Bar peeling method, and peeling plate

Abstract

A method for bar peeling a workpiece (W), wherein, in a tool holder (6), there are disposed at least two uniform cutting plates (1, 1'), on each of which a plurality of roughing cutting sections (2) and a plurality of finishing cutting sections (3) which are different therefrom are formed, wherein, in an installed position, the preceding cutting plate (1) with respect to a machining direction, which cutting plate is provided for roughing machining, is positioned in such a way that it only engages with a roughing cutting section (2), and the following cutting plate (1'), which is provided for finishing machining, is positioned in such a way that it only engages with a finishing cutting section (3).

Description

[0001] Peeling process and peeling plate

[0002] The present invention relates to a method for peeling turning with the features of the preamble of claim 1, an arrangement for peeling turning and a cutting insert for peeling turning.

[0003] The invention further relates to a cassette for holding cutting inserts and to a use of cutting inserts for peeling turning.

[0004] Bar peeling is a machining process for removing outer material layers from rolled or forged blanks with a round cross-section. In bar peeling, the workpiece—usually a bar or thick-walled tube—is guided by rollers centered on a rotating tool, the peeling head.

[0005] A peeling head usually has several tool holders or slides, each typically with one to three cutting inserts.

[0006] The tool holders or slides can be designed with or without so-called cassettes.

[0007] A cassette contains holders for cutting inserts.

[0008] By changing cassettes on a peel-turning machine, cutting inserts can be exchanged particularly quickly.

[0009] The cutting inserts used in peeling turning are also called cutting plates or peeling plates.

[0010] In skiving, the inserts are typically arranged so that on the input side, so-called roughing inserts (also known as pre-cutters) perform the rough material removal, or roughing, while on the output side, so-called finishing inserts (also known as finishing cutters or finishing cutters) ensure high surface quality, shape accuracy, and dimensional accuracy. The input side refers to an insert or a section of a cutting edge that engages first. The finishing inserts are arranged after the roughing inserts in relation to the feed direction. Typically, separate skiving inserts are provided in a tool holder, which perform the tasks of roughing and finishing separately.

[0011] A so-called tandem arrangement has proven to be effective for this purpose, according to which a roughing and a finishing insert are arranged in a cassette.

[0012] Round inserts are often used for roughing.

[0013] For finishing, elongated polygonal inserts are often used, especially elongated octagonal inserts. These have short main cutting edges for shallow cutting depths and very long secondary cutting edges for smoothing.

[0014] In addition, cutting inserts are known that have both main cutting edges for roughing and secondary cutting edges for finishing. The main cutting edge performs the rough material removal, i.e., roughing; the secondary cutting edge performs the finishing, thus ensuring high surface quality, shape accuracy, and dimensional accuracy. For example, AT501655 A1 describes a polygonal cutting insert with a main cutting edge for roughing and a secondary cutting edge ("smoothing edge") for finishing.

[0015] EP3419779 B1 also shows a cutting insert for simultaneous roughing and finishing.

[0016] WO2021161301 A1 shows a square cutting insert for peeling turning with a straight finishing cutting edge formed centrally on one side edge, which is bordered on both sides by roughing cutting edge sections (“peeling sub-edges”).

[0017] A disadvantage of known methods for peeling and the known cutting inserts for peeling is that a large part of the cutting insert (approximately in terms of its circumference) remains unused.

[0018] The object of the present invention is to provide a method for skiving that overcomes the disadvantages. Furthermore, an assembly for skiving and a cutting insert are to be provided. This object is achieved by a method having the features of claim 1.

[0019] In the method according to the invention for skiving a workpiece, at least two identical cutting inserts are arranged in a tool holder, on each of which a plurality of roughing cutting edge sections and a plurality of different finishing cutting edge sections are formed, wherein in an installed position the cutting insert which is in front with respect to a machining direction and is intended for roughing is adjusted such that the preceding cutting insert engages only with one roughing cutting edge section and the following cutting insert which is intended for finishing is adjusted such that it engages only with one finishing cutting edge section, better material utilization of the cutting inserts is achieved. A larger proportion of a circumference of the cutting inserts is used for machining.

[0020] In particular, the method ensures that the relevant cutting edges, namely the roughing cutting edge and the finishing cutting edge, only engage in the intended installation situation. This ensures that no finishing cutting edge engages the preceding cutting insert intended for roughing. Rather, only the roughing cutting edge engages the preceding cutting insert.

[0021] Furthermore, it ensures that no roughing cutting edge engages the subsequent insert intended for finishing. Instead, only a finishing cutting edge engages the subsequent insert.

[0022] This has the additional advantage that when a cutting insert previously used as a subsequent cutting insert for finishing is used as the leading cutting insert for roughing, no worn cutting edge section is used. In particular, the roughing cutting edge sections are formed in a corner area of ​​the cutting insert.

[0023] The finishing cutting sections are, in contrast, formed in particular along a side edge of the cutting insert.

[0024] A corner area of ​​a cutting insert is understood, in particular, to be a section of the cutting insert that surrounds a corner defined by the basic geometric shape. The corner area can be understood, in particular, as a surface portion of the cutting insert in a plan view, which surface portion extends from the relevant corner toward the center of the insert and occupies between 10% and 30% of the total surface area of ​​the cutting insert.

[0025] In particular, it is intended that the leading cutting insert, which performs rough machining, be set at such a steep angle that only the roughing cutting edge formed in a corner area of ​​the cutting insert penetrates the workpiece. This steep angle allows for particularly large cutting depths to be achieved on the leading cutting insert.

[0026] The cutting inserts arranged in a tool holder in the method according to the invention are identical. The cutting insert positioned forward in an installed position with respect to a machining direction, intended for roughing, is identical to the cutting insert positioned downstream, intended for finishing. Therefore, identical inserts can be used for roughing and finishing. In the method according to the invention, identical cutting inserts are arranged differently. In particular, it is provided that two identical cutting inserts are arranged in a tool holder. In addition, one or more additional cutting inserts could also be provided.

[0027] The top and bottom surfaces of the inserts can be the same or different. If the top and bottom surfaces differ, it is specifically intended that only finishing cutting sections are formed on one side and only roughing cutting sections are formed on the other side.

[0028] In one variant, only roughing cutting edges are formed on one side, while finishing cutting edges and additional roughing cutting edges are formed on the other. This development takes into account the fact that roughing cutting edges are subject to particularly severe wear. This variant is particularly intended for inserts with a triangular basic shape.

[0029] A portion on a circumference of a cutting insert at which a cutting edge is provided for roughing is called a roughing cutting portion.

[0030] A portion on a circumference of a cutting insert at which a cutting edge is provided for finishing is called a finishing cutting portion.

[0031] In a plan view, the cutting inserts have a particularly polygonal basic shape.

[0032] The cutting inserts preferably have a rounded polygonal basic shape: this means that the corners are rounded.

[0033] In one embodiment, a cutting plate has an octagonal basic shape.

[0034] In particular, the basic shape is elongated octagonal. This means that, unlike a regular octagon, two opposite edges are longer than the other edges. In particular, the cutting insert with an elongated octagonal basic shape is intended to be symmetrical with respect to an imaginary central axis. This basic shape is also referred to as an L-shape, and the cutting insert is accordingly referred to as an L-plate.

[0035] This shape is particularly advantageous because it allows for the formation of a long finishing cutting edge along each of the long edges. A roughing cutting edge is preferably formed on the narrow side of the insert of this shape. Such an insert allows for the formation of two roughing cutting edges and two finishing cutting edges on each top surface.

[0036] Alternatively, the cutting insert preferably has a triangular-rounded basic shape. In this case, it is preferred to form a roughing cutting section along each of the rounded corners and a finishing cutting section along each of the side edges. Such a cutting insert allows for the formation of three roughing cutting sections and three finishing cutting sections on each top surface.

[0037] According to a further embodiment, the cutting plates have a rounded square basic shape.

[0038] For an embodiment of the cutting inserts with a square basic shape, it is particularly preferred to form only one or more roughing cutting sections on one cover surface of a cutting insert and only one or more finishing cutting sections on the other cover surface.

