JPH05319835A - Production of annular optical element - Google Patents

Abstract

PURPOSE:To reduce the number of stages by heating, softening and pressing a glass material placed on a specified member to form a recessed part and pressing the other surface with a die to form a hole part. CONSTITUTION:A glass raw material 1 is placed on a carrier member 2, and the member 2 is carried between heaters 6 by a carrier arm. The material 1 is then heated by the heaters 6 up to the temp. exceeding the softening point of the material 1 to impart flowability. The material 1 imparted with flowability is allowed to flow into the through-hole 9 of the member 2 by gravity and dripped downward to form a recessed part 1a in the material 1 at the part corresponding to the through-hole 9 and the material 1 is formed into the shape approximating to the final annular shape. The member is then interposed between the upper and lower dies and the material is press-formed into an annular optical element.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a ring-shaped optical element in which a ring-shaped optical element having a hole is molded by a heat softening press.

[0002]

2. Description of the Related Art FIG. 8 shows an example of a ring-shaped optical element 20, which has a hole portion 21 penetrating vertically and formed in a central portion thereof, and is attached to, for example, a distal end portion of an endoscope and used as an illumination window. It Such a ring-shaped optical element is manufactured by grinding and polishing a glass material, but the number of steps is large and the productivity is poor. Therefore, a method of molding by softening and pressing the glass material is preferable,
In Japanese Patent Laid-Open No. 61-132524, the mold is held at a temperature not lower than the glass transition point and not higher than the softening point, and a glass material having a temperature substantially equal to this temperature is put into the mold and pressed to obtain a glass material It is described that the temperature is maintained for 20 seconds or more until the temperature distribution becomes uniform.

[0003]

However, in order to mold the ring-shaped optical element by the method of the above-mentioned publication, a step of molding the hole 21 is necessary in addition to the above-mentioned steps. The formation of the hole 21 is performed by performing a predetermined hole processing before the glass material is put into the mold, or by performing a hole processing by grinding after molding the optical element. For this reason, in addition to the heating and softening press process, a hole forming process is required, and the number of processes cannot be reduced.

The present invention has been made in view of the above circumstances, and a ring-shaped optical element capable of reducing the number of steps by forming a hole portion only by a heating and softening press of a glass material. It is intended to provide a manufacturing method.

[0005]

In order to achieve the above object, the manufacturing method of the present invention has a through hole corresponding to a hole portion of a ring-shaped optical element to be formed and forms one optical surface of the optical element. A step of placing the glass material on a conveying member having a molding surface, a step of heating the glass material by its own weight until it flows into the through hole to form a recess in the glass material, and the other optical surface of the optical element A step of pressing the glass material with the die for molding and the conveying member and causing the glass material corresponding to the recesses to flow out from the through hole.

[0006]

When the glass material is heated to a temperature above the softening point on the conveying member, it has fluidity, so that it flows into the through hole of the conveying member by its own weight to form a concave portion, and a shape close to the final ring shape is obtained. Become. Then, while pressing the mold and the conveying member to form an optical surface, it is possible to form a hole by flowing out the glass material for each recess from the through hole, but since this hole is formed from the recess, The flow amount for hole processing is reduced, and good molding is possible.

[0007]

Embodiment 1 FIGS. 1 to 3 show the manufacturing process of Embodiment 1 of the present invention. First, as shown in FIG. 1, the glass material 1 is placed on the conveying member 2. The carrying member 2 is held by a carrying arm (not shown), the inner bottom surface is a molding surface 8 for molding one optical surface of the optical element, and the inner diameter thereof is the outer diameter of the optical element (for example, , Diameter 9 mm). Further, a through hole 9 is formed by punching out a substantially central portion of the molding surface 8. The through hole 9 is formed corresponding to the hole portion 21 (see FIG. 8) of the optical element, but the diameter of the hole is somewhat smaller than the hole portion of the optical element. If the hole diameter is 4 mm,
The hole diameter is set to 3.8 mm.

The carrying member 2 on which the glass material 1 is placed in this manner is carried between the heaters 6 by the carrying arm and heated by the heaters 6. Such heating is performed until the glass material 1 reaches a temperature that exceeds the softening point, and thereby the glass material 1 is provided with fluidity. FIG. 2 shows this heating step, in which the glass material 1 flows into the through hole 9 of the conveying member 2 by its own weight by being imparted with fluidity, and further hangs downward from the through hole 9. As a result, a concave portion 1a is formed in a portion of the glass material 1 corresponding to the through hole 9, and the glass material 1 has a shape similar to the final ring shape.

After such heating, the carrying member 2 is carried in between the upper die 3 and the lower die 5 to perform pressure molding. FIG. 3 shows this press forming step, in which the inner die 4 is axially slidably inserted into the upper die 3. The inner peripheral die 4 is provided at a portion facing the through hole 9 of the conveying member 2 and has a larger linear expansion coefficient than the glass material 1, for example, Hastelloy (linear expansion coefficient α = 14.0 × 10 ⁻⁶ ). The whole is constituted by. The outer diameter of the inner peripheral die 4 is equal to the diameter of the hole of the optical element (for example, 4 mm), and the tip portion is formed in a tapered shape. Since the inner peripheral die 4 forms the hole 21 of the optical element and does not form the optical surface, a release material such as carbon or boron can be applied to the outer surface thereof. The tip surface of the upper mold 3 is a molding surface 10 for molding the other optical surface of the optical element. On the other hand, the lower die 5 serves as a support member on which the conveying member 2 is placed, and the rise thereof causes the glass material 1 to be pressed by the conveying member 2 and the upper die 3. Reference numeral 11 denotes a storage portion for surplus glass formed in the lower mold 5. A tilt component is prepared for the lower mold 5 and the upper mold 3.

