JP6489412B2 - Hard coating layer and cold plastic working mold - Google Patents

Description

  The present invention relates to a hard coating layer formed on a substrate by physical vapor deposition or the like, further improved in crack resistance and wear resistance, and a cold plastic working gold on which the hard coating layer is formed. It relates to types.

  Conventionally, a physical vapor deposition method is used to improve wear resistance in cutting tools based on metals such as cemented carbide and high-speed tool steel, and jigs and tools such as presses, forging dies, and punching punches. Further, a hard film such as TiN, TiC, TiCN, TiAlN, TiAlCrN, TiAlCrCN, TiAlCrSiBCN, TiCrAlSiBN, CrAlSiBYN, and AlCrN is coated by chemical vapor deposition.

For example, Patent Document 1 (Japanese Patent Application Laid-Open No. 2003-71610) discloses a hard film for a cutting tool that can perform high-speed and high-efficiency cutting and has excellent wear resistance, and has a composition (Ti _a , Al _b , Cr _c ) (C _1-d N _d ), 0.02 ≦ a ≦ 0.30, 0.55 ≦ b ≦ 0.765, 0.06 ≦ c, a + b + c = 1, 0 An invention relating to a hard coating in which .ltoreq.5.ltoreq.d.ltoreq.1 (a, b, and c represent the atomic ratio of Ti, Al, and Cr, respectively, and d represents the atomic ratio of N) has been proposed.

Patent Document 2 (Japanese Patent Application Laid-Open No. 2003-71611) discloses a hard film for a cutting tool that is capable of high-speed and high-efficiency cutting and has excellent wear resistance, and has a composition of (Ti _1- bcd). , Al _a , Cr _b , Si _c , B _d ) (C _1-e N _e ), 0.5 ≦ a ≦ 0.8, 0.06 ≦ b, 0 ≦ c ≦ 0 0.1, 0 ≦ d ≦ 0.1, 0.01 ≦ c + d ≦ 0.1, a + b + c + d <1, 0.5 ≦ e ≦ 1 (a, b, c, d are Al, Cr, Si, B, respectively) The invention relating to a hard coating is proposed, wherein e represents the atomic ratio of N and e represents the atomic ratio of N. Further, this document describes that two or more hard coatings satisfying the above-described requirements are formed (claim 7, table 6 and paragraphs (0084) to (0087)).

Patent Document 3 (Japanese Patent Laid-Open No. 2012-97303) discloses an invention relating to a hard film forming member for the purpose of improving the wear resistance of a hard film coated on a cutting tool, a sliding member, a molding die or the like. Has been proposed. The hard coating member consists formula composition expressed by _{Ti a Cr b Al c Si d} Y e (B u C v N w), wherein a, b, c, d, e, u, v, When w is atomic ratio,
0.05 ≦ a, 0.05 ≦ b, 0.2 ≦ a + b ≦ 0.55, 0.4 ≦ c ≦ 0.7, 0.02 ≦ d ≦ 0.2, 0 ≦ e ≦ 0.1, A layer satisfying 0 ≦ u ≦ 0.1, 0 ≦ v ≦ 0.3, a + b + c + d + e = 1, u + v + w = 1,
When the composition is composed of a formula represented by Ti _f Cr _g Al _h (B _x C _y N _z ), and f, g, h, x, y, z are atomic ratios,
0 ≦ f, 0.05 ≦ g, 0.25 ≦ f + g ≦ 0.6, 0.4 ≦ h ≦ 0.75, 0 ≦ x ≦ 0.1, 0 ≦ y ≦ 0.3, f + g + h = 1, B layer satisfying x + y + z = 1,
When the A layer and the B layer are alternately laminated, and a set of the laminated structure of the A layer and the B layer is one unit, the thickness of the one unit is 10 to 50 nm, and The film thickness of the hard coating is 1 to 5 μm. Furthermore, it is described that the film thickness ratio between the A layer and the B layer is preferably 1: 5 to 5: 1 (paragraph (0035)).

Patent Document 4 (Japanese Patent Application Laid-Open No. 2011-80101) proposes an invention relating to a hard coating in which a cold press die or a punch die is coated to improve wear resistance. The hard film according to claim 2 of Patent Document 4 has a composition represented by (Ti _a Cr _b Al _c L _{d Me} ) (B _x C _y N _z ), where L is Si and At least one of Y, and M is at least one of Group 4 elements (excluding Ti), Group 5 elements, Group 6 elements (excluding Cr), and rare earth elements, When a, b, c, d, e, x, y, z are atomic ratios,
0.1 ≦ a <0.3, 0.3 <b <0.6, 0.2 ≦ c <0.35, 0.01 ≦ d <0.1, 0.01 ≦ e ≦ 0.1, a + b + c + d + e = 1, x ≦ 0.1, y ≦ 0.1, 0.8 ≦ z ≦ 1, and x + y + z = 1.

Patent Document 5 (Japanese Patent Laid-Open No. 2005-226117) proposes an invention related to a hard coating for improving wear resistance of a cutting tool or a sliding member. This hard film is a film formed by alternately laminating layers A and B on the surface of a base material, and when the thicknesses of layer A and layer B are dA and dB, respectively, dB / dA ≦ 0.5 0.5 nm ≦ dB, dA ≦ 200 nm,
The composition of the layer A consists of a formula represented by (Cr _1−α X _α ) (B _a C _b bN _1−b−c O _c ) _e , where X is Ti, Zr, Hf, V , Nb, Ta, Mo, W, Al and Si, one or more elements selected from the group consisting of 0 ≦ α ≦ 0.9, 0 ≦ a ≦ 0.15, ≦ b ≦ 0 .3, 0 ≦ c ≦ 0.1, 2 ≦ e ≦ 1.1, α represents the atomic ratio of X, and a, b, and c represent the atomic ratio of B, C, and O, respectively)
The composition of the layer B is expressed by the formula B _1−s−t C _s N _t , where 0 ≦ s ≦ 0.25, (1−s−t) /t≦1.5, s, t Are hard films made of C and N, respectively.

  Patent Document 6 (Japanese Patent Application Laid-Open No. 2001-259777) proposes an invention relating to an extrusion tool provided with means for preventing wear due to cracks on the tool tip surface. This extrusion tool has a surface modified layer made of TiN, TiC, or TiCN formed around the bearing part of the extrusion tool by PVD or CVD, further increasing the hardness from the inside, and tip that collides relatively with the blank This is a front and rear extrusion tool for forging and heading in which this surface modification layer does not exist on the surface. In addition, in this patent document, after forming a surface modified layer that is harder than the base material, the tip surface that collides with the forging / forging blank is ground to remove the surface modified layer on the tip surface. Have been described.

JP 2003-71610 A JP 2003-71611 A JP 2012-97303 A JP 2011-80101 A JP 2005-226117 A JP 2001-259777 A

The hard coatings disclosed in Patent Literature 1 and Patent Literature 2 improve the wear resistance and oxidation resistance of the hard coating by defining the atomic ratio of the elements contained in the composition, It is a hard coating for cutting tools.
On the other hand, cold forging dies used in particularly harsh environments can be repeatedly applied with tensile stress and compressive stress in the die base material at a high speed (more than 50 shots per minute) in a closed region. Compared with cutting tools and other application molds, fine cracks are likely to occur on the mold surface. Therefore, the hard film formed on the mold surface is required to have crack resistance when subjected to repeated stress, and at the same time, wear resistance.

The hard film forming member disclosed in Patent Document 3 is applied to a cutting tool, a sliding member, a molding die, etc., and the atomic ratio of elements contained in the film composition is increased in order to improve its wear resistance. While having a laminated structure in which the prescribed A layer and B layer are alternately laminated, and when one unit of the laminated structure of the A layer and the B layer is 1 unit, the thickness of this 1 unit is 10 to 50 nm, Furthermore, it is a hard film in which the film thickness of the hard film is 1 to 5 μm and the film thickness ratio is preferably 1: 5 to 5: 1.
However, as in Patent Documents 1 and 2, Patent Document 3 does not disclose the configuration and means of a hard coating for preventing the occurrence of fine cracks on the mold surface. Particularly, since the Al content in the A layer and / or the B layer is too large, the surface roughness is deteriorated, and the durability is inferior when applied to a cold plastic working die. Al and Si are important elements that are added to improve the hardness and oxidation resistance of the hard coating layer, and the atomic ratio thereof needs to be specified in an appropriate range depending on the application.

  Patent Document 4 discloses a hard coating that is coated on a cold pressing die or a punching die to improve wear resistance, but defines the atomic ratio of elements contained in the coating composition. Therefore, the hard coating does not have a laminated structure, and further, no means for preventing the occurrence of fine cracks on the mold surface is disclosed.

The hard coating disclosed in Patent Document 5 is formed by alternately laminating layers A and B having a predetermined composition on a cutting tool or a sliding member, and the thickness of layer A is dA and the thickness of layer B is dB. In this case, the hard film has dB / dA ≦ 0.5, and further 0.5 nm ≦ dB and dA ≦ 200 nm. However, the composition of layer B has the formula B _1−s−t C _s N _t , where 0 ≦ s ≦ 0.25, (1−s−t) /t≦1.5, s, t are Each of which represents an atomic ratio of C and N), and is composed only of B carbonitride. Therefore, it is considered that a hard film having sufficient crack resistance cannot be obtained even when a film obtained by laminating layers A and B on the mold surface is subjected to repeated stress.

