US2459507A

US2459507A - Method of induction heating continuously moving wire

Info

Publication number: US2459507A
Application number: US568703A
Authority: US
Inventors: Robert H Denham
Original assignee: General Electric Co
Current assignee: General Electric Co
Priority date: 1944-12-18
Filing date: 1944-12-18
Publication date: 1949-01-18
Anticipated expiration: 1966-01-18

Description

R. H. DENHAM METHOD OF INDUCTION HEATING CONTINUOUSLY MOVING WIRE Jan. 18, 1949;

Filed De c .IWI m A M y Inventor: Robert, H. Denham, b War/176x) y His Attorney.

Patented Jan. 18, 1949 METHOD OF INDUCTION HEATING CONTINUOUSLY DIOVING WIRE Robert H. Denham, Scotia, N. Y., assignor to General Electric Company, a corporation of New York Application December 18, 1944, Serial No. 568,703

(Cl. 2l913) 4 Claims. 1

My invention relates to an induction heating method, more particularly to a method of annealing wire made of an electrically conducting material, such as copper or steel, and has for its object a simple, reliable and low cost induction heatin method wherein the consumption of electric power is reduced to a minimum.

In carrying out my invention in one form, I provide a tank in which a suitable cooling liquid is maintained at a predetermined level, together with two sheaves in the tank, one totally submerged in the liquid and the other only partly submerged, with means for passing the wire to be annealed in two loops around the sheaves which have conical surfaces thereby to bias the turns together and form a short-circuited secondary. The arrangement is such that the upper length of the secondary leading between the two sheaves consists of a single length of wire. I also provide transformer means for inducing heating currents in the short-circuited secondary and run the wire over the sheaves so that the single length moves from the partially submerged sheave to the other one, during which movement it is first heated and then cooled by the liquid in the tank. Thus the generation of the heat in the wire itself reduces the electric power required to a minimum.

In a modified form of my invention which is particularly applicable to wire having 2. rectangular cross section, I pass the wire in a single loop between the two sheaves with two turns around one sheave, which turns are arranged one above the other to provide for electric contact between them.

For a more complete understanding of my invention, reference should be had to the accompanying drawing, Fig. 1 of which is a sectional view of induction heatin apparatus for annealing wire embodying my invention; Fig. 2 is an enlarged view in section of one of the sheaves; Fig. 3 is a side elevation View with the tank in section showing a modified form of my invention; Fig. 4 is a sectional view along the line 4-4 of Fig. 3 looking in the direction of the arrows; Fig. 5 is a wiring diagram; while Fig. 6 is a diagram showing the arrangement of the wire loops in the device of Fig.1.

Referring to the drawing, I provide a tank I provided with an inlet opening 2 for a suitable quenching fluid, such as water, and an overflow opening 3 by means of which the quenching fluid is maintained at a predetermined level indicated by the dotted line 4. Suitably mounted in the tank for rotation about horizontal axes and electrically insulated from each other are two sheaves 5 and 6, the sheave 5 being largely above the liquid level 4, while the sheave 6 has its uppermost portion a substantial distance below the liquid level 4 so as to be immersed in the liquid.

By means of reels or

spools

1 and 8, the wire 9 to be annealed is passed around the two sheaves in two loops or turns, there being two semicircular lengths on the outer surface of each sheave, as shown in Figs. 2 and 6. As shown in Fig. 2, each sheave is provided with a tapered or conical face or surface l0, constitutin the bottom wall of a peripheral groove in the sheave, on which the two semicircular turns or lengths slide laterally toward the left hand, as seen in Fig. 2, to the point of least diameter whereby an electrically conducting relation is maintained between the two lengths. It will be understood that the turn H (Fig. 2) has slipped on the tapered surface to its point of least diameter against the flange [2, while the turn [3 has moved downward against the turn II.

By reason of the tension applied to the wire, the turn I3 is held against the turn 5 l with a sub-- stantial force, and likewise the turn 13a is held against the turn Hat on the sheave 5 with a substantial force, thereby to maintain good electrically conducting relations between them, whereby the wire constitutes a closed circuit secondary conductor or loop.

The wire is moved between the two reels l and B in the direction indicated by the arrow. Preferably, a suitable driving means, such as an electric motor I4, is applied to the reel 8 thereby to Wind wire up on the retrieving reel 8 and apply a predetermined tension to the wire so as to rotate the sheaves and pull the wire off the feed spool I which is restrained by suitable means (not shown). From the spool l, as indicated in Fig. 6, the wire moves over the sheave B to form the outermost turn l3, then over the sheave 5 in the outermost turn |3a to the sheave E in the single length I 5, then around the sheave 6 in the innermost turn H, thence to the sheave 5 and around the innermost turn Ila to the spool 8.

