JPH02225325A - Apparatus for forming optical element - Google Patents

Abstract

PURPOSE:To improve durability of a metallic mold by providing a forming chamber having forming molds oppositely arranged in the upper and lower sides with inflow parts for a gas, such as nitrogen, and a gas discharging device and enabling prevention of a rise in oxygen concentration in the forming chamber at high temperatures. CONSTITUTION:A forming chamber 24 is formed from an upper base 13 and a lower base 17 respectively holding a top force 11 and a bottom force 14 and a cover 23 for hermetically sealing the periphery of a forming part. The forming chamber 24 is provided with inflow parts 25 for a gas, such as nitrogen gas, and a gas discharging device 30 is provided at the bottom of a pressing shaft 16. A desired optical element is formed with the top force 11 and bottom force 14 oppositely arranged in the upper and lower sides.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention provides an optical element molding device for heating and softening an optical glass material and molding it into a desired lens shape through a pair of upper and lower molding molds. Regarding.

[Conventional technology]

The above-mentioned molding device of this type is disclosed in Japanese Patent Application Laid-Open No. 6228811.
There is a technique disclosed in Publication No. 9. A schematic configuration of this technology is shown in Fig. 3. As shown in the figure, in this molding apparatus, in order to prevent the upper and lower molds 1.2 from being oxidized at high temperatures, the surroundings of the mold 3 are The mold 3 is surrounded by a quartz glass tube 4, and nitrogen gas or the like is supplied from an atmospheric gas supply device 6 into the interior 5 of the device to prevent oxidation of the mold 3.

[Problem to be solved by the invention]

However, in the configuration of the prior art described above, if the temperature of the atmosphere inside the device 5 is around room temperature (around 20°C), it is possible to considerably prevent oxygen from entering from the outside, and the oxygen concentration can be reduced to 1%.
It is possible to do the following, but at the time of molding, that is, the mold 3
When the heating furnace is at a high temperature, the atmosphere inside the device 5 also becomes high temperature, so a convection of non-oxidizing gas occurs, and as a result, oxygen mainly enters through the gap between the lower mold 2 and the lower plate 2a, causing the inside 5 to become hot. There was a problem in that the oxygen concentration of the metal mold 3 increased, and as a result, the mold 3 became susceptible to oxidation.

The present invention has been made in view of the above problems, and is an optical element molding apparatus that prevents oxidation of a mold due to an increase in oxygen concentration at high temperatures and improves the durability of the mold. The purpose is to provide

[Means to solve the problem]

In view of the above problems, the molding apparatus according to the present invention is an optical element molding apparatus that molds a desired optical element using molds arranged vertically opposite to each other. A molding chamber is configured with a cover that seals the periphery of the molding section, and a gas inlet such as nitrogen gas is provided in the molding chamber, the lower mold is fixed to the upper part of the molding chamber, and the press shaft is held by the lower base. An exhaust device for gas supplied into the molding chamber is provided at the bottom of the molding chamber.

In addition, temperature sensors are provided on the upper base and the lower base, and when the temperature of the upper base becomes higher than the temperature of the lower base, the exhaust device is activated to cause the gas in the molding chamber to flow downward. You may.

[For production]

In the above configuration, oxygen is prevented from entering the forming chamber by supplying gas such as nitrogen gas from the gas inlet into the forming chamber and activating the exhaust device as the temperature of the upper and lower bases rises. Ru.

〔Example〕

Embodiments of the present invention will be described in detail below with reference to the drawings.

(First Embodiment) FIG. 1 shows a first embodiment of an optical element molding apparatus 10 according to the present invention.
FIG. 3 is a longitudinal cross-sectional view showing an example.

In the figure, reference numeral 11 indicates an upper mold, and the upper mold 11 is fixed to an upper base 13 via an upper mold heater 12. Reference numeral 14 indicates a lower mold, and the lower mold 14 is fixed to a press shaft 16 via a lower mold heater 15. The press shaft 16 is held in a housing 18 fixed to a lower base 17 via a bearing (sliding bearing) 19 so as to be freely slidable in the axial direction.
It is configured to be able to be driven up and down via a driving air cylinder 20. The upper mold 11 and the lower mold 14 are arranged facing each other on the same axis, and the upper mold 11. The lower mold 14 is also configured to be able to be controlled to a predetermined temperature via the above-mentioned upper mold heater 12 and lower mold heater 15, which are connected to a temperature control device (not shown).

Around the heating furnace 21 and the molding section 22, a cover 23 and upper and lower bases 1 made of a quartz glass tube or a stainless steel tube are arranged.
3.17, and these members 23,
1.3 and 1.7 form a molding chamber 24. A gas nozzle 25 connected to an atmospheric gas supply device (not shown) is provided through the upper and lower bases 13.17, and nitrogen gas and inert gas are supplied into the molding chamber 24 through the gas nozzle 25. or reducing gas to prevent oxidation inside the molding chamber 24. Upper and lower base 1
3 and 17 are connected via a member not shown, so that the mutual distance and position between the upper base 13 and the lower base 17 do not change.

An exhaust device 30 is fixedly installed at the lower part of the housing 18, and can exhaust the gas inside the molding chamber 24 and the housing 18.

The upper and lower bases 13.17 are connected to a temperature monitor 31 so that the temperature of each of the upper and lower bases 13.17 can be measured. 32 is a carrier on which the optical glass material 33 and the optical element after press molding are placed and transported;
This carrier 32 is held by a carrier conveyance arm 34 and is transferred through a heating furnace 21 that can be set at a predetermined temperature by a temperature control device (not shown).
and the lower die 14.

35 indicates 0. The temperature sensor 21a is a furnace heater.

Next, the operation of molding an optical element using the molding apparatus 10 having the above configuration will be explained.

First, at room temperature, that is, before the start of heating, nitrogen gas or the like is supplied into the molding chamber 24 from the upper and lower gas nozzles 25 to replace the oxygen concentration inside the molding chamber 24 to 1% or less. At this time, the oxygen concentration is set to O! Measurement is performed using the concentration sensor 35.

Next, the heating furnace 21° and the upper mold 11.degree. The lower mold 14 is heated to a predetermined temperature. Along with this heating, the upper base 13. As the temperature inside the lower base 17 and the molding chamber 24 also rises, convection occurs within the molding chamber 24. Due to this convection, oxygen mainly from outside the housing 18 enters the molding chamber 24, and the oxygen concentration within the molding chamber 24 decreases. rises. The timing at this time is correlated with the temperature of the upper base 13 and lower base 17, so the upper and lower bases 1
This can be determined by measuring the temperature in 3.17.

At this point, the exhaust bag 230 is activated, the gas supply from the gas nozzles 25 of the lower base 17 is stopped, nitrogen gas, etc. is supplied only from the gas nozzle 25 of the upper base 13, and the flow is directed downward, that is, in the direction of the arrow 40. generate a flow of gas. Note that the gas flow rate at this time is optimally set by the exhaust device 30 in consideration of the balance between supply and discharge. As a result, the inside of the molding chamber 24 becomes a laminar flow state with no convection, and the entry of oxygen from the outside can be blocked. As a result, the oxygen concentration inside the molding chamber 24 can be maintained at a low concentration of 1% or less. can.

In this state, the heating furnace 21. Upper mold 11. When the lower mold 14 reaches a predetermined temperature, the optical glass material 33 is placed in the carrier 32 and carried into the heating furnace 21 via the carrier conveying arm 34, and the optical glass material 33 is placed in the carrier 32 through the upper and lower heaters 21a. 33 is heated and softened until it becomes moldable (up to the softening point temperature).

Next, the conveying arm 34 is advanced to convey the optical glass material 33 together with the carrier 32 between the upper and lower molds 11 and 14. Thereafter, the lower mold 14 is moved upward through the cylinder 20, and the softened optical glass material 33 is press-molded through the upper and lower molds 11 and 14.

When the molding is completed, the lower mold 14 is moved down to release the mold, and the molded optical element is transported via the transport arm 34 into a slow cooling furnace (not shown) provided on the opposite side to the heating furnace 21. death,
The press-molded optical element is cooled, and then the optical element is taken out from the carrier 32.

As explained above, according to this embodiment, the oxygen concentration inside the molding chamber 24 can be maintained at a low concentration of 1% or less even at high temperatures, so oxidation of the upper and lower molds 11 and 14 can be prevented. , the durability of the mold 11°I4 can be improved.

In this embodiment, the gas supply from the gas nozzle 25 of the lower base 17 was stopped and gas was supplied only from the gas nozzle 25 of the upper base 13, but a weak gas supply from the gas nozzle 25 of the lower base I7 was However, in the range where no convection occurs in the molding chamber 24, that is, in the range where laminar flow of gas is ensured, the same effect can be achieved (Second Embodiment). Embodiment 6 This embodiment shows the second embodiment of the invention.
In the configuration shown in the figure, a judge medium 51 is disposed between the molding chamber 24 and the heating furnace 21 and is held movably in the horizontal front and rear directions via a shutter frame 50. The rest of the configuration is the same as in the first embodiment, so the same members are given the same reference numerals and their explanations will be omitted.

According to this embodiment, there is an effect that the degree of sealing of the molding chamber 24 can be improved. Other functions and effects are the same as those in the first embodiment, so their explanation will be omitted.

〔Effect of the invention〕

As described above, according to the present invention, it is possible to prevent the oxygen concentration in the molding chamber from increasing at high temperatures, so the oxygen concentration is always kept at 1.
% or less, thereby preventing oxidation of the mold and improving the durability of the mold.

[Brief explanation of the drawing]

FIG. 1 is a vertical cross-sectional view showing a first embodiment of the apparatus according to the present invention, FIG. 2 is a vertical cross-sectional view, and FIG. 3 is an explanatory diagram of the prior art. 11... Upper die 13... Upper base 14... Lower die 16... Press shaft 17... Lower heath 23... Cover 24... Molding chamber 25... Gas nozzle 39... Exhaust device The second embodiment of the device according to the present invention is presented by the applicant Olympus Optical Industry Co., Ltd.

Claims (2)

[Claims] (1) An upper base that holds an upper mold and a lower mold, respectively, in an optical element molding apparatus that molds a desired optical element using molds arranged vertically to face each other. A molding chamber is configured with a lower base and a cover that seals around the molding section, and a gas inflow port for nitrogen gas or the like is provided in the molding chamber, and the lower mold is fixed on the upper part and held by the lower base. 1. A molding apparatus for an optical element, characterized in that an exhaust device for gas supplied into the molding chamber is provided at a lower part of a press shaft. (2) Temperature sensors are installed on the upper and lower bases, and when the temperature of the upper base becomes higher than the temperature of the lower base, the exhaust device is activated to cause the gas in the molding chamber to flow downward. The optical element molding apparatus according to claim 1, characterized in that: