JPH09253916A - Surface coated fine grain cemented carbide end mill - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a surface coated fine grain cemented carbide end mill excellent in wear resistance and usable in a wide cutting area from low speed to high speed by covering the surface of a tough fine particle cemented carbide base material with an inner layer formed of titanium carbide nitride having high toughness, and further applying aluminum oxide having high wear resistance and fusion resistance thereon. SOLUTION: An end mill is formed by use of a fine particle cemented carbide base material formed of a coupled phase mainly containing tungsten carbide having an average particle size of about 0.2-1.0μm and about 5-15wt.% of Co, and the surface of its cutting part is coated with titanium carbide nitride, or with titanium nitride and titanium carbide nitride. The inner layer is set to have an average thickness of 0.5-3.0μm. Further, the surface of the inner surface is coated with aluminum oxide having an average thickness of 0.1-1.0μm, and the average of total thickness is set to 0.6-4.0μm. Further, the cutting edge of the end mill is subjected to a honing of 1-50μm to form a desired surface coated fine particle cemented carbide end mill.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention has a tough fine grain cemented carbide base material having an inner layer coated on the surface with titanium carbonitride or titanium nitride and titanium carbonitride, and an outer layer coated with an aluminum oxide layer. The present invention relates to a surface-coated fine-grain cemented carbide end mill having excellent wear resistance and fracture resistance.

[0002]

2. Description of the Related Art In order to improve the wear resistance of a cutting edge, a conventional surface-coated cemented carbide end mill is formed on a surface of a base material made of a cemented carbide by TiN, TiCN, (T
It is general to use an end mill in which a hard layer such as i, Al) N is coated to form a hard layer. However, the hard layer produced by the conventional coating process has a weak adhesion strength and thus lacks wear resistance. Then, as a means for further improving the adhesion strength and the wear resistance, JP-A-62-208803 has been proposed.
No. 1, a metallic Ti coating layer having an average layer thickness of 0.1 to 1 μm is formed on the surface of a hard alloy substrate made of any one of tungsten carbide based cemented carbide, titanium carbide based cermet and high speed steel. A hard coating layer having a thickness of 1 to 9 μm, and the hard coating layer having a thickness of 0.2 to 4 μm.
Disclosed is a cutting tool made of a surface-coated hard alloy, which comprises three layers of a lower layer of titanium carbide having the same, an intermediate layer of titanium carbonitride having the same 0.2 to 4 μm, and an upper layer of titanium nitride having the same 0.2 to 3 μm. Has been done. In the above conventional surface-coated hard alloy cutting tool, the peeling phenomenon at the time of cutting is improved because the adhesion strength of the hard coating layer to the substrate is improved, and the cutting performance is improved, but the wear resistance of these coating layers is improved. However, the current situation is that it cannot respond to further speeding up in recent years to improve productivity.

[0003]

SUMMARY OF THE INVENTION In order to solve the above problems, the present invention provides a high strength titanium carbonitride having a vertically elongated crystal structure on the surface of a tough fine grain cemented carbide base material. A surface that can be used in a wide cutting range from low speed to high speed by coating a layer, and by coating the outer layer with aluminum oxide that has excellent adhesion resistance and good adhesion with the titanium carbonitride. It is an object of the present invention to provide a coated fine cemented carbide end mill.

[0004]

In order to achieve such an object, the surface-coated fine-grain cemented carbide end mill according to the present invention is characterized in that the surface of an end mill made of fine-grain tungsten carbide-based cemented carbide is used. , Titanium carbonitride or an average film thickness of 0.5 to 3.0 μm composed of titanium nitride and titanium carbonitride
And an outer layer composed of an aluminum oxide having an average film thickness of 0.1 to 1.0 μm, and an average total film thickness of 0.6 to 4.0 μm, The end mill cutting edge portion is subjected to honing of 1 to 50 μm, and the invention according to claim 2 is characterized in that the crystal structure of the titanium carbonitride layer in the inner layer is a vertically elongated crystal structure or a granular crystal structure. The present invention according to claim 3 is characterized in that the cemented carbide base material comprises tungsten carbide having an average grain size of 0.1 to 1.0 µm and a binder phase of 5 to 15 pieces. Wt% Co, Cr, V, T
The present invention relates to a surface-coated fine cemented carbide end mill having a composition in which one or two carbides of a and Nb are blended in an amount of 0.3 to 1.5% by weight.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION As described above, aluminum oxide having high wear resistance and welding resistance is formed on the surface of a tough fine-grain cemented carbide base material and on an inner layer made of titanium carbonitride having high toughness. By coating the surface-coated fine-grained carbide end mill with wear resistance, it can be used in a wide cutting range from low speed cutting to high speed cutting, and the life can be greatly extended, so productivity is greatly improved. It has advantages.

