JP5127477B2 - Cutting tools - Google Patents

Description

  The present invention relates to a cutting tool formed by forming a coating layer on the surface of a substrate.

  Currently, cutting tools require wear resistance, slidability, and fracture resistance, so various coating layers are formed on the surface of a hard substrate such as a WC-based cemented carbide or TiCN-based cermet to cover the surface. Techniques to improve the wear resistance and fracture resistance of tools are used. As the coating layer, a TiCN layer or a TiAlN layer is generally widely used, but various coating layers are being developed for the purpose of improving higher wear resistance and fracture resistance.

  For example, in Patent Document 1, in the formation of a TiCN coating layer formed by the CVD method, the supply flow rate of the mixed gas is adjusted to 3 to 10 times, and the tip of the nose R of the obtained coating layer is adjusted. The X-ray diffraction intensity near the end (edge) of the corresponding honing is different from that at the center of the flank. Specifically, when the peak intensity of the (111) plane and the peak intensity of the (220) plane are compared, It is disclosed that the ratio of the peak intensity of the (111) plane is higher than that of the central portion of the flank.

  Patent Document 2 describes that a TiAl compound film is formed under conditions where the absolute value of the negative bias voltage is gradually increased, and a coating layer having a high Ti / Al ratio only at the edge is described. .

Furthermore, in Patent Document 3, utilizing the property that the Ti / Al ratio changes only at the edge when the TiAl compound film is formed under conditions where the substrate voltage (bias voltage) is low (the absolute value of minus is large), By changing the substrate voltage during film formation, the proximity portion of the edge ridge line is composed of two or more layers having different Ti / Al ratios, and the central portion excluding the proximity portion of the edge ridge line is Ti. It is disclosed that a covering member such as a tool constituted by a single layer film having a constant ratio of / Al can be produced.
JP-A-10-237648 JP-A-8-267306 JP 2003-113463 A

  However, a TiCN film in which the peak intensity ratio of the X-ray diffraction at the edge portion is changed as in Patent Document 1 above, or a TiAl-based film in which the Ti / Al ratio in the edge portion is changed as in References 2 and 3 However, further wear resistance at the edge portion has been demanded. In addition, in the central portion other than the edge, the chips generated by the cutting blade by the cutting are bent and curled by the rake face, and the curled chips randomly hit the central portion other than the edge portion and the coating layer is partially peeled off. In the central portion other than the edge portion, there has been a demand for high impact resistance that does not separate even when chips collide.

  An object of this invention is to provide the cutting tool which has the abrasion resistance in a cutting blade, and the peeling resistance which a coating layer does not peel also in parts other than the edge which a chip collides.

The cutting tool of the present invention is a cutting tool in which a crossing ridge line portion between a rake face and a flank face is used as a cutting edge, and a coating layer is coated on the surface of a substrate. However, the particles are observed as granular particles having an average particle diameter of 0.5 to 2 μm at the cutting edge part, and the average particle diameter is smaller than the cutting edge part at the central part away from the cutting edge part, and the average particle diameter is 0. 1-0.8μm
It is observed as granular particles, characterized in Rukoto.

Here, in the above configuration, it is desirable that the skewness R _ske at the surface of the coating layer in the cutting edge portion is smaller than the skewness R _skc at the surface of the coating layer in the central portion (R _ske <R _skc ). .

  Further, in the above configuration, a structure obtained by observing the coating layer with a microscope from a cross section is observed as vertically long particles having an average particle width of 0.02 to 0.3 μm in the cutting edge portion, and an average particle width in the central portion. It is desirable to observe as vertically long particles of 0.1 to 0.5 μm.

Further, in the above structure, the hardness H _e at the surface of the coating layer in the cutting edge is higher (H _{e> H c)} is more desirable than the hardness H _c at the surface of the coating layer in the central portion .

In the above configuration, the coating layer is made of Ti _1-ab Al _a M _b (C _x N _1-x ) (where M is a periodic table 4, 5, or 6 element excluding Ti, Y and Si 1 or more selected from the group consisting of 0.40 ≦ a ≦ 0.65, 0 ≦ b ≦ 0.3, and 0 ≦ x ≦ 1).

  The cutting tool of the present invention has low initial wear, low cutting resistance and high wear resistance at the cutting edge. Moreover, the impact resistance is high in the central portion, and the coating layer is difficult to peel off even when chips collide.

