US3498878A - Magnetic curl breaker - Google Patents

Description

March 3,1970 D. N. QBENsHAlN 3,498,873

' MAGNETIC cum. BREAKER Filed May 29,1968 4 sheets-sheet-x March 3, 1970 D. Nr.7oBENsHAlN yMAGNETIC CURL `BREAKER 4 Sheets-Sheet 2.

Filed llay 29, 1968 w m /l n@ M 2 w, @l mi qw 4\ G W. y.

ma lay 29. .1968-, 4 sheets-snm s y INVENT OR David Nae/ Obensha/'n 1.. la7C-Alam..

ATTORNEY March 3, 1970 D. N. OBENSHAIN MAGNETIc cum. BREAKER mea may 29, 1968 4 Sheets-Sheet 4 INVENTOR David iNoel Obenshain ATTORNEY Liu-10.

United States Patent O 3,498,878 MAGNETIC CURL BREAKER David Noel Obenshain, Luke, Md., assignor to Westvaco Corporation, a corporation of Delaware Filed May 29, 1968, Ser. No. 733,001 Int. Cl. D21h 1/00 U.S. Cl. 162-271 13 Claims ABSTRACT OF THE DISCLOSURE An apparatus is presented for decurling a we'b of paper or the like which includes a rotatable rod cradled throughout its length on anti-friction bearings and held in position -by a plurality of spaced apart magnetic devices.

BRIEF SUMMARY OF INVENTION When paper is manufactured, the finished paper is generally wound on cores for shipment to the customer, or for processing into sheets, or other converted paper products. The cores are relatively small, ranging from around two inches to eight inches in outside diameter. A very popular size is a three inch core which has an outside diameter of three and one-half inches.

Due to the fact that the paper is wrapped onto the core under tension throughout its length, and to the relatively long time that the rolls are stored, the paper tends to partially conform to the curvature established by the core. When unwound, the paper is thus found to have acquired a permanent curvature or, as referred to in the industry, the paper contains cur In the outer portions of the rolls the curl may be very minor, if it can be detected at all. However, as the paper is unwound down to the core, the curl becomes more and more pronounced. In many instances, the curl is so great that the paper cannot be used for its intended purpose. Sometimes, as much as to 15 percent of the paper in a roll has to be discarded due to so called roll curl. Even before the point is reached on a roll of paper where the paper has to -be discarded, the curl present may require slowing down of a sheeting machine to avoid jamups in the sheet transporting and stacking mechanisms.

Curl breakers or decurlers of various types have been used to reduce the losses of paper as a result of excess roll curl. Conventional decurlers made from a sharp-edged bar are suitable in some instances with the most elfective being a 'bar with a small radius edge around which the paper web is caused to travel. The side of the paper web opposite from the curl -bears against the edge to induce a reverse curl, thereby counteracting the roll curl. By properly adjusting the angle of bend around such bars, the roll curl can be quite easily removed and, in some instances, the paper can |be made to curl in the opposite direction if desired. Such bars, however, are not suitable for use on highly finished or coated paper, since the edge of the bar tends to scratch the coated surface of the paper. The same decurling problem would be encountered with coated paperboard which suffers from the same mechanical curl problems when stored in roll form.

In addition, decurlers having a round cross-section in the form of cylindrical rolls have been proposed to eliminate the scratching problem, but these devices did not prove satisfactory for other reasons. Namely, because the rolls were made too large in diameter, the decurling operation could not be effectively performed. Smaller diameter rolls were then tried, but because of their tendency to deiiect when supported only at the ends, they too did not eifectively decurl the web. It as found that to properly decurl a web of easily scratched paper, the rolls had tol be in the order of one-half inch diameter or smaller rice and a web width in the order of 12 to 18 inches was the maximum that could lbe run. Attempts were then made to cradle decurling rolls, or rods, of a greater width at intermediate points throughout their lengths bymeans of ball Ibearings or other low friction elements. At nominal web speeds of 1000 feet per minute, a one-half inch diameter rod would have to rotate at 7,650 rpm. It was found that at speeds well below the above rate, the small diameter rod would tend to whip and ride-up out of the supports.

