JP2003048105A - Surface coated cemented carbide cutting tool having coating layer exhibiting superior chipping resistance - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a surface coated cemented carbide cutting tool whose coating layer exhibits superior chipping resistance. SOLUTION: The coating layer is constituted by (a) a lower tough layer having an average layer thickness of 3 to 20 μm, which is formed by one or two layers of Ti compound layers composed of a carbide layer, a nitride layer, a carbnitride layer, a carboxide layer, a nitroxide layer and a carbonitroxide layer of Ti, (b) an upper hard layer having an average layer thickness of 0.5 to 15 μm, which is formed by a porous aluminum oxide evaporation layer having prosity of 5 to 30% in measurement based on the longitudinal section texture observed by a scan type electron microscope, and (c) a surface reinforcement layer having an average layer thickness of 0.5 to 5 μm, which is formed by titanium nitride. The thus formed coating layer is chemically and/or physically evaporated on the surface of a tool base formed by a tungsten carbide base cemented carbide or carbonitride titanium base thermet in this surface coated cemented carbide cutting tool.

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an intermittent cutting of various steels and cast irons, in particular, for heavy cutting such as high cutting and high feed to which high mechanical and thermal shocks are applied. Surface-coated cemented carbide cutting tool that provides excellent chipping resistance even when performed under cutting conditions (hereinafter referred to as coated cemented carbide tool)
It is about. 2. Description of the Related Art Generally, a cutting tool includes a throw-away tip which is removably attached to a tip of a cutting tool for turning or planing of a work material such as steel or cast iron. There are drills and miniature drills used for drilling and cutting work materials, and solid-type end mills used for face milling, grooving, shoulder processing, etc. of the work material. A throw-away end mill tool or the like which is freely mounted and performs cutting in the same manner as the solid type end mill is known. Conventionally, as a cutting tool, (a) Ti carbide (hereinafter, referred to as “tool base”) is formed on the surface of a tool base (hereinafter simply referred to as “tool base”) composed of tungsten carbide-based cemented carbide or titanium carbonitride-based cermet. TiC) layer, nitride (hereinafter also shown as TiN) layer, carbonitride (hereinafter shown as TiCN) layer, carbon oxide (hereinafter shown as TiCO) layer, nitride oxide (hereinafter shown as TiNO) ) Layer and a carbonitride (hereinafter referred to as TiCNO) layer
a lower tough layer composed of one or more layers of the i-compound layer and having an average layer thickness of 3 to 20 μm, (b) an aluminum oxide (hereinafter referred to as Al ₂ O ₃ ) layer,
And an upper hard layer having an average layer thickness of 0.5 to 15 μm,
There is known a coated cemented carbide tool obtained by subjecting the coating layer composed of (a) and (b) to chemical vapor deposition and / or physical vapor deposition. [0004] In recent years, the performance of cutting equipment has been remarkably improved, and on the other hand, there has been a strong demand for labor saving, energy saving, and further cost reduction in the cutting work. Tends to require versatility that is not affected by cutting conditions as much as possible.However, in the above-mentioned conventional coated carbide tools, this is used for continuous or interrupted cutting under ordinary conditions such as steel and cast iron. If there is no problem, but if this is used for cutting that performs intermittent cutting under heavy cutting conditions such as high depth of cut and high feed, due to high mechanical and thermal shock generated during cutting, the coating At present, chipping (small chipping) easily occurs at the cutting edge portion of the layer, and as a result, the service life is reached in a relatively short time. [0005] Accordingly, the present inventors have proposed:
