US2757919A - Forge furnace - Google Patents

Description

Aug. 7, 1956 I w. B. LEVY 2,757,919

FORGE FURNACE Filed May 2, 1952 2 SheetsSheet 1 W. B. LEVY FORGE FURNACE Aug. 7, 1956 2 Shets-Sheet 2 Filed May 2, 1952 Uited States Patent Ofiice FORGE FURNACE William B. Levy, Wilmington, Del., assignor to Delaware Tool Steel Corporation, Wilmington, Del., a corporation of Delaware ApplicationMay 2, 1952, Serial No. 285,631

9 Claims. (Cl. 263-4) The :present invention relates to forge furnaces of the oilorgas-fired type, and theinvention contemplates a furnace departinginessential structural respects from the prior furnacesof the same classes and exhibiting thereby certain novel and highly advantageous functional characteristics as hereinafter fully set forth.

An important'object-of the present invention is .to providea forge furnace wherein provision is made forconfining the forging heat to a highlylocalized area of the work piece.

To this and other related ends hereinafter set forth, the invention contemplates also the.provision in the furnace of a novel front work tile having work-receiving openings of size and shape to accommodate with suitably close tolerances the particular work pieces which .are .to be inserted into thefurnace for local heating, said front tile being readily removable for interchangeability with tiles having work openings differently sized .andshaped in accordance with other'and differing work .pieces.

Another object is to provide a forge furnace which can be heated uniformly so that the heating chamber is freefrom hot. spots and cold spots.

Another object is to provide a forgefurnace which will be relatively economical of fuel.

Still another object is to provide a forge furnace which is susceptible in relatively high degree to accurate and automatic control of-temperature.

A further object of the inventionis .toprovide a furnace havinga novel and advantageous form and .dispositionof fiue opening together with an improved-designofroof tile readily adjustable to regulate the effective :area :of said flue opening as .and for the purposes hereinafter-described.

Still another object is to provide a furnace .of the stated character which-may be brought rapidly from .a coldstart-up toforging or heat-treating temperatures.

A preferred embodiment of .the inventionzisillustrated in the accompanying drawings, wherein:

Fig. 1 is a'plan view of the furnace madein accordance with the invention;

Fig. Zisasectional view :taken on the line22.of Fig. 1;

Fig. 3 is an enlarged sectional view taken on 'thedine 3-3 of Fig. 2;

Fig.4 is a sectional view taken on the line-4-.4 of i 'Figr51is asectionalview taken .on the line 5-?-5-.of Fig. 6;

Fig. 6 is a fragmentary View in perspective of Tone portion of the furnace structure; and,

Fig. 7 istaasectionalwiew on= the.liner77 of Fig. 2.

Referring'more particularly to'the drawings, the combustion orheating chamber 11 ofthefurnace is contained in ametal casing 1-which takes theform of an opentopped rectangular box having its front wall cut away as indicated at 2 to providefor insertion and withdrawal of the Work pieces in and from the chamber. One such work 2,757,919 Patented Aug. 7, 1956 lined withsuitableinsulation material 4, and the chamber 11 is bounded by refractory bottom .tiles 5, .rear tiles 6, and tiles .7, and upper and lower front tiles 8 and 9 which are encased within the said insulation material. While the chamber formed by .these tiles .may be of any desired shape, I have found it desirable to giveit the cross sectional form illustrated :in Fig. 3 of the drawings. The chamber 11 thusassumes a-generally oval shape in transverse cross section terminating at the bottom in a re- .duced generally rectangular basearea 12 and at the top in a-relatively wide flue opening 14. The functional significance-of-this chamber formation willbe fullyset forth hereinafter. The flue opening 14 is normally partially closed :by a top .or roof .tile 15 which is mounted on the top of the furnace for free adjustability forward and back for the purpose of increasing or reducing the effective depth, fore and aft, of the flue opening 14, the width of the opening :from .side to .-.side, which corresponds .to the side to side widthof the chamber, remaining unchanged.

