US2045773A - Heating furnace - Google Patents

Description

June 30, 1936. .J. P. HAvEY HEATING FURNACE Filed June 13, 192B INVENTR BY fr ATTORNEYS Patented June 30, 1936 UNITED STATES PATENT OFFICE 2,045,773 HEATING FURNACE Application June 13, 1928,*Seral No. 284,891

17 Claims.

This invention relates to heating furnaces, More particularly, the invention relates to the construction and mounting of furnace rolls of annealing furnaces and other industrial heating furnaces, for supporting and feeding sheets, strips,

1 tubes, bars, rods, and other articles ofmetal or other materials while being heated in the furnace. The object of the invention is, generally, to simplify and reduce the cost of the furnace equipment and to reduce the cost of operating the furnace, and to improve the heating. Furnace rolls of industrial heating furnaces in which relatively high temperatures are maintained, such, for example, as furnaces for annealing metal sheets, are customarily cooled by means of water caused to flow through the rolls or roll shafts. This Water cooling involves not only a considerable original equipment expense, but, also, a large operating expense including the cost of supplying the large amount of water required and the fuel cost of the heat taken from the furnace by the cooling water. There is, also, the further disadvantage Vthat the work-supporting members of the rolls are usually maintained at a temperature considerably below the temperature .to which the work is heated, and this results in an uneven heating of the work.

The present invention aims to provide furnace rolls which require only such cooling as may be secured by air-cooling, and most desirably with the air moving under natural draft, thus eliminating the use of water for cooling the rolls and greatly reducing the loss of heat from the furnace through the roll shafts; and to provide furnace rolls of which the work-supporting parts or members may while in operation be maintained at a temperature substantially equal to the furnace temperature and, therefore, equal to, or greater than, the temperature to which the work is heated.

Further objects of the invention are to provide a furnace roll which is of comparatively simple and inexpensive construction, and which will withstand operation at high temperatures for long periods.

Furnace rolls according to the invention cornprise a shaft and one or more tubular sheaths or sleeves larger and shorter than the shaft, supported from the shaft, and arranged concentrically of the shaft, and of each other when there are more than one, each sleeve being supported adjacent to its endsby supporting means of relatively low heat conductivity and being insulated from the shaft, and from each other when there are more than one, by an insulating space which is most desirably filled with suitable insulating material, the ends of the outer sleeve most desirably extending into and terminating within the roll openings in the furnace walls, and the ends of the shaft extending beyond the sleeve or sleeves to form Journals which are mounted in suitable bearings outside the furnace walls.

The shaft is most desirably tubular to permit of its being air-cooled by the passage therethrough of sufficient air to prevent the building up of temperature by the relatively small amount of heat which reaches the shaft from the outer sleeve. The outer, or work-carrying, sleeve may be provided with removable work-supporting discs, or other suitable work-supporting members such as are commonly used on furnace rolls.

The work-carrying outer sleeve and the worksupporting discs or other work-supporting means will run at substantially furnace temperature, while the inner tube, or shaft, will receive so little heat as to require very little cooling to prevent any portion thereof from becoming heated to a temperature which would cause any serious loss of rigidity, and there will be a minimum loss of heat from the furnace. The outer cylinder, or sleeve, which is subjected to the furnace temperature is shortest and of greatest diameter and, therefore, most rigid, and the longer and smaller diameter and, therefore, weaker cylinder or cylinders are maintained at a relatively low temperature.

Furthermore, the weight of the work and of the work-supporting discs or other work-supporting members is borne directly by the outer tube or sleeve and is transferred to the shaft only at points near the shaft bearings and away from the central weaker and hotter portion of the shaft. The central portion of the shaft is thus under a uniform and relatively less stress, and may, therefore, be permitted to attain a higher temperature than would otherwise be safe, thus further reducing the degree of cooling required. And the outer tube, which directly supports the load, being of greater diameter and of less length between its points of support, may readily be made of such diameter and wall thickness as to have vthe required rigidity and relatively great load carrying capacity even when heated to a high furnace temperature.

If the roll is for use in a high temperature furnace, the outer, work-carrying sleeve should most desirably be made of a high heat-resisting alloy which will withstand the furnace temperature Without scaling and without too great loss of rigidity. The shaft, and the intermediate sleeve or sleeves, if there -are any, may also be made of heat-resisting alloys, but usually it will not be necessary to make the shaft of such material, although it may be advantageous to do so because of its further reducing the necessary weight of the shaft.

A full understanding of the invention can best be given by a detailed description of constructions embodying the various features of the invention in approved forms, and such a description will now be given in connection with the accompanying drawing illustrating two approved embodiments of the invention, in which:

Fig. 1 is a cross-sectional view through a furnace chamber showing one of the furnace rolls partly in central longitudinalsection; and

Fig. 2 is a central longitudinal sectional view of the main tubular members of another form of roll.

Referring to the drawing, and first to Fig. l, this ilgure shows in transverse sectional view part of the side walls I0 and Il of a sheet annealing or other article heating furnace of the kind having a series of parallel work supporting and feeding rolls extending transversely across the furnace chamber between the side lwalls of the furnace, the view showing one of the furnace rolls and supporting means therefor partly in section longitudinally of the roll.

The roll shown in Fig. 1 comprises a tubular shaft I! and an outer work-supporting sleeve or sheath, I6 the internal diameter ofwhich is substantially greater than the external diameter of the shaft. The shaft extends beyond the ends of the sleeve I6 and is mounted to turn in Journal bearings Il and Il and is rotated by any suitable means, such as the means shown comprising a worm 20 on a driving shaft 2li whichextends Alongitudinally of the furnace, the worm meshing with a gear 22 on the end of the roll shaft beyond the bearing I8. The outer cylinder, or sleeve, I6 is of a length to extend across the furnace chamber with its ends inthe roll opening 23 in the furnace side walls I I and I I, and it is mounted on the shaft by means of supporting collars, or rings, 2l located adjacent each end of the sleeve. The ring at one end of the sleeve is shown in Fig. 1, and asimilar ring is positioned adjacent the other end of the sleeve.

The rings 25 are made to have low heat conductivity and may be thin rings of metal, most desirably a heat resisting alloy of low thermal conductivity. Also, the location of the rings adjacent the ends of the sleeve within the furnace walls results in much less heat being conducted from the sleeve through the rings to the shaft than would be the case if the rings were located to make engagement with a hotter part of the sleeve located within the furnace chamber. The space between the sleeve and shaft inside the rings 25 serves as a heat insulation space and is most desirably filled with suitable heat insulating material. Most desirably, this insulating material is of two nds: an outer layer 20 of high refractory ma al selected primarily for its ability to withstand a high degree of heat, and an inner layer 21 which need not have such great heat resistance but is selected primarily for its heat insulating property.

The sleeve Ii carries a series of work-supporting discs l0 which may be formed in the usual manner with hub portions to seat on the sleeve which are of a length to suitably space the discs and have their meeting faces shouldered as shown so that the discs will be interconnected to rotate together. The discs are positively driven from the shaft Il by means of a driving sleeve 36 the outer end of which fits on the shaft Il in shouldered, interlocking, engagement with the end of a collar I. secured fast to the shaft. The inner end of the driving sleeve 3l is made larger to fit over the end of the sleeve Il and has shouldered engagement with the hub of the end disc 2l, or, as shown, with a collar 31 on the sleeve Ii between the hub of the end disc and the driving sleeve Il and making shouldered engagement with each.

For holding the disc hubs pressed together, while at the same time allowing for difference in expansion between outer and inner members of the roll, abearing sleeve 4I is provided at the other end of the sleeve I8, formed with a smaller outer end to i'lt on the shaft vand a larger inner end to fit over the end of the sleeve l. and bear against the hub of the end disc 20, or, as shown, against a collar 4I which bears against the hub of the end disc. The sleeve 40 is urged inward by a spring 42 compressed between a collar 4I fast on the shaft Il and a collar M slidable on the shaft and bearing against the end of the sleeve 4l.

The sleeve 4l may also serve as a driving sleeve. For this purpose, its inner edge is formed to make shouldered engagement with the collar 4I, and the collar ll makes shouldered engagement with the hub of the end disc; and, in the construction shown, instead of having the sleeve .40 keyed to the shaft Il, its outer end is shouldered to fit the correspondingly shouldered inner end of the collar M, and the collar M is keyed to the shaft so that while free to slide longitudinally of the shaft it is held to turn therewith to rotate the sleeve 40.

One at least ofthe rings 25 should have a sliding nt with either the shaft or the sleeve IB so as to permit relative' movement of different parts under unequal expansion and contraction, but both of the rings should be secured to one of these members so that they will be held against movement out of position.

In order to provide for adjustment of the supporting discs 3l longitudinally of the roll, the driving collar 3i is adjustably secured to the shaft I5, as by means of a nut ll and jam nut 46 screwed on a threaded portion of the shaft. The

4 collar 42 which takes the thrust of the spring I2 is also screwed on a threaded portion of the shaft so as to be adjustable correspondingly with the collar This adjustability of the collar Il also serves for adjusting the strength of the spring pressure on the bearing sleeve I0.

In order to reduce, as far xas possible, the passage of heat from the sleeve I8 and the collars 31 and Il to the sleeves I5 and I0, and thence to the shaft, the internal diameter of the inner ends of the sleeves I5 and lll is made slightly greater 'than the external diameter of the sleeve Il'so as to avoid contact with the sleeve I6, and the inner edges of the sleeves 35 and 40 are formed with projecting lugs 50, shown on the sleeve 35,' so that there shall be minimum contact between the sleeves 3i and III, and the collars I1 and ll, respectively. The sleeves 35 and 40 are also formed with holes 5I to prevent heat from building up within the sleeves and around the supporting rings 2l. l

The ends of the shaft are left open to permit movement of air therethrough, but, as stated, only a slight movement of cooling air through the shaft I5 will usually be required. I have found that a sufilcient ilow of air through the shaft 75.

acume may be secured by connecting to one end of the rshaft an upwardly extendingA pipe, or stack, l0. the connection being made in any convenientl more than one cylinder,`or sleeve, outside the shaft. The higher the furnace temperature and the longer the roll and the greater the load. the more need of greater strength and a. plurality of outer sleeves. Fig. 2 shows the tubular members of a three tube roll having a tubular shaft |541, an outer sleeve Ia, and an intermediate sleeve 1li. The outer sleeve is supported on the intermediate sleeve by supporting rings 1I of compressed asbestos or other suitable material,

and the intermediate sleeve issupported on the shaft by similar rings 12, the rings for supporting each sleeve being positioned adjacent the ends of the sleeve, and the insulation space between the outer and intermediate sleeves and between the intermediate sl'eeve and the shaft being packed with insulating material. The insulatingmaterial 13 between the outer and intermediate sleeves is selected primarily for its heat resistance, and'that 14 between the intermediate sleeve and the shaft for its insulating property.

What is claimed is:

1. In a heating furnace having spaced side walls, a work supportingand feeding roll extending across the furnace chamber between the side walls of the chamber, said roll comprising a hollow shaft, work-carrying means adapted to operate at substantially furnace temperature comprising a sleeve the internal diameter of which is substantially greater than the external -the side wallsl and the end portions of the shaft extending beyond the ends of the sleeve and beyond the side walls to serve as journals for the roll.

2. In a heating furnace having spaced side walls, a work supporting and feeding roll extending across the furnace chamber between the side walls of the chamber, said roll comprising an air-cooled hollow shaft, work-carrying means adapted to operate at substantially furnace temperature comprising a sleeve the internal diameter of whichis substantially greater-than the external diameter of the shaft and a plurality `of work supporting discs mounted on said sleeve, and means adjacent theends of said sleeve for supporting the sleeve on the shaft in coaxial relation thereto and for ypreventing relative rotation of the shaft and said work-carrying means and adapted to permit limited relative longitudinal movement between the shaft and said sleeve, the space between the shaft and said sleeve containing insulating material, the end portions of said sleeve extending into and ter- 3. A- furnace. roll for supporting and feedingl articlesl being heated,y comprising an outer workcarrying sleeve oi a length to extend across the furnace chamber and adapted to operate at substantially yfurnacetelnperature, and a hollow shaft which extends through the sleeve and be-- yond each end thereof and the diameter oi which .is substantially less than the internal diameter, of the sleeve to provide'an insulation space bef tween them, and means adjacent the ends of the sleeve for supporting the `sleeve on the shaft in coaxial relation thereto and for preventing relative rotation. of the shaft and the sleeve and -adapted to permit limited relative longitudinal movement between the sleeve and the shaft,

whereby load on the sleevey is transmitted away fromjthe middle portion of the shaft and to points on the shaft adjacent the ends of the sleeve. j

4. A furnace roll, comprising an outer workcarrying sleeve of a length to extend across the furnace chamber, work supporting discs mounted on the sleeve adapted to operate at substantially furnace temperature, and an air-cooled hollow shaft of substantially smaller diameter than the internal diameter of the sleeve and the'ends of which extend beyond the ends of the sleeve to serve asjournals, the sleeve being mounted on the shaft by collars adjacent the ends of the sleeve, and the space between the shaft and the sleeve and between said collars being filled with the inner tubular member extending to serve as journals, .the outer tubular member being of a ylength to extend across the furnace chamber and being supported by collars of low heat.l conductivity located adjacent the ends vthereof and being insulated to minimize the heat loss inward therefrom, and the inner tubular member being open for access of cooling air to the interior thereof.

6. A furnace roll for supporting and feeding articles being heated, comprising three tubular members of different diameters arranged concentrically one within another, the ends of the inner tubular member extending beyond the ends of the intermediate tubular member to serve as journals and the ends of the intermediate tubular member extending beyond the ends of the outer tubular member, the outer and intermediate tubular members each being supported by collars of low heat conductivity located adjacent the ends thereof and being insulated to minimize the heat-loss inward therefrom, the inner tubular member being open for access of cooling air to the interior thereof. r

7. A furnace roll for supporting and feeding articles 'being heated, comprising three tubular members of different diameters arranged con- 'centrically one within another, the ends of the inner tubular member extending to serve as journals, the outer and intermediate tubular member each being supported by collars of low heat conductivity` located adjacent the ends thereof, a filling of insulating material in the spaces between'said collars, the inner tubular member being open for access of cooling air to the interior thereof. Y

8. A furnace roll for supporting and feeding articles being heated, comprising an outer sleeve,- a shaft which extends through the sleeve and beyond the ends thereof and the diameter of which is substantially less than the internal di' ameter of the sleeve to -provide an insulation space between them, the sleeve being supported on the shaft by collars of lowheat conductivity adjacent the ends of the sleeve, work-supporting meansv mounted on said outer sleeve, yand means for driving said work-supporting means comprising a driving sleeve mounted on the shaft and having an enlarged end,which extends over the'end of said o'uter sleeve but. spaced away therefrom and engages said work-supporting means at spaced points.

9. A furnace roll for supporting and feeding articles being heated, comprising an outer sleeve.

a shaft which extends through the sleeve and beyond the ends thereof and the diameter of which is substantially less than the internal diameter of the sleeve to-provide an insulation` space between them, the sleeve being supported on the shaft by collars of low heat conductivity adjacent the ends of the sleeve, work-supporting means mounted on said outer sleeve, and,means for driving said work-supporting means comprising a driving sleeve mounted on the shaft and having an enlarged end which extends over the end of said outer sleeve but' spaced away therefrom and engages said work-supporting means, said driving sleeve having air openings therein.

10. A furnace roll for supporting and feeding articles being heated, comprising an outer sleeve, a shaft which extends through the sleeve and beyond the ends thereof and the diameter of which is substantially less than the internal diameter of the sleeveto provide an insulation space between them, the sleeve being supported on theshaft by collars of low heat conductivity adjacent the ends of the sleeve, work-supporting discs having their hubs seated on said outer sleeve and in interlocking engagement with each other, a driving sleeve at one end of said outer sleeve mounted on the shaft and having an enlarged end for driving said discs, and a spring-pressed `bearing sleeve at the other end of said outer sleeve mounted on the shaft and having an enlarged end for pressing said discs together.

11. A furnace roll for supporting and feeding articles being heated, comprising an outer sleeve, a shaft which extends through the sleeve and beyond the ends thereof and the diameter of which is substantially less than the internal diameter of the sleeve to provide an insulation space between them.' the sleeve being supported on the shaft by collars of low heat conductivity adjacent the ends of the sleeve, work-supporting discs having their hubs seated on said outer sleeve and in interlocking engagement with each other, a driving sleeve at one end of said outer `sleeve mounted on the shaft and adjustable longitudinally on the shaft and having an enlarged material in'the space between the tube and the l5 sleeve, one of said closure vmembers permitting relative longitudinal movement between the tube and the sleeve.

l 13. A furnace roll. comprising a hollow metallic one-piece sleeve. said sleeve being free of ilssures 20 which would permit leakage of insulating material, a shaft formed by a cooling iluid tube extending through said sleeve, insulating material confined between the tube and the sleeve, and closure memberseadapted to retain the insulat- 25 ing material between the tube land sleeve, one of said closure members permitting relative longitudinal movement between the tube and the sleeve.

14. A furnace conveyor assembly,'including in 30 combination a shaft, a sheath encircling the shaft, conveyor wheels or discs removably mounted on the sheath, means for rotating said wheels or discs with the sheath, and means extending between and engaging the sheath and shaft for maintaining the predetermined spacing of theshaft from the sheath.

15. A furnace conveyor assembly, including in combination a shaft, a sheath encircling the shaft, rconveyor wheels or discs mounted on the eath, means for rotating said wheels or discs with the sheath, and means extending between and engaging the sheath and shaft for maintaining the predetermined spacing of the shaft from the sheath and for retaining heat insulating materiall within the sheath and about the shaft.

16. A furnace conveyor assembly including in combination a shaft, a sheath' encircling the shaft, conveyor wheels or discs removably mounted on the sheath for rotation therewith,

' and means extending between and engaging the sheath and shaft for maintaining the predetermined spacing of the shaft from the sheath. 17. A furnace conveyor assembly including in combination a shaft, a sheath encircling the shaft, conveyor wheels or discs mounted on the sheath for.l rotation therewith, and means extending between and engaging the sheath and shaft for maintaining the predetermined spacing of the shaft from the sheath and for retaining heat insulating material within the sheath and about the shaft.

JOSEPH P. HAVEY.

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