JP3130621B2 - 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 for forming an optical element such as glass.

[0002]

2. Description of the Related Art Optical elements such as glass lenses used in optical instruments such as cameras, microscopes, and telescopes must be formed so that the center thickness of the lenses is constant. As a document describing a technique of forming the lens with a constant thickness, there is, for example, JP-A-61-205630. The technology described in this publication discloses a molding method in which the pressing of a press is stopped by a position-variable stopper, and the optical element is pressed in conjunction with the cooling, solidification and contraction of the optical element. .

However, in the technology disclosed in the above publication,
In order to obtain the exact thickness of the molded optical element,
There are two problems. One is that when the mold is stopped by a stopper during pressing, the optical glass material contracts without pressure. For this reason, the thickness dimension of the optical element after pressing depends on the amount of shrinkage. That is, there is a problem that the thickness of the optical element varies due to the temperature condition. Further, depending on the shape, since the amount of shrinkage is uneven, distortion occurs in the surface shape called sink mark, and there has been a problem that surface accuracy is extremely reduced. Another problem is that the method in which the mold is stopped by the stopper at the time of pressing and the above-mentioned stopper is operated in conjunction with the contraction of the optical glass material and pressurized is also the thickness dimension of the optical element at the completion of pressing. However, since it is formed depending on the amount of shrinkage, there has been a problem that the thickness dimension varies. As described above, it has been difficult to obtain an accurate wall thickness based on the molding method having two problems, or to reduce the variation.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and it is possible to form an optical element with high accuracy and small variation by a simple method. It is another object of the present invention to provide a method for molding an optical element having high quality and good cost performance.

[0005]

According to the present invention, an optical glass material placed on a barrel mold is heated to a predetermined temperature, and is conveyed between an upper mold and a lower mold to be pressed and formed. In a method for forming an optical element in which the pressing is stopped at a position where the optical element to be pressed and formed has a desired thickness, the pressing provided between the body mold and the mold is performed. This is a method for molding an optical element in which the optical glass material that has protruded simultaneously with the stop of the mold is pressed against the protruding portion of the optical glass material.

[0006]

Embodiment 1 A specific example of a method for forming an optical element according to the present invention will be described with reference to the drawings. FIG. 1 is a front cross-sectional view showing a main part of a molding apparatus according to a first embodiment of the invention, which relates to a method for molding an optical element of the present invention. As shown in the figure, a pair of upper and lower molding dies 1 and 2 are arranged coaxially, and the lower dies 2 are configured to be press-formed by vertical movement (arrows). A step 10 having a large diameter is formed at the lower end of the lower mold 2, and a stopper 3 is provided on the upper surface of the lower mold 2 so that the thickness of the optical element to be molded can be regulated to a desired dimension. Has been established.
Further, a ring-shaped member provided between the upper mold 1 and the lower mold 2 and having the concave portion 11 formed on the upper surface thereof, which is not shown in the figure, is provided with an optical glass material from the outside by a transfer arm. (Preform) 6 is a body mold 4 which is transported and mounted between the pair of molding dies 1 and 2 above.
The concave portion 1 on the upper surface on which the optical glass material 6 of the body mold 4 is placed
The inner diameter of the upper mold 1 is formed larger than the outer diameter of the upper mold 1.
The molded part at the tip of the lower mold 2 is formed to be insertable.

When the optical glass material 6 is pressed and formed between the outer periphery of the upper mold 1 and the inner periphery of the concave portion 11 of the body mold 4, a protrusion opening of a protrusion 7 of the optical glass material 6. The unit 16 is constituted. In order to press-mold the protruding opening 16, the outer periphery of the upper mold 1 is, as shown in FIG.
A ring-shaped pressing member 5 having a hole 13 is provided so as to slide in the axial direction. The outer diameter of the pressing member 5 is formed to fit with the inner diameter of the concave portion 11 of the body mold 4. The ring-shaped distal end surface (lower end surface shown in the figure) of the pressing member 5 is formed to be tapered inward, so as to press the protruding portion 7 of the optical glass material 6. Further, on the outer peripheral wall at the upper end of the pressing member 5, a driving means (not shown) for slidingly moving the pressing member 5 in the up-down direction (the direction of the arrow) and a connecting member 14 configured to be connected are provided.
Further, a heating heater 8 is provided on the outer peripheral surface of the pressing member 5 so as to always maintain a high temperature so that the optical glass material 6 is not rapidly cooled during the press molding of the pressing member 5 as shown in the figure.
Is provided.