[0039] In other words, for cutting inserts with a square basic shape, it is preferred not to provide roughing cutting sections and finishing cutting sections on the same cover surface, but to form the cutting insert on two sides.

[0040] In general, with the proposed cutting inserts, the next cutting edge assigned to a side edge can be used after one cutting edge has worn, preferably by further rotating (“indexing”) the cutting insert by an angular amount predetermined by the basic shape. With a square basic shape, for example, four side edges are usable per side, and indexing to the next side edge occurs here by a 90° rotation. The cutting inserts are preferably designed as indexable inserts, i.e. they have two usable cover surfaces that act as cutting faces in sections. The two cover surfaces of a cutting insert can be of the same or different design with regard to the chip breaker structures formed thereon. If one side becomes worn, the other side can be used for machining by turning the cutting insert.

[0041] According to a first variant, the cutting plates each have two identical cover surfaces, i.e. they are double-sided in the sense that there is no difference between a top and a bottom side.

[0042] It is preferably provided that at least one roughing cutting section is formed on the cover surfaces and at least one finishing cutting section is formed therefrom and spaced apart by a cutting edge-free section.

[0043] Depending on the geometry of the cutting insert, several roughing cutting sections and finishing cutting sections can be formed.

[0044] A “cutting edge-free section” means that no chip breaker structure and / or chamfer on the cover surface side is formed along an outer edge of the cutting insert running between a roughing cutting section and a finishing cutting section.

[0045] Particularly preferably, the cover surface extends within the cutting-edge-free section to the outer edge of the cutting insert. In other words, the cutting-edge-free section is at the same level as the cover surface, allowing support right up to the edge of the cutting insert when it is turned and secured in a tool holder. The cutting-edge-free section thus increases the available support surface for a snug fit in the tool holder. It is particularly helpful that the support surface, enlarged beyond the cutting-edge-free section, extends all the way to the edge of the cutting insert.

[0046] Preferably, a cutting edge-free section is provided between all roughing cutting sections and finishing cutting sections formed on a top surface. According to a second variant, the cutting inserts are two-sided and each have two unequal top surfaces. Accordingly, it is provided that only one or more roughing cutting sections are formed on one top surface of a cutting insert, and only one or more finishing cutting sections are formed on the other top surface of the same cutting insert. In other words, the cutting inserts according to this variant have a side designed for rough machining (roughing) ("roughing side") and a side designed for fine machining (finishing) ("finishing side").

[0047] This configuration is particularly applicable for the previously discussed cutting inserts with a square basic shape.

[0048] For this purpose, it is preferably provided that when using the cutting inserts for peeling, the finishing side is used first and after using this side, the cutting insert is turned and the roughing side is used.

[0049] This sequence is particularly advantageous because the side used for rough machining experiences a lot of wear, which means that a secure support on the roughing side after use is not guaranteed.

[0050] In this embodiment of the method, it is also advantageous and preferred with regard to the cutting inserts that cutting edge-free sections are formed between roughing cutting edge sections or finishing cutting edge sections. Preferably, a cutting edge-free section is provided between all roughing cutting edge sections or finishing cutting edge sections on each side.

[0051] As described above, the spacing of the respective cutting sections results in improved support of the cutting insert in a tool holder.

[0052] On the top surfaces of the cutting inserts, chip surfaces with chip guiding structures are formed in sections.

[0053] Chip breaker structures along a roughing cutting section are usually and preferably coarser structured than chip breaker structures along a finishing cutting section.

[0054] Roughing cutting sections generally and preferably have larger chamfer widths than finishing cutting sections. Furthermore, in a plan view, a chip breaker structure associated with the roughing cutting section has a larger surface area than a chip breaker structure of the finishing cutting section. Roughing cutting sections, in particular, taper off in a curved manner, forming an ellipse or a radius, in contrast to finishing cutting sections, which preferably taper off in a straight line.

[0055] Furthermore, finishing cutting edges preferably have a support chamfer. Roughing cutting edges preferably do not have a support chamfer.

[0056] In the method according to the invention, it is provided that in an installation position the cutting insert which is in front with respect to a machining direction is set at a first setting angle and the cutting insert which is behind with respect to the machining direction is set at a second setting angle which is different from the first setting angle, such that the cutting insert which is in front is only in engagement with a roughing cutting section and the cutting insert which is behind is only in engagement with a finishing cutting section.

[0057] In particular, it is provided that any cutting edge-free sections of the preceding and following cutting inserts do not engage with the workpiece.

[0058] Preferably, the first angle of attack is greater in magnitude than the second angle of attack. In other words, the leading cutting insert, acting as a roughing insert, is set at a steeper angle than the following cutting insert, acting as a finishing insert.

[0059] Preferably, the angle of attack of the preceding cutting plate, the first angle of attack, is between 8° and 30°, more preferably between 15° and 25°.

[0060] A first angle of attack between 10° and 25° is preferred for cutting inserts with a square basic shape, so-called S-inserts.

[0061] For elongated octagonal cutting inserts, so-called L-inserts, the angle of attack of the leading cutting insert is more preferably between 5 and 15°, in particular between 7° and 12°, especially 10°. The angle of attack of the following cutting insert, the second angle of attack, is preferably between 0° and 5°. In particular, it can be provided that the angle of attack of the following cutting insert is 0°, i.e., this cutting insert is arranged parallel to the workpiece surface with respect to the main extension direction of the engaged finishing cutting edge.

[0062] In particular, in the method according to the invention, the maximum cutting depths - ap - of the preceding and subsequent cutting inserts differ.

[0063] In particular, it is intended that the cutting depth of the preceding cutting insert acting as a roughing insert is between 0.5 mm and 8 mm, in particular between 3 mm and 6 mm. This applies in particular to S-shaped inserts. For L-shaped and N-shaped cutting inserts, the cutting depth of the preceding cutting insert is in particular between 0.5 mm and 3 mm.

[0064] The cutting depth of the following cutting insert is preferably between 0.1 mm and 2 mm, more preferably between 0.3 mm and 1 mm. The cutting depth of the following cutting insert is particularly preferably at most 0.8 mm.

[0065] There are particular advantages associated with the selection of a low cutting depth for the subsequent cutting insert, which performs the finishing function: with a low chip removal by the subsequent cutting insert, the chip guide structure of the finishing cutting section, which causes material removal, can be designed to be particularly narrow and / or with a low profile.

[0066] This is advantageous in order to provide a large support surface in a reversed installation position of the cutting insert.

[0067] "Narrow" in this context means that the maximum depth extension of the chip breaker structure toward the insert center is less than 25% of the distance between the finishing cutting edge and the insert center. The cutting depths of the preceding and following inserts are additive. This means that the total cutting depth achieved by both inserts is the sum of the respective cutting depths of the preceding and following inserts.

[0068] Accordingly, the cutting insert positioned in front in the machining direction is positioned relative to a workpiece surface created by the following cutting insert in such a way that the roughing cutting section of the preceding cutting insert, which is in engagement with the workpiece, is located radially further outward relative to an imaginary center axis of the workpiece than the finishing cutting section of the following cutting insert, which is in engagement with the workpiece. The radial offset corresponds to the cutting depth of the following cutting insert.

[0069] Preferably, a finishing cutting section comprises a secondary cutting section and a main cutting section extending at an angle to the secondary cutting section in the direction of an insert center. The secondary cutting section is positioned substantially parallel to a center axis of the workpiece, and the main cutting section is positioned such that it covers at least 80% of the cutting depth to be removed by the finishing cutting section. This means that the main cutting section performs the primary material removal of the subsequent cutting insert. The secondary cutting section essentially performs a smoothing function.

[0070] For this purpose, it may preferably be provided to form a chip guide structure of the secondary cutting section narrower than that of the main cutting section, because only a small amount of chip removal takes place at the secondary cutting section.

[0071] Furthermore, protection is sought for an arrangement for peeling, comprising a tool holder and at least two cutting inserts.

[0072] The corresponding claim is directed to a system comprising a tool holder, in particular a cartridge, for skiving, comprising at least two insert seats and identical cutting inserts arranged thereon. In particular, the system is suitable and intended for carrying out a skiving method according to claim 1.

