US2897538A - Means for bending the rolls of rolling machines - Google Patents

Description

Aug. 4, 1959 u. G. SHAPIRO ETAL 2,397,538

MEANS FOR'BENDING THE ROLLS 0F ROLLING MACHINES Filed Nov. 12, 1957 4 Sheets-Sheet 1 F d. L8

1959 u. G. SHAPIRO ETAL 2,897,538

MEANS FOR BENDINC THE ROLLS OF ROLLING MACHINES Filed NOV. 12, 1957 4 Sheets-Sheet 2 4, 1959 u. G. SHAPIRO ETAL' 2,

MEANS FOR BENDING THE ROLLS OF ROLLING MACHINES Filed Nov. 12, 1957 V 4 Sheets-Sheet s u. G. SHAPIRO ET AL 2,897,538

Aug. 4, 1959 MEANS FOR BENDINC- THE ROLLS OF ROLLING MACHINES Filed Nov. 12, 1957 v 4 Sheets-Sheet 4 DEANS FOR BENDlNG THE ROLLS OF ROLLING MAC *l l' Uriel G. Shapiro and Thomas S. Rochester, both of Wallsend-on-Tyne, England, assignors to Commercial Plastics Limited, Wallsend-on-Tyne, England, a British company Application November 12, B57, Serial No. 695,808

Claims priority, application Great Britain November 15, 1956 5 Claims. (Cl. 18-2) This invention relates to means for bending the rolls of rolling machines or mills employed for the rolling of material which is fed between two or more rolls, said bending being for the purpose of compensating for or correcting the deflection of one or more of the rolls, which may take place during the rolling operation, in order thereby to obtain a uniform thickness of the rolled film or sheet of material.

While the invention is particularly suitable for use with rolls employed for the calendering of plastic films or sheets, it is also applicable to rolls used in the rolling of metals and other materials, or in the rolling or grinding of chocolate, pigments and the like, where the material to be rolled is fed in the form of a viscous paste or the like between pairs of rolls.

It is well-known that during the rolling or calendering of plastic material, for example, forces develop which cause the rolls to bend, these forces depending on the size of the bank of excess feed material formed adjacent the gap between the rolls, as well as on the speed of rolling, and on the viscosity of the material at the working temperature. Such bending during rolling would, unless compensated for, cause the rolled film or sheet to be of non-uniform thickness, being thicker at the middle of the rolls.

One known method of compensating for roll bending during rolling has been to employ crowned rolls, the initial degree of crowning being such that during the Working operation the crowning adjacent the roll gap is eliminated, giving a uniform size of rolling gap and consequently uniform thickness of the rolled material. This compensating method involves very accurate machining of the rolls, and a given degree of crowning will only be suitable for a given set of operating conditions, and in order to conform to another set of conditions where the bending forces are different, the rolls have to be changed for rolls of different crowning, or different machines have to be used.

To obviate these disadvantages of compensating for bending merely by crowning the rolls, one or both cooperating rolls have been extended outwards of their main bearings and hydraulic pressure has been applied to auxiliary floating hearings on their ends, in a vertical direction, in order to bend the rolls to any desired degree of initial camber or to restore the rolls to parallel relation after bending due to operational pressures. The application of bending pressure to the ends of the rolls, however, involves utilising the main bearings as fulcra, thereby imposing increased loading and strain on those bearings, tending to shorten their effective life. Also, if the bending force is applied upwardly to a lower roll mounted in floating main bearings, the roll will be pushed up as soon as this force slightly exceeds the downwards forces acting on the roll, and there is consequently a danger of fouling with an upper roll. Moreover, before this condition is reached the upward force will tend to reduce the stability, within the bearings, of the journals Patented Aug. 4, 1959 of the roll to which the said force is applied, with the possibility of variations in the thickness of the sheet resulting. On the other hand, if the bending force is applied vertically downwards, the usual jacks which sup port and vertically adjust the main bearings of at least the lower roll, must overcome much greater forces when closing the gap between the rolls, so that larger motors and reduction gears are needed to operate the jacks.

The object of the present invention is to provide an improved method of and means for applying a compensating bending to a rolling-machine roll, either initially or after deflection during the rolling operation, whereby the disadvantages attending bending by vertical pressures applied to the ends of a roll, as explained above, are avoided, the invention enabling bending to be elfected without imposing any additional load on the main bearings or on the adjusting jacks, or causing instability of the roll journals.