For heating the wire, I provide transformer means consisting of an iron core l6 provided with a primary winding I l, the core having three legs between a pair of which passes the upper and lower lengths of the wire, a central leg [8 of the core extending between the lengths of wire. When the primary winding is energized by suitable alternating current, currents are induced in the short-circuited secondary formed by the wire as it is fed continuously over the two sheaves.

The lower length 19 consists of two conductors and therefore, because of the low resistance of this length, the heat enerated in it is not suflicient to heat it to an annealing temperature. Moreover, this length is completely submerged in the quenching liquid in the tank and is cooled by the liquid. However, the upper single length of wire I is heated because of its higher resistance to a predetermined annealing temperature in passing from the sheave 5 to the sheave 6, and then at its right-hand end is cooled where it is submerged in the cooling liquid.

It will be understood that the two

spools

1 and 8 are axially displaced with respect to each other so that two outgoing and incoming wires where theycross each other at the point are spaced apart so as to be electrically insulated from each other. In a typical apparatus, approximately four-fifths of the voltage induced in the secondary loop appeared across the single strand or length I5.

I also provide a tubular member 2| made of electrically insulating material, such as quartz, which is mounted in an inclined or nonhorizontal position on spaced apart

cross partition walls

22 and 23 in the tank so as to surround the upper wire length to form a chamber surrounding the wire for a sveamatmosphere. The right-hand end of the tube 2i extends downward into the quenching liquid in the tank below its surface so that a small quantity of water is present in this end of the tube. In cooling, the wire raises the temperature of this water in the tube 2! to a boiling temperature, whereby a steam atmosphere is maintained around the wire for the prevention of oxidation, the upper left-hand end of the tube 2| being constricted to restrict the escape of steam around the wire.

The

partition walls

22 and 23 on opposite sides of the core it and primary winding I! are each connected with fluid-tight joints to the bottom and side walls of the tank thereby to divide the tank into two portions at its left-hand and right-hand ends respectively and form a space between them for the core and winding. These two tank portions are connected together through relatively large inclined tubular member 24 made of electrically insulating material adjacent the bottom of the tank through which extends loosely the lower double wire length l9.' The tube 24 further serves to prevent the engagement of this wire length with the conducting parts of the tank in the event that the tension on the wire is relieved with consequent sag of the wire. It will be noted that the tubes 2! and 24 are substantially parallel with each other and spaced apart so that the parallel lengths of wire travel along the center lines of the tubes, the diameters of the two sheaves being the same.

Another advantage of my invention is that no tension is applied to the single heated length I5 other than that resulting from its own weight. This is because the semicircular turn i i (Fig. 6) has a smaller diameter than the semicircular turn Ho and, as a consequence, the turn i3a feeds wire to the spool 6 slightly faster than it is taken up by the turn I! so that no tension is applied to the single length [5.

Moreover, the 'fact that the larger diameter turn 13 or Isa on the two sheaves moves somewhat faster than the smaller diameter turn produces a small amount of relative movement and friction between the two, whereby a good electrical connection between them is assured. If desired, the sheaves may be provided with 4 drums made of good electrically conducting material, such as copper, to form an electrical connection between the two wires. However, I have found that the jamming and frictional action between the two turns is suificient to maintain good electrical contact between them.

In Fig. 3, I have shown a modified form of my invention which is especially adapted to annealing of a rectangular wire whose turns are positioned in superimposed relation around one sheave. The incoming wire 26 is fed to the sheave 27 to form a turn 23 (Fig. 4) lying on top of a turn 29. Then the wire passes in a single turn loop around the sheave 39 and then passes again around the sheave 2? to form the lower almost complete turn 29, after which the wire goes directly to the spool 8. Except for the difierence in the construction of the surfaces of the two sheaves, the apparatus of Fig. 23 is the same as that shown in Fig. 1. As shown in Fig. 4, each sheave is provided with a rectangular peripheral groove which is much wider than the wire to provide for lateral displacement of the outgoing wire, toward the left hand as seen in Fig. 4, as it is drawn on the sheave 2'! so that the wire as drawn off ample clearance with respect to the incoming length 26 and the upper length between the sheaves at the points where the outgoing wire crosses them. Also, the groove is preferably wide enough to accommodate different sizes of rectangular wire. The alignmentcf the wire on the sheaves and the superimposing of the turns on the sheave El is accomplished by the relative axial positioning of the sheaves and the guiding of the incoming wire 25 to the sheave 2?.

