JPH0372578B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a press molding apparatus for optical elements.
The present invention relates to an optical element manufacturing apparatus that can continuously manufacture high-precision optical elements that do not require post-processing after press molding.

(Prior art) In recent years, optical elements with high-precision optical surfaces that do not require post-processing such as grinding and polishing have been developed by press-molding optical element materials placed in molds with a predetermined surface accuracy. A method for molding has been developed.

An optical element molding method using such a press molding method and suitable for continuous molding of optical elements is disclosed in, for example, Japanese Patent Application Laid-Open No. 59-150728 or Japanese Patent Application Laid-Open No. 61-1989.
As shown in Publication No. 26528, a material for molding an optical element is placed in a mold, and while this material is held in the mold, it is placed in a molding chamber having a heating section, a molding section, and a cooling section. After the material is heated and softened to a moldable temperature in the heating section along with the mold, it is pressed in the molding section, and then in the cooling section while maintaining the state of the mold during pressing. It involves the steps of cooling the molding material to below its glass transition point, and then removing the molded product from the mold.

(Problem to be Solved by the Invention) However, during such a process, when the material for molding an optical element is heated to a temperature at which it can be molded, the material for molding is heated to the surface of the mold within the mold. Since they are in contact with each other or in close proximity, there is a problem in that the molding material reacts with the surface of the mold before press molding and the surface of the mold is attacked. In particular, when the molding material for optical elements is a lead-containing glass material, the distance between the glass material and the mold surface is 1
Even in a non-contact state of about mm, the lead component in the glass material adheres to the mold surface after heating and the mold surface is rapidly corroded, resulting in a significant decrease in the surface precision of the mold.

In order to solve these problems, the present inventors have aimed to prevent erosion of the mold by the glass component during press molding, maintain the durability and surface precision of the mold, and create a high-precision optical element. An optical element manufacturing apparatus that can continuously and mass-produce optical elements has already been proposed.

Conventionally, in this type of optical element manufacturing equipment, it has been impossible to provide a cooling process near the pressing process due to the configuration of the equipment, so it is desirable to devise a new molding chamber in order to shorten manufacturing time. was.

The present invention provides a molding chamber configuration and its cooling means that can shorten the time required for cooling after press molding, thereby shortening the manufacturing time of optical elements.

(Means for Solving the Problems) In order to solve the above-mentioned problems, the optical element manufacturing apparatus of the present invention includes an intake chamber for an optical element molding material, a heating section, a press section, an annealing section, and a molded product. a pallet in which the optical element molding material supplied in the intake chamber and a mold for press-molding the molding material are arranged, and means for moving the pallet through the respective parts. In the optical element manufacturing apparatus, the heating section and the pressing section are configured from a linear molding line, and the slow cooling section is arranged in parallel with the forming line, and the forming line and the slow cooling section are connected to form the press section. The method is characterized in that a means for rapidly cooling the molded product after press forming is provided in the connecting path from the to the slow cooling section.

(Function) In the present invention, the heating section and the press section are constructed from a linear forming line, and the slow cooling section is arranged in parallel with the forming line, and these forming lines and the slow cooling section are connected to allow slow cooling from the press section. A means for rapidly cooling the molded product after press molding is provided in the connecting path leading to the press molding section.

With this configuration, it is possible to provide a cooling process near the pressing process, which was impossible due to the configuration of the conventional apparatus, and this cooling means can shorten the entire manufacturing time.

As a means for rapidly cooling the press-formed molded product provided in the connection path as described above, it is possible to provide a fan in the connection furnace to cause gas convection, or to provide a means for flowing cooling gas from the outside into the connection path. It can be implemented by

(Example) Examples of the present invention will be described below with reference to the drawings.

1 to 6 are diagrams showing a device related to an embodiment of the device of the present invention. A schematic plan view of the entire device is shown in FIG. 1, and a sectional view of each part in the order of steps is shown in FIG. ~Illustrated in Figure 6. Moreover, FIG. 7 is a schematic sectional view showing the first embodiment of the connecting path (transfer path 25), and FIG. 8 is a schematic sectional view showing the second embodiment of the connecting path (transfer path 25).
It is a schematic sectional view of an example.