To solve this latter problem the present invention was conceived. It was found that a small diameter rod rotating at high speed could be retained in the cradle formed by low friction support means by arranging beneath the rod and close to, but not touching same, a plurality of permarient magnets or the like located between spaced support means. With the present arrangement, web speeds up to 2000 feet per minute have been attained with-no tendency for the rotating rod to whip and ride-up out of its supports. The ultimate speed limit is not yet known.

It is accordingly an object of the present invention to provide a rotatable rod decurling means which effectively acts to decurl a tensioned web and overcomes the above mentioned difiiculties and shortcomings of conventional decurlers.

It is another object of the present invention to provide a small diameter rotatable decurling rod having means for preventing the intermediate deilection thereof.

Still another object of the present invention is to provide a fully supported small diameter rotatable decurling rod capable of high speed operation with means to prevent it from whipping and riding up IOut of its supports.

More particularly, the present invention provides a small diameter, rotatable decurling rod, of any desired length with intermediate low-friction support means spaced throughout its length, and with novel magnetic means, close to 'but not touching the decurling rod, to retain it in its supports at high rotational speeds.

DESCRIPTION OF THE DRAWING FIGURE l shows a front elevation of a curl breaker assembly, broken at its center;

FIGURE 2 shows a frontal detail of one unit of the curl breaker assembly;

FIGURE 3 shows a sectional view taken at lines 3-3 of FIGURE 2;

FIGURE 4 shows a sectional view taken at lines 4-4 of FIGURE 2;

FIGURE 5 shows a plan view of a curl breaker assembly partially in section;

FIGURE 6 shows a cross sectional view of a dual curl breaker installation and its supporting means;

FIGURE 7 shows a frontal detail of a modied curl breaker unit;

FIGURE 8 shows a sectional View taken at lines 8 8 of FIGURE 7;

FIGURE 9 shows a sectionalview taken at lines 9-9 of FIGURE 7;

FIGURE 10 shows a curl -breaker rod with a plastic covering;

FIGURE 11 shows an end view of the plastic covered rod of FIGURE 10;

FIGURE 12 shows another modiiied curl breaker rod formed from a helical spring;

FIGURE 13 shows schematically how the curl breaker rod installation of the invention could be used as a bowed roll; and,

FIGURE 14 is a sectional view taken at lines 14-14 of FIGURE 13 to show one form of mounting for the bowed roll.

3 DETAILED DESCRIPTION sheeting, inspecting, sorting and stacking paper finishing machine, the magnetic decurler of the present invention has shown a substantial decrease in the paper loss due to roll curl. The apparatus was installed on the machine as an eXtra attachment and without altering the previous design of the machine. The only requirements for a suitable installation being one which allows the web to be tensioned when passed over the decurler bar, and one which allows Some degree of movement to vary the angle of wrap around the decurler bar. Experiments illustrated that with a relatively small diameter rod (one-half inch in diameter) the amount of curl removed or induced increased steadily up to about 60 degrees wrap around the rod. Beyond that point there was only slight increase in curl removal. Also, it was found that a given angle of wrap removed or induced more curl as the basis weight of the web increased.

Referring to the drawing, and particularly to FIGURE 1, the apparatus of the present invention is illustrated as being mounted on a rigid support means 10. The support means 10 may be in turn mounted on movable arms whereby the angle of wrap of the web around the rod can be changed, or it may be xed in place in a location which permits the web angle of wrap to be changed by movable guide means before and/or after the Web passes over the rod. Additionally, the rigid support means 10 must be located such that the web is tensioned when it passes over the rod, and preferably in a place that permits easy access and operator convenience. FIGURE 6 of the drawing shows one example of how the curl breaker of the present invention might be located as a part of a paper finishing apparatus. There is a dual installation 4depicted n FIGURE 6 wherein two rigid support bars 10 are shown installed on arm assembly 2 which is in turn pivotally mounted on shaft 7 supported by machine frame member 4. A similar arm assembly and frame at the opposite side of the machine would support the opposite ends of bars 10. This arrangement is used to control both up and down curl sometimes found in a single paper roll. As illustrated, the curl breaker assemblies are mounted between a pair of rolls 5, 6 on the machine in a place where the web W is under tension. The position of one of the curl breaker assemblies 2 in contact with the paper web W is shown in broken lines. A single installation could be similarly arranged as a part of a paper finishing apparatus.

Referring again to FIGURE l, there is illustrated a side view of a typical curl breaker assembly. The structural support for the assembly comprises the rigid bar member 10 of'rectangular cross section as shown in FIG- URES 3 and 4. The bar member 10 does not necessairly have to be rectangular in cross section, as long as it is rigid enough to prevent excessive deflection. The top of the bar has machined therein a groove or slot 16 to insure accurate alignment of the bearing support blocks 12 and the magnets 26. Thebearing support blocks 12 are attached tothe bar by means of screws 14, FIGURE 4. The magnets are likewise attached by means of screws 28, FIGURE 3.

FIGURE 2 is an enlarged view of the right end of the assembly of FIGURE 1, showing the curl breaker rod 30, end thrust bearing 32, end block 33, bearing support blocks 12, bearing shafts 20, bearing spacers 18 and 19, `bearings 2.2, 24 and magnet 26. The curl breaker rod 30 is preferably made of case hardened and ground tool steel having a Rockwell C hardness of around 60. It may be chrome plated if desired. Other materials may be used as long as they are magnetically attractive. Each end of the rod is machined and has lightly pressed thereon a thrust bearing 32. End block 33 is rigidly attached to the rigid support bar 10 by screws 35, see FIGURE 5. Each end block 33 has recessed in the face thereof an opening 34 to receive the bearing 32 with approximately 1/16 inch clearance in all directions. This clearance allows the rod to position itself freely on supporting bearings 22, 24 and to have end float to provide for thermal expansion of the rod. Recessing the bearing into the end block 33 is a safety precaution to prevent accidental loss of the rod in case some abnormal condition momentarily knocks thel rod out of the cradle formed by the bearings 22, 24. Bearing blocks 33 are of course mounted at each end of the rod 30 as shown in FIGURE 1.

Referring now to FIGURE 5, the bearing support blocks 12 each have openings machined therein for receiving lbearing shafts 20. A bearing and spacer sleeves 18 and 19 are mounted on each shaft 20. The sleeves are of different lengths and are arranged as shown so that the two bearings 22, 24 supported by a pair of mounting blocks are in staggered or offset relation with each other with an overlapping relationship as they form a cradle for supporting the rod. That is, for each pair of bearings 22, 24, their respective axes of rotation are spaced apart a distance less than the diameter of one ball bearing. By arranging the bearings in this manner, the rod 30 is positioned more or less on top of the bearing surfaces which allows a greater angle of wrap of the web to be achieved than would be allowed if the rod 30 were cradled in a deeper V-shaped space formed by opposed ball bearings. It should also be pointed out that the bearings 22, 24 could 'be mounted on opposite sides of a single bearing lblock 12, the important feature being the offset mounting arrangement. By mounting the bearings in offset or staggered relationship with ,respect to one another, so that each ball bearing of a pair rotates in a different plane, the wear on the rod is not concentrated in one spot as would be true if the bearings were directly opposite one another. The bearings 22, 24 and 32 are preferably standard radial ball bearings having built-in shields or seals to retain their lubricant and to keep out dirt and dust. Identical bearings may be used in each instance.

The magnets 26 are of the permanent type and are shimmed for approximately '1A-2 inch clearance with the rod 30. Magnets may be installed between each pair of supporting bearings, or between every other pair of supporting bearings as shown, FIGURE 1. Other forms of magnetic devices including electro-magnets could be employed if desired to accomplish the same purpose.

For decurling light weight papers having a 50 lb. or less basis weight, the rod 30 would be on the order of 5%; inch diameter for achieving the best results. For papers 50 to 120 lb. basis weights, 1/2 inch diameter rods are satisfactory. For papers and paperboards over lb. basis weight, 5/8 and 34 inch rods have been used successfully. The spacing between the pairs of supporting bearings is not critical. For and 1/2 inch rods, four inch spacings have been found adequate. For inch rod, eight inch spacings have proven satisfactory.

The curl breaker assemblies can be made in any desired length by using a multiplicity of support bearings and magnets, together with a rigid supporting -bar 10 stiff enough to avoid excessive deflection.

It is contemplated that the apparatus of this invention may be used singly, in tandem, or in pairs one reversed from the other (FIGURE 6) in order to carry out the desired purpose. Generally the apparatus will be positioned on the machine so that the web can be properly tensioned when it passes over the decurling rod. The angle of wrap necessary to induce a given amount of curl can be calculated knowing the basis weight of the web and the size of the decurling rod.

