JP4865513B2 - Surface coated cutting tool - Google Patents

Description

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

A base material constituting a cutting tool has been coated with various coating layers for the purpose of protecting the surface and further improving various properties such as wear resistance and toughness. . Among them, a layer containing Al ₂ O ₃ has been widely used as a surface layer of a coating layer covering this type of substrate because it is chemically stable and hardly welds to the work material. .

However, since such a layer containing Al ₂ O ₃ usually has a black appearance color, it is difficult to identify the state of use of the blade edge. Therefore, from TiN or the like having a clear color on this layer. A further layer is formed. However, a layer made of TiN or the like having a clear color has a problem that it easily adheres to the work material, resulting in a decrease in wear resistance and a deterioration in the state of the work surface of the work material. It was.

  In general, as means for improving the wear resistance and the like of the coating layer, it has been proposed to increase the adhesion strength between the layers constituting the coating layer and the adhesion strength with the substrate (Patent Documents 1 to 4). In addition, optimization of such adhesion strength has been studied for certain types of applications (Patent Documents 5 to 8).

However, there is not yet provided a means for drastically solving the welding phenomenon of the layer made of TiN as described above.
JP 02-269509 A Japanese Patent Laid-Open No. 06-106402 Japanese Patent Laid-Open No. 06-108254 JP 07-216559 A JP 2005-103657 A JP 2005-186221 A Japanese Patent Laid-Open No. 2005-212046 JP 2005-212047 A

  This invention is made | formed in view of the above present conditions, The place made into the objective is providing the surface-coated cutting tool which reduced the problem that a workpiece material welds to a coating layer.

The surface-coated cutting tool of the present invention has a base material and a coating layer formed on the base material, and the coating layer is formed on one or more inner layers and the inner layer. The inner layer has a layer containing Al ₂ O ₃ having a thickness of 0.5 μm or more as an uppermost layer in contact with the outer layer, and the outer layer is the outermost layer of the inner layer. It includes an intermediate underlayer formed on the upper layer and an outermost layer constituting a surface having an adhesion strength of 20 N or less, and the intermediate underlayer is formed of TiC .

  The outermost layer is composed of at least one element selected from the group consisting of Ti, Zr, Cr, and Hf and at least one element selected from the group consisting of carbon, nitrogen, oxygen, and boron. It is preferable that the layer is formed of a compound.

  In addition to the uppermost layer, the inner layer includes at least one element selected from the group consisting of group IVa elements, group Va elements, group VIa elements, Al, Si, and B in the periodic table, carbon, It is preferable to include a layer formed of a compound composed of at least one element selected from the group consisting of nitrogen, oxygen and boron.

  The surface-coated cutting tool is any one of a drill, end mill, milling or turning cutting edge replacement cutting tip, metal saw, gear cutting tool, reamer, tap, or pin milling cutting edge replacement cutting tip. Preferably there is.

  The surface-coated cutting tool of the present invention has the above-described configuration, thereby reducing the problem that the work material is welded to the coating layer.

Hereinafter, the present invention will be described in more detail.
<Surface coated cutting tool>
The surface-coated cutting tool of the present invention has a base material and a coating layer formed on the base material. The surface-coated cutting tool of the present invention having such a basic configuration is, for example, a drill (including both a blade-tip-exchangeable drill having a blade-tip-exchangeable cutting tip and a solid drill. Unless otherwise specified, includes both tip changeable and solid types))), end mills, milling or turning cutting tips, metal saws, gear cutting tools, reamers, taps, or It is extremely useful as a cutting edge exchangeable cutting tip for pin milling.

<Base material>
As the base material of the surface-coated cutting tool of the present invention, a conventionally known material known as such a cutting tool base material can be used without particular limitation. For example, cemented carbide (for example, WC-based cemented carbide, WC, Co and / or Ni, or further carbide, nitride, carbonitride such as Ti, Ta, Nb, Zr, Hf, Cr, V) Etc.), cermets (those mainly composed of TiC, TiN, TiCN, etc.), high speed steel, ceramics (titanium carbide, silicon carbide, silicon nitride, aluminum nitride, aluminum oxide, and mixtures thereof) Etc.), cubic boron nitride sintered bodies, diamond sintered bodies, silicon nitride sintered bodies, and the like can be given as examples of such base materials. When a cemented carbide is used as such a base material, the effect of the present invention is exhibited even if such a cemented carbide contains an abnormal phase called free carbon or ε phase in the structure.

  In addition, these base materials may have a modified surface. For example, in the case of cemented carbide, a de-β layer may be formed on the surface, or in the case of cermet, a surface hardened layer may be formed, and even if the surface is modified in this way, The effect is shown.

<Coating layer>
The coating layer of the present invention is formed on a substrate and has an effect of improving properties such as toughness and wear resistance. Such a coating layer is preferably formed so as to cover the entire surface of the substrate, but even if a portion where the coating layer is not formed is included on the substrate, it deviates from the scope of the present invention. is not.

