JPS609600B2 - Anodizing treatment method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of anodizing a molded article made of aluminum or an aluminum alloy.

In the anodizing treatment method for molded products made of aluminum or aluminum alloy, the object to be treated immersed in an electrolytic solution is used as an anode, and lead or carbon placed opposite the object to be treated is used as a cathode for electrolysis. However, if the current density is increased to shorten the electrolysis time, uneven coloring and burning will occur.

Therefore, various anodic oxidation treatment methods have been proposed in which the electrolysis is carried out while the electrolytic solution is being fed, thereby preventing color unevenness and burning phenomena even if the current density is increased.
Even when using this type of conventional anodic oxidation treatment method, the current density can only be increased to a maximum of about 1 I/d. It is difficult to say that this is an efficient anodizing treatment method because the electrolysis time is insufficiently shortened.
The present invention was completed with the aim of providing an efficient anodizing treatment method developed in view of the current situation.In the anodizing treatment method for molded products made of aluminum or aluminum alloy, the average diameter is It is characterized by electrolyzing at a high current density while generating countless microscopic bubbles of 0.01 to 4 ribs and shaking these floating microbubbles with vibrations at a frequency of 10 to 200 Hz. .

The present invention utilizes a molded article made of aluminum or aluminum alloy immersed in an electrolytic solution as an object to be treated, and conducts electrolysis using this as an anode and lead or carbon facing the object as a cathode. Although it is similar to the seed anodization treatment method, in the present invention, a ceramic material or an acid-resistant metal is used in which countless minute ventilation holes with an average diameter of about 0.0005 to 0.5 ribs are formed at the bottom of the electrolytic cell. A diffuser tube, a diffuser plate, or other aeration device made of porous material such as porous silk material or synthetic resin porous material is provided, and the air supplied under pressure from the aeration device is used to disperse an average amount of air into the electrolyte. Micro bubbles with a diameter of 0.001 to 4 ribs are generated, and an electromagnetic vibration generator, eccentric rotation vibrator, pneumatic vibrator, or any other vibrator is brought into contact with the workpiece fixing jig. Or, by immersing the diaphragm of a vibrator in the electrolyte, the object to be treated in the electrolyte or the electrolyte has a frequency of 1.
The feature is that vibrations of 0 to 200 Hz are applied to cause the minute bubbles generated in the electrolyte to float while oscillating, and by performing electrolysis in the electrolyte under these conditions, a maximum of 20 A/d can be generated. Even if the current density is increased to such a degree, color unevenness and burning phenomena do not occur, and processing time can be shortened.

That is, the above-mentioned minute bubbles generated and floating in the electrolytic solution are shaken by vibrations at a frequency of 10 to 200 hertz, and the floating path of these minute bubbles is disturbed, so that the minute bubbles are spread to every corner of the electrolyte. As the electrolyte is spread throughout the electrolyte, the temperature of the electrolyte becomes uniform and
As a result, even if a part of the object to be treated heats up due to electrolysis at a high current density, the electrolyte cools the high-temperature part and lowers it to a low temperature, preventing the occurrence of burns. It is possible to generate an anodic oxide film of a desired thickness by electrolysis. The reason why the average diameter of the micro bubbles generated in the electrolytic solution is set at 0.001 to 4 is because normally, when the average diameter near the object to be treated exceeds 4, the buoyancy acting on the bubbles becomes large, and the electrolytic solution The electrolyte rises directly above the object in a straight line and rarely passes near the surface of the object to be processed, so the electrolyte near the object is weak and has little effect on uniformizing the temperature of the electrolyte and cooling it. . Therefore, the upper limit of the bubble diameter is set so that the average diameter near the object to be processed is about 4, so that the buoyant force acting on the bubbles is small and the bubbles float while vibrating due to the vibrations at the above-mentioned frequency and fly close to the object to be processed. "The lower limit of the bubble diameter is the finer the better, but 0.00
This is because bubbles smaller than 1 willow are difficult to generate, and therefore bubbles with an average diameter of 0.001 or more in the vicinity of the object to be treated are considered to be common. On the other hand, the reason for limiting the frequency to 10 to 200 Hz is that when electrolysis is performed while generating bubbles with an average diameter of 4 skin in the electrolytic solution near the object to be treated, if the frequency is less than 10 Hz, the bubbles will not be included. By only gently shaking the electrolyte, the vibration will not be sufficient to disrupt the upward path of the bubbles, so the effect is to make the bubbles flow throughout the electrolyte and make the liquid temperature uniform. If this does not occur and the frequency exceeds 200 Hz, the vibrational energy is absorbed and converted into heat, but the bubbles are not moved, so the vibration is sufficient to disturb the upward path of the bubbles. This is because, as in the case where the vibration frequency is 10 hertz or less, the same machine locally becomes hot and burns, and it is not possible to shorten the processing time by increasing the current density. It has been experimentally confirmed that there is a correlation between the average diameter and the frequency of vibration, and when the equal temperament is small, the maximum effect is at the place where the frequency is high, and when the equal temperament is large, the maximum effect is at the place where the frequency is low. In other words, as shown in Figure 2 as a straight line X-X, a vibration frequency of 80
The maximum film formation rate was obtained near Hertz, and at a frequency of about 40 Hertz on the average bubble diameter side of 4. Example Sio. 25% or less, Feo. 40% or less, Cuo. 0
2% or less, Tio. 02% or less, Mno. A plate material made of an aluminum alloy containing 0.2% or less and having a length of 20 ratios, 5 sides in the middle, and 2 ribs in thickness is made of aluminum alloy with 5 sides and 15 sides from one end in the length direction.
As shown in Fig. 1, the object to be processed 1 bent at a right angle into a U-shape is connected to a power source 2 as an anode, and a lead plate is connected to the power source as a cathode 3 to face the object to be processed. An electromagnetic vibration generator 5 is attached to the fixing jig 4 for the workpiece 1.
An aeration device 7 is installed at the bottom of the electrolytic cell 6 to fix the bubbles and generate minute bubbles. Anodizing was performed by changing the vibration frequency.

