JP2579016B2 - Manufacturing method of glass optical parts - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to a method for manufacturing a glass optical component, and in particular, obtains an optical component by pressing a glass in a molten state from both sides with a molding member while flowing the glass in a molten state. About the method.

[Problems to be Solved by Conventional Techniques and Inventions] As a method of obtaining an optical component from a glass material by press molding, there are a so-called reheat press method and a direct press method.

In the reheat press method, a glass blank that approximates the shape of the final molded product is once formed, and the blank is housed in a molding die apparatus, heated and pressed, and formed by a mold member of the molding apparatus. A final molded product corresponding to the shape of the cavity is obtained.

In the direct press method, a molten glass is introduced into a molding die apparatus and pressurized to directly obtain a final molded product corresponding to the shape of a cavity formed by a mold member of the molding apparatus.

By the way, since the glass blank used in the reheat press method preferably has a certain degree of good shape accuracy and surface accuracy, a glass material having a predetermined accuracy may be obtained by grinding and polishing. However, this requires time and labor for grinding and polishing, and thus the direct press method may be used for manufacturing the glass blank.

As a direct press method, for example, JP-A-63-24
As described in JP-A-8727 and JP-A-1-133948, the molten glass is caused to flow down from a nozzle while using a pair of molding members horizontally opposed from both sides thereof. There is a method in which the glass is cooled and hardened in a cavity formed by sandwiching and thus forming a molded product having a predetermined shape. In this method, a ring-shaped cutting member is arranged on the outer periphery of the optical surface molding surface of one molding die member, and is advanced simultaneously with or after the die member advancement,
The protruding glass is cut and removed to form an optical component having a desired shape. According to this method, an optical component can be obtained without leaving cutting marks of the flowing molten glass on the optical surface, which is preferable.

However, in the above method, when cutting the glass with the ring-shaped cutting member, dust is generated due to the contact between the cutting member and the other mold member, and the dust is formed on the molding surface of the mold member after releasing the molded product. It adheres and adheres to the glass surface which becomes the optical surface at the time of the next press, which may deteriorate the optical characteristics of the molded product.

Furthermore, as described above, the ring-shaped cutting member comes into contact with the other mold member, and thus has a short life, requires frequent replacement, and hinders improvement in manufacturing efficiency.

Further, in the above-described method, shrinkage (sink) is easily generated in the glass during pressing, and there is a problem that the surface accuracy of the obtained optical component is considerably lower than the molding surface accuracy of the mold member.

Accordingly, the present invention has been made in view of the prior art as described above, and has as its object to provide a glass optical component manufacturing method capable of obtaining an optical component having good optical characteristics including surface accuracy and improving the manufacturing efficiency. It is assumed that.

[Means for Solving the Problems] According to the present invention, in order to achieve the above object, the flowing molten glass is pressed by a pair of molding die members from both sides thereof and corresponds to the molding surface of the molding member. In producing an optical component having a surface, the glass is kept pressed without closing the periphery between the pair of forming mold members until the temperature of the glass becomes equal to or lower than its strain point. A method for producing a glass optical component, which obtains a glass molded product having an ear part protruding outside with respect to an optical component body portion formed between the molding die members, which is cut above a part where the molding die member is formed, A groove forming ring having a variable protrusion amount from the molding surface is provided around at least one molding surface of the molding die member, and a groove is formed in the molten glass at the time of pressing by the groove forming ring. And adjusting the thickness of the molded glass optical components by changing the projection amount from the mold member molding surface, a method of manufacturing glass optical components, is provided.

In the present invention, there is a form in which the ears of the optical component obtained by the above method are removed.

In the present invention, there is a form in which one surface of the main body of the optical component obtained by the above method is further processed into a desired shape and accuracy, and an optical component having a desired thickness is formed.

According to the present invention, there is provided a glass optical component having at least one aspheric surface by the above method.

Example An example of the present invention will be described below with reference to the drawings.

FIG. 1 is a sectional view showing a schematic process of an embodiment of a method for manufacturing a glass optical component according to the present invention.

In the figure, reference numeral 2 denotes a molten glass outflow nozzle connected to a glass melting device (not shown), and reference numeral 4 denotes a molten glass continuously flowing down from the nozzle. Reference numeral 6 denotes a shear (cutting blade) located immediately below the nozzle 4 for cutting the flowing molten glass 4 at an appropriate timing.

12 and 12 'are 1 arranged on both sides of the molten glass
A pair of molding die members, in this embodiment, for molding a convex meniscus lens. Reference numerals 12a and 12a 'denote molding surfaces for forming the optical surface, and the molding surfaces are mirror-finished. These mold members are rotationally symmetric, and are arranged coaxially with the molding surfaces facing each other. Each of the above mold members
A pair of mold sets includes 12, 12 '.

As the mold members 12 and 12 ', the forming surface of the Ni-base super heat-resistant alloy base material is polished and finished with a surface roughness Rmax of 0.01 μm and desired shape accuracy, and a nitride ceramic coating layer is formed on the surface.
One coated to a thickness of 0.8 μm can be used. As the mold base material, other Mo-based heat-resistant alloys, Fe-based heat-resistant alloys, stainless-based heat-resistant alloys, Mo, Ta, carbon, carbon composite materials, and the like can be used. The coating layer is used to supplement the hot strength of the base material. In addition to nitrides such as BN, TiN and AIN, carbides such as TiC, SiC and TaC, C (diamond) and others can be used. it can. These can be applied using various film forming techniques. The coating layer does not need to be a single layer, and an intermediate layer may be provided to improve adhesion strength and heat resistance. Also, CVD
In the case of a coating layer formed by a method, a process such as ultra-precision grinding or polishing can be performed to obtain a good surface accuracy on the surface of the coating layer itself. Furthermore, if the base material has a high hot strength and the shape accuracy can be maintained even after performing press molding a sufficient number of times, use a soft material such as platinum, a platinum-based alloy, Ni, or an alloy thereof as the coating layer. Can be.

In the mold set on the left, the molding die member 12 is fixed to a support member 14, which is mounted on a mounting member 16. A groove forming ring 18 is mounted around the mold member 12. The tip of the ring has a blade shape. The ring 18 is fixed to the mounting member 16 with bolts.
20 are interposed. The protrusion amount of the blade of the ring 18 from the mold member forming surface 12a is set according to the thickness of the spacer ring. In some cases, the blade does not protrude from the mold member forming surface 12a (the amount of protrusion is 0), and in some cases, the groove forming ring is not attached.

The mold member 12 includes a heater 22 and a thermocouple 24 for measuring temperature.

Although not shown, the mounting member 16 is supported by a base (not shown) so as to be able to reciprocate in the AB direction. The reciprocation is performed by driving means (not shown).

Although the left mold set has been described above, the right mold set is substantially the same except for the shape of the mold member molding surface 12a ',
Corresponding members are marked with “′”. However, although not shown, in the right mold set, the most forward stop position in the B direction is set by a stopper (not shown). By setting the position of the stopper variable and adjusting the position, the stop position can be appropriately set.

 Hereinafter, the manufacturing process will be described with reference to the drawings.

First, as shown in FIG. 1 (a), the left and right mold sets are opened at a predetermined gap, and while the shear 6 is kept open, the molten glass 4 is inserted between the mold members 12 and 12 'through the nozzle 2. Let down. Then, as shown in FIG. 1 (a), the sensor (not shown) detects that the lower end of the molten glass 4 has reached below the space between the mold members.

Next, based on the detection signal, the right mold set is advanced in the B direction until it comes into contact with the stopper. The left side mold set is advanced in the A direction with a slight delay with respect to the advance operation. As a result, as shown in FIG. 1 (b), the molten glass is pressed corresponding to the cavity formed by the pair of mold members 12, 12 'and the groove forming rings 18, 18'. At this time, as shown in FIG. 1 (b), the tips of the groove forming rings 18, 18 'are not in contact with each other and are separated by an interval D. Are formed around the surfaces corresponding to the mold member forming surfaces 12a and 12a '. Then, the glass optical component main body 30 is formed inside the groove.

