JP2007130709A - Surface coated cutting tool having hard coating layer exhibiting excellent chipping resistance in high-speed cutting of highly viscous workpiece - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a surface coated cutting tool having a hard coating layer exhibiting excellent chipping resistance in high-speed cutting of a highly viscous workpiece. <P>SOLUTION: The surface coated cutting tool is formed by coating a hard coating layer composed of a lower layer (a) and an upper layer (b) on the surface of a substrate composed of cemented carbide or cermet, by vapor deposition, wherein the lower layer (a) is a Ti compound layer having a total average layer thickness of 0.5 to 15 μm, and the upper layer (b) is composed of at least two-phase composite structure of an aluminum oxide and a vanadium oxide having an average layer thickness of 1 to 10 μm, and when two-phase composite structure of the aluminum oxide and the vanadium oxide is expressed by the composition formula: (Al<SB>2</SB>O<SB>3</SB>)<SB>1-X</SB>(VO<SB>M</SB>)<SB>X</SB>, a containing ratio (atomic ratio) of Al and V satisfies the value of M in the composition formula being 1.8 to 2.3, and the value of X being 0.03 to 0.2. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  This invention has a hard coating layer with excellent high-temperature hardness, heat resistance, and high-temperature strength, and excellent lubricity. Therefore, highly viscous work materials such as stainless steel, mild steel and chrome steel can be used at high speed. Even when cutting is performed under the cutting conditions, the frictional force between the work material and the cutting tool is reduced, and the overheat of the hard coating layer is prevented, so that the cutting chips are removed during cutting. Surface-coated cutting that forms a hard coating layer by chemical vapor deposition on the surface of a substrate made of tungsten carbide-based cemented carbide or titanium carbonitride-based cermet that exhibits excellent chipping resistance without welding to The present invention relates to a tool (hereinafter referred to as a coated tool).

Conventionally, generally on the surface of a substrate (hereinafter collectively referred to as a tool substrate) composed of a tungsten carbide (hereinafter referred to as WC) -based cemented carbide or titanium carbonitride (hereinafter referred to as TiCN) -based cermet. ,
(A) The lower layer is a Ti carbide (hereinafter referred to as TiC) layer, a nitride (hereinafter also referred to as TiN) layer, a carbonitride (hereinafter referred to as TiCN) layer, a carbon oxide (hereinafter referred to as TiCO). A Ti compound layer having a total average layer thickness of 0.5 to 15 μm, and one or more of a carbonitride oxide (hereinafter referred to as TiCNO) layer,
(B) an upper layer has an average layer thickness of 1 to 10 μm and has an α-type crystal structure in a state of chemical vapor deposition (hereinafter referred to as an Al ₂ O ₃ layer);
A coated tool formed by vapor-depositing the hard coating layer constituted by (a) and (b) above is known, and this coated tool is used for continuous cutting and intermittent cutting of various steels and cast irons, for example. That is well known.

In general, the Ti compound layer and the Al ₂ O ₃ layer constituting the hard coating layer of the above-mentioned coated tool have a granular crystal structure, and the TiCN layer constituting the Ti compound layer is improved in strength of the layer itself. For this purpose, it is formed by chemical vapor deposition in a temperature range of 700 to 950 ° C. using a mixed gas containing organic carbonitride as a reaction gas in a normal chemical vapor deposition apparatus so that it has a vertically grown crystal structure. It is also known to do.
Japanese Unexamined Patent Publication No. 6-31503 Japanese Patent Laid-Open No. 6-8010

In recent years, FA has been remarkable for cutting devices, but on the other hand, there is a strong demand for labor saving and energy saving and further cost reduction for cutting, and accordingly, cutting is performed at higher speed conditions in addition to normal cutting conditions. However, in the above-mentioned conventional coated tools, there is no particular problem when various types of steel and cast iron are machined under normal conditions. When used for cutting work materials (stainless steel, mild steel, chrome steel, etc.) under high-speed conditions, high heat generation occurs due to high-speed cutting, and Al ₂ O ₃ constituting the upper layer of the hard coating layer Due to insufficient lubricity of the layer, the hard coating layer is overheated, making it easier for the chips to weld to the cutting edge, causing chipping (small chipping), resulting in a service life in a relatively short time. is the current situation.

In view of the above, the present inventors, in particular, are coated tools that exhibit excellent chipping resistance with a high hard coating layer in high-speed cutting of highly viscous work materials such as stainless steel, mild steel, and chrome steel. As a result of conducting research, focusing on the hard coating layer that constitutes the conventional coated tool,
(1) In the conventional vapor deposition of the hard coating layer in which the lower layer is a Ti compound layer and the upper layer is an Al ₂ O ₃ layer, the upper layer is vapor-deposited under the following vapor deposition conditions (a) to (c). performed when, as a top layer, a composite structure consisting of at least two phases of aluminum oxide and vanadium oxide _{(hereinafter,} Al ₂ O 3 shown in -VO _M) that layer is deposited formed with an average layer thickness of 1 to 10 [mu] m.
(A) Reaction gas composition (volume%):
AlCl ₃ : 2.24 to 2.72%,
VCl _4: 0.08~0.56%,
CO _2: 5~7%,
HCl: 2-3%,
H ₂ : Remaining
(B) Reaction atmosphere temperature: 850 to 1050 ° C.
(C) Reaction atmosphere pressure: 5 to 25 kPa,
(2) And the composition ratio (atomic ratio) of each component Al, V, O in the composite structure (Al ₂ O ₃ —VO _M ) composed of at least two phases of aluminum oxide and vanadium oxide is aluminum oxide and vanadium oxide. A composite structure (Al ₂ O ₃ —VO _M ) composed of at least two phases of
Composition formula: (Al ₂ O ₃ ) _1-X (VO _M ) _X
In the above formula, the content ratio of Al and V (atom) satisfying the M value of 1.8 to 2.3 and the X value of 0.03 to 0.2 in the above compositional formula. A composite structure (Al ₂ O ₃ —VO _M ) layer composed of at least two phases of aluminum oxide and vanadium oxide.
(3) the Al ₂ O ₃ -VO _M layer upper layer composed of, in order exhibits a very good lubricating properties by V components contained in the upper layer, Al ₂ as an upper layer of the hard coating layer the O ₃ coated tools -VO _M layer is deposited formed of stainless steel, mild steel, when subjected to high-speed cutting of high viscosity such as chromium steel workpiece is the workpiece by heat generated during cutting and their Even when the chips are heated at a high temperature, excellent lubricity is always ensured between the cutting edge (the rake face and flank, and the cutting edge ridge where these two surfaces intersect) and the work material and chips. The adhesiveness and reactivity of the work material and cutting chips to the cutting blade surface are remarkably reduced, and the welding of cutting powder to the cutting blade is prevented. As a result, the occurrence of chipping can be prevented. What you can do.
The research results shown in (1) to (3) above were obtained.

The present invention has been made on the basis of the research results described above, and comprises a lower layer covering the surface of the substrate on the surface of the substrate made of tungsten carbide-based cemented carbide or titanium carbonitride-based cermet, In a coated tool (surface coated cutting tool) formed by coating a hard coating layer consisting of an upper layer covering the surface of the lower layer,
(A) The lower layer is composed of one or more of Ti carbide layer, nitride layer, carbonitride layer, carbonate layer, and carbonitride layer, and 0.5 to A Ti compound layer having a total average layer thickness of 15 μm,

(B) The upper layer is a composite structure layer of at least two phases of aluminum oxide and vanadium oxide having an average layer thickness of 1 to 10 μm, and the composite structure is
Composition formula: (Al ₂ O ₃ ) _1-X (VO _M ) _X
In the above formula, the content ratio of Al and V (atom) satisfying the M value of 1.8 to 2.3 and the X value of 0.03 to 0.2 in the above compositional formula. A composite structure layer of at least two phases of aluminum oxide and vanadium oxide,

A highly viscous work material formed by chemical vapor deposition on the surface of a substrate made of tungsten carbide-based cemented carbide or titanium carbonitride-based cermet (a) or (b). (Stainless steel, mild steel, chrome steel, etc.) It is characterized by a coated tool (surface coated cutting tool) that exhibits excellent chipping resistance in a hard coating layer in high-speed cutting.

