JPH06320305A - Ceramic tool for groove turning work - Google Patents

Abstract

PURPOSE:To improve high strength, high toughness and wear resistance by containing one or two kinds or more of SiC whiskers and Ti carbide/nitride and two kinds or more of yttrium oxide, zirconium oxide and aluminum oxide. CONSTITUTION:By weight %, respectively 10 to 30% SiC whisker, 5 to 30% one or two kinds or more of carbide, nitride and carbide/nitride of Ti and 0.5 to 2% two kinds or more of yttrium oxide, zirconium oxide and aluminum oxide as a sinter assistant are contained, and the balance of silicon nitride, to obtain a desired ceramic tool for grooving turning work. This tool has a short edge point of 4 to 10mm width, alpha=5 deg. rake angle and beta=5 deg. clearance angle.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tool for grooving and turning a cast iron material or a heat resistant alloy.

[0002]

2. Description of the Related Art Conventionally, cemented carbide and TiC-based cermets have been used as a material for grooving and turning, mainly from the viewpoint of high toughness.
In machining (0), there is a problem that dimensional accuracy cannot be maintained due to chattering and heat generation, and since the tool life is short, development of a long-life tool has been desired.

Cemented carbide tools have a problem with heat resistance, and thermite tools have a low thermal conductivity, and the heat generated by the tool and the work material during cutting is small. At present, dimensional change is a major problem, and due to lack of wear resistance, the life is relatively short. Due to its low toughness, the application of ceramic materials to tools has been limited to relatively light load applications such as finish turning with a simple tool shape.

Therefore, ceramic tools have not been applied to heavy-duty grooving turning.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide a tool material which is required to have characteristics such as high strength, excellent wear resistance and high toughness. Is to provide.

[0006]

From the above viewpoints, the present inventors have paid attention to ceramic-based materials as the material having more heat resistance and high thermal conductivity, rather than cermet and cemented carbide. As a result of conducting research to impart high toughness and strength, excellent wear resistance and high thermal conductivity to these, inclusion of SiC whiskers as a material constituent component in these significantly improves the toughness and hardness of the material. It was found that in addition to having the effect, it is also possible to increase the thermal conductivity.

Next, one or more of Ti carbides, nitrides, and carbonitrides (hereinafter referred to as TiC, TiN, and TiCN, respectively, and collectively referred to as Ti carbonitrides) are selected. It has been found that, when contained, the strength and wear resistance can be further improved without impairing the high toughness originally possessed by the ceramic material.

The present invention has been made on the basis of the above findings, and contains SiC whiskers: 10 to 30%, one or more of carbonitrides of Ti: 5 to 30%, and yttrium oxide, Two or more of each of zirconium oxide and aluminum oxide are contained in an amount of 0.5 to 2%,
The rest is a ceramic tool for grooving turning that consists of Si ₃ N ₄ and inevitable impurities.

Further, it is characterized by being applied to a ceramic tool which exerts its power particularly in grooving turning processing having a rectangular cutting edge because of its wear resistance and heat dissipation derived from the above material (composition). is there.

Next, in the ceramic material of the present invention,
The reasons for limiting the component composition as described above and the reasons for specifying the tool edge shape will be described below.

(A) SiC whisker The SiC whisker component not only significantly improves the toughness and hardness of the material but also enhances the thermal conductivity, but if the content thereof is 10% or less, it is desired. If the above properties cannot be expressed and the content thereof exceeds 30%, the sinterability is lowered and the strength of the material is lowered, so that the content is set to 10 to 30%. Specified.

(B) Carbonitride of Ti These components include Si ₃ which is a matrix (base material).
It has the effect of significantly suppressing the grain growth of N ₄ , and as a result,
By containing these components, the strength and wear resistance of the material are remarkably improved, but if the content is less than 5%, the desired effect on the above action cannot be obtained, while the content is 30%. When it exceeds, the high temperature strength is lowered and the sinterability is also lowered, so the content thereof is set to 5 to 30%.

(C) Sintering aid Yttrium oxide, zirconium oxide, and aluminum oxide have the effects of improving the sinterability and suppressing grain growth, especially when coexisting with titanium (Ti) carbonitride.

If the content of each is less than 0.5%, the desired effect cannot be obtained, whereas if it exceeds 2%, the high temperature strength tends to decrease. It was set to 0.5 to 2%.

Further, the reason why the content of these is limited to two or more is that a sufficient effect cannot be obtained with one type,
It is necessary to add two or more kinds to the composite reinforcing material that adds both SiC whiskers and Ti carbonitride such as the material of the present invention.

