US3182167A - Resistance heating apparatus - Google Patents

Description

y 1965 E. F. M BRIEN 3,182,167

RESISTANCE HEATING APPARATUS Filed Jan. 23, 1962 2 Sheets-Sheet l INVENTOR. EDWARD F. McBRlEN FIG. 3 3% Q1 ATTORNEY y 1965 E. F. M BRIEN 3,182,167

RESISTANCE HEATING APPARATUS Filed Jan. 23 1962 2 Sheets-Sheet 2 FIG. 4

FIG. 5 82 INVENTOR. EDWARD F. Mc BRIEN ATTORNEY United States Patent f 3,182,167 RESISTANCE HEATBIG APPARATUS Edward F. McBrien, Parrna, Ohio, assignor to The Ohio Crankshaft Company, Cleveland, Ohio, a corporation of Ohio Filed Jan. 23, 1962, Ser. No. 168,114 3 Claims. (Cl. 219-1059 This invention pertains to the art of electrical heating and more particularly to an apparatus for resistance heating indefinite lengths of electrically conductive materials.

The invention is particularly applicable to the heating of continuously moving wire and it will be discussed with particular reference thereto; however, it is to be appreciated that the invention has much broader applications and may be used for the heating of other items of indefinite length such as metal strip, springs, tubing, etc.

In the manufacture of wire, it is often desirable to anneal or otherwise heat treat the wire during the processing thereof. For instance, when the diameter of the wire is reduced by successive drawing operations, the wire is intermittently annealed to relieve cold working stresses in the wire. In the past, such wire has been annealed by coiling the Wire onto a spool and soaking the spool in a holding furnace, which procedure greatly increases the production cost and prevents continuous processing of the wire. In order to eliminate the requirement for soaking individual coils of Wire, it has been suggested to continuously heat the moving wire as it is being processed; however, prior attempts to accomplish this desired result have proven unsatisfactory. For instance, a fuel fired mufiie for continuously heating a moving wire had to be excessively long or the speed of the moving wire had to be greatly reduced to obtain the proper temperature in the moving wire. An induction coil for inducing a current into the wire as it was moving Was limited by the reference depth and diameter relationships of the wire so that inefficient heating resulted.

It has heretofore been proposed to heat the wire while it is continuously moving by electrically contacting the Wire at spaced points on its path of movement, inter-connecting these contact points and then causing a heating current to flow in the loop so formed, such currents usually being induced to fiow by transformer action. Dilficulty has been experienced however, with such arrangements because of the arcing which occurs between the contacts and the wire as the Wire leaves the contacts, which arcing tends to pit and otherwise mar the surface of the wire, making it unsuitable for further processing, or otherwise making it unsaleable. These arrangements also required sliding engagement between the contacts and the moving wire which engagement tended to scar the surface of the moving Wire.

The present invention provides apparatus of the type last described which overcomes the disadvantages stated and others and allows the heating current to be introduced into the continuously moving wire Without arcing at the contacts.

In accordance with the present invention there is provided an apparatus for continuously heating a moving wire. This apparatus comprises first and second rotatably mounted drums spaced from each other, the moving wire forming a conductive loop between these spaced drums. This conductive loop comprises a first portion of wire Wrapped partially around the first drum, a second portion of wire extending between the drums and wrapped around the second drum and a third portion of wire wrapped partially around the first drum. A transformer is provided comprising a primary winding and a core with the core having an opening through which the second portion of Wire extends. The first drum comprises a 3,182,167 Patented May 4, 1965 plurality of conductive elements on the periphery thereof and extending in a direction substantially perpendicular to the first and second portions of wire and substantially parallel to the axis of rotation of the first drum. The first drum also includes means for insulating these conductive elements from each other. The second drum has a high electrical resistivity peripheral portion in contact with the second portion of the moving wire and the first and second portions of wire are in overlapped relationship to each other on the periphery of the first drum.

The primary object of the present invention is the provision of an apparatus for heating a continuously moving wire which apparatus is economical to produce and durable in operation.

A further object of the present invention is the provision of an apparatus for heating a continuously moving wire which apparatus can be easily adapted to a continuous Wire manufacturing installation.

Yet another object of the present invention is the provision of an apparatus for resistance heating a continuously moving wire which apparatus comprises a means for forming a current conductive section and means for causing a current to flow in this current conductive section without arcing at the various contacts with the moving wire.

Another object of the present invention is the provision of an apparatus for resistance heating a continously movin wire which apparatus has means for forming a current conductive section in the moving Wire, means for electrically connecting the ends of the section and means for causing a heating current to flow through the section without arcing at the various contacts with the moving wire.

Still a further object of the present invention is the provision of an apparatus for resistance heating a continuously moving wire by passing a high heating current therethrough wherein said apparatus has an electrical connection means dividing the heating current into a plurality of smaller branch currents at the various contact points, or other transfer points used to introduce the heating current into the wire, to prevent arcing as current passes through the contact points.

Another object of the present invention is the provision of an apparatus for resistance heating a continuously moving wire which apparatus does not pit or mar the surface of the Wire.

These and other objects and advantages will become apparent from the following description used to illustrate the preferred embodiments of the invention as read in connection with the accompanying drawings in which:

FIG. 1 is a side elevation view illustrating a preferred embodiment of the present invention;

FIG. 1a is a partial view illustrating a slight modification of the preferred embodiment disclosed in FIG. 1;

FIG. 2 is an enlarged detailed view taken along line 22 of FIG. 1;

FIG. 3 is a diagrammatic view of the preferred embodiment disclosed in FIG. 1

FIG. 4 is a diagrammatic view of the embodiment disclosed in FIG. 1a;

FIG. 5 is a somewhat schematic view illustrating an alternative embodiment of the present invention; and,

FIG. 6 is a somewhat schematic view illustrating still further the alternative embodiment disclosed in FIG. 5.

Referring now to the drawings wherein the showings are for the purposes of illustrating preferred embodiments of the invention and not for the purposes of limiting same, FIG. 1 shows an apparatus A for heating a wire W by passing a heating current through a section of the wire as it is continuously moving in a longitudinal direction. The apparatus is provided with a guide means It which may take a variety of structural forms; however, in this preferred embodiment, the guide means It) comprises a pulley, or drum, rotatably supported by an appropriate journal 12 and having a slack adjusting means such as springs 14. It is to be appreciated that the same journal and slack adjusting arrangement is provided on the opposite, but hidden, side of drum It Spaced downwardly from drum It) is a second guide means 16 which, in the preferred embodiment, takes the form of a drum rotatably supported in appropriate journal 18. Located between drurns It) and I6 is an induction heating device comprising an iron core 29 having a Window, or central opening 22 and a primary winding 24 electrically connected to a schematically represented generator 26. The wire W is wrapped around the drums to form an electrically conductive loop or section of wire between the drums.

The drum 1%, although it may take a variety of structural forms is characterized by being constructed of an insulating material or, at least, of a material having a resistance substantially greater than the resistance of wire W. In accordance with the preferred embodiment of the present invention, the drum to 'has a construction quite similar to a commutator for a D.C. generator. (See FIGURE 2.) The outer periphery of the drum 16 is comprised of a plurality of axially extending, electrically conductive bars 32 electrically insulated from each other by a plurality of intermediately positioned, electrical insulation strips 34. The electrically conductive bars 32 provide a plurality of separate parallel electrical connections joining spaced ends 40, 42 of the conductive section of wire between the drums. Ends 40, 42 are the sections of wire W which are both in over-lapping relationship with respect to each other and also incontact with the outer periphery of the drum 16. The number of separate parallel connections is determined by the number of electrically conducted bars in contact with and extending betweenthese over-lapped ends of the wire. By so constructing drum 16, the heating current I is divided into a plurality of branch currents Ix which are individually designated as current I (a:1) shown in FIGURE 2. The current paths of each branch current Ix have substantially equalized impedance because each branch current Ix flows through the same length of the wire being heated. For instance, branch current Ia flows through the heated wire section from a point at the first contact made by wire end 40, around the loop between the drums 1t) and 16, and back to the position axially spaced from the starting point. By tracing the paths followed by each branch current, it is found that the current paths each have the same length of wire W. Since the resistance or impedance of each parallel branch between Wire ends 40 and 42 is substantially the same, the branchcurrents Ix will have a value determined by dividing the heating current I by the number of conductive bars 32 forming the parallel current conducting paths. The proper number of current paths is determined by increasing the angle a until the magnitudes of the individual branch currents Ix are such that arcing is prevented between the moving wire and the drum lid. To guide the wire W around the periphery of the drum 16, it is within the contemplation of the invention to provide grooves 44, 46. It is to be appreciated that the grooves may be eliminated without departing from the intended scope of the present Moving wire W engages the surface of drum In to the left of axis x, moves along the surface of drum l6 past the axis'x and then progresses into electrically inductive relationship with primary winding 24. The wire W then engages the drunrlfi at the left of axis x and extends along the surface to a point to the right of axis x, at which position the moving wire W leaves the surface of the drum. The path of the heating current I is represented by dashed arrows, and the parallel branch currents Ix are shown as extending between the overlapping portions of the Wire W which are in engagement with the surface of the drum 16. By increasing the angle a, the overlapping portion of the moving wire W is correspondingly increased to in clude a greater number of conductive bars 32, which correspondingly increases the number of parallel paths between the wire ends so that the branch current Ix in each path is reduced. In this manner arcing between the wire and the mechanical transfer device on the drum is elimi nated.

