JP2017226018A - Cutting tools - Google Patents

Abstract

An object of the present invention is to extend the life of a cutting tool coated with a coating layer. A coating layer of a cutting tool is formed from a base material surface by a layer A composed of a nano-layered film of TiSi-based nitride and AlCr-based nitride, and a layered film of TiSi-based nitride and AlCr-based nitride. It is assumed that the B layer, the C layer made of a nano-laminated film of TiSi nitride and AlCr nitride, and the D layer made of AlCr nitride are laminated in this order. The thickness of layer A: the thickness of layer B: the thickness of layer C: the thickness of layer D: the thickness of layer D, which is the ratio of the thicknesses of the layers, is 1: 1: 1: 0.5. Thereby, the adhesiveness between each layer can be ensured enough, and the stress at the time of a cutting process can fully be disperse | distributed. As a result, peeling between the layers can be prevented, and the life of the cutting tool can be extended. [Selection] Figure 3

Description

  The present invention relates to a cutting tool. In particular, the present invention relates to a cutting tool whose base material surface is coated with a coating layer.

  2. Description of the Related Art Conventionally, a cutting tool whose base material surface is coated with a hard coating layer is known. In Patent Document 1, for the purpose of improving wear resistance, an alternating layered structure of a multilayer region in which thin layers A and thin layers B are alternately stacked and a single layer region composed of a single layer is disclosed. A cutting tool having a hard coating layer formed by vapor deposition is disclosed. Further, in Patent Document 1, the thin layer A is composed of an AlCr (aluminum / chromium) nitride layer, the thin layer B is composed of a TiSi (titanium / silicon) nitride layer, and the single layer is The thin layer A is composed of the same type of layer. In addition, a single layer of AlCr-based nitride is provided as the outermost layer.

JP 2011-235393 A

  However, in the coating layer disclosed in Patent Document 1, the stress acting on the coating layer cannot be sufficiently dispersed during cutting, and the AlCr nitride layer and the TiSi nitride It is difficult to ensure sufficient adhesion between the layers of the object. For this reason, there is a possibility that peeling occurs between the layers, and there has been a limit in extending the life of the cutting tool.

  This invention is made | formed in view of this point, The place made into the objective is to attain the lifetime improvement of the cutting tool coat | covered with the coating layer.

  The solution means of the present invention for achieving the above object is premised on a cutting tool whose base material surface is coated with a coating layer. In this cutting tool, the coating layer is formed from the surface of the base material as a layer A composed of a nano-layered film of TiSi-based nitride and AlCr-based nitride, a laminated film of TiSi-based nitride and AlCr-based nitride. B layer, TiSi nitride and AlCr nitride nano-laminated layer C, and AlCr nitride layer D are laminated in this order, and the thickness ratio of each layer Thickness: B layer thickness: C layer thickness: D layer thickness is 1: 1: 1: 0.5.

  Due to this specific matter, the nanolaminate film becomes an adhesion layer, so that the adhesion between the base material surface and the B layer and between the B layer and the D layer is sufficiently ensured. Moreover, the stress which acts on this coating layer at the time of cutting can be fully disperse | distributed. For this reason, peeling between lamination | stacking can be prevented and the lifetime of a cutting tool can be extended.

  In the present invention, the coating layer of the cutting tool is formed of a layer A composed of a nanolaminate film of TiSi nitride and AlCr nitride, and a laminate film of TiSi nitride and AlCr nitride from the surface of the base material. B layer, C layer composed of nano-laminated film of TiSi-based nitride and AlCr-based nitride, and D layer composed of AlCr-based nitride are laminated in this order. A layer thickness: B layer thickness: C Layer thickness: D layer thickness is 1: 1: 1: 0.5. Thereby, the adhesiveness between each layer can be ensured enough, and the stress at the time of a cutting process can fully be disperse | distributed. As a result, peeling between the layers can be prevented, and the life of the cutting tool can be extended.

