US2328321A - Drier drum - Google Patents

Description

2 Sheets-Sheet l QNN .-Aug. 31, 1943. E. E. BERRY 2,328,321

DRIER DRUM File@ Ju1y s1', 19:59

'2 Sheets-Sheet 2 1 HIL! like.

Patented Aug.- 31,y

DRIER. DRUM Earl E. Berry, Beloit, Wis., assigner to Beloit Iron Works, Beloit, Wis., a corporation of Wisconsin Application July 31, 1939, Serial No. 287,507

7 claims. f (cl. 34-9) This invention relates to drier drum constructions, and more particularly to Yankee driers having highly polished bronze peripheral surfaces supported on ferrous metal trunnions which are initially stressed to compensate for differences in expansion of the non-ferrous metal and ferrous metal parts so that the stresses are relieved when the driers are heated to drying temperatures.

Drier drums for producing `machine glazed paper webs 'should have perfect, smooth web-receiving surfaces free from scratches, pits and the 'I'hese drier drums are made from cast metal cylinders, and many mechanical grinding and polishing operations are necessary to smooth oif the web receiving surfaces of the castings. However, the usual cast metal cannot be polished sufficiently to produce a perfect, smooth surface,

and cast ferrous metals in particular are pitted,

lscratched and irregular, even after the most thorough polishing operations.

Since in the Yankee type Fourdrinier paperV machine the newly formed paper web is directly contacted with the Yankee drier, any irregularities in the drier surfaceUwill be reproduced on the' web. Furthermore, any pits in the drier surface will form steam or vapor pockets tending to blow the sheet olf the drum surface and hinder efficient drying. As a result, it has been heretofore necessary to dry at low temperatures so that the steam or vapor formation is suiciently slow to permit its being bled through the sheet Without developing appreciable pressures under the sheet.

This invention now provides a composite drier drum having a cast bronze cylinder mounted on a ferrous metal trunnion. The bronze alloy used I- in forming the cylinder is fine grained and dense,

The axle has head-receiving shoulders thereon spaced apart for a distance greater than the normal spacing between the aperture defining rims of the heads. The heads are then sprung outwardly into tight engagement with the axle shoulders so that theconstruction is stressed both axially and radially. When the composite drum is heated to dryingtemperatures, the bronze cylinder and heads expand more than the ferrous metal axle and the stresses are relieved.

The use of ferrous metal such as iron or mild steel for the axle construction effects large savings since in the larger drier drums this supporting shaft may weight as much as twenty tons. In addition, the cast iron or mild steel possesses great strength.

It is then an object Aof the invention to provide drier drums for the production of superior machine glazed paper.

Another object of the invention is to provide drier drums having perfect mirror-like peripheral surfaces composed of cast non-ferrous metal.

Another object is to provide composite drier drum constructions including cast non-ferrous cylinders mounted on cast ferrous metal trunl nions.

A further object of this invention is to provide a -composite metal drier drum having an initial stress thatis relieved when the drum is brought upto drying temperature.

A specific object of theinvention is to provide a Yankee drier having a bronze' cylinder and bronze heads mounted under stress on" an iron or steel trunnion.

Other and further objects of the invention will become apparent to those skilled in the art from the following detailed description of the annexed sheets of` drawings which disclose a preferred.

embodiment of the invention.

On the drawings:

Figure 1 is a vertical cross-sectional view, taken` Figure 2 is a transverse cross-sectional View,

taken along the line II-II of Figure 1;

Figure 3 is an enlargedA fragmentary vertical cross-sectional view illustrating the manner in which the drum is initially stressed on its supporting trunnion;

Figure 4' is a greatly enlarged cross-sectional view of a web o f paper being dried on a drum according to this invention;

Figure 5 is .a fragmentary plan view of the web shown in Figure 4` and illustrating the machine glazed drum contacting surface of the web;

Figure 6 is a greatly enlarged vertical cross- -v sectional view of a web of paper being dried on the usual drum drier; l

Figure 7 is a plan view of the web dried on the drum shown in Figure 6 .and illustrating the pock-marked machine glazed Adrum contacting surface of the web; and

Figure 8 is a greatly enlarged vertical cross- 'sectional view taken through the usual periphery 'operating temperature.

of a drum" drier and illustrating the effect of a pit in the drum surface on the web being dried on the surface.

As shown on the drawings:

As best shown in Figure 1, the reference numeral l designates generally a drier drum composed of a cast bronze hollow cylinder H bolted to concave or dished cast bronze heads I2 by means of bolts I3. The heads I2 form end walls for the cylinder I I.

