JP2754042B2 - Composite mold for optical component molding and method for producing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial application field) The present invention relates to optical measuring instruments such as cameras, microscopes, and telescopes, video equipment such as video cameras, video movies, and video discs, audio equipment, facsimile machines, and laser beam printers. Used as parts of optical equipment such as office equipment such as copiers, mainly lenses, prisms,
The present invention relates to a composite mold for molding an optical component suitable for molding a contact disk or a magneto-optical disk, and a method for manufacturing the same.

(Prior Art) Conventionally, as a molding material for forming an optical component having a desired shape by heating and softening glass or plastic and then pressing the same, die steel, stainless steel, cemented carbide, or the like has been used. . However, these mold materials have a problem that they have a short life due to mold release properties and surface accuracy of optical components after molding, in the case of a mold material and a work material that has been softened by heating, particularly, a glass that softens at a high temperature. Numerous mold materials for molding optical parts for solving this problem have been proposed, representative examples of which are JP-A-61-266321 and JP-A-63-503058.

(Problems to be Solved by the Invention) Japanese Patent Application Laid-Open No. 61-266321 discloses a glass in which a mold itself is made of conductive ceramics, a molding surface is mirror-finished, and the mold itself is heated by energization. There is disclosed a molding mold or a glass molding mold in which the molding surface is coated with a coating made of Si carbide or nitride. The glass molding mold of the publication is made of conductive ceramics, and has the advantage that the heating temperature on the molding surface of the mold is made uniform in order to generate heat by energizing the mold itself, and When the molding surface is coated with a film made of carbide or nitride, the material that has been heated and softened is more easily released from the mold than a conventional mold made of steel or cemented carbide. However, especially when the material to be processed is glass, it is necessary to mold at a high temperature. During this high-temperature molding, the molding surface of the mold reacts with the glass and the surface of the glass after the molding process is easily roughened. There is a problem that the subsequent glass is difficult to release from the mold.

Patent application publication No. 63-503058 discloses an Al ₂ O ₃ ceramic material, a Z tool, as a press tool for molding a constituent member made of glass or a glass-containing ceramic material.
A method of using a ceramic material containing rO ₂ and / or HfO _{2 and a} ceramic material composed of tetragonal ZrO ₂ and Al ₂ O ₃ and / or Cr ₂ O _{3 as a} base material component is disclosed. Although this publication discloses a method of using oxide ceramics as a pre-tool for forming glass, the conventional tool materials Al ₂ O ₃ ceramics, ZrO ₂ and / or HfO ₂ The use of an oxide ceramic material such as ceramics as a mold for glass molding. The mold releasability between the glass and the molding mold and the effect of the molding mold on the molded glass, such as the composition of the molding mold No study has been made on the degree of reaction between the components and the glass and the accuracy of the glass molding surface, and all oxide ceramics cannot be used for glass molding tools.
For example, when glass is formed using a conventional mold of Al ₂ O ₃ ceramics or ZrO ₂ ceramics, there are problems that the mold and the glass tend to adhere to each other and that the surface accuracy of the formed glass surface after molding is poor.

The present invention has solved the above-mentioned problems. Specifically, the present invention uses ceramics, cermets, cemented carbides, alloys mainly composed of high melting point metals, heat-resistant steels, superalloys, and the like as base materials. An object of the present invention is to provide a composite mold for molding optical parts and a method for producing the same, in which at least a molding surface of the mold that comes into contact with a workpiece is a coating layer having a low affinity for glass or plastic, particularly at high temperatures. is there.

(Means for Solving the Problems) The present inventors have developed glass molding materials from the viewpoints of wettability, foaming property, corrosiveness and coloring property for glass used in various applications as optical components, particularly for glass in a molten state. After examining the mold material and obtaining the finding that a sintered material of a chromium compound containing chromium and oxygen is excellent as a mold material for glass molding, it has already been provided in Japanese Patent Application No. 63-176535. From the viewpoint of Japanese Patent Application No. 63-176535, the direction of further increasing the strength was examined, and at least the molding surface of the base material that is in contact with the workpiece was formed as a layer of a chromium compound having low affinity for glass, Combination of the chromium compound layer and the material of the base material, especially in consideration of strength, if the chrome compound layer thickness is made from 0.1 to 5 mm in a composite mold, it will be a better mold for optical component molding Based on the knowledge, the present invention has been completed.