The angle a may be increased until it approximates 180 by increasing the entrance and exit angle of the moving wire W; however, as the angle a approaches 180 the Wire W entering and leaving the drum surface is substantially parallel, which may not be advantageous in practice. For this reason the angle a is increased to 180 by winding the moving wire W on drum 16 in a manner disclosed in FIG. 1a and diagrammatically represented in FIG. 4. It is noted that the moving wire contacts the drum 16 at one side of verticalaxis y and leaves the surface of drum 16 nearly 270 thereafter. As in FIG. 1, the moving wire W passes through the window 22 and over the insulated drum Jill. The wire W then again contacts and travels around the surface of drum 16 through an angle of approximately 270 and exits in a line substantially parallel with the line of entrance. The overlapping portion of the wire W in contact with the pe ripheral surface of the drum 16 is substantially 180 as is illustrated in FIGS. 10: and 4. It is within the contemplation of the invention to provide other values for angle a by proper winding of the moving wire W around the drum 16.

A preferred embodiment of the present invention as described, includes a means for inducing the heating current into a conductive section of moving wire in the form of a loop around two spaced drums. In accordance with a further aspect of the present invention, the heating current may be induced into a conductive section of the moving wire by brushes in contact with spaced guide means for the continuously moving wire. One of such embodiments is disclosed in. FIG. 5 wherein a pair of guide means, such as drums 7t), '72, contact the longitudinally moving wire W at spaced points; and the drums are rotatably mounted so that there is no sliding movement between the wire and the drums. The rotatable drums '70, 72 are each constructed in a manner similar to drum 16 shown in FIG. 1 and are comprised 70 so that electrical contact may be made with separate a conductive bars 74 by the separate brushes; In a similar manner, drum 72 is provided with spaced brushes 90, 92, 94 and '96. An electrical source schematically represented at tilt) is connected to the individual brushes.

so that current passes through the brushes, through the conductive bars in engagement with the brushes and then into the moving wire W. As so far explained, the major portion of the heating current created by source 104) would pass from brush 86 through the wire W to brush 90 because of the lesser amount of'impedance in the length of wire between the conductive bars opposite these brushes. The wire is represented in FIG. 5 as being a resistance element having a resistance Rt between the drums and smaller resistances R adjacent the separate conductive bars on the spaced drums and, of course, the resistance Rt is lesser than the resistance Rt plus one or more resistances R. To prevent the high heating current from flowing in the low resistance section of wire represented by Rt extending between brushes 86 and 90, a plurality of impedances El -R4 are placed within the circuits leading to the individual brushes. The impedances increase from R1 to R4 in a ratio quite similar to the manner in which the resistance R increases from brush 86 to brush 80. By providing the impedances within the circuits leading to the individual brushes, the current is divided between these brushes to reduce the transfer current at any one brush.

Referring to FIG. 6, a practical apparatus is disclosed for accomplishing the features shown in FIG. 5. The drums 70 and 72 are in sliding engagement with the resistance elements 110, 112 which are connected at their opposite ends through an electrical source such as a battery 114. The resistance of wires 110 and 112 increase substantially proportional to the increased resistance of the length of wire in contact with the conductive bars 74 in engagement with the resistance wires. In this manner, the impedance relationship disclosed in FIG. 5 is conveniently obtained.

The invention has been described in connection with a number of structural embodiments; however, it is not intended that the invention should be limited thereto and it is appreciated that various modifications may be made in these embodiments without departing from the spirit and scope of the invention as defined in the appended claims.

