JPS63123821A - Production of material for glass molding - Google Patents

Abstract

PURPOSE:To obtain high-accuracy glass molding material efficiently and inexpensively in preliminarily processing the glass molding material by etching method, by supporting parts except a face to be molded, corresponding to an optical face, by an acid-resistant and flexible member and etching. CONSTITUTION:A glass material 2 is attached to a hole part of a rubber plate 1 subjected to boring processing, immersed in an etching solution 3 (e.g. hydrofluoric acid) packed in a container 4, only part of the glass material 2 not covered with the hole part is etched, washed with pure water and dried. Consequently, the glass molding material having excellent shape dimensional accuracy, weight accuracy and face accuracy are obtained. The material is press molded precisely and an optical element having high-accuracy transfer face can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention involves placing a predetermined glass molding material between a pair of molds each having a mold corresponding to the shape and surface precision of a desired optical element, and molding the glass molding material. This method is related to a method for manufacturing a glass molding material used in a manufacturing method in which pressure molding is performed while heating to a suitable temperature (hereinafter referred to as precision press method).

Conventionally, optical elements such as glass lenses have been manufactured by a polishing method. However, optical equipment is moving towards aspherical lenses due to the need to reduce weight and cost.

Manufacturing this aspherical lens by the polishing method requires advanced technology, a lot of manpower, and time, and it is difficult to manufacture it in large quantities and at low cost.

For this reason, there is a precision press method as a method for manufacturing aspherical lenses.

The glass molding material used in this technology requires preliminary processing before pressing to obtain higher quality, and the precision and weight of the surface corresponding to the optical surface of the target optical element,
Shape and dimensions must be strictly controlled.

Surface accuracy in preliminary machining, [For L shape dimensions,
Although this can be achieved by sanding and mirror finishing in conventional polishing methods, these methods are inefficient and the resulting glass molding materials are very expensive.

As a means of solving this problem, it is conceivable to perform an etching process on the coarsely ground separate product during preliminary processing.

Etching can achieve a surface roughness of 0.05 μm or less, so it is sufficient as a preliminary processing for precision presses.
It is difficult to apply a uniform surface treatment to the entire surface of the glass, and it is difficult to ensure that the weight accuracy and shape and size accuracy of the treated product are within usable limits.

Furthermore, when precision pressing is performed on a glass molding material outside the usage limit, the pressure between the mold surface and the glass material surface becomes uneven, making it difficult to obtain a good transfer surface.

In order to solve the above-mentioned problems, the present invention provides a method for efficiently, accurately, and stably manufacturing a material for glass molding, and provides a method for manufacturing a material for glass molding that corresponds to the optical surface of a desired optical element. By holding the surface of the material other than the surface to be molded with an acid-resistant and flexible member, acid can be prevented from entering the holding portion, and only the surface to be molded of the glass molding material can be etched.

This method is characterized by the fact that there is no overlapping of glass materials or contact with the container, which are considered to be the cause of poor accuracy in etching processing, so that extremely homogeneous processed products can be obtained.

In addition, it is easy to handle the glass material in the etching process, and the amount of etching processing can be controlled easily, and it is easy to create a large number of holding parts in the member that holds the glass material, so that a large amount of glass material can be processed at once. is possible.

FIG. 1 shows an example of implementing the present invention.

In the figure, 1 is a rubber plate with holes, 2 is a glass material, and 3
is an etching solution, and 4 is a container.

FIG. 2 is a cross-sectional view showing a meniscus-shaped glass material 2' attached to the hole in the rubber plate, and FIG. 3 is a sectional view showing the rubber plate 1.
FIG. 3 is a cross-sectional view showing a state in which a biconvex glass material 2'' is attached to the hole.

Example: SF-1 was selected as the glass material, and its shape was adjusted to an outer diameter of 8.
It was roughly ground into convex and concave shapes with a center thickness of 3.2 mm, a weight of 719 mg, and a radius of curvature of 6.5 mm.

This glass material was attached to a butyl rubber plate processed to have a wall thickness of 3 mm and a hole diameter of 7.8 mm, immersed in hydrofluoric acid for about 6 minutes, washed with pure water, and dried. As a result, the average center thickness is 3.0 mm, the average amount i is 1674 m g, and the average radius of curvature is 8. A 4 mm glass molding material was obtained.

As a comparative example, a concave and convex glass material with an outer diameter of 8.2 mm, a center thickness of 3.2 mm, a weight of 755 mg, and a radius of curvature of 6.5 mm was placed in hydrofluoric acid to etch the entire surface, and then soaked in pure water. After washing and drying.

As a result, a glass material having the same average outer diameter, center thickness, weight, and radius of curvature as the present invention was obtained.

Table 1 is a table showing the standard deviation of the edge diameter, center thickness, and weight before and after the etching treatment in Table 1 in the present invention and comparative examples.

In Table 1, it was confirmed that the present invention maintains the shape accuracy of the coarsely ground product regarding the edge diameter.

In addition, the present invention has a center thickness of 12% and a weight of 1% compared to the comparative example.
The variation was reduced by 5%.

Precision press molding was performed on 30 pieces of each of these glass molding materials. The molding conditions are a mold temperature of 5 in a nitrogen atmosphere.
The temperature was 25°C and the pressure was 30 kg/cm2. Tables 1 and 2 are tables showing average wavefront aberrations of optical elements subjected to precision press molding.

Table 2 Table 2 shows the edge diameter, center thickness and i according to the present invention.
The pressed product using a stable glass molding material with high precision in terms of t has an average wavefront aberration of 0.007λ compared to the comparative example.
An optical element having a highly accurate transfer surface could be obtained.

As described above, the manufacturing method of the present invention is characterized in that only the surface to be formed is etched, and the shape, weight accuracy, and surface accuracy, which are important factors for glass forming materials used in precision presses, are sufficiently etched. It becomes possible to efficiently and inexpensively produce a satisfactory material for glass molding.

Although butyl rubber was used as the holding material for the glass material in the examples, it is not limited to this, and other materials such as fluoro rubber that are acid resistant and flexible enough to prevent penetration of the etching solution may also be used. Although a lens is shown as an element, it goes without saying that the same applies to optical elements such as prisms.

Therefore, the present invention has extremely great value in improving the precision and reducing the cost of optical elements obtained by precision pressing.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing one embodiment of the present invention. Figure 2 is a sectional view with the material attached, and Figure 3 is a sectional view with other materials attached. In the figure, 1 is a rubber plate and 2 is a material. Figure 1 Section 2 Figure 3 Procedures for writing amendments) 2. Name of the invention Method for manufacturing glass molding materials 3. Person making the amendment Relationship to the case Patent applicant address (residence) 3 Uchikanda, Chiyoda-ku, Tokyo Chome 15-4
No. 0 November 4, 1986 (Shipping date: November 1988)
month 24th) b, - length - 1,゛

Claims (1)

[Claims] By holding the surface of the glass molding material other than the molded surface corresponding to the optical surface of the desired optical element with an acid-resistant and flexible member and etching it, the glass molding material corresponding to the optical surface of the desired optical element can be formed. A manufacturing method that processes the surface to be molded.