JPH06239627A - Method for forming optical element - Google Patents

Abstract

PURPOSE:To form an optical element without causing defects in a part opposite to a bottom force. CONSTITUTION:The tip 2 of a glass rod 1 is thermally softened, pressurized to a bottom force 3 and then cut. Thereby, pressurizing forming is carried out with a top force 4 and the bottom force 3. Since the whole forming surface (3a) of the bottom force 3 is simultaneously transferred by pressurizing the tip 2 of the glass rod 1 to the bottom force 3, defects are not caused.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a molding method for pressing a glass material which has been softened by heating to obtain an optical element.

[0002]

2. Description of the Related Art In the case of molding an optical element from a glass material which has been softened by heating, for example, JP-A-2-25864 is used.
As described in Japanese Patent No. 0, a pair of upper and lower molds are used. FIG. 6 shows this conventional method. After a lump of glass material 60 that has been softened by heating is dropped on the molding surface 61a of the lower mold 61 (see FIG. 6A), the lower mold 61 and the lower mold 61 are opposed to each other. It is pressed by the mold 62 to obtain an optical element (see FIG. 2B).

[0003]

However, in the case of molding by the conventional method, as shown in FIG. 2B, a stepped defect 63 recessed in the surface of the glass material 60 facing the lower mold 61 is formed. Had been formed. This is because when the heat-softened glass material 60 is dropped onto the lower mold 61, only a part of the molding surface 61a of the lower mold 61 is attached to the lower surface of the glass material 60 which is in contact with the molding surface 61a of the lower mold 61 due to its own weight. The transferred self-weight transfer region 64 is formed (see FIG. 10A), and thereafter, the molding is performed in two steps in which transfer is performed by the press of the upper die 62. Therefore, due to the time difference between these steps, the self-weight transfer region 64 is formed. This is caused by the difference in viscosity between the portion facing the lower mold 61 exposed to the outside air. The defect 63 causes deterioration of the appearance and quality of the molded product, which is a problem in molding.

The present invention has been made in consideration of the above circumstances, and an object of the present invention is to provide a method for molding an optical element which is improved in appearance and quality without causing defects during pressing.

[0005]

Means and Actions for Solving the Problems In the molding method of the present invention for achieving the above object, a glass rod made of a glass material is heated and softened and pressed to a lower mold, and the tip is removed from the glass rod. It is characterized in that it is cut and pressed by the lower mold and the upper mold.

FIG. 1 shows the steps of the present invention. After the tip 2 of a glass rod 1 made of a glass material is heated and softened (see FIG. 1 (a)), the tip 2 of the glass rod 1 is lowered. The molding surface 3a of the mold 3 is pressed (see FIG. 2B). By this pressing, the molding surface 3a of the lower mold 3 is transferred to the tip portion 2. That is, at this stage, the lower surface of the optical element is molded, but the transfer of the molding surface 3a of the lower mold 3 to the tip portion 2 is all completed at the time of pressing. Therefore, after that, the tip 2 is attached to the glass rod 1.
(See FIG. 3C), the upper mold 4 and the lower mold 3 are pressed to mold the upper surface of the optical element, so that the surface facing the lower mold 3 does not have any defect in appearance and quality. A good optical element can be molded.

[0007]

2 to 5 show one embodiment of the molding method of the present invention. In these figures, the molding surfaces 13a, 1
A lower mold 13 and an upper mold 14 are arranged so that the 4a face each other (see FIG. 5). The lower die 13 can be moved back and forth with respect to a portion facing the upper die 14 by driving an arm 15, and a pair of cutting blades 17 driven forward and backward by a drive arm 16 are arranged above the lower die 13. , This cutting blade 17
A heating furnace 18 is arranged above the. The heating furnace 18 heats and softens by inserting the tip portion 12 of the glass rod 11 made of a glass material.

In the above structure, the Tg temperature is 503 ° C.,
A glass rod 11 made of SF11 having a diameter (φ) of 15 mm is held by the elevating arm 10. Further, as the lower mold 13 and the upper mold 14, those having molding surfaces 13a and 14a having a diameter of 15 mm and a curvature (R) of 30 mm are both at a temperature of 500 ° C.
Use by heating to. First, the tip 12 of the glass rod 11 is inserted into the heating furnace 18 by 10 mm by the elevating arm 10.
It is softened by heating at 900 ° C. for 4 minutes (see FIG. 2). After this heating and softening, the elevating arm 10 is lowered to move the tip 12 of the glass rod 11 to the molding surface 13a of the lower mold 13.
Press on. This pressing is performed so that the front end 12 of the glass rod 11 covers the entire molding surface 13a of the lower mold 13, whereby the molding surface 13a of the lower mold 13 is transferred to the front end 13 of the glass rod 11 and The lower surface is molded (see FIG. 3).

Next, the cutting blade 17 is advanced by the drive arm 16 to cut the tip 12 from the glass rod 11 and separate it (see FIG. 4). After that, the arm 15 is driven to convey the lower mold 13 to directly below the upper mold 14, and the lower mold 13 is pressed by the upper mold 14 and the lower mold 13 with a pressing pressure of 5 Kgf to mold an optical element (see FIG. 5).

In this embodiment as described above, the tip 12 of the glass rod 11 which has been softened by heating is pressed against the lower mold 13 to make the lower mold 1
Since the entire surface of the molding surface 13a of 3 is simultaneously transferred, the lower mold 1
There is no difference in viscosity at the portion opposed to 3. Therefore, the lower mold 13
It is possible to mold an optical element having an improved appearance and quality without causing a defect on the surface facing to.

[0011]

INDUSTRIAL APPLICABILITY As described above, the present invention transfers the molding surface of the lower mold by pressing the tip portion of the glass rod that has been softened by heating to the lower mold, and thus an optical element having a defect-free appearance and improved quality is provided. It can be molded.

[Brief description of drawings]

FIG. 1 is a sectional view showing a molding method of the present invention.

FIG. 2 is a sectional view of an embodiment of the present invention.

FIG. 3 is a cross-sectional view when pressing the lower die in the embodiment.

FIG. 4 is a sectional view at the time of cutting in the embodiment.

FIG. 5 is a cross-sectional view at the time of press molding in an example.

FIG. 6 is a sectional view showing a conventional method.

[Explanation of symbols]

 1 glass rod 2 tip 3 lower mold 4 upper mold

Claims (1)

[Claims] 1. A method of molding an optical element, comprising pressing a softened glass material with a pair of upper and lower molds to heat and soften the tip of a glass rod made of the glass material and press it into a lower mold. Is cut from a glass rod and pressed by a lower die and an upper die.