EP0954400A1

EP0954400A1 - Coated cutting insert or cutting insert blank and method for producing coated cutting inserts for chip-removal of metal

Info

Publication number: EP0954400A1
Application number: EP97953666A
Authority: EP
Inventors: Udo KÖNIG; Hartmut Westphal; Wolfgang Hintze
Original assignee: Widia GmbH
Current assignee: Widia GmbH
Priority date: 1996-12-30
Filing date: 1997-12-20
Publication date: 1999-11-10
Also published as: WO1998029211A1; DE29724599U1

Abstract

The invention relates to a coated cutting insert or cutting insert blank for coating in a gas phase, having a first face and a second face parallel to said first face. The invention further relates to a method for producing coated cutting inserts for chip-removal of metal without a fixing hole. According to the invention the cutting insert blank is made by stamping and has a break-through opening extending from the first face to the second face, whereby the cross-sectional profile of the opening is at least partly noncircular or at least partly circular and said opening is used after sintering to thread the cutting insert during both pre-cleaning and coating.

Description

description

Coated cutting insert or blank insert and method for producing coated cutting inserts for machining

The invention relates to a coated cutting insert or cutting insert blank for coating from a gas phase with a rake face and a parallel support surface. The invention further relates to a method for the production of coated cutting inserts for machining without a fastening hole.

Basically, cutting inserts are fastened either in a holder by means of a clamping screw that passes through a central fastening hole with an upper countersink, or by means of a clamping claw. Furthermore, center hole plates can be tensioned via an eccentric or a toggle lever. The subject of the present application are cutting inserts or cutting insert blanks which are held by means of a clamping claw or a clamping arm or the like and accordingly have no central central fastening hole. The coating, in particular the PCVD or the PVD coating of such cutting inserts usually requires preparatory work, such as pre-cleaning either by sand or wet blasting treatment and finally the coating. In order to be able to pre-clean the relevant cutting inserts on all sides and in particular to coat them as uniformly as possible, it is essential to hold these cutting inserts or cutting insert blanks. Insofar as the substances in question can be magnetized, a holder by means of magnets which are intended to attack at less critical points may be used, otherwise the cutting inserts in question must be placed on grates with as punctiform contact as possible, unless they are additionally used in facilities for pre-cleaning, such as for PVD - Coating must be held in order to term processing, if necessary, with rotations of the workpiece, without the body evading any treatment pressure (such as sand or wet blasting).

It is an object of the present invention to provide a cutting insert or cutting insert blank of the type mentioned at the outset, in which the relevant pre-cleaning and coating work is facilitated by an adequate mounting option for the body in question. However, this support should be designed so that the clamping in a clamping claw or in a clamping finger is not deteriorated. This means that any gill troughs adapted to the clamping finger or the like should still be present or realizable on the rake face as well as the rake face geometries normally used.

This object is achieved by the cutting insert or cutting insert blank according to claim 1, which is characterized in accordance with the invention in that it has an opening which runs continuously from the rake face to the support surface, the cross-sectional profile of which is at least partially non-circular or at least partially circular, and the largest possible inscribed circle is one Has a diameter which is either <0.2 x IC or <1.5 mm, preferably <1 mm or has a diameter which is> 0.65 IC, preferably> 0.75 IC or> 13.5 mm, preferably > 15 mm, where IC denotes the inner circle diameter.

Unlike in the case of center hole plates known in the prior art, the center hole diameter of which is dimensioned according to the diameter of the clamping screw, the openings in question are selected either considerably smaller or significantly larger according to the present invention, in the latter case the recess in question by a precisely fitting insert is closed, which will be discussed later. In the case of a single opening of the cutting insert which is circular in cross section, this opening lies centrally or centrally with respect to the rake face, but in such a way that due to its small size the clamping is not impaired by the system of the clamping finger and the gill trough. For example, the opening can be located in the center of a gill trough, which is not required when the tool (cutting insert) is clamped or is not acted upon by the clamping finger. According to a further embodiment of the invention, the opening can also have non-round cross-sectional shapes, which has the advantage that it provides possibilities for centering and positioning the cutting insert both during the pre-cleaning, the sintering and the coating, and later when aligning in the holder. Any cross-sectional shape that allows, even if only partially, such alignment or indexing is to be understood as non-circular in the sense of the present invention. The cross-sectional profile can thus be geometrically regular, that is to say star-shaped, oval, elongated round or polygonal (polygonal, in particular octagonal) or, with the exception of a groove or a rib or other rotary indexing, round. In the case of non-round cross-sectional profiles, the diameter is preferably <0.2 × IC, which the largest circle that can be inscribed in the cross-sectional profile has.

Rotary indexing options can also be created by providing two small-diameter openings instead of just a single opening. Apart from any possible rotations, which may still be possible with two circular openings, the cross-section of the opening is no longer important with regard to the desired rotary indexing.

Regardless of the shape and size of the opening in question of the cutting insert or cutting insert blank, the possibility of fixing the cutting insert or cutting insert blank in pretreatments and created during coating, as is generally used for perforated plates. The openings in question are accordingly used in the same way for threading or plugging. This eliminates the otherwise necessary magnetic brackets, the use of complicated conditions, possible wiring of the cutting inserts in question, in part with the procedural disadvantage that the cutting inserts in question have to be subjected to multiple coating processes in order to finally coat the areas that were previously used as points of contact or contact have served.

If you choose an opening that is larger than 0.65 x IC in cross-section or the largest diameter, or an out-of-round opening, there is still the possibility of arranging a precisely fitting insert made of another material after the pretreatment and coating in this opening, which is particularly useful for threading "Hole" used during coating is closed again. This is preferably done in such a way that a material with a better thermal conductivity than that of the cutting insert material is used.

It is known that hard metals, for example, have a thermal conductivity of less than 1 W / (cm × K). Furthermore, it is known that during cutting work on the cutting edge considerable temperatures occur, which are only dissipated to a small extent according to the prior art, so that even when using the cutting insert for the first time in a cutting operation, it cannot be ruled out that the heat generated during the cutting can be ruled out the cutting edges that are not used are impaired by changes in the temperature of the material structure in such a way that they have significantly shorter service lives or wear properties. If one now makes use of the breakthrough which is advantageously helpful in the case of pre-cleaning and coating, in that an insert with greater thermal conductivity is arranged therein, the heat generated in the cutting insert can be correspondingly better, in particular via the contact surface, but also via the clamping arm in the holder. The only requirement for this is a surface contact of the insert with the wall of the opening. The dissipation of heat via this insert into the clamping arm or clamping finger and into the support of the holder can be influenced by a suitable choice of material for the holder and in particular by the material of the insert, which is made of a metal or a metal alloy with good thermal properties, preferably aluminum, Copper, an aluminum or copper alloy or a low alloy steel.

According to a further embodiment of the invention, the insert and the opening have an outer dimension that is substantially similar to the outer contour of the cutting insert, preferably the opening top edge and the outer edge of the insert are arranged parallel to the cutting edges delimiting the rake face. Apart from the better heat dissipation that can be achieved, the cutting insert with "inner" insert has the further advantage that less expensive material can be used for the insert. The cutting insert itself consists of a coated substrate material. The extent of the insert, which is accommodated in the opening of the cutting insert, is practically only limited by the required stability of the cutting insert. In other words, the thickness of the cutting insert from the outer edge or the free surface to the edge of the opening must still be sufficiently stable against cracking.

As already mentioned at the beginning, it is not necessary to achieve the object of the present invention that the opening has the same cross section over its entire length. In particular, in the context of the present invention, the opening in cutting inserts with free surfaces can taper conically or stepwise towards the contact surface at a positive clearance angle. In the context of the present invention, it is also possible to make the opening circular for the most part and to impress a different type of rotation-indexable shape only over a partial area, which can be octagonal, star-shaped, but also rotationally asymmetrical, for example.