It is a figure which shows schematic structure of an arc ion plating apparatus. It is a figure for demonstrating the principle of an arc ion plating method. It is a schematic diagram of the cross section of a coating layer. It is a figure which shows the test result of each of the adhesive force and the film | membrane drop-off rate in each of the coating layer which concerns on embodiment, and the coating layer which concerns on a comparative example. It is a figure which shows the test result of each rake face wear, land wear, and VB wear in each of the coating layer according to the embodiment and the coating layer according to the comparative example.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

-Arc ion plating equipment-
First, an outline of the arc ion plating apparatus for forming the coating layer on the surface of the base material of the cutting tool and the operation of forming the coating layer will be described.

  FIG. 1 is a diagram showing a schematic configuration of an arc ion plating apparatus 1. As shown in FIG. 1, the arc ion plating apparatus 1 includes a vacuum chamber 2, a cathode 3, a rotary table 4, an arc power source 5, a bias power source 6, a heater 7, a filament 8, and the like.

  The vacuum chamber 2 is constituted by a sealed casing, and a gas supply port 21 and a vacuum exhaust port 22 are formed respectively. The gas supply port 21 is provided for supplying an inert gas into the vacuum chamber 2 at the time of forming a coating layer or the like, and is connected with piping equipment (not shown) for supplying the inert gas. The vacuum exhaust port 22 is provided to exhaust the residual gas in the vacuum chamber 2 to increase the degree of vacuum, and is connected to a vacuum exhaust facility (not shown) such as a vacuum pump by piping equipment (not shown). Yes.

  The cathode 3 is a cathode portion formed of a material that becomes a target (film forming material), and is connected to an arc power source 5.

  The rotary table 4 is a part that supports workpieces (cutting tools in the present invention) W, W, which is an object for forming a coating layer, and is configured to be rotatable, and is discharged from the cathode 3 by vacuum arc discharge. Metal ions are uniformly deposited on the surfaces of the workpieces W and W. The rotary table 4 is connected to the bias power source 6 so that a bias voltage can be applied to the workpieces W and W via the rotary table 4.

  The heater 7 increases the temperature in the vacuum chamber 2. By raising the temperature in the vacuum chamber 2, excess gas (adsorbed gas) adsorbed on each part such as the surface of the cathode 3 can be released.

  The filament 8 emits thermoelectrons into the vacuum chamber 2.

  Next, the operation for forming the coating layer by the arc ion plating method will be described. FIG. 2 is a diagram for explaining the principle of the arc ion plating method.

  First, the inside of the vacuum chamber 2 is evacuated and the residual gas is reduced to increase the degree of vacuum.

  Next, preheating is performed by the heater 7 to raise the temperature in the vacuum chamber 2. When the temperature in the vacuum chamber 2 rises, the gas adsorbed on the surface of the cathode 3 and the like is released. At this time, the pressure in the vacuum chamber 2 temporarily rises due to the released gas or the like, but the released gas is discharged from the vacuum exhaust port 22 by continuing the vacuum exhaust. Thereby, the degree of vacuum in the vacuum chamber 2 is increased again.

  Next, preheating by the heater 7 is stopped, and evacuation is further continued to increase the pressure in the vacuum chamber 2 to a desired degree of vacuum.

  Next, while maintaining the vacuum state in the vacuum chamber 2, the rotary table 4 is rotated, and an inert gas (for example, nitrogen or the like) is supplied from the gas supply port 21 while adjusting the pressure in the vacuum chamber 2. The inside of the vacuum chamber 2 is made an inert gas atmosphere. Then, electric power is supplied from the arc power source 5 to the cathode 3, and an arc spot is formed on the cathode 3 by a striker rod (not shown). Thereby, the film forming material is evaporated and ionized from the surface of the cathode 3. Plasma is composed of metal ions and electrons released at this time. Further, a negative bias voltage is applied to the workpieces W and W by the bias power source 6. At this time, the positive metal ions are attracted by the workpieces W, W to which a negative potential is applied, and the base metal of the workpieces W, W (reacting the metal ions with an inert gas to form a hard film) For example, a hard film is formed on the surface of high-speed tool steel or the like.

  Such a coating layer forming operation is continuously performed, and the cutting tool coated with the coating layer described later is obtained by switching the film forming material for forming a hard film on the surface of the base material of the workpieces W and W. Will be obtained.

-Coating layer-
Next, the coating layer which coat | covers the base material surface of the cutting tool characterized by this embodiment is demonstrated. FIG. 3 is a schematic diagram of a cross section of the coating layer.

  As shown in FIG. 3, the coating layer is formed by laminating the A layer, the B layer, the C layer, and the D layer in this order from the surface of the base material.

  The A layer is composed of a nanolaminate film of TiSi nitride (TiSiN) and AlCr nitride (AlCrN). This A layer functions as an adhesion layer with the base material.

  The B layer is a laminated film of TiSi nitride (TiSiN) and AlCr nitride (AlCrN). This B layer has a function of relaxing stress acting on the coating layer during cutting and a function of preventing cracking.

  Like the A layer, the C layer is composed of a nanolaminate film of TiSi nitride (TiSiN) and AlCr nitride (AlCrN). This C layer functions as an adhesion layer between the B layer and the D layer.

  The D layer (outermost layer) is a single layer of AlCr-based nitride (AlCrN). This D layer functions as an oxygen barrier film.

  Since the coating layer is configured in this way, as described above, the B layer is not a single layer but a laminated film of TiSi-based nitride and AlCr-based nitride. By relaxing the stress acting on (dispersing the stress), the adhesion of the outermost layer D is enhanced.

  In addition, the AlCr-based nitride component used in each layer is Al-rich with 60% or more of Al, and the TiSi-based nitride component is added with 5% or more of Si. . The upper limit values of these components are appropriately set based on experiments and the like.

  In the B layer which is a laminated film, the thickness of each of the TiSi nitride and the AlCr nitride is set to about 0.1 μm.

  In the A layer and the C layer, which are nanolaminate films, the thickness of each of the TiSi nitride and the AlCr nitride is set to about 0.04 μm or less. These lower limit values of the film thickness are appropriately set based on experiments and the like.

  The total film thickness is 3 μm, the A layer is 800 to 900 nm, the B layer is 800 to 900 nm, the C layer is 800 to 900 nm, and the D layer is 350 to 500 nm. It has become. Therefore, the ratio of the thickness of each layer, that is, the thickness of the A layer: the thickness of the B layer: the thickness of the C layer: the thickness of the D layer is about 1: 1: 1: 0.5. Thereby, cracks and cracks can be suppressed, and stable adhesion strength is obtained.

  In other words, in the case of the conventional technique using a single layer for the intermediate layer, it becomes difficult to relieve the stress acting on the coating layer during the cutting process. Peeling could occur.

  On the other hand, in the present embodiment, a high hardness film such as TiSi-based nitride or AlCr-based nitride is nano-laminated (lowermost layer) to distribute stress, and the laminated film is directed toward the outermost AlCr-based nitride layer. By putting it in between, the adhesion strength is further increased.

  In this way, TiSi-based nitride and AlCr-based nitride are laminated to improve oxidation resistance and heat resistance and to increase hardness. For this reason, for example, an effect can be exhibited in high-speed mist processing such as an MQL (Minimum Quantity Lubrication) drill used for processing an oil hole of a crankshaft for an engine.

-Test example-
Next, test examples and results obtained for confirming the effect of the coating layer according to the present embodiment will be described.

  FIG. 4 is a diagram showing test results for adhesion strength and film drop-off rate in each of the coating layer according to the embodiment and the coating layer according to the comparative example.

  In Comparative Example 1, a TiAlN (TiAl nitride) layer is used as a coating layer. In Comparative Example 2, a Cr-based coating layer is laminated. In Comparative Example 3, a TiSiN layer and a TiAlCrN layer are used as coating layers. Comparative Example 4 is a laminate of TiSiN layers. The film thickness ratio of each layer of these Comparative Examples 1 to 4 and the total film thickness are as shown in FIG. In these comparative examples, the film thickness ratio shown in FIG. 4 represents the film thickness ratio of each layer from the outermost layer to the lowermost layer.

