US2445150A - Method of heat-treating a metallic annulus - Google Patents

Description

July 13, 1948.

H. L. MUELLER METHOD OF HEAT TREATING METALLIC ANNULUS Filed Nov. 2, 1942 INVENTOR. HOMER L.MUELLER ATTORNEYS Patented July 13, 1948 METHOD OF HEAT-TREATING A METALLIC ANNULUS Homer L. ,Mueller, Cleveland, Ohio, assignor to The.Cleveland,Welding Company, Cleveland,

Ohio, a corporation of Ohio ApplicationNovember 2,1942, Serial No. 464,185

,rola: (01.148-13) 1 This invention relatesas indicated to a method of heat ;treatin ';and moreparticularlyto:the method of heat treating-annular articlessuch as large rings, flanges and the like.

not sag and warp during the heat treating operation. A furnace large enough to accommodate such objects becomes uneconomical to operate in view of the proportional relationship between the cubic content of the furnace and the mass of the article,

It is a principal object of my invention, there fore, to provide an improved process for the heat treatment of annular objects of the character and for the purposes above explained, which process affords an easy and economical solution to the problems above pointed out which have attended the prior art practices.

Other objects of my invention will appear as the description proceeds.

To the accomplishment of the foregoing and related ends, said invention then comprises the features hereinafter fully described and particularly pointed out in the claims, the following description and the annexed drawing setting forth in detail certain illustrative embodiments of the invention, these being indicative, however, of but a few of the various ways in which the principle of the invention may be employed.

In said annexed drawing- 2. Fig. l is a perspective of an annulus which may be formed by circularizing and butt welding a blank such as that illustrated in Fig. 1;

Fig. 2 is a side elevational view, partially in ,An expedient ,way; in which large annular ar-. section, of one form of apparatus which may be ticles, such as those having a. comparatively large employed for the purpose of carrying out the imdiameter and a relatively small cross-section, may proved process comprising my invention; and be manufactured is to circularize a flatblank ig. 3 is a t nsv rse Sectional V w Of a p having the desired cross-section and then butt tion of the app s r d in taken weld the ends together to form the complete an-. .10 on a plane substantially indicated by. the line nulus. The forming operation incidental to cir- 4-4. cularizing a fiat blank, and the local heating The blank is circularized in suitable rolling of-the annulus in butt welding the ends together, equipment, and the ends of the blank are welded makes it necessary and desirable to heat treatthe to as 2 0 f the annulus generally finished annulus for thepurpose of relieving the .15 indicated at 3 in Fig. 1. The process comprising stresses and strains therein set up by the above y i en s de i e pu pose of named processing steps. quickly and economically heat treating the an- It is also frequently necessary to heat treat for 1111 3 in Order to remove y-W ra ns-which the purpose ofhardening a metallic annulus, this may be present therein, and also, if desired, to form of heat treatment requiring a heating to a go impa t thedesired de of hardness n d c lhardening temperature, promptly followed by a y to the annulus-by a Progressive e t g to a quench, which is in turn followed by a reheating arde n t pe a q e i n bto a drawing temperature. sequent heating to, a drawing temperature.

When the annulus has a..relatively large di- One means for carrying out such improved-proc- .ameter v and a relatively thin cross-section, many ess is illustrated in Fig. 2, wherein a quench tank problems are encountered inthe heat treating is generally indicated at which Will he process,,.whgther the same be for either ophoth filled to a suitable level, such as indicated by the of; the above mentioned purposes. In the first line W an pp quenching medium place, it is extremely difilcult'and expensive to so such as water. A brace 6 isumounted across the support this type of bject i ord r th t it may tank 4 and it carries a standard l-on which are rotatably supported a pair of rolls 8. A'plurality of paired rolls-9 and'lil are arranged in the, tank 4,,preferably-beneath the level of the quenching medium therein, and all of these circumferentially spaced pairs of rollers are so arranged that when the annulus is placed thereon, the rollers will maintain the annulus in a true circle. One of these pairs of rollers, such as the pair 8, may be provided with a suitable driving pulley (not shown) on the axle thereof, about which may be trained a driving belt H for the purpose of driving the rollers and accordingly rotating the annulus in the rollers.

