JP2007237307A - Surface coated cermet-made cutting tool having hard coating layer exhibiting excellent chipping resistance in heavy cutting - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a surface coated cermet-made cutting tool having a hard coating layer exhibiting excellent chipping resistance in heavy cutting. <P>SOLUTION: The surface coated cermet-made cutting tool is formed by depositing the hard coating layer including: (a) a Ti compound layer as a lower layer; and (b) an aluminum oxide layer as an upper layer all over a cutting face, a flank and a cutting blade ridge line part where both of these faces intersect of a tip base. In the cutting tool, extending all over either of the cutting face and the flank, or both of them, either of a single basic shape mark and a set of the single basic shape marks or both of them are dispersed and distributed, and the single basic shape mark is formed by irradiating a hard coating layer residual stress reducing pattern in which one of the constituting layers of the hard coating layer is exposed to form a sinking surface with a laser beam. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention provides a surface coating that exhibits excellent chipping resistance with a hard coating layer, particularly when cutting various steels and cast irons under heavy cutting conditions such as high cutting and high feed with high load. The present invention relates to a cermet cutting tool (hereinafter referred to as a coated cutting tool).

Conventionally, a rake face of a substrate (hereinafter collectively referred to as a tool substrate) made of tungsten carbide (hereinafter referred to as WC) based cemented carbide or titanium carbonitride (hereinafter referred to as TiCN) based cermet. And the flank, and further across the entire surface of the cutting edge ridge line where these both sides intersect,
(A) 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) A Ti compound layer composed of one or two or more of a layer and a titanium carbonitride oxide (hereinafter referred to as TiCNO) layer and having an overall average layer thickness of 3 to 12 μm,
(B) As an upper layer, an average layer thickness of 1 to 6 μm is an aluminum oxide layer (hereinafter referred to as an Al ₂ O ₃ layer),
A coated cutting tool formed by vapor-depositing the hard coating layer constituted by the above (a) and (b) is known, and this coated cutting tool is used for continuous cutting and intermittent cutting of various steels and cast irons, for example. It is well known that it is used.

In the above-mentioned coated cutting tool, the constituent layer of the hard coating layer generally has a granular crystal structure, and further, 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.
Japanese Unexamined Patent Publication No. 6-31503 Japanese Patent Laid-Open No. 6-8010

  In recent years, the performance of cutting machines has been remarkable. On the other hand, there is a strong demand for labor-saving and energy-saving for cutting, and further cost reduction. Although cutting tends to be performed under heavy cutting conditions such as cutting and high feed, the conventional coated cutting tool described above was used for continuous cutting and intermittent cutting under normal conditions such as steel and cast iron. In particular, there is no problem, but especially when the cutting and feeding of the processing conditions are increased, chipping (small chipping) is likely to occur in the hard coating layer, resulting in a service life in a relatively short time. is the current situation.

Therefore, the present inventors focused on the hard coating layer of the above-mentioned conventional coated cutting tool from the above viewpoint, and as a result of conducting research to improve its chipping resistance,
(A) Usually, the hard coating layer in the above-described conventional coated cutting tool is formed by being deposited on the surface of the tool substrate at a reaction temperature of about 1000 ° C. and cooled to room temperature by a chemical vapor deposition apparatus. In the cooling process, since the thermal expansion coefficient of the hard coating layer is much larger than the thermal expansion coefficient of the tool base, tensile stress remains in the hard coating layer. Chipping is likely to occur during cutting, especially under heavy cutting conditions, due to residual stress in the layer.

(B) On the other hand, a single basic shape mark, for example, a single basic shape mark such as a circle, a triangle and a quadrangle, or a similar shape thereof, is used for either the rake face or the flank face of the tool base, or these The single basic shape mark and the single basic shape, as shown in the embodiment in which the single basic shape mark is circular, for example, in FIGS. One or both of the mark set marks are distributed and distributed (in this case, the layers shown in FIGS. 1 to 3 have a relatively thin hard coating layer and are shown in FIGS. 4, 5 and 5 and 7). The distribution form in the case where the layer thickness increases as it is done), and the condition that the single basic shape mark is a dug surface where any one of the constituent layers of the hard coating layer is exposed (in this case) The single basic of The depth of the exposed surface of the mark mark is individually adjusted in accordance with the layer thickness of the hard coating layer, but in order to reduce the residual stress efficiently, the depth corresponding to 5 to 20% of the layer thickness The residual stress of the hard coating layer is remarkably reduced, and the coated cutting tool formed with this hard coating layer residual stress reduction pattern is particularly suitable for heavy cutting conditions with high loads. When cutting at, the occurrence of chipping due to residual stress in the hard coating layer is further suppressed, and excellent cutting performance is demonstrated over a long period of time.
The research results shown in (a) and (b) above were obtained.

