JPH0339977B2 - - Google Patents

Description

[Detailed description of the invention] [Technical field] The present invention relates to a lens molding method.

[Prior Art] Generally, there are the following methods for molding lenses by press molding.

That is, a rod-shaped glass material is cut with a cutter to a predetermined width, and the cut surface is polished with a grindstone to form a lens material with a desired capacity. Then, this lens material is inserted into a mold, the temperature of the mold is raised to thermally soften the lens material, pressure is applied to the upper and lower molds for press molding, the mold is cooled, and the molding surface is After transferring it to the glass surface, the pressure from the mold was removed and the finished lens was removed.

[Problems] Conventional lens materials were cut with a cutter and the cut surfaces were polished, resulting in the following problems.

That is, since the abrasive grains of the cutter or abrasive stone were attached to or bitten near the surface of the cut surface, there was a problem that the abrasive grains not only remained on the lens but also damaged the molding surface of the mold.

Furthermore, since the cut surface of the lens material was polished, a lot of time was required for the polishing work. If the degree of polishing is simplified at this time, the polishing marks on the lens material must be completely melted (in a fluid state) and smoothed, and for this purpose the heating temperature of the lens material must be adjusted to such a level that the polishing marks disappear and the polishing becomes smooth. When such a lens material is molded, the surface temperature of the mold increases abnormally, shortening the life of the mold and causing a seizure phenomenon. Furthermore, if polishing marks remain on the lens surface after molding, the lens requires polishing work.

As a result, the cost of the equipment becomes high, and each member must be replaced frequently, which, together with the above-mentioned work, takes a lot of time.

[Means and objects for solving the problem] Accordingly, the present invention is achieved by cutting the pressed surface of the lens material from the rod of the glass material, and then deforming the lens material after being pressurized. By heating the lens material until it reaches a certain viscosity and press-molding the heated and softened lens material between upper and lower molds, the smooth mirror surface obtained by cutting the lens material is directly formed as a lens surface, making this type of It is an object of the present invention to provide a lens molding method that can simplify lens molding and greatly improve the life of a mold.

[Example] Hereinafter, an example of the lens molding method of the present invention will be described with reference to the drawings.

First Embodiment FIG. 1 is a side view showing an outline of the apparatus used to carry out the lens molding method of the present invention, FIG.
FIG. 4 is an explanatory diagram showing the stress distribution and fracture state of high pressure on the lens material.

However, in the lens forming apparatus shown in FIG.
21 is a processing section for the lens material 20, 22 is a cleaning section for the lens material 20 used as necessary, 23 is a heating furnace, 24 is a molding section, 25 is a slow cooling furnace, and each of these parts is a carrier for transporting the lens material 20. A conveyor 27 such as a chain, which is equipped with 26 in a row, is arranged in a row along the conveyance direction of the upper conveyance section 32a of the conveyor line 32, which is constructed by stretching between wheels 28, 29, 30, 31. There is.

Moreover, 33 is a take-out part of the molded lens 34,
This take-out section 33 is arranged at the starting end of the lower conveyance section 32b of the conveyance line 32.

Furthermore, the processed portion 21 of the lens material 20 is
As shown in FIG. 2, there is a pressure vessel 41 equipped with a pressure generating device 40, and a push rod 4 for pushing out a rod-shaped lens material 42 loaded into the pressure vessel 41.
3, and a transport pad 44 that takes out the lens material 20 cut into pieces in the pressure vessel 41 and transports it into the cleaning section 22.

In addition, inside the pressure vessel 41 of the processing section 21,
Loading hole 45 into which rod-shaped lens material 42 is loaded
In addition to providing a large diameter portion 45a of this charging hole 45,
A seal 46 such as an O-ring for maintaining airtightness is provided at the tip of the large diameter portion 4 .
5a, a connecting hole 47 with the pressure generating device 40
A buffer member 48 made of stainless steel or the like is interposed at the rear of the large diameter portion 45a. Furthermore, the rear end opening 45b of the insertion hole 45 presses and supports a buffer member 48 and the like, and also supports a lens material 42.
A loading fixing member 49 is removably screwed through a threaded portion 50.

