JPH0748133A - Method for forming optical element and apparatus therefor - Google Patents

Abstract

PURPOSE:To easily obtain the optimum value of the condition to form an optical element in a short time while keeping the necessary accuracy. CONSTITUTION:In the step 1 for measuring the wall thickness of the supplied material, the thickness of the central part of an optical element 5 is measured by a displacement gauge 6 and the measured data are inputted into a processing unit 19. A heater 7 is controlled by a heater-controlling apparatus 8 in the heating step 2 by the signal transmitted from the processing unit 19. In the pressing step 3, the upper and the lower molds 9, 10 are controlled to prescribed temperatures with heaters 11, 12 by heater-controlling apparatuses 15, 16 based on the signal transmitted from the processing unit 19. The value measured by a pressure sensor 13 is inputted to the processing unit 19 via a pressure- sensor amplifier 17. The pressure of a hydraulic cylinder 14 is varied based on the signal transmitted from the processing unit via a pressure-regulation apparatus 20. In the step 4 to measure the wall thickness of the formed material, the central wall thickness of the optical element 5c is measured by a displacement gauge 18 and the measured data are inputted into the processing unit 19.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a molding method and apparatus for pressure molding an optical element.

[0002]

2. Description of the Related Art Conventionally, an optical material that has been softened by heating (hereinafter,
When an optical element is obtained by press-molding a (gob) with a metal mold, measures are taken to prevent sink marks due to local shrinkage in the cooling step and to ensure medium-thickness accuracy.

An example of a molding method which takes the above measures is the invention described in JP-A-61-197428. The above invention is required as an optical element without causing defects in glass while maintaining a highly accurate surface shape by setting the pressing force, the upper and lower mold temperatures, the optical element temperature, and the pressing time to appropriate values. It is intended to ensure the accuracy of

[0004]

However, the above-mentioned prior art has the following problems. That is, the setting of the pressing force, the upper and lower mold temperatures, the gob temperature, and the pressing time in the device until the start of continuous production is determined based on the data obtained by the operator repeating the experiment. Since it requires a large amount of cost and a long period of time, there is a problem that startup is not easy when the type of optical element is changed. In addition, since data setting requires the operator's know-how, tips and know-how, it is very difficult for an inexperienced person to obtain an appropriate value.

Therefore, the present invention was developed in view of the above-mentioned problems in the prior art. In the stage before the start of continuous production of optical elements, an optical element for which required accuracy can be easily secured by anyone in a short time is provided. An object of the present invention is to provide a molding method and apparatus that can derive and set various suitable molding conditions for processing.

[0006]

SUMMARY OF THE INVENTION According to the present invention, an optical material is carried into a heating furnace while being held by a conveying member to be heated and softened, and then a pair of molding surfaces corresponding to desired optical elements are provided. In the molding method of an optical element which is conveyed between molding dies and is pressure-molded by the pair of molding dies, a plurality of trial moldings are performed before the start of continuous production, and the variation in the medium thickness between the optical material and the molded optical element Is a method of automatically deriving appropriate various molding conditions from

Further, a measuring section for measuring the size of the inner wall of the optical material, a heating section for heating the optical material, a molding section for pressing the heated optical material, and a slow cooling section for the molded optical element. And a carrying section for loading and unloading the optical material and the optical element, a measuring section for measuring the size of the inner wall of the molded optical element, and receiving the data of the optical material and the optical element measured by each measuring section. The control unit automatically sets the temperature of the heating unit, the pressing force of the molding unit, and the pressing time of the molding unit.

[0008]

In the present invention, first, after measuring the medium thickness of the optical material to be supplied, it is heated and softened at the initial set temperature.
Next, the medium thickness of the molded optical element is measured by pressing it with the initial pressing force for the initial setting time. Then, the controller calculates the amount of change in the inside wall thickness in the forming process by comparing it with the thickness of the inside wall thickness before forming, and the heating temperature, pressing force, and pressure that are molding conditions are set so that the target amount of inside wall change can be achieved. By repeating the above operation several times while regularly changing the time and the like, an appropriate set value is automatically calculated and set.

[0009]

[Embodiment 1] This embodiment will be described with reference to FIGS.
FIG. 1 is a conceptual diagram showing an embodiment. FIG. 2 is a graph showing the relationship between the gob temperature and the amount of change in fillet in the apparatus shown in FIG. Here, the amount of change in the medium thickness represents the difference between the medium thickness of the optical material before molding and the medium thickness of the optical element after molding, and the greater the difference, the greater the amount of change in the medium thickness. The temperature range that can be varied in the actual molding process is between k1 and k2.

FIG. 3 is a graph showing the relationship between the press pressure and the amount of change in inner wall thickness in the apparatus shown in FIG. The range that can be varied in the actual molding process is between p1 and p2. FIG. 4 is a graph showing the relationship between the pressing time and the amount of change in fillet in the apparatus shown in FIG. The range that can be varied in the actual molding process is between t1 and t2. Figure 5
FIG. 2 is a schematic configuration diagram of a transport system and a process path in the apparatus shown in FIG.

FIG. 6 is a sectional view of the carrier. FIG. 7 is a perspective view of the tip of the carrier carrying arm. FIG. 8 is a flowchart. FIG. 9 is a flowchart of the condition setting change A of FIG.

As shown in FIG. 5, the preheating furnace 7a and the auxiliary annealing furnace 25a are arranged in parallel with each other.
Further, inside the auxiliary slow cooling furnace 25a, carrier caterpillars 26a and 26b are installed, in which carriers 29 are placed at equal intervals and are intermittently driven by a driving device (not shown). A press molding apparatus including an upper mold 9 and a lower mold 10 is installed between the outlet of the preheating furnace 7a and the inlet of the auxiliary annealing furnace 25a. The heater 7 and the slow cooling furnace 25 are provided between the press forming apparatus and the outlet of the preheating furnace 7a and the inlet of the auxiliary slow cooling furnace 25a, respectively.

Near the exit of the preheating furnace 7a and near the entrance of the auxiliary annealing furnace 25a, a carrier carrying arm for carrying the carrier 29 from the exit of the preheating furnace 7a through the heater 7 to the press forming apparatus. 27a and a carrier carrying arm 27b for carrying the carrier 29 from the press forming apparatus through the slow cooling furnace 25 to the inlet of the auxiliary slow cooling furnace 25a.

The carrier 29, as shown in FIG.
The planar shape is a donut shape, and is slightly (about 0.1 mm) larger than the outer diameter of the pressing optical element 5 near the lower part of the inner peripheral surface of the central through hole 30 into which the tip of the lower mold 10 is inserted. An optical element mounting step portion 31 having an inner diameter is provided, and a press lens mounting step portion 32 having an inner diameter larger than the outer diameter of the press lens 5c by about 1 mm is provided above the optical element mounting step portion 31. A flange 33 is provided on the outer periphery of the upper end of the carrier 29.

The carrier carrying arms 27a and 2
7b is connected at its proximal end to drive devices 28a and 28b each having a cylinder for driving an arm in a horizontal direction and a vertical direction, and a flange 33 of a carrier 29 is attached to a distal end thereof as shown in FIG. Two parallel pressing plates 34a, 34 whose central tip is cut so as to be sandwiched
b is attached by a screw 35.

In the step 1 of measuring the thickness of the supplied material, the displacement meter 6 is arranged so that the thickness of the center portion of the supplied optical element 5 can be measured, and the measured data can be input to the arithmetic processing unit 19. It is connected like this. In the heating step 2, the heater control device 8 is arranged so as to control the heater 7 by a signal from the arithmetic processing device 19 and heat the optical element 5a.

In the pressing step 3, the upper die 9 and the pressure cylinder 14 are arranged so that the distance between them does not change, and the lower die 10 is provided at the upper end of the plunger 14a of the pressure cylinder 14. Are arranged so as to be opposed to the lower mold 9 and have their axes aligned. The periphery of the upper mold 9 and the lower mold 10 is surrounded by a device (not shown) so as to maintain an N ₂ gas atmosphere. The heater control devices 15 and 16 receive the heaters 11 and 1 based on the signal from the arithmetic processing device 19.
The upper die 9 and the lower die 10 are each set to a predetermined temperature via 2.

The lower end of the lower mold 10 and the pressure cylinder 14
A pressure sensor 13 is attached between the tip of the plunger 14a and the lower end of the plunger 14a in a heat-insulated state so as not to be affected by heat from the lower mold 10. The measurement value of the pressure sensor 13 is input to the arithmetic processing unit 19 via the pressure sensor amplifier 17 and is controlled so that the pressure always becomes a set value. On the other hand, the pressurizing cylinder 14 is connected to the arithmetic processing unit 19 via the pressure adjusting unit 20.
The pressure can be changed steplessly from low pressure to high pressure based on the signal from. Further, the lower mold 10 is held together with the pressure cylinder 14 and the pressure sensor 13 for driving the lower mold 10 by a vertical mechanism (not shown), and does not buffer the upper mold 9 even if the blanker 14a of the pressure cylinder 14 moves upward. It is arranged as follows.

In the step 4 of measuring the inside wall thickness after molding, the displacement meter 1
8 is arranged so that the thickness of the center of the optical element 5c after molding can be measured, and the measured data is connected to the arithmetic processing unit 19 so that it can be input.

The arithmetic processing unit 19 includes a display 21, a keyboard 22 for inputting data, and a floppy disk drive for storing data (hereinafter referred to as FDD).
23 are provided. In addition, the preset temperature of the heater 7, the upper heater 11, and the lower heater 12 and the preset pressure of the pressure adjusting device 20 are set so that appropriate molding processing can be performed in advance depending on the outer diameter dimension, wall thickness and material of the supply optical element. And the data of the pressing time are set as initial values. In addition, data representing the relationships shown in FIGS. 2, 3, and 4 described above is input.

A molding method using the optical element molding apparatus having the above structure will be described below. First, the operator inputs the external dimensions, thickness and material of the supply optical element from the keyboard 22. Based on the input data, the arithmetic processing unit 19 determines the temperatures of the heater 7, the upper heater 11, and the lower heater 12 and the pressure and pressing time of the pressure adjusting device 20. Based on the data, the arithmetic processing unit 19 controls the heater control units 8, 15, 16 and the pressure adjusting unit 20 so that the determined values become constant.

In the molding apparatus thus set up, first, the optical elements 5 are placed on the optical element placement steps 31 of the carriers 29 arranged on the caterpillar 26a at equal intervals. Next, the optical element 5 is conveyed by the caterpillar 26a in the direction of the arrow a and is transferred to the point of the medium thickness measuring step 1 of the feed material. Therefore, the medium thickness of the optical element 5 supplied by the displacement meter 6 is measured, and the measured data is taken into the arithmetic processing unit 19.

The optical element 5 whose medium thickness has been measured is further conveyed by the caterpillar 26a and passes through the preheating furnace 7a. Carrier 29 reaching the exit of the preheating furnace 7a
The transfer arm 27a horizontally moves from the initial position in FIG. 5 to hold the flange 33 of the carrier 29 by the pressing plates 34a and 34b at the tips thereof. Next, the carrier 29 is lifted by the driving device 28a, then transferred to the position of the heater 7 and allowed to stay in the heated heater 7 for a certain period of time, whereby the optical element 5 is softened.
Here, the residence time in the heater 7 is preset so that the viscosity of the optical element 5 is about 10 ⁶ poise.

The heat-softened optical element (gob) 5a is
Further, by moving the transfer arm 27a horizontally,
It is transferred between the upper mold 9 and the lower mold 10. Then, the pressure cylinder 14 is operated. The plunger 14a of the pressurizing cylinder 14 presses the gob 5a at a set pressure by the pressure adjusting device 20, and the transfer arm 27a retracts. At the same time, the arithmetic processing unit 19 operates the timer. After the lapse of the set pressing time, the pressure cylinder 14 is lowered to release the molded optical element 5b from the mold, and the molding process is completed.

On the other hand, in synchronization with this, the transfer arm 27b moves from the initial position of FIG. 5, holds the carrier 29 on which the optical element 5b is placed, passes through the slow cooling furnace 25, and the carrier 29 is placed on the caterpillar 26b. Transfer and place. The optical element 5b is gradually cooled while passing through the slow cooling furnace 25, and after being transferred onto the caterpillar 26b, is further cooled while being transported in the auxiliary slow cooling furnace 25a by intermittent movement of the caterpillar 26b. It is transferred to the position of the displacement gauge 18 at the exit of the device under the condition of almost room temperature.

