JP2009073693A - Optical element-molding die, and method for producing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To perform the reproduction of a die at low cost. <P>SOLUTION: A platinum group based metal plating layer 20 is provided on the surface of a base material 15, as a machining layer. The desired optical face shape is finished with high precision by ultraprecisely machining the machining layer using a diamond bit. The surface thereof is provided with a surface protective film layer 21 and a die release layer 22. Regarding the die in which the die release layer 22 and the surface protective film layer 21 are deteriorated by the repetition of heating and cooling by being used for the process of molding, the molding face is immersed into hydrofluoric acid, the deteriorated surface protective film layer 21 and die release layer 22 are removed, and a surface protective film layer 21 and a die release layer 22 are newly attached, so as to reproduce the die. Since the platinum based metal plating layer 20 is not eroded by hydrofluoric acid, the shape of the optical face subjected to the ultraprecise working is maintained. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an optical element molding die for producing a lens molded product by press molding a glass optical element, and a manufacturing method thereof.

  Conventionally, a mold for press-molding a glass lens is a cemented carbide mainly composed of tungsten carbide (WC), or a cermet mainly composed of titanium carbide (TiC) or titanium nitride (TiN). As a base material, it is manufactured by grinding using a grindstone. However, cemented carbides and cermets have extremely high hardness, which requires a long time for grinding and increases the cost of the mold. Also, in grinding, it may be difficult to process to a desired accuracy depending on the surface shape of the optical surface.

  Therefore, an electroless nickel plating layer made of Ni and P is provided as a cutting layer on a base material made of a cemented carbide, and the cutting layer is formed into an optical surface shape by ultra-precise cutting using a diamond bite. Are processed to a desired accuracy (Patent Document 1).

  It is also known that a cutting layer made of an amorphous metal or alloy is formed on the surface of a base material by a discharge plasma sintering method, and then the cutting layer is cut to obtain a desired optical surface. (Patent Document 2).

  By the way, in press molding of a glass lens, the glass molding material is heated by heating the mold to around 400 ° C. or higher. For this reason, press molds have high temperature strength, heat resistance and oxidation resistance so that they can withstand use at high temperatures, so that the lens can be molded with the desired shape and dimensional accuracy. However, durability is required to withstand long-term use. In addition, releasability is required so as not to adhere to the glass during molding.

  Therefore, in the mold, a noble metal alloy film such as platinum (Pt), iridium (Ir), osmium (Os), rhenium (Re), etc. is provided on the cutting layer to ensure heat resistance and releasability. As a surface protective film (Patent Document 2), an intermediate layer made of nitride or carbide ceramic, and a release layer made of a DLC film (abbreviated as Diamond Like Carbon: carbon hard film) are provided on the upper surface of the intermediate layer. (Patent Document 1) is also known.

  By the way, in the molding die for lenses, the dimension crossing on the molding surface is of the order of several [μm], and the surface roughness of the molding surface is required to be 10 to 20 [nm] or smoother than that. However, when the press molding is used, for example, about 4000 shots, the surface protective film deteriorates, roughens, or partially peels off, and the mold can be used. It will disappear.

Therefore, the molding die is regenerated by immersing the molding surface of the mold in hydrofluoric acid (HF) to remove the surface protective film and providing the surface protective film again.
JP-A-11-157852 JP 2003-246629 A

  By the way, as a mold regeneration method, for example, when a mold using an electroless nickel plating layer as an intermediate layer is dipped in hydrofluoric acid (HF) and regenerated, it enters the surface protection film from scratches, etc. Since even the nickel plating layer and the base material are melted to cause surface roughness and the like, it is necessary to perform precision cutting, polishing, etc. on the mold, and the mold regeneration cost increases.

  The present invention has been made in consideration of such conventional problems, and prevents the occurrence of surface roughness and the like, and an optical element molding die that can be reproduced at low cost, and It aims at providing the manufacturing method.

  In order to achieve the above object, the present invention provides a base material made of any one of cemented carbide, cermet, silicon carbide, silicon nitride, and stainless steel, and a non-cut layer provided on the base material. An electrolytic nickel plating layer and an intermediate layer provided between the electroless nickel plating layer and the release layer are provided, and the intermediate layer is provided on the white metal-based metal coating layer and the metal coating layer. And a surface protective film layer made of titanium aluminum nitride (TiAlN).

