JP3131496B2 - Optical element molding method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a high-precision optical element which does not require a polishing step after press molding in the production of optical glass elements such as lenses and prisms.

[0002]

2. Description of the Related Art Generally, when a glass gob obtained by cutting molten glass is press-formed, a trace of cutting remains on the surface of a molded lens, and when this surface defect occurs on an optical function surface, it is removed by post-processing such as polishing. There is a need. Conventionally, in order to eliminate the need for post-processing of the molded lens, a technology that rotates the glass gob moderately, moves the cut marks outside the molding surface of the molding die, and does not cause surface defects on the optical function surface of the molded lens is a special feature. It is disclosed in JP-A-63-297224, JP-A-1-145338 and JP-A-2-145441.

In the method disclosed in Japanese Patent Application Laid-Open No. Sho 63-29224, a conduit is arranged so as to be inclined or curved with respect to a molding die, and the cut glass gob is guided to the molding die by the conduit. The glass gob is supplied so as to lie in the horizontal direction so that the cutting mark is located outside the molding surface of the molding die. In the method of JP-A-1-145338,
A molten glass material is cut off from above into a female mold having an upwardly sloping inclined portion provided on the periphery of a mold concave portion (molding surface) for molding the lens body. At this time, both ends of the molten glass are cut on the inclined portion. It is supplied while being rolled over, but dropped. In the method of JP-A-2-145441, the molten glass is cut and a glass gob is dropped freely.
A load force is applied to the tip of the glass gob during dropping by a loader pad to correct the posture of the glass gob when it is loaded, so that the grounding posture of the glass gob is almost horizontal, and the cutting mark is supplied to the molding surface of the molding die. are doing.

[0004]

However, Japanese Patent Application Laid-Open No.
In the method of JP-A-297224, the glass gob moves while contacting the inside of the conduit, and at that time, foreign matter adheres to the glass gob to impair the appearance of the molded lens,
There is a problem that the heat of the glass gob is removed from the conduit and the transferability during press molding is impaired. Further, in order to prevent the glass gob from adhering to the inside of the conduit, it was necessary to strictly control the viscosity of the glass gob.

In the method disclosed in Japanese Patent Application Laid-Open No. 1-145338, the cutting speed of a pair of cutting blades for cutting the molten glass suspended from a hopper from both sides is made different from each other, and the amount of cutting by one of the cutting blades is increased. Then, the molten glass is cut while being tilted, and the cut molten glass is turned over in the middle of dropping, so that it is necessary to strictly control the cutting speed of the cutting blade. Also, the distance between the cutting blade and the female mold had to be strictly controlled. Furthermore, the inclination of the molten glass during cutting also changes due to its own weight deformation, so that the viscosity of the molten glass had to be accurately controlled. In the method disclosed in Japanese Patent Application Laid-Open No. 2-145441, a loader pad is brought into contact with a cut surface of a falling glass gob, the glass gob is rotated by a predetermined angle, and the glass gob is loaded in a nearly horizontal position into the mold. It was necessary to strictly control the weight and the distance between the loader pad and the mold. Further, since it is necessary to provide the loader pad and the driving means of the loader pad, the apparatus itself becomes expensive, and the cost of the molded lens is increased.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems of the prior art, and enables easy and reliable molding of a good appearance without having to strictly control the viscosity, weight, distance, etc. of the molten glass. By supplying molten glass with the cut surface positioned outside the molding surface of the mold, the cut surface of the glass becomes outside the optical function surface, and an object is to provide a method of forming an optical element that does not require post-processing. And

[0007]

In order to achieve the above object, the present invention cuts a molten glass flowing down from a nozzle tip of a glass melting furnace and supplies the cut glass to a lower molding surface of a pair of upper and lower molding dies. In the molding method of the optical element for press-molding the molten glass lump by the molding die, the tip of the molten glass is brought into contact with the outer peripheral edge of the lower mold forming surface while flowing down from the nozzle tip, and immediately thereafter, the lower mold forming surface and The molten glass was supplied onto the lower mold forming surface while displacing the nozzle tip relatively.

