JPH0415177B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method for uniformly chemically etching the surface of an elongated glass rod.

[Prior art]

The method of the present invention can be applied to a wide range of applications, and will be described below using the manufacturing process of a self-focusing lens as an example.

As is well known, a self-focusing lens is a lens body whose refractive index is maximum on the central axis and gradually decreases parabolically toward the periphery.Such a self-focusing lens has flare light (which has a negative effect on image quality). For the purpose of removing stray light, etc., fine irregularities are formed on the peripheral surface of the lens by chemical etching, and this etching has conventionally been carried out by the method shown in FIG. 4. In other words, as an example of a sample with a refractive index distribution after ion exchange in a molten salt bath, the diameter is approximately 1 mm.
In this method, a large number of elongated lens base material glass rods 1 having a length of about 1 m are suspended from a holder 2, immersed in an etching solution 3, and left standing.

[Problem to be solved]

In the above-mentioned conventional method, the reaction product between the glass and the etching solution adheres to the surface of the glass rod 1 over time, and this adhesion becomes an obstacle, causing a rapid decrease in the etching speed as a whole. Because the amount of etching on the kimono is uneven depending on location, there is a large variation in etching speed along the length of the glass rod. For this reason, even if the wire diameter is highly uniform in the length direction of the glass rod before the etching treatment, there is a problem in that after the etching treatment, large differences in wire diameter occur depending on the location.

Such variations in wire diameter can cause irregularities in the arrangement and deterioration of image quality when a lens array is produced by cutting the base material glass rod 1 into a predetermined length and converging and arranging the lenses. The wire diameter of the lens base material glass rod needs to be highly uniform.

[Solution]

In order to prevent the above etching unevenness,
A suitable number of the glass rods are suspended and held in a cylinder having a length sufficient to cover the entire length of the glass rod to be etched and having a uniform diameter in the length direction and open at both ends. The cylinder containing the glass rod is vertically immersed in the etching solution and moved up and down.

[Effect]

As the cylinder moves upward, the etching liquid moves inside the cylinder along the length of the cylinder, that is, along the length of the glass rod in the cylinder. In this way, the etching solution appears to flow on the surface of the glass rod, so
Reactants formed on the glass surface are immediately washed away, and new glass surfaces are always brought into contact with fresh etching solution. As a result, etching progresses uniformly over the entire length of the glass rod, making it possible to maintain a high degree of uniformity in wire diameter even after etching, and allowing rapid mass processing.

In addition, the cylindrical body of the present invention has the effect of rectifying the flow of the etching liquid that comes into contact with the glass rod to generate a laminar flow along the size direction of the glass rod, and when descending, the lower end of the suspended glass rod It plays a role in preventing diffusion and movement. Furthermore, compared to the case where the etching bath is fixed and the etching solution is flowed by a pump, it is easier to generate a high-speed liquid flow without causing any disturbance to the flow, and especially as the cross-sectional area of the liquid flow becomes larger, The superiority of the invention method increases,
Effective for mass processing.

〔Example〕

An embodiment of the present invention will be described in detail below with reference to FIGS. 1 to 3.

In FIG. 1, reference numeral 10 denotes an etching tank, and the etching tank 10 has a vertically long cylindrical shape and contains an etching solution 11 made of hydrofluoric acid or a mixed acid containing hydrofluoric acid. Then, an elevating body 1 is moved up and down in the etching liquid 11 by an external drive device (not shown).
A large number of glass rods 13 to be etched are suspended from this elevating body 12. More specifically, as shown in FIG. 2, the elevating body 12 is centered around a rod 14 that moves up and down, and a plurality of straightening cylinders 15 (six in the illustrated example) are perpendicularly arranged radially at intervals with respect to this rod 14. It is made up of fixed postures. These straightening cylinders 15 are cylinders made of a material that is corrosion resistant to the etching liquid 11, such as stainless steel or synthetic resin.
Both ends are open, the inner diameter is uniform over the entire length, and the length L ₂ is longer than the length L ₁ of the glass rod 13 suspended and held in this cylinder.
As shown in FIG.
It is held in 5.

