US3432407A - Method of anodizing aluminum wire - Google Patents

Description

A. J. RICCI METHOD OF ANODIZING ALUMINUM WIRE Mgrch 11,1969

Filed lay l, 1967 JNVENTOR ANTHNY .I /7/CC/ 7L @fr March 1l, 1969 A. J. Riccl METHOD 0F NGDIZING ALUMINUM WIRE Filed nay i. 19e? Z of 2 Sheet lll/4l United States Patent O 3 Claims ABSTRACT F THE DISCLOSURE There is described method and apparatus for providing improved anodized aluminum wire. Aluminum wire, as it is passed through an anodizing bath, is passed over and around a plurality of pulleys which are located in the bath. The pulleys are of various sizes and lie in planes which are at right angles or very substantial angles to each other. The anodic coated wire as it passes around and over the various pulleys is subjected to stresses which tend to crack or break the coating, thereby exposing the underlying metal to further action of the anodizing bath. An improved anodized coil is prepared by initially bending the anodized wire on different sized pulleys and then winding the wire into a coil having a diameter intermediate the size of the different sized pulleys.

This application is a c-ontinuationinpart of my prior filed copending application Ser. No. 264,649, filed Mar. 12, 1963, and now abandoned.

My invention relates to anodized aluminum wire products, and methods and apparatus for anodizing aluminum wire whereby it is ilexed or bent in idiferent planes and/ or on diiferent radii, and desirably also in opposite directions in each of said planes. Aluminum, as used herein, is inclusive of aluminum alloys.

For example, in various pieces of electrical equipment where the 'wire is to be wound about a core or otherwise coiled, the turns of the coil will come into electrical contact with one another unless the wire is insulated and I have found that by treating the wire according to my novel method, and preferably by means of my novel apparatus, the insulating quality of the anodized coating is much improved. The resultant Wire is itself a new product, as is also a coil of the new anodized wire, when wound to a radius which is between the radii of larger and smaller bends imposed lupon the wire during or in connection with the anodizing process.

The electrical equip-ment iield is but one example of a eld in which a Wire produced by my improved process is useful. It is also useful in other elds where the coating produced on wires by present methods is found to be unsatisfactory.

The primary object of my invention is to provide a greatly improved anodized aluminum wire, and coils made therefrom, and improved methods and apparatus for producing the same. In achieving this object and its advantages, together with such other objects and advantages as may occur to those skilled in the art, or as are incident to my invention, I provide a method and apparatus for repeatedly bending the wire in connection with the anodizing procedure so that the oxide film which is being formed is repeatedly broken or cracked, and for doing this in such a way that the wire is bent in a plurality of planes at ICC substantial angles to each other, and most desirably at right angles; and, alternatively, or even better additionally, that it is bent iir'st on one radius and then on another; and, for obtaining the full advantages of the invention, that it is bent in opposite directions in each plane; and, when the wire is to be formed into an electrical coil, that it is bent on radii greater and smaller than that of the coil. This procedure causes repeated breaking or cracking of the oxide film and exposes unoxidized areas in the region of the cracks. However, the bath will then again attack such exposed metal and reform the coating. I prefer to do this by repeatedly flexing or bending the wire as it passes through the bath although, after initial anodizing treatment, the bending -can take place outside the bath followed by prompt reentry into the bath and this procedure can be repeated as desired. In this way a coating will be built lup which will be heavier, stronger and more resistant to the effects of any future bending which may be involved in the use to which the wire may be put, especially such uses as require the wire to be repeatedly bent or coiled in service. Actually this procedure involves a deliberate breaking and refroming of the coating so that at all potentially weak spots the coating may be broken and reformed.

Although there may be dilferent theories as to what happens to the iilm, it is my theory that the repeated ftexing of the wire, consequent cracking of the iilm, and repeated reforming of the coating at the cracks, produces an article which is finally coated with exceedingly minute scale-like bits of oxide ilm, more or less overlapping. In any event, I have found by actual test that the resulting lm is such that the coating forms a very eiective insulation lupon the wire so that when one run of wire lies immediately adjacent to another, or when the wire is wound in a coil, the electrical insulation between the adjacent wires `or between the adjacent turns of a coil (either axially adjacent or radially adjacent) is very effective. The resultant product is far superior to previously known anodized wires, and is of great practical value as compared with anodized aluminum wire which has been bent over rollers or wheels of only one diameter, during the andoizing, or bent in only one general plane, during anodizing.

