JP2019218608A - Die for press of titanium plate, and press molding method of titanium plate - Google Patents

Abstract

To provide a die for press of titanium plate having no generation of press crack or galling trace, and less in abrasion.SOLUTION: There is adopted a die for press of titanium plate having a substrate and a surface treatment coated film, in which the surface treatment coated film has a first plating layer containing Ni formed on the substrate, and a second plating layer containing Ni formed on the first plating layer, the second plating layer contains a fluorine resin particle of 4 to 10 vol.% in a Ni-P plating layer containing P of 3.0 to 10.0 mass% and the balance Ni and impurities, and Vickers hardness is in a range of 500 to 650.SELECTED DRAWING: None

Description

  The present invention relates to a titanium plate pressing die and a titanium plate press forming method.

Titanium is used in seawater heat exchangers because it has excellent corrosion resistance and has almost no corrosion properties, particularly against seawater. In particular, plate materials are often used in plate heat exchangers.
This type of plate heat exchanger is configured by laminating a plurality of plates formed in a wave shape. In order to improve the heat transfer efficiency, press forming is performed to make the surface of the plate uneven. In recent years, in order to further improve the heat transfer efficiency, due to the need to reduce the thickness of the plate and to complicate the surface unevenness, the formability is improved from the viewpoint of preventing local necking or cracking during the press forming. Is required. Further, titanium has a property of easily adhering to other metals, and since sticking marks may be generated on the titanium plate at the time of press forming, adhesion to the mold is prevented. You also need. Further, it is also desired to suppress the wear of the mold and improve the life of the mold.

In order to prevent press cracking and adhesion of the titanium plate and to prevent wear of the mold, it is necessary to reduce the friction coefficient between the titanium plate and the mold. As means for reducing the coefficient of friction, for example, it is conceivable to enhance the lubricity of the surface of the titanium plate. In this regard, for example, a method described in Patent Document 1 (Japanese Patent Application Laid-Open No. 63-174949) is known. This method requires many steps such as forming an iron and zinc alloy layer of a lubricant carrier, then treating with zinc phosphate and applying a lubricant, resulting in low productivity.
Also, there is a method in which an organic lubricating film represented by a mill bond is formed on the surface of a titanium plate, and then press molding is performed in a state in which lubricating oil is further applied. However, in this method, it is necessary to apply and dry a mill bond solution to form a lubricating film, which requires a number of steps, resulting in low productivity. Further, in the case of an organic lubricating film such as a mill bond, peeled-off press debris causes indentation defects after press working, which may impair the appearance quality of a molded product after processing.

  Further, when a titanium plate is formed into a shape suitable for a plate-type heat exchanger, a deformed state of the titanium plate may include a plane strain state. The plane strain state refers to a deformed state in which only one of the X-axis direction and the Y-axis direction is strained, and the other strain orthogonal to one direction is zero. In general, molding including a plane distortion state is molding in a severe condition for a material, and press cracks are easily generated. For this reason, a reduction in the coefficient of friction between the titanium plate and the mold is more desired.

JP-A-63-174747

  The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a pressing die for a titanium plate that is free from press cracks and seizure traces and has little wear. In addition, press cracking and seizure marks do not occur, the shape of the molded product is not likely to be defective due to the wear of the mold, the appearance quality after processing is excellent, and the productivity of the titanium plate is also excellent. It is an object to provide a method.

The present inventors have studied a mold for press forming a titanium plate having a surface with excellent wear resistance and adhesion resistance and a low surface friction coefficient, and as a result, an alloy which is usually used as a material of the mold Wear resistance is achieved by forming a first plating layer mainly composed of Ni on the base material of tool steel and further forming a second plating layer mainly composed of Ni and containing fluororesin particles on the substrate. It has been found that it is possible to improve the formability of the titanium plate by improving the properties, adhesion resistance and low friction of the surface, and to improve the life of the mold.
The gist of the present invention is as follows.

[1] A press die used for press forming of a titanium plate,
A substrate, comprising a surface treatment film formed on the surface of the substrate,
The base material is, by mass%,
C: 1.00 to 2.30%,
Si: 0.10 to 0.60%,
Mn: 0.20 to 0.80%,
P: 0.030% or less,
S: 0.030% or less,
Cr: containing 4.80 to 13.00%,
The balance is made of steel having a composition consisting of iron and impurities,
The surface treatment film,
A first plating layer formed on the base material and containing Ni,
A second plating layer containing Ni formed on the first plating layer,
The second plating layer contains 3.0 to 10.0% by mass of P, and a balance of 4 to 10% by volume of fluororesin particles is contained in the Ni-P plating layer containing Ni and impurities. A titanium plate pressing die having a Vickers hardness in the range of 500 to 650.
[2] The die for pressing a titanium plate according to [1], wherein the Vickers hardness of the first plating layer is in the range of 700 to 1300.
[3] The titanium according to [1] or [2], wherein the first plating layer is a Ni-P plating layer containing 3.0 to 10.0% by mass of P and the balance being Ni and impurities. Press mold for plate.
[4] The titanium according to [1] or [2], wherein the first plating layer contains 0.3 to 3.0% by mass of B, and the balance is a Ni-B plating layer including Ni and impurities. Press mold for plate.
[5] The titanium plate according to any one of [1] to [4], wherein an electric Ni plating layer having a thickness of 0.1 to 1 μm is formed between the base material and the first plating layer. Press mold.
[6] The die for pressing a titanium plate according to any one of [1] to [5], wherein the thickness of the first plating layer is in a range of 1 to 2 μm.
[7] The die for pressing a titanium plate according to any one of [1] to [6], wherein the thickness of the second plating layer is in a range of 1 to 5 μm.
[8] The die for pressing a titanium plate according to any one of [1] to [7], wherein the Vickers hardness of the base material is 550 to 650.
[9] The die for pressing a titanium plate according to any one of [1] to [8], wherein a nitride layer is formed on a surface of the base material.
[10] The die for pressing a titanium plate according to [9], wherein the thickness of the nitride layer is 0.5 μm to 5 μm.
[11] The die for pressing a titanium plate according to [9] or [10], wherein the nitride layer has an average nitrogen concentration of 0.10 to 0.50% by mass.
[12] The titanium plate press according to any one of [9] to [11], wherein the nitrogen concentration distribution in the nitrided layer has a concentration gradient that decreases from the surface of the nitrided layer in the depth direction. Mold.
[13] The base material further comprises, by mass%,
Mo: 0.70 to 1.20%,
V: 0.15 to 1.00%,
W: 0.60 to 0.80%,
The die for pressing a titanium plate according to any one of [1] to [12], comprising:
[14] The die for pressing a titanium plate according to any one of [1] to [13], wherein the substrate is a punch and a die.
[15] A method for press-forming a titanium plate, wherein the titanium plate is press-formed using the die for pressing a titanium plate according to any one of [1] to [14].
[16] The method for press-forming a titanium plate according to [15], wherein when the titanium plate is press-formed, a deformation state of the titanium plate includes a plane strain state.

