JPS6287420A - Forming of glass lens - Google Patents

Abstract

PURPOSE:To produce a lens having excellent optical face at a low cost, by using a glass raw material having conical shape at least at a part contacting with an optical face of a forming mold, heating the glass material between the forming molds and pressing the material. CONSTITUTION:The surface of a glass material (1, 3) contacting with the optical surface of at least one of the forming mold (6, 8) has conical shape. The glass material is placed at the center of the optical surface of a pair of forming molds (6-6, 8-8) by the aid of a placing jig (5, 7) and pressed in hot state. The weight adjustment of a glass raw material suitable for the forming of a lens can be carried out relatively easily by the above procedure simply by forming one or both ends of a cylindrical glass material for the forming of a lens in conical form. The preparatory processing cost of a glass material can be reduced by this process.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a manufacturing method for forming glass lenses used in optical equipment by precision glass molding.

2. Description of the Related Art In recent years, many attempts have been made to form optical lenses by one-shot molding without a polishing process. The most efficient method is to pour the glass material from a molten state into a mold and press-form it, but it is difficult to control the shrinkage of the glass during cooling.
Not suitable for precision lens molding. Therefore, a common method is to pre-process a glass material into a certain shape, supply it between molds, heat it, and press-form it (for example, Japanese Patent Laid-Open No. 84134/1984).

When producing a precise lens in one molding process using such a method, it is necessary to pre-process the glass material used for molding into a shape as close to the desired lens shape as possible.

In addition, in order to regulate the outer circumference of the lens, a regular mold is used to mold it, but in this case there is no place for excess glass to escape, so it is necessary to precisely match the weight of the glass material to the weight of the intended lens. Furthermore, as disclosed in JP-A-51-60208, it is necessary to center the glass material as much as possible in order to obtain a uniform molded product. Therefore, a method has been proposed in which relief is provided in a part of the body mold and the upper and lower molds to absorb the excess glass and increase the tolerance in the weight matching of the glass (Japanese Patent Application Laid-Open No. 141435/1983).

Furthermore, as disclosed in Japanese Patent Application Laid-Open No. 60-9716, in order to obtain a lens with a smooth surface, preliminary processing is performed to strictly control the surface roughness of the glass material to make the molding surface of the glass material smooth. It is also important to

Problems to be Solved by the Invention However, in the above method, it is necessary to accurately control the weight of the glass material or provide a relief in the structure of the mold. In order to accurately control the weight of the glass material and improve the surface roughness, means such as polishing are required, and there is a problem in that the cost of preliminary processing of the glass is high. Further, when a relief is provided in the mold structure, there is a problem that the molded lens has many optically ineffective parts and the lens becomes heavy.

In view of the above-mentioned problems, the present invention provides a method of controlling the weight of the glass material through relatively easy preliminary processing, making it easy to feed the glass material into the mold, and inexpensively forming a lens having a good optical surface. 1N is provided.

Means for Solving the Problems In order to solve the above problems, the glass lens molding method of the present invention is designed to improve the shape of the glass material, contrary to the conventional method. is different from the desired lens shape. In other words, by cutting a cylindrical glass material and processing both ends or one end into a conical shape, a glass material with good axial symmetry (uniform overlap) is produced. A supply jig is used to supply the material to the center of a pair of molds and a working mold, and heat it.
This method uses pressure molding.

Effect of the present invention By the above-described means, it is possible to match the weight of the glass material to the comparative portion, eliminate the step of polishing the glass material, and easily supply the glass material to the center of the mold. Because the curvature of the desired lens optical surface and the surface shape of the glass material are different, the amount of deformation of the glass that is gradually deformed from the apex of the cone of the glass material to form the optical surface of the lens is large, resulting in a rough surface of the glass material. However, the optical surface of the molded lens has good surface roughness.

EXAMPLE Hereinafter, an example of the method for molding a glass lens of the present invention will be described with reference to the drawings.

FIG. 1 shows some examples of shapes of glass materials in embodiments of the present invention. In FIG. 1, the glass material 1 is made by cutting cylindrical glass into a certain size, and
．． No. 12 was machined into a conical shape using a grinder.

