JPS61230803A - Cutting tool - Google Patents

Abstract

PURPOSE:To improve the cutting performance and the service life of tool by making the cutting tool while covering the surface of sintered body containing high pressure phase boron nitride with specific ceramic. CONSTITUTION:WC-Co 10wt% cermet having same planar dimension is sintered to the underface of high pressure boron nitride sintered material containing 48vol% of wurtzite structure type boron nitride, 36vol% of TiN ad 16vol% of Al. Then the sintered material is silver brazed to the edge to form a throw away tip. Then TiN is chemically covered (CVD) by 3mu over the surface of said tip thus to produce a cutting tool.

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a cutting tool, and more particularly to a cutting tool having a cutting edge equipped with a sintered body containing high-pressure phase boron nitride, and the surface of the cutting edge being coated with a specific material. The present invention relates to a cutting tool that can cut mainly steel materials with higher efficiency and longer life than a conventional cutting tool whose cutting edge is equipped with a sintered body containing uncoated high-phase boron nitride.

Here, the sintered body containing high-pressure phase boron nitride is a sintered body containing 1 cubic crystal boron nitride (hereinafter referred to as OBN), wurtzite m boron nitride (hereinafter referred to as WBN), or a sintered body containing both OBN and WBN. It is a sintered body included in the composition.

C. Conventional Techniques Conventionally, cutting tools whose cutting edges are equipped with sintered bodies containing high-pressure phase boron nitride have been known. It is also known that it can cut ordinary steel, cast iron, and cast M with high efficiency, high precision, and long life.

-1 In recent years, cutting tools with a cemented carbide cutting edge whose surface is covered with a thin film of aluminum oxide, titanium nitride, titanium carbide, etc. have come into use, and are improved mainly in terms of service life compared to those without coating. has been done. However, there is no known cutting tool whose cutting edge is coated with high-pressure phase boron nitride and whose surface is covered with such a material.

(Problem to be solved by the invention) A cutting tool whose cutting edge is equipped with a sintered body containing high-pressure phase boron nitride is its main raw material (both when synthesizing 3BN+WBN and when manufacturing a sintered body). Because it uses ultra-high pressure, manufacturing costs and product prices are high, and despite its superior performance, it is not widely used.

Furthermore, cutting tools whose cutting edges are coated with cemented carbide do not have sufficient cutting performance or service life.

It is urgent to advance industrial technology by popularizing cutting tools whose cutting edges are equipped with sintered bodies containing high-pressure phase boron nitride, which have the excellent performance described above. Since lowering the temperature is a problem related to manufacturing technology in general, there are various difficulties in solving it quickly.

Another possible solution is to reduce the tool cost per unit of machining by significantly improving performance, even if the manufacturing cost increases slightly.

The present inventors have repeatedly conducted various experimental and theoretical studies from this viewpoint.

High-pressure phase boron nitride has a hardness second only to diamond, and it has been conventionally thought that coating the surface with ceramics having a lower hardness would not be very effective. In a sense, this observation is correct; coating a surface with an unsuitable ceramic has no effect at all, and in some cases can even have the opposite effect, reducing the cutting tool's sharpness and shortening its life. However, as a result of the research conducted by the present inventors, coating the surface with a certain ceramic has an excellent effect of extending the life, and when cutting under the same conditions, compared to the case without coating. , 170% to 56
The present invention was achieved based on the knowledge that the lifespan is extended by 0% or more.

c) Means for Solving Problems) The present invention provides a cutting tool having a sintered body containing a high-pressure phase boron nitride at its cutting edge, in which the surface of the sintered body containing a high-pressure phase boron nitride is coated with titanium nitride, titanium carbide and titanium carbide. A cutting tool characterized by being coated with one or more q materials selected from the group consisting of aluminum oxide, sulfur oxide, and tantalum carbide. be.

In the cutting tool of the present invention, the specific material covering the surface of the cutting edge is selected from titanium nitride, titanium carbide, and aluminum oxide.

Titanium nitride (hereinafter referred to as TiN) has excellent adhesion to high-pressure phase boron nitride and exhibits a lubricating effect during cutting.
In addition, aluminum oxide (hereinafter referred to as Al2O8) is
When cutting cast iron, titanium carbide (hereinafter referred to as T1C) exhibits excellent wear resistance, and although it is inferior to TiH in terms of lubricity, it has superior hardness, so it can be coated by taking advantage of these properties. You can choose the material.

Additionally, in order to increase the effectiveness of the coating, it may be effective to coat multiple layers of different materials, but which coating materials should be layered in what thickness and in what order should be determined based on the characteristics described above. It can be set by several experiments with consideration.

In addition to the above materials, silicon oxide, yttrium oxide,
Indium oxide, titanium oxide, chromium nitride, aluminum nitride, tantalum nitride, zirconium nitride, tantalum carbide, vanadium carbide.

There are chromium carbide, zirconium carbide, etc., but they have some problems such as low strength and hardness of the coating, adhesion with high-pressure phase boron nitride, and heat resistance, and are not suitable for the cutting tool of the present invention. However, TiN.

Tantalum carbide (hereinafter Ta
It was found that good effects were obtained with the coating coated with C.

In the present invention, the method of coating the surface of a sintered body containing high-pressure phase boron nitride with a specific ceramic is a chemical coating method (
There are two methods: NC1VD (hereinafter referred to as NC1VD) and physical coating method (hereinafter referred to as PVD). For the former, chemical reactions are mainly used, and for the latter, methods such as vapor deposition, ion blating, sputtering, and plasma methods are used. There is,
All of them have advantages and disadvantages, so their characteristics and application methods can be found in "Ceramic Materials Technology Collection", Ceramic Materials Technology Collection Editorial Committee Kinsen, published by Industrial Technology Center, 6.
As described on page 05-617 (1979),
2.8 Based on the examples in this specification for practical application
Conditions etc. can be easily set by conducting experiments.

Further, the cutting tool to which the present invention is applied can be used for any purpose as long as it uses a sintered body containing high-pressure phase boron nitride.
It can be of any shape, such as a cutting tool, indexable tip, drill, end mill 7 rice cutter, reamer, etc.
It can be applied to any jig such as a polar bite.

(Effect) In the case of conventional cutting tools made of cemented carbide or high-speed steel, the cutting performance and performance of conventional cutting tools made of high-speed steel are poor even when coated with a thin film, which has excellent properties when the hardness of the tool material of the coated base material is low. While the lifespan is still insufficient, the cutting tool of the present invention coats the surface of a sintered body containing a high-pressure phase boron nitride with a specific ceramic,
It has excellent cutting performance and at the same time can significantly extend the cutting life. The reason for this is not clear, but if a thin film is coated on the surface of a sintered body containing high-pressure boron nitride, which has the highest hardness other than diamond, even if it has a lower hardness, it will be backed by a material with extremely high hardness. It is thought that this has brought about excellent effects.

Additionally, titanium and aluminum are known to have an excellent affinity for high-pressure phase boron nitride and are often used as sintering aids for high-pressure phase boron nitride; When coated on the surface of a sintered body, the coated material increases its affinity with high-pressure phase boron nitride at the atomic level, which allows it to withstand severe mechanical and thermal stress during cutting without peeling off from the surface. This is thought to have the effect of extending the lifespan. In particular, TiN and T10 are titanium compounds, and 1,0. It is thought that the excellent effect is produced by the action resulting from the above-mentioned characteristics.

In addition, even if it is not suitable as a coating material, in the case of TaO, it can be coated with TiN, Ti (3, 3, o, 2), or a multilayer coating selected from them. good effects can be obtained.

Furthermore, the reason why it has a longer life compared to conventional uncoated sintered bodies containing high-pressure phase boron nitride is thought to be because the coating material allows it to withstand mechanical stress and thermal stress even more.

(Example) The present invention will be explained below with reference to Examples and Comparative Examples.

Example 1 Thickness Q of a high-pressure phase nitrided porcelain sintered body containing 48% by volume of WBN, 16% by volume of RI, Na, and 16% by volume of aluminum.
It is 9m long, has 5 fins on each side, has an apex angle of 60°, and has a tungsten carbide (hereinafter referred to as ?1!Wa)-cobalt (hereinafter referred to as CO) layer on the bottom surface with a thickness of 2.5 ms. A sintered cermet with the same planar dimensions was attached to the cutting edge using silver solder, and an 8 μm thick TiN Ti:OV D was placed on the surface of a TNG2132 type indexable tip.
A cutting tool coated with was fabricated and subjected to a cutting test.

The material to be cut is 5KD11fJi tempered to Rockwell hardness O scale 6δ, and has a cylindrical shape with an external diameter of 150 mm and a length of 500 mm, and the circumference is W! (Hereafter referred to as v'
l 00-8 Ell / min % depth of cut Q, 5
m.

Cutting was performed at feed rate Q, ltx/reV. As a result, it withstood continuous repeated cutting for a total of one hour, and the flank wear of the cutting edge was Q, 113 m5.

Comparative Example 1 A test similar to the cutting test performed in Example 1 was conducted. The material and shape of the cutting tool were the same as those in Example 1, but without TiH coating. As a result, after a total cutting time of 80 minutes, the surface roughness of the workpiece deteriorated so much that subsequent cutting could no longer be performed. At that point, flank wear of the cutting edge was measured and showed wear of os6+++s.

Example 2 0BN! ! 8 volume%, :W□BN5', 8 volume%, 1"
surface of a sintered body containing high-pressure phase boron nitride of a drill whose cutting edge is equipped with a sintered body containing high-pressure phase boron nitride consisting of if3/Ni, 8.9 volume argon, Al: miniram l), 8 volume % First, an 8 μm thick TIN was coated by OVD, and then a spm muj, O was coated thereon. The shape of the drill is Tokkai Sho! 19-81010, which has a V-shaped cutting edge at the center of the cutting edge at the tip of the drill, and the diameter of the drill is 1411111. The opening of the tip of the V-shaped cutting blade was s and am, and the angle of the V-shaped valley was 60'.

