JP2000264652A - Apparatus for molding optical element and molding - Google Patents

Abstract

PROBLEM TO BE SOLVED: To mold an optical element good in wall thickness accuracy and shape accuracy. SOLUTION: This apparatus for molding an optical element is equipped with a mold driving means 22 for driving a movable mold 5 through a pressing shaft 12 so as to press the heated and softened optical element interposed between a fixed mold 2 and the movable mold 5, a stopper 29 capable of stopping the movable mold 5 driven with the mold driving means 22 at a position reaching a wall thickness in a prescribed ratio based on the final wall thickness of the optical element and arranged at a position adjacent to the movable mold 5, a position detecting means 38 for measuring the stopping position of the movable mold 5 stopped with the stopper 29, a stopper driving means 34 capable of changing the position of the stopper 29 from a position for stopping the movable mold 5 to a position for making the movable mold 5 movable and regulating the stopping position of the movable mold 5 from an output of the position detecting means 38 and a controller 36 for controlling the stopper driving means 34 and the mold driving means 22 in the apparatus for molding the optical element provided with the fixed mold 2 having a heater 1A arranged therein and the movable mold 5 opposite to the fixed mold 2 and having a heater 1B installed therein.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a molding apparatus and a molding method for an optical element, and more particularly to a means for ensuring the molding accuracy of an optical element.

[0002]

2. Description of the Related Art Japanese Patent Laid-Open Publication No.
The technology (prior art 1) described in Japanese Patent Publication No. 172850 is disclosed. In the prior art 1, a control device of a glass forming machine that forms a glass material in a heated and softened state into an arbitrary shape by rotating a drive shaft by a servomotor and pressing a movable mold against a fixed mold is used. A display and operation unit for setting the movement position and speed, pressing force, temperature, etc., and a program for storing a servo operation program and a molding operation program for sequentially generating temperature command values using the setting data of the display and operation unit A storage unit, a temperature control unit that heats and cools the mold, a servo control unit that controls the operation of the servo motor,
A pressing force detecting unit that detects a pressing force applied to a mold, a position detecting unit that detects a position of the mold, a temperature detecting unit that detects a heating temperature of the mold, and a display operation unit according to a program in the program storage unit. And a program execution unit for sequentially generating the glass forming operation set in the step (1).

[0003] In response to a command from the program execution unit, the temperature control unit heats the mold and controls the servo motor by the servo control unit. The pressing force, the pressing speed, and the movement applied to the mold from the program execution unit. When the pressing force control is commanded together with the pressing command data such as the pressing limit, the servo control unit calculates the difference between the pressing force command value and the feedback value from the pressing force detecting unit, and moves the mold based on this value. By calculating the speed and driving the mold with a servomotor under the conditions of the pressing speed and the movement limit command value, the pressing force applied to the glass material in the closed loop type pressing force control mode is reduced to the specified pressing force. Hold and enter the pressing force control mode, after a specified time has elapsed, or after detecting that the specified movement limit has been reached, or by a signal from the outside, It was released by switching to position control mode of closed loop type by the feedback signal from the position detection unit, so as to implement the operation specified in the molding pattern of the display operation unit.

[0004] As a "method and apparatus for molding an optical element", there is a technique (prior art 2) disclosed in Japanese Patent No. 2520522 (registered May 17, 1996). In the optical element molding apparatus of the prior art 2, an optical material heated to a predetermined temperature is carried in between a mold composed of an upper mold and a lower mold, and after press molding, the optical material is thicker than the optical element. In the state, the pressing operation of the mold is stopped by the stopping means, and as the optical material cools and solidifies to a predetermined temperature, the stopping means is released and the optical material is added again in conjunction with the contraction of the optical material. In the molding apparatus for pressing, a sensor for measuring the displacement of the mold, a stop device for stopping the pressing operation of the mold, a means for driving the stop device, and a stop device after a predetermined period of time by sensing an input from the sensor. Delay means for driving.

[0005] In the molding method using the molding apparatus, after detecting an input from a sensor for measuring the displacement of the mold, the delay time until the mold presses the optical material again is determined by the accuracy of the thickness of the optical element. The time is shorter than the time for satisfying the standard value, and is faster than the time for satisfying the standard value of the shape accuracy of the optical element.