Both heads I2 are centrally apertured as at It to receive a cast iron or cast mild steel axle or trunnion designated generally by the reference numeral i5. f

One of the heads I2 can have a second aper-l ture I6 therein to provide amanhole giving access to the interior of the drum I0. The aperture I6 can be closed with a plate or cover Il.

The axle or trunnion I is composed of two hollow axially aligned parts I8 and I9 having a separator plate therebetween. The plate 2U is provided with a thickened Arim portion 2| abutting anges 22 extending `outwardly from the inner ends of the parts I8 and I9. Bolts 23 extend through the flanges y22 and thickened rim 2| of the plate 20 for securing the parts together. The thickened rim 2l is radially drilled at intervals therearound on the side of the plate facing the axle part I9, as indicated at 24. Steam nozzles.` 25 p circular rims 21a which are press fitted into the apertures I4 of the heads I2. -Shoulders 2lb project radially from the rims 21a and form back.

walls for these rims. The shoulders 2lb are spaced apart at a greater distance than the normal distance between the aperture dening rims of the heads I2, as best shown in Figure 3'. Bolts 28 extend through the heads I2 and through the shoulders 2lb to draw the heads outwardly against the shoulders 2lb, as shown in dotted lines in Figure 3. 'I'his springs the concave heads I2 outwardly and places the assembly under axial stress. As also best shown in Figure 3, the rims 21a are press-fitted into the apertures I4 of the assaggi ing for rotatably supporting the drum. A condensate removal pipe 30 is mounted in the trunnion 29 and abuts a seal 3i at its inner end.

A pipe 32I is mounted in the axle part I8 and 'receives a Tfltting 33 at its inner end. The outer condensate dippers or scoops 3l are mountedL on the ends of the pipes 3d and 35 adjacent to the cylinder Il and serve to scoop up steam condensate from the interior of the cylinder into the pipes. This condensate is then discharged out of the cylinder through the drain line 30. Additional brackets38 can be bolted on the flanges 25a to rigidify the pipe lines 34 and 35 extendf; ing on the outsides of the axle part I8. This curved pipe construction permits expansion of the' pipe lines when the cylinder is heated without unduly stressing the pipes.

v The axle part I9 also has a hollow trunnion 39 extending outwardly from its head or collar 2. This trunnion 39 receives a steam inlet pipe 40 for supplying steam to the interior of the axle part I9'. The steam will be ejected from the axle part I`9 through the steam nozzles 25 to heat the cylinder II. The condensate from the steam is removed from the cylinder as described above.

Therefore, according to this invention, the axle construction performs a quadruple function of rotatably supporting the drum; of initially stressing the assembly; of distributing steam to the interior of the drum, and of removl ing steam condensate from the drum.

As shown in Figure 4, the bronze cylinder I I of the drier drum I0 has a smooth polished, continuous, flat surface 4I receiving the web W thereon. The cylinder II is preferably a cast bronzle alloy known commerciallyas D H S Bronze. This bronze4 alloy has extremely ne and dense grain structure, has high heat transfer properties, and can be polished to a mirrorlike degree. Due to the neness and density of heads I2 so that the fit between the rims and the v heads produces a radially stressed assembly.

However, since the bronze cylinder III and the bronze heads I2 have a greater coeflicient oi thermal expansion than the ironor steel axle I5,`

they will expand at a faster rate than the axle when the drier drum is heated to drying temperature, Hence, the cylinder will elongate axially more thanvthe axle will elongate axially,

andthe heads will be carried outwardly. This v will expand radially at a rate greater'than the rim portions 21a of the axle. The initial, radially stressed press fit between the rims and the' bronze heads will thus be relieved. Under the circumstances, the assembly is unstressed at it The axle part I8 has a hollow trunnion portion 29 projecting outwardly from the collar 2'I. This trunnion 29 is adapted to -be mounted ina bearthe grain structure, nov pits are formed during the polishing operation. Y v

The preferred bronze alloys for forming the cast cylinder II have the following physical propertiesz. l f

Ultimate tensile strength. -90,000 to 120,000 pounds per square inch.v

Yield point-45,000 to- 95,000 pounds per square inch. 1 A

Elastic limita-40,000' to 60,000 pounds per square inch. Y

Elongation-25 to 10% vin two inches. Reduction of amar-,25% to 10%. Brinell hardness.185 to 250.

A specific alloy Within the above range that is satisfactory has the following physical properties:

Ultimate tensile 'strength- 119,400 pounds per square inch.