  ADVANTAGE OF THE INVENTION According to this invention, a press die of the titanium plate which does not generate | occur | produce a press crack and a seizure mark and has little wear can be provided. Further, according to the present invention, press cracks and seizure marks do not occur, shape defects of molded products due to abrasion of molds are less likely to occur, excellent appearance quality after processing, and excellent productivity. And a method for press-forming a titanium plate.

FIG. 1 is a schematic side view showing a main part of a plate heat exchanger according to an embodiment of the present invention. FIG. 2 is an exploded perspective view showing a main part of the plate heat exchanger according to the embodiment of the present invention. FIG. 3 is a process diagram illustrating a method for press-forming a titanium plate according to an embodiment of the present invention. FIG. 4 is a diagram illustrating a method for press-forming a titanium plate according to an embodiment of the present invention, and is a schematic diagram showing a titanium plate before forming. FIG. 5 is a diagram illustrating a method for press-forming a titanium plate according to an embodiment of the present invention, and is a schematic diagram showing the titanium plate after forming. FIG. 6 is a graph showing the relationship between the punch stroke amount and the thickness of a titanium plate during press forming. FIG. 7 is a schematic cross-sectional view showing a pressing die of Example 1 and Comparative Example 1.

Hereinafter, a press die for a titanium plate and a method for press-forming a titanium plate according to embodiments of the present invention will be described.
The present embodiment is described in detail for better understanding of the purpose of the press die for titanium plate and the press forming method of the titanium plate of the present invention. There is no limitation.

FIG. 1 shows a main part of the plate heat exchanger according to the present embodiment, and FIG. 2 shows an exploded perspective view of a main part of the plate heat exchanger.
As shown in FIGS. 1 and 2, the plate heat exchanger is configured by laminating wave-shaped plates in a plate thickness direction. By overlapping the wavy plates, a flow path through which the fluid flows is formed between the plates. When a high-temperature fluid and a low-temperature fluid flow through each channel, heat exchange is performed between the fluids via the plate. The plate is made of a titanium plate.

  More specifically, as shown in FIG. 1, the plate heat exchanger is configured such that titanium plates 1A to 1E are stacked at a predetermined interval. Each of the plates 1A to 1E is a corrugated plate in which a flat original plate (titanium plate) is formed in a wave shape, and may be a corrugated plate having a constant wavelength and amplitude, or a corrugated plate having different wavelengths and amplitudes. Is also good. In the example shown in FIG. 1, the wavelength and the amplitude are the same between the plates 1A to 1E. Further, the plates 1A to 1E are fastened by a fastening bolt (not shown) in an overlapped state. Further, a gasket (not shown) for preventing the outflow of fluid is provided on the outer peripheral portion of each of the plates 1A to 1E.

  With the above configuration, a flow path 2A is formed between the plates 1A and 1B, a flow path 2B is formed between the plates 1B and 1C, and a flow path 2C is formed between the plates 1C and 1D. A channel 2D is formed between the plates 1D and 1E. The flow direction of the fluid in each of the flow paths 2A to 2D is opposite to each other between the adjacent flow paths as shown in FIG. Then, for example, a low-temperature fluid (for example, seawater) flows through the flow paths 2A and 2C, and a high-temperature fluid (for example, hot water or steam) flows through the flow paths 2B and 2D. The heat is exchanged between the hot fluid and the cold fluid via

  Each of the plates 1A to 1E is manufactured by press-forming a titanium plate. The titanium plate in the present embodiment is not particularly limited, and may be either a pure titanium plate or a titanium alloy plate. For example, the following pure titanium plate or titanium alloy plate can be used. However, the following titanium plates are merely examples, and pure titanium plates or titanium alloy plates other than those listed below may be used.

  As the pure titanium plate, for example, an industrial pure titanium plate can be used. Industrial pure titanium includes one to four types of JIS standard, and corresponding grades 1 to 4 of ASTM standard and industrial pure titanium specified by DIN standard of 3, 7025, 3, 7035, 3, 7055. Shall be considered. That is, the industrial pure titanium targeted in the present invention is, by mass%, C: 0.1% or less, H: 0.015% or less, O: 0.4% or less, N: 0.07% or less, Fe: 0.5% or less, with the balance being Ti.

As the titanium alloy plate, an α-type titanium alloy, an α + β-type titanium alloy, and a β-type titanium alloy can be used.
As the α-type titanium alloy, for example, a high corrosion resistant alloy (ASTM Grade 7, 11, 16, 26, 13, 30, 33 or a JIS type corresponding thereto or a titanium material containing a small amount of various elements), Ti- 0.5Cu, Ti-1.0Cu, Ti-1.0Cu-0.5Nb, Ti-1.0Cu-1.0Sn-0.3Si-0.25Nb, Ti-0.5Al-0.45Si, Ti- 0.9Al-0.35Si, Ti-3Al-2.5V, Ti-5Al-2.5Sn, Ti-6Al-2Sn-4Zr-2Mo, Ti-6Al-2.75Sn-4Zr-0.4Mo-0. 45Si and the like.

  As the α + β type titanium alloy, for example, Ti-6Al-4V, Ti-6Al-6V-2Sn, Ti-6Al-7V, Ti-3Al-5V, Ti-5Al-2Sn-2Zr-4Mo-4Cr, Ti-6Al -2Sn-4Zr-6Mo, Ti-1Fe-0.35O, Ti-1.5Fe-0.5O, Ti-5Al-1Fe, Ti-5Al-1Fe-0.3Si, Ti-5Al-2Fe, Ti-5Al -2Fe-0.3Si, Ti-5Al-2Fe-3Mo, Ti-4.5Al-2Fe-2V-3Mo and the like.

  Further, as the β-type titanium alloy, for example, Ti-11.5Mo-6Zr-4.5Sn, Ti-8V-3Al-6Cr-4Mo-4Zr, Ti-10V-2Fe-3Mo, Ti-13V-11Cr-3Al , Ti-15V-3Al-3Cr-3Sn, Ti-6.8Mo-4.5Fe-1.5Al, Ti-20V-4Al-1Sn, Ti-22V-4Al and the like.

  Next, an example of a method for forming a titanium plate of the present embodiment will be described. The following example describes an example in which the plates 1A to 1E of the plate heat exchanger shown in FIGS. 1 and 2 are manufactured. However, the present invention is not limited to this. Widely applicable.

  FIG. 3A shows a titanium plate and a pressing mold before molding, and FIG. 3B shows a titanium plate and a pressing mold after molding. First, as shown in FIG. 3A, a titanium plate 11a and a pressing die 21 are prepared. The press mold 21 includes a punch 22 and a die 23. The punch 22 includes a punch plate 22a and a plurality of protrusions 22b attached to the lower surface of the punch plate 22a at equal intervals. The die 23 includes a die plate 23a and a plurality of protrusions 23b attached to the upper surface of the die plate 23a at equal intervals. When the punch 22 descends to the bottom dead center, the tip of the projection 23 b of the die 23 enters between the projections 22 b of the punch 22, and the projection of the punch 22 enters between the projections 23 b of the die 23. Each protruding portion 22b, 23b is positioned so that the tip of the portion 22b enters. The protrusions 22b and 23b are the base material in the present invention, and are made of a steel material having a predetermined component, and a surface treatment film is formed on the surfaces of the protrusions 22b and 23b (base material). The surface treatment film is composed of a laminated film of a first plating layer and a second plating layer. The surface treatment film may include an electric Ni plating layer in some cases. In addition, a nitride layer may be formed on the base material. Although the base material and the surface treatment film will be described later, by forming the surface treatment film on the projections 22b and 23b (base material), the coefficient of friction on the titanium plate 11a is reduced, and the titanium plate 11a during press molding is formed. Lubricity is improved.