Next, as shown in FIG. 1 (c), the shear 6 is closed and the molten glass 4 is cut. As a result, an ear 32 protruding outside the groove is formed around the glass optical component main body 30.

Pressing is continued until the glass temperature becomes equal to or lower than the strain point. During this time, the left-side mold set continues to apply the pressing pressure to the glass without being stopped by the stopper or the like.

Thereafter, as shown in FIG. 1 (d), the left and right mold sets are opened, and the shear 6 is further opened to take out the molded product. A takeout robot (not shown) is used for the removal.

FIG. 2 is a front view showing the molded product obtained in the above steps, and FIG. 3 is a schematic partial sectional view thereof.

In these figures, reference numeral 30 denotes an optical component main body, and 32
Are ears protruding outside thereof, and 34 and 36 are grooves formed on both surfaces between the main body 30 and the ears 32. The cross-sectional shape of the groove is a wedge shape as shown in FIG. 3, and the inside forms an angle θ ₁ on the left side and an angle θ ₂ on the outside with respect to a direction parallel to the lens optical axis, On the right side, the inside forms an angle θ ₁ ′ and the outside forms an angle θ ₂ ′. These angles are, for example, θ ₁ = 30 °, θ ₂ = 15 °, θ ′ = 45 °,
θ ₂ = 15 ′.

In the above process, the mold members 12, 12 'are connected to the thermocouples 24, 2
PID control is performed to a fixed point temperature based on the temperature measurement result by 4 '. The fixed point temperature can be appropriately changed.

The molded article molded as described above can be used as it is incorporated in a lens barrel, or can be used after removing the ear 32.

Since the grooves 34 and 36 are formed, the removal can be performed mechanically by generating a tensile stress at a desired position. That is, for example, it can be removed by applying force with a finger and splitting, or it can be removed by a drop impact from a slight height. The portion 32 can be removed by applying force.

FIG. 4 is a partial schematic sectional view showing the optical component body 30 from which the ears 32 have been removed.

As shown in the figure, the optical component main body 30 has slopes 35 and 37 which are a part of the grooves 34 and 36 on the outer peripheral portion thereof, and a fracture surface 40 for removing the ears. The fractured surface is grooved when the ear is removed.
Since breakage occurs stably from the bottom of the groove 34 to the bottom of the groove 36, it is formed at a desired position.

The slopes 35 and 37 function exactly as chamfers on both sides of the optical component body 30.

In the above press, the left mold set cannot be stopped by a stopper or the like, so that the press pressure can be applied evenly to the glass until the glass is hardened and the final shape of the molded product is determined, thereby causing sink marks on at least one surface. The precision of the molding surface of the mold member can be sufficiently sufficiently transferred to the molded product without occurrence. Note that the right mold set can be supported by a sufficiently large force at the stop position so as not to retreat in response to the pressing of the left mold set.

The thickness of the molded product is determined by the viscosity of the supplied molten glass, the temperature of the mold member, the pressing pressure, and other molding conditions. By appropriately adjusting these, a molded product of a desired thickness can be obtained. The viscosity of the supplied molten glass is
For example, it can be adjusted in the range of 10 ⁶ to 10 ² poise. The temperature of the mold member can be set, for example, in the range from the transition point to the strain point of the glass initially, and can be changed as necessary thereafter. The press pressure can be adjusted, for example, in the range of 1 to 500 kg / cm ₂ .

The thickness of the molded product is determined by the thickness of the groove forming ring 18,1.
It can also be adjusted by changing the amount of protrusion of 8 'from the mold member forming surfaces 12a, 12a'. The larger the amount of protrusion, the thicker the molded product.

