insert has at least two indexing positions. According to one embodiment, cutting edges are provided on all three corners of the upper surface and all three corners of the lower surface so that the turning insert is indexable six times.

[0015] The turning insert is negative. The term "negative insert" shall be understood to describe an insert whose flank extends perpendicular to the mid-plane. Preferably, at least the portion of the flank closest to the cutting edge forms the flank of the turning insert. According to several embodiments, a major portion of the entire flank extends perpendicular to the mid-plane.

[0016] Preferably, both the upper and lower surfaces include a portion closest to the cutting edge that forms a rake surface. Optionally, the upper or lower surface includes a chip breaker, for example in the form of a protrusion or recess.

[0017] The upper surface includes a primary upper support surface, and the lower surface includes a primary lower support surface, which are configured to cooperate with corresponding surfaces in the insert seat to provide at least a majority of the support normal to the mid-plane. Preferably, the primary upper and lower support surfaces are parallel to the mid-plane. Depending on the index position of the cutting insert, one of the primary upper and lower support surfaces cooperates with a seat primary support surface in the insert seat, and the other of the primary upper and lower support surfaces cooperates with a clamping mechanism.

[0018] The primary support surfaces may each comprise a separate partial surface or each form a continuous surface. According to several embodiments, the primary support surfaces or partial surfaces of the primary support surfaces are planar, extend parallel to the mid-plane or at an angle to the mid-plane, or form a convex or concave surface. Preferably, both primary support surfaces are planar and parallel to the mid-plane, respectively, and form a continuous surface covering a major portion of the upper and lower surfaces. Preferably, the primary support surfaces are different from the rake surfaces so as to be less susceptible to wear from cut chips. A large area of ​​the support surface is beneficial in terms of the amount of area available to cooperate with a corresponding support surface in the insert seat or clamping mechanism. Planar surfaces are simpler to manufacture within the desired tolerances.

[0019] Optionally, the clamping mechanism is a clamping screw, a clamp, a resilient member on the turning tool body, or any other suitable mechanism. In embodiments, the turning insert has a central through-hole for the clamping screw.

[0020] The peripheral side comprises a total of three angular side faces. In other words, the peripheral side faces comprise no more or no less than three angular side faces. When viewed in a top view or a cross section parallel to the midplane, the angular side faces optionally form a convexly rounded surface or include one or more flat or curved surfaces that meet within an area having a radius. According to one embodiment, when viewed in a cross section parallel to the midplane, the angular side faces have the same shape as the cutting edge of the corner.

[0021] When viewed from above or in a cross-sectional view parallel to the midplane, each of the three corner side faces is located at a respective corner of an imaginary triangle having three sides. The corners of the imaginary triangle should be located at corresponding locations on the side corner faces. According to one embodiment in which all three corners on both the upper and lower faces have corner cutting edges and the cutting edges of each corner are symmetrical about a bisector, the corners of the imaginary triangle are located at corresponding positions on the respective bisectors. Preferably, the imaginary triangle is an equilateral triangle. This makes it possible to provide a turning insert with symmetry, for example, 120° symmetry, both when the lower face faces a first direction and when the upper face faces the same first direction.

[0022] The peripheral side comprises a total of three major side faces. In other words, the peripheral side comprises no more and no less than three major side faces. Each of the major side faces extends from a respective associated first corner side to a respective associated second corner side along a respective associated one of the three sides of the imaginary triangle. The major side faces extend along an associated side of the imaginary triangle, optionally by being aligned with the imaginary triangle or by deviating inward and / or outward from the imaginary triangle while having a primary extension in the direction of the associated side.

[0023] At least one major side further includes a total of a pair of oppositely facing secondary support surfaces, such that one of the secondary support surfaces is available regardless of whether the upper cutting edge or the lower cutting edge is in an active state.

[0024] At least one of the three major sides comprises a primary support surface.

[0025] Each of the secondary bearing surfaces extends inward relative to each of the primary bearing surfaces. In contrast, bearing surfaces of prior art turning tools, which are configured on protrusions such as exemplary teeth, lack strength and may break. Inwardly extending surfaces are also beneficial for manufacturing methods involving press forming.

[0026] A direction perpendicular to the associated side of the imaginary triangle in the mid-plane defines a depth direction. Preferably, the minor support surface extends inward from at least one major side surface a depth distance of 1-10%, preferably 5%, of the diameter of the inscribed circle. The inscribed circle is the largest circle that can be contained within the side surface when viewed in top view. A longer depth extension is beneficial in achieving a larger area.