  As shown in FIG. 3A, a titanium plate 11a before forming is arranged between the punch 22 and the die 23. Both ends of the titanium plate 11a in the plate length direction (left and right directions in the drawing) are restrained by wrinkle holders (not shown). Further, the titanium plate 11a may or may not be restricted in the width direction.

  Next, as shown in FIG. 3B, the punch 22 is lowered toward the die 23, and the tip of the projection 22 b of the punch 22 is caused to enter between the projections 23 b of the die 23. The titanium plate 11a is located on the protrusion 23a of the die 23 with both ends in the left-right direction being restrained in the figure, and the protrusions 22b, 23b come into contact with the titanium plate 11a as the punch 22 descends. Further, when the respective protruding portions 22b and 23b are pushed into the titanium plate 11a, bending deformation is performed at a plurality of positions of the titanium plate 11a, and finally, the titanium plate 11b formed in a wavy shape is obtained.

  At the time of molding, it is preferable to use an emulsion-based or soluble-oil-based lubricant used for ordinary press molding of a titanium plate. It is preferable to use a lubricant because the friction between the titanium plate 11a and the pressing mold 21 is further reduced. From the viewpoints of lubricating performance and easy removal of the lubricant attached to the product, a soluble oil-based lubricant which is a water-soluble cutting oil is most suitable.

  FIG. 4 shows the titanium plate 11a before molding, and FIG. 5 shows the titanium plate 11b after molding. 4 and 5, the titanium plates 11a and 11b are shown in plan and side views. As shown in FIGS. 4 and 5, the width w2 of the titanium plate 11b after the forming is substantially unchanged from the width w1 before the forming. On the other hand, since the titanium plate 11a was subjected to bending deformation at a plurality of locations while both ends in the plate length direction were constrained, the length L2 along the longitudinal surface of the formed titanium plate 11b was determined as The length L1 along the surface in the longitudinal direction of 11a is elongated by an amount corresponding to the wave-like deformation. In addition, since the both ends are stretched while being restrained, the plate thickness is also partially reduced. That is, when the titanium plate 11b is formed into a corrugated shape, the titanium plate 11b is deformed and distorted along the plate length direction, but is not deformed in the plate width direction orthogonal to the plate length direction and the distortion amount is reduced. 0, which is a so-called plane distortion state.

Next, a base material and a surface treatment film applied to the press die 21 according to the present embodiment will be described. The base material is, by mass%, C: 1.00 to 2.30%, Si: 0.10 to 0.60%, Mn: 0.20 to 0.80%, P: 0.030% or less, S : 0.030% or less, Cr: 4.80 to 13.00%, the balance being a steel material having a steel composition composed of iron and impurities. A surface treatment film is provided on the surfaces of the projections 22b and 23b made of the base material. In the surface treatment film, a first plating layer and a second plating layer are laminated in this order. A nitride film may be formed on the substrate surface, and a surface treatment film may be formed thereon. Further, an electric Ni plating layer having a thickness of 0.1 to 1 μm may be formed between the base material and the first plating layer.
The first plating layer contains Ni. The second plating layer contains 3.0 to 10.0% by mass of P, and the Ni-P plating layer whose balance is composed of Ni and impurities contains 4 to 10% by volume of fluororesin particles. The Vickers hardness of the second plating layer is in the range of 500 to 650.
The Vickers hardness of the first plating layer may be in the range of 700 to 1300.
The first plating layer may be a Ni-P plating layer containing 3.0 to 10.0% by mass of P and the balance being Ni and impurities, and 0.3 to 3.0% by mass of B. And the balance may be a Ni-B plating layer composed of Ni and impurities.
The thickness of the first plating layer may be in the range of 1 to 2 μm. Further, the thickness of the second plating layer may be in the range of 1 to 5 μm.
The Vickers hardness of the substrate may be from 550 to 650.
When a nitride layer is formed on the substrate, the thickness of the nitride layer may be 0.5 μm to 5 μm. The average nitrogen concentration of the nitrided layer may be 0.10 to 0.50% by mass. The nitrogen concentration distribution in the nitrided layer may have a concentration gradient that decreases from the surface of the nitrided layer in the depth direction.

[Substrate composition]
First, regarding the component composition of the base material of the present embodiment, the reasons for limiting each element will be described in detail. In the following description, “%” represents mass% unless otherwise specified. The balance of the basic components and selected elements shown below consists of iron and inevitable impurities.

(C: carbon) 1.00 to 2.30%
C is an element necessary for forming carbides and ensuring the hardness of the base material. In addition, since it combines with Cr, Mo, V and the like to form a hard carbide, it is important as an element for increasing the quenching and tempering hardness and constituting the wear resistance. Therefore, in the present embodiment, 1.00% or more of C is contained. From the viewpoint of securing the hardness, it is preferable to contain 1.4% or more.
On the other hand, if the C content exceeds 2.30%, the toughness is significantly deteriorated. Therefore, in the present embodiment, the C content is limited to 2.30% or less. From the viewpoint of ensuring toughness, the upper limit of the C content is preferably 2.20%, and more preferably 2.00% or less.

(Si: silicon) 0.10 to 0.60%
Si is contained as a deoxidizing agent. Further, Si is contained because it has an effect of increasing softening resistance during high-temperature tempering. From these viewpoints, 0.10% or more of Si is contained. On the other hand, when the Si content exceeds 0.60%, the hot workability and toughness are reduced, and nonmetallic inclusions may increase. Therefore, the Si content is set to 0.60% or less. From the viewpoint of securing the toughness of the substrate, the upper limit of the Si content is preferably 0.50%.

(Mn: manganese) 0.20 to 0.80%
Mn is an element having a deoxidizing effect like Si, and is an element that improves hardenability and increases retained austenite. From this viewpoint, Mn is contained at 0.20% or more. In addition, it is preferable to contain 0.30 or more from the viewpoint of securing the hardness of the base material. In this embodiment, the upper limit of the amount of Mn is set to 0.8% in consideration of the balance with toughness. Preferably, it is 0.6% or less.

(P: phosphorus) 0.030% or less (S: sulfur) 0.030% or less Both P and S are preferable impurity elements that do not exist in steel. For this reason, the contents of both P and S are limited to 0.030% or less. Preferably, it is limited to 0.020% or less.

