JPH01183310A - Surface covering carbonization tungsten group cemented carbide made throw away tip for milling cutter - Google Patents

Abstract

PURPOSE:To improve heat resisting shock property and crack resistance so as to prevent the generation of a pitting and a crack and to extend the life of the tip in the caption by containing Co containing volume in WC group cemented carbide relatively, making the grading of a hard disperse phase and thinning the thickness of a hard covering layer. CONSTITUTION:WC group cemented carbide base body the average diameter of the grading of which is 0.5-2mum is formed in a way that 2-10% of one kind or two kind of TiC and TiN as the forming components of a hard dispersing phase, 2-15% of one kind or two kind of TaC and NbC and 15-25% of Co as the forming component of a connecting phase are contained and the constitution of remainders are WC and unavoidable impurities. Its surface is formed 2-6mum of average layer in thickness by a hard covering layer consisting of metallic carbide, nitride and oxide of 4a, 5a and 6a group is the element periodic table, aluminum oxide and one kind of a single layer of more than two kinds of plural layers in more than two kinds of solid solution. The above-mentioned covering tip has a normal abrasion mainly as the state of the cutting edge, the generation of a pitting is very few and the abrasion is not uniform so that superion milling cutting property is displayed.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention provides surface-coated tungsten carbide (hereinafter referred to as WC) that exhibits excellent fracture resistance, especially in 7-rice cutting.
This invention relates to an indexable tip made of base cemented carbide.

[Conventional technology]

Conventionally, 1 weight - (hereinafter - indicates weight).

As a hard dispersed phase forming component, one or two of titanium carbide (hereinafter referred to as TiC) and titanium nitride (hereinafter referred to as TiN): 10% or less.

Similarly, tantalum carbide (hereinafter referred to as TaC) and niobium carbide (hereinafter referred to as TaC) are hard dispersed phase forming components.

One or two of the following (denoted as NbC): l〇- or less.

As a bonded phase forming component, Co: 5 to 1296. Usually 5 to 40 seconds.

, and the rest is W as a hard dispersed phase forming component.
A WC-based cemented carbide base material having a composition consisting of C and inevitable impurities and having a hard dispersed phase with an average particle size of 3.6 to 4.5 μm is coated with 1 using a normal chemical vapor deposition method. Carbides of metals of groups 4a, 5a, and 6a of the elemental system, i! nitrides and oxides.

A hard coating layer consisting of aluminum oxide and a single layer or a multilayer of two or more of these 2'8 or more solid solutions is formed with an average layer thickness of 7 to 10 μm, usually B to 9 μm. It is well known that indexable inserts made of surface-coated WCC cemented carbide are used for cutting tools.

In this conventional surface-coated WC-based cemented carbide throw 7-way chip, as described above, the 'o content is kept low, while the grain size of the hard dispersed phase is coarsened, and the thickness of the hard coating layer is relatively increased. By increasing the thickness, it ensures high creep strength and excellent wear resistance, making it suitable for cutting with a cutting tool where the cutting temperature rises rapidly and these characteristics are required.

[Problem that the invention seeks to solve]

However, when using the conventional surface-coated WCC cemented carbide indexable insert mentioned above, the increase in cutting temperature is less than when cutting with a bite, but when used for 7-rice cutting, which is subject to thermal shock due to repeated heating and cooling. The cutting edge tends to chip or break due to insufficient thermal shock resistance and fracture resistance.

Currently, they only have a relatively short service life.

[Means for solving problems]

Therefore, the inventors of the present invention, etc., from the above-mentioned viewpoint.

In order to develop indexable inserts for milling cutting, we conducted research focusing on the above-mentioned conventional surface-coated WCC cemented carbide. a - By relatively increasing the Co content of the WCC cemented carbide that constitutes the base of the away chip, by making the hard dispersed phase finer in grain size, and by reducing the thickness of the hard coating layer, the resulting surface coating increases. The slow 7-way insert made of WC-based cemented carbide has excellent thermal shock resistance and chipping resistance, and provides excellent cutting performance when used in milling that requires these properties. We have obtained knowledge that it will be effective over a long period of time.

This invention was made based on the above findings.

As hard dispersed phase forming components, TiC and 'I'iN
One of these and two acids: 2 to 10 liters.

Similarly, TaC and NbC are used as hard dispersed phase forming components.
(7) One or two of these: 2 to 151! .

As a bonded phase forming component, Co: 15-25-.

, and the rest is W as a hard dispersed phase forming component.
Surface K of a we-based cemented carbide having a composition consisting of carbon and inevitable impurities, and in which the average particle size of the hard dispersed phase is 0.5 to 2 μm.

Among the carbides, nitrides, and oxides of metals in Groups 4a, 5a, and 6a of the Periodic Table of Elements, aluminum oxide, and solid solutions of two or more of these, INi is a single layer or a complex of 2a or more. The present invention is characterized by a surface-coated we-based cemented carbide indexable insert for milling cutting, which is formed by forming a hard coating layer with an average layer thickness of 2 to 6 μm.

Next, in the indexable tip of the present invention, the reason why the component composition of the substrate constituting the tip, the average particle size of the hard dispersed phase, and the average layer thickness of the hard coating layer are limited as described above will be explained.

(Al Tic and 'riN, as well as TaC and NbC content. These components contain TiC and/or 'IN.

When TaC and/or NbC coexist in a good condition, they have the effect of significantly improving the hardness of the substrate and thereby improving the wear resistance, but if the content of each is less than 2 -, the desired excellent wear resistance is not achieved. However, the content of TiC and TiN is 10%,
For TaC and NbCK, if the content exceeds 15-1, the fracture resistance of the substrate decreases, so the content is reduced to 'riC and TiN: 2~l O4,Tt
hC and NbC: 2 to 15-, respectively.

lb) Co content Co component has the effect of improving the thermal shock resistance and chipping resistance of the chip, but if its content is less than 15%, the desired effect cannot be obtained; amount is 25
If the content exceeds 15% to 25%, the plastic deformation resistance decreases, so the content was set at 15-25%.

(C) Average particle size of hard dispersed phase If the average particle size is less than 0.6 μm, the desired excellent fracture resistance cannot be secured, whereas if the average particle size exceeds 2 μm, thermal shock resistance will be poor. As the
The average particle size of snow was determined to be 0.6 to 2μ.

(a) Average layer thickness of the hard coating layer If the average layer thickness is less than 2 μm, the desired effect of improving wear resistance cannot be obtained; on the other hand, if the average layer thickness exceeds 6 μm,
The average layer thickness was determined to be 2 to 6 μm since the chipping resistance and thermal shock resistance decreased.

〔Example〕

Next, the indexable tip of the present invention will be specifically explained using examples.

Raw material powders include WC powder, TiC powder, and 'riN powder, each having a predetermined average particle size within the range of 0.5 to 1.5 μw.
Powder, TaC powder, Nt)C powder, and Co powder were prepared, and these raw material powders were each blended into the composition shown in Table 1, ground and mixed in a ball mill for 96 hours, and then press-molded to form a compacted powder. After forming a body, it is sintered in a vacuum of 10"2 Torr at a temperature of 1350 to 1400°C and a holding time of 1 hour to obtain a material having substantially the same composition as the blended composition and a hard dispersion. We-based cemented carbide substrates in which each phase has an average grain size as shown in Table 1 are prepared, and then a conventional chemical vapor deposition method is applied to the surface of each substrate to form a layer with a composition and an average layer also shown in Table 1. The present invention surface coating of 8NP 632 by forming a thick hard coating layer
Throwaway chips made of base cemented carbide (hereinafter referred to as the present invention coated chips) 1 to 9 and comparative surface-coated we base S hard alloy indexable tips (hereinafter referred to as comparative coated chips)
1 to 1O were produced, respectively.

Comparative coated chips 1 to 10 were all tested under any of the following conditions (Table 1 *
(marked) are outside the scope of this invention.

In addition, for comparison purposes, a hard coating layer with the composition and average layer thickness shown in Table 1 was formed on the surface of a P30 WE-based cemented carbide substrate to create a conventional surface wave @ WC-based cemented carbide throw. 7-way chip (hereinafter referred to as conventional coated chip)
was manufactured.

Next, we will discuss the various coated chips obtained as a result.

Cutting method: End face cutting of 1OIllI thick plate material.

Rigid material: 8NCM439 (hardness: I (B270).

Cutting speed: 250m/m, Feed: -0.8ml
blade.

Depth of cut: 1m, Cutting oil: None.

A 7-rice cutting test was conducted on steel under the following conditions, and the cutting length was measured until the relief of the cutting edge reached a surface wear width of 0.4101. In addition, if chipping occurs on the cutting edge during cutting and it becomes unusable, the cutting length up to that point will be shown. These measurement results are shown in Table 1 along with the condition of the cutting edge.

〔Effect of the invention〕

From the results shown in Table 1, the coated inserts 1 to 9 of the present invention all exhibited long cutting life, and the cutting edge condition was mainly normal wear, with only a small amount of chipping occurring. The comparative coated tip 1 showed excellent cutting performance with 7 slices, although the wear was somewhat uneven.
10, if any of the component composition of the substrate, the average particle diameter of the hard dispersed phase in the substrate, and the average layer thickness of the hard coating layer deviate from the scope of the present invention, the cutting edge may deteriorate. Large chipping, breakage, or abnormal wear occurs, and the service life ends in a relatively short period of time, and it is impossible to use conventional coated tips for milling, which are conventionally used for tool cutting. That is clear.

As mentioned above, the surface-coated WE-based cemented carbide indexable insert of the present invention has excellent fracture resistance and furthermore has excellent thermal shock resistance, so these characteristics are required.
When used for rice cutting, it exhibits excellent performance over an extremely long period of time.

Claims (1)

[Claims] (1) carbides of metals from groups 4a, 5a, and 6a of the periodic table of the elements on the surface of the tungsten carbide-based cemented carbide substrate;
A surface-coated tungsten carbide-based carbide formed by forming a hard coating layer consisting of a single layer or a multilayer of two or more of nitrides, oxides, aluminum oxide, and solid solutions of two or more of these. In the alloy throwaway chip, the above-mentioned substrate contains 2 to 10% of one or both of titanium carbide and titanium nitride as hard dispersed phase forming components, and tantalum carbide and niobium carbide as hard dispersed phase forming components. One or two of them: 2 to 15%, Co: 15 to 25% as a binder phase forming component, and the remainder consisting of tungsten carbide as a hard dispersed phase forming component and unavoidable impurities ( % by weight) and whose hard dispersed phase has an average particle size of 0.5 to 2 μm, and the hard coating layer has an average layer thickness of 2 to 6 μm. A surface-coated tungsten carbide-based cemented carbide throw-away tip for milling.