JP5676955B2 - Cutting tool and manufacturing method thereof - Google Patents

Description

  The present invention relates to a cutting tool made of a cermet sintered body and a method for manufacturing the cutting tool.

  At present, cermets such as diamond sintered bodies, ceramic sintered bodies, cemented carbides and Ti-based cermets are widely used as cutting tools. For example, in Patent Document 1, a ceramic sintered body, a cermet, a metal, and the like are arranged at the center, and a diamond sintered body is arranged concentrically on the outermost periphery and fired by an SHS / HIP process. A laminated structure sintered body in which a compressive stress is applied to the bonded body is described.

JP 09-011005 A

  However, in the structure in which different sintered bodies are concentrically laminated on the outer peripheral surface of the sintered body as in Patent Document 1, it is difficult to produce a compact shaped body, although the outermost layer has compressive stress. In particular, it was difficult to produce a complicated shape with a positive angle on the side surface. Moreover, in the concentric sintered body layer arrange | positioned on the outer side, the thickness variation became large, so that the thickness became thin, and the subject that a sintered compact could not be produced stably occurred.

  This invention is for solving the said problem, The objective is to provide the cutting tool which consists of a cermet sintered compact with the high fracture resistance in a cutting blade.

The cutting tool of the present invention has a flat plate shape in which a first cermet portion and a second cermet portion which is arranged on the surface of the first cermet portion and constitutes at least a cutting blade are laminated,
The first cermet part and the second cermet part are composed of one or more kinds of carbides, nitrides, carbonitrides and their solid solutions of Periodic Tables 4, 5, and 6 metals mainly composed of Ti. a hard phase consisting of one or more selected from, mainly is composed of a binder phase comprising an iron group metal, the second cermet part by the presence ratio is small Ikoto of the binder phase than the first cermet part The shrinkage of the second cermet part during firing is smaller than the shrinkage of the first cermet part, and the side face of the first cermet part is made of a cermet laminate in which the side face is recessed from the side face of the second cermet part.

  Here, the thickness of the second cermet part may be 10 to 50% with respect to the thickness of the entire cermet.

  Further, a diffusion layer having a thickness of 300 to 1500 μm may be present at the interface between the first cermet part and the second cermet part.

  Furthermore, the interface between the first cermet part and the second cermet part may be uneven.

Moreover, the manufacturing method of the cutting tool of this invention has the process of preparing two different types of mixed raw materials, and the upper surface, lower surface, or upper and lower surfaces of the 1st molded object part which consists of 1st raw material powder for 1st cermet parts. A step of producing a plate-shaped molded body in which the second molded body portion made of the second raw material powder for the second cermet portion is disposed and laminated, and firing the plate-shaped molded body to form the first cermet portion And a flat plate shape in which at least a second cermet part constituting a cutting edge is disposed on the surface of the first cermet part, and the first cermet part and the second cermet part are composed mainly of Ti. A hard phase composed of one or more carbides, nitrides, carbonitrides and solid solutions thereof selected from Group 4, 5, and 6 metals of the periodic table, and mainly iron group metals And a binder phase comprising Cermet part small, the abundance ratio of the binder phase than the first cermet part Ikoto, the second cermet part upon firing shrinkage is smaller than contraction of the first cermet part, of the first cermet part A step of producing a laminate having a side surface recessed from the side surface of the second cermet part.

  Here, the first molded body part is composed only of coarse granules having an average granule diameter of 150 to 210 μm, and the second molded body part is composed of coarse granules having an average granule diameter of 150 to 210 μm and an average granule diameter. It may be composed of mixed granules with fine granules of 40 to 60 μm.

  According to the cutting tool of the present invention, the second cermet portion has a smaller binder phase ratio than the first cermet portion, and the side surface of the first cermet portion is recessed from the side surface of the second cermet portion. Since it consists of a cermet laminate, the second cermet is subjected to compressive residual stress by firing, and the cutting edge existing on the surface of the second cermet also has compressive stress, so the fracture resistance at the cutting edge is high. Become.