Mounted on a bracket l2, carried by the tank 4, is a small furnace l3, through which the annulus passes as it is rotated by the supporting rollers. This furnace l3, as most clearly illustrated in Fig. 3, comprises two substantially similar sections l4 and l5 hingedly connected as at [6 and maintained in assembled relation by a latch or detent H. The furnace l3 comprises a refractory lining l8 and a metallic carrying and supporting shell [9.

The wall of the furnace is perforated at spaced points to accommodate burner nozzles 20. The

arrangement and location of the burners, and the number of the burners used, will be governed by factors such as the size and shape of the crosssection of the annulus; the speed at which the annulus is to be moved through the furnace, etc.

It has been found that while satisfactory results may be achieved by using a few burners of a high heat content gas, such as acetylene, nevertheless, for most purposes best results will be secured. by using a fuel, such as natural gas and by arranging the burners in such a fashion that the refractory lining of the furnace becomes very highly heated. In this Way the annulus in passing through the furnace derives its heat not only from direct impingement thereon of the flame, but also by radiation from the walls of the furnace. heating produces superior results because of its more even distribution and accordingly the more even heating of the annulus section as it passes through the furnace.

As previously indicated, the furnace is made sectional so that one section may be swung aside to open up the front face of the furnace in order to receive and permit the removal therefrom of an annulus placed on and taken off from the paired guide rollers.

When the annulus is to be hardened, the temperature of the furnace will be so correlated with the speed of travel of the annulus therethrough that the temperature of the annulus section, when it reaches the quenching bath, will be at the proper quenching temperature for the desired hardness. These are all factors which may be readily determined and which are largely dependent upon the character of the particular annulus being treated so that a further and more detailed description is believed unnecessary.

In connection with the hardening operation it is generally customary to reheat the article to a drawing temperature, and this may be conveniently accomplished by mounting a second furnace 2| on a bracket 22 on the side of the tank 4 opposite the principal heating furnace I3. The furnace 2| will be similar in construction, although usually smaller than the furnace I3, since the drawing temperature is never as high as the quenching temperature. Otherwise the furnace 2 l, in its construction and mode of operation, may be similar to the furnace I3 as above described.

From the foregoing description, it will be observed that I have provided an improved process for the economical and expeditious heat treatment of large annular objects which could only This type of 4 be handled with great difiiculty in conventionalheat treating furnaces. Moreover, the cost of operation is considerably less than with the prior art practices, due to many factors which will be apparent to those skilled in the art.

Instead of employing a furnace such as 13, I may resort to other expedients for the purpose of heating to a quenching temperature the circumferentially progressive local area of the an nulus just prior to its entry into the quenching bath.

Similar alternative provisions may be made for heating the annulus after it has emerged fromthe quench to a drawing temperature. Sinc the drawing'temperature is, as indicated above, never as high as the quenching temperature, it will .be found that, for certain types of annulus sections, entirely satisfactory results may be attained by the use of an open flame heater.

Other modes of applying the principle of my invention may be employed, change being made as regards the details described, provided the features stated in the following claim or the equivalent of such be employed.

I, therefore, particularly point out and distinctly claim as my invention:

In the manufacture of a metallic annulus, rotatably supporting the annulus on its inner periphery at a plurality of circumferentially spaced locations to maintain the annulus as a true circle, and heating simultaneously from within and Without to a substantially uniform degree throughout its cross section a circumferentially progressing local segment of such annulus by radiant heat and flame together.

HOMER L. MUELLER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 443,928 Abbott Dec. 30, 1890 1,105,116 Wales July 28, 1914 1,711,835 Davis May '7, 1929 1,959,344 Coberly May 22, 1934 2,041,029 Stargardter May 19, 1936 2,044,763 Bouton June 23, 1936 FOREIGN PATENTS Number Country Date 225,333 Great Britain Dec. 4, 1924

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