JP5517577B2 - Cutting tool for grooving - Google Patents

Description

  The present invention relates to a cutting tool for grooving in which a coating layer is formed on the surface of a substrate.

  In recent years, cutting tools have been demanded for more efficient cutting, and it is not preferable that the cutting edge of the tool is locally worn or chipped to reach the tool life. In a cutting tool for grooving, local abnormal wear occurs on the side of the flank of the side cutting edge, and the front cutting edge is not worn so much, but it has a wear form that becomes the tool life. There were many things that happened. Therefore, when the coating layer is formed thick, there is a problem that the coating layer peels off at the cutting edge portion.

  Therefore, for example, in Patent Document 1, it is possible to remove several layers of the multilayer film on the edge of the cutting edge from the chip on which the multilayer film is formed on the surface of the substrate, thereby preventing peeling of the film and chipping of the blade edge. It is disclosed.

JP-A-8-11005

  However, even if the configuration in which several coating layers are removed from the cutting edge as in Patent Document 1 is simply adopted in the grooving chip, only the flank side of the side cutting edge is abnormally worn due to boundary damage. It was found that since the defects were not solved and the surface condition of the cut surface deteriorated, the quality of the work deteriorated and the tool had to be replaced, and the tool life was not extended.

  The present invention enables fine adjustment of the characteristics of the coating layer in the front cutting edge and the side cutting edge of the coating layer, and can optimize the performance of the front cutting edge and the side cutting edge required for grooving cutting performance. The purpose is to provide a chip.

The cutting tool for grooving according to the present invention forms a coating layer on the surface of the substrate, the front cutting edge is constituted by a single layer of the first coating layer having a small average crystal width, and the side cutting blade has the first layer described above. In the first coating layer, the second layer is composed of a multilayer that is a second coating layer having a larger average crystal width than the first coating layer, and the first coating layer and the second coating layer are the same. It consists of a composition .

  According to the cutting tool for grooving of the present invention, the front cutting edge is constituted by a single layer of the first coating layer having a small average crystal width, so that the cutting edge is sagged even when cutting is started and the sharpness is deteriorated. There is no. In addition, since the second cutting layer having a large average crystal width is formed on the upper portion of the first coating layer, the surface of the horizontal cutting blade wears relatively quickly and becomes a shape along the processing surface. The finished state of the processed surface is improved and the wear resistance of the entire coating layer is high.

It is a schematic perspective view about an example of the throw away tip which is a suitable example of the cutting tool for grooving of this invention. 2A is a schematic view of the chip as viewed from above, and FIG. 2B is a schematic view of the chip as viewed from the tip. They are AA sectional drawing (A), BB sectional drawing (B), and CC sectional drawing (C) of Fig.2 (a). FIG. 2 is a schematic diagram for explaining a honing treatment method after forming a coating layer when manufacturing the throw-away tip of FIG. 1.

  FIG. 1 is a schematic perspective view of a throw-away tip as a preferred example of the cutting tool for grooving according to the present invention, FIG. 1A is a schematic view of the tip as viewed from above, and FIG. 2 and FIG. 2 (a), (A) AA cross-sectional view, (B) BB cross-sectional view, and (C) CC cross-sectional view, FIG.

  As shown in FIG. 1, a throw-away tip (hereinafter simply referred to as a tip) 1 includes a substantially rectangular parallelepiped tip body 2, a rake face 3 provided on the upper end surface of the chip body 2, and a rake face 3. The front cutting edge 4 and the horizontal cutting edge 5 are provided at the leading edge and the both edges, respectively, and a nose cutting edge 7 is formed at the intersection of the front cutting edge 4 and the horizontal cutting edge 5. As shown in FIG. 3, the front cutting edge 4, the side cutting edge 5, and the nose cutting edge 7 are provided with first honings 11, 12, and 13, respectively. It is covered with a coating layer 10. A front relief surface 8 is formed on the side surface following the front cutting edge 4, and a side relief surface 9 is formed on the side surface following the side cutting edge 5. A breaker protrusion 20 is formed on the rake face 3.

  As shown in the cross-sectional view including the front cutting edge 4 in FIG. 3A, the chip 1 is formed as a single layer of the first covering layer 10a having a small average crystal width on the surface of the base 6 in the front cutting edge 4. As shown in the sectional view including the horizontal cutting edge 5 of FIG. 3C, the first layer is the first coating layer 10a and the second layer is the first coating layer 10a. It is comprised by the multilayer which consists of the 2nd coating layer 10b with a larger average crystal width. Thereby, even if it starts cutting with the front cutting edge 4, the front cutting edge 4 does not sag and the sharpness does not deteriorate. Further, in the horizontal cutting edge 5, the second coating layer 10b having a large average crystal width is disposed above the first coating layer 10a, so that the surface of the horizontal cutting edge 5 wears relatively quickly and follows the processing surface. The shape and the finished state of the processed surface are improved, but the overall wear resistance of the coating layer 10 is high.

