US1423969A - Multiple-roll supercalender - Google Patents

Description

C.SCHURIV1ANN.

MULTIPLE ROLL-SUPERCALENDER.

APPLICATION man AUG. 29, 1921.

Patented July 25, 1922.

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CARL soirtiaamnn, or Dus sELDoRr, GERMANY.

MULTIPLE-ROLL SUPERCALENDIPR.

Specification of Letters Batent;

Patented J iii 25, 115E273.

Application filed August 29, 1921, Serial No. 496,686.

1 0 all w from i 6 may concern i I Be it known that I, CARL SGHI'FRMANN, a citizen of the German Republic, and residing at Dusseldorf, Germany, have invented cerby an upper anda lower hard roller. This has the following drawbacks.

The hard rolls mentioned are, in consequence of their necessary thickness both heavy and expensive. Owing to the difficulty in their manufacture and their tedious machining they require a long term for delivery, in particular if the casting should prove faulty, what frequently only appears towards the end of the machining process, so that the delivery of the whole super-calen dcr is thereby delayed.

hen, as in most cases, the journals are cast in one piece with the roll and are not made as separate steel trunnions or a steel shaft pressed through the roll, they have to be made of a comparatively large diameter, so as to render them proof against breaking, whereby-the frictional moment in the hearing is unnecessarily increased, in particular in the lowest roll.

Between the terminal hard rolls. alternately elastic rolls made of paper, cotton or the like and thin, non-elastic rolls (chill cast rolls) are disposed. The number of the latter determines the maximum speed and the calendering effect of the calender, as only the contact points between elastic and hard rolls have a smoothing eifect which is the greater, the thinner the hard rolls are, because. at a constant pressure the surface pressure between the elastic rolls and the hard rolls will increase with a decrease in the diameter of the hard rolls. The passages between the lowest and the uppermost pairs of rolls are, therefore, with the heretofore constructed super-calenders are, owing to the large diameter of the terminal hard rolls not as effective as the others.

The terminal hard rolls are, by taking up the total pressure, caused to sag, and this sagging is communicated tothe neighboring, elastic (paper or cotton) roll, as the latter will, after a short time, adapt itself to the harder roll. Thesagged hard roll, therefore, rounds the paper roll above it,

the neat hard roll, however, tends to force.

the same paper roll into a concave form. The shell of the paper roll is, therefore, at each half revolution, subje'ctedto adeformation; If, however, the lowest hard roll is made with a rounded surface, so that, at

a given load, it will line up straight against the-paper roll above it, the surface of contact' will, at a different load, no more be rectilinear. I I I It is, now, the objectof the present inventionto obviate the drawbacks mentioned by means of a novel arrangement of the rolls.

In the accompanying drawing Fig. 1 shows the heretofore employed arrangement of rolls in side elevation, Fig. 1 only the lower part of the same in front elevation, Figs. 2 and 2 respectively, are the corresponding views of the new arrangement of the rolls, which has the following essential features:

1. For the terminal. hard rolls at the top or bottom, or preferably both at top and bottom, are substituted elastic (paper or cotton) rolls with a steel shaft through them.

The drive of the calender has, in consequence, been shifted from the lowermost or third. roll to the second or seventh roll from below.

The total number of hard rolls has been reduced by 1, that of the elastic rolls been increased by 1. Therefore, obviously, also the number of hard roll scrapers is reduced by 1, and the total height of the calender is, at the same diameter of the rolls, reduced by the difference between the diameter of a medium sized paper roll and a thin hard roll. I

4. The smoothing points, which remain of the same number, lie only between thin hard rolls and elastic rolls and. therefore, produce a maximum effect. If the rolls are, at the same time, slightly staggered as shown in Fig. 2 and described in the German Patent specification No. 252,151, the diameters of the middle hard rolls and paper rolls may be reduced to their practically smallest size, as the danger of their yielding sideways is removed.

If, with this new arrangement, thelowest paper roll should in consequence of the weight resting upon it, sag it will be pressed by the thin hard roll above it, most at its two ends. Contrary to the heretofore arrangement the lowermost, elastic roll (Fig. 2 has to adapt itself to the cylind'ricat hard roll above it, and it will have to assume after a short time a rounded form, which corresponds to its load, so that it will, along its whole length, bear evenly against the thin hard roll. In case the load should vary, the rounding will change by itself correspondingly. The strength of a roll pressed of paper or cotton with a steel shaft through it against sagging greater than may appear at the first moment. Not only the section of the steel shaft will here come into, question, but also that part of the paper shell section which, in case of such sagging is subjected to a compressing strain. S0,

for example, the strength of a paper roll, the shaftdiameter is equal to, one half of the outside diameter of the roll, will be about three times as great as the strength of the inner shaft alone. A tightly compressed paper or cotton roll therefore, verywell adapted asterminal roll in a cale der, already alone forthe reason that its journals are made in one piece with the inner steel shaft.

The drive of the new calender (Fig. 2)

is effected always from a thin hard roll. For this, obviously the second or 4th roll may. according to the total number of rolls employed, be chosen. When the Lth roll is driven, it will be found advisable to drive from it also the second roll from below with a small lead, so that the tension pro duccd in the upper passages will not too suddenly disappear in the paper web and thereby cause the latter to tear at the driven roll.

I claim:

1. In a multiple roll calender an elastic terminal roll disposed below or at the top, or both below and at the top.

2. In a multiple roll calender with elastic rolls below and at the top, the drive effected from the second or fourth roll from below.

In a multiple roll calender with elastic rolls at the top and bottom, the drive eifected from the fourth roll from below, and the second roll from below again driven from said fourth roll.

In testimony whereof I afiix mysignature in presence of two witnesses.

CAR SCHURMANN.

Emit; BaUcERT.

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