US3035331A - Method for contracting resilient rolls to fit sleeves thereon and product - Google Patents

Description

May 22, 1962 R. L.. WIEMAN 3,035,331

METHOD FOR CONTRACTING RESILIENT ROLLS TO FIT sLEEvEs THEREON AND PRODUCT Filed Jan. 9, 1961 WM5/ym@ P055?? A MEM/Wy Patented May 22, i952 3,035,331 METHUD FOR CONTRACTING RESilLllEN'i RLLS T@ MT SLEEVES THEREGN AND PRDUQT Robert L. Wiernan, St. Paul, Minn., assigner to Minnesota Mining and Manufacturing Company, St. Pani,

Minn., a corporation of Delaware Filed Jian. 9, 1961, Ser. No. 81,632 6 Ciaims. (Ci. 29-1l7) This invention relates generally to new and useful sleeve or casing covered resilient bodied cylinder or roll constructions such 'as those used as printing rollers in darnpcning and/ or inking mechanisms of printing presses and the like, although the roller constructions of this invention are not limited to use in this environment. The roller construction of this invention is unique among resilient bodied roller constructions in its retention thereon of a relatively nonstretehable sleeve solely by frictional engagement therewith, while yet permitting such sleeve to be mechanically mounted thereon and demounted therefrom in a simple, fast, convenient, and relatively friction free manner. This application is a continuation-impart of my copending application Serial No. 694,549, filed November 5, :1957, now abandoned.

Rubbery resilient bodied rollers lare prevalent in the printing industry. These resilient bodied printing rollers have achieved wide use in inking mechanisms and dampening mechanisms of lithographie presses and in the inking mechanisms of letter presses and the like because of their superior performance over other types of roller constructions.

Until recently, removable coverings for these rollers had to either be stretched on the roller body and sewed in place or wet wrapped on the roller body and shrunk in place, inefficient techniques that restrict the removable surfacing materials that can be used on the roller bodies and which place the burden of the successful use of the covering on the skill with which it is applied. Because of these limitations, removable surfacings for these rollers have been usually limited to molleton and other clothlike coverings for use in the dampening mechanisms of lithographie presses, these coverings being unsatisfactory for other uses. No removable surfaeings are available for these resilient bodied rollers when they are used in inking mechanisms of lithographie and other printing presses, although there is little doubt that such removable surfacings would be a boon to the printing industry. For example, different surface hardness measurements and non-slip characteristics are demanded of the roller bodies for different inking operations while different chemical resistanees of the resilient roller lbodies are required for different printing inks. At present, ink must be applied directly to the roller body surface and the ink must be tailored to the press rollers rather than the rollers to the ink. In spite of these obvious shortcomings, however, resilient bodied printing roller constructions remained unchanged prior to this invention.

Recently my colleague, Albert E. Raymond, as is more fully described in his copending application Serial No. 670,511, led July S, 1957, developed a nonstretchable, preformed, stiff, dampening roll sleeve which performs on a resilient bodied rol-ler independently of the skill or lack of skill of its application to the roller and which is free from many of the problems affecting cloth coverings and parchment wrappings. Yet, the practical utilization of this sleeve as a removable roller surfacing on `a presently available resilient bodied roller entails a lowering of the temperature of the resilient body of the roller from normal room temperatures to a point considerably below freezing. The contraction of the resilient body which results enables mounting of the preformed sleeve thereon and upon return of the body to normal room temperatures it tightly frictionally retains the sleeve in place. ingenious as this procedure is, it is nevertheless timeconsuming and not conducive to rapid sleeve mounting or demounting.

lt is a particular object of this invention to provide a resilient cylindrical body which readily and quickly circumferentially contracts throughout its length by simple vacuum apparatus and enables the rapid mounting and tight, uniform, frictional retention thereon of stiff, preformed, nonstretehable sleeves or coverings having diameters intermediate the actual and the contracted diameters of the roller body. It is a further object to provide a unique cylindrical resilient body and covering combination wherein the resilient body after insertion into its covering or casing is firmly held in a eircumferentially compressed state by the casing whereby the natural tendency of the body to recover `from compression comprises the fastening means retaining the covering and resilient body frictionally secured to one another.

