JPH08245227A - Device for forming optical element - Google Patents

Abstract

PURPOSE: To prevent the center misalignment of formed elements by forming >=3 positioning surfaces on either one or both of upper and lower drum molds and providing the above device with lateral misalignment preventive members which come into sliding contact with the respective positioning surfaces at the time when the upper and lower drum molds come near to each other. CONSTITUTION: The upper and lower drum molds of this device for forming optical elements which heats and forms the optical elements by bringing the upper and lower molds closer to each other are formed with >=3 positioning surfaces intersecting orthogonally with the direction where the upper and lower drum molds attach and detach. The device described above is provided with the lateral misalignment preventive members which come into sliding contact with the respective positioning surfaces at the time when the upper and lower molds come near to each other. Preforms 31 are placed on lower dies 22 in the opened state of an upper drum mold 10 and a lower drum mold 20. The upper drum mold 10 is lowered by a lifting cylinder rod 15 to the state that the front end of the lateral misalignment preventive plates 16 and the positioning surfaces 26 are slightly engaged. Simultaneously a quartz tube 32 and a heater 33 are lowered. The upper drum mold is further lowered at the point of the time the upper drum mold 10 and the lower drum mold 20 attain a suitable temp. The inside surfaces 16a of the lateral misalignment preventive plates come into sliding contact with the positioning surfaces 26 in a tight contact state. As a result, the lateral misalignment and relative rotation are prevented.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an optical element molding apparatus used for simultaneously press-molding a plurality of heated and softened optical element materials and then cooling them to form an optical element having a required shape.

[0002]

2. Description of the Related Art In this type of optical element molding apparatus, a plurality of optical element molding dies are supported by upper and lower body dies, and each optical element molding is performed with the upper and lower body dies open. The optical element material positioned between the molds is heated and softened by bringing the upper and lower body molds close to each other, and finally molding is performed with the upper and lower body molds closed. In the conventional apparatus, the upper and lower body dies are aligned at room temperature to perform centering and alignment of each optical element forming die, and the optical element forming die is fixed to the body die with a fixing screw or the like. After that, the upper and lower body dies were opened and the forming process was performed. However, in this conventional apparatus, when the barrel die and the optical element molding die are actually heated and molded, the heat causes expansion and slack in each member, and the force at the time of press molding causes the upper and lower barrel die and the optical element molding die. There was a risk of lateral displacement in the mold. When the lateral displacement occurs, an optical element with a misaligned core whose upper and lower molding surfaces are displaced is molded.

[0003]

SUMMARY OF THE INVENTION It is an object of the present invention, based on the above-mentioned awareness of the problems, to provide an apparatus in which lateral displacement of the barrel mold and the optical element molding die is unlikely to occur during press molding.

[0004]

SUMMARY OF THE INVENTION The present invention has been made based on the idea of mechanically preventing lateral displacement between upper and lower barrel dies, and between the upper and lower optical element molding dies supported by the upper and lower barrel dies, respectively. In an optical element molding device for heating and molding the positioned optical element material by bringing the upper and lower body dies into close proximity to each other, one or both of the upper and lower body dies are positioned around the upper and lower body dies, and the upper and lower body dies are provided. A total of three or more positioning surfaces, which are orthogonal to the approaching / separating direction of the mold, are formed, and one or both of the upper and lower barrel molds are
It is characterized in that a lateral displacement prevention member is provided which comes into sliding contact with the respective positioning surfaces when the upper and lower body dies approach each other. It is preferable that the positioning surface and the lateral deviation prevention member are provided at substantially equal angular intervals around the upper and lower body dies. In addition, it is preferable that the positioning surface and the lateral deviation prevention member are provided in a mode of restricting relative rotation of the upper and lower body dies in a sliding contact engagement state of the both. By forming at least one of the flat surfaces, it is possible to reliably prevent rotation of the upper and lower body dies. Preferably, the three-sided surface has a triangular shape in plan view, and the four-sided surface preferably has a rectangular shape.
Although it may have more sides, it is preferable to arrange the upper and lower body dies so as to surround the periphery of the body dies such that relative rotation does not occur. When the upper and lower barrel dies are provided with three or more positioning surfaces and a lateral displacement prevention member in this manner, lateral displacement of the barrel die during molding is prevented, and thus core misalignment of the optical element molded by the optical element molding die is also prevented. To be prevented. Further, by providing the positioning surface and the lateral displacement prevention member so that relative rotation of the upper and lower body dies does not occur, it is possible to more reliably prevent the misalignment of the optical element.

It is simple in construction that the positioning surface is provided on one of the upper and lower body dies and the lateral displacement prevention member is provided on the other of the upper and lower body dies. In this case, in addition to configuring the lateral displacement prevention members corresponding to the respective positioning surfaces as separate members, all the lateral displacement prevention members can be provided in one outer body mold that surrounds either one of the upper and lower body molds. . It is desirable that the barrel die, the optical element molding die, and the lateral displacement prevention member are made of materials having the same expansion coefficient in order to more reliably prevent lateral displacement due to heat.
When the fixing screw is used, the same applies to the fixing screw.

