WO2014190363A1 - Cutting insert made of hard metal or cermet for rotary machining - Google Patents

Abstract

The invention relates to a cutting insert (1) made of hard metal or cermet for rotary machining long-chipping materials, comprising an upper face (3) which is designed as the rake face (11) and which is made of hard metal or cermet, said upper face being provided with at least one chip-influencing structure (9); a lower face (2); at least one lateral surface (4) which extends from the upper face (3) in the direction of the lower face (2); and at least one cutting edge (5) formed between the upper face (3) and the at least one lateral surface (4). A chip breaker (10) is provided which projects out of the rake face (11) and is surrounded by the rake face (11), said chip breaker projecting over the height (h_1) of the cutting edge (5) by at least 0.5 mm.

Description

 CUTTING INSERT OF HARDMETAL OR CERMET

 FOR TURNING

The present invention relates to a cutting insert made of hard metal or cermet for turning long-chipping materials.

It is known to use cutting tools, which have a holder which is equipped with at least one interchangeable cutting insert, in a turning operation, in particular of metallic materials. Of the

interchangeable cutting insert forms the part of the

 Cutting tool, which is intended to engage with the

to get machined workpiece. The holder of the cutting tool is typically made of a tough material, in particular e.g. Tool steel, and the replaceable cutting insert may e.g. typically formed of a hard metal or cermet.

In particular, in the machining of long-chipping materials, such. Of very soft aluminum or aluminum-based alloys, the generated chips of the material flow depending on the respective processing conditions, in particular the depth of cut and the

 Vorschubgeschwtndigkeit often not to the extent desired and / or are not sufficiently broken in order to reliably prevent damage to the generated workpiece surface by the chips under all machining conditions can. Known cutting inserts for the

Processing such long-chipping materials are therefore often only suitable for either a machining with large depths of cut or small depths of cut or either high feed rates or low

Feed speeds. EP 0 257 004 A describes a cutting insert for turning for

Separating and grooving, in addition to chip-forming structures in

Immediately adjacent to a circular cutting edge and a greatly elevated shoulder is provided, which extends in a region between the actual rake face and a holding portion in which the

Cutting insert is mounted in a holder. The shoulder extends over the entire width of the cutting insert and forms the highest portion of the cutting insert relative to a reference plane that is substantially parallel to a lower bearing surface of the cutting insert. The shoulder is intended to form chips at low feed rates, which are formed by the chip-forming structures in the vicinity of the

The cutting edge can not be deformed sufficiently.

It is an object of the present invention to provide an improved carbide or cermet cutting insert for the machining of long chipping materials that allows a wide range of feed rates and depths of cut for different orientations of the cutting insert relative to the workpiece to be machined.

The object is achieved by a cutting insert made of hard metal or cermet for the turning of long-chipping materials according to claim 1.

 Advantageous developments are specified in the dependent claims.

The cutting insert has: a top face of hard metal or cermet, which is designed as a rake surface and is provided with at least one chip-influencing structure; a bottom; at least one side face extending from the

Extends upper side toward the bottom; and at least one formed between the top and the at least one side surface

Cutting edge. It is a protruding from the rake surface of the

Span surface surrounded chipbreaker provided which protrudes by at least 0.5 mm above the height of the cutting edge protrudes.

In the present context, the height of the cutting edge is defined by the height of the cutting edge relative to a reference plane which is determined by the main extension plane of a bearing surface of the cutting insert. The height of the cutting edge is to be determined in the point of the cutting edge, which is farthest from a central axis. The

Central axis runs perpendicular to the reference plane. Due to the greatly increased chip breaker short broken chips can be generated especially at low feeds and / or small depths. For larger feeds and / or larger cutting depths, the resulting chips are reshaped and / or broken by the chip-influencing structure of the rake face. It is thus achieved over a wide range of different processing conditions a good chip control. Since the chip breaker is surrounded by the chip surface, the chip breaker acts on accumulating chips, which can hit the chip breaker from different directions, so that an advantageous chip control for various

Alignments of the cutting insert relative to the machined

Workpiece is provided. In this way, in each case an advantageous chip control is achieved for a variety of possible conditions of use. According to a development, the cutting edge extends over a

 Circumference of more than 200 ° around the chipbreaker. The cutting edge may preferably extend more than 250 ° around the chip breaker. The cutting edge thus extends relatively far behind the chip breaker. In this way, the cutting insert enables advantageous turning of a workpiece to be machined with different orientations of the cutting insert to the workpiece surface to be machined.

Preferably, the chip breaker may be formed of the same material as the rake face and the cutting edge. In this case, a particularly simple and cost-effective production of the cutting insert is possible.

According to one embodiment, the chipbreaker is common

Compacting and sintering in a powder metallurgy manufacturing process integrally formed with the rake face. In this case, a particularly cost-efficient production of the cutting insert is possible in a method that is commonly used in the industrial production of cutting inserts. _Λ

 4

 According to another embodiment, the chip breaker is formed as a separate component, which by soldering or welding to the

Cutting insert is connected. Also in this case, the material of the chip breaker can be equal to the material of the rake face and the cutting edge. However, it is also possible in this case to form the chipbreaker from a different material. Furthermore, in this case, the chipbreaker can also be subsequently introduced into a conventional cutting insert.

According to a further development, the chip breaker has a shape which tapers with increasing distance from the rake face. In this case, chippings coming onto the chipbreaker can be reliably deflected and / or broken in the desired direction. The chipbreaker may be e.g. have an approximately conical or pyramidal shape, these terms are not limited to the exact mathematical-geometric meaning to understand.

According to a development, at least the clamping surface and the

Cutting edge provided with a wear-resistant coating. The coating can be formed in a manner known per se by a PVD process (physical vapor deposition) and / or CVD processes (chemical vapor deposition). The wear-resistant coating can have one or more known hard material layers, such as

in particular TiN, TiCN, TiCNO, ΤΊΑΙ, Al ₂ 0 ₃ , TiB ₂ , or more. By providing the wear-resistant coating, the possible

Useful life of the cutting insert can be significantly increased. Preferably, the chip breaker can also be provided with a wear-resistant coating.

According to one implementation, the cutting edge in plan view over more than 180 °, preferably more than 210 °, a circular arc-shaped course.

According to another embodiment, the cutting edge in plan view a V-shaped course with a rounded cutting edge. _

 5

 Further advantages and advantages of the invention will become apparent from the following description of exemplary embodiments with reference to the accompanying figures. From the figures show:

1 shows a perspective view of a cutting insert according to a first embodiment;

Fig. 2: a plan view of the cutting insert according to the first

 embodiment;

 Fig. 3 is a schematic sectional view taken along the line III-III

 in Fig. 2;

 4 shows a schematic sectional view along the line IV-IV

 in Fig. 2;

5 is a perspective view of a cutting insert according to a second embodiment;

Fig. 6: a plan view of the cutting insert according to the second

 embodiment;

 Fig. 7 is a schematic sectional view taken along the line VII-VII in Fig. 6; and

 8 shows a schematic sectional view along the line VIII-VIII in FIG. 6.

FIRST EMBODIMENT

A first embodiment will be described with reference to FIGS. 1 to 4

described.

The cutting insert 1 according to the first embodiment is formed as a carbide cutting insert, which is in a powder metallurgy

 Manufacturing process by pressing and sintering of powdered

Starting material is made. The cutting insert 1 is for the

Turning long-chipping materials, such as in particular relatively soft aluminum alloys designed. The cutting insert 1 according to the first embodiment has a plan view of a substantially diamond-shaped basic shape with rounded corners. In the illustrated embodiment, the rounded acute-angled corners of the rhombus have an interior angle of about 35 ° and the obtuse corners an interior angle of about 145 °. However, the design is not limited to these specific angles and the acute angles may also have a smaller angle, eg of 30 °, 25 °, etc., or a larger angle, eg of 40 °, 45 °, etc. The embodiment is also not limited to the specific example of a diamond-shaped cutting insert 1, but the cutting insert may, for example, also have a substantially triangular or quadrangular basic shape, if necessary. With rounded or bevelled corners. The cutting insert 1 has a bottom 2, which serves as a support surface for a

Attachment is formed in a tool holder, and one as

Span surface 11 formed top 3 on. The top 3 and the

Bottom 2 are connected via a plurality of side surfaces 4. At the intersection between the top 3 and the side surfaces 4 is a

Cutting edge 5 is formed. The extending below the cutting edge 5 areas of the side surfaces 4 are formed as open spaces. The serving as a support bottom 2 extends along one