The foregoing and other objects which will become apparent hereinafter as the description proceeds are achieved by the new and useful resilient bodied roller constructions of this invention.

The product of this invention may be described as a roll combination that comprises a substantially solid elongated resilient rubbery cylindrical body on which is mounted a nonstretchable, and preferably stiff, tubular covering or sleeve. The elongated resilient cylindrical body has at least one centrally disposed interior passage extending substantially throughout the length thereof whereby the body is capable of radial contraction to a reduced diameter smaller than its natural diameter by lowering the pressure in said passage below that of the surrounding atmosphere and is recoverable from such compressed condition to its natural diameter upon equalization of the pressures of the passage and the surrounding atmosphere. The sleeve, or covering, on the contracted cylindrical body has an internal diameter smaller than the natural diameter of the cylindrical body and Earger than the reduced diameter of the cylindrical body so that the tubular covering maintains the resilient body in a state of contraction and is tightly, frictionally retained on the resilient body solely by the resilient eX- pansive pressure exerted thereagainst by the contracted resilient body.

Although the invention will be particularly described with reference to its use in the printing industry in the laccompanying drawings it is to be understood that such description is to facilitate understanding of the utilization of the invention in a particular field and that the invention is not limited thereto. l,

FIGURE 1 is a schematic side elevational view of a rotary offset lithographie press having roller trains forming the inking and dampening mechanisms and illustrating an environment in which the printing rollers of this invention are useful;

FIGURE 2 is an exploded isometric view of a roller having a resilient rubbery cylindrical body constructed in accordance with this invention showing how the mechanical means for contracting the body are applied to the ends of the roller;

FGURE 3 is a cross-sectional view through the roller body of PlGURE 2 taken substantially along the plane of section line 33 of FIGURE 2;

FiGURE 4 is a side elevational view of the roller body in its contracted condition with a preshaped, nonstretchable sleeve being mounted thereon, certain parts of the assembly being broken away `for clarity of detail in illustrating the manner of contracting the roller and applying the sleeve thereto, the normal diameter of the roller in its natural state being shown in dotted outline;

FIGURE 5 is an end view of the roller of FIGURE 4 with the sleeve frictionally mounted thereon;

FIGURE 6 is an end View of a modified roller construction;

FIGURE 7 is an end view of the roller construction of FIGURE 6 having a nonstretchable sleeve tightly frictionally retained thereon;

FIGURE 8 is an end view of another modified roller construction; and

FIGURE 9 is an end View of the roller of FIGURE 8 having a nonstretchable sleeve tightly frictionally retained thereon.

With reference to the accompanying drawings it is to be understood that the schematically illustrated rotary offset press of FIGURE l, designated in its entirety by the numeral 10, is illustrative only of one general type of printing press in which the rollers of this invention have particular utility.

Printing is carried out on these presses by depositing a dampening or ink repellent solution onto the non-image areas of the printing plate of the plate cylinder by means of the dampening rollers of the dampening mechanism l2 of the press I0. Ink is supplied to the image areas of the plate cylinder by the inking mechanism through the train of inking rollers 14, The plate cylinder applies the image to the surface of the blanket cylinder which then prints on the Web of paper to be printed passing over the impression cylinder. The roller trains 12 and I4 are exemplary of ink supplying and ink repellent supplying systems in which the resilient bodied rollers of this invention find utility as printing rollers.

Referring now to FIGURE 2, there is shown in this figure a preferred roller construction 16. This roller 16 comprises basically a cylindrical metal or other rigid supporting core 18 to which is vulcanized or otherwise adhered a cylindrical resilient rubbery body 20 and is constructed primarily, although not exclusively, for use as a printing roller. Usually, such rollers vary in length from about 8 inches to about 84 inches and in diameter from about 2 inches to about 8 inches. The resilient roller bodies are generally from about 1A to l inch thick or more. While the roller sizes on different types of printing presses may vary considerably, the length of the roller is always considerably more than the roller diameter, the length to diameter ratio of the rollers being as high as, and sometimes higher than, about 14 to l.