[0027] Each of the secondary bearing surfaces extends perpendicular to the midplane, such that both secondary bearing surfaces extend in the same vertical direction in the two index positions of the turning insert, in which either the upper cutting edge or the lower cutting edge is active.

[0028] Preferably, each of the pair of minor support surfaces is planar. Planar surfaces are preferred for manufacturing methods such as those involving press forming.

[0029] The minor bearing surfaces face in opposite directions. For example, each of a pair of minor bearing surfaces faces towards or away from each other. Preferably, when viewed normal to the mid-plane, each of the minor bearing surfaces forms an angle of 45 to 90°, preferably 90°, with the associated side of an imaginary triangle. Optionally, the minor bearing surfaces of the pair face in opposite directions, for example, along the associated side of the imaginary triangle. Minor bearing surfaces facing at 90° towards each other are beneficial for manufacturing methods involving press forming.

[0030] According to one embodiment, the pair of minor support surfaces form respective end walls of the recesses, the end walls being located in a common single recess or in respective recesses. Preferably, each end wall is located adjacent to a corner side, and the recesses extend toward a midpoint midway between the corner sides. The minor support surfaces located adjacent to the corner sides are advantageous in resisting transverse cutting forces that tend to displace the turning insert within the insert seat. The single recesses may extend from near the respective associated first corner side to near the respective associated second corner side.

[0031] Preferably, the depth of each recess decreases from each end wall in a direction along the associated side of the imaginary triangle up to the midpoint between the first associated corner side and the second associated corner side, such that only enough material is removed from the turning insert to provide a pair of minor support surfaces so that the turning insert is not unnecessarily weakened by one or more recesses.

[0032] Preferably, the minor support surface is spaced apart from the intersection of the at least one major side surface with both the upper surface and the lower surface, so that the minor support surface does not interfere with the cutting edges on either the upper or lower surface.

[0033] A normal to the mid-plane defines a height direction, and the upper major support surface has a distance in the height direction relative to the lower major support surface. According to one embodiment, each secondary support surface has a maximum height in the height direction, the maximum height of the secondary support surface being at least 30%, at least 40% or at least 60% of the above-mentioned distance. A long extension in the height direction is advantageous for achieving a large area of ​​the secondary support surface. A smaller height is advantageous for maintaining the strength of the turning insert.

[0034] Other than being oriented in different directions, the pairs of minor support surfaces are preferably identical.

[0035] The major bearing surface of at least one of the major side surfaces may be a separate surface or may form a single continuous surface. Preferably, the major bearing surface is planar. Preferably, the major bearing surface is perpendicular to the mid-plane. According to some embodiments, a relief surface is provided within the major bearing surface.

[0036] According to one embodiment, the primary support surface comprises two planar partial surfaces, each partial surface associated with a respective secondary support surface, which, when viewed normal to the mid-plane, form an angle of 90 to 175° between each other. This allows the two primary support surfaces to also provide support along the associated sides of an imaginary triangle. In another embodiment, the associated sides of the imaginary triangle lie in the plane of the primary support surface.

[0037] Preferably, each of the partial faces extends along an associated side of the imaginary triangle a major length that is at least the distance from each of the first and second associated corner sides to a midpoint between the first and second associated corner sides, the midpoint being located halfway between the first and second associated corner sides. A large length along the major side is advantageous in achieving a large area.

[0038] According to one embodiment, each partial surface comprises a surface defined by an upper surface, a lower surface, an associated minor bearing surface, and one of a first associated corner side surface and a second associated corner side surface that is closest to the partial surface. Thus, the primary bearing surface covers the area between the lateral corner surface and the closest of the pair of minor bearing surfaces. This allows the turning insert to have a primary support closest to the corner, where cutting forces are most effectively resisted.

[0039] Preferably, the turning insert is symmetrical, for example 180° symmetrical when rotated about an axis extending in the midplane so that the cutting edges on the lower surface are identical to the cutting edges on the upper surface at their respective index positions.

[0040] According to one embodiment with 180° symmetry as described above, the corner cutting edges are provided only on the upper and lower surfaces of one of the three corners, and the major side surface opposite that corner constitutes at least one major side surface with a primary support surface and a secondary support surface.

[0041] According to another preferred embodiment, the turning insert has two-fold 120° symmetry. In addition to the 180° symmetry, the turning insert is symmetric when rotated 120° about a central axis normal to the midplane. In that case, the turning insert is indexable three times with respect to the cutting edges on the upper surface and three times with respect to the cutting edges on the lower surface. Preferably, the cutting edges include corner cutting edges that are each symmetric about a bisector. Furthermore, each of the three major side surfaces includes at least one major side surface feature that is configured with corresponding symmetry so that the turning insert presents the same support surface in each of the six index positions.