  Such a covering layer includes an inner layer composed of one or more layers and an outer layer composed of one or more layers formed on the inner layer. In addition, such a coating layer can also be formed by a conventionally well-known chemical vapor deposition (CVD) method, and can also be formed by a physical vapor deposition (PVD) method, The formation method is not specifically limited.

  Such a coating layer preferably has a thickness of 0.6 μm or more and 50 μm or less, more preferably an upper limit of 30 μm, still more preferably 20 μm, and a lower limit of 0.7 μm, still more preferably 1.0 μm. If the thickness is less than 0.6 μm, the effect of improving the durability of the blade-tip-exchangeable cutting tip may not be sufficiently exhibited, and if it exceeds 50 μm, there may be no significant difference in the effect and may be economically disadvantageous.

<Inner layer>
The inner layer of the present invention is a layer formed on the substrate side with respect to an outer layer described later, and is composed of one or more layers. Therefore, the layer formed closest to the base material among the inner layers is formed so as to be in direct contact with the base material.

Such an inner layer needs to have a layer containing Al ₂ O ₃ having a thickness of 0.5 μm or more as the uppermost layer in contact with the outer layer. As will be described later, since the outer layer has a characteristic of being easily peeled off during cutting, it is the uppermost layer of this inner layer that is exposed to the surface during cutting, and this uppermost layer includes Al ₂ O ₃ . It becomes possible to reduce the weldability with respect to a work material by comprising in a layer.

Here, the layer containing Al ₂ O ₃ means that at least Al ₂ O ₃ is included as a part of the layer (if 50% by mass or more is included, it is considered that Al ₂ O ₃ is included). Meaning, it may contain ZrO ₂ , Y ₂ O ₃ (it can be considered that Zr or Y is added to Al ₂ O ₃ ), etc., and may contain chlorine, carbon, boron, nitrogen or the like. . On the other hand, the layer containing Al ₂ O ₃ includes a case where the entire composition excluding inevitable impurities is Al ₂ O ₃ . Incidentally, Al ₂ O ₃ is the crystal structure is not particularly limited, for example, _{α-Al 2 O 3, κ} -Al 2 O 3, with include γ-Al ₂ O ₃ or Al ₂ O ₃ in the amorphous state The state where these are mixed is also included.

Further, such a layer containing Al ₂ O ₃ needs to have a thickness of 0.5 μm or more. If it is less than 0.5 μm, the weldability cannot be sufficiently reduced. Preferably, it is 1.0 μm or more, more preferably 1.5 μm or more. On the other hand, the upper limit of the thickness is not particularly limited, but even if it exceeds 20 μm, there is a case where it is economically unfavorable with the above-mentioned action being not greatly different.

Furthermore, in addition to the uppermost layer (a layer containing Al ₂ O ₃ ), such an inner layer includes an IVa group element (Ti, Zr, Hf, etc.) and a Va group element (V, Nb, Ta, etc.) in the periodic table of elements. At least one element selected from the group consisting of Group VIa elements (Cr, Mo, W, etc.), Al, Si, and B, and at least one element selected from the group consisting of carbon, nitrogen, oxygen, and boron It is preferable to include one or more layers formed of a compound constituted by: By including such a layer, various properties such as wear resistance can be improved, and adhesion between the inner layer and the substrate can be improved.

Here, specific examples of the above compounds include TiC, TiN, TiCN, TiCNO, TiB ₂ , TiBN, TiBNO, TiCBN, Ti ₂ O ₃ , TiZrCN, ZrC, ZrO ₂ , HfC, HfN, TiAlN, AlCrN, Examples thereof include CrN, VN, TiSiN, TiSiCN, AlTiCrN, TiAlCN, Al ₂ O ₃ , ZrCN, ZrCNO, AlN, AlCN, ZrN, and TiAlC.

  In the present invention, when the compound is represented by the chemical formula as described above, it is assumed that all the conventionally known atomic ratios are included unless the atomic ratio is particularly limited, and are not necessarily limited to those in the stoichiometric range. . For example, when simply describing “TiCN”, the atomic ratio of “Ti”, “C”, and “N” is not limited to 50:25:25, and also when “TiN” is described, “Ti” and “N” The atomic ratio is not limited to 50:50. These atomic ratios include all conventionally known atomic ratios.

<Outer layer>
The outer layer of the present invention is one or more layers formed on the inner layer, and includes a layer having an adhesion strength of 20 N or less as the outermost layer constituting the surface of the surface-coated cutting tool (coating layer). To do. By forming such an outer layer (that is, the outermost layer), it is extremely effective that the work material is welded to the surface of the surface-coated cutting tool even though it is easy to identify the usage state of the cutting edge. Can be reduced.