[0073] Protection is also sought for a cutting insert for peeling as defined in the relevant claims.

[0074] Accordingly, it is provided that roughing cutting sections and finishing cutting sections are spatially separated from each other on at least one side of the respective section. Spatially separated or spaced apart means that there is a cutting edge-free area between a roughing cutting section and a finishing cutting section. The disclosed cutting inserts exhibit excellent material utilization due to the formation of distinct roughing and finishing cutting sections.

[0075] The relative position of the roughing and finishing cutting edges is determined by the basic geometric shape of the insert. In particular, the following basic geometric shapes are proposed: inserts with a triangular basic shape (so-called N-inserts), inserts with an elongated octagonal basic shape (so-called L-inserts), and inserts with a square basic shape (so-called S-inserts).

[0076] The invention is explained in more detail below with reference to the attached figures.

[0077] From the figures show:

[0078] Fig. 1 : an arrangement for peeling turning according to the state of the art

[0079] Fig. 2: an arrangement for peeling turning according to a first

[0080] Example

[0081] Fig. 3: an arrangement for peeling turning according to a further

[0082] Example

[0083] Fig. 4: a detail of the cutting plate from Figure 3

[0084] Fig. 5: an arrangement for peeling turning according to a further

[0085] Example

[0086] Fig. 6 a section of a cutting plate from Figure 5

[0087] Fig. 7 an embodiment of a cutting plate

[0088] Fig. 8 a section of the cutting plate from Figure 7

[0089] Fig. 9 an embodiment of a cutting plate

[0090] Fig. 10 another embodiment of a cutting plate

[0091] Fig. 11a and 11b Examples of cutting inserts

[0092] Fig. 12a-12c an embodiment of a tool holder in different views

[0093] Fig. 13a-13c another embodiment of a tool holder in different views

[0094] Fig. 14 Details of a cutting plate according to an embodiment

[0095] Fig. 15 Details of a cutting plate according to another

[0096] Example

[0097] Fig. 16 Details of a cutting plate according to another embodiment

[0098] Fig. 17 Arrangement of cutting plates according to another embodiment

[0099] Fig. 18 an embodiment of a cutting plate and

[0100] Fig. 19 this cutting plate in a side view

[0101] Fig. 20-23 Cutting plates according to another embodiment

[0102] Fig. 24-28 Cutting plates according to another embodiment

[0103] Fig. 29-33 Cutting plates according to a further embodiment Figure 1 shows an arrangement of two identical cutting plates 1, 1' for peeling according to the prior art.

[0104] The cutting inserts 1, 1' have a triangular basic shape according to ISO code "W" with angled, convex side edges. The cutting edges 2, 3 formed on each side edge extend at an external angle of approximately 210° to each other. The cutting inserts 1, 1' are indexable in three positions. By rotating them by 120°, unused cutting edges can be brought into a machining position.

[0105] The cutting inserts 1, 1' engage with a workpiece W in a machining operation, wherein, during a peeling operation as shown here, the workpiece is generally moved translationally in a machining direction D along a central axis M of the workpiece W and the cutting inserts 1, 1' rotate in a flight circle around the central axis M. The direction of movement of the cutting inserts 1, 1' is normal to the plane of the drawing and faces the viewer.

[0106] However, for the discussion of the engagement situation it is irrelevant whether the workpiece W rotates or the cutting inserts 1 , T .

[0107] The cutting inserts 1, 1' are arranged in a tool holder 6 such that the cutting insert 1 which is in front with respect to a machining direction D, i.e. which engages first, takes over the roughing operation with a roughing cutting section 2 which rises with respect to the machining direction D. The first cutting depth ap1 removed by the roughing cutting section 2 reduces a radius of the workpiece W from an original radius ro to a first radius n.

[0108] The following cutting insert 1' performs the finishing machining with a finishing cutting section 3 aligned parallel to the workpiece surface created by the preceding cutting insert 1.

[0109] The second cutting depth ap2 removed from the finishing cutting section 3 of the following cutting insert 1' reduces a radius of the workpiece W from the first radius n to a second radius r2.

[0110] The second cutting depth ap2 is significantly less than the first cutting depth ap1. The cutting inserts 1, 1' are set at the same angle of attack, i.e., KI = K2.

[0111] The finishing cutting sections 3 of the cutting inserts 1, 1' run parallel to the surface of the workpiece W.

[0112] In the following cutting insert 1', the part of the roughing cutting section 2 fed up to the cutting depth ap2 is in engagement.

[0113] The roughing cutting section 2 for roughing and the finishing cutting section 3 for finishing are connected. The cutting insert 1 has a continuous cutting edge all the way around with a chip-breaking structure 7 formed continuously on the top surface.

[0114] A disadvantage of the arrangement shown and the associated method for skiving is that the same sections of the inserts 1, 1' are used for both cutting operations, i.e., roughing and finishing. If an insert initially used for finishing is used for roughing after reaching a level of wear that is unacceptable for further use for finishing, the insert in the roughing position will have worn cutting edges from the outset.

[0115] A further disadvantage is that the chip guiding structures 7 on the cutting edges must be designed in such a way that they function equally for both cutting operations, i.e. roughing and finishing.

[0116] This represents an unfavorable compromise.

[0117] A particular disadvantage of such an arrangement is that both cutting inserts are engaged with the full length of their secondary cutting edges. This causes high passive forces during machining. This results in increased heat input due to friction. Furthermore, these high passive forces must be counteracted by a particularly rigid design.

[0118] Figure 2 shows an arrangement according to the invention in a first exemplary embodiment, based on which the method according to the invention and the cutting inserts according to the invention will be explained in more detail. It shows an arrangement of two cutting inserts 1, 1' in a schematically sketched tool holder 6.

[0119] Also shown schematically is a workpiece - W - and a machining direction D in which the workpiece W moves longitudinally relative to the tool holder 6.

[0120] The cutting plates 1, 1' have a triangular basic shape with rounded corners. In the present embodiment, the side edges are formed by straight sections.

[0121] The cutting plates 1, 1' have identical cover surfaces 51, 52, in particular the cutting plates 1, 1' each have two identical cover surfaces, i.e. they are double-sided in the sense that an upper side and a lower side do not differ.

[0122] Furthermore, it is provided that a plurality of roughing cutting sections 2, in this case exactly three, are formed on the cover surfaces 51, 52, and a plurality of finishing cutting sections 3, in this case exactly three, are formed differently from these. Following the basic geometric shape, the finishing cutting sections 3 each extend at an internal angle of 60° to one another.

[0123] A roughing cutting section 2 refers to a section of a cutting edge formed on a side edge of the cutting plate 1, 1', which is intended for rough machining (roughing).

[0124] A finishing cutting section 3 denotes a section of a cutting edge formed on a side edge of the cutting plate 1, 1', which is intended for fine machining (finishing).

[0125] A finishing cutting section 3 differs from a roughing cutting section 2 in particular in that a chamfer formed along the chip surface side of the finishing cutting section 3 is narrower than a chamfer formed along the chip surface side of a roughing cutting section 2.

[0126] Alternatively or additionally, it can be provided in particular that a chip guide structure 21 assigned to the roughing cutting section 2 extends further in the direction of a plate center than a chip guide structure 31 assigned to the finishing cutting section 3.

[0127] A larger chip deflector structure allows for the deflection of larger chip cross-sections. In particular, a support chamfer 320 with a support chamfer angle of 3° to 6° is formed along the finishing cutting edge sections 3. A support chamfer is a chamfer formed on a flank, in contrast to (protective) chamfers, which are formed on the rake face side.

[0128] In particular, there is no support chamfer on roughing cutting sections 2.

[0129] The roughing cutting section 2 has an at least partially curved profile. In particular, the curvature can be represented or approximated by an ellipse, the main axis of which is parallel to the adjacent side edge, such that the contour of the finishing cutting section 3 adjacent to the roughing cutting section 2 merges tangentially into the roughing cutting section 2.

[0130] Preferably, the curvature of the roughing cutting section 2 increases in the direction of the exit-side corner 82.

