US2383307A - Heat-treating furnace - Google Patents

Description

E. K. HANSEN 2,383,307

Aug. 21, 19.45.

HEAT-TREATING FURNACE 6 Sheets-Sheet 1 Filed June 7, 1941 I! T we WITNESSES: I

I INVENTOR 7n2erK/Va/25ea f 7: WM

Au .21, 1945. l E HANSEN 2,383,307

HEAT-TREATING FURNACE Filed June 7, 1941 6 Sheets-Sheet 5 INVENTOR' 7merA. /an.sen

ATTORNEY Wnussss's:

Aug. 21, 1945. E. K. HANSEN HEAT-TREATING FURNACE Filed June 7, 1941 6 Sheets-Sheet 6 gvlTNE s ES: A

ATTORNEY Y Patented Aug. 21, 1945 I 2 ,383,307 HEAT-TREATING FURNACE Elmer K. Hansen, Edgewood, Pa., assignorto Westinghouse Electric Corporation, East Pittsburgh, Pa... a corporation of Pennsylvania Application June '1, 1941, Serial No. 397,007

3 Claims.

My invention relates to heat-treating furnaces,

and more particularly relates to heat-treating furnaces for heat-treating, ,in a a short heattreating cycle, a large charge or batch comprising a plurality of spaced, suspended, metallic sheets, the heat-treating including heatin'g.and then quenching the charge.

It is an object of my invention-to provide a heat-treating furnace comprising a closed heating-chamber and a quenching means under the heating-chamber, the furnace being so constructed that a charge to be heat-treated therein is first. moved between the heating-chamber and the 'quenching means, then raised by suitable charge-moving means into the heating-chamber for heating, and after heating dropped quickly into the quenching means below the heatingchamber in such manner that the interval of time during which the charge is in transit between the heating-chamber and the quenching means is minimized. Y

It is a primary object of my invention to provide a heat-treating furnace having a wall-structure defining a heating-chamber with a chargingopening at the bottom, and a quenching means under the heating-chamber, the quenching means being sufiiciently below the heating-chamher to allow a supporting means to be interposed between them for receiving a loaded charge-rack from which the charge of suspended plates or sheets is supported, the charge-rack being movable on the supporting means from a position between the heating-chamber and the quenching means to a positionlaterally away therefrom so that the charge-rack can be conveniently loaded or unloaded. I

In the form of my invention which is at present preferred, the charge-rack, from which the metallic sheets are suspended, is sli-dable on the sup porting means. The charge-rack and the supporting means are provided with cooperating rail and roller devices permitting the charge-rack to be easily moved to and from a position underneath the chargingmpening of the heatingchamber, the cooperating devices maintaining the charge-rack aligned on its supporting means so that the supporting means also serves as a guiding means for guiding the charge-rack during its movements.

A feature of my invention resides in providing the supporting means for the charge-rack with a section underneath the heating-chamber, which is easily movable out or the path of a. charge moving between the heating-chamber quenching means.

and the Another feature of this preierred furnace comprises a suitable closure means for the bottom tion for the charging-opening, the rolling motion of the closure as it approaches or leaves the charging-opening including combined relatively vertical and horizontal directional components,

with the vertical components being relatively larger when the closure is nearer the chargingopening and becoming progressively relatively smaller as the closure moves away from the charging-opening and the horizontal components being relatively smaller when the closure is nearer the charging-opening and becoming gradually larger as the closure moves away from the charging-opening, until finally the closure moves substantially laterally only when it is below the charging-opening and clear of the wall-structure.

-It is another object of my invention to provide a means for suspending a sheet to be heat-treated, the means securely locking the sheet at its upper edge.

