JP5185032B2

JP5185032B2 - Cutting tools

Info

Publication number: JP5185032B2
Application number: JP2008234053A
Authority: JP
Inventors: 友幸石田; 秀樹森口; 明彦池ヶ谷
Original assignee: Sumitomo Electric Hardmetal Corp; Sumitomo Electric Industries Ltd
Current assignee: Sumitomo Electric Hardmetal Corp; Sumitomo Electric Industries Ltd
Priority date: 2007-09-14
Filing date: 2008-09-11
Publication date: 2013-04-17
Anticipated expiration: 2028-09-11
Also published as: JP2009083096A

Description

本発明は、超硬合金層及びサーメット層の双方を具えた切削工具に関する。特に、耐衝撃性に優れると共に、良好な仕上げ面光沢が得られる切削工具に関するものである。 The present invention relates to a cutting tool having both a cemented carbide layer and a cermet layer. In particular, the present invention relates to a cutting tool that is excellent in impact resistance and obtains a good finished surface gloss.

従来、切削工具の基材材料に、WC(炭化タングステン)やTiCN(炭窒化チタン)といったTi化合物などのセラミックス粒子(硬質相)をCoやNiといった鉄族金属(結合相)で結合した超硬合金やサーメットが利用されている。 Conventionally, cemented carbide in which ceramic particles (hard phase) such as Ti compounds such as WC (tungsten carbide) and TiCN (titanium carbonitride) are bonded to the base material of a cutting tool with an iron group metal (binding phase) such as Co or Ni. Alloys and cermets are used.

一般に、サーメットは、TiCNなどのTi化合物を主たる硬質相とすることから高硬度であるものの、WCを主たる硬質相とする超硬合金よりも靭性が低いとされる。そのため、サーメットからなる基材を具える切削工具は、適用範囲が狭く、主に低負荷の仕上げ加工に利用される。これに対し、特許文献1では、サーメット中のW濃度を調整することで、耐欠損性を向上することを開示している。また、特許文献2,3では、サーメットと超硬合金とを積層して接合した複合材料を提案している。特許文献2には、超硬合金とサーメットとを別個に作製し、両者の接合面を研削して面粗さを小さくしてから積層したものを加熱して一体化した接合材が開示されている。特許文献3には、別個に作製した焼結体を重ねて通電加熱法により接合したり、別個に作製したプレス成形体を重ねて焼結した超硬合金部材が開示されている。 In general, cermet has a high hardness because a Ti compound such as TiCN is mainly used as a hard phase, but is considered to have lower toughness than a cemented carbide containing WC as a main hard phase. Therefore, a cutting tool having a base material made of cermet has a narrow application range and is mainly used for low-load finishing. In contrast, Patent Document 1 discloses that the fracture resistance is improved by adjusting the W concentration in the cermet. Patent Documents 2 and 3 propose composite materials in which cermet and cemented carbide are laminated and joined. Patent Document 2 discloses a bonding material in which a cemented carbide and a cermet are separately manufactured, and the bonded surfaces of both are ground and the surface roughness is reduced, and then the laminated material is heated and integrated. Yes. Patent Document 3 discloses a cemented carbide member obtained by stacking separately manufactured sintered bodies and joining them by an electric heating method, or by stacking separately manufactured press-formed bodies and sintering them.

特開2005-272877号公報JP 2005-272877 特開平6-240308号公報JP-A-6-240308 特開平7-207398号公報Japanese Unexamined Patent Publication No. 7-207398

特許文献1に記載されるW濃度の調整による靭性の向上には限界があり、大きな性能の向上は難しい。一方、特許文献2,3に記載される接合材を切削に用いた場合、靭性に優れる超硬合金を具えることで、耐衝撃性を高められる。しかし、これらの接合材は、超硬合金の割合が高く、例えば、超硬合金とサーメットとが半々である接合材を切削工具に用いると、切刃がサーメットのみ或いは超硬合金のみとなる。超硬合金は、サーメットと比較して鋼と反応性し易い。そのため、ワーク(被削材)との接触面に占める超硬合金の割合が高いと、特に鋼の切削において、サーメットの利点である良好な仕上げ面光沢を得ることが難しい。 There is a limit to the improvement of toughness by adjusting the W concentration described in Patent Document 1, and it is difficult to greatly improve the performance. On the other hand, when the bonding materials described in Patent Documents 2 and 3 are used for cutting, impact resistance can be improved by providing a cemented carbide having excellent toughness. However, these bonding materials have a high ratio of cemented carbide. For example, when a bonding material in which a cemented carbide alloy and a cermet are halved is used for a cutting tool, the cutting edge is only cermet or only cemented carbide. Cemented carbide is more reactive with steel than cermet. Therefore, if the ratio of the cemented carbide in the contact surface with the workpiece (work material) is high, it is difficult to obtain a good finished surface gloss, which is an advantage of cermet, particularly in steel cutting.

そこで、本発明の目的の一つは、耐衝撃性に優れると共に、良好な仕上げ面光沢が得られる切削工具を提供することにある。 Then, one of the objectives of this invention is providing the cutting tool which is excellent in impact resistance and can obtain favorable finished surface gloss.

本発明は、サーメット層上に薄い超硬合金層を具えることで上記目的を達成する。具体的には、本発明切削工具は、少なくとも一層の超硬合金層と少なくとも一層のサーメット層とが積層されてなる基材を具え、基材の表面側の少なくとも一部に、特に、切刃及び切刃に繋がるすくい面側の少なくとも一部に超硬合金層が配置されている。この基材の積層方向における厚さが最も大きい部分の厚さをh1、切刃部分に存在する上記超硬合金層の積層方向における厚さが最も大きい部分の厚さをh2とするとき、h2/h1が0.002以上0.02以下を満たす。上記「切刃部分」とは、基材の切刃及びその近傍の領域であって、逃げ面からすくい面方向に1000μmまでの領域とする。 The present invention achieves the above object by providing a thin cemented carbide layer on the cermet layer. Specifically, the cutting tool of the present invention comprises a base material in which at least one cemented carbide layer and at least one cermet layer are laminated, and at least part of the surface side of the base material, in particular, a cutting blade. And the cemented carbide layer is arrange | positioned in at least one part of the rake face side connected to a cutting blade. When the thickness of the portion with the largest thickness in the laminating direction of this substrate is h1, and the thickness of the portion with the largest thickness in the laminating direction of the cemented carbide layer present in the cutting edge portion is h2, h2 / h1 satisfies 0.002 or more and 0.02 or less. The above-mentioned “cutting edge portion” refers to a cutting edge of the base material and a region in the vicinity thereof, and is a region from the flank face to the rake face direction up to 1000 μm.

本発明切削工具は、ワークや切屑などと接触する切刃及びすくい面の一部において、サーメット層上に、サーメット層よりも靭性に優れる超硬合金層を具えることで、切屑などとの接触による衝撃を受けても欠損などが生じ難く、耐衝撃性を向上することができ、靭性に優れる。そのため、サーメット工具では欠けなどが生じて適用が困難であった分野にも本発明工具を利用できる。また、本発明工具は、特に、全体厚さに対して切刃部分に具える超硬合金層を薄くしていることで、積層面(積層状態が見える面)におけるサーメットの割合を高められる。従って、この積層面がワークと接触するように本発明工具を用いることで、サーメットと同程度の仕上げ面光沢が得られる。このように本発明工具は、高靭性でありながら、良好な仕上げ面光沢を得ることができる。以下、本発明を詳細に説明する。 The cutting tool of the present invention is provided with a cemented carbide layer that is tougher than the cermet layer on the cermet layer at a part of the cutting blade and the rake face that comes into contact with the workpiece, chips, etc. Even when subjected to an impact due to, it is difficult for defects to occur, the impact resistance can be improved, and the toughness is excellent. Therefore, the tool of the present invention can also be used in fields where application is difficult due to chipping or the like with a cermet tool. Further, in the tool of the present invention, the ratio of the cermet on the laminated surface (the surface where the laminated state can be seen) can be increased particularly by making the cemented carbide layer provided in the cutting edge portion thinner than the entire thickness. Therefore, by using the tool of the present invention so that the laminated surface is in contact with the workpiece, a finished surface gloss equivalent to that of cermet can be obtained. As described above, the tool of the present invention can obtain good finished surface gloss while having high toughness. Hereinafter, the present invention will be described in detail.

〔切削工具〕
＜積層構造＞
本発明工具は、超硬合金層とサーメット層とが積層されて一体化された積層体(複合材料)で構成される基材を具える。本発明工具は、この基材そのもの、或いは後述するように更に、被覆膜を具えていてもよい。この基材の表面側の少なくとも一部、特に、切刃と、切刃に繋がるすくい面の少なくとも一部とには、超硬合金層を具える。すくい面の全面が実質的に超硬合金層により形成されていてもよい。本発明工具は、一般にサーメットよりも靭性の高い超硬合金層を、切屑が接触し易いすくい面側に具えることで、サーメット工具と比較して耐衝撃性に優れ、切屑との接触による欠損を効果的に抑制できる。特に、切刃部分に超硬合金層を具えることで耐欠損性を向上できる。本発明工具は、部分的に積層構造でもよいが、全体が積層構造であると、製造性がよい。具体的な形態は、一つのサーメット層と一つの超硬合金層とが積層された二層構造、一つのサーメット層を内部層とし、内部層の両側を挟むように一対の超硬合金層を配置した三層構造、一つのサーメット層を内部層とし、その外表面全面を覆うように超硬合金層を配置した内包構造(断面二層)、一つのサーメット層を中心層とし、その外表面の一部を囲むように超硬合金層を配置して、サーメット層の一部を露出させた同心状構造(断面二層)などが挙げられる。内包構造や同心状構造の成形体は、例えば、同心状の金型、具体的には、柱状の内側金型と、内側金型の外周に配される枠状の外側金型と、外側金型の外周に配される枠状の金型本体とを具えるものを用いることで形成可能である。内包構造や同心状構造の場合、ワークに接触する部分は、サーメット層が露出するようにする。上記二層構造や三層構造は、ワークに接触する部分にサーメット層を存在させ易く、好ましい。なお、切刃とは、すくい面と逃げ面との交線(稜線)を言う。〔Cutting tools〕
<Laminated structure>
The tool of the present invention includes a base material composed of a laminate (composite material) in which a cemented carbide layer and a cermet layer are laminated and integrated. The tool of the present invention may further include a coating film as described later, or as will be described later. A cemented carbide layer is provided on at least a part of the surface side of the base material, in particular, the cutting edge and at least a part of the rake face connected to the cutting edge. The entire rake face may be substantially formed of a cemented carbide layer. The tool of the present invention is generally superior in impact resistance compared to a cermet tool by providing a cemented carbide layer with higher toughness than cermet on the rake face side where chips are easy to contact. Can be effectively suppressed. In particular, the chipping resistance can be improved by providing a cemented carbide layer on the cutting edge. The tool of the present invention may have a partially laminated structure, but if the whole has a laminated structure, the productivity is good. The specific form is a two-layer structure in which one cermet layer and one cemented carbide layer are laminated, one cermet layer as an inner layer, and a pair of cemented carbide layers sandwiching both sides of the inner layer. Three-layer structure, an inner structure with one cermet layer as the inner layer, and an internal structure (two cross-sections) with a cemented carbide layer covering the entire outer surface, one outer surface with one cermet layer as the central layer And a concentric structure (two-layer cross section) in which a cemented carbide layer is disposed so as to surround a part of the cermet layer and a part of the cermet layer is exposed. The molded body of the inner structure or the concentric structure is, for example, a concentric mold, specifically, a columnar inner mold, a frame-shaped outer mold disposed on the outer periphery of the inner mold, and an outer mold. It can be formed by using one having a frame-shaped mold body arranged on the outer periphery of the mold. In the case of an internal structure or a concentric structure, the cermet layer is exposed at the portion that contacts the workpiece. The two-layer structure or the three-layer structure is preferable because a cermet layer is easily present in a portion in contact with the workpiece. The cutting edge refers to an intersection line (ridge line) between the rake face and the flank face.