[0131] In the present embodiment and preferably for triangular cutting plates, three roughing cutting sections 2 and three finishing cutting sections 3 are formed on each of the cutting plates 1, 1'.

[0132] Between an output-side end of a roughing cutting section 2 and an input-side start of a finishing cutting section 3 there is preferably a cutting edge-free section 4.

[0133] Not implemented in the present embodiment, but also possible, is to provide a cutting edge-free section 4 between an output-side end of a finishing cutting section 3 and an input-side start of a roughing cutting section 2. In the present case, the roughing cutting sections 2 and finishing cutting sections 3 are spatially separated from each other only on one side of the respective section 2, 3.

[0134] The roughing cutting section 2 is formed at the corners of the cutting plates 1, 1'.

[0135] The finishing cutting section 3 is formed along the side edges of the cutting plates 1, 1'.

[0136] The preceding cutting plate 1 is set at a first angle of attack KI, which is defined here between a tangent to the input-side side edge and the central axis M.

[0137] The angle of attack KI of the above cutting insert 1 is 30° in the present embodiment. An angle of attack is generally specified as the angle between the cutting edge and the feed direction.

[0138] The preferred range for the angle of attack KI of the preceding cutting insert 1 for this form of the cutting insert 1 is between 20° and 35°, in particular between 25° and 30°.

[0139] The angle of attack KI of the preceding cutting insert 1 can also be advantageously described in relation to the position of the following cutting insert T: the following cutting insert 1' is positioned such that one side edge runs parallel to the central axis M, which corresponds to an angle of attack of zero degrees. The preceding cutting insert 1 is positioned more steeply than the following cutting insert 1' by the angle of attack KI. The angle of attack K1 of the preceding cutting insert 1 can also be understood in this insert shape such that the preceding cutting insert 1 is rotated 90° counterclockwise relative to the following cutting insert 1', whereby - following the geometry of the cutting insert 1 with side edges running at 120° to each other - the roughing cutting section 2 of the preceding cutting insert 1 is in engagement with an angle of attack K1 of 30°.In an N-plate designed with a radius, as shown here, the leading cutting plate 1 is rotated 60° counterclockwise relative to the following cutting plate 1'. The approach angle KI of the leading cutting plate 1 is preferably selected such that a final contact point P of the roughing cutting section 2 on the output side is located before the end of the roughing cutting section 2.

[0140] In other words, it is preferably provided that an output-side end of the roughing cutting section 2 no longer has contact with a workpiece surface. In particular, it is provided that an output-side corner 82 is spaced from the workpiece surface.

[0141] A theoretical angle of attack Kth can be defined between

[0142] - a connection between the last contact point P on the output side and the first contact point on the input side, at which the first cutting depth ap1 of the preceding cutting insert 1 can be read, and

[0143] - the machining direction D, here corresponding to a parallel to the central axis M. The theoretical angle of attack Kth is approximately 18°.

[0144] Furthermore, the cutting insert 1 (on the left in the illustration) which is in front with respect to the machining direction D is advanced such that the cutting insert 1 is in engagement with the workpiece W with a roughing cutting section 2 formed at a corner having a maximum first cutting depth ap1.

[0145] On the cover surface 51, which is partially designed as a chip surface, a chip guide structure 21 is assigned to the roughing cutting section 2.

[0146] The chip breaker structure 21 assigned to the roughing cutting edge section 2 is preferably designed asymmetrically with respect to an angularly symmetrical WS of the corner of the cutting insert 1, in the sense that a surface portion of the chip breaker structure 21 located at the front (input side) in the machining direction with respect to the angularly symmetrical WS is larger than a surface portion located at the rear with respect to the angularly symmetrical WS. For the sake of clarity, not all roughing cutting edge sections 2 and associated chip breaker structures 21 are highlighted by reference numerals in the drawing.

[0147] The cutting insert 1' following with respect to the machining direction D is advanced such that the cutting insert 1' is in engagement with the workpiece W with a finishing cutting section 3 formed on a side edge with a maximum second cutting depth ap2.

[0148] The cutting insert 1' is set at a second angle of attack K2 that is different from the first angle of attack KI. The second angle of attack K2 is smaller than the first angle of attack KI. In the present embodiment, the second angle of attack K2 is 0° (zero degrees). This means that the second cutting insert 1' runs with the finishing cutting edge section 3 parallel to the central axis M.

[0149] The cutting inserts 1, 1' are arranged in the tool holder 6 such that the leading cutting insert 1 engages only with a roughing cutting edge section 2, and the trailing cutting insert 1' engages only with a finishing cutting edge section 3. This ensures that no wear of a finishing cutting edge section 3 occurs on the leading cutting insert 1, and no wear of a roughing cutting edge section 2 occurs on the trailing cutting insert 1'.

[0150] The tool holder 6 is designed to receive and fix a first cutting plate 1 in such a way that the first cutting plate 1 intended for roughing is set at a first setting angle K1 and the roughing cutting section 2 is in a machining position.

[0151] The tool holder 6 is further designed to receive and fix a second cutting plate 1' in such a way that the second cutting plate 1' intended for finishing is set at a second setting angle K2 which is different from the first setting angle K1 and is smaller than the first setting angle, and the finishing cutting section 3 is in a machining position.

[0152] A finishing cutting edge section 3 is divided, in particular, into an inlet-side main cutting edge section 331 and an outlet-side secondary cutting edge section 332. The main cutting edge section 331 and the secondary cutting edge section 332 are connected to one another, but differ in that the main cutting edge section 331 has an angled profile toward the plate center compared to the secondary cutting edge section 332.

[0153] Such a structure of the finishing cutting section 3 is particularly advantageous since the main cutting section 331 is designed for chip removal corresponding to the second chip depth ap2, while the secondary cutting section 332, which runs straight and parallel to the central axis M, performs a pure smoothing function.

[0154] In particular, a support chamfer 320 with a support chamfer angle between 3° and 6° is formed on the secondary cutting edge section 332.

[0155] An exit-side transition of the secondary cutting edge section 332 to the adjacent roughing cutting edge section 2 is characterized in particular by an increase in the width of the chamfer formed on the rake face side. The roughing cutting edge section 2 has a wider chamfer than the finishing cutting edge section 3.

[0156] The first cutting depth ap1 of the preceding cutting insert 1, which is in engagement with a roughing cutting section 2, is preferably selected such that the roughing cutting section 2 is fully engaged, but the adjacent secondary cutting section 332 of the finishing cutting section 3 on the input side (i.e. on the left in the illustration) has no contact with the workpiece W.

[0157] This ensures ideal utilization of the available cutting length of the roughing cutting section 2. Furthermore, it is avoided that a secondary cutting section 332, which may be worn due to previous use, is involved in the material removal.

[0158] In practice, it is preferably provided that - based on a side view of the cutting insert 1, 1' - the secondary cutting edge section 332 is at the same level as the roughing cutting edge section 2. In other words, there is preferably no height offset of the cutting edge between the secondary cutting edge section 332 and the roughing cutting edge section 2. This ensures that, in the case of relatively large out-of-roundness of the workpiece W, continuous chip removal takes place without scoring, even when the secondary cutting edge section 332 enters the preceding cutting insert 1. The conditions are discussed here for a direction of rotation shown here along a left-hand spiral in a feed direction. It is understood that for a reverse machining direction, the arrangement of the cutting edges on the cutting inserts 1, 1' would be mirrored accordingly.

[0159] Figure 3 shows an arrangement according to the invention in a further exemplary embodiment, on the basis of which the method according to the invention and the cutting inserts according to the invention will be explained in more detail.

[0160] The tool holder 6 and the workpiece W are indicated.

[0161] In this example, the cutting inserts 1, 1' are rounded, octagonal, and elongated. This insert type is also referred to as an L-shaped insert.

[0162] The long side edges preferably run parallel. The short side edges on the end faces of the L-shaped plate shown generally run at 90° to the long side edges and are preferably rounded.

[0163] As in the embodiment according to Figure 2, the cutting plates 1, 1' are arranged such that the leading cutting plate 1 engages along and only with a roughing cutting section 2, and the following cutting plate 1' engages only with a finishing cutting section 3. In this preferred embodiment, the roughing cutting sections 2 and the finishing cutting sections 3 are each spaced apart by a cutting edge-free section 4.