In FIG. 2, reference numeral 51 indicates a notch cut along the length of a rod-shaped lens material 42 processed to have a uniform outer diameter, corresponding to the capacity of the lens, and reference numeral 52 indicates a circuit section 53 of the pressure generating device 40. This shows the pressure indicator installed inside.

Next, a cleaning section 22 disposed adjacent to the processing section 21 cleans the lens material 20, which has been cut in the processing section 21 as will be described later, from dust and oil in the atmosphere of the conveyance path. It is equipped with a structure that can perform necessary cleaning such as washing with water to prevent it from adhering to the molding process and hindering the molding process. Note that this cleaning section 22 can be omitted when the atmosphere of the processing section 21 and the conveyance furnace to the heating furnace 23 are clean. This cleaning section 22
The heating furnace 23 disposed adjacent to the cleaning section 22
After cleaning, the lens material 20 held by the carrier 26 of the conveyance line 32 and carried into the heating furnace 23 is heated in a heating atmosphere that can soften it to a predetermined viscosity, that is, a viscosity that can be deformed when pressurized. It is constructed so that it can be maintained.

Further, the carrier 26 that conveys the lens material 20 after cleaning is formed of an annular body having an opening at the top and an opening 26b for press molding at the bottom 26a, as shown in the molding section 24 shown in the first diagram. Lens material 2 is placed on the inner opening edge of the opening 26b.
It is formed by providing 0 engagement step portions 26c.

Furthermore, the forming section 24 is arranged adjacent to the heating furnace 23, and as shown in FIG.
By installing upper and lower molds 54 and 55 for lens molding on both upper and lower sides of the lens material 20 carried in while being held by the carrier 26 via a fluid cylinder etc., the molds 54 and 55 are connected to a fluid cylinder or the like so as to be movable up and down. It is configured.

The upper and lower molds 54 and 55 are constructed so that they can be heated to a temperature near the dislocation point of the lens material 20 by a heater (not shown), and the inside of the molding section 24 can be maintained in an inert atmosphere at all times. It is configured.

In addition, the annealing section 25 disposed adjacent to the molding section 24 is designed to prevent distortion from occurring in the lens 56 after molding and to maintain uniform optical performance such as refractive index. The structure is such that slow cooling can be performed while setting conditions such as temperature, time, etc.

Incidentally, this slow cooling furnace 24 would not be particularly necessary if the lens material could be maintained under pressure in the upper and lower molds and the above-mentioned distortion and optical performance could be maintained for a long time in the molds, but the yield would be reduced. descend.

Furthermore, the take-out section 33 disposed at the starting end of the lower conveyance section 32b of the conveyance line 32 is connected to the carrier 2.
6 reaches the lower conveyance part 32b from the upper conveyance part 32a, and at the stage where it is reversed, the molded lens 56 held in the carrier 26 falls due to its own weight or a push rod (not shown) to prevent scratches on the lens surface, etc. It is constructed by arranging a pedestal 57 that can receive the object without causing any damage.

Now, the case where a lens is molded using the lens molding apparatus having the above-mentioned configuration will be described below.

First, in the processing section 21 shown in the second figure, a rod-shaped lens material 4 is inserted into the insertion hole 49a of the fixing member 49.
After loading the rear part of the lens material 2, the front part of the rod-shaped lens material 42 is loaded into the charging hole 45 of the pressure vessel 41 while the fixing member 49 is screwed onto the threaded part 50 of the pressure vessel 41.

Further, the notch 51 carved on the outer periphery of the rod-shaped lens material 42 is set so as to be located at the center between the seals 46, which have already been adjusted to have an interval corresponding to the cutting width. The amount by which the lens material 42 is pushed forward by the push rod 43 after cutting is as follows:
The next cutting notch 51 is positioned at the center between the seals 46 and is set so that the cutting surface does not cover the seals 46.

Under the set state of the lens material 42,
The pressure generator 40 is activated to apply a pressure medium such as water, oil, or other fluid or gas to the outer periphery of the lens material 42 through the circuit section 53 and the connection hole 47 of the pressure vessel 41 .

For example, by applying a high pressure P of about 200 to 1000 kg/ ^cm2 , a stress distribution as shown in FIG. The crack progresses with propagation f and is broken.