[0042] Preferably, the imaginary triangle is an equilateral triangle. According to one embodiment having only 180° symmetry about an axis in the mid-plane that forms a bisector through the cutting edge at one of the corners, the imaginary triangle is instead an isosceles triangle.

[0043] According to a second aspect of the present invention, there is provided a turning tool body for holding a turning insert according to the present invention. The turning tool body includes an insert seat having a bottom surface including a seat primary support surface and side surfaces. The side surfaces include a primary support surface and a pair of oppositely facing secondary support surfaces. Each of the secondary support surfaces extends outward relative to the respective primary support surface and perpendicular to a plane defined by the midplane of the turning insert when the turning insert is installed in the insert seat.

[0044] Optionally, the turning tool body includes a shim disposed within the insert seat, the seat primary support surface being disposed on the shim.

[0045] According to various embodiments, the turning insert includes a set of major support surfaces for each index position, while the insert seat includes a single set of support surfaces for simultaneous cooperation with the set of support surfaces of the turning insert. Preferably, each set of support surfaces of the turning insert includes one of the major upper and lower surfaces for cooperation with the seat major support surfaces, a portion of the other of the major upper and lower surfaces for cooperation with a clamping mechanism, and major and minor support surfaces of at least one major side surface for cooperation with the major and minor support surfaces of the insert seat.

[0046] According to a third aspect of the present invention, the turning insert and the turning body together with a clamping mechanism form a turning tool, the turning insert being mounted and secured within the insert seat of the turning body by the clamping mechanism, the seat primary support surface of the insert seat facing the lower primary support surface of the turning insert, the primary support surfaces of the insert seat facing each of at least one of the three primary support surfaces of the turning insert, and the pair of pair of secondary support surfaces of the turning tool body facing each of the pair of secondary support surfaces of at least one major side surface of the turning insert. In the clamping position, the clamping mechanism is configured to removably secure the turning insert in the insert seat by pressing the major lower support surface and main support surface of the turning insert against the major support surface and main support surface of the insert seat, and in the standby position by aligning the pair of secondary support surfaces of the turning insert with each of the pairs of secondary support surfaces on the side surfaces of the insert seat, and by allowing the pair of secondary support surfaces to assume an active position in response to a force acting parallel to the associated side of an imaginary triangle, with at least two mutually facing surfaces of the pair of secondary support surfaces pressing against each other.

[0047] The cooperating primary and secondary support surfaces are pressed firmly against each other, while the secondary support surfaces provide secondary support when necessary. Initially, the turning insert is guided to a desired position and fixed in said position by the cooperation of the primary and secondary support surfaces, and the pair of secondary support surfaces is in a standby state. In the standby state, the secondary support surfaces are optionally separated from each other by a small gap or are in contact with each other without being pressed against each other. For example, the gap is at most 0.1 mm.

[0048] During operation, when a cutting force acts on the turning insert in a direction parallel to the associated side of the imaginary triangle, the cutting force may tend to displace the turning insert within the insert seat. This may cause the turning insert to be forced into the insert seat and assume an operating position by the cooperating secondary support surfaces of the turning insert and insert seat pair engaging and pressing against each other. This allows the turning insert to withstand stronger cutting forces and / or cutting forces from more directions than prior art turning inserts, with the secondary support surfaces providing secondary support where needed.

[0049] According to one embodiment, each of the secondary support surfaces of the insert seat is arranged on a common single sliding block or on a respective sliding block, each of which is fixed in an associated slot in the side of the insert seat. This simplifies manufacturing and makes it easier to achieve predetermined tolerances. Another advantage is that the sliding blocks can be replaced if the support surfaces wear out.

