Патент USA US2407120код для вставки
Sept. 3, 1946. G. P. wlLsoN I 2,407,120 IP PROCESS ING Fv‘iled May 22, 1944 ‘ INVENTOR. ' G'OIderP W801: BY i 1 2150mm? Patented Sept. 3, 1946 2,407,120 UNITED STATES PATENT OFFICE 2,407,120 STRIP PROCESSING Golder P. Wilson, Alton, Ill., assignor to Olin In dustries, Inc., a. corporation of Delaware Application May 22, 1944, Serial‘ No. 536,752 6 Claims. 1 (01. 219-13) 2 This invention relates to the heating of metal offered by such contact bars, and, in some in stances the contact parts are subject to exces strip by means of electric induction. sive wear requiring frequent replacement. It has heretofore been Well known that the heating of metal can be accomplished by electric All such prior methods and apparatus for the induction by employing the transformer principle electric induction heat-treating of metal have in which a primary coil is supplied with an alter been attended by one or more serious disadvan tages and it is an object of this invention to pro nating electric current, and the work, or metal to be heated, when placed in inductive relationship vide an improved method and apparatus over coming all such objections. with the primary coil, is heated by its resistance to the induced electric or magnetic current. Another object of this invention is to provide 10 Various methods and apparatus have been de an improved method and apparatus for the effi scribed heretofore for bringing the metal into cient and economical continuous heating of inductive relationship with the primary coil. For metal strip by electric induction. instance, in one method for treating metal strip, Another object of the invention is to provide a length of the strip was rolled up to provide a an improved. process and an eiiicient electric in ring formed of several layers of the strip and the ring was then heated by the current induced therein from a surrounding primary coil. Such methods and apparatus have the disadvantages of‘ being limited to intermittent operation, and duction furnace for economically effecting the continuous heat treatment of metal strip having either high or low electrical conductivity. in the case of very thin wide strip, the individual layers in the ring tend to become warped at the higher temperatures due to their own weight, and owing to the large cross section of the ring formed by the layers of strip, a current of very high amperage must be induced in order to bring , Still another object of the invention is to pro vide an improved process and an electric induc tion furnace suitable for the heating of a non magnetic metal such as a copper alloy in the form of strip. Other objects and advantage will become ap ~ parent from the description and accompanying drawing, in which the ?gure is a diagrammatic the ring to the effective temperature. perspective view of a metal strip treating appara In another method, the strip was continuously tus illustrating an embodiment of this invention. passed in an axial direction through a primary The above objects and advantages are accom coil, the metal being heated by the locally in- ‘ plished in accordance with this invention by- pro duced magnetic and electric eddy currents. viding a novel process and apparatus in which Such methods and apparatus have the disadvan metal strip is unwound‘ from a coil of metal strip, tage that with high conductivity non-magnetic passed through an alternating electromagnetic strip it is dii?cult to induce electrical eddy cur ?eld and again brought in contact with the coil, rents of suf?cient magnitude to bring the strip to . thus forming a secondary or complete electric an effective treating temperature. circuit from the metal strip itself, with heating According to other methods, the metal in the being effected by the resistance of the metal to form of wire, or coiled rod, was fed in the paths the current induced in the loop. of a helix around, or through, a primary coil, but Referring‘ to the drawing, the metal strip l is such methods and apparatus have among others unwound from the coil of metal strip 2, passes the disadvantage of not being suitable for use over support roll 5, through the laminated iron with wide strip, due to the di?iculty involved in core 6 with primary coil 1 having leads 8 and 9, forming such strip into a helix. passes over support roll [0, around and in con According to still another method for heating . tact with the outer layer of metal strip I in coil metal in the form of wire or strip, two such wires 45 2,, and is wound up into coil II on support roll or or strips were continuously passed in parallel reel 12 which is driven by motor l3‘. The support paths on opposite sides of a primary coil. A com roll or reel 3 for coil 2 may be coupled to a mo plete electrical circuit about the primary coil tor or drag-generator such as illustrated at 4. through the wires or strips was provided by In passing around the coil 2, the wide surface of means of contact bars having rollers on their 50 the strip I is in contact with the outer layer of ends in electrical contact with the moving wires the coil 2 and is bent around a substantial por or strips. Such methods and apparatus, in which tion of the surface of the coil 2 so that a large contact bars and the like are employed, have the area of contact is provided with a good electrical disadvantage that a portion of the induced cur connection and low amperage per square inch rent is consumed in overcoming the resistance 55 between the strip 1 and the outer layer of coil 2 2,407,120 3 to prevent arcing and burning. A complete sec ondary electric circuit is thus provided by the moving strip I around the primary coil ‘I. An alternating electric current, which may be of either high or low frequency or, for instance, 6 any of the available standard commercial fre quencies, is applied to the primary leads 8 and 4 Due to the proximity of the secondary loop and the primary coil 1 and the good electrical con nection between the strip I and the coil 2, a very high power factor may be obtained, for instance as high as 0.90 or higher. If it is desired, for in stance, to bright anneal brass, this may readily be accomplished by enclosing the furnace in a 9, and the strip is heated by the current induced housing supplied with an inert atmosphere in the in the loop. The temperature of the strip can usual manner, If no such housing is used, any be regulated either by varying the speed at which 10 oxide ?lm or discoloration, which may form on the strip travels or by varying the power sup the strip at the annealing temperature employed, plied to the primary coil ‘I, The core 6 may be -may be readily removed by passing the strip mounted on any suitable support and the rollers through an acid pickling solution. 