  The desirable range of the average crystal width of the crystals constituting the first coating layer 10a is 0.01 to 0.1 μm, and the desirable range of the average crystal width of the crystals constituting the second coating layer 10b is 0.1 to 0.1 μm. 0.3 μm. This provides a good balance between wear resistance and chipping resistance in the front cutting edge 4 and the side cutting edge 5.

  Moreover, the desirable thickness of the 1st coating layer 10a in the front cutting edge 4 is 0.5-3.0 micrometers, The desirable thickness of the 1st coating layer 10a in the horizontal cutting edge 5 is 0.5-3.0 micrometers, 2nd. A desirable thickness of the coating layer 10b is 2.0 to 5.0 μm. This provides a good balance between wear resistance and chipping resistance in the front cutting edge 4 and the side cutting edge 5. In addition, since the thickness of the coating layer 3 in the front cutting edge 4 and the side cutting edge 5 may be increased or decreased, it is measured at the center position of each of the front cutting edge 4 and the side cutting edge 5.

Further, the first honing 11 is formed on the surface of the base 6 in the front cutting edge 4, and the second honing 14 is formed on the surface of the first coating layer 10 a of the front cutting edge 4. When the removal amounts a ₁ and a ₂ on the rake face 3 side of the first honing 11 and the second honing 14 are compared with the removal amounts b ₁ and b ₂ on the flank face side, a ₁ / it who b ₁ ratio is less than _a 2 / _{b 2} ratio of the second honing 14 is desirable. As a result, the cutting edge 4 emphasizes sharpness and the wear resistance is further increased, and the side cutting edge 5 emphasizes chipping resistance and can suppress chipping and delamination.

In the tip 1, the rake angle α ₁ at the front cutting edge 4 is larger than the rake angle α _{2 at the} nose cutting edge 7 and the rake angle α _{3 at the} side cutting edge 5 as shown in FIG. This configuration has the effect of improving the fracture resistance of the nose cutting edge 7. In FIG. 3, β ₁ , β ₂ , and β ₃ are clearance angles at the front cutting edge 4, the nose cutting edge 7, and the side cutting edge 5, respectively.

  Furthermore, the base 6 constituting the chip 1 is made of a hard sintered body such as cemented carbide, cermet, ceramics, diamond, or cBN.

(Production method)
A method for manufacturing the above chip will be described with a specific example. First, raw material powders are mixed at a predetermined ratio, formed into a predetermined shape, and fired. Next, the sintered body is subjected to a surface grinding process as desired, and then a honing process is performed on the cutting edge portion. According to the desirable manufacturing method of the present invention, the honing treatment conditions at this time employ a blasting method using a cutting fluid. The honing amount at the front cutting edge 4 is such that the ratio a ₁ / b ₁ between the honing (removal) amount a ₁ viewed from the rake face 3 side and the honing (removal) amount b ₁ viewed from the front flank 8 side becomes smaller. That is, it is desirable to process the honing amount a on the rake face side to be small. A desirable range of the ratio a ₁ / b ₁ is 0.6 to 1.2.

  Next, the coating layer 10 is formed on the fired substrate 6. A physical vapor deposition (PVD) method such as an ion plating method can be suitably applied as a method for forming the coating layer 10. Examples of the target include metal titanium (Ti), metal aluminum (Al), and metal M (where M is one or more selected from Group 4, 5, 6 elements, rare earth elements and Si in the periodic table excluding Ti). Can be used, a metal target containing these independently, an alloy target obtained by compounding these, and a mixture target composed of these compound powders or sintered bodies.

Then, using a target, the metal source is evaporated and ionized by arc discharge, glow discharge, or the like, and at the same time, nitrogen (N ₂ ) gas as a nitrogen source or methane (CH ₄ ) / acetylene (C ₂ H ₂ ) gas as a carbon source. As a result, the coating layer 10 is deposited on the surface of the substrate 6. Further, arc discharge or glow discharge is used to generate plasma, and nitrogen (N ₂ ) gas as a nitrogen source or methane (CH ₄ ) / acetylene (C ₂ H ₂ ) gas as a carbon source is used as an introduction gas. Can be used. Then, a film is formed in a state where nitrogen (N ₂ ) gas or argon (Ar) gas is supplied. Further, it is desirable that the bias voltage during film formation is set to 30 to 125 V in order to reduce the internal stress of the coating layer 10.

Here, in this embodiment, the 1st coating layer 10a and the 2nd coating layer 10b are formed in order. At that time, using the same target, the bias voltage is set as high as 70 to 125 V when the first cover layer 10 a is formed, and is set as low as 30 to 70 V when the second cover layer 10 b is formed. By forming the film, the laminated structure of the coating layer 10 in the horizontal cutting blade 5 described above can be formed.