In the anodizing of aluminum a protective oxide iilm is formed on the metal by passing a high Voltage electric current through a bath in which the metal is suspended and through which it passes. The metal serves as the anode and the bath usually contains sulphuric, chromic or oxalic acid. The process Iof anodizing, per se, is Well known in the art and it is, therefore, unnecessary to described it here.

`In the drawings I have illustrated two forms of novel apparatus for carrying out method steps of this invention, and have also illustrated one typical anodized product constituting part lof the invention.

FIGURE 1 shows an anodizing apparatus, on a small scale;

FIGURE 2 is an isometric view, to a larger scale, of the flexing unit which is in the tank of FIG. 1, to provide for repeated bending of the wire as it passes through the anodizing bath;

FIGURE 3 is a view similar to FIGURE 1 but illustrating an alternative apparatus;

FIGURE 4 is a view similar to FIGURE 2, but illustrating a modiied exing -unit embodied in the apparatus of FIGURE 3;

FIGURE is an elevational view of an electrical coil typifying the anodized aluminum wire products of the present invention, this figure also showing two of the pulleys of the mechanism of FIGURE 4, to illustrate a typical size relationship between those pulleys and the typical electrical coil made from the wire which was exed on said pulleys.

Referring now to FIGURES 1 and 2, it will be understood that, before entering the anodizing tank 3, the wire 4 will be passed through a cleaner unit `and water rinses to prepare it for the anodizing process and that after the wire leaves the tank it will pass through further rinses, neutralizers, driers, etc., in a manner well known in the art. The tank 3 is rubber lined and is filled with the anodizing solution. A rectifier unit (not shown) is provided to deliver a high voltage current to the anodizing solution in a manner also well known in the art.

After the wire enters the tank it passes beneath a guide pulley 5 which is mounted on a horizontal shaft extending between the walls of the tank. It then passes to the exing unit indicated as a whole by the reference letter A. This unit and the various components thereof may be made of any suitable materials resistant to sulphuric acid or other acids used in the bath. It comprises side panels 6-6 connected at the center by upper horizontal panel 7 and lower horizontal panel 7 which are secured to and extend between the side panels. The construction is such as to provide an open, box-like framework through which the anodizing bath is yfree to circulate.

The unit is provided at opposite ends with stationary horizontal shafts 8 and 9 which extend between the side panels 6-6. Stationary vertical shaft 10 extends between the upper and lower panels 7 and 7.

A number of grooved sheaves or pulleys are mounted to rotate freely on the three shafts above referred to. Pulleys 11, 12 and 13 are mounted on shaft 8, pulleys 14, 15, 16 and 17 are mounted on shaft 9 and pulleys 18, 19 and 20 are mounted on shaft 10. The various pulleys are suitably separated and kept clear of the walls of the unit by sleeves surrounding the shafts which will not interfere with the free rotation of the pulleys.

After the wire leaves the guide pulley 5 it bends upwardly and then passes over pulley 12, thence around pulley 18 and back to pulley 11. From pulley 11 it passes to and over pulley 14, thence back to and around pulley 20. From pulley 20 the wire passes to pulley 16 and from that pulley back to pulley 13. From pulley 13 the wire passes to pulley 17 whence it runs to pulley 19, pulley 15 and out of the bath to guide rollers 21-22.

In accordance with one aspect of the invention, the pulleys are of various diameters so as to impart bends of differing degrees. As shown by FIGURES l and 2, the pulleys located in the bath, bearing numbers from 5 to 15, are variously of five different diameters and thus provide five different radii of bend for the wire during anodizing. In accordance with another aspect of the invention, the pulleys are arranged in various planes, in this case in planes at right langles to one another, so las to alter the planes of the flexing which is imparted to the wire, and it will be observed that in its passage through the unit the wire completely reverses its direction of travel no less than eight times; and in each case, as the direction of travel changes, the wire is flexed in a horizontal or vertical plane, and with each exure the oxide film which is formed on the wire between the various pulleys is subjected to stresses which will tend to crack or break it and thereby expose the underlying metal to further action of the anodizing bath.