[0008]

According to the above configuration, immediately after the tip of the molten glass comes into contact with the outer peripheral edge of the lower mold forming surface, if the forming surface and the nozzle tip are relatively displaced, the molten glass is placed on the lower mold forming surface. Supplied to lie down. By cutting the molten glass at the position where the cut portion of the flowing molten glass goes out of the lower mold forming surface, the molten glass lump is supplied in a state where the cut portion is not on the lower mold forming surface. Is done. Thereby, a high-precision optical element having no glass cut portion on the optical function surface can be formed.

[0009]

Embodiment 1 FIG. 1 is a front view showing a molding apparatus for carrying out an embodiment 1 of a molding method of an optical element according to the present invention in a partial cross section. The molding device 1 is provided with an upper base 2 and a lower base 3, and the upper base 2 and the lower base 3
And are arranged in parallel. A press cylinder 5 and a glass melting furnace 6 are attached to the upper base 2. A press shaft 7 is provided in the press cylinder 5 toward the lower base 3, and an upper mold mounting seat 8 is fixed to a lower end of the press shaft 7. An upper molding die 9 is attached to the lower surface of the upper molding mounting seat 8 with the molding surface 9a facing the lower base 3 side. At the lower part of the glass melting furnace 6, a nozzle 6a for discharging the inner molten glass 10 downward is provided. Below the nozzle 6a, a pair of cutting blades 11 for cutting the molten glass 10 are arranged.

A rail 12 is laid on the lower base 3,
On the rail 12, a lower mold mounting seat 14 which is moved by a rodless cylinder 13 in the left-right direction in the figure is arranged. A lower mold 15 is attached to the upper surface of the lower mold mounting seat 14 with the molding surface 15a facing upward. The lower molding die 15 is provided so as to be movable in the left-right direction together with the lower molding die mounting seat 14. 9 can be reciprocated between a molding surface 9a and a position facing the molding surface 9a. The temperature of the upper mold 9 and the lower mold 15 can be adjusted by a controller (not shown).

Next, an embodiment of a method for molding an optical element using the molding apparatus 1 will be described with reference to FIGS.
First, the molten glass 10 is allowed to flow down from the nozzle 6a with the right peripheral portion of the molding surface 15a of the lower molding die 15 positioned immediately below the nozzle 6a of the glass melting furnace 6. When the front end portion 10a of the molten glass 10 reaches the right peripheral portion of the forming surface 15a (see FIG. 1), the rodless cylinder 13
The lower mold 15 is moved rightward on the rail 12. At this time, the flow of the molten glass 10 is continued. And
The cut portion of the molten glass lump 10b cut by the cutting blade 11 is
At a position where it falls outside the optical function surface on the left side of the molding surface 15a,
The molten glass 10 is cut by the cutting blade 11. Therefore,
The cut molten glass lump 10b is placed in a state of lying on the molding surface 15a (see FIG. 2). Further, the lower molding die 15 is moved rightward, and the movement is stopped at a position where the molding surface 15a faces the molding surface 9a of the upper molding die 9.

Thereafter, the upper forming die 9 is lowered by the press cylinder 5, and the molten glass lump 10b is press-formed by the forming surface 9a and the forming surface 15a (see FIG. 3). And
After the glass between the upper and lower molds 9 and 15 has cooled and solidified,
The upper mold 9 is raised by the press cylinder 5, and the molded lens is taken out.

According to this embodiment, since the cut portion of the molten glass lump 10b does not exist on the optically functional surface of the molded lens,
A post-processing is unnecessary, and a molded lens with good appearance can be obtained. Further, since the lower mold 15 only needs to be moved in one direction from the flow of the molten glass 10 to the press molding, the structure of the molding apparatus 1 can be made very simple and easy.

[0014]

Embodiment 2 FIG. 4 is a front view showing a molding apparatus for carrying out Embodiment 2 of the method for molding an optical element according to the present invention in a partial cross section. The molding device 20 is provided with a molding device base 21.
1a and a column 21b raised on both sides of the base 21a. In the center of the lower part of the base 21a, the cylinder 2
The cylinder 22 is provided with a lower shaft 23 which is vertically moved by the cylinder 22 and is provided upward.
The lower molding die 15 is fixed to the upper end of the lower shaft 23 with the molding surface 15a facing upward.

A guide rail 24 is provided at an upper portion between the support portions 21b, and an upper base 25 is slidably mounted on the guide rail 24 in the left-right direction. A glass melting furnace 6, an upper mold 9 and a pair of cutting blades 11 are attached to the upper base 25. Upper mold 9
Are provided with the molding surface 9a facing downward, and the upper base 25
Is moved, the nozzle 6 at the lower part of the glass melting furnace 6 is moved.
a and the molding surface 9a and the molding surface 15a of the lower molding die 15 can be opposed to each other. The pair of cutting blades 11 are attached to the upper base 25 via the holding members 26, respectively, and are arranged below the nozzle 6a to face each other.

Next, this embodiment of a method for molding an optical element using the molding apparatus 20 will be described with reference to FIGS. First, the nozzle 6a of the glass melting furnace 6 is connected to the lower molding die 15
Of the molten glass 1 in the glass melting furnace 6 from the nozzle 6a in this state.
Let 0 flow down. When the tip 10a of the molten glass 10 reaches the right peripheral portion of the forming surface 15a (see FIG. 4), the upper base 25 is moved to the left. At this time, the molten glass 10
Flow is continuing. Then, the molten glass 10 is cut by the cutting blade 11 at a position where the cut portion of the molten glass lump 10b cut by the cutting blade 11 falls outside the optical function surface on the left side of the molding surface 15a. Thereby, the molten glass lump 10b is placed so as to lie on the molding surface 15a (see FIG. 5). Further, the upper base 25 is moved leftward, and the movement of the upper base 25 is stopped at a position where the molding surface 9a of the upper molding die 9 faces the molding surface 15a.

Thereafter, the lower mold 15 is moved by the cylinder 22.
And the molten glass lump 10b is formed into the molding surfaces 9a and 15a.
Press molding is performed (see FIG. 6). After the molten glass being pressed is cooled and solidified, the lower molding die 1
5 is lowered by the cylinder 22, and the molded lens is taken out. According to this embodiment, the same effects as those of the first embodiment can be obtained.

[0018]

Embodiment 3 FIG. 7 is a front view showing a molding apparatus for carrying out Embodiment 3 of the method for molding an optical element according to the present invention in partial cross section, and FIG. FIG. 9 is a side view showing the melting furnace and the lower mold in partial cross-section. FIG. 9 is a plan view showing the glass melting furnace and the lower mold. Molding device 3
A molding apparatus base 31 is provided at 0, and a cylinder 22 is attached to a lower left portion of the molding apparatus base 31. The cylinder 22 is provided with a lower shaft 23 that is moved up and down, and the lower shaping die 15 is fixed to the upper end of the lower shaft 23 with the forming surface 15a facing upward.

Above the lower mold 15, an upper base 32 is mounted on the upper end of a column 33 erected on the molding apparatus base 31. On the lower surface of the upper base 32, an upper molding die 9 is provided with its molding surface 9a facing downward.
5 is mounted so as to be coaxially opposed thereto. On the right side of the upper base 32, the glass melting furnace 6 supported by a column 34 erected on the forming apparatus base 32 is disposed. The lower part of the glass melting furnace 6 has an internal molten glass 10
The nozzle 35 for discharging the gas downward is attached. The nozzle 35 has a tip opening 35a extending on the molding surface 15a of the lower molding die 15, and is indicated by arrows A and B shown in FIG. 9 on the molding surface 15a (in FIG. 7, orthogonal to the paper surface). Direction). Nozzle 3
A pair of cutting blades 11 for cutting the molten glass 10 are arranged below the tip opening 35a of the fifth and above the lower forming die 15.

Next, this embodiment of a method for forming an optical element using the above-described molding apparatus 30 will be described with reference to FIGS. First, as shown in FIG. 8, the tip opening 35a of the nozzle 35 is positioned directly above a right peripheral portion of the molding surface 15a of the lower molding die 15 (in FIG. 7, a front peripheral portion of the molding surface 15a). Then, the molten glass 10 in the glass melting furnace 6 flows down from the tip opening 35a. Tip 10a of molten glass 10
Moves the nozzle 35 in the direction of arrow A shown in FIG. 9 when it reaches the right peripheral portion (see FIG. 8) of the molding surface 15a.
At this time, the flow of the molten glass 10 is continued. Then, the molten glass 10 is cut by the cutting blade 11 at a position where the cut portion of the molten glass lump cut by the cutting blade 11 falls outside the left optical function surface of the molding surface 15a shown in FIG.
As a result, the molten glass lump is placed in a state of lying on the molding surface 15a, as in the above embodiment. further,
The nozzle 35 is moved in the direction of arrow A (see FIG. 9) and stopped at a position where it does not interfere with the elevation of the lower mold 15.