That is, the composite mold for optical component molding of the present invention is:
A composite mold having a coating layer formed on the surface of a substrate, wherein at least a molding surface of the composite mold to be processed is formed of a coating layer having a thickness of 0.1 to 5 mm, and the coating layer is oxidized. It is characterized by containing at least one chromium compound among chromium, chromium oxycarbide, chromium oxynitride, and chromium oxycarbonitride as a main component.

The coating layer in the composite mold for molding an optical component of the present invention may be composed of at least one chromium compound among chromium oxide, chromium oxycarbide, chromium oxynitride, and chromium oxycarbonitride, and an unavoidable impurity. The compound comprises at least 50 vol% and, for example, at least one of rare earth metals, metals of Group 4a, 5a, and 6a of the periodic table, oxides, carbides, and nitrides of Al and Si, and mutual solid solutions thereof. Even in such a case, it is preferable because the affinity with glass or plastic as a workpiece can be kept low.
In particular, the oxide phase of Ti, Zr, Hf, Al, Si, Y, La, Ce, Nb, Sm, Dy, Yb and at least one oxide phase among these mutual solid solutions are reduced to 50 vol% or less. Is a coating layer composed of a chromium compound and unavoidable impurities, for example, the coating layer becomes easily sinterable when the coating layer is formed by sintering, the chromium compound grains become finer, and the strength of the coating layer itself, heat resistance Properties such as heat resistance, thermal shock resistance, surface accuracy, etc.
Al ₂ O ₃ ceramics mainly composed of Al ₂ O ₃ , ZrO ₂ ceramics mainly composed of ZrO ₂ , Cr ₂ O ₃ mainly composed of Cr ₂ O ₃
When an oxide-based ceramic such as a base ceramic is used as the base material, the base material and the coating layer react with each other and are bonded to each other, so that a composite mold having high bonding strength is obtained, which is particularly preferable. Further, it is preferable that the chromium compound in the coating layer is replaced by metal chromium of 0.1 vol% or less, because the strength of the coating layer is improved. When the thickness of this coating layer is less than 0.1 mm, it becomes difficult to re-polish and use it, so that it becomes expensive.On the contrary, when the thickness exceeds 5 mm, the formation of a dense, fine and uniform grain coating layer becomes difficult. The thickness of the coating layer is determined to be 0.1 to 5 mm because it becomes difficult and chipping is likely to occur in the coating layer during molding of the mold.

The base material of the composite mold for molding optical parts of the present invention is made of a material that withstands temperature, pressure, thermal shock, deformation due to repetition of heating and cooling during molding of optical parts, such as Al
₂ O ₃ ceramics, ZrO ₂ ceramics, Cr ₂ O ₃ ceramics, SiC ceramics, Si ₃ N ₄ ceramics, Sialon ceramics, TiC cermet, TiC-TiN cermet, Cr ₃ C ₂ cermet, Al ₂ O ₃ cermet, WC-C
o-based cemented carbide, WC-TiC-Ni-based cemented carbide, high melting point metals such as Cr, Mo, W, Ta, Nb, platinum group metals and alloys containing these as main components, heat-resistant steel, Inconel and Waspaloy, etc. Of super alloys. Among them, Al ₂ O ₃ ceramics or C
r ₂ O ₃ ceramics have various properties such as heat resistance and strength.Because they can be joined by interdiffusion with the coating layer and have similar thermal expansion coefficients, the This is particularly preferable because peeling due to a difference in thermal expansion hardly occurs and the adhesiveness is excellent.

