JPH01115836A - Forming mold for formed glass article - Google Patents

Abstract

PURPOSE:To provide a forming mold having a surface layer formed by dispersing a carbide in a substance composed of at least two components consisting of Pt and Cr, and giving a formed glass article having high precision without polishing after press-forming. CONSTITUTION:The surface layer is formed of a substance composed of at least two components consisting of Pt and Cr and containing 5-40wt.% of Cr. One or more carbides selected from TiC, TaC, B4C, SiC, etc., are dispersed in the substance in an amount of 0.02-30vol.%. An intermediate layer containing one or more components selected from Ni, Ti, Cr, Mo, etc., and their mixture is interposed between said surface layer and the substrate base. The surface layer of the forming mold has dense texture, high hardness and strength, excellent workability and chemical reaction resistance and good releasability of the press-formed glass article.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a mold for press-molding glass, and particularly to a mold for molding into a high-precision glass molded body that does not require polishing after press-molding. Regarding molds.

(Prior art) In general, when forming glass by press molding, pre-softened glass to be formed is placed (or The surface layer of the mold is transferred to the glass to be molded by placing the molded glass in a mold and then heating and softening it, and applying a predetermined pressure to the mold. Therefore, since the shape of the surface layer of the mold is directly transferred as the surface shape of the glass molded object, the mold has no defects such as pores in the surface layer, and can be precisely processed into a dense and mirror-like surface. It is required to meet requirements such as maintaining sufficient hardness and strength at high temperatures.

Conventionally, materials for such molds include silicon carbide (SiC) and silicon nitride (StiC).
N4) (Japanese Unexamined Patent Publication No. 52-45613), tungsten carbide (Japanese Unexamined Patent Publication No. 56-59641), zirconium oxide (ZrOz) as a base material, and platinum-rhodium (Pt-Rh) alloy or platinum - A method in which a coating film of iridium (PL-1r) alloy is formed has been proposed (Japanese Patent Application Laid-open No. 176930/1983).

(Problem to be solved by the invention) However, although molds with a surface layer of silicon carbide or silicon nitride are dense and have excellent hardness and strength, they contain a large amount of lead in the glass to be molded. When a heavy flint-based optical glass containing lead is used, it has high chemical reactivity with lead, making it difficult to mold into a high-precision glass molded body.

Next, although tungsten carbide molds have excellent workability, they oxidize at high temperatures (the mold surface becomes rough, making it impossible to maintain the optical surface. Also, there is the problem of tungsten carbide molds reacting with the glass being molded). There was also.

In addition, it is said that the advantage of coatings formed with platinum-rhodium or platinum-iridium alloys is that they do not cause chemical reactions with the glass to be formed, but according to experiments conducted by the present inventors, There has been a problem in that mold releasability from the glass molded product has been poor since the beginning of press molding.

(Means for Solving the Problems) In the mold for a glass molded article according to the present invention, the surface layer of the mold is formed by dispersing carbides in a substance consisting of at least two components, platinum (Pt) and chromium (Cr). This is what is being done.

Preferably, the substance consisting of at least two components, platinum (Pt) and chromium (Cr), contains 5 to 5 chromium (Cr).
40 wt%, and the carbide is Tic, TaC, B, C
, 5iCSHfC, and ZrC5VC, and the dispersion amount thereof is 0.02 to 30 vol%.
Further, between the surface layer and the underlying base, nickel (Nt), titanium (Ti), chromium (Cr), molybdenum (Mo), cobalt (Co), titanium nitride (T i N) is present. , titanium carbide (Tic),
An intermediate layer containing at least one selected from silicon carbide (S i C) and mixtures thereof is interposed.

These surface layers and intermediate layers are formed on a substrate processed into a predetermined shape by a sputtering method, an ion blasting method, or the like. The film thickness is preferably about 0.05 to 10 μm. If it is too thin, it will be difficult to obtain a uniform film, and if it is too thick, not only will the film formation time become longer, but the surface condition of the film will become rough.

In addition to chromium, iridium (
If carbides are dispersed in a platinum alloy containing Ir), rhodium (Rh), and gold (Au), -! It can withstand use in high-temperature presses.

The 51 materials for the mold are not particularly limited as long as they satisfy the hardness, strength, heat resistance, etc. generally required for the base, and include stainless steel, tungsten carbide (WC), zirconium oxide (ZrO□), and cermet. , silicon carbide (S i C), silicon nitride (SisNn), and the like can be used. Further, as long as the pressure during press molding does not cause a problem in deformation of the base, the base material may be the same alloy as the materials of the above-mentioned surface layer and intermediate layer.

(Function) The surface layer of the mold of the present invention not only has good density, hardness, strength, workability, and chemical reaction resistance, but also has good releasability from a press-molded glass molded body. In addition, crystal growth is suppressed and film roughness is suppressed. That is, platinum-chromium alloy (platinum 50-t% or more,
Carbide, specifically Ti, in chromium 5-40-t%
C, TaC, BaC.

By dispersing SiC, HfC, ZrC1VC, etc., it is possible to particularly improve mold releasability from the glass molded body and maintain surface accuracy.

