DE8613637U1 - Device for electrochemical polishing of the inner surfaces of pipes - Google Patents

Description

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PATENT LAWYERS ■ · · · · · · ·

WUESTHOFF-ν. PECHMANN ^ BEHRENS-'GÖETZ '' •• '»

DIPL.-ING. GERHARD PULS (19Ϊ2-Ι971)

EUROPEAN ^{PATENT TATTORNEYS 7I}

DIPL.-CHEM. DR. E. BARBER OF FCHMANN DR.-ING. DIETER BEHRENS

DIPL ₁ -INCDIPL-TIRTSCh ₁ -INCRUPERT GOETZ DIPL.-PHYS. DR. AXEL VON HELLFELD

POLIGRAT GKBH

1G-60 398 SCHWEIGERSTRASSE 2

phone: (089) 66 20 ji TELEGRAM: PROTECTPATENT TELEX: $ 24070 fax: (089) 663936 (in)

Device for electrochemical polishing of the inner surfaces of pipes

The invention relates to a device for electrochemical polishing and / or pickling of the inner surfaces of pipes with a flowing electrolyte which at least partially passes a cathode arranged inside the anodically connected tube.

From the European patent application 82 104 945.9 are a method and a device for so-called electropolishing of the inner walls of metallic pipes is known, in which the electrolyte is applied to a section of the wall of the pipe by means of high pressure of approx. 50 bar. The cathode is using dej high pressure jet moves in the tube, so that successively different Sections of the inner tube wall can be polished.

From the European patent application 82 104 946.7 are also a method and a device for electrochemical Polishing of the inner walls of tubes is known in which an electrode acting as a cathode can be moved through the tube. Of the Electrolyte is in the entire '^ u electropolishing pipe section filled.

From DE-GM 80 11 918 a device for electropolishing is the inner walls of pipes known in which a pipe lance is inserted into the pipe; those between their tip and a congestion ring has a cathodic area, wherein the

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Pipe lance with bores for the electrolyte liquid to pass through it is provided

The prior art indicated above by way of example for The electrochemical polishing of the inner walls of pipes can be roughly divided into two classes:

1) A continuous cathode is inserted into the tube to be polished on the inside and the electrolyte v. ^T is pumped through the anodically connected pipe. During electropolishing, the pipe lies either horizontally or at a slight angle and is rotated around its longitudinal axis. It is also possible to place the pipe vertically.

2) There will only be a partial one on each specific section the cathode acting on the inner wall of the tube (which is therefore much shorter than the tube to be electropolished) moved through the pipe. The electrolyte is pumped through the pipe.

The known devices for electrochemical polishing and / or pickling of pipe inner surfaces have the disadvantage that for Complete filling, purging and cooling of the pipe requires a very high electrolyte consumption. Also have to the gases (hydrogen and oxygen), which also causes a very high electrolyte throughput through the pipe.

In the known devices, too, only electrolytes can be used, the metal content of which has considerable restrictions is subject. An increased metal content in the electrolyte in the known devices namely leads to Passivation of the cathode surfaces by covering them with cathodically deposited metal sludge, which is a considerable reduction the polishing quality. In order to keep the metal content of the electrolytes low, it is therefore necessary to circulate the electrolyte in significant quantities.

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It should also be taken into account that the elimination of the electrolyte enriched with metals to avoid environmental pollution very costly. In the prior art, for the electropolishing of the inner surfaces of pipes made of aesthetic Chromium-nickel steels used mixtures of phosphoric acid, sulfuric acid and water. These acids are already as such represents a significant environmental pollution and a hazard potential that requires special safety measures iüäChfc.

The invention is based on the object of providing a device for electrochemical polishing and / or pickling of the inner surfaces of To create tubes that both reduce the amount of electrolyte used and improve polishing and pickling quality. The invention is also intended to achieve that compared to conventional methods a much wider variety of electrolyte compositions can be used.

The device according to the invention for solving this problem is characterized by a polishing head that passes through the tube is movable and has supply lines for the electrolyte and for electrical current, one arranged in the interior of the polishing head Cathode and a dielectric which at least partially forms the outer wall of the polishing head and which the electrolyte flow and between itself and the inner surface of the pipe to be polished or pickled, a working gap for the electrolyte flow releases.

According to the invention, a polishing head is moved through the tube. It is essential that between a wall of the polishing head formed from a dielectric and the inner surface of the tube a so-called working gap is formed into which the electrolyte is pressed through the dielectric.

Due to the formation of a working gap between the dielectric and the inner surface of the tube, which is provided according to the invention

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is the electrolyte consumption compared to the state of the art considerably reduced.

It has also been shown that by combining electrochemical polishing with the wiping effect of the dielectric, the effectiveness of the electropolishing process can be considerably improved in a manner that cannot be achieved by conventional methods. Very different electrolytes can also be used with success _; which, compared to the state of the art, represent a significantly lower environmental impact * Electrolytes can be used that can be regenerated via ion exchangers or electrolytic deposition cells. It is possible to keep the metal content of the electrolyte so low that the cathode surfaces cannot be passivated by deposited metal sludge.

In a preferred variant of the invention it is provided that the stream of electrolyte flowing into the polishing head in a anodic substream and a cathodic substream is divided, the anodic substream the dielectric and the inner surface of the tube, but not the cathode, while the cathodic partial flow passes through the cathode, but not the inner surface of the tube happened.

Such a separation of the electrolyte flow into anodic and cathodic substreams is from the unpublished European patent application 86 105 747 of the applicant at partial electrochemical polishing of free surfaces known. All of the advantages mentioned there also apply to that Internal polishing of pipes.

Further advantages of the invention emerge from the subclaims .

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Exemplary embodiments of the invention are explained in more detail below with reference to the drawing. It shows:

Fig. I is a section through the part of a tube, the inner surface is to be polished, as well as a polishing head movable in the tube and

Fig. 2 shows a section according to FIG. 1 with a polishing head in which the Elektrclytstrom in an anociisohen and a cathodic substream is separated.

A pipe 10 made of steel, for example chromium-nickel steel, is to be cleaned and polished on the inside. The polishing head is used for this (12) slowly moved through the pipe 10. The polishing head 12 is sometimes also referred to as a "tampon". By means of a Guide 14, which is designed as a tube with a significantly smaller diameter than the tube 10 to be cleaned, becomes the polishing head 12 moved through the tube 10.

As can be seen from FIGS. 1 and 2, the polishing head 12 is approximately cylindrical and lies concentrically in the pipe to be cleaned 10.

The jacket of the cylindrical polishing head 12 is through a Dielectric 18 is formed which is uniformly spaced from the inner surface 16 of the tube 10 throughout.

The polishing head 12 can be moved through the tube 10 in the direction of the arrow 20, that is to say in both directions.

The electrolyte stream 22 occurs in FIGS. 1 and 2 through the guide 14 from the right into the polishing head 12 and, in the exemplary embodiment according to FIG the arrows pressed radially outwards.

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The guide 14 takes in both embodiments according to the 1 and 2 each show the electrical supply lines 25 for the cathodes 26.

Between the cylinder jacket-shaped dielectric outer walls between the polishing head 12 and the inner surface 16 of the tube 10, a uniform, narrow working gap 28 is formed. The electrolyte flow 22 ″ passes the working gap 28 and effects the electrochemical removal on the inner surface 16 in a known manner and polish.

In the exemplary embodiment shown in FIG. 2, the electrolyte stream 22 entering the polishing head 12 is converted into a cathodic stream and an anodic substream 30 and 32, respectively. The cathodic substream 30 only passes through the cathodes 26, not but the dielectric 18 and the working gap 28. Thus, the hydrogen gas formed at the cathodes 26 does not reach the dielectric 18 and also not to the inner surface 16 to be polished, which on the one hand prevents the dielectric 18 from being with Hydrogen gas is loaded and, on the other hand, harmful effects of the hydrogen on the inner surface 16 are avoided are.

According to FIG. 2, the anodic substream 32 passes the dielectric Wall 18 and the working gap 28, so that the electrochemical polishing of the inner surface 16 can take place.

The cathodic substream 30 passes through an opening 34 in the Front wall of the polishing head 12 and, like the anodic partial flow 32, is collected and after regeneration possibly returned.

Textile Teflon fabrics are preferably used as the dielectric 18. Glass fiber fabrics and acid-resistant plastic fabrics and nonwovens can also be used.

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The dimensions of the polishing head 12 and particularly the dielectric 18 are adapted or selected for a given tube inside diameter so that a working gap with optimal Strength arises.

Claims (3)

Protection claims: 1. Device for electrochemical polishing and / or Pickling of the inner surfaces (16) of tubes (10) with a flowing electrolyte (22), at least partially of which is inside the anodically connected tube (10) passes through the cathode (26) arranged, marked by - A polishing head (12) which can be moved through the tube (10) and 7ülinien (14; 25) for the electrolyte and for electrical Has current, - A cathode (26) arranged in the interior of the polishing head (12) and - A dielectric (18) which at least partially forms the outer wall of the polishing head (12), which allows electrolyte to pass through and, between itself and the inner tube surface (16) to be polished or pickled, a working gap (28) for the flow of electrolyte (22 ¹ , 32) ) releases. 2. Device according to claim 1,
characterized, that the polishing head (12) is at least approximately cylindrical, the dielectric (18) at least partially the jacket of the Cylinder forms. 3. Device according to one of claims 1 or 2, characterized in that that a guide (14) for the polishing head (12) is formed as a tube in which the electrical lines (25) for the polishing head run and through which the electrolyte is pumped to the polishing head. 2064