When the difference between the thermal expansion of the substrate and the thermal expansion coefficient is large, or in the case of a combination having a problem in adhesion, the intermediate layer having a thermal expansion coefficient between the thermal expansion coefficient of the substrate and the thermal expansion coefficient of the coating layer is used. It is also preferable to form a composite mold interposed between the base material and the coating layer. As this intermediate layer, for example,
Al ₂ O ₃ , TiO ₂ , SiO ₂ , carbides, nitrides, carbonates, nitrides and their mutual solid solutions of metals of the 4a, 5a, 6a periodic table, iron group metals, 6a group metal of the periodic table, etc. Can be mentioned.
This intermediate layer is different mainly depending on the material of the base material.For example, when the base material is a metal material such as heat-resistant steel or super alloy having a large thermal expansion coefficient, Cr ₃ C ₂ -Ni cermet, Ti
An intermediate layer such as a C-Cr cermet is preferable.In the case of a substrate of a Si ₃ N ₄ ceramic or a SiC ceramic having a small coefficient of thermal expansion, an intermediate layer of a Cr ₂ C ₃ -SiO ₂ ceramic is preferable. is there. The intermediate layer may be a single layer, or the intermediate layer on the side in contact with the substrate may be made of a material having a thermal expansion coefficient close to that of the substrate, and the intermediate layer on the side in contact with the coating layer may be made of a material having a thermal expansion coefficient close to the coating layer. It may be a multi-layer structure in which a material having an expansion coefficient is used, or an inclined intermediate layer whose coefficient of thermal expansion continuously changes from the base material side to the coating layer side is also preferable. The thickness of the intermediate layer varies depending on the above-described structure, but when it is set to about 0.01 to 1 mm,
This is preferable because both relaxation of thermal stress and enhancement of adhesion can be satisfied.

When producing the composite mold for optical component molding of the present invention, a method of using a commercially available substrate, forming a coating layer on at least the molding surface of the substrate by thermal spraying, and finish-polishing to a predetermined shape is also considered. However, the following method is preferable in order to obtain adhesion between the base material and the coating layer and to obtain a coating layer having a dense, fine and uniform particle.

That is, the method for producing a composite mold for molding an optical component according to the present invention comprises the steps of: providing a chromium oxide powder, a chromium oxycarbide powder, a chromium oxynitride powder, and a chromium oxycarbonitride powder on at least a molding surface of a substrate to be molded. Or coating a coating material containing at least one of the precursors that become chromium oxide, chromium oxycarbide, chromium oxynitride, and chromium oxycarbonitride after heating, or a green compact made of the coating material And then burying it in boron nitride powder and forming a composite in vacuum, nitrogen gas or inert gas under conditions of a pressure of 50 kg / cm ² or more and a temperature of 1100 ° C. or more. Further pressure
By a method of hot isostatic pressure treatment at a temperature of 1000 kg / cm ² or more and a temperature of 1100 ° C. or more, at least the molding surface comprises a coating layer having a thickness of 0.1 to 5 mm, and the coating layer is formed of chromium oxide, chromium oxycarbide, The method is characterized in that a composite mold containing at least one chromium compound of chromium oxynitride and chromium oxycarbonitride as a main component is obtained.

The base material used in the method for producing a composite mold for forming an optical component according to the present invention is obtained by processing a commercially available material to form a base material for a starting material, or by using a conventional powder metallurgy method to obtain a compact. As a starting base material, a sintered body can be used as a composite body by pressing and heating, and at the same time, a base material formed of a green compact.

The coating substance in the production method of the present invention forms a coating layer when formed into a composite by pressurizing and heating. Specifically, for example, Cr ₂ O ₃ , CrO ₃ , Cr (O, C), Cr (O, N), Cr
(O, C, N) powder or mixed powder of chromium oxide and at least one of metal chromium, chromium carbide, chromium nitride, carbon, or chromic anhydride, chromium alkoxide, etc. Precursors to be a coating layer can be given. A method of applying this coating substance to a slurry in the form of a slurry and applying the same to the starting material base material, or when the starting material base material is a green compact, the coating material may also be formed as a green compact, for example, pressurized and adjacent. it can. However, due to the difference in the shrinkage ratio between the base material and the coating substance during heating under pressure and the difference in the optimum sintering conditions, the base material of the starting material is not a compact but a sintered compact or alloy. It is preferably used as a body.