[0050] In the following, exemplary embodiments will be described in more detail with reference to the accompanying drawings. [Brief explanation of the drawings]

[0051] [Figure 1] 1 is a perspective view of a first embodiment of a double-sided negative turning insert according to the present invention; FIG. [Figure 2] FIG. 1 is a top view of a first embodiment of a turning insert. [Figure 3]FIG. 1 is a side view of a first embodiment of a turning insert showing one of the three major sides. [Figure 4] FIG. 1 is a cross-sectional view of the first embodiment taken along the mid-plane; [Figure 5] 1 is an exploded view of a first embodiment of a turning tool according to the present invention; FIG. [Figure 6] 6 is a perspective view of a first embodiment of the turning tool shown in FIG. 5, with a first embodiment turning insert mounted within a first embodiment of a turning tool body according to the present invention. [Figure 7] FIG. 7 is a side view of the first embodiment of the turning tool shown in FIG. 6. [Figure 8-8a] 8a is a cross-sectional view in the mid-plane of the first embodiment of the turning tool shown in FIG. 6 (FIG. 8), and FIG. 8b is an enlarged view of a portion thereof. [Figure 9-9a] 9A and 9B are cross-sectional views (FIG. 9) perpendicular to the mid-plane and the cross-section shown in FIG. 8 of the first embodiment of the turning tool shown in FIG. 6, with FIG. 9A being an enlarged view of a portion thereof; [Figure 10] FIG. 10 is a perspective view of a second embodiment of a double-sided negative turning insert according to the present invention. [Figure 11] FIG. 10 is a side view of a second embodiment of a turning insert showing one of the three major sides. [Figure 12] FIG. 10 is a mid-plane cross-sectional view of the second embodiment. [Figure 13] FIG. 2 is an exploded view of a second embodiment of a turning tool according to the present invention. [Figure 14] 14 is a perspective view of a second embodiment of the turning tool shown in FIG. 13, with a second embodiment turning insert mounted within a second embodiment of a turning tool body according to the present invention. [Figure 15] FIG. 15 is a side view of the second embodiment of the turning tool shown in FIG. 14. [Figure 16] 15 is a cross-sectional view of the second embodiment of the turning tool shown in FIG. 14 taken along the mid-plane. DETAILED DESCRIPTION OF THE INVENTION

[0052] All figures are schematic and not necessarily to scale, and generally show only those parts necessary to clarify the respective embodiment, while other parts may be omitted or merely suggested. Unless otherwise indicated, like reference numerals refer to like parts in different figures.

[0053] 1 to 4, a first embodiment of a double-sided negative turning insert for metal cutting according to the present invention is described. The turning insert comprises a coated body of cemented carbide.

[0054] The body includes an upper surface 1, a lower surface 2, and a peripheral side surface 3 connecting the upper surface 1 and the lower surface 2. The peripheral side surface 3 includes a total of three corner side surfaces 4 and a total of three major side surfaces 5. A central plane, indicated in FIG. 3 and shown in FIG. 4, extends midway between the upper surface 1 and the lower surface 2. The body of the turning insert has a central through-hole 16. A central axis 12, which is both the central axis of the hole 16 and the central axis of the body, extends normal to the central plane.

[0055] The cutting edges are formed at the intersections between the upper surface 1 and the side surface 3, and between the lower surface 2 and the side surface 3. The cutting edges comprise a total of six corner cutting edges 6, one at each corner of the upper surface 1 and the lower surface 2.

[0056] The body of the exemplary embodiment has two-fold 120° symmetry, such that the top and bottom surfaces 1 and 2 are identical to one another, and the three major side surfaces 3 are also identical to one another. Furthermore, all six corner cutting edges 6 are identical to one another, providing six index positions for the turning insert. In other words, the body has 180° symmetry about an axis in the midplane and 120° symmetry about the central axis 12. The turning insert is therefore double-sided.

[0057] The first corner cutting edge 6 is symmetrical about a bisector 9, see FIG. 2. The corner cutting edge 6 comprises a convex nose cutting edge 7 and two straight major cutting edges 8 extending from the nose cutting edge 7 on each side of the corner cutting edge 6. When viewed from the top view of FIG. 2, the major cutting edges 8 form a nose angle α of 71 to 85°. The bisector 9 extends midway between the two major cutting edges 8 and pierces the distal-most point 11 of the corner cutting edge 6.

[0058] Both the upper surface 1 and the lower surface 2 include a portion closest to the cutting edge that forms a rake face. The rake face is provided with a chip breaker in the form of a groove 17. The upper surface 1 includes a primary upper support surface 14, and the lower surface 2 includes a primary lower support surface 15, see FIG. 3. Both primary support surfaces 14, 15 form continuous surfaces that extend from the edge of the central bore 16 to the groove 17.

[0059] When viewed from the top view of FIG. 2 , each corner side 4 is located at a respective corner of an imaginary triangle 10 having three sides. The imaginary triangle 10 is an equilateral triangle, and each corner is located at the distal-most point 11 of the cutting edge 6 at each respective corner. Each distal-most point 11, which is also a corner of the imaginary triangle, is equidistant from the central axis 12. Each major side 5 has an extension along an associated one of the three sides of the imaginary triangle 10. Each major side 5 extends outward from the associated side of the imaginary triangle 10 that is closest to the corner side, and inward from the associated side at the center between the corner sides 4.