In the graph of FIG. 2, curves A, B, and C each have an average diameter of 0.001 "0.001" in the vicinity of the object to be treated in the electrolytic solution.
This shows the relationship between the generation rate of the anodic oxide film and the vibration frequency when electrolyzing at a current density of 20 A/d while generating various vibrations while generating 01 and 4 willow minute bubbles,
The dotted line area is the area where the burn occurred.

For comparison, the anodic oxide film produced when microbubbles with an average diameter of 0.01 pores are generated near the object to be treated in the electrolytic solution and electrolyzed at a current density of 1 pine/d is 4.5 pores/min. Also, the film formation rate when electrolyzed at a current density of 1 ship/d while applying ultrasonic vibrations of a frequency of 20 kilohertz to the object to be treated without generating minute bubbles is 4.2. Buddha skin/minute. However, as shown in the graph, for example, if the average diameter of minute bubbles near the workpiece is set to 0.001, and the minute bubbles are vibrated with vibrations at a frequency of 120 Hz, the surface of the workpiece is When electrolyzing at a current density of 20 A/d, the average rate of film formation during the initial 5 minutes was 8.8 m/min, which clearly shows how the method of the present invention can shorten the processing time. It is. As is clear from the above description, the present invention has an average diameter of 0.001 to
This method generates microscopic bubbles and shakes the microbubbles floating in the electrolyte with vibrations at a frequency of 10 to 200 Hz to disturb the floating path of the microbubbles while electrolyzing. As a result, the temperature of the electrolyte becomes uniform throughout due to the hawk effect caused by minute bubbles, and as a result, even if a part of the object to be treated generates heat due to electrolysis at a high current density, the electrolyte does not cover the high-temperature part. Since it is cooled to a low temperature and prevents burns, it is possible to electrolyze at a high current density, reducing the time required to generate an anodic oxide film of the desired thickness to approximately 1/2. As a possible anodizing treatment method, it will greatly contribute to the development of industry.

[Brief explanation of the drawing]

FIG. 1 is a diagram illustrating the implementation of the method of the present invention, and FIG. 2 is a graph showing the relationship between the rate of anodic oxide film formation and the frequency in the method of the present invention. 1: Processed object, 2: Power supply, 3: Cathode, 4: Fixing jig,
5: Vibration generator, 6: Electrolytic cell, 71: Diffuser, 8: Electrolyte. Figure 1 Figure 2

Claims (1)

[Claims] 1. In an anodizing treatment method for molded products made of aluminum or aluminum alloy, an average diameter of 0.05 mm is added to the electrolytic solution.
An anodizing process characterized by generating countless minute bubbles of 0.001 to 4 mm and electrolyzing them at a high current density while shaking the floating minute bubbles with vibrations at a frequency of 10 to 200 hertz.