Drawn, grooved stainless steel magnetic developer roll and process for making same

Abstract

A drawn stainless steel magnetic development roll having a coating-free developer-receptive surface, and a process for making a development magnetic roll drawn from stainless steel and having a developer-receptive, non-abrasive integral surface. The present invention provides a process for making a novel magnetic roll by cold drawing stainless steel rolls to have a desired grooved surface finish, diameter, straightness, runout, and other mechanical tolerance requirements.

What is claimed:  
     
         1 . Hollow magnetic developer roll for use in an electrophotographic imaging machine, comprising a drawn hollow non-magnetic stainless steel roll having formed in the outer surface of the wall thereof a plurality of narrow axial grooves, each having a maximum depth of between about 0.01 mm and 0.5 mm, uniformly-spaced around the other periphery of the roll.  
     
     
         2 . A developer roll according to  claim 1  in which said axial grooves are hemispherical in cross-section.  
     
     
         3 . A developer roll according to  claim 2  in which said axial grooves have a maximum depth between about 0.1 mm and 0.45 mm.  
     
     
         4 . A developer roll according to  claim 3  in which said arial grooves have a maximum depth of about 0.4 mm.  
     
     
         5 . A developer roll according to  claim 1  in which said axial grooves are uniformly spaced from each other—,center-to-center,—by a distance between about 1.5 mm and 2.5 mm.  
     
     
         6 . A developer roll according to  claim 5  in which said axial grooves are uniformly spaced by a distance of about 1.9 mm.  
     
     
         7 . A developer roll according to  claim 1  in which the opposed ends of the hollow roll are counterbored inwardly a short distance to render the wall thickness of the roll uniform at said ends.  
     
     
         8 . A developer roll according to  claim 1  in which the thickness of the wall is between about 2.5 mm and 3.5 mm.  
     
     
         9 . Process for producing a hollow stainless steel magnetic developer roll for use in an electropholographic imaging machine and having improved receptivity for electrophotographic developer materials, comprising cold-drawing a hollow non-magnetic stainless steel roll to the desired wall thickness, and cold-drawing a plurality of narrow axial grooves in the outer surface of the wall thereof, each having a maximum depth of between about 0.01 mm and 0.5 mm, uniformly spaced around the outer periphery of the roll.  
     
     
         10 . Process according to  claim 9  in which said axial grooves are formed by the displacement of stainless steel from the outer surface of the roll during the cold-drawing step.  
     
     
         11 . Process according to  claim 9  which comprises cold-drawing axial grooves which are hemispherical in cross-section.  
     
     
         12 . Process according to  claim 11  which comprises cold-drawing axial grooves having a maximum depth between about 0.1 mm and 0.45 mm.  
     
     
         13 . Process according to  claim 12  which comprises cold drawing axial grooves having a maximum depth of about 0.4 mm.  
     
     
         14 . Process according to  claim 9  which comprises spacing said axial grooves by a distance between about 1.5 mm and 2.5 mm.  
     
     
         15 . Process according to  claim 14  which comprises spacing said axial grooves by a distance of about 1.9 mm.  
     
     
         16 . Process according to  claim 9  which comprises the step of counterboring the—inner surface at the—opposed ends of the grooved roll inwardly a short distance to render the wall thickness of the roll uniform at said ends.  
     
     
         17 . Process according to  claim 9  in which the thickness of the wall is between about 2.5 mm and 3.5 mm.