JPS63143299A - Method for electrolytically polishing inside surface of long-sized small-diameter pure ni pipe - Google Patents

Abstract

PURPOSE:To permit smoother finishing of the entire part with one time of polishing by using a cathode bar longer than the length of a small-diameter pipe to be polished in a method for using the cathode bar formed by spirally winding fabric wire rods made of soft insulating fibers around a straight bar-shaped arbor. CONSTITUTION:The cathode bar 1 formed by spirally winding the fabric wire rods 3 made of the soft insulating fibers around the straight bar-shaped arbor 2 is inserted into the long-sized small-diameter pipe 4 which is an anode and while an electrolyte is supplied into the pipe 4, the bar 1 and the pipe 4 are relatively rotated and moved back and forth. The stable current density optimum for the electrolytic polishing is as low as about 20-40A/dm<2> if the pipe 4 is of pure Ni in this electrolytic polishing method. The stable current of the copper arbor 2 having about 2-2.5mm diameter in the liquid is, therefore, about 60A. The bar 1 can be consequently made as long as 1,500-2,000mm in order to obtain the above-mentioned stable current density. As a result, the polishing to the electrolytic surface which is free from gas pits and etching surface, has <=1muRmax surface roughness and is uniform over the entire length is permitted by one time of the electrolytic polishing.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a method for electropolishing the inner surface of a pure Ni long narrow diameter tube.

[Prior Art] In recent years, especially in the semiconductor industry, which has been rapidly developing, high purity gases used in the manufacturing stage are required as the scale of semiconductor integration increases, and there is a need to improve the cleanliness of the gases.

For this reason, there are strict regulations regarding piping members for transferring and supplying gas, and it is desired to supply products with high cleanliness (clean and smooth) inner surfaces of piping members.

As for this cleanliness, the tube inner surface roughness is RmaxO63~
Since a quality of approximately 0.6 μm is required, it is impossible to achieve this through cold working, mechanical puff polishing, or chemical polishing. Electrolytic polishing has been adopted as a means to achieve this and improve corrosion resistance. .

On the other hand, recently, chlorine-based highly corrosive gases have begun to be used, so the material of the pipes has changed to 5U.
The transition from S316L to pure Ni has begun.

By the way, what is the technique for electropolishing the inner surface of long tubes?

■As shown in FIG. 6, a cathode $1 has a Teflon band 102 spirally wound around the outer periphery of a straight rod-shaped Cu core metal 101.
A method has been developed in which an i103 is inserted into a long tube 104 serving as an anode, and the cathode rod 103 is moved in the tube axis direction while supplying an electrolyte 105 into the long tube 104. Compared to using a CU core metal as the cathode rod, we achieved certain effects in reducing gas pits and improving the texture of the material, and succeeded in achieving a tube inner surface roughness of Rmax 1 lm or less. are doing.

■Also, as shown in FIG. 6, the present inventor has previously constructed a cathode rod 22 in which a fabric wire 35 made of flexible insulating m fibers is spirally wound around the outer periphery of a straight bar-shaped core bar 34. It is inserted into the long tube 21 which is used as an anode, and while supplying electrolyte into the long tube 21, the cathode #! A method is proposed in which relative rotation is applied between the J22 and the long tube 21, and the cathode rod 22 is moved in the axial direction. Regarding the method of electrolytic polishing of the inner surface of a tube, the following problems may occur in the above method.

■The technique described in ■ above is judged to be good for the reduction of gas pits and smooth finish, but it still leaves much to be desired due to the occurrence of gas beats/pits, gas grooves, and unevenness caused by the gas generated during electrolysis. Due to the problem of not being able to obtain a micro-smooth surface, devices such as forced electrolyte flow cylinders have been developed to allow the gas to quickly flow out together with the electrolyte and to control the flow rate. Although improvements have been made to obtain a smooth surface, there is currently a need for an even smoother finish.

(2) If the technique (2) above is applied to a pure Ni long narrow diameter pipe, the following problem will occur.

In other words, in the case of a small diameter tube of 6.5 mm or less, if you try to quickly release the gas generated during electrolysis outside the tube by making the electrolytic solution flow, the diameter of the Cu core metal is 2 to 2 mm.
．． It can be kept at 5φ. However, Cu with a diameter of 2 to 2.5φ
Since the safe current of the core metal in the liquid is about 60 A, the stable current density (85 to 100 A/d) is optimal for electrolytic polishing.
(Fig. 8(a)), the cathode rod is 400~
It has to be shortened to 500mm, so 500mm
In order to electrolytically polish the long tube as described above, the cathode rod must be moved.

However, when the cathode rod is moved in this way, the part where the cathode rod no longer exists after the movement (part A in Figure 9) becomes N.
In the case of an i-tube, there is a problem in that it is not possible to obtain a uniform electrolyzed skin over the entire length because it is immediately etched.

