US2391970A - Continuous furnace - Google Patents

Description

Jan. 1, 1946. D. J. HOLLERAN ETAL 2,391,970

CONTINUOUS FURNACE Filed Dec. '7l 1943 '7 Sheets-Sheet 1 l l l l l lll l l l lIIL l l l l m /bm N\ l INVENTORS. Dor/nunc Heumann lJosEPH -JCERNY BY Jan. 1, 1946. D. J. HoLLl-:RAN E-rAL 2,391,970

CONTINUOUS FURNACE Filed Deo. 7, 1943 7 Sheets-Sheet 2 oooooo'oo oooooooo ooooooo INVENTQRS.

mc L HoLLERAN QJ. CERNY BY m7/ Jan. l, 1946. D. J. HOLLERAN ETAL CONTINUOUS FURNACE Filed Dec. 7, 1945 7 Sheets-Sheet 3 INVENTORS.4 DoMlmc Heumann JoszPH .CERNY BY Jan- 1, 1946. D. J. HOLLERAN ETAL I 2,391,970

CONTINUOUS FURNACE Filed Deo. '7, 1943 7 Sheets-Sheet 4 INVENTORS. Dommlc Hammam A05am-4 .CERNY Jan. l, y1346.

D. J. HoLLE-RYAN ErAL 2,391,976

cQNTINUoUs FURNACE 7 Smets-sheet 5 Filed Dec. '7, 1943 INVENTORS.

DoMlNlc 'J'.HOLLERAN JosEPH J- CERNY D. J. HOLLERAN ETAL CONTINUOUS FURNACE Filed Dec. 7, 1945 '7 Sheets-SheefI 6 Jan. 1, 1946.

Jan. 1 1946.

D. J. H OLLERAN ErAL CONTINUOUS lFURNACE Filed Dec. 7, 194s '7 sheets-sheet 'r INVENTORS Domme J- HDLLERAN JosEPH JCERNY 35:7?

Patented Jan. l', 1946 Berwyn, tional Loek Washer Ill., assignors'to The Na- Company, Newark, N. J.

Application December "l, 1943, Serial No. 513,314

Claims.

Thisl invention relates to a heating furnace and has for its principal object the provision of a furnace having a low first cost. yet one whichis highly emcient in every way-and by eilicient we mean a furnace which will produce a greater amount of work more quickly, uniformly and economically than any other furnace with which we are familiar.

- By way of illustration but not of limitation, the furnace to be described herein is especially adapted for use in heat-treating devices that have been covered with enamel.

Another object of our invention is the provision of a furnace that may be operated entirely by one person located at one end of the furnace where both the loading and unloading operations are carried out.

Another and very important objectV of our invention is the provision of means for rotating the object while it is going through the furnace in order to get more Imiform heating and, in the case of drying enamel, a more uniform coating.

Another object of our invention is to provide a furnace in which more gradual cooling of the devices which have been heat-treated is attained without increasing the length of the heating chamber of the furnace.

These and other objects will be apparent to one skilled in this particular art after a consideration of the advantages to be hereinafter set forth.

rods will turn the resistors, although it may not be at the same speed as the turning of the rods, but the turning will be suilicient to prevent the running of the enamel to the, bottom side of the resistor, which it would do if the rod and resistor did not turn. Furthermore, in the event of overheating, the turning of the rod prevents the enamel from running off the resistor completely. In the case of resistors, if they are provided with a number of tapsto get different resistances from the same unit, it will be found preferable 'to enamel the rods to increase the One primary advantage is that a construc- A tion has been. developed by which the work is carried on or suspended from rods that are positively turned while these rods and work are passed through the furnace. By turning the rods, they are not so susceptible to bending due to the heat Within the furnace, whereby a smaller diameter rod may be used, thereby reducing the loss of heat'which would be absorbed in a larger diameter rod, and'also reducing the load required to move the rods through the furnace.

A further advantage is that by using a rotatable rod, aheavier coating of enamel, when the devices have been treated with enamel, may be applied to the devices for the reason that when the mature temperature of the enamel is approached, the rotation of the rod prevents molten enamel from gathering at the bottom side of the devices; such as resistors, which are being treated, and thereby produces structures having a uniform thickness of enamel. Even though the resistors, which are slid onto the rods, are loose thereon, the mere turning of the heat-resisting alloys.

friction between 'the rod and the resistor being.

treated.

