DD208482A3 - CUTTING INSERT OF TANTALCARBIDE CONTAINING SINTERHARD METAL - Google Patents

Abstract

The invention relates to a cutting insert of tantalum carbide-containing cemented carbide, in particular for the beam processing, is assumed in the of a known sintered cemented carbide of tungsten carbide and / or titanium carbide with at least one binder metal of the iron group. It is the object of the invention to reduce the raw material costs without sacrificing the performance in such cutting inserts. The invention is based on the object in cutting inserts of tantalum carbide containing cemented carbide to reduce the content of tantalum carbide in comparison to the known cutting inserts of this type, but to maintain their cutting resistance or Temperaturwechselbestaendigkeit. This object is achieved according to the invention in that the edge zone of the cutting insert consists of the sintered hard metal base alloy, which is unchanged in its crystal structure, and with tantalum carbide alloyed with a mixed crystal through a diffusion process.

Description

Cutting insert of tantalum carbide-containing cemented carbide

Field of application of the invention

The invention "relates to a. The cutting insert of Tantalcsr-" bid-containing sintered hard metal, in particular for steel machining _s in the prior art of a cemented carbide of tungsten carbide and / or titanium carbide with at least one binder metal of the iron group 'assumed as a base alloy Trird *

Characteristic of the known technical solutions

Cutting inserts of cemented carbide based on tungsten carbide and / or titanium carbide with cobalt binder are known, which contain an alloying alloy of xantalum carbide, which increases their thermal stability * For base alloy cutting inserts without tantalum carbide, even at relatively low thermal loads. Ixainmrisse on. At the beginning of the factory, whereby, after a short period of time, the latter breaks out and prematurely comes to a standstill. The Zammri.3e: tolerance "5'on Schneideinsätsen is particularly under the S he span naiig ab e dungen the unt3rbroch.en.an cut., like him at

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Presiding tools are decisive, determining the length of the service life * For this reason, special preshare metals have a high tantalum carbide content for steel processing »

In the case of carbides based on titanium carbide with molybdenum carbide and Έ ± cke! Binder, the addition of tantalum carbide also leads to an improvement in the tarmac resistance

These advantages of the improved Teinperaturwachselbeständigkeit of cutting inserts of tantalum carbide containing cemented carbide is compared with ₉ that it is a rare tantalum ago heavy metal, in which the extraction costs and als.Polge of the procurement costs have risen sharply, which is due to the magnitude of factory extraneous costs in the application of such cutting inserts is therefore an objection to many manufacturers of nuts producing "such cutting inserts which contain no or only a low amount of tantalum carbide and preferably have the same bodily and / or siding properties; such as cutting inserts of tantalum carbide-containing cemented carbide,

One such solution would be to use a sintered carbide cutting insert as described in AT Pat. No. 279,792, in which tantalum carbide is to be replaced by mixed crystals of IFioocarbide and Hafniuacarbid, wherein Uiobcarbia is to contain up to 30 % tantalum carbide. Ss has however, it has been shown that acceptable tamperature change resistance is only present in the lower portion of the substitution carbides. "SehneideinsStze", in whose hard material pha.sa more than 30 % tantalum carbide 'is replaced, show an increasing percentage of substitutional carbide 7ersprSangen srdesi. If the content of tantalum carbide is generally high, or if the ratio is still high, these cutting inserts do not represent good substitute solutions ₉

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According to DS-AS 1247 671, it has also been considered to increase the hardness in the surface zone of cemented carbide bodies in relation to the core by virtue of the fact that the PUI mixture from which the molding is manufactured has a surface area greater concentration of hard metal such as tungsten carbide, titanium carbide, tantalum carbide than in the core, but this route was discarded because of the hardness of the carbide in the surface of the surface.

In GB-PS 1457 181 a tungsten carbide smearing tool is described which is characterized by a metal of the group IY S or YB of the SE which has been diffused into its surface. In this diffusion process it is supposed to grow just below the surface of the skin A reduction of the tungsten coarae of the base material and the formation of carbides of the diffused IT B or YB metal (which also includes tantalum) are considered. "In the description of the invention, it is assumed that the resulting tungsten enters the binder body and its melting point disadvantageous, is that the diffusion of an IY 3 or YB metal into a WC-based carbide has the reduction of the WC phase to the PoIg--, where the WG x £ oe? the Cobaltphas-e sole fabric gives off to the forming carbide. Carbon deficit system W / Co / C results

Composition Co ^ W-G, The training of this in the .Hart; The malfunctioning phase leads to the loss of ductility of the binary metal phase and thus to the deformation of the humoral body, which makes it suitable for practical use.

