JP4827204B2 - Coated mold for plastic working and manufacturing method thereof - Google Patents

Description

  The present invention relates to a mold for plastic working that requires wear resistance used for forging, press working, and the like, and a method for manufacturing the same.

  Conventionally, for plastic working such as forging and pressing, steel typified by tool steel such as cold die steel, hot die steel, and high-speed steel, and dies made of metal such as cemented carbide are used. Has been. The above processing methods are classified into cold processing in which processing is performed near room temperature, warm processing in which the workpiece is heated to 400 ° C. or higher, and hot processing (hereinafter also referred to as hot processing). The mold also requires wear resistance on the work surface.

  In recent years, the load on the mold surface has increased due to the increased strength of workpieces, higher product accuracy, lubricant-free, and faster molding cycles. The number of “coating molds” in which hard surfaces are coated on the work surface by chemical vapor deposition (hereinafter also referred to as CVD) has been rapidly increasing. However, the required characteristics of the mold are not limited to the wear resistance of the work surface, and the mold itself is required to have high accuracy. Mold deformation increases. In particular, in the case of steel-based molds represented by tool steel, heat treatment distortion generated by heat treatment such as quenching and tempering performed after coating becomes a problem, and it has become difficult to satisfy the requirements sufficiently by the CVD method.

  Against this background, recently, the application of a physical vapor deposition method (hereinafter also referred to as PVD method) in which the above-described coating operation can be performed at a temperature lower than the tempering temperature of the mold material is increasing. For example, in a cold working mold, a method of applying a TiN coating layer by a PVD method after nitriding the surface of a mold base material in a specific component range has been proposed (Patent Document 1). ). In addition, for hot working molds, a method for pre-processing the PVD method and coating CrN or TiAlN after nitriding has been proposed (Patent Documents 2 and 3).

  Furthermore, a method of forming an AlCr nitride or an AlCrSi nitride by an ion plating method as a hard film exhibiting high durability even at 1000 ° C. or higher has been proposed (Patent Documents 4 and 5). As a hard coating having a low friction coefficient, a method (Patent Document 6) has been proposed in which an AlCr nitride whose surface contains amorphous carbon is formed by a sputtering method.

JP 58-031066 A JP-A-11-092909 JP 2003-245738 A Japanese Patent Laid-Open No. 10-025566 Japanese Patent Laid-Open No. 2003-321764 JP 2000-144378 A

  However, since the working environment of forging and pressing dies is becoming more severe year by year and the surface pressure during molding is higher, the functions of the coating proposed in Patent Documents 1 to 6 sufficiently satisfy various requirements. I can't do it.

  Therefore, the present invention is used for plastic working of metals such as cold and warm forging and press working, and in a metal mold that requires galling resistance and wear resistance, the covering metal for plastic working which has solved the above problems. It aims at providing a type | mold and its manufacturing method.

  The present inventors diligently researched means for improving the durability of the mold used for the above-mentioned plastic working. As a result, it has been found that it is particularly effective that the film coated on the working surface of the mold has a high hardness and heat resistance, and at the same time the surface is extremely smooth. Therefore, by clarifying the specific film configuration that satisfies the above requirements, the plastic working mold coated with this film has improved galling resistance and wear resistance, and the durability is greatly improved. Thus, the present invention has been reached.

That is, according to the present invention, Al _x Cr _y Si _z nitride (where x, y, z indicates an atomic ratio, x + y + z = 100, and x, y, z ≠ 0) is formed on the surface of the mold base. And having a surface roughness according to JIS-B-0601 (2001) of 0.06 μm or less in terms of arithmetic average roughness Ra and a hard coating having a maximum height Rz of 1.0 μm or less. It is a coating mold. Preferably, the hard coating has a thickness of 3 to 20 μm.

In addition, the hard coating preferably satisfies any one or more of the following requirements.
[Requirement 1] It has a composite crystal structure in which cubic crystal transitions to hexagonal crystal from the mold base toward the surface of the coating.
[Requirement 2] It has a gradient composition structure in which the x value increases and the y value decreases from the mold base toward the surface of the coating.
[Requirement 3] From the mold base toward the surface of the coating, the bottom layer made of Cr nitride, Al _x1 Cr _y1 Si _z1 nitride (provided that x1 ≦ y1 and x1, y1, z1 ≠ 0 And a multilayer structure of an uppermost layer made of a nitride of Al _x2 Cr _y2 Si _z2 (where x2> y2 and x2, y2, z2 ≠ 0).
[Requirement 4] From the mold base toward the surface of the coating, the lowermost layer made of Cr nitride, and the intermediate layer made of nitride of Al _x1 Cr _y1 Si _z1 (x1, y1, z1 ≠ 0) Al _x2 Cr _y2 Si _z2 nitride (provided that x2> x1, x2> y2 and x2, y2, z2 ≠ 0).

  Here, when the requirements 3 and / or 4 are satisfied, it is more preferable that the thickness ratios of the lowermost layer, the intermediate layer, and the uppermost layer are 0 to 10%, 50 to 90%, and 10 to 50%, respectively. Alternatively, the intermediate layer has a thickness of 1 μm or more, which is formed by alternately stacking the components of the lowermost layer having a thickness of 0.001 to 0.1 μm and the components of the uppermost layer having a thickness of 0.001 to 0.1 μm. More preferably, it is a layer.

Further, the hard film is made of Al _x Cr _y Si _z (W and / or Nb) _α nitride (where x, y, z, α represents an atomic ratio, x + y + z + α = 100, and x, y, z, It is preferable to include one or more of Nb and W represented by α ≠ 0) while satisfying the relationship of α ≦ 0.1 × x. Alternatively, a carbon film having a surface roughness according to JIS-B-0601 (2001) of 0.06 μm or less in terms of arithmetic average roughness Ra and a maximum height Rz of 1.0 μm or less is coated directly on the hard film. It is preferable that the carbon film contains tungsten carbide.

Furthermore, in the method for manufacturing a plastic working coated mold according to the present invention, Al _x Cr _y Si _z nitride (where x, y, and z are atoms) is formed on the surface of the mold base by a sputtering method using a target. A bias voltage that applies a sputtering power of 5 kW or more applied to the target to the mold substrate, and a hard coating comprising x + y + z = 100 and x, y, z ≠ 0) Is increased to the negative side of −100V or more.

And the preferable manufacturing method of the coating metal mold | die for plastic working of this invention is a reactive sputtering method using a Cr target and an AlCrSi alloy target in nitrogen atmosphere, and the surface of a mold base material is made of Al _x Cr _y Si _z . A method of coating a hard film made of nitride (where x, y, z represents an atomic ratio, x + y + z = 100, and x, y, z ≠ 0),
(1) Sputter power of 5 kW or more is applied to the Cr target, and the surface of the mold base is coated with the lowermost layer, which is a nitride of Cr,
(2) Sputtering power of 5 kW or more is applied to the Cr target and the AlCrSi alloy target, respectively, and an Al _x1 Cr _y1 Si _z1 nitride (x1 ≦ y1 and x1, y1, z1) is formed on the lowermost layer. ≠ 0)
(3) Sputtering power of 5 kW or more is applied to the AlCrSi alloy target, and the intermediate layer is made of a nitride of Al _x2 Cr _y2 Si _z2 (where x2> y2 and x2, y2, z2 ≠ 0). It is characterized by covering the top layer.