＜接合方法＞
上記超硬合金層とサーメット層とは、各層を構成する原料粉末を混合後、造粒装置などにより造粒粉末とし、この造粒粉末を金型に順に供給して積層させ、この状態で加圧して積層プレス成形体を作製し、この成形体を焼結することで、一体に接合する。即ち、従来のように焼結体やプレス成形体を積層するのではなく、成形前の原料粉末の段階で積層状態として本発明工具を製造する。特許文献2,3に開示される製造方法は、焼結体を一旦製造してから表面研削を行った後加熱接合したり、別々にプレス成形体や焼結体を製造して接合するため、工程が多い。また、特に、本発明工具における超硬合金層のような薄いプレス成形体や焼結体を作製して、成形体同士、焼結体同士を隙間無く密着させることは難しいと考えられる。そのため、特許文献2,3に開示される接合材は、表面研削を行ったり、金型成形を経ることで、超硬合金とサーメットとの境界(接合界面)を平坦にしていると考えられるが、このような形状では、両者の熱膨張係数といった特性の差などによる剥離が生じ易い。両者が剥離すると、超硬合金の特性及びサーメットの特性の双方を十分に活用できない。なお、焼結体同士間や成形体同士間に隙間が存在するとその隙間に結合相プールが生じ易いことから、上記結合相プールを防止するために、上記従来の技術では、接合面を平坦化していると考えられる。これに対し、本発明工具は、通常の超硬合金やサーメットの製造プロセスに対して一つの金型における給粉回数を増加することで製造できるため、通常行われている粉末冶金の一連の製法から大きく逸脱することなく、簡単に生産性よく製造することができる。また、本発明工具の製造にあたり、プレス工程以外のプロセスコストの増加もほとんどなく、経済的にも好ましい。更に、原料粉末を積層させた成形体を焼結することで、両層が剥離し難く、接合性に優れる複合材料(基材)が得られる。 <Join method>
The cemented carbide layer and the cermet layer are prepared by mixing the raw material powders constituting each layer, and then using a granulator or the like to form granulated powder. The granulated powder is sequentially supplied to a mold and laminated, and added in this state. A laminated press-molded body is produced by pressing, and the molded body is sintered to be integrally joined. That is, rather than laminating a sintered body or a press-molded body as in the prior art, the tool of the present invention is produced in a laminated state at the raw material powder stage before molding. The manufacturing methods disclosed in Patent Documents 2 and 3 are manufactured by joining the surface after grinding the surface after manufacturing the sintered body, or by separately manufacturing the press-molded body and the sintered body. There are many processes. In particular, it is considered difficult to produce a thin press-molded body or sintered body such as a cemented carbide layer in the tool of the present invention, and to adhere the molded bodies and the sintered bodies together without any gaps. Therefore, the bonding materials disclosed in Patent Documents 2 and 3 are thought to flatten the boundary (bonding interface) between the cemented carbide and the cermet by performing surface grinding or die molding. In such a shape, peeling due to a difference in characteristics such as a thermal expansion coefficient between the two tends to occur. When both are separated, both the characteristics of the cemented carbide and the characteristics of the cermet cannot be fully utilized. In addition, if there is a gap between the sintered bodies or between the molded bodies, a binder phase pool is likely to be generated in the gap. Therefore, in order to prevent the binder phase pool, the conventional technique flattens the bonding surface. It is thought that. On the other hand, since the tool of the present invention can be manufactured by increasing the number of times of powder feeding in one mold with respect to the manufacturing process of a normal cemented carbide or cermet, a series of processes commonly used for powder metallurgy Therefore, it can be easily manufactured with high productivity without greatly deviating from the above. Further, in manufacturing the tool of the present invention, there is almost no increase in process costs other than the pressing step, which is economically preferable. Furthermore, by sintering the molded body in which the raw material powders are laminated, a composite material (base material) that is difficult to peel off both layers and has excellent bondability can be obtained.

＜境界の形状＞
本発明工具は、上述のように原料粉末(造粒粉末)を積層させて成形した後、焼結することで、超硬合金層とサーメット層との境界(接合界面)に、原料粉末に起因すると考えられる微小な凹凸が生じる。この凹凸により両層が互いに係合することで剥離し難いと考えられる。また、本発明工具は、超硬合金層が薄いため、超硬合金層の形状がパンチの形状に倣い易い(転写され易い)。従って、押圧面にチップブレーカー用突起や溝といった凹凸を有する凹凸付きパンチを用いると、境界がパンチに沿って凹凸を有することで両層をより係合し易くして、両層の接合性が高められると考えられる。 <Boundary shape>
The present invention tool is formed by laminating the raw material powder (granulated powder) as described above, and then sintering, resulting in the boundary between the cemented carbide layer and the cermet layer (bonding interface) due to the raw material powder. As a result, microscopic irregularities appear. It is thought that it is hard to peel off because both layers engage with each other by this unevenness. Further, since the tool of the present invention has a thin cemented carbide layer, the shape of the cemented carbide layer easily follows the shape of the punch (is easily transferred). Therefore, when a punch with unevenness such as a chip breaker protrusion or groove is used on the pressing surface, the boundary has unevenness along the punch, making it easier to engage both layers, and the bonding properties of both layers It is thought that it is raised.

＜超硬合金層の厚さ＞
本発明工具は、超硬合金層が薄く、サーメット層の体積割合が多い(50％超である)ことを最大の特徴とする。具体的には、本発明工具の両層の積層方向における厚さが最も大きい部分の厚さをh1、切刃部分に存在する超硬合金層の積層方向における厚さが最も大きい部分の厚さをh2とするとき、h2/h1が0.002以上0.02以下を満たす。特に、h2/h1は、0.002以上0.01以下を満たすことが好ましい。切刃部分に存在する超硬合金層が薄いことで、切刃及びその近傍においてワークとの接触面に占めるサーメット層の割合が高くなるため、本発明工具は、鋼の切削であっても、サーメット工具と同等程度の仕上げ面光沢を得ることができる。また、工具表面に存在する超硬合金層は、超硬合金とサーメットとの熱膨張係数の差に基づく圧縮応力が存在するが、超硬合金層の厚さが薄いことで、この圧縮応力が大きくなる傾向にある。ある程度の圧縮応力は、耐欠損性の向上に寄与すると期待される。本発明工具はこのように靭性や耐欠損性に優れることで、耐欠損性や靭性が低かった従来のサーメット工具よりも適用範囲が広がり、例えば、従来、超硬合金工具を使用していた分野にもサーメット層を主体とする本発明工具を使用可能である。このような本発明工具を利用することで、供給リスクが生じている希少金属(クラーク数:0.006)であるWの使用量を低減し、性能の劣化が生じない範囲で、クラーク数:0.46のTiの化合物を主成分とするサーメット層を多くすることにより、省資源化に寄与することができる。Wは、近年価格が高騰しているため、その使用量の低減は、経済的にも好ましい。 <Cemented carbide layer thickness>
The tool of the present invention is characterized in that the cemented carbide layer is thin and the volume ratio of the cermet layer is large (greater than 50%). Specifically, the thickness of the thickest portion in the stacking direction of both layers of the tool of the present invention is h1, and the thickness of the thickest portion in the stacking direction of the cemented carbide layer present in the cutting edge portion When h2 is h2, h2 / h1 satisfies 0.002 or more and 0.02 or less. In particular, h2 / h1 preferably satisfies 0.002 or more and 0.01 or less. Since the cemented carbide layer present in the cutting edge portion is thin, the cutting blade and the ratio of the cermet layer in the contact surface with the workpiece in the vicinity thereof increase, so that the tool of the present invention is steel cutting, Finished surface gloss equivalent to that of a cermet tool can be obtained. In addition, the cemented carbide layer on the tool surface has a compressive stress based on the difference in thermal expansion coefficient between the cemented carbide and the cermet, but this compressive stress is reduced because the thickness of the cemented carbide layer is thin. It tends to grow. A certain amount of compressive stress is expected to contribute to the improvement of fracture resistance. The tool of the present invention is excellent in toughness and fracture resistance as described above, and thus has a wider range of application than conventional cermet tools having low fracture resistance and toughness. In addition, the tool of the present invention mainly composed of a cermet layer can be used. By using such a tool of the present invention, the use amount of W, which is a rare metal (clerk number: 0.006), in which supply risk occurs is reduced, and within a range where performance degradation does not occur, the number of clarks: 0.46. Increasing the number of cermet layers mainly composed of Ti compounds can contribute to resource saving. Since the price of W has soared in recent years, it is economically preferable to reduce the amount of W used.

h1,h2の測定は、例えば、切削工具の断面の顕微鏡観察像を用いて行う。図1は、工具及び超硬合金層の厚さ、刃先処理量の測定方法を説明する模式断面説明図であり、(I)は、二層構造の工具、(II)は三層構造の工具を示し、(III)は、切刃部分の拡大図である。図1では、多角柱状の切削工具(チップ)を示し、(I)では上面、(II)では上下面がすくい面に相当し、突起の一部及び凹みの一部はチップブレーカーを構成する。また、図1では、超硬合金層、境界の凹凸、チップブレーカー、切刃部分を強調して示す(後述する図2も同様)。図1(I)に示すように超硬合金層101とサーメット層102との積層方向が基準面Sに直交するように切削工具(基材)100を配置し、この状態で超硬合金層101とサーメット層102との境界103が存在する全域に亘って、基準面Sから超硬合金層100の表面101fまでの長さl_fを測定し、長さl_fを切削工具100の積層方向における厚さTとする。図1(II)に示すように切削工具100が基準面Sに接触していない箇所がある場合、接触していない箇所は、基準面Sから、切削工具100の外表面のうち基準面Sに対向する面までの長さl_fuを測定し、同位置における長さl_fとl_fuとの差:l_f-l_fuを厚さTとする。そして、厚さTの最大値T_maxをh1とする。また、上記配置状態で境界103の全域に亘って、基準面Sから境界までの長さl、及び同位置における長さl_fを測定し、その差:l_f-lを超硬合金層101の積層方向における厚さtとする。そして、切刃部分100c(図1(I),(II)において角部近傍(逃げ面からすくい面方向に1000μmまでの領域))の厚さtの最大値t_maxをh2とする。図1(III)に示すように切刃部分にホーニングといった刃先処理を行っている場合、切刃部分100cは、刃先処理が施された範囲(逃げ面201とすくい面202とを結ぶ稜線200において、逃げ面201から稜線200とすくい面202との交点203までの範囲(刃先処理幅w))を含む。図1(I)に示すように切削工具100の一面全面が基準面Sに接している場合、h1は、超硬合金層101の表面101fをハイトゲージといった測定機器で測定して求めてもよい。 The measurement of h1 and h2 is performed using, for example, a microscope observation image of the cross section of the cutting tool. FIG. 1 is a schematic cross-sectional explanatory diagram for explaining a method for measuring the thickness of a tool and a cemented carbide layer and the cutting edge throughput, (I) is a two-layer tool, and (II) is a three-layer tool. (III) is an enlarged view of the cutting edge portion. FIG. 1 shows a polygonal column-shaped cutting tool (chip). In (I), the upper surface corresponds to a rake surface, and in (II), the upper and lower surfaces correspond to a rake surface, and a part of the protrusion and a part of the recess constitute a chip breaker. Further, in FIG. 1, the cemented carbide layer, the unevenness of the boundary, the chip breaker, and the cutting edge portion are highlighted (the same applies to FIG. 2 described later). As shown in FIG. 1 (I), the cutting tool (base material) 100 is arranged so that the lamination direction of the cemented carbide layer 101 and the cermet layer 102 is orthogonal to the reference plane S, and in this state the cemented carbide layer 101 a boundary 103 between the cermet layer 102 over the entire existing measures the length l _f to the surface 101f of the cemented carbide layer 100 from the reference plane S, in the stacking direction of the cutting tool 100 the length l _f The thickness is T. As shown in FIG. 1 (II), when there is a part where the cutting tool 100 is not in contact with the reference surface S, the part that is not in contact is from the reference surface S to the reference surface S of the outer surface of the cutting tool 100. The length l _fu to the opposite surface is measured, and the difference between the lengths l _f and l _fu at the same position: l _f −l _fu is the thickness T. The maximum value T _max of the thickness T is set to h1. Further, the length l from the reference plane S to the boundary and the length l _f at the same position are measured over the entire area of the boundary 103 in the above-described arrangement state, and the difference: l _f −l is determined as the cemented carbide layer 101. The thickness t in the stacking direction of The maximum value t _max of the thickness t near the cutting edge portion 100c (in the vicinity of the corner in FIGS. 1 (I) and 1 (II) (the region from the flank face to the rake face direction of 1000 μm)) is set to h2. When cutting edge processing such as honing is performed on the cutting edge portion as shown in FIG. 1 (III), the cutting edge portion 100c is within the range where the cutting edge processing has been performed (the ridgeline 200 connecting the flank 201 and the rake face 202). , Including the range from the flank 201 to the intersection 203 of the ridgeline 200 and the rake face 202 (blade edge processing width w)). If the entire surface of the cutting tool 100 is in contact with the reference plane S as shown in FIG. 1 (I), h1 may be obtained by measuring the surface 101f of the cemented carbide layer 101 with a measuring instrument such as a height gauge.

超硬合金層の厚さh2の具体的な値としては、10μm以上100μm以下、更に10μm以上50μmが好ましい。10μm未満であると、高靭性層の役割を果たせず、切削時に欠損などが生じ易く、100μm超であると、ワークとの接触面に占める超硬合金層の割合が大きくなり、特に鋼を切削する際、良好な仕上げ面光沢が得られ難くなる。特に、50μm以下とすると、超硬合金層に存在する圧縮応力が大きくなり、靭性の向上効果がより大きくなると考えられる。 The specific value of the thickness h2 of the cemented carbide layer is preferably 10 μm or more and 100 μm or less, more preferably 10 μm or more and 50 μm. If it is less than 10μm, it does not play the role of a tough layer and is likely to be damaged during cutting, and if it exceeds 100μm, the proportion of the cemented carbide layer in the contact surface with the workpiece increases, especially when cutting steel. In this case, it is difficult to obtain a good finished surface gloss. In particular, when the thickness is 50 μm or less, it is considered that the compressive stress existing in the cemented carbide layer is increased, and the effect of improving toughness is further increased.

