US3094476A - Apparatus for forming metal fibers - Google Patents

Description

June 1963 H. T. FRANCIS APPARATUS FOR FORMING METAL FIBERS Filed July 13, 1960 2 m I 7 m m m 5 I 6 1 R 7 n 474 4 W F w mwi a Ali m l M M v Q H w y 2 2 m v are The present invention is directed to a method and ap paratus for forming metal fibers and more particularly, to a method and means whereby very thin fibers of uniform dimension are readily and conveniently formed.

As employed in this specification and claim the term fibers denotes an elongated metallic filament having a long dimension substantially greater than its mean dimension in cross section; in other words, relatively elongated metallic bodies of fine cross section. As a general rule, a fiber should have a length of at least times its mean dimension in cross section. The term mean dimension is related to the shape of the fiber or filament in cross section and refers to the diameter in the case of a circular filament, and in the case of a rectangular ribbon, denotes one-half the sum of the short side and the long side of the rectangle.

Metal fibers are currently manufactured primarily by four different methods, namely; scraping from wire, machining in a lathe, cutting from a stacked sheet, and wire drawing. In all of these methods the fibers produced are of relatively large cross section. That is, it is very .difiicult to produce extremely thin fibers. This is not to say that the likelihood of manufacturing thin fibers, by the aforementioned techniques, is entirely precluded. On the other hand, none of these methods, would continuously produce extremely thin (on the order of 0.5 thousandth of an inch in cross section) fibers.

All of these are mechanical methods with resultant drawbacks. Furthermore, as will be readily understood, only limited control of the fiber dimension is possible with these methods. For example, scraping from wire would allow the least control over fiber dimension. *Contrariwise, cutting from a stacked sheet will provide the best accuracy. The latter method though accurate, is costly in that a multiplicity of operations upon the raw material are necessary.

In contradistinction to the teachings and practices of the prior art, I have developed a primarily electrochemical method enabling continuous manufacture of uniformly fine metal fibers and relatively uncomplex apparatus therefor.

it is accordingly, an object of the present invention to establish an improved method of forming thin metal fibers.

Another object of the present invention is to provide a method and apparatus for the continuous manufacture of extremely thin fibers exhibiting ease of control over fiber dimension.

Still another object of the instant invention is the provision of a method, and apparatus therefor, of electroforming metal fibers.

Yet another object of the instant invention is to provide a method, and apparatus therefor, for the continuous manufacture of extremely thin metal fibers.

The foregoing objects and others which will become apparent from a detailed reading of the description to follow, are accomplished by e-lectrodepositing metal from an appropriate bath onto circular rotating discs immersed in the bath and controlling the dimensions of the fiber by regulating the current density in the solution and the rate of rotation of said discs.

In the drawings:

FlGURE 1 is a schematic View, partly in section, of

atent isc apparatus capable of performing the method of the instant invention.

FIGURE 2 is a schematic perspective View, partly in section, particularly useful in describing the application of the principles of the claimed invention.

FIGURE 3 is a perspective view of two discs illustrating an alternative embodiment thereof.

FIGURE 4 is a view of a bisected conductive disc with a fiber 23 electrodeposited thereon in accordance with the teachings of thi invention.

Before describing my method in detail, it will be helpful to outline the utility of metal fibers. Because of the increasing concern over the strength to weight ratio of metal structures and/or articles a need exists for increasing such ratio. Immediately, one recognizes that a substantial weight reduction coupled with a small decrease in strength will result in a greatly improved structure. It has been discovered that a sintered interlaced network of metal fibers can, in many instances, provide adequate structural strength coupled with a material reduction in weight, and it is along these lines that fiber metallurgy has rapidly developed. However, the ever increasing demands for metal fibers has resulted in the need for a method for economically and efiiciently manufacturing thin metal fibers.

For a more detailed description of metal fibers their field of use, the readers attention is directed to copending applications, Serial Numbers 492,007, filed March 3, 1955, and 6,290, filed February 2, 1960, both assigned to the assignee of the present application.

Turning next to the drawings, FIGURE 1 shows a device for performing my method which includes a container 10 having mounted therein: rotatable shaft 16, anodes 15 and cylinder 11 comprising discs 12 and 13. Conductive metallic discs 12 are alternately interspersed between nonconductive dielectric discs 13. Shaft 16 is insulated from container ill by means of bushings 24 and is opcratively connected to motor 20. Shaft 16 has a key 15a runing therealong which couples rotational motion from the shaft to discs 12 and 13. One end of shaft 16 is connected to a pole of battery 21 while its other end is connected to the armature of motor 20.. That portion of shaft 16 connected to motor 20 is made of a non-conducting material 1612 in order that motor 20 be insulated from battery 21. Anodes 15 are connected to the other pole of battery 21 through switch 22. Anodes 15 are supported within, and insulated from, container 10 by rubber bushings 25. Switch 22 through its various positions, enables control of the voltage applied across shaft 16, conducting discs 12 and anodes 15. By this expedient the current .density in bath 19 is regulated.

Discs 12 are each provided with an opening 18 corresponding to the shaft 16 and are made of a passive metal, for example, stainless steel. By passive metal is meant that type of materia to which an electrodepositable coating will not adhere.

Bath 19, within container 10, is a solution containing the metal to be deposited upon conducting dis-cs 12. The fiber composition is chosen by a proper selection of the constituents in bath 19. For example, bath 19 may comprise solutions of: iron, nickel, copper, combinations thereof, or any other metal which is readily electrodepositable. When switch 22 is moved from the off position to some positive potential, a current is established between the anodes 15 and conducting discs 12 causing metal ions contained in the bath 19 to be deposited upon conducting discs 12. It is noted that no deposit is formed on discs 13 because they are non-conductive.

It is noted that cylinder 11, when mounted on shaft 16, has a portion thereof (/1 see FIGURE 1) extending out of bath 19. The extent of protrusion of cylinder 11 3 out of bath '19 is not critical, however, it must extend beyond bath :19 to enable removal of the formed fibers.

The thickness 1 (see FIGURE 4) of fiber 23 is governed by the angular velocity of cylinder Ill and the magnitude of the current applied. In other words, the thickness is dependent upon the time a finite area (for example da in FIGURE 3) is in the bath and the magnitude of the current density causing the metal in the solution to be deposited on said area. The width w of fiber 23 is independent of the above noted factors, however, w is controlled by providing sets of discs 12 having different thicknesses.

In operation, the fiber thickness is predetermined by calculating the rate of rotation of cylinder .11 for a given voltage setting of switch 2.2;. After controls 20a and 22 are set and metal is being deposited, a doctor blade 14, supported by posts 14a (suspended out of bath 19 but in contact with cylinder '11) scrapes the fibers from discs 12 prior to the re-entry of the disc surf-aces into bath 19.

The means for transporting the fibers from doctor blade 14 are not shown in that many well known devices are suitable therefor. A conveyor belt passing immediately beneath the trailing edge of doctor blade 14- operates satisfactorily as the fiber transporting device.

FIGURE 3 depicts an alternative embodiment of the conducting discs 12 whereby the fibers 23 are of finite length. This is brought about by circumferentially spacing, about discs 12 nonconducting sections 17. Sections 17 are dielectric and may be of the same composition as discs 13. Fiber metal will only deposit upon the conducting sections and, dependent upon the number and displacement of sections 17, specific lengths of metal fibers are produced. In all cases having nonconductive discs 13 at both ends of cylinder 11 provides most efiicient operaton because then no metal is deposited on the exposed planar faces of the discs.

My inventoin may best be fully envisioned by reference to the following examples:

Example I The production of nickel fibers according to my invention is accomplished under the following bath conditions:

Bath composition:

Nickel sulfate, NiSO -7H O gr-ams/liter 300 Nickel chloride, NiCl -6I-I O do 60 -Boric acid, H BO do 38 Temperature C 54 pH 2.0

Cylinder Speed Current Den- Fiber Thickness (square feet per sity (amperes (thousandths of hour passing per square foot) an inch) through bath) 4 Example II The same equipment produces iron fibers when an iron plating bath is used under the following conditions:

Bath composition: Ferrous ammonium sulfate,

Fe(NH (SO "grams/liter" 350 Temperature C Fiber thickness for iron deposition was found to be very similar to that for nickel, being about 8% greater than the nickel thickness under like conditions of cylinder speed and current.

Example III An example of alloy fiber production is brass, plated from the following bath and with the conditions noted:

Bath composition:

The plating efficiency of brass baths is quite variable, therefore, only an approximate fiber thickness is given; thicknesses generally of the same order as for nickel are produced under similar conditions of cylinder speed and current.

From the foregoing it will be appreciated that I have provided a novel method and apparatus for the production of uniformly fine fibers. However, it is noted that the invention is not limited thereto. The method affords considerable versatility coupled with the unique capability of enabling the continuous manufacture of metal fibers of smaller cross section than those heretofore presented.

Accordingly, it is to be understood that within the scope of the appended claim the invention may be practiced otherwise than has been specifically set out in the detailed description of my invention.

I claim as my invention:

In combination, apparatus for the manufacture of thin metal fibers comprising: container means; a solution containing an electrodepositable material in said container, conductive means suspended within said container but insulated therefrom; a series of discs having conductive and non-conductive sections uniformly spaced from each other about the periphery of said discs; a series of nonconductive discs interspersed alternately between said last mentioned discs whereby all the discs are in axial alignment and substantially completely immersed in said solution; means for rotating said discs in unison; means for applying a voltage across said discs and the conductive means; means for removing the electrodepositable material from said conductive sections; means for regulating the rate of rotation of said rotating means; and means for regulating the magnitude of voltage applied across said discs and the conductive means.

References Cited in the file of this patent UNITED STATES PATENTS 1,600,257 Topping Sept. 2.], 1926 1,878,540 Reinhardt et al. Sept. 20, 1932 FOREIGN PATENTS 3,160 Great Britain Feb. 11, 1909

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