Here, the skewness R _{ske on} the surface of the coating layer in the cutting edge part is smaller than the skewness R _skc on the surface of the coating layer in the central part (R _ske <R _skc ), so that Is desirable in that the initial wear is small, the cutting resistance is small and the wear resistance is high, and the impact at the time of chip collision can be absorbed in the central portion.

In addition, the structure obtained by observing the coating layer with a microscope from a cross-section is observed as vertically long particles having an average particle width of 0.02 to 0.3 μm in the cutting edge portion, and an average particle diameter of 0.1 to 0.1 in the central portion. By being observed as 0.5 μm vertically long particles, the wear resistance at the cutting edge portion is higher and the impact resistance at the center portion is higher. At this time, the hardness H _e at the surface of the coating layer in the cutting edge is at high (H _{e> H c)} it is more desirable than the hardness H _c at the surface of the coating layer in the central portion .

In the above configuration, the coating layer is made of Ti _1-ab Al _a M _b (C _x N _1-x ) (where M is a periodic table 4, 5, or 6 element excluding Ti, Y and Si 1 or more selected from the group consisting of 0.40 ≦ a ≦ 0.65, 0 ≦ b ≦ 0.3, and 0 ≦ x ≦ 1) can improve the hardness and oxidation resistance of the coating layer Is desirable.

  As shown in FIG. 1, a cutting tool (hereinafter simply abbreviated as a tool) 1 according to the present invention has a cutting edge 5 as an intersecting ridge line portion between a rake face 3 and a flank face 4, and as shown in FIG. The surface is coated with a coating layer 7.

And according to this invention, as FIG. 2 which shows the scanning electron micrograph about (a) a cutting blade part and (b) center part about an example of the coating layer about the suitable embodiment of the tool 1 is clear. The structure obtained by observing the coating layer 7 coated on the surface of the substrate 6 with a microscope from the outer surface is observed as granular particles having an average particle diameter of 0.5 to 2 μm in the cutting blade portion 5, and from the cutting blade portion 5. in remote central 8, the average particle diameter is smaller than the cutting edge 5, and Rukoto observed as granular particles having an average particle size 0.1~0.8μm is a significant feature. Accordingly, the cutting edge portion 5 has a low initial wear and a low cutting resistance and a high wear resistance, and the central portion 8 has a high impact resistance and the coating layer 7 is difficult to peel off even when chips collide. It has become.

Here, the skewness R _{ske on} the surface of the coating layer 7 in the cutting edge part 5 is smaller than the skewness R _skc on the surface of the coating layer 7 in the central part 8 (R _ske <R _skc ), so that the cutting edge part No. 5 is desirable in that the initial wear is small and the cutting resistance is low and the wear resistance is high, and the center portion 8 can absorb the impact when chips collide. The measurement of skewness measures the surface state of the coating layer 7 by an atomic force microscope (AFM), in the present invention a method of calculating in Ji order provisions of skewness S _sk defined from the irregularities in JISB0601 Can be suitably employed.

  Further, a structure obtained by observing the coating layer 7 with a microscope from a cross-section is observed as vertically long particles having an average particle width of 0.02 to 0.3 μm in the cutting edge portion 5, and an average particle width of 0.1 to 0.1 in the central portion 8. It is desirable to be observed as 0.5 μm long particles. As a result, the wear resistance at the cutting edge portion 5 is higher and the impact resistance at the central portion 8 is higher. That is, it is desirable that the particles contained in the coating layer 7 have a structure that is vertically long when viewed from the cross-sectional direction and looks granular when viewed from the outer surface.

  Here, according to the present invention, the surface of the coating layer 7 is struck more strongly at the cutting edge portion 5 than the central portion 8 by the surface treatment performed during film formation, and is deposited on the outer surface of the coating layer 7. The fine particles re-evaporate. At this time, since the surface property of the coating layer 7 is controlled to be flat under the surface treatment conditions of the present invention, the average particle size of the particles in the tissue measured when observed from the outer surface with a microscope is It is observed to be larger than the average particle width of the particles in the structure measured when observed with a microscope from the cross section as in the above range. In addition, since fine particles are removed from the surface of the coating layer 7 by this process, when the coating layer 7 is subsequently formed, the nucleation is returned to the initial state, which is higher than that in the case where the surface treatment is not performed. It is considered that the particles to be formed are fine.

  On the surface of the coating layer 7, as shown in FIG. 2, the particles in the cutting edge portion 5 disappear due to the erosion of the interface between the particles by the surface treatment, and only a part of this interface remains. . And the remaining part of the interface which connects particle | grains is located in a line, and the part where the interface between this particle | grains disappeared became large in the specific direction, and it has become the structure | tissue where the particle itself was angular. On the other hand, in the central portion 8, particles are hardly re-evaporated while being formed into a film, so that a structure in which fine particles are aggregated is formed.