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

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

  1 includes a first cermet 2 and a second cermet 3 that is disposed on the surface of the first cermet 2 and that forms at least a cutting edge 7. And the 1st cermet part 2 and the 2nd cermet part 3 were chosen from 1 or more types of the carbide | carbonized_material of 4th, 5th, and 6th metal of periodic table, nitride, carbonitride, and these solid solutions. The hard phase is composed of one or more hard phases (not shown) and a binder phase (not shown) mainly composed of an iron group metal, and the hard phase is a first hard phase mainly composed of TiCN, It consists of the 2nd hard phase of the composite carbonitride solid solution of at least 1 sort (s) of the periodic table 4th, 5th and 6th group metals and Ti.

  And the 2nd cermet part 3 becomes a structure with a smaller existence ratio of a binder phase than the 1st cermet part 2. FIG.

  With the above configuration, the cutting edge 7 is composed of the structure of the second cermet part 3 having high cutting performance, and the first cermet part 2 constituting the base applies compressive stress to the cutting edge located at the end of the second cermet 3. It is possible to improve the chipping resistance of the cutting tool 1. In addition, the screw hole 14 is formed in the center part of the rake face 8 of the cutting tool 1 of FIG.

In addition, the total content of the nitrides or carbonitrides of Periodic Table Group 4, 5 and 6 metals mainly composed of Ti which forms the hard phase contained in the cutting tool 1 is 80 to 90 in the whole cermet. On the other hand, the content ratio of the binder phase is preferably 10 to 20% by mass in the whole cermet, so that the balance of hardness and toughness of the cermet is excellent. And in the 1st cermet part 2, in order to give a compressive stress to the 2nd cermet part 3, the content rate of a hard phase is 75-85 mass%, and the content rate of a binder phase is 15-25 mass%. Is desirable. Moreover, in the 2nd cermet part 3, it is desirable that the content rate of a hard phase is 90-95 mass% and the content rate of a binder phase is 5-10 mass% from the point of maintenance of abrasion resistance. Furthermore, as a binder phase, it is desirable to contain 65 mass% or more of Co with respect to the total amount of the iron group metal in order to improve the thermal shock resistance of the cutting tool 1. In addition, in order to maintain the favorable sinterability of the cermet so that the burned skin surface of the cermet becomes a smooth surface, Ni is contained in an amount of 5 to 50% by mass, particularly 10 to 35% by mass as an iron group metal. It is desirable to make it contain.

  Here, the thickness of the second cermet part 3 is desirably 10 to 50% with respect to the thickness of the entire cermet. In addition, when the 2nd cermet part 3 exists in both the upper and lower layers with the same thickness, the thickness of one 2nd cermet part 3 will be 5-25% with respect to the thickness of the whole cermet.

  Further, the presence of the diffusion layer 6 having a thickness of 300 to 1500 μm at the interface between the first cermet part 2 and the second cermet part 3 improves the adhesion at the interface between the first cermet part 2 and the second cermet part 3. It is desirable in that it can.

Furthermore, it is desirable in that peeling at the interface can be suppressed by making the interface between the first cermet part 2 and the second cermet part 3 uneven.
(Production method)
Next, the manufacturing method of the cutting tool which consists of a cermet sintered compact mentioned above is demonstrated.

Two kinds of mixed raw material powders are prepared as raw materials.
First, the first raw material powder for the first cermet part has a composition that is sintered at a low temperature. Specifically, TiCN having an average particle size of 0.5 to 2.0 μm, preferably 0.5 to 1.2 μm. Any one of the powder, carbide powder, nitride powder, or carbonitride powder of other Group 4, 5, and 6 metals of the above-mentioned periodic table having an average particle diameter of 0.1 to 4 μm; A mixed powder in which at least one of Co powder of 0 to 1.5 μm and 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 are mixed. .

On the other hand, the second raw material powder for the second cermet part has a composition having a higher firing temperature than the first raw material powder, and has an average particle size of 0.5 to 2.0 μm, preferably 1.0 to 1.5 μm. TiCN powder, any one of carbide powders, nitride powders or carbonitride powders of other Group 4, 5, and 6 metals described above having an average particle diameter of 0.1 to 10 μm and an average particle diameter of 1 A mixed powder obtained by mixing at least one kind of Co powder of 0 to 1.5 μm and 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; To do.

  Here, the iron group metal content of the second raw material powder is less than the iron group metal content of the first raw material powder, or the average particle size of the primary raw material constituting the second raw material powder is It is desirable that it is larger than the average particle diameter of the first raw material powder.

  TiC powder and TiN powder may be added to the first and second raw material powders, but these raw material powders constitute TiCN in the cermet after firing.

  Further, the first molded body part is composed only of coarse granules having an average granule diameter of 90 to 150 μm, and the second molded body part is composed of coarse granules having an average granule diameter of 100 to 150 μm and an average granule diameter of 40 to 40 μm. It is desirable to be composed of mixed granules with fine granules of 60 μm in that the green density in the molded body to be described later can be made uniform and the vertical warpage of the laminated sintered body can be reduced.

Next, the two different kinds of mixed raw materials are used to form a flat cutting tool shape. As a molding method, the second raw material powder is placed on the upper surface, the lower surface, or the upper and lower surfaces in a press mold, and the first raw material powder is placed in the center and press-molded in a laminated state. Is preferred. In addition, there is a method of applying the slurry containing the first raw material powder to the surface of the compact that is press-molded using only the second raw material powder. In order to increase the density of the sintered body, the method of press molding in a state where both powders are laminated is suitable.

  As a method of arranging the second raw material powder on the upper / lower surface of the first raw material powder, after filling the first raw material powder and leveling it, the second raw material powder is charged, The raw material powder is introduced and the upper punch is lowered and temporarily formed at a low pressure. Thereafter, the upper punch is raised and the second raw material powder is introduced, and the upper punch is lowered again and temporarily formed. It is possible to preferably employ a method of molding at a predetermined pressure repeatedly and finally.

At this time, instead of filling the first raw material powder and leveling it flat, the surface of the first raw material powder filled with the substitute upper punch in which irregularities are engraved on the punch surface is temporarily pressed and the second raw material powder is charged. By doing so, in the sintered body, the interface between the first cermet part 2 and the second cermet part 3 can form an uneven shape. Thereafter, by firing the molded body, the second cermet part 3 has a larger dimension after firing shrinkage than the first cermet part 2, and thus the cermet having the predetermined structure described above can be produced.
As an example of specific firing conditions,
(A) The temperature is raised to 1050 to 1250 ° C.
(B) In an atmosphere filled with an inert gas such as nitrogen (N ₂ ) of 30 to 2000 Pa, the temperature is increased to 1300 to 1450 ° C. at a temperature increase rate of 0.1 to 2 ° C./min,
(C) While raising the temperature to 1520 to 1600 ° C. at a temperature increase rate of 3 to 15 ° C./min in a vacuum atmosphere, maintaining the vacuum atmosphere or an atmosphere filled with an inert gas for 0.5 to 2 hours, (D) Firing is performed at a cooling rate of 6 to 15 ° C./min.
If the firing temperature is lower than 1520 ° C., the first cermet part is not deformed and compressive stress cannot be applied to the surface of the cermet, and the fracture resistance on the surface of the cermet sintered body is lowered.

  Then, if desired, a coating layer is formed on the surface of the cermet. As a method for forming the coating layer, a physical vapor deposition (PVD) method such as an ion plating method or a sputtering method, or a chemical vapor deposition (CVD) method can be suitably applied.