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The aim of Erf indan.

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Ss is the goal 'of the invention, hot cutting inserts of tantalum carbide containing cemented carbide for metal cutting machining lower the raw material costs without sacrificing the performance su.

Presentation of the essence of the invention

The invention is based on the object at a cutting insert 'on. the basis of tungsten carbide and / or titanium carbide with a bond group of the iron group and an alloying additive of tantalum carbide, to reduce the content of tantalum carbide in comparison to the known cutting inserts of this type, but to maintain their cutting resistance with respect to thermal shock resistance *

This object is achieved erfindungsgesäß in that the edge zone of the cutting insert consists of the unchanged in their crystal structure Sinterhartsietäll base alloy rait by • a diffusion process with mixed crystal troughed Sulphated tantalum carbide «

For reasons of edge stability it is expedient that the thickness of the tantalum carbide enriched hand zone of the sintered carbide diffusion alloy 10 is SOOyum preferably 20-200 / Dia.

A further field of application of the cutting unit with the hand zone enriched with tantalum carbide according to the invention is the fact that wear-resistant surface layers of carbides, nitrides, borides and / or oxides are applied to the tantalum carbide-enriched edge zone of the cutting insert.

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As is apparent from this inventive solution of the underlying task, the cutting insert is made of a basic Sinterhartmetallegierurag of tungsten carbide and / or Tixancarbid with at least one binder metal 'iron group whose basic structure is present in the entire cross-section and only in a limited The enrichment with tantalum carbide is enriched by tantalum carbide diffusion through diffusion of tantalum carbide into the base alloy host lattice. As such tantalum carbide host lattices, hard struc- tures and / or mixed crystals are suitable in which tantalum carbide can dissolve, such as ζ * B * titanium carbide ,. Tungsten carbide / titanium carbide mixed crystal or titanium carbide / molybdenum carbide mixed crystals »It is of particular importance ₃ that tantalum carbide forms as additional carbide with the carbides of the basic alloy tungsten carbide and / or titanium carbide saturated mixed crystals«

In terms of manufacturing technology, in the manufacture of the cutting implements according to the invention, the procedure is such that sintered hard metal grains are first produced in the shape of the respective cutting dies according to the usual Kartsietall technology

In the first method step, an etrah 5 × 10 μm thick tantalum carbia top layer is applied to these sintered hard shell bodies by one of the coating methods mentioned. In the second method step, the tantalum carbide coated cemented carbide bodies of a Tennoe ~ ** ρ turbehaxidl'in * ³ * ~ * ni "*" ¹ -rter odex 'Reducing - ^^ · he J ^' tmosOhäre above the alloy specific eutectic temperature under so-called "These BehardlunZrstemOerci ^ ur iTiLifl ie above dsr ~" T9mOer- ^a, · "·

constantly diffused into the edge zone of the cemented carbide body "Accordingly, the treatment rate must also be specified *

It will thus be noted that, depending on the base alloy, the thickness of the applied tantalum carbide surface layer, and the temperature-time regime applied to the temperature treatment in the edge zone of the cutting insert, a phase equilibrium will be established which will govern the range of the factory edger cuts The cutting inserts according to the invention with tantalum-carbide-alloyed Eandsone are equivalent in their physical test values with cutting inserts of tantalum carbide-alloyed sintered hard metals. "In contrast, they have the door part that the raw material costs due to the lower amount of expensive tantalum carbide significantly lower say» in stress tests found that the Cutting inserts according to the invention especially when milling steels and when turning with an interrupted cut or sharply fluctuating cutting loads show a much lower tendency to form τοη comb cracks as comparable cutting inserts made of continuous tantalum

Carbide-alloyed carbide alloys *

embodiments

In the following, production, structure and properties of cutting inserts according to the invention are explained in more detail in three exemplary embodiments:

Example 1:

Cemented carbide inserts made of a sintered metal alloy consisting of 82 % tungsten carbide, 9 % titanium carbide and 9 % cobalt were prepared by means of a gas phase coating (CYD) process.

