JPH01242764A - Manufacture of tough cermet tool - Google Patents

Abstract

PURPOSE:To obtain a cermet tool improved in toughness to a greater extent by binding a hard dispersed phase consisting of the carbonitrides of Ti, W, and one or more elements selected from Mo, Nb, and Ta with a binding phase containing Ni and Co, applying grinding work to the above, and then subjecting the above to annealing under specific conditions. CONSTITUTION:A hard dispersed phase consisting of the carbonitrides of Ti, W, and at least one transition metal selected from Mo, Nb, and Ta is bound with a metallic binding phase containing Ni and Co, by which a cermet is prepared. This cermet is subjected to grinding work so as to be finished into a tool shape, annealed at 700-1,300 deg.C in vacuum, etc., for 15min-2h. By this method, toughness can be improved to a greater extent, and the tough cermet tool sufficiently usable as drills, end mills, etc., in which breakage becomes a critical defect can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for manufacturing extremely strong cermet tools.

[Conventional technology]

In recent years, cermets have come into widespread use as cutting tool materials.

Among cermets, those containing carbonitrides, namely titanium (T1), tungsten (W), and molybdenum (Mo
), niobium (Nb), and tantalum (Ta).
Sintered hard alloys bonded with a metal binder phase containing o) have excellent toughness and are being used as cutting tools. In order to manufacture a cutting tool from this cermet, it is necessary to grind the cermet into the shape to be used using a diamond grindstone or the like.

Cermet tools containing such carbonitrides are made of conventional tungsten carbide (WE) and carbides (T1, T) such as tungsten (W), titanium (T1), tantalum (Ta)
Compared to cutting tools made of cemented carbide, which has IL, W) c as a hard dispersed phase and is bonded with metals such as cobalt, it has extremely low adhesion to steel, so it is suitable for finish turning and milling. It is mainly used as a tool.

In particular, it has recently been found that by increasing the amount of carbonitride nitrogen contained in the hard dispersed phase, the carbonitride particles become finer, and as a result, the thermal cracking resistance among the toughness of cermets is improved. Therefore, the range of applications of cermet tools is expanding (Patent application No. 62-236604)
(see publication).

[Problem to be solved by the invention]

As mentioned above, although it is recognized that the toughness of cermets is improved by making the carbonitrides, which are hard dispersed phases, finer,
Cermet tools manufactured by grinding this material tend to break more easily than conventional cemented carbide tools, and are inferior in toughness, making them ideal for applications such as drills and end mills where breakage can be a fatal defect. It has hardly been put into practical use.

In view of the above-mentioned conventional circumstances, it is an object of the present invention to provide a strong cermet tool that has further improved toughness and can be used as a drill, end mill, etc. where breakage would be a fatal defect. It is something.

[Means for solving problems]

In order to achieve the above object, the method for manufacturing a strong cermet tool of the present invention includes a hard dispersion of carbonitride of titanium, tungsten, and at least one transition metal selected from the group consisting of molybdenum, niobium, and tantalum. phase,
After a cermet tool is produced by grinding from a cermet bonded with a metal binder phase containing nickel and cobalt, the cermet tool is annealed at a temperature of 700 to 1300 C for 15 minutes to 2 hours.

The above-mentioned cermet itself is manufactured by a conventionally known method. For example, powders of T1 and W and nitrides, carbides, oxides, etc. of each transition metal are mixed with carbon powder, and the mixture is heat-treated in a N2 atmosphere. There is a method in which carbonitrides of these metals are prepared in advance, and then 3 to 40% by weight of binding metal powders such as N1 and CO are mixed with the carbonitride powder and sintered in an N2 atmosphere. By such a method, the nitrogen content of the cermet can be increased and the average particle size can be reduced to 2.0
A fine hard dispersed phase of micrometer or less can be obtained.

[Effect]

When using a sintered hard alloy such as cemented carbide or cermet as a cutting tool, it is necessary to grind it using a diamond grindstone or the like to the shape used as the tool. By this grinding process, the surface of the sintered hard alloy is 100'=
It is known that a residual compressive stress of 9.4 or more and a residual tensile stress equal to this residual compressive stress are applied inside. It is also known that this level of residual stress does not particularly affect the cutting characteristics of ordinary cermets and cemented carbides.

However, in recent cermets with increased nitrogen content, the grindability decreases as the hard dispersed phase becomes finer, so the residual stress caused by grinding this cermet significantly deviates from the conventional level. It has become clear that this large residual stress has an adverse effect on the cutting characteristics of cermet tools. In particular, it has been found that in applications such as drills and end mills where breakage is a fatal defect in the tool, this residual stress has an extremely important effect on the occurrence of breakage.

However, according to the method of the present invention, it is possible to effectively remove the residual stress caused by grinding that adversely affects the cutting characteristics of cermet tools, and it is possible to obtain strong cermet tools that do not break when used as drills or end mills. . In particular, when the average particle size of carbonitride, which is a hard dispersed phase, is 2.0 μm or less, the grindability of the cermet is extremely deteriorated.
By removing residual stress through the grinding process, the cutting characteristics of the cermet tool are dramatically improved compared to conventional tools.

The annealing conditions for the cermet tool according to the method of the present invention are 700
The cutting time is 15 minutes to 2 hours at a temperature of ~1300 C, and if either the temperature or time is below this range, no residual stress removal effect is observed, and conversely, if either the temperature or time exceeds the above range, cutting will not occur. Significant dimensional changes occur as a tool,
This must be avoided as it cannot be cut as a tool.

〔Example〕

Example 1 C powder was mixed with commercially available TiO powder (crystalline anatase type), W03 powder, and TaO powder, and the mixture was heated at 1400 °C in vacuum.
After heating to C, carbonitrides (TiTa
W) (CM) powder was obtained. The composition of this carbonitride is '0.38Ta0.05'0.07) (C0,
52N0.48) 0.95, and its average particle size is 0.
．． It was 2 μm.

Add 10% by weight of N1 powder and CO to this carbonitride powder.
After adding 1 part of C powder and mixing and pulverizing, the embossed molded body was sintered at 1420 tr in a 20 torr N gas flow. Furthermore, this sintered body was subjected to H-P treatment in Ar gas at 1380 C and 1000 atm.

The thus obtained cermet was ground with a diamond grindstone to form a solid twist drill (model number MDS 105 Sr, manufactured by Sumitomo Reiki Industries) with a drill diameter of 10.5 fflfi and a drill length of 89 mm.

Thereafter, this was annealed in vacuum at 1000C for 30 minutes to produce drill A of the present invention.

For comparison, Drill B1 was manufactured in the same manner as in the above example except that it was not annealed.
Drill c manufactured by Sumitomo Electric Industries, made of material 'r23A)
1 and a commercially available drill D made of cemented carbide ion-bladed with TIN were prepared, and a cutting test was conducted together with the drill A of the present invention under the following conditions.

Work material: 550S Cutting speed: 63 m/min Feed: 0.231+1l
lln'rev.

Cutting depth: 11 mm (hole punched) As a result of the cutting test using water-soluble cutting agent, Drill A was able to cut 3000 holes, while Drill B chipped at the cutting edge after 2170 holes, and Drill O Cutting edge chipped in 1980 holes, Drill D
It became impossible to cut the 2000 holes due to wear on the cutting edge.

Incidentally, a drill made of the same normal cermet as Drill C was annealed in the same manner as in the above embodiment, and then subjected to the same cutting test as above, and was able to cut 2160 holes until the cutting edge broke.

Example 2 The same cutting tests as in Example 1 were conducted on drills E- and T manufactured in the same manner as in Example 1 except that the annealing conditions were changed, and the results are summarized in the table below.

T! 2 500C 1 hour 2190 holes chipping 7 800C 1 hour 3000 holes or more G
1200t:' 1 hour 〃) (1400C
1 hour Large dimensional change Uncuttable work 1200C5 minutes
Chipping with 2060 holes: r 1200t:'
3 hours Large dimensional change Unable to cut [Effects of the invention] According to the present invention, the toughness of the cermet tool can be further improved, and the tool is strong enough to be used as a drill, end mill, etc. where breakage would be a fatal defect. We can provide cermet tools.

Applicant: Sumitomo Electric Industries, Ltd. 7. --1

Claims (2)

[Claims] (1) A hard dispersed phase consisting of a carbonitride of titanium, tungsten, and at least one transition metal selected from the group consisting of molybdenum, niobium, and tantalum is bonded with a metal binding phase containing nickel and cobalt. After producing a cermet tool by grinding the cermet, the cermet tool is heated at a temperature of 700°C to 1300°C for 15 minutes to 2 hours.
A method for manufacturing a strong cermet tool, characterized by time-annealing. (2) The method for manufacturing a tough cermet tool according to claim (1), wherein the carbonitride has an average particle size of 2.0 μm or less.