Next, the reason why the configuration of the hard coating layer constituting the coated tool of the present invention is limited as described above will be described.
(1) Lower layer (Ti compound layer)
The Ti compound layer basically exists as a lower layer of the upper layer, contributes to improving the high temperature strength of the hard coating layer by its excellent high temperature strength, and also includes the tool base and the upper layer (Al ₂ O ₃ − VO _M layer) either to firmly adhered also show, thus has an effect of improving the adhesion to the tool substrate of a hard coating layer, in the total average layer thickness is less than 0.5 [mu] m, to sufficiently exhibit the effect On the other hand, if the total average layer thickness exceeds 15 μm, it becomes easy to cause thermoplastic deformation that causes uneven wear due to heat generated during cutting, so the total average layer thickness is 0.5 to 15 μm. It was determined.
(2) an upper layer _{(Al 2} O 3 -VO _M layer)
Al component in the Al ₂ O ₃ -VO _M constituting the upper layer has the effect of maintaining the high-temperature hardness of the upper layer, V components, lubricity improvement of the upper layer, which contributes to adhesion resistance improved. That is, in the chemical vapor deposition or in the cooling step after chemical vapor deposition, the V component is taken into the upper Al ₂ O ₃ in the form of VO, V ₂ O ₃ , VO ₂ , V ₂ O ₅ , and the upper layer. V ₂ O ₅ having a low melting point exhibits a lubricating action due to heat generated during cutting, and as a result, the adhesiveness and reactivity of the work material and cutting chips to the cutting edge surface are remarkably reduced. Welding of chips to the part is prevented.

When the upper layer (Al ₂ O ₃ —VO _M layer) is expressed in the form of a composition formula: (Al ₂ O ₃ ) _1-X (VO _M ) _X , the value of M in the above composition formula is, It can be said that it is an index indicating the abundance ratio of V ₂ O ₅ in the vanadium oxide of the entire upper layer (that is, if M is 1, all vanadium oxides exist as VO and V ₂ O ₅ does not exist). And if M is 2.5, all vanadium oxides exist as V ₂ O ₅ and VO, V ₂ O ₃ , VO ₂ do not exist), but the value of M is 1 If it is less than .8, V ₂ O ₅ is very little present in the upper layer formed by chemical vapor deposition, and the effect of improving lubricity and welding resistance cannot be expected. 2.3 (ie most of the vanadium oxide is V ₂ O ₅ ), the high-temperature hardness and high-temperature strength of the upper layer are greatly reduced and the characteristics of the hard coating layer are deteriorated. Therefore, the value of M is determined to be 1.8 to 2.3.

Further, when the value of X in the above composition formula is less than 0.03, the V content ratio is relatively reduced, so that the lubricity in the upper layer is not improved, and the welding resistance is not improved, thereby preventing the occurrence of chipping. On the other hand, when the value of X exceeds 0.2, the lubricity and welding resistance are excellent, but the high-temperature hardness of the upper layer decreases due to the decrease in the relative Al content. Since the wear resistance is insufficient, the value of X, which is an index of the V content ratio in the composition formula: (Al ₂ O ₃ ) _1-X (VO _M ) _X, is determined to be 0.03 to 0.2. .

  If the average layer thickness of the upper layer is less than 1 μm, the excellent properties of the hard coating layer, such as lubricity and welding resistance, cannot be ensured over a long period of time, while if the average layer thickness exceeds 10 μm, Since an abrupt decrease in wear occurred, the average layer thickness of the upper layer was determined to be 1 to 10 μm.

