JPH08208248A - Glass lens and formation of the lens - Google Patents

Abstract

PURPOSE: To enable the production of a lens free from the deterioration of its surface accuracy attributable to sink marks formed during molding even in the case of a large variance in a thickness, a large diameter, etc., of the lens and also free from differences in level on one side of a lens at a low cost by making the lens having a forming surface molded of a fused glass on one side and a polished surface by grinding and polishing on the other side. CONSTITUTION: A receiving mold 26 is placed in a basket 18 of a centrifugal forming apparatus 1. A rotary shaft 15 having a balance weight 20 is manually rotated and the receiving mold 26 is moved to directly below the central shaft (b) of a nozzle 6. Subsequently, a heater 29 is risen and the receiving mold 26 is heated to a temperature between the glass transition temperature and the glass softening point of a glass material. Then, the homogeneous hot-fused glass material free from foams and having a viscosity of <=10 poise is added on the center of a receiving surface 26a of the receiving mold 26 dropwise from the nozzle 6 to form a spherical glass gob 28. According to signals, the heater 29 is lowered, the rotary shaft 15 is driven by a motor 15 and the glass gob 28 is made flat in a vertical direction under close contact with the receiving surface 26a by the centrifugal force. The opposite side of the single- surface forming lens is subjected to CG processing, grinding and then polishing.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a glass lens used as an optical element and a method for molding the glass lens.

[0002]

2. Description of the Related Art Conventionally, in molding a lens using a mold, it is necessary to use a molding material which has a mirror-finished state without defects such as bubbles or scratches.
Molded lenses have become very expensive. Therefore,
As a manufacturing apparatus for reducing the cost of molded lenses, for example, the invention described in Japanese Patent Application Laid-Open No. 2-225324 has been proposed.

In the above invention, as shown in FIGS. 11a, 11b, 11c, and 11c, a receiving die 201, a crucible 202 for supplying glass to the receiving die 201, and a heater for heating the glass in the crucible 202. 203, a heater 204 for heating the glass supplied to the receiving mold 201, and an upper mold 205. After melting the glass in the crucible 202 and dropping the glass into the receiving mold 201 (Fig. 11a). ), The upper surface of the glass is heated again by the heater 204 (see FIG. 11b), and then pressed by the upper mold 205 (see FIG. 11).
(see c) to mold the lens.

According to the apparatus having the above-mentioned structure, after the glass is dropped on the receiving mold 201, the upper surface of the glass is heated again by the heater 204, so that the stringing or the like on the upper surface of the lens generated at the time of dropping can be eliminated, and the lens is inexpensive. Can be manufactured.

[0005]

However, in the above-mentioned prior art, in the case of manufacturing a lens having a large thickness deviation and a large outer diameter, there is a drawback that the surface accuracy is deteriorated by the sink marks generated when the glass is cooled during the molding. there were. In addition, the surface of the receiving mold has a difference in viscosity between the glass that first comes into contact with the receiving mold and the glass that comes into contact with the receiving mold at the time of dripping. There was a drawback that it occurred.

The object of claims 1 and 2 is to provide an inexpensive glass which does not cause deterioration of surface accuracy or a step on one side of the lens due to a sink mark generated by molding even if the thickness deviation, the outer diameter and the like are large. A lens and a method for manufacturing the same are provided.

It is an object of claims 3 and 4 to provide a method of manufacturing a glass lens in which the surface accuracy of one surface is extremely high and a mold is required only on one surface.

An object of claim 5 is to provide a glass lens manufacturing method for manufacturing a cheaper glass lens with an inexpensive device.

[0009]

According to a first aspect of the present invention, one surface is a molding surface obtained by molding molten glass, and the other surface is a polishing surface obtained by grinding and polishing. Is a glass lens.

According to a second aspect of the present invention, a step of molding molten glass with a molding die to transfer one surface and a step of grinding the other surface
And a step of polishing and polishing to a desired curvature.

According to the invention of claim 3, in the step of molding the molten glass with a molding die and transferring one surface, the molding die supplied with the molten glass is moved toward the supplied molten glass side. The method for molding a glass lens according to claim 2, wherein the molding is performed on one side.

According to a fourth aspect of the present invention, in the step of molding the molten glass with a molding die and transferring one surface, the molding die supplied with the molten glass is rotationally moved, and one surface is molded by centrifugal force. The method of molding a glass lens according to claim 2, wherein

According to a fifth aspect of the present invention, in the step of molding the molten glass with a molding die and transferring one surface thereof, after the molten glass is supplied onto the receiving mold, the upper surface of the molten glass is molded with the upper die. The method of molding a glass lens according to claim 2, wherein the glass lens is transferred.