The front and back extrusion tools described in Patent Document 6 have a hard coating (surface modified layer) made of TiN, TiC or TiCN coated on the surface of the tool base material, but the tip of the extrusion tool. The part is deformed by the impact force of driving, and the inner part of the base metal is elastically deformed, but the surface of the tip part has no elastic force, so that a crack occurs, and this crack grows inward, causing the early wear of the extrusion tool. become. Therefore, in order to prevent the occurrence of this crack, the tool adopts a means that does not form a hard film (surface modified layer) at the tip of the tool.
However, hard coatings made of TiN, TiC, or TiCN are conventionally used coatings. Currently, hard coatings with much higher wear resistance than these coatings have been developed. It is desirable to employ a means for covering the part with a hard film to prevent premature wear of the extrusion tool.

  The present invention has been made in view of such problems of the prior art, and its purpose is to provide a hard coating layer that is superior in wear resistance and suppresses the occurrence of cracks than the conventional hard coating, and this An object of the present invention is to provide a die for cold plastic working that has a wear resistance and a crack resistance, and has improved durability (mold life) by coating a base material with a hard coating layer.

As a result of earnest research on the improvement of crack resistance of a hard coating (hereinafter referred to as “hard coating layer”), the present inventor has found that the arbitrarily selected diameter is 1 μm in the cross section in the thickness direction of the hard coating layer. The composition within the range is a hard coating layer having a predetermined component composition , and this hard coating layer is a laminated structure in which an A layer having a predetermined component composition and a B layer having a predetermined component composition are alternately combined . In addition, by defining the film thickness and film thickness ratio between the A layer and the B layer, both crack resistance and wear resistance are improved, especially as a hard coating layer that covers a cold plastic working mold. I found out that I can make it.

  That is, the die for cold plastic working is determined only by specifying the atomic ratio of the predetermined element in each layer of the A layer and the B layer, specifying the layer thickness of each layer, and specifying the layer thickness ratio of each layer independently. Crack resistance and wear resistance of the hard coating layer to be coated are not sufficiently improved. However, by simultaneously controlling the component composition of the hard coating layer, the film thicknesses of the A layer and the B layer constituting the hard coating layer, and the film thickness ratio, the hard coating layer of the cold plastic working mold It has been found that both crack resistance and wear resistance are improved, and in particular, the durability of the mold can be improved by coating the hard coating layer on the punch of a cold plastic working mold.

Invention of Claim 1 of this invention is a hard film layer laminated | stacked on a base material, Comprising: The film thickness of the said hard film layer is 1-5 micrometers,
The composition of the hard coating layer has a general formula: TiaCrbAlcSidMe (BuCvNw) (where M is Nb, one or more elements of V, a, b, c, d, e, u, v, w are It represents the atomic ratio of Ti, Cr, Al, Si, M, B, C, N),
In the cross section in the thickness direction of the hard coating layer , the composition in the range of arbitrarily selected diameter of 1 μm is as follows :
0.3 <a ≦ 0.6,
0 <b ≦ 0.2,
0.2 ≦ c <0.5,
0 <d ≦ 0.1,
0 ≦ e ≦ 0.2,
0 ≦ u ≦ 0.1,
0 ≦ v ≦ 0.3,
0 <w ≦ 1,
a + b + c + d + e = 1,
u + v + w = 1,
The filling,
The hard coating layer is composed of the above general formula and, among its constituent elements, the atomic ratio of Ti, Cr, Si,
The following conditions:
0 ≦ b ≦ 0.1,
0 ≦ d ≦ 0.01,
b <a,
A layer comprising a composition satisfying
Similarly, among the constituent elements, regarding the atomic ratio of Ti, Cr, Al, Si,
The following conditions:
0 ≦ a <0.3,
0.1 <b ≦ 0.3,
0.3 ≦ c <0.7,
0.01 <d ≦ 0.1,
b> a,
B layer composed of a composition satisfying the above, each having a thickness of 50 nm or less of the A layer and the B layer, and having a laminated structure in which a plurality of the A layer and the B layer are alternately laminated,
When the thickness of the A layer is dA and the thickness of the B layer is dB, the (dB / dA) value is
dB / dA = 0.1-0.5,
It is characterized by being made.

  The invention according to claim 2 of the present invention is the hard coating layer according to claim 1, further comprising an underlayer formed between the surface of the substrate and the hard coating layer, and the composition of the underlayer Is characterized by comprising the composition of the A layer.

  The invention according to claim 3 of the present invention is the hard coating layer according to claim 1 or 2, further comprising a surface layer formed on a surface of the hard coating layer, wherein the surface layer is the A layer or It is characterized by comprising the composition of the B layer.

According to a fourth aspect of the present invention, there is provided a cold plastic working mold characterized in that the hard coating layer according to any one of the first to third aspects is formed on the surface of the mold. It is.
is there.

  According to a fifth aspect of the present invention, in the cold plastic working die according to the fourth aspect, the cold plastic working die is integrally connected to a bearing portion, and is driven by shot driving. And a punch having an upper end for plastic working of the workpiece.

  According to a sixth aspect of the present invention, in the punch according to the fifth aspect, the film thickness of the hard film layer formed on the upper end is the same as that of the hard film formed on the other part of the punch. It is characterized by being formed larger than the thickness of the layer.

  According to a seventh aspect of the present invention, in the punch according to the fifth or sixth aspect, the outer peripheral edge portion of the upper end portion and the bearing portion are connected via an arc shape portion, and the arc shape portion Is characterized in that the arc radius is 1 mm or less.

  The invention described in claim 8 of the present invention is characterized in that the punch described in any of claims 5 to 7 is a punch used for a die for backward extrusion.

  The composition of the hard coating layer according to the present invention consists of a general formula: TiaCrbAlcSidMe (BuCvNw) (a, b, c, d, e, u, v, and w are predetermined atomic ratios). In order to improve the wear resistance and crack resistance, the atomic ratio of each element constituting the composition of the A layer and B layer forming the laminated structure was appropriately set, and the film thicknesses dA and B of the A layer The layer thickness dB of each layer is 50 nm or less so that the A layer and the B layer have a laminated structure, and the (dB / dA) value is set to 0.1 to 0.5. Cracking and wear resistance can be significantly improved. Thereby, it becomes possible to improve the lifetime of the cold plastic working mold in which the hard coating layer of the present invention is formed in each step.

It is a cross-sectional schematic diagram for demonstrating the structure of 1st Embodiment about the hard film layer of this invention. It is a cross-sectional schematic diagram for demonstrating the structure of 2nd Embodiment about the hard film layer of this invention. It is a cross-sectional schematic diagram for demonstrating the structure of 3rd Embodiment about the hard film layer of this invention. It is a top view of the punch which shows one Embodiment of the metal mold | die for cold plastic working which concerns on this invention. FIG. 5 is an enlarged view of an E portion in the punch shown in FIG. 4. 1 is a schematic top view showing an example of a film forming apparatus for forming a hard coating layer according to the present invention. It is a figure which shows the outline | summary of the back extrusion process using the metal mold | die for cold plastic working of this invention, Comprising: (a) is the state before carrying out plastic working of an extrusion molded product, (b) is plastic working of an extrusion molded product. It is a figure which shows the state after having performed. In an example in which a cold plastic working die (punch) according to the present invention was prototyped and an experiment of cold plastic working was performed, the peripheral edge of the upper end of the punch at the forging life of the prototype punch of sample number 3 FIG. Similarly, it is the photograph figure of the peripheral part vicinity of the upper end part of a punch at the time of a forge life about the trial manufacture punch of the sample number 1. FIG. Similarly, it is a photograph figure of the peripheral part of the upper end part of the punch at the time of a forge life about the trial manufacture punch (comparative example) of the sample number 8. FIG. Similarly, it is an enlarged photograph figure near the peripheral part of the upper end part of a punch at the time of a forge life about a trial manufacture punch of sample number 8. Similarly, it is an enlarged photograph figure near the peripheral part of the upper end part of the punch at the time of a forge life about the trial manufacture punch of sample number 9 (comparative example). It is an enlarged photograph figure of the surface of the hard coating layer shown by FIG. Similarly, it is an enlarged photograph figure near the peripheral part of the upper end part of the punch at the time of a forge life about the trial manufacture punch of the sample number 10 (comparative example).

  The configuration and characteristics of the hard coating layer of the present invention will be described with reference to FIG. FIG. 1 is a diagram for explaining the structure of a hard coating layer when the hard coating layer of the present invention is coated on a base material such as a cold plastic working die.

(First embodiment of hard coating member)
FIG. 1 shows a first embodiment of the hard coating layer of the present invention, and shows a cross section of the hard coating layer 2 formed (formed) on the surface of the substrate 1. The base material 1 is, for example, a cold plastic working die, and shows a cold forging die, various forming dies, and the like. The hard coating layer 2 includes an A layer 3 containing a predetermined amount of a predetermined element and a B layer 4 containing a predetermined amount of the predetermined element, and a plurality of A layers 3 and B layers 4 are alternately laminated. It is composed of a laminated structure 5. Reference numeral “6” shown in FIG. 1 is an underlayer formed on the surface of the substrate 1, and reference numeral “7” is a surface layer formed on the surface of the hard coating layer 2. The hard coating layer 2, the base layer 6, and the surface layer 7 that form the laminated structure 5 are formed by, for example, an arc ion plating method. The underlayer 6 and the surface layer 7 described above will be described later.