In addition, if the tube is longer than 500 mm, it is necessary to move the cathode rod, so there is a problem that polishing cannot be performed by polishing twice, and electrolytic polishing takes time.

The present invention has: ■ No gas bits; ■ Surface roughness of Rmax lm or less; ■ No etching skin; ■ Uniform electrolytic surface along the entire length; ■ Can be polished entirely by electropolishing - times. An object of the present invention is to provide a method for electrolytic polishing of pure Ni long narrow diameter tubes.

[Means for Solving the Problems] Therefore, in order to solve the above-mentioned problems, the present inventor conducted extensive research and first investigated the characteristics of the voltage current density of pure Ni tubes.

As a result, as shown in FIG. 8(b), it was found that the optimum stable current density for electrolytic polishing in the case of a pure Ni tube is approximately .about.% of that in the case of 5US316L.

Therefore, since the safe current in liquid for a Cu core metal of 2 to 2.5φ is about 60 A, the optimum current density for electrolytic polishing is (20 to 4 OA/drrr') (Fig. 10(a)
), the cathode rod can be made as long as 1500 to 2000 mm.

For this reason, we have found that it is possible to electrolytically polish a pure Ni long narrow diameter tube of 1500 mm or more.

The present invention has been made based on this knowledge.

(Structure of the Invention) In other words, the wooden invention has three cloth wires made of flexible insulating fibers wrapped around the outer periphery of a straight bar-shaped core bar, and which is electrolytically polished. A cathode rod that is longer than the long thin tube used as an anode is inserted into the long thin tube, and while an electrolyte is supplied into the long thin tube, the cathode rod and the long thin tube are connected. A method for electrolytic polishing of the inner surface of a pure Ni long thin-diameter tube, characterized by performing electrolytic polishing at a current density of 20 to 40 A/dm'' while applying relative rotation and reciprocating motion to the long thin-diameter tube. Pertains to.

The present invention will be explained in detail below.

The cathode rod in the present invention is formed by winding a flexible fabric wire made of insulating mta in a spiral shape around the outer periphery of a straight rod-shaped core metal.

The basic concept of the cathode rod of the present invention, in which a fabric wire is spirally wound, is shown in FIG.

In Fig. 1, 1 is a cathode rod, and the outer periphery of a straight rod-shaped core metal 2 has a flexible insulating material! It has a configuration in which a cloth wire material 3 made of A-fiber is wound in a spiral shape.

With such a configuration, the inner surface of the long tube 4 is covered with the cloth wire 3.
When the outer circumferential side of is electrolytically polished while sliding in the circumferential and axial directions, the distance between the surface of the core bar 2, which is the cathode surface, and the inner surface of the long tube 4, which is the anode surface, is the same as that of the cloth wire that is an insulator. 3, the current density is always kept constant, the current density is stabilized, and the core bar 2 does not come into contact with the inner surface of the long tube 4 and cause damage. Electrolysis is further promoted by stirring the mucosal layer.

The gas generated by electrolysis is caused by the electrolytic solution 5 constantly flowing through the spiral channel formed by the cloth wire 3, and the electrolytic solution 5 quickly releasing the gas to the outside of the tube. It can prevent bits and gas grooves from forming.

Here, the core bar 2 may be of any type as long as it is not corroded by the electrolytic solution 5, but it is preferable that the core bar 2 has low resistance and low power loss, and is generally made of Cu. is used as the material.

It is obvious from the above that the wire 3 must be made of insulating fiber, but at the same time it must be made of a cloth made of flexible fibers. If a solid wire is used, it will damage the inner surface of the long tube 4, making it impossible to obtain a ground surface with a small degree of roughness, and if it is made of cloth, flexible sliding contact with the inner surface of the long tube 4 will be prevented. This is convenient because the rotation causes the electrolyte to seep into the inside of the cloth.

From the viewpoint of flexibility and corrosion resistance against the electrolytic solution 5, polypropylene fibers are considered to be the most suitable material for such fibers.

FIG. 2 shows an example of how to wind the fabric wire 3 around the core metal 2. A spiral groove 6 is formed on the outer periphery of the core metal 2, and the wires are wound along the groove 6. A method is adopted in which the cloth wire 3 is rolled up. By configuring like this,
Even when the cloth wire slides on the inner surface of the long tube 4, the core metal 2
This has the advantage that it is fixed so as not to move in the axial direction of the electrolytic solution 5, so that the flow path of the electrolytic solution 5 can be kept constant, and the electrolytic conditions can be stabilized. Note that the groove 6 may be formed by liquid honing, for example.

Furthermore, this cathode rod is longer than the long narrow diameter tube to be electrolytically polished, so that the occurrence of the etching phenomenon described in [Problems to be Solved by the Invention C] can be prevented.

The length of this cathode bar is preferably 1500 to 2000 mm.

