JP3135098B2 - Optical element molding equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to molding of an optical element for molding a highly accurate optical element such as an aspherical lens by pressing a heat-softened glass material with a pair of upper and lower mold members. It concerns the device.

[0002]

2. Description of the Related Art In recent years, as a method of processing an optical element such as a glass lens, a method of press-molding a heat-softened glass material using a molding die instead of a method of grinding and polishing has attracted attention. FIG. 3 shows the structure of a conventional molding apparatus for press-molding such an optical element. In FIG. 3, a molding die 100 is disposed in a molding device in which an atmosphere is generated using an inert gas, and the molding die includes an upper die member 102 and a lower die member 1.
04 and a body mold 106 for slidably holding the upper and lower mold members 102 and 104.
At 06, a heater 108 for heating itself and the mold members 102, 104 is provided. An opening hole 106a is formed in the body die 106, through which the glass material 130 is carried into the molding die 100, or the optical element whose molding has been completed is taken out from the inside. Is available.

[0003] In such a molding apparatus, the heat generated by the heater 108 is transferred to the upper mold member 1 via the body mold 106.
02 and the lower mold member 104, and are further added to the glass material 130 in the molding die via these, and this is heated to a desired press temperature. In this case, the glass material 130 is used for heat conduction from the lower mold member 104 and the upper mold member 1.
02, it is heated by a heat transfer method by radiant heat from the lower mold member 104 and the barrel mold 106 and convection from an inert gas surrounding the glass material 130.

[0004]

As described above, in the case where the diameter of the molded product is relatively small as shown in FIG. 3, the temperature distribution around the molding die (a pair of upper and lower die members) is An optical element that is uniform, has little variation, and is highly accurate can be obtained. However, when a large-diameter mold (upper and lower mold members) is used to mold a large-diameter optical element as shown in FIG. 4, the heater inserted into the body mold and the outer periphery of the mold are used. Since the distance to the part greatly differs depending on the position, the temperature distribution around the molding die varies, and as a result, the molded optical element becomes irregular due to irregular shape or habit. There is a problem that a good product can be produced.

As shown in FIG. 5, in a molding apparatus in which a plurality of pairs of molding dies (upper and lower mold members) are arranged in one body die and a plurality of optical elements are simultaneously produced, the body die itself is used. Since the temperature distribution varies, a considerable temperature difference occurs between the mold located at the center of the body mold and the mold located at the end, and the temperature difference between each mold (each pair of mold members) occurs. As a result, the quality of the molded product varies.

Therefore, as a countermeasure, the body mold is made larger, the distance from the heater to the mold (upper and lower mold members) is made as equal as possible, and the variation in the positional temperature distribution of the mold is reduced. Although it was conceivable to reduce it, this method increased the heat capacity by increasing the size of the barrel, increased the time required to heat and cool the mold, and reduced the production efficiency with respect to temperature control of the mold. It is not practical because it will invite you.

[0007]

SUMMARY OF THE INVENTION The present invention has been made on the basis of the above circumstances. It is an object of the present invention to provide an outer shape and a size of a torso even when a torso having a variation in temperature distribution depending on its position is used. Without changing the temperature, it creates an even temperature distribution in the body, avoids variation in the temperature distribution around the upper and lower mold members, and, in a body with multiple pairs of upper and lower mold members,
An object of the present invention is to provide an optical element molding apparatus devised so that a temperature difference between each molding die (each pair of mold members) can be suppressed.

[0008]

In order to solve the above-mentioned problems and to achieve the object, an optical element molding apparatus according to the present invention uses a glass material heated to a softened state by using an upper mold member and a lower mold member. In the molding device of the optical element for transferring the desired shape formed on the molding surface of each mold member to the surface of the glass material by pressing between the glass material, the barrel mold for guiding the upper mold member and the lower mold member is , Configured to heat the upper mold member and the lower mold member by heat conduction therefrom,
In addition, the body mold itself controls the heat flow and the direction of the heat flow.
Is formed to form a heat insulating layer .

[0009]

Therefore, the heat insulating layer makes the temperature distribution of the body mold in the outer peripheral portion of the upper and lower mold members uniform, and further, the uniformed heat is used by the (or each) pair of molding dies (the upper and lower molds). Press molding can be performed in a state where there is no variation in the temperature distribution in the upper and lower mold members, and in a state where there is no temperature difference between each pair of mold members. Obtainable. Moreover, the heat insulating layer can be easily provided and is very practical,
It is possible to cope with the molding of various kinds of products and the mold for taking plural pieces.