In the present invention, an end mill is formed by using a fine cemented carbide base material composed of tungsten carbide having an average particle size of 0.3 to 1.0 μm and a binder phase containing 5 to 15% by weight of Co as a main component. The surface of the cutting edge is coated with titanium carbonitride or titanium nitride and titanium carbonitride. The thickness of the inner layer is 0.
5 to 3.0 μm. Further, the surface of the inner layer is coated with aluminum oxide having an average film thickness of 0.1 to 1.0 μm, and the average of the total film thickness is set to 0.6 to 4.0 μm. Further, the cutting edge of the end mill is subjected to honing of 1 to 50 μm to form a desired surface-coated fine-grain cemented carbide end mill.
Incidentally, the crystal structure of titanium carbonitride in the inner layer has a crystal structure which changes from a vertically grown crystal structure or a granular crystal structure containing at least W and Co among the constituents of the substrate to a vertically grown crystal structure. . The average grain size of the fine-grained tungsten carbide is set to 0.1 to 1.0 μm, because when the average grain size is smaller than 0.1 μm, the thickness of the binder phase becomes too thin and the fracture resistance decreases. If it exceeds, the hardness is lowered and desired wear resistance cannot be obtained. In addition, the binder phase contains Co as a main component and W and C as a solid solution, and the addition amount of one or more carbides of Cr, V, Ta and Nb is 0.3 to 1.5 wt. If the amount is less than 0.3% by weight, the desired wear resistance cannot be obtained because the grain growth suppressing effect is poor, and if it is more than 1.5% by weight, the amount of precipitates increases and the fracture resistance decreases. The amount of the binder phase is set to 5 to 15% by weight because when the amount is less than 5% by weight, the strength is low and the desired chipping resistance cannot be obtained, and when the amount is more than 15% by weight, the desired abrasion resistance cannot be obtained. This is because deformation occurs when cutting at high speed. The average thickness of the inner layer made of titanium nitride or carbonitride is 0.5 to 3.0 μm, preferably 0.8 to 3.0 μm.
The reason for setting the thickness to 1.2 μm is that if it is thinner than 0.5 μm, the intended wear resistance cannot be obtained, and if it is thicker than 3.0 μm, the coating film at the cutting edge peels or chips. The average thickness of the outer layer of aluminum oxide is set to 0.1 to 1.0 μm, preferably 0.1 to 0.3 μm, because the effect of welding resistance cannot be obtained when the thickness is less than 0.1 μm, This is because if it is thick, peeling occurs. Average total film thickness of 0.6 to 4.0
μm, preferably 0.9 to 1.5 μm is 0.6
If it is thinner than μm, the desired wear resistance cannot be obtained, and it is 4.0 μm.
This is because if the thickness is thicker, peeling and chipping of the coating film due to the tensile residual stress in the coating film caused by the difference in thermal expansion coefficient between the base material and the coating film occur. The honing amount of the cutting edge of the end mill is 1 to 50 μm, preferably 10 to 20 μm.
The reason is that if the honing amount is less than 1 μm, the coating layer locally thickens at the tip of the end mill and the η phase precipitates more, and if the honing amount exceeds 50 μm, the cutting resistance increases. This is because it becomes large and chipping occurs.

[0007]

EXAMPLES The substrates and cores shown in Tables 1, 2, and 3, respectively.
A square-type end mill having a blade edge diameter of 10 mm, a helix angle of 45 °, and a two-blade blade was manufactured by subjecting to cutting and honing. For comparison, the base material shown in Table 1 was coated with the coating material shown in Table 4 by the ion plating method. At this time, the amount of honing was 10 μm. A cutting test was performed on these end mills under the following conditions, and the results are shown in Tables 3 and 4. The number of defects was 10 out of 10 and was defined as 1 when one of the two blades was damaged. The amount of wear of the outer peripheral blade was set to the maximum amount of wear, including the portion where chipping occurred. Cutting speed: 120m / min. Feed per blade: 0.04mm / blade Cutting depth: 15mm Cutting width: 1mm Work material: S50C coolant: Water-soluble downcut Cutting length: 30m

[0008]

[Table 1]

[0009]

[Table 2]

[0010]

[Table 3]

[0011]

[Table 4]

[0012]

INDUSTRIAL APPLICABILITY The present invention comprises, on the surface of a tough fine-grain cemented carbide base material, titanium carbonitride having high toughness, or an inner layer coated with titanium nitride and the high-toughness titanium carbonitride, and coating the inner layer. The layer has a crystal structure that changes from a vertically grown crystal structure or a granular crystal structure to a vertically grown crystal structure, and the outer layer is coated with aluminum oxide having excellent oxidation resistance. It was possible to obtain a surface-coated fine-grain cemented carbide end mill with improved wear resistance and wear resistance.

Claims (3)

[Claims] 1. An average film thickness of 0.5 to 3.0 μm made of titanium carbonitride or titanium nitride and titanium carbonitride on the surface of an end mill composed of fine-grained tungsten carbide based cemented carbide.
and an outer layer made of aluminum oxide having an average film thickness of 0.1 to 1.0 μm and having an average total film thickness of 0.6 to 4.0 μm. A surface-coated fine-grain cemented carbide end mill, characterized in that the end mill cutting edge portion is subjected to honing of 1 to 50 μm. 2. The surface-coated fine grain cemented carbide end mill according to claim 1, wherein the crystal structure of the titanium carbonitride layer in the inner layer is changed from a vertically elongated crystal structure or a granular crystal structure to a vertically grown crystal structure. Surface-coated fine-grain carbide end mill characterized by having a structure. 3. The surface-coated fine grain cemented carbide end mill according to claim 1, wherein the cemented carbide base material has an average grain size of 0.1.
.About.1.0 .mu.m tungsten carbide and 5 to 15 binder phases
A surface-coated fine-grain cemented carbide end mill having a composition in which 0.3% to 1.5% by weight of Co and 1 or 2 types of carbides of Cr, V, Ta, and Nb are blended.