From the above-mentioned point of view, paying attention to the conventional coated carbide tools described above, the coated carbide tools exhibit excellent chipping resistance even when intermittent cutting such as steel or cast iron is performed under heavy cutting conditions. As a result of conducting research to develop (a), using a normal chemical vapor deposition apparatus, the above-mentioned tool substrate surface was coated with a reaction gas composition of AlCl ₃ : 0.01 to 0.2% by volume, H
_{Cl: 0.01~0.2%, CO 2:} 0.01~0.5
%, SiCl ₄ : 10 × 10 ⁻⁴ to 2 × 10 ⁻³ %, H2:
Remaining, and reaction atmosphere temperature: 900 to 1200
° C, reaction atmosphere pressure: 4 to 27 KPa, and A
When the l ₂ O ₃ layer is formed, as a result, an Al ₂ O ₃ layer having a porous structure in which a large number of vacancies are present is formed, and the porosity of the porous Al ₂ O ₃ deposited layer is increased. Can be adjusted mainly by adjusting the content ratio of SiCl ₄ , which is a reactive gas component, and the higher the content ratio, the higher the porosity. (B) In the above-mentioned conventional coated cemented carbide tool, the Al ₂ O ₃ layer forming the coating layer has high high-temperature hardness and excellent heat resistance, but has sufficient impact resistance. Therefore, chipping is likely to occur in the coating layer, especially in intermittent cutting under high cutting conditions in which high mechanical and thermal shocks are applied, whereas the Al in the coating layer of the conventional coated carbide tool is used. Instead of the ₂ O ₃ layer, the porous Al ₂ O ₃ vapor-deposited layer obtained in the above (a) was measured for its porosity based on a vertical cross-sectional structure observed by a scanning electron microscope, and the porosity was 5 to 5. The porous Al ₂ O ₃ vapor-deposited layer is formed after adjusting the porosity within a range of 30% to a predetermined porosity. When a TiCN layer having strength and toughness is formed as a layer,
In this result the coating cemented carbide, porous Al ₂ O ₃ deposition layer whose surface is reinforced by the TiCN layer is sufficiently absorb relieve mechanical and thermal shock generated at the time of cutting, and the porous Al ₂ Because the TiCN layer sufficiently reinforces the O ₃ vapor deposition layer, the coating layer has excellent chipping resistance and exhibits excellent cutting performance over a long period of time. The research results shown in (a) and (b) above were obtained. The present invention has been made based on the results of the above-described research, and (a) TiC
Layer, TiN layer, TiCN layer, TiCO layer, TiNO layer,
And a lower tough layer composed of one or more layers of a Ti compound layer composed of a TiCNO layer and having an average layer thickness of 3 to 20 μm. (B) Based on a longitudinal sectional structure observed by a scanning electron microscope. It consists of a porous Al ₂ O ₃ deposited layer with a porosity of 5 to 30% as determined by measurement.
An upper hard layer having an average layer thickness of 5 to 15 μm, (c) T
a surface reinforcing layer composed of an iCN layer and having an average layer thickness of 0.5 to 5 μm, and a coating layer formed by chemical vapor deposition and / or physical vapor deposition of the coating layer composed of the above (a) to (c). This is a feature of coated carbide tools that exhibit excellent chipping resistance. Next, the coating layer constituting the coated carbide tool of the present invention will be described. (A) Lower toughness layer The Ti compound layer of the lower toughness layer has the effect of improving the strength and toughness of the coating layer and improving the adhesion between the layers. When the average layer thickness is less than 3 μm, the above effect is obtained. If the desired improvement effect cannot be obtained, on the other hand, if the layer thickness exceeds 20 μm, the coating layer is liable to be thermoplastically deformed, and as a result, uneven wear, which causes shortening of the service life of the cutting edge, occurs. Therefore, the average layer thickness was determined to be 3 to 20 μm. (B) Upper Hard Layer The porous Al ₂ O ₃ vapor-deposited layer of the upper hard layer is such that the Al ₂ O ₃ phase which is the main component thereof has a high high-temperature hardness and excellent heat resistance as described above. As a result, the coating layer exhibits excellent wear resistance, and a large number of pores dispersed and distributed in the Al ₂ O ₃ phase absorb and relax thermal and mechanical shocks, so that the coating layer is excellent. It has the effect of exhibiting chipping resistance. Therefore, if the porosity is less than 5%, a sufficient effect of absorbing and absorbing shock cannot be obtained. On the other hand, if the porosity exceeds 30%, the strength is sharply reduced, causing chipping. The porosity is 5-30%