3, 5, I0 and I2 may likewise be mounted on any In addition to annealing treatments, this in suitable support. If the rollers 3, 5 and ID are 15 vention is applicable to other heat treatments, for made of metal or other electrical conductors, care instance, it may be used for “normalizing,” must be taken to avoid providing any electrical “quenching,” and “drawing” of steel strips, for connection between them through their supports, the re?owing of tin on iron strip, for making since the induced current may then flow through copper clad steel sheets or other laminated sheet, the supports instead of being con?ned to the and the like. strip I. Such short circuiting can be avoided with The heating unit can be-made relatively small metal rolls in any of the well known ways, for and simple and sturdy in construction. The in instance, by supplying the rolls with bearings vention accordingly provides for the economical, made of an insulator or by providing separate continuous heating of metal in strip form and has supports or supports made of an insulator. It is a wide ?eld of utility without being subject to all preferred, however, to form the rolls themselves the disadvantages obtained with prior processes from an insulator. and apparatus. If desired, spray systems, such as illustrated at It is understood that the embodiments of the I4 and I5, may be employed to spray ?uid on the present invention as shown and described are only strip I for cleaning or temperature controlling illustrated and, that the scope of the invention is purposes. For instance, the spray system at I5 may be employed to cool the strip I prior to con tact with the coil 2. In operation, the portion of the strip I brought in contact with the coil 2 is preferably maintained at the same temperature as the outer layer of the coil 2, so that there will not to be limited thereby except insofar as is de ?ned in the following claims. be no tendency for the loop formed of strip I to continuously increase in size. Any other suitable means may be employed for bination which comprises an alternating electro magnetic ?eld, means for unwinding metal strip from a coil, means for advancing said strip Having thus described the invention, what is claimed and desired to secureby Letters Patent is: 1. In an electric inductionfurnace, the com supplying the alternating electromagnetic ?eld. 40 through said alternating electromagnetic ?eld, For instance, the primary induction means may consist of a primary coil ‘I wound about a leg of the core 6 outside the loop of strip, or may consist of a coreless primary coil disposed within the loop of strip. ' In accordance with this invention magnetic or and means for bringing said strip and said coil together to provide an electrical contact there between. 2. In an electric induction furnace, the com~ 45 bination which comprises a primary induction means, means for unwinding metal strip from a nonmagnetic metal of either high or low electri cal conductivity may be continuously heated in the form of ?at strip having any desired width, coil, means for advancing said strip around and in inductive relation to the primary induction means, and contacting means for bringing said Likewise, the heating may be accomplished by 50 strip and said coil together to provide an elec applying current to the primary coil of any de trical contact therebetween. sired frequency within practical limits. 3. In an electric induction furnace, the com“ When the coil 2 is completely unwound, a new bination which comprises means for unwinding coil is inserted on the roll or reel 3 and the strip metal strip from a coil thereof, means for hold is again threaded through the furnace, or if de 55 ing said moving strip out of contact with said sired, suitable stitching apparatus may be em coil, means for bringing said strip and said coil together again to provide an electrical contact ployed for fastening the end of the strip from coil 2 to the end of the strip from the new coil so therebetween, and means for inducing an electric current in the electrical loop formed by said strip that a strip is fed through the furnace without interruption. Good electrical connection between 60 and said coil. the strip I and the coil 2 is provided, since the Ll. In an electric induction furnace the com bination which comprises means for unwinding strip I and the outer layer of coil 2 are constantly metal strip from a coil thereof, means for hold~ changing their contact surface, and little or no ing said moving strip out of contact with said oxidation can take place to increase the electri cal resistance at these points of contact, The 65 coil, roller means for bringing said moving strip and said coil together again to provide an elec strip after passing over coil 2 can, if desired, be passed through a quenching or pickling tank be trical contact therebetween, and means for in ducing an electric current in the electrical loop fore being wound up again on coil II. In an formed ‘by said strip and said coil. nealing metal strip, it is desirable to obtain an nealed strip having a certain degree of hardness 70 5. In an electric induction furnace for heating metal strip the combination which comprises a and this can be readily accomplished by chang support roll for holding a coil of metal strip, ing either the speed of travel of the strip or the power input to the primary, or both, until the means for unwinding the strip from said coil, a temperature and time of treatment necessary for primary induction means, support rolls for guid the desired strip hardness is obtained. 75 ing said moving strip around and in inductive 2,407,120 6 5 relation to said primary induction means, and contacting means for bringing said moving strip and said coil together to provide an electrical con tact therebetween. 6. In an electric induction furnace for heating metal strip the combination which comprises means for supporting a coil of metal strip, means for unwinding the metal strip from said coil, a primary induction means, support rolls for guid ing said moving metal strip around and in in ductive relation to said primary induction means, roller means for bringing said strip and said coil together again after said strip has passed around said primary induction means, means for cool ing said strip before it is again contacted 'With said coil, and means for supplying an alternating electric current to said primary induction means. - GOLDER P. WILSON.