JPS6121934A - Etching process of glass bar - Google Patents

Abstract

PURPOSE:To keep high degree of uniformity of diameter of a glass bar for over the whole length of the glass bar in the process for etching a glass bar by dipping the bar in an etching liquid by dipping a cylindrical body having a specified length and contg. a glass bar built therein vertically in the liquid and moving the cylindrical body upward and downward. CONSTITUTION:A vertically movable body 12 movable by an external driving device is dipped in the etching liquid 11 held in a longitudinally cylindrical etching tank 10 and many glass bars 13 are suspended therein. The vertically movable body 12 is constructed by fixing plural numbers of flow straightening cylindrical body 15 vertically and in the radial direction with a certain distance to each other. The cylindrical body 15 is a circular cylinder opened at both ends with uniform inside diameter over its whole length and the length L2 being longer than the length L1 of the bar 13. The bar 13 is inserted into a hole 19 for suspending the bar perforated on a plate 18 fitted to a suspending attachment fixed to the cylindrical body 15, and retained by a spherical head at the top end of the bar. Many holes 20 for making inward and outward liquid flow 11 smoother are provided to the perforated plate 18. When the vertically movable body 12 is moved vertically in the liquid 11, reaction poduct formed on the glass surface is washed away, and uniform etching over the whole length of the bar 13 is processed.

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 explained below by taking the manufacturing process of a self-focusing lens as an example.

As is well known, a self-focusing lens is a lens body with a distribution in which the refractive index is maximum at the center and gradually decreases towards the periphery, and such a self-focusing lens is free from flare light (which has a negative effect on image quality). For the purpose of removing stray light, etc., the peripheral surface of the lens is chemically etched to create fine irregularities, and this etching has conventionally been done using the method shown in Figure 1.

That is, as an example of a lens having a refractive index distribution after ion exchange in a molten salt bath, a large number of elongated lens base material glass rods each having a diameter of approximately /mm and a length of approximately /m are suspended from a holder 2. This is a method of immersing it in etching solution 3 and leaving it still.

[Problem to be solved]

In the conventional method described above, as time passes, reaction products between the glass and the etching solution adhere to the surface of the glass rod l, and this adhesion becomes an obstacle, causing a rapid decrease in the etching rate as a whole. Since the amount of marking on the kimono is uneven depending on the location, the etching speed and large variations occur in the length direction 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 process, there is a problem in that after the etching process, there is a large difference in the wire diameter depending on the location.

Such variations in wire diameter will cause irregularities in the arrangement and deterioration of image quality when a lens array is produced by cutting the base material glass rod l to 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-mentioned etching unevenness, the glass is placed in a cylindrical body with a uniform diameter in the longitudinal direction, which is long enough to cover the entire length of the glass body to be etched, and which is open at both ends. An appropriate number of rods are suspended and held, and the cylindrical body containing the glass rods is vertically immersed in the etching solution and moved up and down.

[For production]

As the cylinder moves up and down, the etching liquid moves in 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 over the surface of the glass rod, so that 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 also 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 length 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 the larger the cross-sectional area of the liquid flow, the more The advantages of the invented method are increased and it is effective in 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/l of hydrofluoric acid or a mixture containing hydrofluoric acid. An elevating body 12, which is moved up and down by an external drive device (not shown) K, is immersed in the etching solution, and a large number of glass rods 13 to be etched are suspended from this elevating body 12. More specifically, as shown in FIG.
It is constructed by fixing a plurality of (six in the illustrated example) vertically. These straightening cylinders IS are cylinders made of materials such as stainless steel and synthetic resin that are corrosion resistant to etching solutions.Both ends are open, and the inner diameter is uniform over the entire length. L2 is longer than the length Ll of the glass rod 13 suspended and held in this cylinder.

As shown in FIG. 3, the etched glass rod 13 is held in the cylinder lj via a glass barrel hanging device 16.

That is, the hanging tool /4 has a structure in which a perforated plate /g is fixed to the lower end of the bar material 17 that is placed on the upper edge of the cylinder /j and locked. The glass rods are passed through the hanging holes/walls provided in large numbers. A spherical head 13k having a diameter larger than the wire diameter is previously formed at the upper end of the glass rod 3 by a method such as local melting of the glass rod, while the diameter of the hole 19 in the perforated plate /3
The diameter of the glass rod 3A is larger than that of the wire and smaller than the diameter of the head 3A, so that the glass rod 3 is held hanging freely between the perforated plate 3A.

In addition to the glass rod hanging holes 19, the perforated plate/IVc is provided with a large number of liquid flow holes 2o evenly spaced KM apart from each other in order to smooth the inflow and outflow of the etching liquid into the cylindrical body. This liquid flow hole 2o is made smaller than the wire diameter of the glass rod /3 so that the hole 2o will not be accidentally blocked by the glass rod 13 when the glass rod 13 is attached.

The elevating body 12, in which a large number of glass rods 3 are suspended and held as described above, is vertically moved up and down in the etching solution 11. Cylinder l! Due to the upward movement of the etching liquid /l, the etching liquid /l apparently flows from the upper end of the cylinder lS, and the etching liquid /l flows into the perforated plate lS.
After passing through which liquid flow hole 20 and the gap between the outer periphery of the perforated plate and the inner wall of the cylinder /j, the liquid flows through the glass rod / while being rectified by the cylinder /S.
3 and flows out from the lower end of the cylinder. Further, when the cylinder /3 is lowered, the air flows in from the lower end of the cylinder IS and flows out from the upper end, contrary to the above.

By the alternating flow of the etching solution to the glass rod 13, reactants generated on the glass surface are washed away, and etching progresses evenly and uniformly over the entire length. Here is the cylinder l! For movement 1) 1! It is desirable that L3 be at least equal to or larger than the length L2 of the cylinder /j in order to keep the concentration of the etching liquid in contact constant over the entire length of the glass rod /3.

[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. 3 is a sectional view showing a conventional method. /7--, etching liquid 12--lifting body t3-@,
Processed glass barrel 15...Cylinder 16...Hanging tool
/I...Perforated plate/9...Glass rod hanging hole λO...Liquid flow hole Figure 1 Figure 2 Figure 3 Figure 4

Claims (6)

[Claims] (1) In a method in which a long and thin glass rod is immersed in an etching solution and the surface of this glass rod is chemically etched,
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 rods and having a uniform diameter in the length direction and open at both ends, and the glass rods are incorporated therein. A method for etching a glass rod, characterized in that the cylindrical body is vertically immersed in an etching solution and moved up and down. (2) The method for etching a glass rod according to claim 1, wherein the vertical movement of the cylinder moves a distance at least equal to the length of the cylinder. (3) The method for etching a glass rod according to claim 1, in which a plurality of the cylindrical bodies are attached to a common elevating member at intervals in a horizontal plane, and all of the cylindrical bodies 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) In claim 1, the glass rod is suspended and held in the cylindrical body by forming a head with a large diameter at the upper end of the glass rod and locking the glass rod in the cylindrical body. A method for etching a glass rod, which comprises passing the glass rod through a hole in a perforated plate provided in a holder and locking the rod at the head. (6) The method for etching a glass rod as set forth in claim page 5, wherein the perforated plate is provided with etching liquid flow holes having a diameter smaller than that of the glass rod.