Патент USA US2588142код для вставки
arch 4, i952 J. l.. MGFARLAND ET AL 2,588,141 CONTINUOUS TYPE FURNACE Filed Sept. 22, 1948 // / / // ///// É? M_ Inventor: «James L3. McFarland NOT-‘ma? B.Jovwes Their Att Orr/1 ey. 2,588,141 Patented Mar. 4, 1952 UNITED STATES> PATENT oFFlcE 2,588,141 l CONTINUOUS TYPE FURNACE James L. McFarland, Schenectady, and Norman B. Jones, Ballston Lake, N. Y., assignors to General Electric Company, a corporation of New York Application September 22, 1948, Serial No. 50,506 2 Claims. (Cl. 263-8) 1 2 , Work pieces 4 to be heated. The rollers I are 'Y driven in synchronism by a suitable driving Our invention relates to furnaces, particularly to high temperature furnaces of the type adapted for continuous operation including roller hearth means such as electric motor 5, best seen in Fig. 2, ' furnaces and the chain conveyor type. Our in vention has for its object to provide an improved furnace and furnace conveying system which fur nishes uniform heating and economical opera tion with a reasonable first cost. Heretofore, roller hearth furnaces have been limited to a practical width of a few feet, when used for high temperature Work, because of the through a suitable driving mechanism such as continuous chain 6 and sprockets 1, which Aare best seen in Fig. 3. In this particular construc tion, the corresponding rollers on the two rows of rollers are coupled together by means of a suitable external interconnecting shaft and cou pling assembly 8 so that the left row of rollers in "Fig. 2 is driven from and in synchronism with the right row which, in turn, is driven by the _ adverse effect of high temperatures on the ‘physi motor and chain and sprocket mechanism. cal strength of the rolls. Accordingly, it is a In the operation of this furnace, the elevated further object of our invention to provide roller hearth type furnaces of much greater width than 15 lcarriers or fixtures 3 supporting the Work to be present designs permit. heated 4 are brought to the furnace by a suitable conveyor 9. The door IU is opened to admit the supporting ñxtures and work to the furnace and they pass through the furnace from left to _right temperatures because of the necessity for keep ing the conveyor chain cooler than the furnace 20.. in Fig. 1. In zone l, the work is preheated, *for proper and because of the escape of heat through 1 example, to approximately 1000° F. In zone 2, the final heating takes'place and the tempera necessary openings in the furnace insulation. It ture of the work is raised, for example, to ap is therefore another object of our invention to proximately 1725° F. In zone 3 of the furnace, provide a chain conveyor type furnace, especially one of large physical size, which can be operated 2,5.. the work is cooled, for example, to approximately at high temperatures with uniform results. 1200° F. Door H is then opened and the work and the supporting fixtures are discharged onto a suit In carrying out our invention in one form we ' provide a continuous roller hearth type electric able conveyor í2 which removes them from the furnace with two parallel rows of rollers extend furnace. The work can be allowed to cool natu ing the full length of the furnace. These rollers rally after it has been removed from the furnace ' 30 Again, conventional chain conveyor furnaces do not provide uniform heating when used at high support suitable elevated carrying devices which, or it can be cooled more rapidly by an air blast or ,other suitable means (not shown) as it is be ing removed from the furnace. in turn, support the work to be heated. The rollers are recessed in the floor ofthe furnace, and the recesses are completely insulated so that there is no large heat loss. While these recesses are maintained at practically full furnace tem perature, the rollers -are comparatively short and, 35 This furnace is heated electrically by electric heaters I3 distributed throughout the furnace. However, our invention is equally applicable to furnaces heated by other conventional means, therefore, can be designed to withstand high tem such as natural or manufactured gas or oil. ' peratures without exceeding the stress limitations Furthermore, While our improved furnace has of the metal of which they are made. 'I'he rollers 40 been illustrated as employing two complete sets are driven in synchronism by a suitable external orv rows of rollers, any desired numberv of such means. . ' For a more complete understanding of our in vention, reference should be had to the attached sets or rows may be employed. By- theuse of a suitable number of rows of rollers, furnaces can be made any desired width by the use of our ín drawing which shows in Fig. 1 a side view of one 45 vention. Heretofore, roller hearth furnaces have form of our invention; Fig. 2 is a sectional view been limited to a width of approximately 81/2 feet taken along the line 2-2 of Fig. 1; and Fig. 3 when constructed for operation at 1650D F. be is a partial detailed sectional View taken along cause of the adverse effect of such a high tem the line 3-3 of Fig. 2. perature on the physical strength of the rolls, Referring to Fig. 1 of the drawing, the rollers l 50 this width being the over-all outside dimension; can be seen extending thev full length of the fur the corresponding inside Wall to wall width in the heating chamber is approximately 6 feet. At 2050° F., the present practical maximum outside The rollers l support the elevated carrying de width is approximately 5 feet, which gives an in vices or fixtures 3 which, in turn, support the 55 side Working width of approximately 30 inches. nace; Fig. 2 shows the relation of the rollers to the insulated recesses 2 in the furnace floor. 