The reason for limiting the dispersion to 0.02 to 30 vol% is that if the carbide content is less than 0.02 vol%, the hardness will be low and scratches will easily occur, and the dispersion effect will suppress crystal growth and prevent film roughness. difficult to obtain, on the other hand, 30νo1
This is because if it exceeds %, the mold releasability from the glass molded object will deteriorate.

Further, the intermediate layer has the effect of increasing the affinity between the base and the surface layer and extending the life of the mold.

(Example) FIG. 1 is a cross-sectional view of a mold showing an example of the present invention. The mold is composed of an upper mold 1 and a lower mold 2. Upper mold 1
and the lower mold 2 are arranged inside the guide mold 3 so that their outer peripheral surfaces slide on the inner peripheral surface of the guide mold 3. These upper mold 1 and lower mold 2 each consist of a base 1a and a surface Jllb, a base 2a and a surface layer 2b, and the surface layer 1b.

2b are arranged facing each other.

The bases 1a and 2a are made of tungsten carbide that has been made dense by HIP treatment during sintering, and is made into a cylindrical shape (
One end surface is ground into a concave spherical shape, and as a final finish, it is polished to a high-precision optical mirror surface using a diamond grindstone, and each is made into a concave spherical surface with a predetermined radius of curvature (32 mm). processed. The surface roughness of this concave spherical surface was 100 Å or less.

The concave spherical surfaces of the bases 11a and 2a were formed using a sputtering device and targets having the material compositions of Examples 1 to 21 shown in the table, and a surface J of a predetermined thickness was formed under predetermined film forming conditions.
ilb, 2b was formed. In addition, in this case, the bases 1a, 2
In order to further strengthen the adhesion between the substrates 1b and 2b, it is effective to clean each surface of the substrates 1a and 2a by reverse sputtering prior to forming the surfaces jllb and 2b.

For example, in Example 1, the argon gas pressure is 1 xlo-''
l' o r r, platinum-chromium 5wt%, DCIKW
, 500 people/1lljrl, titanium carbide, RF
The test was carried out at 400 W, 5 persons/min (dispersion: 1 vol%), an inter-electrode distance of 100 mm, and a rotation speed of 2 Orpm, and the film thickness was 0.5 μm.

In addition, in this example, we have described binary sputtering in which separate targets of platinum-chromium and titanium carbide are sputtered at the same time. A target may also be used. Furthermore, the target itself may be decentralized. In any case, the sputtering rates of each are considered and combined.

In this example, the guide mold 3 is the base ff1l of the upper mold and lower mold.
It is made of tungsten carbide similar to a and 2a.

FIG. 2 is a sectional view of a mold showing another embodiment of the present invention. The upper mold 1' and the lower mold 2' of this embodiment are arranged between the base 1a and the surface layer 1b and between the base 2a and the surface layer 2, respectively.
It is different from the upper mold 1 and the lower mold 2 in FIG. 1 in that the first intermediate layer 1c and the second intermediate layer 2d are interposed between the first intermediate layer 1c and the second intermediate layer 2d between the first width 1712c and the second intermediate layer 2d. However, the structure is otherwise the same. The middle layer is shown as two layers, but
There may be only one layer or three or more layers. In the table, Examples 11 to 13, 16 to 19, and 21 are examples in which the intermediate layer is only one layer, and Example 14 is an example in which the intermediate layer is two layers.
．． 15 and 20.

For example, in Example 11, these intermediate layers and surface layers are formed by ion etching the substrates 1a and 2a, and then using the ion blating method under predetermined film forming conditions (degree of vacuum 5 x
to-”r o r r, film-forming speed 300 people/1Ins
The first intermediate N made of titanium with a substrate voltage of -300 V')
After forming films of lc and 2c (film thickness 0.05 μm), sputtering was performed using platinum (95 wt%)-chromium 5 wt% and titanium carbide (TiC) as targets under the predetermined film formation conditions (described above). It was formed by forming surface layers 1b and 2b (thickness: 3.0 μm).

In Example 20, after ion etching the substrates 1a and 2a, a film was formed on the concave spherical surface by the ion blating method under predetermined conditions (nitrogen gas pressure 5 Xl0
-'T o r r , film formation rate of 300 people/min.

A second intermediate film 2d (film thickness 0.3 μm) made of titanium nitride was formed at a substrate voltage of −300 V). Next, a first intermediate layer IC made of nickel is formed by a sputtering method under predetermined film forming conditions (argon gas pressure I
.
-iU';tsuL (10wt%) alloy and titanium carbide (T i C) were used as targets, and predetermined film formation conditions (
above) and the surface layers 1b, 2b (M thickness 1.Oam
) A film was formed.

In other Examples, the intermediate layer and surface layer were formed by substantially the same method as these.

(The following is a blank space.) Next, how to use such a mold will be explained using the mold shown in FIG. 1 as an example.

FIG. 3 is a sectional view showing the main parts of the press molding machine.