Or, further, a reactive sputtering method using a Cr target and an AlCrSi alloy target in a nitrogen atmosphere, and Al _x Cr _y Si _z nitride (where x, y, and z are atomic ratios) Wherein x + y + z = 100 and x, y, z ≠ 0).
(1) Sputter power of 5 kW or more is applied to the Cr target, and the surface of the mold base is coated with the lowermost layer, which is a nitride of Cr,
(2) Sputtering power of 5 kW or more is applied to the Cr target and the AlCrSi alloy target, respectively, and the Al _x1 Cr _y1 Si _z1 nitride (however, x1, y1, z1 ≠ 0) is formed on the lowermost layer. Cover the intermediate layer,
(3) Sputtering power of 5 kW or more is applied to the AlCrSi alloy target, and Al _x2 Cr _y2 Si _z2 nitride (x2> x1, x2> y2, and x2, y2, z2 ≠ on the intermediate layer 0)) is covered.

In the above manufacturing method, the hard coating is formed of Al _x Cr _y Si _z (W and / or Nb) _α nitride (where x, y, z, α represents an atomic ratio, x + y + z + α = 100, and x , Y, z, α ≠ 0), and can include one or more of Nb and W satisfying the relationship of α ≦ 0.1 × x. In this case, the AlCrSi alloy target used for covering the intermediate layer and the uppermost layer can contain W and / or Nb.

  In the above manufacturing method, after the hard coating is coated, it is preferable to coat the carbon coating directly on the uppermost layer by a sputtering method using a carbon target. And it is more preferable that this carbon film contains WC.

  A conventional PVD method TiN, CrN, TiAlN, AlCrN, AlCrSiN nitride film, and a metal mold coated with these laminated films have a sufficient life against the severe use environment in recent years. It has become impossible. In the present invention, a film type having high hardness and heat resistance is applied, and this is simultaneously coated in an extremely smooth state and having an optimum structure for the damage form of the mold. The galling resistance and wear resistance of the mold work surface can be greatly improved. Therefore, the durability of the metal mold for plastic working is remarkably improved, and this is an indispensable technique for practical use.

It is a scanning electron micrograph of the film | membrane surface of this invention example 1, and is a figure which shows an example of the coating metal mold | die for plastic working of this invention. It is a scanning electron micrograph of the film | membrane surface of the prior art example 9, and is a figure which shows an example of the conventional coating metal mold | die for plastic working. It is a scanning electron micrograph of the film | membrane surface of the prior art example 10, and is a figure which shows an example of the conventional coating metal mold | die for plastic working. It is a surface roughness profile of the example 1 of this invention, and is a figure which shows an example of the coating metal mold | die for plastic working of this invention. It is a surface roughness profile of the example 2 of this invention, and is a figure which shows an example of the coating metal mold | die for plastic working of this invention. It is a surface roughness profile of the prior art example 9, and is a figure which shows an example of the conventional coating metal mold | die for plastic working. It is the surface profile of the prior art example 10, and is a figure which shows an example of the conventional coating metal mold | die for plastic working. It is a film composition of the example 3 of this invention, and is a figure which shows an example of the coating metal mold | die for plastic working of this invention.

  The feature of the present invention is that a film type capable of simultaneously achieving high hardness and excellent heat resistance is selected, and it is optimally applied to the surface of the mold for plastic working, and to the damage form of the mold. By coating with the structure, the same mold with excellent durability can be achieved. Hereinafter, the coating mold for plastic working of the present invention coated with the above-mentioned film will be described for each constituent requirement.

[A] The surface of the mold base is made of a nitride of Al _x Cr _y Si _z (where x, y, z indicate an atomic ratio, x + y + z = 100, and x, y, z ≠ 0). Cover with a hard coating.
The component composition of the hard coating applied to the present invention is based on AlCrSiN, which can have high hardness and excellent heat resistance. Specifically, over the entire film, a nitride of Al _x Cr _y Si _z (where x, y, z indicates an atomic ratio, x + y + z = 100, and x, y, z ≠ 0). It is a film | membrane represented by the compositional formula. Preferably, x> 50, z> 1, and y <50. In the above description, nitride is used, but the characteristics of the present invention are also exhibited even if nitride is the main component and carbon, oxygen, boron, sulfur, etc. are present within 20 atomic% with respect to nitrogen. It is.

  In the above basic component configuration, AlCrN is also a hard film having high hardness and excellent heat resistance. However, since the damage form of the coating mold for plastic working is wear due to the particles of the hard coating falling off, it is particularly effective to add Si to prevent this. That is, by adding Si to AlCrN, the crystal grain size in the film is remarkably refined, and in addition to AlCrN having a columnar fracture surface structure, it shifts to a granular fracture surface structure. As a result, AlCrSiN with a refined and granulated film structure has a smaller drop-off unit than AlCrN and a smaller drop-off area, so that the durability is improved.

[B] The hard coating has a surface roughness according to JIS-B-0601 (2001) of 0.06 μm or less in terms of arithmetic average roughness Ra, and a maximum height Rz of 1.0 μm or less.
In the coating mold for plastic working, when the work surface is simply coated with a hard film, if the surface of the film is rough, the unevenness becomes the starting point of damage, which greatly improves galling resistance and wear resistance. Is not reached. Therefore, for the mold for use in the present invention, the surface of the hard coating coated on the work surface is controlled to 0.06 μm or less for Ra and 1.0 μm or less for Rz. The coated mold of the present invention satisfying this surface roughness greatly improves the durability of forging and press molds that become severe due to a synergistic effect with the above film components.

  Here, in the film generally obtained by the arc ion plating method, there are droplets (molten particles) of about several microns which are inevitably mixed during the film formation. And since this droplet becomes a factor which roughens the film | membrane surface, it has a bad influence on improvement, such as abrasion resistance. In addition, since the droplets are metal particles, the inherent properties of the film composition cannot be activated, which can also be a starting point for galling. Therefore, in order to achieve the smooth surface roughness of the present invention, it is important to take sufficient measures against the droplets.

  For example, if the arc ion plating method as described in Patent Documents 4 and 5 is applied to actual mold production, the coated film surface has many convex portions due to droplets, that is, has a high surface roughness value. The galling and wear resistance will be insufficient. Therefore, in order to smooth the film, they are removed by polishing with emery paper or an abrasive containing diamond particles. However, since the droplets are in the form of particles, they easily fall off during polishing. Therefore, the surface of the film after polishing from which the convex portions have been removed is also apparently smooth (although the Ra value is small), but in fact, the concave portions are formed simultaneously with the removal of the convex portions, and the Rz value is large. The defect that induces galling starting from this recess remains.

  On the other hand, since the film obtained by sputtering as disclosed in Patent Document 6 hardly contains droplets, it is easy to obtain a relatively smooth film surface. However, the smoothness achieved is still inadequate and has not reached the surface roughness value of the present invention. And since it has a defect in the adhesion strength with the substrate is significantly inferior compared with the ion plating method, especially when it is applied to a mold for plastic working under severe use environment, At present, it has not been put into practical use. Therefore, in the development of a coating die for plastic working with a smooth coating surface, which was difficult to establish, the present invention solved the above-mentioned drawbacks in the sputtering method and established a manufacturing method described later. , Has reached its achievement.

