JP4900652B2 - Surface polishing method for cutting throwaway tip made of surface-covered cermet whose hard coating layer exhibits excellent chipping resistance in high-speed cutting - Google Patents

Description

The present invention is a surface-coated cermet cutting throwaway tip (hereinafter referred to as a coated cutting tip) that exhibits excellent chipping resistance with a hard coating layer, particularly when used for high-speed cutting of various steels and cast irons . The present invention relates to a surface polishing method .

Conventionally, generally, as shown in a schematic perspective view in FIG. 3, it is composed of a tungsten carbide (hereinafter referred to as WC) -based cemented carbide or titanium carbonitride (hereinafter referred to as TiCN) -based cermet, and a tool at the center. On the entire surface of the rake face and the flank face including the cutting edge ridge line portion of the base body (hereinafter collectively referred to as a chip base body) having mounting holes,
As a lower layer, a titanium carbide (hereinafter referred to as TiC) layer, a titanium nitride (hereinafter also referred to as TiN) layer, a titanium carbonitride (hereinafter referred to as TiCN) layer, a titanium carbonate (hereinafter referred to as TiCO) layer And a Ti compound layer comprising one or more of titanium carbonitride oxide (hereinafter referred to as TiCNO) layers and having an overall average layer thickness of 3 to 20 μm,
As an upper layer, a two-phase mixed oxide (hereinafter referred to as Al ₂ O ₃ —ZrO ₂ ) layer of aluminum oxide and zirconium oxide having an average layer thickness of 1 to 15 μm and chemical vapor deposition,
It is well known that a coated cutting tip formed by vapor-depositing a hard coating layer composed of is used for continuous cutting and intermittent cutting of, for example, various types of steel and cast iron. Yes.

The Al ₂ O ₃ —ZrO ₂ layer , which is the upper layer, has the following conditions:
(B) Reaction gas composition (volume%)
AlCl ₃ : 1 to 10%,
ZrCl _4: 0.01~10%,
CO _2: 1~30%,
HCl: 1-30%,
H ₂ S: 0.01~1%,
H ₂ : Remaining
(B) Reaction atmosphere temperature: 900 to 1050 ° C.
(C) Reaction atmosphere pressure: 4 to 70 kPa (30 to 525 torr),
It is known that it is formed by chemical vapor deposition under the following conditions .

In the above-mentioned coated cutting tip, the constituent layer of the hard coating layer generally has a granular crystal structure, and the TiCN layer constituting the Ti compound layer as the lower layer is intended to improve the strength of the layer itself. In a normal chemical vapor deposition apparatus, a gas mixture containing organic carbonitrides is used as a reaction gas, and it is formed by chemical vapor deposition at an intermediate temperature range of 700 to 950 ° C. so that it has a vertically grown crystal structure. It is also known to do.
Furthermore, it is also known that the surface of the upper layer constituting the hard coating layer of the above-described coated cutting tip is smoothed by wet blasting for the purpose of improving the cutting performance.
JP 2000-334605 A JP 2004-42150 A Japanese Patent Laid-Open No. 6-8010 JP-A-8-276305

In recent years, the performance of cutting equipment has been remarkable. On the other hand, there is a strong demand for labor saving and energy saving and further cost reduction for cutting, and along with this, cutting tends to be faster. The cutting tip has no problem when it is used for continuous cutting or intermittent cutting under normal conditions such as steel or cast iron, but the cutting speed is 350 m / min. When it is used for cutting at a high speed exceeding 1, the Al ₂ O ₃ —ZrO ₂ layer constituting the upper layer of the hard coating layer is likely to chip (small chipping), resulting in a relatively short time. At present, the service life is reached.