[0164] In the present case, the roughing cutting sections 2 and finishing cutting sections 3 are spatially separated from each other on both sides of the respective section 2, 3.

[0165] The cutting insert 1 (on the left in the illustration) which is in front with respect to the machining direction D is advanced such that the first cutting insert 1 with the roughing cutting section 2 is in engagement with the workpiece W with a maximum first cutting depth ap1.

[0166] The angle of attack K1 of the preceding cutting insert 1 is approximately 10° in the present embodiment. In any case, the preceding cutting insert 1 is set at a significantly steeper angle than the following cutting insert 1'. The angle of attack K1 of the preceding cutting insert 1 can be specified in this insert shape as the angle between a tangent to the engaged roughing cutting section 2 and the central axis M. The angle of attack K1 of the preceding cutting insert 1 can also be understood in this insert shape - with side edges extending at an angle of 90° to each other - as meaning that the preceding cutting insert 1 is rotated 80° counterclockwise relative to the following cutting insert 1', whereby the roughing cutting section 2 of the preceding cutting insert 1 engages with an angle of attack K1 of 10°. Preferably, the angle of attack K1 of the preceding cutting insert

[0167] 1 in the rounded octagonal, elongated basic shape shown here between 2° and 20°, more preferably between 5° and 15°, in particular at 10° ± 3°.

[0168] A theoretical angle of attack Kth can be defined between

[0169] - a connection between the last contact point P on the output side and the first contact point on the input side, at which the first cutting depth ap1 of the preceding cutting insert 1 can be read, and

[0170] - the machining direction D, here corresponding to a parallel to the central axis M. The theoretical angle of attack Kth is approximately 11 °.

[0171] Preferably, an adjustment of the preceding cutting plate 1 is selected such that an output-side last contact point P of the roughing cutting section 2 before the end of the roughing cutting section

[0172] 2. In other words, it is preferably provided that an output-side end of the roughing cutting section 2 has no contact with a workpiece surface. In particular, it is provided that an output-side corner 82 is spaced from the workpiece surface.

[0173] The cutting insert 1' following with respect to the machining direction D is advanced such that the cutting insert 1' is in engagement with the workpiece W with a finishing cutting section 3 formed on a long side edge with a maximum second cutting depth ap2.

[0174] The cutting insert 1' is set at a second angle of attack K2 that is different from the first angle of attack KI. The second angle of attack K2 is smaller than the first angle of attack KI. In the present embodiment, the second angle of attack K2 is 0° (zero degrees). This means that the second cutting insert 1' is arranged with the engaged side edge parallel to the central axis M, which in this case is equivalent to parallel to the feed direction.

[0175] As in the previous embodiment, the finishing cutting section 3 is also divided into a main cutting section 331 and a secondary cutting section 332. The main cutting section 331 and the secondary cutting section 332 are connected to each other, but differ in that the main cutting section 331 has an angled and, in particular, curved profile towards the center of the plate compared to the secondary cutting section 332.

[0176] Due to this design, the main cutting section 331 takes over the chip removal corresponding to the second chip depth ap2, while the secondary cutting section 332, which runs straight and parallel to the central axis M, ensures smoothing of the workpiece surface.

[0177] In addition to the angled extension of the main cutting section 331 relative to the secondary cutting section 332, it is provided that the chip breaker structure 31 extends further toward the center of the plate than the chip breaker structure 31 in the region of the secondary cutting section 332. This takes into account the fact that the actual material removal on the second cutting insert 1' takes place in the region of the main cutting section 331. It can also preferably be provided that elevations 311 for chip formation are formed within the chip breaker structure 31 assigned to the main cutting section 331. The elevations 311 are, in particular, dome-shaped.

[0178] Advantageously and shown in the present embodiment is a curved profile of the roughing cutting section 2. Preferably, the profile is continuously convex.

[0179] In the present case, the roughing cutting edge sections 2 have a curvature along a circle of curvature KK. Alternatively, the roughing cutting edge section 2 could have a curved profile that deviates from a circular arc. In this exemplary embodiment, a circle of curvature KK describing the curvature of the roughing cutting edge section 2 has a larger diameter than the longitudinal extension of the cutting insert 1, 1'.

[0180] This creates advantageously gentle machining conditions, which can only be achieved with round inserts normally used for roughing by using large diameter round inserts.

[0181] The curved course can end as a straight section towards an exit-side corner 82.

[0182] A curved course of the roughing cutting section 2 leads to lower cutting forces and less wear compared to a straight course of the roughing cutting section 2.

[0183] In particular, the preceding cutting insert 1 is positioned such that the curvature of the roughing cutting section 2 runs tangentially to the workpiece surface being produced. This achieves a particularly smooth chip removal process.

[0184] Preferably, the chip breaker structure 21 assigned to the roughing cutting section 2 is designed asymmetrically with respect to a bisector LS along the longitudinal extent of the cutting insert 1, 1'. In particular, the chip breaker structure 21 is designed asymmetrically in the sense that a surface portion of the chip breaker structure 21 located on the input side with respect to the bisector LS is larger than a surface portion of the chip breaker structure 21 located on the output side with respect to the bisector LS.

[0185] This advantageously ensures that a larger area portion of the chip guide structure 21 is allocated to the chip removal on the input side.

[0186] Alternatively or additionally, the asymmetry of the chip breaker structure 21 can be such that a mean lateral extent of the chip breaker structure 21, i.e., a mean dimension transverse to the bisector LS, is larger with respect to the bisector LS on the input side than with respect to the bisector LS on the output side. The relationships are discussed here for a direction of rotation shown here along a left-hand spiral in a feed direction. It is understood that in a reverse machining direction, the arrangement of the cutting sections would be mirrored accordingly.

[0187] The advantage of spacing the roughing cutting sections 2 and the finishing cutting sections 3 by a cutting edge-free section 4 is that the cover surfaces 51, 52 on the cutting edge-free sections 4 extend to the edge of the cutting inserts 1, 1'. If a cutting insert 1, 1' is turned so that a cover surface 51, 52 comes to rest in a tool holder 6, the cutting insert 1, 1' can be mechanically advantageously supported up to the edge of the cutting insert 1, 1'. In the context of the present application, "cutting edge-free" means in particular that the lateral edge of the cutting insert 1, 1' along a section 4 is not designed as a cutting edge. This means that along the cutting edge-free section 4, the side edge of the cutting insert 1, 1' in particular has no chamfer and / or no chip guiding structure is assigned to the side edge in the relevant area.

[0188] Figure 4 shows a section of the cutting insert 1 from Figure 3. The conditions of the chip breaker structure 21 can be seen in more detail. The chip breaker structure 21 has a surface that is bounded by the contour 22 of the chip breaker structure 21 and the roughing cutting section 2. Two partial surfaces can be defined: a first partial surface is located on the input side with respect to the bisector LS, a second partial surface is located on the output side with respect to the bisector LS.

[0189] As already explained, the chip guide structure 21 is preferably designed asymmetrically, such that the first partial area is larger than the second partial area, in particular at least 10% larger.

[0190] Furthermore, a lateral extension Su can be specified for the partial surfaces, which indicates a width of a partial surface normal to the bisector LS and between the bisector LS and the contour 22 of the chip breaker structure 21. Preferably, an average lateral extension SLI of the first partial surface is greater than an average lateral extension SL2 of the second partial surface. Also highlighted in the figure is a depth extension Lu of the chip breaker structure 21 to explain the extent of a depth extension of a chip breaker structure. A depth extension LTI indicates how far the chip breaker structure 21 extends between the cutting edge, here the roughing cutting section 2, and the contour 22 of the chip breaker structure 21 in the direction of a plate center.

[0191] Figure 5 shows an arrangement according to the invention in a further exemplary embodiment, on the basis of which the method according to the invention and the cutting inserts according to the invention will be explained in more detail.

[0192] The tool holder 6 and the workpiece W are only indicated.

[0193] In the exemplary embodiment, the cutting plates 1, 1' are rounded and square.