That is, the layer containing Al ₂ O ₃ which is the uppermost layer of the inner layer exhibits an appearance color of black (or a dark color close to black), and by forming a layer different from this as the outermost layer, Since the outermost layer constitutes the surface, it is possible to easily identify whether the cutting edge has been used or not, and since the outermost layer is peeled off when the cutting is started, the outermost layer and the work material Can be prevented from welding. When the welding of the work material is prevented in this way, as a result, the coating layer (inner layer) is prevented from being destroyed, and thus excellent wear resistance can be obtained. At the same time, it is possible to prevent the state of the processed surface of the work material from being deteriorated.

In order to easily peel the outermost layer in this way, it is necessary to make its adhesion strength 20 N or less. Here, the adhesion strength referred to in the present invention refers to adhesion strength measured by a scratch test (details of test conditions are described in Examples described later).

  Such adhesion strength is preferably as small as possible, and it is not necessary to set the lower limit. The standard of the lower limit can be defined as that of which the outermost layer does not self-peel after film formation, depending on the type of compound constituting the outermost layer, the shape of the substrate, and the like.

  The outer layer of the present invention can include only the outermost layer as described above (in other words, the outer layer includes only the outermost layer), and can also include the outermost layer and the intermediate underlayer. In the above scratch test, peeling of the outermost layer is measured. When an intermediate underlayer is formed, such an intermediate underlayer (all or a part thereof) is peeled off together with the outermost layer. Even in this case, this is regarded as peeling of the outermost layer, and the adhesion strength measured thereby is defined as the adhesion strength of the outermost layer. Of course, only the outermost layer may be peeled off, and this intermediate underlayer (or part of the intermediate underlayer) may be held on the inner layer. However, such an intermediate underlayer is preferably peeled off at the start of cutting during actual cutting. This is to prevent welding of the work material.

In principle, the composition of the outermost layer of the present invention is not particularly limited as long as it is a layer having a composition other than the layer containing Al ₂ O ₃ which is the uppermost layer of the inner layer. In particular, the outermost layer is composed of at least one element selected from the group consisting of Ti, Zr, Cr, and Hf and at least one element selected from the group consisting of carbon, nitrogen, oxygen, and boron. It is preferably a layer formed by the compound that is constituted. These compounds have a color such as a gold color, and can express a clear color contrast with a layer containing Al ₂ O ₃ that exhibits a black appearance color. This is because the state of use of the blade edge can be easily identified by peeling or discoloring. Examples of such compounds include TiN, TiCN, TiBN, TiCNO, TiZrN, TiZrCrN, ZrN, ZrCN, TiC, CrN, CrCN, ZrC, HfN, HfCN, and HfC.

The outermost layer of the present invention can be formed by a conventionally known chemical vapor deposition method as described above, or can be formed by a physical vapor deposition method, and the formation method is not particularly limited. Then, the adhesion strength can be controlled to 20 N or less by appropriately adjusting the thickness, formation conditions, and various conditions such as formation of the intermediate base layer.

  Such an outermost layer preferably has a thickness of 0.01 μm or more and 20 μm or less, more preferably an upper limit of 10 μm, further preferably 5 μm, and a lower limit of 0.1 μm, still more preferably 0.2 μm. If it is less than 0.01 μm, the use state of the surface-coated cutting tool may not be sufficiently identified, and if it exceeds 20 μm, there is a case where it is economically disadvantageous with no significant difference in the action.

The intermediate base layer is formed as a lower layer of the outermost layer, and has a function of adjusting the adhesion strength of the outermost layer. Such an intermediate underlayer is not particularly limited in composition, but, like the outermost layer, at least one element selected from the group consisting of Ti, Zr, Cr, and Hf, and carbon, nitrogen, A layer formed of a compound composed of at least one element selected from the group consisting of oxygen and boron is preferable. Examples of such compounds include TiC, ZrC, ZrCN, TiCN, TiN, TiBN, TiCNO, Ti ₂ O ₃ and TiCO.

Further, the intermediate underlayer includes the layer containing Al ₂ O ₃ described as the uppermost layer of the inner layer and other layers (for example, group IVa element, group Va element, group VIa element, Al, Si, And a layer formed of a compound composed of at least one element selected from the group consisting of B and B and at least one element selected from the group consisting of carbon, nitrogen, oxygen and boron) It can also be set as the layer of the laminated structure above. Thereby, the adhesion strength of the outermost layer can be further effectively reduced, and the outermost layer can be peeled off very easily during the cutting process. In addition, when several layers are laminated | stacked as mentioned above, the lamination | stacking number (cycle number) is although it does not specifically limit, It is preferable to set it as several to several dozen layers.