(Cr: chrome) 4.80 to 13.00%
Cr is an element that is required to combine with C to form a carbide by combining with C, thereby improving the wear resistance of the base material. Further, in the present embodiment, since a CrN film (hard film) is formed on the base material of the pressing die 21, it is very important in securing the adhesion to the CrN film. From these viewpoints, the Cr content is set to 4.80% or more, preferably 8.00% or more, and more preferably 11.00% or more.
On the other hand, if Cr is added excessively, the toughness may be deteriorated due to the formation of coarse carbides. Therefore, the upper limit of the Cr content is set to 13.00%. In addition, it is preferably 12.50% or less.

  In the present embodiment, the above component composition may further contain Mo: 0.70 to 1.20% and V: 0.15 to 1.00%.

(Mo: molybdenum) 0.70 to 1.20%
Mo has the effect of improving the temper softening resistance and imparting wear resistance to the substrate by forming carbides. From these viewpoints, Mo is preferably contained at 0.70% or more, and more preferably at 0.80% or more.
On the other hand, if Mo is added excessively, the toughness of the base material may be deteriorated. For this reason, Mo is preferably contained at 1.20% or less, and more preferably 1.10% or less.

(V: vanadium) 0.15 to 1.00%
V is effective for improving the hardenability of the base material, suppressing tempering softening, and further reducing the size of carbides. Therefore, V is preferably contained in an amount of 0.15% or more, more preferably 0.20% or more.
On the other hand, if V is added excessively, the cold workability may be impaired. Therefore, V is preferably contained at 1.00% or less, more preferably at 0.50% or less.

  In the present embodiment, the above component composition may further contain 0.60 to 0.80% W.

(W: tungsten) 0.60 to 0.80%
W is, like V, effective for improving the hardenability of the substrate, suppressing temper softening, and further reducing the size of carbide. Therefore, it is preferable that W is contained at 0.6% or more. On the other hand, if W is added excessively, the cold workability may be impaired, so that W is preferably contained at 0.80% or less.

  In the present embodiment, the balance other than the above-mentioned elements is substantially made of Fe, and a small amount of impurities and other elements that do not impair the effects of the present invention can be added.

  In the press die of the present embodiment, a material having the above-described composition is used as the material of the base material. Among them, from the viewpoint of securing a good balance between abrasion resistance and anti-adhesion resistance at lower cost. It is preferable to use SKD1, SKD2, SKD10, SKD11 or SKD12 (all within the above component composition range) specified in JIS G 4404, and among them, it is particularly preferable to use SKD11.

[CrN coating]
The hardness of the substrate having the above component composition is about 550 to 650 in Vickers hardness. In other words, when a titanium plate is press-formed without forming a film or the like on the above-described base material, the hardness of the base material itself can be ensured. However, regarding the adhesion resistance, there is a possibility that the material of the titanium plate may seize to the base material, and a large number of flaws may occur in the pressing die.

  Therefore, the present inventors have paid attention to a plating layer containing Ni as a material having excellent adhesion resistance to a titanium plate and excellent wear resistance. It has been found that when a plating layer containing Ni is selected as the material of the press die 21 when cold working a titanium plate, Ni exhibits adhesion resistance to titanium. Further, they have found that it is important to include fluororesin particles in the plating layer in order to impart lubricity to the plating layer containing Ni. By increasing the lubricity of titanium, adhesion resistance can be further increased. Furthermore, the plating layer containing the fluororesin particles has relatively low adhesion to the base material, but by forming another plating layer between the plating layer containing the fluororesin particles and the base material. It was found that the adhesion could be improved. Therefore, in the present embodiment, a mold in which a first plating layer and a second plating layer are formed on a base material is used as the pressing die 21 for a titanium plate. Hereinafter, the first plating layer and the second plating layer will be described.

  The first plating layer is a plating layer mainly containing Ni. The first plating layer is preferably a plating formed by an electroless method. In particular, the first plating layer is preferably a Ni-P plating layer or a Ni-B plating layer among Ni platings formed by an electroless method. Since the reducing agent contained in the plating bath is relatively stable in the Ni-P plating layer, a plating layer having stable quality can be obtained. Further, the Ni-B plating layer has a higher Vickers hardness than the Ni-P plating layer, and therefore has excellent wear resistance. Therefore, the type of plating should be selected according to the required performance. More preferably, a Ni-P plating layer may be selected.

  When the first plating layer is a Ni-P plating layer, the composition preferably contains 3.0 to 10.0% by mass of P, and the balance is preferably made of Ni and impurities. The Vickers hardness of the first plating layer is improved as the P content is smaller, but if the P content is too small, the denseness of the plating is reduced. Therefore, the P content is set to 3.0% by mass or more. If the P content is excessive, the Vickers hardness decreases, so the P content is set to 10.0% by mass or less. A more preferable range of the P amount is 4.0 to 7.0% by mass.

  When the first plating layer is a Ni-B plating layer, the composition preferably contains B in an amount of 0.3 to 3.0% by mass, with the balance being Ni and impurities. The Vickers hardness of the first plating layer is improved as the B content is smaller, but if the B content is too small, the denseness of the plating is reduced. Therefore, the B content is set to 0.3% by mass or more. If the B content is excessive, the Vickers hardness decreases, so the B content is set to 3.0% by mass or less. A more preferable range of the B content is 0.5 to 2.0% by mass.

  The Vickers hardness of the first plating layer is preferably in the range of 700 to 1300. The first plating layer has a higher Vickers hardness than the base material, and is less likely to crack when a load is applied. Further, even if the second plating layer is worn, the presence of the first plating layer can ensure the wear resistance. If the Vickers hardness of the first plating layer is 700 or more, the wear resistance can be improved. On the other hand, if the Vickers hardness is too high, cracks may occur, so the upper limit is set to 1300 or less, more preferably 1000 or less. For example, when it is desired to secure Vickers hardness up to 1000, it is preferable to select the Ni-P plating layer or Ni-B plating layer, and when it is desired to secure Vickers hardness up to 1300, the Ni-B plating layer is used. It is preferable to select.

  The thickness of the first plating layer is preferably in the range of 1 to 2 μm. When the thickness of the first plating layer is 1 μm or more, the smoothness of the plating layer surface is improved, and the wear resistance and the adhesion resistance can be sufficiently increased. Further, by setting the thickness of the first plating layer to 2 μm or less, the first plating layer does not crack even when a load is applied when the mold 21 is used. For these reasons, it is preferable that the thickness of the first plating layer be 1 μm to 2 μm. The preferable range of the thickness of the first plating layer is 1.2 to 1.8 μm.

  The first plating layer is preferably formed by an electroless plating method. Since the plating layer formed by the electroless plating method has a relatively low Vickers hardness, it is preferable to perform a heat treatment after the formation of the first plating layer. Examples of the heat treatment conditions include a heat treatment temperature of 300 to 500 ° C. and a heat treatment time of 0.5 to 3 hours. By setting the heat treatment temperature at 300 ° C. or higher, the Vickers hardness of the first plating layer can be sufficiently increased. Further, by setting the heat treatment temperature to 500 ° C. or lower, the softening of the base material due to tempering can be prevented. By setting the heat treatment time in the range of 0.5 to 3 hours, the Vickers hardness of the first plating layer can be sufficiently improved.