The form and arrangement of the flue opening .contributes .materially to the maintenance of uniform temperatures throughout .the heating chamber, as will be morespecifically set forth below. The adjustability of the roof tileand of the eifectivearea of the line opening affords accurate control of combustion. Thus, when the forging fire. is ignited at .the beginning of .an operation, it is usually desirable to have arelatively large amount of air present to provide for complete combustion of the fuel .and .to avoid formation of soot. .As the furnace approaches normal operating temperatures, the.flue opening may be .restrictedso .as .to conserve heat within the fire box at minimum expenditure .of fuel. Over-extended periods of furnace :operation .under varying conditions of use, theadjustableroof tile vaffords asimple and highly practical method for maintaining most efficient combustion by regulation of the extent of effective flue opening. It will be .noted that the.flue opening is at the back of the furnace remotefrom the operator so that the latter is not exposed to the exhaust ,gases .and their heat. In the presentinstancethe roof .tile .15 is composedof a pluralityof tile elements. which are secured together by through I.bolts.17, 17.and nuts 18.

.The'heatingchamber 11is firedby apair of burners 2'1, 21.in.the frontof thefurnace. Thelower front tiles previously designated collectively by the reference numeralf9, include tworburner blocks 22, 22 arranged relatively as's'hown in Fig. 4. Each of these blocks contains a noz'zlepassagei2'3 whichcomprises.acylindrical mouth 24 at the: outer end whichmergesrsmoothlyinto. a transversely elongated -.an'd=relative1y narrow .terminal orifice 25 at theinner end. The .outer orzmouth end of the passageis countersunk. for reception .ofthe inner .end of a tunnel tile 26 of generally cylindricalor conical form whichis embeddedin theinsulation 4,.the jointbetween the tile 26 and .the'block.22.being snitablysealed as indicated at 27. The outer-.endofthetunnel tile occupiesan opening in.the casing .1.and the tile isheld in place by a flange 28 which abuts .the outer end .of .the .tileand is secured by ..screws.30 .to .the casing. .The .inner end of the bore 29 .of .the .tile. 26- communicates directly with .the outer end oftthenozzle passage .23, and the outer end portion .of thelborehas acounterbore .31 which receives a nipple 32 threaded into and projecting. inwardly from the. flange T2 8. Theflange also receives .the :end .0f.a fuel pipe 33 'whichds-connected .to a..source-of .fuel,.not shown, said pipe containing a control valve34. The burner principles are .similar. to .those disclosed ,in United .States Patents 2,230,960 and'2,277,595.

"The.c'omb.ustible mixture ignites at the mouth 24 of nozzlepassage and the "flameis .projected through the 'slottedorifice'25'into the'chamber ll. 'Byreason of the shapeo'fthe "orifice'and the symmetrical arrangement of the nozzles on opposite sides of the transverse median plane of the chamber, the flames from the two burners cover the full length or lateral width of the chamber and afford substantial uniformity of heating throughout the chamber. Contributing to this uniform temperature condition is the form and location of the flue opening 14 which as previously described extends uniformly over the entire lateral dimension or length of the chamber 11 so that the flow of combustion gases from the chamber is uniform throughout the latter. Also, contributing to the effective elimination of hot spots" and cold spots within the chamber 11 is the peculiar oval or pear shape referred to above, which functions to direct the flame and combustion gases in substantially uniform distribution throughout the chamber toward the flue opening. The rear wall 35 of the chamber, concave in vertical section, toward which the flame from the burners is directed, aids materially in the heat distributing function by affording highly favorable reverberation of heat within the chamber.

For accurate regulation of the intensity of the flame, a thermocouple 36 is inserted in one side of the fire box and extends a substantial distance into the latter. Because of the uniform character of the flame dispersion, the location of the thermocouple is not critical since the heating effect is substantially uniform throughout the fire box and the furnace is devoid of the hot spots and cold spots normally present in conventional furnaces. The thermocouple may provide a visual indication of the forge temperature for manual adjustment of the fuel supply or it may be connected for automatic adjustment of the supply.

Provision is made for inserting the work pieces into the chamber 11 above the burner orifices 25 and below the thermocouple 36. To this end the upper front or work tile 8 is provided with a plurality of openings 37, each dimensioned to pass the work piece 3 with minimum practical clearance so that the latter may project to a desired extent into the interior of the chamber. With this arrangement only that portion of the work which projects into the chamber will be subjected to the heating action of the flame. Because of the snug fit of the work piece in the opening 37, the heating will be highly localized in the exposed portion of the work and the remaining portions will remain relatively cool.