According to the invention, the cutting insert can consist of a composite body which has a substrate body and a single-layer or multilayer layer deposited thereon. Cermets, hard metals or ceramics can be used as substrate body material. The coatings known from the prior art can be used as coatings, such as hard materials, preferably carbides, nitrides and / or carbonitrides of the metals of the IVa to Vla metals of the periodic table, AI2O ₃ and / or Zr0 ₂ , BN, diamond-like Layers, amorphous carbon layers, both as a single layer and as a multiple layer with different of the aforementioned substances.

According to the invention, in the production of coated cutting inserts (without a fastening hole) for machining, a cutting insert blank is produced by pressing, which has an opening that runs from the rake face to the support surface and whose cross-sectional profile is at least partially non-round or at least partially circular with a diameter that is either < 0.2 x IC or <1.5 mm, preferably <1 mm or which has a diameter which is> 0.65 IC, preferably> 0.75 IC or> 13.5 mm, preferably> 15 mm, wherein IC is the inner circle diameter. This opening is used after sintering to thread the cutting insert both for pre-cleaning and for holding during coating. The procedure outlined creates the advantage that the holding of the cutting inserts during the pre-cleaning and the coatings can be simplified and therefore cheaper. In addition, the possibility is created to improve the cleaning or the coating itself or to avoid multiple coating passes. The benefits outlined arise to a particular degree in coating processes with directional deposition or in low-temperature coating processes, such as, for example, the PVD process.

Further exemplary embodiments are shown in the figures. Show it

Fig. 1 is a plan view of a clamp holder with a

Cutting insert,

Fig. 2 is a plan view of a cutting insert

Fig. 1

3 to 6 a section along the line A - A after

2 in different versions,

7a to p alternative embodiments of a cutting insert according to the present invention, each in a sectional view and a plan view,

8a to f are top views of cutting inserts each with at least 2 openings and

9a to f are top views of cutting inserts with a central but non-circular opening,

Fig. 10a, b is a side view and a plan view of a square cutting insert with a substantially trefoil-shaped opening and

11a, b each show a square cutting insert with a larger opening in a side view and a top view, respectively in FIGS. 10 and 11 the largest possible inscribed circles are shown.

1 shows a clamp holder 8 with a clamp claw 9 provided in a manner known from the prior art, by means of which a square indexable insert 10 is held.

The invention can be implemented without exception in any cutting insert shapes known in the prior art.

2 to 7 each show a cutting plate with a square rake face. A common feature of the cutting inserts 10 is that they have a rake face 11, which can optionally be provided with elevations and / or depressions, chamfers etc., and a bearing surface 12. The rake face 11 and the bearing surface 12 are substantially parallel, which is not a mandatory requirement. Likewise, the cutting inserts can be designed as multi-use indexable inserts, in which both the rake face 11 and the support surface 12 are designed identically, so that after the turning, the support surface can be used as a rake face. The rake face 11 is delimited by cutting edges 17, which also represent the boundary line to open areas 13 and 14, respectively.

The cutting insert 10 has a relatively large opening in which an insert 15 is arranged, the surface of which, for example, is flush with the rake face 11 surrounding it and also adjoins it. Alternatively, it can also protrude from the surrounding rake face. The same applies to the wall of the opening and to the outer jacket of the insert 15. In the present case, the boundary line roughly follows the course of the cutting edge 17, the free surface 13, 14 additionally being inclined at a positive clearance angle. Depending on the inclination of the clearance angle, the cutting insert 10 can have a step 18; in a corresponding manner, the insert 15 has a reset paragraph. The insert 15 can as shown in FIG. 6, be cuboid or additionally (see FIG. 3) with an upper chamfer 19. The thermally conductive insert 15 can consist, for example, of aluminum or copper, the thermal conductivities of 2.37 W / (cm x K) or 3.98 W / (cm x K), that is to say substantially greater thermal conductivities than the hard metal used with 0.88 W. / (cm x K). The thermal conductivity of the insert 15, on which both the clamping claw 9 rests, and thus also the cutting insert support of the holder 8 comes into contact with it, ensure that heat generated during the machining can be dissipated, as a result of which the wear of the cutting plate 10 is reduced and the service life is extended .