The overall configuration of this apparatus consists of a material intake chamber 1, a heating section 2, a material transfer section 3, a press section 5, an annealing section 6, and a molded product removal chamber 7. The material intake chamber 1, the heating section 2, the material transfer section 3, and the press section 5 are located in the same line (hereinafter, this line is referred to as a forming line 4), and a slow cooling section 6 is located in parallel with the forming line.
is installed.

A first transfer chamber 21 is constructed near the entrance of the heating section 2, and the material intake chamber 1 is provided in this first transfer chamber 21. A second transfer chamber 22 is configured near the outlet of the press section 5, and a third transfer chamber 23 is configured at the entrance of the annealing section 6, and these second and third transfer chambers are connected by a transfer path 25. connected. or,
A fourth transfer chamber 24 is configured near the outlet of the slow cooling section 6, and a molded product removal chamber 7 that has been moved is provided in this fourth transfer chamber 24, and the fourth transfer chamber 24 and the first It is connected to the transfer chamber 21 by a circulation path 26. With this configuration, the present molding apparatus forms a molding chamber 59 with a continuous circulation path.

Reference numeral 11 denotes a pallet to which the molding chamber 59 is transferred, and on the pallet 11, a material mounting table 12, an upper mold 13 and a lower mold 14 for press molding are arranged at a constant interval. There is. The press molding surfaces of the upper mold 13 and the lower mold 14 are provided with mirror surfaces 13a and 14a, respectively, for molding optical element functional surfaces.

As a means for transferring the pallet 11 into the molding chamber, an extrusion cylinder 51 is provided in the first transfer chamber 21, and the pallet 11 is moved to the press section 5 by this extrusion cylinder. The second transfer chamber 22 has a drawer cylinder 52.
The pallet 11 moved to the press section 5 by the drawer cylinder 52 is pulled out to the second transfer chamber 22, and the pallet 11 moved to the second transfer chamber by the pusher cylinder 53 is provided. is pushed out to the third transfer chamber 23. The third transfer chamber 23 is provided with an extrusion cylinder 54, by which the pallet 11 transferred to the third transfer chamber 23 is extruded to just before the fourth transfer chamber 24. The fourth transfer chamber 24 has a drawer cylinder 5.
5 and an extrusion cylinder 56 are provided,
The pallet 11 moved to just before the fourth transfer chamber 24 by the drawer cylinder 55 is pulled out to the fourth transfer chamber 24, and the pallet 11 moved to the fourth transfer chamber 24 by the pusher cylinder 56.
is pushed out to the first transfer chamber 21 again. Thus,
The pallet 11 is transferred to each process by the extrusion or pull-out operation of these cylinders, and moves within the molding chamber 59 of this apparatus. The pallet 11 is placed on a rail 32 provided in the molding chamber 59, and is moved on the rail by extrusion or extraction of each cylinder.

Next, each part of the molding chamber 59 will be explained.

A heater 57 is provided in the furnace body corresponding to the heating section 2, material transfer section 3, and press section 5, and a slow cooling section 6
A heater 58 is provided in the furnace body corresponding to the above. Each of these heaters is used for heating the material 15 and cooling the molded product 18 after pressing.

An upper mold 13 is provided in the material transfer section 2 and the molded product removal chamber 7.
Lifting hands 16 and 20 are provided for lifting the lower die 14 at a required interval (a fourth
Fig. 6). This lifting hand is moved up and down by a lifting means (not shown). Further, the material transfer section 3 is provided with a suction finger 19a (a fourth
), the upper mold 1 is lifted by the operation of the lifting hand 16.
3 is lifted once, the suction hand is operated and the material 15 is transferred to a predetermined position on the lower mold 14. This suction finger 19a is used to hold the pallet 1 so that the material 15 is accurately placed at a predetermined position on the lower die 14 when the material 15 is transferred as described above.
It is configured to operate with a constant stroke in which the material mounting table 12 on the top 1 and the lower mold 14 are accurately translated in parallel by a length of a predetermined interval.
Further, in the material intake chamber 1 and the molded product removal chamber 7, there are suction fingers 19b for placing the material 15 on the mounting table 12 and for taking out the molded product 18 from the upper mold 14.
(Figure 6).

The press section 5 is provided with a press rod 17 for pressing the upper die 13 during press molding (FIG. 5).

In this device, the inside of the continuous path 59 is evacuated and then filled with N ₂ to prevent the mold materials forming the upper mold 13 and the lower mold 14 from being oxidized at high temperatures.
Since it is necessary to fill with non-oxidizing gas such as gas, the above-mentioned lifting hand 16 and suction finger 1
9a, 19b, press rod 17, etc. and molding chamber 5
9. It is necessary to provide sufficient shielding to the sliding parts with the outer wall to ensure the airtightness of the road body.

Further, in this apparatus, although not shown in the drawings, it is necessary to provide an atmosphere exchange chamber so that when the material 15 is taken into the material intake chamber 1, outside air does not enter the inside of the furnace body.

Next, a first embodiment of the transfer path 25 will be described with reference to FIG. Figure 7 shows the first
A schematic cross-sectional view taken along line A--A in the figure is shown.

In the figure, numeral 33 is a molding chamber corresponding to the second transfer chamber 22, into which high-temperature gas from the heating section 2 flows. 34 is a molding chamber corresponding to the slow cooling section 6.

A fan 35 connected to a motor is provided at a main portion of the transfer path 25, and the cooling gas from the slow cooling section 6 flows into the transfer path 25.

A shutter 30 is provided at the boundary between the transfer path 25 and the second transfer chamber 22, and this shutter is connected to a shutter opening/closing cylinder 31 connected to a controller (not shown), and the extrusion cylinder is driven by the cylinder. It opens and closes in synchronization with the extrusion operation of 53. That is, when the extrusion cylinder 53 is pushed out, the shutter 30 is opened, and when the extrusion cylinder 53 is pulled back, the shutter 30 is closed. This configuration prevents high-temperature gas from entering the molding line 4.

It is preferable that a sufficient shield 37 be applied to the portion of the transfer path 25 where the fan 35 and the shutter opening/closing cylinder 31 slide against the furnace body to ensure airtightness of the path body.

With this configuration, the rotation of the fan 35 causes convection of the gas in the transfer path 25, and the pressed molded product 18 passing through the transfer path is cooled, thereby reducing the burden of slow cooling in the slow cooling section 6. The slow cooling section 6
can be passed through in a short time.

Furthermore, a second embodiment of the transfer path 25 will be described with reference to FIG. FIG. 8 shows a schematic sectional view taken along line A--A in FIG. 1.

In this embodiment, unlike the above-mentioned embodiments, cooling gas is forcibly introduced from outside the furnace body as a cooling means. As shown in the figure, the cooling gas from the slow cooling section 6 is cooled by a cooling means 42 through a suction port 44 provided below the slow cooling section 6 by a blower 43 provided outside the furnace body. After passing through the trachea 40, the discharge nozzle 41
It flows into the transfer path 25 from there.

The other configurations of this embodiment are substantially the same as those of the first embodiment. With this configuration, as in the above embodiment, the inside of the transfer path 25 is rapidly cooled, and the pressed molded product 18 passing through the transfer path 25 is slowly cooled, reducing the burden of slow cooling in the slow cooling section 6. Therefore, the passage through the annealing section 6 can be carried out in a short time.

Next, the operation of the apparatus configured as described above will be explained in accordance with the order of press forming steps shown in FIGS. 2 to 6. FIG. 2 shows the pallet 11 without any materials 15 placed thereon.

