JP4761137B2 - Surface coated cermet cutting tool whose hard coating layer exhibits excellent chipping resistance in heavy cutting - Google Patents

Description

  The present invention provides a surface that exhibits excellent chipping resistance even 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 coated 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,
It is composed of two or more of a titanium carbide (hereinafter referred to as TiC) layer, a titanium nitride (hereinafter also referred to as TiN) layer, and a titanium carbonitride (hereinafter referred to as TiCN) layer, and 3 to 12 μm. A hard coating layer having an overall average layer thickness of
It is well known that a coated cutting tool formed by vapor deposition is used, and this coated cutting tool is used for continuous cutting and intermittent cutting of, for example, various types of steel and cast iron.

Further, in the above-mentioned coated cutting tool, the constituent layer of the hard coating layer generally has a granular crystal structure, and the TiCN layer among them is a normal chemical vapor deposition apparatus for the purpose of improving the strength of the layer itself. It is also known that a mixed gas containing organic carbonitride is used as a reaction gas and is formed by chemical vapor deposition at an intermediate temperature range of 700 to 950 ° C. to have a vertically grown crystal structure. .
JP 48-34912 A Japanese Patent Laid-Open No. 6-8010

  In recent years, the performance of cutting machines has been remarkable. On the other hand, there are strong demands for labor saving and energy saving and further cost reduction for cutting. Accordingly, in order to improve the efficiency of cutting, high cutting and high feed are required. However, the above-mentioned conventional coated cutting tool has a problem when it is used for continuous cutting and intermittent cutting under normal conditions such as steel and cast iron. However, especially when heavy cutting with high cutting and feeding of cutting conditions is performed, chipping (small chipping) is likely to occur in the hard coating layer due to high load during cutting. At present, the service life is reached in a short time.

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-mentioned conventional coated cutting tool is formed by being deposited on the surface of the tool substrate at a reaction temperature of about 1000 ° C. with a chemical vapor deposition apparatus and cooled to room temperature. 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 due to residual stress in the layer, especially during heavy cutting under heavy loads.

(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 6 and 7). The distribution form in the case where the layer thickness becomes thicker is shown) and 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, so that the coated cutting tool formed with this hard coating layer residual stress reduction pattern is particularly heavy under heavy load. When cutting under cutting conditions, the occurrence of chipping 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 hard coating layer composed of two or more of a TiC layer, a TiN layer, and a TiCN layer, and having an overall average layer thickness of 3 to 12 μm,
In a coated cutting tool formed by vapor deposition using a chemical vapor deposition apparatus ,
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.

  The constituent layers of the hard coating layer of the coated cutting tool according to the present invention all have excellent high-temperature strength and excellent wear resistance. It has an effect of tightly adhering to each other, but if the overall average layer thickness is less than 3 μm, the above-mentioned effect cannot be sufficiently exerted, whereas if the overall average layer thickness exceeds 12 μm, it causes uneven wear. Therefore, the total average layer thickness is determined to be 3 to 12 μm.

  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. Since the tensile residual stress in the coating layer is extremely small, various types of steel and cast iron are also used for cutting under heavy cutting conditions such as high cutting and high feed with high loads. It exhibits excellent chipping resistance and 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. The hard coating layer having the target layer thickness shown in Table 4 is formed by vapor deposition under the conditions shown in FIG.
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 / FC250 round bar,
Cutting speed: 250 m / min,
Cutting depth: 3.5mm,
Feed: 0.3mm / rev,
Cutting time: 10 minutes,
Wet continuous high-cut cutting test of cast iron under the above conditions (referred to as cutting condition A) (normal cutting is 2 mm),
Work material: JIS-S35C lengthwise equal length 4 round fluted round bars,
Cutting speed: 280 m / min,
Cutting depth: 2mm,
Feed: 0.55mm / rev,
Cutting time: 10 minutes,
Wet intermittent high feed cutting test of carbon steel under the conditions (cutting condition B) (normal feed is 0.3 mm / rev),
Work material: JIS / SNCM439 round direction bar with 4 equal intervals in the length direction,
Cutting speed: 220 m / min,
Incision: 3mm,
Feed: 0.35mm / rev,
Cutting time: 10 minutes,
Wet intermittent high cutting cutting test of alloy steel under the above conditions (referred to as cutting condition C) (normal cutting is 2 mm), and the flank wear width of the cutting edge 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 with heavy cutting conditions such as high cutting and high feed of steel and cast iron with high loads, the hard coating layer has excellent cutting performance over a long period without chipping. 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 has excellent resistance not only to continuous cutting and interrupted cutting under normal conditions such as various steels and cast iron, but particularly when cutting is performed under heavy cutting conditions. Since it exhibits chipping properties and exhibits excellent cutting performance over a long period of time, it can satisfactorily cope with labor saving and energy saving of cutting work and further 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 hard coating layer composed of two or more of a titanium carbide layer, a titanium nitride layer, and a titanium carbonitride layer, and having an overall average layer thickness of 3 to 12 μm,
In a surface-coated cermet cutting tool formed by vapor deposition using a chemical vapor deposition device ,
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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