JP2007118156A - Non-hole surface-coated cermet throwaway cutting tip having hard coating layer exhibiting excellent chipping resistance in high speed cutting - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a non-hole coated cutting tip exhibiting excellent chipping resistance in high speed cutting. <P>SOLUTION: In the non-hole coated cutting tip having a hard coating layer which is composed of a lower Ti-compound layer and an upper α-type Al<SB>2</SB>O<SB>3</SB>layer, is formed by vapor deposition on the surface of a tip base body and is clamped to a tool body by a clamp block, an abrasive layer, which is composed of two or more alternately laminated layers of a TiN layer and a TiCN layer, each of the layers having a mean layer thickness of 0.1 to 2.5 μm, and has a total mean layer thickness of 0.4 to 5 μm, is formed by vapor deposition over the whole surface of the upper α-type Al<SB>2</SB>O<SB>3</SB>layer. After that, the polishing fluid mixed with fine particles of Al<SB>2</SB>O<SB>3</SB>is jetted by wet blasting in order to polish the surface of the upper α-type Al<SB>2</SB>O<SB>3</SB>layer leaving the abrasive layer on the contact surface zone with the clamp block intact so as to achieve a surface roughness Ra of 0.2 μm or less. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

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

Conventionally, in general, as shown in a schematic perspective view in FIG. 4, a substrate composed of tungsten carbide (hereinafter referred to as WC) based cemented carbide or titanium carbonitride (hereinafter referred to as TiCN) based cermet (hereinafter referred to as these). On the entire surface of the rake face and flank including the cutting edge ridge line portion of the chip base)
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, an aluminum oxide (hereinafter referred to as α-type Al ₂ O ₃ ) layer having an average layer thickness of 1 to 15 μm and having an α-type crystal structure in a state of chemical vapor deposition,
A coated cutting tip formed by vapor-depositing a hard coating layer composed of the lower layer and the upper layer is known.

  Further, as shown in the schematic perspective view in FIG. 5, the above-mentioned coated cutting tip is placed through a sheet on the tip of the tool body, for example, the shank, and the tip of the crank piece is brought into contact with the upper surface of the tip. It is also well known that, for example, it is used for continuous cutting and intermittent cutting of various steels, cast irons, etc. in a state where the clamp screw provided at the rear of the crank piece is clamped and fixed in a replaceable manner.

  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 α-type Al ₂ O ₃ layer (upper layer) constituting the hard coating layer of the above-described coated cutting tip is smoothed by wet blasting for the purpose of improving cutting performance. Yes.
Japanese Unexamined Patent Publication No. 6-31503 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 α-type Al ₂ O ₃ layer constituting the upper layer of the hard coating layer is likely to chip (small chipping), and as a result, in a relatively short time. At present, the service life is reached.