First, as described above, in order to prevent the mold materials of the upper and lower molds 13 and 14 from oxidizing, the inside of the molding chamber 59 is evacuated to 1×10 ^-2 Torr using a vacuum pump (not shown), and then N ₂ gas or other Fill with non-oxidizing gas. Next, the heaters 57 and 58 are energized to raise the temperature inside the furnace to a predetermined value. After the temperature rise is completed, the material is passed through the atmosphere exchange chamber in the material intake chamber 1,
The material 15 is placed on the mounting table 12 of the pallet 11 in the material intake chamber 1 by the suction finger 19b as shown in FIG.

Next, according to the above-mentioned operation, the push-out cylinders 51, 53, 54, 55 and the draw-out cylinder 5 are
Each time the pallets 11 are sequentially sent from the molded product take-out chamber 7 to the material intake chamber 1 by operating the actuators 2 and 56, the materials 15 are placed on each mounting table 12 in the above-described manner. By repeating these operations, the material 15 supplied to the first pallet 11, the upper die 13, and the lower die 14 are heated to the temperature required for press forming near the material transfer section 3, and then the material is removed. 15 is transferred to the lower mold 14. Note that at this time, it is desirable that the material 15, the upper mold 13, and the lower mold 14 be heated to approximately the same temperature. By doing so, the temperature of the material 15 after transfer does not change depending on the temperature of the upper die 13 or the lower die 14, and press forming can be performed under optimal press temperature conditions. And material transfer section 3
, as shown in FIG.
6 lifts the upper mold 13, and then the material 15 is suctioned by the suction fingers 19a and transferred onto the lower mold 14. Thereafter, the extrusion cylinder 51 is pushed out to move the pallet 11, on which the transfer of the materials 15 has been completed, to the position of the press section 5. At this time, the lifting hand 16 is removed and the press rod 1 is removed.
7 is activated to press the upper mold 13 with a predetermined press pressure, thereby performing press molding on the material 15.
Next, the pressure of the press rod 17 is released, and the upper mold 13 is pressed while maintaining its state during pressing.
The pallet 11 is transferred from the press section 5 to the second transfer chamber 2.
Move to 2. Further, this pallet 11 is transferred to a third transfer chamber 23 via a transfer path 25. The molded product 18 held in the upper and lower molds 13 and 14 while passing through the transfer path 25 is cooled by the cooling means of the transfer path 25. Next, palette 11
is moved in the direction of the slow cooling section, but since other pallets 11 are arranged in front of this moving direction, as the above-mentioned operation continues, the pallet 11 is moved toward the slow cooling section. The molded product 18 held in the upper mold 13 and lower mold 14 while reaching the vicinity of the exit of the mold 6 passes through the annealing section 6, where it is continuously cooled by a transfer path 25. Next, the pallet 11 that has been moved to the leading position of the slow cooling section 6 is moved to the molded product removal chamber 7.

Next, the lifting hand 20 is operated to remove the upper mold 13, and then the molded product 18 is taken out by the suction finger 19b. Then, the pallet 11 from which the molded products have been removed is transferred to the material intake chamber 1 via the feeding path 26, and the above-described operations are repeated again to continuously produce molded products 18.

Here, temporal changes in glass temperature in each process of the apparatus of this embodiment will be explained with reference to FIG. 9. Figure 9 shows optical glass SF8 (glass transition point Tg = 443°C,
The time-temperature curve is shown when a convex lens with an outer diameter of 20 mm and a thickness of 2 mm is molded using a specific gravity of 4.22). T1 to T5 indicate the time in each step.

The glass material 15 placed on the material placement 12 in the material intake chamber 1 is heated in the heating section 2 (T0
~T1), Lower mold 1 after raising the press temperature to 530℃
4, and the upper mold 13 is further placed on the mold 13 for press molding (T1 to T2). Next, when passing through the transfer path 25, it is rapidly cooled to 480°C by the cooling means (T2 to T3), and then passed through the slow cooling section 6 and subsequently cooled to a takeout temperature of 330°C (T3 to T3).
T4).

By the way, when cooling is performed only in the slow cooling section like in the conventional equipment, as shown by the dotted line in the same figure, it takes a long time to slowly cool from the press temperature of 530°C to the unloading temperature of 330°C.
It takes T2 to T5, and an additional cooling time of T4 to T5 is required.

According to the embodiment apparatus as described above, the time required to slowly cool the molded product after pressing is shortened, and the overall molding time is significantly shortened. For this reason,
The number of pallets, ie, the number of molds, circulating through the continuous path 59 can be reduced, which is beneficial in reducing manufacturing costs.

Furthermore, according to the apparatus of this embodiment, the material 15 is placed on the material mounting table 12 and separated from the upper mold 13 and the lower mold 14 until just before press forming, so that the material 15 and the molds 13 and 14 are separated from each other. reaction is prevented. Of course, it is not prevented that the reaction between the material 15 and the molds 13 and 14 occurs during press molding and the subsequent slow cooling, but when the temperature decreases after press molding, a reaction similar to that during press molding also occurs. First, in combination with the effect of shortening the reaction time mentioned above, this is beneficial for improving the durability of the mold.

Furthermore, since the apparatus of this embodiment is configured to transfer materials on the same pallet, there is no relative change in the position of the material mounting table 12 and the mold.
Positioning accuracy in handling of the suction fingers 19a, 19b can be easily obtained. Also, suction finger 1
9a and 19b are pallets 1 inside the molding chamber 59.
Since it is heated at the same time as 1, errors in handling positioning accuracy due to thermal expansion are less likely to occur.

Furthermore, according to the apparatus of this embodiment, the durability of the mold is guaranteed as described above, erosion of the molding surface is prevented, and the specularity of the molding surface is maintained for a relatively long period of time. Suitable for continuous production of high-precision optical elements.

(Effects of the Invention) As explained above, according to the present invention, the molded product after pressing is cooled by the rapid cooling means before reaching the normal slow cooling section, the cooling time of the molded product is significantly shortened, and the overall Molding time is much shorter than conventional equipment. Therefore, the number of pallets circulating in the molding chamber, that is, the number of molds for molding, can be reduced, which is advantageous in reducing manufacturing costs.

In addition, since the mounting table for the molding material and the mold are arranged on the same pallet, there is no change in the relative position between them when the pallet is moved. When transferring the molding material using this method, a highly reliable device can be obtained without deteriorating the positioning accuracy of handling even under high temperatures.

Therefore, the apparatus of the present invention is suitable for continuously manufacturing high-precision optical elements by press molding, and is also useful for shortening manufacturing time and reducing manufacturing costs.

[Brief explanation of drawings]

1 to 6 are diagrams showing a first embodiment of the optical element manufacturing apparatus of the present invention, FIG. 1 is an overall plan view thereof, and FIGS. 2 to 6 are diagrams of pallets in each process. FIG. 7 is a schematic cross-sectional view, and FIG.
8 is a schematic sectional view taken along the line A-A in FIG. 1, and FIG. 9 shows temporal changes in glass temperature in each process of the apparatus according to the embodiment of the present invention. FIG. 3 is a diagram of a time-temperature curve showing . 1... Material intake chamber, 2... Heating section, 3... Material transfer section, 4... Molding line, 5... Pressing section, 6
... slow cooling section, 11 ... pallet, 12 ... material mounting table, 13 ... upper mold, 14 ... lower mold, 25 ... transfer path, 59 ... molding chamber.

Claims (1)

[Claims] 1 Consists of an intake chamber for an optical element molding material, a heating section, a press section, an annealing section, and a molded product take-out chamber, and the optical element molding material supplied in the intake chamber and the molding material are press-molded. An optical element manufacturing apparatus comprising a pallet on which a molding die is disposed and a means for moving the pallet through the respective parts, wherein the heating part and the press part are constituted by a linear molding line, and the slow cooling part is constituted by a linear molding line. The method is characterized in that a means for rapidly cooling the molded product after press forming is provided in a connecting path which is arranged in parallel with the molding line and connects the molding line and the slow cooling section and moves from the press section to the slow cooling section. Optical element manufacturing equipment.