JP2004211116A - Apparatus for anodic oxidation-treatment to aluminum or aluminum alloy - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an apparatus for anodic oxidation-treatment with which a uniform anodic oxidized film is formed, even to a treating material of aluminum alloy having any shape. <P>SOLUTION: This anodic oxidation-treatment apparatus 1 is composed of an electroconductive rotary shaft 3 parallel disposed with the vessel bottom part of an electrolytic vessel 20, an electroconductive holding tools 6 radially arranged for holding the treating materials 5 composed of the aluminum alloy at the outer periphery of the rotary shaft 3, a motor 10 and gears 9a-9c for rotating the rotary shaft 3 and electric supplying plates 8 for supplying the electric power to the rotary shaft 3 for energizing to the holding tools 6. When the rotary shaft 3 is rotated with the rotation driving mechanism 10, 9a-9c, since the treating materials held with the holding tools 6, are passed through between the vessel bottom part and solution surface part of the electrolytic vessel 20, the treating materials 5 disposed at any position are passed through between the vessel bottom part and the solution surface part in spite of existence of temperature differences in the electrolytic vessel 20, the treating materials 5 are treated under almost the same condition, and thus, the film thicknesses of the treating materials 5 can be uniformed. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an anodizing apparatus for performing anodizing on an object to be processed made of aluminum or an aluminum alloy using an electrolytic solution in an electrolytic cell.
[0002]
[Prior art]
Conventionally, when forming an anodized film on aluminum or aluminum alloy, the workpiece is attached to a current-carrying jig or holder, and the workpiece is fixed in an electrolytic cell and energized. Alternatively, if the distance from the cathode plate varies depending on the mounting position such as the left and right and the center, the current density becomes non-uniform, resulting in a large variation in the coating thickness. In order to solve such a defect, for example, as shown in Japanese Patent Application Laid-Open No. 50-72832, an object to be processed is mounted on a holder, and the holder is rotated to perform a uniform surface treatment. Has been proposed.
[0003]
[Patent Document 1]
Japanese Patent Laid-Open No. 50-72832 (FIGS. 1 and 3)
[0004]
[Problems to be solved by the invention]
However, the invention disclosed in Japanese Patent Application Laid-Open No. 50-72832 discloses a method in which a plurality of long workpieces are horizontally rotated at the same height position in an electrolytic cell, or a plurality of long workpieces are rotated. The electrolysis was performed by rotating the workpiece in the vertical direction in the electrolyzer, and the current efficiency changed due to the influence of the uneven temperature in the electrolyzer. There is a drawback that the variation occurs. Further, in the technology disclosed in the above-mentioned patent document, when performing an electrolytic treatment on a bottomed container-shaped object to be processed, if the attachment manner is not devised, the object to be processed is immersed in the electrolyte when the object is immersed in the electrolytic solution. There is also a possibility that the air bubbles taken in remain as they are, causing an air pocket phenomenon, and a defect that an anodic oxide film is not formed at that portion. The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an anodizing treatment in which a uniform anodized film is formed on an aluminum or aluminum alloy workpiece of any shape. It is to provide a device.
[0005]
[Means for Solving the Problems]
Specific means adopted by the present invention to achieve the above object will be described with reference to the drawings. FIG. 1 is a side view showing an outline of an anodizing apparatus 1 according to an embodiment of the present invention, FIG. 2 is a side view showing a rotation drive mechanism of the anodizing apparatus 1, and FIG. FIG. 2 is a cross-sectional view of a workpiece 5 to be anodized by the anodizing apparatus 1.
[0006]
In the drawing, the present invention relates to an anodizing apparatus 1 for performing anodizing on an object 5 made of aluminum or an aluminum alloy with an electrolytic solution 21 in an electrolytic tank 20. A conductive rotating shaft 3 arranged in parallel with the bottom of the tank 20; a conductive holder 6 radially provided for holding the workpiece 5 on the outer periphery of the rotating shaft 3; A motor 10 and gears 9a to 9c as a rotary drive mechanism for rotating the rotary shaft 3; a power feeding plate 8 and a power feeding hook 11 as a power feeding mechanism for feeding power to the rotating shaft 3 to energize the holder 6; When the rotation shaft 3 is rotated by the rotation driving mechanisms 10, 9a to 9c, the processing object 5 held by the holder 6 is moved to the bottom of the electrolytic bath 20 and the liquid surface. To pass between And it is characterized in and.