Having thus described my invention, I claim:

1. A heating apparatus for continuously heating a moving wire, comprising in combination: first and second rotatably mounted drums spaced from each other, said moving Wire forming a conductive loop between said spaced drums, said conductive loop comprising a first portion of said wire wrapped partially around said first drum, a second portion of said wire extending between said drums and wrapped around said second drum and a third portion of said wire wrapped partially around said first drum, a transformer comprising a primary winding and a core, said core having an opening, said second portion of said wire extending through said core opening, said first drum comprising a plurality of conductive elements on the periphery of said first drum and extending in a direction substantially perpendicular to said first and third portions of said wire and substantially parallel to the axis of rotation of said first drum, means for insulating said elements one from the other, said second drum having a high electrical resistivity peripheral portion in contact with said second portion of said moving wire, and said first and third portions of said wire being in overlapping relationship with respect to each other on said first drum.

2. A heating device for continuously heating a moving wire, comprising in combination: first and second rotatably mounted drums spaced from each other, said wire moving between said drums and forming a conductive section of wire between said drums, each of said drums comprising a plurality of conductive elements on the periphery of said drums and extending in a direction substantially perpendicular to said wire and substantially parallel to the axis of rotation of the drum on which they are located, a plurality of conductive elements of each drum being in contact with said wire at all times, a set of brushes engaging each of said drums and contacting said elements with each set including a plurality of individual brushes spaced along the periphery of each drum from a position remote of the other drum to a position adjacent to the other drum, each of said brushes in each set having an impedance balancing means with the impedance of each balancing means progressively increasing from the remote brushes to adjacent brushes, conductive means for electrically connecting said sets of brushes, and means for causing a current flow between said brushes and through said section of wire.

3. A heating device for continuously heating a moving wire, comprising in combination: first and second rotatably mounted drums spaced from each other, said wire moving between said drums and forming a conductive section of wire between said drums, each of said drums comprising a plurality of conductive elements on the periphery of said drums and extending in a direction substantially perpendicular to said Wire and substantially parallel to the axis of rotation of the drum on which they are located, a plurality of conductive elements of each drum being in contact with said wire at all times, a brush engaging each of said drums and contacting said elements, said brush of each drum extending from a position remote of the other drum to a position adjacent to the other drum, each of said brushes having an impedance per length of brush substantially equal to the impedance per length of wire in contact with the same elements as said brushes, conductive means for electrically connecting the remote ends of each brush, and means for causing a current flow between said brushes and through said wire section.

References Cited by the Examiner UNITED STATES PATENTS 2,364,623 12/44 Denneen et al. 219-1059 2,502,770 4/50 Watson t21910.61 X 2,675,461 4/54 Leonard 219--10.61 X 3,008,026 11/61 Kennedy 219--l0.61 3,103,571 9/63 Axelsson 21910.61

RICHARD M. WOOD, Primary Examiner.

Claims (1)

1. 3. A HEATING DEVICE FOR CONTINUOUSLY HEATING A MOVING WIRE, COMPRISING IN COMBINATION: FIRST AND SECOND ROTATABLY MOUNTED DRUMS SPACED FROM EACH OTHER, SAID WIRE MOVING BETWEEN SAID DRUMS AND FORMING A CONDUCTIVE SECTION OF WIRE BETWEEN SAID DRUMS, EACH OF SAID DRUMS COMPRISING A PLURALITY OF CONDUCTIVE ELEMENTS ON THE PERIPHERY OF SAID DRUMS AND EXTENDING IN A DIRECTION SUBSTANTIALLY PERPENDICULAR TO SAID WIRE AND SUBSTANTIALLY PARALLEL TO THE AXIS OF ROTATION OF THE DRUM ON WHICH THEY ARE LOCATED, A PLURALITY OF CONDUCTIVE ELEMENTS OF EACH DRUM BEING IN CONTACT WITH SAID WIRE AT ALL TIMES, A BRUSH ENGAGING EACH OF SAID DRUMS AND CONTACTING SAID ELEMENTS, SAID BRUSH OF EACH DRUM EXTENDING FROM A POSITION REMOTE OF THE OTHER DRUM TO A POSITION ADJACENT TO THE OTHER DRUM, EACH OF SAID BRUSHES HAVING AN IMPEDANCE PER LENGTH OF BRUSH SUBSTANTIALLY EQUAL TO THE IMPEDANCE PER LENGTH OF WIRE IN CONTACT WITH THE SAME ELEMENTS AS SAID BRUSHES, CONDUCTIVE MEANS FOR ELECTRICALLY CONNECTING THE REMOTE ENDS OF EACH BRUSH, AND MEANS FOR CAUSING A CURRENT FLOW BETWEEN SAID BRUSHES AND THROUGH SAID WIRE SECTION.

Images