According to the invention, in a rolling machine means are provided for applying to each end of one of the rolls a turning couple acting in a plane containing the axis of said roll and the axis of a co-operating adjacent roll so as to tend to bend said first roll about its middle and thereby compensate for or correct for deflection caused during the rolling operation, said turning means being independent of the main bearings of the roll.

The turning means may comprise auxiliary free or floating bearings independent of the main bearings and encircling opposite end portions of a roll, and means for imparting to said auxiliary bearings an angular turning eifort or couple acting in a plane which contains the axis of the roll and the axis of the adjacent co-operating roll so as to apply to each end portion of said first roll a turning couple or torque acting in said plane and tending to bend the roll about its middle. Conveniently, the auxiliary bearings each carries a lever member or arm rigid therewith, and means are provided for moving the two lever members or arms towards or away from one another in a common plane to bend the roll. The means for angularly moving the lever members or arms may consist of hydraulic means, such as a hydraulic cylinder carried by each lever member or arm and provided with piston means co-operating with stationary abutment surfaces. The two cylinders of the respective lever arms are arranged to be interconnected to ensure balanced hydraulic forces and therefore the elimination of unbalanced axial forces on the roll bearings.

In the accompanying drawings,

Figure 1 is a diagrammatic front view of a rolling machine fitted with roll bending means in accordance with the present invention.

Figure 2 is a diagrammatic side view of the machine shown in Figure 1.

Figure 3 is a more detail part sectional view of one end of a roll and associated bending means in accordance with the invention.

Figure 4 is an end elevation of the roll end of Figure 3.

Figure 5 is a horizontal section on line V--V, Figure 4.

Figure 6 is a schematic diagram showing the general layout of a hydraulic system suitable for operating the roll bending means.

Referring now to the drawings, the rolling machine illustrated therein may be used for calendering or rolling plastic material into sheets or films, and comprises a desired number of co-operating horizontal rolls, indicated by the reference numerals 1, 2, 3 and 4, which may be either slightly crowned or parallel-sided, between successive pairs of which hot plastic is fed and rolled out, the gaps between such successive pairs being progressively reduced and the final pair of rolls 3, 4, having a gap suitable for giving to the finished rolled sheet or film the thickness required. As shown in Figures 1 and 2,

the upper pair of rolls 1, 2, are placed side by side whilst the rest are disposed vertically one above the other giving aninverted L-formation, but, if desired, the rolls may be all vertically stacked or otherwise disposed, as in a Z-formation for example.

Each roll, such as 4, has journal extensions 5, 6, at opposite ends and the journals are supported in main bearings 7 which are adjustably mounted in the sides of a stationary frame 8 so that the gaps between successive pairs of rolls can be adjusted as may be desired to give the desired thickness gauge to the material which is being rolled between them. In the case of the rolls 2, 3, and 4, which are in vertical alignment, the main bearings 7 are freely mounted for vertical displacement in the sides of the frame 8 under the control of a pressure screw 9 or equivalent means acting downwards on the top roll 2 and a screw or jack 10 supporting the lower roll 4, with compression springs 11, 12, between intermediate rolls and their adjacent rolls.

During the rolling of the plastic materials between some or all of the several pairs of adjacent rolls, at least one roll will have its axis slightly deflected or bowed, resulting in the thickness of the sheet or film being thicker at the middle than at the ends unless means are provided for compensating for or correcting such deflection, as is contemplated by the present invention.

Thus, in accordance with the invention, the apparatus includes new and improved means whereby one or more of the rolls (in the case illustrated, the lower roll 4) may be adjustably bent by externally-applied forces, independently of the bending by the material during rollto both pistons and to ensure balanced hydraulic forces and the elimination of unbalanced axial forces on the main roll bearings 7.

By moving the bearing-carried arms either towards one another or away from one another the initiallycambered roll 4 may thus be given either a more positive camber, causing its middle portion to approach the cooperating roll 3 and its axis to bend upwards fromits normal straight condition; or a negative camber, causing its middle portion to recede from the co-operating roll 3, and its axis to bend downwards of its normal straight condition. Such deflections of the roll axis are indicated in exaggerated form by the broken lines in Figure 1. A negative camber would be given, relatively to the original degree of crowning of its surface if, for example, the initial cambering is such that for rolling a given thickness of sheet, no bending would be required, and it is then required to roll a sheet of greater thickness. If a thinner sheet is required, a positive camber would be given by the bending operation, it being understood that thinner gauges of material give a greater bending pressure.

