US2415027A - Apparatus for conducting electricity through lengths of continuously advancing electrically conductive material to heat the same - Google Patents

Description

Jan. '28. 1947.

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S 5mm mi vTSM.v ZWEh .CMS F 3 OT m LMH AMO HMT 3 HLW TwRl RUM l 0 ORA. WHM2 T E MYNM.. T Te mmv. CS ommd TNe BOOM .EC.F L PE G. APPARATUS FOR CONDUCTING ADVANCING ELECTRICALLY GEORGE P. BOSOMWORTH Anp EDWARD 5.HUFFMAN Jan. 28, 1947. G. P. BosoMwoR'rH ETAL 2,415,027 APPARATUS FOR GONDUCTING ELECTRICITY THROUGH LENGTHS OF CONTINUOUSLY ADVANCING ELECTRIGALLY CONDUCTIVE MATERIAL TO HEAT-THE SAME vFiled Sept. 24, 1943 3 Sheets-Sheet 2 gmac/whom GEORGE P. DOSOMWOQTH Ano EVWAQD HUFFMAN Jan. 28. 1947. G. P. BosoMwoR-rH ETAL. 2,415,027

APPARATUS FOR CONDUCTING ELECTRICITY THROUGH LENGTHS 0F CONTINUOUSLY ADVANCING ELECTRICALLY CONDUCTIVE MATERIAL TO HEAT THE SAME Filed Sept. 24, '1943 3 Sheets-Sheet 3 3 rvua/wtO/b GEORGE P DOSOMWORTH' AN D EDWARD B, HUP'FMAN @2M ,(f/Wffffw Patented Jan. 28, 1947 TNUUSLY ADVANCING ELECTRCALLY CNDUCTIVE MATERIAL TO HEAT THE SAME George P. Bosomworth and Edward B. Huffman, Akron, Ohio, assignors to The Firestone Tire & Rubber Company, Akron, Ohio, a corporation of k Ohio Application September 24, 194,3,Seral No. 503,726

l This case concerns an invention in a mechanism for heating or drying continuous or substantially continuous lengths of current conducting material. More speciiically, the invention involves a mechanism for heating or drying cable. According to previous practice, cable has been dried by conducting it through a heating chamber and blowing a current of air through the chamber and about the cable, but that practice is generally unsatisfactory in that the inner part of the cable is not dried, or if sufficient time is taken to dry that part of the cable .the progress of the cable through the drier must be extremely slow. The method and mechanism herein descibed are adapted to dry a cable or other conducting type material while the same is being progressed rather rapidly and by suitably regulating the process in a manner hereinafter described, all parts of the cable will be dried without excessively heating the outside of the cable and without prolonging the period of time it is subjected to the drying action merely for the purpose of accomplishing drying at the inner. strands or core.

While any type of cable or other conducting material may be dried by the mechanism involved, the invention is described with respect to drying cable after it has been plated or tinned whereupon itis generally washed at some point in the process. The cable may then be covered with insulating material or may have rubber bonded thereto. Such bonding with rubber is practiced in the manufacture of treads for track type vehicles in which steel cables are first plated and thereafter limbedded in the rubber ,tread of the track which is actually bonded to the metal of the cable. The washing occurs at some point after one'of the plating operations and since the material must be clean before proper bonding can be realized, the Washing is done just before the cable and rubber are bonded and thus thorough drying during progress of the cable in the continuous process is essential. The cable must be dried without excessively heating the same since it is quite possible that some effect on the plat- -ing might be experienced if thatwere done. V

While only one section of a complete machine adapted to dry cable according to thepresent invention is described here, it is to be understood that the machine may be constructed so as to have as many sections as desired and therefore t act upon many cables simultaneously.v One of the objects in the development of this type of drying means has been that of rendering the mechanism safe, and, to 'that end', a low voltage,

2 claims. (ci. 21e-11) high amperage current is employed. The externalwiring is as short as possible to eliminate losses, thereby making the process economical. Each individual cable is drawn ythrough the machine by an independently driven traction means which preferably comprises an electric motor geared to a take-up and controlled as usual to maintain the cable taut and wind it on a drum. Each of these units has a Zero-speed switch which Lfunctions to control .the drying current flowing in the cable so that whenever it is stopped, that current will be shutoff until the cable is again started through the machine. Actually, this zerofspeed control operates to turn on the drying current after the driving motor has picked upa pre-determined number of revolutions per minute; lalso shuts off the current when that motor speed drops below a pre-determined number of revolutions per minute.

The drying current is brought to the machine through a variable resistance and is transformed by any convenient type kof transformer, for eX- ample, an iron core type transformer having its secondary side connected to the cable or other material to be dried, which material is so guided and the wiring connections thereto so designed that the drying current is confined to a predetermined portion or zone in the advancing cable. This secondary side of the transformer is at re1- atively low voltage, for example, 6 to 14 volts. There are a plurality of taps at'tlie secondary side of ythe transformer and by employing different ones of these, the yvoltage and current characteristics used for drying may be varied.