Therefore, the surface roughness of the hard coating is greatly affected by the droplets present (or existed) on the coating surface. Therefore, in the present invention, it is effective to match the management of the area ratio of the droplets (convex portions) or the traces (recessed portions) from which the droplets have dropped off with the above-mentioned surface roughness value defined according to the JIS standard. That is, the plastic working metal mold according to the present invention is obtained from a droplet when an area of an area of 100 μm ² arbitrarily selected from the surface of the hard film is observed with, for example, a scanning electron microscope (hereinafter also referred to as SEM). It is preferable that the total area ratio of the convex portions or the concave portions from which the droplets are dropped is 5% or less. The area ratio is more preferably 1% or less.

  The droplets themselves are particulate and metal particles, but may be specified with a maximum diameter of approximately 0.5 μm or more. Or even if it analyzes a composition of the macro particle part confirmed on the film | membrane surface, it can be easily distinguished from the part of a healthy hard film | membrane whether it is a droplet. And about the trace of a droplet, the depth is 0.3 micrometer or more with respect to a reference plane (a healthy smooth place where the macro particle containing a droplet is not confirmed) among the recessed parts confirmed on the membrane | film | coat surface. You just have to specify.

  On the other hand, as described above, the droplets existing on the surface of the film can remain, even if all of them can be removed by polishing or the like. Therefore, even if the surface of the hard film according to the present invention is only a trace of droplets, such a recess should be reduced. In other words, the coated mold for plastic working of the present invention has a density of recesses as defined above when a contact surface roughness measurement is performed on a 2 mm long line portion arbitrarily selected from the surface of the hard coating. It is preferably less than 2 pieces / mm. The density is more preferably less than 1 piece / mm. The surface roughness measurement is preferably an average value measured three times.

[C] The hard coating preferably has a thickness of 3 to 20 μm.
For the hard coating of the present invention having a smooth surface roughness value, it is advantageous to control the Ra and Rz values to be low if the thickness of the entire coating is also thin. However, when the thickness is less than 3 μm, the wear resistance tends to decrease. On the other hand, when the film thickness increases, the hard coating tends to be broken or peeled off due to impact during molding when using a mold. Therefore, the film thickness of the present invention is preferably 3 to 20 μm. In addition to the destruction or peeling of the hard coating, the adhesion strength with the base material, and the smoothness of the surface, the total of these is more preferably 6 to 20 μm, considering the durability of the mold itself. 16 μm is more preferable.

  In addition, if the hard film of the present invention is formed by a sputtering method, the residual compressive stress in the film is about 0 to 2 GPa, and shows a low value of less than half compared to the arc ion plating method. It is effective in suppressing In addition, in the film formation by the PVD method, when the film thickness is increased, the discharge time is lengthened. However, in the case of the arc ion plating method, as described above, the number of droplets remaining in the hard film increases. As a result, the surface roughness value increases rapidly. However, if the sputtering method is used, the surface roughness value does not increase significantly even if the sputtering discharge time is increased. Therefore, including the manufacturing method of the present invention to be described later, even when the film thickness is 6 μm or more, it is possible to achieve a hard film sufficiently prevented from being peeled off and to have wear resistance. A coated mold for plastic working having both smoothness can be obtained.

[D] It is preferable that the hard coating has a composite crystal structure in which cubic crystal transitions to hexagonal from the mold base toward the surface of the coating.
In the present invention, the crystal structure of the hard film composed of the component composition of AlCrSiN has a “composite crystal structure” in which the crystal structure moves from cubic to hexagonal toward the surface of the film. That is, the hard coating of the present invention, in terms of its component structure, has the crystal structure transferred to the granular fractured surface structure by the addition of Si, and has improved the drop-off resistance of the coating particles as described above. is there. However, on the other hand, considering the improvement in adhesion to the mold base, it is desirable that at least the vicinity of the base in the coating has a columnar fracture surface structure. Therefore, even if the entire coating is composed of components of AlCrSiN, the crystal structure on the mold substrate side is controlled to be cubic by adjusting the balance of each element in a part of the coating. A composite crystal structure exhibiting a fracture surface structure can provide a hard film having high adhesion strength to the substrate and at the same time having high hardness and excellent wear resistance.

  And in the work surface of the hard film, if the crystal structure is controlled to be hexagonal by adjusting the balance of each element, the hexagonal AlCrSiN film has a granular fracture surface structure with fine crystal grains. From the above, it is effective against particle-dropping wear that proceeds in the depth direction. By making the hard film of the present invention have the above-mentioned composite crystal structure, the wear resistance effect and the drop-off wear resistance effect are exhibited at the same time, and the durability of the coating die for plastic working is improved.

As described above, the control of the composite crystal structure of the AlCrSiN film of the present invention is controlled by the atomic ratio x, y, z value in the composition formula of Al _x Cr _y Si _z . Specifically, a cubic AlCrSiN film can be applied to Cr with 50 <x <55, 45 <y <50, and 0.1 <z <1 if the addition of wear resistance due to its increased hardness is taken into account. On the other hand, it is preferable that the atomic ratio is slightly higher in Al. If film formation is performed by sputtering, it is desirable to control the bias voltage to be applied to the mold base material among the film formation conditions at that time in the range of −100 to −300V. In addition, as for the film | membrane site | part which contacts a metal mold | die base material, when considering adhesiveness first, AlCrSiN of x <y may be sufficient, and the lowermost site | part may be cubic CrN (y = 100).

  The hexagonal AlCrSiN film preferably has an atomic ratio of 55 <x <90, 1 <z <20, 10 <y <45 with Al as the main component of Cr. When forming a film by sputtering, it is particularly desirable to control the bias voltage in the range of −30 to −100V.

[E] The hard coating preferably has a gradient composition structure in which the x value increases and the y value decreases from the mold base toward the surface of the coating.
This is as described in [D]. And, by adopting an “gradient composition structure” in which the value of x increases and the value of y decreases, the crystal structure changes in a gradient toward the coating surface (contact surface with the workpiece), It is preferable because the contrast of the change is relaxed (continuously changed without a clear boundary) and the adhesion strength between layers is improved.

[F] The hard coating consists of a lowermost layer made of a nitride of Cr and a nitride of Al _x1 Cr _y1 Si _z1 (provided that x1 ≦ y1 and x1, y1, It is preferable to have an intermediate layer composed of z1 ≠ 0) and an uppermost multilayer structure composed of nitrides of Al _x2 Cr _y2 Si _z2 (where x2> y2 and x2, y2, z2 ≠ 0).
In consideration of the matters described in [D] above, the hard coating of the present invention can be applied to the base material from a mold base material in order to ensure adhesion strength with the base material, wear resistance, and anti-drop-off resistance. It is also effective to have a “multi-layer structure” consisting of a CrN bottom layer, an AlCrSiN intermediate layer with little Al for Cr, and an AlCrSiN top layer mainly composed of Al toward the surface. However, in the intermediate layer, if the number of Al atoms relative to Cr is smaller than that of the uppermost layer (that is, x2> x1), x1, y1, z1 ≠ 0 regardless of the magnitude relationship between x1 and y1. You may change to AlCrSiN.