  Further, even when the surface roughness of the base material is relatively large, by forming the first plating layer by the electroless plating method, the surface of the base material is smoothed and the surface of the first plating layer is smoothed. it can. For this reason, when re-plating the first plating layer and the second plating layer when regenerating the press mold 21 whose service life has passed, adjustment of the surface roughness of the base material may be omitted in some cases. The productivity of the mold 21 can be increased. Further, although the press die 21 has a relatively complicated shape, the adoption of the electroless plating method allows the first plating layer to be formed with a uniform thickness.

  The first plating layer is a base layer of the second plating layer, and is formed to secure adhesion of the second plating layer. Since the second plating layer contains fluororesin particles, the adhesion to the substrate is relatively low, and if the second plating layer is formed directly on the surface of the substrate, the second plating layer peels during the processing of the titanium plate. There is a risk. On the other hand, since the first plating layer does not contain fluororesin particles, the adhesion to the substrate is higher than that of the second plating layer. Further, since the first plating layer is a plating layer mainly composed of Ni, similarly to the second plating layer, the adhesion to the second plating layer is relatively high. Therefore, by forming the first plating layer on the base material and forming the second plating layer on the first plating layer, the adhesion of the second plating layer to the base material can be improved.

  Like the first plating layer, the second plating layer is a plating layer mainly containing Ni, but the plating layer contains fluororesin particles. The second plating layer is also preferably a plating formed by an electroless method, particularly preferably a Ni-P plating layer. The Ni-P plating layer formed by the electroless plating method can provide a plating layer having a stable quality even when fluorine resin particles are contained in the plating bath. Therefore, it is preferable that the second plating layer contains fluorine resin particles in the Ni-P plating layer.

  The composition of the Ni—P plating layer constituting the second plating layer preferably contains 3.0 to 10.0% by mass of P, with the balance being Ni and impurities. The Vickers hardness of the second plating layer is improved as the P content is smaller, but if the P content is too small, the denseness of the plating is reduced. Therefore, the P content is set to 3.0% by mass or more. If the P content is excessive, the Vickers hardness decreases, so the P content is set to 10.0% by mass or less. A more preferable range of the P amount is 4.0 to 7.0% by mass.

  The fluororesin particles contained in the second plating layer are preferably particles made of polytetrafluoroethylene (PTFE). By including fluorine tree particles in the second plating layer, the lubricity of the second plating layer with respect to the titanium plate can be enhanced, and adhesion of the titanium plate when the pressing die 21 is used can be prevented. The content of the fluorine tree particles is preferably in the range of 4 to 10% by volume in terms of volume fraction with respect to the Ni-P plating layer. When the content of the fluororesin particles is 4% by volume or more, the lubricity of the second plating layer can be sufficiently increased, and adhesion of the titanium plate can be prevented. Further, by setting the fluororesin particles to 10% by volume or less, a decrease in Vickers hardness of the second plating layer can be prevented. A more preferable range of the content of the fluorine tree particles is a range of 4 to 7% by volume in terms of a volume fraction with respect to the Ni-P plating layer.

  The average particle size of the fluororesin particles is preferably in the range of 0.1 to 0.3 μm. If the particle size is large, the local hardness decreases and durability cannot be obtained. Further, by setting the average particle size of the fluororesin particles to 0.1 μm or more, the aggregation of the fluororesin particles can be prevented, and the denseness of the second plating layer can be increased. Also, by setting the average particle size of the fluororesin particles to 0.3 μm or less, the denseness of the second plating layer can be enhanced.

  The Vickers hardness of the second plating layer is preferably in the range of 500 to 650. The second plating layer has a relatively low Vickers hardness because it contains fluororesin particles, but due to the effect of improving lubricity by the fluororesin particles, even if the Vickers hardness is low, the abrasion resistance and adhesion resistance to the titanium pipe are low. Sex can be enhanced sufficiently. If the Vickers hardness of the second plating layer is 500 or more, the wear resistance and the adhesion resistance can be sufficiently improved. In addition, the Vickers hardness of the second plating layer is affected by the content of the fluororesin particles. In order to increase the Vickers hardness of the second plating layer, it is necessary to reduce the content of the fluororesin particles. Decreases lubricity. Therefore, it is preferable that the second plating layer increase Vickers hardness as much as possible while ensuring lubricity. Therefore, the upper limit of the Vickers hardness of the second plating layer is preferably set to 650 or less.

  The thickness of the second plating layer is preferably in the range of 1 to 5 μm. When the thickness of the second plating layer is 1 μm or more, the wear resistance to the titanium plate can be sufficiently improved. Further, by setting the thickness of the second plating layer to 5 μm or less, even if a load is applied during use of the pressing die 21, cracks do not occur in the second plating layer. For these reasons, the thickness of the second plating layer is preferably 1 μm to 5 μm, more preferably 3 μm to 5 μm.

  The second plating layer is preferably formed by an electroless plating method. At that time, it is preferable to disperse the fluororesin particles in the plating bath. The dispersion concentration of the fluororesin particles in the plating bath may be adjusted so that the fluororesin particles are contained in the range of 4 to 10% by volume with respect to the Ni-P plating layer. Since the second plating layer formed by the electroless plating method has a low Vickers hardness, it is preferable to perform a heat treatment. Examples of the heat treatment condition include a condition of 300 to 380 ° C. for 0.5 to 3 hours. By setting the heat treatment temperature at 300 ° C. or higher, the Vickers hardness of the second plating layer can be sufficiently increased. Further, by setting the heat treatment temperature to 380 ° C. or less, the decomposition of the fluororesin particles can be suppressed.

  Further, although the press die 21 for the titanium plate has a relatively complicated shape, the adoption of the electroless plating method allows the second plating layer to be formed to have a uniform thickness.

  The second plating layer is a plating layer that comes into contact with the titanium plate when the pressing die is used. Titanium is said to be a metal that easily adheres to other metals, but by including fluororesin particles in the second plating layer, adhesion of titanium can be significantly suppressed. For this reason, in this embodiment, a plating layer mainly composed of Ni can be adopted as a surface treatment film for preventing abrasion of the base material of the pressing die.

  An electric Ni plating layer may be formed between the base material and the first plating layer. This electric Ni plating layer is called strike plating, and can remove a passive film on the surface of the base material when forming the electroplating layer. Thereby, compared with the case where the first plating layer is formed directly on the base material, improvement in the adhesion between the first plating layer and the second plating layer can be expected. The thickness of the electric Ni plating layer is preferably in the range of 0.1 to 1 μm.

  Further, it is preferable to provide a nitrided layer obtained by subjecting the surface layer of the substrate to a plasma nitriding treatment between the substrate and the first plating layer. As described above, by forming the nitrided layer on the surface layer of the base material, the adhesion between the first plated layer and the base material and the strength can be improved, the peeling of the first plated layer can be reduced, and It is possible to improve the adhesion.

Although the thickness of the nitrided layer is not particularly limited, in the present embodiment, it can be 0.5 μm to 5 μm.
In order to increase the adhesion between the base material and the first plating layer, it is preferable to secure the thickness of the nitride layer to 0.5 μm or more. More preferably, it is 1 μm or more. On the other hand, if the thickness of the nitrided layer is excessively large, the time required for the plasma nitriding treatment is increased, the productivity is reduced, and the manufacturing cost is increased. On the other hand, if the thickness of the nitrided layer is excessively large, the surface roughness of the substrate increases, and it is necessary to polish the surface of the substrate before forming the first plating layer. From these viewpoints, the thickness of the nitrided layer is preferably set to 5 μm or less.

The average nitrogen concentration in the nitrided layer is preferably 0.10 to 0.50% by mass.
If the nitrogen concentration in the nitrided layer is too low, the effect of improving the strength is small and sufficient abrasion resistance may not be obtained. Therefore, the average nitrogen concentration in the nitrided layer should be 0.10% by mass or more. preferable. More preferably, it is 0.20% or more.
On the other hand, if the nitrogen concentration in the nitrided layer is too high, the surface of the nitrided layer tends to be embrittled and cracks may occur. For this reason, the average nitrogen concentration in the nitrided layer is preferably set to 0.50% by mass or less. More preferably, it is 0.40% or less.

Further, it is preferable that the concentration distribution of nitrogen in the nitride layer has a concentration gradient such that the concentration distribution decreases from the surface layer of the nitride layer toward the depth direction.
It is not preferable that the strength difference occurs inside the base material from the viewpoint of the adhesion between the first plating layer and the base material and the strength. Therefore, it is preferable that the difference in the strength inside the base material, that is, the strength gradient along the depth direction of the base material, be gentle. For this purpose, it is preferable to control the concentration distribution of nitrogen in the nitrided layer so as to have a concentration gradient that decreases from the surface layer of the nitrided layer toward the substrate.

  In order to control the concentration distribution of nitrogen so as to have a gradient that decreases in the depth direction from the surface of the nitride layer, the plasma nitridation process on the substrate surface layer for forming the nitride layer is divided into a plurality of times. In addition, by performing each treatment under different conditions, the concentration distribution of nitrogen in the nitride layer may be adjusted.

  The determination of the “nitride layer” (determination of the boundary between the base material and the “nitride layer”) can be performed by a glow discharge optical emission spectrometer (GDS). Specifically, first, in the surface layer of the base material nitrided by the plasma nitriding treatment, the analysis area is set to a diameter of 1 mm, and ordinary glow discharge emission analysis is performed. Subsequently, the analysis is advanced in the depth direction, and the region up to the point where the amount of nitrogen in the analysis region exceeds the average nitrogen concentration of the base material (base material) is defined as a “nitrided layer”. That is, glow discharge emission analysis is performed in the depth direction, and a point where the nitrogen amount has decreased to the average nitrogen concentration of the substrate is determined as the boundary between the substrate and the “nitrided layer”.

  Further, the average nitrogen concentration in the nitrided layer can also be measured using GDS. In the present embodiment, the analysis area is 1 mm in diameter, analysis is performed in the depth direction using GDS, and a QDP (Quantitative Depth Profile) method defined in JIS K 0150 is applied. Measure the nitrogen concentration. Thereby, the concentration distribution of nitrogen in the nitrided layer can be obtained. Further, the average nitrogen concentration of the entire nitrided layer can be obtained by calculating the average of each nitrogen concentration at every 50 nm depth.

  Next, a method of manufacturing the pressing die 21 for a titanium plate will be described.

  The press die 21 is manufactured by sequentially forming a first plating layer and a second plating layer on a base material by an electroless plating method. Various processes described below may be appropriately selected and performed, or may not be performed.

  It is preferable that the surface of the base material on which the first plating layer and the second plating layer are formed is polished or the like in advance to improve smoothness.

  Before forming the plating layer, a sub-zero treatment may be performed on the base material to transform residual austenite contained in the structure of the base material into martensite. Sub-zero treatment may be performed by cooling to about -75 ° C to -130 ° C during quenching. Thereby, the Vickers hardness of the base material can be further increased, and for example, the Vickers hardness can be in the range of 600 to 700. Also, by reducing the amount of retained austenite, the shape stability of the first plating layer or the second plating layer during heat treatment can be increased.

  Further, the substrate may be subjected to a radical nitriding treatment to form a nitrided layer on the surface of the substrate. By performing the radical nitriding treatment, the Vickers hardness of the substrate surface can be made 1000 HV or more.

  Further, before forming the first plating layer, an electric Ni plating layer may be formed on the surface of the base material. By forming the electric Ni plating layer, the passivation film on the surface of the substrate can be removed, and the adhesion of the first plating layer and the second plating layer to the substrate can be further improved.

  Next, a first plating layer is formed by an electroless plating method. Since the first plating layer formed by the electroless plating method has a relatively low Vickers hardness, heat treatment is performed after the formation of the first plating layer. Examples of the heat treatment conditions include a heat treatment temperature of 300 to 500 ° C. and a heat treatment time of 0.5 to 3 hours.

  Next, a second plating layer is formed by an electroless plating method. At that time, fluororesin particles are dispersed in the plating bath. The dispersion concentration of the fluororesin particles in the plating bath may be adjusted so that the fluororesin particles are contained in the range of 4 to 10% by volume with respect to the Ni-P plating layer. Since the second plating layer formed by the electroless plating method has a low Vickers hardness, it is preferable to perform a heat treatment. Examples of the heat treatment conditions include a condition of 300 to 350 ° C. for 0.5 to 3 hours.

  In the present embodiment, the Vickers hardness of the first plating layer and the second plating layer may be simultaneously increased by performing the heat treatment at once after forming the first plating layer and the second plating layer. Examples of the heat treatment conditions in this case include a condition of 300 to 350 ° C. for 0.5 to 3 hours.

  Through the above steps, a pressing die for a titanium plate can be manufactured.

  FIG. 6 is a graph showing the relationship between the stroke amount of the punch and the thickness of the titanium plate. The graph of FIG. 6 is a result obtained by an experiment in which a case where a titanium plate is press-formed with the press die shown in FIG. 2 is simply simulated. In a state in which both ends in the longitudinal direction of the pure titanium plate having a thickness of 0.5 mm are restrained and both ends in the longitudinal direction of the pure titanium plate are supported from below by two rolls, one roll is placed at the center in the longitudinal direction of the titanium plate. FIG. 4 shows a behavior of a reduction in the thickness of a titanium plate when bending is performed by descending from the upper side. The processed titanium plate is in a plane distortion state. The stroke of the punch on the horizontal axis in FIG. 6 is the descending amount of the roll arranged on the upper side, and the plate thickness on the vertical axis is the minimum plate thickness at the portion subjected to bending. By changing the type of roll, the static friction coefficient μ between the titanium plate and the roll is set to 0.05 and 0.1. Looking at the stroke amount when the plate thickness is reduced to 0.3 mm (decrease rate 40%), when the static friction coefficient μ is 0.1, it is 4.3 mm, and when the static friction coefficient μ is 0.05, The stroke amount has been increased to 4.5 mm. As described above, by increasing the coefficient of static friction between the mold and the titanium plate to improve the lubricity, the stroke amount can be increased, and a desired shape can be processed without causing cracks.