The cross-sectional shape of the insert 15 does not necessarily have to follow the course of the cutting edges in the outer contours; equally, in plan view or in cross section, circular, rectangular, hexagonal, oval or other shaped inserts 15 are possible, which are suitable for heat in the clamping claw or the contact surface of the holder. Irrespective of this, the material of the insert 15 can be selected in particular with a view to minimizing the material costs, i.e. this can be a material that fulfills its placeholder function for machining.

If desired, it is of course also possible within the scope of the present invention to also provide the insert 22 with a central bore 23 (FIG. 5). This should be considered in particular if the cutting insert 10 is already connected to the insert 15 before sintering or coating.

While FIGS. 1 to 6 all show cutting inserts with relatively large openings, the cutting inserts shown in FIGS. 7 to 9 are each provided with openings of only a small diameter. The opening 16 of the cutting insert 10 shown in FIGS. 7a, b is in cross section circular and has a diameter that is <0.2 x IC. In the area of the roof and floor area, the recess in question can end with a chamfer.

The embodiment according to FIGS. 7c, d differs from the one described above by a groove-shaped additional recess 25, which allows rotary indexing. The groove 25 extends over the entire cutting insert height.

In the embodiment according to FIGS. 7e and f, four trough-shaped depressions 26 are provided for rotary indexing only on the rake face 11 and are distributed like a cloverleaf around the central hole 26.

The embodiment shown in FIGS. 7g and h has a central opening which is cross-shaped in cross section. The cross-shaped cross-section in question is kept constant over the entire height of the cutting insert.

In order to create a better point of attack for a curved dome of the clamping claw 9 of the holder 8, the cutting insert 20 can have a clamping trough 21 in the case shown in FIGS. 7i to 9. The openings, which have been described in relation to FIGS. 7a to h, are provided centrally in the gill trough, possibly also decentrally.

The embodiments according to FIGS. 8a to f differ from the ones described above in that at least two openings are provided in each case. In the case of FIG. 8 a, in a cutting insert 30 which is triangular in plan view, these are three openings 28 which are equidistant from the cutting edge and which are each circular and have a diameter of less than 0.2 × IC. The cutting insert 20 according to FIG. 8b has recesses 29 which are elongated in cross section and are mirror-symmetrical to a surface diagonal. The diamond-shaped cutting insert 31 according to FIG. 8c has circular openings 32 in cross section in the region of the obtuse-angled cutting corners, which are symmetrical to the longer diagonal. An embodiment with four openings 33 is realized on the square cutting insert 20 according to FIG. 8d, each of which lies mirror-symmetrically on the two diagonals.

The diamond-shaped cutting insert 31 according to FIG. 8e likewise has two openings with a circular cross section, which, however, in contrast to the embodiment according to FIG. 8c, are arranged on the longer diagonal. In the cutting insert, which is square in plan view according to FIG. 8f, only two openings 35 with a circular cross-section are provided, which lie asymmetrically on one half.

8 shows further design variants of the cutting insert types 30, 20, 31 shown in FIGS. 8a to f. In the embodiments there, only one central opening is used, which is triangular in cross section, following the edge profile (see number 36), square (37), diamond-shaped (38), oval (39) lenticular with two tips (40) or essentially circular (41) with a flattened area 42. In the case of FIGS. 9a, b and c, the outer cutting edge course is essentially followed.

The small cross-sectional openings have advantages in particular in the mechanical pretreatment of cutting insert blanks and in a final coating, since they can be easily threaded using these openings. The openings still have advantages during the sintering. Because of the additional outer surface created in the area of the bore, the cutting insert can be better "degassed" during sintering and thus compressed. This improves the structure quality and thus the cutting properties. Centrally arranged openings 16, 25, 26, 27 and 36 to 41 are expedient in the case of clamps acting eccentrically on the rake face or in clamp constructions in which the rake face represents the reference contact face to the carrier body. The outer central arrangement of the openings 28 to 35 is particularly advantageous in the case of clamping finger constructions which act from above (on the rake face) if their pressure point lies in the central region of the indexable insert. To avoid possible harmful edge wear on the edge of the opening in the case of central openings and clamps acting centrally on the rake face, the rake surface around the opening can be designed to be slightly concave. Alternatively, the edge of the opening can be chamfered.