  Such an intermediate underlayer (including a case where a plurality of layers are laminated) can be formed by a conventionally known chemical vapor deposition method as described above, or by a physical vapor deposition method. The formation method is not particularly limited. The thickness is preferably 0.01 μm or more and 30 μm or less, more preferably the upper limit is 25 μm, still more preferably 20 μm, and the lower limit is 0.1 μm, more preferably 1 μm. When the thickness is less than 0.01 μm, the above-described effects may not be exhibited.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated in detail, this invention is not limited to these.

  In the following, each layer constituting the coating layer (inner layer and outer layer) is formed by a CVD method unless otherwise specified, and the conditions are as shown in Table 1 below.

  In Table 1, “mixed gas composition” is the composition of the gas used when forming a layer by CVD, and “temperature” and “pressure” indicate the temperature and pressure at that time.

In Table 1, “TiN (lowermost layer)” refers to a TiN layer (a layer composed of TiN, which is directly in contact with the base material unless otherwise specified). The term “TiN (other than the lowest layer)” refers to the condition for forming the TiN layer at the other laminated position. MT-TiCN refers to a case where a TiCN layer (hereinafter simply referred to as MT-TiCN layer) is formed at a relatively low film formation temperature (medium temperature CVD method). κ-Al ₂ O ₃ is a condition for forming a layer composed of Al ₂ O ₃ having a κ-type crystal structure (hereinafter simply referred to as κ-Al ₂ O ₃ layer), and α-Al ₂ O ₃ Indicates a condition for forming a layer composed of Al ₂ O ₃ having an α-type crystal structure (hereinafter simply referred to as an α-Al ₂ O ₃ layer).

<Example 1>
First, cemented carbide powder having a composition of 2% by mass of TiC, 2% by mass of TaC, 1% by mass of NbC, 5% by mass of Co, and the balance of WC is pressed, followed by 1450 in a vacuum atmosphere. Sintering is performed at 1 ° C. for 1 hour, and then the edge of the edge of the edge is treated by SiC brush honing (the radius (R) is about 0.05 mm for each intersection of the rake face and the flank face. ) To obtain a base material made of cemented carbide having the same shape as the shape of the cutting edge replaceable cutting tip CNMA1204112 (JIS B 4120-1998). It should be noted that a β-free layer was not formed on the surface of this substrate.

Next, a 0.3 μm TiN layer, 10.0 μm MT-TiCN layer, 0.3 μm TiBN layer, and 8.0 μm α are formed as the inner layer in order from the surface side of the substrate with respect to the entire surface of the substrate. -Al ₂ O ₃ layers (the uppermost layer in contact with the outer layer described later) were formed.

Further, the outer layer formation conditions described in Table 2 below as the outer layer (for example, “TiC / 15 minutes” of No. 101 means that after the inner layer is formed, the conditions of Table 1 for continuously forming TiC are continued for 15 minutes. , Indicates that each outermost layer was formed under the conditions shown in Table 1. In other examples, it was agreed that blanks indicate that the outermost layer was formed directly after the inner layer was formed.) (Thickness: 0.3 μm) was formed on the entire surface of the α-Al ₂ O ₃ layer (that is, the outermost layer described in Table 2 was formed on each of the plurality of base materials on which the inner layer was formed as described above. Formed). The inner layer and the outer layer were formed continuously without taking out the substrate from the same CVD apparatus.

  In this way, a surface-coated cutting tool shown in Table 2 having a base material and a coating layer formed on the base material was obtained. In Table 2, No. 101-108 surface-coated cutting tools are examples of the present invention. 109 to 116 surface-coated cutting tools are comparative examples.

In the surface-coated cutting tools of these embodiments, the coating layer includes an inner layer composed of one or more layers and an outer layer formed on the inner layer, and the inner layer has a thickness of 0 as an uppermost layer in contact with the outer layer. a layer containing Al ₂ O ₃ of more than .5Myuemu, outer layer is the outermost layer constituting the surface had the adhesion strength shown in Table 2.

The adhesion strength shown in Table 2 was calculated by a scratch test under the following conditions. Moreover, when the cross section of the coating layer was wrapped and observed with an optical microscope (magnification: 1000 times), the outer layer (that is, the layer containing Al ₂ O ₃ which is the uppermost layer of the inner layer (that is, α-Al ₂ O ₃ layer)) Only the outermost layer shown in Table 2 was observed.

<Scratch test>
Scratch testing machine: CEM-REVETEST (manufactured by Nanotech)
Table speed: 0.17 mm / second Load speed: 100 N / divider (diamond) Curvature radius: 0.2 mm
Indenter (diamond) ridge angle: 120 °
Specific measurement conditions: The position where the outermost layer peeled was detected with an optical microscope and an acoustic emission sensor, and the adhesion strength was measured from the distance between the peeled position and the position where the load was started.

  Then, the blade-tip-exchangeable cutting tip, which is a surface-coated cutting tool obtained as described above, was attached to a holder attached to a collet of a machine tool, and a cutting test was performed under the following conditions.