In the roller construction shown in FIGURES 2 through 5, a plurality of axially extending and axially parallel passages 22 equidistantly circumferentially spaced from one another extend completely through the resilient body 2t) of the roller 16 land open into the opposite ends of this body. These passages are provided radially inwardly from the outer cylindrical surface of the resilient body and do not significantly change the normal surface hardness of the resilient body as is indicated by the durorneter measured on -a Shore Durometer A2 scale.

The rigid roller core is provided with projecting end spindles 24 to facilitate mounting the roller on the supporting structure of an apparatus, such as that carrying the inking or dampening mechanisms of the printing press of FIGURE 1.

To contract the resilient rubbery body 20, a vacuum is drawn in the passages 22 to permit the application thereover of a sleeve having a smaller inside diameter than the normal roller diameter as shown in FIGURE 4. Upon drawing a vacuum in the passages 22, the resilient material of the body 20 liows, or distorts, into the passages 22, the reduction in the total volume of the passages from the normal volume thereof equaling the circumferential reduction in volume of the resilient body from its normal circumference.

A simple and effective means for drawing the vacuum in `the passages 22 is illustrated in FIGURES 2 and 4. This means comprises a small vacuum cup 26 having an axial opening 28 in the bottom wall thereof to permit Slipping the same over one of the spindles 24 of the roller 16, and a washer 36 for slipping over the other spindle 24 of the roller 16. The cup 26 ts against the end of the resilient rubber body 2d in such a manner that all of the passages 22. opening into that end of the roller open directly into the interior of the cup. A nipple 30 opening into the bottom wall of the cup has attached thereto a vacuum line 32 which may be connected to a suitable vacuum source such as a pump or an aspirator for a faucet or the like (not shown). The other end of the roller body is closed off by means of the washer 36, preferably of rubber or similar material, which may be simply slipped over the spindle 24 to cover the mouths of the passages 22 opening into that end of the resilient body. Upon drawing a vacuum through the line 32, the pressure in the passages 22, being reduced below that of the surrounding atmosphere, causes the pressure of the surrounding atmosphere to contract the body.

Another means (not illustrated) to contract the resilient body is to simply interconnect the passages with a circular groove at each end of the resilient body 20, then permanently (or temporarily) cover each end with a thin, soft patch of rubber or the like. Then, to draw a vacuum, a hollow needle can be connected to the vacuum line (in place of cup 26) and the patch simply punctured by the needle in the area thereof overlying the passage interconnecting groove to reduce the pressure in the passages.

To raise the pressure of the passages to that of the surrounding atmosphere, the vacuum line may be simply disconnected from the needle and the pressure within the passages permitted to equalize with that of the surrounding atmosphere.

After the sleeve is slipped in place in the manner shown in FIGURE 4, with the ends of the sleeve terminating approximately on a plane with the ends of the resilient body, vacuum line 32 may be disconnected from the vacuum source and air permitted to re-enter the vacuum cup 26 and the passages 22 to equalize the pressure therein with that of the surrounding atmosphere. When this occurs, the autogenous pressure exerted by the resilient body 20 in attempting to expand to its normal atmospheric circumference, tightly, frictionally retains the sleeve in its mounted position thereon.

Conveniently, and to enable the best retention of the nonstretchable sleeve 38 in place on the roller, the inside diameter of the sleeve should be only slightly greater than the contracted diameter of the resilient body as shown in FIGURE 4 and the nonstretchability of the sleeve should be such that the sleeve does not stretch under the autogenous pressures exerted by the roller body thereagainst upon subsequent equalization of the pressure Within the body passages with that of the normal atmosphere surrounding the body.

The material forming the resilient body may be any rubber or rubber-like substance, for example, those ordinarily used in the formation of presently made resilient bodied printing rollers such as natural or synthetic rubbers, rubbery compositions of glue and glycerin, synthetic resins, vulcanized plant oils, and various other rubbery polymers. The material should have rapid land relatively complete recovery from deformation and be of a relatively incompressible nature as, for example, natural rubber. However, the resilient material may have incorporated therein, as a filler, compressible material such `as cork or the like or even solid, incompressible fillers, without detrimental effect so long as the compressible material does not unduly interfere with the recovery of the rubbery body from deformation.