[0006]

However, the above prior art has the following problems. That is, in the prior art 1, in the control method of the servo motor of the glass forming machine, when load control (pressing force control) is performed on the optical material that has been softened in advance by heating, the positioning accuracy of the movable mold at the time of forming is reduced by the thickness of the optical element. It greatly affects thickness and shape accuracy. However, in the glass forming machine of the prior art 1, since the output signal from the position detector of the servomotor is fed back, in addition to the error of the position control system of the servomotor, the thermal expansion of the ball screw and other components is caused. Variations in position accuracy are large due to errors. Furthermore, when the press shaft (drive shaft) is positioned at a high speed by a servomotor, the pressing force (pressing force) fluctuates the moment the optical material is pressed due to the transient response during positioning, and undulates on the surface of the molded optical element. Occurs. In addition, when an attempt is made to perform molding by load control (pressing force control), the pressing force changes in a short time because the optical material that has been softened by heating in advance is an elastic body, and the accumulated pulse corresponding to the output signal from the pressing force detecting unit is generated. Without converging, intermittent variations in pressing force (pressing force) occur in the initial stage of molding,
Undulation occurs on the surface of the molded optical element.

In the prior art 2, since the stopping means is provided below the long holding shaft (spindle) in the optical element molding apparatus, the stop position of the lower die is the thermal expansion of the holding shaft (spindle). And the thickness accuracy of the molded optical element could not be ensured. In addition, since the component members of the apparatus are large and the driving means for driving are also large, the load control resolution is large, and fine load control cannot be performed, so residual stress is generated inside the molded optical element, and the shape is reduced. It was difficult to ensure accuracy.

The present invention has been made in view of the above-mentioned conventional problems, and an object of the invention according to claim 1 or 2 is to provide an optical element capable of molding an optical element having good wall thickness accuracy and shape accuracy. It is to provide a molding device. It is an object of the invention according to claims 3, 4 or 5 to provide a method for molding an optical element using the molding apparatus.

[0009]

According to a first aspect of the present invention, there is provided an optical element molding apparatus having a fixed type provided with a heater and a movable type provided with a heater opposed to the fixed type. Mold driving means for driving the movable mold via a press shaft so as to press the heat-softened optical material interposed between the fixed mold and the movable mold, and the movable mold driven by the mold driving means To stop at a position where the thickness of the optical element reaches a predetermined thickness with respect to the final thickness of the optical element, position detecting means for measuring the stop position of the movable mold stopped by the stopper, and stopping the movable mold A stopper driving means capable of changing a position of the stopper between a position to be moved and a position to be movable and adjusting a stop position of the movable die from an output of the position detecting means; And a controller for controlling the.

According to a third or fourth aspect of the present invention, there is provided a method for forming an optical element, comprising the steps of: disposing an optical material heated and softened to a temperature equal to or higher than the glass transition point between a fixed mold and a movable mold; Driving the means to press the optical material with the movable mold and stopping the movable mold at a position where the thickness of the optical element reaches a predetermined ratio with respect to the final thickness of the optical element; and the movable mold is stopped. A step of measuring the position by the position detecting means; and obtaining the correction amount of the stop position from the stop position measured by the position detecting means and the stop command position of the movable type which is a condition for obtaining the final thickness of the optical element. And a step of driving the mold driving means after the temperature of the optical material approaches the glass transition temperature at the stop position of the movable mold to press-mold the optical material to the final thickness of the optical element.

In the optical element molding apparatus according to the first or second aspect of the invention, the final thickness of the optical element is reduced while pressing the heat-softened optical material interposed between the fixed mold and the movable mold by the mold driving means. On the other hand, the movable die is stopped by the stopper at a position where the thickness reaches a predetermined ratio, the stop position of the movable die is measured by the position detecting means, and the stop position measured by the position detecting means by the controller controlling the stopper driving means. And obtaining a correction amount of the stop position from a movable stop command position that is a condition for obtaining a final thickness of the optical element, correcting the stopper position by stopper driving means to continue pressing the optical material, and After the temperature of the material approaches the glass transition temperature, the stopper is released and the mold driving means is driven by a command of a controller for controlling the mold driving means, so that the optical material is moved to the final optical element. Up to a thickness to press molding.

