US3094769A

US3094769A - Table roll

Info

Publication number: US3094769A
Application number: US116576A
Authority: US
Inventors: John D Robertson
Original assignee: Mount Hope Machinery Ltd
Current assignee: Mount Hope Machinery Ltd; Mount Hope Machinery Co
Priority date: 1961-06-12
Filing date: 1961-06-12
Publication date: 1963-06-25
Anticipated expiration: 1980-06-25
Also published as: DE1775853B1

Description

June 25, 1963 J. D. ROBERTSON TABLE ROLL Filed June 12, 1961 FIG. I

FIG. 2

FIG.3

INVENTOR. JOHN D. ROBERTSON fi y, 04%

ATTORNEYS 3,094,769 TABLE ROLL John D. Robertson, Taunton, Mass, assignor to Mount Hope Machinery Company, Taunton, Mass, a corporation of Massachusetts Filed June 12, 1961, Ser. No. 116,576 7 Claims. ((31. 29116) This invention relates to rolls for supporting traveling webs, and more particularly concerns a new and improved table roll which maintains an axially straight configuration in use, although the roll may be of relatively great length and small diameter.

The roll of this invention is particularly adapted for use in paper-making machines, although it has utility in many other applications. In the manufacture of sheet paper, the present practice involves depositing a thin suspension of fibre in water on a fine mesh screen, commonly referred to as a wire, which is moving in a horizontal path at high speed and supported by a number of table rolls arranged transversely below the web. The water in the suspension is allowed to drain through the wire to leave a layer of pulp on the wire surface. The pulpy layer is subsequently pressed and dried into sheet paper and wound onto a roll.

During the initial stages in the formation of the paper sheet, it is important that the wire be maintained in as flat a condition as possible. Should the wire sag along its center, the watery suspension would tend to drain towards the center-line with the result that the finished paper sheet would be thicker at its center than at its edges. In order for the wire to present a fiat surface, it follows that the supporting table rolls must be axially straight throughout their entire length.

Heretofore, some of these rolls, which run up to 20 feet or more in length, have been made slightly barrel-shaped to compensate for the sag so that, when mounted horizontally, the upper screen-supporting portion will be longitudinally straight. This type of table roll is quite expensive to produce and has not given entirely satisfactory performance. Other table rolls have been made quite strong and with a relatively large diameter ('16 inches for example) in order to support, without sagging, the weight or the Wire and the partly formed paper. While this measure is effective in providing a generally straight roll, the resulting increase in roll diameter adversely affects the draining of water through the wire. It has been found that when table rolls of relatively large diameter are used to support the wire, a fillet of water tends to build up beneath the wire along the upper quadrant on the discharge side of the roll. This fillet of water creates a rather high vacuum (up to 26 inches) which pulls the wire down and slightly around the roll. From time to time, the fillet will burst, breaking the vacuum so that the wire snaps up. When this occurs, the wet pulp will fly ofi the wire, spot ting the adjacent area and generally disrupting the sheetforming process. However, a table roll of relatively small outside diameter eliminates this problem and has the further advantage of permitting a greater number of rolls to be used in supporting the wire without creating an objectionable vacuum. But, for reasons already stated, any such small-diameter roll must be axially straight when in operation.

Accordingly, it is an object of the present invention to provide a table roll which, in its normal use, will be axially straight although of relatively great length and small diameter.

Another object of this invention is to provide an improved axially-straight table roll which is of simple, lowcost construction, yet completely dependable in operation.

More particularly, the roll of this invention comprises United States Patent 3,094,769 Patented June 25, 1963 a stationary axle and an outer sleeve rotatably mounted thereon. During the course of its manufacture, the axle is bowed with a longitudinal curvature lying in a single plane of a predetermined camber. The term camber refers to the maximum lateral offset of the longitudinal centerline of the axle from the rectilinear axis joining the centerline at the ends of the axle. Following assembly of the sleeve on the axle, the curved roll is stationarily mounted in an upwardly convex position, with the plane of curvature of the axis extending vertically through the rectilinear axis. The camber of the axle is of a pre-selected value sufilcient to compensate for its own weight and that of a load which the roll is intended to carry, so that the elastic deflection produced by these loads Will cause the axle and the roll to assume the desired axiallystraight condition. In the more general case, in which the roll is subjected to a resultant force vector acting trans- Vcrsely thereon, but not necessarily vertically, the axle is oriented so that the resultant lies in the plane of curvature, and acts oppositely to the direction of camber of the axle.