Reference plane R. Although in the first embodiment, a

is completely flat bottom 2 is shown, it is also possible, for example, that the bottom 2 is provided with deviating from a straight surface structures. A central axis Z of the cutting insert 1 extends perpendicular to the reference plane R. As can be seen in FIGS. 3 and 4, the underside 2 has a smaller circumference than the top 3, so that the side surfaces 4 formed as free surfaces have a positive Have clearance angle. In this case, the term clearance angle refers to a cutting insert-specific clearance angle, which is determined by the geometry of the cutting insert 1 itself. It should be noted that the resulting effective clearance angle when using the cutting insert 1 is additionally determined by the relative orientation of the cutting insert 1 relative to the workpiece surface. The cutting insert 1 according to the first embodiment is provided with a central fixing hole 6 through which a threaded portion of a fixing screw (not shown) can be guided to feed the cutting insert 1 to a tool holder of a turning tool

Fasten.

The configuration of the cutting edge 5 and the upper side 3 will be described in more detail below with reference to the lower half of the cutting insert 1 in FIG. Although in the illustrated embodiment, the upper half in Fig. 2 has a slightly different configuration, this upper half may preferably be formed identical to the lower half, so that the cutting insert 1 may preferably have a 2-fold rotational symmetry with respect to the central axis Z. Also in the illustrated

In the exemplary embodiment, the cutting insert 1 has at least approximately a 2-fold rotational symmetry with respect to the central axis Z.

Since the embodiment of the upper half of the cutting insert 1 in FIG. 2 is of secondary importance in the present case, only the lower half of the cutting insert 1 described in FIG. 2 will be described in more detail below.

As can be seen in FIGS. 1 and 2, the cutting edge 5 has a

Cutting corner 7, in which the cutting edge 5 is provided with an arcuate course, which may be formed in particular a circular arc. On both sides of the cutting corner 7, partial cutting edges 8 adjoin. In the illustrated embodiment, the partial cutting edges 8 are each formed substantially straight in plan view. At the cutting corner 7, in the region of the cutting edge 5 furthest from the central axis Z, the cutting edge 5 has a height h_1 relative to the reference plane R, as can be seen in FIG.

Adjacent to the cutting edge 5, the upper side 3 is formed such that it first approximates with increasing distance from the cutting edge 5 of the reference plane R, as can be seen in particular in FIGS. 1 and 4. The top 3 is further provided with a plurality of provided chip-influencing structures 9, which are used in particular at relatively high feeds and / or large depths in the turning processing to redirect the chips and / or to break. The

Spanbeeinflussenden structures 9 are by depressions and / or

Elevations formed in the top 3, which are all at a height level, which has a smaller distance from the reference plane R than the previously described height of the cutting edge h.

It is also a chip breaker 10 is provided, which on all sides of the

Span surface 1 1 is surrounded and strongly protrudes upwards from this. The chip breaker 10 is formed greatly increased and extends to a height h_2, which is a height difference Ah on the height h_1 of

Cutting edge 5 goes out. The height difference Ah is at least 0.5 mm. The chip breaker 10 is made in the illustrated embodiment in one piece with the rake face 1 and the cutting edge 5 of the same material.

As can be seen in Figs. 1 and 2, the extend

Partial cutting edges 8 - viewed from the cutting corner 7 of - until further behind the greatly increased chip breaker 10. In this case, the cutting edge 5 a

V-shaped course with a formed by the cutting corner 7 rounded corner. In the exemplary embodiment illustrated in FIGS. 1 to 4, the partial cutting edges 8 of the cutting edge 5 extend over one

Peripheral range of more than 250 ° around the chip breaker 10th

The chip breaker 10 is designed such that it is with

increasing distance from the surrounding rake face 1 1, i. also increasing distance from the reference plane R, tapered. Of the

Chip breaker 10 thus has the respective sections of the cutting edge 5 each facing a bevelled shape. In the illustrated

Embodiment, the chip breaker 10 while at least approximately the shape of a truncated cone. As can be seen in particular in FIG. 4, the upper side 3 initially drops in a direction from the cutting corner 7 to the central axis Z in the direction of the reference plane R and also remains below the level of the cutting edge 5 in the area of the chip-influencing structures 9. The chip breaker 10 then forms a strong increase over the level h_1 of the cutting edge 5. Behind the chip breaker 10, the top 3 then runs on one again

Height level below the level h_1.

In the exemplary embodiment, the cutting insert 1 can preferably be provided with a wear-resistant coating covering at least the region of the cutting edge 5, the rake face 11 and the chip breaker 10.

Due to the combination of the chip-influencing structures 9 on the one hand, in particular at larger depths of cut and higher feeds the

Forming chips in the desired manner, with the greatly increased chip breaker 10 on the other hand, which forms advantageous especially at small depths of cut and low feeds long chips, the cutting insert 1 allows a wide range of different

Machining conditions when turning long-chipping

Materials.

SECOND EMBODIMENT A second embodiment will be described below with reference to FIGS. 5 to 8.

Also, the cutting insert 101 according to the second embodiment is manufactured in a powder metallurgical manufacturing process by pressing and sintering powdery raw material. The cutting insert 101 is designed for the turning of long-chipping materials, such as in particular relatively soft aluminum alloys. The cutting insert 101 is made of hard metal in the embodiment shown. ₁

However, unlike the cutting insert 1 according to the first embodiment described above, the cutting insert 101 according to the second embodiment is approximately bone-shaped in plan view

Cutting insert formed.

The cutting insert 101 has a clamping surface 111 formed as

Top 103 and formed as a support surface underside 102. In contrast to the first embodiment, however, the underside 102 is not flat, but has an approximately roof-shaped elongated recess, which in the concretely illustrated embodiment further with

 Cross ribs is provided, as can be seen in Fig. 8. The cutting insert 01 has a central axis Z, which extends perpendicular to a reference plane R, which is determined by the main extension plane of the bottom 102. Although the cutting insert 101 in the illustrated embodiment has the elongated recess and the transverse ribs, it is e.g. also possible to provide only the elongated recess or form the cutting insert with a flat base. Furthermore, the underside formed as a support surface 102 may also have other structures or shapes. There is a plurality of side surfaces 04 which extend between the bottom 102 and the top 103. In contrast to the first embodiment, the cutting insert 101 according to the second

Embodiment two in plan view substantially circular

Cutting edges 105, between which at the top 103 a

Holding portion 112 extends, which serves to attach the cutting insert 101 to a tool holder. In the case of the embodiment shown concretely in FIGS. 5 to 8, it is true that the latter differs

Embodiment of the upper side 03 in the upper half of Fig. 6 from the configuration of the upper side 103 in the lower half of Fig. 6, it is e.g. but readily possible, the top 103 in the upper half of Fig. 6 identical to the lower half of Fig. 6 described in more detail below form. Such a symmetrical design in which the

Cutting insert 101 a 2-fold rotational symmetry with respect to

Central axis Z is even preferred. Also in the illustrated Embodiment, the cutting insert 101 but at least approximately 2-fold rotational symmetry with respect to the central axis Z on. Because the

deviating design in the upper half of Fig. 6 present

is incidental, the following description is limited to the lower part of the cutting insert 101 in FIG.

The areas of the side surfaces 104 adjoining the cutting edges 105 are also formed as free surfaces in the second embodiment, which extend at a positive clearance angle. In this case too, the cutting insert-specific clearance angle is again referred to as clearance angle, the actual effective clearance angle during the turning process being determined by the orientation of the cutting insert 101 used relative to the workpiece surface to be machined. As can be seen in particular in FIG. 8, the cutting edge 105 in a region farthest from the central axis Z has a height h_1 relative to the reference plane R. As can be seen in Fig. 6, the runs

Cutting edge 05 in plan view over a large angular range of more than 180 ° at least substantially circular.

In the region immediately adjacent to the cutting edge 105, the upper side 103 formed as a rake surface 111 initially approaches the reference plane R, as can be seen in FIGS. 7 and 8. The rake surface 111 is further provided with a plurality of chip-influencing structures 109, which serve, in particular at relatively high feeds and / or large cutting depths during turning, to redirect and / or break the resulting chips. The chip-influencing structures 109 are formed by depressions and / or elevations in the upper side 103, all of which are at a height level which is closer to the reference plane R than the previously described height

Cutting edge h_11.

It is also a chip breaker 110 is provided, which on all sides of the

Span surface 111 is surrounded and protrudes strongly upwards from this. Of the ^

Chip breaker 110 is formed greatly increased and extends to a height h_12, which is a height difference Ah over the height h_11 of

Cutting edge 105 goes out. The height difference Ah is at least 0.5 mm. The chip breaker 0 is also in the illustrated second

Embodiment in one piece with the clamping surface 111 and the

Cutting edge 105 made of the same material.