Therefore, the present inventors pay attention to the coated cutting tip in which the Al ₂ O ₃ —ZrO ₂ layer constitutes the upper layer of the hard coating layer from the above viewpoint, and in particular, the Al ₂ O ₃ —ZrO _2. As a result of research to improve chipping resistance of the _two layers,
(A) On the surface of the Al ₂ O ₃ —ZrO ₂ layer constituting the upper layer of the hard coating layer in the above-mentioned conventional coated cutting tip, the ratio of the wet blast to the total amount of water as the spray abrasive When a polishing liquid containing 15 to 60% by mass of aluminum oxide (hereinafter referred to as Al ₂ O ₃ ) fine particles is sprayed and polished, the Al ₂ O ₃ —ZrO ₂ layer is in compliance with JIS B0601-1994. (The following surface roughness is a measured value based on such standards.) Ra: 0.3 to 0.6 μm surface roughness is obtained. _Even when a coated cutting tip in which the surface of the ₂ O ₃ —ZrO ₂ layer was smoothed to a surface roughness of Ra: 0.3 to 0.6 μm by wet blasting, the cutting speed was 350 m / min. High-speed cutting that exceeds the limit cannot effectively suppress chipping at the cutting edge.

(B) On the other hand, as shown in the schematic perspective view of FIG. 2, the rake face including the cutting edge ridge portion of the Al ₂ O ₃ —ZrO ₂ layer constituting the upper layer of the hard coating layer in the conventional coated cutting tip and A titanium nitride (hereinafter referred to as TiN) layer is formed on the entire flank surface by using a normal chemical vapor deposition apparatus under normal conditions, for example, conditions shown in Table 3 and an average layer thickness of 0.5 to 5 μm. In a state where chemical vapor deposition is formed,
When a polishing liquid containing 15 to 60% by mass of Al ₂ O ₃ fine particles as a spraying abrasive in a ratio to the total amount of water is sprayed by wet blasting as in (a) above, the TiN layer ( Hereinafter, the TiN abrasive layer is pulverized and pulverized by the Al ₂ O ₃ fine particles, becomes TiN fine particles and acts as an abrasive in the presence of the Al ₂ O ₃ fine particles, and constitutes the upper layer of the hard coating layer to become polishing the surface of the _{Al 2 O} 3 -ZrO 2 layers, the surface of the _{Al 2 O} 3 -ZrO 2 layer after the results polishing, Ra: smoothed to a surface roughness of not more than 0.2μm When high-speed cutting is performed using a coated cutting tip in which the surface of the upper layer Al ₂ O ₃ —ZrO ₂ layer is smoothed to a surface roughness of Ra: 0.2 μm or less 350 m / min. Chipping at the cutting edge is prevented even at a cutting speed exceeding 1, and the hard coating layer exhibits excellent wear resistance over a long period of time.

(C) As described above, the cutting speed is 350 m / min. In high-speed cutting processing exceeding 1, the load applied to the cutting edge of the coated cutting tip is extremely high. Therefore, especially in the case of milling, the coated cutting tip is attached to the tool body with a very high clamping force. As a result, the compressive stress on the hard coating layer around the tool mounting hole of the coated cutting tip becomes extremely high, and in particular, the Al ₂ O ₃ —ZrO ₂ layer constituting the upper layer is made of Vickers. Combined with having a high hardness (Hv) of about 2400, it is easy for cracks to occur, which causes peeling and chipping on the hard coating layer. As shown in the schematic perspective view, during the wet blasting, the periphery of the tool mounting hole is not polished, and the TiN abrasive layer is left in this portion. When the TiN abrasive layer as compared with the _{Al 2 O} 3 -ZrO 2 layer has a relatively high temperature strength, and low in hardness (Hv: about 1950) because it is, the tool body When the coated cutting tip is attached to the surface, it acts as a buffer layer having a high clamping force, and as a result, the compressive stress on the Al ₂ O ₃ —ZrO ₂ layer becomes extremely small, which causes peeling and chipping. The generation of cracks should be prevented.
The research results shown in (a) to (c) above were obtained.

