JPH0445455B2 - - Google Patents

Description

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

(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 housing optical element materials in molds with a predetermined surface accuracy and press-molding them. 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 the material is held in the mold, a heating section is placed in a continuous furnace having a molding section and a cooling section. After heating and softening the molding material together with the mold in the heating section to a temperature at which it can be molded, the mold was pressed in the molding section, and then the state of the mold during pressing was maintained in the cooling section. This process involves cooling the raw material for molding until it reaches a glass transition temperature or lower, 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.

The present invention has been made to solve these problems, and it prevents erosion of the mold by glass components in press molding, maintains the high precision surface of the mold, and improves the quality of the mold. An object of the present invention is to provide a method for manufacturing an optical element that does not reduce durability.

Furthermore, the present invention provides a method for manufacturing an optical element that can continuously manufacture high-precision optical elements by preventing erosion by glass components of a mold during press molding and maintaining the surface precision of the mold. The purpose is to provide.

(Means for Solving the Problems) In order to solve the above-mentioned problems, the optical element manufacturing method of the present invention includes a plurality of molds in which molds are placed in a molding chamber having at least a heating step and a pressing step. A method for manufacturing an optical element, in which a preformed material placed in the mold is continuously press-molded by storing a pallet and transferring each of the steps, wherein the preformed material is separated from the mold. The preformed material is placed in a predetermined position on the pallet and transferred to the heating process, and then transferred to the press process when the preformed material is transferred into the mold, and then the press process is performed. It is characterized by pressing a mold.

(Function) In the present invention, the preformed material refers to a material for molding an optical element that has been processed to a predetermined surface roughness accuracy or higher before the manufacturing process of the present invention.

As described above, the present invention is configured such that a plurality of pallets on which molding molds are placed are transferred into a molding chamber and subjected to predetermined processing in a heating process and a pressing process in the molding chamber. Therefore, continuous molding of optical elements is possible.

Moreover, in the continuous molding of optical elements as described above, the preform material is heated in a state where the mold material and the mold are separated during the heating step where the reaction between the preform material and the mold is most significant. After that, it is transferred to a pressing process.

Therefore, compared to a molding method in which the preform material is heated and softened in the mold, the time spent by the reaction of the molding material in the mold is significantly shortened.
It becomes possible to maintain a high precision surface of the mold.

Thus, in the present invention, an optical element with a high-precision surface can be obtained by polishing the surface of the mold with high precision, and furthermore, with the above-described configuration, the high-precision surface of the mold can be maintained for a relatively long period of time. This makes it suitable for continuous molding of optical elements as described above.

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

1 to 6 are diagrams showing a device applied to an embodiment of the present invention. A plan view of the entire device is shown in FIG. 1, and sectional views of each part are shown in FIGS. 2 to 6.
It is shown in FIG.

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 arranged in the same line, and a slow cooling section 6 is arranged in parallel with these lines.

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. Also, lower mold 1
A guide member 27 is provided on the outer periphery of the mold 4 for guiding the mounting movement of the upper mold 13 and for positioning the upper mold 13.
is fixed so as to slightly protrude from the upper end of the lower mold 14. 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 pallets 11 in the above-mentioned path, a pushing cylinder 51 is provided in the first transfer chamber 21, and the pallets 11 are moved to the press section 5 by this pushing cylinder.
The second transfer chamber 22 is provided with an extrusion cylinder 53 and a drawer cylinder 52. The pallet 11 moved to the press section 5 by the drawer cylinder 52 is drawn out to the second transfer chamber 22, and the pallet 11 is drawn out by the extruder cylinder 53. The pallet 11 moved to the second transfer chamber 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 is provided with a push cylinder 55 and a drawer cylinder 56, and the pallet 11 that has been moved to just before the fourth transfer chamber 24 is pulled out to the fourth transfer chamber 24 by the drawer cylinder 56. Ru. Next, the pallet 11 moved to the fourth transfer chamber 24 is pushed out again to the first transfer chamber 21 by the extrusion cylinder 55.

In this manner, the pallet 11 is transferred to each process by the above-described extrusion or withdrawal operation of the cylinder, and can be moved within the molding chamber 59 of the present apparatus. The pallet 11 is placed on a rail (not shown) provided in the molding chamber 59, and is moved on the rail by extrusion or extraction of the cylinder.

Next, each part of the molding chamber will be explained. Lifting hands 16 and 20 (FIG. 4) are provided in the material transfer section 2 and the molded product removal chamber 7 to lift the upper mold 13 to the lower mold 14 at a required distance.
This lifting hand is moved up and down by a lifting means (not shown). Furthermore, the material transfer unit 3 includes the material 1 placed on the material mounting table 12 in the material intake room 1.
A suction finger 4 is provided for transferring the mold 5 onto the lower mold 14 (FIG. 4), and after the upper mold 13 is once lifted by the operation of the lifting hand 16, the suction hand 4 is activated. Material 15 is lower mold 1
4 to a predetermined position. This suction finger 4 is arranged so that the material mounting table 12 on the pallet 11 and the lower mold 14 are arranged so that the material 15 is accurately placed at a predetermined position on the lower mold 14 when the material 15 is transferred as described above. It is configured to operate with a constant stroke that translates exactly the length of a predetermined interval.

In addition, in the material intake chamber 1 and the molded product removal chamber 7, the material 15 is placed on the mounting table 12, and the molded product 18 is placed on the mounting table 12.
Suction finger 19 for taking out the product 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 molding chamber 59 is evacuated and then filled with N ₂ to prevent the mold materials for molding the upper mold 13 and 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 4 are
It is also necessary to provide sufficient shielding to the sliding portions between the press rod 17 and the outer wall of the furnace body 59.

Further, in this apparatus, although not shown in the drawings, it is necessary to provide an atmosphere exchange chamber so that outside air does not invade the inside of the molding chamber 59 when the material 15 is taken into the material intake chamber 1.

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 mentioned 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 has been raised, the material 15 is passed through the atmosphere replacement chamber in the material intake chamber 1 and placed on the mounting table 12 of the pallet 11 in the material intake chamber 1 by the suction finger 19 as shown in FIG.

Next, as described above, the extrusion cylinders 51, 5
3, 54, 55 and drawer cylinders 52, 56
Each time the pallets 11 are sequentially sent from the molded product take-out chamber 7 to the material intake chamber 1, 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 and the upper mold 1
When the material 15 and the lower mold 14 are heated to a temperature required for press forming near the material transfer section 3, the material 15 is transferred to the lower mold 14.

In addition, at this time, the material 15, the upper mold 13, and the lower mold 1
It is desirable that the temperature is approximately the same as that of 4. 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.

Then, in the material transfer section 3, as shown in FIG. 4, the upper mold 13 is lifted by the lifting hand 16, and then the material 15 is sucked by the suction fingers 4 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 17 is activated to press the upper die 13 with a predetermined press pressure to perform press forming on the material 15.

Next, the pressure of the press rod 17 is released, and
The pallet 11 is moved from the press section 5 to the vicinity of the outlet of the press section 5 by the operation of the extrusion cylinder 51 while the upper die 13 maintains its state during pressing.

Furthermore, this pallet 11 is pulled out by the drawer cylinder 52 and moved to the second transfer chamber 22, and then pushed out by the extrusion cylinder 53 and transferred to the transfer chamber 23 via the transfer path 25.

Next, the pallet 11 is transferred to the extrusion cylinder 54.
By extrusion, the molded product is pushed out in the direction of the take-out chamber 7, but there are other pallets 1
Since the pallets 11 are arranged in an array, the pallets 11 are placed in the slow cooling section 6 while the above-mentioned operation continues.
The molded product 18 held in the upper mold 13 and the lower mold 14 passes through the annealing section 6, where it is gradually cooled. The pallet 11 thus moved to the leading position of the slow cooling section 6 reaches the molded product take-out chamber 7 by the drawer cylinder 56.

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 19. Then, the pallet 11 from which the molded products have been taken out is transferred to the extrusion cylinder 55.
By extrusion, the material is transferred to the material intake chamber 1 via the circuit 26.

According to the embodiment apparatus as described above, the material 15 is placed on the material mounting table 12 and separated from the upper mold 13 and the lower mold 14 until the material is transferred immediately before press molding. 15 and type 1
Reactions with 3 and 14 are prevented. Of course, during press molding and subsequent slow cooling, the material 15 and mold 1
Although reactions with 3 and 14 are not prevented from occurring, when the temperature is lowered after press molding, a reaction similar to that during press molding also occurs, and in combination with the effect of shortening the reaction time mentioned above, the durability of the mold is improved. be beneficial to

In addition, since this device is configured to transfer materials on the same pallet, the material placement table 12
There is no relative change in the position of the suction finger 4 and the mold, making it easier to position the suction finger 4 in handling. Furthermore, since the suction fingers 4 are heated simultaneously with the pallet 11 inside the molding chamber 59, errors in handling positioning accuracy due to thermal expansion are less likely to occur.

Furthermore, according to this device, the durability of the mold is guaranteed as mentioned above, erosion of the molding surface is prevented, and the specularity of the molding surface is maintained for a relatively long period of time, so high-precision optical Suitable for continuous manufacturing of devices.

Hereinafter, another embodiment applied to the present invention will be described with reference to FIG. 7.

The optical element manufacturing apparatus in this embodiment was configured to have a linear process path in the above embodiments and move the pallets using an extrusion or draw-out cylinder, whereas the optical element manufacturing apparatus in this embodiment uses a rotary table to rotate and move the pallets. It has a configuration that performs the following. As shown in FIG. 7, the overall configuration includes a material intake chamber 31 (also serving as a molded product removal chamber), a heating section 32, a material transfer section 33, and a press section 34 on a rotary table 36 driven by a drive device (not shown). and an annealing chamber 35, and a pallet 37 is placed on this table.
are arranged at a constant pitch, and a material mounting table 38 and a mold 39 are arranged on this pallet 37 at a predetermined interval. Similar to the above embodiment, for this device,
Press molding is performed using suction fingers and lifting hands. The basic operation and effects of this device are similar to those of the above embodiments, except that the device operates in a rotary table format to move pallets.

(Effects of the Invention) As explained above, according to the present invention, erosion due to reaction with the preforming material of the molding mold is prevented,
It is effective in maintaining the durability of the molding die and the accuracy of the molding surface.

Therefore, the present invention makes it possible to maintain the precision of the mold surface required for continuous molding of optical elements, and is suitable for continuously manufacturing high-precision optical elements by press molding.

[Brief explanation of drawings]

1 to 6 are diagrams showing a first embodiment of the apparatus applied to the method of manufacturing an optical element of the present invention, in which FIG. 1 is an overall plan view thereof, and FIGS. 2 to 6 FIG. 2 is a schematic cross-sectional view of a pallet in each step of
FIG. 7 is an overall schematic plan view showing another embodiment of the present invention. 1, 31...Material intake chamber, 2,32...Heating section, 3,33...Material transfer section, 5,34...Press section, 6,35...Slow cooling section, 11,37...Pallet , 12, 38...Material mounting table, 13...Upper mold, 14...Lower mold.

Claims (1)

[Claims] 1. Continuously press-forming the preformed material placed in the mold by accommodating a plurality of pallets on which molds are placed in a molding chamber having at least a heating process and a pressing process and transferring each of the processes. A method for manufacturing an optical element, wherein the preformed material is placed in a predetermined position on the pallet separated from the molding die, the heating step is carried out, and then the preliminary formed material is transferred to the pressing step. A method for manufacturing an optical element, comprising transferring a molding material into the mold, and then pressing the mold in the pressing step.