The coated tool of the present invention comprises a hard coating layer, a lower layer comprising a Ti compound layer covering the tool base, and a composite structure of at least two phases of aluminum oxide and vanadium oxide covering the lower layer (Al ₂ O ₃ —VO _M ). By constituting the upper layer composed of layers, the hard coating layer has excellent lubricity and welding resistance while maintaining the high temperature strength and adhesion of the lower layer of the hard coating layer without any loss. In addition, it can be used for cutting under normal conditions such as various types of steel and cast iron, especially in high-speed cutting of highly viscous work materials such as stainless steel, mild steel, and chrome steel. The frictional force between the work material and the cutting tool is reduced, the overheating of the hard coating layer is prevented, and the welding of chips to the cutting edge is prevented, resulting in excellent chipping resistance of the hard coating layer. Indicate Than it exhibits excellent wear resistance over the period.

  Next, the coated tool of the present invention will be specifically described with reference to examples.

As raw material powders, WC powder, TiC powder, VC powder, TaC powder, NbC powder, Cr ₃ C ₂ powder, and Co powder, all having an average particle diameter of 1 to 3 μm, were prepared. And then wet-mixed with a ball mill for 72 hours, dried, and press-molded into a green compact at a pressure of 100 MPa. The green compact was vacuumed at 6 Pa at a temperature of 1400 ° C. for 1 hour. Sintered under holding conditions, and after sintering, tool edge A1 to A10 made of WC-based cemented carbide with ISO standard / CNMG120408 chip shape by applying a honing process of R: 0.07 to the cutting edge portion ( Hereinafter, tool bases A1 to A10) were formed.

In addition, as raw material powders, TiCN (mass ratio, TiC / TiN = 50/50) powder, Mo ₂ C powder, ZrC powder, NbC powder, TaC powder, WC, all having an average particle diameter of 0.5 to 2 μm. Prepare powder, Co powder, and Ni powder, mix these raw material powders into the composition shown in Table 2, wet mix for 24 hours with a ball mill, dry, and press-mold into green compact at 100 MPa pressure The green compact was sintered in a nitrogen atmosphere of 2 kPa at a temperature of 1500 ° C. for 1 hour. After sintering, the cutting edge portion was subjected to a honing process of R: 0.07 and ISO standard TiCN-based cermet tool bases B1 to B6 (hereinafter referred to as tool bases B1 to B6) having a chip shape of CNMG120408 were formed.

  Each of the tool bases A1 to A10 and B1 to B6 is ultrasonically cleaned in acetone and dried, and then placed in the chemical vapor deposition apparatus shown in FIG. 1 of the carbide base support pallet shown in FIG. First, in the state of being placed in the positioning hole, first, Table 3 (l-TiCN in Table 3 indicates the conditions for forming a TiCN layer having a vertically grown crystal structure described in JP-A-6-8010) In the other conditions, the Ti compound layer having the combination shown in Table 6 and the target average layer thickness is formed under the hard coating layer. Deposited as a layer.

Next, the Al ₂ O ₃ —VO _M layer having the target average layer thickness shown in Table 6 under the conditions shown in Table 4 is formed by vapor deposition as the upper layer of the hard coating layer, and this is the coated tool of the present invention. Invention coated throwaway inserts (hereinafter referred to as the present invention coated inserts) 1 to 16 were produced, respectively.

  For comparison purposes, these tool bases A1 to A10 and B1 to B6 were ultrasonically cleaned in acetone and dried, and then charged into the normal chemical vapor deposition apparatus shown in FIGS. The Ti compound layer shown in Table 7 was formed by vapor deposition as the lower layer of the hard coating layer (note that the lower layer (Ti compound layer) of the conventional coated tools 1 to 16 shown in Table 7 is the present coated tools 1 to 16). The specific formation conditions and the target average layer thickness of the lower layer are as shown in Tables 3 and 6).

Next, an Al ₂ O ₃ layer having the target average layer thickness also shown in Table 7 under the conditions shown in Table 5 is deposited on the surface of the lower layer (Ti compound layer) as the upper layer of the hard coating layer, Conventional surface-coated throwaway inserts (hereinafter referred to as conventional coated inserts) 1 to 16 as conventional coated tools were produced, respectively.

