JPH0710566A - Molding method and molding device for optical element - Google Patents

Abstract

PURPOSE:To control the medium thickness of the optical element to be molded with a high accuracy. CONSTITUTION:After the medium thickness of the optical element 1 is measured in a measuring section 8, the optical element 1 is transported by a transporting section 7 to a hating section 6 where the optical element is heated. The optical element 1 is transferred to between the upper mold 3 and lower mold 4 of a molding section 5 by the transporting section 7 after the end of the heating. The lower mold 4 is then moved upward by a pressurizing section and the optical element 1 is molded by the upper mold 3 and the lower mold 4. The molding is executed while the pressing deformation quantity of the optical element 1 is adjusted by changing the heating time of the optical element 1 or the pressing force of the lower mold 4 at every press molding by a control section 9 in accordance with the measured value of the medium thickness at this time. The adjustment of the heating time is executed by controlling the driving of the transporting section 7 in the heating section 6. The adjustment of the pressing is executed by controlling the air pressure to be applied to the pressing section 10.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical element molding method and apparatus for molding an optical element by pressing a softened optical material with a pair of molding dies.

[0002]

2. Description of the Related Art Conventionally, when an optical material is heated and softened and then the optical material is pressed by a mold to form an optical element, a means for ensuring the accuracy of the thickness of the molded product and the shape of the molding surface is, for example, It is disclosed in Japanese Patent Laid-Open No. 61-205630.

FIG. 6 is a sectional view schematically showing a molding apparatus described in the above-mentioned Japanese Patent Laid-Open No. 61-205630, in which a lower die 33 is provided at an upper end portion of a piston 31 via an elastic member 32. It is fixed. Further, above the piston 31, there is provided a stopper 35 for stopping the upward movement of the lower die 33 in order to make the optical material pressed between the upper die 34 and the lower die 33 have a desired thickness. ing.

When an optical element is press-formed by the above-mentioned forming apparatus, the lower die 33 is raised by the operation of the piston 31 and the optical material is press-formed in cooperation with the upper die 34. At this time, the piston 31 is brought into contact with the stopper 35, and the lower mold 33 is placed at a position where the thickness of the pressed optical material becomes a desired thickness.
(Piston 31) is stopped. The lower die 33 is moved upward by the elastic action of the elastic member 32 in association with the shrinkage of the optical material due to cooling and solidification, and the optical material is repressurized to form an optical element.

[0005]

Generally, when an optical element is molded by heating and softening an optical material and pressing it with a pair of molding dies, certain molding conditions (heating temperature of the optical material, molding die temperature, It has been confirmed that a constant pressing deformation amount B is always generated under the pressing force, pressing speed, and pressing time), as shown in FIG.

In the above-mentioned conventional molding apparatus, when there is no optical material between the upper and lower molds 34 and 33 as shown in FIG. 6, the ascent of the piston 31 is restricted by the stopper 35 and the elastic member 32 is prevented. The upper end of the elastic member 32 is c without any deformation.
Ascending to the point, the position of the lower die 33 is determined, and it is elevated to the point a.

Next, as shown in FIG. 7, both upper and lower molds 3
When the optical material 36 is inserted between 4 and 33 and press-molded, the lower die 33 stops at a position (point b) where the optical material 36 has changed by a constant pressing deformation amount B. At this time, the elastic member 32 is deformed (deformation amount L), and the piston 31 and the stopper 35 come into contact with each other.

Generally, the relationship between the medium thickness T of the optical element 37, the medium thickness A of the optical material 36, and the pressing deformation amount B is shown in FIG.
As is clear from the equation, T = A−B Here, the pressing deformation amount B is always constant under the constant molding conditions as described above, and thus the optical element 37 to be molded is formed.
The thickness T of the medium thickness depends on the variation amount of the thickness A of the optical material 36. That is, since the accuracy of the inner wall thickness A of the optical material 36 affects the accuracy of the inner wall thickness T of the optical material 37, an accuracy equal to that of the inner wall thickness T of the optical element 37 to be molded is equal to that. There is also a problem that the accuracy of the thickness A of the optical material 36 used is required.

The present invention has been made in view of the above-mentioned problems of the prior art. Even when an optical material having a low precision of medium thickness is used, the medium precision of the molded optical element can be ensured to a desired precision. An object of the present invention is to provide a molding method and a molding apparatus for an optical element.

[0010]

In order to achieve the above object, the present invention corresponds to a desired optical element after carrying an optical material in a heating furnace while holding it by a carrying member and heating and softening it. The optical element is conveyed between a pair of molding dies having a molding surface, and in the molding method of the optical element in which pressure molding is performed by the molding die, the medium thickness of the optical material before heating and softening is measured for each molding, Based on the measured values, the molding conditions of the heating time or the pressing force of the optical material are changed by the control unit for each molding, and the pressure molding is performed.