Many objects, features, innovations and advantages of my invention, in addition to those mentioned above, will be apparent from the following description thereof which is to be taken in con junction with the accompanying drawings; In these drawings, which are on. considerably varying scales,

, Figure 1 is a lengthwise vertical view, vpartly'in section and partly in elevation, of a heat-treating Fig. 2 is a transverse vertical sectional view of the furnace, taken substantiallyalong the line 11-11 of Fig. 1;

Fig. 3 is a horizontal sectional view of the: furnace, taken substantially along the line III-Z-III of Fig. 2;

Fig. 4 is an elevational view, with a small. part shown in vertical section, of a closure for the bottom charging-opening of the furnace;

Fig. 5 is a vertical sectional view, transverse to the view of Fig. 4, of the closure;

Fig. 6 is a plan view of one of the sets of rail means on which the closure is moved to and from closing position for the charging-opening; 0

Fig. 7 and Fig; 8 are an elevational view and an end view, respectively, of this set ofthe rail means.

Fig. 9 is, a-plan view of a charge-rack from which the metallic sheets are suspendingly supported;

Figs. and 11 are a lengthwise sectional view and a transverse sectional view, respectively, of the charge-rack from which the metallic sheets are suspended in spaced substantially parallel relation;

- Fig. 12 is a detail view of a rack-hook engaging I detail of Fig. 14; and

Figs. 16, 17 and 18 are, respectively, a plan view and elevational views in planes at right angles to each other, of a wedging pin for securing a metallicsheet in the slot of the barof Fig. 13.

The furnace which is herein described is particularly useful for the heat-treating of metallic sheets comprising aluminium or aluminium alloys, and particularly sheets having pure aluminium protective coatings. In the heat-treatment of such aluminium sheets, time is an all impor-" tant element in the heat-treating process and my preferred form of furnace herein described is built so that the sheets can be heated in as short a'time as possible in order to prevent the diffusion of alloying elements of the inner core of the sheet out into the'outside coating of the sheet, and to permit quenching in as short a time as possible, a few seconds at the most, after the sheets have been suitably heated.

Referring more particularly to the drawings, and in particular to Figs. 1, 2 and 3, in which smaller details are either omitted or shown somewhat schematically because of the scale of the drawings, the furnace consists of awail-structure, indicated in its entirety by the reference numeral I, comprising side walls 2 and 4, end walls 6 and 8, and a top wall I0, defining a heating-chamber 12. The wall-structure I is built of any suitable refractory and insulating brick, and is encased in a gas-impervious metallic outer shell I4. The Wall-structure l is supported by a suitable structural framework, indicated in its entirety by the reference numeral l6, at a considerable distance above a quenching means l8 which can be disposed in a floor or foundation 28 in which the structural framework l6 may be secured.

The structural framework 16 comprises structural I-beams 22 at one end of the furnace and I-beams 23 at the other end of the furnace, the

I-beams 22 being spaced from the I-beams 23'to provide an unobstructed space. along the length of the furnace for receiving a. charge to be heattreated in the furnace, which is loaded into the a length which is somewhat greater than the short dimension of the heating chamber l2, the heating chamber being preferably rectangular.

' Each of the rail-sections 36 has one end pivoted at 38 so that both sections 36 of the track- rails 32 and 34 can be dropped into vertical position, the other ends of the rail-sections 3'6 being provided with any suitable means whereby they can be locked or latched in raised position in alignment with the stationary parts of the elevated track- rails 32 and 34. The stationary parts of the track- rails 32 and 34 extend beyond both sides of the furnace so that a charge-rack can be easily accommodated on-each side of the furnace away heating-chamber l2 through a bottom chargingopening 24 closed by a closure indicated in its entirety by the reference numeral 26.

The closure 26, which will be described in somewhat greater detail later, includes a plurality of wheels ridable on rails at the ends of the furnace, two sets of rails 28 and 30, respectively, being provided.

The sheets to be heat-treated in thefurnace are supported by a, charge-rack 3| which is shown in Figs, 9, 10 and 11, the charge-rack being ridable on a supporting means comprising a-track from underneath the heating-chamber, enabling a second charge-rack to be loaded with sheets while a, loaded charge-rack is undergoing heattreatment.