超硬合金層の厚さは、切刃部分全体に亘って均一的にしてもよいし、基材全体に亘って均一的にしてもよい。例えば、すくい面全域に亘って均一的な厚さとしてもよい。また、超硬合金層の厚さに差をつけた構成、即ち、部分的に厚さを異ならせてもよい。例えば、すくい面の特定箇所に存在する超硬合金層の厚さを厚くしたり薄くしたりしてもよい。特に、本発明工具を多角柱状の刃先交換型チップとし、その角部に切刃が形成され、この切刃に繋がるすくい面にチップブレーカーを具えており、このブレーカー部分にも超硬合金層を具える場合、ブレーカー部分に存在する超硬合金層を切刃部分よりも厚くすることが好ましい。チップブレーカーは、切屑の接触による衝撃が加わり易い。そこで、靭性に優れる超硬合金層を上記ブレーカー部分に厚く具えることで耐衝撃性を高められると共に、相対的に切刃部分の超硬合金層を薄くすることで、切刃及びその近傍においてワークに接触する逃げ面側のサーメット層の割合が高められるため、良好な仕上げ面光沢をより顕著に得られる。具体的には、チップブレーカーにおいてすくい面から最も突出した部分の超硬合金層の厚さをhb(図1(II)参照)とするとき、h2/hbが0.5以上1以下であることが好ましい。0.5未満では、超硬合金層の厚さの差が大きくなり過ぎて変形が生じ易くなり、1.0超では、上記耐衝撃性の向上及び良好な仕上げ面光沢の維持効果の双方を十分に得難い。 The thickness of the cemented carbide layer may be uniform over the entire cutting edge portion or may be uniform over the entire substrate. For example, the thickness may be uniform over the entire rake face. Also, the thickness of the cemented carbide layer may be different, that is, the thickness may be partially different. For example, the thickness of the cemented carbide layer present at a specific location on the rake face may be increased or decreased. In particular, the tool of the present invention is a polygonal-blade blade-tip-exchangeable tip, a cutting edge is formed at the corner, and a chip breaker is provided on a rake face connected to the cutting blade, and a cemented carbide layer is also provided on the breaker portion. When it is provided, it is preferable to make the cemented carbide layer present in the breaker part thicker than the cutting edge part. The chip breaker is easily subjected to an impact due to chip contact. Therefore, by providing a thicker cemented carbide layer with excellent toughness to the above-mentioned breaker part, impact resistance can be improved, and by relatively thinning the cemented carbide layer of the cutting edge part, the cutting edge and its vicinity Since the ratio of the cermet layer on the flank side in contact with the workpiece is increased, a good finished surface gloss can be obtained more remarkably. Specifically, when the thickness of the cemented carbide layer that protrudes most from the rake face in the chip breaker is hb (see FIG. 1 (II)), h2 / hb is preferably 0.5 or more and 1 or less. . If it is less than 0.5, the difference in the thickness of the cemented carbide layer becomes too large and deformation is likely to occur, and if it exceeds 1.0, it is difficult to sufficiently obtain both the above-described improvement in impact resistance and the good effect of maintaining the finished surface gloss.

＜超硬合金層＞
《硬質相》
超硬合金層は、WC粒子を主たる硬質相とし、Coといった鉄族金属を主たる結合相とするWC基超硬合金から構成される。この超硬合金層は、硬質相となるWC粒子をサーメット層よりも多く含むものとする。特に、超硬合金層は、W及びWCを合計で65質量％超含有することが好ましく、80質量％以上含有することがより好ましい。また、WC粒子は、特に、0.1μm以上1.0μm以下が好ましい。上記範囲において、平均粒径が小さいと、高硬度で耐摩耗性に優れる超硬合金層が得られ、大きいと、耐熱亀裂性といった靭性に優れる超硬合金層が得られる。また、WC粒子が上記範囲であると、刃先処理幅が0.05mm以下という小さな刃先処理が可能であり、切刃稜線をシャープにできる。更に、WC粒子が上記範囲である場合、本発明工具の表面に存在する超硬合金層の上に、PVD法により被覆膜を形成すると、被覆膜において超硬合金層との界面付近で膜の結晶粒が微粒のWC粒子に倣って微細化し、膜の密着力を高められるといった効果が得られる。所望の特性に応じてWC粒子の大きさを選択することができる。超硬合金層中のWC粒子の大きさは、概ね原料粉末に依存するため、原料粉末の大きさにより調整するとよい。後述するサーメット層中の硬質相粒子の大きさも同様に原料粉末の大きさにより調整できる。 <Cemented carbide layer>
《Hard phase》
The cemented carbide layer is composed of a WC-based cemented carbide with WC particles as the main hard phase and iron group metal such as Co as the main binder phase. This cemented carbide layer contains a larger amount of WC particles as a hard phase than the cermet layer. In particular, the cemented carbide layer preferably contains a total of more than 65% by mass of W and WC, and more preferably contains 80% by mass or more. The WC particles are particularly preferably 0.1 μm or more and 1.0 μm or less. Within the above range, if the average particle size is small, a cemented carbide layer having high hardness and excellent wear resistance can be obtained, and if it is large, a cemented carbide layer having excellent toughness such as heat cracking resistance can be obtained. Further, when the WC particles are in the above range, a small blade edge treatment with a blade edge treatment width of 0.05 mm or less is possible, and the cutting edge ridge line can be sharpened. Furthermore, when the WC particles are in the above range, when a coating film is formed on the cemented carbide layer existing on the surface of the tool of the present invention by the PVD method, in the coating film, near the interface with the cemented carbide layer. The effect is that the crystal grains of the film are refined to follow the fine WC particles and the adhesion of the film is enhanced. The size of the WC particles can be selected according to the desired properties. Since the size of the WC particles in the cemented carbide layer generally depends on the raw material powder, it may be adjusted according to the size of the raw material powder. Similarly, the size of the hard phase particles in the cermet layer described later can be adjusted by the size of the raw material powder.

《結合相》
結合相は、主として鉄族金属からなり(80質量％以上が鉄族金属)、鉄族金属の他に原料粉末に起因すると考えられる元素が含有(固溶)されることを許容する。鉄族金属は、Coの他、FeやNiを含有していてもよいが、Coのみが好ましい。超硬合金層中の結合相の含有量は、3質量％以上20質量％以下が好ましい。20質量％超であると、靭性が高くなる反面、強度や耐摩耗性が低下し易く、3質量％未満であると、靭性が低下し易い。特に、5質量％以上15質量％以下であると、靭性に優れるため、好ましい。 << Binder Phase >>
The binder phase is mainly composed of an iron group metal (80% by mass or more is an iron group metal), and allows an element considered to be derived from the raw material powder in addition to the iron group metal (solid solution). The iron group metal may contain Fe or Ni in addition to Co, but only Co is preferable. The content of the binder phase in the cemented carbide layer is preferably 3% by mass or more and 20% by mass or less. If it exceeds 20% by mass, the toughness increases, but the strength and wear resistance tend to decrease, and if it is less than 3% by mass, the toughness tends to decrease. In particular, the content of 5% by mass or more and 15% by mass or less is preferable because of excellent toughness.

《その他の含有物》
超硬合金層は、WC粒子や鉄族金属の他、更に、周期律表IVa,Va,VIa族の金属元素群から選択される1種以上の元素や、同金属元素群から選択される1種以上の元素と、炭素、窒素、酸素及び硼素からなる群から選択される1種以上の元素とからなる化合物や固溶体を含有していてもよい。具体的な元素は、Cr,Ta,Ti,Nb,Zr,V、化合物は、(Ta,Nb)C,VC,Cr₂C₃,NbC,TiCNなどが挙げられる。これらの元素や化合物は、結合相に含有(固溶)されて存在したり、粒子で存在して硬質相として機能したりする。これらの元素や化合物は、焼結中においてWC粒子の粒成長を抑制する作用を有するものが多い。超硬合金層がこれらの元素や化合物を含有する場合、その含有量は、合計40質量％以下(但し0質量％を含む)が好ましい。なお、WC粒子は、これらの元素や化合物、結合相及び不純物を除く残部を構成する。《Other contents》
The cemented carbide layer is selected from one or more elements selected from the group of metal elements of the periodic table IVa, Va, VIa in addition to WC particles and iron group metals, and 1 It may contain a compound or solid solution composed of one or more elements and one or more elements selected from the group consisting of carbon, nitrogen, oxygen and boron. Specific elements include Cr, Ta, Ti, Nb, Zr, and V, and examples of the compound include (Ta, Nb) C, VC, Cr ₂ C ₃ , NbC, and TiCN. These elements and compounds exist in the binder phase (solid solution) or exist as particles and function as a hard phase. Many of these elements and compounds have an action of suppressing the grain growth of WC particles during sintering. When the cemented carbide layer contains these elements and compounds, the total content is preferably 40% by mass or less (including 0% by mass). The WC particles constitute the remainder excluding these elements, compounds, binder phases and impurities.

特に、超硬合金層は、Crを含有していることが好ましく、超硬合金層の結合相量をx1(質量％)とし、超硬合金層中のCrの含有量をx2(質量％)とするとき、x2/x1が0.02以上0.2以下を満たすことが好ましい。0.02未満とCrが少な過ぎると、粒成長抑制効果が十分に得られず、超硬合金層中のWCが粗大化して、耐摩耗性の低下を招く。逆に、0.2超とCrが多過ぎると、超硬合金の組織中にCrの析出や凝集ができ易くなり、この析出物などを起点として破壊が起こるため、耐欠損性の低下を招く。また、上記範囲でCrを含有することで、超硬合金の液相出現温度を調整することができる。Crの増加に伴い、上記液相出現温度が低下する傾向にあり、超硬合金の液相出現温度とサーメットの液相出現温度との差を小さくすることができる。同差を小さくすることで、液相移動を抑制し、液相移動による性能低下や変形などを低減できる。超硬合金層が所望の組成となるように、原料粉末の組成設計を行う。 In particular, the cemented carbide layer preferably contains Cr, and the cemented phase amount of the cemented carbide layer is x1 (mass%), and the content of Cr in the cemented carbide layer is x2 (mass%). X2 / x1 preferably satisfies 0.02 or more and 0.2 or less. If the Cr content is less than 0.02 and the Cr content is too small, the effect of suppressing grain growth cannot be obtained sufficiently, and the WC in the cemented carbide layer becomes coarse, resulting in a decrease in wear resistance. On the other hand, if it exceeds 0.2 and there is too much Cr, it becomes easy to precipitate and agglomerate Cr in the structure of the cemented carbide, and breakage occurs starting from this precipitate and the like, leading to a reduction in fracture resistance. Moreover, the liquid phase appearance temperature of a cemented carbide can be adjusted by containing Cr in the said range. As the Cr content increases, the liquid phase appearance temperature tends to decrease, and the difference between the liquid phase appearance temperature of the cemented carbide and the liquid phase appearance temperature of the cermet can be reduced. By reducing the difference, liquid phase movement can be suppressed, and performance degradation and deformation due to liquid phase movement can be reduced. The composition of the raw material powder is designed so that the cemented carbide layer has a desired composition.

＜サーメット層＞
《硬質相》
サーメット層は、少なくとも硬質相としてTi化合物を含有し、Co,Niといった鉄族金属を主たる結合相とする硬質材料から構成される。Ti化合物は、代表的には、Tiの炭化物(TiC)、Tiの窒化物(TiN)及びTiの炭窒化物(TiCN)から選択される少なくとも1種の化合物が挙げられる。その他、Ti化合物は、Ti及び周期律表IVa,Va,VIa族の金属元素(Tiを除く)と、C及びNの少なくとも1種とを含む複合化合物、即ち、Tiを含む複合炭化物、Tiを含む複合窒化物、Tiを含む複合炭窒化物が挙げられる。具体的な複合化合物は、(Ti,W,Mo,Ta,Nb)(C,N)、(Ti,W,Nb)(C,N)、(Ti,W,Mo,Ta)(C,N)、(Ti,W,Mo,Zr)(C,N)などが挙げられる。硬質相を構成するTi化合物からなる粒子は、単一の組成から構成されるものでも(例えば、TiCN)、中心部とその周辺部とでTi濃度が異なる有芯構造であってもよい。SEM観察によれば、有芯構造の粒子のうち、中心部にTiを多く含む粒子は、黒っぽく見え(黒芯粒子)、中心部にWを多く含む粒子は、白っぽく見える(白芯粒子)。これら硬質相粒子(有芯構造の粒子の場合、周辺部を含む大きさ)の平均粒径は、0.5〜5.0μm、特に1.0〜3.0μmが好ましい。また、サーメット層は、少なくともWを含有させると、超硬合金層との熱膨張係数の差を小さくして、変形や剥離を抑制し易く好ましい。サーメット層中にWを存在させるには、原料にWCを用いることが挙げられる。原料のWCは、焼結後、Wとなって結合相などに含有(固溶)されて存在し、原料の添加量の増加に伴ってWCやWを多く含む複合化合物が析出する傾向にある。析出されたWCや複合化合物は硬質相として機能する。また、原料のWCの添加量の増加に伴って、白芯粒子が増加する傾向にある。サーメット層を100質量％とするとき、WC及びWを合計15質量％以上含有していれば、上記効果を期待できる。W及びWCの合計含有量の増加に伴い、熱膨張係数の差を小さくし易いが、多過ぎると、超硬合金層に圧縮応力が存在することによる靭性の向上効果が得られ難くなることから、合計含有量は65質量％以下が好ましい。より好ましいWC及びWの合計含有量は、15質量％以上40質量％以下である。サーメット層中のWC及びW量は、原料粉末のWC添加量に概ね依存するため、原料のWC添加量を調整することで、上記所定の範囲とすることができる。また、原料のWCは、平均粒径が1〜8μm、特に3〜5μmと比較的粗大なものを用いると、サーメット層に析出されたWCなどが比較的粗粒となり、亀裂進展の抵抗の向上といった効果が得られる。サーメット層中のWC量の測定は、例えば、XRDなどで化合物の同定を行い、EDX,EPMA,蛍光X線,IPC-AESなどを用いて組成を分析することで行え、W量の測定は、上記EDXなどで組成を分析することで行える。 <Cermet layer>
《Hard phase》
The cermet layer is composed of a hard material containing at least a Ti compound as a hard phase and having an iron group metal such as Co or Ni as a main binder phase. The Ti compound typically includes at least one compound selected from Ti carbide (TiC), Ti nitride (TiN), and Ti carbonitride (TiCN). In addition, the Ti compound is a composite compound containing Ti and periodic group IVa, Va, VIa group metal elements (excluding Ti) and at least one of C and N, that is, a composite carbide containing Ti, Ti. The composite nitride containing and the composite carbonitride containing Ti are mentioned. Specific composite compounds are (Ti, W, Mo, Ta, Nb) (C, N), (Ti, W, Nb) (C, N), (Ti, W, Mo, Ta) (C, N ), (Ti, W, Mo, Zr) (C, N) and the like. The particles composed of the Ti compound constituting the hard phase may be composed of a single composition (for example, TiCN), or may have a cored structure in which the Ti concentration is different between the central portion and the peripheral portion. According to SEM observation, among the cored structure particles, particles containing a large amount of Ti at the center portion appear black (black core particles), and particles containing a large amount of W at the center portion appear white (white core particles). The average particle size of these hard phase particles (in the case of cored structure particles including the peripheral portion) is preferably 0.5 to 5.0 μm, particularly preferably 1.0 to 3.0 μm. Further, it is preferable that the cermet layer contains at least W so that the difference in thermal expansion coefficient from the cemented carbide layer is reduced and deformation and peeling are easily suppressed. In order to make W exist in the cermet layer, WC is used as a raw material. The raw material WC exists as a W after being sintered and contained (solid solution) in the binder phase, etc., and there is a tendency for the composite compound containing a large amount of WC and W to precipitate as the amount of raw material added increases. . The precipitated WC and composite compound function as a hard phase. In addition, white core particles tend to increase as the amount of raw material WC increases. When the cermet layer is 100% by mass, the above effect can be expected if the total content of WC and W is 15% by mass or more. As the total content of W and WC increases, it is easy to reduce the difference in thermal expansion coefficient, but if too much, it is difficult to obtain the effect of improving toughness due to the presence of compressive stress in the cemented carbide layer. The total content is preferably 65% by mass or less. A more preferable total content of WC and W is 15% by mass or more and 40% by mass or less. Since the amount of WC and W in the cermet layer generally depends on the amount of WC added to the raw material powder, the amount of WC added to the raw material can be adjusted to the predetermined range. If the average particle size of WC is 1 to 8 μm, especially 3 to 5 μm, the WC that is relatively coarse is used, and the WC deposited on the cermet layer becomes relatively coarse, improving the resistance to crack growth. The effect is obtained. Measurement of the amount of WC in the cermet layer can be performed, for example, by identifying the compound with XRD and analyzing the composition using EDX, EPMA, fluorescent X-ray, IPC-AES, etc. This can be done by analyzing the composition with the above EDX.