Thereafter, the lower mold 15 is moved by the cylinder 22.
And the molten glass lump is press-formed by the forming surfaces 9a and 15a. After the molten glass that has been pressed is cooled and solidified, the lower mold 15 is moved to the cylinder 22.
To take out the molded lens. According to this embodiment, the same effect as in the first embodiment can be obtained. Further, since there is no lateral movement of the upper mold 9 or the lower mold 15, the coaxial accuracy of the upper and lower molds 9, 15 is improved.

[0022]

Fourth Embodiment FIG. 10 is a sectional view showing a lower mold used in a fourth embodiment of the method for molding an optical element according to the present invention. In this embodiment, a biconcave lens or a concave-convex lens is press-molded.
Are formed. Guide 3 is provided on the outer periphery of molding surface 36a.
7 is provided with its tip protruding from the molding surface 36a. This lower molding die 36 is provided with molding devices 10, 20,
The optical element is mounted in place of the lower mold 9 of 30 and the method of forming the optical element is the same as in the above-described embodiments 1, 2, and 3, and therefore the description thereof is omitted.

According to the present embodiment, the molten glass lump placed on the lower mold 36 is guided by the guide 37 in the same manner as in the above embodiments.
By this, it can be prevented from falling off from the convex molding surface 36a,
The biconvex lens or the concave / convex lens can be press-molded while being securely held on the molding surface 36a. Other effects are the same as those of the above embodiments.

[0024]

As described above, according to the present invention, molten glass can be supplied so as to lie on the lower mold forming surface. Therefore, since the cut portion of the molten glass lump can be supplied in a state of being located outside the outer periphery of the lower mold forming surface, it is possible to obtain an optical element with a good appearance in which the cut portion of the molten glass does not exist on the optical function surface.

[Brief description of the drawings]

FIG. 1 is a front view showing a partially sectioned molding apparatus used for carrying out a first embodiment of the present invention.

FIG. 2 is a partial front view showing a state after a molten glass lump in Example 1 is supplied to a lower mold forming surface.

FIG. 3 is a partial front view showing the optical element in Example 1 during press molding.

FIG. 4 is a front view showing, in partial cross section, a molding apparatus used for carrying out Embodiment 2 of the present invention.

FIG. 5 is a front view of a forming apparatus showing a state in which a molten glass lump in Example 2 is supplied to a lower mold forming surface.

FIG. 6 is a front view of a molding apparatus during press molding in Example 2.

FIG. 7 is a front view showing, in partial cross section, a molding apparatus used for carrying out Embodiment 3 of the present invention.

8 is a left side view showing the glass melting furnace and the lower mold in FIG. 7;

FIG. 9 is a plan view showing a glass melting furnace and a lower mold in FIG. 7;

FIG. 10 is a cross-sectional view showing a lower forming die of a forming apparatus used for carrying out Embodiment 4 of the present invention.

[Explanation of symbols]

 6 Glass melting furnace 6a Nozzle 9 Upper forming die 9a Forming surface 10 Molten glass 11 Cutting blade 15, 36 Lower forming die 15a, 36a Forming surface 35 Nozzle 35a Tip opening

Claims (1)

(57) [Claims] An optical element forming method for cutting molten glass flowing down from a nozzle tip of a glass melting furnace, and press-molding the molten glass mass supplied to a lower mold forming surface of a pair of upper and lower molds using the molding die. In the above, the tip of the molten glass is brought into contact with the outer peripheral edge of the lower mold forming surface while flowing down from the nozzle tip, and immediately thereafter, the molten glass is moved relative to the lower mold forming surface while relatively displacing the lower mold forming surface and the nozzle tip. A method for molding an optical element, characterized in that it is supplied above.