[0060] In the following, only one of the major sides 5 will be described. Due to symmetry, the other major side 5 has the same characteristics.

[0061] The major side surface 5 extends from the first corner side surface 4 to the second corner side surface 4, while the third corner side surface 4 is opposite the aforementioned major side surface 5. The major side surface 5 has a portion closest to the cutting edge that forms a flank surface 18. The flank surface 18 and a major portion of the major side surface 5 extend perpendicular to the mid-plane. The corner side surface 4 also extends perpendicular to the mid-plane. The turning insert can be defined as negative.

[0062] The main side surface 5 comprises a main support surface 13 in the form of two separate partial surfaces, both of which are planar and form an angle β of 165°, as can be seen in Figure 4. Between the two partial surfaces, the main side surface 5 comprises a relief notch 19.

[0063] The major side 5 has two recesses 20, each extending from an end wall adjacent to a corner side 4 along the associated side of the imaginary triangle 10 to a midpoint midway between the corner sides 4, specifically a point adjacent to the relief notch 19.

[0064] The major side surface 5 comprises a total of one pair of minor support surfaces 21. In the exemplary embodiment, each of the two minor support surfaces 21 of the pair is formed by an end wall of a respective recess 20. The minor support surfaces 21 are both planar and face in opposite directions toward each other. When viewed normal to the mid-plane, each of the minor support surfaces 21 forms a 90° angle γ with the associated side of the imaginary triangle 10. In this case, the normal to the plane of each minor support surface is parallel to the associated side of the imaginary triangle 10.

[0065] The direction in the mid-plane perpendicular to the associated side of the imaginary triangle 10 defines the depth direction. The minor support surface 21 extends inward from at least one major side surface 5 a depth distance 22 of 1-10%, preferably 5%, of the diameter of the inscribed circle IC, see Figure 4. The inscribed circle IC is the largest circle that can be contained within the side surface 3 when viewed in top view in Figure 4.

[0066] Referring to FIG. 4 , a normal to the midplane defines a height direction. In the exemplary embodiment, the minor support surfaces 21 have a uniform height along their depth direction extension. In the exemplary embodiment, the height 23 of each minor support surface 21 is 37% of the height distance 24 from the major upper support surface 14 to the lower major support surface 15. The minor support surfaces 21 do not extend to the intersections of the major side surfaces 5 with the upper surface 1 and the lower surface 2. Similarly, the recess 20 has an opening in the major side surface 5. The opening is defined by upper and lower edges that are spaced apart from the intersections of the major side surfaces 5 with the upper surface 1 and the lower surface 2. Thus, the minor support surfaces 21 are spaced apart from the cutting edge.

[0067] In the depth direction, the recesses 20 are limited by a bottom in the form of a base surface 25. The depth of each recess 20 decreases from each end wall in a direction along the associated side of the imaginary triangle 10 toward a midpoint halfway between the first and second associated corner side surfaces 4, in this case a short distance from the relief notch 19. In the exemplary embodiment, when viewed in a cross section parallel to the midplane (see FIG. 4 ), the base surfaces are parallel to the sides of the imaginary triangle 10. The decreasing depth of the recesses 20 is achieved by the inclined partial surfaces that form the primary support surface 13, with the base surface 25 abutting the primary support surface 13 at an intersection close to the relief notch 19.

[0068] Each recess 20 is surrounded by each of the partial surfaces that make up the primary support surface 13. The opening is limited by the upper and lower edges, i.e., the line formed by the intersection of the partial surface of the secondary support surface 21 with the lateral corner surface 4 at the end closest to the lateral corner surface 4, and the line formed by the intersection of the base surface 25 with the partial surface at the end closest to the relief notch 19. Each partial surface has an extension in the direction of the associated side of the imaginary triangle 10 that is at least the major length of the distance from the corner surface 4 to the midpoint halfway between the first associated corner surface 4 and the second associated corner surface 4. Each partial surface also comprises a surface limited by the upper surface 1, the lower surface 2, the associated secondary support surface 21, and the corner surface 4.

[0069] 5 to 9, a first embodiment of a turning tool equipped with a turning insert according to the first embodiment is shown. Specifically, the first embodiment of a turning tool body 26 is included in the turning tool described above.

