Lens forming method

1 . A lens forming method, comprising:

heating a blank mold with a pre-molding cavity to a first preset temperature until a glass preform in the pre-molding cavity is in a semi-molten state;

applying a first preset pressure to the blank mold, so that the glass preform is extruded to form a lens rough blank with a predetermined shape;

cooling the blank mold and the lens rough blank, separating the blank mold by depressurization, to transfer the lens rough blank to a molding cavity of a high-precision aspherical mold;

heating the high-precision aspherical mold to a second preset temperature until the lens rough blank is softened to a semi-molten state;

applying a second preset pressure to the high-precision aspherical mold, so that the lens rough blank is extruded to form a lens molded part with an aspherical structure;

cooling the high-precision aspherical mold and the lens molded part; and separating the high-precision aspherical mold by depressurization, to remove the lens molded part;

wherein, the second preset temperature is greater than or equal to the first preset temperature, and the second preset pressure is greater than or equal to the first preset pressure;

the blank mold comprises: a first fixed mold with a first molding surface; and a first moving mold with a second molding surface; the first molding surface and the second molding surface are

opposite and spaced apart, to form the pre-molding cavity; multiple first cavities are defined in the first molding surface; multiple second cavities are defined in the second molding surface; on a cross-section parallel to a mold closing direction, each of the multiple first cavities and each of the multiple second cavities has rectangular shape and spaces between the first cavities and the second cavities form pre-molding spaces of the lens rough blank;

the high-precision aspherical mold comprises: a second fixed mold with a third molding surface; and a second moving mold with a fourth molding surface; the third molding surface and the fourth molding surface are opposite and spaced apart, to form the molding cavity; multiple third cavities are defined in the third molding surface; multiple fourth cavities are defined in the fourth molding surface; and spaces between the third cavities and the fourth cavities form molding spaces of the lens molded part.

2 . The lens forming method according to claim 1 , wherein, the first preset pressure applied to the blank mold acts on the first moving mold; and

when the first preset pressure is applied to the blank mold so that the glass preform is extruded to form the lens rough blank with the predetermined shape, a magnitude of a surface force is changed by controlling a distance between parting surfaces of the first moving mold and the first fixed mold, to control a shape of the lens rough blank.

3 . The lens forming method according to claim 1 , wherein, the second preset pressure applied to the high-precision aspherical mold acts on the second moving mold; and

when the second preset pressure is applied to the high-precision aspherical mold so that the lens rough blank is extruded to form the lens molded part with an aspherical structure, a magnitude of a surface force is changed by controlling a distance between parting surfaces of the second moving mold and the second fixed mold, to control a shape of the lens molded part.

4 . The lens forming method according to claim 1 , wherein,

the blank mold is subjected to the heating and cooling steps separately in a first molding chamber of a molding machine, and during the blank mold heating and cooling steps, the first molding chamber is filled with nitrogen gas; or/and,

the high-precision aspherical mold is subjected to the heating and cooling steps separately in a second molding chamber of the molding machine, and during the high-precision aspherical mold heating and cooling steps, the second molding chamber is filled with nitrogen gas.

5 . The lens forming method according to claim 1 , further comprising, vacuuming the pre-molding cavity, before applying the first preset pressure to the blank mold;

or/and,

vacuuming the molding cavity, before applying the second preset pressure to the high-precision aspherical mold.

6 . The lens forming method according to claim 1 , wherein,

the first preset temperature is equal to a glass sag temperature plus T1, and 20° C.≤T1≤40° C.; or/and,

the second preset temperature is equal to the glass sag temperature plus T2, and 20° C.≤T2≤50° C.; or/and,

after cooling the blank mold and the lens rough blank, a temperature of the blank mold is a third preset temperature, wherein the third preset temperature is equal to a glass transition temperature minus T3, and 20° C.≤T3≤50° C.

7 . The lens forming method according to claim 1 , wherein the lens molded part comprises a plurality of lenses arranged in an array, and the plurality of lenses arranged in an array are cut by a laser to obtain individual lenses.

8 . The lens forming method according to claim 1 , wherein the glass preform is a molten glass droplet or a glass substrate.