In the optical element molding apparatus according to the second aspect of the present invention, in addition to the above operation, the mold driving means is a servomotor, and the controller controls the servomotor with a predetermined torque. In the process of press-molding the optical material to the final thickness of the optical element, the servomotor is controlled with a predetermined torque so that the pressing force for pressing the optical material has a value corresponding to the molding process.

According to a third aspect of the present invention, there is provided a method for forming an optical element, wherein an optical material heated and softened to a temperature equal to or higher than a glass transition point is disposed between a fixed mold and a movable mold, and the mold driving means is provided. The movable mold is driven to press the optical material with the movable mold, and the movable mold is stopped at a position where the thickness of the optical element reaches a predetermined thickness with respect to the final thickness of the optical element, and the position where the movable mold is stopped is measured by the position detecting means. Then, a correction amount of the stop position is obtained from the stop position measured by the position detection means and the movable stop command position that is a condition for obtaining the final thickness of the optical element, and the temperature of the optical material at the movable stop position is obtained. After the temperature approaches the glass transition temperature, the mold driving means is driven to press-mold the optical material to the final thickness of the optical element.

According to a fourth aspect of the present invention, in addition to the above operation, the mold driving means is a servomotor, and the servomotor is controlled at a predetermined torque by a controller for controlling the mold driving means. In the process of pressing and molding the optical material to the final thickness of the optical element, the servo motor is controlled with a predetermined torque so that the pressing force for pressing the optical material has a value corresponding to the molding process. Press molding while pressing.

According to a fifth aspect of the present invention, in addition to the above operation, when the correction amount of the stop position is out of the allowable error range of the stop command position, the position of the movable stop position is corrected. The position of the stopper is changed so that the correction amount of the movable stop position is within the allowable error range of the stop command position.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a table showing a relationship between a pressing load as a pressing force and an elapsed time according to an embodiment of the present invention. In the present invention, in FIG. 1, an optical material heated and softened to a temperature equal to or higher than the glass transition point is inserted between a fixed mold and a movable mold, and a stopper mechanism whose position is set in advance is driven. , The pressing shaft is driven with a predetermined torque or a predetermined air pressure, and the optical material is pressed with a press load F ₁ until the movable die is stopped by the stopper at an elapsed time T ₁ until a constant thickness is obtained. _The stopped pressing position is held until ₂ . Then, after the optical material is cooled to near the glass transition temperature, the stopper is released, and the press shaft is adjusted to the predetermined torque or higher torque or the predetermined air pressure or more in accordance with the contraction speed of the optical material. It is set to a high air pressure, further constant pressing load F until the elapsed time from elapsed time T ₃ T ₄
Press with ₂ .

Furthermore, after reducing the press load stepwise, retract the press axis by the elapsed time T _5, thereby releasing the mobile. The set position of the stopper mechanism is detected by position detecting means installed in the housing, and the set position is fed back. If a position shift occurs with respect to the set position, the set position is corrected by the controller, and the fixed position is always maintained. Thickness control is possible. Hereinafter, specific embodiments will be described.

(Embodiment 1) FIGS. 2 to 5 show Embodiment 1, FIG. 2 is a configuration diagram of a molding device for an optical element, FIG. 3 is a schematic configuration diagram of a molding device in an initial state before molding, FIG. 4 is a schematic configuration diagram of the molding device during molding by the press shaft contacting the stopper, and FIG. 5 is a schematic configuration diagram of the molding device during molding after the stopper is retracted.