[0070] 5, the turning tool body 26 includes an insert seat 27, which includes a shim 28. The bottom surface, including the seat's main support surface 29, is located above the shim 29. The shim 28 includes a central through-hole 30 and is attached to the turning tool body 26 by a screw 31 that extends through the hole 30.

[0071] The insert seat 27 further comprises a side surface 32. The side surface 32 comprises two protruding wedge elements 35, each extending along an associated side of the imaginary triangle 10 of the turning insert mounted in the insert seat 27. In this case, each wedge element 35 has an end face that protrudes most from the side surface 32 at the end closest to the corner side surface 4 of the mounted turning insert. Between the two wedge elements 35, at the midpoint, the side surface 32 comprises a relief ridge 36. Each wedge element 35 comprises an inclined surface 37 extending from the end face, terminating at the end closest to the midpoint halfway between the corner side surfaces 4 of the mounted turning insert, and meeting at the intersection of the side surface 32 and the relief ridge 36.

[0072] The side surfaces 32 include primary support surfaces 33 in the form of two separate partial surfaces. Each wedge element 35 is surrounded on three sides by each of two partial surfaces and on a fourth side by a relief ridge. Both partial surfaces are planar and form an angle ε of 165° therebetween, as can be seen in FIG. 8. In the exemplary embodiment, the angle ε is equal to the angle β formed by the partial surfaces of the turning insert.

[0073] The side surface 32 comprises a total of one pair of secondary support surfaces 34. In the exemplary embodiment, the two secondary support surfaces 34 are located on respective end faces of the wedge element 35 and extend outward relative to the respective part surface. Both secondary support surfaces 34 are planar, facing in opposite directions and away from each other. When viewed in a direction normal to the midplane of the turning insert mounted in the insert seat 27, each of the secondary support surfaces 34 forms a 90° angle with the associated side of the imaginary triangle 10. In an exemplary embodiment, TIFF2026503227000003.tif6170 is equal to the angle γ of the minor bearing surface 21 of the turning insert. In this case, the normal to the plane of each minor bearing surface 34 is parallel to the associated side of the imaginary triangle 10.

[0074] FIG. 5 also shows the clamping mechanism, which comprises a spring element 38, a clamp 39 and a set screw 40.

[0075] A first embodiment of a turning tool comprising a turning tool body 26 according to the first embodiment, a turning insert according to the first embodiment, and a clamping mechanism is shown in Figures 6 to 9, where the turning insert is removably secured in an insert seat 27 of the turning tool body 26 by the clamping mechanism.

[0076] 9 , the seat primary support surface 29 of the insert seat 27 faces the turning insert's lower primary support surface 15. The partial surfaces constituting the insert seat 27's primary support surface 33 face each of the partial surfaces constituting the turning insert's primary support surface 13 of at least one of the turning insert's three major side surfaces 5. The pair of secondary support surfaces 34 of the turning tool body pair faces each of the pair of secondary support surfaces 21 of the at least one of the turning insert's major side surfaces 5. To secure the turning insert, the clamping mechanism's set screw 40 is tightened, causing the clamp 39 to engage the primary upper support surface 14 and press the turning insert against the shim 28 and side surface 32. This causes the turning insert's lower primary support surface 15 to be firmly pressed against the insert seat's seat primary support surface 29, and the partial surfaces constituting the turning insert's primary support surface 13 to be firmly pressed against the partial surfaces constituting the insert seat's primary support surface 33. The pairs of secondary bearing surfaces 21 of the turning insert are aligned with respective pairs of secondary bearing surfaces 34 of the side surfaces 32 of the insert seat 27. Thus, one secondary bearing surface of each pair cooperates.

[0077] The secondary support surface 34 of the insert seat 27 extends outward from the side surface 32 a distance in a direction corresponding to the depth of the turning insert mounted in the insert seat 27, the distance being less than the depth of one of the cooperating secondary support surfaces 21 of the turning insert. The secondary support surface 34 of the insert seat 27 extends a height distance that is less than the maximum height of the secondary support surface 21 of the turning insert. This creates play 43 around the wedge element 35 in the respective recess 20, see FIG. 9a. The relief ridge 36 is received in the relief notch 19.

[0078] In the clamped position, initially the secondary support surfaces 21, 34 are in a standby position and there is a small gap 46 of 0.05 mm between the two aligned cooperating secondary support surfaces 21, 34 respectively.