This invention has been made based on the above research results, and it covers the rake face and flank face of the tool base, and the entire surface of the cutting edge ridge line where these both faces meet.
(A) 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 as a lower layer, and having an overall average layer thickness of 3 to 12 μm,
(B) Al ₂ O ₃ layer having an average layer thickness of 1 to 6 μm as an upper layer,
In the coated cutting tool formed by vapor-depositing the hard coating layer composed of (a) and (b) above,
Either one or both of the rake face and the flank face, or the single basic shape mark and the set mark of the single basic shape mark are distributed over the entire surface of both the rake face and flank face. One basic shape mark is formed by irradiating a laser beam with a hard coating layer residual stress reduction pattern in which any one of the constituent layers of the hard coating layer is exposed.
The hard coating layer is characterized by a coated cutting tool that exhibits excellent chipping resistance in heavy cutting.

In addition, regarding the hard coating layer of the coated cutting tool of the present invention, the lower Ti compound layer exists as a lower layer of the Al ₂ O ₃ layer, and the high temperature strength of the hard coating layer is improved by the excellent high temperature strength possessed by itself. In addition to contributing firmly to the tool substrate and the Al ₂ O ₃ layer, it has the effect of improving the adhesion of the hard coating layer to the tool substrate, but if the overall average layer thickness is less than 3 μm, The above-mentioned action cannot be sufficiently exerted. On the other hand, if the total average layer thickness exceeds 12 μm, it becomes easy to cause thermoplastic deformation causing uneven wear, so the total average layer thickness is 3 to 12 μm. The upper Al ₂ O ₃ layer has excellent high-temperature hardness and heat resistance and contributes to improving the wear resistance of the coated cutting tool. However, if the average layer thickness is less than 1 μm, Good wear resistance desired The can not be exerted for a long time, whereas when the average layer thickness becomes too thick beyond the 6 [mu] m, since the chipping is likely to occur, it's the average layer thickness was defined as 1 to 6 m.

  In the coated cutting tool of the present invention, either or both of the rake face and the flank face, or both of the single basic shape mark and the collective mark of the single basic shape mark are distributed over the entire surface of both surfaces. In addition, a hard coating layer residual stress reduction pattern in which the single basic shape mark is formed as a dug surface where any one of the constituent layers of the hard coating layer is exposed is formed by laser beam irradiation. Because the tensile residual stress in the coating layer is extremely small, cutting of various steels and cast iron, etc., when used to perform heavy cutting conditions such as high cutting with high load and high feed, It exhibits excellent chipping resistance and exhibits excellent wear resistance over a long period of time.

  Next, the coated cutting tool 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 performing the processing, tool bases A to F made of WC-base cemented carbide having a tool shape specified in ISO · CNMG160608 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. Tool bases a to f made of TiCN base cermet having a standard / CNMG160608 chip shape were formed.

Then, each of these tool bases A to F and tool 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. Under the conditions shown in Table 4), the Ti compound layer and the Al ₂ O ₃ layer having the target layer thickness shown in Table 4 are vapor-deposited as the lower layer and the upper layer of the hard coating layer,
Next, using a laser beam irradiation device, the hard coating layer,
Laser beam output: 10W
The shape of a single basic shape mark: a circle with a diameter of 0.5 mm,
Hard coating layer residual stress reduction pattern: any one of the implementation patterns shown in FIGS. 1 to 7 is applied in the combination shown in Table 4.
Depth of exposed surface of single basic shape mark: Depth shown as a percentage of total target layer thickness in Table 4,
The coated cutting tools 1 to 13 of the present invention were produced by forming a hard coating layer residual stress reduction pattern under the conditions described above.

  For comparison purposes, as shown in Table 5, conventionally coated cutting tools 1 to 13 were produced under the same conditions except that the hard coating layer residual stress reduction pattern was not formed on the hard coating layer.

  Moreover, when the thickness of the structural layer of the hard coating layer of the said invention coated cutting tool 1-13 and the conventional coated cutting tool 1-13 was measured using the scanning electron microscope (longitudinal section measurement), all were target. The average layer thickness (average value of 5-point measurement) substantially the same as the layer thickness was shown.