In FIG. 2, a fixed mold 2 in which a heater 1A is embedded is attached to the center of a ceiling surface of a housing 4 forming a molding chamber by a mold holder 3A. Housing 4
Is attached to an upper base plate 14, and the upper base plate 14 is connected to a lower base plate 16 via a support 15. Also,
A movable mold 5 having a heater 1B embedded therein, opposite to the fixed mold 2.
Is attached to the upper surface of the tilt adjustment unit 6 which is a tilt adjustment means by a mold holder 3B. The tilt adjustment unit 6 can adjust the position so as to be tiltable along the spherical surface on the lower surface side, and can fix the position. The tilt adjustment unit 6 is attached to a shift adjustment unit 7 that is a shift adjustment unit. The shift adjustment unit 7 has a spherical upper surface to support the tilt adjustment unit 6, and the tilt adjustment unit 6 can be adjusted in position and fixed in position on a horizontal surface. The shift adjustment unit 7 is attached to the movable base 8. Both ends of the movable base 8 are attached to a slide guide 9 which is a high-precision guide attached to the inner wall of the housing 4, and is configured to be able to move up and down inside the housing 4.

A holder 10 is attached to a lower portion of the movable base 8, and a floating joint 11 having a spherical tip attached to an upper end of a press shaft 12 is rotatably connected to the holder 10. . At the middle of the press shaft 12, a stopper flange 13 is fixed.
A cam follower 17 is rotatably attached to the right end of the cam follower. The press shaft 12 is attached to a press shaft support block 18. The press shaft support block 18 is attached to a slide guide 26, and the slide guide 26 is attached to a side surface of a scale 27 as a support member so as to be vertically movable. Therefore, the press shaft 12 can move up and down while being guided by the slide guide 26.

A ball screw 20 is screwed into the press shaft support block 18, and both upper and lower ends of the ball screw 20 are supported by support units 19 as bearing members. Both support units 19 are attached to a scale member 28, which is a support member. Each of the scales 27 and 28 is attached to the upper surface of the drive base plate 23 supported on the lower base 16 by the plurality of columns 24. A press servomotor 22 as a mold driving means is connected to a lower end of the ball screw 20 via a coupling 21. Servo motor for press 22
Is mounted on the lower surface of the drive base plate 23, and drives the ball screw 20 to drive the press shaft 12 in the vertical direction. A press SM driver 25 for controlling the torque of the press servo motor 22 is connected to the press servo motor 22.
5 is connected to the controller 36.

A stopper 29 is provided so as to slide on the lower surface of the upper base 14, and a tapered surface 29a of the stopper 29 engages with the cam follower 17 attached to the press shaft 12 via the stopper flange 13, thereby forming a taper. The vertical stop position of the press shaft 12 can be changed by the contact position between the surface 29a and the cam follower 17. The stopper 29 is configured to be slidable in the left-right direction along the slide guide 30.
Is screwed. Both ends of the ball screw 31 are respectively supported by support units 32 which are bearing members. Slide guide 30 and both support units 3
2 are attached to the stopper base plate 37, respectively, and the stopper base plate 37 is attached to the lower surface of the upper base plate 14. A stopper servomotor 34 as stopper driving means is connected to the right end of the ball screw 31 via a coupling 33.

The stopper servomotor 34 is attached to the side surface of the stopper base plate 37, and drives the stopper 29 in the left-right direction by rotating the ball screw 31. Therefore, the amount of movement of the stopper 29 changes according to the driving amount (rotation amount) of the stopper servomotor 34, and the contact position between the tapered surface 29 a of the stopper 29 and the cam follower 17 changes according to the amount of movement, and The position of the direction changes. The stopper SM driver 35 is connected to the stopper servo motor 34, and the stopper SM driver 35 is connected to the controller 36. A displacement sensor 38 as a position detecting means is vertically provided from the ceiling surface of the housing 4, and the tip thereof is in contact with the upper surface of the tilt adjustment unit 6, and the base end is connected to the controller 36. Thus, the vertical position of the mobile mold 5 is measured, and the data is transmitted to the controller 36.

Next, a method for molding an optical element using the molding apparatus having the above configuration will be described. As shown in FIG.
The fixed mold 2 and the movable mold 5 each have a heater 1 embedded therein.
A, heater 1B heats to a temperature below the glass transition point. The movable die 5 is adjusted coaxially with the fixed die 2 by the tilt adjustment unit 6 and the shift adjustment unit 7, and is positioned at the molding standby position by the press servo motor 22. A heated and softened optical material 39 is carried in between the fixed mold 2 and the movable mold 5 by a transport device (not shown). The stopper 29 drives the stopper servo motor 34 so that the optical material 39 sandwiched between the molding surfaces of the fixed mold 2 and the movable mold 5 has a thickness of 105 to 110% of the final thickness. It is positioned at such a setting position. In the case of 110% to 115%, a large torque is required when finally pressed.