Next, in the state where each of the above various coated inserts is screwed to the tip of the tool steel tool with a fixing jig, the present invention coated inserts 1 to 16 and the conventional coated inserts 1 to 16,
Work material: JIS / SUS304 round bar,
Cutting speed: 300 m / min. ,
Cutting depth: 1.5 mm,
Feed: 0.2 mm / rev. ,
Cutting time: 20 minutes,
A dry continuous high-speed cutting test of stainless steel under the conditions (referred to as cutting condition A) (normal cutting speed is 150 m / min.),
Work material: JIS · SCr420H lengthwise equidistant four round grooved round bars,
Cutting speed: 400 m / min. ,
Cutting depth: 1.7 mm,
Feed: 0.3 mm / rev. ,
Cutting time: 25 minutes,
Dry intermittent high-speed cutting test of chrome steel under the conditions (cutting condition B) (normal cutting speed is 200 m / min.),
Work material: JIS / S15C round bar,
Cutting speed: 450 m / min. ,
Cutting depth: 1.6 mm,
Feed: 0.3 mm / rev. ,
Cutting time: 25 minutes,
A dry continuous high-speed cutting test (normal cutting speed is 250 m / min.) Of mild steel under the above conditions (referred to as cutting condition C), and the flank wear width of the cutting edge was measured in any cutting test. The measurement results are shown in Table 8.

About each layer which comprises the hard coating layer of this invention coated inserts 1-16 obtained as a result of this, and the conventional coated inserts 1-16, when the composition was measured using the Auger spectroscopic analyzer, any Ti compound layer, The Al ₂ O ₃ —VO _M layer also showed substantially the same composition as the target composition, and the layer thickness of each layer also showed substantially the same value as the target average layer thickness.

From the results shown in Table 8, the hard layer top _layer, Al _{2 O} 3 -VO _M layer present invention coated inserts 1 to 16 that is configured in both stainless steel, mild steel, or chromium steel viscous Even when cutting a high work material under high-speed cutting conditions, the hard coating layer exhibits excellent lubricity and welding resistance, and exhibits excellent chipping resistance and wear resistance over a long period of time. On the other hand, in the conventional coated inserts 1 to 16 in which the upper layer of the hard coating layer is composed only of the Al ₂ O ₃ layer, chipping is likely to occur, particularly due to insufficient lubricity of the upper layer. It is clear that the service life is reached in a short time.

  As described above, the coated tool of the present invention is capable of cutting a highly viscous work material such as stainless steel, mild steel, and chrome steel under high speed cutting conditions as well as cutting under normal conditions. In this case, excellent chipping resistance is exhibited and excellent wear resistance is exhibited over a long period of time. It can cope with cost reduction sufficiently.

It is a schematic longitudinal cross-sectional view which shows the chemical vapor deposition apparatus used in forming the hard coating layer which comprises a coating tool. The tool base support pallet which is a structural member of a chemical vapor deposition apparatus is shown, (a) is a schematic perspective view, (b) is a schematic plan view.

Claims (1)

A hard coating layer composed of a lower layer covering the surface of the substrate and an upper layer covering the surface of the lower layer is formed on the surface of the substrate made of tungsten carbide-based cemented carbide or titanium carbonitride-based cermet. In the surface-coated cutting tool
(A) The lower layer is composed of one or more of Ti carbide layer, nitride layer, carbonitride layer, carbonate layer, and carbonitride layer, and 0.5 to A Ti compound layer having a total average layer thickness of 15 μm,
(B) The upper layer is a composite structure layer of at least two phases of aluminum oxide and vanadium oxide having an average layer thickness of 1 to 10 μm, and the composite structure is
Composition formula: (Al ₂ O ₃ ) _1-X (VO _M ) _X
In the above formula, the content ratio of Al and V (atom) satisfying the M value of 1.8 to 2.3 and the X value of 0.03 to 0.2 in the above compositional formula. A composite structure layer of at least two phases of aluminum oxide and vanadium oxide,
A high-viscosity work material formed by chemical vapor deposition on the surface of a substrate composed of a tungsten carbide-based cemented carbide or titanium carbonitride-based cermet, the hard coating layer comprising the above (a) and (b). A surface-coated cutting tool that exhibits excellent chipping resistance with a hard coating layer in high-speed cutting.

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