  Further, Comparative Example 5 is obtained by laminating the same A layer to D layer as in the above embodiment, but the ratio of the thickness of each layer was set to 0.5: 1: 2: 0.25. is there. In Comparative Example 6, the same A layer to D layer as those in the above embodiment are laminated, and the ratio of the thicknesses of the respective layers is 1: 1: 0.5: 2. In Comparative Example 7, three of the A to D layers similar to those of the above-described embodiment are laminated, and the thickness ratio of each layer is 1: 1: 3. Also in these comparative examples, the film thickness ratio shown in FIG. 4 represents the film thickness ratio of each layer from the outermost layer to the lowermost layer. The film thickness ratio of the embodiment shown in FIG. 4 also represents the film thickness ratio of each layer from the outermost layer to the lowermost layer (D layer: C layer: B layer: A layer).

  In any of these comparative examples, it is impossible to achieve both a sufficient adhesion and a low film drop-off rate. Specifically, the film drop-off rate is not 0% while securing 40 N or more as the adhesion.

  Particularly, Comparative Example 1, Comparative Example 3 and Comparative Example 7 have a high film drop-off rate at the cutting edge portion, and Comparative Example 2 and Comparative Example 4 cause chipping at an early stage. Then, film splitting at the edge portion occurred, and the result of Comparative Example 6 was that the toughness was low.

  On the other hand, in the embodiment, the adhesion force is 42.5 N, and the film drop-off rate is 0%. That is, it was confirmed that sufficient adhesion force (adhesion force of 40 N or more) and a low film drop-off rate (membrane drop-off rate 0%) can be achieved at the same time.

  FIG. 5 is a diagram showing test results of rake face wear, land wear, and VB wear in the covering layer according to the embodiment and the covering layer according to the conventional example (for example, the comparative example 1), respectively.

  In the present embodiment, even when the number of machining reaches a predetermined machining constant, the wear amount of rake face wear, land wear, and VB wear is half that of the conventional example. It was confirmed that the wear resistance was sufficiently secured. That is, in the case of the conventional example, the amount of wear reaches the limit when the machining constant is reached, whereas in the present embodiment, good machining performance is achieved even after reaching this machining constant. It was confirmed that it was maintained.

  As described above, in the present embodiment, from the surface of the base material of the cutting tool, a layer A composed of a nano-layered film of TiSi-based nitride and AlCr-based nitride, and a stack of TiSi-based nitride and AlCr-based nitride. B layer made of film, C layer made of nano-laminated film of TiSi-based nitride and AlCr-based nitride, and D layer made of AlCr-based nitride are laminated in this order, and the thickness of A layer which is the ratio of the thickness of each layer : B layer thickness: C layer thickness: D layer thickness is 1: 1: 1: 0.5. As a result, sufficient adhesion between the layers can be secured, stress during cutting can be sufficiently dispersed, peeling between the layers can be prevented, and the life of the cutting tool can be extended. it can.

-Other embodiments-
The film thickness of each layer (A layer to D layer) in the embodiment described above is an example, and the film thickness of each layer (A layer to D layer) is as long as the ratio of the thickness of each layer described above is ensured. Can be appropriately set without being limited to the above-described values.

  In the present invention, the thickness ratio of each layer (A layer to D layer) is not particularly limited as long as the above-described effects of the invention can be achieved. It is.

  The present invention can be applied to a cutting tool whose base material surface is coated with a coating layer.

1 Arc ion plating equipment W Workpiece (cutting tool)

Claims (1)

In a cutting tool whose base material surface is covered with a coating layer,
The coating layer includes, from the base material surface, an A layer composed of a nano-laminated film of TiSi nitride and AlCr nitride, a B layer composed of a laminated film of TiSi nitride and AlCr nitride, and TiSi The layer A is formed by stacking a C layer made of a nano-laminated film of nitride and an AlCr-based nitride, and a D layer made of AlCr-based nitride. The thickness of C layer: The thickness of D layer is 1: 1: 1: 0.5. The cutting tool characterized by the above-mentioned.

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