The cable is guided over trolleys, two of which are Xed at the .top oi the machine frame while the other is adjustablysupported, ene purpose thereof being to `'vary' .the lengthA of cable in which the dryingcurrent is allowed to flow. This movable trolley is the means through which current is initially introduced to the cable and forms a sort of dividing point in that part or length of the cable 'beingdried One portion of that part or length is shorterl than the opposite whereby a greater flow of current is permitted in the shortside. than in the longer side. Incidentally,.the shorter side is that in which the initial drying isaccomplished whereas the second part of the cable to be dried and which has a lower rate of current flow constitutes the second stage of drying, however, for other purposes the opposite arrangement may be more desirable. rhe relative lengths of these two stages as well as the total length of cable in the drying zone may be varied.

A system of bus bars is employed by means of which the fixed trolleys are interconnected and through which current flow is completed back to the secondary side of the transformer. These fixed trolleys are also grounded to the frame. This system of wiring serves to oder as little electrical resistance as possible so that power loss is kept at a minimum.g Drying of .the cableY due to heat rise caused by resistance therein is thus accomplished with a minimum of electric `power consumption.

By dividing the current now between two portions of the current ,carrying part of the advancing cable Vand by having the initial portion oi' that cable shorter than the second part'in which current is flowing, the temperature. of the cable is raised very quickly as it enters the heating zone. However, the outside or surface portion of the cable is heated much more quickly than the center or core. To heat the entire cable rapidly, the current necessary ,could not be maintained for -long as it would very likely increase the temperature above safe limits.' To eliminate any unevenness in heating, the iirst heating stage or zone is followed by another during which less but sucient current flows to maintain desired temperature and permit uniform distribution of heat and drying effect throughout the cable. The outside part of the cable is actually dried during this'initial stage or iirstV zone of its travel through the machine.v In'the second zone the reduced iiow 'of current andfgreater resistance is only sufcient tomaintain temperature, that is, the temperature at the outside of the cable is not raised substantially beyond that point to which it was raised in the initial Zone. However, due to the fact that travel through this second zone Ais longer than the first and since the outside of 'the cableV is substantially dry at its maximum temperature, the center or core ,of the cable willv be dried in that time, being Vaffected by bothnthe resistance to the iicw of current-and also by conduction of heat from the outside inwardly to the core.

The invention willbe further described by reference to one specific embodiment of the same asV illustrated i'n the accompanying figures of drawings in which:

Fig. l is a plan View of a section of the drying machine, this section being adapted to accommcdate two separate cables;

' Fig. 2 is an end elevation of the machine showing means for'guiding the cable, one of the transformers-and wiring andthe zero-speed switches;

FigyB is an elevation at the back of the machine showing zero-speed switches;

Fig. 4 is a detail ofbne of the trolleys for 'guiding cable through the machine and by means of which current is conducted to or from the cable; n Y

l'ig.V 5 is `a section showing the zero-speed switches and drive for the same; and

Fig. 6 is a Adiagrammatic view illustrating in a more or less elementary way the wiring incidental l to drying a single cable.

New lreferring to Figs. l, 2 and 3, Vtlfie'machine is built up on a frame work structure which includes posts it and Hand cross members I2 and-i3, also longitudinallmembers Ml and l at the tcp and. i5 at the bottom. There is another longitudinal member at the opposite side from the member `i'r'although that does not show in any of the 'gures. It is to be understood that the frame work may beas longr as desired or as is necessary for accommodating the particular number of cables or other current carrying elements which are to be progressed through the machine. For each cable, one of which is indicated by a dot-and-dash line Il, there is a trolley it at what will be termed the front or" the machine, an

adjustable trolley l andthen another trolley 2li at the back side of the machine, these trolleys preferably being identical in construction. The trolleys l vand 253 are iixed in position at the top of the machine and serve as guiding means for the cable, also are grounded to the frame by means of wires 2l and 22.

The trolley i@ is rendered bodily movable to and from the trolleys I3 and 29 since it is mounted to be moved vertically along the post li. This trolley which is rotatable within a harp 23 is lined to an insulating board 2li made of Transito or other material suitable for the purpose, and this insulating board is attached to brackets 25 and 2t which clamp to the post l! and thus may be locked in any desired position on that post. In actual practice the board 2li extends the entire length of the frame and a plurality of bracket-s 25 and will be unclamped from their respective posts I l in the event the trolleys le are to be adjusted, the entire `assembly will be moved to a desired position and then all will be clamped by tightening the clamping means, the. same not being illustrated in detail in this case. Dotted line positions indicate more or less the extremes to which the movable trolleys may be adjusted for a purpose-hereinafter more definitely to be described.