A second embodiment of the novel magnetic curl breaker is illustrated in FIGURES 7-9. During the coursevof the development of the novel arrangement described hereinbefore, at least one prototype rotating rod curl breaker was tried which consisted of a hardened and ground rod in air lubricated bearings. Standard Oilite bronze bearings with the lubricant removed were used with the top three-fifths of the bearing being ground away leaving a cup shape for the bar to rotate in. An air channel was provided under the bearings and they were clamped in place. The apparatus was then operated by applying compressed air through the air channel and bearings to support the rod. End caps were then necessary to retain the rod within the cup shaped bearings when the rod was not in contact with the paper web. i

The apparatus illustrated in FIGURE 7 then became an outgrowth of the preliminary approach described above. In this instance, air lubricated bronze bearings 40 have been substituted for the ball bearings used in FIGURES 1-5. The use of these air lubricated bearings 40 in combination with the magnets 26 provides an operative structure which is the functional equivalent of the previously disclosed apparatus of FIGURES 1-5. The rigid support structure remains the same except that it is drilled with an opening 42 to provide the air supply conduit for lubricating the bearings 40. Each lubricated bearing unit comprises a base member 45 tted in a slot 46 machined in support means 10, and fixed by bolts or the like 47 to the rigid support structure. The base member 45 has air conduits 48 drilled therein which are adapted to be aligned with cooperating air conduits 50 located in the support structure 10. The air conduits 50 are perpendicular to the main supply conduit 42 .also located in support structure 10. With this arrangement, compressed air can be supplied through conduit 42 and distributed evenly to the porous bearing 40 via connecting conduits 48, 50. The apparatus is thus seen to provide an air film at the bearing surface 40 on which the rod 30 may ride.

Referring now to FIGURE 9, means for retaining the bearing 40 in its bearing seat is illustrated. In order to accomplish this requirement a pair of retaining plates 52 are secured to the base member 45 by screw means 54. As can be noted from the drawing, the retaining plates 52 are each machined so as to t smoothly with the side edges of the base member 45 and to cooperate but not interfere with the rotation of the rod 30. Retaining plates 52 do not hold the rod 30 in the bearing seat since the magnetic means 26 located on each end of the bearing unit (FIGURE 7) performs the hold down requirement. This embodiment has been found to work satisfactorily and would prove useful where a supply of compressed air was readily available.

Trials performed with the magnetic curl breaker, using ball bearings as a low friction bearing means, have shown conclusively that mechanical curl can be satisfactorily removed from just about any grade of paper. Of course, for light basis weight paper, the smaller the diameter the decurler rod should be. In addition, for coated papers, it may be deemed desirable to use a covered rod to further reduce any tendency to produce scratches on the paper surface. For that purpose, a plastic coated decurling rod 60 is illustrated in FIGURE 10. Any suitable smooth plastic 62 may be used without interfering with the holding power of the magnets nor causing an excess amount of friction. FIGURE 11 shows an end view of the plastic covered rod of FIGURE 10 to illustrate the close tit that the plastic 62 assumes around the rod 60.

Another form that the decurling rod may take is illustratcd in FIGURE l2. For this embodiment, a helical spring 64 is shown. In the case where the spring 64 is used, it has been found desirable although not necessary to use a plastic coating over the spring to prevent scratching of the paper. As a matter of fact, when the magnetic curl breaker assembly of this invention is utilized as a bowed or spreader roll, the helical spring covered rod 64 may be used to achieve the proper amount of curvature. However, a solid small diameter rod could be used just as well. As explained hereinbefore, the bowed roll is generally used to minimize cross machine direction shrinkage in the manufacture of paper on the paper machine. The magnetic curl breaker of the present invention when used like a bowed roll as described above, would be employed to reduce the tendency for the paper to wrinkle in an otf machine operation. A further advantage of the bowed roll magnetic curl breaker would be the desirable decurling of the paper web in the machine direction due to roll curl.