As can be seen in FIGS. 5 and 6, the cutting edge 105 extends from the area furthest away from the central axis Z to behind the greatly elevated chip breaker 110. In the case of the embodiment shown in FIGS. 5 to 6 In the second embodiment shown, the cutting edge 105 extends over a circumferential region of more than 200 ° about the chip breaker 110. The chip breaker 110 is also formed in the second embodiment so that it increases with increasing distance from the surrounding rake face 111, ie also increasing distance from the reference plane R, tapered. The chip breaker 110 thus has a respective beveled shape facing the respective sections of the cutting edge 5. In the illustrated second embodiment, the chip breaker 0 has at least approximately the shape of a truncated cone.

As can be seen in particular in Fig. 8, the top 103 of the falls

Cutting insert 101 in a direction from the cutting edge 05 to the central axis Z initially in the direction of the reference plane R down. Of the

Chip breaker 110 then forms a sharp increase above the level h_11 of the cutting edge 105. Behind the chip breaker 110, the top 103 then again runs at a height level below the level h_11. Also in the second embodiment, the cutting insert 101 is preferably provided with a wear-resistant coating which covers at least the region of the cutting edge 105, the rake face 111 and the chip breaker 110. 1

 MODIFICATIONS

Although implementations have been described with respect to each of the above-described embodiments in which the chip breaker 10 and 110 are formed integrally and made of the same material as the rest of the cutting insert 1 and 101, respectively, according to a modification, e.g. It is also possible to provide the chipbreaker as a separate element, which may preferably be materially bonded (e.g., by soldering or welding) to the remainder of the cutting insert. In this case, the chip breaker may e.g. also be formed of a different material than the rest of the cutting insert.

Although specific chip-influencing structures 9 and 109 are shown with respect to the embodiments, a variety of other configurations of the chip-influencing structures are possible. The chip-influencing

 However, in each case structures form relatively weak height variations of the upper side in comparison to the very high chipbreaker. In this case, the chip-influencing structures preferably extend in each case below the level h 1 or h 11 of the cutting edge.

Claims

claims Cutting insert (1; 100) made of carbide or cermet for the  Turning of long-chipping materials, with an upper side (3, 103) formed as a rake face (11; 111) Carbide or cermet, with at least one chip-influencing Structure (9; 109) is provided a bottom (2, 102), at least one side surface (4; 104) extending from the upper side (3; 103) in the direction of the lower side (2; 102), and at least one cutting edge (5; 105) formed between the upper side (3; 103) and the at least one side surface (4; 104); wherein one of the rake face (11, 111) protruding from the Chip surface (11, 111) surrounded chip breaker (10, 110) is provided, which increases by at least 0.5 mm above the height (h_1, h_11) of Cutting edge (5; 105) protrudes. The cutting insert according to claim 1, wherein the cutting edge (5; 105) extends over a peripheral area of more than 200 °, preferably more than 250 °, around the chip breaker (10; 110). A cutting insert according to claim 1 or 2, wherein the chip breaker (10; 110) is made of the same material as the rake surface (11; 111) and the Cutting edge (5; 105) is formed. A cutting insert according to any one of the preceding claims, wherein the chip breaker (10; 110) is formed integrally with the rake face (11; 111) by co-compacting and sintering in a powder metallurgy manufacturing process. Cutting insert according to one of claims 1 to 3, wherein the Chip breaker (10; 110) is formed as a separate component, which is connected by soldering or welding to the cutting insert (1; 100). 6. Cutting insert according to one of the preceding claims, wherein the chip breaker (10; 110) has a tapering with increasing distance from the rake face (11; 11). 7. Cutting insert according to one of the preceding claims, wherein the chip breaker (10; 110) has a conical or pyramidal shape. 8. Cutting insert according to one of the preceding claims, wherein at least the rake face (11; 111) and the cutting edge (5; 105) are provided with a wear-resistant coating. 9. Cutting insert according to one of the preceding claims, wherein the chip breaker (10; 110) is provided with a wear-resistant coating. 0. Cutting insert according to one of the preceding claims, wherein the cutting edge (105) in plan view over more than 180 °, preferably more than 210 °, a circular arc-shaped course. 11. Cutting insert according to one of the preceding claims, wherein the cutting edge (5) in plan view has a V-shaped course with a rounded cutting edge (7).