  Since the surface treatment film according to the present embodiment is formed on the pressing mold for the titanium plate of the present embodiment, compared with the case where the surface treatment film is not formed, the distance between the titanium plate and the pressing mold is reduced. Lubricity can be greatly improved. This makes it possible to suppress cracking of the titanium plate during press forming in the method of press-forming a titanium plate.

  In addition, according to the pressing die for a titanium plate of the present embodiment, by forming the first plating layer and the second plating layer on the base material, the lubricating property, abrasion resistance, and the like of the pressing die 21 are improved. Adhesion resistance can be improved. In particular, by including fluororesin particles in the second plating layer, lubricity to the titanium tube can be improved, and adhesion of titanium at the time of forming the titanium tube can be prevented. In addition, by forming the first plating layer between the second plating layer and the base material, the adhesion of the second plating layer can be increased, and peeling of the second plating layer can be suppressed.

  Further, the method for press-forming a titanium plate according to the present embodiment can be applied to cracking, press-fitting of titanium material, and wear of a mold even after a deformation of the titanium plate includes a plane strain state. Can be prevented. That is, in the method for press-molding a titanium plate of the present embodiment, the lubricating property between the projections 22b and 23b and the titanium plate 11a is enhanced by the surface treatment film. Is performed, the titanium plate 11a slides on the surface of the protrusion during the bending process and does not adhere, and the titanium plate 11a is stretched without being restrained by the protrusions 22b and 23b, and can be formed into a desired shape. Further, even if the projections 22b and 23b collide with the titanium plate 11a due to the lowering of the punch 22 and an impact is applied to the surface treatment film and the base material, the surface treatment film has the first plating layer, and further, if necessary, Since the Ni plating layer is provided, the second plating layer does not peel off, and lubricity, adhesion resistance and wear resistance are not impaired. Thus, even when the deformed state of the titanium plate after forming includes a plane strain state, it is possible to prevent cracking after press forming, adhesion of the titanium material, and wear of the mold.

  Further, when forming the titanium plate, by applying a lubricant to the titanium plate and then press-forming, the lubricity between the titanium plate and the pressing mold can be further improved.

  Furthermore, according to the press die according to the present embodiment, the life of the die can be significantly improved, the frequency of replacing the die can be reduced, and the manufacturing cost can be greatly reduced. Further, by reducing the frequency of mold replacement, it is possible to prevent a decrease in yield due to position adjustment or the like at the time of mold replacement, and to achieve an improvement in yield by improving molding dimensional accuracy.

  The present invention is not limited to the above-described embodiment, and can be applied to any mold that is used for press molding of a titanium plate.

  Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited to the conditions used in the following examples.

<Dies for press>
(Example 1)
First, a tool steel SKD11 (C, Si, Mn, Cr, Mo, V, P, S, the balance of iron and impurities) specified in JIS G 4404 as a base material of a die and a punch of a press die is used in the present invention. After being formed into a predetermined shape, quenching and tempering were performed.
Next, a first plating layer composed of a Ni-P plating layer containing P was formed on the surface of the obtained base material. The first plating layer was formed by an electroless plating method. A plating bath containing nickel sulfate, sodium hypophosphite, a pH buffer, a stabilizer and a complexing agent was used.
Next, a second plating layer made of a Ni-P plating layer containing P was formed on the first plating layer. The second plating layer was formed by an electroless plating method. A plating bath containing nickel sulfate, sodium hypophosphite, a pH buffer, a stabilizer and a complexing agent is used. In addition, a fluororesin made of tetrafluoroethylene having an average particle diameter of 0.3 μm is used in the plating bath. Particles were added. Thereby, the fluororesin particles were contained in the second plating layer. After the formation of the second plating layer, heat treatment was performed under the conditions of a heat treatment temperature of 300 ° C. and a heat treatment time of one hour.
In this way, a press-forming die having the first plating layer and the second plating layer as shown in Table 1 was manufactured.

(Example 2)
The tool steel SKD11 (C, Si, Mn, Cr, Mo, V, P, S, the balance of iron and impurities as specified in JIS G 4404 as a base material for a die and a punch of a press die is included in the scope of the present invention. , And quenching and tempering were performed.
Next, a Ni electroplating layer was formed on the surface of the substrate by an electroplating method, and immediately thereafter, the substrate was immersed in an electroless plating bath for forming a first plating layer to form a first plating layer. A plating bath containing nickel sulfate, sodium hypophosphite, a pH buffer, a stabilizer and a complexing agent was used.
Next, a second plating layer made of a Ni-P plating layer containing P was formed on the first plating layer. The second plating layer was formed by an electroless plating method. A plating bath containing nickel sulfate, sodium hypophosphite, a pH buffer, a stabilizer and a complexing agent is used. In addition, a fluororesin made of tetrafluoroethylene having an average particle diameter of 0.3 μm is used in the plating bath. Particles were added. Thereby, the fluororesin particles were contained in the second plating layer. After the formation of the second plating layer, heat treatment was performed under the conditions of a heat treatment temperature of 300 ° C. and a heat treatment time of one hour.
In this way, a press-molding die including the electric Ni plating layer, the first plating layer, and the second plating layer as shown in Table 1 was manufactured.

(Example 3)
The tool steel SKD11 (C, Si, Mn, Cr, Mo, V, P, S, the balance of iron and impurities as specified in JIS G 4404 as a base material for a die and a punch of a press die is included in the scope of the present invention. , And quenching and tempering were performed.
Next, a Ni electroplating layer was formed on the surface of the substrate by an electroplating method, and immediately thereafter, the substrate was immersed in an electroless plating bath for forming a first plating layer to form a first plating layer. A plating bath containing nickel sulfate, dimethylamine borane, a pH buffer, a stabilizer and a complexing agent was used.
Next, a second plating layer made of a Ni-P plating layer containing P was formed on the first plating layer. The second plating layer was formed by an electroless plating method. A plating bath containing nickel sulfate, sodium hypophosphite, a pH buffer, a stabilizer and a complexing agent is used. In addition, a fluororesin made of tetrafluoroethylene having an average particle diameter of 0.3 μm is used in the plating bath. Particles were added. Thereby, the fluororesin particles were contained in the second plating layer. After the formation of the second plating layer, heat treatment was performed under the conditions of a heat treatment temperature of 300 ° C. and a heat treatment time of one hour.
In this way, a press-molding die including the electric Ni plating layer, the first plating layer, and the second plating layer as shown in Table 1 was manufactured.

