JPS5835660Y2 - Spherical inner surface electrolytic polishing device - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an improvement in a spherical inner surface electrolytic polishing device used for electrolytically polishing the inner surface of a spherical gas tank such as one mounted on a space rocket.

Generally, an electrolytic polishing method or a chemical polishing method is often employed to polish the inner surface of a sphere.

This chemical polishing has the disadvantage that the polishing quality is considerably inferior to that of electrolytic polishing.

On the other hand, electrolytic polishing has the advantage that the inner surface of the sphere can be polished to a mirror surface.

That is, in the conventional electrolytic polishing apparatus, as shown in Fig. 1, a spherical stainless steel tank manufactured by drawing is connected to the anode 11.
Then, a stainless steel rod is inserted as a cathode 13 into the tank from a small insertion port 12 at the top of the tank, and the insertion port 12 and cathode 13 are insulated with an insulating vinyl 14. Furthermore, the polishing liquid 15 is poured into the tank from the insertion port 12. A DC power source 17 is connected between the protruding end of the cathode 13 and the anode take-out portion 16.

In such a conventional electrolytic polishing method, the inner surface of the tank, which is the anode 11, can be polished to a mirror surface, but since the anode 11 is spherical in contrast to the rod-shaped cathode 13, the center and upper and lower parts of the tank can be polished to a mirror surface. In this case, the distance between the electrodes differs greatly, which causes variations in the current distribution on the anode 11, which has the disadvantage that uniform polishing cannot be achieved.

Further, hydrogen gas is generated during polishing, but the insertion port 12 is small because the diameter is limited to the minimum necessary in order to obtain the mechanical strength of the tank, and hydrogen gas cannot easily escape from the insertion port 12.

Therefore, the polishing liquid in the tank overflows from the insertion port 12 due to the pressure of this gas.

Alternatively, gas may accumulate in the tank, increasing liquid resistance and eventually electrolyzing the water, reducing current efficiency and increasing power consumption.

In addition, since the cathode 13 is formed thin so that it can be inserted through the small insertion opening 12, the surface area of the cathode 13 is naturally extremely small compared to the inner surface area of the anode 11, so the current efficiency is less than 100%, and the gas The occurrence becomes more pronounced.

The present invention was developed to eliminate the above-mentioned drawbacks. By forming the outer surface of the cathode part inserted into the spherical anode in a similar shape to the inner surface of the anode, the current distribution on the anode is suppressed and uniform. The object of the present invention is to provide an electrolytic polishing device for the inner surface of a sphere, which can polish the surface of the sphere and improve the current efficiency by improving the area ratio of the cathode to the anode.

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

In Fig. 2, 11 is a cathode, which is made of, for example, a spherical stainless steel tank manufactured by drawing, and a cathode insertion port 12 of a size determined in consideration of the mechanical strength of the tank is provided in the upper part of the tank. There is.

On the other hand, the cathode 20 has an arcuate portion 22 formed at the lower end of a rod-shaped portion 21 and curved in a shape similar to the inner surface of the tank.

This arcuate portion 22 and the rod-shaped portion 2 connected thereto
1 is inserted into the tank through the insertion port 12.

The upper end of the rod upper part 21 is connected to the chuck 2 of the motor 23.
It is held between 4.

In this case, the rod upper portion 21 is located on the same axis as the tank center axis.

A portion of the rod-shaped portion 21 from the boundary with the arcuate portion 22 to a position slightly above the insertion port 12 is covered with an insulating material, for example, an insulating vinyl 14.

Thereby, the cathode 20 and the anode 11 are insulated.

Furthermore, the amount of thrust of the rod-shaped portion 21 into the tank is the same as that of the arc-shaped portion 2.
The distance between the outer surface of the tank 2 and the inner surface of the tank opposite thereto is determined to be constant.

A slip ring 25 is arranged so as to be in sliding contact with the outer peripheral surface of the rod-shaped portion 21 outside the tank.
. . . A DC power source 17 is connected between the anode extraction portion 16 and the anode extraction portion 16.

Further, a polishing liquid 15 is injected into the tank.

According to the electrolytic polishing apparatus configured as described above, the arcuate portion 22 of the cathode 20 is curved to resemble the inner surface of the tank, and when the cathode 20 rotates with the rotation of the motor 23, the arcuate portion 22
2 rotates around the central axis of the tank, and the electrode spacing between the outer surface of this rotating arcuate portion (rotating outer surface) and each part of the inner surface of the tank is constant.

Therefore, variations in the current distribution on the anode 11 are suppressed, so that uniform polishing is performed and the inner surface of the tank becomes a uniform mirror surface.

