JPH03223125A - Apparatus for forming optical element - Google Patents

Abstract

PURPOSE:To miniaturize an apparatus and shorten the tact time by arranging top and bottom forces of a forming mold, forming chamber and a spare apparatus in the vertical direction on the same axis. CONSTITUTION:An entrance and exit door 24 of a spare chamber 3 is closed to open an opening and closing door 4. A bottom force 21 is lowered into the chamber 3 and a valve (22a) of a vent valve 22 is opened in the aforementioned state of the bottom force 21 to evacuate a forming chamber 2 and the chamber 3. A valve (23a) of a suction pipe 23 is subsequently opened to introduce an inert gas into the chambers 2 and 3. The door 4 is then closed and the chamber 2, an upper shaft 11 and a lower shaft 20 are heated at a temperature near the glass transition point of a glass material 17 by passing a current through heaters 6, 10 and 19 provided therein. The door 24 is then opened to set the glass material 17 placed on a carrier stage 25 through a conveying shaft 26 on the bottom force 21. The shaft 26 is then retreated to close the door 24. The valves (22a) and (23a) of the vent pipe 22 and the suction pipe 23 are operated to provide an inert atmosphere in the chamber 3. The door 4 is subsequently opened to lift the material 17 with a cylinder 16. The material 17 is fitted into a sleeve 13 and the interior of the chamber 2 is heated until a temperature at which forming can be carried out is attained. The material 17 is then press formed between the top force 12 and the bottom force 21 with cylinders 8 and 16.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an apparatus for molding an optical element by heating and softening a glass material and then press-molding the glass material.

(Prior Art) Conventionally, the following inventions have been disclosed as apparatuses for press-molding optical elements.

For example, in the invention described in JP-A No. 61-44721, an intake chamber, a heating chamber for preheating, a press chamber equipped with a heater, a cooling chamber, and a take-out chamber are each provided separately, and a glass material is installed. An apparatus has been proposed in which an optical element is molded by press-molding the mold by sequentially transferring the mold into the chambers under reduced pressure.

Further, in the invention described in JP-A-1-172234, a heating section is provided coaxially in the vertical direction inside the optical element molding chamber.
An apparatus has been proposed in which a pressurizing section, a cooling section, and a mold are disposed, and the mold is moved up and down by a driving means to heat and soften an optical element material and then press-form it.

[Problem to be solved by the invention]

However, the prior art has the following problems.

That is, the invention described in Japanese Patent Application Laid-Open No. 61-44721 is a system in which each individual chamber is sequentially transferred, so that one line is enlarged in the horizontal axis direction. Furthermore, if a belt conveyor or the like is attached, the device will become bulky. In addition, the sequential transfer method is inefficient because the time required for each process is different, resulting in waiting time for the mold.

Regarding the invention described in JP-A-1-1722:14, a heating section, a pressurizing section, a cooling section, and a molding die are disposed coaxially in the vertical direction inside an optical element molding chamber, and a mold for molding an optical element is provided. After supplying the material between a pair of upper and lower molds and creating an inert gas atmosphere in the molding chamber, heating and pressure molding is performed.However,
In order to take out the molded optical element, the mold must be cooled to near room temperature. Therefore, the takt time becomes longer. Furthermore, during pressure molding, the heat from the mold passes through the pressure section and moves toward the main body. In particular, at the initial stage of startup, the amount of heat in the pressurizing part that moves toward the main body changes moment by moment, and the temperature of the mold fluctuates each time molding is performed. unable to hold.

Therefore, the present invention has been developed in view of the problems in the prior art, and aims to provide an efficient molding device that is compact and shortens takt time.

[Means and effects for solving the problems] The present invention provides a molding apparatus that heats a workpiece and a mold in an inert gas atmosphere and press-moldes an optical element, in which a mold, a mold, and a mold are coaxially arranged in a vertical direction. In addition to arranging a molding chamber and a preliminary chamber, the upper mold is installed so that it can move up and down within the molding chamber, and the lower mold is installed so that it can move vertically within the molding chamber and the preliminary chamber. It is equipped with an independent temperature control means.

In order to mold an optical element using the optical element molding apparatus having the above configuration, first, the molding chamber is replaced with an inert gas atmosphere, and the molding chamber, upper mold, and lower mold are heated to a predetermined temperature. Next, a glass material is placed on the lower mold in the preliminary chamber, and the preliminary chamber is changed to an inert gas atmosphere in the same way as the molding chamber. Then, after raising the lower mold and heating the glass material, upper mold, and lower mold to a temperature that allows molding in the molding chamber, pressure molding is performed.While maintaining this pressurized state, the temperature is lowered to a temperature that does not deform the glass. Cool the molding chamber until . When the temperature has dropped to a temperature at which the glass does not deform, the upper mold and optical element are separated, and the optical element and lower mold are lowered into a preliminary chamber. After the optical element is removed from the lower mold in the preliminary chamber, a new glass material is placed on the lower mold and the molding is repeated.