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provided with a 8 / um thick tantalum carbide ,, Subsequently, the "coated Sintarhartmetallkörpar" at 1320 C under Yakuuni were teaperaturbehandelt, "Examination of the indexable inserts thus prepared with the Slektronenstrahlziikro probe showed. that, in the cutting region close in a et ~? a 80 / The properties of the indexable inserts according to the invention were determined in a twisting test and with the properties of indexable inserts of a tantalum carbide alloyed sintered hard-metal alloy consisting of 74.5 % WC, 5 % TiC , 12 % TaC and 8.5% Co compared.

Test conditions: 3s were 4 studs made of steel C 60 with

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Plazigedreht outside.

- 1 cutting speed: ~ r = 60 rn. * Inin.

Feed: s = 0.5

Depth of cut: a = 1 mm

Performance result: the measurement of the Tsrschlai brand width

after the machining of 30 workpieces, the known as well as the turning according to the invention were sewn

cut the same size

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Example 2:

On one of the number of indexable inserts To ^ Be ~ s "oie" i 1 "TU" ** de after the teinioeraturbeha ^ dlurs; under & i wenilung a CYD Yerfahrens a S / um thick 'layer of titanium carbide applied "Diesa inserts were coated with the same passage Yergleichs indexable inserts from Example 1 in einers. trial compared *

test conditions; Blocks made of steel C 60 in the dimension 1000 s -300 mm were milled with a milling head of 315 sin diameter »

Cutting speed: ν = 140 irumin "feed per tooth: s = 0.15 mra / g depth of cut: a = 2 mm

Performance result: tool life of the known indexable inserts 25 m

Standstill of the indexable inserts 40 in accordance with the invention

The well-known. Indexable inserts showed on the standstead reinforced KaisrnrißbilduiLg,

Example 3 *

Indexable inserts made of tungsten carbide-free cemented carbide, consisting of 68 % titanium carbide and 12 % molybdenum molybdenum carbide and. 20% .IIickel were CYD at 850 ° C with a 5 / um thick. Provided tantalum carbide layer and then at 1300 ⁰ C for one hour under hydrogen atmosphere temperatürbehändeIt "Subsequently, they were still with a 6 / provided to thick Ti tanca.ro id layer * The studies with the electron microprobe seigten ^ that the indexable inserts below the TiC-surface layer about 40 to thick edge zone in which TO % tantalum carbide had been diffusion-doped. "These indexable inserts of the present invention were rotationally continuous cut with the cemented carbide inserts of a 63 % titanium carbide, 12 % molybdenum-metal carbide cemented carbide alloy and 20 % hickel, also coated with TiC, compared *

Backing conditions: A steel roll made of steel G 6θ was used.

Circumference overrun *

Cutting speed: ύ - 1 50 laminin feed: s = 0.3 nnn / ü

Depth of cut: a = 3 mm

Performance result: the measurement of the wear range

after, a rotation time of 60 min resulted

familiar 'indexable insert: B = 0 _s o1 now

Turnover according to the invention

Cutting plate: B = 0.40 mm.

Claims (3)

1 * cutting insert of tantalum carbide-containing cemented carbide based on tungsten carbide and / or titanium carbide Sinterhartiaetall-Legiarungen with at least one binder metal of the iron group, characterized in that the edge zone of the cutting insert of the in. its crystal structure is unchanged sintered carbide base metal alloy with tantalum carbide alloyed by diffusion through mixed crystal formation * 1 Π J o ίο rfindungsanspruch He-p The cutting insert of cemented carbide containing tantalum carbide according to item 1, characterized in that the thickness of the tantalum carbide enriched edge zone made of the sintered carbide biffusion alloy is 10 - 800 / μm, preferably 20 - 200 μm. 3 «Cutting insert of Tautalcarbid-containing cemented carbide according to the ¹ points 1 and 2, characterized in that wear-resistant surface layers of garbides, nitrides, Boricsn and / or oxides are applied on der.mit" tantalum carbide enriched edge zone of the cutting insert.