JPH0369523A - Method and device for molding optical device - Google Patents

Abstract

PURPOSE:To improve the transferability and durability of a forming die at the time of press-molding a heated and softened glass material with a couple of the upper and lower molding dies by independently controlling the heating of the upper and lower glass material pressing surfaces in accordance with the molding deformation amt. at the glass material pressing surface. CONSTITUTION:A glass material 1 is heated 6 and 8 and softened, and the material 1 is conveyed (conveyor 2 and conveyor arm 3) between a couple of molding dies 14 and 15 and press-molded by the dies 14 and 15 to form an optical device. In this method, when the material 1 is heated, the heating of the material pressing surfaces is independently controlled in accordance with the desired deformation amt. at the material pressing surface. The heating amt. is changed by adjusting the relative distance between the material 1 and the heaters 6 and 8 or by adjusting the heating values of the heaters 6 and 8.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method and apparatus for molding an optical element, in which a glass material is softened by heating and then press-molded using a pair of molding dies.

[Conventional technology]

2. Description of the Related Art Conventionally, a method for forming an optical element is known in which a glass material is heated and softened, conveyed between a pair of molding molds, and then press-molded by the molding molds to obtain an optical element. In particular, for example, Japanese Patent Application Laid-open No. 62-27335 discloses that when heating a glass material, the surface and inside of the glass material are set to a predetermined temperature corresponding to 109 to 104.5 voids and 101.5 to 109 voids, respectively, and the surface A method of providing a temperature gradient between a part and an interior is disclosed. According to this method,
Both the glass material and the mold can reach a temperature below the transition point in a short time, the transfer is rapidly completed, and the molded product can be taken out from the mold immediately.

[Problem to be solved by the invention]

However, when using a glass material that has been previously ground and polished into a shape similar to the final shape, for example when obtaining an optical element with an aspherical surface on only one side, it is necessary to mold the pressing surface of the glass material on the side that will be aspherical. It is not necessary to heat the glass material pressing surface on the side that is to be made spherical in the same way as the aspherical side. Therefore, simply creating a temperature difference between the surface and the inside of the glass material as in the past is unnecessary for forming, and prevents the shape of the glass material from being significantly deformed just before being pressed due to unnecessary heating. Another object of the present invention is to provide a method and apparatus for molding an optical element, which has excellent transferability and durability of a molding die, and can shorten cycle time.

[Means to solve the problem]

In order to achieve the above object, the present invention provides an optical element in which a glass material is heated to soften it, the glass material is conveyed between a pair of molding molds, and then press-molded by the molding molds to obtain an optical element. In the method for molding the element, when heating the glass material, the heating of each glass material pressing surface is independently controlled depending on the required amount of deformation on the glass material pressing surface.

Further, the present invention provides a heating furnace equipped with heaters on the upper and lower sides to heat and soften the glass material, and a molding chamber equipped with a pair of upper and lower molding molds for press-molding the heated and softened glass material in the heating furnace. In an optical element molding device that is connected in series, the pressing surface of each glass material is softened and fluidly deformed according to the required amount of deformation on the pressing surface of the glass material, which improves transferability and molding properties. The durability of the mold has deteriorated significantly. In other words, the glass material softens and deforms when heated, so if the glass material is heated more than necessary, the shape of the glass material just before being pressed will be deformed.
By producing a larger amount of glass flow, transferability and durability for molding are adversely affected.

Furthermore, even when obtaining an optical element having a double-sided aspherical surface, conventionally both surfaces (both glass material pressing surfaces) are uniformly heated and softened regardless of the amount of aspherical surface. There was a problem similar to that of shaped optical elements. In other words, the necessary amount of deformation is determined for each surface according to the amount of asphericity, but since both sides are heated equally according to the required amount of deformation on one side, some sides are heated more than necessary. This had a negative effect on the transferability and the durability of the mold. Furthermore, unnecessary heating has been an impediment to shortening cycle time.

The present invention has been made in view of such conventional problems, and has made it possible to adjust the relative distance between the glass material and each heater in order to independently control the heating of the molding surface.

Furthermore, the present invention provides a heating furnace equipped with upper and lower heaters to heat and soften the glass material, and a molding chamber equipped with a pair of upper and lower molding molds for press-molding the heated and softened glass material in the heating furnace. In an optical element molding device that is connected in series, the heat generation amount of the upper and lower heaters is independently controlled in order to independently control the heating of each glass material pressing surface according to the required amount of deformation on the glass material pressing surface. Adjustable.

[For production]

According to the method and apparatus for molding an optical element having the above configuration, when heating the glass material, the upper glass material pressing surface and the lower glass material pressing surface are separated depending on the amount of molding deformation on the glass material pressing surface. Change the amount of heating for. That is, by adjusting the relative distance between the glass material and the heater, or by adjusting the amount of heat generated by the upper and lower heaters, the amount of heating is increased for the pressing surface of the glass material that has a larger amount of deformation. For smaller glass material pressing surfaces, the amount of force and heat is reduced.