Referring to Fig. ll, one of the trolleys such as le is illustrated being freely rotatable upon an axle 2'! vpassing through the harp 23, that harp being bolted Aor otherwise suitably attached to the board 2d' in the event the unit is to be insulated from the fra-me, but in the `case of trolleys such las IS and 2G, being attached to any suitable bracket welded or otherwise'fixed at the top port'ion'ofk the Vframe structure. Current connection to the'trolleys isfby a wire soldered to a Contact clip 2?. which is slipped over the aXle 21 as the unitis assembled and which is pressed against the end ofthe hub of the trolley by a contact spring 29. The cable l? is guided within a small groove 35 within a lar-ger groove with which the trolley has originally been provided. Depending upon the size -cf cable to be handled 'and other factors, the diameter and general characteristics of these trolleys may vary. Generally speaking, they are similar to trolleys used for taking current from trolley wires as 'in street cars or other railway equipment.

At the back of the machine'two angle irons 3l and 32 extend the length of the Aframe.work-and carry supports for the zero-speedswitches, yEach switch is driven by the moving cable asthe same passes about a sheave 33 grooved Ato receive it. As shown Vmore Vclearly in Fig. 5, a gro-cved'sheave 33 is keyed to one end of-a shaft et rotatable on ball bearings 35 and 35 in the bearing closures lj'and 38. These Iclosures are bolted to ahorizontallyY disposed shelf 3S extending youtwardly from vertical supports it and il which are welded or otherwise attached to the angle irons. 'Each switch 42 is bolted lto the lower side of the horizontal shelf 3% and is driven by the rotation of shaft 34 under influence of the moving cable and through gearing including pinion i3 and-gear Ml. The pinion 33 is pinned to the end of the motor shaft and gear lid is keyed to shaft 3&3. y

The zero-speed switches function to controlthe heating ordrying current: so that -Whenltheicable stops or slows down to a point where the switch rotates at about -40 R. P. M. the current is shut off. Alternatively, as speed builds up, the current is again caused to flow as the zero-speed switch rotor reaches about 50 R. P, lVI. Of course, these speeds are adjustable as desired. rlhis prevents overheating the cable and also makes it impossible to draw cable through the machine when drying current is not flowing, that being something which would lead to difficulties since undried cable might then be subjected to a bonding step, and, of course, the wet cable would not be properly bonded to the rubber.

A series of bus bars 45 are connected across between the frame members I4 and I5, while bus bar 46 extends lengthwise of the frame and connects to each one of the transverse bars 45. The trolleys I8 and 20 are actually grounded to the frame through these bus bars by connection of the short cables 2l and 22, The bus bars are not insulated from the frame, but attach directly thereto.

The secondary side of the transformer is connected by means of a conductor 41 to the trolley I9, that conductor being soldered to a clip such as the clip 28, Fig. 4, so that the current is carried through the trolley Wheel and then to the cable to be dried since that cable is in contact with the wheel. The current divides at that particular point part flowing through the cable eX- tending from the trolley I3 to trolley I9, the other .part going to that length of the cable which passes from trolley I9 up to and over trolley 2i).

The amount, of current passing through these portions of cable of unequal length varies inversely as the resistances therein. By moving the trolley I9 as before described it is possible to lengthen or shorten the entire amount of cable in which current ows and also to vary the relative length of the two parts of the cable. A second conductor 48 attaches to the bus bar il@ and that completes the circuit back to the transformer. The bus bars I5 and 46 are of copper and are designed to set up a minimum of resistance so thatl practically all the current being used is employed to overcome resistance in the cable itself and therefore for heating purposes.

' The grounding of the trolleys I8 and 2B to the frame also decreases the resistance in the entire system thereby making it possible to use very little current and especially, to obtain heating effect in the cable from as great a proportion of the current as possible. The secondary side of the transformer is also grounded to the machine frame.

In actual operation of the drier the resistance in that part of the cable moving between trolley I8 and trolley I9 is less than in that part between trolleys I9 and 2li. rlhe resistance in the rst part is considerably less than in the second part and with the voltage and amperage of the current available allows that rst length of ,cable to become heated very quickly. However, that cable is heated at the surface, .or strands close to the surface are heated rst, while those at the core are not heated to the same extent so that duced in it during its travel in the lrst pathway. However, since the pathway'is longer and while the outside of the cable remains at substantially constant temperature, the inside will be brought to that same temperature .by conduction of the heat from the outside toward the inside with accompanying drying at the inside. For different conditions such as variations in size, material from which the cable is made and other factors, the pathway through which it passes for drying may be lengthened or otherwise altered so as to accomplish the drying at as great a speed as possible, yet assuring that the cable will be completely dried outside and also at the core.