  The electroless nickel plating layer becomes a cutting layer. The white metal-based metal coat layer prevents the entry of hydrofluoric acid from scratches on the surface protective film during reproduction. The white metal-based metal coating is preferably a thin layer, for example, a thickness of about 0.5 to 2 μm. The white metal-based metal may be a metal mainly composed of at least one of platinum, rhodium, palladium, ruthenium, and iridium, or a mixture thereof. Moreover, as a mixture with platinum, rhodium, palladium, ruthenium, iridium, and other substances, the total content of platinum, rhodium, palladium, ruthenium, and iridium may be 50% by weight or more. Further, as the white metal-based metal, any one of platinum, rhodium, ruthenium, and iridium, or a mixture thereof, or any one of these substances or a mixture of these substances as a main component Mixtures may be used. As a mixture with this other substance, the total content of platinum, rhodium, palladium, ruthenium and iridium may be 50% by weight or more. Furthermore, gold may be used instead of the white metal.

  As the cutting layer, a white metal-based metal plating layer may be provided instead of the electroless nickel plating layer. In this case, the white metal-based metal plating layer serves as a cutting layer, and prevents the entry of hydrofluoric acid from scratches on the surface protective film during reproduction. The plating thickness of the white metal-based metal plating layer is preferably about 80 to 200 μm, for example. As described above, the white metal-based metal plating layer is preferably a metal plating layer mainly composed of at least one of platinum, rhodium, palladium, ruthenium, and iridium, or a mixture thereof. As the base material, any of cemented carbide, cermet, silicon carbide, silicon nitride, and stainless steel can be used.

  The surface protective film layer made of titanium aluminum nitride is coated by PVD treatment, for example, vacuum deposition. Note that alumina, titanium nitride (TiN), titanium carbide (TiC), titanium carbonitride (TiCN), silicon dioxide, zirconium oxide, or the like may be used instead of titanium aluminum nitride. As the release layer, a DLC film is suitable.

  According to the present invention, since the white metal-based metal layer is provided in the intermediate layer, it is possible to regenerate only the surface protective film in order to surely prevent entry of hydrofluoric acid from scratches on the surface protective film during reproduction. .

  As shown in FIG. 1, the glass optical element molding die 10 includes an upper die 11 and a lower die 12. A spherical glass material 13 adjusted to a desired volume is transferred to the lower mold 12 at the center of the molding surface 12a. The upper mold 11 is movable up and down by the pressurizing mechanism 14. By lowering the upper mold 11 to the pressurization position, a lens molded product is made by applying a load of about 200 kgf to the glass material 13 between the lower mold 12 and press molding. Note that the lower mold may be configured to be movable up and down.

  Although not shown, a heating mechanism, a cooling mechanism, and a handling robot are provided. After the glass material 13 is supplied onto the molding surface of the lower mold 12 by the robot, the upper mold 11 and The lower mold 12 is heated, and after the glass material 13 reaches a predetermined temperature exceeding the deformation temperature (At), press molding is performed for about 5 minutes, and then the glass material 13 is cooled to a glass transition temperature (Tg) or less by a cooling mechanism. The upper mold 11 is released from the mold, and the molded product is discharged from the lower mold 12 by the robot.

[Embodiment 1]
As shown in FIG. 2, the lower mold 12 has an electroless nickel plating layer 16 as a cutting layer formed on a temporary molding surface (surface having a schematic optical surface shape) 15 a of a base material 15 made of stainless steel. Further, a white metal-based metal coat layer 17 is provided on the electroless nickel plating layer 16, and a surface protective film layer 18 made of titanium aluminum nitride is further formed on the white metal-based metal coat layer 17. It is formed and a release layer 22 is provided thereon. That is, in this embodiment, the base material 15, the electroless nickel plating layer 16 provided thereon, and the intermediate layer between the electroless nickel plating layer 16 and the release layer 22 are made of a white metal metal. The coating layer 17 and the surface protective film layer 18 are used.

  In the case of using a base material 15 made of martensitic stainless steel, as shown in FIG. 3, a step of preparing a temporary molding surface 15a by cutting and polishing the base material 15 in advance, and then this temporary molding surface Step of forming electroless nickel plating layer 16 on 15a, and then processing electroless nickel plating layer 16 into a desired surface shape such as a spherical or aspherical shape by precision cutting using a diamond tool. A step of forming the surface 16a, a step of providing a white metal-based metal coat layer 17 on the processed surface 16a of the electroless nickel plating layer 16, and a titanium aluminum nitride on the white metal-based metal coat layer 17. The lower mold 12 is manufactured through a step of forming the surface protective film layer 18 by vacuum deposition and finally a step of forming the release layer 22 on the surface protective film layer 18. In this embodiment, since nickel is used, the workability is good and the mold can be made at low cost. The white metal-based metal coat layer 17 is preferably applied with a thickness of about 0.5 to 2 μm.

  As a regeneration method, as shown in FIG. 4, the surface protection film layer 18 is removed by immersing the molding surface 12 a of the used lower mold 12 in hydrofluoric acid. At this time, the white metal-based metal coat layer 17 prevents the entry of hydrofluoric acid from scratches on the surface protective film layer 18 or the like. Therefore, it is possible to reliably prevent the electroless nickel plating layer 16 from causing inconveniences such as surface roughness. Thereafter, a new surface protective film layer 18 is formed by vacuum deposition, and then a release layer 22 is formed on the surface protective film layer 18. Thus, since the electroless nickel plating layer 16 that has been subjected to ultra-precision machining in a desired shape is not eroded by hydrofluoric acid or the like, there is no need to re-create the ultra-precision machining layer during regeneration, and the lower mold 12 can be reduced. Can be played at a cost.

  Instead of the white metal-based metal coat layer, gold may be coated. In addition, as a white metal-type metal, the metal which has 1 type in platinum, iridium, palladium, rhodium, and ruthenium, or these mixtures as a main component is suitable. Here, as a mixture with platinum, rhodium, palladium, ruthenium, iridium and other substances, the total content of platinum, rhodium, palladium, ruthenium and iridium may be 50% by weight or more. Further, any one of platinum, rhodium, ruthenium, and iridium, or a mixture thereof, or a mixture with any one of these substances or a mixture of these substances as a main component may be used. As a mixture with this other substance, the total content of platinum, rhodium, palladium, ruthenium and iridium may be 50% by weight or more. Furthermore, gold may be used instead of the white metal.

  Moreover, although stainless steel is used as the base material 15, any of cemented carbide, cermet, silicon carbide, and silicon nitride mainly composed of tungsten carbide (WC) is used instead of stainless steel. It may be used. As the release layer 22, a DLC film which is a carbon hard film is suitable.

[Second Embodiment]
As shown in FIG. 5, the lower mold 19 has a white metal-based metal plating layer 20 formed as a cutting layer on a temporary molding surface 15a of a base material 15 made of stainless steel (SUS). A surface protective film layer 21 made of titanium aluminum nitride is coated on the metal plating layer 20, and a release layer 22 is provided on the surface protective film layer 21. In this embodiment, the intermediate layer between the base material 15 and the release layer 22 is composed of a white metal-based metal plating layer 20 and a surface protective film layer 21 which are cutting layers.

  In the case of using a base material 15 made of martensitic stainless steel, as shown in FIG. 6, a step of preparing the temporary molding surface 15a by cutting and polishing the base material 15 in advance, and then this temporary molding surface The step of forming a white metal-based metal plating layer 20 on 15a, and then processing the white metal-based metal plating layer 20 into a desired spherical or aspherical shape by precision cutting using a diamond tool. Forming a surface 20a, forming a surface protective film layer 21 made of titanium aluminum nitride on the processed surface 20a of the white metal plating layer 20 by vacuum deposition, and finally separating the surface protective film layer 21 on the surface protective film layer 21; The lower mold 19 is manufactured through the process of forming the mold layer 22. In this embodiment, since there is one layer less than in the first embodiment, the number of steps is reduced.

  As a regeneration method, as described with reference to FIG. 4, the surface protection film layer 21 is removed by immersing the molding surface of the used lower mold 19 in hydrofluoric acid. At this time, even if hydrofluoric acid enters due to scratches on the surface protective film layer 21 or the like, the white metal-based metal plating layer 20 is not eroded by hydrofluoric acid, so the surface that has been ultra-precision processed into a desired shape is maintained as it is. The Further, the base material 15 can be prevented from being eroded. Therefore, the lower mold 19 can be regenerated at low cost simply by forming a new surface protective film layer 21 by vacuum deposition and forming the release layer 22 thereon.