《結合相》
サーメット層中の結合相の含有量は、8質量％以上20質量％以下が好ましい。20質量％超であると、靭性が高くなる反面、強度や耐摩耗性が低下し、8質量％未満であると、焼結性、靭性が低下する。また、この結合相は、主として鉄族金属からなり(80質量％以上が鉄族金属)、鉄族金属の他に原料粉末に起因すると考えられる元素が含有(固溶)されることを許容する。鉄族金属は、Coの他、Niを含有していてもよいが、Niを多く含有すると、焼結中などでNiが超硬合金層に移動する液相移動が生じ易い。液相移動量が多いと、特に、超硬合金層の組成が変化して硬度の低下といった性能低下や本発明工具の変形などを生じる恐れがある。従って、サーメット層の結合相は、Coが多い方が好ましく、サーメット層の結合相中の鉄族金属を100質量％とするとき、80質量％以上、特に90質量％以上がCoであることが好ましく、Coのみとすることが最適である。このように結合相中にCoを多く含有することで、変形の抑制、性能低下の抑制といった効果を奏することができる。 << Binder Phase >>
The content of the binder phase in the cermet layer is preferably 8% by mass or more and 20% by mass or less. If it exceeds 20% by mass, the toughness increases, but the strength and wear resistance decrease. If it is less than 8% by mass, the sinterability and toughness decrease. This binder phase is mainly composed of an iron group metal (80% by mass or more is an iron group metal), and allows an element considered to be caused by the raw material powder in addition to the iron group metal to be contained (solid solution). . The iron group metal may contain Ni in addition to Co. However, if Ni is contained in a large amount, liquid phase transfer in which Ni moves to the cemented carbide layer easily occurs during sintering or the like. If the amount of liquid phase transfer is large, the composition of the cemented carbide layer may change, and there is a risk of performance deterioration such as a decrease in hardness, deformation of the tool of the present invention, and the like. Therefore, the binder phase of the cermet layer is preferably rich in Co. When the iron group metal in the binder phase of the cermet layer is 100% by mass, 80% by mass or more, particularly 90% by mass or more may be Co. Preferably, only Co is optimal. Thus, by containing much Co in a binder phase, there can exist an effect, such as suppression of a deformation | transformation and suppression of a performance fall.

超硬合金とサーメットとの積層体は、組成などの違いから、焼結時に液相移動が起こり易く、上述のように液相移動による性能の低下や変形が生じ易い。しかし、サーメット層の結合相の含有量と超硬合金層の結合相の含有量との差が小さいと、上記液相移動量を低減でき、液相移動に伴う特性の劣化を低減できる。具体的には、超硬合金層の結合相の含有量をy1(体積％)、サーメット層の結合相の含有量をy2(体積％)とするとき、y1/y2が0.8以上1.2以下を満たすことが好ましい。0.8未満及び1.2超では、結合相量が多い方から少ない方に液相移動が生じ易くなる。また、上述のように超硬合金層にCrを添加すると、液相移動を抑制することができる。 A laminated body of cemented carbide and cermet is liable to cause liquid phase movement during sintering due to differences in composition and the like, and as described above, performance deterioration and deformation are liable to occur due to liquid phase movement. However, if the difference between the content of the binder phase in the cermet layer and the content of the binder phase in the cemented carbide layer is small, the liquid phase transfer amount can be reduced, and the deterioration of the characteristics accompanying the liquid phase transfer can be reduced. Specifically, when the binder phase content of the cemented carbide layer is y1 (volume%) and the binder phase content of the cermet layer is y2 (volume%), y1 / y2 satisfies 0.8 or more and 1.2 or less. It is preferable. If it is less than 0.8 and more than 1.2, liquid phase transfer tends to occur in the direction from the larger amount of the binder phase to the smaller amount. Moreover, when Cr is added to the cemented carbide layer as described above, liquid phase transfer can be suppressed.

《その他の含有物》
サーメット層も上記超硬合金と同様に、Cr,Ta,Nb,Zr,V,Moといった元素や(Ta,Nb)C,VC,Cr₂C₃,NbCといった化合物を更に含有していてもよく、その含有量は、合計で5〜50質量％が好ましい。なお、サーメット層において、結合相及び不純物を除く残部が硬質相を構成する。サーメット層が所望の組成となるように、原料粉末の組成設計を行う。《Other contents》
The cermet layer may further contain elements such as Cr, Ta, Nb, Zr, V, Mo and compounds such as (Ta, Nb) C, VC, Cr ₂ C ₃ , and NbC, similar to the above cemented carbide. The content is preferably 5 to 50% by mass in total. In the cermet layer, the remainder excluding the binder phase and impurities constitutes the hard phase. The composition of the raw material powder is designed so that the cermet layer has a desired composition.

《刃先処理》
本発明工具において表面の稜線の少なくとも一部は、切刃になる。切刃は、焼結したままの状態でもよいが、ホーニングといった刃先処理を行うことで、耐チッピング性を向上できることに加えて、ワーク(被削材)の加工面粗さをより小さくして良好な加工面が得られる。ここで、サーメットからなる基材は、焼結したままではシャープな刃先であるものの、靭性が低いためチッピングが生じ易く、刃先処理をしようとしても、靭性が低いため、シャープな刃先処理が難しく、加工面粗さが大きくなり易い。これに対し、本発明工具は、切刃となる部分の少なくとも一部に靭性が高い超硬合金層を具えるため、刃先処理を行わなくても、耐チッピング性に優れる。また、刃先処理を行う場合でも、本発明工具は、刃先処理を施す部分に靭性が高い超硬合金層を具えるため、上記刃先処理により、シャープな刃先が得られることから、加工面粗さをより小さくすることができる。更に、加工精度の向上に加えて、バリの発生も抑制することができる。刃先処理量は、刃先処理幅が0mm超0.05mm以下であることが好ましい。0.05mm超では、刃先が鋭くないため、加工面粗さが小さくならず、加工精度を十分に向上できない。《Blade treatment》
In the tool of the present invention, at least a part of the surface ridge line becomes a cutting edge. The cutting edge may be in the as-sintered state, but in addition to being able to improve chipping resistance by performing cutting edge processing such as honing, it is better to reduce the work surface roughness of the workpiece (work material) A machined surface can be obtained. Here, although the base material made of cermet is a sharp cutting edge as it is sintered, chipping is likely to occur due to low toughness, and even when trying to perform cutting edge processing, because the toughness is low, sharp cutting edge processing is difficult, The machined surface roughness tends to increase. On the other hand, since the tool of the present invention includes a cemented carbide layer having high toughness in at least a part of a portion serving as a cutting edge, the chipping resistance is excellent even without performing blade edge treatment. Even when performing the blade edge treatment, the tool of the present invention includes a cemented carbide layer having high toughness in the portion subjected to the blade edge treatment, and therefore, a sharp edge can be obtained by the above-mentioned blade edge treatment. Can be made smaller. Furthermore, in addition to improving the processing accuracy, the generation of burrs can also be suppressed. The cutting edge processing amount is preferably such that the cutting edge processing width is more than 0 mm and not more than 0.05 mm. If it exceeds 0.05 mm, the cutting edge is not sharp, so the surface roughness will not be small and the processing accuracy cannot be improved sufficiently.

《圧縮応力》
超硬合金層及びサーメット層について、熱膨張係数及び収縮率を調整することにより、上述のように超硬合金層に圧縮応力を存在させることができる。熱膨張係数の異なる材料を積層すると、熱膨張係数の小さい側に圧縮応力が生じ、この圧縮応力が原因で層間剥離が生じることがある。これに対し、本発明工具は、上述のように両層が微視的に係合することで、上記圧縮応力に起因する層間剥離が生じ難く、圧縮応力による靭性の向上効果が期待できる。但し、圧縮応力が大き過ぎると層間剥離が生じるため、剥離が生じない範囲で圧縮応力を存在させることが好ましい。圧縮応力の調整は、上述のように熱膨張係数及び収縮率を調整する、具体的には、原料粉末の組成などを調整することが挙げられる。圧縮応力の大きさは、例えば、超硬合金層の表面をラッピングした後、その表面の中心付近をXRDにより測定することで求められる。好適な圧縮応力の大きさは、0.1〜3.0GPa程度である。《Compressive stress》
By adjusting the thermal expansion coefficient and shrinkage rate of the cemented carbide layer and the cermet layer, compressive stress can be present in the cemented carbide layer as described above. When materials having different thermal expansion coefficients are laminated, compressive stress is generated on the side having a smaller thermal expansion coefficient, and delamination may occur due to the compressive stress. On the other hand, since the present invention tool is microscopically engaged as described above, delamination due to the compressive stress hardly occurs, and an effect of improving toughness due to the compressive stress can be expected. However, since the delamination occurs when the compressive stress is too large, it is preferable that the compressive stress exists within a range in which delamination does not occur. The adjustment of the compressive stress includes adjusting the thermal expansion coefficient and the shrinkage rate as described above, specifically, adjusting the composition of the raw material powder. The magnitude of the compressive stress is obtained, for example, by wrapping the surface of the cemented carbide layer and measuring the vicinity of the center of the surface by XRD. A suitable magnitude of the compressive stress is about 0.1 to 3.0 GPa.

＜製造方法＞
本発明工具は、上述のように造粒粉末を準備して、所望の積層構造となるように順次金型に供給し、全ての粉末を金型に充填した後プレスして、積層構造のプレス成形体を形成し、この成形体を焼結することで製造できる。得られた焼結体(本発明工具)は、超硬合金層とサーメット層との境界に、造粒の大きさや形状に概ね対応した凹凸形状を有する。凹凸形状は、造粒径を例えば、10〜200μmに調整したり、造粒径や造粒粉末の硬さ、密度、形状といった造粒粉末の性状、プレス圧力などを調整することで変化できる。これらの要因を制御することで、超硬合金層とサーメット層との接合性に優れる本発明工具が得られる。押圧時の圧力は、0.5t/cm²以上2.5t/cm²以下が好ましい。0.5t/cm²未満では、プレス成形体の密度が低く、焼結時の収縮量が大きくなって寸法精度が低下し易く、2.5t/cm²超では、プレス成形体が緻密化し過ぎて、亀裂が生じ易く、特に複雑な形状の成形体の場合、亀裂の発生がより多くなる。本発明工具の表面側に具える超硬合金層は、比較的薄いため、押圧に用いるパンチの形状に倣い易く、工具外形と、表面側の超硬合金層とサーメット層との境界の形状とが概ね相似形状となる。 <Manufacturing method>
The tool of the present invention prepares the granulated powder as described above, sequentially supplies it to the mold so as to obtain a desired laminated structure, presses after filling all the powder into the mold, and presses the laminated structure It can be manufactured by forming a molded body and sintering the molded body. The obtained sintered body (tool of the present invention) has a concavo-convex shape generally corresponding to the size and shape of granulation at the boundary between the cemented carbide layer and the cermet layer. The uneven shape can be changed by adjusting the granulated particle size to, for example, 10 to 200 μm, or adjusting the granulated powder properties such as the granulated particle size, the hardness, density, and shape of the granulated powder, and the press pressure. By controlling these factors, it is possible to obtain the tool of the present invention which is excellent in the bondability between the cemented carbide layer and the cermet layer. The pressure during pressing is preferably 0.5 t / cm ² or more and 2.5 t / cm ² or less. If the density is less than 0.5 t / cm ² , the density of the press-molded body is low, the shrinkage amount during sintering is large, and the dimensional accuracy tends to decrease, and if it exceeds 2.5 t / cm ² , the press-molded body is too dense, Cracks are likely to occur, and more cracks are generated particularly in the case of a molded article having a complicated shape. Since the cemented carbide layer provided on the surface side of the tool of the present invention is relatively thin, it is easy to follow the shape of the punch used for pressing, and the outer shape of the tool and the shape of the boundary between the cemented carbide layer on the surface side and the cermet layer Is a similar shape.

上記焼結は、焼結体の形成と共に、超硬合金層とサーメット層との一体接合も兼ねる。焼結は、一般的な条件を利用することができる。例えば、焼結条件は、真空雰囲気で1300〜1500℃に0.5〜3.0時間保持することが挙げられる。 The above-mentioned sintering also serves as integral bonding of the cemented carbide layer and the cermet layer together with the formation of the sintered body. Sintering can utilize general conditions. For example, the sintering conditions include holding at 1300-1500 ° C. in a vacuum atmosphere for 0.5-3.0 hours.