When a large amount of these reinforcing materials is required and a combination of strength and wear resistance is required, three types of additions are effective.

(D) Tool shape In the cermet which is a conventional tool, the rake angle α = 6.
However, in the case of ceramics that are slightly inferior in toughness compared to cermet tools, α = 5 °, which is a small value to compensate for the lack of toughness. Further, when the rake angle is set to the end of 5 °, the sharpness is inferior, so the rake angle is set to 5 °.

On the other hand, since the clearance angle β does not particularly reflect the difference in material characteristics, it is set to 5 ° like the cermet tool. Also, the width of the tool should be variable depending on the size of the groove to be machined, but if it is 4 mm, it will be extremely difficult to machine into a tool, and if it exceeds 10 mm, the strength of the sintered body as a tool material Since there is a problem in manufacturing technology in terms of securing, it is desirable that it is less than that.

[0019]

EXAMPLES Next, the ceramic material of the present invention will be specifically described by way of examples. 20-200 as raw material powder
SiC whiskers having a predetermined length in the range of μm and a predetermined diameter in the range of 0.1 to 1.6 μm, all of which are commercially available metal oxide powders having an average particle size of 0.5 μm, and 0.7
μm Ti carbonitride powder and 0.3 μm Si ₃
First, N ₄ powder is prepared.
The mixture was blended in a predetermined ratio except for the whiskers, and acetone was added as a solvent to the blended mixture, which was mixed in a ball mill for 24 hours, dried and crushed to obtain a matrix powder.

Next, a predetermined amount of SiC whiskers was added to the above-mentioned matrix powder together with purified water, and the pH of the slurry was adjusted to the alkaline side by dropping diethylamine, and then mixed for 1 h using a ball mill to homogenize the whiskers. Dispersed. Then, ultrasonic vibration is applied to the mixed slurry, and nitric acid is added dropwise while stirring to adjust the pH to 7
Change to.

As a result, the viscosity of the slurry rapidly rises, the movement of particles is hindered, and the whiskers can be fixed in a uniformly dispersed state.

This slurry was suction-filtered to remove water, and then the dried and pulverized mixed powder was hot-press fired under the conditions of a temperature of 1770 ° C. and a pressure of 40 MPa, so that the blending composition shown in Table 1 was substantially obtained. Inventive ceramic materials 1 to 5 and comparative material 6 having the same composition
~ 7 were produced respectively.

Next, for each of the various ceramic materials obtained, Vickers hardness, transverse rupture strength, and fracture toughness values were measured for the purpose of evaluating wear resistance, transverse rupture strength, and toughness. A cutting tip having the shape of SNGN432 is cut out from the cast iron material (FC300 equivalent)
The intermittent cutting test was carried out to measure the number of impacts until failure. The results are shown in Table 1.

[0024]

[Table 1]

Further, a cutting tip having a shape as shown in FIG. 1 was cut out from a material corresponding to the material 4, and a grooving experiment with a width of 5 mm and a depth of 3.5 mm was conducted. Cutting speed is 4
It was 00 m / min. Table 2 shows the results of processing experiments including the comparative material.

[0026]

[Table 2]

From the results shown in Table 1, the present invention Si ₃
The N ₄ -based ceramic materials 1 to 5 have substantially the same high toughness as the Al ₂ O ₃ -based ceramic tool evaluated as a comparative material, and further have excellent tool performance (wear resistance).
It is clear that

Further, from the results shown in Table 2, when applied to grooving of a cast iron material, a very good finished surface was obtained, and at the same time, chattering did not occur, and the efficiency was 2.2.
It is possible to improve the product life and the life by 16.7 times.

[0029]

Since the ceramic material of the present invention has high strength and high toughness and excellent wear resistance, it is particularly useful as a cutting tool for high-speed cutting, interrupted cutting and grooving which require these characteristics. If so, it will exhibit excellent cutting performance for a remarkably long time.

[Brief description of drawings]

FIG. 1 is an explanatory view showing the shape of a grooving turning ceramic tool of the present invention.

Claims (2)

[Claims] 1. Silicon carbide whiskers as a weight percentage: 1
0 to 30%, one or more of Ti carbide, nitride, and carbonitride: 5 to 30%, and two or more of yttrium oxide, zirconium oxide, and aluminum oxide as a sintering aid. 0.5 to 2% each
A ceramic tool for grooving and turning, characterized in that it contains silicon nitride and the rest is silicon nitride. 2. A ceramic tool for grooving turning according to claim 1, which has a rectangular cutting edge having a width of 4 to 10 mm, a rake angle α = 5 ° and a clearance angle β = 5 °.