FIG. 5 is a sectional view showing a modification of the above embodiment of the method for manufacturing a glass optical component according to the present invention. This figure shows the first
It is a figure corresponding to figure (b), and the same code | symbol is attached | subjected to the same member as the figure.

This modification differs from the embodiment of FIG. 1 only in that a groove forming ring is not provided around the right mold member 12 'and the outer diameter of the mold member 12' is large.

FIG. 5 shows a stopper 50 for setting the most forward stop position in the direction B of the right mold set.

Next, the result of specifically manufacturing a glass optical component using the above method is shown below.

Example 1: An apparatus as shown in Fig. 1 was used, except that the groove forming rings 18, 18 'were removed, and the outer diameter was 16.0mmφ, the maximum beam effective aperture was 14.8mmφ, the edge thickness was 1.33mm, and the wall thickness difference was 0.55. A double meniscus concave meniscus lens of mm was manufactured as follows.

 The diameter of each of the mold members 12, 12 ′ was 16.0 mmφ.

Heavy flint glass strain point temperature 378 ° C. at a transition temperature 455 ° C., allowed to flow down from the platinum nozzle 2 having an inner diameter of 15mmφ was stabilized as a viscosity 10 ^5.1 poise.

The pressing conditions were as follows: the initial mold member temperature was 360 ° C, the heating was stopped 2 seconds after the start of the press, the press pressure was 50 kg / cm ² ,
The pressing time was 9 seconds, and then the mold was released, and the press cycle was continuously performed.

Thus, 600 molded articles were obtained. Both surfaces of the main body portion of the molded optical component were optical surfaces having no surface defects and good appearance, and the surface accuracy thereof was uneven within 3 Newtons and within 1.5 Newtons. The thickness variation was ± 0.09 mm. This is sufficiently practical as an optical lens.

The molded product obtained in the present example can be formed into an optical lens having a normal shape by performing centering as required.

Example 2: Using an apparatus as shown in FIG. 5 above, an outer diameter of 21.0 mm
φ, maximum beam effective aperture 20.0mmφ, edge thickness 1.78mm, wall thickness 1.
A 42 mm bispherical convex meniscus lens was manufactured as follows.

The diameter of the mold member 12 is 21.10 mmφ, and the diameter of the mold member 12 ′ is 26.
0 mmφ, and the amount of protrusion of the tip of the groove forming ring 18 was 1.20 mm.

Heavy flint glass having a transition point temperature of 430 ° C. and a strain point temperature of 373 ° C. was stabilized from a platinum nozzle 2 having an inner diameter of 15 mmφ with a viscosity of ^4.7 poise and allowed to flow down.

The pressing conditions were as follows: the initial mold member temperature was 380 ° C., the temperature was 330 ° C. 3.5 seconds after the start of pressing, the pressing pressure was 40 kg / cm ² , the pressing time was 14 seconds, and the mold was released.

The concave surface of the main body portion 30 of the molded optical component thus obtained was an optical surface having no surface defects and good appearance, and the surface accuracy was sufficiently high at about 1 Newton. Further, the convex surface had such a degree that a slight sink mark was recognized at the center. Therefore, this optical component can be favorably used as a surface reflector by forming a reflection film on a concave surface. Further, the convex surface can be processed to have better surface accuracy and used as an optical lens.

Next, the change in the thickness of the molded product was measured by changing the amount of protrusion of the tip of the groove forming ring 18. In addition, molding was performed 100 times for the same protrusion amount. The results are shown in FIG.

As can be seen from FIG. 6, the thickness of the molded glass optical component can be adjusted by changing the amount of protrusion of the groove forming ring 18 from the mold member molding surface 12a.

Example 3 Using an apparatus as shown in FIG. 1 above, an outer diameter of 28.8 mm
φ, maximum beam effective aperture 27.0mmφ, edge thickness 2.18mm, thickness difference
A 0.89 mm bispherical convex meniscus lens was produced as follows.

The diameter of each mold member 12 is 28.8 mmφ, and the groove forming ring
The protruding amount of the tip of each of the 18, 18 'was set to 0.45 mm.