[0079] Opposite the major side 5 which cooperates with the side 32 of the insert seat 27 in the illustrated indexed position of the turning insert, a corner cutting edge 6 projects from the upper surface 1. The corner cutting edge 6 may be used to cut a rotating metal workpiece, and the corner cutting edge 6 may be fed in both directions across the bisector 9.

[0080] During operation, if a cutting force, for example, a force acting across the bisector in the direction of an imaginary side of the triangle 10, acts to displace the turning insert in the insert seat 27, two of the aligned cooperating minor bearing surfaces 21, 34 assume their operating positions, contacting and pressing against each other. This provides additional support to prevent any movement of the turning insert. Because the distance between the minor bearing surfaces 21, 34 is very small, the turning insert remains substantially in a clamped position. Of the surfaces of the wedge element 35, only the minor bearing surface 34 contacts the surface of the turning insert, i.e., the minor bearing surface 21 of the turning insert.

[0081] A second embodiment of a turning tool including a turning tool body 26 according to the second embodiment, a turning insert according to the second embodiment, and a clamping mechanism are shown in Figures 10-16, with the turning insert removably secured in an insert seat 27 of the turning tool body 27 by the clamping mechanism. These devices have many features in common with the corresponding devices of the first embodiment, and therefore only the features that primarily represent differences will be described. Figures 10-16 show a second embodiment of a double-sided negative turning insert for metalcutting according to the present invention.

[0082] Since the turning insert according to the second embodiment is also a double-sided negative turning insert for metal cutting and has the same symmetry as the turning insert of the first embodiment, the following will describe one of the major sides 5, and the other major sides 5 have the same features.

[0083] The turning insert according to the second embodiment differs from the turning insert according to the first embodiment described above mainly in that the major side surface 5 comprises a single recess 20 instead of two recesses. The single recess 20 extends from an end wall adjacent to the first corner side surface 4 along the associated side of the imaginary triangle 10 to an end wall adjacent to the second corner side surface 4. A total of one pair of minor support surfaces 21 of the turning insert are formed by the respective end walls of the single recess 20.

[0084] The depth of the recesses 20 is defined by a bottom in the form of a base surface 25. The depth of the single recess 20 decreases from each end wall to a midpoint halfway between the first associated corner side 4 and the second associated corner side 4 in a direction along the associated side of the imaginary triangle 10. In the exemplary embodiment, the base surface 25 extends outward from the primary support surface 13 to its shallowest point at the midpoint when viewed in a cross-section parallel to the midplane and along the associated side of the imaginary triangle 10. The relief notch 19 is divided in two by the single recess 20.

[0085] The turning tool body according to the second embodiment includes a slot 44 in the insert seat surface 32. A sliding block 41 is positioned in the slot 44. The sliding block 41 has a central through hole 42 and is fixed in the slot 44 by a screw 31 extending through the hole 42, see Figures 13 and 16.

[0086] The two secondary support surfaces 34 of a total pair of insert seats are arranged on the surface of the sliding block 41. The two secondary support surfaces 34 according to the second embodiment have the same size and extension as the secondary support surfaces 34 of the first embodiment described above.

[0087] The turning insert, turning tool holder and clamping mechanism are assembled to form a turning tool according to the second embodiment, whereby all the above-mentioned surfaces cooperate.

Claims

1. an upper surface (1) with a main upper support surface (14); a lower surface (2) with a main lower support surface (15); - a peripheral side surface (3) connecting said upper surface (1) and said lower surface (2); cutting edges formed at the intersections between the upper surface and the side surface and between the lower surface and the side surface; a central plane between said upper and lower surfaces; a main body comprising: - the peripheral side surface comprises a total of three corner side surfaces (4), each of which is arranged at a corner of an imaginary triangle (10) having three sides when viewed from above; - said peripheral side comprises a total of three main side surfaces (5), each of said three main side surfaces (5) extending from a respective associated first said corner side surface (4) to a respective associated second said corner side surface (4) along a respective associated one of said three sides of said imaginary triangle (10); at least one of the three said main sides (5) comprises a main support surface (13); In double-sided negative turning inserts for metal cutting, At least one of the main sides (5) further comprises a total of a pair of oppositely oriented secondary support surfaces (21), each of which extends inwardly relative to a respective one of the main support surfaces (13), and each of which extends perpendicularly to the central plane. A turning insert characterized by:

2. 2. The turning insert according to claim 1, wherein each of said pair of said secondary support surfaces (21) is a plane.

3. 3. Turning insert according to claim 1 or 2, wherein each of the secondary support surfaces (21) of the pair faces towards each other.