These and other features of the invention, along with further objects and advantages thereof, will be more readily apparent from the following detailed description of a preferred embodiment thereof, taken in connection with the accompanying drawings, in which:

FIG. 1 is a view in side elevation of an unmounted table roll made according to this invention;

FIG. 2 is a similar view, showing the roll mounted in operating position and under a normal load; and

FIG. 3 is a fragmentary sectional view in side elevation, showing certain details of construction of the roll.

Referring to :FIG. 1, there is illustrated an unmounted and unloaded table roll 10 having a longitudinally curved tubular axle 12 having a camber C.

The degree of curvature for a particular roll axle may be varied according to the conditions under which it is designed to operate, but the camber should be equal to the elastic deflection which will be produced at the iongitudinal center of the axle by the weight of the complete roll and that of the intended load. This value may be readily calculated in a well-known manner for particular forms and dimensions of axles, and load weights.

Referring to FIG. 3, a slightly resilient, hard corrosionresistant surface sleeve 14 is disposed lengthwise about the axle and supported for rotation thereon by a number of 'spool assemblies 16 arranged in axially-spaced relation. Each spool assembly comprises a ball bearing unit 18, an annular spacing element 20 for axially spacing the bearing units, and an annular roll sleeve 22 mounted upon the outer race of each ball bearing to support the surface sleeve 14. Locking rings 24 having set screws 25 are mounted at oppote ends of the axle to maintain the several parts in assembled relation.

Since the roll will normally be in use where a great deal of water is present, it is desirable that the ends of the sleeve 14 be closed by annular plates 26, and that the ends of the tubular axle be sealed by abutrnents 28. In conjunction with the plates 26, any well-known form of rotatable fluid seal may also be used if desired.

As shown in FIGS. 2 and 3, the roll is mounted in a horizontal plane by means of brackets 32 receiving opposite ends of the axle 12 to mount them upon suitable fixed supports 34. To prevent the axle from turning about its longitudinal axis, keys 35 are received in keyways 36 formed in the brackets 32, and in a keyway 37 which may be formed longitudinally the full length of the axle as shown, or limited to the end portions of the axle. One or more set screws 38 are threaded into at least one of the brackets 32 to axially secure the axle therein. It will be apparent that other locking arrangecording to several fiactors. sleeve, their-configurations, diameters and moduli of elasments may be provided to hold the axle in the desired position.

The roll is mounted in an upwardly convex position, with the plane of curvature of the axle cxtendin g vertically through the rectilineanaxis determined by the ends of the roll. "In FIGS. 2 and .3, :the roll is shown deflected to an axially straight configuration under the gravitational forces of "the rolls own weight and the predetermined weight of a fine mesh screen .or wire 39 carrying. a layer of pulp 40 over the top of the roll .in normal operation. All of the major forces :acting to deflect the roll are directed vertically downward and, accordingly, the vertical orientation of the .plane of curvature of the .axle results in an elastic deflection balancing the load in an axiallystraight condition of the roll. Obviously, the roll axle maybe set at any angular degree to compensate for known ad1vectors which are not vertical. For example, in a conveyor system, the first and last rolls will be subjected to the vertical force of gravity plus the horizontal component of the tension of the conveyor belt. Under such circumstances, the roll axle would be set so that the convex side of the .roll will be oriented in the plane of the vectorial resultant of the two force components.

The degree of set longitudinal curvature or camber that should be introduced into the roll axle will vary ac- The length of the axle and ticity, as well as the weight of the roll and the intended opera-ting load, must be considered in order to establish the proper degree of curvature, in accordance with wellknown theories of the deflection of simply-supported beams.

While the :roll axle has been illustrated-and described as tubular in shape, which is generally preferable by reason of its relatively high strength and rigidity for a given weight, it will be understood that a solid axle .could be used if'desired.

A table roll made according to the invention has several advantages not present in table rolls heretofore available. This construction permits the fabrication of elongated, relatively small-diameter t-able-rolls'which will not sagin use, but will be axiallyistraight under the operating loads for which they are designed. For reasons already presented, rolls of relatively small diameter are highly desirable in the manufacture of paper. sincethey contribute 'to'an improved-product.

While the invention has been described with particular reference to a preferred embodiment for purposes of illustration, it will be understood that various modifications may be made without departing from the true scope of the invention.