The present invention has been made on the basis of the above research results, and includes a cutting edge ridge portion of a chip base made of a WC-based cemented carbide or TiCN-based cermet and having a tool mounting hole in the center. On the entire surface and flank,
As a lower layer, a Ti compound layer composed of one or more of a TiC layer, a TiN layer, a TiCN layer, a TiCO layer, and a TiCNO layer and having an overall average layer thickness of 3 to 20 μm,
As an upper layer, it has an average layer thickness of 1 to 15 μm, and ZrO ₂ is 0 in terms of the ratio (atomic ratio) in the total amount of Al and Zr contained in the layer, in terms of the content ratio of Zr. Al ₂ O ₃ —ZrO ₂ layer satisfying .01 to 0.20,
In the surface polishing method of a coated cutting chip formed by chemical vapor deposition of a hard coating layer composed of
(A) the entire surface of the _{Al 2 O} 3 -ZrO 2 layer which is the upper layer of the hard coating layer, an average layer thickness of 0.5 to 5 [mu] m, and chemical vapor deposition a TiN abrasive layer,
( B ) Next , in wet blasting, a polishing liquid containing 15 to 60% by mass of Al ₂ O ₃ fine particles as a proportion of the total amount with water is sprayed as a spray abrasive.
In this case, the TiN abrasive layer around the tool mounting hole is not polished and left as a buffer layer having a high clamping force when the tool body is mounted, and the TiN abrasive layer on the remaining polishing surface is a jet abrasive. and there Al ₂ O ₃ milled TiN fine made by grinding atomized by injection fine, in the presence of Al ₂ O ₃ fine as injection abrasive, Al ₂ O ₃ constituting the upper layer of the hard coating layer - By polishing the surface of the ZrO ₂ layer and measuring the surface roughness of the rake face and flank face including the cutting edge ridge line portion of the Al ₂ O ₃ —ZrO ₂ layer based on the compliant standard JIS B0601-1994, Ra The hard coating layer having a thickness of 0.2 μm or less has a feature in the surface polishing method of a coated cutting chip that exhibits excellent chipping resistance in high-speed cutting.

Hereinafter, in the surface polishing method of the coated cutting tip of the present invention, the reason why the hard coating layer, the TiN abrasive layer, and the Al ₂ O ₃ fine particles of the polishing liquid used in wet blasting are numerically limited as described above will be described. To do.
(A) hard coating layer (a-1) Ti compound layer Ti compound layer of the lower layer is present as a lower layer of _{Al 2 O} 3 -ZrO 2 layer, the hard coating layer by excellent high temperature strength which includes its own In addition to contributing to the improvement of high-temperature strength, it has a function of firmly adhering to both the chip base and the Al ₂ O ₃ —ZrO ₂ layer , thereby improving the adhesion of the hard coating layer to the chip base. If the thickness is less than 3 μm, the above-mentioned effect cannot be sufficiently exerted. On the other hand, if the total average layer thickness exceeds 20 μm, thermoplastic deformation tends to occur particularly in high-speed cutting accompanied by high heat generation. Since it causes wear, the overall average layer thickness is determined to be 3 to 20 μm.

(A-2) Al ₂ O ₃ —ZrO ₂ layer of the upper layer
The Al ₂ O ₃ —ZrO ₂ layer has excellent high-temperature hardness and heat resistance due to its Al component, and excellent high-temperature strength due to its Zr component, and the cutting performance (chipping resistance) of the coated cutting tip. However, the content ratio of ZrO _{2 in} the Al ₂ O ₃ —ZrO ₂ layer is converted to the content ratio of Zr and accounts for the total amount of Al and Zr contained in the layer. The ratio [= Zr / (Al + Zr)] is within a range of 0.01 to 0.20 (atomic ratio). When this value indicating the content ratio of ZrO _{2 in} the Al ₂ O ₃ —ZrO ₂ layer is less than 0.01, the effect of improving the high-temperature strength of the upper layer is small, whereas this value exceeds 0.20. And the relative decrease in the amount of Al ₂ O ₃ in the upper layer causes a decrease in high-temperature hardness and heat resistance. As a result, there is a tendency for wear resistance to deteriorate, so the Al ₂ O ₃ —ZrO ₂ layer As described above, the ZrO ₂ content ratio [Zr / (Al + Zr) value converted in terms of atomic ratio) is set to a value within the range of 0.01 to 0.20.
Further, if the average layer thickness is less than 1 μm, the desired excellent cutting performance cannot be exhibited over a long period of time. On the other hand, if the average layer thickness exceeds 15 μm, chipping is likely to occur. Therefore, the average layer thickness was determined to be 1 to 15 μm.

(B) TiN abrasive layer As described above, TiN abrasive layer during wet blasting, the Al ₂ O ₃ fine formulated as injection abrasive in the polishing liquid milled micronized, the Al ₂ O ₃ becomes TiN fine Acts as an abrasive in the presence of fine particles and polishes the surface of the Al ₂ O ₃ —ZrO ₂ layer constituting the upper layer of the hard coating layer. In this case, if the average layer thickness is less than 0.5 μm, When the ratio of the pulverized TiN fine particles at the time of wet blasting is too small, the polishing function cannot be sufficiently exhibited. On the other hand, when the average layer thickness exceeds 5 μm, Al ₂ blended in the polishing liquid as a jetting abrasive. The balance with the O ₃ fine particles is lost, and the balance is excessively increased. In this case, the polishing function is rapidly deteriorated. In each case, the surface of the Al ₂ O ₃ —ZrO ₂ layer is set to Ra: 0. 2 μm or less Because it is can not be polished to a surface roughness, it determined the average layer thickness and 0.5 to 5 [mu] m.

(C) The Al ₂ O ₃ fine of Al ₂ O ₃ fine fraction polishing liquid of the polishing liquid, while coexisting with pulverized TiN fine of TiN abrasive layer during wet blasting, _{Al 2 O} 3 -ZrO 2 layers However, even if the ratio is less than 15% by mass or more than 60% by mass with respect to the total amount of water, the polishing function will rapidly decrease. The ratio was determined to be 15 to 60% by mass.

The coated cutting tip surface-polished by the method of the present invention has a rake face and a flank face including the cutting edge ridge line portion of the Al ₂ O ₃ —ZrO ₂ layer constituting the upper layer of the hard coating layer, with Ra: 0.2 μm. The TiN abrasive layer polished to the following surface roughness and present around the tool mounting hole acts as a buffer layer with a high clamping force, which is indispensable for high-speed cutting when attaching the coated cutting tip to the tool body. Accordingly, the compressive stress on the Al ₂ O ₃ —ZrO ₂ layer is extremely small, and as a result, cracking that causes peeling and chipping is prevented, and various steels are combined. Cutting of cast iron and cast iron, the cutting speed is 350 m / min. Even when used for high-speed operation exceeding the above, excellent chipping resistance is exhibited, and the service life can be further extended.

Next, the method for polishing the surface of the coated cutting tip according to the present invention will be specifically described with reference to examples.

WC powder, TiC powder, ZrC powder, VC powder, TaC powder, NbC powder, Cr ₃ C ₂ powder, TiN powder, TaN powder, and Co powder all having an average particle diameter of 1 to 3 μm are prepared as raw material powders. These raw material powders were blended into the composition shown in Table 1, added with wax, ball milled in acetone for 24 hours, dried under reduced pressure, and pressed into a green compact with a predetermined shape at a pressure of 98 MPa. The green compact was vacuum sintered at a predetermined temperature in the range of 1370 to 1470 ° C. for 1 hour in a vacuum of 5 Pa. After sintering, the cutting edge portion was R: 0.07 mm honing By processing, chip bases A to F made of a WC-based cemented carbide having a throwaway tip shape defined in ISO · CNMG120408 were manufactured.

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 powder, all having an average particle diameter of 0.5 to 2 μm. Co powder and Ni powder are prepared, and these raw material powders are blended in the blending composition shown in Table 2, wet mixed by a ball mill for 24 hours, dried, and pressed into a compact at a pressure of 98 MPa. The green compact was sintered in a nitrogen atmosphere of 1.3 kPa at a temperature of 1540 ° C. for 1 hour, and after the sintering, the cutting edge portion was subjected to a honing process of R: 0.07 mm. TiCN base cermet chip bases a to f having a standard / CNMG12041 chip shape were formed.