[0014]

The effects of claims 1 and 2 are that by forming one side directly from molten glass and forming the other side by grinding and polishing, defects (sinks, steps, wrinkles, etc.) associated with the forming are formed. Concentrate on the polishing surface.

The function of the third aspect is to drop the molten glass into the mold and then quickly move the mold toward the molten glass to bring the molten glass into close contact with the mold.

The operation of claim 4 is to drop the molten glass on the molding die, and then rapidly rotate the molding die to bring the molten glass into close contact with the entire surface of the molding die by centrifugal force.

According to the operation of claim 5, the surface formed by the upper die is left as it is, and the surface formed by the receiving die having a step is ground.
It is to be polished. Since the upper surface of the molten glass has a low cooling effect from the receiving mold and the solidification rate is moderated, it is possible to closely transfer the image.

[0018]

Embodiment 1 FIGS. 1 to 4 show the present embodiment, FIG. 1 is a vertical sectional view of a centrifugal molding apparatus, and FIGS. 2 and 3 are sectional views of essential parts.
4A to 4C are process diagrams. 1 is a centrifugal molding device,
The centrifugal molding apparatus 1 includes a glass raw material melting section 2 that heats and melts glass raw materials, a centrifugal molding section 3 that performs molding by rotating a receiving mold into which molten glass has been injected, and a discharge unit 4 that takes out the molded glass. It consists of

The glass raw material melting part 2 has a crucible 5, a nozzle 6 connected to the bottom surface of the crucible 5, and the crucible 5 having a glass viscosity of 10 poise or less (usually 1000 ° C. to 18 ° C.).
High frequency heating coil for crucible 7 for heating to 00 ° C)
And a nozzle high-frequency heating coil 8 for heating the nozzle 6 to a temperature of about 10 poise (usually 1000 ° C. to 1600 ° C.) with a glass viscosity. Then, below the nozzle 6, a photo sensor 49 for detecting the timing of dropping the molten glass dropped from the nozzle 6 is installed. The glass raw material melting section 2 is fixed to the frame 9 of the centrifugal molding apparatus 1 via an arm 10.

The centrifugal molding unit 3 is composed of a centrifugal rotating unit 11 and a receiving type heating unit 12. The centrifugal rotating unit 11 is
A bearing 14 fixed to a base 13 of the centrifugal molding apparatus 1,
A rotating shaft 15 rotatably erected on the bearing 14, a rotating arm 16 attached to the rotating shaft 15, and a rotating arm 1
6, a bucket 18 rotatably supported around a support point O via a support arm 17, a rotary arm 19 mounted on the opposite side of the rotary shaft 16 to the rotary shaft 15, and a rotary arm 19 A balance weight 20 attached to the tip of the rotary shaft 15, and a slit plate 21 fitted in an intermediate portion of the rotary shaft 15 and having a slit formed in a part thereof,
It is composed of a photo sensor 22 that can detect the slit of the slit plate 21 in a non-contact state, a pulley 23 that is fitted in the lower portion of the rotating shaft 15, and a controllable motor 25 that supplies power to the pulley 23 via a belt 24. ing.

The motor 25 is constructed so as to rotate upon receiving a signal from the photosensor 49 for detecting the dropping. The central axis a of the bucket 18 when the rotary shaft 15 is stopped is in a positional relationship such that it coincides with the central axis b of the nozzle 6 of the glass raw material melting portion 2.

As shown in FIG. 2, the bucket 18 has a bottomed cylindrical shape, and a receiving die 26 is inserted into the inner peripheral surface 18a thereof. The receiving mold 26 has heat resistance and mirror surface workability,
And a material having low reactivity with molten glass, such as AlN,
It is made of a sintered body such as BN and CR ₂ O ₃ or a cemented carbide or the surface of the sintered body which is coated with AlN, BN, CR ₂ O ₃ , CrN and noble metals. The receiving surface 26a of the receiving die 26 is formed to have a curvature of a molded lens, and is mirror-finished to have a surface roughness Rmax of less than 0.1 μm.

A transport member 27 for transporting glass is fitted into the outer peripheral portion 26b of the tip of the receiving mold 26. Transport member 2
The material 7 may be a material having heat resistance and low reactivity with molten glass, for example, a material similar to that of the receiving mold 26 or a material having a slightly inferior denseness. The inner peripheral portion 27a of the conveying member 27 has a desired lens outer diameter. 28 is a glass gob supplied from the nozzle 6 onto the receiving mold 26a.