A molding method according to the present embodiment having the above-described configuration will be described. An optical glass material (preform) 6 having both surfaces formed flat is placed in the concave portion 11 of the barrel 4 and the barrel 4 is placed on a transfer arm (not shown) to bring the optical glass material 6 to a desired softening temperature. After heating, it is transported between the upper mold 1 and the lower mold 2. When the lower mold 2 is moved upward from below the conveyed mold 4, the molding surface at the tip end of the lower mold 2 protrudes above the hole 12 provided in the step of the mold 4, and the optical glass Abuts against the material 6 and abuts on the lower edge of the hole 12 of the body mold 4 against the step 15 provided at the tip of the lower mold 2;
The torso 4 is lifted up. The optical glass material 6 is press-molded by the upper mold 1 by raising the lower mold 2. The lower mold 2 rises until the stopper 3 comes into contact with the upper surface of the step 10 at the base end of the lower mold 2, and the rising operation is stopped by coming into contact with the stopper 3. Simultaneously with the stop of the lower mold 2, the pressing member 5 moves downward along the outer peripheral surface of the upper mold 1, and the optical member formed between the outer periphery of the upper mold 1 and the concave portion 11 of the body mold 4. The glass material 6 is pressed against the upper surface of the protrusion 7 due to the pressing of the glass material 6.

After the molding of the protruding portion 7 is completed, the optical glass material 6 is cooled, the pressing member 5 moves upward and slides, and the lower mold 2 moves downward to be molded. The formed optical element is transferred to the next step together with the barrel mold 4, and the molding is completed.

When the optical element is molded by the molding method as described above, the standard of the desired thickness dimension is 2.00 mm.
Although it was in the range of ２．０2.02 mm, it was a value sufficiently clearing this. Further, there was almost no variation in the thickness of the optical element. Also, the transfer accuracy is good,
A high-precision, high-quality optical element could be formed without sink marks.

[0011]

Embodiment 2 FIG. 2 is a front sectional view showing a main part of a molding apparatus according to Embodiment 2 relating to a method for molding an optical element of the present invention. As shown in the figure, a pair of upper and lower molding dies 21 and 22 each having a columnar shape are arranged coaxially, and are configured to be press-formed by vertically moving (arrow) the lower mold 22. . In addition, a step 23 having a large diameter is formed at the lower end of the lower mold 22, and the body mold 2 is formed on the upper surface of the step 23.
A cylindrical stopper 24 whose axial direction is regulated in accordance with the thickness dimension value of the optical element placed and molded on the upper surface of the upper surface 5 is in contact with the outer peripheral edge of the lower end surface of the body mold 25. It is attached to. That is, when the lower mold 22 rises, the stopper 24 also rises, and its tip comes into contact with the lower surface of the barrel mold 25 to raise the barrel mold 25. Further, the upper end surface of the body mold 25 is configured to contact the step of the upper mold 21 to stop the lower mold 22 from rising. A body mold 25 having a ring shape disposed between the upper mold 21 and the lower mold 22 and having a step 27 on which an optical glass material 26 is placed at the lower end of the inner diameter is arranged. I have. Although not shown, the body mold 25 is provided with an optical glass material 26 as a molding material from outside by a transfer arm, and the pair of upper and lower molds 21 and 2
2 to be conveyed and molded.

