Abstract:
A roller including an inner tubing and an outer tubing which is fixed relative to the inner tubing by fixing means which includes welding the outer tubing to the inner tubing or by providing a plurality of radially disposed and spaced apart spokes rigidly interconnecting the inner elongate tubing to the outer elongate tubing. The roller with weldments is particularly suitably for a nipped application.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS  
       [0001]    The present application claims the benefit of the filing date of U.S. Provisional Patent Application No. 60/273,395. 
     
    
     
       FIELD OF THE INVENTION  
         [0002]    The present invention relates generally to rollers used in various kinds of machinery and, in particular, to rollers used in continuous web conveying or converting machinery.  
         BACKGROUND OF THE INVENTION  
         [0003]    Because all kinds of conveying and converting systems utilize rollers, considerable attention has been given to improving their reliability, reducing bending of the tubing and reducing the inertial tension required to turn the roller. In web (i.e., continuous sheet) machinery, all kinds of materials, e.g., paper, plastic, tissue, foam, may be looped around a series of rollers. The rollers must have a necessary rigidity and strength to support a web load while withstanding the turning torque stress produced by the web. Rollers have been made of steel, aluminum or other metals to provide the necessary rigidity and strength. Yet, the materials themselves have inherent problems. For example, steel rollers require excessive horsepower to overcome the initial start-up inertia and to keeping the steel rollers turning.  
           [0004]    Many patents disclose rollers and methods of making thereof. For example, U.S. Pat. No. 1,742,454 issued to Van Derhoef and U.S. Pat. No. 2,593,069 issued to Steinmetz teach methods of making roller rollers. U.S. Pat. No. 1,622,758 issued to Beulke et al.; U.S. Pat. No. 2,808,730 issued to Shank; and U.S. Pat. No. 3,958,837 issued to Chagawa disclose improved roller designs. U.S. Pat. No. 4,029,200 issued to Dillon teaches a roller design fabricated in plastic. U.S. Pat. No. 5,022,132 issued to Valster et al. and U.S. Pat. No. 5,568,976 issued to Gabriele disclose bearing mounts for rollers. U.S. Pat. No. 5,387,962 issued to Castelli et al. discloses a self-aligning roll for belt loop modules.  
           [0005]    In continuous web making machinery, all kinds of materials, e.g., paper, plastic, tissue, film, fabric, foam, etc., may be transported through a nip formed between two rollers. The purpose of a nip between a pair of rollers is to exert pressure on the web material. As is generally known, it is desirable to produce a uniform pressure across the nip formed between the rollers.  
           [0006]    One way to produce this desired result is to form a gradual crown on the outer surfaces of the rollers. The crown is in the form of a gradual increase in diameter of the roller toward the midpoint of the roller. When a crowned roller is combined with a straight roller or another crowned roller, and the ends of the opposed rollers are brought together, a uniform pressure can be produced along the entire length of the rollers as the rollers deflect under the applied load.  
           [0007]    In many machines and systems, many different crowns are needed for various sized rollers. The process of crowning a roller requires extensive, precision machining, thereby resulting in substantial sums associated with labor and manufacturing costs. Moreover, in many machines and systems, many different rollers of different lengths and diameters are needed. This requires extensive fabrication, costing substantial sums for labor and parts, as well as requiring a large inventory of tubing and bearing assemblies. Notwithstanding these known rollers and bearing mounts, the art has not adequately responded to date with the introduction of an roller which reduces job specific construction by eliminating end plugs, balancing weights, and extensive machining.  
         SUMMARY OF THE INVENTION  
         [0008]    Accordingly, the present invention provides a roller design which substantially reduces the need for crowning rollers used in nipped applications, and generally reduces job specific construction in other applications. In one aspect of the present invention, there is provided an inner tubing and an outer tubing concentrically disposed around the inner tubing. The inner tubing has an outer diameter and the outer tubing has an inner diameter which is larger than the outer diameter of the inner tubing. To fix the positions of the inner and outer tubing, e.g., weldments spaced a distance from each end of the tubings are suitably provided to secure the outer tubing to the inner tubing. During a nipped application, the outer tubing will pivot about the weldments to substantially provide a uniform pressure across the nip. This pivoting effect reduces the amount of crowning normally required for a particular nipped application.  