The receiving type heating section 12 has a heater 29.
And an elevating mechanism 30 that is fixed to the base 13 and supports the heater 29 so that the heater 29 can move up and down.
The heater 29 is located directly below the central axis a, and when the bucket 18 is in a stopped state when it rises, the bucket heater 18 has a glass transition point temperature or higher and a glass softening point temperature or lower (normally 500 ° C. to 800 ° C.). ) Can be heated to.

The discharge unit 4 is composed of a discharge arm 31 attached to a drive mechanism (not shown) and a claw 32 fixed to the tip thereof. The discharge unit 4 has the claw 3
At 2, it is possible to take out the conveying member 27 fitted in the receiving mold 26 and discharge it to the outside of the centrifugal molding apparatus 1, and to feed another conveying member 27 by fitting it in the receiving mold 26. It is configured.

In the centrifugal molding apparatus 1 having the above structure, first, the receiving mold 26 is set in the bucket 18, and the balance weight 20 having a weight balanced with the receiving mold 26 is set at the tip of the rotating arm 19. Then, rotate the rotary shaft 15 manually,
The receiving mold 26 in the bucket 18 is moved right below the central axis b of the nozzle 6 and positioned so as to receive the molten glass falling. At this time, the slits formed in the slit plate 21 are detected by the photosensor 22 and LE
By illuminating D, it is possible to know that the predetermined position has been reached.

Next, the receiving die heating section 12 is raised to bring the receiving die 26 to the glass transition temperature or higher and the glass softening point temperature or lower by the heater 29. Then, a glass material is put into the crucible 5 and heated by the high-frequency heating coil for crucible 7 to have a glass viscosity of 10 poise or less and melted. After the molten glass is in a homogeneous and bubble-free state, the nozzle high-frequency heating coil 8 heats the nozzle 6 to adjust the glass viscosity to about 10 poise suitable for dropping and separating, and the molten glass droplet from the tip of the nozzle 6 is adjusted. Is dripped.

The molten glass dropped from the tip of the nozzle 6 drops onto the center of the receiving surface 26a of the receiving die 26 and becomes a spherical glass gob 28 (see FIG. 2) due to surface tension. When the glass gob 28 is dropped on the receiving surface 26a, the heater 2 receives the signal from the photo sensor 49.
9 descends, and immediately the motor 25 starts to rotate. As a result, the receiving mold 26 and the glass gob 28 in the bucket 18 both rotate around the rotation shaft 15. Due to the centrifugal force generated at this time, the bucket 18 is brought into a horizontal state, and the glass gob 28 is flattened in the vertical direction while being in close contact with the receiving surface 26a of the receiving die 26 (see FIG. 3).

At the time of molding, the glass gob 28 transfers heat to the receiving mold 26, but since the receiving mold 26 has been heated in advance and the other surface is only in contact with the atmosphere, the heat transfer is slow and the viscosity is low. Can be maintained for a long time. Therefore, one surface of the glass gob 28 that receives the centrifugal force is the receiving surface 26a.
And the other surface is flattened against the surface tension, and the inner peripheral portion 2 of the conveying member 27
While being molded until it comes into contact with 7a, it is solidified and the single-sided molding is completed.

The molding conditions are such that the centrifugal force is changed depending on the number of rotations of the motor 25 and the length of the rotating arm 16, or the glass gob 28 is heated by the heating temperature of the receiving mold 26 or temperature control means.
It is appropriately determined by changing the cooling rate of.

After the molding is completed, the motor 25 is stopped and the bucket 18 is stopped at the initial position. Then, the discharge arm 31
Is moved forward to position the claw 32 on the outer periphery of the conveying member 27 on the receiving mold 26, moves upward, picks up the conveying member 27 from the receiving mold 26, then moves backward, and is discharged to the outside of the centrifugal molding apparatus 1. When the molding is repeated again, another conveying member 27 is supplied onto the receiving mold 26 by the discharging unit 4 and the above operation is repeated. The single-sided lens thus obtained has a polishing surface 33b on the free surface side as shown in FIGS.
The glass lens 33 is completed by subjecting the (almost flat shape) to CG processing (spherical surface generation processing, see FIG. 4b) and grinding / polishing processing (see FIG. 4c).

As described above, one surface is the molding surface 33a obtained by molding molten glass, and the other surface is the polishing surface 33b obtained by grinding and polishing.
3 can be processed. The molding surface 33a is obtained by transferring the molten glass to the molding die surface. Therefore, the transfer of the molding die (grinding traces) and minute deposits are recognized, but minute scratches such as polishing scratches and latent scratches are not recognized.
On the other hand, the polishing surface 33b has a feature that polishing scratches and latent scratches peculiar to the profile processing are recognized.

According to this embodiment, since only the molding surface is molded on one side, the solidification rate of the glass is moderated, and the molten glass is pressed against the mold by centrifugal force, so that extremely high surface accuracy can be obtained. Moreover, since only one mold is required, the cost of the mold can be reduced.

[0034]

[Embodiment 2] FIGS. 5 and 6 show the present embodiment, FIG. 5 is a longitudinal sectional view of a molding apparatus, and FIGS.
In the present embodiment, the same components as those in the first embodiment are designated by the same reference numerals and the description thereof will be omitted.

The molding apparatus 50 is provided with a glass blow-out chamber 52, a wall 55 on the right side thereof, a press chamber 53, and a holding member 72 provided on the left side of the glass blow-out chamber 52 to convey the holding member 72 into the glass blow-out chamber 52. The holding member supply arm 51 configured as described above and the holding member 7 provided on the right of the press chamber 53.
The discharge arm 31 is configured to carry out 2 from the press chamber 53, and the crucible 5 provided above the glass blowing chamber 52.

The crucible 5 has a nozzle 6 at the center thereof.
Thus, the molten glass 62 can be supplied into the glass blowing chamber 52. Further, a crucible high-frequency heating coil 7 is wound around the outer peripheral surface of the crucible 5, and the molten glass 6
2 can be controlled to a predetermined temperature. The blowout hole 63 installed on the surface of the crucible 5 can be opened and closed by a plunger 64 which can be moved up and down by a driving means (not shown). Further, a nozzle high-frequency heating coil 8 for constantly maintaining the molten glass 62 at a predetermined temperature is also wound on the outer peripheral surface of the nozzle 6.

In the glass blowing chamber 52, a columnar shaft 65 is vertically arranged at a position directly below the nozzle 6 of the crucible 5 so as to be vertically movable by bearings 66 and 67 by driving means (not shown). Has been done. This shaft 6
A column-shaped receiving die 26 having a heater 68 wound around the outer peripheral surface thereof is detachably installed on the upper end surface of 5. An upper end portion of the receiving mold 26 is configured so that a ring-shaped holding member 72 conveyed by a holding member supply arm 51 described later can be detachably mounted. An opening 54 for loading the holding member supply arm 51 for loading the holding member 72 from the outside is formed at an intermediate position of the wall 74,
A shutter 58 is installed in the opening 54.

The tip of the holding member supply arm 51 is formed in a U-shape having a size and shape corresponding to the outer peripheral surface of the holding member 72, and the holding member 72 is fitted and attached for conveyance. The holding member 72 has a flange portion 69 formed on the outer peripheral surface of the upper end thereof, and the inner peripheral surface 72a is formed with an inner diameter corresponding to the outer peripheral dimension of the lens to be molded. Further, at the intermediate position thereof, the upper end surface 26a of the receiving mold 26 is
The stepped portion 70 is formed so as to protrude within a range that does not interfere with the approximated lens forming surface.
On the lower end surface of 0, a fitting portion having a dimension corresponding to the outer diameter dimension of the receiving die 26 is formed.

The tip surface 26a of the receiving mold 26 is formed into a shape surface close to the final shape of the glass optical element to be molded. Its surface 26a, in order to prevent fusion of the molten glass, CrN, thin film of poor wettability substance is coated against Cr ₂ O _3, TiN and the molten glass, such as C-BN. At a position below the wall 74, there is formed a gas introduction port 60 connected to an external gas supply means (not shown) for introducing a non-oxidizing gas into the room.

An opening 56 and a shutter 59 having the same structure as the opening 54 and the shutter 58 formed in the wall 74 are provided in the partition wall 55 adjacent to the glass discharge chamber 52, that is, the partition wall 55 with the precision press chamber 53. Is formed at the same horizontal position as the upper end surface 26a of the. A similar opening 75 and a shutter 86 are arranged in the wall 75 at the same position as the partition wall 55, and the discharge arm 31 for transporting the molded lens 76 to the outside is configured to be able to go in and out through the opening 57. ing. In order to introduce the non-oxidizing gas into the room, a gas introduction port 61 connected to a gas supply means (not shown) provided outside is formed below the wall 75.

