JP4463656B2 - Reproduction method of mold for molding - Google Patents

Description

  The present invention relates to a method for regenerating a molding die.

  Conventionally, a press molding method is provided for molding a high-precision optical element, for example, a lens such as an aspherical lens, as a molded product. In the press molding method, a lower die and an upper die having a molding surface having a lens shape, and a molding die having a barrel die are used, and a molding material is provided between the lower die and the upper die. A glass preform is set. Subsequently, the molding die is heated to the vicinity of the glass bending point (At) in a non-oxidizing gas atmosphere, and is held by pressing the upper die against the lower die to compress the preform. In this state, the preform is gradually cooled to the glass transition point and further cooled to form a lens. Thereafter, the upper mold can be moved upward to take out the lens.

  Although the glass yield point for lenses used in the press molding method varies depending on the glass material, that is, the glass component, it is about 300 to 700 [° C.], and molding is performed at a relatively high temperature. Therefore, in the molding die, the performance shown in Table 1 is required for the lower die, the upper die, and the barrel die.

  That is, the lower mold, upper mold, and barrel mold have high temperature strength, heat resistance, and oxidation resistance so that they can withstand use at high temperatures, so that a lens can be molded with a desired shape and dimensional accuracy. However, durability is required to withstand long-term use. In addition, for the lower and upper molds, the mold release is performed so that they do not adhere to the softened glass at the time of molding, and the surface accuracy and roughness of the lens for improving the optical properties are only pressure-molded. Specularity is required so that

  Therefore, in the lower mold and the upper mold, ceramics such as silicon carbide (SiC), tungsten carbide (WC), or cemented carbide is used as a base material, and the tip surface of the base material is attached to the lens. After processing into a shape and mirror polishing, nitriding consisting of a nitride of a single metal element such as titanium (Ti), aluminum (Al), zirconium (Zr), hafnium (Hf), etc. to ensure releasability A material film or a double nitride film made of double nitride combined with the nitride is coated as a release film on the tip surface to form a molding surface.

  Further, the tip surface is coated with a noble metal alloy film such as platinum (Pt), iridium (Ir), osmium (Os), rhenium (Re) as a release film, a diamond-like carbon film, a hard carbon film or the like. It can also be coated as a release film.

  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, the various mold release films deteriorate as the press molding is repeatedly performed, causing surface roughness, partial peeling (peeling), and the like, and the molding die can be used. It will disappear.

Therefore, the mold release film is removed by irradiating the mold release film with an ion beam or etching to form a reproduction mold, and the mold is coated on the mold again. Thus, the molding die is regenerated (see, for example, Patent Document 1).
JP-A-5-32424

  However, in the conventional method of regenerating a molding die, when the release film is irradiated with an ion beam, the ion beam acceleration voltage is increased to increase the speed of removing the release film, or the ion current is increased. If it is increased, surface roughness will occur in the reproduction mold. Further, when etching is performed on the release film, etching may be performed up to the base material, resulting in surface roughness on the reproduction master mold.

  As a result, it is necessary to perform finish processing, finish polishing, and the like on the reproduction mold, and the cost of the molding die increases.

  The present invention solves the problems of the above-mentioned conventional molding die regeneration method, can prevent surface roughness from occurring in the regeneration mold, and can reduce the cost. An object of the present invention is to provide a mold recycling method.

Therefore, in the method for regenerating a molding die of the present invention, a base material formed in a predetermined shape, an etching resistant layer made of a material that does not react with an etching solution and coated on the tip surface of the base material, A molding die made of a material that reacts with an etching solution and coated with a thin film layer coated on the etching resistant layer, and a release film that is made of a material that does not react with the etching solution and coated on the thin film layer. Applied.
Then, the thin film layer and the release film are removed by reacting the thin film layer with an etching solution, and the thin film layer is coated on the etching resistant layer in a state where the etching resistant layer is coated on the base material. A release film is coated on the layer.