4. 4. Turning insert according to claim 2 or 3, wherein when viewed normal to said mid-plane, each of said minor support surfaces (21) forms an angle γ of 45 to 90°, preferably 90°, with the associated side of said imaginary triangle.

5. 5. The turning insert according to claim 1, wherein the secondary support surface (21) is spaced apart from the intersection of at least one of the major side surfaces with both the upper surface (1) and the lower surface (2).

6. a normal to the mid-plane defines a height direction; - said upper main support surface (14) has a distance (24) in said height direction relative to the lower main support surface (15); each secondary support surface (21) has a maximum height (23) in said height direction, Turning insert according to claim 5, wherein the maximum height of the secondary support surface (21) is at least 30%, at least 40% or at least 60% of the distance.

7. a direction in the mid-plane perpendicular to the associated side of the imaginary triangle defines a depth direction; Turning insert according to any one of claims 1 to 6, wherein the secondary support surface (21) extends inwardly from at least one of the main side surfaces (5) for a depth distance of 1 to 10%, preferably 5%, of the diameter of the inscribed circle.

8. 8. The turning insert according to claim 1, wherein each of the secondary support surfaces (21) forms an end wall of a respective one of the recesses (20), the end walls being arranged in a common single recess (20) or in each of the recesses (20).

9. 9. The turning insert according to claim 3, 7 or 8, wherein the depth of each recess (20) decreases from each end wall in a direction along the associated side of the imaginary triangle (10) up to a midpoint halfway between the first associated corner side (4) and the second associated corner side (4).

10. - said primary support surface (13) comprises two planar partial surfaces, each partial surface being associated with a respective one of said secondary support surfaces (21); Turning insert according to any one of claims 1 to 9, wherein the part faces form an angle of 90 to 175° between one another when viewed normal to the mid-plane.

11. 11. The turning insert according to claim 10, wherein each of the part faces extends along the associated side of the imaginary triangle (10) for at least a major length of a distance from each of the first associated corner side (4) and the second associated corner side (4) to a midpoint halfway between the first associated corner side (4) and the second associated corner side (4).

12. 12. The turning insert according to claim 10 or 11, wherein each of the part faces comprises a surface defined by the upper face (1), the lower face (2), the associated secondary support face (21), and the one of the first associated corner flank (4) and the second associated corner flank (4) that is closest to the part face.

13. - said imaginary triangle (10) is an equilateral triangle; - each of the three main sides (5) has at least one feature of the main side (5); - Turning insert according to any one of claims 1 to 12, wherein said turning insert is six times indexable.

14. 14. A turning tool body (26) for holding the turning insert according to any one of claims 1 to 13, wherein the tool body comprises an insert seat, the insert seat comprising: a bottom surface including the seat main support surface (29); - Side (32) and and the side surface (32) is - a primary support surface (29), a total of one pair of oppositely oriented secondary support surfaces (34), each of which extends outward relative to a respective one of the primary support surfaces (29), and each of which extends perpendicular to a plane defined by the mid-plane of the turning insert when the turning insert is mounted in the insert seat (27); A turning tool body (26) including:

15. A turning tool comprising the turning insert according to any one of claims 1 to 13, a turning tool body (26) according to claim 14, and a clamping mechanism, - the seat main support surface (27) faces the main lower support surface (15) of the turning insert; - said main support surface (33) of the insert seat (27) faces each of said main support surfaces (13) of at least one of said three main side surfaces (5) of said turning insert; - the secondary support surfaces (34) of a pair of tool bodies face each of the secondary support surfaces (21) of the pair of at least one of the main sides (5) of the turning insert, The clamping mechanism includes: - by pressing the main lower support surface (15) and the main support surface (13) of the turning insert against the seat main support surface (29) and the main support surface (33) of the insert seat (27), respectively; and - by aligning the pair of secondary support surfaces (21) of the turning insert with the respective secondary support surfaces (34) of the pair of insert seats (27) in a standby position; and - by enabling said pair (21, 34) of secondary support surfaces to assume an active position in response to a force acting parallel to the relevant side of said imaginary triangle (10), at least two mutually facing surfaces of said pair (21, 34) pressing against each other, A turning tool configured to removably secure the turning insert within the insert seat (27).

16. 16. A turning tool according to claim 15, wherein each of the secondary support surfaces (34) of the insert seats (27) is arranged on a common single sliding block (41) or on a respective sliding block (41) surface, each sliding block (41) being fixed in an associated slot (44) in the side surface (32) of the insert seat (27).

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