US2406554A - Heating metal bodies preparatory to hot working - Google Patents

Description

,f Aug. 27, 1946. K. MARSH HEATING METAL BODIES PREPARATORY TO HOT WORKING'l Filed nec'. '28, 194s #ww/@91M ATTORNEY Patented Aug. 27, 1946 HEATING METAL BODIES PREPARATORY TO HOT WORKING Kirtland Marsh, Pittsburgh, Pa., assignor to Aluminum Company of America, Pittsburgh, Pa., a corporation of Pennsylvania Application December 28, 1943, Serial No. 515,938

.This invention relates to a process for heat conditioning metal bodies of considerable mass, particularly ingots, for hot working, and it is hereinafter described in connection with the treatment of ingots preparatory to hot rolling or breakdown. Y

To sustain a high output schedule, a common practice of processing ingots to bring them into the desired metallurgical and thermal conditionsV for hot rolling 'is carried out by the well known "soaking pit procedure. This practice has various known deficiencies and disadvantages; Among them may be mentioned the individual handling of each ingot for removal from the heating or combustion zone, the fluctuation in pit temperature and waste of heat and fuel upon removal of the covers to expose an ingot ywhich it is desired to remove with consequent deleterious effecten other ingots in the same heat zone or pit but not yet removed, and especiallythe lack of temperature equilibrium or uniformity in all parts of the ingots when they reach the mill for rolling, particularly as between the interior and exterior portions thereof.

Itis among the objectives of this invention to provide a process which overcomes the foregoingand other difficulties, which eliminates individual` handling of the ingots being processed, which results in maximum economy in the employment of heat and maximum conservation of heat, and by which treated or processed ingots of more uniform thermal and metallurgical conditions are produced for hot working under such predetermined schedule as may be desired and atpmaterially lower costs. A further object of the invention is to provide an improved process whereby a large number or multiplicity of ingots may be heated up to and held at a predetermined preheating and soaking temperature above the working temperature to condition the same metallurgically, and thereafter rapidly vbringing the ingots to hot working or rolling temperature, effectively establishing temperature equilibrium, throughout each ingot in readiness for rolling, and holding them indefinitely in ready condition for delivery to the mill one by one as needed. Other objects and advantages will become apparent from the following description of the invention.

By way of example, the accompanying draw- 6 Claims. (Cl. 26S-52) inglshows diagrammatically certain apparatus mally treated, and Fig.r 2 illustrating a second y furnace equipment in. which a redistributed batch of ingots is further processed.

The nature of the preferred embodiment of the present invention may be described in general terms as including the steps of forming a multiple layer, stack or pile of the bodies or ingots to be treated with a plurality of ingots in each layer or row, introducing one or more of the piles into a soaking-preheating chamber held at a predetermined temperature above working temperature, subsequently` removing a pile o-f heated ingots from said chamber, transferring all the ingots in the pile, in layers or in units, successively to a second furnace, and introducing the said layers of ingots into said second furnace, utilizing residual heat in the ngots while they are in the second furnace to cause equalization of temperature throughout each ingot rapidly, and advancing the ingots through the second furnace intermittently to effect discharge thereof for delivery to the mill as needed. The temperatures employed in each of the respective furnace chambers will depend upon the characteristics of the metal being treated, and specie.` temperatures need not be here mentioned as they are well known to the metallurgist, and for-a given kind of metal the usual temperatures required to effect the desired results will be utilized. Some bodies of alloyed metals prior to initial hot working thereof require heating to a temperature above hot working temperature and soaking at that elevated temperaturefor a substantial length of time to improve the metallurgical characteristics, in addition to rendering the metal readily workable. Among the charf acteristicsY so improved by heating and soaking isl that of structural uniformity, i. e., the'heating causes some diffusion of alloy ingredients in the base metal with consequent "diminution in size of brittle constituents that interfere with properA Working of the bodies. will bev particularly advantageous for thevtreatment of metal bodies or ingots of such metal, aluminum alloys being a particular example.

` In one mode of practicing the invention, and withreference tothe drawing, a horizontal furnace 8 is provided, into the heating chamber of which the ingots are charged and there heated up to and held at a desired high temperature. The construction of this furnace may take any well known form. Preferably, it will have a heat, ing chamber 9, spaced from the walls of the furnace-and adapted forforced circulation of the furnace atmosphere by means of `suitable` cir- The invention p Vof each ingot and the average or mean temperature of al1 the ingots are caused to be brought into a greater degree of uniformity, which manifests itself in the working operation subsequently performed. In the processing of metal bodies or ingots of certain kinds of metal, it may be advantageous to provide a non-oxidizing or inert atmosphere in the holding furnace I5 if desired.

