JPS5848291B2 - Electrolytic buffing method - Google Patents

Description

[Detailed Description of the Invention] This invention combines the elution of anode metal by electrolytic action, the creation of a passivating oxide film, and the polishing action by a puff, thereby producing a mirror-like finish on the surface of stainless steel, etc. Relating to a puff polishing method.

Traditionally, the surface finishing methods for stainless steel, etc.
An electrolytic polishing method is used.

However, in general, the electrolytic polishing method is a so-called immersion method in which the object to be polished and the electrode are immersed in an electrolyte bath while facing each other. This is a method in which a current with a current density of 0.2 to 0.7 A/1 is passed through the electrolytic solution to finish the surface of the object to be polished into a mirror surface.

Therefore, although this immersion electropolishing method (CT) is an effective method for surface treatment of small parts with relatively small areas,
For example, when polishing the inner surface of a large-sized canned product that has a large area, the power supply equipment and electrolyte equipment are large-scale, and the current density is uneven, and the polishing speed is low because the current density is small. There are problems such as slow speed, making it difficult to put it into practical use from both technical and economical points of view.

This invention takes the above points into consideration and provides an electrolytic puff polishing method that can easily and economically finish even large and large-area objects to a mirror finish. This will be explained in detail along with drawings showing actual cases.

First, in Fig. 1, 1 is a disk-shaped tool electrode connected to the cathode side of a DC power source or pulsed power source, and 2 is a tool electrode 1.
It is an abrasive material attached to the lower surface of the tool electrode 1 with an adhesive 3, and is made of an electrical insulator, has water permeability, and has flexibility and elasticity, and is attached to the radially exposed electrode of the tool electrode 1. 1' and abrasive material 2 are formed alternately in the direction of rotation of the tool electrode 1, and the abrasive material 2 is provided on the abrasive surface of the tool electrode 1 so as to protrude from the exposed electrode surface of the electrode 1'.

Reference numeral 4 designates an electrolytic solution supply port transparently provided in the tool electrode 1, and the supply port 4 is located in the gap between the tool electrode 1 and the object to be polished (not shown), which is placed oppositely below the tool electrode 1. The electrolytic solution is supplied in the direction of the arrow shown in the figure.

5 is a rotating shaft of the tool electrode 1, and the anode side of a DC power source or a pulse power source is connected to the object to be polished.

Then, the electrolytic solution mixed with abrasive grains is supplied from the supply port 4 to the cap of the tool electrode 1 and the object to be polished, and the tool electrode 1 is rotated via the rotating shaft 5 by the drive machine, so that the tool electrode 1 DC power or pulse power is supplied between the exposed electrode 1 and the object to be polished, and the surface metal of the object to be polished is eluted by electrolytic action, and a passivation oxide film is formed on the uneven parts of the surface of the object to be polished. It is formed.

Of this passivated oxide film, only the convex portions of the passivated oxide film are removed by the abrasive material and the abrasive grains in the electrolyte, and the electrolytic action concentrates on the convex portions, giving priority to the convex portions. It is eluted and the surface of the object to be polished is finished to a mirror finish.

Next, experimental results of this invention will be explained.

The diameter of the tool electrode 1 is 150 l (area 177 ffl),
An exposed electrode 1' with an area of 40 ml and an abrasive material 2 with a thickness of 0.5 to 1 mN was used, and an electrolytic solution to which sodium nitrate was added at a weight ratio of 20% was added at a rate of 3 to 5 l/mitt. ,
Tool electrode 1 and polished object made of stainless steel (SUS27)
The experimental results are shown in FIGS. 2 to 4.

Figure 2 shows that the pressing force of the tool electrode against the object to be polished is 0.2 kg.
2 shows the change in electrolytic current when the rotational peripheral speed of the tool electrode is changed from O to 680 m/mvt under a constant condition of /i.

As is clear from the figure, when the rotation peripheral speed of the tool electrode is low, a sufficient electrolytic current cannot be obtained because the passivating oxide film formed on the surface of the object to be polished cannot be removed.

Furthermore, when the peripheral speed of rotation of the tool electrode is high, air bubbles are mixed into the electrolytic solution, resulting in a decrease in the substantial conductivity of the electrolytic solution and a decrease in electrolytic current.

