US1762329A - Method of and apparatus for saturating sheet material by calenders - Google Patents

Description

June 10, 1930. w, G, DUDLESTON 1,762,329

METHOD OF AND APPARATUS FOR SATURATING SHEET MATERIAL BY CALENDERS Filed Juhe 11. 1926 `atented ,lune W, w3@

WILLIAM G. DUDLESTON, OF CHICAGO HEIGHTS, ILLINOIS, ASSIGNOR, BY MESNE AS- SIGNMENTS, TO THE PATENT AND LICENSING CORIPORATION,- OF lBOSTON, MAS- y SACHUSETTS, A CORPORATION OF MASSACHUSETTS METHOD OF AND APPARATUS FOR SATUBATING SHEET MATERIAL BY GALENDERS Application med June 1i,

This invention relates to a method of and apparatus for -saturating sheet material, and is more particularly designed for the continuous progressive saturation of a web of ,a indeterminate length, being also especially suitable for webs of comparatively slight tensile strength.

Apparatus embodying my invention finds a field of utility in the manufactured roofing art. A large amount of the manufactured roofing of today is Vmade of sheets of feltedv fibrous material which are saturated and coated with asphaltic compounds, and further treated in various ways. The material commonly used as a base for such roong is made from a pulp of rag or asbestos fibers, or the, like, which is formed into continuous sheets in a paper-making machine, the fibers being loosely felted to- .20 gether as the sheet is formed. Sheet material of this kind, known as roofing felt, is ordinarily of a relatively loose, (porous texture, capable of absorbing a consi erable quantity of saturant. It has, however, relatively low tensile strength so that the problem of feeding such material without subjecting it to more than'moderate tensile stresses is one which demands consideration in the construction of a machine to handle and operate upon it. This is particularly true of the'step of saturating with a lique fled asphaltic compound. The liquid asphalt is of an oily consistency, and has a tendency to lubricate the interfelted fibers,l

ythus reducing vfurther the tensile strength ofthe sheet. ln order to fill up the pores and voids betweenthe fibers in the sheet by immersing the sheetin a pool of saturant, the saturant must have a relatively high degree of fluidity, preferably combined with alternating changes of pressure to Vallow the air orl gases caught in the pores to escape and to force the saturant thereinto. Where commonly used asphaltic compounds are employed as saturants, the fluidity is usually obtained byh'eat while the pressure changes may be effected by leading the sheet down and up a number of times in a deep body of saturant, the head of the liquid producing 50 the increased pressure.

1926.l Serial No. 115,89.

In order to obtain suihcient fluidity of the saturant without raising it to a prohibitive temperature which would tend to scorch or injure the fibrous sheet, it is necessary to vuse a relatively low melting-point asphalt practice, the sheet is led through a pool of low melting-point asphalt of considerable size inorder to provide suciently extensive immersion for thorough saturation. The Immersion step may be carried out by leading the web beneath the surface of the saturant at one end of a container of considerable length, extending it through the saturant for substantially the entirelength of the container, and leading it out at the further end. Or series of upper and lower rolls may be providedin a container of considerable depth, the web being passed over the upper and lower rolls alternately. In either case, a considerable length of web is drawn through the body of thesaturant again'stthe skin friction of the saturant on the rough fibrous 'faces of the web. This dragging action combined with the `weakening effect of the saturant upon the fibrous structure of the web renders the latter linable to breakage, particularly if for p any reason the viscosity of the saturant happens to increase. As a result, it is'necessary to keep a relatively large body of saturant at a given temperature and it is also necessary to 'devote a considerable amount of fioor space in a plant for thesaturating pool.

`The tops of these pools are frequently flush or nearly flush with thefloor level, a source of danger to the workmen attending the apparatus.

By my invention, I provide apparatus which occupies relatively little oor space, which enables felted sheet material to be fed through the saturating process with very littletension on the sheet and hence practically no danger of breakage of the sheet,

the sheet firmly therebetween, liquid saturant being flowed upon a face of the sheet immediately prior to its passage between eaclrpair of the rolls, so that the saturant is rolled together with the web and is pressed thereinto and therethrough. This held in the voids between the fibers.

step of squeezing and pressing the felt sheet and the saturant is effective only to the extent of thoroughly coating or wetting the individual fibers in the sheet. Further squeezing of the sheet'preventsthe further absorption of saturant; in fact, once thel fibers are wetted, squeezing the sheet tends to press-saturant out of the sheet, after the manner of a wringer pressing from a wet towel water that has been taken up arIid n order to complete the saturation of the sheet therefore, it is necessary to follow the squeezing process by further treatment to l fill up the voids or pores in the sheet. This Amay be accomplished .by pressing saturant against a face `of the sheet without squeezing the sheet. This may be done by passing the sheet through a stack of rolls whichare supported with sufficient clearance to permit the passage of the sheet vand a layer of saturant. By fiowing the saturant on the sheet as it comes into contact with each roll, the liquid is caught between the sheet and roll and is pressed into the ores of the felt without any squeezing o the sheet itself.

