JPS5819409B2 - Mirror finish processing method - Google Patents

Description

[Detailed description of the invention] The present invention relates to a mirror finishing method for metal surfaces.

Electrolytic polishing is generally used for mirror finishing of metal surfaces.

In this method, a workpiece is immersed in a suitable electrolytic solution, and this is used as an anode to electrolyze the workpiece at a relatively low current density, thereby melting the surface of the workpiece and giving it a mirror finish.

As the electrolyte, a strongly acidic solution such as hydrochloric acid or sulfuric acid is used.

Compared to mechanical polishing, this method is very superior in that it selectively dissolves microscopic convexities, resulting in an extremely smooth and glossy surface.

However, since relatively large irregularities (approximately 3 to 6 μRmax) remain as they are, this method has to be applied after finishing the base to a certain extent, resulting in double work.

Furthermore, it is impossible to partially polish the workpiece, and the electrolyte ages quickly and is not efficient.

This invention was made in view of the above-mentioned circumstances, and it is possible to efficiently achieve an extremely smooth mirror finish in a single polishing operation, even on relatively large irregularities on the surface of the workpiece, and it also enables partial polishing. This provides a processing method.

The mirror finish processing method according to the present invention uses a polishing tool in which electrodes and coated abrasive papers are arranged alternately and the coated abrasive paper protrudes more than the electrodes, and the polishing tool is placed opposite the workpiece. The abrasive cloth paper is placed in contact with the surface of the workpiece with the required pressure and the required gap is maintained between the electrode and the surface of the workpiece, and the workpiece is used as the anode and the electrode as the cathode. ,
In the above state, current is passed between the two electrodes through an electrolytic solution that generates a passive oxide film on the surface of the workpiece, and the workpiece and polishing tool are moved relative to each other, thereby polishing the workpiece. Anodic dissolution by electrolysis of the surface and removal of the passive oxide film formed on the surface of the workpiece by the abrasive cloth paper are alternately performed.

Here, the abrasive coated paper is a general term for abrasive cloth and abrasive paper, and includes those with abrasive grains fixed by an adhesive and those without abrasive grains.

Further, as the workpiece material, it can be applied to metals including pure metals and alloys thereof.

A more detailed explanation will be given below with reference to the drawings.

1 to 4 show polishing tools 1 and 11 used in the present invention.

In FIGS. 1 and 2, the polishing tool 1 includes a conductive disk 2 with a circular electrolyte outlet 6 in the center, and an electrically insulating material 5 with the lower surface left in the shape of a cross. The electrode 3 is a 3,000-character shaped portion made up of the fan-shaped abrasive cloth paper 4 attached thereto.

One end of the hollow rotating shaft 7 is inserted into the outflow hole 6 and fixed.

This polishing tool 11 is rotated around the rotating shaft 7.

The polishing tool 11 shown in FIGS. 3 and 4 is a conductive square plate 1.
2, and rectangular abrasive cloth paper 14 attached to the lower surface of this in the longitudinal direction at a required interval via an electrical insulating material 15.

The lower surface of the plate 12 between the abrasive cloth papers 14 and 14 becomes the electrode 13.

This polishing tool 11 is used by being reciprocated in its longitudinal direction.

It is also possible to use an endless belt as the plate 12 of the polishing tool 11 so as to move in one direction.

In this case, a flexible plate material is selected as the plate material.

In the above, the area of the polishing cloth paper surface is preferably larger than that of the electrode surface, and according to experiments, the area ratio of the polishing cloth paper surface to the electrode surface is most preferably about 4 to 1.

However, it is quite possible to set the above ratio to about 10=1, for example.

Further, although the insulating materials 5 and 15 are not necessarily required, it is desirable to attach the abrasive cloth paper through the insulating materials in order to prevent leakage current.

Furthermore, all of the above-mentioned polishing tools have coated abrasive paper attached to the bottom surface of a conductive plate, but separately prepared electrode pieces and coated abrasive paper are attached to one side of the support plate or flexible endless belt. You may also use one in which these are alternately fixed.

In this case, it is necessary to make the abrasive cloth protrude more than the electrode.

An insulating spacer may be interposed between the electrode piece and the abrasive cloth paper.

FIG. 5 shows a state in which the surface of a workpiece 20 is polished to a mirror finish using the polishing tool 1.

In this figure, the polishing tool 1 is rotated around the rotating shaft 7 while the electrode 3 and the surface of the workpiece 20 are separated for a required period and the abrasive cloth 4 is pressed against the surface of the workpiece 20 with an appropriate polishing pressure. while moving the surface of the workpiece 20 in any direction.

At the same time, an electrolytic solution that tends to form a passive oxide film on the surface of the workpiece 20 is poured through the rotating shaft 7 into the outflow hole 6 or into the gap between the electrode 3 and the surface of the workpiece 20.

The electrolytic solution preferably has a low throwing power.

If abrasive grains are not fixed to the abrasive cloth paper 4, the abrasive grains are mixed in the electrolytic solution and sent to the polishing area together with the electrolytic solution.

Further, a DC voltage is applied using the workpiece 20 as an anode and the polishing tool 1 side as a cathode.

Then, when looking at a certain point on the surface of the workpiece 20, a current flows when it faces the electrode 3, and at the next moment it comes into contact with the abrasive cloth 4, so no current flows, and eventually a pulse-like pulse appears at that point. Current flows.

Through this pulsed electrolysis, the surface of the workpiece 20 is anodic-dissolved, but a passive oxide film is immediately generated.

However, at the next instant, the coated abrasive paper 4 removes the film.

The most important thing here is that since the film on the convex portions of the uneven surface of the workpiece 20 is mainly peeled off and removed, anodic dissolution by electrolytic action is also predominantly performed on the convex portions.

Since the recessed portion is protected by the insulating oxide film, anodic dissolution is hardly performed.

This electrolytic anodic melting of the surface of the workpiece, especially the convex parts,
By alternately and repeatedly removing the passive oxide film formed on the surface convex portions with the coated abrasive paper 4, the surface of the workpiece 20 is finished into an extremely smooth surface with a specular gloss.

- I'l, to specifically describe the case where stainless steel is finished processed, in Fig. 5, the electrode 3 and the workpiece 2 are
The abrasive cloth paper 4 is pressed against the surface at a pressure of 0.1 to 0.7 kg/crj, and the abrasive tool 1 is moved at a circumferential speed of 2 to 5 m while maintaining the gap with the surface at 0.5 to 2.0 m. Rotate at a speed of /sec.

A 10-20% sodium nitrate aqueous solution is used as the electrolyte,
Add 5 to 10' of abrasive grains of grain size 600 to 1500 to this. /
l Mix.

Then, apply a DC voltage of 6 to 10 μ between both electrodes,
Current density 0.5-4. A current of OA/crrr is applied.

This current has a frequency of 20 to 40 at various locations on the workpiece surface.
A unidirectional pulsed current with a duty factor of 0108 to 0.2 is obtained.

As a result, 3 to 6μR, which cannot be polished with conventional electrolytic polishing,
A surface with a roughness of about max.
Finished with a high quality mirror finish of x or less.

Note that a sodium chlorate aqueous solution can also be used as the electrolyte.

In these cases, since an acid solution is not used as the electrolyte, there is little danger in handling and post-treatment is very simple.

According to the present invention, in addition to the method shown in FIG. 5, for example, both the polishing tool and the workpiece may be immersed in an electrolytic solution, and the two may be moved relative to each other in the electrolytic solution.

Also, instead of moving the abrasive tool, the workpiece can be moved.

Furthermore, the voltage applied between both electrodes may be a unidirectional pulse voltage in addition to a DC voltage.

As explained in detail above, according to the processing method according to the present invention, the anodic dissolution of the surface of the workpiece by electrolysis and the removal of the passive film formed on the surface of the workpiece using abrasive cloth are alternately performed. Because of this, they work very effectively on relatively large irregularities on the surface, and even surfaces with large irregularities that cannot be polished with conventional electrolytic polishing can be polished to an extremely smooth mirror-like luster with a single polishing operation. Can be finished on the surface.

Therefore, there is no need for rough finishing in advance, which is efficient.

Moreover, since the passive oxide film is forcibly removed, the current density is high and the polishing speed is high.

Especially since the abrasive paper is electrically insulated from the electrode,
When polishing with abrasive paper is being performed, no electric field polishing is performed, and the two polishing processes are clearly separated in time.

The areas of the abrasive cloth and electrode affect both abrasive action,
As mentioned above, in this invention, the area of the abrasive cloth paper is set larger than the area of the electrode so that a good finish can be achieved.

Moreover, since the abrasive cloth paper protrudes more than the electrode, the gap necessary for electric field polishing is secured.

Furthermore, by making the polishing tool an appropriate size and shape, it is possible to partially finish the surface of the workpiece, and the polishing tool can be applied to workpieces of various shapes.

[Brief explanation of drawings]

1 to 4 show an example of the polishing tool used in the present invention, FIGS. 1 and 3 are bottom views thereof, and FIGS. 2 and 4 are the ■-■ line and the IV-IV line, respectively.
FIG. 5 is a sectional view taken along the line and shows a state in which mirror finishing is being performed. 1.11...Abrasive tool, 3,13...Electrode, 4゜14...Abrasive cloth paper, 20...
Work material.

Claims (1)

[Claims] 1 Electrodes and coated abrasive paper electrically insulated from the electrodes are arranged alternately, the area of the coated abrasive paper is larger than the area of the electrode, and the coated abrasive paper is larger than the electrode. Using a polishing tool that protrudes by the gap required for electric field polishing, the polishing tool is placed facing the workpiece, and the workpiece is used as an anode and the electrode is a cathode to form a passive oxide film on the surface of the workpiece. Electricity is passed between the two electrodes through an electrolytic solution that produces 1. A mirror finishing method characterized by alternately performing removal of the passive oxide film by using the coated abrasive paper.