JPS60246230A - Mold for press molding of optical glass element - Google Patents

Abstract

PURPOSE:To provide the titled forming mold obtained by applying a noble metal layer to the carbide alloy matrix formed in the form of a pair of press molds, facilitating the high-precision molding, and giving an optical glass lens having excellent image-forming quality without polishing. CONSTITUTION:The matrix made of a carbide alloy composed mainly of WC is formed in the form of a pair of press molds consisting of the top force 11 and the bottom force 12 each having a concave form furnished with a notch 11'' machined by electrical discharge machining. The molding faces 11' and 12' of the press molds are mirror polished with ultrafine diamond abrasive at the maximum roughness of about 0.02mum. The mirror face is coated with a layer of a noble metal alloy consisting of 60-99wt% Pt and the rest part of one or more metals selected from Ir, Os, Pd, Rh and Ru, e.g. by sputtering. The molds 11, 12 are set to the piston cylinders 15, 16 of a press machine, and an optical glass block 17 is pressed in N2 atmosphere under heating with the heaters 13, 14. The formed optical glass lens having high precision is cooled and taken out through the outlet port 19.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a method for manufacturing an optical glass element, particularly when directly press-molding a 11-precision optical glass element without requiring a polishing step after press molding. The present invention relates to a press molding mold for an optical glass element that can be used.

Conventional Structures and Their Problems In recent years, optical glass lenses have been trending toward aspheric surfaces that can simultaneously simplify the lens structure of optical equipment and reduce the weight of the lens portion. In manufacturing these non-swiveled lenses, the optical polishing method, which is the conventional manufacturing method for optical lenses, has difficulty in adding properties and producing R-products, and direct press molding is now being considered. There is.

This direct press molding method involves heating and forming a lump of optical glass on a mold with an aspherical shape that has been prepared in advance to the desired surface quality and degree of area, or forming a lump of glass that has been heated in advance. This is a method of manufacturing optical lenses without the need for hot pressing and molding, and then further processing.

However, the method for manufacturing the optical glass lens described above is
After press molding, the obtained lens image forming product must be so excellent that it is not damaged. In particular, in the case of an aspherical lens, it is required that it can be molded with high surface accuracy.

Therefore, as a mold material, it should have minimal chemical action on the glass at high temperatures, be resistant to damage such as scratches on the glass pressing surface of the mold, and have high fracture resistance V1" against thermal shock. It is necessary to have a certain color quality.

For this purpose, molds made of silicon carbide (5iCi), silicon nitride (Si3N4), etc., molds with a coating film such as SiC formed on high-density carbon, or molds coated with noble metals such as platinum on zirconium oxide are used. It is believed that the following types are suitable, and various studies have been made.

However, since materials such as Sin and Si3N4 have an extremely high degree of 6IJj, it is extremely difficult to add these materials to a spherical or aspherical mold with high precision. Moreover, since these materials are also sintered, Al2O3,8 is used as a sintering aid.
A substance such as 206 that reacts relatively easily with lead glass or alkali glass is used, and the reaction between the mold and the glass progresses when molding is repeated, making it impossible to mold lenses with high precision. The mold made by coating high-density carbon -L with silicon carbide also reacts with glass containing large amounts of lead and alkali elements because the coating film is beta silicon carbide (β-8iC). This method has the disadvantage that it is difficult to mold a glass lens with high precision. It has been found that molds coated with precious metals on top of zirconium oxide have the disadvantage that the coating peels off over time during thermal cycling.

Object of the Invention The object of the present invention is to easily perform the high-precision mold processing required for a mold for direct press molding of a glass lens, and to achieve good image forming quality by using the mold produced in this way. The present invention provides a press-molding mold for an optical glass element that enables direct press-molding of an optical glass lens.

Composition of the Invention The mold for press-molding an optical glass element of the present invention uses a cemented carbide as an art material, which is a product of tungsten carbide)'(W'C)'f, and processes it into the shape of a lens to be molded. , on which iridium (Ir), osmium (O8)
, palladium (Pd), rhodium (Rh) and ruthenium 1. It is characterized by being coated with a precious metal-like alloy layer consisting of at least one element selected from the group consisting of ()tu) and platinum (Pt).

The cemented carbide whose main component is tungsten carbide used as the base material here allows for higher precision than SiC, Si, and N4, which were conventionally used for glass lens press molds, even when performing general grinding. Na type addition
2, and the maximum entrance surface tfl of the mold surface
It has the characteristic of being able to easily reduce Rw) to an accuracy of 0.02/1 so.

Moreover, the cemented carbide used as the base material and iridium (Ir)
), osmium (Os), palladium (Pd).

Since the thermal expansion coefficients of the noble metal layer consisting of at least one element selected from the group consisting of rhodium (Rh) and ruthenium (U) and platinum (PT) are relatively the same, the glass is press-formed. Provides strong adhesive strength that can withstand thermal shock.

Therefore, by using the mold of the present invention, it is possible to overcome the difficulty of high-precision mold processing, which was a drawback of SiC and Si3N4 molds conventionally used for similar purposes. .

Even when glass containing a large amount of alkali elements such as potassium or lead is molded, there is little reaction between the mold and the glass, and the cemented carbide as the base material and the noble metal layer formed on it are strong. Because it is attached to the glass, it can withstand the thermal shock that occurs when glass is repeatedly molded.

In addition, in the noble metal layer formed on the cemented carbide -L, the alloy composition is platinum (Pt) in an amount of 60 to 99% by mass.

The remainder was defined as at least one element selected from the group consisting of iridium (Ir), osmium (Os), barium (Pd), rhodium (Rh), and ruthenium (Ru). This is because the suitability as a mold material for press molding of optical glass elements differs depending on the weight percentage). In other words, if the alloy composition amount (wt%) as claimed in the claims of the present invention is used, it is possible to perform good press molding of an optical glass element, but if the specified composition amount (wt%)
) or less, the strength or hardness of the brushed metal layer is low,
After press molding, fine scratches may occur on the surface of 211.
This is because the 111 gold wind layer coated on the cemented carbide undergoes plastic deformation and the highly accurate surface shape deteriorates. This is because if the composition amount (% by weight) is less than the specified amount, the press-molded glass will be colored and the noble metal layer will easily volatilize at high temperatures.

Description of examples Examples of the present invention will be described below.

A cylindrical We- with a diameter of 30jll+ and a length of 5Q kQ
Two rods of cemented carbide having a composition of 10Tie -10TaC-8Go are prepared, and a concave shape with a diameter of 46n is formed using a discharge lamp TT as shown in FIG. A pair of molds for press molding was formed, consisting of a mold 11 and a concave lower mold 12 with a radius of curvature of 200 mm.

The press-molded surface of this mold was mirror-polished using ultrafine diamond abrasive grains. As a result, it was possible to perform mirror finishing with an accuracy of maximum surface roughness of 0.02 μm in 1 hour. Next, on this mirror surface 14, a 24 m long layer 19 of a binary alloy such as platinum-1]dium (Pt-Rh) alloy, platinum-rhodium-iridium A
(Pt-Rh-Ir) ternary alloy such as alloy layer,
Platinum-rhodium-iridium-palladium (Pt-Rh
-Ir-Pd) alloy layer, platinum-rhodium-iridium-palladium-osmium (Pt-
Ternary alloys such as Rh-Ir-Pa-Os) alloy layers and platinum-rhodium-iridium-palladium-osmium-ruthenium (Pt-Rh-Ir-Pd-Os-Ru
) Six-element alloys such as alloy layers were formed respectively.

The molds 11 and 12 thus produced were set in the piston cylinders 16 and 16 of the press machine shown in FIG.
A lead oxide-based optical glass consisting of 27% lead oxide and trace components was processed into a spherical shape with a radius of 2Q, and the lump was pressed to form a lens shape with convex surfaces on both sides. Mold temperature during glass press molding is 500℃, press pressure is 4oKy/c
rd for 2 minutes, the molded glass was cooled down to 300'C together with the mold] and the molded glass was taken out from the molded glass outlet 19, and the molded glass and the mold were each evaluated. After repeating this pressing process 600 times, the mold used was removed and the surface condition of the mold after 500 presses was observed.

The pressing experiment as described below-1- was repeated on a pair of molds with different alloy compositions as shown in Table 1, and the molded glass and mold after pressing were evaluated. The results are shown in Table 1.

For comparison, we made a mold made of conventionally used silicon carbide, a mold made of high-density carbon coated with silicon carbide, and a mold made of zirconium oxide coated with noble metal. set in the press machine instead of the mold of the present invention.

The glass was press-molded under the same pressing conditions as described above.