  In the hard coating layer 2 of the present invention, the layer thickness (dA) that is a single thickness of the A layer 3 that forms the laminated structure and the layer thickness (dB) that is also the single thickness of the B layer 4 are respectively The thickness is 50 nm or less, and the layer thickness ratio (film thickness ratio) obtained by dividing the layer thickness of the B layer 4 by the thickness of the A layer 3 (dB / dA) is 0.1 to 0.5. Thus, the film thickness of the hard coating layer 2 having a laminated structure is set to 1 to 5 μm.

  As the base material 1 of the cold plastic working die according to the present invention, a cemented carbide, an iron-based alloy having a metal carbide, ceramics, high-speed tool steel, or the like can be used, but is not limited thereto. Instead, any material can be used as long as it can be applied to members such as jigs and tools. In particular, a cemented carbide containing Cr having a WC (tungsten carbide) average particle size of 0.8 to 3 μm and a Co content of 8 to 15% by weight is used as a cold plastic working die. Is preferred.

(Hard film layer thickness and composition)
The hard coating layer 2 of the present invention has the following characteristics.
[Film thickness]
As described above, the film thickness of the hard coating layer 2 having a laminated structure in which the A layers 3 and the B layers 4 are alternately laminated (the film thickness of the laminated structure 5) is 1 to 5 μm.
[composition]
The composition of the hard coating layer 2 is represented by the general formula _{"Ti a Cr b Al c Si d} M e (B u C v N w). However, M is at least one of Nb, V, The a, b, c, d, e, u, v, and w are atomic ratios of the elements Ti, Cr, Al, Si, M, B, C, and N, respectively.
[ Composition in the range in which the diameter arbitrarily selected in the cross section in the thickness direction of the hard coating layer 2 is 1 μm ]
In the cross section in the thickness direction of the hard coating layer 2 having the composition represented by the above general formula, the composition within a range of an arbitrarily selected diameter of 1 μm satisfies the following conditional expression.
0.3 <a ≦ 0.6,
0 <b ≦ 0.2,
0.2 ≦ c <0.5,
0 <d ≦ 0.1,
0 ≦ e ≦ 0.2,
0 ≦ u ≦ 0.1,
0 ≦ v ≦ 0.3,
0 <w ≦ 1,
a + b + c + d + e = 1,
u + v + w = 1 .

[Composition of layer A and layer B]
The composition of the A layer 3 satisfies the following conditional expression with respect to the atomic ratio of Ti, Cr, and Si among the constituent elements constituting the above general formula indicating the composition of the hard coating layer 2.
0 ≦ b ≦ 0.1,
0 ≦ d ≦ 0.01,
b <a,
Similarly, the composition of the B layer 4 satisfies the following conditional expression with respect to the atomic ratio of Ti, Al, Cr, and Si among the constituent elements constituting the above general formula indicating the composition of the hard coating layer 2. I have to.
0 ≦ a <0.3,
0.1 <b ≦ 0.3,
0.3 ≦ c <0.7,
0.01 <d ≦ 0.1,
b> a,

[Layer thickness and layer thickness ratio of layer A and layer B]
Each of the A layer 3 and the B layer 4 has a thickness of 50 nm or less, and has a stacked structure in which a plurality of A layers 3 and B layers 4 are alternately stacked. The layer thickness (thickness) of the A layer 3 is dA and B layers. When the layer thickness (thickness) of 4 is dB, the layer thickness ratio (dB / dA) value is
dB / dA = 0.1-0.5,
Has been made.

Regarding the hard coating layer 2 of the present invention, the reason why the composition within the range of the diameter of 1 μm arbitrarily selected in the cross section in the thickness direction is set so as to satisfy the above formula is as follows. .

(Ti: 0.3 <a ≦ 0.6, Cr: 0 <b ≦ 0.2, (a + b + c + d + e = 1)) Ti and Cr are used to refine the columnar structure of the hard coating layer 2 by adding Al and Si. It is an element to be added in order to suppress the balance and maintain the balance between hardness and toughness. That is, if the addition amount of Ti and Cr is too large, the hardness is lowered and the wear resistance is lowered. On the other hand, when the addition amount of Ti and Cr is too small, the columnar structure is refined and the toughness is lowered, so that the crack resistance is lowered. In order to exhibit the effect of adding Ti and Cr, it is necessary that a, which is the atomic ratio of Ti, exceeds 0.3 and 0.6 or less, and b, which is the atomic ratio of Cr, exceeds 0 and is 0.2 or less. is there.

About (Al: 0.2 ≦ c <0.5, Si: 0 <d ≦ 0.1, (a + b + c + d = 1)) Al and Si are used to improve the hardness and oxidation resistance of the hard coating layer 2. It is an element to be added. That is, when the amount of Al and Si added is too large, the columnar structure becomes finer, the hard coating layer becomes brittle, and there is a tendency that peeling or abnormal wear occurs. On the other hand, if the addition amount of Al and Si is too small, the hardness tends to decrease, and therefore the wear resistance decreases. In order to exert the effect of addition of Al and Si, it is necessary that c, which is the atomic ratio of Al, is 0.2 or more and less than 0.5, and d, which is the atomic ratio of Si, is more than 0 and less than 0.1. . In addition, since the increase in Al content deteriorates the surface roughness of the film and the wear resistance deteriorates when applied to a cold plastic working die, the atomic ratio c of the hard film layer 2 In the cross section in the thickness direction, it is necessary that the arbitrarily selected diameter does not exceed 0.5 in the composition in the range of 1 μm .

(M: 0 ≦ e ≦ 0.2, (a + b + c + d + e = 1)) M is one or more of Nb and V, and may not be contained, but the main effect of adding Nb and / or V is Similar to Ti and Cr. That is, the hard coating layer 2 is an element added to prevent the columnar structure from being refined by the addition of Al and Si and to maintain a balance between hardness and toughness. On the other hand, the addition of M slightly improves the hardness of the A layer 3 and contributes to the improvement of wear resistance. If the amount of Nb and / or V added is too large, the hardness will decrease and the wear resistance will decrease. On the other hand, if the addition amount of Nb and / or V is too small, the columnar structure is refined and the toughness is lowered, so that the crack resistance is lowered. In order to exhibit the effect of adding Nb and / or V, e, which is the atomic ratio of Nb and / or V, needs to be 0.2 or less.

About (B: 0 ≦ u ≦ 0.1, C: 0 ≦ v ≦ 0.3, N: 0 <w ≦ 1, (u + v + w = 1)) B and C add high hardness to the hard coating layer 2 And low friction. However, when B exceeds 0.1 in atomic ratio, the columnar structure becomes coarse and the hardness decreases. On the other hand, if C exceeds 0.3 in atomic ratio, the hard coating layer 2 becomes amorphous and the hardness decreases. Therefore, B and C may be added in an atomic ratio of 0.1 or 0.3, respectively. Since N plays a role of forming a nitride of the hard coating layer 2 in the present invention by combining with a metal element, an atomic ratio of 0.6 or more is necessary.

(Laminated structure)
As described above, the hard coating layer 2 having the laminated structure 5 has a laminated structure in which the A layer 3 and the B layer 4 are alternately laminated with a layer thickness of 50 nm or less. A characteristic is that the (dB / dA) value, which is the layer thickness ratio (film thickness ratio) when the single thicknesses of each are dA and dB, is set to 0.1 to 0.5.

  By forming the hard coating layer 2 in a laminated structure having such a layer thickness ratio, the crystallinity of the B layer 4 is improved by the high toughness characteristics of the A layer 3 and the toughness of the hard coating layer 2 is improved. Further, the high hardness characteristic of the B layer 4 improves the wear resistance of the A layer 3. Thus, the defects of the respective layers are complemented by using a laminated structure while taking advantage of the characteristics inherent to the A layer 3 and the B layer 4 themselves. As a result, when the hard coating layer 2 of the present invention is formed on the surface of the cold plastic working mold, the durability of the mold (due to the crack resistance and wear resistance of the hard coating layer 2) (Lifetime) can be remarkably improved. Further, the fine columnar structure of the B layer 4 improves the hardness of the A layer 3 and significantly improves the wear resistance of the hard coating layer 2 formed on the cold plastic working mold.

  In addition, when each layer thickness of A layer 3 and B layer 4 exceeds 50 nm, the characteristic of each of A layer 3 or B layer 4, that is, the characteristic of A layer 3 having poor wear resistance, Due to the poor toughness, the durability of the cold plastic working mold is not improved. When the (dB / dA) value is smaller than 0.1, the characteristic of the A layer 3 having poor wear resistance appears strongly, and the durability of the cold plastic working die is not improved. On the other hand, if the (dB / dA) value is larger than 0.5, the characteristics of the B layer 4 that are poor in toughness appear strongly, abnormal wear occurs in the hard coating layer, and the durability of the cold plastic working mold is improved. do not do. Therefore, in the present invention, the (dB / dA) value is set to 0.1 to 0.5. The (dB / dA) value is more preferably set to 0.1 to 0.3, and the durability of the cold plastic working die can be further improved. The layer thickness (film thickness) of the A layer 3 and the B layer 4 can be measured by cross-sectional observation with a transmission electron microscope.

