US2168233A - Roll, specially suitable for use in paper making machines - Google Patents

Description

1, 1939- w. H. MILLSPAIUGH 2,168,233

ROLL, SPECIALLY SUITABLE FOR USE IN PAPER MAKING MACHINES Filed May 26, 1937 Patented Aug. 1, 1939 UNlTED STATES 2,168,233 ROLL, SPECIALLY sm'mnm roa use m PAPER MAKING MACHINES William Hulse Millspaugh; Sandusky, Ohio Application May 26, 1937, SerialNo. 144,948

In Great Britain May 29, 1936 g 2 Claims. (Cl. 9115-49) This invention relates to rolls specially suitable for use in paper malnng machines and particularly in presses of the kind used in such machines, and which comprises two or more superposed rolls between which a web or sheet of paper, comprising one or more plies of paper (hereinafter referred to generically as a web of paper) is passed 'by the aid of one or more press felts for the purpose of squeezing or expressing water from it by pressure exerted between the rolls. The lower roll, or each lower roll of the press may "bea suction roll, or it may be a plain roll, that is to say, an unperforated roll, but the top roll is always a plain roll, thatis to say an unperforated roll. The pressure exerted between the, rolls for the purpose mentioned, may be due to the weight of the rolls alone, or to the weight of the said rolls and additional pressure applied to the journals of the top roll, the pressure between the rolls being a longitudinal line pressure.

It is important that this line pressure shall be capable of wide variation in order to obtain the desired thickness and finish of different papers to be produced. Top rolls have heretofore been made of cast iron, as hollow bodies or shells having integral therewith, end Walls in which roll journals are fixed, such roll bodies or shells with integral end walls being cast in cored mould boxes in the ordinary manner. For use, such top rolls have been provided with a covering of bronze, rubber, or other non-rusting material or composition. Top rolls have also been made of a solid block of granite provided with a heavy central metal shaft for supporting it in position for use. the disadvantages attending the use of each of these constructions of top roll are that in order to obtain a stiff enough roll to resist excessive plexure, it becomes necessary to make it very heavy, and the papermaker is not able readily to adjust the line pressure on the web of paper to the best advantage, consequently the paper is liable to be crushed, or its thickness or finish to be adversely affected. This is a great drawback where bulk production of paper is required.

Another disadvantage is that with a heavy top roll of either of the known kinds above referred to, it is necessary to provide the roll with a sumciently large camber to compensate for the deflection of the bottom press roll against which it bears. The two rolls have to contact withan even pressure across the width of the web of paper travelling between them, as any concentration of load at one part of the line'of pressure would make the paper thinner at that part and then the paper would be unsaleable. When the forged or cast steel on be fixed. within the end lower press roll is a suction roll and. too great a line pressure is applied thereto, such a roll will become unduly deflected.

, With the higher speeds at which modem-paper making machines are now run, particularly for making newsprint, itis desirable tohave'allrolls dynamically balanced that is to say, of even wall thickness and density at every cross section thereof in order that balancing weights need not be applied to them, especially such rolls as top press rolls which do not have a direct drivebut are driven by-contact with the travelling web of paper. With the known construction of moulded cast iron top rolls hereinbefore referred to, this is not "practicable because of mechanical limitations in the foundry and'machine shop. It is also not practicable to make hollow top rolls of account of the high manuiacturing cost.

An object of the present invention is to provide a roll specially adapted for use as a top roll in a press for a paper making machine, which shall be free from the disadvantagesof the known constructions of top rolls hereinbefore referred to.

For this purpose,- a roll according to the present invention comprises a centrifugally cast hollow body or shell (hereinafter called a shell) of uniform thickness and density circumferentially I at each cross section of its length, and formed of The steel of which the shell is made may be a 35 straight carbon steel. or an alloy stecl,of any known or suitable composition adapted to offer great resistance to flexure by applied pressure, when in the form of a shell.

The casting of the shell centrifugally can be effected in any known or suitable manner, as for" example in the manner commonly adopted for casting cylinders or tubes of cast iron and bronze centrifugally.

The metal end walls or heads provided with journals are or may be formed of steel and can portions of the shell in any known or suitable manner.

A steel roll constructed as described is, for use in a press for a paper making machine, provided with a covering of non-rusting material.

Inthe accompanying drawing, Fig.1 shows in longitudinal central section, a steel roll construct. ed according to the present invention. .Fig. 2 is a central longitudinal section of a portion'of one end of the roll, showing an alternative mode of securing the metal end wall or head thereto.

