US2985100A - Calender stack - Google Patents

Description

L. HORNBOSTEL CALENDER STACK May 23, 1961 2 Sheets-Sheet 1 F4qhl Filed Jan. 29, 1958 L/oyd Horn bosfe/ -4 /%h4.; 44 ZZ L775 y 1961 HORNBOSTEL 2,985,100

CALENDER STACK Filed Jan. 29, 1958 2 Sheets-Sheet 2 Lloyd Ham bosze/ CALENDER STACK Lloyd Hornbostel, Beloit, Wis., assignor to Beloit Iron Works, Beloit, Wis., a corporation of Wisconsin Filed Jan. 29, 1958, Ser. No. 711,827

7 Claims. (Cl. 100--163) This invention relates to the portion of a paper machine known as the calender or calender stack, and more particularly, to an improved multi-nip calender.

Although the instant invention may have utility in other fields involving the pressing, smoothing, ironing or the like treatment of a strip of flexible material, a particularly preferred use is in the paper machine calender. The operation of the calender in paper machines is well known and understood in the art. The purpose of the calender is to compact the paper to some extent and to give it a fine smooth finish. This effect is obtained on both sides of the paper by the use of friction and pressure. The calender stack comprises a plurality of upright or vertically aligned calender rolls. The lowest or bottom roll of the stack is driven mechanically and it, in turn, may drive the roll immediately thereabove, and so on, by friction throughout the stack. On the other hand, calender stacks are also provided wherein there are separate drives for one or more of the other rolls above the bottom roll, either for the purpose of obtaining superior drive correlation, or for the purpose of deliberately effecting speed diiferentials at nips in the calender. There is a certain amount of slip between the rolls and the result is that a substantial amount of friction acts on the paper as it passes through each of the calender nips.

In the ordinary calender, the calender rolls are made of fine grained cast iron that is susceptible of a high polish, in order to give a fine finish; whereas in super calenders, some of the rolls are made of compacted fibrous material such as paper and these rolls are called fibrous rolls. The paper web is directed first to the top roll of the stack and it passes either over the top roll and through the top nip or directly through the top nip from which it follows downwardly to successive nips and is ultimately transferred through a bottom nip and onto suitable windup means.

In many instances, eflicient calendering of paper requires a relatively large number of nip treatments at relatively low pressures, or at pressures at least sufliciently low to prevent crushing of the paper while ironing it smooth. In general, the rolls are so mounted in the ordinary calender that the entire weight of each roll rests on the roll therebelow. This is accomplished by mounting each roll so as to permit limited vertical movement thereof. The full weight of a plurality of heavy rollers is thus applied to the paper web passing through the bottom nip in the stack; and the bottom or king roll is usually formed with a slight crown or enlarged crosssectional area in the middle thereof in order to compensate for the deflection of the king roll downwardly which is brought about by the application of the rather substantial weight of the rolls thereabove to the king roll.

As will be appreciated, the king roll is provided with fixed bearings at opposite ends thereof and when a substantial load is applied across the top of the roll there is a tendency for the middle portion of the roll to be deflected downwardly (from the normal generally horizontal axis of the roll). For this reason, it is the general practice to have a crown of perhaps 0.01 or 0.02. inch formed in the center of the roll to compensate for the deflection. Actually, the crown may be formed so that the deflection of a given load is such as to create a substantially horizontal upper nip-defining" surface for the roll, or the crown may be slightly greater so as to provide substantially equal pressures at the central portion of the nip and at the edges thereof. In any event, a particular type of paper in the ordinary calender requires a specific type of crown for a specific number of calender rolls in the stack (or for a specific weight of calender rolls in the stack).

In addition, it has been found that another variable is introduced into the force system here involved. The bearings which support the ends of each of the calender rolls above the king roll have appreciable weight. For example, each of bearings may weigh approximately 1000 pounds, while a cast iron roll itself may weigh approximately 10,000 pounds. In a typical paper machine, the diameter of the king roll may be about 40 inches and the diameter of each of the rolls stacked thereabove may be about 18 inches. All of the rolls have an axial dimension that is the Width of the paper machine which in modern-day machines may be as much as 20 to 25 feet. Since the rolls are supported through the bearings at the extremities thereof there is, of course, a tendency for each roll to be deflected downwardly slightly at the central portion thereof by virtue of the weight of the roll. If the king roll has a slight crown in its normalconfiguration, however, a slight downward deflection of the king roll in the middle portion thereof (in order to support the weight of all of the rolls stacked thereon) may result in a substantially horizontal nip-defining top surface for the king roll. This is so if there is a precise correlation between (1) the contour of the crown, (2) the number of stacked calender rolls (or the weight thereof), and (3) the particular web being processed in the calender. If these factors are not carefully correlated, it will be appreciated that defective operation of the calender may result. The difficulty here is that calenders are preferably adapted for a number of different operations, which operations cannot be varied without careful variation of the factors just mentioned so as to obtain the proper correlation therebetween. Moreover, it has been found that the weight of the hearings, or the weight which the bearings apply to the extremities of each calender roll is a fourth factor which materially affects the operation of the calender stack.

