JP2008056502A - Apparatus for molding optical element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an apparatus for molding an optical element reducing the time needed for stabilizing the temperature of a set of molds after heating is started. <P>SOLUTION: The apparatus is for molding an optical element by conveying a set of molds 15, where an optical element material is placed between the upper mold and the lower mold, in sequence to each process stage, i. e. heating, press-molding, and cooling, where a thermocouple 26 is embedded in the plate 1 of the heating stage around the lower surface of the lower mold of the set of molds. Electricity is supplied independently to respective infrared lamps 22 arranged to be moving up and down in an infrared lamp heating apparatus 4. More electricity is supplied for heating the plate to the infrared lamps placed at the lowest row which are located nearest to the plate than those supplied to the other infrared lamps placed at the middle and upper rows. Since the thermocouple is embedded in the plate and does not receive directly the radiant heat from the infrared lamps, it can feed back a stable detected signal to a heater control unit (not shown) and a designated temperature can be attained within a short time after heating is started. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an optical element molding apparatus that heats and softens an optical element material, and particularly relates to a heating means for heating a mold set on which the optical element material is placed before the pressure molding.

  Pressing in a device that molds a desired optical element by sequentially transferring the mold set with the optical element material placed between the upper mold and the lower mold to each process area with heating, pressure molding and cooling In the heating stage in which the mold set is heated to a predetermined temperature before molding, the mold set and the optical element material are heated by sandwiching the mold set with heating plates arranged in the vertical direction of the mold set. (Patent Document 1). However, in the method according to Patent Document 1, since the heating plate is brought into contact with the mold set, not only the heating efficiency is low and the temperature rising rate is slow, but the mold set is easily damaged, and a relatively large size mold set is used. In order to avoid such problems, the present inventors have come to consider the configuration of the heating unit 4 shown in FIG. 6 in which the upper heating plate is changed to a non-contact heating method. .

FIG. 6 shows the details of the configuration of the heating unit 4. In order to measure the temperature of the mold set 15, a thermocouple 24 supported by a spring 25 is provided at the top. Further, the lower plate 1 is provided with a sheath heater 1a for heating and a thermocouple for temperature measurement (not shown).
The thermocouple 24 that is in direct contact with the upper part of the mold set 15 includes the contact angle with the upper mold of the mold set 15, the surface roughness of the contact surface between the mold set 15 and the thermocouple 24, the degree of oxidation, etc. As a result, the measurement temperature is not stabilized, the temperature variation among the molds, the repeatability in the same mold set 15 is very unstable, and the thermocouple 24 is directly connected to the infrared lamp 22. Since the radiant heat from the reflecting plate 23 and the like is received, it has been found that accurate temperature measurement is difficult due to heat conduction of the thermocouple sheath portion and that the lifetime of the thermocouple 24 is short. The heating unit 4 is a system that heats with the infrared lamp 22 for non-contact heating and the sheath heater 1a in the lower plate 1, but the heating rate by the infrared lamp 22 is fast, and conversely the heating rate of the sheath heater 1a is Since it is slow, when heating is started at the same time, it has been found that it takes time for the temperature to stabilize due to interference with each other.
JP 62-292629

  As a result of examining the above-mentioned problems, the inventors have embedded a temperature sensor in a plate on which the mold set is placed, and measures the temperature in the vicinity of the plate surface in contact with the mold by the sensor. It was found that the temperature of the set can be controlled with high accuracy.

  Accordingly, an object of the present invention is to enable a thermocouple for measuring the temperature of a mold set not to receive radiant heat directly from an infrared lamp, a reflector, etc., and to accurately measure the temperature, and to make the thermocouple longer. Another object of the present invention is to provide an optical element molding apparatus that can be used and that can shorten the time until the temperature of a mold set is stabilized after the start of heating.

In order to achieve the above object, an optical element molding apparatus according to the present invention comprises:
A molding apparatus for molding an optical element by sequentially transporting a mold set in which an optical element material is placed between an upper mold and a lower mold to each process stage of heating, pressure molding, and cooling. The molding equipment
A molding chamber in which the mold set is mounted, and a plate for performing heating, pressure molding, and cooling processes on the mounted mold set, respectively, is disposed in the molding chamber. Conveying means for moving the mold set to a predetermined position on the upper surface of the plates adjacent to each other, and a control device for controlling the heating, pressure forming and cooling processes and the conveying means,
The heating process stage is disposed so as to be movable up and down around a mold set placed in contact with the lower plate, and heating means for heating the mold set in a non-contact manner,
Temperature control means for controlling the heating means;
The mold set is mounted, and a temperature sensor embedded near the center of the lower plate so as to measure the temperature near the lower plate surface; and
The temperature detected by the temperature sensor is fed back to the temperature control means.

In this case, it is preferable that the heating means is a non-contact type heater arranged on the outer peripheral portion, the upper portion or the outer peripheral portion and the upper portion of the mold set on which the optical element material is placed.
Further, in that case, the heating means is a non-contact heater disposed on the outer periphery of the mold set on which the optical element material is placed, and the heater output near the lower plate on which the mold set is placed, It can be set larger with respect to the heater output located farther from the lower plate.
Further, in this case, the temperature control means for controlling the heating means outputs the total output of the non-contact type heater arranged on the outer periphery of the mold set on which the optical element material is placed, to the mold set. It can be changed according to the height.
In this case, the heating means may be constituted by an infrared lamp heater arranged on the outer periphery of the mold set on which the optical element material is placed, and the infrared lamp heater may be configured to perform radiant heating.
Further, in that case, the heating means may be constituted by a resistance heating device disposed on the outer peripheral portion of the mold set on which the optical element material is placed, and may be configured to perform radiant heating using the resistance heating device. it can.
Further, in that case, the heating means is composed of a high-frequency induction coil arranged on the outer periphery of the mold set on which the optical element material is placed, and is configured to perform high-frequency induction heating using the high-frequency induction coil. Can do.

According to the present invention, the heating process stage is disposed so as to be movable up and down around the mold set placed in contact with the lower plate, and heating means for heating the mold set in a non-contact manner. A temperature control means for controlling the heating means and a temperature sensor on which the mold set is mounted and embedded in the vicinity of the center of the lower plate so as to measure the temperature in the vicinity of the lower plate surface. Since the detected temperature is fed back to the temperature control means, the temperature sensor for measuring the temperature of the mold set does not directly receive radiant heat from the non-contact type heating means, enabling accurate temperature measurement. In addition, the lifetime of the temperature sensor can be extended, and the time until the temperature of the mold set is stabilized after the start of heating can be shortened.

Hereinafter, examples based on embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 shows the arrangement of the overall configuration of an optical element molding apparatus to which the present invention is applied. In FIG. 1, reference numeral 8 is a molding chamber, and an import load lock chamber (hereinafter referred to as a replacement chamber) 12 for waiting a mold set 15 before molding is placed on the upper surface of the right end portion, and an upper surface of the left end portion thereof. An outport load lock chamber (hereinafter referred to as a replacement chamber) 13 is provided for waiting for the mold set 15 after molding. A vacuum pump 30 is connected to the replacement chamber 12 via a pipe L. Further, nitrogen gas is supplied from the nitrogen gas supply unit 40 to the replacement chambers 12 and 13 and the molding chamber 8 via supply pipelines L1, L2, and L3, respectively. In this embodiment, nitrogen gas is used as an inert gas. Each of the pipes L, L1, L2, L3 is provided with a valve as shown in the figure so that the shutoff or opening degree of each pipe can be adjusted.

  Inside the molding chamber 8, a table 9 that is movable up and down by an air cylinder 11 a provided below the replacement chamber 12 is arranged, and a mold set 15 before molding is mounted through the opening 12 a of the replacement chamber 12. To receive. Similarly, a table 10 that can be moved up and down by an air cylinder 11 b provided below the replacement chamber 13 is disposed, and a mold set 15 that is mounted on the table 10 has an opening 13 a in the replacement chamber 13. Through the replacement chamber 13. Each of the openings 12a and 13a is provided with a shutter that hermetically blocks the replacement chambers 12 and 13 and the molding chamber 8 from each other.

Between the tables 9 and 10, a plate 1 forming a heating zone and a known infrared lamp heater device 4, a pair of upper and lower plates 2 and 5 forming a pressure forming zone, and a pair of cooling zones are formed. Plates 3 and 6 are arranged. The infrared lamp heater device 4 can be moved up and down by a rod of an air cylinder 7a, and is lifted upward when the mold set 15 is transferred from the table 9 onto the adjacent plate 1.
Reference numeral 22 denotes each lamp unit of the infrared lamp heater device 4 and is configured such that the output of the lamp can be controlled independently. Reference numeral 7b is an air cylinder that allows the upper plate 6 of the cooling zone to move up and down.

  Cartridge heaters 2a and 5a are embedded in the plates 2 and 5 forming the stage of the pressure forming zone, respectively, and a temperature sensor (not shown) is embedded in the center of each plate, The temperature in the vicinity of the surface of the contacting plate central portion is detected. The upper plate 5 is fixed to a shaft 20 c coupled to the servo motor unit 20. Accordingly, the rotation of the output shaft of the servo motor 20a together with the plate 5 is advanced and retracted up and down via a known servo motor unit 20 including a linear motion conversion portion 20b including a nut, and pressure forming. During the process, the position of the plate 5 and the pressing force against the mold set 15 are controlled by the servo motor 20a.

  Reference numeral 50 denotes the entirety of the conveying device disposed on the rear side of each zone in the molding chamber 8, and details thereof are shown in FIGS. 2 (a) and 2 (b).

  The example shown in FIG. 2A shows a state in which the interior of the molding chamber 8 is viewed from above, and is a configuration using a robot arm. Specifically, the mold set 15 in the molding chamber 8 is These are transported between the tables 9, 10 and the plates 1, 2, 3 using a robot arm. As shown in FIG. 5A, the transport device 50 includes a mold transport unit 51 that transports the mold set 15 from the intake zone to the heating zone, and a mold transport unit 52 that transports the heating zone to the pressure molding zone. , A mold conveyance unit 53 that conveys from the pressure molding zone to the cooling zone, and a mold conveyance unit 54 that conveys from the cooling zone to the take-out zone.

  In addition, although the metal mold | die conveyance unit is arrange | positioned between each zone here, you may share a some conveyance unit with one. Further, if the table 9 and the table 10 in the lowered state are arranged so that the upper surfaces of the lower plates 1, 2, and 3 of each zone are on the same horizontal plane, the mold set 15 need only be moved horizontally. The transport unit has a small degree of freedom and may be a simple mechanism. Further, in the figure, each heating, pressing, and cooling zone is provided one by one, but a plurality of zones may be provided in consideration of molding tact and the like.

FIG. 2B shows a cross section of the mold set 15. The mold set 15 includes an upper mold 18 a having a guide hole and a lower mold 18 b having a guide pin 17. An optical element material 19 is placed between the upper mold 18a and the lower mold 18b. Although not shown, a spring is disposed between the upper and lower molds 18a and 18b so that the load of the upper mold 18a does not act on the optical element material 19 except during pressure molding.
In FIG. 1, introduction / discharge of the mold set 15 between the replacement chambers 12 and 13 and the outside is not illustrated, but for example, a shutter is provided on the upper surface or side surface of each replacement chamber 12 or 13. The shutters can be opened and closed when the mold set 15 is introduced and discharged.

  Reference numeral 60 in FIG. 1 is a controller that controls the above-described components 12, 13, 11a, 11b, 7a, 7b, 20a, 4, 2a, 5a, 30, 40, 50, and the like. FIG. 3 shows a configuration block, and FIG. 4 shows an example of temperature control of the infrared lamp heater device.

  In FIG. 3, the controller 60 basically takes the flow of the operation of the molding apparatus, that is, takes the mold set 15 into the replacement chamber 12 and introduces it into the molding chamber 8, and sequentially passes through each molding process from the replacement chamber 13 to the outside. The control device 60a generates a command signal for the operation sequence of each component corresponding to a series of sequences until discharging, and a plurality of control units respectively connected to the control device 60a.

    Here, the control unit includes a heater temperature control unit 60b for driving the infrared lamp heater device 4 in the heating zone, and a temperature control unit 60c for the cartridge heaters 2a and 5a embedded in the plates 2 and 5 in the pressure molding zone. , A drive control unit 60d for the servo motor unit 20 in the pressure forming zone, a cylinder drive unit 60e for driving and controlling the air cylinders, a shutter drive unit 60f for opening and closing the shutters, and the pipes A valve drive unit 60g for driving and controlling the operation of the on-off valve is provided.

  In FIG. 4, the heater control unit 60b for the infrared lamp includes power PW1 and PW2 independently for the upper, middle, and lower infrared lamp units 22, 22, and 22 provided in the infrared lamp heater device 4, respectively. , PW3 is supplied. Reference numerals 70, 72, and 74 are circuit breakers that turn on and off the supply of power to the respective infrared lamp units, and an on / off command is given by the heater control unit 60 b based on a detection signal from the thermocouple 26. . In the figure, three infrared lamp units are illustrated, but the number is not limited to three for the purpose of the present invention.

  FIG. 5 shows the configuration of the infrared lamp heater device in detail. In FIG. 5, the same components as those shown in FIG. 6 are given the same reference numerals. The infrared lamp heater device 4 includes three infrared lamp heaters 22 processed in an arc shape in a vertical arrangement in the vertical direction. A reflection mirror 23 is provided on the outer periphery of each infrared lamp heater 22. The reflecting mirror 23 is gold-plated in consideration of the reflection efficiency of radiant heat. Using the thermocouple 26 that is a temperature sensor embedded in the plate 1, the output of each infrared lamp heater 22 is adjusted by the infrared lamp heater control unit 60 b so that the mold set 15 has a desired temperature. It has become.

Further, the output of each infrared lamp can be blocked by the circuit breakers 70 to 74 according to the height of the mold set 15. In this configuration, an optical lens having a diameter of about 15 mm was molded using an optical element material having a Tg point of 560 ° C.
In that case, when continuous molding is performed under the conditions where the molding temperature of the pressure molding part is 570 ° C. and the applied pressure is 3 kN, the thickness accuracy of the molded product is ± 10 μm or more because the temperature reproducibility in the heating part is poor in the past. Although there was variation, according to this example, the temperature reproducibility can be improved to ± 0.5 ° C. or less and the thickness accuracy of the molded product can be improved to ± 5 μm or less, and the molding accuracy can be improved. .

In addition, conventionally, since it is necessary to heat the plate 1 at the lower part of the mold set 15, the upper part of the mold set 15 tends to be warmed, and the shape defect of the molded product occurs at a rate of less than 20%. . Therefore, by increasing the heater output of the lower part of the infrared lamp 22 by about 20% compared to other stages, the temperature difference between the upper and lower parts of the mold set 15 is within about 3 degrees, and the shape defect is reduced to 5% or less. It became possible to make it.
In addition, although the example using the infrared lamp 22 was shown in FIG. 4, it is also possible to use a resistance heating apparatus and a high frequency induction coil as a heating means.

  Although the preferred embodiments of the present invention have been described with reference to the accompanying drawings, those skilled in the art can implement various modifications without departing from the spirit of the present invention.

It is a figure which shows arrangement | positioning of the whole structure of the optical element shaping | molding apparatus to which this invention is applied. FIGS. 1A and 1B are diagrams for explaining the transfer device and the mold set of FIG. 1, respectively, wherein FIG. 1A is a view of the molding chamber as viewed from above, and shows a mold transfer unit disposed in the vicinity of each plate; b) is a view showing a cross section of the mold set. It is a block diagram which shows schematic structure of the controller of FIG. It is a control block diagram which shows the example of the temperature control of the infrared lamp heater apparatus which illustrates the structure of the heating means by this invention. It is sectional drawing of the infrared lamp heater apparatus which illustrates the structure of the heating means by this invention. It is sectional drawing of the infrared lamp heater apparatus which illustrates the structure of the conventional heating means.

Explanation of symbols

1, 2, 3, 5, 6 Plate 4 Infrared lamp heater device 7a, 7b Air cylinder 8 Molding chamber 9, 10 Table 11a, 11b Air cylinder 12, 13 Replacement chamber 15 Mold assembly 17 Guide pin 18a Upper mold 18b Bottom Mold 19 Optical element material 26 Thermocouple 30 Vacuum pump 40 Nitrogen gas supply unit 50 Transport device 51, 52, 53, 54 Mold transport unit 60 Controller 60a Control device 60b Heater control unit 60c Cartridge heater temperature control unit 60d Servo motor drive Control unit 70, 72, 74 Breaker

Claims (7)

A molding apparatus for molding an optical element by sequentially transporting a mold set in which an optical element material is placed between an upper mold and a lower mold to each process stage of heating, pressure molding, and cooling. The molding equipment
A molding chamber in which the mold set is mounted, and a plate for performing heating, pressure molding, and cooling processes on the mounted mold set is disposed therein,
Conveying means for moving the mold set to predetermined positions on the upper surfaces of the plates adjacent to each other in the molding chamber;
The heating, pressure forming, and cooling processes and a control device that controls the conveying means,
The heating process stage is disposed so as to be movable up and down around a mold set placed in contact with the lower plate, and heating means for heating the mold set in a non-contact manner,
Temperature control means for controlling the heating means;
The mold set is mounted, and a temperature sensor embedded near the center of the lower plate so as to measure the temperature near the lower plate surface; and
An optical element molding apparatus, wherein the temperature detected by the temperature sensor is fed back to the temperature control means. 2. The heating unit according to claim 1, wherein the heating means is a non-contact type heater arranged at an outer peripheral portion, an upper portion, or an outer peripheral portion and an upper portion of a mold set in which the optical element material is placed. Optical element molding device. In the non-contact heater disposed on the outer periphery of the mold set on which the optical element material is placed, the heating means outputs a heater output near the lower plate on which the mold set is placed from the lower plate. The optical element molding apparatus according to claim 1 or 2, wherein a large value is set for a heater output located far away. The temperature control means for controlling the heating means determines the total output of the non-contact type heater arranged on the outer periphery of the mold set on which the optical element material is placed according to the height of the mold set. The optical element molding apparatus according to claim 1, wherein the optical element molding apparatus can be changed. 5. The heating means according to claim 1, wherein the heating means comprises an infrared lamp heater disposed on an outer peripheral portion of a mold set on which the optical element material is placed, and radiant heating is performed by the infrared lamp heater. The optical element molding apparatus described in any one. The heating means is composed of a resistance heating device disposed on an outer periphery of a mold set on which the optical element material is placed, and radiant heating is performed using the resistance heating device. 4. The optical element molding apparatus described in any one of 4 above. 2. The heating means is constituted by a high frequency induction coil disposed on an outer peripheral portion of a mold set on which the optical element material is placed, and high frequency induction heating is performed using the high frequency induction coil. The optical element molding apparatus described in any one of 4 thru | or 4.

Images