JP2007111786A - Cermet insert and cutting tool - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cermet insert excellent in chipping resistance and wear resistance and a cutting tool. <P>SOLUTION: This cermet insert contains Ti, Nb and/or Ta and W of 70 to 95 wt.% in relation to the entire structure constituting the sintered body in a sum of a value of Ti in terms of carbonitride, a value of Nb and/or Ta in terms of carbide and a value of W in terms of carbide (containing W of 20 to 35 wt.% in relation to the entire structure in a value in terms of carbide), and contains Co and Ni of 5 to 30 wt.% in relation to the entire structure, as a sintered body composition. The cermet insert has the structure made of a hard phase made of at least (Ti, W, Ta/Nb)CN of (Ti, W, Ta/Nb)CN and titanium carbonitride and a binding phase mainly made of W, Co and/or Ni. Of W contained in the entire structure, W of 40 to 65 wt.% is contained in the hard phase, and the remaining part of W is contained in the binding phase. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a cermet insert and a cutting tool, and more particularly to a cermet insert excellent in wear resistance and fracture resistance and a cutting tool including the cermet insert.

  Conventionally, cermet inserts having a structure consisting of a hard phase (hard particles) and a binder phase existing between the hard phases have been used for cutting steel and the like, in order to improve the performance of the cermet inserts. Various technologies have been proposed.

For example, Patent Document 1 below has an ordinary cored structure. Specifically, the core is rich in 4a group such as Ti, and the peripheral part is rich in 5a and 6a groups such as W and Ta (black). Phase) and a core portion composed of a plurality of phases (white phase) rich in 5a group and 6a group such as W and Ta, and by dispersing the black phase and the white phase in an optimal ratio, TiCN-based cermets with improved alloy strength have been proposed.
JP-A-62-170452

  However, the technique of Patent Document 1 has a problem in that although the strength of the alloy can be improved to some extent by the above-described configuration of the black phase / white phase, the examination on the wear resistance and fracture resistance is not always sufficient. .

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a cermet insert and a cutting tool capable of maintaining high wear resistance and realizing high fracture resistance. .

The invention of claim 1 (cermet insert) for solving the above problem
As the sintered body composition, Ti, Nb and / or Ta, and W, the value obtained by converting the Ti into a carbonitride, the value obtained by converting the Nb and / or Ta into a carbide, and the W as a carbide. And 70 to 95% by weight with respect to the entire structure constituting the sintered body (of which W is a value in terms of carbide, 20 to 35% by weight with respect to the entire structure) ,
A cermet insert containing 5 to 30% by weight of Co and Ni with respect to the entire structure,
Among the (Ti, W, Ta / Nb) CN and titanium carbonitride, a hard phase comprising at least the (Ti, W, Ta / Nb) CN,
Having a structure consisting of W and a binder phase mainly composed of Co and / or Ni,
Of the W contained in the entire structure, the hard phase contains 40 to 65% by weight, and the binder phase contains the remainder.

The insert made from cermet of this invention is substantially comprised by the structure | tissue which consists of a hard phase (hard particle) and the binder phase which covers the circumference | surroundings.
In the present invention, the reason why the total of converted values of Ti and Nb and / or Ta and W is set to 70 to 95% by weight as the sintered body composition is as follows. Ti is TiCN converted, Nb and / or Ta is (Nb / Ta) C converted, and W is a WC converted value.

  First, the composite carbonitride and carbonitride that form the hard phase (hard particles) have the effect of improving the hardness of the cermet and improving the wear resistance. However, the ratio of the hard phase is 95% of the entire cermet. This is because the proportion of the binder phase is relatively less than 5% by weight when the content exceeds 50%, the toughness is lowered, and the fracture resistance is lowered. On the other hand, if the ratio of the hard phase is less than 70% by weight, the ratio of the binder phase relatively exceeds 30% by weight, so that the wear resistance of the cermet is lowered.

Moreover, the wear resistance of an insert can be improved by containing 20 to 35 weight% (in WC conversion) with respect to the whole structure | tissue.
Furthermore, Co improves the sinterability, forms a binder phase, and improves the strength of the insert. Ni forms a binder phase during sintering and improves the heat resistance of the binder phase, thereby increasing the wear resistance of the insert. That is, the above characteristics can be exhibited by containing Co and Ni in a total amount of 5 to 30% by weight, but each of Co and Ni is preferably 5% by weight or more.