＜用途＞
本発明工具は、超硬合金層とサーメット層との双方の特性を兼ね備え、高靭性で、仕上げ面精度に優れる。従って、本発明工具は、特に、仕上げ加工に好適に利用することができる。本発明工具の代表的な形態としては、フライス加工用刃先交換型チップ、旋削用刃先交換型チップが挙げられる。その他、ドリル、エンドミル、メタルソー、歯切工具、リーマ、タップなどの利用が期待できる。 <Application>
The tool of the present invention combines the characteristics of both a cemented carbide layer and a cermet layer, has high toughness and excellent finished surface accuracy. Therefore, the tool of the present invention can be suitably used particularly for finishing. As a typical form of the tool of the present invention, there are a cutting edge exchangeable tip for milling and a cutting edge exchangeable tip for turning. In addition, use of drills, end mills, metal saws, gear cutting tools, reamers, taps, etc. can be expected.

本発明工具は、基材表面に被覆膜を具えた被覆切削工具としてもよい。ここで、サーメットからなる基材は、一般に被覆膜との密着性が低い。これに対し、本発明工具は、超硬合金層を具えることで被覆膜との密着性を向上することができ、良好な仕上げ面光沢も得られる。被覆膜は、少なくとも切刃及びその近傍に具えることが好ましい。被覆膜の組成は、例えば、周期律表IVa,Va,VIa族元素,及びSi,Alから選ばれる少なくとも1種の元素と、炭素(C),窒素(N),酸素(O),及び硼素(B)から選ばれる少なくとも1種の元素とからなる化合物、ダイヤモンド、ダイヤモンドライクカーボン(DLC)、及び立方晶窒化硼素(cBN)から選択される少なくとも1種からなるものが挙げられる。即ち、上記金属などの元素の炭化物、窒化物、酸化物、硼化物及びこれらの固溶体からなるもの、例えば、TiCN,Al₂O₃,TiAlN,TiN,AlCrN,TiSiN、ダイヤモンド、DLC、及びcBNのうち、1種以上が挙げられる。上記の候補から選択される膜を1層以上具える被覆切削工具は、被覆膜がない状態と比較して、耐摩耗性をより向上できる。被覆膜は、単層でも複数層でもよく、合計膜厚は、1〜20μmが好ましい。PVD法にて形成する場合、合計膜厚は、1〜10μmがより好ましい。被覆膜の厚さは、成膜時間を調整することで変化させられる。 The tool of the present invention may be a coated cutting tool having a coating film on the substrate surface. Here, the base material which consists of cermets generally has low adhesiveness with a coating film. On the other hand, the tool of the present invention can improve the adhesion with the coating film by providing the cemented carbide layer, and can obtain a good finished surface gloss. The coating film is preferably provided at least on the cutting edge and in the vicinity thereof. The composition of the coating film is, for example, periodic table IVa, Va, VIa group elements, and at least one element selected from Si, Al, carbon (C), nitrogen (N), oxygen (O), and Examples thereof include compounds composed of at least one element selected from boron (B), at least one selected from diamond, diamond-like carbon (DLC), and cubic boron nitride (cBN). That is, carbides, nitrides, oxides, borides, and solid solutions of these elements such as metals, such as TiCN, Al ₂ O ₃ , TiAlN, TiN, AlCrN, TiSiN, diamond, DLC, and cBN Of these, one or more may be mentioned. A coated cutting tool having one or more layers selected from the above-mentioned candidates can further improve wear resistance as compared with a state without a coating layer. The coating film may be a single layer or a plurality of layers, and the total film thickness is preferably 1 to 20 μm. When formed by the PVD method, the total film thickness is more preferably 1 to 10 μm. The thickness of the coating film can be changed by adjusting the film formation time.

被覆膜の形成は、PVD法,CVD法のいずれも利用することができる。例えば、PVD法としてアークイオンプレーティング法を利用する場合、成膜条件は、基材温度:400〜600℃、雰囲気の圧力：0.5〜5Pa、バイアス電圧:-50〜-150Vが挙げられる。例えば、CVD法として熱CVD法を利用する場合、成膜条件は、基材温度:800〜1000℃、ガス圧:5〜10MPa、反応ガス:CH₄,H₂,N₂,CO₂,AlCl₃,TiCl₄などが挙げられる。成膜条件は、公知の条件を利用することができる。 The PVD method and the CVD method can be used to form the coating film. For example, when the arc ion plating method is used as the PVD method, the film formation conditions include a substrate temperature: 400 to 600 ° C., an atmospheric pressure: 0.5 to 5 Pa, and a bias voltage: −50 to −150 V. For example, when the thermal CVD method is used as the CVD method, the film forming conditions are: substrate temperature: 800 to 1000 ° C., gas pressure: 5 to 10 MPa, reaction gas: CH ₄ , H ₂ , N ₂ , CO ₂ , AlCl ₃ , TiCl _{4 and the} like. As film formation conditions, known conditions can be used.

CVD法により例えばTi化合物の成膜を行う場合、サーメット層中にNiを多く含有すると、Niが膜の性能に悪影響を及ぼす可能性があるため、サーメット層の結合相中のCo量を高めることが好ましいと考えられる。一方、PVD法により成膜する場合、通常、CVD法よりもPVD法による膜の方が薄膜であることから、シャープな刃先が得られ易い。また、CVD法よりもPVD法による膜の方が膜の表面粗さも小さくなり易い。従って、上述した刃先処理を行わない基材にPVD法による薄膜を形成した場合でも、耐摩耗性を向上させることができ、また、加工面粗さが小さく、加工精度に優れる。更に、刃先処理幅が0.05mm以下の小さな刃先処理を行った基材にPVD膜を形成すると、加工精度をある程度維持しつつ、刃先の欠けを効果的に抑制することができる。 For example, when forming a Ti compound film by the CVD method, if Ni is contained in the cermet layer, Ni may adversely affect the performance of the film. Therefore, increase the amount of Co in the binder phase of the cermet layer. Is considered preferable. On the other hand, when a film is formed by the PVD method, since a film by the PVD method is usually thinner than a CVD method, a sharp cutting edge is easily obtained. In addition, the surface roughness of the film by the PVD method tends to be smaller than that by the CVD method. Therefore, even when a thin film formed by the PVD method is formed on a base material that is not subjected to the above-mentioned blade edge treatment, the wear resistance can be improved, the processed surface roughness is small, and the processing accuracy is excellent. Furthermore, when a PVD film is formed on a base material that has been subjected to a small blade edge treatment with a blade edge treatment width of 0.05 mm or less, chipping of the blade edge can be effectively suppressed while maintaining processing accuracy to some extent.

本発明切削工具は、超硬合金層とサーメット層との双方の特性を兼ね備え、耐衝撃性に優れると共に良好な仕上げ面光沢が得られる。 The cutting tool of the present invention combines the characteristics of both a cemented carbide layer and a cermet layer, and is excellent in impact resistance and has a good finished surface gloss.

(試験例1)
超硬合金層とサーメット層とが積層された複合材料からなる切削工具を作製して、切削性能を調べた。この試験では、切刃部分の超硬合金層の厚さが異なる試料、及び比較としてサーメットのみからなる試料を用いた。 (Test Example 1)
A cutting tool made of a composite material in which a cemented carbide layer and a cermet layer were laminated was produced, and the cutting performance was examined. In this test, a sample having a different thickness of the cemented carbide layer in the cutting edge portion and a sample made of only cermet as a comparison were used.

切削工具は、以下のように作製した。表1に示す組成となるように原料粉末を秤量し、これら原料粉末をエタノール中で11時間、アトライター(ATR)により混合した後、造粒を行い、平均粒径100μmの超硬合金用粉末(造粒粉末)、及びサーメット用粉末(造粒粉末)を得る。造粒粉末の平均粒径の測定は、粉末のSEM(走査電子顕微鏡)写真を画像解析して行ったが、粒度測定器などを用いて行うこともできる。超硬合金層及びサーメット層が所望の厚さとなるように、得られた超硬合金用粉末、及びサーメット粉末を量り取る。なお、表1及び後述する表15において、超硬合金における「Cr比」とは、結合相(ここでは主にCo)の含有量x1(質量％)に対するCrの含有量x2(質量％)の割合:x2/x1(無単位)を示す。サーメットにおける「Co割合」とは、結合相(ここでは主にCo+Ni)の含有量を100質量％とするときのCoの含有量(質量％)を示す。 The cutting tool was produced as follows. The raw material powder was weighed so as to have the composition shown in Table 1, and these raw material powders were mixed in ethanol for 11 hours with an attritor (ATR), then granulated, and the powder for cemented carbide with an average particle size of 100 μm (Granulated powder) and cermet powder (granulated powder) are obtained. Measurement of the average particle size of the granulated powder was performed by image analysis of a SEM (scanning electron microscope) photograph of the powder, but can also be performed using a particle size measuring instrument or the like. The obtained cemented carbide powder and cermet powder are weighed out so that the cemented carbide layer and the cermet layer have a desired thickness. In Table 1 and Table 15 described later, the “Cr ratio” in the cemented carbide is the content of Cr x2 (mass%) with respect to the binder phase (mainly Co) content x1 (mass%). Ratio: Indicates x2 / x1 (no unit). The “Co ratio” in the cermet indicates the Co content (mass%) when the content of the binder phase (mainly Co + Ni here) is 100 mass%.

得られた超硬合金用粉末、及びサーメット用粉末を用いて積層プレス成形体を作製する。この試験では、四角柱状のブレーカー付き切削チップ(住友電気工業株式会社型番:SNMG120408N-UX)を作製した。具体的には、所定形状の金型に、超硬合金用粉末、サーメット用粉末、超硬合金用粉末を順に給粉した後、1.0t/cm²で押圧して積層プレス成形体を作製する。得られた成形体を真空雰囲気にて1430℃×60minの条件で焼結して、図2に示すように、一つのサーメット層12を挟むように一対の超硬合金層11を配置した三層構造の複合材料を得る。この複合材料は、上下面の全面が実質的に超硬合金層で形成され、側面が超硬合金層とサーメット層との積層面で形成される。得られたの複合材料の角部において、上下面と側面との交線の一部に刃先処理(刃先処理幅w(図1(III)参照):0.04mm)を施して切削工具10が得られる。なお、切削工具10の上下面がすくい面、側面が逃げ面であり、すくい面と逃げ面との交線が切刃、すくい面に具える凹み部分及び突出部分の一部がチップブレーカーであり、工具中央に本体(図示せず)に取り付けるための取付穴14を具える。 A laminated press-molded body is produced using the obtained powder for cemented carbide and cermet powder. In this test, a square pillar-shaped cutting tip with a breaker (Sumitomo Electric Industries, Ltd. model number: SNMG120408N-UX) was produced. Specifically, cemented carbide powder, cermet powder, and cemented carbide powder are sequentially fed to a mold having a predetermined shape, and then pressed at 1.0 t / cm ² to produce a laminated press-formed body. . The obtained molded body was sintered in a vacuum atmosphere at 1430 ° C. for 60 minutes, and as shown in FIG. 2, three layers in which a pair of cemented carbide layers 11 were arranged so as to sandwich one cermet layer 12 A structural composite material is obtained. In this composite material, the entire upper and lower surfaces are substantially formed of a cemented carbide layer, and the side surfaces are formed of a laminated surface of a cemented carbide layer and a cermet layer. At the corner of the obtained composite material, cutting edge processing (cutting edge processing width w (see FIG. 1 (III)): 0.04 mm) is applied to part of the line of intersection between the upper and lower surfaces and the side surface to obtain the cutting tool 10. It is done. The upper and lower surfaces of the cutting tool 10 are the rake face and the side face are the flank face, the intersection line between the rake face and the flank face is the cutting edge, and the dent part and the protruding part of the rake face are chip breakers. In the center of the tool, an attachment hole 14 for attaching to a main body (not shown) is provided.

