US2116069A - Apparatus for selectively quenching ferrous sections - Google Patents

Description

May 3, 1938. P. HOFFMAN ET AL APPARATUS FOR SELECTIVELY QUENCHING FERROUS SECTIONS Filed Jan. 27, 1936 3 Sheets-Sheet l W ENTOR BY 5W M ATTORNEYS May 3, 1938. P. HOFFMAN ET AL APPARATUS FOR SELECTIVELY QUENCHING'FERROUS SECTIONS Filed Jan. 27, 1936 3 Sheets-Sheet 2 BY M ATTORNEYS -May 3, 1938.

P. HOFFMAN ET AL APPARATUS FOR SELECTIVELIY QUENCHIIIG FERROUS SECTIONS Filed Jan. 27, 1936 3 Sheets-Sheet 3 ATTO R N EYS Patented May 3, 1938 UNITED STATES PATENT OFFICE APPARATUS FOR SELECTIVELY QUENCHING FERROUS SECTIONS ware Application January 27, 1936, Serial No. 60,990

Claims.

The invention relates to apparatus for heat treating metals, and more particularly to a container'for maintaining a quenching bath at elevated temperature.

5 According to the invention an elongated pot or container is provided for holding the liquid bath, such as lead, at a suitable elevated quenching temperature. This container is of comparatively shallow and narrow cross section and of sufficient length to accommodate the member to be heat treated which, for example, may be a length of steel railway rail.

The pot or container may be supported by a suitable structural framework above an open top elongated furnace. This furnace may be made up of the usual brickwork construction and sup ported by the same framework which supports the pot or container.

The bath container may be heated by gas burn- 2o ers distributed on opposite sides of the furnace along the length of the container so as to provide substantially uniform heating of the entire bath.

Burners for burning either fuel gas or oil are built into the side walls of the furnace along the 25 length thereof and are preferably disposed with the burners on opposite sides in staggered relation, with respect to one another.

In addition to the burners for supplying the necessary heat to raise the temperature of the bath to the desired value, suitable cooling devices may also be provided to cool the bath in case it exceeds the desired temperature. These cooling devices may take the form of spaced nozzles distributed along the length of the container on opposite sides thereof and supplied with air.

Suitable automatic controlling devices may be provided for turning on the fuel burners when the temperature falls below a predetermined limit and for turning off the fuel burners and turning 40 on the air nozzles when a predetermined temperature is exceeded. Suitable thermocouples may be immersed in the bath adjacent the point at which close regulation is desired for automatically controlling the turning on and off of the fuel 45 burners and of the air nozzles.

While the apparatus may be used for heat treating various forms and kinds of metals, it may be especially adapted for heat treating steel rails. Suitable supports may be provided at the top of 50 the container between which the head of the steel rail may be inserted head downward for the selective immersion of the head and either part or all of the web into the liquid bath, the base of the rail resting on these supports. These sup- 55 ports may be so spaced lengthwise along the container and may have such physical length as to provide any predetermined supporting action to the rail to assist in controlling warping or cambering of the rail.

Although the apparatus may be used to carry 5 out different methods of heat treatment, it is essentially adapted for carrying out the method disclosed in copending application Serial No. 374, filed January 4, 1935.

The invention also consists in certain new and. original features of construction and combinations of parts hereinafter set forth and claimed.

Although the novel features which are believed to be characteristic of this invention will be particularly pointed out in the claims appended hereto, the invention itself, as to its objects and advantages, and'the manner in which it may be carried out, may be better understood by referring to the following description taken in connection with the accompanying drawings forming a part thereof, in which Fig. l is a transverse cross section through the treating bath taken on the line l-| of Fig. 2;

Fig. 2 is a side elevation;

Fig. 3 is a horizontal section taken through the burners;

Fig. 4 is a top plan view of the bath.

Fig. 5 is a diagrammatic view illustrating positive circulating devices.

In the following description and in the claims, various details will be identified by specific names for convenience, but they are intended to be as generic in their application as the art will permit.

Like reference characters denote like parts in the several figures of the drawings.

In the drawings accompanying and forming part of this specification, certain specific disclosures of the invention are made for purposes of explanation, but it will be understood that the details may be modified in various respects without departure from the broad aspects of the invention.

Referring now to the drawings, and more particularlyto Fig. l, the bath construction, in general, comprises a suitable foundation supporting a steel framework 2| and suitable brickwork 30 forming the furnace chamber 33. Above the furnace chamber is the elongated body 53 which contains the bath 56 of molten lead or other suitable material. The article being treated is shown as a steel railway rail and is indicated by 80. This rail rests onthe supports 64 and has its head immersed in the bath, as shown.

The foundation 20 supports a suitable steel framework indicated in general by 2|. This framework 2| includes longitudinal angle irons 22, upright structural members 23, side plates 24 and tie rods 25. Supported by this framework is thebrickwork 30 which comprises a'bottorn 3| and sides 32 forming the furnacechamber 33. The details of the construction of the steel iramework 2| and'of the brickwork 30 will be i'nac-' The burners may be of standard construction and may be adapted for burning either gaseous or liquid fuels The burners 31 are supplied by gas headers 43, one on eachside of the furnace, which in turnare supplied .by feed pipes 44 extending to the fuel supply. Branch pipes 45 having manual control valves 46 connect the respective burners 31 with the headers 43.

For supplying each burner with the necessary air for combustion, air headers 41 are provided, each of which is supplied by a feed pipe 48 which extends to a supply of air under pressure. Branch pipes 49 having valves 50 connect the respective burners 31 with the air headers 41.

The lead pot or container 53 may be conveniently manufactured from a half of a ten inch steel pipe indicated by 54. This pipe is welded to angle irons 551 which in turn are supported by the framework uprights 23. The pct 53 is filled with the bath indicated by 53 which may be of any desired substance maintained at any desired temperature.

' Forcarrying out the process for which the present apparatus was especially arranged, the

bath 55 may comprise an alloy of lead and antimony in the proportion of approximately V lead and antimony by weight. The bath may be of such limited cross section that only 5000 lbs. of molten metal is necessary'for the preferred heat treating operation. It is obvious that baths of other proportions of lead and antimony and of other materials may also be used.

For cooling the bath when it becomes overheated, a plurality of air jets 59 are provided, extending along the length of the pot on opposite sides thereof. These air jets 59 are supplied from air headers 60 which in turn are supplied from feed pipes 6| connected to a suitable source of air under pressure.

For supporting the base flange of the rail being treated, when it is immersed head down in the bath, suitable pairs of supports 64 are provided. These supports may takethe form of angle irons resting on bars 65, in turn supported by the main frameworkof the apparatus. The angle irons may extend along the length of the bath a sufficient distance to give the desired supporting effect to the rail to assist in limiting the cambering or warping of the rail due to heat treatment. These rail supports are a sufficient distance apart to permit entry of the head of the rail, but are close enough together to engage the base of the rail as illustrated especially in Fig. 1.

For removing any lead fumes or other obnoxious gases which may be formed, a special exhaust system is provided. It will be understood that ordinarily the temperatures used are well below the volatilization points of the metals n fans (not shown) The exhaust system comprises a plurality of exhaust boxes denoted, in general, by 31 connected by exhaust pipes 88 to suitable exhaust The exhaust boxes are provided with slots 69 at the edge of the pot and suitable holes 10 in the ends of the boxes for carrying away any obnoxious gases which may be given ofi during the heat treating operation.

Provision is made for close automatic temperature regulation. A series of thermocouples denoted by 13-(Fig. l) are immersed in the bath. These thermocouples are of standard construction and are preferably immersed so that they are disposed close to that part -o f the member undergoing heat treatment whose, temperature should be most closely contra In the illustration shown for treating ast 1,rail, the thermocouples. 13 are disposedcloseto the head of the a l For maintaining a" uniform temperature throughout the length of the bath, a plurality of thermocouples may be used which may be disposed on opposite sides of the bath. For example, referring to Fig. 4, eight thermocouples may be used, indicated by l to 8. Couples I, 3, 4, 5, I and 8 may be disposed on one side of the bath while couples 2 and 6 may be disposed on the other side of the bath. It will be understood that these couples are connected up to suitable regulating apparatus (shown diagrammatically in Fig. 2) which controls the flow of fuel to the burners 31 and the control of air to the jets 59. The specific structure for exercising this automatic control is old and well known in the art and of itself forms no part of the present invention, but the technique of applying the automatic control to the particular furnace is new.

Couple 3 may be used for controlling the supply of gas to all burners; couple 4 may be used for checking the operation of couple 3 on the gas control; couple 5 may be used for controlling the flow of cooling air to the jets 59, while couple 5 may be used for checking the control of couple 6.

'Couples 3, 4, 5 and 6 may be connected to meters reading the instantaneous temperature registered by these couples; couples I, 2, I and 8 may be connected to recording meters which record the temperature at these points and act as a check on the temperatures indicated by the other couples so that a uniform temperature may be maintained along the entire length of the bath.

The operation of the temperature control is such that when the temperature of the bath drops below a predetermined temperature which, for example, may be 500 F., all of the burners 31 are turned on and all of the air jets 59 are turned be provided for igniting the burners. Or, if

desired, the burners may burn with a small flame, which generates practically no heat, when the burners are in their ofi condition, ther eby obviating the necessity for pilots.

It is obvious that the present construction may be used to carry out various forms of heat treatdescribed. 5

9,116,060 ment. In addition to the heat treating method disclosed in the copending application above referred to, the following heat treating method. which has been found'to be especially effective for certain kinds of steel rails giving certain desired structural The entire rail may be heated in a special heating furnace throughout its entire section to a point above its criticalternperature', for example, to about 1500 F. This rail is then removed from the heating furnace and is immersed head downwardly in the bath'as indicated inFlg. l with the base flange resting on the supports 64. The level 'of the bath 56 may be such as to reach a point characteristics, will be briefly on the web of the rail, as indicated. This point may be the neutral axis of the rail, or in some cases, may be about one inch below the bottom of the head:

The bath is preferably composed of% lead and A antimony by weight and may be maintained 1 at a temperature of about 500 F.

If desired, a, one-half inch layer of crushed coke, indicated by 8|, may float on the bath;

consequently makes the temperature control easier. Furthermore, there is less volatilization with a small amount of bath material.

The provision of a small cross section bath assists directly in the quenching effect. The immersion of the rail at approximately 1500 into the bath at 500 causes eddy currents in the bath which keeps the liquid circulating. The centering of the head of the rail in the bath with substantially equal amounts of lead under the head and on the sides of the head equalizes the heat treatment on the top and side faces of the rail head. I

Referring to Fig. 5, if desired, positive means may be provided to circulate the moltenbath to accelerate the heat flow from the rail, thereby increasing the quenching rate to obtain greater hardening. For example, an external circulatory system including 'a pump may be provided for withdrawing the molten bath from one end of the container and returning it; after cooling in a suitable cooling device, to the other end.

Thus, a lead'pot is provided which is comparatively inexpensive to construct and comparatively inexpensive to operate. The distribution of heating burners along the length of the pot and the constant temperature control reduces the warping of the pot and also reduces warping of the rail. The comparatively small volume of bath material minimizes the investment in bath material and provides easier temperature control.

While certain novel features of the inventionv 1. A quenching tank comprising an elongated framework having an elongated furnace chamber, the bottom and side walls of the furnace chamber being made up of fire-brick, an elongated bath-containing pot supported by said framework above the open top of said furnace chamber, said furnace chamber having a plurality of fuel burners applied thereto and distributed along the length of the furnace for heating said pot. a plurality of air jets distributed along the length of the furnace, and means for mounting said jets adjacent said pot and above the furnace ,walls to.

cool said pot.

2. Aquenching tankfor heat treating steel rails and the like comprising a comparatively long shallow container holding a quenching bath, setsof spaced supports near opposite ends, each set being sumciently long to contact a substantial length of the base flange of the rail to reduce cambering, the supports of each set being spMedapart to permit vertical insertion of the rail head therebetween an immersion of the head into the quenching be. said sets being spaced apart longitudinally and the rail being unsupported between said sets, said container and saidsupports both being stationary. said supports being lothat, with the base flange of the rail resting upon said supports, the head of the rail isimmersed in the bath.

3. A quenching bath for long steel sections and the like comprising a comparatively long narrow container for holding the bath liquid, means for heating said container and separate 7 cated above the container and so related thereto means for cooling said container, both said means being distributed along the length of the container to uniformly control the temperature of the bath liquid.

4. A lead pot comprising a comparatively long and shallow container, 9. series of individual heat framework having an elongated furnace chamher, the bottom and side walls of the furnace chamber being made up of fire-brick, a bath-containing pot comprising a half of a roundiron pipe supported by said framework above the open top of said furnace chamber, both side walls of said furnace chamber having a plurality. of fuel burners disposed therein and distributed along the length of the furnace, a plurality of air jets distributed along the length of the furnace and located on opposite sides of said pot and above the furnace walls for cooling said pot, said pot having sets of rail supports, said supports supporting the base flangeof a rail immersed head down in the bath, the content of said pot being of small cross section, and a plurality of thermocouples secured to the side of the pot and distributed along the'length of the pot, said thermocouples being immersedin the bath between the side walls of the pot and the side of the rail head

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