Next, each of these chip bases A to F and chip bases a to f is charged into a normal chemical vapor deposition apparatus,
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 No. 6-8010, and other than that, a normal granular crystal structure is shown. The Ti compound layer and the Al ₂ O ₃ —ZrO ₂ layer having the target layer thicknesses shown in Table 6 are used as the lower and upper layers of the hard coating layer under the conditions shown in Table 4 and the conditions shown in Table 4. Vapor deposition (see Figure 3)
Next, a TiN abrasive material layer was formed by vapor deposition with a target layer thickness also shown in Table 6 under the TiN layer formation conditions shown in Table 3 (see FIG. 2).
Subsequently, the coated cutting tip for forming the TiN abrasive layer was wet-blasted under the blast conditions shown in Table 5 and in the combinations shown in Table 6, and the TiN abrasive layer was formed around the tool mounting hole. In the state of being present, the rake face and flank face including the cutting edge ridge line portion of the upper layer composed of the Al ₂ O ₃ —ZrO ₂ layer are polished to the surface roughness shown in Table 6 to cover the present invention. Cutting tips 1 to 13 were manufactured (see FIG. 1).

Further, for comparison purposes, as shown in Table 7, it is the same except that wet blasting is directly applied to the surface of the Al ₂ O ₃ —ZrO ₂ layer of the hard coating layer without forming the TiN abrasive layer. Conventional coated cutting chips 1 to 13 were manufactured under the conditions.
Table 7 shows the surface roughness after wet blasting of the Al ₂ O ₃ —ZrO ₂ layer constituting the hard coating layer of the conventional coated cutting chips 1 to 13 obtained as a result.

  In addition, the composition of the hard coating layer and the abrasive layer of the above-described coated cutting chips 1 to 13 of the present invention, and the composition of the hard coating layer of the conventional coated cutting chips 1 to 13 are each measured with an Auger spectroscopic analyzer at the center in the thickness direction. When measured, all showed substantially the same composition as the target composition, and when the thickness of the same constituent layer was measured using a scanning electron microscope (longitudinal section measurement), both were substantially the same as the target layer thickness. The same average layer thickness (average value of 5-point measurement) was shown.

Next, for the various coated cutting chips of the present invention coated cutting chips 1 to 13 and the conventional coated cutting chips 1 to 13 described above, all of them are screwed to the tip of the tool steel tool with a fixing jig,
Work material: JIS / FC300 lengthwise equidistant 4 bars with vertical grooves,
Cutting speed: 580 m / min,
Cutting depth: 2.0 mm,
Feed: 0.2 mm / rev,
Cutting time: 8 minutes,
Dry interrupted high-speed cutting test of normal cast iron under the conditions (cutting condition A) (normal cutting speed is 200 m / min),
Work material: JIS / S55C lengthwise equidistant round bars with 4 vertical grooves,
Cutting speed: 400 m / min,
Cutting depth: 2.0 mm,
Feed: 0.4 mm / rev,
Cutting time: 11 minutes,
Dry intermittent high speed cutting test (normal cutting speed is 200 m / min) of carbon steel under the above conditions (referred to as cutting conditions B),
Work material: JIS / SCM435 round bar,
Cutting speed: 450 m / min,
Cutting depth: 2.0 mm,
Feed: 0.5 mm / rev,
Cutting time: 7 minutes,
The dry continuous high-speed cutting test (normal cutting speed is 200 m / min) of the alloy steel under the above conditions (referred to as cutting condition C) was performed, and the flank wear width of the cutting edge was measured in any cutting test. The measurement results are shown in Table 8.