(Comparative Example 1)
The tool steel SKD11 (C, Si, Mn, Cr, Mo, V, P, S, the balance of iron and impurities as specified in JIS G 4404 as a base material for a die and a punch of a press die is included in the scope of the present invention. , And quenching and tempering were performed.
Next, a plating layer composed of a Ni-P plating layer containing P was formed on the surface of the base material. The plating layer was formed by an electroless plating method. A plating bath containing nickel sulfate, sodium hypophosphite, a pH buffer, a stabilizer and a complexing agent was used, and fluororesin particles composed of tetrafluoroethylene having an average particle diameter of 0.3 μm were further added. . After the formation of the plating layer, heat treatment was performed under the conditions of a heat treatment temperature of 300 ° C. and a heat treatment time of 1 hour.
In this way, a press-forming die having a plating layer as shown in Table 1 was manufactured. The components of the plating layer of Comparative Example 1 were described in the column of the second plating layer in Table 1.

<Evaluation of press molding>
The press formability was evaluated by press-forming a titanium plate using the dies and punches of Examples 1 to 3 and Comparative Example 1.
FIG. 7 shows a schematic cross-sectional view of a press die used in the test. The press die shown in FIG. 7 was composed of a punch 21, a die 22, and a wrinkle holding pad 23. The punch 21 is provided with three protrusions 21a at equal intervals. The die 22 was provided with two protrusions 22a, 22a. The tips of the projections of the die 21 and the punch 22 had a curved surface with a radius of curvature of 3.0 mm when viewed in cross section. The protrusion 21a of the punch 21 and the protrusion 22a of the die 22 are positioned so that the gap between the protrusions 21a and 22a becomes 1.5 mm when the punch 21 descends to the bottom dead center. The dimension of the punch 21 in the width direction in the figure was 36 mm, and the height of each protrusion of the punch 21 and the die 22 was 10 mm. Above the outer peripheral portion of the die 22, a wrinkle holding pad 23 was arranged. The die 22 was provided with a bead 22b for preventing the material from flowing so as to surround the punch 21. Thereby, the titanium plate that has been subjected to the forming process is in a plane strain state.

  Using a pressing die shown in FIG. 7, a 0.5 mm-thick titanium plate was press-formed. As the titanium plate, a titanium plate made of JIS Class 1 titanium was used. When the pressing dies of Examples 1 to 3 were used, only a rust-preventive oil (trade name: Knoxlast, manufactured by Parker Kosan Co., Ltd.) was applied to a titanium plate as a lubricant, and press-formed. When the press die of Comparative Example 1 was used, the same lubricant as in Examples 1 to 3 was applied to a titanium plate surface-treated by mill bonding and press-formed. The titanium plate was formed into a corrugated shape as shown in FIG. 2 by press forming. At this time, the punch 21 was pushed in so that the amplitude of the wave became 2.5 mm as a target value.

As a result of press molding, Examples 1 to 3 and Comparative Example 1 were each formed into a corrugated shape as shown in FIG. 2, and the radius of curvature of the cross section of one and the other protrusions was in the range of 3.05 to 3.11 mm. And the amplitude became 4.8 mm, and the shape almost as intended was obtained. Cracks from Examples 1 to 3 and Comparative Example 1 did not occur.
The minimum value of the plate thickness was 0.38 mm in Example 1 and 0.37 mm in Comparative Example 1, and there was no significant difference between the two.
As described above, the titanium plates press-formed using the press dies of Examples 1 to 3 were not subjected to the mill bond treatment. It became possible to mold into the same shape.

  In addition, a durability test was performed by applying the mold of the present invention to punches of the Erichsen test specified in JIS Z 2247. That is, a punch for an Erichsen test was manufactured in the same manner as in Examples 1 to 3, except that the shape of the base material of the punch was changed to the shape specified in JIS Z 2247. Then, a JIS type 1 titanium plate having a thickness of 0.5 mm was used as a test piece, and a punch was pushed into the test piece until a through crack occurred. This was repeated 200 times. As a result, in each of the punches, although the thickness of the second plating layer formed on the surface of the punch was slightly reduced, the second plating layer itself was not peeled off, and the durability was good.

  1A to 1E: Plate (titanium plate), 11a, 11b: Titanium plate, 21: Press mold, 22: Punch, 22a: Punch plate, 22b: Projection (base material), 23: Die, 23a: Die plate , 23b ... protrusions (base material).

Claims (16)

A press mold used for press forming of a titanium plate,
A substrate, comprising a surface treatment film formed on the surface of the substrate,
The base material is, by mass%,
C: 1.00 to 2.30%,
Si: 0.10 to 0.60%,
Mn: 0.20 to 0.80%,
P: 0.030% or less,
S: 0.030% or less,
Cr: containing 4.80 to 13.00%,
The balance is made of steel having a composition consisting of iron and impurities,
The surface treatment film,
A first plating layer formed on the base material and containing Ni,
A second plating layer containing Ni formed on the first plating layer,
The second plating layer contains 3.0 to 10.0% by mass of P, and a balance of 4 to 10% by volume of fluororesin particles is contained in the Ni-P plating layer containing Ni and impurities. A titanium plate pressing die having a Vickers hardness in the range of 500 to 650.   The die for pressing a titanium plate according to claim 1, wherein the Vickers hardness of the first plating layer is in a range of 700 to 1300.   3. The titanium plate press according to claim 1, wherein the first plating layer is a Ni—P plating layer containing 3.0 to 10.0 mass% of P and the balance being Ni and impurities. 4. Mold.   3. The titanium plate press according to claim 1, wherein the first plating layer is a Ni—B plating layer containing 0.3 to 3.0 mass% of B and the balance being Ni and impurities. 4. Mold.   5. The titanium sheet press according to claim 1, wherein an electric Ni plating layer having a thickness of 0.1 to 1 μm is formed between the base material and the first plating layer. 6. Mold.   The die for pressing a titanium plate according to any one of claims 1 to 5, wherein the thickness of the first plating layer is in a range of 1 to 2 µm.   The mold for pressing a titanium plate according to any one of claims 1 to 6, wherein the thickness of the second plating layer is in a range of 1 to 5 µm.   The die according to any one of claims 1 to 7, wherein the substrate has a Vickers hardness of 550 to 650.   The die for pressing a titanium plate according to any one of claims 1 to 8, wherein a nitride layer is formed on a surface of the base material.   The mold for pressing a titanium plate according to claim 9, wherein the thickness of the nitride layer is 0.5 μm to 5 μm.   The mold for pressing a titanium plate according to claim 9 or 10, wherein the nitrided layer has an average nitrogen concentration of 0.10 to 0.50% by mass.   The die for pressing a titanium plate according to any one of claims 9 to 11, wherein the concentration distribution of nitrogen in the nitride layer has a concentration gradient that decreases from the surface layer of the nitride layer toward the depth direction. . The substrate further comprises, in mass%,
Mo: 0.70 to 1.20%,
V: 0.15 to 1.00%,
W: 0.60 to 0.80%,
The mold for pressing a titanium plate according to any one of claims 1 to 12, comprising:   The mold for pressing a titanium plate according to any one of claims 1 to 13, wherein the substrate is a punch and a die.   A method for press-forming a titanium plate, comprising pressing the titanium plate using the die for pressing a titanium plate according to claim 1.   The method of press-forming a titanium plate according to claim 15, wherein when the titanium plate is press-formed, a deformed state of the titanium plate includes a plane strain state.

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