The closure means 26 is moved to and from closing position by any suitable closure-operating means which, in this embodiment, comprises a pair of suitably-controlled pneumatic cylinders 48 at the ends of the closure means, the pneumatic cylinders being pivotally supported as at 44, and of such type as to keep the closure 26 at the extremity of its movements. The piston rods of the cylinders are pivotally connected to clevises 46 on the closure 26.

In .order to raise a loaded charge-rack which is supported on the rail-sections 36, a chargemoving means is provided comprising a hoisting means having its operating mechanism on the top of the wall-structure i. The hoisting means includes a reversible motor 52 suitably geared to drive a cable drum 54 around which are wrapped two pairs of cable chains. The cable drum 54 winds and unwinds a pair of spaced cable chains 60 passing over a chain guide-drum 62 at one end of the furnace,-and winds and unwinds a pair of similarly spaced cable chains 64 passing over a chain guide-drum 65 at the other end of the furnacer Each of the cable chains passes through suitable hollow corner tubes fixed in the top wall of the furnace, and terminates in a hoist-hook 66 for engaging an associated rack-hook 68 secured,

to the charge-rack, so that the, hoisting means can suitably raise and lower the charge-rack without significant swaying of the loaded chargerack. The cable chains are provided with short solid tubes somewhat loosely. fitting the fixed tubes in the top wall when the charge-rack is in sheets suspendingly supported from this chargerack, the rack is moved to a position on the movable rail-sectiohs' 36, which are underneath the heating-chamber l2. By controlling the pneumatic cylinders 40, the closure means 26 can be moved to a position on the substantially hori' zontal portions 10 of the rail sets 28 and 38, thereby uncovering the charging-opening 24. The cable chains of the hoisting means can then be lowered and the hoist-hooks 66 made to engage the rack-hooks 68 so that the charge-rack and the metal sheet charge thereon, under the charging-opening 24, can be raised into the heats terference.

ing-chamber I 2, after which the closure 26 can be moved to closing position for closing the charging-opening 24. In the heating-chamber I2. the

charge is heated by means of electrical heating means I4, or other suitable heating means, mounted on the side and end walls of the wallstructure I.

Since aluminium alloy heating sheets are preferably heat-treated by heating to a relatively low temperature, say in the neighborhood oi 950 F., it is desirable to provide convection heating in the heating-chamber I2. To this end suitable bafiies I6, at the sides of the furnace, and baflies I8, at the ends of the furnace, terminate short of the top and bottom of the heating-chamber I2 so that air-recirculating paths are provided which may be downwardly between the baffles and upwardly between the baflles and the side and end walls 2, 4, 6 and 8, of the heating-chamber, where the circulating air is heated by the heating means I4. The air may be recirculated by fans 80 secured to shafts 82 extending through the top wall II! of the wall-structure I, and driven, through suitable belting, by motors 84. The shafts 82 may be supported in any suitable bearlugs and provided with packing glands to limit leakage of atmosphere. An apertured' top baflie means 88 is provided across the tops of the bailles I and I8 for guiding the air flow along the top of the heating-chamber, the top baflle means 86 rectilinearly blowing the air downward through the suspended metal sheets carried by the chargerack, the charge-rack comprising a substantially open framework to permit the air to passfreely between the sheets.

While a loaded-rack is being heated, the-movable rail-sections 36 of the elevated track- rails 32 and 34 can be lowered so that the loadedrack, after heating, can be lowered without in- After the loaded charge-rack has been heated for the proper time, the closure 26 is moved quickly to open position, and at the same time the heating means I4 and the fans 80 are deenergized, and the hoisting means operated to lower the loaded charge-rack into the quenching-liquid of the quenching means 20 at a high rate of speed. In an actual embodiment of the furnace described, only about seven secends are consumed from the moment the closure 26 starts to open until the loaded charge-rack is completely immersed in the quenching-liquid within the quenching means. After the loaded charge-rack has been quenched it is raised to clear the elevated rail- tracks 32 and 34 so that the movable rail-sections 36 can be .moved back into alignment with thestationary sections of the elevated track- rails 32 and 34; The loaded charge-rack is then lowered so that the chargerack rests on the elevated track- rails 32 and 84, on which it is moved to one side for unloading. After the heat-treated loaded charge-rack has been moved to one side on the track- rails 32 and 34, a second loaded charge-rack on the other side of the track- rails 32 and 34, which has in the meantime been prepared, may be moved to proper position under the charging-opening 24 80 being provided with short cylindrical tubes 88 in which the fans 80 are disposed for substantially to avoid interfering with vertical movements of the loaded charge-racks; and are above the trackrails 32 and 34 a distance sufhcient to clear a charge-rack on the track-rails. In order to limit the time for loading and unloading the furnace it is desirable to move the closure 28 laterally of the length of the furnace, which is the shortest dimension of the charging-opening; and in one particular furnace, the widthof the chargingopening was between ,4; to it of its length.

If .the furnace is of relatively large size forheat-treating large vbatches at one time, the closure means also becomes large and long and since the rails upon which the closure rides are at the ends of the furnace, it is desirable to provide means which will confine the closure movements to predetermined tolerances so that ithe closure will properly seat with respect to the wall-structure I, for closing the charging-opening 24. Such means is especially desirable if gas-sealing means are to be provided between the wall-structure I and the closure. To this end. the closure and the closure-supporting means, comprising the. railsets 28 and 30, are provided with means. for guid ing the closure and for causing the closure to seat properly in the charging-opening 24 of lthe furnace.

With reference also to Figs. 4 and 55, the 010-" and claimed more particularly in the Joint application' of P. G. Lessman and A. Krauscope,

Serial No. 396,996, filed concurrently herewith V and assigned to Westinghouse Electric 8: Manufacturing Company. This joint application has become Patent No. 2,354,127, dated July 18, 1944. The gas-sealing means generally comprises aninverted U-shaped set of members I II2 slidable for loading into the heatingchamber I2, and

the heat-treating process repeated for this rack while the heat-treated sheets carried by the other rack are removed and new sheets, which are to be heat-treated, are suspended therefrom,

The rail- sets 28 and 30 are spaced apart a I distance along the length of the furnace suflicient between the flanges 94 and 98 and spring-pressed upwardly so that in closing position of the closure the inverted U-shaped members press against a bottom door frame I04 along the bottom of the vertiiial'walls 2,4, 6 and 8 of the wall-structure I, the door frame I04 being protected against heat within the heating-chamber I2 by the re-- fractory bricks of the wall-structure, which ex tend beyond the inner edges of the door frame. The bottom side of the closure is provided with a pair of forward or leading flanged wheels III] and, H2 at the corners of the forward side of the closure, considering the forward side as that side closest to the wall structure I when the closure starts to move from open position to closing position. A second pair of rear, flanged wheels "4 and H6 is provided at the corners of the rear side of the closure; the gauge of, or the distance separating, the wheels I I4 and I I6 bein -less than that of the wheels I III and H2. The

wheels are journaled in any suitable manner by any suitable means secured to the closure framework 92. The front wheels III) and M2 ride on inside rails H8 and I29, respectively, of the railsets 28 and 30, and the rear wheels "I I4 and H6 ride on outside rails I22 and I24, respectively. The rails are shaped so that the closure means, in moving from opening to closing position, is

. fine the guide rails on as shown in Fig. 7.

The inner rails'and the outer rails of both railsets 28 and 30 are designed so that the front and rear sides of the closure are raised in the same direction 'at the same time therebymaintaining the closure substantially horizontal.

In order to keep the closure means properly aligned at all times during its movement so that it will suitably mate the wall-structure I about its charging-opening 24, the rail- sets 28 and 30 are provided with a gear rail I26 and a gear rail I28, respectively, in the form of a rack bar shaped to correspond to the associated rails' H8 and I20, the gear rails I26 and I28 being provided with gear teeth. A gear I meshes with the gear rail I26 and a gear I32 meshes 'with the gear rail 8 I28, the two gears being secured to a common shaft I34 rotatably supported by the closure framework 82. The gears. I80 and I32 are in mesh with the gear: rails j I26 and I28 in all positions of the closure 26.

During movement of the closure 26, the meshing of the gears I30 and I32 with the gear tracks I26 and I28, causes both ends of the closure to move in the same direction at the same speed. If the closure is properly positioned initially, the gearing between the 'closure'and the closuresupporting means, including the gear rails I26 and I28, will maintain the alignment of the closure.

The charge-rack 3| and its appurtenances for suspendingly supporting the metallic sheets to be heat-treated, are shown in greater detail in Figs. 9 throughlB. The charge-rack comprises an open rack-frame I40 which is rectangular in shape and fits within the baflle structure of the heating-chamber I2. "I'he rack-frame I40.

comprises opposite-long; frame sides I42 and I44, and also frame ends I46 and I48, the sides and ends being of suitable structural forms, to provide the necessary strength of the rackfor the full length of an end of the rack-frame and has down turned flanges I54 and I56 to conthe elevated roller trackrails 32and 34.

Each of the frame sides I42 and I44, and each of the frameends I46 and I48, is provided with a horizontal inwardly-extending leg I51 terminating in an upstanding leg .I58'to form a channel. Somewhat inward of the frame end I46, the edges of the upstanding legs I58 of the frame sides I42 and I44, slidably support a cross-bar rack-frame. Each cross-bar ing the associated slotted bar I12.

A plurality of other cross-bars I65, each of which is similar to the cross-bar I69 are slidably supported by the frame sides I42 and I44 at a spaced interval along the length of the I66 has a depending leg I66, similar to the leg I 68 of the crossbar I69, thelegs I66 also having space holes I64.

The holes I64 in thediflerent legs of the slidably-supported cross-bars receive wires I68 which also pass through holes I in the upper part of a slotted'clip bar I12, each wire being looped and the loop twisted ,supporting metallic sheets from the framework securing means for f'securing thasheet in the slot I14. Consequently, a side I18 'of the slot I14 may be considered to have an enlarged indentation forming the major part of the hole I16, and .the other side I80 of the slot may be considered as having a smaller indentation I82 or may be smooth if the hole I16 is sufliciently ofl' center with respect. to the slot I14. The'bar I12 is somewhat resilient so that the sides of the slot are spreadable under pressure and can be maintained spread under pressure, the bar resisting this pressure and tending to force the 7 slot sides back to normal position.

For securing a metallic sheet in place its edge is placed within the slots of a plurality of spaced bars I12 which are suitably aligned to receive the edge of the sheet, and a securing means comprising a securing pin or wedge I90, of special shape, is forced or driven into each hole I16 thereby wedgin g or pressing the sheet S against the slot sides corresponding-to a slot side I80 so that the sheet is frictionally held in place.

The number of bars I12 used to support a single.

sheet will of course, depend upon the length of the edge of the sheet to be fastened.