<Cutting conditions>
Holder: PCLNR2525-43 (manufactured by Sumitomo Electric Hardmetal Corp.)
Work material: FCD450 round bar (diameter: 250mm, HB = 240)
Cutting speed: 280 m / min Feed: 0.40 mm / rev.
Cutting depth: 1.5mm
Dry / Wet: Dry cutting time: 15 minutes Then, the state of the cutting edge of each cutting edge replaceable cutting tip (presence of welding of the work material) was observed and the flank average wear amount (VB) was measured. The results are shown in Table 2 below. In observation of the state of the cutting edge, the machined surface of the work material was more beautiful as the work material was less welded. Also, the smaller the flank average wear amount, the better the wear resistance.

As is apparent from Table 2, the surface-coated cutting tool of the example of the present invention has reduced welding of the work material to the coating layer of the blade edge as compared with the surface-coated cutting tool of the comparative example, and wear resistance It was excellent. Therefore, it was confirmed that the surface-coated cutting tool having the configuration of the present invention has an excellent effect. On the other hand, in the surface-coated cutting tool of the comparative example, the reason why the work material is welded in large amounts on the cutting edge and the wear resistance is inferior is that the adhesion strength of the outermost layer exceeds 20 N.

<Example 2>
First, the following two types were prepared as base materials. That is, one type was used for a continuous cutting test described later, and was produced as follows.

  First, cemented carbide powder having a composition of 3% by mass of TiC, 2% by mass of TaC, 0.5% by mass of NbC, 8% by mass of Co, and the balance of WC is pressed, and subsequently in a vacuum atmosphere Sintering is performed at 1420 ° C. for 1 hour, and then the edge of the blade edge is processed by SiC brush honing (the radius of about 0.05 mm for each intersection of the rake face and the flank face) By applying (R), a cemented carbide base material having the same shape as that of the cutting edge replaceable cutting tip CNMA1204112 (JIS B 4120-1998) was obtained. A 13 μm de-β layer was formed on the surface of the substrate.

  The other type was used for the intermittent cutting test described later, and was produced as follows. That is, first, a cemented carbide powder having a composition of 8% by mass of TaC, 2% by mass of TiC, 10% by mass of Co, and the balance of WC is pressed, followed by 1380 ° C. for 1 hour in a vacuum atmosphere Sintering was performed under the conditions, and then the edge of the edge of the edge was treated by SiC brush honing treatment (R (R) with a radius of about 0.05 mm was applied to each intersection of the rake face and the flank face) ) To obtain a base material made of cemented carbide having the same shape as the shape of the cutting edge replaceable cutting tip SEMT13T3AGSN-N (manufactured by Sumitomo Electric Hardmetal Co., Ltd.). It should be noted that a β-free layer was not formed on the surface of this substrate.

Then, with respect to the entire surface of each of the two types of base materials, in order from the surface side of the base material, a 0.4 μm TiN layer, a 6.0 μm MT-TiCN layer, a 0.3 μm TiBN layer, and 1 κ-Al ₂ O ₃ layer of .5μm to (a top layer in contact with the outer layer described later) were formed.

Further, as the outer layer, the outer layer forming conditions (thickness 0.4 μm) described in Table 3 are applied on the entire surface of the κ-Al ₂ O ₃ layer under the outer layer forming conditions described in Table 3 below. (That is, the outermost layer shown in Table 3 was formed on each of the plurality of base materials on which the inner layer was formed as described above). The inner layer and the outer layer were formed continuously without taking out the substrate from the same CVD apparatus.

Thus, the surface-coated cutting tool shown in Table 3 having a base material and a coating layer formed on the base material was obtained for each of the two types of base materials described above. In Table 3, No. Nos. 201 to 208 are examples of the present invention (however, those marked with “*” are reference examples) . The surface-coated cutting tools 209 to 216 are comparative examples.

In the surface-coated cutting tools of these embodiments, the coating layer includes an inner layer composed of one or more layers and an outer layer formed on the inner layer, and the inner layer has a thickness of 0 as an uppermost layer in contact with the outer layer. a layer containing Al ₂ O ₃ of more than .5Myuemu, outer layer is the outermost layer constituting the surface had the adhesion strength shown in Table 3.

The adhesion strength described in Table 3 was calculated in the same manner as in Example 1. Moreover, when the cross section of the coating layer was wrapped and observed with an optical microscope (magnification: 1000 times), the outer layer (that is, the layer containing Al ₂ O ₃ which is the uppermost layer of the inner layer (ie, κ-Al ₂ O ₃ layer)) Only the outermost layer shown in Table 3 was observed.

  Then, each one of the edge-replaceable cutting tips, which are surface-coated cutting tools obtained as described above, is attached to a holder or a cutter attached to a collet of a machine tool, and the following conditions are set for each base material. A cutting test was performed.