That is, the optimal rotational peripheral speed of the tool electrode is 50 to 450
m/w.

In addition, the electrolytic current at the optimum rotation speed of 8 is 28 to 76 A.
and the current density (electrolytic current/exposed electrode area) is 0.7
~1.9A/cI1l.

Next, Figure 3 shows that the rotational circumferential speed of the tool electrode is 180 m/m.
The graph shows the change in electrolytic current when the pressing force of the tool electrode against the object to be polished is changed from O to 0.7 kg/crIL under a constant vt condition.

As is clear from the figure, the pressing force is 0.05 kg/ff.
From l to 0.2 kg/cv*, the electrolytic current increases rapidly, and even if a pressing force of more than 0.2 kg/cv is applied, the electrolytic current only increases slightly and remains at a constant value of approximately 76 to 80 A. .

That is, the current density (electrolytic current/exposed electrode area) is 1.
It becomes a constant value of 9 to 2 A/1.

Furthermore, Figure 4 shows how the peripheral speed of rotation and pressing force of the tool electrode affect polishing.
Using a material that has been pre-finished to μRmax, the pressing force is 0.2k under certain conditions with a polishing time of 1 minute.
The surface roughness of the object to be polished is shown when g/i is constant and the circumferential rotational speed is varied, and when the circumferential rotational speed is constant at 1 80 m/mvt and the pressing force is varied.

As is clear from the figure, when the pressing force reaches 0.4 kgld, the mechanical grinding force by the abrasive grains in the electrolyte acts directly on the surface of the object to be polished, deteriorating the polished surface.

Therefore, the same rotational speed of the tool electrode is 50 to 450n.
/mvt, pressing force is 0. 0 5 ~ 0. 4 kg/
d, the current density on the exposed electrode surface is 0.7 to 1.9 A/cf
In the case of IL, it is clear that this is the optimum value for carrying out electrolytic puff polishing.

In addition, if the area ratio of the exposed electrode surface and the abrasive material changes, the voltage applied between the exposed electrode and the object to be polished should be adjusted appropriately so that the current density on the exposed electrode surface becomes the optimum value of 0.7 to 1.9 A/C11l. Further, as long as the electrolytic solution can form a passivation oxide film, the applied voltage may be changed depending on the concentration, supply amount, etc. so that the current density is as described above.

As described above, according to the electrolytic puff polishing method of the present invention,
The relative speed between the tool electrode and the object to be polished is set to 50 to 450.
m/rnvt, the pressing force of the tool electrode to the object to be polished is 0.
05~0. 4 kg/cyt. By setting the current density on the exposed electrode surface to 0.7 to 1.9/ffl, it is possible to effectively finish a polished object with a large area to a mirror surface, which was previously considered impossible. Because the polishing speed is high, the polishing speed is 0.2-0.4μRmax in one process, from 3-4μRmax rough finish of stainless steel.
The present invention provides a highly effective electrolytic puff polishing method.

[Brief explanation of the drawing]

FIG. 1 shows an embodiment of the tool electrode of the electrolytic puff polishing method of the present invention, in which FIG. 1A is a bottom view and FIG.
Line sectional view, Figure 2 is a relationship between the rotational peripheral speed of the tool electrode and electrolytic current, Figure 3 is a relationship between the tool electrode pressing force and electrolysis current, and Figure 4 is the rotational peripheral speed of the tool electrode and pressing force. 1...Tool electrode, 2...Abrasive material.

Claims (1)

[Claims] 1. An exposed electrode surface and an abrasive material having insulating properties and flexibility that protrude from the exposed electrode surface are provided on the polished surface of the tool electrode, and electrolysis is applied to the irregularities on the surface of the anodic object to be polished. Among the worn passivation oxide films, the passivation oxide films on the convex parts are removed by a mechanical method such as a puff, and the electrolytic action is concentrated on the convex parts on the surface of the object to be polished. In the electrolytic puff polishing method that preferentially elutes and smoothes, the relative speed between the tool electrode and the object to be polished is set to 50 m/mvi to 4
50 m/mvt, and the pressing force of the tool electrode against the object to be polished was 0.05 kg/CrIL or o. 4y,'= and the current density variation on the exposed electrode surface is 0.7 A/ffl to 1.9 A/cffl.