The formation of the passages in the roller is subject to wide variation. These passages need not be axially parallel or identical in size to one another. The ends of the passages may terminate short of the ends of the resilient body in which case communication with the passages can be by means of an access passage through the end of the roller core or spindle opening at its inner end into a connecting passage communicating the axially extending passages wit-h one another. The passages need not be equidistantly circumferentially distributed about the axis of the roller, and any distribution about this axis which enables a reasonably uniform circumferential body contractionthroughout the length of the body is contemplated. It is desirable, however, that the major portion of the volume of the longitudinal passages be situated closer to the roller core than to the outer surface of the resilient body, as is shown in all the illustrated embodiments, so that the bulk of the flow of resilient material into the passages during circumferential contraction of the body will be radially inward toward the roller axis.

Resilient rubbery bodies having `a durometer range of between about l and about 60, and preferably in the range of about 20-40, are useful in most printing press operations. However, harder and softer resilient bodies may be useful in special printing or other environments and the desired durometer rubbery material can be selected in accordance with the particular conditions of use of the roller. If the resilient body is too hard, it will not contract sufliciently to be useful; however, if the body is too soft, although easily contracted, its frictional engagement with a sleeve or casing mounted thereon will be insufflcient for most industrial applications.

The following specific examples illustrate the formation and use yof the roller described in FIGURES 2 through 5 as a printing roller.

Example 1 A pair of rollers was constructed for a 17 x 22 inch (the size of a sheet that can be printed) Harris rotary offset lithographie press. Each 4roller was made as follows. On a metal shaft l inch in diameter were wrapped layers of vulcanizable natural rubber to provide a cylindrical resilient rubbery body having a length of 23% inches. The rubbery body thickness was Iabout W16 inch, measuring radially outward from the core, resulting in a roller having an outer diameter of about 2% inches.

ln the application of the vulcanizable rubber, a first roller layer about 1/16 of an inch thick was wrapped around the shaft. Next, eight 1A; inch outer diameter metal rods coated with polytetrailuoroethylene polymer (to prevent the rubber from sticking to the rods) were laid on and pressed into this first layer `and held in spaced circumferentially equidistant relation thereon yand in axially parallel relation to one another about 1/32 of an inch radially outward from the shaft surface. Thereafter, the remaining layer of rubber to build up the %6 inch radial thickness of the roller body was wrapped over the first layer, embedding the rods.

Each rubber roller body was next wound with wet nylon tape which was thereafter dried to compress the body layers and provide continuous interfacial contact of these layers with one another and with the rods. Then, the rubber body was vulcanized at 290 F. in an autoclave at 4() pounds per square inch pressure for about 11/2 hours, removed from the autoclave, and cooled. After cooling, the roller body surface was ground to the desired 21/8 inch diameter and the rods removed to provide longitudinal passages extending throughout the length of the roller body. i

Each resilient body surface had a hardness reading of about 271/2 on the Shore Durometer A2 scale at any point on the cylindrical surface thereof.

The resulting resilient rubbery body of each roller was then contracted to a diameter of about .O30 inch less than its normal room temperature diameter by evacuating air from the body passages, utilizing the apparatus shown in FIGURES 2 and 4 of the drawings connected to a vacuum pump. While each roller was retained in its contracted state. A dampening roll sleeve having an inside diameter about .G20 inch less than the normal diameter of the resilient roller body, and made in accordance with the procedure of Example 2 of the companion application of my colleague, Albert E. Raymond, previously referred to herein, was slipped on over this surface. Thereafter the vacuum was released and the autogenous pressure exerted by the resilient roller body upon such release tightly, frictionally retained the sleeve on the roller body.

These rollers, with removable sleeves of the type and size indicated above mounted thereon, have been and are being successfully used as the form rollers (those contacting the plate cylinder) in the dampening mechanism of a 17 x 22 inch Harris rotary odset press. The sleeves do not slip on the rollers as the rollers are rotated on the press, nor do the sleeves tend to travel olf the ends of the rollers even at high press speeds.

Example 2 Somewhat larger roller constructions were made for a Miehle 29 rotary offset press following the procedures of Example l. The shaft diameter of each of these rollers was 1% inches and the finished roller diameter was about 21/2 inches. Here again the distance of the passages from the shaft surface was about 1/32 of an inch. However, in view of the increased size of lthe roller, ten axially parallel, circumferentially equidistant passages were formed through the length of the resilient body, rather than eight, as in the 21A; inch diameter roll construction. The rubber hardness reading on each of these vulcanized rubber roller bodies was about 3()` on the Shore Durometer A2 scale.

A dampening roll sleeve of the type referred to in the previous example about .020 inch smaller than the normal diameter of the roll body was easily and quickly applied to the roll body upon circumferential contraction of the roll body with the vacuum apparatus of FIGURES 2 and 4 to a diameter .U25 inch smaller than the normal room temperature diameter of the roll body. After return of the pressure in the passage to that of the surrounding atmosphere the sleeve was found to be extremely tightly, frictionally retained on the roller body.

With both the resilient rubbery bodied roller constructions of these specific examples, the roller bodies could be contracted and the sleeves applied thereto or removed therefrom with a vacuum of about l1 inches of mercury, or even less. Thus, since even a common faucet aspirator, which may be used in place of the vacuum pump, ordinarily draws a vacuum of about 2O inches of mercury, the amount of the vacuum is of secondary consideration with these roller constructions.

In FIGURES 6 through 9 there are shown some alternative constructions of contractible rollers constructed in accordance with this invention. Referring to FlG- URES 6 and 7, the roller is designated in its entirety by the numeral 4t) and comprises a resilient, rubbery, cylindrical body 42 permanently mounted on an axially extending cylindrical metal, or similar rigid supporting core 44. This core is provided with projecting end spindles 46 for rotatably mounting the roller on a suitable supporting framework. The inner cylindrical wall surface of the resilient body/"42 is provided with grooves or troughs 48 which extend the length of the body. The grooves 43 are circumferentially equidistantly spaced and extend in an axially parallel direction throughout the length of the body, opening into the opposite ends of the body. Throughout their length, each groove is closed by abutment of the inside wall surface of the resilient body with the surface of the metal core 44 to provide a longitudinal passage.

This roller is contracted by the same procedures outlined hereinbefore, and when a nonstretchable sleeve 3S having a diameter slightly larger than the contracted diameter of the roller is applied thereover While the roller is in its contracted condition, the sleeve becomes subsequently, tightly, frictionally retained on the roller body .l as shown in FIGURE 7 by the autogenous pressure exerted by the roller body upon equalization of the pressure within the passages with that of the surrounding atmosphere.

FIGURES S and 9 disclose a variation of the modication of FIGURES 6 and 7 in that the roller construction, which is designated in its entirety by the numeral 50, has the supporting core 52 thereof provided with axially extending grooves 54 opening into the periphery thereof throughout the length of the core, which is coextensive with the resilient body 56 while the inside wall of the resilient body remains as a smooth, cylindrical unbroken surface closing the grooves and forming them into passages. When the pressure in these passages is lowered below that of the surrounding atmosphere the material of the resilient body 56 adjacent the passages flows or distorts into these passages and reduces the diameter of the body enabling the application thereon of a nonstretchable sleeve 38 having an inside diameter less than the normal diameter of the roller body. The return of the passage pressure to that of the surrounding atmosphere causes the circumferential expansion of the roller body to autogenously tightly, frictionally retain the sleeve thereon.

