JPH03281799A - Method for polishing surface of metallic material - Google Patents

Abstract

PURPOSE:To efficiently remove oxide scale on a metallic material and to uniformly polish the surface of the material by holding paste contg. an electrolyte between the material as an electrode and a counter electrode fitted with a pad and supplying electricity between the electrodes while relatively moving the electrodes at a prescribed speed under a prescribed pressure. CONSTITUTION:Paste 13 contg. an electrolyte is interposed between a metallic material 14 to be surface-treated as an electrode and a counter electrode (rotating electrode) 12 fitted with a pad 11 for holding the paste 13 by impregnation. The pad 11 is pressed against the surface of the electrode 14 under >=100g/cm<2> pressure and the electrodes 12, 14 are relatively moved at >=55m/min peripheral speed of the pad 11. Electricity is supplied between the electrodes 12, 14 through the paste 13 and the surface of the material 14 is polished.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a method for efficiently removing oxide scale by electrolytically polishing the surface of a metal material, particularly the surface of a steel material such as stainless steel.

<Prior Art> Conventionally, there are methods such as mechanical processing, chemical processing, and electrochemical processing as polishing (descaling) processing performed on the surface of a metal material. However, these conventional processing methods have the following drawbacks.

For example, mechanical treatment has disadvantages such as environmental problems such as dust and noise generation.

As a chemical treatment, so-called pickling treatment is available, but the treatment requires a long time, and the use of an acid solution poses environmental problems, and it has the disadvantage that on-site treatment is difficult. In recent years, an in-situ pickling treatment method using a pickling base material has been carried out, but it has the disadvantage that it requires a long treatment time and is likely to cause uneven pickling.

On the other hand, electrochemical treatment can be carried out in a short time, but has the disadvantage that on-site treatment is difficult due to limitations in the solution and equipment.

Furthermore, in conventional electrochemical surface treatment methods, various surface treatments are performed by passing electricity between the object to be treated and a counter electrode in various electrolytes. There are limitations on the size of the object to be treated depending on the electrolytic solution tank held, and depending on the solution, the processing solution may contain harmful substances, so cleaning the object after treatment is costly. there were.

Therefore, the present applicant has overcome the drawbacks of these conventional electrochemical processing methods, and by making the electrolyte for polishing the surface of metal materials into a paste with an appropriate viscosity, it can be used anywhere without an electrolyte bath. has proposed an electrolytic treatment method for the surface of a metal material that can treat any part of a structure (see Japanese Patent Application Laid-open No. 4500/1983).

That is, a rotating electrode type electrolytic polishing apparatus as schematically shown in FIG. 1 is used for polishing (descaling) the surface of a material to be treated. In FIG. 1, the rotating electrode type electrolytic polishing apparatus uses a counter electrode 12, which is a circular copper plate rotating electrode equipped with a glass pad as an electrode pad 11, and an electrolyte paste 13.
The paste 13 is held on the treated material 14 coated with the paste 13 . The material to be treated 14 is connected to the power source 16 by the electric wire 15.
! It is connected to a pole, placed on an insulating support stand 17, and insulated from the floor surface.

The rotating electrode is composed of a counter electrode 12, an electrode rotating means (motor) 18, and a rotating shaft 19 connecting the counter electrode 12 and the electrode rotating means (motor) 18, and rotates the counter electrode 12.

Further, the counter electrode 12 is configured so that it is always connected to the cathode of the power source 16 via the electric wire 15 by the conductive brush 20 even when the rotating electrode moves over the material to be treated 14 .

At this time, the paste 13 containing an electrolyte and an abrasive is automatically supplied from the paste supply tank 23 between the counter electrode 12 and the material to be treated I40 through the paste supply vibrator 22,
The surface of the material to be treated 14 can be polished (descaled).

<Problems to be Solved by the Invention> By the way, the conventional electrolytic polishing method described above has a problem in that the polishing rate must be lowered in order to obtain a good polished surface.

An object of the present invention is to provide a method for polishing the surface of a metal material, which has a high polishing rate, excellent descaling ability, and has no uneven polishing.

