US1013191A - Case-hardening apparatus. - Google Patents

Description

A. W. MAOHLBT.

CASE HARDBNING APPARATUS.

APPLICATION FILED MAY 25, 1906.

Patented J an. 2, 1912.

R 1 W A IJ Q. Q? .N w m a My v +M f,

UNITED STATES PATENT OFFICE.

ADOLPH w. macnnEg-or ELIZABETH, new JERSEY.

I casn-na meume Ann -terns. 1,013,191., Specificationot Letters-Patent." Patented Jan. 2,1912.

Application filed May 25, Serial 1T0. 318,679. I

To all whom it ma concern} V Be it known that I, AnoLPH W. MacHLE'r, a citizen of the United States, residing in Elizabeth, in the county of Union andState of New Jersey, have invented certain new and useful Improvements in Case-Hardening Apparatus, of which the following is a specification. I w

This invention relates principally to. case.- hardening steel or iron articles.

In my co-pending application No. 244,244 Patent No. 822,460'is set forth a manner of case-hardening by inclosing articles in. aretort, and both'heating and rotating theretort while a current of carburizing gas circulates therethrough; and my ctypending application No- 292,515 filedDecember 19, 1905, is disclosed a'manner of thinning the carburizing gas by. means of ammonia.

One of the objects of the present invention is to simplify and reduce the cost of the heating apparatus and the operation there'- of, "as Well as to adapt the same for certain kinds of work, and another object is toprovide for securing the proper quality of carburizing gas, as well as for diluting the same, .whereby the user may operate inde pendently of the ordinary illuminating gas supply, which is not always available, and which in some cases-is not suitable for car,- burizing.

According to the first part of the present invention, the articles are placed directly in the flame chamber of a retort which is in the form of an oven, and heated directly by the flames, and then the flames are extinguished, and the oven is filled with carburiz ing gas, which cements the articles by means of their own retained heat. The walls of the oven are greatly thickened for the purpose of retaining heat, thus delaying the cooling of the articles sufficiently to enable them to be substantially cemented by their retained heat, or by the heat retained in the oven.

The top of the oven is provided with one or more capacious vents for the escape of products of combustion durlng the heating of the articles, and these vents are providedwith closures, whereby they may be closed during the subsequent carburizing- 0per a. tion; and thG'OVBIl is also provided with, a

constricted regulatable vent for controlling ing the vcarburizing operation.

carburilzing' gas therethrough. The carburizing gas is preferably introduced .into the oven through the same pipe which feeds theburners. I r V I In practicing my invention in one Way,

.ammonla gas may be led, from a tank through a body of naphtha, the ammonia taking up a quantity of naphtha, and being then led into'the retort'or oven to carburize the articles; the ammonia serving as a di1uent for the carburizing gas whichit derives from the naphtha, and avoiding the deposit of free carbon upon'the articles, and hasten By this means, the user becomesindependent "of the supply of illuminating or heating gas from the usual sources, ,whichis liable tofluctuate in quality,'or which may not be available, and is assured a continuous supply of carburizing gasof uniform quality.

Other objects, features and advantages will hereinafter appear. j

'In the accompanying drawings, Figure 1 shows one form of apparatus operating in accordance with my'present invention portionsof the oven and "the, oil tank being broken away to disclose the construction. Fig. 2 is a) cross-section of the oven, showing the burnerslet into the opposite walls thereof. i

The oven comprises side walls 1, 2, rear walls 3, top 4, front wall 5 and base 6, all made of refractory material andv greatly thickened in proportion to the capacity of the oven, so that they retain heat, thereby to delay the cooling of the articles, and

hence prolong the cementing operation until a substantial shell is formed upon the arti-.

cles. The oven is preferably containedin an iron boxing7, and rests upon an iron base 8 supported uponlegs 9. At the front of the oven is provided a door or lid 10 of thick refractory material, which maybe lifted by means of books 11. In thetopof the oven are provided capacious vents 12, which are made open during the generation of flames in the oven and may be closed by conical plugs 12' during the subsequent filling of the oven with carburiz'ing gas.

Gas or other fuel is supplied tothe oven through a pipe 13 controlled by a valve 14; and air is supplied through a pipe 15 conthe renewal. through. the pipe 13 of freshhence enabled to control the condition and trolled by a valve 16; the air being preter-' ably supplied under pressure. The mixed air and fuel are distributed by means of pipes 17, 18, 19 and 20, to burners 21 in the base of the oven. Preferably the burners are arranged'in two series in the opposite walls 1, 2, so as to direct the flames along the floor 6 of the oven. A thick plate 22 of either iron or refractory material may lie horizontally just above the burners, spaces being left at 23 around the edges of the screen for the passage of flames up into the body of the oven, whereby the flames are caused to heat the walls of the oven very hot, as well as articles contained therein. The screen also because ofits great thlckness serves as a reservoir of heat efl'ective'to prolong the carburizing operation.