[0010]

Preferred embodiments of the present invention will be described below in detail with reference to the accompanying drawings. (First Embodiment) FIG. 1 shows an outline of a configuration of a molding die in an optical element molding apparatus according to a first embodiment, as viewed from above. B
Constitutes a gas heat insulating layer. This slit is a 0.5 mm wide cavity formed by wire cutting.
The transfer of heat in the heat insulating layer is heat conduction of the inert gas including convection and radiation. When this is expressed by one thermal conductivity, it is about 0.04 to 0.06 W / MK (a value obtained by an experiment and analysis unique to the present applicant). In comparison, there is a difference of about 1500 times. Of course, if done in a vacuum, the difference is even greater. By utilizing this large difference in thermal conductivity, the heat flow is arbitrarily controlled by squeezing or circulating the heat flow to create a desired uniform temperature distribution.

In the figure, the state of the heat flow and the heat flow at points 1 to 4 set on the periphery of the upper and lower mold members 12 in the body mold 11 will be described first. If the mold has no slits, points 1 and 3
The distance from the heater is small and the temperature is high. However, the temperatures of the points 2 and 4 are low because the distance from the heater 13 is large and at the same time, the heat escapes from the end of the shell 11. As a result, the temperature difference between points 1 and 3 and points 2 and 4
For example, it is about 20 ° C.

In view of this, slits A and B are provided in the body mold as shown in the drawing, utilizing the above-mentioned heat insulating effect. In this case, the slit B serves to restrict the heat flow from the heater in the width direction of the slit and scatter it in the length direction. Further, the slit A serves as a heat insulating member and retains heat escaping from the end of the body mold. As a result, point 1
In Nos. To 4, variation in the temperature distribution can be reduced to a difference of about 3 ° C. In addition, the temperature distribution has the effect of equalizing the temperature distribution during cooling for the same reason, and a high-quality optical element can be obtained.

In this embodiment, width 0.5 × length 12 mm and length 35 mm are adopted as slit specifications.
The width, length, and number for obtaining the same effect are not limited to this. Further, the shape is not limited to the elongated slit, and may be another shape such as a round hole. It is natural that the specific specification of the heat insulating layer is determined by a temperature measurement experiment, and this can easily be determined by using a commercially available heat transfer simulation. (Second Embodiment) FIG. 2 shows the appearance of a molding die in an optical element molding apparatus according to a second embodiment as viewed from above. In this embodiment, for one body mold 11,
A large-sized mold structure in which a plurality of pairs of upper and lower mold members 12 are arranged is shown. Are provided with slits A ′ and B ′ (although their shapes, dimensions, arrangements, etc. can be determined experimentally) as in the above embodiment. Here, the heater as a heating source is disposed outside the body mold. Comparing the variation in the temperature distribution between each pair with the conventional example (without slits), there was a difference of 14 ° C. in the conventional example, but in the forming die according to the present invention, The difference was 4 ° C.

[0014]

As described above, according to the optical element molding apparatus of the present invention, the heat insulating layer arbitrarily provided on the barrel mold allows the temperature distribution of each part of the barrel mold at the outer peripheral portion of the upper and lower mold members to be reduced. Uniform and further, the uniformed heat is transmitted to each mold member, so that the temperature distribution in the mold varies,
Further, the optical element can be molded in a state where there is no temperature difference between a plurality of pairs of mold members, and a high-quality optical element can be obtained. In addition, the heat insulating layer has a simple structure such as a slit, is easily provided, and is very practical. Therefore, in manufacturing a variety of products, the heat insulating layer is compatible with a multi-cavity molding die. This is advantageous.

[Brief description of the drawings]

FIG. 1 is a schematic plan view of a molding die showing a first embodiment of the present invention and a graph showing a temperature distribution at designated points.

FIG. 2 is a schematic plan view of a molding die showing a second embodiment of the present invention and a graph showing a temperature distribution at designated points.

FIG. 3 is a schematic cross-sectional plan view and a vertical cross-sectional side view of a conventional molding die.

FIG. 4 is a plan view showing a temperature distribution curve in a conventional molding die.

FIG. 5 is a plan view showing a temperature distribution curve in a conventional multi-cavity molding die.

[Explanation of symbols]

 Reference Signs List 11 body mold 12 molding mold (upper and lower mold members) 13 heater A, B slit

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-2-55237 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C03B 11/08 C03B 11/12

Claims (1)

(57) [Claims] 1. A glass material heated to a softened state is pressed between an upper mold member and a lower mold member, and a desired shape formed on a molding surface of each mold member is transferred to a surface of the glass material. In the optical device molding apparatus, the upper mold member and the lower mold member guiding the upper mold member are configured to heat the upper mold member and the lower mold member by heat conduction therefrom. A molding device for an optical element, wherein a slit for controlling a heat flow rate and a direction of a heat flow is formed in a mold itself to form a heat insulating layer .