US2433121A - Drier drum - Google Patents

Description

Det?.` 23, 1947. L. HQRNBOSTEL 2,433,121

DR I ER DRUM Filed Jan. 29. 1944 2 sheets-snaai 1 Loro Hoen/ 0.5751..

Ig' 24 s/IZ Patented D ec. 23, 19.4'

DRIER DRUM Lloyd Hornbostel, Beloit, Wis., assigner to Beloit Iron Works, Beloit, Wis., a corporation of Wisconsn l Application January 29, 1944, Serial No. 520,189

order to secure the desired surface on the sheet that is so dried (for example, in the production of a so-called machine glaze sheet), it is desirable that the surface of thedrier drum or .cylinder be homogeneous and machinable to a high degree of regularity and smoothness. At-

the same time it is necessary that the surface be very hard and durable to effectively withstand the action of doctors and other mechanism necessarily brought into contact therewith.

Cast iron provides an admirable metal for this purpose, but the physical strength thereof is so low that too great a thickness of metal is required to withstand the extremely high pressures desirable for eicient drying operation. Cast steel does not provide the desired surface character-f istics and the heat treatment or case hardening thereof has proven impracticable with the large size drums or cylinders required fordrlers of this character.

It is an important object, therefore, of the present invention to provide a, drier drum of relatively light weight which is capable of withstanding extremely high heating medium pressures and which, at the same time, has a drying surface providing the desired characteristics of homogeneity, smoothness and hardness.

, It is a-further important object of this invention to provide a method of making such a drier drum wherein a steel drum adapted to afford desired resistance to high steam vpressure is pro- 40 v and to prevent heat loss. At the side of the chamvided with a completely welded coating of an airhardened metallic alloy that is capable of being machined or ground to provide the desired surface characteristics.

A further important object of this inventionresides in the provision of a drier having a wall of high heat conductivity which is adapted to withstand extremely high pressures and which, at the same time, possesses the requisite characteristics of hardness and smoothness. 5o

' Other and further important objects of this invention will be apparent from the following` speciilcation and claims and the accompanying drawings.

On the drawings: 55

Figure 1 is a central longitudinal sectional View with parts shown in elevation showing a drier drum or cylinder constructed in accordance with the present invention.

Figure 2 is a fragmentary side elevational view diagrammatically illustrating the method of depositing air-hardening metallic alloy on the surface of the drier drum.

Figure 3 is an enlarged fragmentary section taken as in Figure 1 showing a portion of the drier drumwith the outer cylinder ground down to uniform thickness prior to deposition of molten metallic alloy thereon.

Figure 4 is similar to Figure 3 showing the surface of the drier drum as it appears after deposition of molten air-hardening metallic alloy thereon; and

Figure 5 is a view similar to Figure 3 showing the drier drum after grinding down of the coating of deposited air-hardening metallic alloy tothe desired uniform thickness and smoothness.

As shown on' the drawings;

The reference numeral Ill indicates a hollow axle member which is provided with bearing surfaces I2 to permit the mounting thereof for rotation and which is alsoprovided at either end with supporting spiders I3 which carry the dryingy chamber in a manner that will now be described.

The spiders I3 are provided with shoulders as at I4 to engage complementary shouldered portions on cylindrical end plates I5 which are sei cured to said spiders by bolts I6 engaged through the shouldered portions of the respective parts.

The inner faces of the end plates I5 are provided with inwardly extending annular flanges I1 on which are carried an inner cylinder I8 which forms -the inner wall of a steam chamber I9. The inner cylinder I8 is preferably formed of steel so as to withstand high fluid pressure,

ber dened by said inner wall I8 a layer of insulating material 20 is provided on the inside of the cylinder I8, said layer of insulation 20 being f conveniently positioned by a supplemental cylinsure which is molded or otherwise secured in pressure resisting relation to-the inner faces off; the end plates I5 as shown in Figure 1, saidsteel' 3 cylinder 22 being provided with a uniformhomogeneous coating of air-hardened metallic alloy 23 applied thereto in a manner 'to be described hereinafter.

Superheated steam at extremely high pressure is introduced into the chamber I3 from a conduit 24 which leads in through the left hand side of the hollow axle member l and has a lateral portion 25 extending to said steam chamber.

The conduit 24 may be provided with the usual steam joint, not shown, to permit rotation thereof but since such steam joints are well known in the art and provide no part of the present invention, they will be neither shown nor described here.

An outlet whereby steam is conducted out of the steam chamber i3 comprises a conduit 28 extending outwardly through the hollow axle member shown at the right hand side of Figure 1, said conduit 26 being provided with a lateral portion 2l extending into the steam chamber and provided with the usual scoop type of outlet 28. The

conduit 26 may be provided with a usual steam Joint .(not shown) to permit rotation in the manner above described.