〔Example〕

Hereinafter, embodiments of the optical element molding apparatus according to the present invention will be described in detail with reference to the drawings.

FIG. 1 is a longitudinal sectional view showing an embodiment of the optical element molding apparatus according to the present invention, FIGS. 2 a and b show the relationship between time and temperature in molding, and FIG. The graph of the device, Figure 2, is a conventional graph.

1 is an optical element molding apparatus; this optical element molding apparatus 1
is composed of a molding chamber 2 and a preliminary chamber 3. The molding chamber 2 is connected above the preliminary chamber 3 via an opening/closing door 4. The inner peripheral surface of the molding chamber 2 is composed of a quartz glass tube 5, and a heater 6 is arranged on the outer peripheral surface of the quartz glass tube 5, which is divided into three parts in the vertical direction and can control the temperature of each part. . A heat insulating material 7 is embedded in a space formed by the outer wall 2a of the molding chamber 2 and the quartz glass tube 5.

A cylinder 8 is fixedly installed at the center of the upper surface of the upper wall 2b of the molding chamber 2. At the lower end of the cylinder 8, there is provided an upper shaft 11 in which a heater lO whose temperature can be controlled via a heat insulating material 9 is installed. It is configured to be movable in the vertical direction by a cylinder 8.

A sleeve 13 that fits the upper mold 12 and is vertically coaxial with the upper mold 12 is fixed to the lower surface of the upper wall 2b by a support tube 14. A stepped portion 13a is formed on the inner surface of this sleeve 13.

A bearing 15 is fixedly installed in the lower part of the preliminary chamber 3, and a cylinder 16 is supported and erected by the bearing link 15.

The cylinder 16 is configured to be able to move up and down so as to be able to transport the glass material 17 from the preliminary chamber 3 to the molding chamber 2 and to pressurize the glass material 17 within the molding chamber 2.

A lower shaft 20 is fixed to the upper end of the cylinder 16 via a heat insulating material 18 and has a temperature controllable heater 19 installed therein. The lower die 21 attached to the upper end of the lower shaft 20 is the sleeve 1
When inserted into the mold 3, the eccentricity with respect to the upper mold 12 can be adjusted.

The preliminary chamber 3 is connected to an exhaust pipe 22 connected to a vacuum pump (not shown) and an intake pipe 23 connected to an inert gas cylinder (not shown) such as N, argon, etc., each having a valve 22a, 23a is provided. Further, the preliminary room 3 is provided with an access door 24. In the vicinity of the preliminary chamber 3, a transport shaft 26 that can move forward and backward is arranged to take the mounting table 25 in and out and transport it from the outside onto the lower mold 21 through the W24. The mounting table 25 is configured so that the glass material 17 is placed thereon, and at the time of molding, the effect of regulating the outer periphery can be obtained as a body shape.

The dimensions of the inner diameter of the sleeve 13, the outer diameter of the upper mold 12, and the outer diameter of the lower mold 21 are determined by taking into account the coefficient of linear expansion of the material and the clearance at which the eccentricity between the molds is less than the allowable amount of the optical element when they are heated. is set.

In the optical element molding apparatus 1 having the above configuration, first, the loading/unloading door 24 of the preliminary chamber 3 is closed, the opening/closing door 4 is opened, and the lower mold 2 is opened.
1 into the preliminary chamber 3, open the valve 22 of the exhaust pipe 22.
A is opened and the molding chamber 2 and preliminary chamber 3 are evacuated. Thereafter, the valve 23a of the intake pipe 23 is opened to allow inert gas to flow in, thereby creating an inert gas atmosphere in the molding chamber 2 and the preliminary chamber 3.

Then, the opening/closing door 4 is closed and the heaters 6, 10, and 19 provided in the molding chamber 2, the upper shaft 11, and the lower shaft 20 are energized, and the temperature reaches the maximum temperature at which the glass material 17 to be molded does not deform. and maintain that temperature. The temperature is a temperature near the glass transition point for boat fishing, but it is precisely determined by taking into consideration the outer diameter, inner thickness, and other shapes of the optical element.

Next, the loading/unloading 1iI 24 is opened and the glass material 17 placed on the mounting table 25 is placed onto the lower mold 21 by the conveying shaft 26. Retract the conveyance shaft 26 and close the loading/unloading door 24,
The valves 22a and 23a of the exhaust pipe 22 and intake pipe 23 are operated to create an inert gas atmosphere in the preliminary chamber 3. and,
The opening/closing door 4 is opened and the glass material 17 is raised by the cylinder 16 and fitted into the sleeve 13.

Thereafter, the temperature of the molding chamber 2 is raised by the heater 6 of the molding chamber 2 until the temperature reaches a temperature at which the upper mold 12, the lower mold 21, and the glass material 17 can be molded. Then, the glass material 17 is pressure-molded using the cylinder 8.16.

After pressure forming, the glass material 17 is gradually cooled to a temperature at which it does not deform, and the pressurization is completed. Then, the upper mold 12 and the lower mold 21 are slightly raised, and the sleeve 13 releases the upper mold 12 and the optical element by raising the upper mold 12.
The end of the optical element or the upper end of the mounting table 25 is brought into contact with the stepped portion. The upper mold 12 is further raised and the optical element is released from the upper mold 12. The mounting table 25 on which the optical element is placed is lowered into the preliminary chamber 3, and the opening/closing door 4 is closed. Inlet/outlet door 24
is opened and the mounting table 25 is taken out using the transport shaft 26, and one molding cycle is completed.

When the loading/unloading door 24 is opened, the valve 23 of the intake pipe 23
A is opened and inert gas flows into the preliminary chamber 3, thereby preventing oxygen from flowing in through the loading/unloading door 24.

FIGS. 2a and 2b show the relationship between time and temperature in molding, where FIG. 2a is a graph of the molding apparatus according to the present invention, and FIG. 2 is a graph of a conventional example. As shown in Figure 2, conventionally, optical elements are molded by raising the temperature from a temperature near room temperature (T o ) to a moldable temperature (T2), and after molding, the optical element is cooled to a temperature near room temperature (TO). takt time was long (from to to t2).

As shown in FIG. 2a, according to the present invention, it is not necessary to cool the mold below the temperature (T,) at which the optical element does not deform, thereby shortening the takt time (from to to t1). can.

Furthermore, the upper and lower forming molds 12.
21 is quickly heated and maintained at a constant temperature, and when the molding chamber is heated, the amount of heat transferred from the upper and lower molding chambers 12 and 21 to the outside can be kept constant, and as a result, the upper and lower molding molds 1
It becomes possible to maintain a constant temperature of 2.21.

In this embodiment, the exhaust pipe 22 for controlling the atmosphere is
Although the intake pipe 23 is provided only in the preliminary chamber 3, the present invention is not limited to this, and may be provided in both the preliminary chamber 3 and the molding chamber 2. In that case, the atmosphere control immediately after startup Time can be further reduced.

Furthermore, if an annealing process is required for the purpose of removing inner diameter distortion of the optical element or adjusting the refractive index, the optical element may be annealed separately after being taken out from the preliminary chamber 3.

〔Effect of the invention〕

As described above, according to the optical element molding apparatus according to the present invention, the mold, the molding chamber, and the preparatory chamber are arranged coaxially in the vertical direction, so that the apparatus can be miniaturized. Further, by providing the upper mold and the lower mold with temperature control means, temperature fluctuations in the mold can be eliminated, and stable molding can be performed quickly after startup. Furthermore, the workpiece is placed on the lower mold in the preparatory chamber, and the workpiece and mold are heated and pressure-molded in the molding chamber, thereby making it possible to shorten the takt time.

[Brief explanation of drawings]

FIG. 1 is a vertical cross-sectional view showing an embodiment of the optical element molding apparatus according to the present invention, FIGS. 2 a and b show the relationship between time and temperature during molding, and FIG. The graph of the molding apparatus in FIG. 2 is a graph of a conventional example. 1... Optical element molding device 2... Molding chamber 3... Preliminary chamber 4... Opening/closing door 5... Quartz glass tube 6.10.19... Heater 7.9.18...・Insulating material 8.16...Cylinder 11...Upper shaft 12...Upper die 13...Sleeve 14...Support cylinder 5...Bearing 7...Glass material O...Lower shaft l... Lower mold 2... Exhaust pipe 3... Intake pipe 4... Load/unload door 5... Mounting table 6-... Conveyance axis

Claims (1)

[Claims] In a molding device that heats a workpiece and a mold in an inert gas atmosphere and press-forms an optical element, a mold, a molding chamber, and a preparatory chamber are disposed coaxially in a vertical direction, and
The upper mold is installed so that it can move vertically within the molding chamber, and the lower mold is installed so that it can move vertically within the molding chamber and the preliminary chamber, and independent temperature control means are provided for each of the upper mold and lower mold. Characteristic optical element molding equipment.