Further, in order to improve the positional accuracy of the optical element molding die and the positioning surface, a plurality of insertion and fixing holes which are formed in the upper and lower body dies and which are inserted and fixed to the optical element molding die and which form a pair, and the positioning surface Is preferably machined simultaneously while the two body dies are brought close to each other and held integrally.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described below with reference to illustrated embodiments. 1 and 2 show a first embodiment of the present invention. This apparatus includes an upper body mold 10 and a lower body mold 20. A plurality of (four in this embodiment) a plurality of upper body molds 10 and a lower body mold 20 are associated with each other in vertical positions. Insertion fixing holes 11 and 21 of the optical element molding die are formed. The insert fixing holes 11 and 21 are respectively provided in the upper mold 1 for molding an optical element.
2 and the lower mold 22 are inserted and fixed. The optical element molding upper die 12 has a flange 12a at the upper end thereof, and the lower die 22
Has a flange 22a at the lower end. Flange 12
a is clamped and fixed between the upper end surface of the upper body die 10 and the upper die base 13, and the flange 22 a is provided with a spacer 24.
It is clamped and fixed between the lower end surface of the lower body die 20 and the lower die base 23. The spacer 24 sets the gap between the optical element molding upper die 12 and the optical element molding lower die 22. The upper mold base 13 is connected to the lifting cylinder rod 15, and the lower mold base 23 is connected to the lifting cylinder rod 25.

FIG. 3 shows a single shape of the lower die 22 for molding an optical element. The base material of the optical element molding lower die 22 is made of, for example, cemented carbide tungsten carbide WC, and after the molding surface is ground by an ultra-precision lathe, the surface roughness is further adjusted by using a diamond abrasive, and Then, a platinum film 22b of about 1 μm is formed by sputtering. The platinum film 22b improves the heat resistance, oxidation resistance and wettability of the base material. The same applies to the structure on the optical element molding upper die 12 side.

A positioning surface (positioning plane) 26, which is a feature of the present invention, is formed around the lower body mold 20.
A lateral displacement prevention plate (flat plate) 16 corresponding to the positioning surface 26 is fixed to the upper body mold 10. Positioning surface 2
Reference numeral 6 denotes a surface orthogonal to the contacting / separating direction of the upper body mold 10 and the lower body mold 20, and in plan view, as shown in FIG. It is configured. A similar positioning surface 17 is formed on the upper body mold 10 at the same position as these positioning surfaces 26 in plan view, and the lateral misalignment prevention plate 16 is brought into close contact with the positioning surface 17 by the fixing screw 18. It is fixed. Therefore, the inner surface 16 a of the lateral displacement prevention plate 16 and its extension plane are located on the same plane as the positioning surface 26. Lateral displacement prevention plate 1
A taper guide surface 16b is formed on the inner surface of the lower end portion of 6 to incline upward, and a taper guide surface 26a is also formed on the upper end of the positioning surface 26. Has been formed.

The insertion fixing hole 11 and the positioning surface 17 of the upper body mold 10, and the insertion fixing hole 21 and the positioning surface 2 of the lower body mold 20.
No. 6 is machined at the same time in a state where the upper body mold 10 and the lower body mold 20 are brought into contact with each other and are mechanically coupled. By adopting such a processing method, the positional accuracy of the insertion fixing hole 11 and the insertion fixing hole 21, and the positioning surfaces 17 and 26 can be kept high. Further, the upper body mold 10, the optical element molding upper mold 12, the lower body mold 20, and the optical element molding lower mold 2
2, it is preferable that the lateral deviation prevention plate 16 and the fixing screw 18 are made of materials having the same coefficient of thermal expansion. Specifically, the upper body mold 10, the optical element molding upper mold 12, the lower body mold 2
0, the optical element molding lower die 22, and the lateral deviation prevention plate 16 are
For example, the fixing screws 18 may be made of the same cemented carbide, and the fixing screw 18 may be made of a tungsten alloy having the same coefficient of thermal expansion.

In the present apparatus having the above-mentioned structure, the optical element (lens) is molded as follows. Upper body type 1 as shown in Fig. 1.
0 and the lower body mold 20 are opened, the preform (optical element material) 31 is placed on the platinum film 22b of each optical element molding lower mold 22 by the work supply / extraction arm 30. next,
By the lifting cylinder rod 15, the upper body die 1 is brought into a state in which the tip of the lateral deviation prevention plate 16 and the positioning surface 26 are slightly engaged.
0, and at the same time, as shown in FIG.
The quartz tube 32 and the heater 33 are lowered around the lower body mold 20. The quartz tube 32 forms a closed chamber around the upper body die 10 and the lower body die 20, and the quartz tube 32 is filled with nitrogen gas, and heating is started by the heater 33.
When the temperatures of the upper body mold 10 and the lower body mold 20 reach appropriate temperatures, the elevating cylinder rod 15 further lowers the upper body mold 10 with respect to the lower body mold 20. The temperatures of the upper body mold 10 and the lower body mold 20 are detected by thermocouples 19 and 29.