Means for Solving the Problems> In order to achieve the above object, according to the present invention, the above-mentioned method is provided between the metal material to be surface-treated and the counter electrode equipped with a pad for impregnating and retaining a paste containing an electrolyte. While holding the paste and relatively moving the metal material and the counter electrode,
When applying current through the paste between the metal material and the counter electrode to polish the surface of the metal material, the pressing force of the pad against the surface of the metal material is set to 100 g/
cm2 or more, and the speed of the outer periphery of the pad is 55 m
Provided is a method for polishing the surface of a metal material, which is characterized by polishing the surface of a metal material while maintaining the polishing temperature at a polishing temperature of /min or more.

Preferably, the pad is coated with abrasive powder.

The present invention will be explained in more detail below.

The metal material used in the present invention may be any metal material that requires surface polishing, such as steel materials such as stainless steel, ordinary steel, and low alloy steel, copper, nickel, aluminum, titanium, chromium, etc. It broadly includes non-ferrous materials, their alloys, and metal materials coated with various metals.

Since the present invention does not require an electrolytic solution tank, the metal surface may be any metal surface located at any location or part of any structure as long as it requires electrolytic polishing.

The electrolyte used in the present invention may be any electrolyte contained in the electrolytic solution necessary for the electrolytic polishing treatment of the surface of the metal material described above as long as it can be made into a paste. and mixtures thereof may be used.

The paste used in the present invention includes the above-mentioned electrolyte alone or a paste made by adding water.
Furthermore, sodium polyacrylate or silicon dioxide,
The paste may be made by adding a paste-forming material such as sodium alginate, and may be produced by any method as long as it is electrically conductive.

If an abrasive is mixed into the paste, the pad will be severely worn, and the surface of the metal material will not be polished well. Any method may be used to hold the paste containing the electrolyte between the surface of the metal material that requires surface polishing and the counter electrode, but it may be applied to the surface of the metal material before roughening, or
Alternatively, it is preferable to automatically supply the metal material between the surface of the metal material and the counter electrode at the appropriate time, or to the center of rotation of the rotating electrode using a device previously proposed by the present applicant in Japanese Patent Application No. 159279/1983. .

In order to perform electrolytic polishing efficiently, the distance between the counter electrode and the metal surface to be treated must be several tens of mm or less, preferably t.
It is necessary to keep it below Om m and not to short circuit.

The pad used in the present invention may be made of a material that has chemical resistance and insulation properties, is capable of impregnating and retaining paste, and has mechanical strength that will not break even when rotated. For example, woven fabrics such as polyester fibers, glass fibers, alumina fibers, etc.
Examples include silk cloth, sponge, porous ceramic sintered body, scrubber, brush-like object, etc. Further, the pad is coated with abrasive grains such as Al, O, silicon carbide, etc. as an abrasive material.

The present invention electrolytically polishes the surface of a workpiece by rotating a counter electrode to move it relative to the metal material that is the workpiece.

Here, the method for relatively moving the metal material and the counter electrode may be any method as long as it can give a relative movement between elements such as metal materials, pads, counter electrodes, etc., but for example, a small movable counter electrode may be used. For example, a method using

When using the above-mentioned movable small-sized counter electrode, it is preferable to attach the above-mentioned pad to the counter electrode and apply rotational motion to the padded electrode or the pad.

The method of polishing the surface of a metal material according to the present invention is basically constructed as described above, but in general use, it may be carried out by manufacturing a dedicated device. For example, the rotating electrode type electrolytic polishing apparatus shown in FIG. 1 used in the examples can be used. Details of these devices will be described later.

In the present invention, electrolytic polishing is carried out by setting the pressing force of the pad against the surface of the material to be treated to be 100 g/cm 2 or more, and maintaining the speed of the outer peripheral portion of the pad to 55 m/min or more. A satisfactory polished surface can be obtained if the pressing force is 100 g/cm2 or more, but the best is 130 g/cr.
n' or more, and the upper limit is preferably 300 g/cm' or less in consideration of wear due to pad friction.

A good polishing surface can be obtained by setting the peripheral speed of the pad to 55 m/min or more, but for even better polishing, it is better to set it to 70 m/min or more.

However, if the speed is too high, it will be difficult to retain the paste (the paste will scatter due to centrifugal force).
It is better to keep it below Q m/min.

The basis for limiting the pressing force and rotational speed of the pad to the above range will be explained.

Using the apparatus shown in FIG. 1, the polishing ability was evaluated by varying the pressing force of the pad under the following conditions.

Material to be treated: Stainless clad steel paste supply tray 2. Oj2/win.

