JPH0645466B2 - Method for molding optical glass parts - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for molding an optical glass component, which comprises softening a molding material for an optical glass component by heating and then press-molding it with a molding die.

[Prior Art] Conventionally, most of optical glass parts such as lenses, prisms, and filters have been formed by a method mainly including grinding and polishing treatment of a molding material of the optical glass part. However, such processing requires a considerable amount of time and skill, and it has been difficult to manufacture a large amount of optical glass parts in a short time. Therefore, for example, Japanese Patent Laid-Open No. 61-13252
As disclosed in Japanese Patent Publication No. 5, a method has been developed and implemented in which a molding material for an optical glass component is inserted and arranged in a pair of molding dies, and an optical glass component such as a lens is molded by simply pressing the material. Has been done.

In the apparatus used in such a molding method, for example, as shown in FIG. 9, a molding die is composed of a cylindrical upper die 1 and a lower die 2 which are paired and are coaxially opposed to each other. ing.
Molding surfaces 1a and 2a having a shape corresponding to a desired lens shape are formed on the respective facing surfaces of the upper mold 1 and the lower mold 2.
The upper mold 1 and the lower mold 2 are connected to a drive device (not shown) so that they can move toward and away from each other.
Further, cylindrical mold releasing members 3 and 4 are slidably fitted to the outer peripheral surfaces of the upper mold 1 and the lower mold 2, respectively. These mold release members 3 and 4 are movable toward and away from each other, like the upper and lower molds 1 and 2.

In the molding apparatus having the above-mentioned configuration, the molding material made of glass gob is heated and softened, and this is carried between the upper and lower molds 1 and 2, and as shown in FIG. 2. Press molding by 2. During such press molding, the release members 3 and 4 are molded lenses 5 obtained by the press molding.
Have not been contacted. Next, when the press molding is completed,
The upper mold releasing member 3 descends to press the outer peripheral portion 5a of the molded lens 5 downward, the upper mold 1 rises and is separated from the lens portion 5b of the molded lens 5, and the lower mold releasing member 4 rises. Then, the outer peripheral portion 5a of the molded lens 5 is pressed upward, the lower mold 2 descends and is separated from the lens portion 5b of the molded lens 5, and the molded lens 5 after pressure molding in the optical contact state is released. .

[Problems to be Solved by the Invention] According to the above-described conventional molding method, the lens portion 5b of the molded lens 5 is cooled to the mold temperature of the upper and lower molds 1 and 2 during the press molding. However, since the release members 3 and 4 are not in contact with the outer peripheral portion 5a of the molded lens 5 during the press molding, and the temperature of the release members 3 and 4 is not controlled, the cooling rate of the outer peripheral portion 5a is , Is significantly slower than the cooling rate of the lens part. Therefore, there is a problem that a non-uniform temperature portion is generated in the molded lens 5 and a sink mark is generated around the lens portion 5b. The present invention has been made in view of such problems, and the molding die is brought into contact by cooling the portion other than the portion with which the molding die comes into contact in the molding material during press molding. The purpose of this is to prevent sink marks from being generated around the part.

[Means for Solving Problems] In order to solve such conventional problems, the present invention provides a molding die in which a molding material of an optical glass component heated to a predetermined temperature is lower than the molding material temperature. In a method for molding an optical glass component, which comprises press molding and releasing a press-molded product by a mold release member, the mold release member is heated to a predetermined temperature of 200 ° C lower than the mold temperature of the molding die to the mold temperature. In addition to the control, the release member is pressed while being brought into contact with the molding material.

Here, when the temperature of the release member is higher than the mold temperature,
The cooling effect is reduced and sink marks are generated in the peripheral portion of the die contact portion. In addition, the temperature of the release member is (mold temperature −
When the temperature is lower than 200 ° C) ° C, the molding material has an internal non-uniform temperature portion, and sink marks are generated in the peripheral portion of the die contact portion.

[Operation] In the method for molding an optical glass component of the present invention, the release member is also in contact with the molding material during press molding. Then, the release member is controlled to a predetermined temperature within a range of a temperature lower than the mold temperature of the molding mold by 200 ° C. to the mold temperature. As a result, during the press molding, the portion of the molding material other than the portion where the molding die abuts is also cooled in the same manner as the abutting portion of the molding die. Therefore, the press-molded product does not sink.

[Examples] Hereinafter, the present invention will be described in detail based on examples shown in the drawings.

FIGS. 1 to 4 are views showing a molding apparatus in an embodiment of the molding method of the present invention. For molding from a cylindrical upper mold 11 and a lower mold 12 which are paired and are coaxially opposed to each other. The mold is made up. Formed on the respective facing surfaces of the upper mold 11 and the lower mold 12 are molding surfaces 11a and 12a having a high surface shape and surface roughness corresponding to a desired optical element. In this embodiment,
A case where SF-8 glass is used as an optical glass material and a biconvex lens of R11.4 is molded is shown. Upper mold 11 and lower mold 12
And are connected to a drive device (not shown) so that they can move toward and away from each other.

In addition, on the outer peripheral surfaces of the upper mold 11 and the lower mold 12, substantially cylindrical mold releasing members 13, whose tip portions 13a, 14a are thin,
14 are slidably fitted together. These release members 13 and 14 can be moved toward and away from each other like the upper and lower dies. Furthermore, each of the release members 13 and 14 includes
Heaters 15 and 16 with thermocouples are built in, respectively.

Reference numeral 17 denotes a carrier for mounting and carrying a molding material 18 made of a thick-walled disc-shaped glass gob. A through hole 19 having a diameter larger than the outer diameter of the lower mold 12 of the pressing mold is formed in the center of the carrier table 17. Further, the through hole 19 is formed with a receiving portion 20 including a step portion for mounting and locking the molding material 18 on the upper opening edge portion thereof. The carrier 17 moves from the heating furnace (not shown) to the space between the upper and lower molds 11 and 12 and the slow cooling furnace (not shown) while mounting the molding material 18.

In the molding apparatus having such a configuration, the receiving portion 2 of the carrier table 17 is provided.
The molding material 18 is placed and locked at 0, and the molding material 18 is loaded into a heating furnace to heat and soften the molding material 18 to 570 ° C. Then, as shown in FIG. 2, the molding material 18 is carried in between the upper and lower molds 11 and 12. Here, upper and lower molds 1
1, 12 are heated so that the mold temperature is 370 ° C,
The mold releasing members 13 and 14 are also heated to 370 ° C. by the thermocoupled heaters 15 and 16.

In connection with the loading of the molding material 18, the upper and lower molds 11, 1
At the same time that the drive device connected to 2 starts to operate, the drive device connected to the release members 13 and 14 also starts to operate.
Then, as shown in FIG. 1, the molding material 18 is press-molded for 15 seconds while aligning the tips of the tip portions 13a, 14a of the release members 13, 14 with the tips of the upper and lower dies 11, 12, and While transferring the shape, the molding material 18 is cooled to 370 ° C.

In order to release the molded lens 21 thus obtained, as shown in FIG. 3, the mold releasing members 13 and 14 hold the outer peripheral portion 21a of the molded lens 21 and hold the upper and lower molds 1 together.
The lenses 1 and 12 are separated from the lens portion 21b of the molded lens 21. Then, as shown in FIG.
4 is separated from the outer peripheral portion 21 a of the molded lens 21, and the molded lens 21 is placed on the carrier table 17. Then, the molded lens 21 is carried into a slow cooling furnace (not shown) by the movement of the carrier, and is gradually cooled.

FIG. 5 is an interference pattern showing an interference image of the glass lens obtained by the above-mentioned embodiment by a Fizeau interferometer. The glass lens 22 is a lens having good transferability without a sink mark in its peripheral portion. I know there is.

On the other hand, FIG. 6 shows an interference pattern of an interference image of a glass lens obtained by the conventional molding method in which the release member is not brought into contact with the molding material during the press molding. As can be seen from FIG. 6, according to the conventional method, a sink mark is generated around the glass lens 23.

FIGS. 7 and 8 show a molding apparatus in another embodiment of the molding method of the present invention. The same parts as those in the above embodiment are designated by the same reference numerals as those in FIGS. 1 to 4 and their explanations are omitted. To do.

In this embodiment, the release member 24 fitted on the outer peripheral portion of the upper mold 11 is different from that of the above-mentioned embodiment. That is,
The upper part of the release member 24 is shaped such that its tip end portion 24a fits into the outer peripheral portion of the upper end of the molding material 18 during press molding. Therefore, as shown in FIG.
Has an effect as a barrel mold that regulates a part of the outer periphery of the molded lens 21 during press molding.

In addition, in each of the above-described embodiments, the two release members 13 (2
4), 14 was made to contact the molding material 18,
The present invention is not limited to such an embodiment, and only one of the upper and lower mold release members may be brought into contact with the molding material depending on the desired shape of the press-molded product. Also,
The position of the tip of the release member may be any position as long as it comes into contact with the molding material during press molding, and does not necessarily have to be the same position as the tip of the molding die.

[Effects of the Invention] As described above, according to the method for molding an optical glass component of the present invention, the release member is controlled to a predetermined temperature of 200 ° C. lower than the mold temperature of the mold for molding to the mold temperature. At the same time, since the release member is press-molded while being in contact with the molding material, a sink product is not formed in the peripheral portion of the die contact portion of the press-molded product, and a molded product having good transferability is obtained. be able to.

[Brief description of drawings]

1 to 4 show a molding apparatus in one embodiment of the molding method of the present invention, and FIG. 1 is a longitudinal sectional view during press molding,
2 is a vertical cross-sectional view before press molding, FIG. 3 is a vertical cross-sectional view after mold release, FIG. 4 is a vertical cross-sectional view after completion of molding, and FIGS. 5 and 6 are respectively FIG. An interference pattern showing an interference image in each glass lens molded by the example shown in the example and the conventional example, FIGS. 7 and 8 show a molding apparatus in another example of the present invention, and FIG. FIG. 8 is a vertical cross-sectional view before molding, FIG. 8 is a vertical cross-sectional view during press molding, and FIG. 9 is a vertical cross-sectional view during press molding of a molding apparatus in a conventional molding method. 11, 24 ...... Upper mold 12 ...... Lower mold 13,14 ...... Releasing member 18 ...... Molding material 21 ...... Molding lens

Claims (1)

[Claims] 1. Molding of an optical glass component in which a molding material for an optical glass component heated to a predetermined temperature is press-molded by a molding die whose temperature is lower than the molding material temperature, and a press-molded product is released by a release member. In the method, controlling the release member to a predetermined temperature of 200 ° C. lower than the mold temperature of the molding die to a mold temperature, and press-molding the release member while contacting the mold material. A method for forming a characteristic optical glass component.