In order to withstand the high steam pressures the cylinders i8 and 22 are made of strong steel, so-called 31-40 steel having been found suitable for this purpose. While steel of this character is well adapted to withstand high steam pressures, it is not adaptable to providing the required smooth surface that is suiciently hard to withstand the mechanicalaction of doctors, scrapers, and similar apparatus which may be engaged against the surface thereof in the paper making operation.

l For that reason it is desirable that the outer surface of the cylinder 22 be provided with a coating of hard material adapted to be ground to a high degree of uniformity and smoothness, and having a rate of heat transfer approximately equal to that of the cylinder to which such coating is applied. It isfor this reason that the coating 23 has been provided. It has been found that such coating may be satisfactorily made of an air-hardening type of metallic alloy applied to the surface of the cylinder 22 by a welding process. By air-hardening alloy is meant the commonly accepted metallurgical meaning of the term which denotes properties quite distinct from the mere solidification of the alloy material when exposed to air and normal temperatures. By air-v hardening alloy is meant an alloy which will assume a degree of hardness upon being cooled in air which is in the range of hardness equivalent to that obtained in other ferrous alloys by rapid quench cooling following heating of the alloy above its critical temperature. Good examples of air-hardening metallic alloys which have all been found satisfactory for this purpose are the well' known non-ferrous alloys containing chromium and cobalt plus a small amount of molybdenum or tungsten; the ferrous alloys containing a high percentage of nickel and molybdenum; or the ferrous alloys containing high percentages of chromium and molybdenum together with smalle amounts of cobalt and vanadium.

The method of applying these air-hardened metallic alloys as th'e coating 23 on the cylinder 22 will now be described, reference being had to Figures 2, 3, 4 and 5 of the drawings in such description.

After a drier drum or cylinder has Ibeen built up, it is mounted for rotation between standards 29 which afford journals for receiving the bearing Portions I2 of the hollow axle member I0 so that the drier drum may be slowly rotated by means of a drive mechanism consisting of a motor 30. a gear reduction mechanism or coupling device 3|, and gearing 32, which gearing is connected to rotate the drum- The gearing 32 also serves engagement of the gear 33 to rotate a screw feed shaft 34 rotatably mounted in the upper ends of the standards 23 above the rotating drier drum.

Thus screw feed member 34 is adapted to advance a welding head or. other suitable tool lengthwise of the face of the drum as the same is r0- tated, said welding head or tool being in turn guided by a guide rod 36 secured to the upper extremities of the standards 29.

In practicing the method of this invention, the drier drum, after being set up as just above described, may .be subjected to'a suitable machining operation whereby the steel cylinder 22 is machined to a uniform thickness. Thereafter, while still positioned in the set-up shown diagrammatically in Figure 2, the welding head 35 is operated to deposit overlapping spiral layers of airhardening metallic alloy on the surface of the cylinder 22 to provide the coating 23 in rough -form as shown in Figures 2 and 4.

After the coating 23 has been applied to the cylinder 22 in rough form as shown in Figure 4, it is ground down to a uniform and desired degree of smoothness as shown in Figure 5, whereupon there is provided a composite wall affording the drying surface of the drier drum which is of substantially uniform heat conducting characteristics, which is capable 0f withstanding 'extremely high steam pressures and which, at the same time, has a sufficiently hard surface to withstand the action of doctors and Scrapers.

It should be further noted that by the use of steel walls for enclosing the high pressure steam chamber it is not only possible to withstand much higher steam pressures, but that it is also possible to do so with considerably thinner walls than is the case when cast iron is used for that purpose.

Therefore, this invention not only provides a more efficient drier drum, but also one of less weight and of more economical construction.

While I have illustrated and described herein a preferred embodiment of the present invention, it is to be understood that this has been done by way of illustration, and that the invention is not to be specifically confined to such embodiment. For example, I have made reference to certain airhardened metallic alloys that have been found satisfactory for use in the practicing of this invention. It is obvious that modifications of such alloys be used so long as they are of air-hardening character and of approximately the same rate of heat conductivity as the steel forming the outer wall of the drying chamber.

It is understood, therefore, that this invention includes every construction and method falling within the terms of any one or more of the following claims.

I claim as my invention:

1. In a drier, a plurality of metal walls defining a chamber capable of withstanding high fluid pressure, a continuous, integral, air-hardeningl coating on one of said walls formed by the uniform deposition of molten air-hardening metallic alloy thereon, said coating having a rate of heat conductivity approximately that of the metal of the wall to which it is applied, means for feeding heating fluid to said chamber, and means for removing spent heating, fluid from said chamber.

3. In a drier drum, a cylindrical steel wall adapted to withstand highpressure, an integral air-hardening alloy exterior coating on said wall formed by the uniform deposition of molten airhardening metallic alloy thereon, means for feeding heating uid into the cylinder defined by said v cylindrical wall to heat the wall, and means for i removing spent vheating iiuid from the cylinder.

LLOYD HORNBOSTEL.

REFERENCES CITED The following references are of record in the le of this patent:

OTHER REFERENCES Buuenn No. 285, page 1o, Buffalo Foundry and Machine Company, Buffalo, N. Y. Published in

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