It is preferred to discharge all of the ingots from the holding furnace I5 before introducing another batch thereinto, so that temperature conditions therein can be more readily maintained uniform and fluctuations and heat losses kept to a minimum, and crosswise ingot disposition enables a furnace and its conveyor mechanism of greatly simplied construction to be employed, Accordingly, it is preferred to provide at least an additional holding furnace 25, in all respects a duplicate of the furnace I5, arranged to'discharge its ingots to the runway or roller table 22, so that uninterrupted iiow of ingots to the mill can be accomplished. This furnace 25 will be charged with an entire pile or batch of ingots from the soaking-preheating furnace 8 while the mill is being supplied with ingots from the furnace I5. After the supply of ingots is exhausted from furnace I5 delivery of fully processed ingots from the furnace 25 is effected. A suiiicient number of furnaces 8 will be used to supply batches of ingots to the holding furnaces I5 and 25, alternately, to meet the predetermined schedule or requirement of the mill. The discharge of ingots from the respective holding furnaces may be under control of the mill operator. Since each of the ingots as discharged from one of the holding furnaces is in required rolling condition thermally and discharge thereof is effected only as needed at the mill, there is eliminated by this invention that interdependency between the operation of themill and the operation of associated pits extant in prior practices.

What is claimed is:

1. A process for heat conditioning cast metal bodies of an aluminum alloy and the like for initial working at a given hot working temperature comprising introducingv simultaneously into a heating furnace a multiplicity of said bodies removing said bodies from said furnace simulltaneously after bringing them to and maintaining them at a temperature greater than said working temperature to effect metallurgical oonditioning thereof, cooling said removed bodies in air, introducing all of said removed bodies into a second furnace in side by side relation at an average temperature about equal to said working temperature to check cooling thereof, effecting equalization of the temperature of said bodies in said second furnace at substantially said working temperature, and moving said bodies through said second furnace to discharge them one at a time.

2. The method of treating cast metal alloy bodies preparatory to initial hot working at a given hot working'temperature whichcomprises, introducing a .batch of said bodies intoL a furnace heated to a temperature above said working` 17em-` perature, heating and soaking said bodies in said f.urnace,'withdrawing the batchv of heated bodies from said furnace, charging all'A the bodies constituting said batch in spaced relationship intoLa second furnace normally maintained substantially at said working temperature, for subsequentv discharge therefrom'oneat atime, as needed for working, allthe bodiesin said-second furnace being held substantially at said working temperature until discharged therefrom, and imparting intermittent movement to the said bodies in said second furnace to discharge one of them.

3. The method of treating cast metal alloy bodies preparatory to initial hot working at a given hot working temperature which comprises, introducing a batch of said bodies into a furnace heated to a temperature above said working temperature, heating and soaking said bodies in said furnace, withdrawing the batch of heated bodies from said furnace, charging all the bodies `constituting said batch in spaced relationship into a second furnace normally maintained substantially at said working temperature, for subsequent discharge therefrom one at a time, as needed for working, all the bodies in said second furnace being held substantially at said Working temperature until discharged therefrom, imparting intermittent movement to the said bodies in said second furnace to discharge one of them, similarly charging all the heated bodies of another batch into a third furnace identical to said secondfurnace during discharge of bodies from the latter, and effecting discharge of bodies from said third furnace after al1 the bodies have been discharged from said second furnace.

4. The method of preparing cast metal alloy bodies for initial working at a given hot Working temperature which comprises, introducing a load consisting of a multiplicity of said bodies arranged in spaced piled relation into a furnace, heating said load to and soaking the same at a temperature higher than said working temperature to effect metallurgical conditioning thereof, removing the load after soaking is completed, effecting rearrangement of the said bodies of said load and introduction thereof into a second furnace without reducing the mean temperature of said bodies materially below said working temperature, equalizing the temperature of said bodies in said second furnace, prior to discharge from said second furnace, and imparting intermittent movement to said bodies in said second furnace to discharge them only as needed for Working.

5. The method of preparing cast metal alloy bodies for initial working at a given hot working temperature which comprises, introducing a load consisting of a multiplicity of said bodies arranged in spaced piled relation into a furnace,

heating said load to and soaking the same at a temperature higher than said working temperature to effect metallurgical conditioning thereof, removing the load after soaking is completed, effecting rearrangement of said bodies of said load and introduction thereof into a second furnace without reducing the mean temperature of said bodies materially below said working temperature, equalizing the temperature of said bodies in said second furnace primarily by the residual heat in each of them, prior to discharge from said second furnace, and imparting intermitteilt `novement tojsaid .bodies Lin said second l furnaoe ftov :discharge 'them only as :needed Afor' working` 6. process :for `heat oondti'oningiingots cony8 perature to Yeiect metallurgical conditioning thereof, ivremoving Lthe .pi-'1e :of lingots .from .said furnace after soaking is completed, removing the layers voi'the fpil'e 1in Asuccession, and introducing themrnto *a second iurnace in a single'rlayeriin spaced irela'tionship, maintaining ysaidiingots .in f

said second .furnace `at 4a. temperature substan tialiy equal to zsaidrworking temperature, and' Y moving said ingots through said second furnace 1-0k to disohancge :them one ata time.

Images