得られた切削工具の積層方向における最大厚さh1は4.76mmであり、切刃部分(逃げ面からすくい面方向に1000μmまでの領域)における超硬合金層の最大厚さh2、ブレーカー部分における超硬合金層の最大厚さ(ここでは切刃よりもすくい面側に突出した部分の最大厚さ)hbを表3に示す。切削工具の厚さh1の測定は、ハイトゲージを用いて行い、超硬合金層の厚さh2,hbの測定は、切削工具の断面を顕微鏡観察し(500倍)、その観察像を用いて行った。この観察像において、切削工具の境界13の形状を調べたところ、概ね外形(押圧パンチ)に沿った形状であるが、部分的にパンチの形状に沿わない微細な凹凸が見られる。また、切刃部分の超硬合金層の厚さは、概ね均一的である。更に、超硬合金層のWCの平均粒径を測定したところ、0.9μmである。平均粒径は、工具の切断面をラッピングしてSEMによる結晶解析を行い、解析画像を画像解析装置に取り込んで解析して、切断面におけるWC粒子の結晶粒の粒径(μm)を測定して、これらの平均値とする。これら切削工具について、両層の境界から切刃部分における超硬合金層の最大厚さh2の1/2の地点(例えば、h2＝100μmの場合、境界から50μmの地点)の結合相量をEPMAで測定したところ、超硬合金層の結合相量y1は16.2体積％、サーメット層の結合相量y2は15.8体積％、y1/y2:1.0である。超硬合金層中のCr量、サーメット層中のCo量も結合相量の測定と同様にして測定して、Cr比、Co割合を求められる。測定は、EPMAの他、EDXを利用してもよい。また、サーメット層のW及びWCの合計量を測定したところ、36.3質量％である。W量は、上記Co量と同様に測定し、WC量は、両層の境界から100μmの地点について、EPMA及びXRDを用いて測定し、これらを合計してW及びWCの合計含有量としている。これらの測定量は、いずれも平均値である。なお、得られた複合材料についてサーメット層の組織をSEMにより観察したところ、硬質相粒子として、TiCN粒子、黒芯粒子、白芯粒子が存在していた。 The maximum thickness h1 in the stacking direction of the obtained cutting tool is 4.76 mm, the maximum thickness h2 of the cemented carbide layer in the cutting edge part (area from the flank face to the rake face direction is 1000 μm), and the superthickness in the breaker part. Table 3 shows the maximum thickness hb of the hard alloy layer (here, the maximum thickness of the portion protruding to the rake face side of the cutting edge). The thickness h1 of the cutting tool is measured using a height gauge, and the thickness h2 and hb of the cemented carbide layer is measured by observing the section of the cutting tool with a microscope (500 times) and using the observation image. It was. In this observation image, when the shape of the boundary 13 of the cutting tool was examined, the shape was substantially along the outer shape (press punch), but fine irregularities that did not partially follow the punch shape were observed. Moreover, the thickness of the cemented carbide layer in the cutting edge portion is substantially uniform. Furthermore, when the average particle diameter of WC of the cemented carbide layer was measured, it was 0.9 μm. The average particle size is determined by wrapping the cut surface of the tool and performing crystal analysis by SEM, taking the analysis image into an image analyzer and analyzing it, and measuring the particle size (μm) of the WC particles on the cut surface. And the average of these values. For these cutting tools, the amount of the binder phase from the boundary between the two layers to the point 1/2 of the maximum thickness h2 of the cemented carbide layer at the cutting edge part (for example, the point 50 μm from the boundary when h2 = 100 μm) is EPMA. As a result of measurement, the bonded phase amount y1 of the cemented carbide layer is 16.2% by volume, and the bonded phase amount y2 of the cermet layer is 15.8% by volume, y1 / y2: 1.0. The Cr content and the Co ratio can be obtained by measuring the Cr content in the cemented carbide layer and the Co content in the cermet layer in the same manner as the measurement of the binder phase. For the measurement, EDX may be used in addition to EPMA. The total amount of W and WC in the cermet layer was measured and found to be 36.3% by mass. The amount of W was measured in the same manner as the amount of Co above, and the amount of WC was measured using EPMA and XRD at a point 100 μm from the boundary between both layers, and these were combined to obtain the total content of W and WC. . These measured amounts are all average values. When the structure of the cermet layer of the obtained composite material was observed by SEM, TiCN particles, black core particles, and white core particles were present as hard phase particles.

得られた切削工具を用いて、表2に示す切削条件で靭性試験及び仕上げ加工試験(いずれも旋削加工)を行った。その結果を表3に示す。靭性(耐欠損性)は、工具が破損するまでの衝撃回数を評価した。仕上げ加工では、仕上げ面光沢を評価した。仕上げ面光沢は、加工後のワークを目視により確認し、黒光りの金属光沢を有する場合を○、白光りの金属光沢を有する場合を△、白濁した状態である場合を×とした。なお、仕上げ面が綺麗であれば、金属光沢が黒っぽく見え、通常の金属光沢は、白っぽく見え、仕上げ面が粗いと白濁して見える。 Using the obtained cutting tool, a toughness test and a finishing test (both turned) were performed under the cutting conditions shown in Table 2. The results are shown in Table 3. As for toughness (breakage resistance), the number of impacts until the tool was damaged was evaluated. In the finishing process, the gloss of the finished surface was evaluated. As for the finished surface gloss, the processed workpiece was visually confirmed, and the case where it had a black metallic luster, the case where it had a white metallic gloss, Δ, and the case where it was cloudy, x. If the finished surface is clean, the metallic luster appears blackish, the normal metallic luster appears whitish, and the roughened surface appears cloudy.

表3に示すように、超硬合金層を具える試料は、サーメットのみからなる試料No.100と比較して、靭性に優れることが分かる。かつ、切刃部分の超硬合金層が100μm以下の薄い試料は、良好な仕上げ面光沢が得られることが分かる。特に、切刃部分の超硬合金層が10μm以上50μm以下の試料は、靭性及び仕上げ精度の双方に優れることが分かる。なお、超硬合金層を具える試料はいずれも、超硬合金層が剥離することが無かった。この理由は、超硬合金層とサーメット層との境界に微視的な凹凸が存在したためであると考えられる。 As shown in Table 3, it can be seen that the sample provided with the cemented carbide layer is superior in toughness as compared with Sample No. 100 consisting only of cermet. In addition, it can be seen that a thin sample having a cemented carbide layer of the cutting edge portion of 100 μm or less can obtain a good finished surface gloss. In particular, it can be seen that a sample having a cemented carbide layer of the cutting edge portion of 10 μm or more and 50 μm or less is excellent in both toughness and finishing accuracy. In addition, in any sample including the cemented carbide layer, the cemented carbide layer did not peel off. The reason for this is considered that microscopic irregularities existed at the boundary between the cemented carbide layer and the cermet layer.

(試験例2)
試験例1と同様にして同じ形状の切削工具(切削チップ)を作製し、超硬合金層の剥離状態、及び切削性能を調べた。この試験では、試験例1で用いた工具のサーメット層に対して組成(W及びWCの合計含有量)を変えた点以外の点は、試験例1と概ね同様としている(超硬合金層の組成:試験例1と同様、厚さh1:4.76mm、切刃部分の超硬合金層の厚さh2:50μm(h2/h1＝0.01)、ブレーカー部分の超硬合金層の厚さhb:100μm(h2/hb＝0.5)、刃先処理幅:0.04mm、超硬合金層のCr比:0.06、サーメット層のCo割合:88.9質量％、超硬合金層のWC粒子の平均粒径:0.9μm)。原料に用いたWCの添加量を変化させることで、表4に示すようにサーメット層のW及びWCの合計含有量を変化させた。上記原料のWCの添加量の増減した分に対して、原料のTiCNの添加量を増減させ、TiCNとWCとの合計量が試験例1と同様になるようにした。サーメット層中のW量及びWC量の測定は、試験例1と同様に行った。また、工具の両層の結合相量比y1/y2を試験例1と同様にして調べたところ、いずれの試料もy1/y2:0.8〜1.2を満たしていた。 (Test Example 2)
A cutting tool (cutting tip) having the same shape was produced in the same manner as in Test Example 1, and the peeled state of the cemented carbide layer and the cutting performance were examined. In this test, points other than the change in the composition (total content of W and WC) with respect to the cermet layer of the tool used in Test Example 1 are substantially the same as in Test Example 1 (the cemented carbide layer). Composition: Similar to Test Example 1, thickness h1: 4.76 mm, cemented carbide layer thickness h2 at cutting edge: 50 μm (h2 / h1 = 0.01), cemented carbide layer thickness at breaker hb: 100 μm (h2 / hb = 0.5), cutting edge treatment width: 0.04 mm, Cr ratio of cemented carbide layer: 0.06, Co ratio of cermet layer: 88.9 mass%, average particle size of WC particles of cemented carbide layer: 0.9 μm) . By changing the amount of WC used as a raw material, the total content of W and WC in the cermet layer was changed as shown in Table 4. The amount of TiCN added to the raw material was increased or decreased relative to the amount of increase or decrease in the amount of WC added to the raw material, so that the total amount of TiCN and WC was the same as in Test Example 1. Measurement of the amount of W and the amount of WC in the cermet layer was performed in the same manner as in Test Example 1. Further, when the binder phase ratio y1 / y2 between both layers of the tool was examined in the same manner as in Test Example 1, all the samples satisfied y1 / y2: 0.8 to 1.2.

得られた切削工具について、超硬合金層の剥離状態を調べた。その結果を表4に示す。また、得られた切削工具を用いて、表2に示す切削条件で靭性(耐欠損性)試験を行った。その結果を表4に示す。剥離状態は顕微鏡又は目視で観察し、超硬合金層とサーメット層との接合界面において、超硬合金層の少なくとも一部がサーメット層と接合せず、浮き上がっていたり、超硬合金層の一部が脱落しているものを×、脱落や浮きが無いものの微小なヒビを有するものを△、上記浮き、脱落、ヒビの無いものを○と評価する。靭性の評価は、試験例1と同様である。靭性の評価が「×」の試料は、焼結後に超硬合金層の剥離が生じたために切削試験を行っていない。 About the obtained cutting tool, the peeling state of the cemented carbide layer was investigated. The results are shown in Table 4. Further, using the obtained cutting tool, a toughness (breakage resistance) test was performed under the cutting conditions shown in Table 2. The results are shown in Table 4. The peeled state is observed with a microscope or visually, and at the bonding interface between the cemented carbide layer and the cermet layer, at least a part of the cemented carbide layer is not joined with the cermet layer and is floating or part of the cemented carbide layer. Is evaluated as “X”, with no omission or floating but with a fine crack, and with no floating, omission or crack. Evaluation of toughness is the same as in Test Example 1. A sample having a toughness evaluation of “x” has not been subjected to a cutting test because peeling of the cemented carbide layer occurred after sintering.

表4に示すように、サーメット層に含有されるW及びWCの合計含有量が多くなるほど、剥離し難いことが分かる。しかし、W及びWCが多過ぎると、靭性が低下し易いことが分かる。この理由は、工具中にW及びWCの合計含有量が多くなり過ぎて超硬合金層とサーメット層との熱膨張係数の差が小さくなり、超硬合金層に導入される圧縮応力が小さくなったためと考えられる。なお、原料のWCの添加量が多くなるにつれて、サーメット層中にWCや白芯粒子の析出が認められた。 As shown in Table 4, it can be seen that the higher the total content of W and WC contained in the cermet layer, the more difficult it is to peel off. However, it can be seen that if there is too much W and WC, the toughness tends to decrease. This is because the total content of W and WC in the tool becomes too large, the difference in thermal expansion coefficient between the cemented carbide layer and the cermet layer is reduced, and the compressive stress introduced into the cemented carbide layer is reduced. It is thought that it was because of. As the amount of WC added as a raw material increased, precipitation of WC and white core particles was observed in the cermet layer.

(試験例3)
試験例1と同様にして同じ形状の切削チップを作製して基材とし、この基材に被覆膜を形成して被覆切削工具を作製し、切削性能を調べた。この試験では、試験例1で用いた切削チップに対して、サーメット層のCo割合を変えた点以外の点は、試験例1と概ね同様としている(超硬合金層の組成:試験例1と同様、厚さh1:4.76mm、切刃部分の超硬合金層の厚さh2:50μm(h2/h1＝0.01)、ブレーカー部分の超硬合金層の厚さhb:100μm(h2/hb＝0.5)、刃先処理幅:0.04mm、超硬合金層のCr比:0.06、サーメット層のW及びWCの合計含有量:36.3質量％、超硬合金層のWC粒子の平均粒径:0.9μm)。Coの含有量の増減した分に対して、Niの含有量を増減させ、結合相の合計量が試験例1と同様になるようにした。そして、原料に用いたCo量を変化させることで、表7に示すようにサーメット層の結合相中のCo量を変化させた。表7中のCo割合は、結合相中の鉄族金属量を100質量％とする。鉄族金属量及びCo量は、試験例1の結合相量の測定と同様にEPMAで同様にして測定した。また、基材の両層の結合相量比y1/y2を試験例1と同様にして調べたところ、いずれの試料も0.8〜1.2を満たしていた。 (Test Example 3)
In the same manner as in Test Example 1, a cutting tip having the same shape was prepared as a base material, a coating film was formed on the base material to prepare a coated cutting tool, and the cutting performance was examined. In this test, the cutting tip used in Test Example 1 is substantially the same as Test Example 1 except that the Co ratio of the cermet layer is changed (the composition of the cemented carbide layer: Test Example 1 and Similarly, the thickness h1: 4.76 mm, the thickness of the cemented carbide layer at the cutting edge h2: 50 μm (h2 / h1 = 0.01), the thickness of the cemented carbide layer at the breaker portion hb: 100 μm (h2 / hb = 0.5) ), Cutting edge treatment width: 0.04 mm, Cr ratio of cemented carbide layer: 0.06, total content of W and WC in cermet layer: 36.3% by mass, average particle size of WC particles in cemented carbide layer: 0.9 μm). The amount of Ni was increased or decreased with respect to the amount of increase or decrease of the Co content, so that the total amount of the binder phase was the same as in Test Example 1. Then, by changing the amount of Co used as a raw material, the amount of Co in the binder phase of the cermet layer was changed as shown in Table 7. In the Co ratio in Table 7, the amount of iron group metal in the binder phase is 100% by mass. The amount of iron group metal and the amount of Co were measured by EPMA in the same manner as in the measurement of the binder phase amount in Test Example 1. Further, when the binder phase amount ratio y1 / y2 of both layers of the base material was examined in the same manner as in Test Example 1, all the samples satisfied 0.8 to 1.2.

得られた基材に、CVD法(ここでは熱CVD法)により、公知の条件で表5に示す組成の被覆膜(三層)を形成して被覆切削工具を作製し、表6に示す切削条件で切削試験(いずれも旋削加工)を行い、耐摩耗性及び靭性(耐欠損性)を調べた。その結果を表7に示す。靭性の評価は、試験例1と同様であり、耐摩耗性の評価は、30分後の逃げ面摩耗量(mm)を測定して行った。 On the obtained base material, a coating film (three layers) having the composition shown in Table 5 was formed under a known condition by a CVD method (here, thermal CVD method) to produce a coated cutting tool, and shown in Table 6. Cutting tests (both turning) were performed under the cutting conditions to examine the wear resistance and toughness (breakage resistance). The results are shown in Table 7. The evaluation of toughness was the same as in Test Example 1, and the evaluation of wear resistance was performed by measuring the flank wear amount (mm) after 30 minutes.

