US3070362A - Furnace roller - Google Patents

Description

3,070,362 Patented Dec. 25, 1962 3,070,362 FURNACE ROLLER Gloyd H. Young, Ida, Mich., and Carroll Cone, Toledo, Ohio, assignors to Midland-Ross Corporation, Toledo, (bhio, a corporation of Ohio Filed Mar. 2, 1961, Ser. No. 92,863 4 Claims. (Cl. 263-6) This invention pertains to a furnace roller. More particularly, this invention relates to a furnace roller suited for supporting and turning a strip of sheet metal as it passes through a continuous heating furnace. The invention may, in general, be considered to be directed to an improvement in furnace rollers of the type described in United States Patent 2,932,497 to W. H. Dailey, lr. et al.

The continuous metallurgically heat-'treatment of a strip of sheet metal is normally accomplished by conveying the strip in a series of vertical passes or strands through each of several treating zones, the transition of the strip from one pass to another being accomplished by means of a turning roller. Normally a furnace for accomplishing this heat treatment includes a heating zone, a holding zone, and several -cooling zones. A typical example of such a treating unit is illustrated at page 76 of the February 1957 issue of Iron and Steel Engineer.

The design of a turning roller for the heating section of a continuous strip processing furnace 4normally involves several problems not inherent in the design of rollers for other stages of the furnace. To begin with, the rollers in the heating section will normally be of an appreciably greater diameter than rollers in lthe other furnace zones. The larger diameter is required to provide suilicient clearance between adjacent strip passes for insertion of radiant heating tubes therebetween, such clearance normally being equal to the roller diameter.

Secondly, the furnace zone rollers tend to receive great quantities of heat which tends to pass through the roller to the bearings in which the roller is mounted. This problem of transfer of heat through the roller to the bearings, in addition to the fact that it adversely affects temperature uniformity within the furnace, is a problem which can lead to lubrication difliculties and even to premature bearing failure. Such problem can be combatted by means of certain heat flow retarding expediencies disclosed in the aforementioned APatent 2,932,497 to Dailey, I r. et al.

Among the heat flow retarding expediencies utilized by Dailey, lr., et al. is the expediency of constructing the ends of the roller with tapered trunnions at each end thereof. Such a construction permits a substantial reduction in the size of the ports in the fur-nace wall through which the ends of the roller pass and therefore helps to decrease heat transfer from the furnace through the roller. -As an additional heat liow retarding expediency it was suggested to line the tapered trunnion-s with refractory, which is normally accomplished by filling the trunnions with a cast refractory insert.

The use of refractory filled roller trunnions has heretofore met with some success in lower speed strip processing furnaces. In recent years, however, there has been a demand for higher -speed strip processing, with furnace users now requiring equipment to process strip at strip speeds in excess of 2000 f.p.m. whereas the maximum limit on strip speeds was 1000 rf.p.m. but a few years ago. Rollers constructed with refractory filled tapered trunnions have not been well suited for higher speed strip processing because the mode of inserting such refractory, which normally comprises packing a wet castable refractory into place and allowing it to set, inherently makes it diicult to balance the rollers.

In any strip processing furnace it is necessary to carefully balance the furnace rollers to avoid roller vibration which can reduce roller life and cause damage to the `bearing and drive elements. A roller for a higher speed furnace must be more carefully balanced than a roller for a lower speed furnace since the problem of vibration becomes more acute at higher speeds. The use of refractory insulation not only makes it more diflicult to lbalance the rollers but also makes it more diflicult to maintain balance because of the tendency of such material to deteriorate and to be displaced, a tendency which is also greater at higher speeds by virtue of the greater centrifugal force to which the refractory is subjected.

Accordingly, it is the object of this invention to provide novel means for retarding the passage of heat through the trunnions of a furnace roller, said means comprising at least one (l) and preferably a plurality of thin metal plates mounted within said trunnion in such a manner that a substantial portion of the faces of each plate are in nonthermal conducting relationship with any other plate and/ or other portions of the roller, such plates therefore being adapted to serve as radiation shields.

For a further consideration of what we believe to be novel and our invention, attention is directed to the following portion of the specification, the drawing, and the appended claims.

In the drawing:

FIGURE l is a fragment of a sectional elevational view of a furnace having rollers constructed in accordance with this invention.

FIGURE 2 is a partially sectional view of a roller embodying the invention.

As is shown in FIGURE l, a furnace heating chamber 11, which is dened by refractory walls 12 and metal binding 13, is provided for heating a strip of sheet metal 14 which is passed to and fro through heating chamber in a plurality of vertical passes. Strip 14 is heated primarily by thermal radiation from radiant heating tubes 15 which are mounted intermediate adjacent passes of strip.

A number of furnace rollers 16 are located within the -furnace to support strip 14 therein and to provide .for the turning of the strip from an upwardly traveling pass to the next -downwardly traveling pass. It is to be understood that like rollers are located near the bottom of heating chamber 11 to provide for the turning of the strip from a downwardly traveling pass to the next upwardly traveling pass. Located intermediate rollers 16 and radiant tubes 15 are a number of bailies 17 whose function it is to block direct thermal radiation from the radiant tubes to the rollers, thereby serving to combat the problems of heat dissipation associated with such rollers.

The construction of furnace roller 16, per se, is shown in more detail in FIGURE 2 wherein roller 16 is constructed of a cylindrical roller body 21 having tapered trunnions 22 attached to the ends thereof. Roller body 21 and trunnions 22 are assembled by inserting a trunnion in each end of the roller body, a bored portion 23 being provided in each end of roller body 21 for receiving a trunnion. Trunnions 22 are then secured to roller body 21 as by means of a weld 24. A bearing shaft 25 is located at each end of the roller to provide for mounting of the roller, which may be accomplished in accordance with the teachings of Dailey, Ir. et al. Patent 2,932,497.

To retard the tlow of heat from the roller body 21, which is located within the heating chamber, to bearing shafts 25, which are located outside of the heating chamber, insulating means 26 are provided inside the trunnions. The insulating means heretofore utilized by prior artisans, as was previously mentioned, normally comprised a cast refractory insert. Such construction was quite effective insofar as insulating properties are concerned, but was, however, subject to mechanical deterioration caused by heat, vibration, and centrifugal force, a problem which became quite severe in higher speed furnaces. To eliminate the problems associated with refractory filled trunnions we have devised insulating means which comprises at least one (l) and preferably a plurality of thin metal plates such as plates 27 and 28 `which are inserted within trunnions 22, extending generally perpendicularly with respect to the axis of the trunnion. Plates 27 and 28 are adapted to serve as thermal radiation shields which requircs that at least a substantial portion of both faces of each plate be in non-conducting relationship with the other plate and/or any portion of the roller.

Metal plates 27 and 28, which are of different diameters to insure that they will be maintained in spaced apart or non-heat conducting relationship with respect to each other, are attached to the respective trunnions by aixing the outer periphery of the plates to the inner surface of a trunnion, as by means of tack welds 31 and 32. The centers of metal plates 27 and 28 are secured with respect to each other by afiixing them to a central spindle 33 which also serves as a spacer. When additional insulating effect is desired the narrower cooler portion 22a of each trunnion may be filled with a suitable insulating material 34 such as rock wool. Insulating material 34, when used, can be retained in place by means of a metal plate 3S which is similar to metal plates 27 and 28 but does not function as a true radiation shield because it is in thermal conducting relationship with insulation 34.

The means for insulating a furnace roller trunnion described above, which comprises two (2) radiation shields 27 and 28 located therein, approaches the insulating efectiveness of a refractory filled trunnion while at the same time avoiding the mechanical problems associated therewith. It is to be noted that any number of radiation shields may be used depending on the degree of insulating effectiveness desired, each radiation shield, in theory, serving to block about one-half of the heat radiated to it.

The best mode known to us to carry out this invention has been described above in terms sufficiently full, clear, concise, and exact as to enable any person skilled in the art to make and use the same. It is to be understood, however, that certain modications of the above described mode of practicing this invention can be made by a skilled artisan without departing from the scope of the invention which is defined only by the appended claims.

We claim:

l. A furnace roller comprising, in combination: a cylindrical body; a tapered trunnion attached to each end of the cylindrical body; a first thin circular metal plate disposed within each trunnion, said metal plate being disposed substantially perpendicularly to the axis of the trunnion with its periphery attached to the inner surface of the trunnion and having a substantial portion of each face in non-thermal conducting relationship with any other portion of the roller; and a second thin circular metal plate being disposed within each trunnion at a distance from said first plate and nearer to the cylindrical body than said first plate, said second plate having a diameter greater than the diameter of the first plate and being disposed generally parallel to the first plate with its periphery attached to the inner surface of the trunnion and defin fr ing a substantially enclosed insulating volume with the trunnion and the first plate.

2. Apparatus according to claim l and further compris ing a spindle disposed within the trunnion axially thereof and attached to the centers of the first and second thin circular metal plates.

3. A furnace roller comprising, in combination: a cylindrical body; a tapered trunnion attached to each end of the cylindrical body; a first thin circular metal plate disposed within each trunnion, said metal plate being disposed substantially perpendicularly to the axis of the trunnion with its periphery attached to the inner surface of the trunnion and having a substantial portion of each face in non-thermal conducting relationship with any other portion of the roller; a second thin circular metal plate being disposed within each trunnion at a distance from said first plate and nearer to the cylindrical body than said first plate, said second plate having a diameter greater than the diameter of the first plate and being disposed generally parallel to the first plate with its periphery attached to the inner surface of the trunnion and defining a substantially enclosed insulating volume with the trunnion and the first plate, insulating material disposed within the trunnion at a distance from the first plate and further away from the end of the cylindrical body to which the trunnion is attached; and a third thin circular metal plate intermediate said first plate and said insulating material having a face abutting against said insulating material and being adapted to retain said insulating material, said third plate having a lesser diameter than said first plate and being disposed generally parallel to the first plate with its periphery attached to the inner surface of the trunnion and defining a second substantially enclosed insulating volume with the trunnion and the first plate intermediate the insulating material and the first insulating volume.

4. A furnace roller comprising, in combination: a cylindrical body; a tapered trunnion attached to each end of the cylindrical body; a first thin circular metal plate disposed within each trunnion, said metal plate being disposed substantially perpendicularly to the axis of the trunnion and having a substantial portion of each face in non-thermal conducting relationship with any other portion of the roller; insulating material disposed within the trunnion at a distance from the first plate and further away from the end of the cylindrical body to which the trunnion is attached; and a second thin circular metal plate intermediate said first plate and said insulating material having a face abutting against said insulating material, and being adapted to retain said insulating material said second plate having a lesser diameter than said first plate and being disposed generally parallel to the first plate with its periphery attached to the inner surface of the trunnion and defining a substantially enclosed insulating volume with the trunnion and the first plate.

References Cited in the file of this patent UNITED STATES PATENTS 1,840,661 Fahrenwald Jan. 12, 1932 1,871,937 Wilson Aug. 16, 1932 2,932,497 Dailey et al Apr. 12, 1960

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