Another advantage of the construction herein described is that the rods are easily replaceable and as a result do not have to be made of an alloy or heat-resistant metal such as those which contain nickel, chromium or other metals that act to slow down oxidation under higher temperature, but may be made of ordinary steel. Another advantage derived from our construe,- tion is that the rods are carried by a conveyor or chain which runs on the outsidegof the chamber portion of the furnace, thereby reducing to a minimum the loss of heat which is absorbed by a conveyor or lchain passing through the furnace, whereby this heat that is absorbed is dissipated when the conveyor passes out of the furnace on its return trip. While some heat is taken up by the conveyor or chain on what may be termed the heating side, this is relatively low and hence adds to the economy of the furnace and increases the-life of the conveyor orl chain. Furthermore, a cheaper metal such as ordinary steel may be used in the conveyor rather than Furthermore, adjustments are provided whereby the rods can be maintained in* their rela-- tive horizontal position with respect to the top and bottom heating coils of the funace.

Another advantage of the construction to be herein described, is that the steel casing around the furnace lining of reproof bricks is held together in places which will allow expansion and contraction to take place at controlled points, whereby readjustment vof these points may be made if necessary. This adjustment or control of the casing is for the purpose of maintaining the longitudinal opening through which the support rods pass into the. furnace.

Another advantage derived from our construction is the method of holding the heating coils at both the top and bottom of the'furnace. The

bottom coils are mounted on tapered bridges or supports of suitable ilre-and-heat-reslsting material, these supports being spaced longitudinally of the furnace and close enough together to prevent the electrical heating coils from sagging under heat. Because of these bridges or supports being tapered upwardly toward the heating coil or coils, any enamel that may fall oi the units being treated will readily clear the coils and pass down the tapered surface to the bottom wall of the furnace.-

The top supports for the heating coils are preferably of high heat-resisting material and terminate in loops just below the top of the furnace ure l, with the front cover plate and other parts removed to show the conveyor or chain carrying the rods as they come up from the bottom of the furnace for unloading and loading prior to going into the furnace chamber.

In the drawings, wherein like numbers refer to corresponding parts, the framework F is made up of a steel construction of any suitable charchamber and the heating coils are suspended in these loops along the ceiling of the furnace chamber, thereby giving maximum radiation all along the heating coils, it being understood that these top supports or holders are spaced longitudinally in number to prevent sagging of the heating coils.

Another advantage of our construction is that the heating coils are so designed that each is a unit in itself, extending the entire length of the furnace, and is adapted to take the full voltage of the power supply available in the factory or place where the furnace is being'used, without the use of transformers, contactors, relays, etc., it being understood that each heating unit is provided with a control device, eithermanual or automatic, so that one or more of the heating coils may be connected in parallel to control the heat within the furnace chamber in the manner to be hereinafter described.

A further advantage, of our construction is that the take-up oradjustment of the conveyor or chain takes place' automatically due to any var'- iations caused by expansion or contraction of the conveyor or chain.

Another advantage of our construction is that since one section of the conveyor and the rods carried thereby comes back to the loading end beneath the furnace, this permits more gradual cooling of these parts than on furnaces heretofore known to us, and since the parts treated, as well as the rods are sufliciently cooled at the acter, such as horizontal supports i, vertical support members 2, cross-members 3, all of which may be made of angle irons, and cross-channel irons i and 5 which are held together by tie rods 6 to which special reference will be later made.

Since the framework per se, outside of one detail which will be mentioned later, forms no part of time they reach the loading end, they are very back end of the furnace showing the conveyordriving means. It is to be understood that the intermediate portion of the furnace between the left-hand end of Figure 1 and the right-hand end of Figure 2 is similar to these adjacent portions.

Figure 3 is a section on the line 3-3 of Figure 2.

Figure 4 is a section on the line 4 4 of Figure 3.

Figure 5 is a view on the line 5-5 of Figure 2.

Figure 6 is a view on the line 6 6 of Figure 11, or of a portion of the furnace on the back side of the forward end of Figure l, showing the manual control switches for the heating units.