Next, the substrate on which the coating substance is adhered is buried in a boron nitride powder such as an amorphous boron nitride powder or a hexagonal boron nitride powder, and a pressure of 50 kg / min is applied in vacuum, nitrogen gas or inert gas. cm ² or more, preferably 200 to 500 kg / cm ² , temperature 1100
C. or higher, preferably 1250 ° C. to 1400 ° C. by hot pressing to form a composite consisting of a coating layer and a substrate, or further heat the composite under the conditions of a pressure of 100 kg / cm ² or higher and a temperature of 1100 ° C. or higher. The composite mold of the present invention can be produced by performing the isostatic pressure treatment (HIP treatment).

In the case where the intermediate layer is formed in the manufacturing method of the present invention, for example, the formation of the intermediate layer made of a compound such as TiC or TiN may be performed by a conventional chemical vapor deposition (CVD) or physical vapor deposition (PVD). Preferably, at least one compound phase of carbides, nitrides, carbonates, nitrides and their mutual solid solutions of metals of groups 4a, 5a and 6a of the periodic table and Fe, Ni, C
The formation of an intermediate phase consisting of a cermet composed of o, Cr and at least one metal phase of these mutual alloys can be carried out in the same manner as in the above-mentioned coating layer.

(Operation) In the composite mold for molding optical parts of the present invention, the coating layer acts to prevent reaction, wetting, and welding with the work material, particularly glass, and as a result, discoloration and surface roughness of the work material are prevented. The base material holds the coating layer and acts to cover the strength of the coating layer.

In addition, the method for producing a composite mold for molding an optical component of the present invention makes it possible to form a coating layer having a thickness that is difficult to be buried with boron nitride powder and hot pressed by a conventional chemical vapor deposition method or physical vapor deposition method. In addition, it is possible to form a dense coating layer.

(Example) Commercially available Al ₂ O ₃ ceramic sintered body, TiC cermet sintered body, cemented carbide equivalent to JIS standard P10, heat resistant steel, Inconel 1
00 super alloys and _{50wt% Al 2 O 3 -50wt%} Cr 2 O 3 sintered body, 90 wt
% Cr ₂ O ₃ -10 wt% Zr ₂ O ₂ sintered body, 85 wt% Al ₂ O ₃ -15 wt% Cr cermet sintered body as a base material, and the surface of each base material has an average grain size shown in Table 1. A powder having a diameter of 1.5 μm or less was applied under pressure and pressure or in a slurry state, embedded in BN powder, and heated under pressure under the conditions described in Table 1 to produce a composite. The base material is a cylindrical shape of 10φ × 13mm, and one surface of 10φ is
A 15R concave surface was formed, and a powder of the coating substance shown in Table 1 was pressed or applied to this surface.

The coating layer thickness and the average crystal grain size of the coating layer of the products 1 to 13 of the present invention thus obtained in Table 1 were examined by a scanning electron microscope.
The results are shown in Table 2. Next, the product 1 of the present invention shown in Table 1
To 13 are commercially available sintered Al ₂ O ₃ ceramics, and commercially available ZrO ₂
System sintered body and commercially available SiC sintered body were added as comparative products 1, 2, and 3, respectively, and each was made the same shape, and the 15R surface was mirror-polished to form a composite mold. Was subjected to a molding test. Table 2 also shows the surface roughness of the mirror-polished surface of each sample and the results of the glass forming test.

Glass forming test conditions Mold shape 10φ × 13mm Heating temperature 500 ° C Pressing force 100kg Pressing time 20 seconds Operating atmosphere N _2- (1-3%) O ₂ evaluation Perform continuous forming 250 times in one cycle Judged by roughness and releasability.

(Effects of the Invention) From the above results, the composite mold for optical component molding of the present invention has an effect of being 70 to 1000 times better in the molding of glass as compared with a commercially available ceramic sintered body mold. There is an excellent effect that mass production is possible when applied when polishing after press molding is difficult such as an aspherical lens, for example.

In addition, the composite mold for molding optical parts of the present invention can be used in the atmosphere or in an oxygen-containing gas atmosphere, and for this reason, for example, the surface of the formed glass is less likely to be cloudy and is used in a state after press molding. There is an excellent effect that it can be done.

Continuation of the front page (56) References JP-A-2-26841 (JP, A) JP-A-61-266321 (JP, A) JP-T-63-503058 (JP, A)

Claims (10)

(57) [Claims] 1. A composite mold having a coating layer formed on the surface of a substrate, wherein at least a molding surface of the composite mold on which a material to be processed is formed comprises a coating layer having a thickness of 0.1 to 5 mm. A composite mold for molding optical parts, characterized in that the layer mainly comprises at least one chromium compound among chromium oxide, chromium oxycarbide, chromium oxynitride and chromium oxycarbonitride. 2. The coating layer according to claim 1, wherein said coating layer comprises at least one of oxides of Ti, Zr, Hf, Al, Si, rare earth metals and their mutual solid solutions.
2. The composite mold for molding optical parts according to claim 1, wherein the kind of oxide phase is 50 vol% or less, and the balance consists of the chromium compound and unavoidable impurities. 3. The composite mold for molding optical parts according to claim 1, wherein said chromium compound is obtained by substituting 0.1 vol% or less with metallic chromium. 4. The optical component according to claim 1, wherein said substrate is made of a ceramic sintered body containing aluminum oxide or chromium oxide as a main component. Composite mold for molding. 5. A composite mold in which an intermediate layer is interposed between a base material and a coating layer, wherein at least a molding surface of a material to be processed of the composite mold is formed from a coating layer having a thickness of 0.1 to 5 mm. The coating layer is made of chromium oxide, chromium oxycarbide,
The intermediate layer has at least one chromium compound of chromium oxynitride and chromium oxycarbonitride as a main component, and the thermal expansion coefficient of the intermediate layer is between the thermal expansion coefficient of the base material and the thermal expansion coefficient of the coating layer. A composite mold for molding optical parts, characterized in that: 6. The coating layer comprises at least one of oxides of Ti, Zr, Hf, Al, Si, a rare earth metal and a mutual solid solution thereof.
6. The composite mold for optical component molding according to claim 5, wherein the kind of oxide phase is 50 vol% or less, and the balance comprises the chromium compound and unavoidable impurities. 7. The composite mold for molding optical parts according to claim 5, wherein said chromium compound is obtained by substituting 0.1 vol% or less with metallic chromium. 8. An optical component molding according to claim 5, wherein said base material is made of a high melting point metal, heat resistant steel, super alloy or die steel. Composite mold. 9. The intermediate layer is composed of at least one compound phase of carbides, nitrides, carbonates, nitrides and their mutual solid solutions of metals belonging to groups 4a, 5a and 6a of the periodic table and Fe, Ni , Co, Cr
9. The optical device according to claim 5, wherein the optical device comprises a single layer or a multilayer comprising at least one metal phase among these mutual alloys. Composite mold for parts molding. 10. A method for manufacturing a composite mold comprising a substrate and a coating layer formed on a surface thereof, wherein at least a molding surface of the substrate to be processed is formed of chromium oxide powder, chromium oxycarbide powder, Chromium nitride powder, chromium oxycarbonitride powder,
Or after heating, chromium oxide, chromium oxycarbide, chromium oxynitride,
After coating a coating material containing at least one of the precursors to be chromium oxycarbonitride as a main component, or adjoining a green compact made of the coating material, burying in a boron nitride powder, In nitrogen gas or inert gas, pressure 50kg / cm ² or more,
A method of forming a composite at a temperature of 1100 ° C. or higher, or a method of subjecting the composite to a hot isostatic pressure treatment at a pressure of 1000 kg / cm ² or higher and a temperature of 1100 ° C. or higher, wherein at least the molding surface is 0.1 to A composite mold comprising a coating layer having a thickness of 5 mm, wherein the coating layer mainly comprises at least one chromium compound of chromium oxide, chromium oxycarbide, chromium oxynitride, and chromium oxycarbonitride. Of manufacturing a composite mold for molding optical parts.