Optical element 5 molded by displacement meter 18
The medium wall thickness of c is measured, and the measurement data is taken into the arithmetic processing unit 19. The arithmetic processing unit 19 calculates the medium thickness data of the optical element 5c after molding and the medium thickness data of the optical element 5 before molding to calculate the variation amount of the medium thickness in the molding process. In order to obtain the target amount of change in meat by referring to the data of the relationship between the gob temperature and the amount of change in meat shown in FIG. The set temperature of the heater 7 is changed.

By repeating the above operation several times, depending on the optical element, the target amount of change in the medium thickness is reached, at which point the above operation ends. The data of the heater control devices 8, 15, 16 and the pressure adjusting device 20 at that time are recorded in the FDD 23. After that, at the time of continuous production of the same optical element, it is possible to read the above data from the FDD 23 and perform molding immediately. This operation flow is shown in FIG. Here, the content of the condition setting change A of FIG. 8 is shown in FIG.

According to this embodiment, since the ratio of the amount of change in the medium thickness to the gob temperature is large, it is possible to correct even if the thickness error is relatively large.

[0029]

[Second Embodiment] FIG. 10 is a flow chart showing the contents of the condition setting change A of FIG. 8 according to the present embodiment. In addition, in the present embodiment, description will be made with reference to FIGS. 1, 3 and 8.
The present embodiment has the same configuration and molding process as those of the first embodiment, and the description thereof will be omitted.

The arithmetic processing unit 19 includes the optical element 5 after molding.
The medium thickness data of c and the medium thickness data of the optical element 5c before molding are calculated to calculate the variation amount of the medium thickness in the molding process. In order to obtain the target amount of change in the inside meat by comparing the amount of change in the inside meat with the target amount of change in the inside meat and referring to the data of the relationship between the press pressure and the amount of change in the inside meat shown in FIG. Then, the set pressure of the pressure adjusting device 20 is changed.

By repeating the above-mentioned operation, the above-mentioned operation is terminated when the target amount of change in the inner wall is reached, and the data of the heater control devices 8, 15, 16 and the pressure adjusting device 20 at that time are stored in the FDD 23. Record. After that, when the same optical element is continuously manufactured, the above data can be read from the FDD 23 and the molding can be performed immediately, as in the first embodiment. This operation flow is shown in FIG.
Here, the content of the condition setting change A of FIG. 8 is shown in FIG.

According to this embodiment, since the ratio of the change amount of the medium thickness to the pressing pressure is small, it is effective for the correction when the thickness error is relatively small.

[0033]

[Third Embodiment] FIG. 11 is a flow chart showing the contents of the condition setting change A of FIG. 8 according to the present embodiment. In addition, in the present embodiment, description will be given with reference to FIGS. 1, 4 and 8.
The present embodiment has the same configuration and molding process as those of the first embodiment, and the description thereof will be omitted.

The arithmetic processing unit 19 includes the optical element 5 after molding.
The medium thickness data of c and the medium thickness data of the optical element 5 before molding are calculated to calculate the variation amount of the medium thickness in the molding process. In order to obtain the target amount of change in the inside meat by comparing and calculating the amount of change in the inside meat with the target amount of change in the inside meat and referring to the data of the relationship between the pressing time and the amount of change in the inside meat shown in FIG. Change the set value of press time.

By repeating the above operation, the above operation is terminated when the target amount of change in the inner wall is reached, and the data of the heater control devices 8, 15, 16 and the pressure adjusting device 20 at that time are stored in the FDD 23. Record. After that, when the same optical element is continuously manufactured, the above data can be read from the FDD 23 and the molding can be performed immediately, as in the first embodiment. This operation flow is shown in FIG.
Here, the content of the condition setting change A of FIG. 8 is shown in FIG.

According to the present embodiment, the cycle time of the molding time can be shortened by correcting the pressing time.