Figure 7 is a view of the cover plate looking at the back end of the furnace (see'Figure 2).

Figure is a front view of the front cover plate (see Figure l) Figure 9 is a section on the line 9-9 of Figure 2.

our present invention, further description of the same seems to be unnecessary. The'framework F carries a conveyor 1, preferably in the form of an endless chain, the links of which on what may be termed the furnace-chamber side of the conveyor, are carried in a channel iron 8 or two angle irons which may be mounted to simulate a chanchain has its rungs I3 in engagement with a rodv lli extending longitudinally of the furnace. The

rod l is carried by supports i5 mounted on frame bars i6. Additional supports are provided by rods il on similar Supports i5 carried by the same frame bars i6. The rod I1 is engaged by holders i8 that are carried by certain link members I9 and 20 which form part of the conveyor or chain. The projecting ends of the link members I9 and 20 carry a sleeve 2l that supports the end 22 of the holder I8, and on the end 22 is fastened a gear 23, by a tapered key l0. The gear 23 is adapted to mesh with the teeth of a rack 24 supported by a frame member 2'5 which may also carry parts 26 that carry an adjusting screw 21 for a purpose which will be later described.

The holders i8 are hollow and are adapted to have support manswhich, in the form shown, are rods 28 that are fastened to the holder by any satisfactory means as by a set screw 29 whereby the rod 28 may be projected more or less through the holder i8. It may be mentioned h e e that the outer ends of the rods 28 are suppor d on rods l1 carried by the support I5 on the frame member i6. As shown in Figure 3, the holder projects toward or into a relatively narrow slot or opening 30 which extends longitudinally the entire length of the furnacev along the conveyor side. Thus the adjustment of the rod or rods 28 or `their length may be such as to be positioned between any group of resistance units 3| mounted ing on the resistance units 3l, will pass downwardly therefrom and onto the tapered surface of the supports 32 to the bottom of the furnace. The

direct of the opening 30,' .the bricks 44 and 45 are in place by angle irons 4 5 and 41. 1

forming to the circular surface ofthe units 3|,

of heating unit used and the mannerrin which theyaretobe Itwillbenotedfrom Figurethatthefeedbusbariisconnectedto and arms extending through holes in the supports4 32, with bent-over ends 34 positioned in recesses in the bottom of thesupports 32 (see Figure 3).` It isto be understoodthat the supports 32 are spaced apart a distance so that there will be no sagging ofv the units 3| between the supportsf also, the holes are such that the holders maybe easily removed and this also applies tothe top hangers.

'I'he top holders or hangers for the heatingunits have circular ring portions 35 conforming to the circular portion of the continuous resistance units 3| and bent-over ends 35 positioned in a recessV in the top bricks with which they are associated. Preferably these top supports 35 are ofv high heatresisting metal and since the heating coils are suspended in the said ring or loop of each support member, maximum radiation is given all along the heating coils. These supports are preferably spaced longitudinally of the furnace chamber, the same as at the bottom, so as to prevent sagging of the heating coils.

It may be noted at this point that the furnace chamber is made up of a steel casing 31 held together with corner angle irons 38 and intermediate angle irons 39 and 40 bolted together by bolts 4I. Side channels 42 are also used, being held in position by cross-bolts 43.

Within the casing 31, are positioned fire `and heat-resisting outer bricks 44 and inner bricks 45.

On the conveyor or chain side, adjacent the walls held' Passing across the top of the furnace and resting on the angle irons 38, are a plurality of the lic make the width of the opening .30 irregular, this irregularity may be corrected by adjusting the tie rods B.

In order to take up for expansion and contraetion with the conveyor or chain 1, the front sprocket wheel 48 is mounted on a slide 49 that is slidably mounted on a frame member on the chain sideof the furnace. Pivotally mounted on a rod 50 y which extends transversely across the furnace at the front end is a cam 5i in engagement with a part 52 which-may be attached to the slide 49 or movably connected therewith. Fastened to the rod 50 on opposite sides of the furnace, 'are arms 53 having links 54 connected by adjustable studs 55 to weights 55 positioned in cylinders or recep- 4 tacles 51 so that any expansion or contraction of the chain 1 will move the slide 49 through the sprocket wheel 48 to move the cam 5l, thereby moving the weight up or down. Thus the weight 58 will maintain a steady pressure on the cam 5|. and will keep the chain in proper working condition.