Heavy ground gas having a transition point temperature of 659 ° C and a strain point temperature of 602 ° C was passed through a platinum nozzle 2 having an opening of 25 mm x 5 mm to a viscosity of 1
Stabilized as ^3.7 poise and allowed to flow down.

The pressing conditions were as follows: the mold member temperature was 550 ° C., the pressing pressure was 18 kg / cm ² , the pressing time was 8 seconds, and then the mold was released.

Both surfaces of the main body 30 of the molded optical component thus obtained were optical surfaces having no surface defects and good appearance, and the surface accuracy was within 3 Newtons. The edge thickness of the molded optical component was within ± 0.05 mm from the target value of 2.18 mm.

In the above three examples, the pressing time was set after measuring and confirming that the glass temperature became equal to or lower than the strain point after the elapse of the pressing time.

In the above embodiments, the case where both surfaces of the molded optical component are spherical is shown, but it goes without saying that one or both surfaces can be aspherical.

[Effects of the Invention] As described above, according to the present invention, the molding die member is continuously pressed without closing the periphery between the pair of molding die members until the temperature becomes equal to or lower than the strain point of glass. By obtaining a glass molded product with ears protruding outside of the optical component body formed between them, dust is not generated at the time of pressing, so dust adheres to the molding surface of the mold member and surface accuracy Thus, an optical component having good optical characteristics can be obtained without deteriorating. Further, the pressing pressure can be uniformly applied to the glass until the glass is hardened and the final shape of the molded product is determined, whereby the accuracy of the molding surface of the mold member can be sufficiently improved without causing sink marks on at least one surface. And an optical component having a desired shape and accuracy can be easily obtained.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a schematic process of an embodiment of a method for manufacturing a glass optical component according to the present invention. FIG. 2 is a front view showing a molded product, and FIG. 3 is a schematic partial sectional view thereof. FIG. 4 is a partial schematic cross-sectional view showing the optical component body from which the ears have been removed. FIG. 5 is a sectional view showing a modification of the method for manufacturing a glass optical component according to the present invention. FIG. 6 is a graph showing a measurement result of a change in thickness of a molded product obtained by changing the amount of protrusion of the tip of the groove forming ring. 2: Nozzle, 4: Molten glass, 6: Shear, 12,12 ': Mold member, 12a, 12a': Molding surface, 18,18 ': Groove forming ring, 22,22': Heater, 24,24 ′: Thermocouple, 30: optical component body, 32: ear, 34, 36: groove, 35, 37: chamfer, 40: fracture surface.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Tsuyoshi Nomura 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Hiroyuki Kubo 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon (56) References JP-A-1-133948 (JP, A) JP-B-41-9190 (JP, B1)

Claims (4)

(57) [Claims] 1. A method of manufacturing an optical part having a surface corresponding to a molding surface of a mold member by pressing a flowing molten glass with a pair of molding mold members from both sides thereof. Is continued without closing the periphery between the pair of molding die members until the molten glass flowing down is cut above the pressed portion,
A method for manufacturing a glass optical component, which obtains a glass molded product having an ear portion protruding outward with respect to an optical component main body formed between the molding die members, wherein at least one of the molding die members is provided. A groove forming ring having a variable protrusion amount from the forming surface is provided around the forming surface, a groove is formed in the molten glass at the time of the pressing by the groove forming ring, and the groove forming ring protrudes from the mold member forming surface. A method for producing a glass optical component, comprising adjusting the thickness of a molded glass optical component by changing the amount. 2. A method for producing a glass optical component, comprising removing the ears of the optical component obtained by the method according to claim 1. 3. A method for manufacturing a glass optical component, wherein one surface of a main body portion of the optical component obtained by the method according to claim 1 is further processed into a desired shape and precision to form an optical component having a desired thickness. . 4. A glass optical component obtained by the method according to claim 1, wherein at least one surface is an aspherical surface.