A mount 82 is provided at the center of the upper wall of the press chamber 53. On the lower end surface of the mount 82, a cylindrical upper mold 84 is provided, the base end portion of which is detachably formed. A heater 83 for controlling the temperature of the upper die 84 to a predetermined value is wound around the outer periphery of the upper die 84. The molding surface 84a of the upper mold 84 is precisely formed in a shape corresponding to the final shape of the molded lens. Further, in order to prevent fusion with the heat-softened glass, CrN, Cr ₂ O ₃ , TiN and C are formed on the surface of the molding surface 84a.
-A thin film of a substance having poor wettability is coated on the heat-softened glass such as BN.

On the outer peripheral surface of the mount 82 on which the upper die 84 is mounted, vertical sliding (arrow) is performed by a driving means (not shown).
A ring-shaped release member 85 that is freely configured is fitted. On the inner peripheral edge of the tip (lower end) of the release member 85, there is formed a protrusion whose front end surface facilitates abutting against the flange 69 of the holding member 72 when descending. When the molded lens is molded by the molding die, the release member 85 starts to descend almost simultaneously with the lowering operation of the lower die 81, and its tip end surface abuts against the upper surface of the flange portion 69 of the holding member 72 to press it. Molding surface 84a and molding lens 76
It is automatically controlled so as to release from the optical surface of the upper surface of. The molded lens 76 that has been released from the mold is configured to be released along with the holding member 72 onto the discharge arm 31 and drop.

A cylindrical shaft 77 is erected at a lower position facing the molding surface 84a of the upper mold 84, and bearings 78 and 79 are arranged between the base end portion and the base to drive the shaft. As shown by the arrow, it is configured to be movable in the vertical direction by means (not shown). A cylindrical lower die 81 is detachably attached to the upper end surface of the shaft 77. A heater 80 for controlling the temperature of the lower die 81 at a predetermined value is wound around the outer peripheral surface of the lower die 81.

The upper end surface 81a of the lower mold 81 is formed in a shape close to the final shape of the molded lens (corresponding to the curvature to be ground / polished later), and the molten glass 73 in the holding member 72 is sandwiched between the predetermined shape. It is configured to apply a pressing pressure. To the surface of the upper end surface 81a to prevent fusion of the glass that is heated and softened, CrN, Cr ₂ O _3, relative to the heat-softened glass, such as TiN and C-BN of poor wettability substance The thin film is coated. Discharge arm 31
The holding member supplying arm 51 has the same structure as the holding member supplying arm 51 and can convey the holding member to the glass blowing chamber 52, the press chamber 53 and the outside.

The manufacturing method of this embodiment having the above structure will be described below. First, in order to maintain the inside of the molding apparatus 50 in a non-oxidizing atmosphere, nitrogen gas is introduced from the gas introduction ports 60 and 61 of the glass blowing chamber 52 and the press chamber 53. Then, the glass raw material stored in the crucible 5 is heated by the high frequency heating coil 7 and melted until the glass viscosity becomes 10 ³ poise. Further, the receiving mold 26 in the glass blowing chamber 52 is previously prepared.
The temperature is maintained at a temperature lower than the glass transition point by about 50 ° by the heater 68 by the control means.

Next, the holding member supply arm 51 on which the holding member 72 is mounted is stopped on the receiving mold 26 in the glass blowing chamber 52 through the opening 54 of the wall 74. Thereafter, the shaft 65 is moved up to fit the upper end of the receiving die 26 with the lower end of the holding member 72, and the holding member 72 is mounted on the receiving die 26. On the upper surfaces of the holding member 72 and the receiving mold 26,
The preforming step is started by raising the plunger 64 provided in the crucible 5 and discharging the molten glass 62 by a predetermined amount. During the above-described operation process, the discharging arm 3 in which the holding member 72 is carried and mounted on the receiving mold 26 in the glass blowing chamber 52.
1 is evacuated to the outside and is prepared to carry and carry the next new holding member 72. This completes the process of supplying and conveying the holding member 72.

In the preforming step, the discharge glass 73 discharged onto the receiving mold 26 and the holding member 72 has the upper end surface 2 of the receiving mold 26 on which the holding member 72 is mounted in advance.
While being gradually cooled in the central portion of 6a, it gradually spreads outward due to its own weight. In this embodiment, when the discharge glass 73 is discharged onto the holding member 72 and the receiving mold 26, the discharge arm 31 is actuated to enter the glass blowing chamber 52 and the position below the flange portion 69 of the holding member 72. Stop at. At this time, the discharge glass 73 spreads and contacts the inner peripheral surface 72a of the holding member 72 while being cooled, and is formed into a constant shape. After that, by lowering the shaft 65, the blown glass 73 is caught by the stepped portion 70 of the holding member 72, and the flange portion 6 of the holding member 72 is held.
When 9 comes into contact with the discharge arm 31, the discharge glass 73 is released from the receiving mold 26, and the preforming step is completed.

Holding member 7 on which the discharge glass 73 is mounted
2 is conveyed to the press chamber 53 by retreating the discharge arm 31. At this time, the upper mold 84 and the lower mold 81 are controlled to have a constant temperature near the glass transition point. continue,
When the lower die 81 is raised, the molding surface 81a of the lower die 81 is inserted into the inner diameter of the lower end portion of the holding member 72 and comes into contact with the holding member 72 and the discharge glass 73. Further, when the lower die 81 is moved upward, the lower die 81 lifts the holding member 72 so that the molding surface 84a of the upper die 84 and the surface of the ejection glass 73 to be molded come into contact with each other, and the ejection glass 73 is 184 kg / cm.
Press molding is performed by applying a pressure of ² and holding for 20 seconds. The upper surface of the discharge glass 73 has a low cooling effect from the receiving mold 26 and the solidification rate is moderated, so that the transfer can be performed in close contact.

After the press molding, the shaft 77 is moved down and the release member 85 provided on the outer periphery of the upper die 84 is also moved down to release the molded lens 76 from the upper die 84 and eject the discharge arm 31. The pressing process is completed by mounting the product on the tip of the and collecting it. When the molded lens 76 is in close contact with the upper mold 84, the mold release member 85 causes the holding member 72 to move.
The upper surface of the flange portion 69 is abutted and released. Further, when it comes into close contact with the lower mold 81, the flange portion 69 of the holding member 72 comes into contact with the discharge arm 31 to release the mold. The holding member 72 and the molded lens 76, which are released from the mold and mounted in the tip of the discharge arm 31,
Is transported to the outside of the molding apparatus 50 and gradually cooled.

In the molded lens 76 composed of the upper mold molding surface 76a and the lower mold molding surface 76b obtained as described above, defects (sinks, steps, wrinkles, etc.) due to molding are generated in the lower mold molding surface 76b. There is. Therefore, as shown in FIGS.
The lower mold surface 76b is subjected to CG processing (spherical surface generation processing, see FIG. 6b) and grinding / polishing processing (see FIG. 6c) to complete a lens. The amount cut by CG processing is smaller than that in the first embodiment.

According to this embodiment, the apparatus can be downsized as compared with the centrifugal molding machine. Also, the CG of the surface to be ground / polished
The cutting amount of machining (spherical surface machining) is reduced, and the machining time can be shortened. Further, when the wrinkles are shallow, the CG process can be omitted and the product can be manufactured only by grinding and polishing.

In the present invention, the receiving shape can be formed with a radius of curvature substantially equal to the radius of curvature for grinding and polishing. With the above configuration, the machining time of the spherical surface forming process performed before the grinding / polishing process is smaller than that in the case of machining the square piece, and the processing time of the spherical surface forming process is shortened. According to the above configuration, the processing time can be shortened, so that the manufacturing cost can be reduced.
Further, when the surface roughness is good, the spherical surface forming process can be omitted.

[0053]

Third Embodiment FIGS. 7 and 8 show the present embodiment, FIG. 7 is a vertical sectional view of a molding apparatus, and FIGS.
The difference between this embodiment and the second embodiment is that the lower mold 92 has a curvature calculated from the molding surface 91a of the upper mold 91 so that the thickness of the molded lens is the same from the center to the entire outer circumference. Since the molding surface 92a is formed, it is particularly suitable for a lens which is difficult to be molded due to its large thickness deviation. In the present embodiment, the same components as those in the second embodiment are designated by the same reference numerals and the description thereof will be omitted.

The molding surface 92a of the lower mold 92 is calculated and formed so that the molding surface 91a of the upper mold 91 and the molding surface 92a of the lower mold 92 are evenly spaced over the entire surface. Also,
On the surface of the molding surface 92a of the lower mold 92, in order to prevent fusion with the heat-softened glass, CrN, Cr ₂ O ₃ ,
A thin film of a material having poor wettability is coated on heat-softened glass such as TiN and C-BN.

When the lens is molded by the same procedure as in the second embodiment, the molded lens 93 has a uniform thickness over the entire surface. Therefore, the cooling speeds of the central part and the outer peripheral part are equal (the lens cools from the surface, so if the uneven thickness is large, the thin part will cool quickly and become hard), and the entire surface of the lens will become hard at the same time. , Is closely transferred to the mold.

The molded lens 93 comprising the upper mold molding surface 93a and the lower mold molding surface 93b obtained as described above has defects (sinks, steps, wrinkles, etc.) associated with molding on the lower mold molding surface 93b.
Is occurring. Therefore, as shown in FIGS. 8a to 8c, CG processing is performed on the lower mold molding surface 93b (spherical surface generation processing, see FIG. 8b).
Then, grinding and polishing (see FIG. 8c) are performed to complete a lens.

According to this embodiment, it is possible to manufacture a lens which has a large degree of thickness deviation and cannot be manufactured by the method of the second embodiment. Further, since the solidification speed is the same over the entire surface of the lens, the transferability to the mold is good and the surface accuracy of the second embodiment or more can be obtained, so that the high-precision lens can be manufactured.

The lower mold molding surface may be formed to have a curvature along the curvature shape of the upper mold molding surface so that the respective thicknesses from the center to the outer periphery of the molded lens are the same.

The lower mold molding surface having the above structure is formed by calculation from the shape (curvature radius) of the upper mold molding surface and the lens thickness after molding. As a result, shrinkage due to cooling occurs similarly throughout, so if you examine the degree of shrinkage you can know the shape (curvature radius) of the lens after cooling, and design the upper mold in consideration of shrinkage. You can

According to the above construction, the precision on the molding surface (transfer surface) side can be improved even with a lens having a larger thickness deviation and outer diameter.

[0061]

Fourth Embodiment FIGS. 9 and 10 show the present embodiment.
Is a vertical cross-sectional view of the molding apparatus, and FIG. 10 is a vertical cross-sectional view showing a bucket accommodating a molding die. Reference numeral 103 denotes a base, and a column 104 is erected and fixed on the base 103. Prop 1
A guide rail 105 is vertically fixed to one side surface of 04, and a bucket 107 is supported on the guide rail 105 via an arm 106 so as to be vertically movable.

One end of a rope 108 is connected to the arm 106, and the other end of the rope 108 is guided by a pulley 109 provided on the upper portion of the support 104 to the surface of the support 104 opposite to the guide rail 105. . Rope 10
A weight 118 for giving an acceleration motion to the bucket 107 is connected to the other end of the weight 8, and the weight 118 can fall by gravity.

As shown in FIG. 10, in the bucket 107, a sleeve 110 and a molding die 111 which is mirror-finished to have a curvature of a molding lens are arranged inside. A hollow portion 110a is formed inside the sleeve 110,
The molding die 111 is fitted into the hollow portion 110a so that the outer peripheral surface of the molding die 111 and the inner peripheral surface of the hollow portion 110a are in contact with each other. On the upper part of the hollow part 110a, the mold 11
1, a hole 110b for supplying the molten glass 112 is formed, and a mortar-shaped taper 110c communicating with the hole 110b is provided on the upper part of the sleeve 110.

On the base 113, there is provided a die heater 113 for heating the bucket 107 when the bucket 107 descends to the lowermost part. A stand 115 for holding a pipe 114 for dropping and supplying the molten glass 112 onto the molding die 111 inside the bucket 107 is arranged on the side of the bucket 107. The pipe 114 is held by a stand 115 via an arm 115a, and the stand 115 is rotatable about its axis.
The tip of No. 4 is located substantially above the center of the hole 110b of the sleeve 110, and the pipe 114 can be retracted to a position that does not hinder the movement of the bucket 107.

A gas burner 116 for heating and melting the glass material in the pipe 114 to a predetermined viscosity is provided near the pipe 114. In addition, the pillar 104
The molten glass 112a in the bucket 107 on the upper side of the
A gas nozzle 117 for annealing while pressing the mold against the molding die 111 is arranged toward the hole 110 b of the bucket 107.

Next, a molding method using the apparatus having the above structure will be described. The bucket 107 in which the mirror-shaped forming die 111 is housed in advance is heated by the die heater 113 to a temperature of the glass transition temperature Tg-100 ° C. to Tg + 70 ° C. of the glass material used. Next, the glass material charged into the pipe 114 is heated and melted by the gas burner 116 to a viscosity of 10 ² poise or less, and the glass material is allowed to spontaneously flow out from the lower end (tip) of the pipe 114, and then onto the molding die 111 in the bucket 107. Molten glass 112 is dropped.

After the molten glass 112 is supplied onto the molding die 111, the pipe 114 is retracted from above the bucket 107 by the rotation of the stand 115, and the weight 118.
Is released and dropped by gravity, the bucket 107 is pulled by the load of the weight 118 via the rope 108, and the bucket 107 is raised by a uniform acceleration linear motion. After that, prop 10
4 The molten glass 112a in the bucket 107 is annealed while being pressed against the molding die 111 by hot air blown from the gas nozzle 117 located on the upper side.

The molten glass 112 immediately after dropping from the pipe 114 is heated and melted on the molding die 111 to have a viscosity of 10 ² poise suitable for molding, so that the bucket 107
When the mold 118 is pulled by the weight 118 and rises, the mold 111 makes an upward uniform linear acceleration motion, so that the molten glass 112a on the mold 111 is pressed against the mold 111 by the downward inertial force F and flattened. The inertial force F becomes a mass of molten glass M _G, the mass of the entire bucket m, the mass of the weight M, the gravitational acceleration is g, and _{F = M G g (M-} m) / (M + m) .

Therefore, if the inertial force F is sufficiently large, the molten glass 112a is spread by the molding die 111 to the inner wall of the sleeve 110 that regulates the outer periphery thereof.
The molten glass 112a has a shape as shown in FIG. Therefore, the weight 118 is appropriately selected to exert a desired inertial force F on the molten glass 112a, and the outer circumference of the molding die 111 and the inner diameter of the sleeve 110 are set and used according to the outer diameter of the desired lens. , Molten glass 112a
(Hereinafter, the one-sided molding lens 112a) is molded to a desired diameter on the molding die 111.

Next, when the bucket 107 is raised,
4 is stopped at the upper portion (the bucket 107 is stopped by a stopper (not shown).
It is provided on the 07 side or the weight 118 side). When the glass on the mold 111 is in a high temperature softened state when the bucket 107 is stopped, the diameter of the single-sided molded lens 112a is
Although it tries to return to its original shape due to surface tension, the single-sided molded lens 112a is annealed and cooled while being pressed and held from above by the hot air from the gas nozzle 117, and is flattened and solidified with a desired diameter. Where the sleeve 110
And the temperature of the molding die 111 is previously set to Tg-100 ° C to Tg.
By heating to + 70 ° C., it can be easily taken out from the bucket 107.

The single-sided molded lens having the desired diameter obtained as described above is ground and polished on the free surface side (the surface not in contact with the molding die 111) to complete the lens.

According to this embodiment, the molding apparatus can be manufactured at a lower cost than in the first embodiment, and the space can be minimized.

[0073]

The effects of the first and second aspects are that it is possible to realize the production of a glass lens which has a high surface accuracy and is cheaper than a double-sided polished lens. The effects of claims 3 and 4 are that it is possible to realize a method of manufacturing a glass lens having extremely high surface accuracy and requiring only one surface of the mold. The effect of claim 5 is that it is possible to manufacture a cheaper glass lens.

[Brief description of drawings]

FIG. 1 is a vertical sectional view showing a first embodiment.

FIG. 2 is a cross-sectional view of a main part showing the first embodiment.

FIG. 3 is a cross-sectional view of a main part showing the first embodiment.

4A to 4C are process diagrams of the first embodiment.

FIG. 5 is a vertical sectional view showing a second embodiment.

6A to 6C are process diagrams of the second embodiment.

FIG. 7 is a vertical sectional view showing a third embodiment.

8A to 8C are process diagrams of the third embodiment.

FIG. 9 is a vertical sectional view showing a fourth embodiment.

FIG. 10 is a vertical sectional view showing a fourth embodiment.

11A to 11C are molding process diagrams showing a conventional example.

[Explanation of symbols]

 1 Centrifugal Molding Equipment 2 Glass Raw Material Melting Section 3 Centrifugal Molding Section 4 Discharge Unit 5 Crucible 6 Nozzle 11 Centrifugal Rotating Section 12 Receiving Type Heating Section

Claims (5)

[Claims] 1. A glass lens, wherein one surface is a molding surface obtained by molding molten glass, and the other surface is a polishing surface obtained by grinding and polishing. 2. A glass lens comprising a step of molding molten glass with a molding die to transfer one surface and a step of grinding and polishing the other surface to a desired curvature. Molding method. 3. The step of molding the molten glass with a molding die and transferring one surface thereof comprises moving the molding die supplied with the molten glass toward the supplied molten glass side to perform single-sided molding. The method for molding a glass lens according to claim 2, which is characterized in that. 4. The step of molding the molten glass with a molding die and transferring one surface thereof is characterized in that the molding die to which the molten glass is supplied is rotationally moved and one-sided molding is performed by centrifugal force. Item 3. A method for forming a glass lens according to Item 2. 5. The step of molding the molten glass with a molding die and transferring one surface thereof comprises supplying the molten glass onto a receiving mold, and then molding and transferring the upper surface of the molten glass with an upper mold. The method of molding a glass lens according to claim 2, wherein