Yield point-94,200 pounds per square inch. Elongaticm.-15% in two inches. Reduction of area-15.5%. Brinell hardness.f'235. y

The smooth continuous surface 4I of the cylinder Il is imparted to the cylinder contacting surface 4la of the web Wsto produce a perfect machine glazed iinishon the web.

As shown -in Figure 6, the usual cast metal cylinder Ila has a rough surface 42 full of pits 43`which cannot be polished out of the metal. This rough surface 4Z will form a correspondingly rough surface 42a on the paper web W being dried thereon. ,The surface 42a is full of pock marks 43a from the pits 43. As a re' ksult the machine glazed web W' is highly imperfect.

As shown in Figure 8, the pits 43 in the surface of the usual drum cylinder Ila will form a steam pocket 44 under the web W' since the steam generated from the water in the web W becomes entrapped between the web and the cylinder. This trapped steam will actually blow the web W off of the surface of the cylinder with a result that the web is not uniformly dried.

In order to minimize the blowing of oi of driers it has heretofore been necessary to operate at lower drying'temperatures ,than are now possible. As a result, the heretofore known driers have been slow. This invention, by providing a smooth continuous drying surface makes possible a thorough contact between the web and the heated drying surface. As a result, higher vappended claims.

I claim as my invention: o 1. A Yankee drier comprising a cast bronze the webs cylinder for receiving a wet webof paper thereon, said cylinder having a highly polished mirror-like continuous peripheral surfacefree from pits and irregularities and composed of a fine grained, dense, bronze alloy with an ultimate tensile strength of from 90,000 to 120,000 pounds 95,000 pounds per-squareinch, an elastic limit of from 40,000 to 60,000 pounds per square inch, and a Brinell hardness of from l185 to 250 whereby said surface can be highly heated to rapidly dry a wet 'web of paper thereon without formation of vapor pockets under the web.

per square inch, a yield point of from 45,000to 2. A drierdrum assembly comprising a bronze cylinder having a polished continuous peripheral surface, a ferrous metal axle extending through Vsaid cylinder to rotatably support the cylinder, means connecting the cylinder and axle tpstress the same in opposite axial directions when cold, and means for heating the linder to axially expand the same at a higher rate thanrthe axle for relieving the stress.A

3. A drier construction comprising a hollow metal cylinder, stiff springable concave heads secured to the ends of said cylinder, said heads having central apertures therethrough, a'

hollow metal trunnion. extending through said cylinder and said apertures in said heads, said trunnion having rim portions force-fitted into said apertures, said rim portions having back walls spaced outwardly from said heads when the heads are unsprung, and bolts drawing said heads against said back walls to spring the heads outwardly whereby said drum construction is stressed radially and axially.

. 4. A drier drum assembly adapted for the production of machine glazed paper which comprises a hollow metalf" cylinder, stii springable concave heads closing the endsof said cylinder,

a hollow metal trunnion having a lower coeiiicient of expansion than said cylinder and said heads extending through the cylinder and force-fitted in the heads, means springing said heads outwardly into xed connection with said trunnion whereby said assembly is under radial and axial stresses, means for introducing a heating fluid to said ldrum to relieve said stresses and heat the cylinder, and means for removing spent heating iluid from thedrum.

5. A drier drum comprising a cast bronze hollow cylinder. having a highly polished peripheral surface, concave cast bronze heads secured to the ends of said cylinder and having central apertures therethrough, a hollow ferrous metal trunnion extending through Vsaid cylinder and' having enlarged rim portions force-fitted insaid apertures, shoulders adjacent said rim portions.

bolts springing said heads outwardly against s aid shoulders, a dividing Wallin said trunnion, steam jets on one side of said dividing. wall communieating with the interior of the trunnion andthe cylinder, means for introducing the steam to said steam jets, steam condensate drain lines extending ,into said cylinder from said trunnion on the opposite side of the dividing wall whereby radial and axial stresses are relieved when steam is introduced into the drumvto heat the cylinder due to the higher rate of expansion of said bronze material members over said ferrous metal trunnion. e

6. The -method of making machine glazed paper which comprises contacting wetV paper with the highly polished bronz'e surface of a heated, fine grained bronze drum, and vaporiaing4 the moisture in said paper lat a rapid rate with: out blowingthe paper off said surface.

'1. The method of rapidlydrying A-vvet paper webs to impart a machine glazed nish'thereon which comprises vintimately sontactlng a wetpaper web with ,the mirror-like continuous surface of a rotating drum composed throughout .itsv cross-sectional depth of cast' nue-grained dense bronze, and continually heating said surface to a high temperature to rapidly drive moisture from the web, whereby the continuity of the surface will eliminate h vapor pockets botween the web and the surface.

RARLE..

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