(Hard film layer thickness)
In the present invention, the thickness of the hard coating layer 2 having a laminated structure is 1 to 5 μm. The reason for this is that when the film thickness is less than 1 μm, the effect of improving the durability of the cold plastic working mold is poor, while when it exceeds 5 μm, the hard coating layer 2 is easily peeled off from the substrate 1. . Therefore, the film thickness of the hard coating layer 2 is preferably 1 to 5 μm.

[Composition of layer A]
A layer 3, the hard coating layer formula composition described _{above: Ti a Cr b Al c Si} d M consists _{e (B u C v N w} ), wherein a, b, c, d, e, u, v , W is the atomic ratio of the elements Ti, Cr, Al, Si, M, B, C, N, respectively, the following conditions:
0.3 <a ≦ 0.6,
0 ≦ b ≦ 0.1,
b <a,
0.2 ≦ c <0.5,
0 ≦ d ≦ 0.01,
0 ≦ e ≦ 0.2,
0 ≦ u ≦ 0.1,
0 ≦ v ≦ 0.3,
0 <w ≦ 1,
a + b + c + d + e = 1,
u + v + w = 1,
It is a film that satisfies

As described above, the A layer 3 having the above composition has a laminated structure having a predetermined number of layers alternately with the B layer 4 to increase the hardness of the A layer 3 and at the same time, the crystallinity of the B layer 4. To increase the toughness, and as a result, it has a function of simultaneously improving the crack resistance and wear resistance of the hard coating layer 2. Here, the total number of laminations (number of laminations) is 100 when the combination of one A layer and one B layer is one lamination number, for example, when the thickness of the hard coating layer 2 is 2 μm. About 400 times is preferable in terms of crack resistance and wear resistance of the hard coating layer 2.
In addition, in the cross section in the thickness direction of the hard coating layer 2 in the layer A 3 described above, an element different from the composition range in the range of the arbitrarily selected diameter of 1 μm is Cr atomic ratio b, Si Atomic ratio d. The reason why the composition of the A layer 3 is different from the composition in the range of 1 μm in the diameter selected in the cross section in the thickness direction of the hard coating layer 2 is as follows.

When the atomic ratio b of Cr exceeds 0.1, the columnar structure of the hard coating layer 2 becomes coarse and the hardness is lowered, so that the durability of the cold plastic working die is lowered. When the atomic ratio d of Si exceeds 0.01, the columnar structure of the hard coating layer 2 is excessively refined and crack resistance is lowered, so that the durability of the cold plastic working die is lowered.
In addition, in the relationship between the atomic ratio a of Ti and the atomic ratio b of Cr, the atomic ratio a of Ti is increased. The reason for this is that if the Cr atomic ratio b is greater than the Ti atomic ratio a, the hardness of the hard coating layer 2 decreases and wear resistance decreases, and as a result, the durability of the cold plastic working mold is reduced. This is because of the decrease.

  As described above, since the A layer 3 includes Ti, Al, and N as essential components, and Cr, Nb, V, Si, B, and C are optional components, the combination related to the composition of the A layer 3 is TiAlN. TiAlCrN, TiAlNbN, TiAlVN, TiAlSiN, and the like. N may be any one of (CN), (BCN), and (BN).

[B layer composition]
The B layer 4 is composed of the above-described general formula: Ti _a Cr _b Al _c Si _{d Me} (B _u C _v N _w ), and the a, b, c, d, e, u, v, and w are When the atomic ratio is
0 ≦ a ≦ 0.3,
0.1 <b ≦ 0.3,
b> a,
0.3 ≦ c <0.7,
0.01 <d ≦ 0.1,
0 ≦ e ≦ 0.2,
0 ≦ u ≦ 0.1,
0 ≦ v ≦ 0.3,
0 <w ≦ 1,
a + b + c + d + e = 1,
u + v + w = 1,
It is a film that satisfies The B layer 4 is alternately laminated with the A layer 3 in the above-described predetermined laminated structure, thereby improving the crystallinity of the B layer 4 and increasing the toughness. At the same time, increasing the hardness of the A layer 3, the hard coating layer 2 exhibits the function of improving wear resistance and crack resistance.

Among the compositions of the B layer 4 described above, in the cross section in the thickness direction of the hard coating layer 2, the elements different from the composition range within the range of the arbitrarily selected diameter of 1 μm are Ti atomic ratio a and Cr The atomic ratio b, the atomic ratio c of Al, and the atomic ratio d of Si. Ti does not need to be included, but it is effective to include it when hardness is required. By setting the upper limit to 0.3, it is for cold plastic working within a range that does not impair the toughness of the hard coating layer 2 The wear resistance of the mold is improved. When the atomic ratio b of Cr is 0.1 or less, the wear resistance of the hard coating layer 2 decreases, and when the atomic ratio b of Cr exceeds 0.3, the crack resistance decreases. The durability of the mold is reduced. When the atomic ratio c of Al is less than 0.3, the heat resistance of the hard coating layer 2 is lowered, so the wear resistance of the cold plastic working mold is lowered, and the atomic ratio c of Al is 0.7 or more. Then, since the hardness is lowered, the wear resistance of the cold plastic working die is lowered.
Moreover, when the atomic ratio d of Si is lower than 0.01, the wear resistance of the hard coating layer 2 is lowered, and when the atomic ratio d of Si exceeds 0.1, the columnar structure of the hard coating layer 2 is excessive. Since it becomes finer, the wear resistance of the B layer can be improved by defining the atomic ratio d of Si to 0.01 <d ≦ 0.1.
Further, in the relationship between the atomic ratio a of Ti and the atomic ratio b of Cr, the atomic ratio b of Cr is increased. This is because the wear resistance of the hard coating layer 2 is lowered when the atomic ratio a of Ti is larger than the atomic ratio b of Cr, so that the durability of the cold plastic working die is lowered.

  As described above, in the B layer 4, Cr, Al, Si, and N are essential components, and Ti, Nb, V, B, and C are optional components. Are TiCrAlSiN, TiCrAlSiNbN, TiAlCrAlSiVN, AlCrNbSiN, and the like. N may be any one of (CN), (BCN), and (BN).

(Underlayer and surface layer)
In the first embodiment relating to the hard coating layer 2 of the present invention shown in FIG. 1, the base layer 6 is formed on the surface of the mold base 1, and the hard coating layer 2 is formed on the surface (surface) of the base layer 6. Further, an example in which the surface layer 7 is formed on the surface of the hard coating layer 2 is shown. In the present invention, the composition of the base layer 6 is the composition of the A layer 3 described above.
The hard coating layer 2 of the present invention has a laminated structure in which the A layer 3 and the B layer 4 are alternately laminated. However, the adhesion strength between the mold base 1 and the hard coating layer 2 varies, and the cold coating layer 2 is cooled. It may cause abnormal damage in the mold for interplastic working. However, the adhesion between the mold base 1 and the hard coating layer 2 can be improved by coating the surface of the mold base 1 with the base layer 6 made of the A layer. The durability of the cold plastic working die can be further improved by setting the layer thickness of the underlayer 6 made of the A layer 3 in the range of 0.3 to 3 μm.

The composition of the surface layer 7 formed on the surface of the hard coating layer 2 may be the same as that of the A layer 3 or the B layer 4, and the layer thickness is most preferably about 0.1 to 2 μm. The reason why it is desirable to form the surface layer 7 is as follows.
That is, since the hard coating layer 2 of the present invention is composed of a laminated structure of the A layer 3 and the B layer 4, the outermost surface of the hard coating layer 2 is covered with the A layer 3 or the B layer 4, Color unevenness is likely to occur in the hard coating layer 2. This color unevenness is not preferable in terms of quality control, and there is a possibility that the durability of the cold plastic working mold may vary. For this reason, it is preferable to coat the surface of the hard coating layer 2 with a surface layer 7 as shown in FIG.

(Second and third embodiments of the hard coating layer)
In the first embodiment of the hard coating layer 2 shown in FIG. 1, an example in which both the base layer 6 and the surface layer 7 are formed is shown, but only the base layer 6 is formed as shown in FIG. The surface layer 7 may not be formed (second embodiment of the hard coating layer). Moreover, as shown in FIG. 3, you may form only the surface layer 7 without forming the base layer 6 (3rd Embodiment of a hard film layer).
Also in these second and third embodiments, the composition of the underlayer 6 is the same as that of the A layer 3 as in the first embodiment of the hard coating layer 2 shown in FIG. It is desirable to make it ~ 3 μm. Similarly, the composition of the surface layer 7 is preferably the same as that of the A layer 3 or the B layer 4 and the film thickness is preferably 0.1 to 2 μm.
In order to further improve the durability of the cold plastic working mold coated with the hard coating layer 2 of the present invention, both the base layer 6 and the surface layer 7 are formed as shown in FIG. Is desirable.