The instant invention relates to a unique structural concept which permits a great deal of flexibility in operation of a given calender stack and which permits unique control of the load forces and the distribution thereof across the calender. In addition, the instant invention provides a simplified arrangement for accomplishing these desirable results using a normal present-day type of calender stack structure with relatively slight alterations therein. This is accomplished by providing individual load relieving means for each bearing, with such load relieving means supported independently on a separate frame element, which is preferably merely a cable with stop means mounted thereon. Such stop means are mounted adjacent each of the individual bearings and linking arms interconnecting the same are mounted for independent load relieving at each of such bearings. The stop means are connected to the linking arms so that the conventional lifting means may still operate to lift the entire stack, when such is desired.

It is, therefore, an important object of the instant invention to provide an improved calender stack arrangement and method of calendering.

Another important object of the instant invention is to provide an improved multi-nip calender comprising a calender frame, a stack of calender rolls in the frame including a bottom roll and a plurality of superimposed rolls, separate and independent bearings rotatably carrying the ends of each of said superimposed rolls, means providing a stop adjacent each of said bearings, and linking means interconnecting each bearing with the stop adjacent thereto for independently urging each bearing upwardly.

Other and further objects, features and advantages of the instant invention will become apparent to those skilled in the art from the following detailed disclosure thereof and the drawings attached hereto and made a part hereof.

On the drawings:

Figure 1 is a side elevational view of a calender stack embodying the instant invention;

Figure 2 is a detail view of a bearing mounting employed in the practice of the instant invention;

Figure 3 is a top plan view of the stop means employed in the practice of the instant invention;

Figure 4 is a top plan View of cap means used in the practice of the instant invention;

Figure 5 is a side elevational view with parts broken away and parts shown in section of the stop means of Figure 3 and the cap means of Figure 4 in operative assembly; and

Figure 6 is a side elevational view of the elements shown in Figure 5 in another position for these elements in the operation of the instant device.

As shown on the drawings:

In Figure l, a calender stack indicated generally by the reference numeral 10 is shown comprising a main upright frame member 11 structurally connected to a cross beam 12 which, in turn, is structurally connected to another upright supporting member 13 (shown partially). The upright supporting member 13 carries the last roll 14 of the dryer from which the web W travels under a guide roll 15 and over a guide roll 16.

The calender 10 comprises a bottom roll and a plurality of superimposed rolls 21 through 29 having separate and independent bearings 21a, 21a, 22a, 22a, etc. through 29a, 29a, rotatably carrying the ends of each of said superimposed rolls 2129, and it will be noted that only the bearings Zda, 22a, 23a, etc. on one side are shown in Figure 1.

Although certain details of the bearing mountings are not important for the purposes of the instant invention, because they are conventional in the art, it will be noted that the top bearing 29a is carried in a bearing frame 2% which in turn is bolted to a pivot arm 29c pivotally mounted on the frame at B. It is also apparent that the other bearings 21a through 28a are swingably mounted on pivots P to permit limited vertical movement of each roll 21 through 29 independently of the other rolls.

Overhead lifting links L, L (on opposite sides of the calender frame 11, only one of which being shown) are provided in the conventional manner to permit limited vertical lifting movement of each of the bearings 21a through 29a. The oversize connections such as at 1 at the top of the link L permit limited vertical movement of the bearing 29, when the lifting arms are not in operation, but when it is desired to lift all of the bearings for shutdown and repair, the linking arm L is raised upwardly. The linking arm is connected to the bearing housing or frame 2% (and to each of the successive bearing housings as shown in Figure l).

The main frame 11 is fixed by secure mounting to the floor F. The lifting arms L, L are permitted limited movement, although the top of the lifting arms L, L is connected to the top of the frame '11 (not shown) in the conventional manner. Also connected to the top of the frame in any conventional manner is a cable C which mounts a plurality of stop means S, the cable C and stop means S being shown diagrammatically in Figure 1, but in detail in the remaining views which will be discussed.

4 Referring still to the essentially diagrammatic showing in Figure 1, it will be seen that the stops S, S etc. are mounted on the cable C adjacent each of the bearings 29a, 28a, etc. and linking arms 29d, 28d, interconnect each bearing 29a, 28a, etc. with a separate and independent stop S, S, etc. Fluid actuated means in the form of a pneumatic cylinder 39, 38, etc. interconnect each bearing housing 2% with each linking arm 290! so as to independently urge the bearing 29a upwardly (or downwardly as the case may be). Actually, the device here involved is a device for assisting in relieving the load of the bearing 29a, so in operation it acts to urge the bearing 29a up wardly to relieve from 0 to 100% of the bearing weight, as the case may be. The stop means S cooperates with the linking arm 29d, so that only downward urging of the linking arm 29d against the stop means 5 is operative. The linking arm 29d is thus urged against the stop means downwardly to a greater or lesser extent depending upon the amount of the bearing load to be relieved. If the bearing load is completely relieved, further upward movement of the linking arm 29d unseats it from the stop S. This is the case when the lifting means L are employed to lift the entire calender stack. An advantage of the instant invention is that the stop means stop downward movement only of the linking arm 29d and permit upward movement thereof when the lifting means L are put into operation. This, as will be appreciated by those skilled in the art, simplifies greatly the changes which must e made in a conventional calender stack in order to employ the instant invention.

Referring now to the details of Figures 2 through 6, it will be seen that only the mounting for the bearing 29a is shown, although it will be appreciated that this is the same mounting as that used for the bearings 21a through 29a. As indicated, the bearing housing 2% is connected through a flange joint 4% to a pivot arm 290 connected to the pivot P carried by the frame 11, so that limited vertical (swinging) movement of the bearing 29a is permitted. The lifting means L is also shown for swinging the bearing 2% upwardly in the manner hereinbefore described. A generally U-shaped bracket 41 mounted by bolts (not shown) in a flange joint 42 at the outward extremity of the bearing housing 2% carries a linking arm 29d on a pivot pin 43. At the upper end of the bracket 41 another pivot pin 44 carries a pneumatic cylinder 45 and the piston 45:: of the pneumatic cylinder 45 is connected through a pivot pin 46 to' an intermediate portion of the linking arm 29d. Movement of the piston 45a effects relative swinging movement of the linking arm 29d and relative movement between a cap 47 carried by the linking arm 29d and stop means S secured to the fixed cable C. As is shown in Figure 4, the cap 47 is carried at the outer extremity of the linking arm 29d and secured thereto by welds (not shown).

As will be appreciated, the invention provides a linking assembly (45, 29d) mounted at four pivot points including the cap 47 in direct pivotal contact with the stop S (which, of course, function as the stop pivot point) and the three pins 43, 44 and 46 all of which are moved vertically or upwardly relative to the stop pivot point (47, S) by expansion of the pneumatic cylinder asscmbly (45, 45a). For convenience, the linking arm 29d may be referred to as a primary linking arm and the piston 45a (and cylinder 45, in assembly) may be re ferred to as a secondary arm.

The cap 47 is a shell of generally hemispherical shape having a slot 47a therein through which the cable C may be slipped. The top circular aperture 47b of the cap 47 is slightly larger in diameter than the cable C so as to permit relative vertical movement therebetween, but a pin 48 held in position by nuts 49, 49 in recesses 47c, 47c prevents the cable C from slipping back out through the slot 47a during ordinary operation. The linking arm 29d, with the cap 47, is thus permitted limited vertical movement, while the cable. C remains fixed in position.

As shown in Figure 3, the stop is in the form of two hemispheres 50a, 50b, with central grooves 50c, 50a, respectively, which clampingly engage the cable C. The clamping force is applied through bolt and nut assemblies 51a, 51b mounted in suitable recesses. The spherical stop S has a top contour of substantially the same shape as the inner contour of the cap 47, so that the relatively secure assembly of Figure 5 is obtained when the pneumatic cylinder 45 urges the linking arm 29d downwardly; but when the lifting means L, for example, raise the bearings 29a, etc. upwardly, the cap 47 separates easily from the stop S (as shown in Figure 6).

It will be understood that modifications and variations may be effected without departing from the spirit and scope of the novel concepts of the present invention.