<Continuous cutting test>
Chip: CNMA120204
Holder: PCLNR2525-43 (manufactured by Sumitomo Electric Hardmetal Corp.)
Work material: SCM435 round bar (diameter: 250mm, HB = 270)
Cutting speed: 280 m / min Feed: 0.40 mm / rev.
Cutting depth: 2.0mm
Dry / Wet: Wet (water-soluble oil)
Cutting time: 10 minutes <Intermittent cutting test>
Chip: SEMT13T3AGSN-N
Cutter: WGC4100R (manufactured by Sumitomo Electric Hard Metal Co., Ltd.)
Work material: SCM440 block material (HB = 300)
Cutting speed: 250 m / min Feed: 0.30 mm / Blade cutting: 2.0 mm
Dry / Wet: Wet (water-soluble oil)
Cutting distance: 5m
Then, the state of the cutting edge of each cutting edge replaceable cutting tip (presence / absence of welding of the work material) was observed and the flank average wear amount (VB) was measured. The results are shown in Table 3 below. In observation of the state of the cutting edge, the machined surface of the work material was more beautiful as the work material was less welded. Also, the smaller the flank average wear amount, the better the wear resistance.

  As is apparent from Table 3, the surface-coated cutting tool of the example of the present invention has reduced welding of the work material to the coating layer of the blade edge as compared with the surface-coated cutting tool of the comparative example, and wear resistance It was excellent. Therefore, it was confirmed that the surface-coated cutting tool having the configuration of the present invention has an excellent effect.

<Example 3>
First, a cemented carbide powder having a composition of 2% by mass of TaC, 9% by mass of Co, and the balance of WC is pressed, followed by sintering in a vacuum atmosphere at 1400 ° C. for 1 hour. Thereafter, the edge of the edge of the edge is treated by SiC brush honing (with a radius (R) having a radius of about 0.03 mm for each of the intersections of the rake face and the flank face). A base material made of cemented carbide having the same shape as that of the exchangeable cutting tip TNMG160404R-HM (manufactured by Sumitomo Electric Hardmetal Co., Ltd.) was obtained. It should be noted that a β-free layer was not formed on the surface of this substrate.

Subsequently, with respect to the entire surface of the base material, in order from the surface side of the base material, as an inner layer, a 0.3 μm TiN layer, a 4.0 μm MT-TiCN layer, a 0.4 μm TiBN layer, and a 2.0 μm α -Al ₂ O ₃ layers (the uppermost layer in contact with the outer layer described later) were formed.

Further, as the outer layer, the outer layer forming conditions (thickness 0.4 μm) described in Table 4 are applied on the entire surface of the α-Al ₂ O ₃ layer under the outer layer forming conditions described in Table 4 below (the description regarding the conditions is the same as Table 2). (That is, the outermost layer shown in Table 4 was formed on each of the plurality of base materials on which the inner layer was formed as described above). The inner layer and the outer layer were formed continuously without taking out the substrate from the same CVD apparatus.

In this way, a surface-coated cutting tool shown in Table 4 having a base material and a coating layer formed on the base material was obtained. In Table 4, No. Nos. 301 to 305 are examples of the present invention (however, those marked with “*” are reference examples) . Surface-coated cutting tools 306 to 308 are comparative examples.

In the surface-coated cutting tools of these embodiments, the coating layer includes an inner layer composed of one or more layers and an outer layer formed on the inner layer, and the inner layer has a thickness of 0 as an uppermost layer in contact with the outer layer. a layer containing Al ₂ O ₃ of more than .5Myuemu, outer layer is the outermost layer constituting the surface had the adhesion strength shown in Table 4.

The adhesion strength described in Table 4 was calculated in the same manner as in Example 1. Moreover, when the cross section of the coating layer was wrapped and observed with an optical microscope (magnification: 1000 times), the outer layer (that is, the layer containing Al ₂ O ₃ which is the uppermost layer of the inner layer (that is, α-Al ₂ O ₃ layer)) Only the outermost layer described in Table 4 was observed.

  Then, the blade-tip-exchangeable cutting tip, which is a surface-coated cutting tool obtained as described above, was attached to a holder attached to a collet of a machine tool, and a cutting test was performed under the following conditions.

<Cutting conditions>
Holder: PTGNR2525-43 (Sumitomo Electric Hardmetal Co., Ltd.)
Work material: SUS304 round bar (diameter: 250mm)
Cutting speed: 150 m / min Feed: 0.25 mm / rev.
Cutting depth: 2.0mm
Dry / Wet: Wet (water-soluble oil)
Cutting time: 5 minutes And the state of the cutting edge of each cutting edge replaceable cutting tip (the presence or absence of welding of the work material) was observed, and the average flank wear (VB) was measured. The results are shown in Table 4 below. In the observation of the state of the cutting edge, the fewer the burrs were, the smaller the welded material and the boundary defect. Also, the smaller the flank average wear amount, the better the wear resistance.