Of course, the cable or other material to be dried is continuously being ladvanced or drawn through the machine so that the description here of what is happening to the cable in the first or second stages or zones of drying may be considered as applying to an incremental length of cable as it passes through those Zones.

Now referring to Fig. 6, the cable Il is shown passing over trolley IS, around Linder trolley IS and then over the third trolley 2li. The trolleys i8 and 26 are connected by the bus bar 65 and each of the trolleys is grounded as at 49. An iron core type transformer 50 has a primary winding 5 I, current being supplied to that primary Winding through a variable resistance 52. The secondary side of the transformer comprises a secondary winding 53 and a series of taps 54, there being ive shown here although that number may be varied according to requirements. The secondary side of the transformer is grounded at 555. Each of these taps allows current to be drawn from the secondary side of the transformer, said current being of differing voltages according to the particular tap used. For example, in one machine having a supply of current from a 440 volt- 60 cycle- 3 phase line, current may be transformed so as to make available for the drying process a current having from 6 to 14 volts and varying from to 180 amperes. While S-phase current is employed, each of the individual sections, that is, each transformer in a complete multi-section frame functions as a single phase circuit. |The bus bar 46 runs lengthwise of the frame connecting to each transverse bus bar 4S and a conductor 48 is shown running from that bus bar 45 down to the return side of the secondary winding.

As actually constructed the wiring and controls for the entire unit pass through a rather elaborate switchboard and there are several safety devices, warning lights, etc., but those have not been illustrated here since they do not appear essential to a description of the invention itself. The drying of cable has been referred to by way of example, but it is to be understood that the invention is applicable to the drying of any material which may be heated due to its resistance to flow of current and which may be easily progressed through the machine at the desired speed. This method of drying and the mechanism are particularly adapted to use when the drying is performed in conjunction with other processes on the material and when it is desired that the drying be done continuously and in synchronism with these other processes.

Alternating current is preferably to be employed, but it is within the invention as originally conceived to employ direct current in the event alternating current is not available. The use of low voltage renders the entire mechanism comparatively safe and since control of the heating effect makes it unnecessary to resort to higher temperatures, the drying is carried on Without any adverse eect upon the plating o the cable.

In some instances it may be desirable to divide the cable which is being dried into more than two zones or portions as herein illustrated, For example, there may be two or more movable 'trolleys such as the trolley l@ and thus the drying may be divided into more stages so that in the first temperature may be raised to a maximum very quickly, in the second stage drying may be carried through toward the center oi the material and the last stage may be one in which temperature at the outside is maintained' while the core is dried asy heat is conducted through to the center and the entire cable or other ma terial soaked in heat.

The invention may take varied forms and may be employed for many purposes other than those particularly referred to here without from the scope of the same as originally conceived and as expressed in the appended claims.

We claim:

1. Mechanism for drying a substantially continuous length of current Conducting material while advancing said material at a uniform rate, including in combination, a frame comprising upright posts, top cross members and top and bottom longitudinal members, guide means for said material, said guide means comprising two ixed and one adjustable trolley, one of said fixed trolleys being mounted on the iront portion and the other on the rear portion of said frame, said adjustable trolley being mounted intermediate the Xed trolleys relative to the path of travel of said current conducting material between said fixed trolleys, said adjustable trolley being insulated from said frame and being mounted upon a board which in turn is mounted upon brackets clamped to a said upright post by releasaole clamps, said clamps when released being slidably adjustable in a direction transversely to a straight line connecting said xed trolleys land may b clamped in any selectedpositon within the over Which the clamps are slidably adjustn1 said upright post, a source of low voltage, amperage current, consisting of a transioriner mounted and grounded on said frame, a current connection from said source to the movable trolley consisting of a wire extending from said source to the aXle of the movable trolley, said fixed trolleys being conductors and being grounded on said frame through which frame a circuit is completed back to said source.

2. Mechanism for drying a substantially continuous length of current conducting material while advancing said material at a uniform rate, including in combination, a frame guide means for said material, said guide means comprising two ixed and one adjustable trolley, one of said fixed trolleys being mounted on the iront portion and the other on the rear portion of said frame, said adjustable trolley being mounted intermediate the fixed trolleys relative to the path of travel of said material being dried between said Xed trolleys, said adjustable trolley being insulated from said frame and being slidably adjustable in a direction transversely to a Straight line between said fixed trolleys may be clamped in any selected position Within the range over which the clamps are slidable on the Jframe, a source of low voltage, high amperage current, including a transformer mounted and grounded on said frame, a current connection from :aid source to the movable trolley, said fixed trolleys being conductors and being grounded on said frame through which frame a circuit is coinpleted back to said source from each of the said xed trolleys.

GEORGE P. EOSOMVVORTH. EDV/'ARD B. HUFFDAN.

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