The diameter of the cylinder is controlled within a certain range, and by adjusting the grinding machine, the glass is machined into a conical shape so that the weight of the glass is within a certain range. The surfaces of the conical ends 11, 12 are not specially polished. The glass material 2 has only one end processed into a conical shape and the other end is flat.

The glass material 3 is further processed to eliminate the cylindrical portion. Machining the shape shown in FIG. 1 is relatively simple and requires no special processing such as polishing, so the cost is low. In addition, the glass weight control is 0.0
It can be done with an accuracy of within 5g, and if the processing machine is properly adjusted, it will be 0.0
It can be processed with an accuracy of less than 1 g, and has sufficient weight accuracy as a glass material for precision lens molding.

FIG. 2 is a sectional view showing a state in which the glass material 1 described in FIG. 1 is press-molded to form a biconvex lens. 1 is a glass material, 6 is a pair of molds, and a glass material supply jig 5
is divided into two or more parts, and can be separated and moved out of the mold. The glass material 1 has conical ends and is placed at the center of the optical surfaces of a pair of molds 6 by a supply jig 5. The mold and glass are heated by an appropriate means (not shown), the mold is moved in the pressing direction, the molding surface contacts the apex of the cone of the glass material 1, and molding begins, and the glass material is sandwiched between the molds. Once filled, the supply jig 5 is moved out of the mold. The deformation of the glass begins at the apex of the cone and gradually spreads in concentric circles. By making the apex angle of the cone of the glass material sufficiently small compared to the curvature of the optical surface of the mold, the amount of deformation of the glass is large until it completely follows the surface of the mold, and the deformation can be done with sufficient control. If this is done slowly, the optical surface of the molded lens will have good surface roughness even if the conical surface of the glass material is not a polished surface. Furthermore, since the glass material is placed exactly in the center by the supply jig, the deformation progresses uniformly, making it possible to obtain a very uniform lens.

A second embodiment of the present invention will be described below with reference to the drawings.

FIG. 3 is a sectional view showing a state in which a glass material 3 is press-molded in a second embodiment of the present invention.

In FIG. 3, 3 is a glass material having a conical shape as a whole, 7 is a supply jig, and 8 is a pair of molds. The difference from FIG. 2 is that in order to mold the meniscus lens, an entirely conical glass material is used.

The operations of the supply jig 7 and the mold 8 are the same as in the first embodiment. However, in this case, the concave portion of the lens is formed by deforming the plane of the glass material. If the curvature of the concave surface is large, the amount of deformation of the glass is small, so some surface roughness of the glass material may remain on the lens surface.

In this case, a smooth lens surface can be obtained by using conical glass materials at both ends as in the example shown in FIG. Alternatively, the flat surface may be polished by gI, but the polishing cost is high.

Effects of the Invention As described above, the present invention makes it relatively easy to adjust the stacking of glass materials suitable for lens molding by a simple process of making both ends or one end of a cylindrical glass material used for lens molding into a conical shape. Therefore, the cost of preliminary processing of glass materials can be reduced.

Furthermore, by placing the isotropically processed glass material in the center of the mold using a jig as described above, uniform molding is possible, and by increasing the amount of deformation of the glass, the glass material is This has the effect that a lens with good surface roughness can be obtained even without preliminary polishing.

[Brief explanation of drawings]

FIG. 1 is a sketch showing the shape of a glass material in an embodiment of the present invention, and FIGS. 2 and 3 are cross-sectional views showing a molded state of a lens in an embodiment of the present invention. 1.2.3...Glass material, 5.7...
- Supply jig, 6.8...Medium mold. Name of agent Patent attorney Toshio Nakao 1 person Fig. 1 4~ and one glass 6-AΦ supervisor No. 3 Fig. δ-S most

Claims (2)

[Claims] (1) A method for molding a glass lens, characterized in that a glass material whose surface in contact with the optical surface of at least one mold is conical is held between molds, heated, and press-molded. (2) A supply jig is used to supply a glass material whose surface in contact with the optical surface of at least one mold is conical.
A method for molding a glass lens, characterized by supplying the glass lens to the center of the optical surface of a pair of molds, heating, and press molding.