JPS63277528A - Production of optical element and production device therefor - Google Patents

Abstract

PURPOSE:To produce an optical element in a short time and in excellent inversion, by transferring glass preform brought into contact with a heating block and heated to between molds and press molding. CONSTITUTION:Glass preform 3 held by an arm 21 attached to the tip of an arm driving mechanism 22 is transferred through a preform transporting mechanism part 20 from an inlet 4 to a molding chamber 2, the arm 21 is upward moved by the mechanism 22 and the preform 3 is brought into contact with a preheated heat transfer member 6a of a heating block part 6 at the fixed side. Then a heating block part 7 at the mobile side is upward moved, the preform 3 is brought into contact with a heat transfer member 7a, heated, then the block part 7 and the arm 21 are downward moved. Then the preform 3 is transferred through the mechanism 20 to between molding blocks 8 and 9 the arm 21 is upward moved, the preform 3 is brought into contact with a molding face 11a of a mold 11, the molding block 9 is upward moved, the perform is brought into contact with a molding face 12a of a mold 12, pressurized and press molded.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention involves heating a glass preform to a predetermined temperature, transferring it between molds, and press-molding it into a predetermined shape in the mold to obtain a desired shape. An object of the present invention is to provide a method for manufacturing an optical element and an apparatus for manufacturing the same.

[Conventional technology]

As this kind of technology mentioned above, for example, Japanese Patent Application Laid-Open No. 61-219
There is a technique disclosed in Publication No. 27. In this technique, a glass preform is inserted into a press mold in which an upper mold and a lower mold are fitted into a sleeve and at least the upper mold is slidable, and the glass preform has a glass viscosity of 10".
・At a temperature corresponding to 5 to 1010° 5 poise, a load is applied to the upper mold using a push rod separate from the upper mold, and the upper mold is pressed for several seconds to several tens of seconds.Then, the push rod is moved back to release the load, and the glass is pressed. A pressed lens is produced by cooling the molded object while it is wrapped in the mold until the glass viscosity becomes 101).5 poise or more. As a concrete first example, a glass preform is set between upper and lower molds, and after heating both the press mold and the preform, they are pressurized at a predetermined pressure for a predetermined time, and after the pressure is released, the glass is formed. A method for cooling and removing the body at a rate of 25° C./sin is described. In addition, as a second embodiment, the upper and lower molds and the sleeve are heated in advance with a heater, while the preform is heated in a furnace separate from the pressurizing section until it reaches a predetermined viscosity. A method is described in which the preform is transferred between upper and lower molds via a transfer device, pressed, and then cooled at a cooling rate of 15° C./sin, removing any load other than the weight of the upper mold, and then taken out.

[Problem that the invention seeks to solve]

Although the above-mentioned conventional technology aims to improve the manufacturing speed of press lenses, it is not satisfactory for the following reasons.

That is, in the technique of the first embodiment of the above publication, after the preform is set between the upper and lower molds, the preform and the pressing mold (consisting of the upper and lower molds and a sleeve etc. that slidably holds the upper and lower molds) are attached together. Since this method involves first heating and then cooling again after press molding, there is a problem in that the time required for production is extremely long and the purpose cannot be achieved. In this case, it is conceivable to raise the mold temperature to a high temperature in order to shorten the manufacturing time, but if you try to raise the mold temperature to a high temperature, the mold and glass will react and molding will not be possible. Furthermore, the technique of the second embodiment also has the disadvantage that it takes time to heat the glass preform in the heating furnace, making it difficult to achieve the objective. In addition, when a glass preform is heated to a moldable state in a heating furnace, the viscosity of the glass preform decreases during heating and becomes warped, which increases the amount of molding and makes it uneven. There was a problem in that sufficient reversibility could not be obtained when pressing between the upper and lower dies.

The present invention has been made in view of the problems of the prior art described above, and includes a method for manufacturing an optical element that can shorten the manufacturing time when manufacturing the optical element and improve reversibility during molding. The purpose is to provide equipment.

[Means and effects for solving the problems] FIG. 1 shows a conceptual diagram of the present invention.

As shown in the figure, a manufacturing apparatus 1 for manufacturing an optical element 3a can freely contact a glass preform 3,
6. Heating block with temperature controllable and pressure means.
7, and molds 8 and 9 for press-molding the glass preform 3 heated to a predetermined temperature via the heating block 6°7.

When manufacturing the optical element 3a using the manufacturing apparatus 1, first, the glass preform 3 is transferred between the heating blocks 6.7 and stopped, and the heating block 6.7 heated by the glass preform 3 is transferred to the heating block 6.7. Heat by contacting.

Next, the heated glass preform 3 is placed in a mold 8.9.
The optical element 3a is then transferred and press-molded into an optical element 3a having a predetermined shape.

In the manufacturing apparatus 1 and manufacturing method described above, the glass preform 3 can be press-molded in a short time, and the reversibility between the mold and the molded product during molding is extremely good.

〔Example〕

Embodiments of the present invention will be described in detail below with reference to the drawings. In the following description, the same components as those shown in FIG. 1 are denoted by the same reference numerals as L.

2 and 3 show a manufacturing bag W1 for implementing one embodiment of the method for manufacturing an optical element according to the present invention, FIG. 2 is a front sectional view, and FIG. It is a top view of the main part of a figure.

In the figure, 2 indicates the molding room (frame body), and this molding room 2 includes an entrance 4 for carrying 31 g of preforms for 12 people, and a transport port for transporting the molded products that have been molded out of the molding room 2. Exit 5 is now open.

A pair of heating block parts 6.7 and a pair of mold block parts 8.9 are provided in the molding chamber 2. The pair of heating block parts 6.7 are for heating the preform 3 to be press-molded by the pair of mold block parts 8 and 9 to a moldable state. It is also located on the loading port 4 side. One side of the pair of heating block parts 6.7 (upper side in Fig. 2)
The heating block section 6 is fixedly installed on the upper surface inside the molding chamber 2, and the block section 7 on the other side is configured to be movable in the direction toward and away from the heating block section 6 on the one side. . Each heating block part 6, 7 includes a heat transfer member 6a, 7a which can freely contact the preform 3, a heating heater 6b which is a heat generation source,
7b, insulation play) 6c, 7c,
The - side heating block section 6 is fixed to the molding chamber 2 via a heat insulating plate 6C. The heating block section 7 on the other side is configured to be freely movable and driven via a block drive section 10 such as a cylinder device fixedly installed in the molding chamber 2. The heat transfer parts 5a and 7a are made of a ceramic material such as SiC, which is heat resistant and has good thermal conductivity, and has poor wettability with glass, such as CBN. 7c is made of a ceramic-based heat insulating material with poor thermal conductivity such as zirconia. The heat transfer portions 6a, 7a of each heating block portion 6°7 are connected to both heat transfer portions 6a, 7a.
This is for heating the preform 3 by contacting it with the preform 3 carried in between, and the temperature of each heating block 6.7 and the contact time with the preform 3 are the same as that of the preform 3.
can be controlled arbitrarily depending on the size and shape of the

The mold block part 8.9 is similar to the heating block part 6.
is fixed on the upper surface of the molding chamber 2, and the mold block section 9 on the other side is configured to be movable in the direction toward and away from the mold block 8 on the one side. Each mold block 8,
9 is a mold 1) for press-molding the preform 3 heated in the heating block section 6.7. 12, heaters 8a and 9a which are heat generation sources, and a heat insulating plate 8b
, 9b, - the mold block part 8 of the example
is fixed to the molding chamber 2 via a heat insulating plate 8b. The mold block section 9 on the other side is configured to be movably driven via a mold drive section 13 such as a cylinder device fixedly installed in the molding chamber 2. Heaters 8a, 9
a and heat insulation play) 8b, 9b are heating block parts 6,
It has the same configuration as the heaters 6b, 7b, heat insulation plate) 6C, 7c of No. 7. Molding mold 1). 12 is made of 13 chromium-based stainless steel material, CrCn, or other carbide material, and each molding surface 1) 8° 12a is shaped into a spherical, flat, or aspherical shape to correspond to the desired shape of the molded product. It is formed. Each molding surface 1) a, 12a has a surface roughness R
The molding surfaces 1)a and 12a are coated with a film of chromium nitride, titanium nitride, boron nitride, etc..

The atmosphere in the molding chamber 2 is maintained such that the 02 concentration is 1% or less, and the glass and mold 1) during molding of the preform 3 are maintained at a concentration of 1% or less. This reduces the reactivity with 12.

The preform 3 is carried into the molding chamber 2 from the carry-in port 4 via the preform transfer mechanism section 20, and passes between each block section 6, 7, 8, and 9, and is transferred from the carry-out port 5 to the molding chamber 2. It is being carried outside. Transport mechanism section 20
is an arm 21 for holding and transporting the preform 3;
, an arm drive mechanism 22 for moving the arm 21 in the vertical direction in FIG. 2, that is, the same direction as the molding direction of the mold 1) 12; The arm drive head 23 and the arm drive mechanism 22 are moved and driven via the guide rail 24 and the arm drive head 23 is moved and driven via the guide rail 24. It is composed of a moving table 25 that is guided to move in a direction parallel to the line connecting the outlet 5, and a table moving section 26 for moving the moving table 25. Arm 21
has a bifurcated arm holding portion 21a at its tip, and a groove 27 for holding the preform 3 is formed in this arm holding portion 21a. The rail 24 is disposed on the side surface of the molding chamber 2, and its length is set to be an appropriate amount longer than the length of the molding chamber 2. It is composed of a wire 32 wound between a drive pulley 30 fixed to a drive shaft 29 and a driven boob IJ 31, and the wire 32 is fixed to the movable table 25. Note that the arm 21 is preferably coated with a nitride such as titanium nitride (TiN), chromium nitride (CrN), or boron nitride (BN) in order to reduce wetting with glass.

Next, in the manufacturing apparatus 1, a lens/lens (optical element) is manufactured.
The method of manufacturing will be explained.

First, the press lens 3 is held by the arm 21. This setting operation is performed outside the entrance 4 in the molding chamber 2.

Next, the preform 3 is carried into the molding chamber 2 via the preform transfer mechanism 20, and the heating block 6
．． It will be transferred for 7 hours and then stopped.

Next, the arm 21 is moved upward via the arm drive mechanism 22, and the preform 3 is brought into contact with the heat transfer member 6a of the stationary side heating block section 6 and stopped.

Next, the movable heating block section 7 is moved upward to bring the heat transfer member 7a of the movable heating block section 7 into contact with the preform 3 and then stopped.

In the above steps, the preform 3 is formed into both heat transfer members 6a and 7.
Heat is transferred from a and heated. In this case, the temperature of each heating block section 6, 7 and the contact time with the preform 3 are controlled so that the viscosity of the preform 3 is 109 to 10' poise. This temperature and time depend on the size and shape of the preform 3, but each heat transfer portion 5a, 7a
The preform 3 can be heated by setting the temperature to a temperature corresponding to the viscosity of the preform 3 of IO 9 to 105 poise and setting the time to about 2 to 15 seconds.

When the heating of the preform 3 is completed, the heating block section 7
At the same time, the arm 21 is also moved downward.

Next, the preform 3 is transferred between the mold block sections 8 and 9 via the preform transfer mechanism section 20 and stopped.

Next, the arm 21 is moved upward and stopped when the preform 3 contacts the molding surface 1) a of the mold 1). Subsequently, the mold block 9 is moved upward to bring the molding surface 12a of the mold 12 into contact with and press the preform 3, thereby press-molding the preform 3.

When the press molding is completed, the mold block 9 is moved down, and then the arm 21 is moved down.

Arm 2 holds the press lens, which is a molded product.
1 is carried out and transferred to the outside of the molding chamber 2 via the carrying out port 5.

With the above steps, the process of manufacturing a press lens is completed.

As described above, according to this embodiment, the heating time of the preform 3 by heat conduction is about 2 to 15 seconds, and moreover, heating and molding can be performed within a short time in the molding chamber 2, so that the manufacturing process The time required for this can be significantly shortened.

Furthermore, as is clear from the simulation results shown below, the bending during heating of the preform 3 can be eliminated and the moldability can be improved. That is, according to the heating method as shown in the prior art, the viscosity of the glass preform 3 decreases as the temperature rises, causing warping as shown in FIG. Note that FIG. 4a shows the preform 3 before heating. If molding is continued in this state, a large amount of heat will be absorbed by the mold the moment the glass preform 3 comes into contact with the mold, the viscosity of the glass preform 3 will instantly increase, and the glass becomes solidified. When this is simulated through numerical calculations, the result is shown in Figure 5.As shown in the simulation results shown in the figure, the temperature of the glass preform drops rapidly, and the solidification of the glass progresses rapidly within a few seconds. Recognize. Note that this simulation was conducted under conditions of a mold temperature of 340°C and a preform temperature of 590°C.

In this example, since the shape of the preform 3 is maintained in a predetermined shape during heating and no bending occurs,
The amount of deformation during molding is small, so press molding from an optimal heated preform shape is possible. As a result, there is an advantage that the inversion of the mold shape can be completed in a short time, no inversion failure occurs, and the molding conditions can be set at a lower temperature.

Note that the shape of the heat transfer section 6a of the heating block section 6.7 for heating the glass preform 3 in the above embodiment is the same as that of the mold 1). The molding surfaces 1)a and 12a of No. 12 may be formed in a shape similar to that of the molding surfaces 1)a and 12a. According to such a configuration, the amount of glass flow during molding can be reduced, and pressing work with good reversibility can be performed in a shorter time.

〔Effect of the invention〕

As described above, according to the present invention, since the preform is heated by thermal conduction, the preform can be heated in a short time, and the manufacturing time of the optical element can be extremely shortened. Furthermore, since the preform is not deformed during heating, press molding can be realized from an optimal heated preform shape with a small amount of deformation during molding, and good reversibility can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a conceptual diagram of the present invention, FIG. 2 is a front sectional view showing one embodiment of the present invention, FIG. 3 is a plan view of the main part of FIG. 2, and FIG.
Figures a, b, and 5 are explanatory diagrams for explaining the effects of this embodiment. 2...Molding chamber 3...Preform 6.7...Heating block parts 5a, 7a...Heat transfer part 8.9...Mold block part 1). 12...Molding mold 1)a, 12a...Molding surface -'knee'2・Figure 1 1)a, 12a...Molding surface

Claims (3)

[Claims] (1) The glass preform is brought into contact with a heated heating block and heated to a predetermined temperature, and then the heated glass preform is transferred between molds and press-molded into a predetermined shape. A method for manufacturing an optical element. (2) A heating block that can freely contact the glass preform, is temperature controllable, and has a pressurizing means, and molding for press-molding the glass preform heated to a predetermined temperature via the heating block. 1. An optical element manufacturing device characterized by comprising a mold. (3) The optical element manufacturing apparatus according to claim 2, wherein the heating block is formed so that its heating surface shape approximates the shape of the molding surface of the mold.