  In the [F] hard coating, the thickness ratios of the lowermost layer, the intermediate layer, and the uppermost layer are preferably 0 to 10%, 50 to 90%, and 10 to 50%, respectively. Even if the lowermost layer of CrN is omitted, it is possible to ensure adhesion strength with the substrate. However, in a more severe use environment, the adhesion strength is improved by using this lowermost layer. And when forming a lowermost layer, it is preferable that the thickness ratio which occupies for the whole hard film shall be 10% or less. The function of the lowermost layer is mainly to strengthen the adhesion with the base material, and the hardness is low. When the thickness exceeds 10%, the wear resistance tends to decrease. A preferred thickness ratio is 5% or less.

  On the other hand, the intermediate layer composed of the mixed composition of the lowermost layer and the uppermost layer is a layer that exhibits wear resistance on the one hand while strengthening the adhesion with the base material. It is preferable that it is 50 to 90%. And, the uppermost layer mainly composed of Al is inferior in wear resistance to the intermediate layer, but the fracture surface structure as described above is granular, so that it is excellent in galling resistance and the deposits fall off. It has the effect of reducing damage caused by. For this function and effect, the thickness ratio of the entire hard coating is preferably 10 to 50%.

  In the [F] hard coating, the intermediate layer is coated with the lowermost layer component having a thickness of 0.001 to 0.1 μm and the uppermost layer component having a thickness of 0.001 to 0.1 μm alternately stacked. It is preferable that the layer has a thickness of 1 μm or more. In other words, in the intermediate layer, although the overall appearance is a mixed composition of the lowermost layer and the uppermost layer, in fact, the structure in which the lowermost layer and the uppermost layer are superfinely stacked has an excellent wear resistance effect. In addition, a hard film having high deformability, high hardness and high toughness that can follow the deformation of the mold base in use can be obtained. And about each thickness of the lowermost layer and uppermost layer which comprise an intermediate | middle layer finely, when each exceeds 0.1 micrometer, the adhesive strength between both fine layers falls, and the tendency for hardness and toughness to fall conversely, Become. Note that it is difficult to control each of them to be less than 0.001 μm.

[G] The above hard coating is Al _x Cr _y Si _z (W and / or Nb) _α nitride (where x, y, z, α represents an atomic ratio, x + y + z + α = 100, and x, y , Z, α ≠ 0), and preferably includes at least one of Nb and W satisfying the relationship of α ≦ 0.1 × x.
As a result, the hard coating of the present invention has a finer crystal grain size and higher hardness, and at the same time, improved heat resistance. However, it is important for increasing the hardness of the hard coating that the total amount of Nb and W be 10% or less with respect to the above x.

[H] Directly above the hard film is coated with a carbon film having a surface roughness according to JIS-B-0601 (2001) of 0.06 μm or less in terms of arithmetic average roughness Ra and a maximum height Rz of 1.0 μm or less. It is preferred that
Although the hard film of the present invention exhibits excellent wear resistance, in order to improve the initial conformability of the mold, it is preferable to coat the carbon film directly thereon. That is, since it is effective for suppressing the initial chipping of the hard coating, the characteristics of the hard coating itself of the present invention are easily exhibited, and as a result, the durability of the mold is improved. Here, since the surface of the carbon film is extremely smooth, the surface roughness of the hard film itself (Ra of 0. 0 is preferably controlled) is preferably controlled by coating with a layer thickness of about 0.1 to 2 microns. 06 μm or less and Rz 1.0 μm or less).

  The carbon film of the present invention preferably has a relatively soft and highly deformable structure such as so-called diamond-like carbon (hereinafter also referred to as DLC), which is coated by sputtering using a target containing graphite, which will be described later. In order to improve the heat resistance of the carbon film, a carbon film containing tungsten carbide having a WC bond (hereinafter referred to as WC) is preferable.

  In the above, the covering metal mold | die for plastic working of this invention was demonstrated. The metal mold of the present invention is not particularly defined with respect to the metal material used as the base material. For example, cold die steel, hot die steel, high speed steel, cemented carbide and the like as described above can be used. In this regard, improved metal types that have been proposed as steel types that can be used in conventional molds, including standard metal types (steel types) according to JIS and the like, can also be applied.

  In addition, if necessary, the surface of the base material before coating may be coated with a metal layer. Moreover, in a hard film, you may coat | cover a very thin functional layer on it. And for nitrogen in the nitride forming the hard film, oxygen, boron, sulfur, carbon, etc. may be added in a total atomic ratio of 20% or less, preferably 10% or less. The effect of the present invention is exhibited.

  Next, the manufacturing method of the metal mold | die for plastic working of this invention is described. As described above, in order to achieve the same mold according to the present invention, the PVD method used for coating is advantageously applied by a sputtering method in which a smooth coating surface can be easily obtained. However, on the other hand, as described above, there was a drawback in that the adhesion strength with the substrate was weak. Therefore, in the present invention, the above-described method for producing a coating die for plastic working has been achieved by establishing a sputtering method capable of greatly improving the adhesion strength.

  Conventionally, when a film is coated by a known arc ion plating method, the surface roughness value in the as-coated state is about 0.1 μm even if the Ra value is small, and exceeds 2.0 μm when reaching the Rz value. It was rough. And even if the Ra value can be reduced to 0.1 μm or less by polishing after coating, it is practically difficult to reduce the Rz value to 1.0 μm or less by forming recesses due to dropout of the droplets. It is.

  On the other hand, the sputtering method is an advantageous technique for obtaining a film having a smooth surface as described in Patent Document 6, for example, that the Ra value of the coated AlCrN film is 0.02 μm. If it becomes a smooth surface, there is room for improvement, and it is as above-mentioned that it is inferior to adhesiveness with a base material above all. Therefore, the present invention succeeded in increasing the adhesion strength between the hard coating and the base material by setting the film forming conditions with much higher sputtering energy compared to Patent Document 6. Hereinafter, the manufacturing method will be described for each constituent requirement.

[I] In the sputtering method using a target, the sputtering power input to the target is 5 kW or more, and the bias voltage applied to the mold base is −100 V or more (on the negative side).
For example, as described in Patent Document 6, the sputtering power applied to the target when coating a conventional AlCr-based nitride film is about 300 W. On the other hand, that of the present invention is set to a high power value of 5 kW or more. When the sputtering power is high, the growth direction of the particles of the AlCrSiN coating changes, and the particle morphology changes to a granular shape or a columnar shape, so that a dense coating structure can be obtained. Further, when the sputtering power is low, the energy at the time of film formation is low, so that the particles tend to grow in the vertical direction, and the obtained coating surface has irregularities of individual particles, that is, needle-like surface morphology. Therefore, in the present invention, by setting the above sputtering power to a high value, the adhesion strength of the film to the base material and the surface smoothness are remarkably improved, and various requirements for the coating die for plastic working are required. Satisfy the characteristics.

  Furthermore, in the manufacturing method of the present invention, the bias voltage applied to the mold base during sputtering is also important. That is, the AlCrSiN film coated on the substrate surface is bombarded with sputter gas ions simultaneously with the film formation by a negatively applied bias voltage. At this time, when the bias voltage is less than −100 V (on the positive side of −100 V), the bombard effect is weak, and the particles of the AlCrSiN film grow like needles as described above. Therefore, in the present invention, the surface smoothness is improved by increasing the bias voltage to the minus side of −100 V or more.

And in particular, in coating the hard film of [F] described above, by a reactive sputtering method using a Cr target and an AlCrSi alloy target in a nitrogen atmosphere,
(1) Sputter power of 5 kW or more is applied to the Cr target, and the surface of the mold base is coated with the lowermost layer, which is a nitride of Cr,
(2) Sputtering power of 5 kW or more is applied to each of the Cr target and the AlCrSi alloy target, and Al _x1 Cr _y1 Si _z1 nitride (x1 ≦ y1 and x1, y1, z1 ≠ on the lowermost layer) 0) covering the intermediate layer consisting of
(3) Sputtering power of 5 kW or more is applied to the AlCrSi alloy target, and the intermediate layer is made of a nitride of Al _x2 Cr _y2 Si _z2 (where x2> y2 and x2, y2, z2 ≠ 0). It is preferred to coat the top layer.

  In other words, the Cr nitride, which is the lowermost layer, can be coated with a sputtering power of 5 kW or more, particularly to improve the adhesion to the substrate and to relieve the stress of the high hardness layer coated thereon. It is effective for exhibiting excellent mechanical properties. Next, the intermediate layer obtained by applying a sputtering power of 5 kW or more has high crystallinity, high hardness and high toughness, and improves the wear resistance of the entire film. The uppermost layer obtained by applying a sputtering power of 5 kW or more has a fine crystal grain size, and is effective in suppressing the above-described drop-off wear. In the intermediate layer, if the number of Al atoms with respect to Cr is smaller than that of the uppermost layer (that is, x2> x1), regardless of the magnitude relationship between x1 and y1, AlCrSiN of x1, y1, z1 ≠ 0 What may be changed is the same as [F] above.

  As described above, the hard coating of the present invention may contain one or more of Nb and W. Therefore, according to this, in the manufacturing method of the present invention, the AlCrSi alloy target used for covering the intermediate layer and the uppermost layer can contain W and / or Nb.

[J] After coating the hard coating, it is preferable to coat the carbon coating directly on the uppermost layer by sputtering using a carbon target.
The carbon film has a relatively soft and highly deformable structure such as so-called DLC as described above. When such a carbon film is coated by a sputtering method using a target, the sputtering power applied to the carbon target is preferably 4 kW or more.

  Further, as described above, in order to improve heat resistance, it is preferable to use a carbon film containing WC. The carbon film containing WC can be coated by, for example, a sputtering method using a composite target of WC and graphite. At this time, it is preferable to create the target so that the ratio of WC and graphite in the composite target is larger for the graphite component. More specifically, WC: graphite = 10-40: 60-90 (however, the chemical formula WC: ratio by C atom).

<Preparation of sample for evaluation>
Here, a sample for evaluating mechanical properties (that is, surface roughness, film hardness, adhesion) required for a plastic working coating mold was prepared. For the base material, high-speed steel SKH51 specified by JIS is prepared, and this is tempered at 180 to 580 ° C. by tempering at 540 to 580 ° C. after quenching by heating at 1180 ° C. in a vacuum and cooling with nitrogen gas. It was. The substrate has a cylindrical shape with a thickness of 5 mm and a diameter of 20 mm.

  Next, after polishing the surface of the cylindrical base material with # 1000 and # 1500 abrasive paper, it is smoothed by an aero lapping machine, and the surface roughness is adjusted to 0.05 μm for Ra and 0.5 μm for Rz. It was. Then, the following surface treatment was applied to those subjected to ultrasonic cleaning in a hydrocarbon-based solvent and degreased to prepare samples for evaluation that are examples of the present invention and conventional examples.

[Invention Example 1]
As the film forming means, a sputtering method in which a bias voltage was applied to the substrate was adopted, and the lowermost layer, the intermediate layer, the uppermost layer, and the carbon film were successively formed in the same chamber. Regarding the film forming apparatus, first, a DC power source was used as a sputtering power source and a bias power source. Then, an independent anode is provided to increase the distance of electron movement and to devise a means for activating the plasma, thereby adopting means for increasing the ionization rate as compared with a normal sputtering apparatus. Thereby, the crystallinity of the film is improved and the hardness can be increased.

Vacuum evacuation is performed with a turbo molecular pump and a rotary pump. Four sputtering evaporation sources are mounted in the apparatus. Then, cathode 1: Cr target, cathode 2: WC ₇₀ C ₃₀ target (chemical formula WC: ratio by C atom), cathode 3 and 4: Al ₆₀ Cr ₃₇ Si ₃ target (atomic ratio) were installed. The introduced gas is Ar, Kr, or N ₂ and is introduced from the gas supply port.

  The bias power source is connected to the substrate and independently applies a negative bias voltage to the substrate. The substrate rotates at two revolutions per minute and revolves through a fixing jig and a sample holder. The distance between the substrate and the target surface was 50 mm.

Regarding the film forming conditions, first, heating was performed for 90 minutes in a state where the substrate temperature was 500 ° C. by the heater in the film forming apparatus, and the pressure in the vacuum container (chamber) reached 4 × 10 ⁻³ Pa. After that, Ar gas was introduced into the vacuum vessel. Then, a pulse bias voltage of −650 V was applied to the substrate, and the substrate was cleaned with Ar ions for 15 minutes. Thereafter, a DC bias voltage of −200 V was applied to the substrate. At this time, power of 1500 W was supplied between the independent anode and cathode, the plasma density of Ar was increased, and the substrate was cleaned with Ar ions for 30 minutes.

Next, the pressure inside the container is evacuated to 1 × 10 ⁻³ Pa, the base material temperature is kept constant at 450 ° C., and the pressure inside the container becomes 580 mPa under a constant flow rate of Ar gas of 500 ml. N ₂ gas was introduced as described above. As in the case of cleaning the substrate, the bias voltage is set to -120 V, the anode voltage is set to -110 V, the sputtering power of 5 kW is supplied to the cathode 1 (Cr target), and held for 10 minutes. A 0.5 μm CrN bottom layer was coated.

Subsequently, with the power supplied to the cathode 1, a sputtering power of 5 kW is supplied to each of the cathodes 3 and 4 (Al ₆₀ Cr ₃₇ Si ₃ target: numerical values are atomic ratios), and a coating treatment for 10 minutes is first performed. went. Then, the sputtering power applied to the cathodes 3 and 4 was increased by 1 kW every 10 minutes, reached 9 kW, held for 60 minutes, and coated with an AlCrSiN intermediate layer having a thickness of about 5 μm.

Then, the power supply to the cathode 1 was interrupted, and the AlCrSiN uppermost layer having a thickness of about 2 μm was covered only with the cathodes 3 and 4 after that. Finally, the supply of power to the cathodes 3 and 4 and the supply of nitrogen are stopped, the Ar gas is maintained at a constant flow rate of 500 ml, and 4 kW of power is supplied to the cathode 2 (WC ₇₀ C ₃₀ target). A DLC layer containing about 1 μm thick WC was coated. The coated sample (substrate—CrN bottom layer—AlCrSiN intermediate layer—AlCrSiN top layer—DLC layer) was cooled to 150 ° C. or lower and then taken out from the container. FIG. 1 is a SEM photograph showing the surface of the film of Example 1 of the present invention.