表7に示すように、サーメット層の結合相に対するCo割合が高くなるほど、靭性に優れることが分かる。かつ、耐摩耗性にも優れることが分かる。これは、Niを低減して液相の移動を抑制することで変形を防止して硬度の低下を低減したことで、結果として耐摩耗性を向上できたと考えられる。また、この試験では、CVD膜を形成したが、基材が超硬合金層を具えることで基材と被覆膜との密着性に優れていた。 As shown in Table 7, it can be seen that the higher the Co ratio of the cermet layer to the binder phase, the better the toughness. It is also found that the wear resistance is excellent. This is thought to be because the wear resistance was improved as a result of reducing the decrease in hardness by preventing deformation by reducing the movement of the liquid phase by reducing Ni. In this test, a CVD film was formed, but the base material provided with a cemented carbide layer was excellent in adhesion between the base material and the coating film.

(試験例4)
試験例1と同様にして同じ形状の切削チップを作製して基材とし、この基材に被覆膜を形成して被覆切削工具を作製し、切削性能を調べた。この試験では、試験例1で用いた切削チップにおいて、刃先処理幅を変えた点以外の点は、試験例1と概ね同様としている(基材の組成:同様(両層の結合相量比y1/y2:1.0)、厚さh1:4.76mm、切刃部分の超硬合金層の厚さh2:50μm(h2/h1＝0.01)、ブレーカー部分の超硬合金層の厚さhb:100μm(h2/hb＝0.5)、超硬合金層のCr比:0.06、サーメット層のW及びWCの合計含有量:36.3質量％、サーメット層のCo割合:88.9質量％、超硬合金層のWC粒子の平均粒径:0.9μm)。 (Test Example 4)
In the same manner as in Test Example 1, a cutting tip having the same shape was prepared as a base material, a coating film was formed on the base material to prepare a coated cutting tool, and the cutting performance was examined. In this test, the cutting tip used in Test Example 1 is substantially the same as Test Example 1 except that the cutting edge processing width was changed (base material composition: same (bonded phase amount ratio y1 of both layers). /y2:1.0), thickness h1: 4.76 mm, the thickness of the cemented carbide layer at the cutting edge h2: 50 μm (h2 / h1 = 0.01), the thickness of the cemented carbide layer at the breaker portion hb: 100 μm (h2 /hb=0.5), Cr ratio of cemented carbide layer: 0.06, total content of W and WC in cermet layer: 36.3% by mass, Co ratio in cermet layer: 88.9% by mass, average of WC particles in cemented carbide layer Particle size: 0.9 μm).

得られた基材に、以下のようにして、PVD法(ここでは、アークイオンプレーティング法)により被覆膜を形成する。成膜装置のチャンバ内にアルゴンガスを導入して、チャンバ内の圧力を3.0Paに保持し、基材バイアス電圧を-1000Vとし、タングステン(W)フィラメントを利用して、基材表面のクリーニングを30分間行った後、チャンバ内からアルゴンガスを排気し、引き続いて成膜を行う。成膜は、基材温度を所定の温度とし、真空状態、或いは反応ガスとして窒素、メタン及び酸素のいずれか1種以上のガスを導入させながら、蒸発源とチャンバ間のアーク放電により、蒸発源からカソード物質を蒸発させて行う。この試験では、表8に示す組成の被覆膜(二層)を形成した。成膜条件は、基材温度:500℃、バイアス電圧:-100V、雰囲気の圧力:1.5Paとした。 A coating film is formed on the obtained substrate by the PVD method (here, arc ion plating method) as follows. Argon gas is introduced into the chamber of the deposition system, the pressure in the chamber is maintained at 3.0 Pa, the substrate bias voltage is -1000 V, and the substrate surface is cleaned using a tungsten (W) filament. After 30 minutes, the argon gas is evacuated from the chamber and film formation is subsequently performed. The film is formed by setting the substrate temperature to a predetermined temperature, in a vacuum state, or by introducing an arc discharge between the evaporation source and the chamber while introducing at least one of nitrogen, methane and oxygen as the reaction gas. To evaporate the cathode material. In this test, a coating film (two layers) having the composition shown in Table 8 was formed. The film forming conditions were as follows: substrate temperature: 500 ° C., bias voltage: −100 V, and atmospheric pressure: 1.5 Pa.

得られた被覆切削工具を用いて、表9に示す切削条件で切削試験(いずれも旋削加工)を行い、靭性(耐欠損性)及びワークのバリ状態を調べた。その結果を表10に示す。靭性の評価方法は、試験例1と同様である。ワークのバリ状態は、ワークに生じたバリの高さを測定し、バリの高さが1mm以下:○、1mm超1.5mm以下:△、1.5mm超:×として評価した。 Using the obtained coated cutting tool, a cutting test (both turned) was performed under the cutting conditions shown in Table 9, and the toughness (breakage resistance) and the burr state of the workpiece were examined. The results are shown in Table 10. The toughness evaluation method is the same as in Test Example 1. The burr state of the workpiece was evaluated by measuring the height of the burr generated on the workpiece and evaluating the burr height as 1 mm or less: ◯, 1 mm to 1.5 mm or less: Δ, 1.5 mm or more: ×.

表10に示すように、刃先処理を行うことで、靭性を向上できることが分かる。特に、刃先処理幅が0.05mm以下の小さな刃先処理によりシャープな刃先が得られたことで、バリの発生も抑制することができることが分かる。また、基材が超硬合金層を具えることで被覆膜との密着性に優れており、かつ0.05mm以下の刃先処理を行った基材にPVD膜を具えることで、上記靭性を向上できる上に、良好な加工精度を達成することができる。 As shown in Table 10, it can be seen that the toughness can be improved by performing the cutting edge treatment. In particular, it can be seen that the generation of burrs can be suppressed by obtaining a sharp cutting edge by a small cutting edge treatment with a cutting edge treatment width of 0.05 mm or less. In addition, since the base material has a cemented carbide layer, it has excellent adhesion to the coating film, and by providing a PVD film on the base material that has been subjected to a cutting edge treatment of 0.05 mm or less, the above toughness is achieved. In addition to improvement, good machining accuracy can be achieved.

(試験例5)
試験例1と同様にして同じ形状の切削工具(切削チップ)を作製し、切削性能を調べた。この試験では、試験例1で用いた工具に対して、超硬合金層におけるCrの含有量を変えた点以外の点は、試験例1と概ね同様としている(サーメット層の組成:試験例1と同様、厚さh1:4.76mm、切刃部分の超硬合金層の厚さh2:50μm(h2/h1＝0.01)、ブレーカー部分の超硬合金層の厚さhb:100μm(h2/hb＝0.5)、刃先処理幅:0.04mm、超硬合金層のWC粒子の平均粒径:0.9μm、サーメット層のW及びWCの合計含有量:36.3質量％、サーメット層のCo割合:88.9質量％)。原料に用いたCrの添加量を変化させることで、表12に示すように超硬合金層のCrの含有量を変化させた。原料のCrの添加量の増減した分に対して、原料のWCの添加量を増減させ、Coの含有量は一定にした(Co:10質量％)。また、基材の両層の結合相量比y1/y2を試験例1と同様にして調べたところ、いずれの試料もy1/y2:0.8〜1.2を満たしていた。 (Test Example 5)
A cutting tool (cutting tip) having the same shape was produced in the same manner as in Test Example 1, and the cutting performance was examined. In this test, the tool used in Test Example 1 is substantially the same as Test Example 1 except that the content of Cr in the cemented carbide layer is changed (the composition of the cermet layer: Test Example 1). Similar to, thickness h1: 4.76mm, cutting edge part cemented carbide layer thickness h2: 50μm (h2 / h1 = 0.01), breaker part cemented carbide layer thickness hb: 100μm (h2 / hb = 0.5), blade edge treatment width: 0.04 mm, average particle size of WC particles in cemented carbide layer: 0.9 μm, total content of W and WC in cermet layer: 36.3 mass%, Co ratio in cermet layer: 88.9 mass%) . By changing the amount of Cr used as the raw material, the Cr content of the cemented carbide layer was changed as shown in Table 12. The amount of WC added as a raw material was increased or decreased with respect to the amount of increase in the amount of Cr added as a raw material, and the Co content was kept constant (Co: 10% by mass). Further, when the binder phase amount ratio y1 / y2 of both layers of the substrate was examined in the same manner as in Test Example 1, all the samples satisfied y1 / y2: 0.8 to 1.2.

得られた切削工具を用いて、表11に示す切削条件で切削試験を行い、耐摩耗性及び靭性(耐欠損性)を調べた。その結果を表12に示す。耐摩耗性及び靭性の評価方法は、試験例3と同様である。表12において「x2/x1」は、超硬合金層中の結合相(Co)の含有量:x1(質量％)に対するCrの含有量:x2(質量％)の割合を示す。Cr量の測定は、EPMAで試験例1と同様にして行った。その結果を表12に示す。 Using the obtained cutting tool, a cutting test was performed under the cutting conditions shown in Table 11, and the wear resistance and toughness (breakage resistance) were examined. The results are shown in Table 12. The evaluation methods for wear resistance and toughness are the same as in Test Example 3. In Table 12, “x2 / x1” indicates the ratio of the content of Cr: x2 (mass%) to the content of the binder phase (Co) in the cemented carbide layer: x1 (mass%). The Cr amount was measured in the same manner as in Test Example 1 using EPMA. The results are shown in Table 12.

表12に示すように、超硬合金層中のCrの含有割合x2/x1が0.02以上0.2以下を満たすことで、WC粒子の粗大化による耐摩耗性の低下やCrの析出などによる耐欠損性の低下を抑制することができ、耐摩耗性及び靭性の双方に優れることが分かる。また、適量のCrを含有することで、液相移動による変形や性能の低下も抑制できたと考えられる。 As shown in Table 12, when the Cr content ratio x2 / x1 in the cemented carbide layer satisfies 0.02 or more and 0.2 or less, wear resistance decreases due to coarsening of WC particles, and fracture resistance due to Cr precipitation, etc. It can be seen that the decrease in the resistance can be suppressed, and both the wear resistance and the toughness are excellent. In addition, it is considered that deformation and deterioration of performance due to liquid phase transfer could be suppressed by containing an appropriate amount of Cr.

(試験例6)
サーメット層における結合相量(体積％)を一定として、超硬合金層における結合相量(体積％)を変化させた切削工具を作製し、焼結後における変形状態を調べた。ここでは、超硬合金層の厚さが均一的な二層構造で、表面が平面的な四角柱状のもの(図1(I)参照)、即ち、ブレーカーが無いものを作製した(厚さh1:4.76mm、切刃部分の超硬合金層の厚さh2:50μm(h2/h1＝0.01))。両層の結合相量を変えた点以外は試験例1と同様の原料粉末を用い、所定形状の金型に、サーメット用粉末、超硬合金用粉末を順に給粉した後、1.0t/cm²で押圧して作製した積層プレス成形体を試験例1と同様の条件で焼結して切削工具を得た。超硬合金層の結合相を増減した分に対して、WCを増減させた。なお、粉末の給粉順序は上記と逆でもよい。 (Test Example 6)
A cutting tool was produced in which the amount of binder phase (vol%) in the cemented carbide layer was changed while the amount of binder phase (vol%) in the cermet layer was constant, and the deformation state after sintering was examined. Here, a cemented carbide layer having a two-layer structure with a uniform thickness and a planar square columnar shape (see FIG. 1 (I)), i.e., without a breaker (thickness h1). : 4.76 mm, the thickness of the cemented carbide layer at the cutting edge h2: 50 μm (h2 / h1 = 0.01)). Except that the amount of the binder phase in both layers was changed, the same raw material powder as in Test Example 1 was used, and the powder for cermet and the powder for cemented carbide were sequentially fed to a mold with a predetermined shape, and then 1.0 t / cm ^The laminated press-formed body produced by pressing in ² was sintered under the same conditions as in Test Example 1 to obtain a cutting tool. The WC was increased or decreased with respect to the increased or decreased binder phase of the cemented carbide layer. Note that the powder feeding sequence may be reversed.

得られた切削工具に対して、超硬合金層とサーメット層との境界近傍の結合相量(体積％)を測定した。結合相量の測定は、工具の断面を顕微鏡観察し(500倍)、上記境界から超硬合金層の厚さh2の1/2の地点(25μm)をEPMAにてライン分析して行った。また、得られた切削工具の変形状態を評価した。変形状態は、各試料を超硬合金層が上方を向くように水平な台上に配置し、ハイトゲージで表面全体を測定し、この表面のうち、最も高い位置と最も低い位置の差(反りの度合い)を算出し、その差が0.1mm超を×、0.1mm以下を○と評価する。これらの結果を表13に示す。 For the obtained cutting tool, the amount of binder phase (% by volume) in the vicinity of the boundary between the cemented carbide layer and the cermet layer was measured. The amount of the binder phase was measured by observing a cross section of the tool with a microscope (500 times) and performing line analysis with EPMA at a point (25 μm) of the thickness h2 of the cemented carbide layer from the boundary. Moreover, the deformation state of the obtained cutting tool was evaluated. In the deformed state, each sample is placed on a horizontal table so that the cemented carbide layer faces upward, and the entire surface is measured with a height gauge, and the difference between the highest position and the lowest position (warpage of the surface) is measured. Degree) is evaluated as x when the difference is more than 0.1 mm, and ○ when the difference is 0.1 mm or less. These results are shown in Table 13.

表13に示すように、両層の結合相量の差が小さいほど、結合相の移動が少なく、変形が小さいことが分かる。 As shown in Table 13, it can be seen that the smaller the difference in the amount of the binder phase between the two layers, the less the movement of the binder phase and the smaller the deformation.