From the results shown in Tables 6 to 8, the coated cutting tips 1 to 13 of the present invention all have a rake face and a relief including the cutting edge ridge portion of the Al ₂ O ₃ —ZrO ₂ layer constituting the upper layer of the hard coating layer. The surface is polished to a surface roughness of Ra: 0.2 μm or less, and the TiN abrasive layer existing around the tool mounting hole has a high speed cutting exceeding 350 m / min when the coated cutting tip is attached to the tool body. Since it acts as a buffer layer with a high clamping force, which is indispensable in machining, it prevents cracks that can cause peeling and chipping, and exhibits excellent chipping resistance in high-speed cutting of steel and cast iron for a long time. whereas exhibit excellent cutting performance Te, the surface roughness of the Al ₂ O ₃ -ZrO ₂ layer constituting the upper layer of the hard coating layer, Ra: conventional coating showing a 0.3~0.6μm In cutting chips 1-13, both in high-speed cutting of over 350 meters / min, coupled with the fact that require high clamping force to the tool mounting, chipping occurring in the Al ₂ O ₃ -ZrO ₂ layers It is clear that the service life is reached in a relatively short time.

As described above, the coated cutting tip surface-polished by the method of the present invention exceeds 350 m / min in particular, in addition to continuous cutting and intermittent cutting under normal conditions such as various steels and cast iron. Excellent chipping resistance even when performed at high speeds, and excellent cutting performance over a long period of time. Higher performance of cutting equipment, labor saving and energy saving of cutting, and cost reduction It is possible to cope with the above sufficiently.

It is the schematic perspective view which notched and showed a part of hard coating layer of the coated cutting chip surface-polished by the method of this invention . It is the schematic perspective view which notched and showed a part of abrasive material layer of the covering cutting chip after the abrasive material layer vapor deposition formation in the method of this invention . It is the schematic perspective view which notched and showed a part of hard coating layer of the conventional coated cutting chip .

Claims (1)

It is composed of a tungsten carbide base cemented carbide or a titanium carbonitride base cermet, and the entire rake face and flank face including the cutting edge ridge line part of the chip base having a tool attachment hole in the center part,
The lower layer is composed of one or more of a titanium carbide layer, a titanium nitride layer, a titanium carbonitride layer, a titanium carbonate layer, and a titanium carbonitride oxide layer, and has an overall average layer thickness of 3 to 20 μm. Having a Ti compound layer,
As an upper layer, it has an average layer thickness of 1 to 15 μm, has a two-phase mixed oxide structure of aluminum oxide and zirconium oxide in the state of chemical vapor deposition, and the zirconium oxide is converted into a content ratio of Zr Then, the ratio (atomic ratio) of the total amount of Al and Zr contained in the layer is 0.01 to 0.20, and the two-phase mixed oxide layer of aluminum oxide and zirconium oxide (Al ₂ O ₃ -ZrO ₂ layer),
In the surface polishing method of the surface coated cermet cutting throwaway tip, formed by chemical vapor deposition of a hard coating layer composed of
(A) the entire surface of the 2-phase mixed oxide layer of aluminum oxide and zirconium oxide, which is the upper layer of the hard coating layer _{(Al 2} O 3 -ZrO ₂ layer), nitride having an average layer thickness of 0.5~5μm Chemical vapor deposition of an abrasive layer composed of a titanium layer,
( B ) Next , in wet blasting, as a spraying abrasive, a polishing liquid containing 15 to 60% by mass of aluminum oxide fine particles in a proportion of the total amount with water is sprayed.
In this case, the abrasive layer around the tool mounting hole is not polished, and remains as a buffer layer having a high clamping force when the tool body is mounted, and the abrasive layer on the remaining polishing surface is a jet abrasive. Two-phase mixing of aluminum oxide and zirconium oxide constituting the upper layer of the hard coating layer in the coexistence of pulverized titanium nitride particles formed by pulverizing and atomizing aluminum oxide particles and aluminum oxide particles as a spray abrasive The surface of the oxide layer (Al ₂ O ₃ —ZrO ₂ layer) is polished to include a cutting edge ridge line portion of the two-phase mixed oxide layer of aluminum oxide and zirconium oxide (Al ₂ O ₃ —ZrO ₂ layer) Rigid surface and roughness of rake face measured according to JIS B0601-1994, Ra: 0.2 μm or less Surface polishing method of the surface-coated cermet cutting throw-away tip layer exhibits excellent chipping resistance in high-speed cutting.

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