           [0009]    In another aspect of the present invention, there is provided a method of assembling a roller as just described. The method includes providing an inner tubing and an outer tubing, placing the outer tubing around the inner tubing, positioning a fixture device at opposite ends of the roller to space the outer tubing away from the inner tubing, drilling a plurality of holes around the circumference of the outer tubing at a distance spaced inward from both ends of the roller, filling the holes with welding material to securely fasten the outer tubing to the inner tubing, and thereafter removing the fixture device from between the inner tubing and the outer tubing.  
           [0010]    The foregoing design of an inner and outer tubing can be extended to other embodiments in which the inner and outer tubings are secured relative to each other by different means. Thus, in another aspect, the present invention provides a roller tubing, which includes an outer elongate tube; an inner elongate tube concentrically disposed within the outer tube; and a plurality of radially disposed spokes rigidly interconnecting the inner tube to the outer tube.  
           [0011]    In yet another aspect, the invention provides a roller which includes a substantially cylindrical roller body having opposed ends. The roller body includes an outer elongate tube; an inner elongate tube concentrically disposed within the outer tube; a plurality of radially disposed spokes rigidly interconnecting the inner tube to the outer tube; and a pair of bearings, spaced apart and press fit into the inner surface of the inner tube, at a distance apart from the ends of the roller body.  
           [0012]    In a further aspect, the invention provides a method of constructing an roller. The method includes the steps of (i) providing a length of a tubing having opposed ends, and including an outer elongate tube; an inner elongate tube having an inner surface, and concentrically disposed within the outer tube; and a plurality of spokes rigidly interconnecting the inner tube to the outer tube; (ii) inserting a bearing assembly into the inner surface of the inner tube at a distance apart from an end of the tubing material, the inner surface closely receiving the bearing assembly; and (iii) press-fitting a support shaft into the bearing assembly.  
           [0013]    Other advantages and a fuller appreciation of the specific attributes of this invention will be gained upon an examination of the following drawings, detailed description of preferred embodiments, and appended claims. It is expressly understood that the drawings are for the purpose of illustration and description only, and are not intended as a definition of the limits of the invention.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0014]    The preferred exemplary embodiment of the present invention will hereinafter be described in conjunction with the appended drawing wherein like designations refer to like elements throughout and in which:  
         [0015]    [0015]FIG. 1 is a cross-sectional view of a roller according to one aspect of the present invention;  
         [0016]    [0016]FIG. 2 is a cross-sectional view of an alternative roller according to one aspect of the present invention;  
         [0017]    [0017]FIG. 3 is a cross-sectional view of yet another alternative roller according one aspect of the present invention;  
         [0018]    [0018]FIG. 4 is an isometric view of a roller tubing in accordance with yet another aspect of the present invention;  
         [0019]    [0019]FIG. 5 is a cross-sectional view of the roller tubing of FIG. 4 along line  5 - 5 ′; and  
         [0020]    [0020]FIG. 6 is a cross-sectional view of a roller in accordance with the present invention, illustrating the placement of bearings assemblies in the recessed bearing bores. 
     
    
       [0021]    Before the embodiments of the invention are explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangements of the components set forth in the following description or illustrated in the drawings. The invention is capable of other embodiments and of being practiced or being carried out in various ways. Also, it is understood that the phraseology and terminology used herein are for the purpose of description and should not be regarded as limiting. The use of “including” and “comprising” and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items and equivalents thereof.  
       DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0022]    Illustrated in FIGS.  1 - 3  are rollers embodying one aspect of the present invention. FIGS. 4 and 5 embody another aspect of the present invention. It should be understood that the principles of the present invention can be applied to other roller designs, and the rollers shown and described in FIGS.  1 - 5  are merely examples of such rollers.  
         [0023]    Reference is initially made to FIG. 1 depicting a roller  10  in accordance with the present invention. The roller  10  is substantially cylindrical. The roller  10  is suitably made of steel or aluminum, but can be made of other suitable materials. The roller  10  is shown as being a cantilevered roller, but may be of other suitable rollers. The roller  10  includes an elongated inner tubing  14  having an outer diameter  18 , a first end  22  and a second end  26 . The inner tubing  14  can be substantially hollow as shown or of any other suitable construction. The roller  10  further includes an elongated outer tubing  30  having an inner diameter  34 , an outer circumferential surface  38 , a first end  42  and a second end  46 . The roller  10  rotates about a shaft according to any acceptable manner, such as by providing a pair of bearing assemblies on opposite ends of the roller  10  between the inner tubing  14  and the axial shaft. In one aspect of the invention, the outer tubing  30  is fixed in position relative to the inner tubing  14 , by weldments, as shown by reference numeral  50  depicting the welding material. A rubberized surface  52  may be applied to the outer tubing  30 , if desired.  
         [0024]    The roller  10  is assembled as follows. The inner diameter  34  of the outer tubing  30  is larger than the outer diameter  18  of the inner tubing  14 , so that the outer tubing  30  can be positioned over the inner tubing  14 . A fixture device (not shown) is positioned between the inner tubing  14  and the outer tubing  30 , so that the central longitudinal axes of the inner tubing  14  and the outer tubing  30  are substantially coincident (see reference numeral  54  referring to the circumferential space between the outer surface of the inner tubing  14  and the inner surface of the outer tubing  30 ). Although not clearly shown, a plurality of holes spaced inward from each end  42  and  46  of the outer tubing  30  are drilled through the outer tubing material. Preferably, the holes are equally spaced from the ends  42  and  46 , and also equally spaced around the circumference of the outer tubing  30 . Referring to FIG. 1, the holes are located approximately halfway from the ends of the tubing  42  and  46 , respectively, to the middle of the outer tubing  30 , but may be located in other suitable locations. Any number of holes may be provided around the circumference of the outer tubing  30 , depending on the desired effect. The holes may have different diameters, depending on the desired weld between the inner tubing  14  and the outer tubing  30 . The holes are filled with appropriate welding material, such as aluminum welding rods, so as to secure the outer tubing  30  to the inner tubing  14 . As representatively shown by reference numerals  50 , the welding material will slightly spread out in the space  54  between the inner tubing  14  and the outer tubing  30 .  
         [0025]    According to the principles of the present invention, in a nipped application, the outer tubing  30  is designed to pivot about the weldments  50 . In this way, as the ends of opposing rollers are brought together, the portion of the outer tubing  30  between the weldments  50  will tend to bow outward, thereby minimizing the need for crowning the roller  10 .  
         [0026]    [0026]FIG. 2 depicts an alternative roller  10 ′. The roller  10 ′ incorporates the features of the WINertia dead shaft roller roll sold by Engineered Metals Corporation of Monona, Wis., and described in U.S. Pat. No. 6,113,059, which is hereby incorporated herein by reference.  
         [0027]    [0027]FIG. 3 depicts yet another roller  10 ″.  
         [0028]    Reference is now made to FIGS. 4 and 5 depicting a roller tubing in accordance with another aspect of the present invention, and generally designated as reference numeral  100 . Tubing  100  is substantially cylindrical, and has an outer elongate, substantially hollow cylindrical wall, shell or tube  122  and an inner elongate, substantially hollow cylindrical wall of shell  124  concentrically disposed within the outer wall  122 . The central longitudinal axes of tubes  122  and  124  are substantially coincident with each other. Outer shell  122  and inner shell  124  are fixed relative to each other, e.g., by being rigidly interconnected by a plurality of elongate interconnectors, bars or spokes  126  which run the length of tubing  100 . The number of spokes  126  can be varied, for example, from three to nine.  
         [0029]    Outer shell  122  has an inside circumferential surface  128 , an outside circumferential surface  130 . Outer shell  122  also has an inside diameter  134 , an outside diameter  136  and a wall thickness  138 . Thickness  138  is suitably, e.g., about 0.200 inches.  
         [0030]    Inner shell  124  has an outer circumferential surface  140  and an inner circumferential surface  142 . Inner shell  124  has an inside diameter  144 , an outer diameter  146  and a wall thickness  148 . Thickness  148  is suitably, e.g., about 0.100-0.150 inches depending on diameter  136  of outer wall  122 . The thicknesses of both shells  122  and  124  are substantially less than the typical nominal sidewall thickness of conventional single-walled tubing.  