The optimum stable current density for electrolytic polishing for Ni tubes is 20 to 40 A/2 as described above and shown in Figure 8(b).
drrT', if electrolytic polishing is performed at the same electric ffi and density, even if the length of the cathode rod is 1500 to 2000 mm and the Cu core metal is 2 mm in diameter, the safe current of the Cu core metal will not be exceeded.

In addition, for example, two cathode rods each having a length of 2000 mm may be connected via an insulator. In this case, the length of 4000 m
Electrolytic polishing of a long tube of m is the turning part.

In the present invention, the above cathode rod is used, the cathode rod is inserted into a long thin diameter tube serving as an anode, and while an electrolyte is supplied into the long thin tube, the cathode rod and the long thin tube are Electrolytic polishing is performed while applying rotation and reciprocating motion relative to the small diameter tube.

Here, as a means for supplying the electrolytic solution into the long narrow diameter tube, for example, the means shown in FIG. 3 may be used. Of course, other means may also be used.

In the present invention, relative rotation and reciprocation are applied between the cathode rod and the long thin tube during electrolytic polishing. "Giving reciprocating motion in the direction" is realized by moving both or one of the cathode rod and the elongated tube in such a manner. However, even when reciprocating motion is applied, the cathode rod is always inside the long narrow diameter tube.

The reason for giving reciprocating motion in the axial direction in this way is to prevent unevenness in electrolytic polishing and to provide a uniform electrolytically polished surface over the entire tube.

Note that any known common means may be used to apply the rotational and reciprocating M'iEJ to the cathode and/or the long thin diameter tube.

Note that the present invention is particularly effective when applied to a long tube having an inner diameter of 6.25 mmφ or less.

[Example] FIG. 4 is a front view showing the entire apparatus for carrying out the method of electropolishing the inner surface of a long tube according to the present invention.

In Figure 4, 4 is approximately 4 m in length and 6.25 mm in inner diameter.
This is a long, small-diameter tube that is to be polished.

Also, ■, 1' are cathode rods, and in this example, the long thin diameter tube is 4 m long, so as shown in Fig. 5, two wooden cathode rods 1, 1' are cathode rods.
1'' are connected via an insulator 30. Note that the joint portion is insulated by a Teflon heat-shrinkable tube 31. This joined cathode rod is inserted into the long narrow diameter tube 4 via the electrolyte flow tube 23.

The temperature of the electrolyte is adjusted in a tank (not shown), and a filter (not shown) is passed through a pump (not shown).
, a quantity adjusting stirrup (not shown), a reverse action valve (not shown), etc., are sent to the flow tube 23 through a series of piping paths, and flowed into the long small diameter pipe 4. After passing through the tube 4 it is discharged into the drainage box 15.

The long thin diameter tube 4 serving as the anode is fixed to the tip of the drum body 28 by an air checker 26 at the end face on the left end in the drawing. This drum body 28 is fixed to a tube rotation motor 27, and therefore, the long narrow diameter tube 4 is rotated by the tube rotation motor 27.

On the other hand, a dummy tube 13 is provided at the right end of the long narrow diameter tube 4 in the drawing, and the bearing of this dummy tube 13 is supported by a dummy tube current carrying body 14 having a shaped portion.

Furthermore, two anode current-carrying rollers 9, 9' are electrically connected to the surface of the long thin-diameter tube 4, and the long thin-diameter tube 4 is connected via the anode current-carrying rollers 9, 9'. It is designed to energize.

On the other hand, the cathode rod formed by joining two wooden cathode rods 1.1', on the left side in the drawing, has a drum body 28, a tube rotation motor 27, and a fluidizing cylinder 23 fitted therein, and a tension rubber at its left end. It is supported by 31.

On the other hand, on the right side in the drawing, a waste liquid box 17 is inserted and supported by a cathode checking 17 at its right end.

The cathode bar 1 on the left side of the drawing is energized through the first cathode joint 32, and the cathode 1'' on the right side of the drawing is energized through the cathode checking 17 and the second cathode joint 18.

Further, the entire cathode is caused to reciprocate in the axial direction by being driven by a cathode back and forth drive section 19.

The cathode rod 1.1'' has a spiral groove formed on the outer circumferential surface of a core metal 2, which is a tube made of Cu, and a cloth wire material 3 made of polypropylene fiber is wound along the groove. .

In addition, the mechanism of the anode energizing roller must have the function of energizing the long narrow diameter tube 4 that rotates once, and the 6th
As shown in the figure, the receiver connects a long narrow diameter tube 41 supported by a roller 42 to a current-carrying portion 43 from above, and a current-carrying roller 4 elastically supported by a spring 45.
It uses a mechanism that presses with 4. Note that the receiver 46 is an adjustment screw for adjusting the height of the roller by yA.

In conventional anode energizing devices, a copper plate was fitted around the outer periphery of a long thin tube to apply electricity, which caused scratches on the outer periphery of the long thin tube due to sliding, but by adopting this mechanism. Therefore, current can be applied without causing scratches, and the contact area, which greatly affects the amount of current applied, can be sufficiently secured by providing a plurality of anode current-carrying rollers.

According to this embodiment, it is possible to electrolytically polish the inner surface of a pure Ni long thin diameter pipe with a very small roughness without gas pits, gas grooves, or uneven undulations. It is possible to obtain a long, narrow diameter tube, and since no scratches occur on the outer circumferential surface, the commercial value can be improved.

Using the apparatus of the above example, electrolytic polishing was performed on the inner surface of a long, small diameter tube with an outer diameter of 6.35 mm and an inner diameter of 4.35 mm, but in both cases the inner surface roughness was Rmaxo, 5.
A very clean polished surface of JA m can be obtained,
Also, no gas bits were observed, and no etched skin was observed.

In addition, in the above example, the case of a 4 m long small diameter pipe was explained, but in the case of a 2 m long small diameter pipe, electrolytic polishing can be performed with a simpler configuration by using one cathode. I can do it.

[Effects of the Invention] As described above, the present invention relates to a method for electropolishing the inner surface of a pure Ni long thin-diameter tube. By adopting a special winding configuration, and applying circumferential rotation and axial movement to long, small-diameter tubes within the tube, electrolytic polishing is performed while the fabric wire is in sliding contact with the inner surface of the tube. effect can be obtained.

■It is possible to obtain a pure Ni tube with a very high degree of cleanliness over the entire length of the tube.

■It is possible to obtain an electrolytically polished surface free of gas bits, gas grooves, and unevenness.

(2) An electrolytically polished surface having a surface roughness of Rtaax O, 5 pm or less can be obtained.

■An electrolytically polished surface without etched skin can be obtained.

(2) The entire surface can be polished by electrolytic polishing twice.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing the basic concept of the cathode rod according to the present invention. FIG. 2 is a side view showing the core metal of the cathode rod according to the present invention. FIG. 3 is a sectional view showing the electrolyte supply means. FIG. 4 is a side view showing an apparatus for carrying out the invention. FIG. 5 is a sectional view showing the joint portion of the cathode rod. FIG. 6 is a side view showing the mechanism of the energizing roller. FIG. 7 is a sectional view showing a conventional example. FIGS. 8 and 9 are sectional views showing other conventional examples. FIG. 10 is a graph showing voltage-current density characteristics of electrolytic polishing for 5US316L and pure Ni tubes. Description of symbols 1.1°... cathode rod, 2... Φ core metal, 3... cloth wire made of flexible insulating fiber, 4... long thin diameter tube, 5... electrolyte, 6... screw Linear groove, 9.9゛...Anode energized roller,
13. Dummy tube, 14. Dummy tube energizing body, 15 Fist.
Drainage box, 16... Sleeve, 17... Cathode checking, 18... Second cathode joint, 19... Cathode front and back diversion part, 21... Long tube, 22... Cathode rod, 23 Fluid cylinder,
24. Fist/Mechanical Seal King, 27.. Pipe rotation motor, 28.. Drum body, 3.
0・φ insulator, 31...Teflon heat shrink tube, 31
...Tensile rubber, 32.. First cathode joint, 34. Core metal 35.. Cloth wire, 38.. Cathode electrolysis section, 42.--Receiver is roller, 43. Current-carrying section, 44. φ presser power-carrying roller,
45 war/spring, 101**cu core metal, 102--
Teflon band, 103, fist cathode rod, 104...long tube, 105Φ electrolyte. Figure 1 Figure 2

Claims (4)

[Claims] (1) A fabric wire made of flexible insulating fibers is spirally wound around the outer periphery of a straight rod-shaped core metal, and the cathode rod, which is longer than the long thin diameter tube to be electrolytically polished, is used as an anode. The cathode rod is inserted into the long thin tube, and while an electrolyte is supplied into the long thin tube, the cathode rod and the long thin tube are rotated relative to each other. A method for electropolishing the inner surface of a pure Ni long narrow-diameter tube, which is characterized in that electrolytic polishing is performed while applying reciprocating motion. (2) A method for electropolishing the inner surface of a pure Ni long narrow diameter tube according to claim (1), wherein the current density is 20 to 40 A/dm^2. (3) Claim (1) or (2) wherein the flexible insulating fibers constituting the cloth wire are polypropylene fibers.
) The electrolytic polishing method for the inner surface of a pure Ni long narrow diameter tube. (4) Claims (1) to (3) above, wherein the cathode rod has a spiral groove formed on the outer periphery of the metal core, and a cloth wire is wound along the groove. Pure Ni described in any of
Electrolytic polishing method for the inner surface of a long narrow diameter tube.