Therefore, the lens material 4 through this notch 51
In the cutting process in step 2, when the completion of cutting is confirmed by a cutting sound, etc., the push rod 43 is moved forward to advance the lens material 42 by a predetermined amount, and the next notch 51 is placed at the center position between the seals 46. Set it while positioning it.

On the other hand, by pushing the push rod 43, the lens material 20 cut from the rod-shaped lens material 42 is pushed out toward the opening side of the charging hole 45 of the pressure vessel 41.

At this time, the conveyance pad 44 moves to the opening side of the charging hole 45, and the cut lens material 20 is suctioned and held by the suction cup 44a attached to the front side thereof.

Further, the conveyance pad 44 supplies the lens material 20 held by suction into the cleaning section 22, and after the required cleaning is carried out in the cleaning section 22, the lens material 20 of the conveyance line 32 is transferred to the carrier 2 of the conveyance line 32.
6 and place it there.

Thereafter, by the movement of the conveyance line 32, the lens material 20 placed in the carrier 26 is carried into the heating furnace 23, where it is heated in accordance with the movement speed of the conveyance line 32, and is heated to a predetermined temperature necessary for molding. It is transported into the molding section 24 while being softened to a viscosity.

Thus, the softened lens material 20 is placed in the molding section 24 and in the carrier 26 while being accurately vertically centered. In connection with this centering and stationary operation of the lens material 20, the upper and lower molding molds 54 and 55 are moved downward and upward in opposite directions by the operation of fluid cylinders, etc., and the carrier 26
The inner lens material 20 is press-molded into a desired shape.

Further, in the press-molding state of both molds 54 and 55, the lens material 20 is cooled to a temperature at which it does not deform (the mold temperature of both molds 54 and 55). In other words, the temperature of the entire molded lens 56 reaches the same temperature as the mold in a few seconds to several tens of seconds or a few minutes, depending on the diameter and thickness of the lens, and at that stage both molds 54, 5
After opening the mold 5, the carrier 2 on the conveying line 32
6, the molded lens 56 is conveyed to an annealing furnace 25, and as described above, an annealing process is performed within a range that does not cause distortion or changes in optical properties of the molded lens 56.

At this time, if the molded lens is slowly cooled in the mold as described above, a slow cooling furnace is not particularly required.

After the slow cooling process, the carrier 26 passes through the wheels 29 and 30 and reaches the lower conveyance section 32b, as shown in FIG. The molded lens 56 falls onto a pedestal 57 and is released by its own weight or by a push rod (not shown). At this time, in order to raise the pedestal 57 to the molded lens 56 in the carrier 26, it may be connected to a reciprocating cylinder or the like to eliminate the impact when it falls.

Therefore, as described above, each of the steps of cutting the lens material 20, heat treatment, press molding, slow cooling, and mold release in the lens molding apparatus can be continuously molded into the molded lens 56 by a series of repeated operations. It is.

In addition, in FIG. 5, the rod-shaped lens material 42
In addition to showing the state of the cut surface of the lens material 20 obtained by cutting, FIG. 6 shows its surface roughness, and FIGS. 7a and 7b show interference images of the surface shape of the molded lens 56. .

Second Embodiment FIG. 8 shows the second embodiment of the processing section 21 in FIG.
It is a longitudinal cross-sectional view which shows another Example different from the figure.

However, the processing section 21 in this embodiment is
A holding part 58 rotatably holds the rod-shaped lens material 42, and a diamond needle 5 is attached to the outer periphery of the rod-shaped lens material 42 held by the holding part 58.
Diamond needle 59 that holds 9 while pressing it
It consists of a holding part 60 and a flame part 61 held on the opposite side of the holding part 60.

When cutting the lens material 20 in the processing section 21, the rod-shaped lens material 42 is rotated and held in the holding section 58, and the diamond needle 59 is rotated through the holding section 60. The lens material 42 is pressed against the cutting position of the lens material 42,
A scratch 62 is carved on the outer periphery of a rod-shaped lens material 42.

Thereafter, a flame 61a is applied from the flame section 61 to the scratch 62 carved on the outer periphery of the lens material 42 and heated, thereby generating thermal stress in the lens material 42 and causing a desired width to be formed through the scratch 62. The lens material 20 can be cut.

Further, as is well known, the cut surface obtained in this manner has a high surface roughness, although there are some waviness or the like.