These contractible resilient bodied rollers, in addition to possessing all the desirable qualities of conventional resilient bodied printing rollers, have the additional advantage that they can be readily and rapidly contracted in a manner that does not interfere with the application of a covering sleeve thereto. The magnitude of this advantage is best appreciated by the realization that this construction enables the convenient application thereover of nonstretchable removable sleeve surfacings independently of the skill or technique of applying the surfacing. These contractible rollers enhance the application thereto of nonstretchable sleeves having diameters normally smaller than the normal diameters of the rollers by enabling such application without necessitating lowering the temperature of the roller body. By adding this new dimension of ready and quick contractibility to resilient rubbery bodied printing rollers, it is believed this invention will further stimulate the development of preformed nonstretchable removable roller surfacings for both inkand dampening mechanisms of lithographic and other printing presses.

While in the specific embodiments illustrated the resilient cylindrical bodies of the roll constructions have been disclosed as having rigid axial cores with axial tubular passages surrounding such cores, it is to be understood that cylindrical bodies displaying wide variations in constructional details are possible within the scope of this invention depending upon the use to which the roll constructions are to be put, Thus, the resilient body of the roll construction may be coreless and provided with a centrally disposed passage in place of a rigid core (as would result, for example, from the removal of the rigid cores of the resilient roll bodies illustrated in the accompanying drawing).

Such a construction is particularly advantageous, for example, in the field of rocketry where a cylindrical resilient roll body may be utilized as solid rocket propellant, usually called a propellant grain A solid propellant grain may be extruded or cast from a resilient oxidizable binder loaded with a powdered oxidizing agent in a mold by conventional techniques to provide a roll body having appropriately shaped passageways therein (as would result, for example, if the rigid cores of the illustrated rollers were used as forming mandrels coated with a suitable mold release agent for removal after roller formation).

The grain may thereafter be conveniently and easily inserted into a rocket casing by subjecting the passage or passages thereof to reduced pressure below that of the surrounding atmosphere, causing the grain to circumferentially contract substantially throughout its length and enabling ready insertion into a casing having an internal diameter intermediate the natural and contracted diameters of the grain. Thereafter, the pressure of the passages upon again being equalized with that of the surrounding atmosphere causes the grain to expand against the casing, much as the resilient bodied printing rollers of the illustrated roll constructions expand against their covering sleeves, to be tightly, frictionally retained ltherein. By this means, the grain is maintainedy in a compressed condition, and resists any tendency for the formation of cracks or separation from the wall of the casing. Furthermore, the compressed condition of the propellant grain tends to prevent the formation of cracks therein through expansion and contraction brought about by changes in temperature.

The passage, or passages, can be formed of inner-communicating cells throughout the length of the resilient body or by other means. As a practical matter, all of the passages, even though they terminate short of the ends of the resilient body, must be accessible from at least one end of the roller for drawing a vacuum therein and disposed radially inwardly of the cylindrical surface of the resilient body a sucient distance to prevent undue interference with the uniformity of the body surface hardness, which would unduly interfere with the circumferential contraction of the body. Upon recovery from contraction, the resilience of the resilient body of the roll construction must be sufficient to enable tight frictional engagement of the resilient body and the covering therefor of the roll construction, it being understood of course in all instances that the covering must possess a maximum internal diameter somewhere between the contracted diameter of the resilient body and the normal or natural diameter of the resilient body.

In addition to the fields of printing and rocketry noted above, the contractible resilient bodied roll constructions of this invention have significant utility in other industrial and commercial applications such as in the abrasive industry, the paper industry, the textile industry, and in other industries wherein it is desired to make roll constructions of tightly, frictionally intertting resilient bodied rolls and removable or permanent sleeves, casings, or other coverings, or wherein it is desired to ll such sleeves, casing or other coverings with resilient cylindrical bodies.

What is claimed is:

l. The method of mounting a nonstretchable tubular covering on a roller having a substantially solid resilient rubbery cylindrical body with a normal outside diameter larger than the inside diameter of said tubular covering which comprises providing a roller having interior passages into which a portion of the material comprising the resilient body can distort, lowering the pressure within said passages below that of the surrounding atmosphere causing the distortion of a portion of said solid rubbery body into said passages thereby circumferentially contracting said body throughout its length, applying the tubular covering to said body while said body is retained in its circumferentially contracted condition, and thereafter equalizing the pressure of the passages with that of the surrounding atmosphere causing the tubular covering to be tightly, frictionally retained on said body.