  The white metal-based metal plating layer 20 has high heat resistance, is easy to cut, has a thick plating layer, has good adhesion to the base material 15, and has good plating density. Since the plating layer has characteristics such as a Vickers hardness (Hv) of 300 to 1000, it is suitable as a cutting layer.

  Further, the white metal-based metal plating layer 20 can be formed to a thickness of about 80 to 200 μm. Thereby, the thickness of the cutting layer sufficient to process into the shape according to the shape of the desired optical surface is obtained. Further, since the white metal-based metal plating layer 20 has good machinability, it is possible to perform precision machining that is difficult to process by grinding, such as a curved surface having a small radius of curvature or an aspherical shape.

  In addition, as the base material 15, you may use any of the cemented carbide which has tungsten carbide (WC) as a main component, a cermet, a silicon carbide, and a silicon nitride instead of stainless steel. In addition, as the metal used in the white metal-based metal plating layer 20, a metal having the same structure as described in paragraph [0021] can be used.

  Moreover, in each said embodiment, although the lower mold | type 12 is made using this invention, you may make the upper mold | type 11 using this invention.

It is sectional drawing which shows the metal mold | die for shaping | molding. It is sectional drawing which shows the lower mold | type demonstrated in FIG. It is a flowchart figure which shows the procedure which manufactures a lower mold | type. It is a flowchart figure which shows the procedure which reproduce | regenerates a lower mold | type. It is sectional drawing which shows the lower mold | type of another embodiment. It is a flowchart figure which shows the procedure which manufactures the lower mold | type demonstrated in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Mold 11 Upper mold | type 12,19 Lower mold | type 13 Glass material 15 Base material 16 Electroless nickel plating layer 17 White metal type metal coating layer 18, 21 Surface protection film layer 20 White metal type metal plating layer 22 Release layer

Claims (6)

An intermediate layer is provided between the electroless nickel plating layer provided as a cutting layer on the base material made of cemented carbide, cermet, silicon carbide, silicon nitride, and stainless steel, and the release layer. In the provided glass optical element molding die,
The intermediate layer is
A white metal-based metal coating layer provided on the electroless nickel plating layer;
A surface protective film layer made of titanium aluminum nitride provided on the metal coat layer;
A glass optical element molding die comprising: In a mold for glass optical element molding in which an intermediate layer is provided between a base material made of cemented carbide, cermet, silicon carbide, silicon nitride, and stainless steel, and a release layer,
The intermediate layer is
A white metal-based metal plating layer provided as a cutting layer on the base material;
A surface protective film layer made of titanium aluminum nitride provided as a protective layer on the metal plating layer;
A glass optical element molding die comprising:   3. The metal according to claim 1, wherein the white metal is a metal mainly composed of at least one of platinum, rhodium, ruthenium, and iridium, or a mixture thereof. Mold for glass optical element molding. Providing an electroless nickel plating layer on a base material made of any one of cemented carbide, cermet, silicon carbide, silicon nitride, and stainless steel;
Finishing the electroless nickel plating layer to a desired accuracy as an optical surface shape by ultra-precision cutting;
Providing a white metal-based metal coating layer on the cut surface of the electroless nickel plating layer;
Providing a surface protective film layer made of titanium aluminum nitride as a protective layer on the metal coat layer;
A method for producing a mold for molding a glass optical element, comprising: Providing a white metal-based metal plating layer on a base material made of any one of cemented carbide, cermet, silicon carbide, silicon nitride, and stainless steel;
Finishing the white metal-based metal plating layer to the desired accuracy as an optical surface shape by ultra-precision cutting;
Providing a surface protective film layer made of titanium aluminum nitride as a protective layer on the cut surface of the white metal-based metal plating layer;
A method for producing a mold for molding a glass optical element, comprising:   6. The metal according to claim 4 or 5, wherein the white metal is a metal mainly composed of at least one of platinum, rhodium, ruthenium, and iridium, or a mixture thereof. A method for producing a mold for molding a glass optical element.

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