(試験例7)
試験例1と同様にして同じ形状の切削チップを作製して基材とし、この基材に試験例4と同様にして被覆膜(PVD膜)を形成して被覆切削工具を作製し、切削性能を調べた。この試験では、試験例1で用いた切削チップにおいて、超硬合金層に用いたWC粉末の大きさを変えた点以外の点は、試験例1と概ね同様としている(基材の組成:試験例1と同様(両層の結合相量比y1/y2:1.0)、厚さh1:4.76mm、切刃部分の超硬合金層の厚さh2:50μm(h2/h1＝0.01)、ブレーカー部分の超硬合金層の厚さhb:100μm(h2/hb＝0.5)、刃先処理幅:0.04mm、超硬合金層のCr比:0.06、サーメット層のW及びWCの合計含有量:36.3質量％、サーメット層のCo割合:88.9質量％)。 (Test Example 7)
As in Test Example 1, a cutting tip having the same shape was prepared as a base material, and a coated film (PVD film) was formed on the base material in the same manner as in Test Example 4 to produce a coated cutting tool, and cutting was performed. The performance was examined. In this test, the cutting tip used in Test Example 1 is substantially the same as Test Example 1 except that the size of the WC powder used in the cemented carbide layer was changed (Substrate composition: Test Same as Example 1 (Binder phase ratio y1 / y2: 1.0), thickness h1: 4.76 mm, cemented carbide layer thickness h2: 50 μm (h2 / h1 = 0.01), breaker part Cemented carbide layer thickness hb: 100μm (h2 / hb = 0.5), cutting edge treatment width: 0.04mm, Cr ratio of cemented carbide layer: 0.06, total content of W and WC in cermet layer: 36.3 mass% , Co ratio of cermet layer: 88.9% by mass).

得られた切削工具について、超硬合金層の平均粒径を調べた。その結果を表14に示す。また、得られた被覆切削工具を用いて、表6に示す切削条件で切削試験を行い、耐摩耗性及び靭性(耐欠損性)を調べた。その結果を表14に示す。平均粒径は、試験例1と同様にして測定した。耐摩耗性及び靭性の評価方法は、試験例3と同様である。 About the obtained cutting tool, the average particle diameter of the cemented carbide layer was investigated. The results are shown in Table 14. In addition, using the obtained coated cutting tool, a cutting test was performed under the cutting conditions shown in Table 6 to examine the wear resistance and toughness (breakage resistance). The results are shown in Table 14. The average particle size was measured in the same manner as in Test Example 1. The evaluation methods for wear resistance and toughness are the same as in Test Example 3.

表14に示すように超硬合金層中のWCの平均粒径が1.0μm以下と小さい試料は、耐摩耗性に優れることが分かる。かつ、これらの試料は、靭性にも優れることが分かる。これは、超硬合金層の微細なWC粒子に倣って、PVD膜における基材との境界近傍の結晶粒も微粒化し、基材とPVD膜との密着力を高めたことで靭性を向上できたと考えられる。 As shown in Table 14, it can be seen that a sample having a small average WC particle size of 1.0 μm or less in the cemented carbide layer is excellent in wear resistance. And it turns out that these samples are excellent also in toughness. This is because the fine WC particles in the cemented carbide layer are followed by the crystal grains near the boundary between the PVD film and the base material, and the adhesion between the base material and the PVD film is enhanced, improving toughness. It is thought.

(試験例8)
試験例1と同様にして同じ形状の切削工具(切削チップ)を作製し、切削性能を調べた。この試験では、試験例1で用いた工具に対して、サーメット層の組成を異ならせた点以外の点は、試験例1と概ね同様とし、超硬合金層の厚さが異なる試料を複数作製した。 (Test Example 8)
A cutting tool (cutting tip) having the same shape was produced in the same manner as in Test Example 1, and the cutting performance was examined. In this test, the sample used in Test Example 1 was the same as Test Example 1 except that the composition of the cermet layer was changed, and multiple samples with different cemented carbide layer thicknesses were prepared. did.

切削工具は、以下のように作製した。表15に示す組成となるように原料粉末を秤量し、試験例1と同様にして平均粒径100μmの造粒粉末を作製する。得られた超硬合金用粉末及びサーメット用粉末を用いて、試験例1と同様にして三層構造の積層プレス成形体を作製し、得られた成形体を真空雰囲気にて1480℃×60minの条件で焼結して図2に示す三層構造の複合材料を得る。得られた複合材料の角部において、試験例1と同様に刃先処理(刃先処理幅:0.04mm)を施して、試験例1と同様に四角柱状のブレーカー付き切削チップ(住友電気工業株式会社型番:SNMG120408N-UX)を得る。 The cutting tool was produced as follows. The raw material powder is weighed so as to have the composition shown in Table 15, and a granulated powder having an average particle diameter of 100 μm is prepared in the same manner as in Test Example 1. Using the obtained cemented carbide powder and cermet powder, a laminated press-molded body having a three-layer structure was prepared in the same manner as in Test Example 1, and the obtained molded body was 1480 ° C x 60 min in a vacuum atmosphere. The composite material having a three-layer structure shown in FIG. 2 is obtained by sintering under conditions. In the corner portion of the obtained composite material, the cutting edge treatment (blade edge treatment width: 0.04 mm) was applied in the same manner as in Test Example 1, and the cutting tip with a square column breaker (Sumitomo Electric Industries, Ltd. : SNMG120408N-UX).

焼結後、得られた切削工具について、サーメット層の組織をSEMで観察したところ、TiCNからなる芯部(黒芯)の周辺に(Ti,W,Mo,Ta,Nb)(C,N)からなる周辺部を有する有芯構造を持つ粒子が存在する組織であった。また、後述する厚さの測定に用いた観察像において、工具における超硬合金層とサーメット層との境界の形状を調べたところ、概ね外形(押圧パンチ)に沿った形状であるが、部分的にパンチの形状に沿わない微細な凹凸が見られる。また、切刃部分の超硬合金層の厚さは、概ね均一的である。 After sintering, for the obtained cutting tool, the structure of the cermet layer was observed by SEM, around the core part (black core) made of TiCN (Ti, W, Mo, Ta, Nb) (C, N) It was the structure | tissue in which the particle | grains with the core structure which have the peripheral part which consists of exist. In addition, in the observation image used for the thickness measurement described later, when the shape of the boundary between the cemented carbide layer and the cermet layer in the tool was examined, the shape was generally along the outer shape (press punch), but partially There are fine irregularities that do not follow the shape of the punch. Moreover, the thickness of the cemented carbide layer in the cutting edge portion is substantially uniform.

得られた各切削工具について、試験例1と同様にして、工具の積層方向における最大厚さh1を測定したところ、いずれの試料も4.76mmであった。また、各切削工具について、切刃部分における超硬合金層の最大厚さh2、ブレーカー部分における超硬合金層の最大厚さhbを試験例1と同様にして測定した。その結果を表16に示す。更に、試験例1と同様にして種々の特性を測定したところ、超硬合金層のWCの平均粒径:0.9μm、超硬合金層の結合相量y1:16.2体積％、サーメット層の結合相量y2:16.4体積％、y1/y2:1.0、サーメット層のW及びWCの合計量:32.6質量％である。 For each of the obtained cutting tools, the maximum thickness h1 in the tool stacking direction was measured in the same manner as in Test Example 1, and all the samples were 4.76 mm. For each cutting tool, the maximum thickness h2 of the cemented carbide layer at the cutting edge portion and the maximum thickness hb of the cemented carbide layer at the breaker portion were measured in the same manner as in Test Example 1. The results are shown in Table 16. Furthermore, when various properties were measured in the same manner as in Test Example 1, the average particle diameter of WC of the cemented carbide layer was 0.9 μm, the binder phase amount of the cemented carbide layer was y1: 16.2% by volume, and the binder phase of the cermet layer. The amount is y2: 16.4% by volume, y1 / y2: 1.0, and the total amount of W and WC in the cermet layer is 32.6% by mass.

得られた切削工具を用いて、表2に示す切削条件で靭性試験及び仕上げ加工試験(いずれも旋削加工)を行った。その結果を表16に示す。試験の評価方法は、試験例1と同様である。 Using the obtained cutting tool, a toughness test and a finishing test (both turned) were performed under the cutting conditions shown in Table 2. The results are shown in Table 16. The test evaluation method is the same as in Test Example 1.

表16に示すように、この試験例で作製した切削工具も、超硬合金層を具える試料は、サーメットのみからなる試料No.800と比較して、靭性に優れることが分かる。かつ、切刃部分の超硬合金層が100μm以下の薄い試料は、良好な仕上げ面光沢が得られることが分かる。特に、切刃部分の超硬合金層が10μm以上50μm以下の試料は、靭性及び仕上げ精度の双方に優れることが分かる。また、超硬合金層を具える試料はいずれも、超硬合金層が剥離することが無かった。 As shown in Table 16, it can be seen that also in the cutting tool produced in this test example, the sample including the cemented carbide layer is superior in toughness as compared with the sample No. 800 including only cermet. In addition, it can be seen that a thin sample having a cemented carbide layer of the cutting edge portion of 100 μm or less can obtain a good finished surface gloss. In particular, it can be seen that a sample having a cemented carbide layer of the cutting edge portion of 10 μm or more and 50 μm or less is excellent in both toughness and finishing accuracy. Moreover, the sample which provided the cemented carbide layer did not exfoliate the cemented carbide layer.

なお、上述した実施の形態は、本発明の要旨を逸脱することなく、適宜変更することが可能であり、上述した構成に限定されるものではない。例えば、超硬合金層及びサーメット層の組成や被覆膜の種類、成膜方法などを変更することができる。 The above-described embodiment can be appropriately changed without departing from the gist of the present invention, and is not limited to the above-described configuration. For example, the composition of the cemented carbide layer and the cermet layer, the type of coating film, the film forming method, and the like can be changed.

本発明切削工具は、耐衝撃性及び仕上げ面光沢に優れることが望まれる切削加工に好適に利用することができる。例えば、仕上げ加工に好適に使用することができる。 The cutting tool of the present invention can be suitably used for cutting work that is desired to be excellent in impact resistance and finished surface gloss. For example, it can be suitably used for finishing.

本発明切削工具の厚さ、超硬合金層の厚さ、刃先処理量の測定方法を説明する模式断面説明図であり、(I)は、二層構造の工具、(II)は三層構造の工具、(III)は、刃先部分の拡大図である。BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic cross-sectional explanatory view illustrating a method for measuring the thickness of a cutting tool of the present invention, the thickness of a cemented carbide layer, and the amount of cutting edge treatment, (I) is a two-layer structure tool, and (II) is a three-layer structure. (III) is an enlarged view of the cutting edge portion. 本発明切削工具の一例を示す模式断面図である。It is a schematic cross section which shows an example of this invention cutting tool.

Explanation of symbols

10 切削工具(基材) 11 超硬合金層 12 サーメット層 13 境界
14 取付穴 100 切削工具(基材) 100c 切刃部分 101 超硬合金層
101f 表面 102 サーメット層 103 境界 S 基準面
200 稜線 201 逃げ面 202 すくい面 203 交点 10 Cutting tool (base material) 11 Cemented carbide layer 12 Cermet layer 13 Boundary
14 Mounting hole 100 Cutting tool (base material) 100c Cutting edge part 101 Cemented carbide layer
101f Surface 102 Cermet layer 103 Boundary S Reference plane
200 Ridge line 201 Flank 202 Rake face 203 Intersection

Claims

Comprising a substrate in which a cemented carbide layer and a cermet layer are laminated,
The cemented carbide layer is disposed on at least a part of the rake face side connected to the cutting edge and the cutting edge of the base material,
The base material is h1 when the thickness of the portion with the largest thickness in the laminating direction is h1, and the thickness of the portion with the largest thickness in the laminating direction of the cemented carbide layer existing in the cutting edge portion is h2. Cutting tool characterized by / h1 satisfying 0.002 or more and 0.02 or less.

2. The cutting tool according to claim 1, wherein a thickness h2 of the cemented carbide layer is 10 μm or more and 100 μm or less.

2. The cutting tool according to claim 1, wherein a thickness h2 of the cemented carbide layer is 10 μm or more and 50 μm or less.

The cutting tool according to any one of claims 1 to 3, wherein the cermet layer contains WC and W in a total of 15 mass% or more and 65 mass% or less.

The cemented carbide layer includes a binder phase containing an iron group metal and Cr, and when the amount of the binder phase is x1 (mass%) and the content of Cr is x2 (mass%), x2 The cutting tool according to any one of claims 1 to 4, wherein / x1 satisfies 0.02 or more and 0.2 or less.

The cemented carbide layer and the cermet layer comprise a binder phase containing an iron group metal, the binder phase content of the cemented carbide layer is y1 (volume%), and the binder phase content of the cermet layer is y2 (volume). 6) The cutting tool according to any one of claims 1 to 5, wherein y1 / y2 satisfies 0.8 or more and 1.2 or less.

The substrate is
It is a polygonal column-shaped blade tip replaceable tip, and a cutting blade is formed at its corner,
A chip breaker is provided on the rake face connected to the cutting blade, and a cemented carbide layer is present in the breaker part,
The thickness of the cemented carbide layer of the portion most protruding from the rake face in the chip breaker is hb, h2 / hb is 0.5 or more and 1 or less, any one of claims 1 to 6, The cutting tool described in 1.

The cutting according to any one of claims 1 to 7, wherein the cermet layer includes a binder phase containing an iron group metal, and 80 mass% or more of the iron group metal in the binder phase is Co. tool.

The cutting tool further comprises a coating film formed on the substrate surface,
The cutting tool according to any one of claims 1 to 8, wherein the coating film is formed by a CVD method.

The cutting tool further comprises a coating film formed on the substrate surface,
The cutting tool according to any one of claims 1 to 8, wherein the coating film is formed by a PVD method.

11. The cutting tool according to claim 10, wherein in the base material, an average particle size of hard phase particles in the cemented carbide layer is 0.1 μm or more and 1.0 μm or less.

The cutting tool according to any one of claims 9 to 11, wherein the base material has a blade edge processing portion, and the blade edge processing width is 0.05 mm or less.