According to the present invention, in the method for regenerating the molding die, the base material formed in a predetermined shape, an etching resistant layer made of a material that does not react with the etching solution and coated on the tip surface of the base material, A molding die made of a material that reacts with an etching solution and coated with a thin film layer coated on the etching resistant layer, and a release film that is made of a material that does not react with the etching solution and coated on the thin film layer. Applied.
Then, the thin film layer and the release film are removed by reacting the thin film layer with an etching solution, and the thin film layer is coated on the etching resistant layer in a state where the etching resistant layer is coated on the base material. A release film is coated on the layer.

  In this case, when the thin film layer and the release film are removed by the etching solution, the etching resistant layer remains on the base material, but an ion beam is irradiated to remove the thin film layer and the release film. Since it is not necessary, it is possible to prevent surface roughness from occurring in the reproduction mold. In addition, since the etching resistant layer does not react with the etching solution, it is possible to prevent surface roughness from occurring in the reproduction master mold. Therefore, it is not necessary to perform finishing processing, finish polishing, or the like on the reproduction mold, so that the cost of the molding die can be reduced.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In this case, a molding die for molding a high-precision optical element, for example, a lens such as an aspherical lens, as a molded product, and a reproducing method thereof will be described.

  FIG. 1 is a cross-sectional view showing a main part of a lower mold in an embodiment of the present invention, FIG. 2 is a first diagram showing a press molding method in an embodiment of the present invention, and FIG. 3 is in an embodiment of the present invention. FIG. 4 is a second view showing the press molding method, and FIG. 4 is a cross-sectional view of the lower mold in the embodiment of the present invention.

  In the figure, 10 is a mold for molding, 11 is a lower mold as a first mold, 12 is an upper mold as a second mold, and 13 is a trunk mold. The lower mold 11 is provided on a support member (not shown), and includes a flange portion 15 and a lower core 16 as a first core portion extending upward from the flange portion 15. The upper mold 12 is supported by a mold opening / closing device (not shown) so as to be movable in the vertical direction. The upper mold 12 is opposed to the flange portion 17 and the lower core 16 and extends downward from the flange portion 17. The upper core 18 is provided as a core part.

  The body mold 13 is placed on the flange portion 15 and is disposed so as to surround the entire lower core 16 and a part of the upper core 18, and the center of the lower mold 11 and the upper mold 12. At the same time, the upper mold 12 is guided. For this purpose, the lower core 16 and the upper core 18 have a columnar shape, and the body mold 13 is formed of a cylindrical body that tightly covers the lower core 16 and the upper core 18. It is slid with the inner peripheral surface of the trunk mold 13.

  A lower molding surface s1 as a first molding surface is formed at the upper end of the lower core 16, and an upper molding surface s2 as a second molding surface is formed at the lower end of the upper core 18.

  A method for manufacturing a lens in the molding die 10 having the above-described configuration will be described.

  First, in the loading step, the mold opening / closing device moves the upper mold 12 upward, and the loading apparatus (not shown) is a plastic made of glass as a molding material between the lower mold 11 and the upper mold 12. Reform 21 is set. Then, a heating device (not shown) in the non-oxidizing gas atmosphere heats and holds the molding die 10 to near the glass bending point.

  Subsequently, in the pressurizing step, the mold opening / closing device moves the upper mold 12 downward to close the mold, and presses the upper mold 12 against the lower mold 11 to move the preform 21 as shown in FIG. Press to form by compression. At this time, the upper mold 12 and the lower mold 11 are brought into contact with each other, and the preform 21 is deformed in accordance with the shapes of the lower molding surface s1 and the upper molding surface s2. Then, in the cooling step, the preform 21 is gradually cooled to the glass transition point, and then further cooled to form a lens. Thereafter, in the removing process, the mold opening / closing device moves the upper mold 12 upward to open the mold, and the lens is removed.

  By the way, for the lower mold 11, the upper mold 12 and the body mold 13, a lens can be molded with a desired shape and dimensional accuracy with high temperature strength, heat resistance and oxidation resistance so that it can withstand use at high temperatures. Thus, durability is required so that the workability can withstand long-term use. In addition, the lower mold 11 and the upper mold 12 are pressure-molded so that the releasability of the lower mold 11 and the upper mold 12 does not adhere to the softened glass, and the surface accuracy and roughness of the lens to improve the optical characteristics. Specularity is required so that it can be obtained simply by performing.