Mounted on the back side and at the loading end of the furnace, are two switch panels 53 and 59. each panel having ve switches 60 and 6| that are adapted to control the electric circuit through each of the resistance units 3l. The number of allofthe switches Il and Il andtheyinturn run toterminalracks and ,fromwhieh connectionsaremadetothe cennits 3i. At the rear end of the furnace, .the top resistance umts are connected toY a busbar 35, while the bottom resistance units are connected to a him bar 35. 'Ihe bus bars 55 and 55 are connected to a common bus 31, leading back to the source of current supply. From this arrangement it will be seen that any resistance unit may be cut in or out atwill. Insomecasesitmaybeadvisabletouse It should be mentioned in passing that the work coming through the furnace may be viewed from the rear of the furnace by means of a glass window 63 (see Figure '3), and a somewhat similar window 5! may be utilized to advantage at the front of the furnace (see Figure 8) From what has been said, it will be seen that we have provided a construction which will accomplish all of the advantages and attain the objects heretofore set forth, and while many of the details may bevaried, these variations will not detract from the spirit of our invention or the scope ofthe appended claims; for example, the return side of the 'conveyor mayrpass above instead of below the "heatlng side of the conveyor, and while the cooling of the conveyor, the rods and work carried thereon, would still be gradual, it probably would not be done quite as fast as in the position shown, yet in either position, the

same advantage is derived asrexplained in the early part of this specicaon.

What we claim is: e

l. A continuous furnace comprising an elongated structural frame, a. heating chamber having a casing madeup of sheet metal plates preferably of steel, with means for holding the plates in position and additional means for correcting any warpage which may take place in the casing, the casing being lined with fire bricks, support means carried in spaced relation by the fire bricks along the length of the chamber at the top and bottom of the chamber, heating coils carried by said support means, the chamber having a narrow opening along and through one of its sides, an endls chain extending longitudinally of the chamber but outside thereof with one loop of the chain positioned closely adjacent said opening, rods carried by the chain and extending into the chamber via said opening and wholly located therein while through the chamber, and means for moving the chain.

2. A continuous furnace as set forth in claim 1, further defined in that means are provided for turning the rods within the chamber as the chain is moved. Y

3. A continuous furnace comprising an elongated frame, a. chamber lined with heat-resisting material carried by the frame. means within the chamber for heating it to a desired temperature, the chamber having a-relatively narrow opening switches used depends, of course, onV the number 'l5 along and through 'one side wall, an endless chain extending longitudinally of the frame outside the chamber with meansfor moving the chain, one loop of the chain being positioned closely adjacent said opening, holders carried by said chain inrspaced relation and extending into said opening, article-support members carried by said holders wholly within said chamber while passing therethrough and extending nearly across the chamber, a rack extending along the chamber just above the upper loop of the chain, gears fixed to said holders and in mesh with the rack wherebysaid holders and article-support members carried thereby are turned as they pass through the chamber.

4. A continuous furnace as set forth in claim 3, further dened in that means are provided in the form ofadjusting screws for putting pressure Y on the top of the rack at desired points to change its relation with respect to 'said gears as and for the purpose described.

5. A continuous furnace as set forth in claim 3, further defined in that automatically-acting means are provided for taking up the slack in the chain.

6. A continuous furnace as set forthin claim 3, further'deflned in that the chain passes over a toothed wheel at the loading end of the fur-nace;

with means for holding the coils in their respective locations, the chamber having a narrow opening on one side along its length, an endless conveyor outside the chamber and having one loop positioned closely adjacent said opening, with means for moving the conveyor, and means carried by the conveyor extending through the opening and having members fully positioned within the chamber while passing therethrough between said rows of heating coils, and preferably midway between the two rows, for carrying articles to be heat-treated.

10. A continuous furnace as set forth in claim 9, further defined in that the length of the furnace and the heating coils are so correlated that each coil will take the full voltage of the regular source of supply available without voltage and/or current-adjusting devices, and further defined in that means are provided for cutting in or out any one or more of the heating coils as required to give the desired result.