         [0031]    Spokes  126  interconnect outer surface  140  of inner tube  124  with inside surface  128  of outside tube  122 , spokes  126  being radially disposed and equally spaced on circumferential surface  140  and circumferential surface  128  and extending therebetween. Spokes  126  define a plurality of spaces  127 . Spokes  126  have sidewalls  147 , a thickness  149  and a length  151 . Thickness  149  is suitably, e.g., about 0.100-0.150 inches depending on diameter  136  of outer wall  122 . The spokes  126  can be of any length, e.g., length  151  is suitably about 0.5 inch to 1.5 inches depending on diameter  136 . Concentric shells  122  and  124  and spokes  126  are suitably constructed of materials such as extruded aluminum, carbon fiber and plastic. The plastic is suitably any hard wearing, impact resistant polymer or copolymer composition, e.g., a polyester, a polypropylene, a nonfoamed polyurethane.  
         [0032]    Reference is now made to FIG. 6 wherein a roller  152  constructed of tubing  100  having outer shell  122 , inner shell  124  and spokes  126  as described hereinbefore, is shown. Roller  152  includes a roller body  154 , two bearing assemblies  156   a  and  156   b  and an axial elongate roller support shaft  158  about which roller  152  rotates. Support shaft  158  has an outer circumferential surface  160 . The central longitudinal axes of support shaft  158  and roller  152  are substantially coincident.  
         [0033]    Bearing assemblies  156   a  and  156   b  each have an inner race  162  with an inner circumferential surface  164  and an outer race  166  with an outer circumferential surface  168 . Inner race  162  is press-fit onto support shaft  158  and outer race  162  is press-fit into a machined inner surface  143  of inner surface  142  of inner tube  124 , i.e., surface  143  is suitably machined, as needed, to match the bearing assembly outside diameter to form machined surface  143 . In this way, roller body  154  rotates in unison with outer race  166  of the bearing. The press or interference fit between outer circumferential surface  168  of outer race  166  and machined inner surface  143  of inner tube  124  prevents roller body  154  from rotating relative to outer race  166 . The press or interference fit between inner circumferential surface  164  of inner race  162  and outer circumferential surface  160  of support shaft  158  prevents inner race  162  from rotating relative to support shaft  158 . While roller body  154  is suitably made of, e.g., extruded aluminum, carbon fiber or plastic, support shaft  158  may be suitably made of the same or another material, e.g., steel. Bearing  156   a  and  156   b  may be any class of insert ball bearings.  
         [0034]    As can be seen in FIG. 6, bearings  156   a  and  156   b  are recessed from the ends of roller body  154 . Tubing  100 , from which roller body  154  is constructed, permits bearings to be so mounted and recessed in inner tube  124 . As such, no end plugs are necessary, thus, eliminating their installation and their machining for bearing bores. The recessed mounting also shortens the distance between the bearings and therefore, decreases the deflection property in the roller body as explained in detail hereinafter.  
         [0035]    Inside diameter  144  of inner tube  124  is matched to industry standards for bearings. Thus, while outer diameter  136  of outer tube or shell  122  can be varied, e.g., 4″, 5″, 6″, inside diameter  144  of inner tube or shell  124  can be maintained to match the industry standards for bearings. As outer diameter  136  increases, length  151  and thickness  148  of spokes  126  are also proportionately increased as the distance between inner tube  124  and outer tube  122  increases.  
         [0036]    A roller constructed from double-walled tubing material in accordance with the present invention provides an advantageous 20% reduction in weight on average compared to ordinary single-walled tubing because of its thinner walls. Thus, the tubing provides substantial cost savings in tubing materials.  
         [0037]    Variations and modifications of the foregoing are within the scope of the present invention. It is understood that the invention disclosed and defined herein extends to all alternative combinations of two or more of the individual features mentioned or evident from the text and/or drawings. All of these different combinations constitute various alternative aspects of the present invention. The embodiments described herein explain the best modes known for practicing the invention and will enable others skilled in the art to utilize the invention. The claims are to be construed to include alternative embodiments to the extent permitted by the prior art.  
         [0038]    Various features of the invention are set forth in the following claims.