[Invention Example 2]
Except for the film forming conditions described below, the sample preparation method of Example 1 of the present invention is the same. That is, for the substrate after cleaning, the cathode 1 is not used, and a sputtering power of 5 kW is supplied to each of the cathodes 3 and 4 (Al ₆₀ Cr ₃₇ Si ₃ target) to perform a coating process for 10 minutes. went. Then, the sputtering power applied to the cathodes 3 and 4 is increased by 1 kW every 10 minutes, and after reaching 9 kW, it is held for 60 minutes to cover a film made of an AlCrSiN layer having a thickness of about 5 μm corresponding to the intermediate layer. did. The coated sample (substrate-AlCrSiN single layer) was cooled to 150 ° C. or lower and then taken out from the container.

[Invention Example 3]
For the sample preparation method of Example 1 of the present invention, after coating up to the uppermost layer of AlCrSiN, the coated sample taken out from the container without coating the DLC layer (substrate-CrN lowermost layer-AlCrSiN intermediate layer- AlCrSiN top layer).

[Invention Example 4]
The coated sample (substrate-CrN bottom layer-AlCrSiN intermediate layer-AlCrSiN bottom layer) according to the same sample preparation method as Example 1 except that the cathodes 3 and 4 were changed to Al ₆₀ Cr ₃₅ Si ₅ targets (atomic ratio). Upper layer-DLC layer).

[Invention Example 5]
A coated sample (substrate-CrN bottom layer-AlCrSiN intermediate layer-AlCrSiN bottom layer) according to the same sample preparation method as Example 1 except that the cathodes 3 and 4 were changed to Al ₇₅ Cr ₁₅ Si ₁₀ targets (atomic ratio). Upper layer-DLC layer).

[Invention Example 6]
A coated sample according to the same sample preparation method as that of Example 1 of the present invention except that the cathodes 3 and 4 were changed to Al ₆₀ Cr ₂₅ Nb ₁₀ Si ₅ target (atomic ratio) (substrate—CrN bottom layer—AlCrNbSiN intermediate layer— AlCrNbSiN top layer-DLC layer).

[Invention Example 7]
A coated sample (substrate-CrN bottom layer-AlCrWSiN intermediate layer-) according to the same sample preparation method as Example 1 except that the cathodes 3 and 4 were changed to Al ₆₀ Cr ₂₅ W ₁₀ Si ₅ target (atomic ratio). AlCrWSiN top layer-DLC layer).

[Invention Example 8]
Except for the film forming conditions described below, the sample preparation method of Example 1 of the present invention is the same. That is, after supplying a sputtering power of 5 kW to each of the cathodes 3 and 4 (Al ₆₀ Cr ₃₇ Si ₃ target) and performing a coating treatment for 10 minutes, the sputtering power applied to the cathodes 3 and 4 every 50 minutes is applied. The film structure is formed by coating the AlCrSiN intermediate layer having a thickness of about 18 μm by raising it by 1 kW and holding for 240 minutes after reaching 9 kW. -DLC layer). Thereby, the thickness of the hard film of the invention example 8 excluding the carbon film is about 20 μm in total.

[Conventional Example 9]
The cylindrical substrate is a sample coated with an AlCrSiN film having a thickness of about 5 μm by a known arc ion plating method. FIG. 2 is an SEM photograph showing the surface of the film of Conventional Example 9.

[Conventional Example 10]
For the coated sample of Conventional Example 9, the protrusions (droplets) confirmed on the surface of the film are polished and removed using # 1000 and # 1500 emery paper, and the entire surface is further aero-wrapped. This is a smoothed sample. FIG. 3 is an SEM photograph showing the coating surface of Conventional Example 10.

[Conventional Example 11]
For the above cylindrical substrate, as a known manufacturing method, for example, an AlCrSiN film having a thickness of about 5 μm coated with a sputtering output of 300 W according to the pretreatment and film formation conditions described in Patent Document 6 is used. It is a sample having.

<Coating composition analysis>
About the coating sample of this invention example 1-8 and the conventional examples 9-11, the composition of the film | membrane was analyzed using the electron probe microanalyzer (EPMA; JEOL Co., Ltd. JXA-8900R). Analysis is such that the cross-section of the film with the specimen tilted 5 degrees with respect to the outermost surface of the film is mirror-polished, and the average value is as wide as possible in the lowermost layer, intermediate layer, and uppermost layer on the polished surface. The analysis area of each layer was selected. The analysis value was measured five times with an acceleration voltage of 15 kV, a sample current of 0.2 μA, and a counting time of 10 seconds, and the average value was obtained. The analysis results are shown in Table 1.

  In Inventive Examples 1 and 3 to 8, the intermediate layer is formed by simultaneously operating the three-component and four-component targets as in the cathode 1. Therefore, strictly speaking, this intermediate layer has a structure in which a nitride layer made of the metal component of the cathode 1 and a nitride layer made of the metal component 3 (and 4) are stacked with an extremely thin layer thickness. It has become. The thickness of each layer varies depending on the substrate rotation speed, sputtering power, gas pressure, etc. at the time of film formation, but in the case of the present invention example 1, the intermediate layer has a thickness of 0.005 to 0.02 μm. And a CrN layer in the range of 0.005 to 0.07 μm. The thickness of each layer was measured by observing the cross section with a transmission electron microscope.

  Moreover, about the example 3 of this invention, the composition analysis of the depth direction was also performed by the high frequency glow discharge emission analysis. The result is shown in FIG. From the outermost surface (sputtering time 0 seconds) toward the substrate side, the presence of the uppermost layer, intermediate layer, and lowermost layer of the present invention is confirmed. The intermediate layer has a gradient composition structure composed of a mixed component of the lowermost layer and the uppermost layer, with the Cr content continuously decreasing and the Al and Si content increasing continuously toward the surface side. It is. In particular, since the adhesion strength between layers is improved by this gradient composition structure, the galling resistance of the coating die for plastic working of the present invention is greatly improved.

<Evaluation of mechanical properties>
[Evaluation of hardness]
The hardness of the film was measured using a nanoindentation device manufactured by Elionix. Since this evaluation apparatus can measure with a minute load, the indentation formed on the measurement object is also minute, and thus the hardness of each layer of the laminated structure film can be measured. Then, in order to measure the hardness of each layer, the cross section of the film in which the test piece is inclined by 5 degrees with respect to the outermost surface of the film is mirror-polished, and then the maximum indentation depth is about 1/10 of the thickness of each layer in the polishing surface of the film An area that would be less than 1 was selected. At this time, even if the maximum indentation depth was about 1/5, there was no influence from the base material.

  Then, 10 points were measured for each layer under the measurement conditions of an indentation load of 9.8 mN, a maximum load holding time of 1 second, and a removal rate after loading of 0.098 mN / second, and the average value was obtained. The film hardness by this measurement method is easily influenced by the fine shape of the indenter, the temperature, humidity at the time of measurement, and the surface condition of the sample, and the obtained numerical values cannot be treated as quantitative values. Is different. Therefore, on the other hand, a single crystal Si reference sample was prepared, and its hardness was measured simultaneously (it was 15 GPa), so that a relative comparison can be made based on the measurement result. In Invention Examples 1 and 3 to 8, since the lowermost layer was thin, the hardness of the intermediate layer and the uppermost layer was measured. The results are shown in Table 1.