(Embodiment to cold plastic working mold)
Next, an embodiment of a cold plastic working die coated with the hard coating layer 2 of the present invention will be described. Among the cold plastic working dies, the cold forging dies used in particularly harsh environments are in a closed area and at a high speed (more than 50 shots per minute). Since a tensile stress and a compressive stress are repeatedly applied to the metal, fine cracks are likely to be generated on the mold surface as compared with a mold for other uses. Therefore, the hard coating layer formed on the mold surface is required to have crack resistance against repetitive stress, and at the same time, wear resistance. By covering the mold for such use with the hard coating layer 2 of the present invention, the durability of the mold can be remarkably improved. Especially, the durability improvement of a metal mold | die becomes more remarkable by coat | covering the metal film | membrane used for back extrusion molding among the metal mold | die for cold forging, especially the hard film layer 2 to a punch.
Hereinafter, as an embodiment of a cold plastic working die according to the present invention, a punch used as a cold forging die will be described as an example.

4 shows a plan view of the punch 10 as an example of a cold forging die, and FIG. 5 shows an enlarged view of a portion E shown in FIG. The punch 10 shown in FIG. 4 (FIG. 5) has a substantially cylindrical shape. The punch 10 having a substantially cylindrical shape includes a gripping part 11 for causing a forging device to grip, a function part 12, and an upper end part 13 serving as an end face of the function part 12. The functional part 12 has a length L1 with respect to the longitudinal (axial) direction of the punch 10, and the gripping part 11 has a length L2. Since the functional part 12 including the upper end part 13 is a part that contributes to cold forging on the workpiece, the hard coating layer 2 of the present invention is formed (covered) on the surface of the functional part 12.

FIG. 5 is an enlarged view of a portion E in the tip portion 14 of the punch 10 shown in FIG. 4 and shows a part of the upper portion of the punch 10 in the longitudinal direction. As shown in FIG. 5, the tip portion 14 of the punch 10 includes an upper end portion 13, a bearing portion 15, a diameter reducing portion 16, and a relief portion 17. A diameter reduced portion 16 in which the diameter of the punch 10 is reduced by a gradient of the relief angle α is provided from the bearing portion 15 to the relief portion 17, and the diameter reduced portion 16 is provided at the relief ridge line portion 18 that is one end (vertex) thereof. Is configured to be integrally connected to the bearing portion 15. Further, the upper end portion 13 is a surface having a conical shape that is gently inclined in the direction of the central portion of the upper end portion 13 with a gradient of the tip angle β with respect to a plane orthogonal to the longitudinal direction of the punch 10. The outer peripheral edge portion 13 a of the upper end portion 13 forming the conical surface is formed with an arc-shaped portion 19 over the entire circumference, and the arc-shaped portion 19 is integrally connected to the bearing portion 15. Further, the connecting portions of the bearing portion 15, the diameter reducing portion 16, and the relief portion 17 may be connected in a smooth circular arc shape although not shown.
The tip angle β described above may be 0 °, that is, the upper end portion 13 may have a plane surface. Even in this case, the outer peripheral edge portion 13a of the upper end portion 13 is provided with the arc-shaped portion 19 over the entire circumference.

  In the punch 10 according to the present invention, the arc radius of the arc-shaped portion 19 is preferably set to 1 mm or less. This is because it is considered that the balance between the crack resistance and the wear resistance with respect to the hard coating layer 2 is optimized by setting the arc radius of the arc-shaped portion 19 to 1 mm or less. On the other hand, when the sliding resistance is relatively high such that the arc radius of the arc-shaped portion 19 exceeds 1 mm, the arc-shaped portion 19 or a hard layer coating in the vicinity thereof during cold forging. Abnormal wear may easily occur starting from the layer 2.

(Hard film formation on cold plastic working mold)
When the hard coating layer 2 of the present invention is formed on the surface of the functional portion 12 of the punch 10 shown in FIG. 4 (FIG. 5), the film thickness of the upper end portion 13 is the bearing portion 15, the diameter reducing portion 16, and the relief portion 17. Cover to be thicker. Thereby, the durability of the punch 10, particularly the durability of the upper end portion 13 can be further improved.
Generally, as described in Patent Document 6, when a high hardness coating layer is coated on the upper end portion 13 rather than the relief portion 17 or the like, the coating layer on the upper end portion 13 is cracked to cause abnormal wear on the punch. It was easy to occur. However, as described above, the hard coating layer 2 of the present invention also has crack resistance in addition to excellent wear resistance, and the thickness of the hard coating layer 2 formed on the upper end portion 13 is reduced by the relief portion 17. Even if the bearing 15 and the diameter-reduced portion 16 are coated so as to be thicker, such abnormal wear is suppressed. In particular, the thickness ratio of the upper end portion 13 to the relief portion 17 is more than 1 and less than 2.5 (the thickness of the upper end portion 13 is more than 1 and less than 2.5 times the thickness of the relief portion 17). The most excellent durability can be obtained.

(Method for forming hard coating layer)
Regarding the formation (film formation) of the hard coating layer 2 according to the present invention on a mold such as a punch 10, the hard coating layer 2 contains many elements in the A layer 3 and the B layer 4 constituting the laminated structure. Therefore, it is necessary to accurately control the composition of each layer. For this reason, it is most preferable to form the hard coating layer 2 using an arc ion plating method using a solid evaporation source. This is because the arc ion plating method has a high ionization rate when each atom contained in the target is evaporated, and a dense film can be formed by a bias voltage applied to the substrate.

  In order to form a hard coating layer on the base material of the punch 10, ultrasonic degreasing cleaning is first performed on the base material of the punch 10 having a predetermined size as a pretreatment. Next, after inserting the base material of the ultrasonic degreased and washed punch 10 at a predetermined position in the film forming apparatus, the base material is held at a predetermined temperature of 400 to 550 ° C., and arc ion plating is performed. A hard coating layer is formed on the base material of the punch 10 by the method. Thereby, it is possible to manufacture a punch for a cold plastic working mold in which a hard coating layer having a predetermined composition and a laminated structure is formed.

  A specific film forming method will be described as follows. Various alloys or metal targets are attached to the cathode of the film forming apparatus, and further, the base material of the punch 10 serving as an object to be processed is attached on a support base on the rotating base material stage 35 (see FIG. 6). Further, the fixing of the punch 10 as the object to be processed may be a so-called self-revolution process that further rotates on the rotating substrate stage 35.

Next, the inside of the chamber (vacuum container) is evacuated (exhaust to 5 × 10 −3 Pa or less) to be in a vacuum state. Next, the temperature of the object to be processed is heated to about 500 ° C. with a heater installed in the chamber, and etching with Ar ions is performed for about 5 minutes by an ion source by thermionic emission from the filament.
Subsequently, a nitride film of the target component is formed by arc ion plating using the target with an arc evaporation source in an N ₂ atmosphere with an arc current of 150 A and a total pressure of 3.2 Pa. At this time, when the carbonitride film is used, the carbonitride film of the target component is similarly formed by arc ion plating in an atmosphere in which a gas containing carbon is added in addition to N ₂ gas. To do. Further, when a boron-containing film is used, a boron-containing nitride or carbonitride film is similarly formed by arc ion plating using a boron-containing target.

  In addition, the target of a different composition is attached to a plurality of evaporation sources, the base material of the punch 10 is placed on the support base of the rotating base material stage, and the base material of the punch 10 is rotated together with the base material stage during film formation. By laminating, it is possible to form a laminated hard coating layer. At this time, when the base material of the punch 10 alternately passes in front of the evaporation source to which the target having a different composition is attached as the substrate stage rotates, the coating corresponding to the target composition of each evaporation source is alternately It is formed on the surface of the base material of the punch 10. This makes it possible to form a hard coating layer having a laminated structure.

  The layer thicknesses of the A layer 3 and the B layer 4 constituting the laminated structure are the distance between the base material of the punch 10 and the target surface, the input power (evaporation amount) to each evaporation source, and the rotational speed of the base material stage. And it can control based on the accumulated value of the rotation speed. In addition, if it controls so that the rotational speed of a base material stage may become high, the thickness of the membrane | film | coat per rotation of a base material stage will become thin.

  In the film formation on the base material of the punch 10, a method of forming a film in which the film thickness of the upper end portion 13 is thicker than the relief portion 17 that is a peripheral surface facing the longitudinal direction of the punch 10 is the punch 10. When the base material passes through the front surface of the target, the punch 10 is placed on the base material stage with the upper end portion 13 facing the target surface.

The base material of the punch 10 coated with the hard coating layer based on the above-described procedure is the adhesion of metal particles called droplets inevitably mixed during film formation, the crystal grain size of the coating layer, the unevenness of the substrate surface Thus, the surface roughness of the hard coating layer is worse than that before coating. Therefore, after the hard coating layer is formed, the surface of the hard coating layer is buffed with a buff containing hard particles such as diamond particles to obtain a smoothed hard coating layer 2 having a predetermined surface roughness. Like that. Thereby, the punch 10 in which the hard coating layer 2 is formed can be manufactured.
In addition, based on the above-described film forming procedure, the above-described underlayer 6 can be formed on the surface of the base material of the punch 10, and the surface layer 7 can be formed on the surface of the hard coating layer 2.

  Examples of the present invention will be described below. An experiment for evaluating the durability of the hard coating layer 2 according to the present invention and a cold plastic working mold coated with the hard coating layer 2 was performed. In order to perform this experiment, as a cold plastic working die, the punch of the die composed of a punch and a die, the present invention example in which a hard coating layer was formed, and 25 kinds of cold forgings as comparative examples A prototype punch was made. The prototype punches were made of cemented carbide and used CIS standard VM30 (CIS019D classification). And the punch base material (henceforth "the punch base material 34") which gave the shape which gave grinding and cutting to the raw material which consists of this cemented carbide alloy was manufactured. In addition, this punch base material 34 is a surface of a punch function part (function part 12 having a length L1 shown in FIG. 4) that becomes a contact part (contact part with the work to be forged) at the time of forging. The surface roughness (Ra) of the functional part was 0.03 μm, and the surface roughness (Ry) was 0.3 μm.