By thus confining the heat treatment to a predetermined length of the work piece it is possible to heat the desired area without heating the shank portions to an extent such that the temper will be drawn and the hardness removed. This has particular utility in operations for redressing pneumatic chisels and the like, wherein the operations consist of reforging, heat-treating and finally regrooving the working tip. As the chisel contains a hardened shank, which should last the life of the chisel, it is of particular advantage to be able to redress the chisel end without disturbing the hardness of the shank as by overheating.

In many cases by confining the heat-treatment to the inner terminal end of the work it will be possible to eliminate the need for tongs in handling the work. Obviously by manual handling the operator can handle the work pieces faster and more accurately thus increasing his production. Unnecessary bending of the work pieces may also be eliminated because the heat may be confined only to that length of the work which goes into the forging dies, or the length which is to be hot worked by the dies. By keeping cool that portion of the work piece which extends beyond the dies, ductility of that section is minimized and consequently the chance of bending is substantially reduced.

Localization of the heat to that portion of the work which is to be forged also .effects great economy in fuel consumption since no substantial amount of heat is wasted unnecessarily in heating the work beyond that portion which is actually required, and the snug fit of L' the work in the recess precludes any substantial heat loss by convection around the work piece.

In accordance with the present invention the upper front or work tile 8 is removable and is thereby interchangeable with tiles adapted for use with work pieces of different sizes or shapes. To this end the work tile 8 is grooved along each edge 38 which confronts an end tile 7, and the latter tile is provided with a tongue 39 which engages in the groove 38 and prevents lateral displacement of the work tile 8. As shown in Figs. 3 and 6 the work tile 8 may be readily removed by upward displacement after adjustment of the roof tile 15. In the present instance the end tile 7 is provided with two such tongues 39 which cooperate individually with corresponding tongues on the other end tile to support the work tile selectively in two different positions in which that tile is more or less remote from the inner faces of the rear tiles 6. By thus adjusting the position of the work tile the effective depth of the heating chamber may be regulated in accordance with the length of the work piece which it may be desired to heat. Obviously, more than two sets of the positioning tongues 39 may be provided to afford a greater number of selective positions for the work tile.

By providing the work tile 8 with a plurality of workreceiving apertures 37 of minimum size, it is possible to minimize the operators exposure to the heat of the forging chamber and yet provide capacity for a sufficient number of forgings to maintain continuous operation. To further reduce this exposure when all of the work apertures are not in use, a refractory plug 40 is provided for each opening. The plug 40 effectively bars passage of heat through the unused apertures and protects the operator from excessive exposure to the forging temperatures. With reference to Figs. 2 and 7 it is seen that the plug comprises a generally cylindrical shank 41 terminating at its inner end in a tapered portion 42. The outer end is provided with a radial flange 43 and is formed with an integral eye 44 for easy insertion and removal. The flange 43 not only serves as a limit stop in the insertion of the plug but provides an effec tive seal against the escape of gases around the cylindrical shank portion 41.

The aforedescribed construction of work tile contributes also to maintaining uniform temperature throughout the heating chamber in that it reduces to a minimum the heat losses in the localized area of work admission. The operator protecting aspect of the work tile is accentuated by the location of the flue opening at the top and rear of the furnace remote to the operators position. It should be noted that the invention provides a forge furnace which may be so accurately and automatically controlled as to temperature, that the furnace may be used either for forging or for heat treating. This is particularly important in the forging of such items as high speed steel chisels and similar tools which can be heat treated directly from the forging operation if the temperature at which the pieces are forged is controllable within the close accurate limits required. This accuracy is not available in the conventional furnace where hot spots prevail in certain sections of the heating area.

While a single preferred embodiment of the invention has been illustrated and described, deviation in structural details and arrangements of parts is possible within the scope of the invention as defined in the appended claims.