ing, in order to compensate for such bending by the material. Thus, mounted on each projecting end of the journal extensions 5 and 6 of the lower roll 4 is a free or floating auxiliary bearing 13, conveniently of a tworow tapered roller type, which is surrounded by an outer housing 14 having attached to it, or integral with, a radial arm 15 which depends vertically. The lower end of this arm 15 is arranged to have a force applied to it, in a plane containing the axis of the roll 4, tending to turn it angularly in one direction or the other in the said plane containing the axis of the roll. Such force is applied simultaneously to the two arms 15 at opposite ends of the roll 4 but in opposite directions, so that the arms 15 are moved either away from one another or towards one another. The result of so moving the arms 15 angularly in a plane containing the axis of the roll 4 is that a couple or turning torque acting in said plane is applied to the end journals 5 and 6 of the roll 2 through the auxiliary bearings 13 so that the roll becomes bent in arcuate form about its middle point without imposing any additional load upon the main bearings 7.

The forces on the lever arms 15 tending to turn them angularly, in one direction or the other, may be applied by means of a horizontal hydraulic cylinder 16 attached to or incorporated in the lower end of each arm 15 and containing a double-acting stationary piston 17 to one side or the other of which hydraulic pressure can be applied. The piston 17 carries two central stems or rods 18 and 19 extending through the ends of the cylinder 16, the extremities of said stems 18, 19, engaging two spaced-apart vertical abutment surfaces 20, 21, between which the lower end of the arm 15 is free to move or float up and down as the arm is deflected or as the roll 4 is adjusted vertically to vary the rolling gap. When hydraulic pressure is applied, to one side or to the other of the stationary piston 1'7, the reaction of the stem 18 or 19 on one or other of the abutment surfaces 20 and 21 will cause the cylinder 16, and thus the arm 15, to move relatively in one angular direction or the other. Preferably the hydraulic supply lines to the cylinders 16 of the two lever arms 15 are interconnected both as regards the inner ends on one side of the pistons 17 as well as the outer ends on the other side of the pistons 17, to enable hydraulic power to be applied simultaneously Referring now to Figures 3 to S of the drawings which illustrate one constructional arrangement in greater detail, the main bearing 7 which supports the one journal extension 5 of the roll 4 is shown as comprising a plain bush 23 which is so dimensioned as to have a small radial clearance 24 so as to permit of a small degree of angular movement of the roll 4 during the bending operation. Other types of bearing, however, such as self-aligning bearings, for example, may be employed if desired. 7 V

Mounted on the journal extension 5 outwardly of the said main bearing 7 is the floating auxiliary bearing 13 which is of a two-row tapered roller type comprising pairs of conical inner and outer race rings, 25 and 26 respectively, separated by spacing members 27 and 27 and two rows of tapered rollers, 28 and 29, running between the respective conical race surfaces of the inner and outer race rings 25, 26, with their larger ends directed outwardly.

The inner race rings 25 of the auxiliary bearing 13 are mounted upon a sleeve 30 which is fixed upon the journal extension 5, being located against an abutment shoulder 31 at the inner end and being held in place at the outer end by a driving pinion or spacing sleeve 32 which is secured by an end plate 33 bolted to the end of the shaft.

The outer race rings 26 of the auxiliary bearing 13 are contained within the outer housing 14 which carries a lower web of flange 34- bolted to the arm 15 so that the latter depends vertically therefrom. The arm 15 carries at its lower end an extension member 35 which is formed with a semi-circular recess 36 extending transversely across one face, within which recess is interlockingly housed the horizontal hydraulic cylinder 16 which is retained in place by an outer semi-circular clamping covered plate 37 secured by bolts 38. The ends of the cylinder 16 are closed by end caps 39 provided With central apertures 40 through which pass the stems or rods 18 and 19 of the doubleacting piston 17 which is contained within the cylinder 16 as herein before described, and parts (not shown) are provided in the cylinder walls on either side of the said piston 17 for the entry and exit of a hydraulic fluid.

The outer extremities of the piston stems 18 and 19 which engage the two spaced apart abutment surfaces 20, 21, are preferably formed with rounded end surfaces 41, 42, as shown, and the overall length between the two extreme end surfaces 41 and 42 is only slightly less than the distance between the abutment surfaces 20, 21, so that the piston 17 remains virtually stationary as far as movement in an axial direction is concerned.