Next, for the various coated cutting tools of the present invention coated cutting tools 1 to 13 and the conventional coated cutting tools 1 to 13, all of them are screwed to the tip of the tool steel tool with a fixing jig,
Work material: JIS / FC300 round bar,
Cutting speed: 300 m / min,
Incision: 3mm,
Feed: 0.3mm / rev,
Cutting time: 10 minutes,
A continuous continuous high-cutting cutting test of cast iron under the conditions (cutting condition A) (normal cutting is 2 mm),
Work material: JIS · S45C lengthwise equal 4 round grooved round bars,
Cutting speed: 300 m / min,
Cutting depth: 2mm,
Feed: 0.5mm / rev,
Cutting time: 10 minutes,
Carbon steel dry intermittent high feed cutting test under normal conditions (referred to as cutting condition B) (normal feed is 0.3 mm / rev),
Work material: JIS · SCM440 lengthwise equidistant 4 vertical grooved round bar,
Cutting speed: 250 m / min,
Cutting depth: 3.5mm,
Feed: 0.35mm / rev,
Cutting time: 10 minutes,
A dry interrupted high cut cutting test (normal cutting is 2 mm) of the alloy steel under the above conditions (referred to as cutting conditions C) was performed, and the flank wear width of the cutting blade was measured in any cutting test. The measurement results are shown in Table 6.

  From the results shown in Tables 4 to 6, all of the coated cutting tools 1 to 13 of the present invention have a residual tensile stress in the hard coating layer due to the hard coating layer residual stress reduction pattern formed by laser beam irradiation on the hard coating layer. Since it is remarkably reduced, even when cutting under heavy cutting conditions with high loads such as high cutting and high feed of steel and cast iron, the hard coating layer does not generate chipping and has excellent cutting performance over a long period of time. In contrast, in the conventional coated cutting tools 1 to 13 without the formation of the hard coating layer residual stress reduction pattern, chipping occurs in the hard coating layer in the cutting under the heavy cutting conditions, It is clear that the service life is reached in a relatively short time.

  As described above, the coated cutting tool 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 particularly when the cutting is performed under heavy cutting conditions with high load. Since it exhibits excellent chipping resistance and exhibits excellent cutting performance over a long period of time, it can sufficiently satisfactorily cope with labor saving and energy saving of cutting work and cost reduction.

It is a schematic perspective view of this invention coating cutting tip which formed the hard coating layer residual stress reduction pattern as an Example by laser beam irradiation formation. FIG. 2 is a schematic perspective view of a coated cutting tip of the present invention in which a hard coating layer residual stress reducing pattern as an embodiment other than FIG. 1 is formed by laser beam irradiation. FIG. 3 is a schematic perspective view of a coated cutting tip of the present invention in which a hard coating layer residual stress reducing pattern as an embodiment other than FIGS. FIG. 4 is a schematic perspective view of a coated cutting tip of the present invention in which a hard coating layer residual stress reduction pattern as an embodiment other than FIGS. FIG. 5 is a schematic perspective view of a coated cutting tip of the present invention in which a hard coating layer residual stress reducing pattern as an embodiment other than FIGS. FIG. 6 is a schematic perspective view of a coated cutting tip of the present invention in which a hard coating layer residual stress reduction pattern as an embodiment other than FIGS. FIG. 7 is a schematic perspective view of a coated cutting tip of the present invention in which a hard coating layer residual stress reducing pattern as an embodiment other than FIGS. 1 to 6 is formed by laser beam irradiation.

Claims (1)

Over the rake face and flank face of the tool base made of tungsten carbide-based cemented carbide or titanium carbonitride-based cermet, and further across the entire surface of the cutting edge ridge line where these both sides intersect,
(A) The lower layer is composed of one or more of a titanium carbide layer, a titanium nitride layer, a titanium carbonitride layer, a titanium carbonated carbon layer, and a titanium carbonitride oxide layer, and has an overall average of 3 to 12 μm. A Ti compound layer having a layer thickness,
(B) As an upper layer, an aluminum oxide layer having an average layer thickness of 1 to 6 μm,
In the surface-coated cermet cutting tool formed by vapor-depositing the hard coating layer composed of (a) and (b) above,
Either one or both of the rake face and the flank face, or the single basic shape mark and the set mark of the single basic shape mark are distributed over the entire surface of both the rake face and flank face. The hard coating layer residual stress reduction pattern was formed by laser beam irradiation, with one basic shape mark as a dug surface where any one of the constituent layers of the hard coating layer was exposed,
A surface-coated cermet cutting tool with a hard coating layer that exhibits excellent chipping resistance in heavy cutting.

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