  Therefore, in the lower mold 11, as shown in FIG. 1, ceramics such as silicon carbide and tungsten carbide, or a cemented carbide is used as the base material 23, and the tip surface s4 of the base material 23 is formed into a lens shape. After being processed into a mirror surface and subjected to mirror polishing, in order to ensure releasability, the release film structure 24 is coated on the tip surface s4 to form the lower molding surface s1.

  Since the lower mold 11 and the upper mold 12 have the same structure, only the lower mold 11 will be described, and the description of the upper mold 12 will be omitted.

  Incidentally, in the molding die 10 for lenses, the dimensional tolerance on the lower molding surface s1 is on the order of several [μm], and the surface roughness of the lower molding surface s1 is 10 to 20 [nm] in terms of Ra or smoother than that. However, if the release film structure 24 deteriorates during repeated press molding and causes surface roughness, partial peeling, etc., the molding die 10 is used. It becomes impossible to do.

  Therefore, as shown in FIG. 1, the release film structure 24 is coated on the tip surface s4 and is made of a material that does not react with the etchant and cannot be removed by the etchant. A thin film layer 32 that is coated on the etching-resistant layer 31 and is made of a material that reacts with the etching solution and can be removed by the etching solution. The thin film layer 32 is coated on the thin film layer 32 and is the outermost surface, that is, the separation constituting the outermost surface. It is formed with a laminated structure composed of the mold film 33. The release film 33 is preferably formed of a material that reacts with the etching solution, but it is not necessarily formed of a material that reacts with the etching solution.

  The thickness of the etching resistant layer 31 is preferably 1 [μm] or less so as not to impair the surface roughness of the tip surface s4 when the thin film layer 32 and the release film 33 are covered. The thickness of the thin film layer 32 is preferably 1 [μm] or less so that the time required for removing with the etching solution can be shortened.

  Next, the regeneration process of the molding die 10 will be described.

  FIG. 5 is a diagram showing a process for regenerating the molding die in the embodiment of the present invention.

  In the figure, 11 is a lower mold, 23 is a base material, 31 is an etching resistant layer, 32 is a thin film layer, and 33 is a release film.

  First, in the etching process, the lower mold 11 is immersed in an etching solution, and the thin film layer 32 and the release film 33 are removed to form a reproduction mold. Accordingly, the etching resistance layer 31 remains on the base material 23. Subsequently, the thin film layer 32 is coated on the etching resistant layer 31 in the first film forming process, and the release film 33 is coated on the thin film layer 32 in the second film forming process.

  By the way, in the second film formation step, a nitride layer made of a single metal element nitride or a multi-nitride layer made of a combination of the nitrides is formed on the thin film layer 32 as a primary treatment film. And then subjecting the primary treatment film to an appropriate oxidation treatment to form the double oxide layer on the outermost surface as a secondary treatment film accompanying the oxidation treatment. On the inner side, that is, between the double oxide layer and the double nitride layer, an oxygen diffusion layer composed of a nitride compound of a metal element of the double oxide and oxygen is formed as an intermediate layer.

  As a result, the release film 33 includes a nitride layer or a double nitride layer coated on the thin film layer 32, an oxygen diffusion layer formed on the nitride layer or the double nitride layer, and the oxygen diffusion layer. The three-layer structure composed of the multiple oxide layers formed in (1), and the lower molding surface s1 is constituted by the multiple oxide layers. In the oxygen diffusion layer, the oxygen concentration gradually decreases toward the inner side, that is, from the double oxide layer to the nitride layer or double nitride layer. The nitride layer or the double nitride layer is formed of a nitride or a double nitride containing the metal element of the double oxide.

  In the present embodiment, the thin film layer 32 is covered with the first film formation step and the release film 33 is covered with the second film formation step. However, the thin film layer 32 is formed in one film formation step. And the release film 33 can be formed simultaneously.