  The uppermost layer of Invention Example 1 and Conventional Example 11 are films having the same composition, but Invention Example 1 coated with the production method (film formation conditions) of the present invention has high hardness because the structure is dense, Although it is a sputtering method, a hardness equal to or higher than that of the arc ion plating method is obtained. This is because the sputtering power of the present invention is higher than that of the conventional one by “high power”, and in addition, the plasma density at the time of film formation is high, so the crystallization of the film is promoted. It is thought that it was because it was done.

[Evaluation of adhesion]
In order to evaluate the adhesion of the film (substrate and film, interlayer), the peel load of the film was measured using a CSM scratch tester (REVETEST). The measurement conditions are as follows.
Measurement load: 0.9 to 120 N,
Load speed: 99.25 N / min,
Scratch speed: 10 mm / min,
Scratch distance: 12 mm,
AE sensitivity: 5,
Indenter: Rockwell, diamond,
Tip radius: 2 μm,
Hardware setting: Fn contact 0.9N,
Fn speed: 5 N / s
Fn removal speed: 10 N / s
Approach speed: 2% / s
The peeling load is determined by observing the scratch mark after the test with an optical microscope when the scratch is scratched from the outermost surface of the film (the surface where the carbon film is present). The load when peeled (that is, when the base material at the bottom of the scratch mark was completely exposed) was used. The results are shown in Table 3.

  Invention Examples 1 to 8 each had a peel load of 80 N or higher, and showed high adhesion strength equal to or higher than that of a film coated by the arc ion plating method. In addition, the conventional example 11 by the well-known sputtering method was a result with very low adhesive strength.

[Evaluation of surface roughness]
Ra and Rz of the coating surface were measured with a contact type surface roughness measuring instrument of SURFCOM 480A manufactured by Tokyo Seimitsu. The measurement conditions were as follows.
Evaluation length: 2 mm or 4 mm,
Measurement speed: 0.3 mm / s,
Cut-off value: 0.8mm,
Filter type: Gaussian,
Measurement range: ± 40 μm
Tilt correction: Straight line,
Cut-off ratio: 300,
And Ra and Rz were measured from the obtained profile. The measured value is the average value when measured three times (FIGS. 4, 5, 6, and 7 are examples of the coating surface profiles of Examples 1 and 2 of the present invention and Conventional Examples 9 and 10, respectively. ).

  Moreover, the recessed part confirmed on the surface of a film | membrane was also measured. That is, in the film of Conventional Example 10 formed by the arc ion plating method and polished to the surface, it is a drop-off trace of the droplets also confirmed in the profile of FIG. For the reference line (smooth film surface) of the profile of each sample, as a result of counting the recesses deeper than 300 nm, for example, in FIG. 7, there are 7 recesses for the measurement length of 2 mm. Is a density of about 3 pieces / mm.

  Furthermore, when it applied to the above, the convex part confirmed on the surface of a membrane | film | coat was observed, and the total of the area ratio with the concave part was measured. That is, at the convex portion, by taking an SEM photograph at a magnification of 1000 times, for example, the maximum diameter of 0.5 μm or more, which is often confirmed in the film of Conventional Example 9 (FIG. 2) formed by the arc ion plating method, The particles (droplets) were subjected to image processing, and the area ratio was calculated. In addition, by taking SEM photographs in the recesses, for example, dropouts or removal traces of particulate droplets that are confirmed to be black in the film of Conventional Example 10 (FIG. 3) are also measured, and these recesses are imaged. The area ratio was calculated after processing. The above results are summarized in Table 4.

  Inventive Examples 1 to 8 achieve a smooth coating surface with Ra of 0.06 μm or less and Rz of 1.0 μm or less. On the other hand, in the conventional example 9 formed by the arc ion plating method, as shown in FIG. 2, a large number of droplets are present on the coating surface, and the surface is rough. Further, even in the case of the conventional example 10 in which the polishing finish is applied to smooth the coating surface of the conventional example 9, traces of droplets are seen instead of the coating surface, and the Rz value is not improved. .

[Evaluation of oxidation resistance]
After each sample was held in the air at 1000 ° C. for 6 hours, the Ra value of the coating surface was measured with the same contact surface roughness meter as described above. The results are shown in Table 5.

  Inventive Examples 1 to 8 having a smooth surface are excellent in oxidation resistance because there are few irregularities as starting points of oxidation. In particular, Examples 4, 5, and 7 of the present invention showed little damage due to oxidation, and only the surface layer portion was discolored in the above oxidizing environment, and no oxidation of the substrate was confirmed. This is because the uppermost layers of the hard coatings of Invention Examples 4, 5, and 7 have a hexagonal crystal structure (hcp) in the X-ray diffraction results shown later, so that the crystal grain size is fine. Conceivable. Such a hard film has excellent oxidation resistance even at 1000 ° C. or higher.

  On the other hand, in the conventional examples 9 and 10 having a rough surface, in addition to the presence of many droplets, the oxidation of the base material was also confirmed from the pinhole from which the droplets were dropped. In Conventional Example 11, the surface of the film was in a needle-like rough form, so oxygen entered from the grain boundary and oxidation progressed.

[Evaluation of crystallinity]
The film of each sample was subjected to X-ray diffraction, and their crystal structure was examined. The equipment used was an X-ray diffractometer manufactured by Rigaku Corporation, tube voltage 120 kV, tube current 40 μm, X-ray source Cukα, X-ray incident angle 5 degrees, X-ray incident slit 0.4 mm, 2θ 20-90 degrees. Measured with These results are shown in Table 6. In addition, when the presence of two or more kinds of crystal structures is identified from each layer, only the crystal structure showing the maximum intensity is listed in Table 6 among the crystal structures whose existence is identified. In the films of Invention Examples 1 to 8, the intermediate layer had a cubic (fcc) structure with an excellent balance between hardness and adhesion.

<Production of real mold>
A cold forging die for cup molding made of SKH51 (hardness 64HRC) was produced, and the life evaluation in the real die of the present invention was performed. The mold has a diameter of 30 mm and a height of 250 mm, and a working surface for cup molding is processed at the tip. First, the raw material was roughly processed into a mold shape in the annealed state. And after quenching by nitrogen gas cooling from heating and holding at 1180 ° C. in a vacuum, it was tempered at 540 to 580 ° C. and tempered to 64 HRC. Finally, the working surfaces of the molds that are finished to the final shape by finishing (polishing + aero lapping) are coated with the coatings of Invention Examples 1-8 and Conventional Examples 9-11 evaluated in Example 1. did.

<Durability evaluation>
Cold forging was performed on the cold forging die for cup forming produced above using the carbon steel for mechanical structure S50C defined in JIS as a workpiece. The durability of the mold was evaluated based on the number of shots when vertical flaws occurred in the product. Table 7 shows the number of shots for each mold.

  Compared to the mold of the conventional example, the mold of the present invention has a life of three times or more and has excellent durability. In particular, the molds of Examples 1, 4, 5, and 7 of the present invention realized stable processing, and the defect rate due to vertical scratches was 0% even at the time of 10,000 shots. Even with the molds of Examples 2, 3, 6, and 8 of the present invention in which several defects occurred in the product before reaching 10,000 shots, they were in a state where they could be used continuously until 10,000 shots. It was.