In the press molding step, the lower mold 5 is raised to press the glass material 1 by the conveying member 2 and the upper mold 3, and after a predetermined time has passed (for example, 0.5 seconds), the inner peripheral mold is pressed. Four
Moves into the glass material 1. In this case, the inner peripheral die 4 may be advanced before the pressing. Since the outer diameter of the inner peripheral die 4 that has advanced is larger than the through hole 9 of the conveying member 2, only the tapered tip portion enters the through hole 9 and then fits into the through hole 9 to form the through hole 9. Seal tightly. The inner peripheral die 4 thus advanced passes through the concave portions 1a of the glass material 1, and the surplus glass that hangs down is cut by the taper portion and the through hole 9 of the conveying member 2, and the surplus glass that is cut is the lower die 5. , And is sucked and collected. Since the hole 21 of the optical element 20 is formed by the advance of the inner peripheral die 4, the mold is opened to take out the optical element.

In this embodiment as described above, since the ring-shaped optical element can be molded by the heat softening press, hole machining becomes unnecessary and the number of steps can be reduced. Further, since the glass material is preliminarily formed with concave portions by heating and softening, and the inner peripheral die 4 is inserted into each of the concave portions to form holes, the inner peripheral die 4 is
In addition to reducing the resistance to, the amount of flow of the glass material is also reduced, which makes it possible to improve the hole and to form it reliably.

[0012]

Second Embodiment FIGS. 4 to 6 show a manufacturing process of a second embodiment of the present invention, in which the same elements as in the first embodiment are designated by the same reference numerals. In the second embodiment, as shown in FIG. 4, the inner peripheral ring 7 is attached to the conveying member 2. The inner peripheral ring 7 is made of a member such as Hastelloy having a linear expansion coefficient larger than that of the glass material. As shown in FIG. 7, the inner peripheral ring 7 has a through hole 9 in the conveying member 2.
The outer diameter of which is the same as the hole diameter of the hole of the optical element. Further, in the present embodiment, the upper end portion of the inner peripheral ring 7 is a pointed cutting edge 12.

In the molding according to this embodiment, first, the glass material 1 is placed on the inner peripheral ring 7 as shown in FIG. 4, and then, as shown in FIG. To do. Since this heating imparts fluidity to the glass material 1, the glass material 1 falls into the conveying member 2 by its own weight. At the time of this drop, the glass material 1 is separated into the central recessed portion 1a and the outer peripheral portion by the cutting edge 12 of the inner peripheral ring 7. And
After being cooled to the softening point, it is conveyed between the upper mold 3 and the lower mold 5 as shown in FIG. 6, and the optical surface is pressed by the upper mold 3 and the conveying member 2 to form a ring-shaped optical element. ..

In Example 2 as well, the ring-shaped optical element can be molded by the heat softening press, but since the volume of the glass material after flowing is relatively stable, it is possible to mold the optical element with improved wall thickness accuracy. A mold release material can be applied to the inner peripheral ring 7 as in the first embodiment.

[0015]

As described above, according to the present invention, since the ring-shaped optical element can be molded only by the heat softening press, the manufacturing process can be reduced.

[Brief description of drawings]

FIG. 1 is a sectional view of a first step of Example 1 of the present invention.

FIG. 2 is a sectional view of a second step of the first embodiment of the present invention.

FIG. 3 is a sectional view of a third step of Example 1 of the present invention.

FIG. 4 is a sectional view of a first process of Example 2.

FIG. 5 is a sectional view of a second step of the second embodiment.

FIG. 6 is a sectional view of a third step of the second embodiment.

FIG. 7 is a sectional view of an inner peripheral ring.

FIG. 8 is a perspective view of a ring-shaped optical element.

[Explanation of symbols]

 1 glass material 2 conveying member 3 upper mold 8 molding surface 9 through hole

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Motosaka Misaka 2-43-2 Hatagaya, Shibuya-ku, Tokyo Inside Olympus Optical Co., Ltd. (72) Inventor Shigeya Sugata 2-43 Hatagaya, Shibuya-ku, Tokyo No. 2 Olympus Optical Industry Co., Ltd.

Claims (1)

[Claims] 1. A step of placing a glass material on a conveying member having a through hole corresponding to a hole of a ring-shaped optical element to be molded and having a molding surface for molding one optical surface of the optical element. A step of forming a recess in the glass material by heating until the glass material flows into the through hole under its own weight,
A ring-shaped optics characterized by comprising a step of pressing a glass material with a mold for molding the other optical surface of the optical element and the conveying member and causing the glass material of the recesses to flow out from the through hole. Manufacturing method of device.