As shown in FIG. 4, the press servomotor 22 is driven to rotate by the torque set by the press SM driver 25, and the press shaft 12 is raised along the slide guide 26. It is raised along the slide guide 9. When the cam follower 17 attached to the press shaft 12 via the stopper flange 13 contacts the stopper 29 and the press shaft 12 stops,
The movable mold 5 presses the optical material 39 and is formed by the fixed mold 2 and the movable mold 5 at a position where the distance between the movable mold 5 and the fixed mold 2 is constant, that is, at a temperature where the optical material 39 is higher than the glass transition point. The optical material 39 is stopped at a position where the optical material 39 maintains a positional relationship with a constant ratio with respect to the final thickness. The stop position of the movable mold 5 is detected by a displacement sensor 38, and a detection signal is output to a controller 36. The controller 36 determines the command position, that is, the desired stop command of the movable mold that is a condition for obtaining the final thickness of the optical element. An error from the position is calculated, and if the error exceeds an allowable range, a signal corresponding to the corrected position is output to the stopper SM driver 35, and the stopper servo motor 34 is driven again to position the stopper 29. Do it again.

As shown in FIG. 5, when the temperature of the optical material 39 decreases and approaches the glass transition point temperature, the servo motor 34 for stopper is driven, the ball screw 31 is rotated in the reverse direction, and along the slide guide 30. The stopper 29 is retracted. The press shaft 12 can be raised by the torque control (the set torque) of the press servomotor 22 by the retraction of the stopper 29, but the optical material 39 is sandwiched between the movable mold 5 and the fixed mold 2. By having
Even if the temperature of the optical material 39 decreases and contracts, the optical material 39 is always pressed with a constant torque. Thereafter, the press load is reduced by reducing the torque value of the press servo motor 22 according to the elapsed time, and the internal stress of the optical material 39 is relaxed. After that, the press servomotor 22 is driven to rotate in the reverse direction, and the press shaft 12 is lowered, whereby the movable die 5 is retracted to the molding standby position. Thereafter, the formed optical element is taken out by a transport device (not shown).

As described above, the pressing of the optical material 39 is performed by torque control, and the positioning of the movable mold 5 before the final thickness of the optical element is performed by the stopper 29, thereby obtaining an optical element with good shape accuracy. Can be. The stopper 2 is located at a position close to the position of the movable mold 5 for making the optical element the final thickness.
The stop position of the movable mold 5 is detected, and when the stop position has a deviation as a correction amount, the position of the stopper 29 is corrected. That is, the stopper servomotor 3
By controlling the position of the stopper 29 by 4 and changing the contact position between the tapered surface 29a of the stopper 29 and the cam follower 17, an optical element with good wall thickness accuracy can be obtained.

According to the present embodiment, the press shaft is driven with a predetermined torque and the pressing operation of the movable mold is stopped via the stopper, so that the distance between the fixed mold and the movable mold is reduced by the motor drive system. Press molding can be performed without being affected by the positioning error, transient response, and the like of the device. Also,
By disposing the movable type guide on the side of the housing and the movable type base, it is possible to dispose the stopper at a position close to the movable type, and errors due to thermal expansion of mechanical elements such as ball screws and press shafts can be achieved. Can also be kept very small. Further, by releasing the stopper and keeping the stopper pressed in accordance with the contraction of the optical material, deterioration of the shape accuracy due to sink can be prevented. Furthermore, by controlling the press load step by step with high accuracy, it is possible to prevent the generation of residual stress inside the optical element, and to obtain an optical element with good shape accuracy. In addition, by performing feedback control of the stop position of the stopper by the position detection means,
Even if a temporal error or a sudden error occurs, the thickness control is not continuously affected.

In the present embodiment, when the press servomotor 22 is driven to rotate, the torque is set at a constant value.
In the case where the stopper 29 retreats and the press shaft 12 rises again after being stopped by the step 9, the torque value is increased corresponding to the decrease in the temperature of the optical material, or the amount of deformation of the optical material is reduced. The servo motor driver 25 can control so that the torque value is set low in response to the decrease, and the torque value can be set so as to be increased or decreased stepwise.