The saturating action of the rolls can bemade more effective by suitable temperature control.V If the temperature of the sheet, after being thoroughly wetted with saturant, is progressively reduced in the vpresence of excess saturant, the contraction of the vsaturant and residual air in the sheet occasioned by the cooling, draws more of the saturant into the sheet. This feature of temperature control maybe carried out by regulating the steam admitted to successive rolls in a stack so that each successive roll in the stack is coolerl than the onebefore it. Thus for example a sheet Aof roofing felt is passed through a calender stack and squeezed between the nips with asphalt at a temperature of about 450o F., wetting all the fibers thoroughly. Next, the sheet is passed through another calender stack with spaced rolls to obviate squeezing the felt. Excess saturant is 4supplied to both faces as required during the passage of the sheet through the stack and the cooling of the sheet by the successively lower temperatures of the rolls contracts the asphalt and air within the pores and sucks more saturant in. This sucking action in conjunction with the pressing of the rolls against the sheet effects a high degree of saturation.

Further details of structure and advantageous features will be set forth in the description which follows and are disclosed on the drawing, of which:

Figure 1 is a side elevation of the apparatus including an embodiment of my invention, part of the apparatus being diagrammatically shown.

Figure is an end elevation of a set of calenders.

Figure 3 is a fragmentary showing partly in section of a calender, showing the method of supporting and heating the same.

Fi. re 4 is a View of a spout for supplying liquid saturant to the sheet.

Figure 5 is a sectional view showing the 4manner of application of saturant through a spout to the'traveling sheet.

Figure 6 shows an alternative means of applying the saturant to the sheet.

Figure 7 shows an alternative heating means for a calender roll.

Referring to the drawing in detail, 10 represents a supply roll of sheet material, such forA example as roofing felt. In order to maintain a continuous length of vsheet to pass through the machine, a splicing device generally indicated at 11 may be supplied to join the ends of successive rolls together, a looping device indicated at 12 being supplied to provide a reserve supply of sheet to feed through the apparatus during the splicing of ends in the splicer 11. The sheet of felt .is preferably preheated as by a series of heated rolls 13 of which there may be any desired number, and which may be heated -in any desired way, as for example by steam pipes connected as shown in Figure 3. The preheated sheet may then be led through a calendering mechanism comprising a plurality of calender rolls 14 which for economy of floor space and utilization of gravity. pressure may be arranged in superposed relation. The rolls 14 are each supported on a cross bar 15 at each end of the roll, these cross bars 15 resting on nuts 16 which are adjustably mounted on screw-threaded vertical rods 17 which pass loosely through perforations in the cross bars 15. 'Ihe nuts 16 are so arranged on the rod 17 that when the lat.'- ter are raised by a motor-driven mechanism m It is pre erred that the rolls 14 be heated to maintain the saturant in Huid conditionand to prevent sticking of the sheet to the rolls. This may be done by any desired means suitable .for the required tempera- 15 tures, the temperature used being :determined by the characteristics of the saturant employed. In the embodiment shown in the drawing meansv for heating the rolls by steam have been indicated in Figures 2 and 3, the piping beingomitted from Figure4 1 to avoid undue complication ofdetail. As shown in Figure 3,' steam may be introduced through a supply pipe 20, the pipe entering the hollow roll by a suitable packed joint such as is well known in the steamtitting art. The exhaust pipe 21 may be led in through the opposite end 'of the roll, the end 22 being preferably turned down in order to exhaust from the -bottom lof the roll any condensed liquid which may be formed there. Valves may be employed on the branches of the pipes 20 and 21 to regulate the steam supply -to the several rolls. Instead offsteam for heating the rolls, I may use electricity, burning or heated gases, heated oil, or any other heating agency suitable for the purpose, together with means for regulating the temperatures of the individual rolls.

As indicated in Figure 1, the saturant is preferably flowed on to a surface of the sheet innnediately before it enters the .nip of a pair of successive rolls. As the sheet is threaded back andl forth between the successive rolls, saturant is dowed alternately on the two sides of the sheet and from'opposite sides of the stack of rolls. The hot asphalt may he suppliedf` through pipes 23 which are 'preferably steam jacketed by surrounding pipes 24 yin order to maintain the asphalt passing therethrough at the de`.

sired temperature, and to prevent premature cooling thereof which would quickly clog the supply pipes 23. At the delivery end of the supply pipes 23, suitable nozzles 25 are preferably attached, these nozzles being elongated horizontally as indicated in Figure 4f to supply a liquid sheet of saturant to the entire width of the traveling felt sheet. In order to insure thorough saturation, it is preferred to supply an excess of saturant beyond what the sheet can absorb, the excess being caught as by pans 26 and returned by suitable pumping means 2'? t0 the heated reservoir from which the asphalt is supplied to the pipes 23.4

Instead of supplyingthe 'saturant in streams from nozzles 25, I may substitute for the nozzles, pansor containers 28 which are supplied with liquid saturant as by pipes 29 and may be maintained atthe proper temperature as by steam pipes 30 or other equivalent heating means. The pans 28 are constructed with an open end, the sides adjacent that end .being of curved shape to permit the pans to be positioned adjacent to the rolls with a very'slight clearance be-4 tween the pan and thel surface of the felt sheet. In this form of construction, the sheet in passing comes in contact with the body of saturant contained in the panj28 and picks up a coating of saturant which is carried therewith to the nip of the rolls.

The layer of saturant deposited upon the sheet either by a nozzle 25 orby a pan 28 is worked into the felt as it passes between a pair of rolls, the pressure of the rolls serv'- ing to squeeze the sheet and to press the porL tion of the saturant into thepores and voidsY thereof, so that all the individual fibers of the sheet are thoroughly wetted with the saturant.' If desired, the extent or completeness of saturation may be controlled to some extent with apparatus of this kind by regulating the number of rolls between which the sheet is passed and the pressure between successive rolls. The saturant may also be supplied on one side only of the stack, it thus being applied successively to one side only of the sheet and forced through to the other side. In the drawing two stacks of calendars are illustrated, but as many more may be employed as desired. For thorough saturation of the sheet it is preferred to separate the rolls of the second stack so that the sheet will not be squeezed when passing betweenl them. This is easily done by adjusting the supports for the several rolls. The temperatures of the individual rolls may also be regulated by adjusting the steam valves if steam is used to heat the rolls, or regulating the current if electricit is used. Other heating means may he use if preferred.A It is obvious that each pair of rolls, besides -pressing the saturant into the felt, will serve as feedrolls to advance the sheet, hence there is 'no considerable length of the sheet being drawn through a viscous liquid as in the case of the ordinary saturating tanks, and the liability of damage to the sheet from breaking or tearing is reduced to a minimum. Since a machine. of this kind can be run at a relatively high speed, the sheet passes through quickly and is in contact with the heated elements and bodies of saturating fluid for only a relai tively short time. Hence it is possible with this machine to use as a saturantasphaltic compounds of relatively high melting-point ico which by reason of their physical properties as well as their high melting points, are amore desirable constituent 4of roofing elements than th(` lower melting-point asphalts. 5 Having thus described an embodiment of my invention, it should be evident to those. skilled in the art that many changes and modifications may be made therein without departing from its spirit or scope as dem fined by the appended claims.

' I claim:

1. The method of saturating a web of fibrous material, which comprises applying liquid saturant to the faces of the web, squeezing the web and saturant together, flowing a film of saturant on each face of the web, and successively pressing said films into the web without squeezing the web.

'2. The method of saturating a web, of fibrous material with a heat-liquefied saturant,- which comprises applying liquefied saturant to the web, squeezing the web and saturant together, flowing additional saturantonto the faces of the web, and reducing the temperature of the web and the saturant Carried therewith.

3. The method of saturating a web of fibrous material with a heat-liquefied saturant, which comprises flowing saturant onto 30 the faces of the web, squeezing the web and saturant together, flowing more saturant onto the faces ofthe web, pressing alternately against opposite faces of the web without squeezing the web, and progressively reducing the temperature of the web during said pressing operations.

4. An apparatus of the class described, comprising a series of rolls each of the intermediate rolls of the series forming a nip 4o with each of two other rolls and the end rolls forming nips with their respective adjacent lntermediate rolls through which nips a web of brous lmaterial may be fed in zigzag formation, and means for directing streams of saturanttowardsaid nips to coat the web as it passes thereto.

5. An apparatus of the class described, Acomprising means for flowing liquid saturant onto the faces of a sheet of fibrous ma# terial, means for'squeezing the sheet and the saturant together, said squeezlng means comprising a plurality of rolls between 'which the sheet is adapted to be passed, a series of spaced rolls having suiiicient clearance to permit the passageA of the sheet therebetween without "squeezing, and means for iiowing films of saturant onto the faces of the sheet immediately before contacting the spaced rolls.

In testimony whereof have afiixed my signature.

WILLIAM G. DUDLESTON.

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