2. The method of mounting a nonstretchable tubular covering on an elongated solid resilient rubbery cylindrical body having at least one centrally disposed interior passage therethrough extending substantially throughout the length thereof and which solid body has a normal relaxed outside diameter larger than the inside diameter of said covering, the method comprising lowering the pressure in said interior passage below the pressure of the surrounding atmosphere to distort a sufficient amount of the resilient rubbery material of said body into said passage to circumferentially contract said body and reduce the diameter of said body to a smaller diameter than that of said tubular covering, applying said tubular covering to said resilient body while said body is retained in its circumferentially contracted condition, and thereafter equalizing .the pressure in said passage with that of the surrounding atmosphere causing the tubular covering to constrictively retain said resilient body against expansion to its normal diameter whereby said covering is tightly, irictionally retained on said body.

3. In a roll combination, a substantial-ly solid elongated rubbery cylindrical body capable of radial contraction to less than its natural diameter and recoverable from a contracted condition to its natural diameter and shape, said resilient body having at least one centrally disposed interior passage extending substantially throughout the length thereof and being contracted throughout its length to -a compressed state wherein it possesses `a reduced diameter smaller than said natural diameter, and a nonstretchable tubular covering on said contracted cylindrical body having an internal diameter smaller than the natural diameter of said cylindrical body `and larger than said reduced diameter so that said tubular covering maintains said resilient body in said state of contraction and is tightly frictionally retained on said body solely by the resilient expansive pressure exerted thereagainst by said contracted resilient body.

4. In a roll combination, a substantially solid elongated resilient rubbery cylindrical body capable of radial contraction to less than its natural diameter `and recoverable from a contracted condition to its natural diameter and shape, said resilient body having a rigid axial core and having a plurality of interior passages circumferentialily disposed -around said core fand extending substantially throughout the length olf said body, and being contracted throughout its length to a compressed state wherein it possesses a reduced diameter smaller than said natural diameter, `and a nonstretchable tubular covering on said contracted cylindrical body having an internal diameter smaller than the natural diameter of said cylindrical body and larger than said reduced diameter so that said tubular covering maintains said resilient body in said state of contraction and is tightly, `frictionally retained on said body solely by the resilient expansive pressure exerted thereagainst by said contracted resilient body.

5. In a roll combination, a substantially solid elongated resilient rubbery cylindrical body capable of radial contraction to less than its natural diameter and recoverable from `a contracted condition to its natural Adiameter and shape, said resilient body having at least one centrally disposed interior passage extending substantially throughout the length thereof -and being contracted throughout its length to a compressed state wherein it possesses a reduced di-ameter `smaller than said natural diameter, land a stii, preformed, non-stretchable, tubular covering on said contracted cylindrical body having an internal diameter smaller than the natural diameter of said cylindrical body and larger than said reduced diameter so that said tubular covering maintains said resilient body in said state of contraction and is tightly frictionally retained on -said body solely by the resilient expansive pressure exerted thereagainst by said contracted resilient body.

6. In a roll combination, a substantially solid elongated resilient rubbery cylindrical body capable of radiai contraction to less than its natural diameter and recoverable from a contracted condition toits natural diameter and shape, said resilient body having a rigid axial core and having a plurality olf interior passages circumi'erentially disposed around said core and extending lsub-stantially throughout the length of said body, and being contracted throughout its length to a compressed state wherein it possesses a reduced diameter smalier than said natural diameter, and a stiff, preformed, non-stretchable, tubular covering on said contracted cylindrical body having an internal diameter smaller than the natural diameter of said cylindrical body and larger than said reduced diameter so that said tubular covering maintains said resilient body in said stt-ate of contraction and is tightly rfrictionally retained on said body solely by the resilient expansive pressure exerted thereagainst by said contracted resilient body.

ReferencesCited in the le of this patent UNITED STATES PATENTS 1,145,558 Coppage July 6, 1915 1,681,829 Wesseler Aug. 21, 1928 2,044,640 Schuster June 16, 1936 2,746,138 Smith May 22, 1956

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