JP2012045694A - Cutting tool - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cutting tool having good wear resistance and high thermal shock resistance.SOLUTION: The cutting tool 1 includes a laminated body in which second sintered bodies 3 comprising a carbonitride titanium based cermet are laminated on the upper and lower surface of a first sintered body 2 comprising a titanium diboride (TiB) based sintered body. The cutting edges 7 includes the second sintered body 3. The thickness of the second sintered body 3 is preferably 10-35% of the entire thickness of the cutting tool 1.

Description

  The present invention relates to a cutting tool.

  Currently, cemented carbides mainly composed of WC and cermets mainly composed of TiCN are widely used as cutting tools. It is known that cermet has higher hardness than cemented carbide, but has low thermal shock resistance and easily breaks down suddenly.

For example, Patent Document 1 discloses that a softened layer having a high binder phase concentration is formed on the surface of a cermet to increase the toughness of the cermet. Patent Document 2 discloses a composite ceramics composed of 50 to 80% by weight of TiB ₂ and the balance being TiN. By forming a structure in which TiN particles are taken into TiB ₂ particles, it is easy to sinter and has a hardness. It is disclosed that the ceramic is rich in strength and toughness.

Japanese Patent Laid-Open No. 07-62482 JP 09-208322 A

  However, the configurations of Patent Documents 1 and 2 have a problem that the thermal shock resistance of the sintered body is insufficient.

  The present invention is to solve the above-mentioned problems, and an object thereof is to provide a laminate and a cutting tool having good wear resistance and thermal shock resistance and high cutting performance.

  The cutting tool of the present invention comprises a laminate in which a second sintered body made of titanium carbonitride-based cermet is laminated on the upper and lower surfaces of a first sintered body made of a titanium diboride sintered body, The second sintered body is used.

  Here, the thickness of the second sintered body is preferably 10 to 35% with respect to the thickness of the entire cutting tool.

According to the cutting tool of the present invention, since the cutting edge is made of cermet, the wear resistance is good, and since the TiB ₂ sintered body is disposed at the center of the cutting tool, the thermal shock resistance is also high.

  The thickness of the second sintered body is preferably 10 to 35% with respect to the thickness of the entire cutting tool in terms of maintaining wear resistance and improving thermal shock resistance.

An example of the cutting tool which consists of a laminated body of this invention is shown, (a) A schematic perspective view, (b) A cross-sectional schematic diagram.

  An example of a cutting tool made of the laminate of the present invention will be described with reference to FIG. 1 which is a schematic perspective view thereof and FIG.

  In the cutting tool 1 of FIG. 1, the first sintered body 2 and the second sintered body 3 are made of titanium carbonitride-based cermets on the upper and lower surfaces of the first sintered body 2 made of a titanium diboride sintered body. Hereinafter, the laminate is formed by laminating a second sintered body 3 composed of simply cermet, and the cutting edge 7 is composed of the second sintered body 3.

  With the above configuration, the cutting blade 7 is made of the structure of the second sintered body 3 having high wear resistance, and the first sintered body 2 constituting the central portion has high thermal conductivity. 2 Contributes to the improvement of the thermal shock resistance of the sintered body 3. In addition, the screw hole 14 is formed in the center part of the rake face 8 of the cutting tool 1 of FIG.

The TiB ₂ -based sintered body constituting the first sintered body ₂ is composed of TiB ₂ as a main component, and a carbide of at least one metal selected from the group consisting of Group 4, 5, 6 metals and Si of the periodic table. It consists of nitrides, carbonitrides, oxides, borides, and optionally added iron group metals and the like. On the other hand, the cermet forming the second sintered body 3 is mainly composed of Ti, and a hard phase of carbonitride in which one or more kinds of metals of Group 4, 5, and 6 of the periodic table other than Ti are dissolved, It consists of a binder phase of an iron group metal.

  Here, it is desirable that the thickness of the second sintered body 3 is 10 to 35% with respect to the thickness of the entire cutting tool. In addition, when the 2nd sintered compact 3 exists in both upper and lower layers, the total thickness of the 2nd sintered compact 3 will be 20 to 70% with respect to the thickness of the whole cutting tool. Thereby, the cutting tool 1 with high cutting performance and small deformation can be easily manufactured.

  Further, if there are irregularities on the surface of the first sintered body 2, it is difficult for the second sintered body 3 to peel off and the heat dissipation of the second sintered body 3 is improved.

  Furthermore, the laminated body of the first sintered body 2 and the second sintered body 3 may be obtained by firing at the same time. A method of firing the raw material powder forming the second sintered body 3 adjacent to the first sintered body 2 in a predetermined shape may be used. Alternatively, the first sintered body 2 and the second sintered body 3 may be separately fired and bonded.

(Production method)
Next, an example of the manufacturing method of the cutting tool mentioned above is demonstrated.

Two kinds of mixed raw material powders are prepared as raw materials.
The first raw material powder has a composition having a higher firing temperature than the second raw material powder forming the second sintered body, and has an average particle size of 1 to ₂ μm and TiB ₂ powder and an average particle size of 0.5 to 10 μm. Let it be the raw material powder which mixed the compound powder of the said metal element, and the iron group metal powder with an average particle diameter of 1-3 micrometers.

On the other hand, the second mixed raw material powder has a cermet composition that is sintered at a lower temperature than the first sintered body. Specifically, the TiCN powder having an average particle diameter of 0.6 to 1 μm and an average particle diameter of 0.1 Any one of carbide powders, nitride powders, or carbonitride powders of the above-mentioned other periodic tables Nos. 4, 5 and 6 metals of ˜2 μm, and Co powder having an average particle size of 1.0 to 3.0 μm, A raw material powder obtained by mixing at least one of Ni powder having an average particle size of 0.3 to 0.8 μm and optionally MnCO ₃ powder having an average particle size of 0.5 to 10 μm is used. In addition, although TiC powder and TiN powder may be added to the second raw material, these raw material powders constitute TiCN in the cermet after firing.

Next, it shape | molds in the shape of a cutting tool using the said two different types of mixed raw materials. As a forming method, for example, when a laminated body of the first sintered body and the second sintered body is manufactured by simultaneous firing, the second mixed raw material is arranged on the upper and lower surfaces in the press mold. In addition, it is possible to employ a method of press molding in a state where the first raw material powder is disposed and laminated in the central portion. In addition, a compact that has been press-molded using only the second raw material powder is once fired to prepare a TiB ₂ sintered body, and then a slurry containing the first raw material powder on the surface of the sintered body is provided. The method of apply | coating is also mentioned. According to this method, since the second sintered body is fired once and then fired at a lower firing temperature, the deformation amount w due to sintering is small, and the deformation of the entire sintered body can be suppressed and complicated. Even with a simple shape, the cutting tool 1 with high dimensional accuracy can be easily produced.

  As a method of placing the second raw material powder on the upper / lower surface of the first sintered body, the first sintered body is placed in a mold and the second raw material powder is placed on the upper and lower surfaces thereof. Alternatively, a method in which the first sintered body and the second sintered body are separately manufactured and bonded can be suitably employed.

  Thereafter, the structure can be fired as desired to produce a laminate having the above-described predetermined structure. Then, if desired, a coating layer is formed on the surface of the laminate. 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.

TiB ₂ powder having an average particle diameter (d ₅₀ value) of 1.5 μm, SiC powder having an average particle diameter of 3 μm, Cr ₃ C ₂ powder, NbC powder, WC powder having an average particle diameter of 9 μm and an average particle A first raw material powder prepared at a ratio shown in Table 1 was prepared using a Co powder having a diameter of 2 μm, a binder was mixed, and granules of the first raw material powder were produced by a spray dryer. And sample no. For 1, 2, and 7, the compacts press-molded using these granules were fired by HIP treatment to produce TiB ₂ sintered bodies. Sample No. About 3-5, 8, the molded object of the laminated structure was produced by press molding using this granule and the following 2nd raw material powder.

The second raw material powder is a TiCN powder having an average particle diameter (d ₅₀ value) of 2 μm, a carbide powder of Table 1 having an average particle diameter of 2 μm, a Ni powder having an average particle diameter of 2 μm, and an average particle diameter as measured by the microtrack method. A 2 μm Co powder was used to prepare a second mixed raw material powder shown in Table 1, mixed with a binder, and spray-dried to produce.

  And using this raw material powder for molding, sample No. For 1, 2, and 7, the second raw material powder shown in Table 1 was put into the mold mold, leveled flat, the upper punch was lowered and temporarily formed by hand, then the upper punch was raised. Then, the first raw material powder is put on the temporarily formed powder or the first sintered body is placed, leveled as desired, and temporarily formed as desired. Further, the second raw material powder is put on the granulated powder and leveled, and finally the upper punch is lowered and pressed at 200 MPa to form a tool shape of CNMG120408HQ or CNMG120408PS (chip thickness 4.76 mm). Press molded.

Furthermore, this molded body was put into a firing furnace, (a) heated to 1200 ° C. at a heating rate of 10 ° C./min, (b) 0.5 ° C. in an atmosphere filled with 1000 Pa of nitrogen (N ₂ ). (C) The temperature was raised to 1400 ° C. at a temperature rising rate of 1 minute per minute, (c) the temperature was raised to the temperature shown in Table 1 at a temperature rising rate of 7 ° C./minute in a vacuum atmosphere, and maintained in that state for 1 hour. ) It baked on the baking conditions baked in the process cooled at the cooling rate of 10 degree-C / min. Table 2 shows the average unevenness height between the first sintered body and the second sintered body and the porosity of each sintered body.

Next, the cutting test was done on the following cutting conditions using the obtained cermet cutting tool. Moreover, the side surface (flank) shape of the cermet was traced using the metal microscope, and the bulge amount in the center part of the side surface was calculated. The results are shown in Table 2.
Wear evaluation work material: SCM435
Cutting speed: 250 m / min Feed: 0.20 mm / blade cutting: 1.0 mm
Cutting condition: wet (use water-soluble cutting fluid)
Evaluation method: Time until nose wear reaches 0.1 mm Thermal shock evaluation Workpiece: SCM435
Cutting speed: 300 m / min Feed: 0.30 mm /
Cutting depth: 2.0mm
Cutting condition: wet (use water-soluble cutting fluid)
Evaluation method: 20 mm / pass and the number of passes until loss

From Tables 1 and 2, sample Nos. That are not laminated structures of a TiB ₂ sintered body and a cermet sintered body. In Nos. 6 and 7, the heat dissipation was poor or the cutting edge hardness was poor, so that both thermal shock resistance and wear resistance could not be achieved, wear from chipping progressed, and defects due to thermal shock occurred early. Sample No. 1 in which a TiB ₂ sintered body was laminated on the upper and lower surfaces of the cermet sintered body. In No. 8, the chipping resistance was poor, and the progress of wear due to this was seen, and the thermal shock resistance was also bad.

On the other hand, sample No. 1 having a structure in which a cermet sintered body is laminated on the upper and lower surfaces of the TiB ₂ sintered body. Nos. 1 to 5 exhibited excellent wear resistance, good thermal shock resistance, and long tool life.

DESCRIPTION OF SYMBOLS 1 Cutting tool 2 1st sintered compact 3 2nd sintered compact 7 Cutting edge 8 Rake face 9 Relief face 10 Internal 14 Screw hole

Claims (2)

  It consists of a laminate in which a second sintered body made of a titanium carbonitride-based cermet is laminated on the upper and lower surfaces of a first sintered body made of a titanium diboride sintered body, and the cutting edge is attached to the second sintered body Cutting tool configured.   The cutting tool according to claim 1, wherein the thickness of the second sintered body is 10 to 35% with respect to the total thickness.