Referring to Fig. 1, a is a centrifugally cast hollow shell of uniform thickness and density from end to end and formed of steel capable of offering considerable resistance to flexure by applied pressure, and b, b, are metal heads of suitable formflrmlysecinedintheoppositeendportions of the shell, as for example by welding them in position, or by shrinking the end portions of the shell upon them. Each end wall is provided with ajournalcthatmaybeintegraltherewithorbe made separatetherefromandbesecm'edina hole boredinthesaidendwall.

Fig. 2 shows one of the end portions of the shell a provided with a metal end wall D b3, the portion 12 of which is fltted within the adjacent end portion of the shell, and the flange portion 12 bearing against the adjacent end of the shell. Thesaidheadissecuredinpositionintheshell by screw hook bolts, one of which is shown at d. The bolts" extend through longitudinally arranged lateral grooves in the portion b of the head and through holes in the flange portion b of.the head andare provided at their inner ends with lateral extensions or books d arranged to extend into notches or recesses o formed in the inner side of the shell 1: and enga i a flat side or shoulder in the notches or recesses, the outer ends of the screw bolts being provided with tightening up nuts e.

By making the roll shell (I centrifugally,'it ensured that the density and thickness of its wall 'will be imiform from end to end, of the roll, thus ensuring that the whole shell shall be in balance when in use without boring, except at the ends for the heads. For high speed use, the shell can, if desired, readily be rough bored. For wide-machines the shell may be cast of greater thicknes and be taper bored from near the centre of its length to near each it will be stiflened at its central portion to resist flexure by applied praslne. In this case also, the shell will be of uniform thickness and density aroundthe whole of its circinnference at any cross section of the shell so that balance of the shellwillbemaintainedinthiscasealso.

Foruseinapapermak ingpresatheimproved roll'is covered with non-rusting material I, as for example rubber'or bronze, but preferably with a covering consisting of a composition known under the trade name of Stonite", formed of minute pieces of rock embedded in a binder consisting of vulcanised rubber and having a smooth sln'face, as described in the specification of British Letters Patent No. 363,025. Such a covering is particularly suitable for use on a top roll of a-pres, as a wet web of paper I brought into contact therewith will not readily stick thereto.

A roll constructed according to the present invention is both stiffer and lighter than a moulded cast iron roll, or a granite roll, of the same length and diameter, as will appear from x the following statement as applied to a roll for a 244 inch paper making machine.

A roll constructed according to the present invention and having a length of 244 inches and a diameter of 28" when covered with *Stonite' thick, will weigh 7 tons complete and give a line pressure across a wet web of paper 240 inches wide between it and an adjacent lower roll, of 55.3 pounds per linear inch when unweighted. A moulded hollow cast iron eter and therefore heavier.

gmsothat,

roll such as hereinbefore referred to, of the same length and diameter as the new roll and such asis now used in a paper making press, would weigh 10 tons, giving a line pressure of 98 lbs. per linear inch unweighted. These line pressures'are the minimum line pressures of the two rolls when unweighted. Furthermore, the cast iron roll would have only 70% of the stillness against deflection of the new steel roll it both 'rolls were equally weighted for. greater line pressures. A solid cast iron roll of the same lgth and diameter would weight 15 ,5 tons, and would have of the rigidity of the steel roll, and when unweighted, would exert a line pressure of lbs. per linear inch. For the same deflection as that of the new roll, a cast iron roll would need to be made of greater diam- A solid granite roll of the same external length and diameter as the new steel roll, and provided with the usual steel central shaft, would weight 9 tons giving. a line roll and would consequently be of greater weight and exert a, greater line pressure than in the case of the new steel roll.

A steel roll constructed according to the present invention, being both stiffer and lighter than other known rolls of similar length and diameter, can advantageously be used for other purposes than for a top roll in a press, for example as a. pressure roll on a; larger dryer cylinder where the line pressure applied to a web of paper is very high and a stiff roll is necessary in order to obtain an even flnished'web or sheet of paper.

What I claim isv 1. A roll comprising a centrifugally cast shell having its wall of even thickness and density circumferentially at each cross section of its length and formed of steel capable of oifering considerable resistance to flexure by applied pressure, a covering for said shell of non-rusting material, said shell being constructed with angularly spaced notches in its inner surface near its ends, metal end walls or heads having flanges abutting the ends of the shell and provided with journals, bolts through said flanges extending through the heads, said bolts having hooked ends arranged to engage the notches in the shell and retaining nuts on said bolts outside of the inner surface near its ends, metal end walls or heads having flanges abutting the ends of the shell and provided with journals, bolts through said flanges extending through the heads, saidbolts having hooked ends arranged to engage the notches in the shell and retaining nuts on said bolts outside of the flanges.

WILLIAM HULSE ILILLSPAUGH.

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