The present inventors have, from the viewpoint as described above, focuses on coated cutting tip α type the Al ₂ O ₃ layer described above constituting the upper layer of the hard coating layer, in particular the α-type the Al ₂ O ₃ layer As a result of research to improve chipping resistance of
(A) On the surface of the α-type Al ₂ O ₃ layer constituting the upper layer of the hard coating layer in the above-mentioned conventional coated cutting chip, the ratio of the wet blasting material to the total amount of water as a spraying abrasive is 15 When the polishing liquid containing -60 mass% aluminum oxide (hereinafter referred to as Al ₂ O ₃ ) fine particles is sprayed and polished, the α-type Al ₂ O ₃ layer is based on the compliant standard JIS B0601-1994. (The following surface roughness indicates all measured values based on the standard), and Ra: 0.3-0.6 μm surface roughness is obtained. _Even when a coated cutting tip having a surface roughness of Ra: 0.3 to 0.6 μm smoothed by wet blasting on the surface of the ₂ O ₃ layer was used, 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 and clearance including the cutting edge ridge line portion of the α-type Al ₂ O ₃ layer constituting the upper layer of the hard coating layer in the conventional coated cutting tip described above. On the entire surface, titanium nitride having an average layer thickness of 0.1 to 2.5 μm (hereinafter referred to as TiN) under normal conditions, for example, conditions shown in Table 3, using a normal chemical vapor deposition apparatus. In a state where two or more alternating layers of layers and titanium carbonitride (hereinafter referred to as TiCN) layers are vapor-deposited with an overall average layer thickness of 0.4 to 5 μm,
As in the above (a), when a polishing liquid containing 15 to 60% by mass of Al ₂ O ₃ fine particles as a spray abrasive is mixed with water as a spray abrasive, the TiN layer and Two or more alternating layers of TiCN layers (hereinafter referred to individually as a TiN abrasive layer and a TiCN abrasive layer, and these are shown as TiN / TiCN abrasive layers) are pulverized and atomized by the Al ₂ O ₃ granules. The TiN fine particles and TiCN fine particles act as an abrasive in the presence of the Al ₂ O ₃ fine particles, and the surface of the α-type Al ₂ O ₃ layer constituting the upper layer of the hard coating layer is polished. As a result, the surface of the α-type Al ₂ O ₃ layer after polishing is smoothed to a surface roughness of Ra: 0.2 μm or less, and the upper layer of the α-type Al ₂ O ₃ layer is smoothed. Surface roughness Ra: 0.2 μm or less surface roughness When a high-speed cutting process was performed using a coated cutting tip smoothed to 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 that exceeds 1, the load applied to the cutting edge of the coated cutting tip becomes extremely high. Especially in the case of milling, when attaching the coated cutting tip to the tool body, the clamping force is extremely high. As a result, not only the compressive stress on the hard coating layer of the clamp piece abutting portion of the coated cutting tip is extremely high, but also the clamp piece abutting portion during cutting is correspondingly applied. In particular, the α-type Al ₂ O ₃ layer constituting the upper layer has a high hardness of about 3000 in terms of Vickers hardness (Hv). Cracks are likely to occur, and this causes peeling and chipping of the hard coating layer. As shown in the schematic perspective view of FIG. At this time, if the clamp piece abutting portion is not polished and the TiN / TiCN abrasive layer of this portion is left, the TiN abrasive layer constituting this is Hv: about 1950, the TiCN abrasive layer. Hv: has a hardness of around 2600, and these hardnesses are relatively low compared to the α-type Al ₂ O ₃ layer, and thus the hardness is relatively low, The TiN / TiCN abrasive layer having two different laminated layers significantly increases the tightening strength when attaching the coated cutting tip to the tool body, and reduces the compressive stress on the α-type Al ₂ O ₃ layer. from act to significantly dispersed relaxed, so that a very firm anchoring attachment not only becomes possible, occurrence of cracks that cause delamination and chipping in the α-type Al ₂ O ₃ layer is prevented A.
The research results shown in (a) to (c) above were obtained.

The present invention has been made based on the above research results, and the entire rake face and flank face including the cutting edge ridge line portion of the chip base composed of the WC-based cemented carbide or TiCN-based cermet,
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, an α-type Al ₂ O ₃ layer having an average layer thickness of 1 to 15 μm,
In the holeless coated cutting tip that is formed by vapor-depositing the hard coating layer composed of the lower layer and the upper layer, and is attached to the tool body by clamping with a clamp piece so as to be replaceable,
Two or more alternating layers of TiN abrasive layer and TiCN abrasive layer each having an average layer thickness of 0.1 to 2.5 μm are formed on the entire surface of the α-type Al ₂ O ₃ layer which is the upper layer of the hard coating layer. In a state where a TiN / TiCN abrasive layer having a total average layer thickness of 0.4 to 5 μm is formed by vapor deposition,
In wet blasting, as a spraying abrasive, a polishing liquid containing 15 to 60% by mass of Al ₂ O ₃ fine particles in a proportion of the total amount with water is sprayed,
In the presence of the pulverized TiN fine particles and the pulverized TiCN fine particles by wet blasting of the TiN / TiCN abrasive layer and the Al ₂ O ₃ fine particles as the spray abrasive, the abrasive layer on the contact surface portion of the clamp piece is formed. The surface of the α-type Al ₂ O ₃ layer constituting the upper layer of the hard coating layer is polished and the surface roughness of the rake face and the flank face including the cutting edge ridge line portion is determined according to JIS / B0601-1994. According to the measurement, Ra: 0.2 μm or less, the hard coating layer is characterized by a coated cutting tip exhibiting excellent chipping resistance in high-speed cutting.

The reason why the hard coating layer and the abrasive layer of the coated cutting chip of the present invention and the Al ₂ O ₃ fine particles of the polishing liquid used in wet blasting are limited numerically as described above will be described below.
(A) Hard coating layer (a-1) Ti compound layer of lower layer The Ti compound layer exists as a lower layer of the α-type Al ₂ O ₃ layer, and the hard coating layer has a high temperature due to its excellent high temperature strength. In addition to contributing to strength improvement, it has a function of firmly adhering to both the chip base and the α-type Al ₂ O ₃ layer, thereby improving the adhesion of the hard coating layer to the chip base, but the overall average layer thickness is 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, it becomes easy to cause thermoplastic deformation particularly in high-speed cutting accompanied by generation of high heat. Since it becomes a cause, the whole average layer thickness was set to 3-20 micrometers.
(A-2) α-type Al ₂ O ₃ layer of the upper layer The α-type Al ₂ O ₃ layer has excellent high-temperature hardness and heat resistance, and contributes to improving the cutting performance of the coated cutting tip. 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 tends to occur. The average layer thickness was set to 1 to 15 μm.
(B) TiN / TiCN abrasive material layer As described above, the TiN / TiCN abrasive material layer is pulverized and atomized by Al ₂ O ₃ fine particles blended in the polishing liquid as an injection abrasive during wet blasting, and TiN fine particles and TiCN fine particles It acts as an abrasive in the coexistence with the Al ₂ O ₃ fine particles, and polishes the surface of the α-type Al ₂ O ₃ layer constituting the upper layer of the hard coating layer. When the average layer thickness is less than 0.1 μm, or the overall average layer thickness of the TiN / TiCN abrasive layer is less than 0.4 μm, the clamping force buffering effect by the abrasive layer on the clamp piece contact surface portion In addition to not being able to fully exhibit the anti-seismic effect, the ratio of pulverized TiN fine particles and pulverized TiCN fine particles at the time of wet blasting is too small to sufficiently exhibit the polishing function On the other hand, if the average layer thickness of each abrasive layer exceeds 2.5 μm, or the total average layer thickness of the TiN / TiCN abrasive layer exceeds 5 μm, it is blended into the polishing liquid as a spray abrasive. The balance with the Al ₂ O ₃ fine particles is lost and becomes relatively large, and in this case as well, the polishing function is suddenly lowered. In either case, the surface of the α-type Al ₂ O ₃ layer is Ra: 0. The average layer thickness of each abrasive layer was determined to be 0.1 to 2.5 μm, and the overall average layer thickness was set to 0.4 to 5 μm, because it was impossible to polish to a surface roughness of 2 μm or less. .
The Al ₂ O ₃ fine fraction polishing liquid Al ₂ O ₃ fine of (c) polishing liquid, in a state where at the time of wet blast coexists with pulverized TiN atomization and pulverization TiCN fine of TiN / TiCN abrasive layer, alpha The surface of the type Al ₂ O ₃ layer has an action of polishing, but even if the ratio is less than 15% by mass or more than 60% by mass with respect to the total amount with water, the polishing function seems to be drastically reduced. Therefore, the ratio was determined to be 15 to 60% by mass.

In the coated cutting tip of the present invention, the rake face and flank face including the cutting edge ridge line portion of the α-type Al ₂ O ₃ layer constituting the upper layer of the hard coating layer are polished to a surface roughness of Ra: 0.2 μm or less. In addition, the abrasive layer on the abutting surface of the clamp piece acts as a buffer layer with high clamping force, which is indispensable for high-speed cutting when attaching a coated cutting tip to the tool body, and also occurs during cutting. Acting as a strong mechanical vibration isolation layer, the compressive stress on the α-type Al ₂ O ₃ layer is remarkably relieved, and the vibration attack by the clamp piece is extremely small. What it coupled with the cracking that causes peeling and chipping in the mold the Al ₂ O ₃ layer is to be prevented, the cutting of various kinds of steel and cast iron, cutting speed 350 meters / m n. 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 coated cutting tip of 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 specified in ISO · CNMN120408 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. Chip bases a to f made of TiCN base cermet having standard / CNMN12041 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 α-type Al ₂ O ₃ layer having the target layer thicknesses shown in Table 5 are vapor-deposited as the lower layer and the upper layer of the hard coating layer under the conditions shown in FIG. (See Fig. 4)
Next, a TiN / TiCN abrasive layer was formed by vapor deposition with the number of layers and the target layer thickness also shown in Table 6 under the TiN abrasive layer and TiCN abrasive layer forming conditions shown in Table 3 (see FIG. 2).
Subsequently, the coated cutting tip for forming the TiN / TiCN abrasive layer was wet-blasted under the blasting conditions shown in Table 4 and in the combinations shown in Table 6, and TiN / Polishing the rake face and flank face including the cutting edge ridge line portion of the α-type Al ₂ O ₃ layer (upper layer) to the surface roughness shown in Table 6 in the presence of the TiCN abrasive layer. According to the present invention, the coated cutting chips 1 to 13 of the present invention were manufactured (see FIG. 1).

For comparison purposes, as shown in Table 7, it is the same except that the above-described TiN / TiCN abrasive layer is not formed and wet blasting is directly applied to the surface of the α-type Al ₂ O ₃ layer of the hard coating layer. The conventional coated cutting tips 1 to 13 were manufactured under the conditions (see FIG. 4).