  As is apparent from Table 4, the surface-coated cutting tool of the example of the present invention has reduced welding of the work material to the coating layer of the blade edge as compared with the surface-coated cutting tool of the comparative example, and wear resistance It was excellent. Therefore, it was confirmed that the surface-coated cutting tool having the configuration of the present invention has an excellent effect.

<Example 4>
No. of Example 1 101 and no. In the surface-coated cutting tool No. 102, surface-coated cutting tools were obtained in the same manner except that the thickness of the outermost layer was set to the thickness described in Table 5 below (No. 101-2 to No. 101). -5 indicates that it corresponds to No. 101, and No. 102-2 to No. 102-5 indicate that it corresponds to No. 102).

For these surface-coated cutting tools, the adhesion strength of the outermost layer was measured in the same manner as in Example 1, and the same cutting test as in Example 1 was performed. The results are shown in Table 5 below. No. Surface-coated cutting tools 101, 101-2, 101-3, 102, 102-2, and 102-3 are examples of the present invention. In addition, when the cross section of the coating layer of each surface coating cutting tool is lapped and observed with an optical microscope (magnification: 1000 times), it is formed on the outer layer (that is, the layer containing Al ₂ O ₃ which is the uppermost layer of the inner layer). As in Example 1, only the outermost layer was observed as the layer).

  As is clear from Table 5, the surface-coated cutting tool of the example of the present invention has reduced welding of the work material to the coating layer of the blade edge as compared with the surface-coated cutting tool of the comparative example, and wear resistance It was excellent. Therefore, it was confirmed that the surface-coated cutting tool having the configuration of the present invention has an excellent effect.

<Example 5>
First, the following two types were prepared as base materials. That is, one type was used for a continuous cutting test described later, and was produced as follows.

  First, cemented carbide powder having a composition of 3% by mass of TiC, 4% by mass of TaC, 0.5% by mass of NbC, 10% by mass of Co, and the balance of WC is pressed, and subsequently in a vacuum atmosphere Sintering is performed at 1420 ° C. for 1 hour, and then the edge of the blade edge is processed by SiC brush honing (the radius of about 0.05 mm for each intersection of the rake face and the flank face) By applying (R), a cemented carbide base material having the same shape as that of the cutting edge replaceable cutting tip CNMA120404 (JIS B 4120-1998) was obtained. It should be noted that a β-free layer was not formed on the surface of this substrate.

The other type was used for the intermittent cutting test described later, and was produced as follows. That is, first, a cemented carbide powder having a composition of 0.5% by mass of Cr ₃ C ₂ , 10% by mass of Co, and the balance of WC is pressed, followed by conditions of 1380 ° C. for 1 hour in a vacuum atmosphere. Sintering is then performed, and then the edge of the edge of the edge is treated by SiC brush honing (with a radius (R) of about 0.05 mm applied to each intersection of the rake face and flank face) As a result, a cemented carbide base material having the same shape as the shape of the cutting edge-exchangeable cutting tip SEET13T3AGSN-N (manufactured by Sumitomo Electric Hardmetal Co., Ltd.) was obtained. It should be noted that a β-free layer was not formed on the surface of this substrate.

Next, with respect to the entire surface of each of the two types of base materials, in order from the surface side of the base material, an inner layer of 0.5 μm TiN layer, 3.0 μm MT-TiCN layer, 0.3 μm TiBN layer, and 2 α-Al ₂ O ₃ layer of .5μm to (a top layer in contact with the outer layer described later) were formed.

Further, the conditions described in Table 6 below as the outer layer on the entire surface of the α-Al ₂ O ₃ layer (the description in Table 6 conforms to Table 1. However, “time” means the duration of vapor deposition by the CVD method) The TiN layer having a thickness of 0.4 μm was formed as the outermost layer (i.e., for each of the substrates on which the inner layer was formed as described above). After the vapor deposition was performed, a TiN layer having a thickness of 0.4 μm was formed as the outermost layer). The inner layer and the outer layer were formed continuously without taking out the substrate from the same CVD apparatus.

In this manner, a surface-coated cutting tool having a base material and a coating layer formed on the base material was obtained for each of the above two types of base materials. In Table 6, no. The surface-coated cutting tools Nos. 501 to 508 are examples of the present invention (however, those marked with “*” are reference examples) . The surface-coated cutting tools 509 to 514 are comparative examples.

In the surface-coated cutting tools of these embodiments, the coating layer includes an inner layer composed of one or more layers and an outer layer formed on the inner layer, and the inner layer has a thickness of 0 as an uppermost layer in contact with the outer layer. It has a layer containing Al ₂ O ₃ of 0.5 μm or more, and the outer layer had the adhesion strength shown in Table 7 below as the outermost layer constituting the surface.