Asecuring pin I90 is more particularly shown in Figs. 16, 17 and 18 and comprises a round rod of slightly less diameter than the holes I16. The pin is formed with right angular sides I92 and I94, the side I94, which may havea rounded tip,

* being adapted to be inserted in a hole I16 and I59v which comprises an angle bar I60, between the frameflsides I42 and I44, and metal sup- .witha down-turned lug I 62 disposed within the channel of the associated frame side, so that the cross-bar I59, although slidably supported by the frame sides I42 and I 44, is interlocked with the frame-sides. The angle bar I has a depending leg I63 provided with a plurality of I spaced holes I64.

the side I92 providing a convenient means by which the pin is inserted or withdrawn. The pin-side I94 is tapered to provide an end easily insertable in a. hole I16, the taper having a surface I96 starting at aboutthe vertical diameter of an end of the pin-side I94 which diameter is parallel to the-pineside I92, andterminating near the pin-side I92, as shown in Figs. 16 and 17. The taper surface I96 is provided with a small central ridge I98 for better forcing the sheet S against the slot side I80. In cases where the slot side I is provided with a smallindentation I62, the ridge I98 may force the metal of the sheet S. into this indentation so that the sheet is somewhat locked to the bar I 12. The cross-bars I59 and I65 can be slid on the frame sides I42 and I44 to correspond to the length of ,the metal sheets to be heat-treated, and more than one sheet can be supported in substantially a single plane.

The charge-rack 8| is further provided with spaced cross members 200 to which the rackhooks 68 are secured in spaced relation, the

for flexibly" suspend-- The wires and slotted bars form a suspending means'for charge-rack of the preferred embodiment having four such rack-hooks, one near each corner thereof. Each pair of associated rack-hooks 68 on a cross member 200 has secured thereto and between them an angle bar 202 having a relatively wide horizontal leg 2%. A small retainhoisting means and the charge-rack for substantially vertically raising and lowering the charge-rack in .a manner to maintain the charge-rack substantially horizontal.

While I have described my invention in a form which is the preferred embodiment thereof, it

is obvious that many modifications may be made thereof and equivalent elements substituted therein.

I claim as my invention:

1. A heat-treating furnace comprising a heating-chamber having a charging-opening, a movable closure for said charging-opening, furnace loading and unloading means comprising a charge-rack having means for suspendedly supporting a charge comprising a plurality of spaced suspended metallic objects, rail means for movably supporting said charge-rack so that a loaded charge-rack can be moved to a position in substantially vertical alignment with said charging-opening, said rail means including a section directly below said charging-opening, quenching means below said section of said rail means, charge-moving means for lowering a loaded charge-rack from said heating-chamber into said quenching means, and means for pivotally supporting an end of said section of said rail means so that said section can be swung to a position in which it will be out of the path of a loaded charge-rack being lowered into said quenching means.

2. A heat-treating furnace comprising a wallstructure defining a heating-chamber having a bottom charging-opening, a rack means comprising a substantially rectangular framework and a plurality of members secured to said framework, said members having rack-hooks above said framework, a rack-bar secured across a pair of said rack-hooks, said rack means having charge-supporting means comprising spaced depending bars for suspendedly supporting metallic objects, spaced rails below said charging-opening, on which said rack means is supported to be movable to or away from a position under said charging-opening, hoisting means comprising a plurality of cables passing through an upper section of said wall-structure, and terminating in hoist-hooks, and a'hoist-bar across a pair of said hoist-hooks, said hoist-bar and said rack-bar providing interlocking means for preventing said rack-hooks from slipping from saidhoist-hooks, said spaced rails being spaced apart a distance sufiicient to permit said suspended sheets to be raised between them, said rails also having a movable section movable out of rail alignment for permitting said hoisting means to lower said rack means and the charge thereon, below said spaced rails.

3. A heat-treating furnace comprising a. heating-chamber having a bottom charging-opening, a quenching means under said heating-chamber, supporting means comprising a rail means between said heating-chamber and said quenching means for supporting, above said quenching means, a charge to be moved into said heatingchamber, means for moving the charge from said supporting means into said heating-chamber, and for dropping the charge from said heatingchamber into said quenching means, said rail means comprising a pivoted section, said pivoted section being placea'ble under said heatingchamber for supporting a charge directly below said heating-chamber, and movable out of the path of a charge being dropped from said heating-chamber into said quenching means.

ELMER K. HANSEN.

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