Having thus described my invention, what I claim and esire :to secure by.Letters Patent of the United States is: .1. A roll comprising an'elongated axle and an annular sleeve, .means rotatably mounting and supporting said sleeve against transverse sagging with respect to said axle,

thetaxlebeing a stiifi-beam permanently set in a bow with a predetermined longitudinal curvaturelying in a plane,

.means stat-ionarily supporting said axle horizontally for subjection toapredetermined resultant force acting transversely thereon, said axle being oriented with said resultant lying in said plane of curvature and acting against the convex side of the how, the degree of bow being preselected forelastic-deflection of said roll to a longitudinally straight configuration by said resultant.

2.. A roll comprising an elongated axle and an annular sleeve, means rotatably mounting and supporting said sleeve against transverse. sagging with respect to said axle, the axle being a still beam permanently set in a bow with a predetermined longitudinal curvature lying in a plane, means stationarily supporting said axle horizontally for subjection to a predetermined weight, said axle being oriented with said plane extending vertically and said bow upwardly convex, the degree of said how being preselected for elastic deflection of said roll to a longitudinally straight configuration by said weight.

3. A roll comprising an axle being a stiff beam longitudinally curved in a plane with a permanent set, and a sleeve, means rotatably mounting and supporting said sleeve against transverse sagging with respect to said axle, the camber of the curvature of said axle having a value preselected to compensate for a predetermined force vector acting transversely against said roll, said axle being supported substantially at its ends and oriented so that said force vector lies in said plane and acts oppositely to the direction of said camber, such that said force vector deflects said roll to .a longitudinally straight condition.

directed upwardly, such that said weight deflects said roll to alongitudinally straight condition.

.5. A .roll comprising an elongated axle, a plurality of :bearings mounted on'said'ax-le in axially-spaced relation,

an annular sleeve rotatably mounted on said bearings, means supporting said sleeve against transverse sagging with respect to said axle intermediate said bearings, said axle being a still beam and :having a set longitudinal curv-ature lying in a plane, saidaxle being supported substantially at its ends for subjection to a predetermined force vector transverse thereto, said axle furtherbeing oriented so that said force vector lies in said plane of curvature oppositely to the direction of curvature, the camber of said curvature being of a preselected value such that said roll is elastically deflected by said force vector to a longitudinally straight configuration.

6. A table roll comprising an elongated axle being a still beam longitudinally curved in a plane, an annular sleeve surrounding said axle, aplurality of bearings axially spaced on-said axle and rotatably supporting said sleeve thereon, means supporting said sleeve against transverse sagging with respect to said axle intermediate said bearings, thecaniber of the curvatureof said axle being 'of a preselected value to compensate for a predetermined rcsultant'of -forces acting transversely against said roll,

said axle being supported substantially at its ends and so oriented that said resultant lies in said-plane of curvature and is oppositely directed to the camber of said axle,

such'that said resultant elastically deflects said roll into a longitudinally straight configuration.

7. -A roll comp-rising an elongated axle, a pluralityof spool assemblies-each including at least one bearing and a spool-rotatably supported by said bearing, said spool assemblies being mountedon said axle in axially-spaced relation, an annular sleeve rotatablymounted on the spools of said spool assemblies, said spools supporting said sleeve against transverse sagging with respect to said axle-intermediate said bearings, said axle beinga stitf beamand having a setilongitudinal curvature lying in a plane, said axle-being supported substantially at its ends=for subjection to a. predetermined force vector transverse thereto, said axle further being oriented so that said force vector 'lies in said plane of curvature oppositely to the direction of curvature, the camber of said curvature being of-a preselected value such that said roll is elastically deflected by 2,952,889 Hanssen Sept. 20, 1960

Claims

1. A ROLL COMPRISING AN ELONGATED AXLE AND AN ANNULAR SLEEVE, MEANS ROTATABLY MOUNTING AND SUPPORTING SAID SLEEVE AGAINST TRANSVERSE SAGGING WITH RESPECT TO SAID AXLE, THE AXLE BEING A STIFF BEAM PERMANENTLY SET IN A BOW WITH A PREDETERMINED LONGITUDINAL CURVATURE LYING IN A PLANE, MEANS STATIONARILY SUPPORTING SAID AXLE HORIZONTALLY FOR SUBJECTION TO A PREDETERMINED RESULTANT FORCE ACTING TRANSVERSELY THEREON, SAID AXLE BEING ORIENTED WITH SAID RESULTANT LYING IN SAID PLANE OF CURVATURE AND ACTING AGAINST THE CONVEX SIDE OF THE BOW, THE DEGREE OF BOW BEING PRESELECTED FOR ELASTIC DEFLECTION OF SAID ROLL TO A LONGITUDINALLY STRAIGHT CONFIGURATION BY SAID RESULTANT.