[0007]
With this configuration, the rotating shaft 3 rotates in the electrolytic cell 20 in parallel with the bottom of the cell, so that the workpiece 5 disposed at any position regardless of the temperature difference in the electrolytic cell 20 is also required. Since it passes between the bottom of the tank and the liquid surface of the electrolytic solution 21, the treatment is performed under substantially the same conditions. Therefore, it is possible to make the thickness of the workpiece 5 uniform for each lot. In addition, the cathode plate 22 provided in the electrolytic cell 20 by periodic rotation as described above (disposed on the left and right inner side surfaces of the electrolytic cell 20 in FIG. Since the distance between the electrodes and the workpiece 5 is leveled, the film thickness of the workpiece 5 for each lot can be made uniform. In addition, since the temperature rise caused by Joule heat at the aluminum interface is diffused by the stirring effect due to the periodic rotation, the local current of the portion not stirred under a high current density (for example, 3 A / dm ² or more) is generated. Burning and melting can be prevented, and the workpiece 5 on which a high-quality anodic oxide film is formed can be provided.
[0008]
Further, the workpiece 5 made of an aluminum alloy to be treated by the anodizing apparatus 1 according to the present invention is also effective for the workpiece 5 having a bottomed container shape as shown in FIG. Can be applied to This is because, in the processing target 5 having the shape of a bottomed container, when the processing target 5 is put into the electrolytic tank 20, a portion where air bubbles are taken into the bottomed container and do not come into contact with the electrolytic solution 21 is formed. However, in the anodic oxidation apparatus 1 according to the present invention, the processing target 5 in the form of a container with a bottom has a tank bottom and the liquid level of the electrolyte 21. This is because the air bubbles are periodically rotated so as to pass through the gap between the air pocket and the air pocket, so that the air bubbles can be diffused and the air pocket portion can be eliminated. Further, when the processing object 5 in the form of a container with a bottom is lifted from the electrolytic cell 20, the electrolytic solution 21 made of a harmful acid or the like is also taken out of the processing object 5 together with the electrolytic solution 21. May be released into the wastewater and adversely affect the environment. However, in the case of rotating the object 5 as in the present invention, the rotation of the rotating shaft 3 is continued in a state where the rotating shaft 3 is pulled up from the electrolytic tank 20. By doing so, the electrolytic solution 21 brought out by the processing object 5 can be shaken down to the electrolytic tank 20, so that the harmful electrolytic solution 21 can be minimized from being taken out of the electrolytic bath 20, and adversely affecting the environment. Can be suppressed.
[0009]
In addition, as a schematic structure of the anodizing apparatus 1 according to the present invention, as shown in FIG. 2 and a conductive rotating shaft 3 is rotatably supported at the lower part of the left and right vertical frames 2 via bearings 4. Although both ends of the rotating shaft 3 are formed in a small-diameter cylindrical shape because they are supported by the bearings 4, the cross-section is rectangular as shown in FIG. A plurality of conductive holders 6 are provided radially at equal intervals. The holder 6 has a structure in which the workpiece 5 having a bottomed container made of aluminum or an aluminum alloy according to the present embodiment can be easily mounted or removed. A large-diameter third gear 9c is fixed to the inside of the frame 2 at one end of the rotating shaft 3, and the second gear 9b is rotatably supported by the frame 2 so as to mesh with the third gear 9c. The first gear 9a is fixed to the drive shaft of the motor 10 so as to mesh with the second gear 9b. The motor 10 is mounted on the horizontal frame 2. The motor 10 and the gears 9a to 9c constitute a rotation drive mechanism, and the rotation of the motor 10 causes the rotation shaft 3 to rotate in the electrolyte 21 at a predetermined cycle. Further, a power supply plate 8 is attached to the outside of the vertical frame 2 via an insulating plate 7, and the lower end of the power supply plate 8 is connected to both ends of the rotating shaft 3. The gears 9a to 9c immersed in the electrolytic solution 21 are formed of polypropylene or vinyl chloride which has corrosion resistance and excellent mechanical strength. It is covered with a resin coating.
[0010]
In the anodizing apparatus 1 configured as described above, the step formed on the power supply plate 8 is placed on the L-shaped power supply hook 11 fixedly provided on the upper part of the electrolytic cell 20. As a result, the direct current supplied from the power supply line 12 connected to the power supply hook 11 is supplied to the power supply hook 11, the power supply plate 8, the rotating shaft 3, the holder 6, and the workpiece 5. An anodizing process is performed on the workpiece 5 by forming an anode and flowing a current between the anode plate and the cathode plate 22. Therefore, the power supply hook 11 and the power supply plate 8 constitute a power supply mechanism for supplying power to the rotating shaft 3 to supply electricity to the holder 6.
[0011]
Note that the configuration described above does not limit the structure of the anodizing apparatus 1 of the present invention. For example, the holders 6 provided on the rotating shaft 3 are provided on all sides at 90-degree intervals. , May be provided radially in six directions at intervals of 60 degrees and octagonally at intervals of 45 degrees, or by omitting the power supply mechanism by forming the gears 9a to 9c with a conductive material (for example, titanium or the like). Power may be supplied to the rotating shaft 3 via the gears 9a to 9c. Further, when rotating by the motor 10, it may be rotated at a constant cycle or may be rotated intermittently at a predetermined interval. In this case, the rotation control of the motor 10 is executed by control which is programmed by an separately provided control unit so as to obtain an optimum rotation speed according to the shape of the workpiece and the amount of current load.