FIG. 10 shows a cutting insert which is essentially square in plan view and which shows an opening 27 in a cloverleaf or cross shape analogous to the illustrations in FIG. 7h. The largest possible inscribed circle 43 can be seen from this illustration.

In the embodiment according to FIG. 11, the opening 44 is made significantly larger with the largest possible inscribed circle 45. The opening 46 in question differs from the circular shape by four recesses, each offset by 90 ° and extending over the entire height of the cutting insert, the additional recesses 47 being designed in the form of a lobe in cross section, so that there is approximately a recess 46 with a rectangular cross section results.

Claims

claims

1. Coated cutting insert or cutting insert blank for coating from a gas phase with a rake face and a substantially parallel contact surface, characterized in that the cutting insert (10, 20, 30, 31) or cutting insert blank one from the rake face (11) to the contact surface (12 ) has continuous opening (16; 25 to 29; 32 to 41), the cross-sectional profile of which is at least partially non-circular or at least partially circular and wherein the largest possible inscribed circle (43, 45) has a diameter which is either <0.2 x IC or <1.5 mm, preferably <1 mm or which has a diameter which is> 0.65 IC, preferably> 0.75 IC or> 13.5 mm, preferably> 15 mm, where IC is the inner circle diameter (22 ) is.

2. Cutting insert or cutting insert blank according to claim 1, characterized in that the non-circular cross-sectional profile of the opening is star-shaped, oval, elongated round or polygonal (polygonal) or is round with the exception of a groove or rib or other rotary indexing.

3. Cutting insert or cutting insert blank according to claim 1 or 2, characterized by several adjacent openings smaller diameter or smaller largest diameter, which is <0.2 IC in each case.

4. Cutting insert or cutting insert blank according to claim 1 or 2, characterized by a cross-section or the largest diameter 0.65 x IC exceeding or non-circular opening (16), in which a precisely fitting insert (15) is arranged from a different material, preferably from a material with better thermal conductivity than the cutting insert material.

5. Cutting insert or cutting insert blank according to claim 4, characterized in that the insert (15) consists of Al, Cu, Al or Cu alloys or steel.

6. Cutting insert or cutting insert blank according to claim 4 or 5, characterized in that the insert (15) and the opening has an outer contour of the cutting insert (10) substantially similar external dimension, preferably in each case arranged parallel to the cutting edges delimiting the rake face (11) .

7. Cutting insert or cutting insert blank according to one of claims 1 to 6, characterized in that the opening (16) viewed across its height has different cross-sectional profile dimensions, in particular in the case of cutting inserts (10) with free surfaces (13, 14) at a positive clearance angle, conical or gradually tapered towards the support surface (12).

8. Cutting insert or cutting insert blank according to one of claims 1 to 7, characterized in that it consists of a coated substrate body made of a cermet, a hard metal, or a ceramic, the single- or multi-layer coating being a hard material, preferably a carbide, nitride and / or carbonitride of the IVa to Vla metals of the periodic table, A1 ₂ 0 ₃ and / or Zr0, BN, a diamond-like layer or amorphous carbon.

9. A method for producing coated cutting inserts without a mounting hole for machining, characterized in that a cutting insert blank is produced by pressing, which has a through-opening (16) from the rake face (11) to the bearing surface (12), the cross-sectional profile of which is at least partially out of round or at least partially circular and where the largest possible inscribed circle has a diameter which is either <0.2 x IC or <1.5 mm, preferably <1 mm or which has a diameter which is> 0.65 IC or> 13.5 mm, where IC is the Inner circle diameter, and that this opening after sintering is used to thread the cutting insert both during pre-cleaning and during coating.

10. The method according to claim 9, characterized in that the coating is carried out by a low-temperature process and / or with directional deposition, preferably by the PVD or PCVD process.