On the upper surface of the above-mentioned barrel mold 25, the inner diameter of a step portion 27 formed so as to place the optical glass material 26 thereon is:
The lower die 22 is formed to have a diameter larger than the outer diameter of the distal end portion. That is, a step 2 having a small diameter is provided in the middle of the axis of the cylindrical lower mold 22.
9 around the axis on the step surface of the step portion 29, for example, a wire diameter of 1.5 mm, an inner diameter of 11 mm, a total number of turns of 4, material SU
The spring-shaped spring 30 wound in S304 is fitted, and the optical glass material 2 placed on the barrel mold 25 on the upper surface thereof.
The ring-shaped pressing member 31 is superposed so as to lift the protruding portion 33 by the pressing force at the time of molding of 6, and a gap is formed by the bias of the spring 30 into which the distal end can be inserted. .

A step portion 32 having a small diameter is formed at the tip (the lower end shown in the figure) of the upper mold 21 above the body mold 25, and the tip is inserted into the body mold 25 to form the body. The upper surface of the optical glass material 26 placed in the mold 25 is formed. Also, the surface of the step 32 of the upper mold 25 is
The edges of the upper surface of the optical element 5 are in contact with each other and constitute a regulating surface of the thickness of the optical element to be molded.

The molding method according to the present embodiment having the above configuration will be described. First, an optical glass material (preform) 26 formed on a flat surface on both sides is placed in the concave portion 28 of the body mold 25,
After being heated to a temperature at which the optical glass material 26 is softened by the heating means, the upper mold 21 and the lower mold 2 are moved by the transfer arm.
When the lower mold 22 is raised and the body mold 25 is also raised via the stopper 24, and the upper end surface of the body mold 25 abuts on the step 32 of the upper mold 21. Lower mold 22
Operation stops. At this time, the optical glass material 2 by pressing
The protruding portion 33 of 6 is pressed via the pressing member 31 by the bias of the spring 30.

When the optical element is molded by the above-described molding method, the thickness of the optical element matches the variation in the height of the barrel mold 25, and if this height is within the standard of the thickness of the optical element. All variations in the thickness of the optical element were within the standard range. In addition, there was no sink mark, and the transferability was good.

[0016]

According to the present invention having the above configuration and method,
Since a gap is provided between the mold and the body mold, the mold is stopped by the stopper at a position where the optical element has a desired thickness, and the material that has protruded during the press into the gap is pressed. , The shrinkage of the optical glass material and the occurrence of sink marks can be reliably prevented, the accurate thickness of the optical element can be obtained, and high transfer accuracy can be obtained. Accordingly, the cost performance is good, and the high precision is always constant, so that an optical element with good quality can be manufactured with high productivity.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a first embodiment of a method for forming an optical element according to the present invention.
It is sectional drawing from the front which shows the principal part of the shaping | molding apparatus used for (1).

FIG. 2 is a second embodiment relating to a method for molding an optical element of the present invention.
It is sectional drawing from the front which shows the principal part of the shaping | molding apparatus used for (1).

[Explanation of symbols]

 1,21 Upper mold 2,22 Lower mold 3,24 Stopper 4,25 Trunk mold 5,31 Pressing member 6,26 Optical glass material 7,33 Protruding part 8 Heater 10,15,23,27,29 , 32 Step 11, 28 Recess 12, 13, Hole 14 Connection member 16 Protruding opening 30 Spring

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-61-205630 (JP, A) JP-A-62-78122 (JP, A) JP-A-3-228837 (JP, A) JP-A-3-3 242331 (JP, A) JP-A-4-331725 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C03B 11/08 C03B 11/00

Claims (1)

(57) [Claims] 1. An optical glass material placed on a body mold is heated to a predetermined temperature, and is conveyed between an upper mold and a lower mold to be pressed and formed. At a position where a desired thickness dimension is obtained, in the method of molding an optical element in which the pressurization is stopped, in the protruding portion of the optical glass material by pressing provided between the body mold and the mold, A method for molding an optical element, wherein the extruded optical glass material is pressed simultaneously with the stop of the mold.