  The shape of the tip portion of the punch base 34 is such that the diameter of the bearing portion is 12.35 mm, the diameter of the escape portion is 12.15 mm, the arc radius of the arc-shaped portion (arc-shaped portion 19 shown in FIG. 4) is 0.5 mm, The relief angle α is 5 °, the tip angle β of the tip is 4 °, and the bearing portion 15 and the diameter reducing portion 16 are smoothly connected. The length (L1) of the punch functional part 12 was set to 105 mm, and the length (L2) of the punch holding part 11 was set to 30 mm.

  For the 25 types of punch base material 34 having the above specifications, a film forming apparatus having a plurality of arc evaporation sources on the surface thereof, that is, on the surface of the functional unit 12 of the punch 10 shown in FIG. A prototype punch with a hard coating layer having the specifications shown was manufactured. In the following description, the reference numerals and names of each part of the punch base material 34 and the prototype punch will be described using the reference numerals and names shown in FIGS. 4 and 5.

FIG. 6 shows a schematic configuration of the film forming apparatus 30 used in this experiment. Hereinafter, a procedure for forming a hard coating layer on the punch base material 34 using the film forming apparatus 30 will be described.
First, various alloys or metal targets (not shown) were attached to the cathode (A) 32 and the cathode (B) 33 provided in the vacuum container 31 of the film forming apparatus 30. And the punch base material 34 which performed ultrasonic degreasing washing | cleaning in the hydrocarbon-type solvent was attached on the support stand (not shown) on the base-material stage 35. As shown in FIG. At this time, the upper end portion 13 (upper end portion 13 shown in FIG. 4) of the punch base material 34 was mounted on a support base (not shown) on the base material stage 35 so as to face the target.
Subsequently, the inside of the vacuum vessel 31 is evacuated (evacuated to 5 × 10 −3 Pa or less) to be in a vacuum state, and then the temperature of the punch base 34 is heated to 500 ° C. by a heater (not shown), In order to clean the surface of the base material 34, Ar is ionized by an ion source generated by thermionic emission from a filament (not shown), and a bias voltage is applied to the base material stage 35. Etching was performed with Ar ions for about 5 minutes.

  Subsequently, a mixed gas obtained by adding nitrogen gas and, if necessary, a gas containing carbon to nitrogen gas is introduced into the vacuum vessel 31, and when the pressure in the vacuum vessel 31 reaches 3.5 Pa, it is an arc evaporation source. A discharge current 150A is applied to the cathode (A) 32 and the cathode (B) 33, and a bias voltage is applied while rotating the substrate stage 35 in the R direction at a predetermined rotation speed, whereby a predetermined voltage is applied to the punch substrate 34. A hard coating layer having a thickness was formed. Note that reference numerals “36” and “37” shown in FIG. 6 are arc power supply apparatuses, and reference numeral “38” is a bias power supply apparatus.

  For the formation of a hard coating layer having a laminated structure, a base material on which a punch base material 34 is mounted by attaching a target having the composition of the A layer 3 and the B layer 4 to the cathode (A) 32 and the cathode (B) 33. The stage 35 was rotated in the R direction. First, only the target of the A layer 3 is discharged alone in a predetermined atmosphere containing the nitrogen gas described above, a bias voltage of −40 V is applied to the punch base material 34, and the base layer 6 having a thickness of 0.5 μm. Formed. Thereafter, the target having the composition of the A layer 3 and the B layer 4 is discharged at the same time, and a bias voltage of −40 V is applied to the punch base material 34 and the base material stage 35 is rotated. A hard film layer having a laminated structure 5 laminated alternately in this order was formed on the surface of the punch base 34. In this film formation, the total film thickness of the hard coating layer formed on the punch base material 34 was set to 2 μm, 2.5 μm, or 3 μm.

In the film formation of the hard coating layer described above, the method for controlling the (dB / dA) value, which is the layer thickness ratio of the A layer 3 and the B layer 4, is as follows. Changing the distance (distance between target substrates) L3 and the arc discharge current applied to the deposition targets corresponding to the A layer 3 and the B layer 4 in the range of 80 to 150 A, and further rotating the substrate stage 35 Control was based on the cumulative value of speed and rotation speed. That is, by increasing the distance L3 between the target substrates, decreasing the arc discharge current applied to the target, and increasing the rotation speed of the substrate stage 35, a single film of the A layer 3 and the B layer 4 is obtained. The thickness can be reduced.
In this example, except for sample numbers 9 and 10 shown in Table 1, the distance L3 between the target substrates and the arc applied to the target so that the single film thickness of the A layer and the B layer is 50 nm or less. The discharge current and the rotation speed of the substrate stage 35 were controlled. After the hard coating layer was formed on the punch base material 34, film formation was performed by subsequently coating the surface of the hard coating layer with the surface layer 7 having the composition of A layer or B layer having a thickness of 1 μm. Then, after the temperature of the punch base material 34 for which the film forming process was completed became 200 ° C. or less, the punch base material 34 was taken out from the vacuum vessel 31.

  For the punch base material 34 on which the hard coating layer was formed by the above procedure, the surface of the functional part 12 of the punch base material 34 is mirror-polished again, and the surface roughness (Ra) of the functional part 12 is 0.05 μm or less. 25 types of prototype punches 41 (sample numbers 1 to 25 shown in Table 1) having surface roughness (Ry) of 0.5 μm or less were produced.

In the cross section in the thickness direction of the hard coating layer formed on the punch base material 34, the measurement of the composition in the range of the arbitrarily selected diameter of 1 μm was performed by energy dispersive X-ray analysis. In addition, the composition of the A layer and B layer constituting the hard coating layer was separately prepared by coating each single layer with 2 μm or more under the same film formation conditions described above, and similarly analyzed by energy dispersive X-ray analysis. did.

(Cold forging experiment)
Subsequently, in order to evaluate the durability of the trial punch 41 having a hard coating layer formed by the above-described procedure, an experiment of cold forging using this punch as a die for cold forging was performed. FIG. 7A and FIG. 7B are diagrams for explaining the cold forging experimental method. Hereinafter, an experimental method for cold forging will be described with reference to FIG.

  In FIG. 7, reference numeral “40” indicates a schematic diagram of a backward extrusion molding process (hereinafter referred to as “backward extrusion molding process 40”) in the cold forging method. The backward extrusion molding process 40 includes at least a prototype punch 41 in which a hard coating layer is formed based on the above-described procedure as a cold working mold, a base punch 42, a die 43, and a frame body 44. . 7A shows a state before the extrusion punched product is plastically processed with the prototype punch 41, and FIG. 7B shows a state after the extrusion molded product is plastic processed with the prototype punch 41. FIG.

  When backward extrusion molding is performed on the workpiece, as shown in FIG. 7A, for example, a workpiece 45 having a cylindrical shape is inserted into the hole 43 a of the die 43, so that Next, driving for moving the prototype punch 41 up and down in the F direction, that is, driving the prototype punch 41 in the hole 43a of the die 43 by shot and plasticizing the workpiece 45 by cold forging. Processing (molding by plastic processing) was performed to process the workpiece 45 into an extruded product having a bottomed cylindrical shape.

  In this backward extrusion molding, the material of the workpiece 45 was S45C (carbon steel for machine structure). Further, the workpiece 45 is subjected to annealing and bond treatment (phosphate treatment) at the time of drawing the workpiece to the raw material, and then cutting, cutting edge correction and drawing using a parts former. It manufactured through the process to perform.

In this plastic working by cold forging, plastic working consisting of a backward extrusion process in which the cross-section reduction rate of the work piece 45 is 70% and the forming depth is about 5 times the diameter is performed, and is shown in FIG. 7B. As described above, the durability of the prototype punch 41 was evaluated while sequentially forming a forged molded product (extruded product) 46 having a cylindrical shape having a cylindrical portion 46a and a bottom portion 46b.
In this backward extrusion molding, the forging molding stress acting on the surface of the upper end portion 13 of the prototype punch 41 is about 2500 MPa, the number of shots per minute is 60 shots, and the lubricating oil contains a sulfur-based extreme pressure additive. The water-insoluble forging oil thus prepared was directly supplied to the trial punch 41.

  The durability of the prototype punch 41 was evaluated based on the following procedure. That is, when 25 workpiece prototype punches 41 are sequentially used and the workpiece 45 is plastically processed by the backward extrusion molding described above, whether or not vertical stripes are generated on the inner surface of the cylindrical portion 46a of the extruded product 46. Judged. This vertical streak is prominently generated, and it is determined whether or not the vertical streak causes an error of ± 0.01 mm in the inner diameter dimension of the extruded product 46 with respect to the target dimension. The cumulative number of shots at the time when this occurred was determined as the forging life, that is, the life due to damage of the prototype punch 41.

