US2303983A

US2303983A - Heat treating apparatus

Info

Publication number: US2303983A
Application number: US396102A
Authority: US
Inventors: George H Brown
Original assignee: RCA Corp
Current assignee: RCA Corp
Priority date: 1941-05-31
Filing date: 1941-05-31
Publication date: 1942-12-01
Anticipated expiration: 1959-12-01

Description

1942. G. H. BROWN HEAT TREATING APPARATUS Filed May 31, 1941 2 Sheets-Sheet l lugkwkm (Zttorneg Dec. 1, 1942.

G. H. BROWN -HEAT TREATING APPARAT u Filed May 51, 1941 v g 39 J7 T IL T 77 3/ Z9 Imventor v Gwyn/553M107 Patented Dec. 1, 1942 HEAT TREATING APPARATUS George H. Brown, Haddoniield, N. J., assignor to Radio Corporation of America, a corporation of Delaware Application May 31, 1941, Serial No. 396,102

10 Claims.

This invention relates to heat treating apparatus, and more particularly to apparatus employing an electrostatic field for heating materials of high resistance, the present invention being particularly useful in connection with, although by no means limited to, the heating of rayon threads in the manufacture thereof.

Under certain circumstances, it has been found desirable to apply heat to rayon threads in the course of fabricating the threads. Th conditions under which rayon is manufactured make it rather diflicult to apply heat to the threads by conventional methods, and the primary object of my present invention is to provide an improved heating method and apparatus which will be suitable for this purpose.

More particularly, it is an object of my present invention to provide an improved method of heating a thread, wire, strip or the like of high resistance in a manner which is both simple and economical, as well as highly eflicient.

In accordance with this invention, I provide a high frequency oscillator which may be designed to generate alternating current of a frequency of the order of between ten and fifteen megacycles. Included in the oscillator are a plurality of terminal electrodes maintained at different potentials and disposed in spaced relation to each other along a predetermined path. As the rayon thread, is brought out from the sulphuric acid bath, in which the threads are solidified, they are advanced along said path successively past said terminals or electrodes and in closely spaced relation thereto so as to be capacitlvely coupled to -the electrodes. Thus, as the thread passes these electrodes, an alternating current of high frequency is caused to flow therein, and this current heats the portion of the rayon threads between the electrodes, the rayon having, of

course, been rendered conductive by the sulphuric acid. i

slightly difierent form of my invention which may be used in a system such as that shown in Figure 1,

Figure 3 is a wiring diagram corresponding to Figure 2 and showing the electrical analogues of certain parts shown structurally in Figure 2,

Figure 4 is a schematic diagram showing still another form of my invention which may be used in a system such as that shown in Figure l, and

Figure 5 is a wiring diagram corresponding to Figure 4 and showing the electrical analogues of certain parts shown structurally in Figure 4.

Referring more particularly to the drawings, wherein similar reference characters designate corresponding parts throughout, there is shown, in Fig. l, a storage tank I for the liquid viscose from which the rayon is made and a pump 3 which serves to force the liquid in the tank I through a pipe '5 which terminates in a perforated plate in the side of a tank 1 containing sulphuric acid. As the liquid material is forced through the openings in the aforementioned perforated plate, it is formed into thin threads which solidify as soon as they come in contact with i the sulphuric acid. From the tank I, the threads 9 (of which only one is shown in the drawing for the sake of simplicity) pass around a plurality of rollers H), H, I3, l5 and I1 and are fed into a cylindrical drum or tank IS on a turntable 2| which is driven by a motor 23, the thread 9 collecting in spiral fashion in the drum I9.

The roller I1 is preferably driven at a greater speed than the roller l5 whereby the thread 9 is caused to stretch between these two rollers. It is between the rollers l5 and I! that it has been found desirable to also apply heat to the stretched threads. For this purpose, I provide, according to the form of my invention shown in Fig. 1, an oscillator 2-5 which includes a pair of vacuum tubes 21 and 29 arranged in push-pull relation and a tuned tank circuit 3|, having an inductance 33 and a capacitance 34 in shunt relation. The inductance 33 constitutes the primary winding of an output transformer 35 having a secondary winding 31 in series with an inductance 39 which is tuned to the desired frequency with a capacitance 4 l.