It was decided. If the average layer thickness is less than 0.5 μm, the effect of the porous Al ₂ O ₃ vapor-deposited layer cannot be satisfactorily ensured. On the other hand, if the average layer thickness exceeds 15 μm, the strength of the coating layer itself will increase. Further, since the toughness rapidly decreases and chipping easily occurs in the coating layer, the average layer thickness is set to 0.5 to 15 μm. (C) Surface Reinforcement Layer The TiCN layer of the surface reinforcement layer has the high toughness of TiN and
Since it has the high hardness of C, it exerts the effect of sufficiently reinforcing the strength reduction due to the formation of pores in the porous Al ₂ O ₃ deposited layer, but if the average layer thickness is less than 0.5 μm, Since the average layer thickness of 5 μm is sufficient for the above purpose, while the average layer thickness of 5 μm is sufficient for the above purpose, the average layer thickness is set to 0.5 to 5 μm. Next, the coated carbide tool of the present invention will be specifically described with reference to examples. WC powder, TiC, each having an average particle size of 1 to 3 μm, as raw material powders
Powder, ZrC powder, VC powder, TaC powder, NbC powder, Cr ₃ C ₂ powder, TiN powder, TaN powder, and Co powder were prepared, and these raw material powders were blended into the composition shown in Table 1 to form a ball mill. For 72 hours,
After drying, it is pressed into a green compact at a pressure of 1.5 × 10 ⁸ Pa, and this green compact is heated to 1400 ° C. in vacuum at a temperature of 1400 ° C.
After sintering under the condition of holding time, and after sintering, R: 0.
Honing process of 05, ISO standard, CNMG1
Tool bases A1 to A8 made of a WC-based cemented carbide having a chip shape of 20412 were formed. In addition, as raw material powders,
TiCN having an average particle size of 2 μm (by mass ratio TiC /
(TiN = 50/50) powder, Mo ₂ C powder, ZrC powder, NbC powder, TaC powder, WC powder, Co powder, and Ni powder were prepared, and these raw material powders were blended into the composition shown in Table 2. After wet-mixing with a ball mill for 24 hours and drying, the mixture is pressed into a green compact at a pressure of 9.8 × 10 ⁷ Pa, and the green compact is heated in a nitrogen atmosphere of 1.3 × 10 ³ Pa at a temperature of: Sintering was carried out at 1540 ° C. for 1 hour, and after sintering, the cutting edge was subjected to a honing process of R: 0.03, and a tool base B1 made of a TiCN-based cermet having a tip shape of ISO standard CNMG120412. ~ B
6 was formed. Next, the surfaces of the tool bases A1 to A8 and B1 to B6 were ultrasonically cleaned in acetone, dried, and then dried using an ordinary chemical vapor deposition apparatus. -TiCN indicates the conditions for forming a TiCN layer having a vertically elongated crystal structure described in, for example, JP-A-6-8010, and indicates the conditions for forming a coating layer having a normal granular crystal structure. Table 4
The “porous Al ₂ O ₃ ” is an abbreviation of a porous Al ₂ O ₃ vapor-deposited layer). Carbide tools 1 to 14 and conventional coated carbide tools 1 to 14 were produced, respectively. The coated carbide tools 1 to 14 according to the present invention described above.
The longitudinal section of each coating layer was observed using a scanning electron microscope for microstructure. Based on the observation results, the porous Al
_{When the} porosity of the ₂ O ₃ vapor-deposited layer was measured, it showed substantially the same value as the target porosity shown in Table 4, and these coated carbide tools 1 to 14 according to the present invention and conventional coated carbide tools 1 ~ 14
When the layer thickness of the coating layer was measured, the average layer thickness was substantially the same as the target layer thickness in Tables 5 and 6. Next, the coated carbide tools 1 to 14 according to the present invention will be described.
And conventional coated carbide tools 1 to 14; Work material: JIS SCM440, lengthwise equally spaced round bar with four longitudinal grooves; Cutting speed: 120 m / min. Notch: 3.0 mm Feed: 0.2 mm / rev. , Cutting time: 10 minutes, Dry high-cut intermittent cutting test of alloy steel under the following conditions: Work material: JIS S45C lengthwise round bar with four longitudinal grooves, Cutting speed: 100 m / min. Infeed: 1.5 mm Feed: 1.0 mm / rev. , Cutting time: 5 minutes, Dry high-feed intermittent cutting test of carbon steel under the following conditions: Work material: Round bar with four longitudinal grooves at equal intervals in the longitudinal direction of FC300, Cutting speed: 150 m / min. Infeed: 3.0 mm Feed: 0.25 mm / rev. , Cutting time: 10 minutes, Dry high-cut intermittent cutting test of cast iron under the following conditions:
In each cutting test, the maximum flank wear width of the cutting edge was measured. Table 7 shows the measurement results. [Table 1] [Table 2] [Table 3] [Table 4] [Table 5] [Table 6] [Table 7] According to the results shown in Table 7, the coated carbide tools 1 to 14 of the present invention can be used under heavy cutting conditions of steel and cast iron with extremely high thermal and mechanical shocks. Even in intermittent cutting, the coating layer has excellent mechanical and thermal shock resistance due to the porous Al ₂ O ₃ vapor deposition layer constituting the coating layer. On the other hand, in conventional coated carbide tools 1 to 14 in which the coating layer comprises a lower tough layer of a Ti compound layer and an upper hard layer of an Al ₂ O ₃ layer, the coating layer exhibits intermittent cutting under the heavy cutting conditions. In cutting, chipping occurs in the coating layer,
It is clear that the service life is reached in a relatively short time. As described above, the coated cemented carbide tool of the present invention involves not only continuous cutting and interrupted cutting under ordinary conditions such as various types of steel and cast iron, but also involves particularly high mechanical and thermal shocks. Even when used in intermittent cutting under heavy cutting conditions, it exhibits excellent cutting performance over a long period of time, so it can respond satisfactorily to the versatility of cutting and further saves on cutting. It is possible to achieve energy saving, energy saving, and further cost reduction.

   ────────────────────────────────────────────────── ─── Continuation of front page    F-term (reference) 3C037 CC02 CC04 CC09 CC11                 3C046 FF03 FF05 FF10 FF17 FF19                       FF25                 4K029 AA04 BA41 BA43 BA44 BA54                       BA55 BA60 BB02 BC00 BD05                       EA01                 4K030 BA18 BA35 BA36 BA38 BA41                       BA43 BB12 JA01 LA01 LA22

Claims (1)

Claims 1. A tool base made of a tungsten carbide-based cemented carbide or a titanium carbonitride-based cermet,
(A) one or more layers of a Ti compound layer consisting of a Ti carbide layer, a nitride layer, a carbonitride layer, a carbonate layer, a nitrogen oxide layer, and a carbonitride layer; and 3 ~
A lower tough layer having an average layer thickness of 20 μm, (b) a porous aluminum oxide vapor-deposited layer having a porosity of 5 to 30% as measured based on a longitudinal sectional structure observed by a scanning electron microscope, and An upper hard layer having an average layer thickness of 0.5 to 15 μm, (c) a surface reinforcing layer comprising a titanium carbonitride layer and having an average layer thickness of 0.5 to 5 μm; Chemical vapor deposition and / or
Alternatively, a cutting tool made of a surface-coated cemented carbide in which a coating layer characterized by physical vapor deposition exhibits excellent chipping resistance.