Therefore, it was confirmed that the lens material 20 could be molded into a molded lens similar to that of the first embodiment by the molding process in the molding apparatus shown in the first figure.

Third Embodiment FIG. 9 is a longitudinal sectional view showing another embodiment of the processing section 21 in FIG. 8.

The processing section 21 has the same structure as the holding section 58 of the lens material 42 and the holding section 60 of the diamond needle 59 in the second embodiment, but instead of the flame section 60 that causes thermal stress. , a thermal light source 63 such as a laser beam capable of more localized heating is provided.

Incidentally, reference numeral 64 indicates the heat rays irradiated onto the scratch 62 through the condenser lenses 64 and 65.

Therefore, similarly to the second embodiment, the lens material 4
A scratch 62 is made at the cutting position of 2 using a diamond needle 59, and a heat ray is irradiated from the thermal light source 63 through the condensing lens 64 to generate thermal stress in the same area, thereby cutting the lens material into a predetermined width. 20
can be cut.

Therefore, it was confirmed that a molded lens similar to that of the first example could be molded from the lens material 20 by passing through each process of the molding apparatus shown in the first figure.

[Effects of the Invention] As is clear from the above description, the lens molding method of the present invention is characterized by cutting a rod-shaped lens material in the preliminary processing step of the lens material. It is possible to automatically process a lens material having a mirror surface in a short time, and it is possible to mold the lens material by heating and softening it, and this also simplifies the molding in this type of lens molding method. The molding time can be shortened.

In addition, everything from preliminary processing of the lens material to molding and mold release operations can be completely automated, making it possible to mold lenses with high precision at low cost as a whole.

In addition, the molding temperature required for lens molding with a lens material of a predetermined width obtained by cutting a rod-shaped lens material is lower than that required for molding a lens material with polishing marks. Furthermore, since foreign matter that adversely affects the mold is not attached to the cut surface, the life of the mold can be greatly improved.

[Brief explanation of drawings]

Fig. 1 is a side view showing an overview of the lens molding apparatus used in the lens forming method of the present invention, Fig. 2 is a longitudinal cross-sectional view showing the processed portion of the rod-shaped lens material, and Fig. 3 shows the stress distribution in the lens material. FIG. 4 is an explanatory diagram showing the propagation state, FIG. 5 is a surface diagram showing the cut surface of the lens material after cutting, and FIG.
The figure is a diagram showing the surface roughness on the same surface, Figure 7a,
b is an explanatory view showing an interference image of the surface shape of a molded lens, and FIGS. 8 and 9 are longitudinal sectional views showing a processed portion of the rod-shaped lens material. 20...Lens material, 21...Processing section, 22...
...Cleaning section, 23...Heating section, 24...Molding section, 2
5...Learning furnace, 26...Carrier, 27...Conveyor, 28, 29, 30, 31...Wheel, 3
2... Conveyance line, 33... Take-out section, 40...
...Pressure generator, 41...Pressure vessel, 42...Rod-shaped lens material, 43...Push rod, 44...
Transfer pad, 45...Charging hole, 46...Seal,
47...Connecting hole, 48...Buffer member, 49...Fixing member, 50...Threaded portion, 51...Notch, 52
...Pressure indicator, 53...Circuit section, 54...Upper mold, 55...Lower mold, 56...Molded lens, 57...
...cradle.

Claims (1)

[Claims] 1. Processing a rod-shaped glass material to a predetermined width with stress to form a broken surface on the lens material, and a process of forming a broken surface on the lens material, which has a viscosity that allows it to deform when pressurized. The process of heating the lens material in a heating furnace to
A process of press-molding the lens material using a mold heated to a molding temperature, a process of cooling the molded lens in the mold until the temperature reaches a temperature at which the molded lens after press-molding does not deform, and a process of preventing distortion of the molded lens after cooling. A lens molding method characterized by comprising a gradual cooling process within a range that does not cause changes in optical properties. 2. The lens molding method according to claim 1, wherein the step of cutting the rod-shaped glass material into a predetermined width with stress is performed by applying pressure to a notch formed in the glass material. 3. The lens according to claim 1, wherein the step of cutting the rod-shaped glass material with a stress of a predetermined width is performed by applying thermal stress by heating the scratches carved in the glass material. Molding method.