[0194] The preceding cutting plate 1, i.e. the one that engages first, is set at a first angle of attack K1, which in the example shown is 15°.

[0195] The cutting insert 1 (on the left in the illustration) which is in front with respect to the machining direction D is advanced such that the first cutting insert 1 with the roughing cutting section 2 is in engagement with the workpiece W with a maximum first cutting depth ap1.

[0196] At a first angle of attack K1 of 15°, at a

[0197] For example, a plate inside diameter of 32 mm achieves a maximum first cutting depth ap1 of 5 mm.

[0198] If the same insert is set at a steeper angle, for example with a first angle of attack K1 of 20°, a maximum first cutting depth ap1 of 6 mm is achieved.

[0199] If the same plate is set with a first angle of attack K1 of 25°, a maximum first cutting depth ap1 of 8.5 mm is achieved.

[0200] These numerical examples demonstrate that the cutting depths can be determined by varying the angle of attack of the preceding insert. This advantageously takes into account the machinability of the material to be machined. High-alloy / high-strength materials, for example, can be machined with a smaller angle of attack (e.g., 15°) and a correspondingly lower cutting depth.

[0201] The above-mentioned cutting insert 1 has four roughing cutting edge sections 2 with associated chip breaker structures 21 on its top surface 51. The roughing cutting edge sections 2 are each spaced apart by a cutting edge-free section 4. In particular, no defined cutting edge and / or chip breaker structure is formed along the side edge of the cutting insert 1 in the region of the cutting edge-free section 4. An edge is considered a "defined" cutting edge if a chamfer and / or a rounding is formed thereon.

[0202] In particular, the cover surface 51 extends in the region of the cutting edge-free section 4 up to the edge of the cutting plate 1, whereby support up to the edge is possible in a turned position of the cutting plate 1.

[0203] The cutting insert 1', which is positioned downwards with respect to the machining direction D, has four finishing cutting edge sections 3 with associated chip breaker structures 31 on its top surface 52.

[0204] A support chamfer 320 is preferably formed on the flank side of the finishing cutting edge sections 3. Support chamfers stabilize the cutting wedge and improve the suitability of a cutting edge for smoothing.

[0205] The finishing cutting sections 3 are each spaced apart by a cutting edge-free section 4. In particular, the cover surface 52 extends in the region of the cutting edge-free section 4 to the edge of the cutting insert 1', whereby support up to the edge is possible in a turned position of the cutting insert 1'.

[0206] The following cutting insert 1' is advanced such that the cutting insert 1', with a finishing cutting edge section 3 formed on a side edge and having a maximum second cutting depth ap2, is in engagement with the workpiece W. The cutting insert 1' is set at a second setting angle K2 that is different from the first setting angle KI. The second setting angle K2 is smaller than the first setting angle KI. In the present embodiment, the second setting angle K2 is 0° (zero degrees). This means that the engaging side edge runs parallel to the central axis M.

[0207] The cutting plates 1, 1' are each positioned in such a way that the cutting edge-free sections 4 do not engage.

[0208] In the present exemplary embodiment, the embodiment of the method and the cutting plates 1, 1' is shown in which the cover surfaces 51, 52 of the sides of the cutting plates 1; 1' currently in engagement differ.

[0209] In this context, it is preferably provided that on each cutting plate 1;1' one side is designed as a “roughing side”, i.e. exclusively with roughing cutting sections 2, and the other side is designed as a “finishing side” with exclusively finishing cutting sections 3.

[0210] In other words, the cutting inserts 1;1' are double-sided with different top and bottom surfaces. One side contains exclusively roughing cutting sections 2, while the other side contains exclusively finishing cutting sections 3.

[0211] In the present case, the roughing cutting sections 2 and finishing cutting sections 3 are spatially separated from each other as they are located on different sides of the cutting plates 1, 1'.

[0212] In addition, the roughing cutting sections 2 and the finishing cutting sections 3 are spatially separated from each other, as there is a cutting edge-free section 4 between them.

[0213] As in the previously discussed embodiments, the finishing cutting section 3 is also divided into a main cutting section 331 and a secondary cutting section 332. The main cutting section 331 and the secondary cutting section 332 are connected to one another, but differ in that the main cutting section 331 has an angled and, in particular, curved profile towards the plate center compared to the secondary cutting section 332.

[0214] With this configuration, the main cutting edge section 331 takes over the chip removal corresponding to the second chip depth ap2, while the secondary cutting edge section 332, which runs straight and parallel to the central axis M, ensures smoothing of the workpiece surface. Particularly in the area of ​​the main cutting edge section 331, elevations 311 for chip formation are formed in the chip guide structure 31 of the finishing cutting edge section 3. This is particularly advantageous since the actual chip removal by the finishing cutting edge section 3 takes place in the area of ​​the main cutting edge section 331.

[0215] Figure 6 shows a partial cross-section of the cutting insert 1' (the cutting insert below) according to section AA of Figure 5. It thus concerns that side of a cutting insert 1, 1' on which exclusively finishing cutting sections 3 are formed. The section AA occurs in the region of the secondary cutting section 332.

[0216] A depth extension STS of the chip breaker structure 31 assigned to the finishing cutting section 3 is presently approximately 20% of the distance from the finishing cutting section 3 to a plate center. Preferably, the depth extension of the chip breaker structure 31 is between 5% and 30% of the distance from the finishing cutting section 3 to the plate center. In particular, this applies to at least 50%, preferably at least 70%, more preferably at least 80% of a length of the contour 32 of the chip breaker structure 31 of the finishing cutting section 3. This expresses that the chip breaker structure 31 of the finishing cutting section 3 is narrow, whereby a large support surface is available when the cutting insert 1' is in a turned position.

[0217] The chip guide structure 31 is formed into the cover surface 52 and is at least partially lowered relative to the cover surface 52.

[0218] A profile depth SPS is entered at the deepest point of the chip breaker structure 31 in the present section.

[0219] A maximum profile depth of the chip breaker structure 31 is in particular between 0.1 mm and 0.7 mm.

[0220] The chip breaker structure 31 of the finishing cutting edge section 3 preferably has elevations 311 for chip formation. The elevations 311 are particularly dome-shaped. The elevations 311 for chip formation are particularly formed on the entry side, i.e., in the region of the main cutting edge section 331.

[0221] In the area of ​​the secondary cutting edge section 332, and in particular on the exit side, there are preferably no elevations 311 for chip formation.

[0222] In particular, the finishing cutting section 3 is lowered at least in sections, in particular along its entire extent, compared to the level of the cover surface 52.

[0223] Figure 7 shows a top view of the above cutting insert 1, indicating section BB. This refers to the side of the two-sided cutting insert 1, 1' on which only roughing cutting sections 2 are formed.

[0224] Figure 8 shows a partial cross-section of the cutting plate 1 according to section BB of Figure 7.

[0225] The chip breaker structure 21 assigned to the roughing cutting section 2 has a depth extension ST2 at the cutting position.

[0226] A maximum depth extension ST2max of the chip breaker structure 21 is the maximum normal distance from the roughing cutting section 2 to the contour 22 of the chip breaker structure 21.

[0227] A maximum depth extension ST2max of the chip breaker structure 21 is in particular between 15% and 50% of the distance between the roughing cutting section 2 and the plate center.

[0228] This expresses that the chip breaker structure 21 assigned to the roughing cutting section 2 preferably extends far towards the center of the plate.

[0229] The chip guide structure 21 is formed into the cover surface 51 and is at least partially lowered relative to the cover surface 51.

[0230] A profile depth SP2 is marked at the deepest point of the chip breaker structure 21 in the present section. The profile depth SP2 is preferably between 0.2 mm and 2.5 mm. At the cutting position BB shown, the profile depth SP2 is approximately 0.8 mm. The roughing cutting section 2 is preferably lowered at least in sections, in particular along its entire extent, relative to the level of the cover surface 51.

[0231] Figure 9 shows schematically a cutting plate 1 from Figure 2 in a perspective view.