This prevents the shape of the glass material just before pressing from being deformed more than necessary due to unnecessary heating.
Transferability and durability of the molding die are improved, and cycle time is also shortened.

〔Example〕

(First Embodiment) FIGS. 1 and 2 show an embodiment of the molding apparatus of the present invention. A glass material 1, which has been previously finished into a shape approximating the final shape by grinding and polishing, is conveyed. It is placed on a transport arm 3 via a tool 2.

The transport arm 3 is movable in its longitudinal direction, and is capable of transporting the glass material 1 through the heating furnace 4 into the molding chamber 5, and is also movable up and down.

The heating furnace 4 is provided with an upper heater plate 7 having an upper heater 6 installed on its inner surface, and a lower heater plate 9 having a lower heater 8 installed on its inner surface.

The lower mold 15 is connected to a drive device (not shown) and is provided to be movable up and down.

In this example, a single-sided aspherical lens with an aspherical surface M of 100 μm and made of glass type 5KII was molded using a molding apparatus having such a configuration.

First, with the pressing surface of the glass material on the aspherical side facing up,
The glass material work was placed on the transport arm 3 via the transport tool 2. Here, the glass material 1 has been processed by grinding and polishing in advance, and the glass material pressing surface (top surface), which is the aspheric side, is processed into an approximate spherical surface, and the glass material pressing surface (bottom surface), which is the spherical side, is approximately spherical. Processed to design value. Therefore, the aspherical side requires a heating amount corresponding to the aspherical amount of 100 μm, while the spherical side does not need to be deformed. For this reason,
The relative distance between the upper surface of the glass material 1 and the upper heater 6 was set to 10 mm, and the relative distance between the lower surface of the glass material 1 and the lower heater 8 was set to 30 mm. In this way, the present embodiment is composed of two side plates 1011 that independently change the relative distance between the glass material 1 and the heater 6.8 and close the plate 7.9 from the sides. Further, the upper heater plate 7 and the lower heater plate 9 each have a support rod 1213
It is connected to a drive device (not shown) such as a cylinder via a cylinder, and each is provided so as to be able to move up and down independently. As a result, each of the upper and lower heaters 68 can move toward and away from the glass material 1 independently, together with the vertical movement of the transport arm 3, and the glass material 1 and the heater 6.8 can be moved independently. It is provided so that the amount of heating can be adjusted by changing the relative distance. Furthermore, thermocouples (not shown) for temperature control are separately arranged in the center of each of the upper and lower heaters 6.8.
The temperature of each can be controlled independently, and the temperature can be set according to the required amount of heating.

On the other hand, the heating furnace 4 is connected with a molding chamber 5 in which the glass material 1 heated and softened in the heating furnace 4 is press-molded. In this molding chamber 5, an upper mold 14 and a lower mold 15 are coaxially opposed to each other so that the amount of heating is different. Both sides were set at 680°C.

The glass material 1 was heated in the heating furnace 4 for 1 minute, and then transported between the molds 1/1.15 by the transport arm 3, and was press-molded by raising the lower mold 15. As a result of measurement using a thermocouple, the temperature on the upper surface of the glass material 1 was approximately 655°C, and the temperature on the lower surface was approximately 600'C.

The shape of the glass material 1 after heating is 60 μm on average on the top surface,
The lower surface was deformed by an average of about 5 μm. Note that the lower molding molds 14 and 15 were required to be maintained at a temperature near the transition point of the glass material 1 in order to improve transferability.

In this embodiment, there is almost no need for deformation of the lower surface side of the glass material 1, and the temperature of the lower pressing surface of the glass blank is also lowered, so the temperature of the lower mold 15 for molding can be lowered accordingly. was completed. As a result, the lower mold 15 has less reaction with the glass and has improved durability. Furthermore, since the glass material 1 was heated only to the minimum necessary level and the temperature was relatively low, sink marks at the center, which are typical of press molding, were less likely to occur, and the yield of transferability was improved. Furthermore, since unnecessary heating is not performed during heating, there is less variation in shape change of the glass material 1 during heating, and therefore, variation in transferability is reduced. The lack of unnecessary heating also helped improve cooling efficiency and shorten cycle times.

(Second Example) In this example, similar to the first example, the molding apparatus shown in FIGS. 1 and 2 is used, and the heat generation amount of the upper and lower heaters 6.8 is independently controlled to The amount of heating applied to the pressing surface of the material was varied. Other configurations, functions, etc. are the same as those in the first embodiment, so explanations will be omitted.