Pad outer circumferential speed: 83 m/ll1in Moving speed: 0.3 m/win Pad abrasive material
...Au2203 abrasive current density...35
0 mA/cm2 Evaluation method: The state of descaling was visually evaluated, and a rating of 4 or higher was considered to be a level that could be inspected for defects in the next step.

The results were as shown in Figure 2. That is, if the pressing force is less than 10037 cm2, descaling will not be sufficient, and if it exceeds 300 g/cm2, the evaluation will be 5 or more, but the pad will be worn to a large extent, causing clogging and decreasing paste holding ability.

In addition, using the apparatus shown in Figure 1, the amount of paste supplied was
, 2 A/ff1in, , pad pressing force 120
The polishing ability was evaluated under the same conditions as when the pad pressing force was changed, except that the pad rotation speed was changed and the pad outer peripheral speed was changed.

The results were as shown in Figure 3. That is, when the rotation speed is less than 55 m/win, descaling is not sufficient, and when it exceeds 150 m/win, pad wear increases and the paste holding ability decreases.

Among the above conditions, a decrease in the generated voltage was observed especially when the pressing force of the pad was increased. This is considered to be the effect of shortening the distance between the electrodes (distance 11 between the electrode and the surface of the metal material) due to the increase in pressing force.

<Example> The present invention will be specifically described below based on Examples.

In order to confirm the effectiveness of the present invention, 5US304 stainless steel (6 m
Descaling treatment was performed using a steel plate with a black scale (300 x 300 mm thick).

(Example 1) The surface of the stainless steel plate was polished using the apparatus shown in FIG.

The electrode pad 11 has a thickness of 5 mm and is made of Au2 as an abrasive material.
0. A counter electrode 12, which is a rotating electrode made of a circular copper plate equipped with a pad made of glass 1AIA coated with abrasive grains of It was held on a certain 5 US 304 steel plate through paste 13. Material to be treated 14
is connected to the anode of a power source 16 by an electric wire 15, placed on an insulating support stand 17, and insulated from the floor.

The rotating electrode was composed of a counter electrode 12, an electrode rotating means (motor) 18, and a rotating shaft 19 connecting the counter electrode 12 and the electrode rotating means (motor) 18, and rotated the counter electrode 12.

A paste 13 containing an electrolyte is supplied by a paste supplying vibrator 2.
2, the paste was automatically supplied between the counter electrode 12 and the material to be treated 14 from the paste supply tank 23.

Using the above paste, polishing was performed under the conditions shown in Table 1 (Inventive Examples 1 to 5).

For comparison, the same metal material as in Example was treated in the same manner except that the conditions shown in Table 1 outside the scope of the present invention were applied (Comparative Example 1).
-3) and the results are shown in Table 1. Note that the "evaluation" in the table was based on the same criteria as in FIGS. 2 and 3 above.

From the results in Table 1, all of the examples of the present invention have low generated voltage;
It can be seen that a high polishing rate is required to achieve an excellent descaling state.

<Effects of the Invention> Since the present invention is configured as described above, according to the present invention, it is possible to polish the surface of a metal material with excellent descaling ability and with no polishing unevenness at a high polishing rate. can.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of a rotating electrode type electrolytic polishing apparatus used to carry out the method of polishing the surface of a metal material according to the present invention. FIG. 2 is a graph showing the relationship between pad pressing force and descaling state. FIG. 3 is a graph showing the relationship between the pad outer peripheral speed and the descaling state. Explanation of symbols 11... Electrode pad, 12... Counter electrode (rotating electrode) 13... Paste, 14... Processed material, 5... Electric wire, 6... Power source, 7... Insulation 8... Electrode rotating means (motor) 9... Rotating shaft, 0... Conductive brush, 1... Holding pad, 2... Paste supply pipe, 3... Paste supply tank FIG, 1 18 FIG, 3 FIG, 2

Claims (2)

[Claims] (1) The paste is held between the metal material to be surface-treated and a counter electrode equipped with a pad for impregnating and holding paste containing an electrolyte, and while the metal material and the counter electrode are relatively moved, When applying current through the paste between the metal material and the counter electrode to polish the surface of the metal material, the pressing force of the pad against the surface of the metal material is 100 g/cm^2 or more, and the outer circumference of the pad is A method for polishing the surface of a metal material, characterized in that polishing is carried out at a speed of 55 m/min or higher. (2) The method for polishing the surface of a metal material according to claim 1, wherein the pad is coated with abrasive powder.