  Thus, when the thin film layer 32 and the release film 33 are removed in the etching step, the etching resistance layer 31 remains on the base material 23, but the thin film layer 32 and the release film 33 are removed. Therefore, it is not necessary to irradiate the ion beam, so that it is possible to prevent surface roughness from occurring in the reproduction master mold. Moreover, since the etching-resistant layer 31 does not react with the etching solution, it is possible to prevent the surface roughness of the reproduction prototype mold. Therefore, since it is not necessary to perform finish processing, finish polishing, or the like on the reproduction prototype mold, the cost of the molding mold 10 can be reduced.

  Further, when the thin film layer 32 is coated, when the method for maintaining the shape, dimensional accuracy, etc. of the reproduction prototype mold is maintained, for example, physical vapor deposition or chemical vapor deposition is performed, the thin film layer 32 is removed in the etching process. In addition, the shape, dimensional accuracy, etc. of the reproduction prototype mold can be maintained.

  Since the thin film layer 32 is formed under the release film 33, the etching resistant layer 31 does not come into contact with the lens even if the release film 33 is peeled off. The pull-out phenomenon that is taken can be prevented from occurring.

  A cemented carbide is used as the base material 23, the tip surface s4 is processed into a lens shape, mirror polished, and then chromium (Cr) or chromium nitride (CrN) is nitrided as the etching resistant layer 31 and nitrided as the thin film layer 32 Titanium (TiN) was coated. Subsequently, the release film 33 includes a double oxide layer containing oxides of titanium (Ti) and aluminum (Al), an oxide diffusion layer, and a titanium aluminum nitride (TiAlN) layer which is a double nitride layer. A layer structure was formed.

  The etching resistant layer 31, the thin film layer 32, and the release film 33 were all 0.2 [μm] in thickness, and each of the etching resistant layer 31, the thin film layer 32, and the release film 33 was coated by a sputtering method. The surface roughness of the lower molding surface s1 was 3 to 4 [nm] in Ra.

  Using the molding die 10 having the above-described configuration, when a lens was molded at a temperature of 580 [° C.] in an atmosphere of non-oxidizing gas, for example, in a nitrogen gas atmosphere, about 2200 [shots] were obtained. Surface roughness occurred in the release film 33 beyond the limit. Therefore, a commercially available titanium nitride slow film solution that dissolves only the titanium nitride film is used as an etching solution, and after removing the thin film layer 32 and the release film 33 in the etching process, the first and second film formations are performed. In the process, the thin film layer 32 and the release film 33 were again coated on the etching resistant layer 31. In the first and second film forming steps, the processing temperature was 25 to 30 [° C.], and the processing time was 3 to 8 hours.

  When the chromium nitride film as the etching resistant layer 31 is formed or not formed, and when the chromium (Cr) film as the etching resistant layer 31 is formed or not formed, the molding die 10 is formed. Table 2 shows the surface roughness of the lower molding surface s1 before use and after regeneration.

  When a chromium nitride film or a chromium film is formed as the etching resistant layer 31, it can be seen that the surface roughness hardly changes before and after the molding die 10 is used.

  And when the lens was shape | molded on the same conditions using the reproduction | regeneration metal mold | die 10, the lifetime same as before reproducing | regenerating the metal mold | die 10 was acquired.

  In addition, when the chromium nitride film and the chromium film are not formed, it can be seen that the base material 23 is corroded by the titanium nitride gradual film solution and the surface is roughened.

  The release film 33 is formed of a nitride film such as chromium nitride, or a noble metal film such as platinum-iridium (Pr-Ir), platinum-rhenium (Pr-Rt), rhenium-iridium (Rt-Ir). Even if it is formed, the shape, dimensional accuracy, etc. of the base material 23 and the etching resistant layer 31 are maintained, and the surface roughness hardly changes before and after the molding die 10 is used.

  In the present embodiment, the case where the etching resistant thin film layer 31 is made of chromium or chromium nitride, the thin film layer 32 is made of titanium nitride, and the titanium nitride film removing solution is used as an etching solution has been described. The etching solution can be selected as appropriate. Table 3 shows an example of the film structure corresponding to the etching solution used.

That is, when the etching solution is sulfuric acid, the etching resistant layer 31 is made of titanium nitride, aluminum oxide (Al ₂ O ₃ ), boron carbide (B ₄ C), titanium carbonitride (TiCN), titanium aluminum nitride, It consists of chromium nitride, chromium nitride titanium (TiCrN), titanium oxide (TiO ₂ ), silicon carbide, carbon (C), silicon dioxide (SiO ₂ ) or aluminum nitride (AlN), and the thin film layer 32 is magnesium oxide (MgO). Or it consists of zirconium carbide (ZrC). When the etching solution is hydrochloric acid, the etching resistant layer 31 is titanium nitride, aluminum oxide, boron carbide, titanium carbonitride, titanium aluminum nitride, chromium nitride, chromium nitride titanium, titanium oxide, silicon carbide, carbon. The thin film layer 32 is made of beryllium oxide (BeO), zirconium oxide (ZrO ₂ ), or zirconium boride (ZrB ₂ ). When the etching solution is nitric acid, the etching resistant layer 31 is made of aluminum oxide, boron carbide, titanium carbonitride, titanium aluminum nitride, chromium nitride, chromium nitride titanium, titanium oxide, silicon carbide, carbon, silicon dioxide. Alternatively, the thin film layer 32 is made of beryllium oxide, magnesium oxide, titanium carbide (TiC), zirconium carbide, or titanium nitride. When the etching solution is hydrofluoric acid, the etching resistant layer 31 is made of aluminum oxide, boron carbide, silicon carbide, carbon, or aluminum nitride, and the thin film layer 32 is titanium nitride, titanium carbonitride, titanium aluminum nitride. It consists of a ride, silicon dioxide or zirconium oxide. When the etching solution is a mixed solution of nitric acid and hydrofluoric acid, the etching resistant layer 31 is made of boron carbide, silicon carbide, or carbon, and the thin film layer 32 is magnesium oxide, titanium carbide, zirconium carbide, titanium nitride. , Titanium carbonitride, titanium aluminum nitride, chromium nitride titanium or chromium nitride.

Furthermore, when the etching solution is sodium hydroxide (NaOH) or a mixed solution of sodium hydroxide and hydrogen peroxide (H ₂ O ₂ ), the etching resistant layer 31 is made of chromium nitride, chromium nitride titanium, beryllium oxide. , Magnesium oxide, aluminum oxide, boron carbide, carbon or aluminum nitride, and the thin film layer 32 is made of titanium nitride, titanium carbonitride, titanium aluminum nitride, titanium oxide, titanium nitride or silicon dioxide.

  In addition, this invention is not limited to the said embodiment, It can change variously based on the meaning of this invention, and does not exclude them from the scope of the present invention.

It is sectional drawing which shows the principal part of the lower mold | type in embodiment of this invention. It is a 1st figure which shows the press molding method in embodiment of this invention. It is a 2nd figure which shows the press molding method in embodiment of this invention. It is sectional drawing of the lower mold | type in embodiment of this invention. It is a figure which shows the reproduction | regeneration process of the metal mold | die in embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Mold 23 Base material 31 Etching-resistant layer 32 Thin film layer 33 Release film s4 Tip surface

Claims (1)

A base material formed in a predetermined shape, made of a material that does not react to the etching solution, and made of an etching resistant layer coated on the tip surface of the base material, a material that reacts to the etching solution, and coated on the etching resistant layer In the method for regenerating a molding die comprising a thin film layer formed and a material that does not react with an etching solution and having a release film coated on the thin film layer,
(A) removing the thin film layer and the release film by reacting the thin film layer with an etching solution ;
(B) In a state where the base material is coated with an etching resistant layer, a thin film layer is coated on the etching resistant layer,
(C) A method for regenerating a molding die, wherein a release film is coated on the thin film layer.

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