These silicon carbide, high-density carbon, and zirconium oxide molds were prepared by grinding in the same manner as the cemented carbide mold described above, and the surfaces were mirror-polished using diamond abrasive grains. Even in this mirror polishing process alone,
The polishing time required to finish the mold surface to a maximum surface roughness of 0.02 μm is 2 to 2 times longer than when mirror polishing cemented carbide.
It required 60 times more.

Using a mold made of silicon carbide and a mold made of high-density carbon coated with silicon carbide, lead oxide optical glass was press-molded under the same conditions as described above. As a result, the press-molded glass became cloudy, Also, traces of the reaction with the glass remained on the mold surface.Furthermore, when similar press molding was performed using a mold coated with zirconium oxide -1- for precious metals, the coating film was removed after about 300 presses. It came off.

On the other hand, the press molding mold for the optical glass element in the present invention is made of lead oxide based optical glass.

Even after double press molding, it does not react with lead oxide optical glass, the precious gold striped layer formed on the cemented carbide does not peel off, and there are no minute scratches on the mold surface. It is superior to the conventionally used press molding molds, and it takes only 1 hour to increase the maximum surface roughness of the mold surface to 0.02/1 m, making it easy to manufacture molds. It was found that the optical glass element could be precisely press-molded.

In Table 1, the solace molding mold marked with * in the upper right corner of Sample 1a is listed as a comparative example in the claims column of the present application.

In this example, the cemented carbide composition used as the base material of the press molding die for the optical glass element was wc-10'l'iG -
10TaC-sCo, f'J4;4J:L,
The cemented carbide composition is limited to the above composition, and V, 1
The main component is WC, and other additives include, for example, 1°iC, '1'aC, NbC, Mo2C, Cr3C.
A cemented carbide containing 2° VC, Go, Ni, etc. can be used. 1. In order to explain the present invention, a concave-shaped press-molding mold for an optical glass element was used, but the shape of the mold surface is not limited to the shape of this example; , etc. may also be suitable for the shape of the optical glass element such as V, ):;iu4.

(Hereinafter referred to as Shimokin White) 3 4 19.

21, - 2 :(λ 23′ The * marked to the right of the black sample indicates a comparative example.

Effects of the Invention As is clear from the explanation below-1-, the press molding mold for the 9Pγ glass element of the present invention is made of super 6ψ alloy,
This is a press-molding mold for optical glass elements, which is characterized by adding this to the press mold of the molding pot and forming a precious metal island layer on top of it. lF+1 density carbon -L coated with silicon carbide, or zirconium oxide -1-
Precious appetizer: Compared to a mold coated with maple, when molded with glass, ht I, t = 4.1 - 1 is less, or general grinding - 1 - upper mirror 1fn addition T is easier. There is one 9fr Il piece that can be made into a mold shape for high sugar.

Therefore, by using the press-molding mold for optical glass elements of the present invention, it is possible to (a) produce optical glass elements with high precision more easily than with conventionally used press-molding molds for optical glass elements. I understand that.

[Brief explanation of drawings]

FIG. 1 shows a mold for press-molding an optical cuff element in an embodiment of the present invention, and FIG. 2 shows a press machine used in the same embodiment. 11...-Upper mold, 12...Lower mold, 11' ・
・Press surface of upper die, 12<...press surface of lower die, 11
' ・Notch part, 13・ ・Heating heater for upper die, 14
...Heating heater for lower mold, 16 ...-Piston cylinder for upper mold, 16...Piston cylinder for lower mold, 1
End: Raw glass lumps, 18: Raw glass supply jig, 19: Molded glass outlet, 20
...Raw material glass preheating furnace, 21...Shell. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
figure

Claims (4)

[Claims] (1) A mold for press-molding an optical glass element, characterized in that the base material is a cemented carbide, and the base material is coated with a noble metal layer. (2) The mold for press-molding an optical glass element according to claim 1, wherein the cemented carbide used as the In material has tungsten carbide (W()) as a main component. (3) The Kikinjima layer contains iridium (Ir), osmium (
Claims characterized in that the alloy is an alloy consisting of platinum (Pt) and at least one element selected from the group consisting of (Pd), rhodium (Rh), and ruthenium (Ru). A press molding mold for an optical glass element according to item 1 or 2. (4) The precious metal layer contains 60 to 99 percent platinum (pt). A special feature characterized in that the remainder is an alloy consisting of at least one element selected from the group consisting of iridium (Ir), osmium (Os), palladium (Pd), rhodium (Rh) and ruthenium (Ru). (f) A press-molding mold for an optical glass element according to claim 1, 2, or 3.