[0232] On an edge 11 of the cutting insert 1, cutting edges in the form of roughing cutting sections 2 and finishing cutting sections 3 are formed in sections. Regarding the arrangement of the cutting sections, the cutting insert 1 is designed for use according to the machining direction discussed so far. The division of the finishing cutting section 3 into a main cutting section 331 and a secondary cutting section 332 is thus such that the main cutting section 331 is located on the input side during use, and the secondary cutting section 332 is located on the output side.

[0233] A support chamfer 320 is preferably formed along the finishing cutting edge sections 3, and in particular along the respective secondary cutting edge section 332. In the exemplary embodiment shown, the support chamfer 320 extends slightly beyond the secondary cutting edge section 332 on both sides, i.e., on the input side into the main cutting edge section 331 and on the output side into the roughing cutting edge section 2. It is preferred that the support chamfer 320 extends only along the secondary cutting edge section 332 or that the support chamfer 320 also extends partially into the main cutting edge section 331. The support chamfer 320 preferably ends before the roughing cutting edge section 2. The roughing cutting edge section 2 is therefore preferably free of a support chamfer 320.

[0234] Between an output-side end of the roughing cutting section 2 and a finishing cutting section 3, a cutting edge-free section 4 is provided, in which the cover surface 51 extends to the edge 11 of the cutting insert 1. Since the cutting insert 1 - as preferably provided - is designed as an indexable insert on both sides, the cutting edge-free sections 4 can also be seen as projections on the lower side of the cutting insert 1 with respect to the illustration, since in the area of ​​the cutting edge-free sections 4, the level of the lower cover surface 52 (not visible here) extends to the edge of the cutting insert 1.

[0235] Figure 10 shows a cutting plate 1 from Figure 3 in a perspective view.

[0236] Between the roughing cutting sections 2 and the finishing cutting sections 3, cutting edge-free sections 4 are provided, in which the cover surface 51 extends to the edge 11 of the cutting insert 1.

[0237] A support chamfer 320 is preferably formed along a secondary cutting edge section 332 of a finishing cutting edge section 3. A support chamfer is a chamfer on the flank face. The support chamfer 320 ensures improved stability of the cutting wedge in the region of the secondary cutting edge section 332, which provides smoothing.

[0238] Figures 11 a and 11 b show cutting plates 1, 1' from Figure 5 in a perspective view. As already discussed, the cutting plate 1, 1' with a square basic shape is preferably designed as a two-sided cutting plate in which the top and bottom sides are different.

[0239] Figure 11a shows the cutting insert 1, 1' with the cover surface 52 as the upper side, on which cover surface 52 exclusively finishing cutting sections 3 are formed. In the present case, four finishing cutting sections 3 are present.

[0240] The finishing cutting sections 3 are each spaced apart by a cutting edge-free section 4.

[0241] A support chamfer 320 is preferably formed along a secondary cutting edge section 332 of a finishing cutting edge section 3. The support chamfer 320 ensures improved stability of the cutting wedge in the region of the secondary cutting edge section 332, which ensures smoothing. Figure 11 b shows the cutting insert 1, 1' with that cover surface 51 as being at the top in the illustration, on which cover surface 51 exclusively roughing cutting edge sections 2 are formed.

[0242] The roughing cutting sections 2 are each spaced apart by a cutting edge-free section 4 and thus spatially separated. The drawing shows the support chamfer 320 of the finishing cutting sections 3 located on the other side of the insert.

[0243] Figures 12a to 12c show a tool holder 6 designed as a cassette with cutting plates 1, 1' fixed therein in different views.

[0244] The cutting plates 1, 1' shown in the example correspond to those in Figures 3, 4 and 10.

[0245] Figure 12a shows the tool holder 6 in an elevation, i.e., a front view. Figure 12b shows the tool holder 6 in a top view. Figure 12c shows the tool holder 6 in a perspective view. The tool holder 6 is designed to receive and secure a first cutting insert 1 in such a way that the first cutting insert 1, intended for roughing, is set at a first angle of attack K1 and the roughing cutting section 2 is in a machining position.

[0246] The tool holder 6 is further configured to receive and secure a second cutting insert 1' in such a way that the second cutting insert 1', intended for finishing, is set at a second setting angle K2 that is different from the first setting angle K1, smaller than the first setting angle, and the finishing cutting section 3 is in a machining position. In particular, the design of the tool holder 6 also allows a ratio of the cutting depths of the first cutting insert 1 and the second cutting insert 1' to be specified.

[0247] The second angle of attack K2 is zero degrees.

[0248] Figures 13a to 13c show a tool holder designed as a cassette

[0249] 6 with cutting inserts 1, 1' fixed therein in various views. Figure 13a shows the tool holder 6 in an elevation. Figure 13b shows the tool holder 6 in a plan view. Figure 13c shows the tool holder 6 in a perspective view. Shown here is a tool holder 6 which is designed to hold double-sided cutting inserts 1, 1' according to the example in Figure 5. In these cutting inserts 1, 1', the top and bottom sides are different. On a first cover surface 51, there are exclusively roughing cutting sections 2, and on the second cover surface 52 there are exclusively finishing cutting sections 3.

[0250] The tool holder 6 is designed to receive and secure a first cutting insert 1 in such a way that the first cutting insert 1, intended for roughing, is set at a first angle of attack K1 and the roughing cutting section 2 is in a machining position. The tool holder 6 is further designed to receive and secure a second cutting insert 1' in such a way that the second cutting insert 1', intended for finishing, is set at a second angle of attack K2, which is different from the first angle of attack K1 and smaller than the first angle of attack, and the finishing cutting section 3 is in a machining position. In particular, the design of the tool holder 6 also allows a ratio of the cutting depths of the first cutting insert 1 and the second cutting insert 1' to be specified. The second angle of attack K2 here is zero degrees.

[0251] Preferably provided and evident from Figure 13a, a plate seat 61 of the cutting insert 1 intended for roughing is designed with a tilt angle α relative to a plate seat 62 of the cutting insert 1' intended for finishing. The tilt angle α is approximately 3° in this case. Preferably, the tilt angle α is between 0° and 6°. The advantages of tilting are improved clearance of the cutting insert and a softer, peeling cut.

[0252] As can be seen from Figure 13b, the cutting inserts 1, 1' are preferably provided with a marking to clearly distinguish the top and bottom surfaces. The letter "R" (for rough machining) is embossed into the top surface 51 with roughing cutting sections 2. The letter "F" (for fine machining) is embossed into the top surface 52 with finishing cutting sections 3.

[0253] Figure 14 shows a cutting insert 1, 1' with a triangular basic shape (a so-called N-insert), as discussed in the exemplary embodiment according to Figure 2. Highlighted in the present drawing is a corner region EB, which extends from a corner E of the cutting insert 1, 1' toward a center of the insert. The center of the insert is understood to be, in particular, a center of gravity of the cutting insert. The drawing serves to illustrate the further development, according to which the roughing cutting sections 2 are formed in a corner region EB of the cutting insert 1, 1'.

[0254] The finishing cutting sections 3 are, in contrast, formed in particular along a side edge of the cutting plate.

[0255] The corner region EB comprises, in particular, that portion of the surface of the cutting insert 1, 1' in a plan view which extends from the relevant corner E toward the center of the insert and occupies between 10% and 30% of the total surface of the cutting insert 1, 1'. This expresses that roughing cutting sections 2 are preferably located adjacent to corners E of the cutting insert 1, 1', whereby, with appropriate positioning of the cutting insert 1, 1', only one roughing cutting section 2 engages. Thus, large cutting depths can be achieved without a finishing cutting section 3 engaging.

[0256] On the present plate shape, an angle ß between a roughing cutting section 2 and a finishing cutting section 3 can be defined as spanned between a line parallel to the straight path of the finishing cutting section 3 and the roughing cutting section 2, wherein the orientation of the roughing cutting section 2 is specified as the connection between the beginning of the roughing cutting section 2 facing away from the considered corner E and the corner E. The angle ß between a roughing cutting section 2 and a finishing cutting section 3 is approximately 78° in the present case.