(Embodiment 2) FIGS. 6 to 9 show Embodiment 2, FIG. 6 is a configuration diagram of an optical element molding device, FIG. 7 is a schematic configuration diagram of an initial molding device before molding, FIG. 8 is a schematic configuration diagram of a molding device during molding while the press shaft is in contact with the stopper, and FIG. 9 is a schematic configuration diagram of the molding device during molding after the stopper is retracted. The optical element molding apparatus of the present embodiment is different from the first embodiment only in the drive actuator of the press shaft and members related thereto, and the other parts are the same as in the first embodiment. Therefore, only different parts will be described. , The same members are denoted by the same reference numerals, and description thereof will be omitted.

In FIG. 6, an air cylinder 51 as a mold driving means is mounted on the drive base plate 23.
The cylinder rod 51a is connected to a lower end of the press shaft 12 via a floating joint 52.
An electromagnetic valve 53 is connected to the air cylinder 51, and an electropneumatic proportional valve 54 is connected to the electromagnetic valve 53, respectively.
The electropneumatic proportional valve 54 is connected to a pneumatic pressure source 55 by piping. The electromagnetic valve 53 and the electropneumatic proportional valve 54 are electrically connected to the controller 36, respectively. The electropneumatic proportional valve 54 can control the air pressure of the air sent to the air cylinder 51 in accordance with a command from the controller 36. Other configurations are the same as those of the first embodiment.

Next, a method for molding an optical element using the molding apparatus having the above configuration will be described. As shown in FIG.
The fixed mold 2 and the movable mold 5 each have a heater 1 embedded therein.
A, heater 1B heats to a temperature below the glass transition point. The movable die 5 is adjusted coaxially with the fixed die 2 by the tilt adjustment unit 6 and the shift adjustment unit 7, and is positioned at the molding standby position by the air cylinder 51. A heated and softened optical material 39 is carried in between the fixed mold 2 and the movable mold 5 by a transport device (not shown). As in the first embodiment, the stopper 29 is driven by the stopper servomotor 34 so that
The optical material 39 sandwiched between the molding surfaces of the and the movable mold 5 is positioned at a set position such that the thickness is 105 to 110% of the final thickness. In addition, 110-115%
In the case of (1), a large air pressure is required for the final pressing.

As shown in FIG. 8, the air pressure is set by the electropneumatic proportional valve 54, and the solenoid valve 53 is operated to set the air cylinder 5
1 is driven by sending air to the movable die 5 by raising the press shaft 12 along the slide guide 26.
Is raised along the slide guide 9. Press shaft 12
When the cam follower 17 attached via the stopper flange 13 contacts the stopper 29 and the press shaft 12 stops, the movable mold 5 presses the optical material 39 and the distance between the movable mold 5 and the fixed mold 2 is reduced. At a certain position, that is, in a state where the optical material 39 is at a temperature higher than the glass transition point, the optical material 39 formed by the fixed mold 2 and the movable mold 5 maintains a positional relationship with a constant ratio to the final thickness. Stop at the position. The stop position of the movable mold 5 is detected by a displacement sensor 38, and this detection signal is output to a controller 36, and the controller 36 determines the command position, that is, the desired stop command of the movable mold which is a condition for obtaining the final thickness of the optical element. An error from the position is calculated, and if the error exceeds an allowable range, a signal corresponding to the corrected position is output to the stopper SM driver 35, and the stopper servo motor 34 is driven again to position the stopper 29. Do it again.

As shown in FIG. 9, when the temperature of the optical material 39 decreases and approaches the glass transition temperature, the stopper servomotor 34 is driven, the ball screw 31 is rotated in the reverse direction, and along the slide guide 30. The stopper 29 is retracted. When the stopper 29 is retracted, the press shaft 12 controls the air pressure of the air cylinder 51 (the electropneumatic proportional valve 54).
The air pressure can be increased by the air pressure set in step (1), but the optical material 39 is sandwiched between the movable mold 5 and the fixed mold 2 so that the optical material 39 is always kept constant even if the temperature of the optical material 39 decreases and contracts. Continue pressing with load. Thereafter, the press load is reduced by reducing the air pressure by the electropneumatic proportional valve 54 according to the elapsed time, and the internal stress of the optical material 39 is reduced. After that, the solenoid valve 53 is switched so that the air cylinder 5
The movable die 5 is retracted to the molding standby position by driving the drive shaft 1 and lowering the press shaft 12. Thereafter, the formed optical element is taken out by a transport device (not shown).

According to the present embodiment, in addition to the same effects as those of the first embodiment, since the air cylinder as the driving means is coaxial with the press shaft, no moment is applied to the driving portion to receive a press load. In addition, the device configuration can be simplified.

The technical idea of the following configuration is derived from the specific embodiment described above. (Supplementary note) (1) A fixed type having a heater embedded therein, a movable type disposed opposite to the fixed type and having a heater embedded therein, and heat-softened between the fixed type and the movable type. An optical element molding device having means for supplying an optical material,
A housing in which the fixed mold is disposed, a movable mold part including the movable mold, the movable shift adjustment means and the movable tilt adjustment means, and a movable mold part disposed in the housing. A high-precision guide for supporting the side surface so as to be movable up and down, position detecting means disposed in the housing for measuring a distance between the fixed die and the movable die, and a press shaft having the movable die portion supported at an upper end thereof A stopper disposed near the lower part of the movable mold part and capable of stopping the press shaft at a predetermined position, stopper driving means for driving the stopper, and mold driving means for driving the press shaft up and down; And a controller capable of controlling all the driving means and correcting the stop position of the stopper from the output of the position detecting means.

According to the appendix (1), the stopper is disposed at a position close to the movable mold, the thickness accuracy of the optical element is secured by using the stopper position correcting means, and after the stopper is released, the step is performed. It is possible to provide an optical element molding apparatus that obtains an optical element with good shape accuracy by adjusting the pressing force in a targeted manner.

(2) A first step in which the optical material is heated and softened to a temperature equal to or higher than the glass transition point and supplied between the fixed mold and the movable mold, and a press shaft is driven while driving a stopper to control torque or air pressure. By driving, the movable mold portion including the movable mold, the shift adjuster of the movable mold and the tilt adjuster of the movable mold is raised to a position where the stopper engages and the press shaft stops, and a position detecting means is provided. A second step of measuring the stop position and pressing the optical material, and after waiting until the temperature of the optical material falls to the glass transition point, release the stopper, follow the sink of the optical material, and move the movable mold part. The third step of driving and pressing the press shaft while controlling the torque or the air pressure, and correcting the position of the stopper by the controller, and repeating the first to third steps. A method for molding an optical element, comprising:

According to the supplementary note (2), it is possible to obtain an optical element having good wall thickness accuracy and shape accuracy.

(3) In the second step, when the stop position of the stopper deviates from an appropriate value, the controller calculates a correction value from the output of the position detection means, and corrects the position of the stopper. (2) The method for molding an optical element according to (2).

According to the supplementary note (3), in addition to the effect of the supplementary note (2), it is possible to obtain an optical element having a thickness accuracy without variation.

[0042]

According to the first or second aspect of the present invention,
The stopper is placed at a position close to the movable mold, the thickness accuracy of the optical element is secured by using the stopper position correcting means, and the pressing accuracy is adjusted stepwise after the stopper is released, and the shape accuracy is adjusted. An optical element molding apparatus for obtaining an optical element with good quality can be provided. According to the invention according to claim 2, in addition to the above effects, in the process of press-molding the optical material to the final thickness of the optical element, the pressing force for pressing the optical material is set to a value corresponding to the molding process. Since the servomotor is controlled by the torque, the pressing force can be accurately and easily controlled. According to the invention according to claim 3, 4 or 5, an optical material heated and softened to a temperature equal to or higher than the glass transition point is disposed between the fixed mold and the movable mold, and the mold driving means is driven to move the optical material. The movable mold is stopped at a position where the thickness of the optical element reaches a predetermined thickness with respect to the final thickness of the optical element, and the position at which the movable mold has stopped is measured by the position detecting means, and is measured by the position detecting means. The amount of correction of the stop position was obtained from the stopped position and the movable stop command position, which is a condition for obtaining the final thickness of the optical element, and the temperature of the optical material approached the glass transition point temperature at the movable stop position. Later, by driving the mold driving means to press-mold the optical material to the final thickness of the optical element, an optical element with good wall thickness accuracy and shape accuracy can be obtained. According to the invention according to claim 4 or 5, in addition to the above effects, in the process of press-molding the optical material to the final thickness of the optical element, the pressing force for pressing the optical material is set to a value corresponding to the molding process. Since the press forming is performed while controlling the servomotor with a predetermined torque, the pressing force is accurately and easily controlled, and the shape accuracy of the optical element can be easily obtained. According to the invention according to claim 5, in addition to the above effects, the position of the stopper is changed so that the correction amount of the stop position of the movable die falls within the allowable error range of the stop command position. Can be obtained.

[Brief description of the drawings]

FIG. 1 is a table showing a relationship between a press load and an elapsed time according to an embodiment of the present invention.

FIG. 2 is a configuration diagram of an optical element molding apparatus according to the first embodiment.

FIG. 3 is a schematic configuration diagram of a molding apparatus in an initial state before molding according to the first embodiment.

FIG. 4 is a schematic configuration diagram of a molding device according to the first embodiment during molding by a press shaft being in contact with a stopper.

FIG. 5 is a schematic configuration diagram of the molding apparatus during molding after the stopper of Embodiment 1 is retracted.

FIG. 6 is a configuration diagram of an optical element molding apparatus according to a second embodiment.

FIG. 7 is a schematic configuration diagram of a molding apparatus in an initial state before molding according to a second embodiment.

FIG. 8 is a schematic configuration diagram of a molding apparatus according to a second embodiment in which a press shaft is in contact with a stopper and is being molded.

FIG. 9 is a schematic configuration diagram of a molding apparatus during molding after a stopper of Embodiment 2 is retracted.

[Description of Signs] 1A heater 1B heater 2 Fixed type 5 Moving type 12 Press shaft 22 Pressing servomotor 29 Stopper 34 Stopper servomotor 36 Controller 38 Displacement sensor

Claims (5)

[Claims] 1. An optical element molding apparatus comprising: a fixed mold provided with a heater; and a movable mold opposed to the fixed mold and provided with a heater, wherein the molding device is provided between the fixed mold and the movable mold. A mold driving means for driving the movable mold via a press shaft so as to press the heat-softened optical material; and a method in which the movable mold driven by the mold driving means has a predetermined ratio to a final thickness of the optical element. A stopper for stopping at a position where the thickness of the movable mold is stopped, position detecting means for measuring a stop position of the movable mold stopped by the stopper, and positions of the stopper at a position where the movable mold is stopped and a movable position. And a controller for controlling the stopper driving means and the mold driving means, the stopper driving means being capable of changing the stop position of the movable mold from the output of the position detecting means. Forming apparatus of optical elements. 2. The mold driving means is a servomotor,
The optical element molding apparatus according to claim 1, wherein the controller that controls the mold driving unit controls the servomotor with a predetermined torque. 3. A step of arranging an optical material heated and softened to a temperature equal to or higher than a glass transition point between a fixed mold and a movable mold; A step of stopping the movable mold at a position where the thickness of the element reaches a predetermined thickness with respect to the final thickness of the element, and a step of measuring the position at which the movable mold has stopped by position detection means,
Obtaining a correction amount of the stop position from the stop position measured by the position detection unit and the stop command position of the movable type, which is a condition for obtaining the final thickness of the optical element; A step of driving the mold driving means after the temperature of the material approaches the glass transition temperature to press-mold the optical material to a final thickness of the optical element. 4. The mold driving means is a servomotor,
4. The method of molding an optical element according to claim 3, wherein said servomotor is controlled at a predetermined torque by a controller for controlling said mold driving means. 5. The method according to claim 3, further comprising the step of correcting the position of the movable stop position when the correction amount of the stop position is out of an allowable error range of a stop command position. The method for molding the optical element according to the above.