[0037]

[Fourth Embodiment] FIG. 12 is a flow chart showing the contents of the condition setting change A of FIG. 8 according to the present embodiment. In addition, in the present embodiment, description will be given with reference to FIGS. 1, 2, 3, 4, and 8. The present embodiment has the same configuration and molding process as those of the first embodiment, and the description thereof will be omitted.

The arithmetic processing unit 19 includes the optical element 5 after molding.
By referring to the medium thickness data of c and the medium thickness data of the optical element 5 before molding, the change amount of the medium thickness in the molding process is calculated. The change amount of the inside meat and the target change amount of the inside meat are compared and calculated. First, referring to the data of the relationship between the gop temperature and the inside meat change amount shown in FIG. In order to do so, the set temperature of the heater 7 is changed.

Next, the same molding is carried out, and the set pressure of the pressure adjusting device 20 is changed in order to obtain the target amount of change in the inside wall by referring to the data on the relationship between the press pressure and the amount of change in the inside wall shown in FIG. Let The same molding is performed again, and the set value of the press time is changed in order to obtain the target amount of change in the inner wall by referring to the data on the relationship between the pressing time and the amount of change in the inner wall shown in FIG.

By repeating the above operation, the above operation is stopped when the target amount of change in the inside meat is reached, and the data of the heater control devices 8, 15, 16 and the pressure adjusting device 20 at that time are stored in the FDD 23. Record. After that, when the same optical element is continuously manufactured, the above data can be read from the FDD 23 and the molding can be performed immediately, as in the first embodiment. This operation flow is shown in FIG.
Here, the contents of the condition setting change A of FIG. 8 are shown in FIG.

According to this embodiment, it is possible to set the molding conditions in a well-balanced manner, and to set the molding conditions with a small variation in the molding accuracy for each molding in a shorter time.

[0042]

As described above, according to the method and apparatus for molding an optical element of the present invention, it is possible to obtain an appropriate value of the condition for processing the optical element with the required accuracy secured in a short time. Anyone can easily process the optical element with the required accuracy. In addition, the appropriate value is automatically set. Further, it has various effects such as preventing malfunction of the device and accident due to data input error.

[Brief description of drawings]

FIG. 1 is a conceptual diagram showing a first embodiment.

2 is a graph showing Example 1. FIG.

FIG. 3 is a graph showing Example 1.

FIG. 4 is a graph showing Example 1.

FIG. 5 is a schematic configuration diagram showing a first embodiment.

FIG. 6 is a cross-sectional view showing the first embodiment.

FIG. 7 is a perspective view of a distal end portion of the first embodiment.

FIG. 8 is a flowchart showing the first embodiment.

FIG. 9 is a flowchart showing the first embodiment.

FIG. 10 is a flowchart showing a second embodiment.

FIG. 11 is a flowchart showing a third embodiment.

FIG. 12 is a flowchart showing a fourth embodiment.

[Explanation of symbols]

 1 Supply Material Medium Thickness Measuring Step 2 Heating Step 3 Pressing Step 4 Medium Pressure After Measuring Step 5,5a, 5b, 5c Optical Element 6,18 Displacement Gauge 7 Heater 8 Heater Control Device 9 Upper Mold 10 Lower Mold 11 Upper Mold Heater 12 Lower heater 13 Pressure sensor 14 Pressurizing cylinder 15 and 16 Heater control device 17 Pressure sensor amplifier 19 Arithmetic processing device 20 Pressure adjusting device 25 Slow cooling furnace

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 carried between a pair of molding dies having a molding surface corresponding to a desired optical element, In the optical element molding method of pressing with a pair of molding dies, a plurality of trial moldings are performed before the start of continuous production, and appropriate various molding conditions are automatically determined from the amount of change in the thickness of the optical material and the molded optical element. A method for molding an optical element, which is characterized by: 2. A measuring section for measuring the size of the inner wall of the optical material, a heating section for heating the optical material, a molding section for pressing the heated optical material, and a slow cooling section for the molded optical element. And a carrying section for loading and unloading the optical material and the optical element, a measuring section for measuring the size of the inner wall of the molded optical element, and receiving the data of the optical material and the optical element measured by each measuring section. And a control unit for automatically setting the temperature of the heating unit, the pressing force of the molding unit, and the pressing time of the molding unit.