As explained in connection with Fig. l, the faster traveling outer turn 23 sildes somewhat with respect to the inner turn 29 thereby maintaining a good electrical connection between them and preventing any substantial tension in the single lengths of wire extending between the two sheaves. Fhis is of importance in connection with the upper length which is heated. The only tension in the upper length is that required to turn the sheave 39.

Preferably, as shown in Fig. 5, an induction regulator 3i is provided in circuit with the primary winding l! for the control of the voltage supplied to the winding and the temperature of the upper heated length of wire. Current is supplied at a suitable frequency by supply mains 32, for example, a frequency of 60 cycles. Additional control of the heating operation is obtained by taps 33 on the primary winding.

While I have shown a particular embodiment of my invention, it will be understood, of course, that I do not wish to be limited thereto since many modifications may be made, and I therefore contemplate by the appended claims to cover any such modifications as fall within the true spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. The method of heating electrically conducting wire which consists in passing the wire continuously in a loop having two turns at each end in electrically conducting engagement with each other while maintaining the ends of the wire in separated electrically insulating relation with each other thereby to form a loop having two electrically connected turns at opposite ends with a single wire length on one side of the loop and a double wire length on the other side of the loop, and inducing in said loop by magnetic induc tion a heating current flowing through said single and double wire lengths in series with each other so that heat is generated mainly in said single wire length to heat the wire to a predetermined temperature.

2. The method of heating electrically conducting wire wherein are utilized two sheaves spaced a predetermined distance apart and constructed each to maintain two turns of wire thereon in electrically conducting relation with each other which consists in passing the wire continuously at least two times around both of said sheaves while maintaining the ends of the wire in separated electrically insulating relation with each other thereby to form a loop extending between said sheaves having two electrically connected turns on each sheave with a single wire length on one side of the loop extending between said sheaves and a double wire length on the other side of the loop extending between said sheaves, inducing in said loop by magnetic induction a heating current flowing through said single and double wire lengths in series with each other so that heat is generated mainly in said single wire length to heat the wire to a predetermined temperature, and passing the Wire continuously around said sheaves by drawing the wire from one sheave while feeding the wire to the other sheave.

3. The method of heating electrically conducting wire wherein are utilized two sheaves spaced a predetermined distance apart and constructed each to maintain two turns of wire thereon of different diameters in electrically conducting relation with each other which consists in passing the wire continuously at least two times around both of said sheaves while maintaining the ends of the wire in separated electrically insulating relation with each other thereby to form a loop extending between said sheaves having two electrically connected turns of different diameter on each sheave with a single wire length on one side of the loop extending between said sheaves and a double wire length on the other side of the loop extending between said sheaves, inducing in said loop by magnetic induction a heating current flowing through said single and double wire lengths in series with each other so that heat is generated mainly in said single wire length to heat the wire to a predetermined temperature,

and passing the wire continuously around said sheaves by drawing the wire from the smaller turn on one sheave while feeding the wire to the larger turn on the other sheave whereby substantially no tension is applied to said heated single length of wire.

4. The method of heating electrically conducting wire wherein are utilized two sheaves spaced a predetermined distance apart and constructed each to maintain two turns of wire thereon of different diameters in electrically conducting engagement with each other which consists in passing the wire continuously at least two times around both of said sheaves while maintaining the ends of the wire in separated electrically insulating relation with each other thereby to form a loop extending between said sheaves having two electrically connected turns of different diameter on each sheave with a single wire length on one side of the loop extending between said sheaves and a double wire length on the other side of the loop extending between said sheaves, inducing in said loop by magnetic induction a heating current flowing through said single and double wire lengths in series with each other so that heat is generated mainly in said single wire length to heat the wire to a predetermined temperature, and passing the wire continuously around said sheaves by drawing the wire from the smaller turn on one sheave while feeding the wire to the larger turn on the other sheave whereby substantially no tension is applied to said heated single length of wire and a small amount of relative movement is produced between the turns on each sheave to assure a good electrical connection between them.

ROBERT H. DENHAM.

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

UNITED STATES PATENTS Number Name Date 496,208 Procunier Apr. 25, 1893 1,607,675 Jefferies Nov. 23, 1926 1,811,522 Shover et al June 23, 1931 1,937,420 Wood et al. Nov. 28, 1933 2,040,343 Simons et al May 12, 1936 2,064,589 Convers Dec. 15, 1936 2,176,583 Cook Oct. 17, 1939 2,315,189 Cook Mar. 30, 1943 2,407,120 Wilson Sept. 3, 1946 2,415,027 Bosomworth et a1. Jan. 28, 1947 2,417,029 Wilson Mar. 4, 1947