JP3705504B2 - Mold for molding resin lenses for eyeglasses - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to the shape of a mold for cast molding.
[0002]
[Prior art]
In plastic spectacle lenses, lenses with a power in the normal range are manufactured by the casting polymerization molding method, but prescription lenses manufactured based on spectacle prescriptions, especially in terms of intensity number and sphericalness and astigmatism. Almost all lenses are manufactured from a semi-finished lens that is preliminarily manufactured by polishing based on spectacle prescription. In polishing work from this semi-finished lens, both sides are made into a molding surface that does not require polishing and the other side is molded into an unprocessed surface, rather than polishing based on spectacle prescription. It is efficient to polish only the unprocessed surface based on the prescription. A spectacle lens generally has a meniscus shape, a concave surface is formed by a mold having an arbitrary simple curvature, and is usually formed as a spherical unprocessed surface, and a convex surface has a predetermined shape and curvature. Molded with a highly polished mold and formed into a spherically shaped molding surface that does not require polishing, corresponding to the mold surface. The prescription lens desired by the customer is completed and provided by polishing the concave surface of the processing.
[0003]
As described above, in order to complete a semi-finished lens as a prescription lens, it is necessary to polish the concave surface side, and an aspherical shape such as a hyperboloid or an ellipsoid or a complicated toroidal surface is required. When polishing an astigmatism lens to be formed, a variety of complicated jigs and tools are required, and an extremely advanced technique is required. Therefore, there is a drawback that it takes a lot of processing time to obtain a lens with high processing accuracy.
[0004]
In addition, prescription lenses that are finished by polishing semi-finished lenses among plastic single focus lenses are generally used mainly for special powers outside the range normally produced by lens manufacturers. The sphericity and astigmatism are mainly composed of lenses with a considerable number of intensities. For this reason, the lens completed by polishing the concave surface as described above has a considerably thick peripheral edge, which is not preferable in appearance.
[0005]
Furthermore, both spherical and astigmatic degrees have a spherical shape, and a lens manufactured by polishing has the drawback of producing spherical aberration, and since it is an intensity number as described above, the problem of this spherical aberration is more pronounced. It has become big. In particular, plastic lenses with shapes that are extremely difficult to technically mass-produce in terms of polishing processing are complicated in shape and polished rather than being manufactured by polishing each time. The surface that is difficult to process and requires advanced technology is formed as a molding surface corresponding to the mold surface that does not require polishing by using a mold that has high precision with an arbitrary shape and curvature. This is more desirable from the viewpoints of difficulty of polishing, production yield, and processing time.
[0006]
In order to overcome such a problem, the inventors added a convex surface to a spherical raw surface and a concave surface having an aspherical shape such as a hyperboloid or an elliptical surface, or a toroidal surface or the like added to the aspherical shape. An attempt was made to make a semi-finished lens formed on a molded lens surface having a special surface shape and which does not require polishing, and the result was shown in Utility Model Registration Application No. 1-38235. In the practical stage, as shown in FIG. 3, the height H ′ is changed so as to follow the curved surface at the peripheral edge of the mold in order to improve the sealing performance of the mold 7 and the gasket 8 for molding the concave side of the lens. In addition, the gasket was manufactured in conformity with the curved surface E. Since gaskets are manufactured by injection molding, a mold is required, so a large number of molds are required to match changes in the aspherical surface and / or toroidal surface, and the cost is enormous, resulting in an increase in lens cost. It is. Further, as shown in FIG. 3, the adhesion surfaces of the gasket 8 and the mold 7 are only two surfaces of the E portion and the F portion, and the demand for improving the adhesion has increased.
[0007]
[Problems to be solved by the invention]
The problem to be solved is to reduce the types of gasket molding dies and to improve the adhesion between the mold and the gasket.
[0008]
[Means for Solving the Problems]