In particular, in the present invention, 40 to 65% by weight of the W is distributed in the hard phase as a carbide converted value, and the remainder of W is distributed to the binder phase.
In other words, in the present invention, the hard phase is strengthened by containing 40 to 65% by weight of W contained in the entire structure in the hard phase, so that the hard phase is strengthened. In addition, by including the remainder of W in the binder phase as a solid solution, the hardness of the binder phase is increased, so that the wear resistance is improved. Thereby, there is a remarkable effect that both high wear resistance and chipping resistance can be realized.

  The “A and / or B” means at least one of A and B (the same applies hereinafter). Moreover, the above-mentioned “having W and Co and / or Ni as main components” indicates a state in which the total amount is larger than the total amount of other components, for example, the total amount reaches about 98% by weight.

  The invention of claim 2 includes 45 to 60% by weight of Ti in terms of carbonitride and 5 to 10% by weight of Nb and / or Ta in terms of carbide with respect to the entire structure. It is characterized by including.

  The present invention exemplifies a preferable content of Ti, Nb and / or Ta. If Ti is in this range, the wear resistance is high, and if Nb and / or Ta is in this range, the thermal shock resistance is high. Is expensive.

The invention of claim 3 is characterized in that the hard phase includes one or more of the following (1) to (3) (excluding (3) alone).
(1) a first hard phase having a core structure in which a core part is a titanium carbonitride phase and a peripheral part is a (Ti, W, Ta / Nb) CN phase;
(2) a second hard phase having a core structure in which both the core portion and the peripheral portion are composed of (Ti, W, Ta / Nb) CN phase;
(3) Third hard phase having a single-phase structure composed of a titanium carbonitride phase In the present invention, as illustrated in FIG. 1, the hard phase has a configuration selected from the above-described three hard phases, The hardness of the insert can be increased and the wear resistance can be improved.

The invention of claim 4 is further characterized in that Mo is contained in the hard phase and / or the binder phase.
By containing Mo, the wettability of the hard phase and the binder phase is improved, so that the sinterability can be improved. In the case of Mo, Mo is included in the peripheral portion of the first hard phase, the second hard phase, and the binder phase. Mo is contained, for example, in an amount of 20 to 35% by weight in terms of carbide (Mo ₂ C) with respect to the entire insert.

The invention of claim 5 is further characterized in that the binder phase contains 40 to 60% by weight of W with respect to the whole binder phase.
In the present invention, since 40 to 60 wt% of W is contained in the binder phase, the high-temperature hardness of the binder phase is improved, and thus excellent wear resistance can be exhibited, for example, in high-speed cutting with high temperature generation.

The invention of claim 6 (cutting tool) is characterized in that the holder includes the cermet insert according to any one of claims 1 to 5.
Since the cutting tool of the present invention is provided with the cermet insert described above in the holder, it is excellent in wear resistance and fracture resistance.

Here, as a preferable embodiment of the present invention, for example, as described in Japanese Patent Application No. 2005-173463 already filed by the applicants of the present application, the following configuration can be further adopted.
For example, as an insert, “tungsten carbide: 20-30% by mass, tantalum carbide and / or niobium carbide: 5-10% by mass, Co: 5-10% by mass, Ni: 5-10% by mass, titanium carbonitride: balance (However, it is contained in a range of 50 to 60% by mass).

Furthermore, for example, as the sintered body, “a structure having a structure composed of a hard phase: 75 to 90 area% and a binder phase: the remainder in a structure observation with a scanning electron microscope” can be adopted.
In addition, as the binder phase, “in the proportion of the binder phase, Co: 18 to 33 mass%, Ni: 20 to 35 mass%, Ti, Ta and / or Nb: 5 mass% or less, W: balance (however, , W: 40 to 60% by mass) ”.

  The balance of the composition usually contains inevitable impurities.

  Next, an example (example) of the best mode of the present invention, that is, an example of a cermet insert and a cutting tool will be described.

a) First, a cermet insert (hereinafter simply referred to as an insert) of this example will be described.
As shown in FIG. 2, the insert 1 of this embodiment is a cutting tip made of a sintered body having a shape of ISO standard: SNGN120408.

  As shown in FIG. 1, the insert 1 is composed of a structure (including inevitable impurities) composed of a hard phase (hard particles) and a binder phase existing so as to cover the periphery thereof. Among these, the hard phase is composed of (Ti, W, Ta / Nb) CN and titanium carbonitride, and the binder phase is mainly composed of W and Co and / or Ni.

  As the sintered body composition of the insert 1, with respect to Ti, Nb and / or Ta, and W, Ti is converted into carbonitride, Nb and / or Ta is converted into carbide, and W is converted into carbide. In total, it contains 70 to 95% by weight with respect to the entire insert. Of these, W is a value in terms of carbide and is contained in an amount of 20 to 35% by weight with respect to the entire structure.

Further, Ti contains 45 to 60% by weight in terms of carbonitride with respect to the entire structure, and Nb and / or Ta contains 5 to 10% by weight in terms of carbide.
Further, the hard phase contains 40 to 65% by weight of W in terms of carbide, and the remainder of W is contained in the binder phase.

In addition, as the hard phase, for example, all of the following hard phases (1) to (3) are provided.
(1) a first hard phase having a core structure in which a core part is a titanium carbonitride phase and a peripheral part is a (Ti, W, Ta / Nb) CN phase;
(2) a second hard phase having a core structure in which both the core portion and the peripheral portion are composed of (Ti, W, Ta / Nb) CN phase;
(3) Third hard phase having a single-phase structure composed of a titanium carbonitride phase Therefore, the insert 1 of this example has high wear resistance and chipping resistance, as shown in an experimental example described later, due to the unique configuration described above. Both have sex.

  Moreover, the insert 1 mentioned above is fixed to the front-end | tip of the columnar holder 3 made from steel with the fixing jig 5, as illustrated in FIG. And cutting of steel etc. is performed using the cutting tool 7 with which the insert 1 was fixed to this holder 3. FIG.

b) Next, the manufacturing method of the insert of a present Example is demonstrated. Here, an explanation will be given by taking as an example a method for manufacturing an insert for use in an experiment described later.
In this example, first, the raw material powder was prepared and wet mixed.

Specifically, as shown in Table 1 below, TiC _0.5 N _0.5 powder having an average particle size of _{0.5 to 2} μm, TiC _0.3 N _0.7 powder having an average particle size of _{0.5 to 2} μm, and an average particle size of 1 to 2 μm. Prepare WC powder, Ta powder with an average particle size of 1-2 μm, NbC powder with an average particle size of 1-2 μm, Co powder with an average particle size of 2-3 μm, Ni powder with an average particle size of 2-3 μm, and these raw material powders Were blended into the blending composition shown in Table 1 below to prepare four types of mixed powders A to D.

Next, each of the mixed powders A to D was wet-mixed in alcohol in a ball mill for 24 hours, and then dried.
Next, this dried powder was press-molded into a green compact at a pressure of 98 MPa.

Next, the green compact was fired under the following firing conditions (a) to (e) as shown in FIG.
(a) The temperature is raised from room temperature to 1200 ° C. at a rate of 10 ° C./min in a vacuum atmosphere (V) of 10 Pa or less,
(b) After heating up to a temperature of 1200 ° C. (intermediate temperature: 1200 to 1250 ° C. can be used as the intermediate temperature), holding the Ar atmosphere for a short period of 2 minutes in an Ar atmosphere of 35 kPa, and 10 Pa or less Perform atmosphere alternation process to alternately and repeatedly hold vacuum atmosphere for 15 minutes in vacuum atmosphere,
(c) After the atmosphere alternating change treatment, the temperature is raised to 1350 ° C. in a vacuum atmosphere of 10 Pa or less at a rate of 2 ° C./min,
(c) The temperature was increased from 1350 ° C. to a predetermined sintering temperature (1500 ° C.) at a rate of 2 ° C./min, and the sintering temperature was maintained for 60 minutes in a nitrogen atmosphere of 1.3 kPa,
(e) Furnace cooling from the sintering temperature was performed in an Ar atmosphere of 90 kPa or less.

The insert 1 having a chip shape of ISO standard: SNGN120408 was manufactured by sintering under conditions including the steps (a) to (e) described above, followed by polishing after sintering.
That is, as shown in Table 2 below, inserts of sample Nos. 1 to 4 corresponding to the four kinds of mixed powders were produced.

  For comparison purposes, as shown in Table 2 below, comparative examples of inserts were produced under substantially the same conditions (sample Nos. 5 to 8) except for the difference in intermediate temperature.

c) Next, composition analysis and cutting evaluation of the inserts of sample Nos. 1 to 4 of the present invention example and the inserts of comparative sample Nos. 5 to 8 manufactured by the above-described manufacturing method will be described.
(1) Composition analysis-Components (elements) contained in the inserts (sintered bodies) of each sample No. 1 to 4 of the present invention and sample No. 5 to 8 of the comparative example by EDS (energy dispersion method) Was quantified. And the component conversion of the component was performed. The results are shown in Tables 3 and 4 below.

  In addition, the composition of the bonded phase of the insert was analyzed by analysis using STEM (scanning transmission electron microscope) and EDS. The results are shown in Table 5 below.

-Further, the content of W was determined. The results are shown in Table 6 below.
Here, the amount of W in the binder phase relative to the entire insert, the amount of W in the hard phase relative to the entire insert, and the amount of W in the binder phase relative to the total amount of W are respectively represented by the following formulas <1> to <3>. It can ask for. In calculating the amount of W, etc., the amount of element (wt%) was used instead of the converted value.

・ W amount in binder phase [wt%]
= (B in binder phase composition) * (Co + Ni in sintered body composition) / (Co + Ni in binder phase composition)
... <1>
・ W amount in hard phase [wt%]
= (W amount in the sintered body)-(W amount in the binder phase) <2>
-W amount in the binder phase with respect to the total W amount [wt%]
= (W amount in the binder phase) / (Total W amount) ... <3>

(2) Fracture resistance test The insert of each sample was screwed to the tip of a tool steel tool (holder) with a fixing jig to obtain a cutting tool.

And using this cutting tool, the dry intermittent high-speed cutting test of alloy steel was done on the cutting conditions of the following Table 2. The defect resistance test was performed using 20 inserts of the same type.
Then, the cumulative defect rate at the number of impacts of 700 times (the ratio of the number of inserts in which the defect occurs at 700 times) was examined. The results are shown in Table 8 below.

(3) Wear resistance test The insert of each sample was screwed to the tip of a tool steel tool (holder) with a fixing jig to obtain a cutting tool.

And using this cutting tool, the dry intermittent high-speed cutting test of alloy steel was done on the cutting conditions of the following Table 6.
The flank wear after 4min processing (V _B wear amount) was measured. The results are shown in Table 8 below.

  As is apparent from Tables 1 to 8, since the insert of the present invention example contains 40 to 65% by weight in the hard phase, particularly the W contained in the insert, and the remainder contains the binder phase. It turns out that it has the remarkable effect that both high abrasion resistance and defect resistance are realizable.

  Needless to say, the present invention is not limited to the above-described embodiments, and can be implemented in various modes without departing from the scope of the present invention.

It is explanatory drawing which shows typically the cross section of the insert made from cermet of this invention. It is a perspective view which shows the insert made from cermet of an Example. It is explanatory drawing which shows the cutting tool of an Example. It is explanatory drawing which shows the manufacturing method of the inserts made from cermet of an Example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Insert 3 ... Holder 5 ... Fixing jig 7 ... Cutting tool

Claims (6)

As the sintered body composition, Ti, Nb and / or Ta, and W, the value obtained by converting the Ti into a carbonitride, the value obtained by converting the Nb and / or Ta into a carbide, and the W as a carbide. And 70 to 95% by weight with respect to the entire structure constituting the sintered body (of which W is a value in terms of carbide, 20 to 35% by weight with respect to the entire structure) ,
A cermet insert containing 5 to 30% by weight of Co and Ni with respect to the entire structure,
Among the composite carbonitride of Ti and W and Ta and / or Nb [hereinafter referred to as (Ti, W, Ta / Nb) CN] and titanium carbonitride, at least the above (Ti, W, Ta / Nb) a hard phase composed of CN;
Having a structure consisting of W and a binder phase mainly composed of Co and / or Ni,
A cermet insert characterized in that, in W contained in the whole structure, the hard phase contains 40 to 65 wt% and the binder phase contains the remainder.   The entire structure contains 45 to 60% by weight of Ti in terms of carbonitride and 5 to 10% by weight of Nb and / or Ta in terms of carbide. Item 2. A cermet insert according to item 1. The cermet according to claim 1 or 2, wherein the hard phase comprises one or more of the following (1) to (3) (excluding (3) alone). insert.
(1) a first hard phase having a core structure in which a core part is a titanium carbonitride phase and a peripheral part is a (Ti, W, Ta / Nb) CN phase;
(2) a second hard phase having a core structure in which both the core portion and the peripheral portion are composed of (Ti, W, Ta / Nb) CN phase;
(3) Third hard phase with a single phase structure consisting of titanium carbonitride phase   Furthermore, Mo is contained in the said hard phase and / or a binder phase, The insert made from cermet in any one of the said Claims 1-3 characterized by the above-mentioned.   The cermet insert according to any one of claims 1 to 4, wherein the binder phase contains 40 to 60% by weight of W with respect to the whole binder phase.   A cutting tool comprising the holder and the cermet insert according to any one of claims 1 to 5.