TiCN powder having an average particle diameter (d ₅₀ value) shown in Table 1 as measured by the microtrack method, WC powder having an average particle diameter of 1.5 μm, TiN powder having an average particle diameter of 1.5 μm, TaC having an average particle diameter of 2.0 μm NbC powder with an average particle size of 1.1 μm, ZrC powder with an average particle size of 1.8 μm, VC powder with an average particle size of 1.6 μm, Ni powder with an average particle size of 2.4 μm, and an average particle size of 1.2 μm Using a Co powder, the first raw material powder prepared in the ratio shown in Table 1 was wet mixed using isopropyl alcohol (IPA) using a stainless steel ball mill and cemented carbide ball, and 3% by mass of paraffin was added. After mixing, the mixture was granulated with a spray dryer.

  Similarly, the 2nd raw material powder shown in Table 1 was prepared using the said raw material powder, the binder was mixed, and the granule of the 2nd raw material powder was produced with the spray dryer. Sample No. 1-3, the first raw material powder granules are divided into 7 stages by mesh sieve and only the coarse granules of 150 μm to 210 μm are used, and the second raw material powder granules are 7 stages by mesh sieve. In this case, a mixed powder prepared by mixing the coarsest granules of 150 μm to 210 μm, the second coarsest and the finest granules of 40 μm to 60 μm, the second finest was used.

Then, using this raw material powder for molding, the second raw material powder is poured into the mold mold, leveled flat, the upper punch is lowered and temporarily formed by hand, and then the upper punch is raised. The first raw material powder is put on the temporarily formed powder and leveled flatly, the temporary forming is performed in the same manner as described above, and the second raw material powder is put on the granulated powder. It was leveled flat, and finally the upper punch was lowered and pressed at 200 MPa to press-mold into a tool shape of CNMA1204012 (chip thickness 4.76 mm).

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.

次に、金属顕微鏡を用いてサーメットの側面（逃げ面）形状をトレースし、側面の中央部における凹み量（図１（ｂ）のｗ）を算出した。また、焼結体の走査型電子顕微鏡観察を行い、各サーメットの組織観察を行うとともに、エネルギー分散分光分析にて第１サーメット部と第２サーメット部の界面における各金属元素の分布を分析して、第２サーメット部の厚み、および拡散層の厚みを確認した。結果は表２に示した。

Next, the shape of the side surface (flank) of the cermet was traced using a metal microscope, and the amount of depression (w in FIG. 1B) at the center of the side surface was calculated. Also, the sintered body is observed with a scanning electron microscope to observe the structure of each cermet, and the distribution of each metal element at the interface between the first cermet part and the second cermet part is analyzed by energy dispersion spectroscopy. The thickness of the second cermet part and the thickness of the diffusion layer were confirmed. The results are shown in Table 2.

また、得られたサーメット製の切削工具を用いて以下の切削条件にて切削試験を行った。結果は表３に示した。
（耐摩耗性評価）
被削材：ＦＣ２５０
切削速度：３５０ｍ／分
送り：０．２０ｍｍ／ｒｅｖ
切込み：１．０ｍｍ
切削状態：湿式（水溶性切削液使用）
評価方法：摩耗量が０．２ｍｍに達するまでの時間
（耐欠損性評価）
被削材：Ｓ４５Ｃ
切削速度：１００ｍ／分
送り：０．０５〜０．５０ｍｍ／ｒｅｖ
切込み：２．０ｍｍ
切削状態：乾式
評価方法：各送り１０秒で欠損するまでの時間（秒）

Moreover, the cutting test was done on the following cutting conditions using the obtained cermet cutting tool. The results are shown in Table 3.
(Abrasion resistance evaluation)
Work material: FC250
Cutting speed: 350 m / min Feed: 0.20 mm / rev
Cutting depth: 1.0mm
Cutting condition: wet (use water-soluble cutting fluid)
Evaluation method: Time until the wear amount reaches 0.2 mm (defect resistance evaluation)
Work material: S45C
Cutting speed: 100 m / min Feed: 0.05 to 0.50 mm / rev
Cutting depth: 2.0mm
Cutting state: Dry evaluation method: Time until chipping in 10 seconds for each feed (seconds)

表１〜３より、全体が均一な組成からなる試料Ｎｏ．６は、切刃の耐欠損性が低くて早期に欠損した。また、第１サーメット部の上下面に第２サーメット部を積層した構成からなるが、第１サーメット部の側面が膨らんだ試料Ｎｏ．５では、工具本体への装着にがたつきが発生し、切削評価においても早期に欠損した。

From Tables 1 to 3, the sample No. 1 composed entirely of a uniform composition. No. 6 was deficient early because the cutting edge had low fracture resistance. In addition, although the second cermet portion is laminated on the upper and lower surfaces of the first cermet portion, the side surface of the first cermet portion is expanded. In No. 5, rattling occurred on the tool body and it was lost early in the cutting evaluation.

  On the other hand, sample no. Nos. 1 to 4 exhibited excellent wear resistance, good fracture resistance, and long tool life.

DESCRIPTION OF SYMBOLS 1 Cutting tool 2 1st cermet part 3 2nd cermet part 6 Diffusion layer 7 Cutting edge 8 Rake face 9 Relief face 14 Screw hole

Claims (6)

The first cermet portion and the second cermet portion that is disposed on the surface of the first cermet portion and constitutes at least the cutting edge are laminated in a flat plate shape,
The first cermet part and the second cermet part are composed of one or more kinds of carbides, nitrides, carbonitrides and their solid solutions of Periodic Tables 4, 5, and 6 metals mainly composed of Ti. a hard phase consisting of one or more selected from, mainly is composed of a binder phase comprising an iron group metal, the second cermet part by the presence ratio is small Ikoto of the binder phase than the first cermet part A cutting tool comprising a cermet laminate in which the shrinkage of the second cermet portion is smaller than the shrinkage of the first cermet portion during firing, and the side surface of the first cermet portion is recessed from the side surface of the second cermet portion. .   The cutting tool according to claim 1, wherein the thickness of the second cermet part is 10 to 50% with respect to the thickness of the entire cermet.   The cutting tool according to claim 1, wherein a diffusion layer having a thickness of 300 to 1500 μm is present at an interface between the first cermet part and the second cermet part.   The cutting tool according to any one of claims 1 to 3, wherein an interface between the first cermet part and the second cermet part is uneven. A step of preparing two different mixed raw materials, and a second raw material for the second cermet portion on the upper surface, the lower surface, or the upper and lower surfaces of the first molded body portion made of the first raw material powder for the first cermet portion A step of producing a laminated plate-like molded body in which the second molded body portion made of powder is arranged and laminated, and firing the plate-like molded body,
The first cermet portion and the second cermet portion that is disposed on the surface of the first cermet portion and constitutes at least the cutting edge are laminated in a flat plate shape,
The first cermet part and the second cermet part are composed of one or more kinds of carbides, nitrides, carbonitrides and their solid solutions of Periodic Tables 4, 5, and 6 metals mainly composed of Ti. a hard phase consisting of one or more selected from, mainly is composed of a binder phase comprising an iron group metal, the second cermet part by the presence ratio is small Ikoto of the binder phase than the first cermet part And a step of producing a laminate in which the shrinkage of the second cermet part is smaller than the shrinkage of the first cermet part and the side surface of the first cermet part is recessed from the side face of the second cermet part during firing. A manufacturing method of a cutting tool provided.   The first molded body part is composed only of coarse granules having an average granule diameter of 150 to 210 μm, and the second molded body part is composed of coarse granules having an average granule diameter of 150 to 210 μm and an average granule diameter of 40 to 60 μm. The manufacturing method of the cutting tool of Claim 5 comprised by a mixed granule with a fine granule.

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