The present invention relates to a in mold casting mold of the ophthalmic plastic lens, finely polished surfaces in what constitutes a non-spherical and / or toroidal surface, a contact portion of the gasket of the mold In the peripheral part, the side of the precisely polished surface is cut out to form a stepped surface (A) existing on the same plane over the entire circumference .
[0009]
Further, the surface of the abutting portion of the gasket and the mold is formed in a step (A) having a step shape existing on the same plane over the entire circumference, and in the direction crossing the surface adjacent to the inside of the surface (A). And a surface (B) whose height (h) changes following the shape of the precisely polished surface over the entire circumference, and a mold outer peripheral surface adjacent to the outside of the surface (A) (C) is used to improve the sealing performance of the casting mold .
[0010]
【Example】
FIG. 1 is a sectional view of a mold showing an embodiment of the present invention. 1 and 2 are molds, 3 is a gasket, and 4 is a resin injected from an injection port 9. FIG. 2 is an enlarged view of a circle indicated by a broken line in FIG. Plane A at the peripheral portion of the mold 1, without the horizontal stepped annular be in the same plane over the entire circumference, which is notched in precision polishing surface 5 side, B side and C side adjacent to the surface A Is set to be orthogonal to the surface A and lightly pressed against the gasket 3 to improve the sealing performance. Here, the height h of the surface B adjacent to the inside of the surface A and intersecting with the surface A changes following the aspherical surface and / or toroidal surface of the precise polished surface 5 of the mold 1. The surface C is the remaining outer peripheral surface of the mold that is notched adjacent to the outside of the surface A. That is, the conventional mold and big difference is that it is provided with a dihedral of surfaces A and B into the mold. Further, the surfaces A and B are not necessarily perpendicular to each other, and may be two adjacent surfaces.
[0011]
Since the molding surface 6 of the mold 2 is a surface that is polished into a spherical convex surface based on the optometry prescription, it may be a spherical surface having a predetermined radius of curvature, so that the surface D of the portion in contact with the gasket 3 at the peripheral edge is within the same plane. Therefore, the height H serving as a spacer of the gasket 3 is constant.
[0012]
With the configuration described above, only one type of mold may be used when the gasket 3 is injection-molded. However, it is practical to prepare two or three types in consideration of extreme astigmatism. It ’s fine.
[0013]
【The invention's effect】
As described above, when the mold of the present invention is used, cast molding can be performed with one type of gasket even if the precise polished surface is aspherical surfaces such as hyperboloids and ellipsoids and / or toroidal surfaces. Since only one type of mold is required for injection molding of the gasket, it is extremely economical, and the sealability with the gasket is improved to prevent foam generation and early mold release. The present invention can also be used when the objective surface side of the lens is an aspherical surface.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing a relationship between a mold and a gasket.
2 is a partially enlarged view of FIG.
FIG. 3 is a cross-sectional view showing the relationship between a conventional mold and gasket.
[Explanation of symbols]
1, 2 Mold 3 Gasket 4 Resin 5 Precise polished surface 6 Molded surface 7 Mold 8 Gasket

Claims (2)

Ri Na from tubular gasket for coupling the pair of mold and both mold for molding the lens both surfaces, the inner surface of the gasket has a protruding portion having a role of a spacer, the state sandwiching the portion out mold projecting in a mold in casting mold for molding a resin lens glasses, in mold precision ground machined surface as a lens molding surface constitutes the aspheric and / or toroidal surface, a contact portion between the mold of the gasket A resin for spectacles, characterized in that a stepped surface (A) that exists on the same plane is formed on the entire periphery of the peripheral portion that is cut out on the side of the precisely polished surface. Mold for lens casting. The surface of the abutting portion with the gasket of the mold was polished precisely over the entire surface of the surface (A) and adjacent to the inner surface of the surface (A) . The surface (B) whose height (h) changes following the shape of the surface, and the outer peripheral surface (C) adjacent to the outside of the surface (A), The mold for cast molding of the resin lens for spectacles described in 1.

Images