It will also be observed that when passing from certain of the pulleys to certain others, the wire is given reverse bends, so that a given part of the wire surface will receive a concave flexure at one pulley and a convex flexure at the other.

With wires of different diameters or forms, the nature and size of the grooves in the pulleys may be suitably altered to accommodate them to the form and size of the wire, but the effect produced remains the same, i.e., the cracking of the anodized coating to expose unoxidized portions to the further action of the bath and thus to increase the effectiveness of the final coating which is built up on the surface.

Turning now to FIGURES 3 and 4, it will be seen that the pulleys, in the bath, from the initial guide pulley to the final lead-off pulley are of one or the other of two sizes only. For convenience, these pulleys are designated by letters, smaller case letters being used for the smaller size pulleys and capital letters for the large size pulleys.

The first pulley a, used as the guide or lead-in pulley, as shown in FIGURE 3, may be mounted in the tank itself, just as is the pulley 5 in FIGURE l, but it could equally well be mounted on a separate shaft supported in the side frame members of the exing unit. Taken in order of the reeving of the wire around the pulleys, the remaining pulleys in the anodizing equipment are designated B, C, D, E, F, G, lz, z', j, k, l, m, and for convenience in following the path of the wire 4, the runs of the wire are designated alphabetically, from 4a to 4u, as shown in FIGURES 3 and 4. In this embodiment, all the pulleys within the bath are mounted in the frame of the exing unit or assembly, the lead-in pulley a being mounted by a shaft supported by extensions 6a of the side members 6 and 6.

Although the anodized wire produced on the apparatus of FIGURES 1 and 2 is suitable for the production of electrical coils of various diameters, and also for other uses, the wire produced by the equipment of FIGURES 3 and 4 is especially useful when formed into an electrical coil having a diameter intermediate the diameters of the small pulleys a, h, i, j, k, I and m, on the one hand, and the larger pulleys B, C, D, E, F and G, on the other hand.

For the purpose of illustrating this, FIGURE 5 shows a typical small pulley a and a typical large pulley B having a diameter about idouble that of pulley a. Intermediate these pulleys is shown an electrical coil comprising two layers of anodized vire 4z, produced on the equipment of FIGURES 3 and 4, and wound to a diameter about half way between the diameters of pulleys a and B, upon a core or spool 23 having retaining pieces 24 at its ends. By test, I have found that an electrical coil made in accordance with the method and apparatus of the present invention, is characterized by exceptionally good insulation.

As to certain terms used in the appended claims, I would here add by way of further definition that, according to the method of the present invention, the wire is subjected to an anodizing medium, for example by being drawn through an anodizing bath; it is repeatedly subjected to substantially differing bending operations, by which I mean bending operations in planes at very substantial angles to each other or bending operations on substantially differing radii; and it is resubjected to an anodizing medium, by which I mean subjection during and/ or after bending operations. The equipment, illustratively, but not by Iway of limitation, employs, as bending members, pulleys or sheaves for Idirecting as well as for bending or exing the wire.

-I claim:

1. The method of anodizing aluminum wire ywhich comprises subjecting the wire to an anodizing medium to form an anodic coating thereon, breaking the coating by bending the wire in one plane, straightening the wire, resubjecting the straightened wire to an anodizing medium to form additional anodic coating thereon, again breaking the coating by bending the wire in a plane transverse to said one plane, again straightening the wire, again resubjecting the straightened wire t0 an anodizing operation to form additional anodic coating thereon, thereafter repeating said wire bending and straightening steps, vand subjecting the wire to additional anodizing operations following the repeated straightening operations.

2. The method of claim 1 wherein the wire is bent to different radii in different bending operations.

3'. The :method of claim 2 wherein the wire is wound into a coil having a radius intermediate the radii of bending in the different bending operations.

6 References Cited UNITED STATES PATENTS 4/1932 Kuttner 204-35.l

U.S. Cl. X.R.

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