2,588,141 3 - l _ means for providing an artificial non-oxidizing reducing atmosphere utilizing such gases as hy drogen, or a mixture of hydrogen and nitrogen, or atmosphere convertor gas which is made by One modification of our invention relates to the use of rollers. similar to those already .de scribed, in completely insulated recesses in the floor of the furnace to support one or more chain conveyors. These chain conveyors are conven 5 burning suitable manufactured or natural gas with a controlled deficiency of air. Hign tem perature furnaces are sometimes used without artificial atmosphei'e, however, for some kinds of material. Our invention is suitable for applica tion to furnaces with or without artificial atmos tional in form except that they are made of special alloy steel to withstand full furnace tempera ture. They have dogs or other prolecting mem bers on them which project above the furnace floor and propel the work to be heated along the phere. floor of the furnace from the entrance to the While we have described one preferred em bodiment'of our invention along with one modifi cation, many other modifications will occur to exit. This arrangement is applicable primarily to large pipes and other similar objects which will roll tlirough the furnace when pushed by the dogs on the conveyor chains. Alternatively, 15 those skilled in the- art and it should, therefore, be understood that we intend by the appended if the material to be heated is not suitable for claims'to cover alll such modifications which fall rolling, the conveyor chains can be made of such withinthe true spirit and scope of our invention. dimensions that they support the weight of the What we claim as new and desire to secure by work 1n the furnace While they, in turn, are sup Patent of the United States is: ported by the recessed rollers. y 20 Letters 1`. A horizontally disposed furnace of the type Tile use oi sucli a cilaiii conveyor or conveyors adapted for continuous conveyor operation hav operating at ruil furnace temperature is made ing a plurality of parallel insulated recesses in practical oy the use ol the recessed supporting the ñoor of the furnace heating chamber and rollers of our invention. These rollers greatly reduce the il'lctloil oil tile chalii or ciiallls wl'ilcll, 25 extending longitudinally througii said furnace, a plurality of rollers extending transversely in turll, i‘educes trie size ol chains required to through one of said recesses, an equal number of rollers extending transversely through each of is required to withstand nign tempera the other recesses, means supported by said roll Conventional chain conveyor type iur where the chains are supported in metal 30 ers for propelling work through the furnace, means external to said heating chamber for con somewhat below the 1100i` oi the furnace, witilin practical limits lor the special alloy steel wllich tures. naces, guides necting together corresponding rollers in sep are not practical for use at high temperatures in large installations. The chains must be of arate recesses, and means external to said heat ing chamber for driving said rollers irl syncnro and the large friction load, caused by tile weight 35 nism to actuate said work propelling means. 2. A horizontally disposed furnace adaptable or tile chains themselves in the metal guides, in for continuous conveyor operation having a plu addition to the work being propelled through the rality of parallel insulated recesses in the floor of furnace, makes the chains so large that the cost the furnaceV heating chamber extending longi is prohibitive. Furthermore, on conventional chain conveyor 40 tudinally through said furnace, a plurality of rollers extending transversely through one of furnaces there usually are slots cut in the floor said recesses, an' approximately equal nuinoer of insulation t0 permit the dogs on the conveyor rollers extending transversely through each of chains to prolect through the floor and engage the other recesses, separate supporting means for the work-piece. These slots’permit the escape ofv large amounts of heat from the furnace which 45A each recess carried _on-‘said rollers extending above said furnace floor for supporting work lowers its efficiency and at the same time cause special` alloy steel to withstand the temperature, cold spots in the work. Our invention, utilizing pieces and> conveying them through said fui' completely insulated recesses in the furnace floor, prevents the escape of large quantities of heat nace,` and- means for operating said rollers‘in synchronism. heated uniformly. . - When our invention is applied to a chain con-veyor furnace, it is n'ot necessary for the rollers to be independentlydriven from an external REFERENCES YCITED 'The following references' are'of record in the 'ï' source, as shown on the accompanying drawing and described above for the roller hearth ar rangement. file of this patent: , UNITED STATES PATENTS In this modification, the conveyor Number chain or chains are driven by >a suitable external means, such as an electric motor, and the rollers are used` merely to support the chains. It is generally knownthat high temperature electric furnaces are, very often equipped _with l _ JAMES L. McFARLAND. NORMAN B. JONES. from the furnace and causes the work to be 50 489,017 o Name l Date Koch _________ __'____ Jan. 3, 1893 786,565 Hughes ___________ -_ Apr. 4, 1905 1,362,369 Talley '_ ___________ _,Dec. 14, 1920 1,825,107 Wean ___________ .__ Sept. 29, 1931 '