Tables 1 and 2 show the results of durability evaluation experiments for the 25 types of prototype punches 41 described above.
Table 1 shows the composition of each of the 25 prototype punches (sample numbers 1 to 25) in the range of 1 μm in the diameter selected arbitrarily in the cross section in the thickness direction of the hard coating layer formed. Atomic ratio). Table 2 shows the composition (atomic ratio) of the A and B layers constituting the hard coating layer, the thickness of the A layer (dA), and B for each of the 25 prototype punches (sample numbers 1 to 25). Layer thickness (dB), number of laminations, hard coating layer thickness, (dB / dA) value, coating type of base layer and surface layer (distinguish between A layer and B layer), forging life (10,000 shots) Information on items related to, is described. Of these, the number of laminations is the total number of laminations when the combination of one A layer and one B layer is one. The film thickness of the hard coating layer indicates the film thickness of the hard coating layer itself that does not include the base layer and the surface layer.

  In addition, when the symbol “↑” is displayed in the vertical column in which the composition (atomic ratio) of each element contained in the A layer and the B layer for each sample number in Table 2 is displayed, the upper row It is shown that the same composition as that of the sample number is used, and that the target having the same composition was used. Moreover, the sample number in which the composition value of each element is described indicates that the film was formed by changing the target. In Table 2, when the symbol “-” is written in the element symbol column of the A layer and the B layer, it indicates that the A layer or the B layer is not formed, and this sample number has (dB / Since there is no dA) value, “-” is also written in the (dB / dA) column. When "-" is described in the column of the underlayer and the surface layer, it indicates that the underlayer or the surface layer is not formed.

Among the items shown in Table 1 and Table 2 above, in the cross section in the thickness direction of the hard coating layer, the composition within the range of the diameter of 1 μm arbitrarily selected, and the A layer and B layer constituting the hard coating layer The composition of represents the atomic ratio of elements Ti, Cr, Al, Si, Nb, V contained in each coating layer, and the total of the atomic ratio is 1. The film thickness (dA) of the A layer and the film thickness (dB) of the B layer are each a single layer film thickness. The film thickness of the hard coating layer indicates the film thickness of the relief portion 17 of the prototype punch, and the (dB / dA) value is a value obtained by rounding off the second decimal place. Note that, as described above, the film thickness of the hard coating layer at the tip portion 13 of the prototype punch 41 is in the range of more than 1 time and less than 2.5 times the film thickness of the relief portion 17.

  Further, the forging life (10,000 shots) shown in Table 2 indicates the cumulative number of shots as described above, and the unit of this number is indicated by a numerical value obtained by discarding 10,000 shots or less with 10,000 shots as a unit. In the sample number column of Table 1 (Table 2), it is described whether the prototype punch corresponding to this sample number corresponds to the sample number, which corresponds to the punch of the present invention example or the comparative example. ing.

Next, specifications regarding the hard coating layer formed on each prototype punch 41 will be described based on Tables 1 and 2.
(1) Sample numbers 1 to 8 were samples in which the hard coating layer was formed by changing the (dB / dA) value in the range of 0.1 to 2.0. Sample No. 9 was a sample in which only the A layer was formed with a predetermined film thickness. Sample No. 10 was a sample in which only the B layer was formed with a predetermined film thickness.
(2) Sample No. 11 is a sample in which the base layer is an A layer and the surface layer is a B layer.
(3) Sample numbers 12 to 17 and 22 were samples in which the composition of the A layer was changed, and sample numbers 18 to 21 were samples in which the composition of the B layer was changed.
(4) Sample numbers 23 and 24 were samples that did not cover either the base layer or the surface layer.
(5) Sample number 25 was a sample in which the Si content contained in the A layer and the B layer was increased.

[Evaluation of durability of prototype punch]
The results of the cold forging experiment conducted on the prototype punches 41 according to the sample numbers 1 to 25 based on the above-described cold forging experimental conditions are shown in the “Forging life (10,000 shots)” column of Table 2. From the results of this forging life, the matters described in the following (1) to (5) became clear.

  (1) For sample numbers 1 to 8, the influence of the (dB / dA) value on the forging life was compared. The forging life of Sample Nos. 1 to 5 which is an example of the present invention having a (dB / dA) value of 0.1 to 0.5 was 1260 to 260,000 shots, whereas the (dB / dA) value was 0. Sample Nos. 6 to 8 (Comparative Example) having a thickness of 0.7 to 2.0 had a forging life of 50,000 shots or less. Sample No. 9 as a comparative example is a case where a single layer of A layer is coated, and Sample No. 10 as a comparative example is a case where a single layer of B layer is coated, both of which have a forging life of 20,000 shots or less.

FIG. 8 shows a sample punch 3 having a (dB / dA) value of 0.3 in the trial forging life of the sample No. 3 at the tip end of the upper end portion 13 (the arc-shaped portion serving as the outer peripheral edge portion 13a of the upper end portion). 19) A microphotograph of the vicinity from above, FIG. 9 shows the vicinity of the tip of the upper end of the prototype punch during the forging life of Sample No. 1 of the present invention example having a (dB / dA) value of 0.5. The micrograph figure from above is shown. Further, FIG. 10 shows a microphotograph of the prototype punch during the forging life of the sample number 8 of the comparative example having a (dB / dA) value of 2.0 , as viewed from the upper portion near the tip end of the upper end portion. 8 to 10, the portion having a gentle arc shape corresponds to the tip of the upper end of the prototype punch, that is, the arc shape portion 19 shown in FIG. Imaged as double.

As apparent from FIGS. 8 to 10, as the (dB / dA) value increases, in particular, in the prototype punch of sample number 8 as a comparative example, as shown in FIG. It can be seen that the hard coating layer at is abnormally damaged.
Further, FIG. 11 shows a micrograph (magnification 300 times) in a side view of the vicinity of the tip of the upper end at the forging life of sample number 8 as a comparative example. As shown in FIG. 11, many microcracks were observed on the surface of the hard coating layer in the direction perpendicular to the axis of the prototype punch. From this, it is considered that as the (dB / dA) value increases beyond 0.5, a microcrack occurs in the hard coating layer, and this microcrack causes early damage to the punch.

FIG. 12 shows a photomicrograph (magnification 60 times) of the prototype punch at the forging life of sample number 9 as a comparative example, as viewed from the side near the tip of the upper end. As shown in FIG. 12, sample No. 9 not coated with the B layer had the hard coating layer in the vicinity of the tip of the upper end of the trial punch peeled off, and the base material surface of the trial punch was exposed.
Further, FIG. 13 shows a micrograph (magnification 500 times) in the vicinity of the tip point (arc-shaped portion) of the upper end portion displayed in FIG. Was observed. These micro cracks were recognized as the destruction of the hard coating layer starting from the grain boundary.
FIG. 14 shows a micrograph (magnification: 80 times) of the prototype punch at the forging life of sample number 10 as a comparative example not coated with the A layer, as viewed from the side near the tip of the upper end. Abnormal damage was observed in the hard coating layer near the tip.

  From the above experimental results of durability of the prototype punch, the A layer and the B layer having a predetermined component composition are formed into a laminated structure, and the thickness ratio (dB / dA) of the A layer and the B layer is set to 0. It has been found that the impact resistance and wear resistance of the hard coating layer are improved by setting it to 1 to 0.5, and a remarkably excellent cold mold is obtained. Moreover, it can be judged from the numerical value of each forge life shown in Table 2 that it is more preferable to set (dB / dA) value in the range of 0.1-0.3.

(2) Sample No. 11 (Example of the present invention) shows an example of the present invention when the surface layer is coated with the B layer. Like Sample No. 3 where the surface layer is coated with the A layer, 200,000 shots or more are obtained. A forging life was obtained.
Sample No. 12 (example of the present invention) shows an example of the present invention in which the atomic ratios of Ti, Cr, and Al constituting the A layer are 0.55, 0.05, and 0.40, respectively. A forging life was obtained.
Sample No. 13 (example of the present invention) shows an example of the present invention in which the atomic ratio of Ti, Cr, and Al constituting the A layer is 0.50, 0.10, and 0.40, respectively. A forging life was obtained.
Sample No. 14 (example of the present invention) shows an example of the present invention in which the atomic ratios of Ti, Cr, Al, and Si constituting the A layer were 0.55, 0.05, 0.39, and 0.01, respectively. However, a forging life of 300,000 shots was obtained.
Sample No. 15 (example of the present invention) shows an example of the present invention in which the atomic ratios of Ti, Al, and Nb constituting the A layer are 0.55, 0.35, and 0.10, respectively. A forging life was obtained.
Sample No. 16 (example of the present invention) shows an example of the present invention in which the atomic ratios of Ti, Al, and Nb constituting the A layer are 0.45, 0.35, and 0.20, respectively. A forging life was obtained.
Sample No. 17 (Example of the present invention) shows an example of the present invention in which the atomic ratios of Ti, Al, and V constituting the composition of the A layer are 0.50, 0.40, and 0.10, respectively. A forging life was obtained.
Sample No. 22 (example of the present invention) has Ti, Cr and Al atomic ratios of 0.35, 0.10 and 0.55, respectively, and the composition of B layer is the same as sample No. 21. In this example, the forging life of 200,000 shots was obtained.