For drilling, a Fo-sa type cast iron fourk was prepared as the material to be machined, and a hole with a depth of 40 m111 was machined 1000 times using a mail machine. The processing conditions are 1780 rotations (V = 78.2m/min), feed Q 0g
sa/reV. These machining conditions are equivalent to 4 to 6 times the recommended working conditions for high-speed steel drills. 5l, 0.
No part of the coating was found to have exposed the TIN of the underlying coating, and it was determined that processing could continue in good condition.

Comparative Example 2 A test similar to Example 2 was conducted using a drill with the same shape as that used in Example 2, with TiN, mulch, and 0. This was done with an uncoated drill.

When the cutting edge was inspected after 1000 machining operations,
Several small chippings were observed at the boundary between the relief face and the rake face, and it was determined that the product could not withstand further processing.

Example 8 A chip having the same shape as that used in Example 1 was prepared.

Ta! The coating was made by coating TiO with a thickness of 5 μm, and then coating TIN with a thickness of 8 μm by applying an ion blasting method.

As a rigid material, a width 2IIs and a depth 1, jj are attached to the side surface of a cylindrical type 801415 steel with an outer diameter of 2Is and a length of 180.
A specimen was prepared in which four grooves of m diameter were provided at equal intervals parallel to the central axis of the cylinder, and the hardness was 58 on the Rockwell hardness C scale.

The above workpiece material is V -219,8m/win, feed 0
．． When inspecting the cutting edge after cutting 850 pieces at 2wg/r6y and a cutting depth of 0.5M, it was found that the coating was slightly worn and the surface of the sintered body containing high-pressure phase boron nitride was exposed. There was no chipping or major wear, and it was determined that continued cutting was possible.

Comparative Example 8 A test similar to Example 8 was conducted using the same workpiece and cutting conditions as the indexable tip, which was the same except that it was not coated. As a result, the surface roughness of the cut surface of the work material became extremely rough after 182 pieces were cut, so the test was stopped and the cutting edge was inspected. In addition, chipping is thought to have developed at the boundary between the flank face and rake face.Width Q: 5m, depth: 0.18wl1
A large size of the s1 depth 0.8 sieve was found to have worn out, and it was determined that cutting the plate diameter was impossible.

A test similar to the cutting test conducted in Comparative Meeting Example 1 was conducted. Ta!
The cutting tool has the same shape and is made of WC94094 weight%6.
made of cemented carbide with a composition of % by weight, and Example 1
The tool was coated in the same way as the tool. As a result, the cutting edge broke off when the side surface of the material was cut over a length of 150 mm. When the state of the defect was examined, it was found that the coating near the fracture surface had partially peeled off. The cutting time was 7 minutes, which was only about 1/9 of the cutting time in Example 1, and it was determined that further cutting was possible in Example 1, so it is thought that the actual service life ratio is lower. It will be done.

Comparative Example 5 Same shape as the drill used in Example 2, but entirely made of WO94
A cutting test was conducted using a material made of cemented carbide having a composition of 8% by weight and 8% by weight of Oo and coated with the same coating as in Example 2. When the material to be cut and the conditions were the same as in Example 2, the test results showed that 88 holes were cut at the point where they were machined.
Further cutting is no longer possible.

Comparison N6 A test similar to the cutting test of Example 8 was performed, except for the material of the chip, and the entire chip was tested? 1080% by weight, 15% by weight of nickel,
Change to cermet consisting of molyb weight% weight curse composition,
The experiment was carried out using a chip coated with a coating similar to that of Example 8. As a result, the cutting edge broke off after cutting 48 pieces of workpiece material, making further cutting impossible. This cutting number is
The number of pieces cut in Example 8 is 1/8 or less, and Example 8
In contrast, it was determined that further cutting was possible in the case of
It is understood that the ratio is lower.

Comparison N7 Only the coating of the cutting tool used in Example 1 was coated with tantalum nitride [hereinafter TaN] with a thickness of 8 μm by OVD.
A cutting test similar to that in Example 1 was conducted using the same material as in Example 1. As a result, the cutting edge broke off after cutting the work material for 8 minutes, making it impossible to carry out further cutting. It was observed that the TaN coating had peeled off in the vicinity of the defective portion, and it was determined that the coating lacked compatibility with the sintered body containing high-pressure phase boron nitride.

Example 4 The first coating of the tool used in Comparative Example) was 8 μm thick.
A cutting test similar to that in Example 1 was conducted using a tool in which the surface of a sintered body containing high-pressure phase boron nitride was coated with TiN and TaO was further coated with a thickness of 8 μm. As a result, it withstood repeated cutting for a total of one hour without any problems, and the flank wear of the cutting edge was 0.1J? It was m.

As described above in detail, the present invention is an industrially useful invention that can extend the life of a cutting tool whose cutting edge is equipped with a sintered body containing high-pressure phase boron nitride.

Claims (1)

[Claims] 1. In a cutting tool equipped with a sintered body containing high-pressure phase boron nitride at the cutting edge, the surface of the sintered body containing high-pressure phase boron nitride is coated with one type selected from the group consisting of titanium nitride, titanium carbide, and aluminum oxide. A cutting tool characterized by being coated with two or more types of materials, or coated with those coating materials and further coated with tantalum carbide.