  In the present invention, the vertically long particles refer to particles that have grown long vertically to the surface of the substrate 6 as shown in FIG. 3, and the vertically long particles reduce internal stress generated in the coating layer 7. Since the fracture resistance of the tool 1 can be improved, stable film formation is possible without self-destruction even when the thickness of the coating layer 7 is increased, and the fracture resistance is improved because the toughness of the coating layer 7 is high. Therefore, the coating layer 7 is difficult to chip, and even when the thickness of the coating layer 7 is 0.5 to 6 μm, the coating layer 7 can be prevented from peeling or chipping, and sufficient wear resistance can be maintained. it can.

Further, the particle width of the vertically long particles in the coating layer 7 is measured by a line A drawn to a portion corresponding to an intermediate thickness of the coating layer 7 forming the vertically long particles. The average particle width w _t of the longitudinally long particles in the coating layer 7 specifies the length L of the line A (however, 100 nm or more), and the number of grain boundaries crossing the line A of this length L is counted. It can be calculated by the number of grain boundaries.

Further, the cutting edge 5 has a hardness H _{e on} the surface of the coating layer 7 in the cutting edge 5 higher than the hardness H _c on the surface of the coating 7 in the central part 8 (H _e > H _c ). This is desirable in terms of both improvement in wear resistance and improvement in fracture resistance in the central portion 8.

The covering layer 7 may be composed of simple Ti _1-a Al _a N. For example, Ti _1-a-b Al _a M _b (C _x N _1-x ) (however, M Is one or more selected from Group 4, 5, 6 elements of the periodic table excluding Ti, rare earth elements, and Si, and 0 ≦ a <1, 0 <b ≦ 1, and 0 ≦ x ≦ 1. It may be configured. Among them, Ti _1-a-b Al _a M _b (C _x N _1-x ) (where M is one or more selected from Group 4, 5 and 6 elements in the periodic table excluding Ti and Al, Y and Si, 0.40 ≦ a ≦ 0.65, 0 ≦ b ≦ 0.3, and 0 ≦ x ≦ 1) are desirable from the viewpoint of increasing the hardness and oxidation resistance of the coating layer 7. Further, among the above _{composition, Ti 1-a-b-} c-d Al a M b W c Si d (C x N 1-x) ( where periodic table 4, 5 M is, except for Ti and W 1 or more selected from group 6 elements and rare earth elements, and 0.4 ≦ a ≦ 0.65, 0 ≦ b ≦ 0.3, and 0 ≦ x ≦ 1). In the composition region, the oxidation start temperature is high, the oxidation resistance is high, the wear resistance at the time of cutting is improved, and the chipping that is likely to occur at the tip of the cutting edge can be suppressed, and the fracture resistance is high. Further, the metal M is at least one selected from Nb, Mo, Ta, Hf, and Y. Among them, the inclusion of Nb or Mo is desirable in terms of the most excellent wear resistance and oxidation resistance.

  Furthermore, C and N which are non-metallic components of the coating layer 7 are excellent in hardness and toughness required for the cutting tool, and in order to suppress excessive generation of droplets generated on the surface of the coating layer 7, A particularly desirable range of x (C content ratio) is 0 ≦ x ≦ 0.5. The composition of the coating layer 7 can be measured by energy dispersive X-ray spectroscopy (EDS) analysis or X-ray photoelectron spectroscopy (XPS) analysis.

  In the cutting tool 1 of the present invention, the above-described configuration can be realized even if the surface of the coating layer 7 is not machined, and can be applied to the tool 1 having a complicated shape, and the manufacturing process can be simplified. Is possible.

Further, there is a tendency that the layer thickness t _e of the coating layer 7 in the cutting edge 5 becomes thinner than the thickness t _c of the coating layer 7 in the central portion 8, the layer thickness at the ratio (cutting edge 5 t _e / The layer thickness t _c ) at the central portion 8 is preferably 0.7 or more in order to increase the wear resistance of the tool 1. Further, the composition of the coating layer 7 is such that the ratio of Ti to the total amount of Ti and Al of the coating layer 7 in the cutting edge portion 5 is Ti _e , and the ratio of Ti to the total amount of Ti and Al of the coating layer 7 in the central portion 8 When Ti is _c , Ti _e / Ti _c is 1 to 1.2, which optimizes the balance between the wear resistance required for the cutting edge part 5 and the fracture resistance required for the central part 8 Is desirable.