  From the results of Sample Nos. 11 to 17 and 22, which are examples of the present invention described above, a B layer having a predetermined component composition and an A layer added with a predetermined amount of Cr, Nb, V, and Si in addition to Ti and Al are laminated. With the structure, and the (dB / dA) value, which is the film thickness ratio of the A layer and the B layer, is 0.1 to 0.5, the impact resistance and wear resistance of the coating layer are improved. It has been found that an excellent cold mold can be obtained.

(3) Sample No. 18 (example of the present invention) has the same composition of the A layer as the sample No. 12, and the atomic ratios of Cr, Al, Si, and Nb constituting the composition of the B layer are 0.12 and 0.63, respectively. , 0.10 and 0.15, the forging life of 250,000 shots was obtained.
Sample No. 19 (example of the present invention) has the same composition of the A layer as that of the sample No. 12, and the atomic ratios of Ti, Cr, Al, and Si constituting the B layer are 0.15, 0.20,. Examples of the present invention with 55 and 0.10 are shown, but a forging life of 320,000 shots was obtained.
Sample No. 20 (example of the present invention) has the same composition of the A layer as the sample No. 12, and the atomic ratios of Ti, Cr, Al and Si constituting the composition of the B layer are 0.24, 0.28,. Examples of the present invention with 38 and 0.10 are shown, and a forging life of 320,000 shots was obtained.
Sample No. 21 (example of the present invention) has the same composition of the A layer as that of the sample No. 12, and the atomic ratios of Ti, Cr, Al, and Si constituting the B layer are 0.25, 0.30,. Examples of the present invention with 37 and 0.08 are shown, and a forging life of 360,000 shots was obtained.

  From the results of the sample numbers 18 to 21 as the above-described examples of the present invention, the A layer and the B layer added with a predetermined amount of Ti, Al, Cr, Nb, V, and Si contained in the A layer and the B layer have a laminated structure, Furthermore, by setting the (dB / dA) value, which is the film thickness ratio of the A layer and the B layer, to 0.1 to 0.5, the impact resistance and wear resistance of the hard coating layer are improved, which is remarkably excellent. It has been found that a cold mold can be obtained.

  (4) Sample No. 23 shows an example of the present invention in which the underlayer is not coated, but a forging life of 150,000 shots was obtained, but abnormal damage was confirmed near the tip of the upper end of the prototype punch, This caused vertical streaks in the product. Sample No. 24 shows an example of the present invention in which the surface layer is not coated, but a forging life of 160,000 shots was obtained, but abnormal damage was also confirmed near the tip of the upper end of the prototype punch. Vertical streaks occurred in the product.

  From the results of Sample No. 23 and Sample No. 24 described above, the hard coating layer is coated with both the base layer and the surface layer to reduce abnormal damage to the hard coating layer near the tip of the upper end of the prototype punch. It has been found that a long forging life can be obtained stably.

(5) Sample No. 25 is 0.12 in the composition in which the atomic ratio of the Si content of the hard coating layer is within a range of an arbitrarily selected diameter of 1 μm in the cross section in the thickness direction of the hard coating layer. Comparative example with 0.1 and 0.15 in B layer shows peeling type damage that peels hard coating layer, and crack resistance is reduced, so forging life is as low as 20,000 shots became.

  From the results of Sample No. 25 described above, it can be determined that by setting the Si content to an atomic ratio of 0.1 or less, the crack resistance of the hard coating layer is improved and a stable long forging life can be obtained.

  Furthermore, a cold forging experiment was also conducted to measure the forging life of a prototype punch on which a hard coating layer containing element B was formed. In this experiment, a target containing B so that the composition of the A layer becomes the composition of the A layer shown in Sample No. 3 of Table 2 (composition: atomic ratios of Ti, Al, and B are 55, 40, and 5, respectively) The B layer was formed using a target having the same composition as the B layer shown in Sample No. 3. At this time, the film thickness of the hard coating layer was 2 μm, the (dB / dA) value was 0.3, and an A layer was formed as an underlayer and a surface layer. The forging life of the prototype punch on which the hard coating layer containing B was formed was 300,000 shots.

In the embodiment and examples of the present invention described above, as an example of a cold plastic working mold in which the hard coating layer 2 according to the present invention is formed, a punch used for a cold forging mold. The cross-sectional shape in the direction orthogonal to the longitudinal direction is circular, and the tip is provided with an upper end (conical portion) for applying a compressive stress of plastic working to the workpiece, backward extrusion molding An example of a punch for use has been described.
The mold for cold plastic working formed with the hard coating layer 2 according to the present invention includes a forward extrusion mold, an upsetting mold, a punching mold, a coining mold, and various press moldings. Includes punches such as metal molds. For example, the cold plastic working die of the present invention includes a punch corresponding to the inner diameter shape of a forged product such as a polygonal shape such as a quadrilateral or hexagonal cross-sectional shape, an elliptical shape, or a gear shape. Punches having a hexagonal cross-sectional shape can be used as molding punches for bolts and nuts. Further, by forming the hard coating layer of the present invention on a die for performing cold plastic working in cooperation with these punches, it is possible to improve the durability of the die.

  As described above, the cold plastic working mold formed with the hard coating layer according to the present invention is not limited to the various punches described above, and plastic working jigs generally referred to as punches or pins, these It includes dies used in combination with punches, punches, pins, or dies. In addition, various ceramics such as iron-base alloy, high-speed tool steel, and cemented carbide can be used as the material.

1: Base material (mold base material)
2: Hard coating layer 3: A layer 4: B layer 5: Laminated structure 6: Underlayer 7: Surface layer 10: Punch 11: Gripping part 12: Functional part 13: Upper end part, 13a: Outer peripheral edge part 14: Punch Tip portion 15: Bearing portion 16: Diameter reducing portion 17: Escape portion 18: Escape ridge portion 19: Arc shape portion 30: Film forming device 31: Vacuum vessel 32: Cathode (A)
33: Cathode (B)
34: Punch substrate 35: Substrate stage 36, 37: Arc power supply device 38: Bias power supply device 40: Backward extrusion process 41: Trial punch 42: Base punch 43: Die, 43a: Hole 44: Frame 45: Workpiece 46: Forged molded product (extrusion molded product), 46a: Cylindrical portion, 46b: Bottom portion L1: Length of punch functional portion L2: Length of punch gripping portion L3: Distance between target and prototype punch ( Target substrate distance)
α: Clearance angle β: Tip angle

Claims (8)

It is a hard coating layer laminated on a substrate, and the film thickness of the hard coating layer is 1 to 5 μm,
The composition of the hard coating layer has the general _{formula: Ti a Cr b Al c Si} d M e (B u C v N w) ( however, M is Nb, 1 or more elements of the V, a, b, c, d, e, u, v, and w are respectively represented by the atomic ratio of Ti, Cr, Al, Si, M, B, C, and N).
In the cross section in the thickness direction of the hard coating layer , the composition in the range of arbitrarily selected diameter of 1 μm is as follows :
0.3 <a ≦ 0.6,
0 <b ≦ 0.2,
0.2 ≦ c <0.5,
0 <d ≦ 0.1,
0 ≦ e ≦ 0.2,
0 ≦ u ≦ 0.1,
0 ≦ v ≦ 0.3,
0 <w ≦ 1,
a + b + c + d + e = 1,
u + v + w = 1,
The filling,
The hard coating layer is composed of the above general formula and, among its constituent elements, the atomic ratio of Ti, Cr, Si,
The following conditions:
0 ≦ b ≦ 0.1,
0 ≦ d ≦ 0.01,
b <a,
A layer comprising a composition satisfying
Similarly, among the constituent elements, regarding the atomic ratio of Ti, Cr, Al, Si,
The following conditions:
0 ≦ a <0.3,
0.1 <b ≦ 0.3,
0.3 ≦ c <0.7,
0.01 <d ≦ 0.1,
b> a,
B layer composed of a composition satisfying the above, each having a thickness of 50 nm or less of the A layer and the B layer, and having a laminated structure in which a plurality of the A layer and the B layer are alternately laminated,
When the thickness of the A layer is dA and the thickness of the B layer is dB, the (dB / dA) value is
dB / dA = 0.1-0.5,
Hard coating layer characterized by being made to.   2. The hard coating layer according to claim 1, further comprising an underlayer formed between a surface of the substrate and the hard coating layer, wherein the composition of the underlayer is composed of the composition of the A layer. Characteristic hard coating layer.   3. The hard coating layer according to claim 1, further comprising a surface layer formed on a surface of the hard coating layer, wherein the surface layer is composed of the composition of the A layer or the B layer. Hard coating layer.   A cold plastic working mold, wherein the hard coating layer according to any one of claims 1 to 3 is formed on a surface of the cold plastic working mold.   5. The cold plastic working die according to claim 4, wherein the cold plastic working die is integrally connected to a bearing portion, and collides with the work piece by shot driving to plastically process the work piece. A die for cold plastic working, characterized by being a punch provided with an upper end for the purpose.   6. The punch according to claim 5, wherein the film thickness of the hard coating layer formed on the upper end is larger than the film thickness of the hard coating layer formed on the other part of the punch. Features a die for cold plastic working.   The punch according to claim 5 or 6, wherein the outer peripheral edge portion of the upper end portion and the bearing portion are connected via an arc shape portion, and the arc radius of the arc shape portion is 1 mm or less. Features a die for cold plastic working.   The punch according to any one of claims 5 to 7, wherein the punch is a punch used for a backward extrusion mold.