Low-mass roller or pulley

Abstract

A low-mass roller is disclosed comprising a cylindrical body formed of polymeric material and having an exterior surface, first and second open ends and defining an interior tubular space along a longitudinal axis therethrough for receiving an axle; and an outer shell formed of thin metal covering the exterior surface of the cylindrical body. In another aspect, the outer shell of the low-mass roller comprises an assembly of first and second tubular shells having inside diameters, equal within a predetermined tolerance, at first respective ends thereof, wherein the first respective ends are joined together and welded. The assembly of the first and second tubular shells includes a weld ring disposed between and nested within the first respective ends of the first and second tubular shells such that the shells are held together in alignment during the welding process.

1 . A weld ring for joining first and second round, thin-walled tubes of a uniform wall thickness, like inside diameter and like material, comprising: 
 a circular band of said like material having first and second parallel edges, a band inside diameter and an outside diameter equal to or slightly less than said like inside diameter of said first and second tubes; and    a circumferential ring of said like material extending orthogonally outward by a height greater than said wall thickness from said outside diameter around said band and disposed approximately midway between said first and second parallel edges of said band; wherein    said circular band and said circumferential ring are formed as one piece of said like material.    
   
   
       2 . The weld ring of  claim 1 , wherein said weld ring in use being disposed with each said first and second edge of said circular band portion inserted in nested relationship within a respective end of one of said first and second tubes and each said respective end of said first and second tubes butted up against a proximate side of said circumferential ring portion of said weld ring.  
   
   
       3 . The weld ring of  claim 1 , wherein said like material of said circular band and circumferential ring portions is a metal capable of joining said first and second thin-walled tubes of said like material by a welding process.  
   
   
       4 . The weld ring of  claim 1 , wherein said metal like material of said weld ring and said first and second thin-walled tubes is stainless steel.  
   
   
       5 . The weld ring of  claim 1 , wherein said like material of said circular band and said circumferential ring portions is a non-metallic material capable of joining said first and second thin-walled tubes of said non-metallic material by a process selected from the group consisting of welding, cementing, gluing and epoxying.  
   
   
       6 . The weld ring of  claim 3 , wherein said welding process comprises a process performed using energy of a form selected form the group consisting of thermal energy, electric energy, optical energy, chemical energy and acoustic energy.  
   
   
       7 . The weld ring of  claim 5 , wherein said welding process comprises a process performed using energy of a form selected form the group consisting of thermal energy, electric energy, optical energy, chemical energy and acoustic energy.  
   
   
       8 . The weld ring of  claim 1 , wherein said circular band and said circumferential ring are formed of one piece of said like material by a process selected from the group consisting of machining, casting and molding.  
   
   
       9 . A method for making a low-mass roller, comprising the steps of: 
 forming a thin-walled, cylindrical outer shell of the low-mass roller of metal, the outer shell having an exterior surface, an interior surface and a longitudinal axis coincident with an axis of rotation of the low-mass roller, the outer shell further having first and second ends; and    forming a hollow body in situ within the outer shell of a polymeric material such that the assembly of the outer shell and the hollow body remain in contact with the interior surface of the outer shell and further such that the hollow body defines a cylindrical axial space surrounding and coincident with said axis of rotation for receiving an axle.    
   
   
       10 . The method of  claim 9 , wherein the step of forming a thin-walled, cylindrical outer shell comprises the step of: 
 shaping the first and second ends of the outer shell to define circular alignment openings and partially enclose the polymeric hollow body within the outer shell.    
   
   
       11 . The method of  claim 9 , wherein the step of forming a hollow body comprises the step of: 
 providing a wall-thickness of the hollow body substantially greater than the wall-thickness of the thin-walled outer shell.    
   
   
       12 . The method of  claim 9 , wherein the step of forming a hollow body comprises the steps of: 
 forming the hollow body of a polymeric material that conducts electricity.    
   
   
       13 . The method of  claim 9 , wherein the step of forming a thin-walled, cylindrical outer shell comprises the steps of: 
 forming first and second tubular shell sections of the thin-walled metal and having inside diameters, equal within a predetermined tolerance, at first respective ends thereof;    assembling the first respective ends of the first and second tubular shell sections upon a weld ring disposed therebetween; and    welding the assembled first and second tubular shell sections and the weld ring together.    
   