In operation the door 10 s lifted and the articles 24-, such as tubes, or bars or devices of any shape are placed upon the screen or table 22. Before the door 10 is dropped, the valves 14 and 16 are opened and the mixture of the gas and fuel is ignited at the burners 21, the products of combustion escaping through the vent or vents 12. The heating proceeds until the articles reach a carburizin'g heat which is say above red heat and below the melting point; at which time the door and the walls of the oven, as well as the'screen 22, are heated to about the same temperature as the articles, and serve as reservoirs of heat to prolong the carburizing operation. Thereupon the valve '16 is closed to out off the air and extinguish the flames at the burners, and the vents 1-2 are closed by the lugs 12; and gas may continue to flow -1n through the pipe'13 to immediately fill the oven and carburize the articles; this gas being of any suitable quality, as coal gas or any other carburizing fluid. Preferably a constricted vent pipe 46 is fitted in the lower part of the door 10 or one of the walls of the oven, so that the current of carburizing gas may pass slowly through the oven, thus insuring the drawing off of the vitiated gas, and

gas. This vent may be regulated by a valve 47. The gas escaping through this vent and igniting in the air shows its condition by the color of its flame. The operator is flow of the gaseous atmosphere in the oven by regulating either valve 47 or 14 or both. Owing to the thickness of the heated walls, the cooling'of the metal articles is greatly delayed, and they are enabled to become cemented to a substantial depth by means of their own retained heat, or by means of the heat retained in the oven. After the articles cool to a certain extent, the chemical action of the gas thereon, ceases; and- In case the cementation does not proceed to a suflicient depth, they may be allowed to remain in the oven, and the valve 16 may be opened to admit air, and the oven again heated as before by raising the arti-- cles to the carburizing point, whereupon the flames may be again extinguished and carburizing gas supplied to the oven, thus causing the cementation of the articles to proceed to a greater depth; and this operation may be repeated on the same articles until they have the required depth of cementation.

Ammonia or other inert gas may if desired be admitted through a pipe 48 which joins the pipe 17, and is provided with a valve 49, the latter being closed during the operation of heating the oven. The mixture of gas and ammonia may be controlled ity suitable for case-hardening, or if no gas is available from ordinary sources, for the purpose of carburizing, the devices now to be described may be employed. A tank 50 is nearly filled with naphtha 51. A tank 52 containing ammonia or other suitable lnert gas under pressure, is put in connect1on with the tank 50 by means of a pipe 53, the flow of ammonia being controlled by a valve 54 in said pipe. The latter extends down into the oil tank. 50, and terminates near the bottom thereof in a spray -55. Bubbles of ammonia are seen at 56 rising from the spray, and during this action. they take up a plenum of naphtha or carbon fill ng the top of the tank 50 with gas comprlslng ammonia and carbon. This gas may be led through the pipe 48 from the top of the tank 50 through the pipes 17 18 and 19, and into the oven through the burners 21;- the valves 14 and 16 being closed and the flames'extinguished. Pref-- .erably the proportion of ammonia which Variations may be resorted to within the scope of the invention, and portions of the improvements may be used without others. Having thus described my inventi0n, I claim:

1. In combination, a close-d oven having walls of refractory material, a series of burners opening within said oven; the latter provided with a capacious vent for products of combustion, and with means for closing said vent, and means for supplying to said burners either carburizing gas alone or mixed air and fuel at will constricted means being provided for slowly'venting carburizing gas from the oven; said walls being sufficiently thick in proportion to the capacity of the oven, to maintain iron or steel articles there in at carburi'zing heat for a substantial length of time after the extinction of flames at the burners, to enable cementation of the articles to proceed to a substantial depth before they cool.

2. In combination, a closed oven having greatly thickened walls of refractory material and provided with a capacious vent for products of combustion and with means for closing said vent,'a series of burners in said oven, means for permitting extinction of flames at the burners, and means for supplying'mixed air and fuel to said burners and for supplying the oven with carburizing gas after extinction of flames at the burners, regulatable means being provided for slowly venting the carburizing gas from the oven.

A case-hardening apparatus. comprising a closed oven having walls of refractory material which are greatly thickened in pro-portion .to the capacity .of the oven, :1

series of burners insaid oven, means for permitting extinction of flames at-vtheburners, means for supplying mixed air and fuel to sald burners, and means for supply ng and passing a current of mixed ammonia and carburizing gas through the oven after extinction of the flames at the burners; said oven having a capacious' vent for products of combustion, and a closure for said vent.

4. The combination with a closed oven whose walls are formed of r fractory Inatcrial, of burners for mixed air and fuel in said oven, and means for filling the oven, after extinction of the flames at the burners,

with a different gas capable of chemically acting upon the articles contained in the oven while they remain heated; the walls of the oven being greatly thickened so as to retain suflicient heat to maintain the articles in the oven at the required heat during such chemical action; said oven provided with a vent for the products of combustion and a closure for said vent.

5. The combination of a closed oven having walls thickened to retain heat, a series of burners for mixed air and fuel opening into said oven at the base t-hereof, a thick heat-retaining bed slab between said burners and the body of the oven, flame passages being left between the edges of the bed and the walls of the oven, and means for supplying carburizing gasto said oven after extinction of flames at said burners the oven being provided with a capacious vent for the products of combustion and'with a closure for said vent, and also having a regulatable constricted vent for the carburizing gas.

6. The combination of an oil tank connected with an oil supply and having automatic means to regulate the flow of oil into the tank, an ammonia tank, a pipe leading froni the ammonia tank and terminating in a spray in the lower portion of the oil tank. means for controlling the flow of ammonia into the oil tank, and a case-hardening retort provided with heating means and a vent and in communication with the upper part. of said oil tank.

7. The combination with a: retort in the form of a closed oven having thickened heatretaining Walls, of a series of burners opening into said oven, means for supplying mixed air and fuel to said burners. and means for applying and introducing cal-bib rizing fluid thinned with ammonia into said retort through said burners; the retort being provided with a capacious vent for the products of combustion and a closure for said vent, and also with'a constricted vent for the carburizing fluid.

. --8. The combination of a closed oven having its walls thickened to retain heat and provided with 'a door, a series of burners for mixed air and fuel opening into said oven,

means for permitting extinction of flames at the burners, the latter provided with a capacious vent for the products of combustion and with a tapering solid plug to fit said vent, means being provided for supplying carbnrizing gas to the oven after extinction of flames at the burners, and the oven alsohaving a regnlatableconstricted vent for the carbnrizing gas.

9. In combination, an oven having greatly thickened walls of refractory material and provided with a capacious vent for products of combustion and with means for closing said vent, a series of burners in said oven, means for permitting extinction of flames at the burners, and means for supplying mixed air and fuel to said burners and for supplying the oven with carburizing gas diluted with another gas after extinction of flames at the burners.

7 10. A carburizing retort in the form of a closed oven having a door and provided with burners and means forpermitting the extinction. of'flames at the burners, and hav-.

in at carburizing heat for a substantial length of time after the extinction of flames at the burners, to enable cementation of the articles to proceed to a substantial depth before they cool, provision being made for passing carburizing gas slowly through the heated oven.

11. A carburizing retort in the form of a closed oven having walls and a door all of refractory material and provided in its bottom portion with a heat-bed distinct from the Walls of the oven; burners for mixing air and fuel provided in the bottom. portion of said oven; and means for permitting the extinction'of flames at the burners; said walls and door being sufficiently thick in proportion to the capacity of the oven, to serve as an ample reservoir for heat to maintain iron or steel articles therein at carburizing heat for a substantial length of time after the extinction of flames at the burners, to enable ceinentation of'the articles to proceed to .a substantial depth before flames, gas supply pipes 13, air supply pipe 15, and a pipe 4:8 for the supply of inert gas; said walls, heat-bed and door being sufiioiently thick. in proportion to the capacity of the oven, to maintain iron or steel articles therein at carburizing heat for a substantiallength of time after the extinction of flames at the burners, to enable cementation of the articles to proceed to a substantial depth before they cool.

13. A earburizing retort in the form of a closed oven having walls and a door all of refractory material and provided in the bottom portion of its flame chamber with a heat-bed distinct from the walls of the oven;

burners for mixing air and fuel provided in the bottom portion of said oven; means'for permitting the extinction of flames at the burners; a closable escape for the flames from the oven, and a constricted rgas-vent; said walls being sufficiently thick in proportion to the capacity of the oven to form a'heat reservoir, to maintain iron or steel articles therein at carburizing heat for a substantial length of time after the extinction of flames at the burners, to enable cementation of the articles to proceed to a substantial depth before they cool.

14:. The combination of a closed oven,

burners opening in said oven for mixed air and gas, means for extinguishing the burntory material of sufliciently great thickness to constitute a heat reservoir capable of maintaining the contained articles atthe necessary temperature to enable them to become carburized to a substantial depth.

ADOLPH W. MACHLET. Vitnesses SAMUEL R. OGDEN, PI-uLIr C. OSTERMAN.

- Copies of this patent may, be obtained for five cents each, by addressing the Commissioner of Patents,

Washington, D. G.

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