[0257] Figure 15 shows a cutting plate 1, 1' as in the embodiment according to

[0258] Figure 3 was presented. The drawing serves to illustrate the further development, according to which the roughing cutting sections 2 are formed in a corner region EB of the cutting insert 1, 1'. The explanation given in Figure 14 applies accordingly.

[0259] Figure 16 shows a two-sided cutting plate 1, 1' as presented in the embodiment according to Figure 5.

[0260] Unlike the cutting insert with a triangular basic shape according to Figure 2 and unlike the cutting insert with an L-basic shape according to Figure 3, only roughing cutting sections 2 are formed on one of the cover surfaces 51 visible here.

[0261] Figure 17 shows an arrangement of two cutting plates 1, 1' with a triangular basic shape (so-called N-plates) in another exemplary embodiment. The cutting plates 1, 1' are arranged rotated 180° relative to each other. Thus, the facing side edges run parallel, resulting in a particularly compact arrangement.

[0262] A theoretical angle of attack Kth of the roughing cutting section 2 is 24° in this case.

[0263] Figure 18 shows a cutting plate 1, 1' from Figure 17 in a perspective view.

[0264] Figure 19 shows a cutting plate 1, 1' from Figure 17 in a side view.

[0265] In the cutting inserts 1, 1' shown in Figures 17 to 19, the roughing cutting sections 2 and the finishing cutting sections 3 are each spaced apart by a cutting edge-free section 4 and thus spatially separated. The cutting inserts 1, 1' have two identical cover surfaces, i.e., they are double-sided in the sense that there is no difference between the top and bottom surfaces.

[0266] Figure 20 shows an arrangement of two cutting plates 1, 1' with a triangular basic shape (so-called N-plates) in a further exemplary embodiment. In contrast to the exemplary embodiment of Figure 17, the cutting plates 1, 1' have cutting edge-free sections 4 only between an outlet-side end of a roughing cutting section 2 and a finishing cutting section 3. In this exemplary embodiment, the cutting plates 1, 1' are also double-sided, i.e., the top and bottom sides are the same.

[0267] Figures 21-23 show the cutting plate 1, 1' of this embodiment in different views.

[0268] Figures 24-28 show different views of a cutting plate 1, 1' with a triangular basic shape (so-called N-plate) according to a further embodiment.

[0269] Here, the case is realized that the upper and lower sides are different: on the first cover surface 51, only roughing cutting sections 2 are formed.

[0270] Finishing cutting sections 3 and roughing cutting sections 2 are formed on the second cover surface 52. This makes it possible to initially use the cutting insert with the second cover surface 52 for roughing, with the cutting insert 1, 1' being used as the leading insert in an installation position as shown in Figure 20. After the roughing cutting sections 2 on the second cover surface 52 have been used up, the cutting insert 1, 1' can be used in a subsequent position for finishing with the finishing cutting sections 3.

[0271] After the finishing cutting edges 3 have been used up, the cutting insert 1, 1' can be turned over and used for roughing with the roughing cutting edges 2 on the first cover surface 51. The cutting insert 1, 1' would then be positioned for use of the roughing cutting edges 2 on the first cover surface 51, as indicated in Figure 28, at a flatter angle of attack than that shown in Figure 20—here approximately 20°.

[0272] This allows particularly good material utilization to be achieved, in particular because a cutting insert has more of the roughing cutting sections 2, which are subject to particularly heavy wear.

[0273] A support chamfer 320 is provided along each of the finishing cutting sections 3.

[0274] Figures 29-33 show various views of an L-shaped plate in another embodiment. The cutting plate 1, 1' is significantly compressed compared to the embodiment shown in Figure 3, i.e., it is shorter.

[0275] This allows a particularly compact arrangement of the cutting plate 1, 1' with a simultaneous sufficient length of the finishing cutting sections 3. In this exemplary embodiment, a tapered end of a finishing cutting section 3 is spaced from a roughing cutting section 2 via a cutting edge-free section 4.

[0276] The top and bottom are no different.

[0277] The features of the roughing cutting sections 2 and finishing cutting sections 3 discussed with reference to the embodiments generally apply to cutting inserts within the scope of the present application.

Claims

Claims 1. A method for skiving a workpiece (W), wherein at least two identical cutting plates (1, 1') are arranged in a tool holder (6), on each of which a plurality of roughing cutting edge sections (2) and a plurality of different finishing cutting edge sections (3) are formed, wherein in an installed position the cutting plate (1) which is in front with respect to a machining direction and is intended for roughing is adjusted such that it engages only with one roughing cutting edge section (2) and the cutting plate (1') which is below and is intended for finishing is adjusted such that it engages only with one finishing cutting edge section (3).

2. Method according to claim 1, wherein the cutting plate (1) which is in front with respect to a machining direction and is intended for roughing is set at a first setting angle (K1) and the cutting plate (1') which is behind with respect to the machining direction is set at a second setting angle (K2) which is different from the first setting angle (K1), wherein the first setting angle (K1) is greater than the second setting angle (K2).

3. Method according to claim 1 or 2, wherein a finishing cutting section (3) has a secondary cutting section (332) and a main cutting section (331) extending at an angle thereto in the direction of a plate center, wherein the secondary cutting section (332) is set substantially parallel to a center axis (M) of the workpiece (W) and the main cutting section (331) is set such that it covers at least 80% of a second cutting depth (ap2) to be removed by the finishing cutting section (3).

4. Method according to at least one of claims 1 to 3, wherein the cutting plates (1, 1') either each have two identical cover surfaces (51, 52), wherein a plurality of roughing cutting edge sections (2) and, different therefrom, a plurality of finishing cutting edge sections (3) are formed on the cover surfaces (51, 52), or the cutting plates (1, 1') are formed on two sides in such a way that the cover surfaces (51, 52) differ and only a plurality of roughing cutting edge sections (2) are formed on one cover surface (51) of a cutting plate (1, 1') and a plurality of finishing cutting edge sections (3) and optionally further roughing cutting edge sections (2) are formed on the other cover surface (52).

5. Method according to one of claims 1 to 4, wherein a first cutting depth (ap1) of the preceding cutting plate (1) is greater than a second cutting depth (ap2) of the following cutting plate (1') and the first cutting depth (ap1) is in particular between 0.5 mm and 8 mm.

6. Method according to one of the preceding claims 1 to 5, wherein the second cutting depth (ap2) of the following cutting plate (1') is between 0.1 mm and 2 mm.

7. System comprising a tool holder (6), in particular a cassette (6), for skiving, comprising at least two insert seats (61, 62) and identical cutting inserts (1, 1') arranged thereon, on each of which a plurality of roughing cutting edge sections (2) and a plurality of different finishing cutting edge sections (3) are formed, and the insert seats (61, 62) are designed such that the cutting insert (1) which is in front with respect to an intended machining direction and is intended for roughing is oriented such that only one roughing cutting edge section (2) is in an engaged position and that the cutting insert (1') which is below and is intended for finishing is oriented such that only one finishing cutting edge section (3) is in an engaged position.

8. Cutting plate (1, 1') for peeling, wherein the cutting plate (1, 1') is either - has two identical cover surfaces (51, 52), wherein a plurality of roughing cutting sections (2) and a plurality of different finishing cutting sections (3) are formed on the cover surfaces (51, 52), or - the cutting plate (1, 1') is formed on two sides, such that the cover surfaces (51, 52) differ and on one cover surface (51) of the cutting plate (1, 1') exclusively a plurality of roughing cutting sections (2) and on the other cover surface (52) exclusively a plurality of different finishing cutting sections (3) are formed, wherein roughing cutting sections (2) and finishing cutting sections (3) are spatially separated from one another at least on one side of the respective section (2, 3).

9. Cutting plate (1, 1') according to claim 8, wherein a roughing cutting section (2) is formed at a corner region (EB) of the cutting plate (1, 1').

10. Cutting plate (1, 1') according to claim 8 or 9, wherein a finishing cutting edge portion (3) comprises a secondary cutting edge portion (332) and a main cutting edge portion (331) extending at an angle thereto in the direction of a plate center.

11. Use of a cutting insert (1, 1') according to one of claims 8 to 10 for peeling, in particular for a method for peeling according to at least one of claims 1 to 6.

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