This press molding machine includes the above-mentioned upper mold 1, lower mold 2, and one guide mold 3, and a glass to be formed 4 is placed on the lower mold 2. These molds 1, 2.3 are supported by a support base 6 also made of stainless steel via a holder 5 made of stainless steel and having an 11-shaped cross section. Reference numeral 7 denotes a push rod made of stainless steel. These are housed inside a quartz tube 8, and the molds 1, 2.3 and the glass to be formed 4 are heated by an induction heating coil 9 placed on the outer periphery. It is lowered to the head of the mold 1, and the glass to be formed 4 is press-molded. Temperature control is performed by measuring the mold temperature with a thermocouple 10 disposed inside the lower mold 2. Next, a specific example will be explained.

As the glass to be formed 4, the glass composition is -t% and Si
OZ: 27.8+ A 1. z03:2.0. N
a! O: 1.81 KzO: 1.2. PbO:
65.2. Heavy flint optical glass (transition temperature 435°C) with T i Oz: 2.0 was processed into a spherical glass lump with a diameter of 10 mm, and the mold temperature was 500°C and the pressure was 40 kg in an N2 gas atmosphere. /c was added for 30 seconds. After that, the pressure is released, and the press-molded glass molded body is slowly cooled to the above transition temperature while in contact with the upper mold 1 and the lower mold 2, and then allowed to cool to room temperature.
The glass molded body formed into a biconvex spherical lens is taken out from the mold.

The above press molding method is similarly performed using the mold shown in FIG. Then, in the press molding machine shown in FIG. 3, the heavy flint glass was molded 1000 times each under the same conditions as described above using the upper and lower molds having the surface layer or intermediate layer of Examples 1 to 21. I did it repeatedly. As a result, for all molds of Examples, the glass molded product had good releasability from the mold, and no chemical reaction was observed on the contact surface with the mold.
The surface area and mirror surface of the lower mold surface layer were maintained in their original state, and the surface precision of the glass molded product was 100 Å or less, and the transparency was also good.

For comparison, press forming was carried out in the same manner as in the above-mentioned example using molds in which coating films of platinum-rhodium and platinum-iridium alloys were formed as surface layers. The mold release properties between the glass molded body and the mold were poor, and it was observed that a chemical reaction occurred at the mutual contact surfaces.

Although the shape of the surface layer of the mold has been described above as a concave spherical surface, the present invention is not limited to such a shape, and any shape such as a convex spherical surface, an aspherical surface, a flat surface, etc. may be used.

In addition, the intermediate layer has the same effect as long as it contains the substance used in each of the above-mentioned examples as a main component. It may be something.

Furthermore, since good results were obtained using heavy flint optical glass, which is relatively easy to cause chemical reactions, other optical glasses can also be molded using the mold of the present invention. It goes without saying that it can be done.

Note that the surface layer of the mold of the present invention may be oxidized during film formation and press molding, but even if it is oxidized, there is no problem in its use.

Moreover, some kind of coating layer may be further formed on the surface layer, and the coating layer may be interposed between the surface layer and the glass to be formed.

(Effects of the Invention) According to the present invention, the surface layer of the mold is formed by dispersing carbide in a substance consisting of at least two components, platinum and chromium, which improves density, hardness, strength, and chemical resistance. Good results can be obtained in both reactivity and retention of surface precision by suppressing crystal growth, and the mold releasability from the glass molded body is also improved.

[Brief explanation of the drawing]

Fig. 1 is a sectional view of a mold showing one embodiment of the present invention;
The figure is a sectional view showing another embodiment of the present invention, and FIG. 3 is a sectional view showing an example of the configuration of a press molding machine. 1.1'-upper mold, la, 2a-base, lb, 2b-one surface layer, lc, ld, 2c, 2d... intermediate layer, 2.2'
・-Lower mold. Applicant Tanaka Kikinzoku Kogyo Co., Ltd. Hoya Co., Ltd. Figure 1 Figure N2 Figure 3

Claims (4)

[Claims] (1) A mold comprising a base and a surface layer, in which the shape of the surface layer is transferred to the glass to be formed by press molding to form a glass molded object, in which the surface layer is made of at least platinum (Pt) and chromium (Cr). A mold for a glass molded article, characterized in that it is formed by dispersing carbide in a substance consisting of two components. (2) The surface layer is mainly composed of platinum (Pt) and chromium (C
The mold according to claim 1, characterized in that the mold is formed by dispersing carbide in a substance consisting of at least two components containing 5 to 40 wt% of r). (3) Carbide is TiC, TaC, B_4C, SiC, H
The molding according to claim 1 or 2, wherein the molding is made of at least one selected from fC, ZrC, and VC, and is formed by dispersing 0.02 to 30 vol%. Type. (4) An intermediate layer is provided between the base and the surface layer, and the intermediate layer is composed of nickel (Ni), titanium (Ti), and chromium (Cr).
), molybdenum (Mo), cobalt (Co), titanium nitride (TiN), titanium carbide (TiC),
4. The mold according to claim 1, wherein the mold is made of a material containing at least one selected from silicon carbide (SiC) and a mixture thereof.