JPS6337043B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a lens molding method and a molding apparatus, and particularly to a lens molding method and a molding apparatus that can continuously mold lenses by pressing softened glass. This is the purpose.

The method for molding the above type of lens has conventionally been carried out as shown in FIG. Hereinafter, a conventional lens molding method and its problems will be explained using FIG.

First, to explain the apparatus for carrying out the method, a rotary table 3 that is configured to be rotatably driven and stopped freely via a main shaft 2 is located below an orifice 1 that is connected to a glass melting furnace (not shown). On this rotary table 3 are lower molds 4, 5, 6, and 3 molds for molding molten glass.
7 are arranged at four equally spaced positions on the circumference. When the rotary table 3 is stopped, that is, before lens molding starts,
The opening 8 of the orifice 1 is configured to face the upper position of the lower mold 4 (the lower mold on the left side in the figure), and the upper position of the lower mold 5 adjacent to this lower mold 4 is A plunger 10 for press-molding the molten glass (softened glass) 9 in the lower mold 5 in cooperation with the mold 5 is disposed so as to be freely slidable in the vertical direction. Further, between the opening 8 of the orifice 1 and the lower die 4 located below the opening 8, there is a cutting clamp configured to be able to open and close freely in order to cut a predetermined amount of the molten glass 9 flowing down from the opening 8. 11 are arranged. The rotary table 3 is controlled to repeatedly rotate and stop in 90 degree increments, and one stroke ends when the lower mold 4 repeats 90 degree increments and stops four times and is restored to its original position. I'm starting to do that.

To explain the method of molding a lens using the above-mentioned apparatus, first, the molten glass 9 is made to flow and hang down from the orifice 1 into the lower mold 4, and an appropriate amount of the molten glass 9 is cut through the cutting scissor 11. Next, move the rotary table 3 counterclockwise 90 degrees in the figure.
After rotating once, it is stopped, and the lower mold 4 filled with molten glass 9 is moved to a position directly below the plunger 10. Then, in that state, plunger 1
0 downward, this plunger 10 and the lower die 4
The molten glass 9 is pressed by the cooperative action of
Press molding of molten glass 9 is performed. In this case, the heat of the molten glass 9 is removed by the plunger 10.

After press molding, the plunger 10 is moved upward, and then the rotary table 3 is rotated 90 degrees counterclockwise in the figure and stopped. That is, the lower mold 4 stops at the position of the lower mold 6 in the figure. At this stop position, no work is performed; only the shape of the molded glass (molded lens) 9 is maintained.

Then, the lower mold 4 is stopped at a position where the rotary table 3 is further rotated by 90 degrees, that is, at the position of the lower mold 7 in the figure, and the molded lens 9 inside the lower mold 4 is pushed up from below to take out the molded lens 9. The lens molding process is completed.

The above lens molding method is as follows: each lower mold 4, 5, 6,
7, respectively, whereby lenses are continuously molded.

The molded lens 9 taken out from the lower mold 4 is placed in a slow cooling furnace (not shown), and cooled to room temperature while creating a temperature gradient to adjust optical characteristics.

However, the conventional lens molding method described above has the following problems. That is, first of all, it is necessary to raise the temperature of the softened glass to such a level that it becomes viscous fluid and to make it flow and hang down in the lower mold.
There was a problem in that each member such as 5, 6, 7 and plunger 10 was easily oxidized, and the life of each of these members was shortened. As a result, the cost of the equipment increases, and each member must be replaced frequently, which takes a lot of time. Second, there was a problem in that it was difficult to uniformly remove heat from the molten glass 9 during molding, and therefore sink marks were likely to occur. Furthermore, it is difficult to maintain the plunger 10 at a molding temperature (temperature suitable for molding), and therefore a device for cooling the plunger 10 is required, making the device complicated. Thirdly, when taking out the molded lens 9, the molded lens 9 was pushed up from below to release it from the mold, so the curvature portion of the molded lens 9 is easily damaged during this operation, reducing the quality of the molded lens 9. It was a contributing factor.

This invention was made in view of the problems of the prior art described above, and includes a step of smoothing the press surface of a lens material for molding in advance, and a step of heating the lens material after the processing until it reaches a predetermined viscosity. , by providing a lens molding method comprising the steps of transporting the lens material softened to a predetermined viscosity into an upper mold and a lower mold, and press-molding the lens material by the upper and lower molds, the above-mentioned prior art This solution solves various problems in .

Hereinafter, a case in which the lens molding method of the present invention is carried out using a lens molding apparatus shown in FIG. 2 and subsequent drawings will be described in detail.

The present invention includes a step of smoothing the press surface of a lens material for molding in advance, a step of heating the lens material after the processing until it reaches a predetermined viscosity, and a step of applying the lens material softened to the predetermined viscosity to an upper mold and a lower mold. A lens is molded by a step of transporting the lens material between the molds and a step of press-molding the lens material using the upper and lower molds, and each step will be explained below.

First, the process of smoothing the press surface of a lens material for molding will be explained using FIG. 2. That is, in FIG. 2, a plurality of glass blanks (lens materials) 13 evenly attached to the lower surface of the holder 12 are polished smoothly through a flat lap plate 15 whose upper surface is coated with an abrasive 14. As shown in the figure, the pressing surface (lower surface in the figure) of the glass blank 13 is smoothed by the cooperative action of the flat lap plate 15 which rotates and the holder 12 which is caused to make an oscar movement by the needle 16. It is now being polished. The glass blanks 13 are made by blanking an appropriate amount of rod material, and each glass blank 13 attached to the bottom surface of the holder 12 is
It is cut to a predetermined size. In addition, the polishing process of the press surface of the glass blank 13 does not require flatness, but only needs to be polished to a smooth surface. Therefore, the polishing means is not limited to the above-mentioned polishing means, and other means may be used as long as the surface can be polished to a smooth surface. Further, the glass blank may be made of a material having a polished spherical surface.

Next, a process of heating the polished lens material 13 until it reaches a predetermined viscosity will be described. As shown in FIG. 3, this step is performed as one step of a series of molding devices 17 for press-molding the lens material 13, and the heating furnace 18 performs this step. This heating furnace 18 is open at both ends and is formed into a so-called tunnel shape, and two rail-shaped conveyors 20 pass through the inside of the furnace 18 for transporting the lens material 13 toward the press molding section 19. . The temperature at the opening at the transfer start end of the lens material 13 in the heating furnace 18 is set to approximately room temperature, and the temperature near the opening at the transfer end side of the lens material 13 in the heating furnace 18 is such that the lens material 13 can be press-molded. The temperature is controlled to a predetermined high temperature in order to soften the material.
That is, for example, the material of the lens material 13 has a softening point.
In the case of optical glass called SFS ₁ , which is 480℃,
It is set so that it can be heated to 525° C. by passing through a heating furnace 18 and softened to a viscosity of 10 ⁶ poise.

Lens material 13 heated and softened as above
is carried between the upper and lower molds for press molding, and the carrying process is as follows. That is, the conveyor 20
The conveyor 20 is set to be long so that the molded lens can be transferred to a slow cooling furnace 21 having the same structure as the heating furnace 18. Mounting tables (carrying tables) 22 are fixedly mounted at appropriate intervals, and the lens material 13 placed on the mounting tables 22 is
is configured to pass through a heating furnace 18 and be transferred toward a press molding section 19. The mounting table 22 is made of a flat plate and is formed into a square shape, with a fourth plate in the center.
As shown in FIGS. 7 to 7, holes 23 and 24 are formed in two stages. The holes 23 and 24 are
Although the hole 23 on the upper side is formed with a larger diameter,
The diameter of this hole 23 is set to be smaller than the outer diameter of the lens material 13. As shown in FIG.
A lens material stage 25 having a step similar to (engages with) step 24 is fitted from above by means of dropping. This lens material stage 25
is configured to be able to move upward via a protruding rod 26 that can be used as a transfer member and is disposed at the center of the width direction of the conveyor 20 so as to be able to move up and down. During this upward movement, the lens material stage 25 and The protruding rod 26 has a magnet (electromagnet) 27, which is provided with a protrusion and a recess, respectively.
They are fixedly connected to each other via 28. The mounting table 22 and the lens material stage 25 are made of glass and a material that does not easily get wet, such as BN (boron nitride). On the side of the protruding rod 26 (on the outside of the conveyor 20), there is an upper mold 31 that is configured to be slidable within the upper mold guide member 29 and the lower mold guide member 30 by a hydraulic device (not shown). and a lower mold 32 are disposed, and the upper and lower molds 31 and 32 constitute a press molding section 19. There is a gap 3 between the upper mold guide member 29 and the lower mold guide member 30.
3 is provided, and lens material holding members 34, 34, which can serve as holding members, are interposed in this gap 33 so as to be movable in a direction orthogonal to the transport direction of the conveyor 20. Lens material holding member 3
4 and 34 are divided into parts so as to be able to clamp and fix the lens material 13 that has been moved upwardly through the protruding rod 26 at the upward movement position, and the clamping portions 34a, 4 and 34 in each clamping member 34, 34 At the bottom of 34a, there is a lens material 13 as shown in FIG.
Protrusions 35, 35 are provided respectively so as to support the lower circumferential surface of the lens material 13 when the lens material 13 is held between the lenses. Further, the diameter dimension D ₁ (see FIG. 5) of the upper side hole of the clamping portion 34 a formed when the lens material 13 is clamped and supported is formed to be the same diameter as the hole diameter d ₁ of the upper mold guide member 29. In addition, the diameter dimension of the lower side hole formed with a small diameter by the lower protrusion 35
D ₂ is formed to have the same diameter as the hole diameter d ₂ of the lower die guide member 30. Then, the lens material holding member 3
When the lens material 13 is fixedly supported and carried between the upper mold 31 and the lower mold 32 via the clamping members 34 and 34, the axis of each hole formed in the clamping members 34 and 34 and the upper and lower guide members 29 , 30 are aligned with each other. The clamping portion 34a of the lens material clamping members 34, 34 is made of glass and a material that does not easily get wet.
For example, it may be made of BN and attached and fixed, or the surface that contacts the glass may be coated with BN. Furthermore, the structure may be subjected to surface treatment such as carburization or ceramic coating with chromium oxide. Further, the atmosphere inside the room where the lens material 13 is pressed, the inside of the heating furnace 18, and the inside of the slow cooling furnace 21 is maintained by N ₂ gas.

The lens material 13 carried between the upper and lower molds 31 and 32 by the lens material holding members 34 and 34 is
Pressure molding is performed using upper and lower molds 31 and 32.

The lenses press-molded by the upper and lower molds 31, 32 are again clamped via the clamping members 34, 34, placed on the mounting table 22 of the conveyor 20, and transferred to the lehr 21 where they are slowly cooled to room temperature. It is becoming more and more common. Note that the slow cooling furnace 21 is
As shown in the figure, it is placed opposite the heating furnace 18, and the temperature near the opening on the starting side of slow cooling of the lens after molding is set to a predetermined high temperature state, but the temperature near the opening on the end side of slow cooling is set to a predetermined high temperature state. is set to be at room temperature.

The functions and effects of this embodiment consisting of the above steps will be explained. The cylindrical lens material 13 whose press surface has been smoothly polished in the first step is conveyed to the conveyor 2.
0 into the heating furnace 18 placed on the mounting table 22. The conveyor 20 is stopped when the lens material 13, which has passed through the heating furnace 18 and has been heated to a predetermined temperature, reaches the sliding surface of the holding members 34, 34 (see FIG. 4). Then, as shown in FIG.
After that, each clamping member 34, 34 is moved in the direction of the arrow to clamp the lens material 13. Then, as shown in FIG. 6, the lens material 1 is
3 is carried between upper and lower molds 31 and 32 maintained at a temperature 100° C. lower than the temperature of the lens material 13, and the lens material 13 is press-molded by the respective molds 31 and 32. The molding speed of each mold 31, 32 during this molding is
It is about 250mm/min. During this molding process,
The upper outer peripheral edge of the molded lens material 13 and the upper mold 3
If the pushing amount is set so that an appropriate gap is formed between the lens material 13 and the lens material 13, variations in the volume of the lens material 13 will be absorbed, which is convenient. After molding, the upper and lower molds 31 and 32 are restored to their original states, and the molded lens 13a is restored to the position shown in FIG. 5 via the clamping members 34 and 34, as shown in FIG. Then, the respective clamping parts 34a of the clamping members 34, 34 are opened, and the lens 1 after molding is
3a is placed on the lens stage 25 that has been moved upward. After that, the lens 13a is lowered onto the conveyor 20 via the protruding rod 26, and the conveyor 20 is moved down.
The lens 13a is turned on and transferred to the slow cooling furnace 21 for slow cooling. Then, the lens 13a after being slowly cooled can be taken out.

According to the method and apparatus for molding the lens of this embodiment, the lens material 13 only needs to be heated to a temperature at which it can be press-molded, and there is no need to heat it to a temperature at which it melts as in the prior art. Therefore, the upper and lower molds 31, 32 are less likely to be oxidized, and their lifespan can be extended. Furthermore, since the cooling range of the lens 13a becomes smaller, the occurrence of lens distortion, sink marks, etc. can be prevented compared to the prior art. In addition, since the upper and lower molds 31, 32 and the lens material 13 come into contact only during pressure molding (pressing), it is easy to control the temperature of the molds 31, 32 at a constant level, and the lens material 13 is uniformly cooled during molding. It has the advantage of being able to go to It also has the advantage that even if there is some volumetric error in the lens material 13, it can be absorbed. Furthermore, the lens material 13 is molded into mold 3.
Since the holding members 34, 34 which also serve as barrel molds are used for carrying the lens 13a between the lenses 1 and 32, it is possible to release the lens 13a after molding without damaging the lens 13a, thereby improving the quality of the lens. It is something that can be achieved.

FIG. 9 shows another embodiment of the clamping member 34, in which holes 36 are evenly provided in the body-shaped portion in order to absorb variations in the amount of lens material 13. It is composed of

The clamping member 34 has the advantage of being able to absorb the volumetric error of the lens material 13, and that the convex portion of the outer periphery formed thereby can be used as a reference when assembling the lens.

FIG. 10 shows a third embodiment of the present invention, and shows an apparatus for carrying out a method for molding a convex lens. The molding process is the same as that of the first embodiment, but in this case, the lens material 13 used is one that has been quantitatively polished into a spherical shape by ball polishing or the like. Further, a lens material suction member 37 is used as a transfer member for moving the lens material 13 upward, and a mounting table 38 having a concave portion 38a is fixed to the upper part of the conveyor 20 that transfers the lens material 13. Also, the clamping member 3
A pair of mounting members 39 are provided at the bottom of 4 and 34 as shown in FIG. This mounting member 39 is configured to slide the lower part of the holding members 34, 34 and retreat from the molding surface of the lower mold 32 after carrying the glass material between the upper mold and the lower mold.

The function of forming a convex lens by the above device is the first.
This embodiment is substantially the same as the embodiment described above, but since the lens material 13 is spherical, its upward and downward movements are performed via a suction member 37 that is in communication with a vacuum pump (not shown). Other functions are the same as those in the first embodiment, so their explanation will be omitted.

In each of the above examples, the viscosity of the lens material 13 was set to 10 ⁶ poise, but the viscosity is not limited to this, and the temperature between the mold temperature and the lens material 13 was set to 50°C.
If you slow down the molding speed to about 100mm/min,
A viscosity of 10 ⁷ poise is also possible. Further, the lower limit of the viscosity can be up to 10 ^5.5 poise, at which the lens material 13 does not deform due to its own weight. Therefore, the present invention is applicable if the viscosity of the lens material 13 is 10 ⁷ to 10 ^5.5 poise.

According to the above lens molding method and apparatus of the present invention, the lens material only needs to be heated to a temperature at which it can be press-molded, and there is no need to heat it to a temperature at which it melts as in the prior art. Therefore, the upper and lower molds are less likely to be oxidized and their lifespan can be extended. Furthermore, since the cooling range of the lens after molding becomes smaller, distortion of the lens, sink marks, etc. can be prevented compared to the prior art. In addition, since the upper and lower molds and the lens material only come into contact during pressure molding (pressing), it is easy to control the temperature of the upper and lower molds at a constant level, which has the advantage of uniformly cooling the lens material during molding. . moreover,
Since we use a holding member, such as a clamping member, that also serves as a body mold to transport the lens material between the upper and lower molds, it is possible to release the molded lens without damaging the molded lens. This is something that can be measured to improve quality.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of a conventional method, and FIG. 2 is an explanatory diagram of a method for polishing a lens material, which is one step of the present invention.
FIG. 3 is a perspective view of the main parts of an apparatus for carrying out this invention, FIGS. 4 to 7 are explanatory diagrams showing the operating state of the apparatus for carrying out this invention, and FIG. FIG. 9 is a perspective view of the main part of the implementation device; FIG. 9 is a perspective view showing the second embodiment of the main part shown in FIG. 8;
The figure is an explanatory diagram showing a third embodiment of the present invention.
FIG. 1 is a perspective view of the main part of FIG. 10. 12...Holder, 13...Lens material, 14
... Abrasive, 15 ... Flat lap plate, 16 ... Kanzashi, 18 ... Heating furnace, 19 ... Press molding part,
20...Conveyor, 21...Learning furnace, 22,38
... Mounting table, 23, 24 ... Hole, 25 ... Lens material stage, 26 ... Protruding rod, 27, 28 ...
Magnet, 29... Upper die guide member, 30... Lower die guide member, 31... Upper die, 32... Lower die, 33...
...Gap portion, 34...Lens material holding member, 34a
...Holding part, 35...Protrusion part, 37...Lens material adsorption member, 39...Placement member.

Claims (1)

[Claims] 1. Place a lens material on each of a plurality of rows of mounting tables, heat and soften the lens material to 10 ⁷ to 10 ^5.5 poise while transporting the lens material together with the mounting table, Stopping the lens material together with the mounting table, lifting the softened lens material from the mounting table, holding and transferring the lens material with a holding member, and carrying the lens material into an upper mold and a lower mold using the holding member. While holding the lens material with a holding member, the upper mold and the lower mold at a temperature lower than the temperature of the lens material are press-molded into a desired lens shape, and the molded glass lens is placed above the mounting table by the holding member. A method for molding a lens, which comprises: transporting the glass lens to a container, lowering the glass lens, placing it on the mounting table, transferring the glass lens, transferring the glass lens together with the mounting table again, and slowly cooling the glass lens. 2. The method for molding a lens according to claim 1, wherein the lens material has a pressed surface smoothed in advance. 3 In a molding device that heats and softens a glass material and then continuously molds a molded lens using an upper mold and a lower mold,
a conveyor that arranges mounting tables on which lens materials are placed at required intervals and moves them intermittently; a heating furnace that constitutes a heating atmosphere for heating and softening the lens materials in the conveyance direction of the conveyor; and an annealing furnace that constitutes an annealing atmosphere for the molded lens, which is disposed facing and separated from the heating furnace, and an annealing furnace that is disposed between the heating furnace and the annealing furnace, and is stopped between the heating furnace and the annealing furnace. A transfer member that can be raised and lowered to raise and hold the lens material on the mounting table and process and place the molded lens after molding on the mounting table; Upper mold for press molding into the required shape,
A press molding section in which a lower mold is arranged to be movable in the vertical direction, and the lens material held upward by the transfer member is carried between the upper mold and the lower mold of the press molding section, and the lens material is transferred between the upper mold and the lower mold. and a pair of lens material holding members that are reciprocally movable in a direction orthogonal to the conveyance direction of the conveyor, for transporting the molded lens onto the mounting table again. Molding equipment. 4. A patent characterized in that the transfer member is a protruding rod that lifts and holds the lens material placed on the mounting table through a lens material stage that is removable only in the upward direction, together with the lens material stage. A lens molding apparatus according to claim 3. 5. The lens molding apparatus according to claim 3, wherein the transfer member is a lens material suction member that suctions and holds the lens material and the upper surface of the molding surface of the molded lens.