It will thus be seen that, processwise, the instant invention consists in a method of calendering a paper web that comprises resting a plurality of superimposed calender rolls 21, 22, 23, etc. on one another to load calender nips defined therebetween, rotatably mounting each roll 21, 22, etc. in bearings 21a, 22a, etc. at opposite ends thereof, passing a traveling paper web through each of said nips intermediate the roll ends, and resiliently urging each bearing 21a, 22a, etc. upwardly to relieve loading at each nip laterally beyond the paper web passing therethrough. The resilient lifting of the bearings is of particular importance, because the high spots in the paper or other possible imperfections may pass through the calender nips without the creation of such high local loads as to cause injury to the equipment. The resilient mounting means is capable of absorbing a temporary high load, if such is necessary. Also, the instant resilient means are capable of more accurate adjustment than any mechanical positioning device for mounting the bearings.

I claim as my invention:

1. A multi-nip calender comprising a substantially vertical calender frame, a stack of calender rolls adjacent the frame including a bottom roll and a plurality of superimposed rolls, separate and independent bearings rotatably carrying the ends of each of said superimposed rolls, separate and independent bearing arms pivotally mounted at one end on said frame and extending swingably outwardly therefrom to carry in an intermediate portion of each bearing arm one of said bearings of one of said superimposed rolls, vertical means adjacent the outwardly extending end of each of said bearing arms providing a stop adjacent each of said bearing arms on the side of the bearings opposite the frame, and fluid actuated means connected to each of said bearing arms for independently urging each bearing associated therewith upwardly with respect to said stop.

2. A calender as claimed in claim 1 wherein there is a linking arm pivotally connected to the outwardly extending end of each bearing arm, each said linking arm including one of said fluid actuated means within its structure for expansion of the fluid actuated means to effect lifting of the bearing associated therewith.

3. A calender as defined in claim 1 wherein there is a linking arm pivotally connected to the outwardly extending end of each bearing arm and each of said linking arms is pivotally connected at one end to the bearing arm associated therewith and at the other end to the adjacent stop, and wherein said fluid actuated means is so connected to each of said linking arms as to move said one end thereof in a vertical direction relative to said outer end thereof.

4. A calender as defined in claim 3 wherein each of said linking arms is limited in downward movement by direct pivotal contact with the stop associated therewith but is separably connected to said stop to permit upward movement of said arm.

5. A multi-nip calender comprising a substantially vertical calender frame, a stack of calender rolls adjacent the frame including a bottom roll and a plurality of superimposed rolls, separate and independent bearings rotatably carrying the ends of each of said superimposed rolls, separate and independent bearing arms pivotally mounted at one end on said frame and extending swingably outwardly therefrom to carry in an intermediate portion of each bearing arm one of said bearings of one of said superimposed rolls, vertical means adjacent the outwardly extending end of each of said bearing arms providing a stop adjacent each of said bearings on the side of the bearings opposite the frame, a substantially horizontal primary linking arm pivotally mounted on the outwardly extending end of each said bearing arm and pivotally connected to the stop adjacent thereto, a secondary linking arm for each of said primary arms pivotally connected to an intermediate portion of the primary arm and to the outwardly extending end of the bearing arm mounting the primary arm, and fluid actuated means connected to each of said secondary arms for independently urging upwardly each bearing carried by the bearing arm to which such secondary arm is pivotally connected.

6. A calender as claimed in claim 5 wherein each said secondary linking arm includes one of said fluid actuated means within its structure for expansion of the fluid actuated means to effect lifting of the bearing associated therewith.

7. A multi-nip calender comprising a substantially vertical calender frame, a stack of calender rolls adjacent the frame including a bottom roll and a plurality of superimposed rolls, separate and independent bearings rotatably carrying the ends of each of said superimposed rolls, separate and independent bearing arms pivotally mounted on said frame and extending swingably outwardly there from to carry in an intermediate portion of each bearing arm one of said bearings of one of said superimposed rolls, vertically suspended means adjacent the outwardly extending end of each of said bearing arms providing a stop associated with each of said bearing arms, a substantially horizontal primary linking arm pivotally mounted on the outwardly extending end of each said bearing arm and pivotally connected to the stop adjacent thereto, said stop limiting downward movement only of said primary arm and permitting upward movement thereof, a secondary linking arm for each of said primary arms pivotally connected to an intermediate portion of the primary arm and to the outwardly extending end of the bearing arm mounting the primary arm, and fluid actuated means connected to each of said secondary arms for independently urging upwardly each bearing carried by the bearing arm to which such secondary arm is pivotally connected.

References Cited in the file of this patent UNITED STATES PATENTS 2,058,352 Putnam et al Oct. 20, 1936 2,138,397 Channity Nov. 29, 1938 2,300,994 Thiele et al. Nov. 3, 1942 2,850,952 Hornbostel Sept. 9, 1958 FOREIGN PATENTS 440,634 Great Britain Jan. 2, 1936 843,687 Germany July 10, 1952

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