Table 7 shows the surface roughness after wet blasting of the α-type Al ₂ O ₃ 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, as for the various coated cutting tips of the present invention coated cutting tips 1 to 13 and the conventional coated cutting tips 1 to 13, respectively, as shown in FIGS. In a state where it is attached to the tip of the shank by clamping with the clamp screw of the clamp piece,
Work material: JIS / FC250 round bar,
Cutting speed: 500 m / min,
Incision: 3mm,
Feed: 0.3mm / rev,
Cutting time: 14 minutes,
Dry continuous high-speed cutting test (normal cutting speed is 250 m / min) of normal cast iron under the following conditions (referred to as cutting condition A),
Work material: JIS / S55C lengthwise equidistant round bars with 4 vertical grooves,
Cutting speed: 430 m / min,
Cutting depth: 2mm,
Feed: 0.3mm / rev,
Cutting time: 8 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 · SCM420 lengthwise equal four round grooved round bars,
Cutting speed: 400 m / min,
Cutting depth: 2mm,
Feed: 0.25mm / rev,
Cutting time: 6 minutes
A dry interrupted 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), 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 5 to 8, the coated cutting tips 1 to 13 of the present invention all have a rake face and a flank face including the cutting edge ridge line portion of the α-type Al ₂ O ₃ layer constituting the upper layer of the hard coating layer. However, Ra: polished to a surface roughness of 0.2 μm or less, and the abrasive layer present on the clamp piece abutting surface portion is high-speed cutting exceeding 350 m / min when the coated cutting tip is attached to the tool body. It acts as a buffer layer with a high clamping force, which is indispensable for machining, and also acts as an anti-vibration layer for strong mechanical vibrations that occur during cutting, so the compressive stress on the α-type Al ₂ O ₃ layer is remarkably relieved. It is, and vibration attack becomes extremely small due to the clamping piece, as a result the causative cracking peeling or chipping occurred at the α-type the Al ₂ O ₃ layer is prevented, the steel and cast iron Fast cutting, excellent chipping resistance indicates the relative to exhibit excellent cutting performance over a long period of time, the surface roughness of the α type the Al ₂ O ₃ layer constituting the upper layer of the hard coating layer Ra: 0.3 to 0.6 μm Conventional coated cutting tips 1 to 13 are all coupled with the fact that high clamping force exceeding 350 m / min requires high clamping force for tool attachment. Thus, it is clear that chipping occurs in the α-type Al ₂ O ₃ layer and the service life is reached in a relatively short time.

  As described above, the coated cutting tip of the present invention can be used not only for continuous cutting and intermittent cutting under normal conditions such as various steels and cast iron, but also when cutting is performed at a high speed exceeding 350 m / min. Because it shows excellent chipping resistance and exhibits excellent cutting performance over a long period of time, it can sufficiently satisfy the high performance of cutting equipment, labor saving and energy saving of cutting work, and further cost reduction. Is.

It is a schematic perspective view of this invention coating cutting tip shown notching a part of hard coating layer. It is a schematic perspective view of the coated cutting tip of the abrasive layer vapor deposition formed by cutting away a part of the abrasive layer. It is a schematic perspective view which shows the attachment aspect to the tool main body of this invention coated cutting tip. It is a schematic perspective view of the conventional coated cutting tip shown by cutting out a part of a hard coating layer. It is a schematic perspective view which shows the attachment aspect to the tool main body of the conventional coated cutting tip.

Claims (1)

On the entire rake face and flank face including the cutting edge ridge line portion of the chip base composed of tungsten carbide base cemented carbide or titanium carbonitride base cermet,
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, an aluminum oxide layer having an average layer thickness of 1 to 15 μm and having an α-type crystal structure in a state of chemical vapor deposition,
In the cutting throwaway tip made of surface-covered cermet without holes, which is formed by vapor-depositing the hard coating layer composed of the lower layer and the upper layer, and is attached to the tool body by clamping with a clamp piece so as to be replaceable.
The entire surface of the aluminum oxide layer, which is the upper layer of the hard coating layer, is composed of two or more alternating layers of titanium nitride layers and titanium carbonitride layers having an average layer thickness of 0.1 to 2.5 μm, And in a state where the abrasive layer having an overall average layer thickness of 0.4 to 5 μm is formed by vapor deposition,
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 the presence of the pulverized titanium nitride fine particles and pulverized titanium carbonitride fine particles by wet blasting of the abrasive layer and the aluminum oxide fine particles as the spray abrasive, the abrasive layer on the contact surface portion of the clamp piece is left. Then, the surface of the aluminum oxide layer constituting the upper layer of the hard coating layer is polished, and the surface roughness of the rake face and the flank face including the cutting edge ridge line portion is measured based on the compliant standard JIS B0601-1994. Ra: 0.2 μm or less, characterized in that the hard coating layer has a hole-less surface-coated cermet cutting throwaway tip that exhibits excellent chipping resistance in high-speed cutting.

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