Spaced from each other along the path 01' movement of the thread 9 between the rollers I5 and I! are three cooperating electrodes or terminals for the oscillator 25. The end terminals 43 and 45 are connected to a grounded conductive plate 41 and are therefore maintained at ground potential. Intermediate the electrodes 43 and 45 is a third electrode 49 supported on the plate 41 from which it is insulated by an insulator 5|, the electrode or terminal 49 being spaced substantially equally from each of the terminals 43 and 45. One side of the output circuit of the oscillator 25 may be connected to ground (through the terminal 45, for example) by a lead 53, and the other side of the output circuit is connected to the terminal or electrode 49 by a lead 55. The

electrodes

43, 45 and 49 are preferably V shaped in cross-section and are disposed in aligned relation with each other, the thread 9 being arranged to pass between the sides of the V's but in spaced relation to their vertices, as well as the sides thereof. Thus, it will be obvious that the conductive portion of the thread 9 is capacitively coupled to each of the

electrodes

43, 49 and 45 as it passes along them in succession.

The oscillator 25 preferably operates at a frequency of between 10 and megacycles and generates voltages which set up electric fields around the electrodes. By reason of the-capacitive coupling between the thread 9 and the several electrodes, an alternating current of correspondingly high frequency is caused to fiow in the thread 9 between the

electrodes

43 and 49 as one pair and the electrodes 45 and 49 as another pair, the current fiowing in that portion of the thread 9 between the

electrodes

43 and 49 being first in one direction (for example, in the direction of travel of the thread 9) and then in the opposite direction, and the current flowing in that portion of the thread 9 between the electrodes 45 and 49 being simultaneously first in said opposite direction and then in the direction of travel of the thread. The current fiowing in the thread 9 generates heat therein while the thread is being stretched between the rollers l5 and I1.

In Fig. 2, there is shown an oscillator which employs only two electrodes 51 and 59, the lead 53 being connected to the electrode 51 and the lead 55 being connected to the electrode 59. In all other respects, the oscillator of Fig. 2 may be similar to that shown in Fig. 1.

Fig. 3 illustrates the action of the system shown in Fig. 2. In Fig. 3, the capacitor Bl represents the capacity between the electrode 51 and the thread 9 of Fig. 2, the capacitor 63 represents the capacity between the electrode 59 andthe thread 9, and the resistance 65 represents the resistance of that portion of the thread 9 through which current flows (that is, the portion of the thread between the electrodes or terminals 51 and 59). It is due to the resistance 65 that the requisite heat is generated by the high frequency alternating current flowing in the thread 9.

Fig. 4 shows an oscillator similar to that shown in Fig. l, but included in series with the lead 55 and the middle electrode 49 is a tunable circuit constituted by an inductance 51 and a variable capacitor 69 for further controlling the operating frequency of the oscillator.

Fig. 5 shows more clearly the operation of the system of Fig. 4, the capacitor ll of Fig. 5 representing the capacity between the electrode or terminal 43 and the thread 9, the capacitor-13 representing the capacitance between the electrode or terminal 45 and the thread 9, and the capacitor 15 representing the capacitance between the intermediate electrode or terminal 49 and the thread 9. The resistance 11 shown in Fig. 5 represents the resistance of the portion of the thread 9 which is between the

electrodes

43 and 49, and the resistance 19 of Fig. 5 represents the resistance of that portion of the thread 9 which is between the electrodes and 49, it being apparent from an inspection of Fig. 5 that current will fiow in each of the resistances I1 and 19 in opposite directions.

Although I have shown and described several embodiments of my invention, it will be apparent to those skilled in the art that many other variations thereof are possible. For example, any

other suitable type of oscillator than those shown may be employed; the

electrodes

43, 45 and 49 may be of any other suitable shape than a V; any suitable number of pairs of cooperating electrodes may be employed, and so on. Also, it will undoubtedly be apparent to those skilled in the art that my invention is not necessarily limited to use in connection with the heating of rayon thread, but that it may be used equally well for heating any high resistance conductive strip, web, film, or the like, such as high resistance wire, or tape, the strip or the like being first rendered conductive where it is normally nonconductive. Since my invention is capable of a variety of expressions and uses, I desire to have it understood that I do not wish to limit myself except insofar as is made necessary by the prior art and by the spirit of the appended claims.