I claim:

1. In a forge furnace, a work chamber and means for heating said chamber and a work tile forming a part of the wall of the chamber and having a plurality of openings affording access to the chamber for admission of work to the latter, said work tile being slidably interlocked by way of upright guideways with the adjoining relatively fixed walls of the furnace and being detachable by elevation in said guideways from the normal working position, each said opening being designed with respect to a particular work piece to aflord passage for the latter with minimum clearance whereby the said piece when occupying the opening may act as a plug to limit the escape of heat through said opening during the work-heating operation.

2- A forge furnace according to claim 1 wherein the heating chamber has a top flue opening together with a roof tile slidably and rernovably seated on the top of the Work tile for adjustment over the flue opening to regulate the eflective open area of the latter.

3. In a forge furnace, an elongated work chamber, a Work tile forming a part of the forward wall of the chamber and having a plurality of openings aflording access to the chamber for admission of work to the latter, burner means in said forward wall and arranged to project a flame into and across the minor dimension of the chamber toward the rear wall thereof, said burner means extending over the full major dimension of the chamber below said admission openings and affording a substantially uniform distribution of flame in the chamber, a flue opening at the top of said chamber substantially coextensive with the said major dimension of the latter, and extending parallel to the work tile, and means adjustable across the minor dimension of said flue opening to regulate the extent of the effective open area of the flue.

4. In a forge furnace, an elongated work chamber and means for heating said chamber, said heating means comprising burner means arranged to project a flame across the minor dimension of the chamber and extending over the full major dimension of the chamber so as to afford a substantially uniform distribution of flame in the chamber, the wall of the chamber toward which the flame is projected being concave substantially throughout its height in the vertical section across the said minor dimension and terminating at the top in a flue opening substantially coextensive with the said major dimension of the chamber, and means adjustable across the minor dimension of said flue opening to regulate the extent of the effective open area of the flue.

5. A forge furnace according to claim 4 wherein the chamber is generally oval shaped in the said vertical cross section.

6. In a forge furnace, an elongated work chamber and means for heating said chamber, said heating means comprising burner means arranged to project the flame into and across the minor dimension of said chamber and extending over the full major dimension of the chamber so as to afford a substantially uniform distribution of flame in the chamber, a work tile in the same wall of the chamber as the burner means and immediately above the latter and extending along the major dimension of the chamber, said tile having openings for admission of Work to the chamber and said admission openings being dimensioned for reception of the work pieces with minimum clearance, a flue opening at the top of the chamber substantially coextensive with the said major dimension of the latter, and an adjustable roof tile at the top of the chamber extending over the major dimension of the chamber and being adjustable across the minor dimension to regulate the effective exposed area of the flue opening.

7. A forge furnace according to claim 6 wherein the portion of the flue opening left exposed by the roof tile lies at the opposite side of the chamber from the work tile.

8. In a forge furnace, a work chamber having side Walls embracing the entire perimeter of the chamber and means for projecting a flame into the lower part of the chamber to heat the latter, a work tile forming a part at least of the perimetral wall of the chamber and having an opening for access to the chamber for admission of work to the latter at a point remote from and above the point where the flame enters the chamber, and a top wall for said chamber movably supported on the said perimetral walls and defining a side of a flue opening in the top of said chamber remote from and above said work access opening, said top wall being adjustable to vary the size of the flue opening.

9. A forge furnace according to claim 8 wherein the flue opening is at the side of said chamber toward which the flame is projected and wherein the inner surface of the chamber wall at said side is contoured so as to direct the flame upwardly along said wall toward the flue opening.

References Cited in the file of this patent UNITED STATES PATENTS 1,004,200 Regan Sept. 26, 1911 1,321,098 Gray et a1. Nov. 11, 1919 1,448,701 Breaker Mar. 13, 1923 1,550,902 Hansen Aug. 25, 1925 2,086,290 Bedford July 6, 1937 2,519,616 Watkins Aug. 22, 1950 2,580,377 Patton Dec. 25, 1951 FOREIGN PATENTS 107,433 Great Britain July 5, 1917 357,336 Germany Aug. 22, 1922 551,519 Germany June 1, 1932 OTHER REFERENCES 'Irinks Industrial Furnaces, volume H, second edition, copyright 1942, published by John Wiley and Sons, New York, New York, pages 338 and 339.

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