  On the other hand, the mold of Conventional Example 9 could not be continuously molded because the defective rate of products due to vertical stripes increased rapidly before reaching 100 shots. Similarly, the mold of Conventional Example 10 could no longer be used continuously after 500 shots due to the occurrence of galling starting from the concave portion of the work surface. The mold of Conventional Example 11 could not be used at all because the film peeled off from the beginning of forging stuck to the product.

  The present invention describes a metal mold for plastic working that is used for metal plastic working such as cold and warm forging and press working and requires wear resistance. And considering its excellent wear resistance, oxidation resistance, galling resistance, and adhesion, it can be applied to plastic working of titanium, aluminum, and their alloys, depending on the usage conditions, not limited to iron It is. Further, the coating mold for plastic working of the present invention is used in contact with a molten metal such as a die used for die casting and casting, or a casting pin or a piston ring used for an injection machine for die casting. Diversion is also possible as a casting member.

Claims (18)

Al _x Cr _y Si _z nitride on the surface of the mold base (where x, y, z indicates an atomic ratio, x + y + z = 100, and x, y, z ≠ 0), and JIS− A coating die for plastic working, characterized in that a hard coating having a surface roughness according to B-0601 (2001) of 0.06 μm or less in terms of arithmetic average roughness Ra and a maximum height Rz of 1.0 μm or less is coated.   The coating die for plastic working according to claim 1, wherein the hard coating has a thickness of 3 to 20 μm.   The coating for plastic working according to claim 1 or 2, wherein the hard film has a composite crystal structure in which cubic crystals shift to hexagonal crystals from the mold base toward the surface of the film. Mold.   The hard coating has a gradient composition structure in which the x value increases and the y value decreases from the mold base toward the surface of the coating. The coating mold for plastic working as described. The hard coating is a lowermost layer made of a nitride of Cr from the mold substrate toward the surface of the coating, and a nitride of Al _x1 Cr _y1 Si _z1 (where x1 ≦ y1 and x1, y1, z1 ≠ 0 And a multilayer structure of an uppermost layer made of a nitride of Al _x2 Cr _y2 Si _z2 (where x2> y2 and x2, y2, z2 ≠ 0). 5. A metal mold for plastic working according to any one of 1 to 4. The hard coating is a lowermost layer made of Cr nitride and an intermediate layer made of Al _x1 Cr _y1 Si _z1 nitride (x1, y1, z1 ≠ 0) from the mold base toward the surface of the coating. 2. A multilayer structure of an uppermost layer made of a nitride of Al _x2 Cr _y2 Si _z2 (where x2> x1, x2> y2, and x2, y2, z2 ≠ 0). The covering metal mold | die for plastic working in any one of thru | or 5.   7. The plasticity according to claim 5, wherein the hard coating has a thickness ratio of the lowermost layer, the intermediate layer, and the uppermost layer of 0 to 10%, 50 to 90%, and 10 to 50%, respectively. Coating mold for processing.   The hard coating has a thickness of 1 μm or more, in which the intermediate layer is coated by alternately stacking the lowermost layer component having a thickness of 0.001 to 0.1 μm and the uppermost layer component having a thickness of 0.001 to 0.1 μm. The coating die for plastic working according to any one of claims 5 to 7, wherein the coating die is for plastic working. The hard film is made of Al _x Cr _y Si _z (W and / or Nb) _α nitride (where x, y, z, α represents an atomic ratio, x + y + z + α = 100, and x, y, z, α ≠ The metal-plating cover for plastic working according to any one of claims 1 to 8, comprising at least one of Nb and W represented by 0) satisfying a relationship of α ≦ 0.1 × x. Type.   A carbon film having a surface roughness according to JIS-B-0601 (2001) of 0.06 μm or less in terms of arithmetic mean roughness Ra and a maximum height Rz of 1.0 μm or less is coated directly on the hard film. The covering metal mold | die for plastic working in any one of Claim 1 thru | or 9.   The coating die for plastic working according to claim 10, wherein the carbon coating immediately above the hard coating contains tungsten carbide. By sputtering using a target, Al _x Cr _y Si _z nitride (where x, y, z indicates an atomic ratio, x + y + z = 100, and x, y, z ≠ 0) is formed on the surface of the mold base. ), And the bias power applied to the mold base is increased to the negative side of −100 V or higher. A method for manufacturing a coated mold for processing. By reactive sputtering using a Cr target and an AlCrSi alloy target in a nitrogen atmosphere, Al _x Cr _y Si _z nitride (where x, y, z indicates an atomic ratio, and x + y + z = 100, and x, y, z ≠ 0).
(1) Sputter power of 5 kW or more is applied to the Cr target, and the surface of the mold base is coated with the lowermost layer, which is a nitride of Cr,
(2) Sputtering power of 5 kW or more is applied to the Cr target and the AlCrSi alloy target, respectively, and an Al _x1 Cr _y1 Si _z1 nitride (x1 ≦ y1 and x1, y1, z1) is formed on the lowermost layer. ≠ 0)
(3) Sputtering power of 5 kW or more is applied to the AlCrSi alloy target, and the intermediate layer is made of a nitride of Al _x2 Cr _y2 Si _z2 (where x2> y2 and x2, y2, z2 ≠ 0). The uppermost layer is coated, The method for producing a coating die for plastic working according to claim 12. By reactive sputtering using a Cr target and an AlCrSi alloy target in a nitrogen atmosphere, Al _x Cr _y Si _z nitride (where x, y, z indicates an atomic ratio, and x + y + z = 100, and x, y, z ≠ 0).
(1) Sputter power of 5 kW or more is applied to the Cr target, and the surface of the mold base is coated with the lowermost layer, which is a nitride of Cr,
(2) Sputtering power of 5 kW or more is applied to the Cr target and the AlCrSi alloy target, respectively, and the Al _x1 Cr _y1 Si _z1 nitride (however, x1, y1, z1 ≠ 0) is formed on the lowermost layer. Cover the intermediate layer,
(3) Sputtering power of 5 kW or more is applied to the AlCrSi alloy target, and Al _x2 Cr _y2 Si _z2 nitride (x2> x1, x2> y2, and x2, y2, z2 ≠ on the intermediate layer The method for producing a coating die for plastic working according to claim 12 or 13, wherein the uppermost layer comprising 0) is coated. The hard film is made of Al _x Cr _y Si _z (W and / or Nb) _α nitride (where x, y, z, α represents an atomic ratio, x + y + z + α = 100, and x, y, z, α ≠ The method for producing a coated metal mold for plastic working according to claim 12, comprising at least one of Nb and W represented by 0) satisfying a relationship of α ≦ 0.1 × x. The hard film is made of Al _x Cr _y Si _z (W and / or Nb) _α nitride (where x, y, z, α represents an atomic ratio, x + y + z + α = 100, and x, y, z, α ≠ Or Nb and W represented by 0) satisfying the relationship of α ≦ 0.1 × x, and the AlCrSi alloy target contains W and / or Nb. 14. A method for producing a metal mold for plastic working according to item 14.   The coated metal mold for plastic working according to any one of claims 12 to 16, wherein after the hard film is coated, the carbon film is coated directly on the uppermost layer by a sputtering method using a carbon target. Production method.   The method for producing a coating die for plastic working according to claim 17, wherein the carbon film immediately above the hard film contains tungsten carbide.