The two abutment surfaces 20 and 21 are formed by small plates 43 and 44 which are secured to parallel It will be understood that when the two arms 15 are simultaneously moved towards or away from one another the couple tending to bend the roll into arcuate form is applied to the journal extensions 5 and 6 by virtue of the upper rollers of the auxiliary bearing 13 being caused to exert a downward force on the journal at one point thereon, whilst the lower rollers of the bearing 13 are caused to exert an upward force on the journal at a point which is longitudinally displaced from the point of application of the first-named force.

To prevent angular movement of each arm 15 in a direction transverse to the axis of the roll 4, the extension member 35 at the lower end of the said arm is provided with laterally projecting side arms 49, d9, which slidingly engage within guide slots 50, 59, formed in plates 51, 51, secured to the walls 45 and 46 of the bracket member 47.

The source of power for operating the hydraulic cylinders 16 and effecting the bending of the roll 4 is conveniently a compressed air operated hydraulic pump 52 which is shown in Figure 6 as being connected to the cylinders through a changeover 4-way valve 53 enabling the pressure to be applied either to the inner ends or to the outer ends of the cylinders, the opposite ends in each case being connected to exhaust. The hydraulic fluid is contained in a reservoir 54 and the reference numeral 55 denotes an accumulator bottle for stabilizing the pressure and preventing sudden fluctuations. Various pressure gauges are shown in the circuit being denoted generally by the reference letter G.

In a modification, instead of each lever arm 15 carrying a hydraulic cylinder fitted with a stationary piston, a single stationary cylinder may be provided midway between the two arms 15 and fitted with two spaced movable pistons respectively coupled to the arms, fluid pressure being admitted either to the outer ends of the pistons or to the space between the pistons according to whether the arms are to be moved towards or away from one another.

It is to be understood that the bending may be applied to the roll or rolls either initially, before the material is operated upon, or after rolling of the material has commenced, when the roll has been deflected by the material, in which case the bending is applied to bend the roll to a condition in which the gap is of uniform size throughout the length of the rolls during the rolling operation.

The bending may be applied to any one or more of the rolls as may be desired, and the rolls may initially have parallel sides, instead of being crowned.

We claim:

1. A rolling machine comprising a frame; at least two cooperating rolls each mounted in bearings in opposite sides of the frame one of said rolls being extended at each end beyond the frame; auxiliary free bearing units inde pendent of the frame bearings and encircling the extended ends of said roll; a lever arm rigid with each auxiliary bearing unit; and means for acting on the two lever arms to move them angularly relatively to one another in a plane which contains the axes of said roll and of an adjacent roll, so as to bend the said roll about its middle.

2. A rolling machine comprising a frame; at least two cooperating rolls each mounted in bearings in opposite sides of the frame, one of said rolls being extended at each end beyond the frame; auxiliary free bearing units independent of the frame bearings and encircling the extended ends of said roll; a lever arm rigid with each auxiliary bearing unit; a hydraulic cylinder carried by each lever arm; a piston within the cylinder; stationary abutment means co-operating with each piston to prevent axial movement thereof; and means for supplying fluid pressure to said cylinders to cause the lever arms to move angularly relatively to one another in a plane which contains the axes of said roll and of an adjacent roll so as to bend said roll about its middle.

3. A rolling machine according to claim 2, wherein each piston carries axial stems at opposite sides, said stems extending through the ends of the cylinder, and the abutment means for each piston are provided with vertical abutment surfaces engaged by the ends of the piston stems, said abutment surfaces permitting the piston to move vertically between them for the adjustment of the rolls of the machine.

4. A rolling machine comprising a frame; at least two cooperating rolls each mounted in bearings in the frame, one of said rolls being extended beyond the frame; an auxiliary free bearing unit encircling each extended end of said roll, said bearing unit having two laterally-spaced rows of rolling elements enclosed within a housing; a lever arm rigidly carried by each said bearing housing; and means for acting on the two lever arms to move them angularly relatively to one another in a plane which contains the axes of said roll and of an adjacent roll, in order to bend said roll about its middle.

5. A rolling machine comprising a frame; at least two co-operating rolls mounted in bearings in the frame; two auxiliary free bearing units, independent of the frame bearings, encircling the respective ends of one of the rolls; a lever aim rigid with each auxiliary bearing unit; means for acting on the two lever arms to move them angularly relatively to one another in a plane which con tains the axes of said roll and of an adjacent roll, so as to bend the said roll about its middle; and means for preventing said lever arms from turning angularly about the axis of the roll.

References Cited in the file of this patent UNITED STATES PATENTS 2,611,150 Goulding Sept. 23, 1952 FOREIGN PATENTS 747,347 Great Britain Apr. 4, 1956

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