11. A continuous furnace comprising an elongated frame, a chamber lined with heat-resistber, the coils at the top being held by hangers having a hook at one end for engaging a chamber-lining member and a loop at the other end for encompassing a coil directly adjacent the top of the chamber, the coils at the bottom being. held by holders positioned in individual supports -or bridges of heat-resisting material located in spaced relation longitudinally of the chamber,

said supports or bridges being tapered upwardly toward their respective coils, the holders terminating in loops at one end to embrace the coils directly at the top of said supports or bridges, and at the other end in arms positioned in a recess of a lining member.

8. A continuous furnace as set forth in claim 3, further defined in that the heating means comprises two rows of spaced current-conducting coils of suitable resistance, one row being suspended from the top of the furnace chamber by hooks of high heat-resisting material in such a way as to give maximum radiation, the other row being supported above the bottom of the chamber on spaced bridges of heat-resisting material, said bridges beingv tapered upwardly from the bottom of the chamber and provided with internally positioned holders for holding the coils in place.

9. A continuous furnace comprising an elongated frame, a chamber lined with heat-resisting material carried by the frame, heating coils arranged in two rows longitudinally of the chamber, one row closely adjacent the top of the chamber while the other row is spaced from the bottom of the chamber on the apex of tapered supports which extend transversely across the interior of the chamber and are sucient in number to prevent sagging of said heating coils.

ing material carried by the frame, means within the chamber for heating it to a desired temperature, the chamber having a relatively narrow opening along and through one side wall, an endlessI chain extending longitudinally of the frame outside the chamber with means for moving the chain, one loop of the chain being positioned closely adjacent said opening, article-support members carried by the chain, each of said support members having two parts, one part being directly attached to the chain and extending through said opening into ythe chamber,` the other part being longitudinally adjustably carried by the first-mentioned part and being the part on which the articles to be treated are actually positioned, this last-mentioned part being wholly positioned within the chamber while passing therethrough", the return loop of the l chain being positioned a considerable distance from the flrstfmentioned loop and merging therewith at one end which serves both as the loading and unloading end.

12. A continuous furnace comprising an elon-` gated frame, a chamber lined with heat-resisting material carried by the frame, means within the chamber for heating it to a desired temperature, the chamber having a relatively narrow opening along and through one side wall, an endless chain carried principally by two sprocket wheels located one at each end of the furnace, loading rods carried by the chain and projecting in a xed position, when the chain is moved, through said opening into the chamber and wholly within the chamber while going through it, power-driving means connected to one of said wheels to move the chain so one loop passes closely adjacent said chamber opening while-the other loop moves a distance away from the first loop to give very gradual cooling to the devices carried by the loading rods, said rods being loaded and unloaded at the other sprocket-wheel end of -the furnace.

13. A continuous furnace as s et forth in claim 12, further defined in that the frame has members for supporting said rods in an outboard manner as they move back toward the unloading end.

14. For use in a heating furnace of the type herein described wherein articles are to be heat treated, which articles have a centrally located opening therethrough and have their mass generally equally distributed about said opening but subject to some asymmetrical loading, single rods on which are slipped the articles to be heat treated, said rods being carried by an endless conveyor and also being wholly positioned within the furnace while passing therethrough, and being of considerably smaller diameter than said opening to facilitate placement of the articles thereon, the furnace having heating means positioned on opposite sides of the rods and extending the entire length of the furnace, means for turning the rods and means on the rods for increasing the friction between the rods and said articles to insure a rolling like turning of the articles on the rods as they pass through the furnace.

15. A continuous furnace comprising an elon-v ture, the chamber having a relatively narrow opening along and through one side wall, an endless chain extending longitudinally of the frame outside the chamber with means for moving the chain, one loop of the chain being positioned adjacent said. opening, article-support members carried by the chain and extending through the opening into the chamber, `means for turning said article-support members at least while within the chamber as the chain moves, means for maintaining the article-support members in the same relative position with respect to the heating means as said members pass through the heating chamber, and means for continuously applying tension to the chain.

:ooMiNro J. HOLLERAN. JOSEPH J. CERNY.

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