A schematic showing of how the magnetic curl breaker of the present invention might be used as a bowed roll is illustrated in FIGURES 13 and 14. In this embodiment the curl breaker rod could be solid if the bow is very slight, or the spring type rod 64 as shown in FIGURE 12 where greater bow is required. The rod is supported by ball bearing assemblies 22, 24 mounted on brackets 12 similar to the arrangement shown in more detail in FIG- URES 1 5. Located between the ball bearing assemblies are the usual hold down magnets 26. These magnets and the brackets 12 are fxedly attached to the support means 10 in any suitable manner. For the bowed roll installation, the mounting bracket is shown as being supported by adjustable support elements 68 from the base 70. The adjustable support is necessary to provide the degree of bow at its center to accomplish the desired results. FIGURE 14 shows in detail a schematic representation of how the adjustable support 68 could operate. The support consists of a threaded rod 67 screwed into the support element 10. The opposite end of the rod 67 is universally mounted in the base 70 with a ball element 66. Hence, when the adjustable support 68 is turned, the support element 10 including the decurler rod 64 moves up or down as desired. Of course, any other suitable means could be used to mount the bowed roll as long as it was adjustable. Where a predetermined fixed bow is satisfactory, a suitably curved support 10` may be employed.

The foregoing description is deemed to be illustrative of the invention.

I claim:

1. A decurler apparatus for conditioning a tensioned web of paper or the like comprising;

(a) a rigid support means adapted to extend across the width of the web;

(b) a thrust bearing located at each end of the rigid support means;

(c) a freely rotatable rod of magnetically attractable material mounted between said thrust bearings;

(d) a plurality of low friction bearing elements secured to said support means at spaced locations to cradle said rod throughout its length; and,

(e) a plurality of magneticdevices secured to said support means at spaced locations betweenthe low friction lbearing elements in close proximityy to said rod whereby said rod is retained in place on'the low friction bearing elements by magnetic attraction.

2. The apparatus of claim 1 wherein said low friction bearing elements of paragraph (d) further comprise;

(1) pairs of ball bearings mounted on support blocks so that the ball bearings of each pair rotate in planes which are off-set from one another.

3. The apparatus of claim 2 wherein the ball bearings of each pair are further mounted on the support blocks with;

(2) their respective axes of rotation spaced aparta distance Which is less than the diameter of one ball bearing so that the ball bearings overlap one another and form a shallow V-shaped cradle for said rod.

4. The apparatus of claim 3 wherein the magnetic devices -of paragraph (e) comprise;

(1) permanent magnets which vare xedly secured in a groove located in said rigid support means.

5. The apparatus of claim 1 wherein said low friction bearing elements of paragraph (d) further comprise;

(1) air lubricated bearings mounted on a 4bearing block and shaped to provide a cradle for said rod.

6. The apparatus of claim wherein said air lubricated bearings each;

(2) extend longitudinally of said rod to support the rod throughout its length and include air conduits which are aligned with cooperating conduits in said rigid support means whereby lubricating air may be supplied to said bearing surface adjacent said rod.

7. The apparatus of claim 6 wherein said air lubricated bearings each further include;

(3) retaining plates attached to said bearing block to keep the bearing surface in its seat.

8. The apparatus of claim 1 lwherein the rod of paragraph (c) has a plastic cover.

9. The apparatus of claim 1 wherein the rod of paragraph (c) is formed from a helically wound spring.

10. The apparatus of claim 1 wherein said rigid supporting means of paragraph (a) is further;

(1) adjustably mounted on a base member with a plurality of adjustable elements which extend between the rigid supporting means and the base member.

11. The apparatus of claim wherein said adjustable elements each comprise;

(2) a universal portion in the base member and a threaded portion extending into a cooperating threaded opening in the rigid support means whereby 10 support means;

(c) a. freely rotatabl rod of magnetically attractable material mounted between the thrust bearings of each rigid support means;

(d) a plurality of low friction bearing elements secured to each rigid support means at spaced locations to cradle said rod throughout its length; and,

(e) av plurality of magnetic devices secured to each rigid support means at spaced locations between the low friction Vbearing elements in close proximity to said rod whereby said rod is retained in place on the low, friction bearing elements by magnetic attraction.

13. The apparatus recited in claim 12, wherein the rigid support means of paragraph (a) are each;

(1) mounted on arrn assemblies which are in turn pivotally attached to a machine frame member.

References Cited UNITED STATES PATENTS 3/ 1904 Ostrandel' 162-271 12/1959 Zernov 162-271 X ALLEN N. KNOWLES, Primary Examiner

Images