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the oxidation in the case where the object 5 (the product, a piston of an automobile brake cylinder) shown in FIG. 3 is anodized under predetermined conditions using the anodizing apparatus 1 configured as described above. The results measured for the variation in the coating were as follows.
[0013]
Embodiment 1
In an electrolytic cell having a tank depth of 500 mm, a tank width of 400 mm and a tank length of 600 mm, the material of the object to be treated: A1050, current density: 2 A / dm ² , electrolysis time: 30 min, electrolyte temperature: 20 ° C., rotation speed: 10 sec The result of the film thickness measurement under the condition of / rotation was 19 μm ± 0.5 μm, and the variation range was within 2.7%. This is because the variation in the film thickness is greatly improved as compared with the variation range of 20% when the anodic oxidation treatment is performed by the conventional fixing method, and the current density can be increased as compared with the conventional method (conventional method). Is generally 1 A / dm ^{2 to} 1.5 A / dm ² ), so that the thickness of the film itself can be increased even when the conditions except the current density are almost the same.
[0014]
Embodiment 2
In an electrolytic cell having a tank depth of 500 mm, a tank width of 400 mm and a tank length of 600 mm, the material of the object to be treated: A1050, current density: 3 A / dm ² , electrolysis time: 30 min, electrolyte temperature: 5 ° C. (hard alumite), The result of the film thickness measurement under the condition that the number of rotations was 16 sec / rotation was 29 μm ± 0.8 μm, and the variation range was within 2.8%. As in the case of the first embodiment, as compared with the variation range in the case where the anodic oxidation treatment is performed by the conventional fixing method, the variation in the film thickness is greatly improved, and the thickness of the film itself can be increased.
[0015]
【The invention's effect】
As described above, as is clear from the above description, since the rotating shaft rotates in parallel with the bottom of the electrolytic cell, the object to be treated can be placed at any position regardless of the temperature difference in the electrolytic cell. Since it passes between the bottom and the liquid surface of the electrolytic solution, it is processed under almost the same conditions. Therefore, it is possible to make the film thickness of the object to be processed uniform for each lot. In addition, the distance between the cathode plate provided in the electrolytic cell and the object to be processed is leveled by the periodic rotational movement as described above, which also allows the film thickness of the object to be processed for each lot to be reduced. Uniformity can be achieved. In addition, since the temperature rise caused by Joule heat at the aluminum interface is diffused by the stirring effect due to the periodic rotational motion, "burning" and "melting" caused by the local current of the unstirred portion under high current density are prevented. Thus, an object to be processed on which a high quality anodic oxide film is formed can be provided. Further, the object to be processed by the anodizing apparatus according to the present invention can be effectively applied to an object to be processed having a bottomed container shape. In addition, by continuing the rotation of the rotating shaft while being lifted from the electrolytic cell, the electrolytic solution brought out by the object to be processed can be shaken down to the electrolytic cell, thereby minimizing the removal of harmful electrolytic solution to the outside. And adverse effects on the environment can be suppressed.
[Brief description of the drawings]
FIG. 1 is a side view showing an outline of an anodizing apparatus according to an embodiment of the present invention.
FIG. 2 is a side view showing a rotation drive mechanism of the anodizing apparatus.
FIG. 3 is a cross-sectional view of an object to be anodized by an anodizing apparatus.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Anodizing apparatus 2 Frame 3 Rotating shaft 4 Bearing 5 Workpiece 6 Holder 8 Power supply plate 9a First gear 9b Second gear 9c Third gear 10 Motor 11 Power supply hook 12 Power supply line 20 Electrolyte tank 21 Electrolyte solution 22 Cathode plate

Claims (2)

In an anodizing apparatus that performs an anodizing process on an object to be processed made of aluminum or an aluminum alloy with an electrolytic solution in an electrolytic cell,
The anodizing apparatus includes a conductive rotating shaft arranged in parallel with a bottom of the electrolytic cell, and a conductive holder radially provided to hold the workpiece on the outer periphery of the rotating shaft. And, a rotation drive mechanism for rotating the rotation shaft, and a power supply mechanism for supplying power to the rotation shaft to supply electricity to the holder,
When the rotation shaft is rotated by the rotation drive mechanism, the object to be processed held by the holder is passed between the tank bottom and the liquid surface of the electrolytic tank. Anodizing equipment for aluminum or aluminum alloy. The anodizing apparatus for aluminum or an aluminum alloy according to claim 1, wherein the object to be processed made of aluminum or an aluminum alloy is an object to be processed having a bottomed container shape.

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