In the process of lowering the upper body mold 10 with respect to the lower body mold 20 and crushing the preform 31,
The inner surface 16a of the lateral displacement prevention plate 16 of the upper body die 10 is brought into sliding contact with the positioning surface 26 of the lower body die 20 in a close contact state. For this reason, when a molding pressure is applied between the upper body mold 10 and the lower body mold 20, between the upper body mold 10 and the lower body mold 20, that is, between the upper mold 12 and the lower mold 22 for molding the optical element. No lateral displacement or relative rotation occurs, and no misalignment occurs in the molded optical element formed by molding the preform 31. After molding, when the temperature falls below the glass transition point, the quartz tube 3
The nitrogen gas in 2 is removed, the upper cylinder mold 10 is raised by the elevating cylinder rod 15, the upper cylinder mold 10 and the lower cylinder mold 20 are opened, and the molded product is taken out via the work supply / extraction arm 30.

5 and 6 show a second embodiment of the present invention, in which an outer body die 40 is separately provided on the outer periphery of the lower body die 20. The outer body die 40 integrally has four flat surfaces 40 a that are in sliding contact with the four positioning surfaces 17 around the upper body die 10. That is, it can be considered that the outer body die 40 integrally includes the four lateral deviation prevention portions 41 having the flat surface 40 a that is in sliding contact with the positioning surface 17. Also in this embodiment, it is possible to obtain the same effect as that of the first embodiment.

In the above embodiment, the upper body mold 10 and the lower body mold 2
No. 0 is provided with all the positioning surfaces 17 and 26, and the other is provided with all the lateral deviation prevention plates 16 and lateral deviation prevention members 41 (outer body mold 40).
The same operational effect can be obtained even if the 0 and lower body molds 20 are provided with two positioning surfaces and two lateral displacement prevention members.

[0015]

According to the present invention, it is possible to prevent the horizontal displacement of the upper and lower barrel dies during heating and pressurization, and to prevent the horizontal displacement of the upper and lower optical element molding dies. It is possible to eliminate the core misalignment. Further, by providing the positioning surface and the lateral displacement prevention member so that relative rotation of the upper and lower body dies does not occur, it is possible to more reliably prevent the misalignment of the optical element.

[Brief description of drawings]

FIG. 1 is a vertical sectional view showing an embodiment of an optical element molding apparatus of the present invention.

FIG. 2 is a plan view taken along the line II of FIG.

FIG. 3 is a schematic sectional view of an optical element molding lower die alone.

4 is a cross-sectional view of the apparatus of FIG. 1 in a molded state.

FIG. 5 is a vertical sectional view showing another embodiment of the optical element molding apparatus of the present invention.

6 is a plan view taken along the line VI of FIG.

[Explanation of symbols]

 10 Upper Body Mold 11 Insertion Fixing Hole 12 Optical Element Molding Upper Mold 15 Elevating Cylinder Rod 16 Horizontal Displacement Prevention Plate (Horizontal Displacement Prevention Member) 17 Positioning Surface 18 Fixing Screw 20 Lower Body Mold 21 Insertion Fixing Hole 22 Optical Element Molding Lower Mold 24 Spacer 26 Positioning surface 40 Outer body type (lateral displacement prevention member) 41 Horizontal displacement prevention part

Claims (7)

[Claims] 1. Upper and lower body dies; a plurality of upper and lower optical element forming dies supported by the upper and lower body dies, respectively.
In an optical element molding apparatus for forming an optical element material positioned between the upper and lower optical element molding dies by heating the upper and lower body molds close to each other, one or both of the upper and lower body molds, A total of three or more positioning surfaces are formed around the upper and lower body dies and are orthogonal to the approaching and separating directions of the upper and lower body dies, and the upper and lower body dies approach one or both of the upper and lower body dies. An optical element molding apparatus, characterized in that a lateral deviation prevention member is provided that is in sliding contact with each positioning surface when the optical elements are formed. 2. The optical element molding apparatus according to claim 1, wherein the positioning surface and the lateral misalignment preventing member are provided in such a manner as to restrict relative rotation of the upper and lower body dies in a sliding contact engagement state between the two. 3. The optical element molding apparatus according to claim 1, wherein the positioning surface is provided with four surfaces which are orthogonal to each other when seen in a plan view. 4. The positioning surface according to claim 1, wherein the positioning surface is provided on one of the upper and lower body dies, and the lateral displacement prevention member is provided on the other of the upper and lower body dies. Optical element molding machine. 5. The optical element molding apparatus according to claim 4, wherein all the lateral displacement prevention members are provided in one outer body mold that surrounds one of the upper and lower body molds. 6. The optical element molding apparatus according to claim 1, wherein the barrel die, the optical element molding die, and the lateral deviation prevention member are made of materials having the same expansion coefficient. 7. The upper and lower body dies according to claim 1, wherein the upper and lower body dies have a plurality of paired upper and lower insertion fixing holes into which the optical element forming dies are inserted and fixed. A surface is an optical element molding device that is processed at the same time when both barrel dies are brought close to each other and held together.