JPS63176367A - Cubic boron nitride base superhigh pressure sintering material for cutting tool - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Industrial Field III] This invention provides a cubic crystal which has excellent heat resistance and toughness and is particularly suitable for use as a cutting tool for high-speed cutting of high-hardness steel such as hardened steel. It relates to boron nitride (under 12i, denoted CBN) based sintered materials.

[Conventional technology]

In recent years, there has been a rapid shift from grinding of high-hardness steels such as hardened steel to cutting processes with higher processing efficiency, and along with this, there has been a rapid shift from grinding of high-hardness steels such as hardened steel to cutting processes with higher processing efficiency. Sintered materials based on CBN\ group have attracted attention as materials for cutting tools, for example, Group 4a of the periodic table.

One or more of the group 5a + group 6a metal carbides, nitrides, borides, silicides, AA203 lMgO, AIN, Si3N4: 20-80% by weight, CBN
and unavoidable impurities: the remainder, the composition consisting of? CB with
A Nu sintered material has been proposed as a material for cutting tools for hardened steel (see Japanese Patent Publication No. 57-3631) [Problems to be solved by the invention] However, the above-mentioned conventional CBN-based sintered material Of these,
A CBN-based sintered material consisting of one or more of Ti carbides, nitrides, and borides, and cnN and inevitable impurities? As a cutting tool, for example, HRC: Hardness of 60 or higher? Hardened steel? If turning, what is the cutting speed? If the speed is 150 m/m Y, the material to be stiffened will easily weld to the cutting edge due to the temperature rise at the cutting edge.
Does this increase frictional heat and the temperature of the cutting edge? invite,
In addition to rapidly increasing wear on the cutting edge, the lack of toughness of the CBN-based sintered material causes chipping and damage to the cutting edge. Due to the fact that the conventional CBN-based sintered material is easily used as a cutting tool made of hardened steel, it has a cutting speed of approximately 100 m/wi.
It can only be used at cutting speeds below th, so it takes a long time to process each piece. So high cutting speed? Therefore, the above-mentioned conventional CBN-based sintered materials cannot be used for cutting large parts as required.
There is a problem that the value of using it as a cutting tool for cutting high hardness steel such as hardened steel has not yet been sufficiently obtained [Research-based knowledge]. This is the result of two rounds of various research to find a solution.

(1) The above conventional CBN-based sintered material f4? High hardness 'II4' as a cutting tool when cutting at high cutting speeds.

Therefore, during cutting, it is exposed to high temperatures7? :@Welded together? During the production of this CBN-based sintered material, the mixing device 1 made of cemented carbide or stainless steel, for example, the poles and pots of the sintered material are worn out, resulting in a significant decrease in wear resistance. The iron group metals and W mixed in the blade form a compound with B, and the B in the compound becomes unstable at high temperatures and becomes mobile, and when this B diffuses into the rigid material, it coats the cutting edge. Is the rigid material welding, increasing frictional heat and increasing the temperature of the cutting edge? Attributable to inviting.

f2) CBN-based sintered material #F+? If iron group metals are mixed in the raw material powder for manufacturing, iron group metals and B will be mixed during sintering.
reacts with partially liquid phase? Does this cause grain growth of Ti compounds? What is the toughness of sintered materials? to lower.

Therefore, are iron group metals and W mixed into the sintered material? If avoided, the above two problems will be solved at once, and a CBN-based sintered material with excellent heat resistance and improved toughness will be obtained.

(3) M in the fcBN-based sintered material improves the above properties.
oxides, nitrogen (arsenic oxides, nitric acid, arsenic oxides, and borides) (hereinafter referred to as A/203, respectively). It has been found that when one or more of the following are contained in an amount of 0.5 to 20%, the sinterability is improved and the fA property is further improved.

[Majun point? Means to solve]

This invention was invented based on the above knowledge, and has excellent heat resistance and toughness. CBN-based ultra-high pressure sintered material for cutting tools, especially suitable for high-speed cutting of high-hardness steels such as hardened steel. What to offer? For the purposes of this study, the carbides, nitrides, carbonitrides, and borides of Ti, denoted below by TiCr, TiN, T1CN, and T1B2, respectively, are these? One type or 2Ki or more of (collectively referred to as Ti compounds): 5 to 50%,
Impurities consisting of one or more of Fe + Co * Ni and W (12 is referred to as an impurity consisting of an iron group metal and W): 0.5% or less, as necessary.

One or more of the compounds of M: 0.5 to 20
%.

Unavoidable impurities other than CBN and the above impurities: Remaining.

Composition consisting of (1% heavy electric on lu)? To have? This is a characteristic feature.

[Detailed description of the invention]

Next, what is the composition range of this invention? Why did you limit it as above? state

(Al Ti compounds These components have the effect of imparting welding resistance to the material, but if the content is less than 5%, the same applies hereinafter), the desired welding resistance will not be achieved. cannot be secured, while it is 5
0%? If the content exceeds this amount, the toughness will be insufficient and the cutting edge will be prone to chipping.

Its contained electricity? The ratio is set at 5-50%.

(b) Impurities consisting of iron group metals and W These components combine with B during sintering to partially form a liquid phase? generation, thereby causing grain growth of Ti compounds? Urge material toughness? B contained in the sintered material in a state combined with the above components.

Exposure to high temperature C during cutting makes it easier to diffuse into the rigid material, resulting in poor welding resistance on the cutting edge. Will it degrade and wear out? In the CBN-based sintered material of this invention used as a cutting tool, especially for high-speed cutting of high-hardness steels, its toughness and sufficient welding resistance at high temperatures and therefore wear resistance, i.e. Heat resistance and? to ensure.

It is important that these impurities consisting of iron group metals and W are not included as much as possible, but if the content is 0.5% or less, the above disadvantages can be ignored. Containing punch? It was set as 15% or less.

(c) Compounds of RI These ingredients have a property of toughness of the material. Since it has the effect of improving the effect, it is added to the sintered material of the present invention as necessary, but if the content is less than 0.5%, the desired effect on the above effect cannot be obtained; ? If it exceeds this, the wear resistance of the cutting edge will decrease when the temperature reaches high temperatures, so its content is set at 20.5 to 20%.

The CBN-based sintered material of the present invention can be produced using an appropriate method that prevents impurities consisting of iron group metals and W from being contained in the mixed powder or green compact subjected to ultra-high pressure sintering. While adding or adopting, i.e. 1 e.g.
The above impurities during or after the preparation of the mixed powder? How to remove? Or is there a mixing method that does not mix the impurities into the mixed powder? 1. While adopting the normal ultra-high pressure sintering method, firstly, CBN powder is used as the raw material powder.

TiC powder, TiN powder, T1CN powder, TiB2
powder.

Al2O3 powder, MN powder, AJNO powder, and Ag
B.

Powder? Prepared and appropriately selected from these raw material powders? Blend into the specified composition and mix.

Then, in the state of mixed powder or compacted powder.

Along with WCC cemented carbide plate etc. as required,
It is inserted into a metal container, heated to a temperature of 2,800 to 1,200°C, vacuum degassed 2, and sealed.

Next is this enclosed container? Pressure and temperature after installing it on the high pressure and high temperature generator? After raising the pressure and holding the pressure and temperature within the range of 40 to 70 Kb and 1200 to 1600°C for several minutes to several tens of minutes.

Cooling and finally pressure? The basic process consisting of releasing? After that, it can be crushed.

Are the impurities introduced from mixing equipment such as ball mills during the mixing process of mixed powder preparation and armor making? Methods of removal include 1.For example, use a magnet in a mixed powder that is mixed with a solvent such as acetone to form a slurry. W? gently rotated and thereby bonded to iron group metals and them? How to attract it to a magnet, or mixed powder? After it dries? Pickling and said impurities? How to selectively dissolve etc? can be used.

In addition, when using the CBN-based sintered material of this invention as a cutting tool, it can be used as a smear-away tip either alone or in combination with a high-rigidity material such as WCC cemented carbide cermet. Furthermore, these chips may be used in a state in which they are housed in the tip of a holder made of YWC-based cemented carbide, hardened steel, or the like by brazing.

[Implementation fee]

Next, what about the CBN-based sintered material of this invention? This will be explained by an example.

As raw material powder, average particle size: 3μ? CBN powder having
Are all of them 1μ average particle size? TiC powder with TiN
powder, TiC□, 5NO, 5 powder, and TiB2
Powder and average particle size: 1.51J OJ Ai! 2
03 powder.

UN powder, MNO powder, A/B2 powder of the same 0.7μ? Prepare these raw powders? , impurities consisting of iron group metals and W among the composition components shown in Table 1, respectively. After blending each other at a blending ratio of fE, the mixture was mixed in acetone using a ball mill for 5 hours to form a mixed powder. Formation The mixed powder at this stage contains impurities mainly composed of iron group metals and W originating from the mixing device, and dry heavy grains.
It contained 1-5% based on the content.

Next, magnetically adsorbed impurities? Surface for easy removal? A cylindrical permanent magnet covered with a Teflon sheet (Teflon is a trademark of DuPont, USA)? The impurities are removed by gently rotating the mixed powder for 2 hours in the mixed powder that has been mixed with acetone to form a slurry. adsorption and removal thereby of the aforementioned impurities of the containing acids respectively shown in Table 1?
Contains.

9. What is the composition shown in Table 1? Mixed powder with? Prepared.

Next, 12 f2 tons of mixed powder prepared as follows
Dimensions of diameter: 13w x thickness: 1.5M at a pressure of /i? After molding into powder compacts, these compacts? , insert it into the container of the ultra-high pressure and high temperature generator.

By performing ultra-high pressure sintering under the conditions of pressure crab 50Kb, temperature: 1500℃, and holding time = 5 minutes, the composition is essentially the same as the blended composition. CBN-based sintered material of the present invention 1~
12 and comparative CBN-based sintered materials 1-5? The point was that they were manufactured and the impurities U) adsorption and removal 7 described above were not performed? Conventional CB by the same method as above except for
The N-based sintered material was also mold-centered. In addition, all of Comparative CBN-based sintered materials 1 to 5 have compositions in which one of the constituent acids (indicated by * in Table 1) is outside the scope of the present invention. It is something that we have.

Next, the resulting CBN-based sintered materials 1 to 1 of the present invention
12. Comparative CBN-based sintered materials 1 to 5 and conventional CBN
What is the toughness of the base sintered material? Fracture toughness value for evaluation purpose? Have you measured the welding resistance and abrasion resistance at high temperatures?
For the purpose of evaluation, cutting chips were cut out from each of the sintered materials (l), brazed to wC7I!i cemented carbide holders, and polished.

? J) FIIHJ: SCM-418 (7) Quenching w4 (
Hardness: HRC62) round bar (diameter: 100 m)
.

Cutting speed: 250m/m.

Continuous cutting test under the conditions of depth of cut: Q, ls- feed: O, OS times/rev. How long does it take for the flank wear width of the cutting edge to reach 0.2 W during actual turning? Measure these results? [Effects of the invention] are also shown in Table 1.

From the results shown in No. tl 1 CBN-based sintered material 1 of the present invention
~12 are all high toughness? It also has excellent welding resistance and wear resistance at high temperatures T81:? show,
Therefore, it is possible to achieve excellent cutting performance even in high-speed cutting of high-hardness steel such as hardened steel, which requires special orders. Compared to CBN & sintered materials? -11 to 5, if the content of any of the constituent components falls outside the scope of the present invention, at least one of the above properties will deteriorate, resulting in poor cutting performance. In addition, in conventional CBN-based sintered materials, iron group metals and W
In this invention, the impurity consisting of fCI′i, ? It can be seen that if a large amount of steel is contained in the steel, its adhesion resistance and wear resistance will deteriorate, and the cutting performance will be significantly inferior, making it impossible to obtain an FC cutting tool suitable for high-speed cutting of high-hardness steel. .

As mentioned above, the CBN-based sintered material eaves (2) of the present invention.

High toughness and heat resistance? Therefore, when used as a cutting tool for high-speed cutting of high-hardness steels such as hardened steel, which require these characteristics, it exhibits extremely excellent constant cutting performance, and therefore, Even if the material to be cut becomes a large part, it can be efficiently cut.

Claims (2)

[Claims] (1) One or more of Ti carbides, nitrides, carbonitrides, and borides: 5 to 50%, Fe, Co
, Ni, and W: 0.5% or less; unavoidable impurities other than cubic boron nitride and the above impurities: the remainder; A cubic boron nitride-based ultra-high pressure sintered material for cutting tools. (2) One or more of Ti carbides, nitrides, carbonitrides, and borides: 5 to 50%, Fe, Co
, Ni, and W: 0.5% or less; One or more of M oxides, nitrides, nitride oxides, and borides: 0 A cubic boron nitride-based ultra-high pressure sintered material for a cutting tool, characterized in that it has a composition (the above, weight %) consisting of: .5 to 20%, cubic boron nitride and impurities other than the above-mentioned impurities: the remainder.