I claim as my invention:

1. The method of treating a strip of electroconductive material which comprises moving said strip along a predetermined path, applying to said strip capacitively a high frequency alternating current as it passes along said path whereby to effect heating thereof, and simultaneously causing said strip to stretch as it passes along at least a portion of said path.

2. The method of treating a strip of electroconductive material which comprises moving said strip along a predetermined path, establishing electric fields at spaced points along said path, causing said electric fields to vary at a high frequency, passing said strip successively through said fields to thereby cause a fiow of current in said strip from one of said fields to another of said fields to thereby heat said strip, and simultaneously causing said strip to stretch as it passes between said points.

3. The method of treating a strip of conductive material which comprises moving said strip along a predetermined path, establishing two electric fields of different polarity at spaced points along said path, causing the polarity of said fields to reverse at a high frequency, passing said strip successively through said fields to thereby cause an alternating current of high frequency to fiow in said strip between said points to thereby heat said strip, and simultaneously causing said strip to stretch as it passes between said points.

4. The method of treating a strip of electroconductive material which comprises passing said strip along a predetermined path, generating in an oscillatory circuit which has terminals at spaced points in said path a high frequency alternating current, passing said strip successively past said terminals in capacitive relation thereto whereby to generate a current in the portions of said strip between said terminals for heating said portion, and simultaneously causing said strip to stretch as it passes between said terminals.

5. The method of treating a strip of electroconductive material which comprises passing said strip along a predetermined path and in a predetermined direction, generating in an osclllatory circuit which has terminals at spaced points in said path a high frequency alternating current, passing said strip successively past said terminals in capacitive relation thereto whereby to generate in the portion of said strip between said terminals an alternating current which flows through said strip alternately in the direction of travel thereof and then in the opposite direction for heating said portion, and simultaneously causing said strip to stretch as it passes between said terminals.

6. The method of treating a strip of electroconductive material which comprises passing said strip along a predetermined path and in a predetermined direction, generating a high frequency alternating current in an oscillatory circuit which has a pair of terminals of one potential at spaced points along said path and a third terminal in said path intermediate said first named terminals at a different potential, passing said strip successively past said three terminals in capacitive relation thereto whereby to generate in the portion of said strip between one of said first named two terminals and said intermediate terminal an alternating current which fiows through said portion alternately first in said predetermined direction and then in the opposite direction and simultaneously to generate in the portion of said strip between said inter- -mediate terminal and the other of said first named two terminals an alternating current which flows through said last named strip portion alternately first in said opposite direction and then in said predetermined direction for heating both said strip portions and simultaneously causing said strip to stretch as it passes between said first named pair of terminals.

7. In a system for treating a movable conductive strip, the combination of a high irequency oscillator including a plurality of cooperatively associated terminals in spaced relation to each other along a predetermined path, means for moving said strip along said path successively past said terminals and in slightly spaced relation to said terminals whereby said strip is capacitively coupled to said terminals as it passes by them, and constitutes a current path therebetween, and means for simultaneously stretching the portion of said strip between said terminals as it moves therebetween.

8. In a system for treating a movable conductive strip, the combination of a high frequency oscillator including a pair of terminals in spaced relation to each other along a predetermined path and a third terminal in said path intermediate said two first named terminals, means for maintaining said first named two terminals at a predetermined potential, means for varying the potential of said third terminal relative to said first named two terminals at a high frequency, and means for moving said strip along said path successively past said three terminals in slightly spaced relation thereto whereby said strip is capacitively coupled to said terminals as it passes them to thereby generate in said strip alternating current for heating said strip.

9. The invention set forth in claim 7 characterized in that said terminals are constituted by substantially V-shaped electrodes and characterized further in that said electrodes and said strip are so disposed in said path that said strip passes between the sides of each of said electrodes and in proximity to the apex thereof.

10. In the method of forming rayon by coagulation of viscose material by means of an electroconductive coagulating material, the steps which comprise forming the viscose material into a thread, coagulating said thread with said conductive material whereby to render said thread electro-conductive, moving said electro-conductive thread continuously along a predetermined path, generating in an oscillatory circuit which has terminals at spaced oints in said path a high frequency alternating current, and passing said electro-conductive thread successively past said terminals in capacitive relation thereto whereby to generate in that portion of said thread which lies between said terminals at any time a current for heating said thread portion.

GEORGE H. BROWN.