Then, according to the present embodiment, after the film formation is finished, as shown in FIG. 4, the surface of the cutting tool 1 including the side cutting edge 5 is covered with the masking 22 and then honing is performed again. As the honing process conditions at this time, honing is preferably performed by brush polishing. Specifically, honing is performed by placing the rake face side of the chip in a direction facing the brush tip. Then, the honing (removal) amount a ₂ viewed from the rake face 3 side and the honing (removal) amount viewed from the front flank 8 side with respect to the shape of the first honing 11 applied to the surface of the base 6 described above. the ratio a _{2 /} b ₂ and b ₂ is increased, i.e. it is desirable to process the shape of the second honing 14 as honing amount a ₂ of the rake face side becomes large. A desirable range of the ratio a ₂ / b ₂ is 1.2 to 2.0.

WC powder, Co powder, Cr ₃ C ₂ powder and VC powder are mixed, press-molded into a chip shape of a throw-away chip for grooving (Kyocera throw-away chip model number GMM3020-040MW), and fired for grinding Further, honing was performed by blasting using MYBLAST MY-40 (alumina powder) as a medium. Thereafter, the sample is placed in a film forming apparatus, nitrogen (N ₂ ) gas is introduced into the chamber, and a coating layer having a thickness shown in Table 1 is formed by the PVD method under the conditions shown in Table 1. It produced (sample No. 1-6). During the film formation, the bias voltage was changed to the conditions shown in Table 1 for film formation. After that, as shown in FIG. 4, the center portion excluding the front cutting edge portion of the tip including the horizontal cutting edge is masked with carbon tape, and the front cutting edge, the nose cutting edge and the front flank portion are exposed. Brush processing was performed, and the second coating layer on the front cutting edge was removed by polishing. Sample No. For No. 6, brush honing was performed without masking.

The obtained chip was observed with a microscope, and the amount of honing when viewed from the rake face side of the front cutting edge and the side cutting edge and the amount of honing when viewed from the flank face side were measured. Further, each cross section including the front cutting edge and the side cutting edge of the chip is observed with a scanning electron microscope, and the first honing amount (the honing amount a ₁ when viewed from the rake face side) is determined from the cross-sectional substrate shape. The honing amount b ₁ ) when viewed from the flank side and the second honing amount (the honing amount a ₂ when viewed from the rake side and the honing amount b ₂ when viewed from the flank side) were estimated. Furthermore, components constituting the coating layer were analyzed by energy dispersive spectroscopic analysis, and the composition of the coating layer was calculated. Moreover, the transmission electron microscope observation was performed in the said cross section, and the average crystal width (it describes with a crystal width in a table | surface) and average thickness (it describes with thickness in a table | surface) in each site | part were measured. The results are shown in Table 2.

And this chip | tip was mounted | worn to the holder, the following cutting tests were done, and cutting performance evaluation was performed.
Cutting method: Grooving work material: SNCM439
Cutting speed: 200 m / min Feed: 0.1 mm / rev
Cutting depth: 2.0mm
Cutting state: wet evaluation method: After cutting for 60 minutes, the state of the cutting edge was confirmed, and the wear amount of the flank (tip (front cutting edge), side flank (lateral cutting edge)) was measured. After the measurement, the cutting time was further continued to evaluate the workable time until the chip reached the end of its life. The results are shown in Table 3.

  As apparent from the results of Tables 1 to 3, the sample No. 2 in which the second layer was not polished and removed by the front cutting edge or the side cutting edge was obtained. In No. 6, the progress of wear on the side clearance surface was fast and the tool life was short. In addition, the sample No. 2 in which the second layer was polished and removed in both the front cutting edge and the side cutting edge was used. No. 5, the wear on the side flank was fast, the tool life was short, and the cut surface was rough. Furthermore, sample No. 1 in which the entire coating layer was formed under the same conditions. In No. 7, the coating layer on the lateral flank face was peeled off and was worn relatively quickly.

  On the other hand, according to the present invention, the front cutting edge is composed of a single layer of the first coating layer having a small average crystal width, and the horizontal cutting blade has the first coating layer as the first layer and the first coating as the second layer. Sample No. 2 composed of multiple layers of the second coating layer having an average crystal width larger than that of the layer. In each of 1-4, the progress of wear was suppressed, and the tool life was long.

1 Throw away tip (chip)
2 Chip body 3 Rake face 4 Front cutting edge 5 Horizontal cutting edge 6 Base body 7 Nose cutting edge 8 Front relief face 9 Lateral relief face 10 Coating layer 10a First coating layer 10b Second coating layers 11, 12, 13 First honing 14 Second honing 20 Breaker protrusion 22 Masking

Claims (1)

A coating layer is formed on the surface of the substrate, the front cutting edge is constituted by a single layer of the first coating layer having a small average crystal width, the horizontal cutting blade has the first coating layer as the first layer, and the second layer as the above. A cutting tool for grooving , which is composed of a multilayer that is a second coating layer having an average crystal width larger than that of the first coating layer, and in which the first coating layer and the second coating layer have the same composition .

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