The content ratio of each element in the coating layer 7 can be measured using an energy dispersive X-ray spectroscopy (EDS) analyzer provided in the transmission electron microscope measurement device. The content ratio is calculated by the ratio between the total peak intensity of each element and the peak intensity of the Ti element. Here, the peak of the Lα ray of Ti (energy around 0.4 keV) in the energy dispersive X-ray spectroscopy (EDS) analysis method cannot be accurately measured because it overlaps with the Kα ray peak of the N element. If there is a possibility that Ti is contained, this peak is excluded from the peak used for calculation, and Ti _e and Ti _c are also calculated using the peak of Ti Kα ray (energy around 4.5 keV), and the ratio Ti _e / Ti _c is obtained. Further, according to the present invention, when measuring Ti _e and Ti _c , the average value is obtained based on the measured values at five or more arbitrary locations of the coating layer 7.

  In addition, as the substrate 6, in addition to cemented carbide or cermet composed of tungsten carbide, a hard phase mainly composed of titanium carbonitride, and a binder phase mainly composed of an iron group metal such as cobalt or nickel, silicon nitride And hard materials such as ceramics mainly composed of aluminum oxide, a hard phase composed of multi-particle diamond or cubic boron nitride, and a super-high pressure sintered body in which a binder phase such as ceramics or iron group metal is fired under an ultra-high pressure. Materials are preferably used.

(Production method)
Next, the manufacturing method of the cutting tool of this invention is demonstrated.

  First, a tool-shaped substrate is produced using a conventionally known method. Next, a coating layer is formed on the surface of the substrate. A physical vapor deposition (PVD) method such as an ion plating method or a sputtering method can be suitably applied as the coating layer forming method. An example of the details of the film forming method will be described. When the coating layer is manufactured by the ion plating method, metal titanium (Ti), metal aluminum (Al), metal M (where M is a periodic table excluding Ti). One or more selected from Group 4, 5, 6 elements, rare earth elements and Si) are used independently for metal targets or composite alloy targets.

As the film forming conditions, using this target, the metal source is evaporated and ionized by arc discharge or glow discharge, and at the same time, nitrogen (N ₂ ) gas as a nitrogen source or methane (CH ₄ ) / acetylene (C) as a carbon source. Conditions for reacting with ₂ H ₂ ) gas can be suitably employed. At this time, the sample was heated to 400 to 600 ° C. using nitrogen (N ₂ ) gas or a mixed gas obtained by adding argon (Ar) gas thereto, and the sample was heated to 30 to 200 V by an ion plating method or a sputtering method. A coating layer is formed while applying a bias voltage. At this time, surface treatment is performed for 30 to 60 minutes with a bias voltage of 100 to 300 V before film formation, and film formation is performed while performing surface treatment for 5 to 10 minutes with a bias voltage of 100 to 300 V during film formation. By doing so, the structure of the coating layer of the present invention described above can be formed.

10% by mass of metallic cobalt (Co) powder, 0.2% by mass of vanadium carbide (VC) powder, chromium carbide (Cr ₃ C ₂ ) powder with respect to tungsten carbide (WC) powder having an average particle size of 0.5 μm Was added and mixed at a ratio of 0.8% by mass, molded into an insert shape cutting tool (DCGT11T302FR-U) insert shape, and fired. After the grinding process, the surface was washed in the order of alkali, acid, and distilled water to produce an insert substrate.

And the said base | substrate was set in the arc ion plating apparatus, the base | substrate was heated to the temperature shown in Table 1, and the coating layer shown in Table 1 was formed into a film. The surface treatment conditions during film formation are also shown in Table 1. The film forming conditions were an arc current of 150 A in a mixed gas of nitrogen gas and argon gas in an atmosphere having a total pressure of 4 Pa. The bias voltage is abbreviated as voltage, and the time is the net film formation time excluding the surface treatment time. Furthermore, the time during film formation under the surface treatment conditions in Table 1 indicates the time during which the film was formed before the surface treatment was started.

The obtained insert was subjected to a structure observation at a magnification of 5000 for each of the outer surface and the cross section of the coating layer using a scanning electron microscope (VE8800) manufactured by Keyence, and the properties and layer thickness of the particles constituting the coating layer were observed. (T _e , t _c ) was confirmed. In addition, using the EDAX analyzer (AMETEK EDAX-VE9800) attached to the device, the composition of the coating layer is quantitatively analyzed by the ZAF method, which is a type of energy dispersive X-ray spectroscopy (EDS) analysis method, at an acceleration voltage of 15 kV. Ti / (Ti + Al), which is the ratio of Ti and Al, was calculated for each of the cutting edge part and the central part (cutting edge part Ti _e , central part Ti _c ). For elements that could not be measured by this method, a PHI X-ray photoelectron spectrometer (Quantum2000) was used, and the X-ray source was irradiated with monochrome AlK (200 μm, 35 W, 15 kV) to a measurement region of about 200 μm. Measurements were made. The results are shown in Table 2.

Further, the cross section of the coating layer was observed with a transmission electron microscope (TEM) to confirm the details of the structure state, and the average particle width of the vertically long particles was calculated. The results are shown in Table 2.

Furthermore, the cutting test was done on the following cutting conditions using the obtained insert. The results are shown in Table 2.

Cutting method: Outer turning work material: S45C
Cutting speed: 100 m / minute feed: 0.04 mm / blade cutting: 1.5 mm
Cutting state: wet evaluation method: At the time of cutting for 60 minutes, the flank wear amount, the chipping state at the cutting edge, and the processed surface roughness of the work material are measured.

  From Tables 1 to 3, in the structure in which the coating layer was observed with a microscope from the outer surface, Sample No. observed as granular particles having an average particle size in the cutting edge portion smaller than 0.5 μm. In No. 11, the initial wear at the cutting edge was large and the wear progressed rapidly thereafter. Sample No. in which the average particle size at the cutting edge exceeds 2 μm. 15 also had poor wear resistance at the cutting edge. In addition, Sample No. with an average particle size of less than 0.1 μm in the central portion. In No. 13, chipping resistance was lowered by internal stress, and peeling of the coating layer occurred at the portion where the chips collided. On the other hand, Sample No. with an average particle size in the center exceeding 0.8 μm. 12, peeling of the coating layer due to the collision of chips occurred.

On the other hand, the structure obtained by observing the coating layer with a microscope from the outer surface is observed as granular particles having an average particle diameter of 0.5 to 2 μm at the cutting edge, and at the center portion away from the cutting edge , Sample No. observed as granular particles having an average particle size smaller than the blade portion and having an average particle size of 0.1 to 0.5 μm. In Nos. 1 to 10, the chipping resistance and wear resistance were good and the cutting performance was excellent.

It is a schematic perspective view which shows an example of the cutting tool of this invention. It is an example of the structure | tissue which observed the coating layer of the cutting tool of this invention with the scanning electron microscope from the outer surface, (a) Cutting edge part, (b) Center part. It is an example of the structure | tissue observed with the scanning electron microscope from the cross section containing the coating layer of the cutting tool of FIG. 2, (a) Cutting edge part, (b) Center part.

Explanation of symbols

1 Cutting tool
3 rake face 4 flank face 5 cutting edge part 6 base 7 covering layer 8 center part

Claims (5)

In a cutting tool in which a crossing ridge line portion between a rake face and a flank surface is used as a cutting edge, and the surface of the substrate is coated with a coating layer, the structure of the coating layer observed with a microscope from the outer surface is It is observed as granular particles having an average particle diameter of 0.5 to 2 μm, and in the central part away from the cutting edge part, the average particle diameter is smaller than that of the cutting edge part, and the average particle diameter is 0.1 to 0.8 μm. A cutting tool characterized by being observed as particles. The skewness R _ske at the surface of the coating layer in the cutting edge portion is smaller than the skewness R _skc at the surface of the coating layer in the central portion (R _ske <R _skc ). Cutting tools.   A structure obtained by observing the coating layer with a microscope from a cross section is observed as vertically long particles having an average particle width of 0.02 to 0.3 μm in the cutting edge portion, and an average particle width of 0.1 to 0.3 in the central portion. The cutting tool according to claim 1, wherein the cutting tool is observed as 5 μm long particles. Hardness H _e at the surface of the coating layer in the cutting portion, to claim 1, characterized in said higher than the hardness H _c at the surface of the coating layer (H _{e> H c)} that in the central portion 4. The cutting tool according to any one of 3. The coating layer is Ti _1-ab Al _a M _b (C _x N _1-x ) (where M is one or more selected from the periodic tables 4, 5, 6 elements except Ti, Y and Si) The cutting tool according to claim 1, wherein 0.40 ≦ a ≦ 0.65, 0 ≦ b ≦ 0.3, and 0 ≦ x ≦ 1).