The adhesion strength described in Table 7 was calculated in the same manner as in Example 1. Moreover, when the cross section of the coating layer was wrapped and observed with an optical microscope (magnification: 1000 times), No. In 504, 505, 506, 507, 508, 513, and 514, an intermediate base layer is formed between the α-Al ₂ O ₃ layer, which is the uppermost layer of the inner layer, and the outermost layer (No. 504 and 505 TiC layer, the other No. is Ti ₂ O against _3-layer) of was observed, alpha-Al ₂ which is the uppermost layer layer (i.e. inner layer of the surface-coated cutting tool of the rest As a layer formed on the O ₃ layer, only a 0.4 μm TiN layer was observed as the outermost layer.

  Then, the blade-tip-exchangeable cutting tip, which is a surface-coated cutting tool obtained as described above, is attached to a holder or cutter attached to a collet of a machine tool, and a cutting test is performed for each base material under the following conditions. It was.

<Continuous cutting test>
Chip: CNMA120404
Holder: PCLNR2525-43 (manufactured by Sumitomo Electric Hardmetal Corp.)
Work material: SUS316 round bar (diameter: 250mm)
Cutting speed: 150 m / min Feed: 0.25 mm / rev.
Cutting depth: 1.2mm
Dry / Wet: Wet (water-soluble oil)
Cutting time: 20 minutes <Intermittent cutting test>
Chip: SEET13T3AGSN-N
Cutter: WGC4100R (manufactured by Sumitomo Electric Hard Metal Co., Ltd.)
Work material: FCD450 block material Cutting speed: 150 m / min Feed: 0.30 mm / blade cutting: 2.0 mm
Dry / Wet: Dry cutting distance: 4.5m
Then, the state of the cutting edge of each cutting edge replaceable cutting tip (the presence or absence of welding of the work material) is observed, and the wear amount (boundary wear amount (VN) (measured from the flank) for continuous cutting test), and intermittent cutting test is escaped Surface average wear amount (VB)) was measured. The results are shown in Table 7 below. In the observation of the state of the cutting edge, the machined surface of the work material was more beautiful as the work material was less welded (the less welded, the smaller the defect in the boundary, and the larger the weld, the larger the defect in the boundary. In the intermittent cutting test, chipping did not occur for those with little welding, but there were cases where chipping occurred or chipped when welding increased. Also, the smaller the flank average wear amount, the better the wear resistance.

  As is apparent from Table 7, the surface-coated cutting tool of the example of the present invention has reduced welding of the work material to the coating layer of the blade edge as compared with the surface-coated cutting tool of the comparative example, and wear resistance It was excellent. Therefore, it was confirmed that the surface-coated cutting tool having the configuration of the present invention has an excellent effect.

  In the surface-coated cutting tool according to the embodiment of the present invention, the present embodiment can be implemented by replacing the outermost 0.4 μm TiN layer with a 0.4 μm TiCN layer, TiBN layer, ZrN layer, and ZrCN layer, respectively. Excellent effect similar to the example was shown (the adhesion strength of the outermost layer was within ± 2N, and the wear amount was within ± 0.1 mm for the boundary wear amount (VN) and the flank average wear amount (VB)) Was within).

  Although the embodiments and examples of the present invention have been described as described above, it is also planned from the beginning to appropriately combine the configurations of the above-described embodiments and examples.

  It should be understood that the embodiments and examples disclosed herein are illustrative and non-restrictive in every respect. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

Claims (4)

A surface-coated cutting tool having a substrate and a coating layer formed on the substrate,
The coating layer includes an inner layer composed of one or more layers and an outer layer composed of one or more layers formed on the inner layer,
The inner layer has a layer containing Al ₂ O ₃ having a thickness of 0.5 μm or more as an uppermost layer in contact with the outer layer,
The outer layer includes an intermediate base layer formed on the uppermost layer of the inner layer, and an outermost layer constituting a surface having an adhesion strength of 20 N or less,
A surface-coated cutting tool, wherein the intermediate underlayer is made of TiC.   The outermost layer is composed of at least one element selected from the group consisting of Ti, Zr, Cr, and Hf and at least one element selected from the group consisting of carbon, nitrogen, oxygen, and boron. The surface-coated cutting tool according to claim 1, wherein the surface-coated cutting tool is a layer formed by:   In addition to the uppermost layer, the inner layer includes at least one element selected from the group consisting of group IVa elements, group Va elements, group VIa elements, Al, Si, and B of the periodic table, carbon, nitrogen, The surface-coated cutting tool according to claim 1, comprising a layer formed of a compound composed of at least one element selected from the group consisting of oxygen and boron.   The surface-coated cutting tool is any one of a drill, end mill, milling or turning cutting edge replacement cutting tip, metal saw, gear cutting tool, reamer, tap, or pin milling cutting edge replacement cutting tip. The surface-coated cutting tool according to any one of claims 1 to 3.