   
       14 . The method of  claim 13 , wherein the step of forming comprises the steps of: 
 performing a drawing operation upon a pre-shaped sheet metal blank;    trimming the drawn tubular shell section to a predetermined dimension; and    removing material from an end opposite from the first respective end of the tubular shell section along and perpendicular to the longitudinal axis.    
   
   
       15 . The method of  claim 14 , wherein the step of performing comprises pre-shaping the sheet metal blank from stainless steel.  
   
   
       16 . The method of  claim 13 , wherein the step of forming comprises performing a process upon a sheet metal blank selected from the group consisting of drawing, spinning and stamping processes.  
   
   
       17 . The method of  claim 13 , wherein the step of providing a weld ring comprises the step of: 
 forming the weld ring as a single piece of the same material as the first and second tubular shell sections by at least one process selected from the group consisting of machining, forging, stamping, casting and molding.    
   
   
       18 . The method of  claim 13 , wherein the step of assembling further comprises the step of: 
 supporting the assembled portions of the outer shell in a true alignment along the longitudinal axis.    
   
   
       19 . The method of  claim 13 , wherein the step of welding comprises the steps of: 
 applying the welding energy to the outermost edge of the circumferential ring such that welding occurs at the interface between the weld ring and the first and second tubular shell sections; and    smoothing the exterior surface of the welded outer shell to provide a uniform exterior surface finish.    
   
   
       20 . The method of  claim 19 , wherein the step of smoothing comprises the steps of: 
 grinding a weld bead surrounding the cylindrical outer shell to provide a continuous surface at a constant radius from the longitudinal axis across the region of the weld ring; and    polishing the exterior surface of the cylindrical outer shell.    
   
   
       21 . A method for joining first and second thin-walled tubing sections having an equal first cross-section with the other, comprising the steps of: 
 cutting a first end, of a first thin-walled tubing section to be joined, at a first angle with respect to the longitudinal centerline of the first tubing section;    cutting a first end, of a second thin-walled tubing section to be joined, at the first angle with respect to the longitudinal centerline of the second tubing section; and    assembling the first ends of the first and second thin-walled tubing sections together end-to-end and overlapping respective sides of an outer surface of a band portion of a weld ring disposed in a nesting relationship therewith, wherein the weld ring includes a circumferential ring portion around the outer surface of the band portion of the weld ring and extending outward from the outer surface of the band portion of the weld ring at the first angle with respect to the longitudinal centerline of the joined first and second thin-walled tubing sections such that the circumferential ring portion of the weld ring is disposed between the respective first ends of the first and second thin-walled tubing sections.    
   
   
       22 . The method of  claim 21 , wherein the first angle with respect to the longitudinal centerline of the first and second tubing sections and the weld ring is 90 degrees within a predetermined tolerance.  
   
   
       23 . The method of  claim 21 , wherein the predetermined tolerance is plus or minus one degree.  
   
   
       24 . The method of  claim 21 , further comprising the step of: 
 fabricating the weld ring of a section of thin-walled tubing having the same cross-section shape as the first and second thin-walled tubing sections and outer cross-section dimensions less than corresponding inner cross-section dimensions of the first and second thin-walled tubing sections such that the band portion of the weld ring may be nested within and in contact with the respective first ends of the first and second thin-walled tubing sections; and    fabricating the circumferential ring portion of the weld ring around the outer surface of the weld ring such that the circumferential ring portion extends from the outer surface of the weld ring by a height greater by a predetermined distance than the wall thickness of the thin-walled tubing sections.    
   
   
       25 . The method of  claim 21 , further comprising the steps of: 
 supporting the assembly of the first and second thin-walled tubing sections upon the weld ring in uniform alignment with the longitudinal centerline; and welding the weld ring to the assembled tubing sections by applying welding energy to the circumferential ring portion of the weld ring.    
   
   
       26 . The method of  claim 13 , further comprising the step of: 
 providing a weld ring band portion having an outside diameter sized to nest within the inside diameter at each first respective end of the first and second tubular shell sections wherein further a circumferential ring is disposed around the outside diameter of the band portion along a midline of the band portion and extending orthogonally from the midline of the outside diameter of the band portion of the weld ring.    
   
   
       27 . The method of  claim 26 , further comprising the step of: 
 nesting the weld ring within and between the first respective ends of the first and second tubular shell sections upon assembly thereof such that the first respective ends of the first and second tubular shell sections are butted against respective sides of said circumferential ring.