As shown in the conceptual diagram of FIG. 1, the molding apparatus of the present invention comprises a measuring section 8 for measuring the dimensions of the supplied optical material 1, a heating section 6 for heating the optical material 1, and A molding unit 5 including an upper mold 3, a lower mold 4, a pressure mechanism 10 and the like for press-molding the heated optical material 1, and a measuring unit 8 to a heating unit 6 and molding while the optical material 1 is held on the conveying member 2. Part 5
Based on the data of the optical material 1 measured by the transfer part 7 and the measuring part 8, the heating time of the optical material 1 in the heating part 6 or the pressure at the time of press molding in the molding part 5 is automatically adjusted. It is composed of a controller 9 for adjusting.

[0012]

As shown in FIG. 8, the medium thickness A of the optical material 36 is
When the amount of press deformation between the press-molded optical element 37 and the medium thickness T of the optical element 37 is B, when the optical material 1 having a medium thickness of 6 mm and an outer diameter of 10 mm is press-molded for 60 seconds in heating time, As shown, a constant proportional relationship is recognized between the pressing force and the pressing deformation amount B. Even when the optical material 1 (medium thickness 6 mm, outer diameter φ10 mm) is press-molded with a pressing force of 400 N, as shown in FIG. 3, between the heating time of the optical material 1 and the pressing deformation amount B. It has been confirmed by experiments that a certain proportional relationship is recognized in the.

In the method and apparatus for molding an optical element of the present invention, the above-mentioned proportional relationship is used for molding. By measuring the inner wall size of the optical material 1 before heating by the measuring section 8, the optical material 1 is determined by the control unit 9, and the molding conditions (heating time, pressure molding pressure) that can secure the press deformation amount B of the optical material 1 for keeping the inner thickness of the optical element to be molded constant. By automatically calculating and molding under appropriate molding conditions according to the size of the optical material 1 to be supplied, the precision of the inside thickness of the molded optical element is always kept constant.

[0014]

Example 1 FIG. 4 is a sectional view showing a molding apparatus of Example 1 of the present invention. An upper die 3 and a lower die 4 are coaxially and vertically arranged in the molding portion 5 so as to face each other. The upper mold 3 is the molding chamber 1
1, the lower mold 4 is held on the upper end of a movable shaft 13 connected to the piston shaft of the pressing cylinder 12, and is vertically movable so as to approach and separate from the upper shaft 3. ing. An electric furnace 14 for heating the optical material 1 is installed on the side surface of the molding chamber 11 of the molding unit 5.

A measuring unit 8 for measuring the thickness of the optical material 1 is provided on the side of the electric furnace 14. In the measurement unit 8, a pair of electric micrometers 15 and 16 are coaxially arranged so as to face each other vertically. A pair of electric micrometer 1
5 and 16 are held by guides 17 and 18 so as to be vertically movable, and driven by cylinders 19 and 20 in a direction in which the optical material 1 is sandwiched from above and below.

A controller 22 is connected to the electric micrometers 15 and 16 via a comparator 21. That is, the measured values of the electric micrometers 15 and 16 are taken into the comparator 21, the thickness of the optical material 1 is calculated, and the data is sent to the controller 22.

On the side of the measuring section 8, a conveying section 7 for the optical material 1 is provided. In the measuring unit 8, a transfer arm 23 that holds the optical material 1 placed on the transfer member 2 is provided in a base 24.
It is provided above the guide 25 so as to be movable in the horizontal direction. A cylinder 27 supported on a base 24 is connected to the transfer arm 23 via a support member 26. An electromagnetic valve 28 that enables the intermediate stop of the cylinder 27 is connected to the cylinder 27, and the cylinder 27 is driven to transfer the optical material 1 through the transfer arm 23 to the measuring unit 8, the inside of the electric furnace 14 and the upper and lower molds 3. , 4 and can be stopped. The electromagnetic valve 28 is
The timing of opening and closing the electromagnetic valve 28, which is connected to the controller 22, (operation timing of the transfer arm 23)
Is performed by a signal from the controller 22.

Next, a method of molding an optical element using the molding apparatus having the above structure will be described. First, while being placed on the transport member 2, the optical material 1 is held by the transport arm 23 by a mechanism (not shown). Next, the cylinder 27 and the electromagnetic valve 28 are drive-controlled to move the transfer arm 23 to the measuring unit 8.
, And move the optical material 1 to the electric micrometer 1
The transfer arm 23 is stopped by moving the transfer arm 23. Then, the electric micrometer 15 is connected to the cylinder 1.
9. The electric micrometer 16 is moved downward by the guide 17, and the electric micrometer 16 is moved upward by the cylinder 20 and the guide 18 so as to sandwich the optical material 1.
The inner wall thickness of the optical material 1 is measured by.

After the above measurement, electric micrometers 15 and 1
6 is moved up and down, and the transfer arm 23 is moved by the cylinder 27.
The optical material 1 is conveyed into the electric furnace 14 via the, and the optical material 1 is heated to a moldable temperature. At this time, the controller 22 automatically sets an appropriate heating time according to the medium thickness of the optical material 1 measured in the previous step in accordance with the relationship calculated in advance by the experiment, and the cylinder 27 of the cylinder 27 is set for the heating time. The driving is stopped and the optical material 1 is held in the electric furnace 14. After the heating for the set time is completed, the cylinder 27
Thus, the optical material 1 is transported between the upper and lower molds 3 and 4 of the molding unit 5 via the transport arm 23. Next, press cylinder 1
2 is driven to move the lower mold 4 upward, and the optical material 1 is press-molded by the upper mold 3 and the lower mold 4.

According to the present embodiment, by controlling the heating condition according to the medium thickness of the optical material 1 by using the time-controllable parameter, the amount of pressing deformation of the optical material 1 can be controlled, and the high deformation can be achieved. It is possible to easily secure the medium thickness of the optical element with high accuracy.

[0021]

[Embodiment 2] FIG. 5 is a sectional view showing a molding apparatus according to Embodiment 2 of the present invention. The present embodiment is characterized in that the pressure forming force of the optical material 1 by the upper and lower molds 3 and 4 is controlled to ensure the accuracy of the medium thickness of the optical element. The molding apparatus of this embodiment includes an electropneumatic proportional valve 2 controlled by the controller 22.
9 is provided. The electro-pneumatic proportional valve 29 is connected to the pressing cylinder 12 that moves up and down the movable shaft 13 to which the lower mold 4 is fixed. Air is supplied through the electro-pneumatic proportional valve 29 to adjust the pressing force of the pressing cylinder 12. Is configured to get. Since other configurations are similar to those of the first embodiment, the same components are designated by the same reference numerals, and the description thereof will be omitted.

Next, a method of molding an optical material using the molding apparatus having the above-mentioned structure will be described. First, according to the same operation procedure as in Example 1 above, the optical material 1 whose medium wall thickness is measured is heated and softened in the electric furnace 14 for a certain period of time. Next, cylinder 2
The optical material 1 is conveyed between the upper and lower molds 3 and 4 of the forming unit 5 by the conveying arm 23 by the conveying arm 23, and is pressed by the pressing force of the pressing cylinder 12. The pressing force at this time is obtained by the air pressure supplied to the pressing cylinder 12, and this air pressure is an appropriate pressing force according to the medium thickness of the optical material 1 measured in the previous step in advance. The controller 23 automatically judges according to the relationship calculated in the experiment etc., and the electropneumatic proportional valve 2
I am adjusting with 9.

According to this embodiment, the pressing deformation amount of the optical material 1 can be controlled by adjusting the pressing force of the optical material 1 by the upper and lower molds 3 and 4, and the optical material having a highly accurate medium thickness can be controlled. The material can be molded. Furthermore, since the thickness of the optical material is controlled by changing the pressing force of the optical material 1, there is no influence on the molding cycle time, and a planned molding operation becomes possible.

[0024]

As described above, according to the present invention, the inside dimension of the optical material to be pressed is measured and, based on the measured value, the heating time of the optical material is selected from the molding conditions for press molding. Alternatively, since the pressing force is automatically adjusted by the control unit for each molding, it is possible to always manufacture an optical element having a stable and highly accurate medium thickness.

[Brief description of drawings]

FIG. 1 is a conceptual diagram showing a molding apparatus of the present invention.

FIG. 2 is a graph showing the relationship between the pressing force of an optical material and the pressing deformation amount.

FIG. 3 is a graph showing the relationship between the heating time of an optical material and the amount of press deformation.

FIG. 4 is a cross-sectional view showing a molding apparatus of Example 1 of the present invention.

FIG. 5 is a sectional view showing a molding apparatus of Example 2 of the present invention.

FIG. 6 is a sectional view showing a main part of a conventional molding apparatus.

FIG. 7 is a cross-sectional view for explaining the operation of a conventional molding device.

FIG. 8 is an explanatory diagram showing the relationship between the optical material and the thickness of the optical element.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Optical material 2 Conveying member 3 Upper mold 4 Lower mold 5 Molding part 6 Heating part 7 Conveying part 8 Measuring part 9 Control part 10 Pressing part

Claims (2)

[Claims] 1. An optical material is carried into a heating furnace while being held by a carrying member to be softened by heating, and then the optical element is carried between a pair of molding dies having a molding surface corresponding to a desired optical element. In the method for molding an optical element that is press-molded by the molding die, the thickness of the optical material before heating and softening is measured for each molding, and the heating time of the optical material or the molding condition of the pressing force based on the measured value. A method for molding an optical element, characterized in that the control section changes the pressure for each molding and press molding is performed. 2. A measuring section for measuring the medium thickness of an optical material, a heating section for heating the optical material, a molding section for press-molding the heated optical material, a measuring section, a heating section and a molding for the optical material. And a control unit that automatically adjusts the heating time of the optical material in the heating unit and the molding pressure in the molding unit based on the data of the optical material measured by the measuring unit. A device for molding optical elements.