JPH01225800A - Method for removing oxide film in metallic material - Google Patents

Abstract

PURPOSE:To rapidly remove an oxide film from the surface of a metallic material by rubbing the surface of the oxide film of a metallic member with a liq. absorptive member impregnated with an acidic processing soln. while carrying out electrolysis with a locally high current density. CONSTITUTION:A cylindrical body 4 (e.g., a pipe 10) having an oxide film 12 is horizontally fixed to a rotating mechanism 6, and the liq. absorptive member such as a felt material 16 is supported by a concentric receiving plate 14 set under the cylindrical body 4. When the device 2 is operated, a high current density is locally generated below the right end of the receiving plate 14 and the upper surface at the right end of the felt material 16. Meanwhile, when a dil. acid processing soln. is injected 24, the soln. flows over the pipe surface and is absorbed by the felt material 16. When the pipe 10 is rotated, the film 12 on the pipe surface is rubbed by the felt material 16, and the film 12 is successively separated and removed along the circumference. In this case, the spent dil. acid processing soln. is sent to a tank 22 by a pump 20 from the receiving plate 14, and circulated. Consequently, only a small amt. of the fresh soln. is replenished, and waste liq. is hardly generated.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a method for rapidly removing a relatively thick oxide film formed when a metal material is heat treated in air.

(Prior Art) When metal materials such as stainless steel materials are welded in air, a band-shaped oxide film is formed along the weld line, and sulfuric acid or hydrochloric acid is mainly used for descaling. When immersing metal materials in sulfuric acid or hydrochloric acid solution, approximately 20
%, and descaling is 1.5 to 2.0 times faster with hydrochloric acid than with sulfuric acid at the same concentration and temperature, but both generate mist, so an exhaust cleaning device must be installed. There is a need. This improved method includes a jelly containing a hydrochloric acid solution, which is applied onto the oxide film of the metal material and washed off with water after about 30 minutes.

There is also a method of applying paint containing silver powder along a band-shaped oxide film to conceal and shield the oxide film. As a method using an acid, there is also a method of performing cathodic electrolysis, anodic electrolysis, and PR electrolysis in a 5 to 20% solution of sulfuric acid.

(Problem to be Solved by the Invention) When a jelly-like material containing a hydrochloric acid solution is used, a pollution problem occurs in the treatment of wastewater because the water used for washing has an odor and corrodes the pond materials. Although the removal effect of this jelly-like material increases if it is heated, there remains the problem that it is necessary to leave it on the oxide film for a long time, resulting in poor working efficiency. Furthermore, applying paint containing silver powder is expensive, and the paint tends to peel off during use. Although the electrolytic method can quickly remove even strong oxide films, it requires electrolytic equipment and is expensive, and the oxide film on concave areas dissolves more slowly than on convex areas.
Moreover, the problem of wastewater treatment still remains.

The present invention was proposed in order to improve the above-mentioned problems related to the technology for removing oxide films from metal materials, and it can quickly and easily remove even strong oxide films using an inexpensive electrolytic method. The object of the present invention is to provide a method for removing an oxide film using a device that hardly causes problems in waste liquid treatment.

(Means for Solving the Problems) In order to achieve the above object, in the method for removing an oxide film according to the present invention, a liquid absorbing member is attached to one electrode body,
In addition, the other electrode body is brought into contact with a metal material. This liquid-absorbing material is preferably a cotton pad wrapped in cloth, felt, sponge, etc., which can sufficiently absorb and retain the acid treatment solution and has wear resistance.On the other hand, both electrode bodies are made of sintered material. Preferably, it is an insoluble electrode material such as carbon. In order to apply a predetermined potential between both electrode bodies using an external power source, a liquid absorbing member is attached to the anode or cathode electrode body, and the opposite electrode body is brought into contact with the surface of the metal material.
Electrolysis by the R method is also possible.

Both electrode bodies are brought close to each other on a metal material to locally generate a high current density, and the voltage is kept low so as not to generate a large amount of gas such as SO2 at the anode electrode S. The liquid-absorbing member is impregnated with an acid treatment liquid whose main component is sulfuric acid or hydrochloric acid, and is usually impregnated with a dilute acid treatment liquid that can be easily post-treated and brought into contact with the oxide film. An inhibitor or the like may be added to the treatment solution. Next, the liquid-absorbing member or the metal material is moved relatively along the oxide film, and this movement can be done manually (see Figure 3) or by an appropriate drive device (see Figure 1 or 5).
(see figure). Metal materials that can be processed include various types of steel such as stainless steel, and aluminum.

These include zinc and its alloys. In the case of stainless steel materials, after the oxide film on the surface produced by welding or the like is separated by friction with a water-absorbing member, the activated separated part is sometimes plated with nickel.

(Function) In the method of the present invention, the oxide film is removed from the surface of the metal material by rubbing the surface of the oxide film on the metal material with a liquid-absorbing member impregnated with an acid treatment liquid while locally electrolyzing at a high current density. quickly separate and remove. Regarding the metal materials to be treated, cathode electrolysis causes less corrosion of metal materials, maintains dimensional accuracy, and is good for plating adhesion because it is activated. Not suitable for steel and spring steel.

On the other hand, in anodic electrolysis, the oxide film is physically removed using oxygen gas, making the surface of the metal material immobile, preventing corrosion, and mitigating the occurrence of hydrogen embrittlement. and its alloys.

(Example) Next, an example of the method of the present invention will be described with reference to the drawings.

Embodiment 1 In the cleaning apparatus 2 shown in FIG. 1, the cylindrical body 4 having the oxide film to be removed is horizontally attached to the chuck 8 of the rotating mechanism 6, and the rotating mechanism may be a headstock of a lathe or the like. . The cylindrical body 4 is, for example, a welded pipe 10 shown in FIG.
A ring-shaped oxide film 12 is formed on the pipe surface along the weld line. Below the cylindrical body 4, that is, the vibrator 10, a receiving plate 14 with an arcuate side surface concentric with the vibrator is installed,
A liquid-absorbing member such as a strip-shaped felt material 16 is supported by the receiving plate. The receiving plate 14 has an inverted U-shaped cross section, and by placing a strip of felt material 16 along its inner surface, the felt material also deforms into an arcuate side surface and comes into contact with the surface of the pipe 10. A liquid sending pipe 18 is communicated with the lower end of the receiving plate 14,
It extends to the head tank 22 via the circulation pump 20. The tank 22 sends the dilute acid treatment liquid to the nozzle 24 via the liquid sending pipe 23. By wiring an appropriate external DC power supply 26 to the tip of the nozzle 24 and the right end of the receiving plate 14, the right end of the receiving plate contacts one electrode body and the surface of the pipe 10 contacts the other electrode. corresponds to the body. In FIG. 1, the nozzle tip is an anode electrode body, but this tip may be a cathode electrode body, or a PR lightning current may be used.

When this device 2 is operated, a localized high current density is generated at the right end of the felt material 14 between the right end of the receiving plate and the pipe surface. On the other hand, when the dilute acid treatment liquid is injected from the nozzle 24, this treatment liquid flows on the pipe surface and is absorbed by the felt material 16, so that the felt material is constantly impregnated with the dilute acid treatment liquid. Since the felt material 16 is in contact with the surface of the pipe 10, when the pipe is rotated by the chuck 8, the felt material 16 rubs the oxide film 12 on the pipe surface, and the oxide film 12 is sequentially removed along the circumference. Separate. The used dilute acid treatment liquid is transferred to the receiving plate 1 by the pump 20.
4 to the tank 22 for circulation and replenishing a small amount of new liquid, almost no waste liquid is generated.

In this cleaning device, it is also possible to use a roller wrapped with felt material (see FIG. 5) instead of the receiving plate 14. Further, instead of the liquid circulation circuit, only the necessary amount of dilute acid treatment liquid may be forcibly sent to the right end of the receiving plate 14.

Example 2 In the cleaning equipment 30 shown in FIG.
2 is elongated and its upper part 34 is bent horizontally. A liquid-absorbing member, which is a pad 36, is attached to the tip of one rod-shaped electrode body 38, and the other rod-shaped electrode body 40 is placed above the rod-shaped electrode body in close proximity to the electrode body, and both electrode bodies are attached to the tip surface of the upper part 34 of the device. Install it horizontally. The tip of the electrode body 40 is usually pointed, and is positioned slightly forward of the front surface of the button 36.
is biased forward by a spring 42 within the device body 32.

Both electrode bodies 38, 40 are wired via a manually operated switch 44 to an external power source (not shown), which is, for example, a constant voltage DC power source connected to an AC power source.

This device 3o is used by holding the device main body 32 by hand, and when immersing the button 36 in the dilute acid treatment liquid, use the operation switch 4.
Do not apply current by separating the As illustrated in FIG. 4, when the tampon 36 is impregnated with a dilute acid treatment liquid and then the tampon 36 and the electrode body 40 are applied to the oxide film 46 of the metal material and energized, the electrode body 38 at the tampon 36 A localized high current density is generated between the tip of the metal material and the surface of the metal material. When the device 30 is moved along the arbitrarily shaped oxide film 46 while the pad 36 and the electrode body 40 are in contact with the surface of the metal material, the oxide film 46 is rubbed by the pad and separated one by one. Since the tank 36 is simply immersed in the dilute acid treatment liquid each time, only a small amount of the consumed dilute acid treatment liquid is needed, and full-scale treatment equipment is not required. No waste liquid is generated.

In the cleaning device 30 shown in FIG. 3, the tampon 36 is immersed in a dilute acid treatment solution, but a tank containing the dilute acid treatment solution is attached to the device 30, and the tank 36 is directly poured from the tank. You may also send it. Furthermore, instead of a stationary external power source, a dry battery or charger of a predetermined voltage may be housed in the main body of the device, or a small power source may be attached to the user's waist belt. These modifications make the cleaning equipment even more portable and allow for easier removal of oxide films created by welding in inconvenient locations.

Embodiment 3 In a cleaning device 50 shown in FIG. 5, a metal plate 52 having a linear oxide film 51 to be removed is moved horizontally by rollers 54 and 56 with the film positioned on the lower side. A cleaning roller 58 is disposed between the rollers 54 and 56, and a felt material 60, which is a liquid-absorbing member, is wrapped around the circumference of the cleaning roller 58.

The annular felt material 60 has its upper end in contact with the lower side of the metal plate 52 and its lower end is immersed in the liquid bath 62 .

A dilute acid treatment solution is placed in the liquid bath 62, and the solution is replenished by a pump 66 via a pipe 64. The picture electrode body 68,70 is a rotor wired with an appropriate external power source 72, and the plate 52
The plate rotates while abutting the upper side of the plate and the inner circumferential wall of the roller 58 at the contact point between the felt material 60 and the felt material 60 .

When the device 50 is operated, a localized high current density is generated at the contact point between the plate 52 and the felt material 60. On the other hand, the dilute acid treatment liquid in the liquid bath 62 is applied to the felt material 60.
It is absorbed at the lower end of the felt material and reaches its upper end by rotation of the felt material. The rotation speed of the cleaning roller 60 is the same as that of the roller 5.
Due to the rotation of the plates 5 and 56, which is different from the traveling speed of the plates 5 and 2, the felt material 60 rubs the oxide film 51 on the lower side of the plate, and as the plate 52 travels, the oxide film 51 is linearly separated one by one. To go. In the dilute acid treatment 7α, only the amount that adheres to the plate 52 needs to be replenished by the pump 66, and since only a small amount of new liquid is replenished, almost no waste liquid is generated.

In this cleaning device, the dilute acid treatment liquid is sent to the inner center of the roller 58, and from there it is radially distributed around the felt material 6 at the circumferential portion.
It may also be leached. Moreover, if the plate 52 is manually pressed onto the felt material 60 without using the rollers 54 and 56, it is possible to partially remove the oxide film.

(Effects of the Invention) In the method of the present invention, the oxide film can be quickly and easily removed from the metal material by locally electrolyzing at a high current density and then rubbing the oxide film surface of the metal material with a liquid-absorbing member. The work efficiency is superior to that of conventional methods, and there is almost no deterioration of the work environment. The method of the present invention has simpler electrolytic equipment and lower equipment cost than normal electrolysis methods, and because the liquid-absorbing member performs friction, the oxide film on the recesses does not dissolve more slowly than on the protrusions. rarely occurs.

In addition, since the method of the present invention generally uses only a small amount of dilute acid treatment solution, less waste fluid is produced than in the electrolytic method that uses an electrolytic bath. It does not corrode and there is little risk of pollution problems related to wastewater treatment.

[Brief explanation of the drawing]

Fig. 1 is an overall explanatory diagram schematically showing an apparatus for carrying out the method of the present invention, Fig. 2 is a perspective view showing an example of a welded pipe having an annular oxide film, and Fig. 3 is a diagram illustrating the method of the present invention. FIG. 4 is a side view of a main part showing the usage state of FIG. 3, and FIG. 5 is a side view of still another device for implementing the method of the present invention. 2...Cleaning device, 4...Cylindrical body, 6...Rotating mechanism, 8...Chuck, 10...Welded pipe, 12...
- Oxide film, 14... Reception plate, 16... Felt material, 20... Circulation pump, 22... Head tank,
24... Nozzle, 26... External DC power supply. Patent applicant Gilphy Co., Ltd.

Claims (1)

[Claims] 1. In order to remove a relatively thick oxide film that occurs when a metal material is heat-treated in air, a liquid-absorbing member is attached to one electrode body, and the other electrode body is made of a metal material. and apply a predetermined potential between both electrode bodies using an external power source to generate a locally high current density, and impregnate the liquid-absorbing member with an acid treatment liquid and bring it into contact with the oxide film. Next, the liquid-absorbing member or metal material is moved relatively along the oxide film, and the liquid-absorbing member rubs the surface of the oxide film, thereby sequentially separating the oxide film of the metal material. How to remove oxide film. 2. The method according to claim 1, wherein the oxide film on the surface of the stainless steel material is separated by rubbing with a liquid-absorbing member impregnated with a dilute acid treatment solution, and then the activated separated part is plated with nickel.