In this case, the electrode interval between the rotating outer surface of the arcuate portion 22 and the inner surface of the tank is within a predetermined range (for example, 0.5 cm or more and 3 crn
below.

) is set. The reason for this is that if the electrode spacing is too small, a large current will locally occur on the anode 11, making it difficult to polish uniformly and creating a risk of short circuit between the electrodes.

On the other hand, if the electrode spacing is too large, the voltage drop within the polishing liquid 15 will increase, making it impossible to obtain sufficient polishing.

Further, the thickness of the arcuate portion 22 is preferably as thick as possible in the sense of reducing the area ratio between the anode 11 and the cathode 20 and increasing current efficiency, but is naturally limited by the size of the insertion port 12.

However, in the above embodiment, the ratio of the anode area to the cathode area is equivalently reduced as the cathode 20 rotates, so the current efficiency is improved and the amount of hydrogen gas generated is suppressed.

Further, since the polishing liquid 15 is stirred by the rotation of the cathode 20, the polishing liquid 15 is used efficiently, and the gas generated at the same time is quickly discharged from the insertion port '12.

Note that the rotation speed of the cathode 20 is within a predetermined range (for example, 100 to 5
00 V, p, m).

The reason is that if the rotation speed is too low, the effect of reducing variations in current distribution on the anode 11, in other words, the effect of obtaining a uniform polished surface will be reduced.

On the other hand, if the rotation speed is too high, the polishing liquid 15 will overflow from the insertion port 12 to the outside of the tank, which is dangerous, and since a space is created in the tank, the voltage drop during polishing will increase, making it impossible to obtain sufficient polishing. do not have.

In the above embodiment, since the arcuate portion 22 of the cathode 20 is semi-circular and long, it may be difficult to insert the cathode 20 through the insertion port 12.

Therefore, the length of the arcuate portion was shortened to facilitate insertion of the cathode (see FIG. 30).

), the same effect as in the above embodiment can be obtained.

Furthermore, as shown in FIG. 4, a cathode 40 having a spiral portion 42 at the lower end of a rod-shaped portion 41 may be used.

The outer surface of this spiral portion 42 is formed into a spherical shape similar to the inner surface of the tank, and the center of the spiral portion 42 coincides with the center inside the tank. The facing distance is kept constant.

Further, the electrode spacing between this spiral portion 42 and the inner surface of the tank is set within a predetermined range (for example, 0.5 to 3 cm as described above), and the total surface area of the spiral portion 42 is at least h or more than the surface area of the inner surface of the tank. The number of turns and the thickness of the material used are determined so that

In this way, the cathode 40 having the spiral portion 42 can generate a substantially uniform current distribution on the inner surface of the tank without rotating, and the area ratio of the spiral portion 42 and the inner surface of the tank is smaller than that of the cathode 20. Since it is sufficiently large compared to the arcuate portion 22, the current efficiency can be increased and a nearly uniform mirror surface can be obtained.

Although the spiral portion 42 as a whole is wider than the insertion port 12, it can be inserted into the tank from the insertion port 12 by screwing.

In FIGS. 3 and 4, the same parts as those in FIG. 2 are designated by the same reference numerals, and the explanation thereof will be omitted.

As mentioned above, the present invention has the outer surface of the cathode inserted into the spherical anode similar to the inner surface of the anode, thereby suppressing variations in the current distribution on the anode and achieving uniform polishing. It is possible to provide a spherical inner surface electrolytic polishing device that can improve current efficiency by improving the area ratio of .

[Brief explanation of the drawing]

Fig. 1 is a structural explanatory diagram showing a conventional electrolytic polishing device, Fig. 2 is a structural explanatory diagram showing an embodiment of a spherical inner surface electrolytic polishing device according to the present invention, and Figs. 3 and 4 are respectively diagrams of the present invention. FIG. 7 is a configuration explanatory diagram showing another embodiment. 11... Anode, 12... Insertion port, 20
, 40... cathode, 22... arcuate portion,
42...Spiral part.

Claims (3)

[Scope of utility model registration request] (1) In a device that performs electrolytic polishing of the inner surface of a sphere by inserting a part of the cathode through an insertion opening provided in a part of the sphere that will serve as the anode, the outer surface of the inserted cathode portion is similar to the inner surface of the sphere. 1. A spherical inner surface electrolytic polishing device, characterized in that the spherical inner surface electrolytic polishing device is arranged so as to face each part of the spherical inner surface at approximately constant intervals. (2) The electrolytic polishing apparatus for the inner surface of a sphere according to claim 1, wherein the cathode portion is curved in an arcuate shape and is driven to rotate around the center axis of the sphere. (3) The spherical inner surface electrolytic polishing apparatus according to claim 1, wherein the cathode portion is formed by a cathode rod wound spirally.