JPH08208244A - Apparatus for forming optical element - Google Patents

Abstract

PURPOSE: To provide the subject apparatus capable of producing a lens in a short cycle time even with a simple structure and effectively preventing the generation of differences in level, creased irregularity, etc. CONSTITUTION: This apparatus is provided with a pair of an upper and a lower molds 1, 2 placed in a sleeve 3, a nozzle 7 placed in a manner capable of freely moving in forwarding and retreating directions from the lateral side of the sleeve 3 into a space between the both molds 1, 2 and capable of supplying fused glass dropwise onto the lower mold 2 and a sensor 10 for detecting the dropping of the fused glass from the nozzle 7.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical glass element molding apparatus for directly pressing molten glass with a molding die to obtain optical elements such as lenses and prisms.

[0002]

2. Description of the Related Art Conventionally, as this type of molding apparatus, for example, the apparatus disclosed in Japanese Patent Laid-Open No. 3-45523 is known. In this apparatus, as shown in FIG. 4, after the molten glass 20 is received by the first heat processing jig 21, it is attached to the second heat processing jig 22, inverted, and reheated to make the first glass. The step generated when received by the thermal processing jig 21,
After removing the wrinkles, press molding is performed by the molding die 23.

[0003]

However, in the above-mentioned prior art, the process is complicated such that the molten glass is received by the first heat processing jig and then inverted by the second heat processing jig.
There are problems that the molding apparatus becomes complicated, the cycle time is long, and the manufacturing cost of the lens is high.

The present invention has been made in view of the above-mentioned problems, and it is possible to manufacture a lens with a simple structure in a short cycle time and effectively prevent the occurrence of defects such as steps and wrinkles. An object is to provide a glass element molding device.

[0005]

In order to achieve the above object, an optical glass element molding apparatus of the present invention comprises a pair of upper and lower molds provided in a sleeve and at least one of which is vertically movable. It is composed of a nozzle that is provided so as to advance and retreat from the side of the sleeve toward the upper and lower molding dies and that supplies molten glass to the lower mold by dripping, and a sensor that detects that molten glass has been dripped from the nozzle. It

In this case, as described in claim 2, it is preferable that the lower die of the forming dies is provided so as to be able to move up and down, and the molten glass is dropped onto the lower die during the upward accelerating motion.

[0007]

In the optical glass element molding apparatus of the present invention having the above structure, the molten glass is pressed and spread before it cools and hardens, so that the molten glass cools and hardens from the point of contact with the mold. The occurrence of so-called steps and wrinkles is prevented. Moreover, the molding cycle time of the glass element can be shortened.

When the molten glass is dripped into the lower mold during the upward acceleration motion, a downward inertial force acts on the molten glass, and the flattened before press molding. Since it spreads over, the occurrence of steps and wrinkles can be prevented more effectively.

[0009]

Embodiments of the optical glass element molding apparatus according to the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a sectional front view showing an optical glass element molding apparatus.

Reference numeral 1 is an upper die, and 2 is a lower die, both of which are of chromia cylindrical shape, and the opposite end surfaces are mirror-finished to a molding surface which is the inverted lens shape. A hollow cylindrical sleeve 3 is provided so as to surround the upper mold 1 and the lower mold 2, and has a window 3a on its side wall for supplying molten glass and taking out a molded product. Further, a driving means (not shown) for independently raising and lowering the upper die 1 and the lower die 2 is additionally provided. Reference numeral 4 denotes a heating coil arranged on the outer circumference of the sleeve 3, which heats the upper die 1 and the lower die 2 through the sleeve 3.

Reference numeral 5 denotes a crucible arranged on the side of the sleeve 3, which is movable left and right so as to come into contact with and separate from the sleeve 3, is made of a platinum material, and has a heating coil on the outer periphery. 6 is attached. Reference numeral 6 denotes a tubular nozzle provided through the bottom surface of the crucible 5, and is movable left and right integrally with the crucible 5. At the left end position of the crucible 5, the tip of the nozzle 6 opens the window 3a. It passes through to the center axis of the lower mold 2, and the nozzle 6 retreats to the side of the sleeve at the right end position. Reference numeral 8 denotes a plunger provided on the bottom of the crucible 5 so as to be vertically movable, and controls the flow of the molten glass discharged and supplied from the nozzle 6. A motor 9 moves the crucible 5 to the left and right.

Reference numeral 10 denotes a molten glass 11 from the tip of the nozzle 6.
This is a reflected light type sensor that detects that the ink has been dripped, and is attached to the side surface of the sleeve 3 and is disposed directly below the tip of the nozzle 6. Reference numeral 12 denotes a control device incorporating a microcomputer, which receives a signal from the sensor 10 to drive and control the motor 9 to move the crucible 5 to the left or right and to control the opening / closing operation of the plunger 8. Further, the up-and-down control of the upper die 1 and the lower die 2 is also performed.

Next, the operation of the optical glass element molding apparatus of this embodiment having the above construction will be described.

First, the upper mold 1 is moved to the upper end in the sleeve 3, the lower mold 2 is moved to the lower end, and the crucible 5 is moved to the left end position to stand by. The heating coil 4 is energized to heat the upper die 1 and the lower die 2 to a temperature corresponding to a glass viscosity of 10 ^11.5 to 10 ¹⁴ poises. Further, the heating coil 6 is energized to heat and melt the molten glass 11 in the crucible 5 to 10 to 10 ^2.5 poise. At this time, the plunger 8 is in a closed state.

Next, the plunger 8 is opened and one drop of molten glass is dropped from the tip of the nozzle 6. The dropping of the molten glass is detected by the sensor 10 and input to the control device 12.

The controller 12 immediately closes the plunger 8, moves the crucible 5 to the right, and raises the lower mold 2.
These three operations are performed almost at the same time, and in this embodiment, the time from the drop of the molten glass on the surface of the lower mold 2 to the press molding with the upper mold 1 is 0.8 seconds or less.

At this time, the molten glass is dropped upward while colliding with the lower mold 2 during acceleration, and thereafter, the molten glass is accelerated together with the lower mold 2 in an upward motion. Therefore, a downward inertial force acts on the molten glass, and when it is press-molded with the upper mold 1, the molten glass is in a flatly spread state, which suppresses the occurrence of steps or wrinkles during pressing. be able to.

After press molding, the viscosity of the molded product is 10 ¹⁴
The mold is slowly cooled to the poise level, the upper mold 1 and the lower mold 2 are lowered, and the molded product is taken out from the window 3a.

(Modification)

The present invention is not limited to the above embodiment, but may be modified to perform the following operations, for example. That is, although the lower mold 2 is controlled to be raised after the dropping of the molten glass is detected in the above embodiment, the upper mold 1 may be controlled to be lowered as shown in FIG. In this case, the upper mold 1 and the lower mold 2 are raised when the molded product is taken out from the window 3a.

[0022]

As described above, according to the optical glass element molding apparatus of the present invention, after the molten glass is detected to drop, the mold is immediately moved to perform the press molding, so that the molten glass is pressed before it becomes cold and hard. It is molded, and steps and wrinkles are prevented from occurring. Moreover, the molding work can be performed in the shortest cycle time.

When the molten glass is dripped in the lower mold during the upward acceleration motion, a downward inertial force acts on the molten glass to flatten it before press molding. Since it spreads over, the occurrence of steps and wrinkles can be prevented more effectively.

[Brief description of drawings]

FIG. 1 is a sectional front view showing a state before molten glass dropping in an optical glass element molding apparatus according to an example of the present invention.

FIG. 2 is a sectional front view showing a state during press molding in the optical glass element molding apparatus according to the embodiment of the present invention.

FIG. 3 is a sectional front view showing a state during press molding in another example of the operation of the embodiment of the present invention.

FIG. 4 is a sectional front view schematically showing a conventional optical glass element molding device.

[Explanation of symbols]

 1 Upper Mold 2 Lower Mold 3 Sleeve 4 Heating Coil 5 Crucible 6 Heating Coil 7 Nozzle 8 Plunger 9 Motor 10 Sensor 11 Molten Glass 12 Control Device

Claims (2)

[Claims] 1. A pair of upper and lower molds disposed in a sleeve, at least one of which is vertically movable, and a lower mold which is provided from the side of the sleeve so as to be movable back and forth between the upper and lower molds. An optical glass element molding apparatus comprising: a nozzle for dropping and supplying molten glass to a mold; and a sensor for detecting that molten glass has been dropped from the nozzle. 2. The optical glass element molding apparatus according to claim 1, wherein the lower mold of the molding dies is provided so as to be able to move up and down, and the molten glass is dropped onto the lower mold during upward acceleration motion. .