When heating the glass element + A' 1, the distance between the upper heater 6 and the glass material 1 and the lower heater 8
The distance between the glass material 1 and the glass material 1 was 10 mm. Then, the upper heater 6 is set at 680'C according to the aspherical amount of 100 μm, and the glass material 1 is transferred to the transport arm via the transport tool 2 with the glass material pressing surface that is the aspherical surface facing upward. It was placed on 3. Here, the glass material 1 is ground and polished in advance so that the aspherical pressing surface (upper surface) of the glass material is processed into an approximate spherical surface, and the glass material pressing surface (lower surface) which is the flat side is processed into a flat surface. There is.

Therefore, the upper surface of the glass material 1 and the second side heater 6
The relative distance between the lower surface of the glass material 1 and the lower heater 8 was set to 10 mm, and the relative distance between the lower surface of the glass material 1 and the lower heater 8 was set to 50 mm. Further, the temperature was set preferentially on the aspherical side, and the upper heater 6 was set at 695°C. On the other hand, if the lower heater 8 is set to 695°C in the same way, the plane will be deformed by heating, so it is set to 600°C in consideration of the maximum relative distance to the glass material 1 of 50 mm. did.

Thereby, the flat side of the glass material 1 could be molded without deformation. Moreover, the temperature of the lower mold 15 could be set to a low temperature below the transition point, and the durability of the lower mold 15 could be improved.

In addition, when the center wall thickness of the glass material l is thick, the one-sided heater 8 has a diameter of 620 mm, considering that the lower surface side does not need to be deformed.
It was set at °C. As a result, the temperatures of the upper and lower surfaces of the glass material 1 were approximately 655° C. and approximately 600° C., respectively, as measured by thermocouples, which were the same as in the first example.

In this embodiment, the same effects as in the first embodiment can be obtained. In particular, when the transport arm 3 is given rigidity or when a positioning member is added between the transport arm 3 and the glass material 1 to improve the positioning of the mold 14, 15 and the glass material 1, the transport arm 3 However, in this embodiment, the temperature of both heaters 68 can be controlled separately. Therefore, the heat softening rate can be freely adjusted, which is effective, and shortening of cycle time can be realized.

(Third Example) In this example, a single-sided aspherical plano-convex lens made of glass type 5KII and having an aspherical surface M of 150 μm was molded using the molding apparatus shown in FIGS. 1 and 2.

If the amount of deformation is matched to the amount of deformation on the other side, the surface that does not need to be deformed will be deformed, and since the heat capacity is large, temperature distribution is likely to occur during cooling, causing problems such as requiring a long cooling time. According to this embodiment, not only can the cooling time be shortened, but also good transferability can be obtained. In particular, in this embodiment, the glass material 1 and the lower heater 8 are located at the longest distance, and by reducing the amount of heat generated by the lower heater 8, heating softening of the surface that does not require deformation is prevented. It is effective for Other effects similar to those of the first embodiment can be obtained.

The forming apparatus used in each of the above embodiments can change the relative distance between the glass material 1 and each heater 6, 8,
Although the amount of heat generated by each heater 6.8 can be controlled independently, a predetermined effect can be obtained even with either one of the configurations.

〔Effect of the invention〕

As described above, according to the method and apparatus for molding an optical element of the present invention, when heating a glass material, the amount of heating can be changed separately depending on the amount of molding deformation on the pressing surface of the glass material, and unnecessary It is possible to prevent the shape of the glass material just before being pressed from being unnecessarily deformed by heating, and it is possible to improve the transferability and the durability of the molding die, and to shorten the cycle time.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional front view showing an embodiment of an optical element molding apparatus according to the present invention, and FIG. 2 is a lateral sectional side view of the main parts in FIG. 1. 1... Glass material 3... Transfer arm 4... Heating furnace 5... Molding chamber 6... Upper heater 8... Lower heater 14... Upper mold for molding 15...・Bottom mold for molding

Claims (3)

[Claims] (1) In a method for molding an optical element in which a glass material is heated to soften it, the glass material is conveyed between a pair of molding molds, and an optical element is obtained by press-molding with the molding molds.
A method for molding an optical element, characterized in that when heating the glass material, heating of each pressing surface of the glass material is independently controlled according to a required amount of deformation on the pressing surface of the glass material. (2) A heating furnace equipped with upper and lower heaters is provided to heat and soften the glass material, and a molding chamber equipped with a pair of upper and lower molding molds for press-molding the heated and softened glass material is connected to the heating furnace. In an optical element molding apparatus comprising: An optical element molding device characterized by: (3) A heating furnace equipped with upper and lower heaters is provided to heat and soften the glass material, and a molding chamber equipped with a pair of upper and lower molding molds for press-molding the heated and softened glass material is connected to the heating furnace. In an optical element molding device, the amount of heat generated by the upper and lower heaters can be adjusted independently in order to independently control the heating of each glass material pressing surface according to the required amount of deformation on the glass material pressing surface. An optical element molding device characterized by: