JP3042410B2 - Lens molding method and molding apparatus - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method and an apparatus for molding a lens such as a plastic lens or a glass lens.

[0002]

2. Description of the Related Art Conventionally, as a molding apparatus and a molding method of a lens, generally, a heated lens material is sandwiched between a pair of upper and lower molds and pressed to mold. For example, Japanese Patent Application Laid-Open No. Hei 7-291637 has been proposed.

[0003]

However, in the above-mentioned conventional case, the productivity of the lens is low and the cost is high. SUMMARY OF THE INVENTION An object of the present invention is to provide a low cost lens forming method and a lens forming apparatus which have high productivity with a simple configuration and are low in cost.

[0004]

In order to solve the above-mentioned problems, the present invention uses a pair of upper and lower dies slidably fitted between body dies. (1) arranging a plurality of lens forming dies in which a lens element is arranged between an upper mold and a lower mold in a radial manner; A lens molding method is characterized in that a lens molding die is rotated to perform centrifugal molding.

(2) Pallets in which a plurality of lens forming dies having a lens element arranged between an upper mold and a lower mold are radially arranged are stacked in multiple stages, and the pallets are rotated to perform centrifugal molding. And a lens molding method characterized by the following.

(3) Means for radially holding a plurality of lens molding dies each having a lens element disposed between an upper mold and a lower mold, means for heating the lens molding dies, and means for heating the lens molding dies. Means for rotating the mold and performing centrifugal molding.

With the above-described configuration, the present invention can provide a molding method and a molding apparatus which are excellent in the accuracy of the lens surface shape with a simple configuration. Further, the productivity is improved, the apparatus cost is small, and the cost of the lens can be reduced.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention according to claim 1 of the present invention is characterized in that a plurality of lens forming dies having a lens element arranged between an upper die and a lower die are radially arranged, and This is a lens molding method characterized by rotating a mold and performing centrifugal molding, and has an effect that a large number of lenses can be molded at once with high productivity.

According to a fourth aspect of the present invention, a pallet comprising a plurality of radially arranged lens molding dies each having a lens element disposed between an upper mold and a lower mold is stacked in multiple stages, and the pallets are rotated. This is a lens molding method characterized by performing centrifugal molding, and has the effect that a large number of lenses can be molded at once with high productivity.

According to a fifth aspect of the present invention, there is provided means for radially holding a plurality of lens molding dies each having a lens element disposed between an upper mold and a lower mold, and heating and cooling the lens molding dies. And a means for rotating the lens forming die and performing centrifugal forming. The lens forming apparatus has an effect that a large number of lenses can be formed at a time with high productivity.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIGS.

(Embodiment 1) FIG. 1 is a plan view of a principal part showing the concept of a centrifugal molding apparatus according to an embodiment of the present invention, and FIG.
1 is a cross-sectional view of a main part of FIG. 1 cut along a cutting line SS, and FIG. 3 is a cross-sectional view of a lens molding die used in the lens centrifugal molding apparatus of FIG.

In FIG. 3, reference numeral 1 denotes an upper mold, 2 denotes a lower mold,
Reference numeral 3 denotes a vent for discharging gas from the mold and gas to flow into the mold.
Denotes a lens element, and 100 denotes a lens molding die.

The upper mold 1 and the lower mold 2 are made of a ceramic material or the like, and are set to a value smaller than the heat shrinkage of the lens element.

Further, the lens surface shape accuracy of the lens element 11 is made as close as possible to the final lens surface shape accuracy.

The body mold holder 4 is made of a member such as stainless steel, and has a body mold 5 fitted to the upper mold 1.

The body mold 5 is made of a ceramic material or the like.
A through hole 8 is formed in the axis. The through hole 8 plays a role of a cavity for molding the lens element 11 into a desired lens shape, and also maintains the lens surface forming upper mold 1 and lower mold 2 slidably fitted in a predetermined positional relationship. That is,
It has the function of keeping the deviations and inclinations of the mold centers 1 and 2 within desired accuracy.

The upper mold 1 has a flange portion 1B, and forms each lens element 10 heated to a predetermined temperature into a desired lens surface shape.

The insertion depth of the upper die into the die 5 is naturally determined by the flange 1B of the upper die 1 being in contact with the upper surface of the die holder 4. That is, the desired lens thickness can be arbitrarily set by defining the height of the barrel holder 4.

For the purpose of the upper mold 1 constantly pressing the lens surface as the molded lens cools, or the purpose of releasing the molded body from the lens after molding, the members constituting the barrel mold 5 such as ceramics are expanded. The coefficient is configured to be smaller than the expansion coefficient of the lens material.

Further, as described above, the body type holder 4 is made of a metal member such as stainless steel so that the expansion coefficient is made larger than the expansion coefficient of the lens material. The reason why the expansion coefficient of the body-shaped holder is set to be larger than the expansion coefficient of the lens material is to obtain desired lens surface shape accuracy.

That is, when the softened lens element 10 is pressed and formed by the upper mold 1, the lower position of the upper mold 1 is set to the barrel mold holder 4.
Is regulated by the upper surface of

When the flange 1B of the upper mold comes into contact with the upper surface of the barrel mold holder 4, cooling of the molded lens is started while the pressure of the upper mold is maintained, and cooled to a lens take-out temperature lower than the glass transition temperature. .

Cooling the molded lens is nothing less than cooling the barrel holder 4 and the barrel mold 5, and the heat shrinkage of the barrel holder 4 due to the temperature drop is surely larger than the heat shrinkage of the molded lens. With this configuration, the pressing force of the upper mold always acts on the lens during the molding process.

The lens centrifugal molding apparatus 2 shown in FIGS. 1 and 2
00 is a cylindrical housing 207 and the housing 2
07, a rotating spindle 205 rotatably supported at the center of the rotating spindle and slidable in the vertical direction, a rotating drive means such as a motor for rotating the rotating spindle 205, and a hydraulic cylinder for vertically driving the rotating spindle 205. Neither is shown.),
A mounting table 204 fixed to the rotating spindle 205,
It comprises a heating means 201 for heating the lens element 10 and the molding die 100 to a temperature higher than the lens transition temperature, and a lid 206. The heating means 201 is formed by arranging four divided heating blocks in an annular shape.

Reference numeral 202 denotes a fluid supply / exhaust hole for supplying / exhausting a fluid (gas) for heating or cooling the lens molding die and the lens element. Reference numeral 203 denotes the lens molding apparatus 100 of FIG. It is a pallet to hold.

The pallets 203 are stacked and mounted in multiple stages on the mounting table 204 (the embodiment of FIG. 2 shows an example of four-stage stacking).

Next, an example of a process for forming a lens will be described. In the centrifugal pressing of the lens element in FIGS. 1 and 2, after the lens element 10 is heated to a glass transition temperature or higher, the rotation speed of the pallet 203 is gradually increased to 300 to 1
500r. p. m (revolutions / minute), the temperature is maintained for several seconds to several tens of seconds, and then the temperature is gradually reduced. When the temperature reaches the glass transition temperature or lower, the rotation speed of the pallet 203 is reduced.

After the lens is cooled and reaches a temperature at which the lens can be taken out of the mold, the lid 206 is opened, the rotating main shaft 205 is raised, and the pallet 203 is positioned outside the housing 207. Further, each pallet 203 is pulled out from the rotating main shaft 205, the molding die is disassembled, and the lens is taken out.

The process of setting the pallet 203 in the centrifugal molding device 200 → heating → centrifugal molding → cooling → removing the pallet can be performed in about 3 to 5 minutes.

With the above configuration, the lenses can be batch-processed to produce efficiently and at low cost. Also, as compared with a configuration in which the upper mold is pressed by the cylinder press, the press molding can be performed simply and independently at a high pressure with respect to each upper mold. As a result, the lens surface shape accuracy can be improved. Further, it has a feature that the number of centrifugal rotations can be easily set arbitrarily or can be changed.

It is needless to say that the diameter and the thickness of the lens element may be arbitrarily set in the above embodiment. For example, the diameter of the lens element may be set smaller and the thickness dimension may be set larger than the final shape of the target lens.

Further, the use of the barrel-shaped holder is optional, and need not be used separately. Further, the set number of lens molding dies 100 arranged in the centrifugal molding device, the number of rotations of the centrifugal molding device, and the like may be arbitrarily set according to the diameter and material of the lens.

Further, heating and cooling of a lens element and a molding die by supplying and exhausting a heating gas or a cooling gas from a fluid supply / exhaust hole 202 provided in the rotating main shaft 205 may be arbitrarily performed.

[0035]

As described above, according to the present invention, by batch-processing lens elements, a high-precision lens can be obtained efficiently at low cost and without producing large-scale equipment.

[Brief description of the drawings]

FIG. 1 is a plan view of a principal part showing the concept of a lens centrifugal molding apparatus according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view of a main part of FIG. 1 taken along a cutting line SS.

FIG. 3 is a sectional view of a lens molding die used in the lens centrifugal molding apparatus of FIG. 1;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Upper die 1B Flange part 2 Lower die 3 Ventilation hole 4 Body holder 5 Body mold 8 Through hole 9 Hole 10 Lens element 100 Lens molding die 200 Centrifugal molding device 201 Heating means 202 Fluid supply / exhaust hole (heating gas, cooling gas ) 203 pallet 204 mounting table 205 rotating spindle 206 lid 207 housing

Claims (3)

(57) [Claims] 1. A lens element is arranged between an upper mold and a lower mold.
A plurality of lens molds are radially arranged, and the lens
A method of spinning a metal mold and performing centrifugal molding,
A barrel mold in which a lens molding die holds the upper mold and the lower mold
And a trunk holder for holding the trunk.
Make the heat shrinkage of the mold holder larger than that of the lens.
A lens molding method characterized in that: 2. A lens element is arranged between an upper mold and a lower mold.
Means for radially holding a plurality of lens molding dies comprising:
Means for heating the lens molding die, and the lens molding
Means for rotating a mold to perform centrifugal molding, wherein the lens
A molding die holding the upper die and the lower die;
A barrel holder for holding the barrel mold;
The heat shrinkage of the lens is larger than the heat shrinkage of the lens
A lens molding device characterized by the above-mentioned . 3. A plurality of lens molds are radially held.
Means were stacked in multiple stages, rotated and centrifuged.
3. The lens forming apparatus according to claim 2, wherein: