US2457870A - Three-phase electric resistance wire heating apparatus - Google Patents

Description

Jan. 4, 1949. 2,457,870

- J. COO THREE-PHASE ELECTRIC RESISTANCE WIRE HEATING APPARATUS Filed May 31,1946

Patented Jan. 4, 1949 OFFICE -?P!IASE ELEC WIRE 'HEATIN m6 RESISTAN E G APPARATUS 10hr: Ridzcwood, N. J. p cat on May 31, 1946, serial No. erases 6 cla ms- This invention relates to apparatus for electt'nicallv heating a continuously mowing wire. More particularly, it relates to a device or heat.- ing a continuously moving wire to predetermined and differing temperatures at various sections along path of travel .0! the wire.

This invention is particularly applicable to the metrical heating of continuously moving wire, ior the purposes of raising wire to a tem pemture sufiioient to or completely an.- i

the wire, as my be desired in any given instance, and especially prevents overheating of wire while it is exposed to the oxidizing inoi'the arr. 1 invention is applicable to many i conn ti n with the manufa ture of wire, but is here illustrated as applied to the annealing of wire during the manufacturing process, between the final stage 0! drawing the wire and the stage of winding or spoofing the wire.

"In H. B. TPatents 2,178,582 and 2,116,583, granted to the present applicant, there are shown certain for electrically heating and anhealing continuously moving wire. The present eradication includes a further development and imnrouement in the heating apparatus disclosed in the above identified patents.

In the electrical heating of moving wire, it has cust mary to emb m as asoume of electrical power, single-phase alternating current. The employment of cmrent, of this character has been to several difiicultlcs. In the first Place, i has been DIODORd that there be employed commzratirely elaborate and complex current re u at ry d r ces, when it was found desirable to heat the wire to clifiercnt temperatures at different sections along its bath of traverse This difliculty a ises Irom. the :fact a .sinxle nhase current source is necessarily of a single voltage, and the effective vol age .or eflective current flow m st. be r duc d by suitable recuiatory means before such current is applied to sec tions of the in order that may be as highly heated as are other sections of the wire, to which latter the full voltage must be applied. More particularly, a simple series connection of the entire ngth of who becomes imp ssible under suc cir umstance since this mode or conncc time esta lishes a uniform flow o1 current throughout the wire, and the heat d veloped by this uniform current flow will cause. development of vary ng de rees of heat, since the spool no res stanc at therwire, varies at difierent points along its path of travel, due to the temperature resistance .coemcicnt oi the material of which is ordinarily not positive temperature-resistance coefficient, there has been encountered great difllculty in securing a'desired distribution of heat along the length of the wire, when such series connection was attempted to be employed. Another difficulty inherent with the employment of a single-phase source has been that the greater portion of clcotzicalencrgy available for power purposes is of type, and it is undesirable, for reasons well known in the electrical art, to impose a load upon any sin le phase of such polyphase circuits, thereby causing electrical unbalonce of the power system.

Still another problem which is lnvolvai in the animating of wire, arises from the -fact that the final stage of the annealing is performed upon a section of the wire which is then passing through a protective atmosphere of a non-oxidizing nature. It is therefore of the greatest importance that the wire shall not, before it enters this atmosphere, be heated so highly that it will oxidize upon the surface. At the same time it is essential that the wire be at such a temperature that annealing will progress properly as soon as the-wire does enter the final stage just described. Mechanical considerations render it not feasible to. make, either mechanical or electrical contact with the wire when it is passing through this final stage; Therefore the only control over the temperature of the wire at this stage must be by contacts which are made with the wire before it enters the stage, and after it leaves it again.

have iound that it is possible to employ poly phase alternating current for heating a continuonsly moving wire to different temperatures at difierent portions along its path of travel, while at the sunshine maintaining a substantially uniform load upon. difi'erent phases of the power circuit, and assuring the correct temperature of the wire during the final stage, while not overheating it before it reaches this stage.

,I have likewisev found it possible, when employin: polyphase electrical current derived from a three wire, delta connected circuit as an energy source, so to connect the various phases of the power source to a continuously moving wire that dilfcrentsectlons of this wire will be heated to the different temperatures which have been found most-desirable in practice.

' An other object. of this invention is to provide apparatus for heating continuously moving wire by the direct passage of electrical current therethrough, while maintaining the wire entering and leaving such apparatus at substantially ground potential, so that the possibility of electrical shock to the operator of the apparatus is a substantially equilateral delta, and electrical currents of differing phases and differing voltages are applied to the capstans so as to cause unequal heating of the wire along different sides of the delta.

Further purposes and advantages of the instant invention will be apparent to those skilled in the art from the following specification and from the hereunto appended drawings.

Reference is now made to the drawings where:

Fig. 1 is a partly schematic representation of wire heating and annealing apparatus according to my invention, in which the wire is divided into sections, all having the same length.

Figure 2 is a partly schematic representation of a modified form of my invention in which the wire is mechanically and electrically divided into sections of unequal length.

In Fig. 1 reference numeral I is a schematic representation of the final stage of wire drawing machinery, from which the wire proceeds through the annealing device in the direction indicated by the arrows l2. At I3 is schematically indicated a contact device, preferably of the rotating contact wheel type, over which the wire passes, current being conducted to this contact wheel via brush I l. The wire passes over a similar contact wheel l5. The portion l6 of the wire, lying between these two wheels thus constitutes a separate portion of an electrical heating circuit, current being conducted to wheel I5, via brush |1. Similarly, the wire passes over contact wheel l8, fed with current via brush 19. The section of wire 2|), thus constitutes another discrete portion of the electrical heating circuit. The wire then passes over a fourth contact wheel 2|, fed with current via brush 22, thus providing still another section 23 of the wire in still another electrical circuit. After leaving wheel 2|, section 24 of the wire passes over a fixed capstan 25, and then passes to the spooling machine, schematically indicated at 26. The wire is thus seen to be arranged in a completely closed electrical loop or delta.

A transformer 21 of which only the secondary is indicated in the drawings, for purposes of clarity is of the polyphase type, provided with deltaarranged windings 28, 29 and 30. The common connection of windings 28 and 30 is preferably grounded as indicated at 3|, and brushes I4 and 22 are both connected to this grounded terminal, thereby establishing a substantially zero potential upon the two contact wheels over which the wire passes when entering and leaving the annealing device. Winding 28 has the fewest number of turns and therefore supplies the lowest voltage to the portion I6 of the wire. Winding 29 is somewhat larger and supplies an increased voltage to the already heated and consequently more resistant portion 20 of the wire via contact wheels l and I8, thus causing equal heat to be developed along portion 20, and consequently producing a higher temperature in this portion of the wire. Winding 30 has the greatest number of turns, and therefore supplies to the still more heated portion 23 of the wire an amount of elec trical energy sufficient to produce the maximum desired temperature, the energy in watts of the various sections usually being kept at substantially identical values. As well known in the art, the portions 23 and 24 of the wire may be protected by enveloping shields, through which an inert gas or steam may be passed, for the purpose of preventing undue oxidation of the surface of wire at the elevated temperatures encountered at these portions. Such shields do not constitute part of the instant invention and may not be needed in some cases, although they are usually employed in the annealing of copper wire.

In Fig. 2 certain elements are identical with those shown in Fig. 1 and bear corresponding reference numerals, so that detailed description thereof is unnecessary. In this embodiment of the invention, transformer 21 is provided with three windings 28, 29' and 30 which are connected, respectively, to section IS, 20 and 23' of the moving wire. All the transformer windings are substantially equal in terminal potential, thus allowing the use of a transformer of a readily available commercial type.

In the operation of the embodiment shown in Fig. 2 the contact wheels are so spaced relative to one another that section 16 of the wire has the greatest length, the hotter section 20 is somewhat shorter, and the hottest section 23' is the shortest. Since the resistance of any given section of the wire varies according to its temperature and length, section l5, section 20 and section 23 will have a substantially equal amount of g heat developed therein, from the respective currents flowing therethrough, since the power in watts in the various sections is kept substantially equal.

The current flow through the various sections of the wire will not usually remain uniform, but the energy liberated as heat will be substantially constant, section H3 having the lowest temperature, section 20' having a greater temperature, and section 23 having the highest temperature, as is desirable in the annealing process. Since the heat produced by the current is expressed by the well known formula 1 R, the current necessary to secure the desired increase of temperature as the wire produces, may readily be determined, allowance being made for the fact that the value R will also vary, due to the temperatureresistance coefficient of the wire, such coefficient usually being positive, as previously discussed.

While I have shown in Fig. 1 a transformer provided with windings of unequal size, it is to be understood that windings of equal size might be employed, and the current available from the various windings might be regulated by the use of'external inductors, resistors, or the like. Likewise, in the form shown in Fig. 2, it is possible to make close adjustments of the temperature in the different portions of the wire by theadditional employment of such external regulatory devices as just mentioned.

As diagrammatically illustrated in Figures 1 and 2 of the drawing, a liquid cooling tank T may be employed in which is disposed, subjacent the liquid level, the contact wheel 2| and the lower ends of the shields, which may constitute steam and cooling tubes S and C which receive the portions 23 or 23' and 24 of the wire, respectively, the upper end of the tube C being equipped with a wiper W for wiping the wire as it passes out of tube C.

It is to be understood that transformer 21 may be of any suitable type and that the primary windings thereof (not shown) are to be of a size and type suitable for connection to the available power source.

While I have shown and described'certain embodiments of this invention, these are given by way of example and not of limitation, and it is to be understood that variations and changes thereof will be apparent to those skilled in the art. I am accordingly limited only by the scope of the hereunto appended claims.

What is claimed is:

Electrical wire annealing device, including four contact wheels over which the wire is successively drawn, means for supplying a predetermined voltage between the first and second of said contact wheels, means for supplying greater voltage between the second and third of said contact wheels, means for supplying the greatest voltage between the third and fourth of said contact wheels, and means interconnecting and grounding both said first and said fourth contact wheels, whereby current flows in a longitudinal direction only through said wire, between said contact wheels, and the wire is progressively heated as it passes over said contact wheels, whereby the wire enters and leaves said device at substantially zero potential, and whereby the wire is progressively heated without exceeding a predetermined maximum temperature at any point.

2. A device according to claim 1, in which said means for supplying voltage of unequal values to the respective contact wheels, comprises three delta connected transformer windings yielding unequal and successively increasing potentials.

3. An electrical wire annealing system operative upon moving wire, including means for subdividing the wire into a plurality of electrically discrete sections, arranged to form a delta loop, the wire entering and leaving the system at a linkage point of the loop, said linkage point being grounded, a polyphase electrical power supply arranged in a similar delta 100p and respectively connected to said discrete sections of wire, and means for sending substantially uniform heating power through each successive link of said loop, whereby the temperature of the wire is progressively increased, and prevented from exceeding a predetermined maximum temperature at any section along the path of travel thereof.

4. A system according to claim 3, wherein said current determining means comprises means for making successive links of the wire loop each shorter than the preceding one, whereby heating of the wire is progressively increased, and heating power is kept substantially constant along the entire loop.

5. A system according to claim 3, wherein said current determining means comprises means for making successive links of said power supply delta loop of successively increasing voltages.

6. In a three phase system of annealing wire, means for arranging a wire to be annealed in the form of a substantially triangular loop, means for applying current thereto via contact members located at the respective apices of the triangle and having three phase energy supplied thereto via said contact members, means whereby the wattages of the respective phases of said loop are kept approximately identical in value, and means whereby wire entering the third phase of said loop is held below a predetermined temperature, whereby to prevent the oxidation thereof, said means also providing that the wire in passing through said third phase of said loop will reach a proper annealing temperature, said wire upon entering and leaving said loop being connected to a single contact element, and means for grounding said last contact element.

I JOHN COOK.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,347,917 Sheperdson July 17, 1920 1,718,806 Witting June 25, 1929 2,005,912 Drake June 25, 1935 2,415,027 Bosomworth et a1. Jan. 28, 1947 FOREIGN PATENTS Number Country Date 444,491 Great Britain Mar. 20, 1936 547,035 Germany Mar. 22, 1932

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