That is, the hanging tool 16 has a structure in which a perforated plate 18 is fixed to the lower end of a bar material 17 that is placed on the upper edge of the cylindrical body 15 and locked. Hanging hole 1 provided
9 through which the glass rod is passed. glass rod 13
A spherical head 13 with a diameter larger than the wire diameter is pre-installed at the upper end.
A is formed by a method such as local melting of a glass rod, while the diameter of the hole 19 of the perforated plate 18 is the same as that of the glass rod 1.
3 and smaller than the diameter of the head 13A, so that the glass rod 13 is held suspended from the perforated plate 18 in a freely hanging state.

The perforated plate 18 also has a hole 1 for hanging a glass rod.
In addition to 9, a large number of liquid flow holes 20 are provided evenly scattered in order to smoothly flow the etching liquid into and out of the cylinder. This liquid flow hole 20 is formed when the glass rod 13 is attached by mistake.
Glass rod 13 to prevent it from being blocked by 3.
The diameter of the wire is smaller than that of the wire.

The elevating body 12, in which a large number of glass rods 13 are suspended and held as described above, is vertically moved up and down in the etching liquid 11. As the cylindrical body 15 moves upward, the etching liquid 11 apparently flows from the upper end of the cylindrical body 15 and passes through the liquid flow holes 20 of the perforated plate 18 and the gap between the outer periphery of the perforated plate and the inner wall of the cylindrical body 15. , flows in the length direction of the glass rod 13 while being rectified by the cylinder 15 and flows out from the lower end of the cylinder. Further, when the cylinder 15 is lowered, the water flows in from the lower end of the cylinder 15 and flows out from the upper end, contrary to the above.

By the alternating flow of the etching liquid 11 against the glass rod 13, reactants generated on the glass surface are washed away, and etching progresses evenly and uniformly over the entire length. Here, the moving distance of the cylinder 15
L ₃ is desirably at least equal to or larger than the length L ₂ of the cylindrical body 15 in order to keep the concentration of the etching liquid in contact with the glass rod ₁₃ constant over its entire length.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing an example of an apparatus for carrying out the present invention, FIG. 2 is a perspective view of an elevating body in the apparatus shown in FIG. 1, and FIG. 3 is a partial sectional view showing a method of supporting a glass rod to a cylinder. , FIG. 4 is a sectional view showing a conventional method. 11...Etching liquid, 12...Elevating body, 13
... Treated glass rod, 15 ... Cylindrical body, 16 ... Hanging tool, 18 ... Perforated plate, 19 ... Glass rod hanging hole, 20 ... Liquid flow hole.

Claims (1)

[Scope of Claims] 1. A method of chemically etching the surface of a long and slender glass rod by immersing it in an etching solution, which has a length sufficient to cover the entire length of the glass rod and is open at both ends. A suitable number of the glass rods are suspended and held in a cylinder having a uniform diameter in the length direction, and the cylinder containing the glass rods is vertically immersed in the etching solution and moved up and down. A glass rod etching method characterized by: 2. The method of etching a glass rod according to claim 1, wherein the vertical movement of the cylindrical body moves a distance at least equal to or longer than the length of the cylindrical body. 3. The method of etching a glass rod according to claim 1, characterized in that a plurality of the cylinders are attached to a common lifting member at intervals in a horizontal plane, and all the cylinders are moved up and down at the same time. 4. The method of etching a glass rod according to claim 1, wherein the cylinder has a cylindrical shape. 5 Suspension and retention of the glass rod in the cylindrical body:
A large-diameter head is formed at the upper end of the glass rod, and the glass rod is inserted into a hole in a perforated plate provided in a holder that is locked to the cylinder and is locked at the head. Characteristic claim 1
Etching method for glass rods as described in section. 6. The method of etching a glass rod according to claim 5, wherein the perforated plate is provided with etching liquid flow holes having a diameter smaller than that of the glass rod.