Sheet conveying roller and production method therefor

Abstract

The present invention provides a sheet conveying roller, which effectively reduces the amount of paper dust accumulated on its outer peripheral surface to thereby suppress sheet transportation failure. The sheet conveying roller includes a nonporous tubular elastic member ( 1 ). The elastic member ( 1 ) has a plurality of recesses ( 6 ) or a plurality of through-holes ( 8 ) equidistantly arranged in a center axis (L 1 ) direction thereof and equidistantly arranged in a circumferential direction thereof, and each having an opening having a round plan shape in an outer peripheral surface ( 2 ) thereof, wherein the recesses ( 6 ) each have a constant depth as measured thicknesswise of the elastic member ( 1 ), wherein the through-holes ( 8 ) each extend thicknesswise through the elastic member ( 1 ). A production method includes forming the elastic member by vulcanizing a rubber composition in a vulcanization mold having projections corresponding to the recesses or the through-holes.

What is claimed is: 
     
         1 . A sheet conveying roller comprising:
 a non-porous tubular elastic member;   wherein the elastic member has a plurality of recesses provided in an outer peripheral surface thereof as equidistantly arranged in a center axis direction thereof and equidistantly arranged in a circumferential direction thereof, the recesses each having an opening having a round plan shape as seen perpendicularly to the outer peripheral surface in the outer peripheral surface, and each having a predetermined depth as measured thicknesswise of the elastic member.   
     
     
         2 . The sheet conveying roller according to  claim 1 , wherein the recesses include cylindrical recesses. 
     
     
         3 . The sheet conveying roller according to  claim 2 , wherein the recesses each have an opening diameter of 0.5 mm to 5 mm. 
     
     
         4 . The sheet conveying roller according to  claim 3 , wherein the recesses are equidistantly arranged in the center axis direction of the elastic member so as to occupy an area of 50% to 60% of the outer peripheral surface of the elastic member as measured in the center axis direction of the elastic member. 
     
     
         5 . The sheet conveying roller according to  claim 1 , wherein the recesses include columnar recesses each having a polygonal plan shape, an oval plan shape or any other plan shape inscribed inside the round plan shape as seen perpendicularly to the outer peripheral surface. 
     
     
         6 . A sheet conveying roller comprising:
 a non-porous tubular elastic member having an outer peripheral surface and an inner peripheral surface disposed coaxially with each other;   wherein the elastic member has a plurality of through-holes equidistantly arranged in a center axis direction thereof and equidistantly arranged in a circumferential direction thereof, the through-holes each having an opening having a round plan shape as seen perpendicularly to the outer peripheral surface in the outer peripheral surface and extending thicknesswise through the elastic member to the inner peripheral surface.   
     
     
         7 . The sheet conveying roller according to  claim 6 , wherein the through-holes include cylindrical through-holes. 
     
     
         8 . The sheet conveying roller according to  claim 7 , wherein the through-holes each have an opening diameter of 0.5 mm to 5 mm. 
     
     
         9 . The sheet conveying roller according to  claim 8 , wherein the through-holes are arranged in the center axis direction of the elastic member so as to occupy an area of 50% to 60% of the outer peripheral surface of the elastic member as measured in the center axis direction of the elastic member. 
     
     
         10 . The sheet conveying roller according to  claim 6 , wherein the through-holes include columnar through-holes each having a polygonal plan shape, an oval plan shape or any other plan shape inscribed inside the round plan shape as seen perpendicularly to the outer peripheral surface. 
     
     
         11 . A method of producing a sheet conveying roller including a nonporous tubular elastic member having a plurality of columnar recesses in an outer peripheral surface thereof, the method comprising the steps of:
 providing a vulcanization mold which includes an outer mold and an inner mold,   the outer mold being circumferentially dividable into at least two mold pieces, and having a shape-imparting tubular inner surface corresponding to the outer peripheral surface of the elastic member, and a plurality of projections projecting radially inward from the shape-imparting inner surface and each having a sectional shape corresponding to a plan shape of the columnar recesses of the elastic member and a projection height corresponding to a depth of the columnar recesses as measured thicknesswise of the elastic member,   the inner mold having a shape-imparting tubular outer surface to be located coaxially with the shape-imparting inner surface so as to be spaced a distance corresponding to a thickness of the elastic member from the shape-imparting inner surface; and   forming the nonporous tubular elastic member with the plurality of recesses formed as corresponding to the projections in the outer peripheral surface thereof by preheating the vulcanization mold, locating the shape-imparting inner surface of the outer mold and the shape-imparting outer surface of the inner mold of the vulcanization mold coaxially with each other, filling a space defined between the shape-imparting inner surface and the shape-imparting outer surface with a rubber composition as a material for the elastic member, and vulcanizing the rubber composition.   
     
     
         12 . A method of producing a sheet conveying roller including a nonporous tubular elastic member having a plurality of columnar through-holes extending through the elastic member, the method comprising the steps of:
 (1) providing a vulcanization mold which includes an outer mold and an inner mold,
 the outer mold being circumferentially dividable into at least two mold pieces, and having a shape-imparting tubular inner surface having an inner diameter equal to a sum of an outer diameter of the tubular elastic member and a predetermined grinding margin, 
 the inner mold having a shape-imparting tubular outer surface to be located coaxially with the shape-imparting inner surface so as to be spaced a distance equal to a sum of a thickness of the elastic member and the grinding margin from the shape-imparting inner surface, and a plurality of projections projecting radially outward from the shape-imparting outer surface and each having a sectional shape corresponding to a plan shape of the columnar through-holes of the elastic member and a projection height that is not less than the thickness of the elastic member and less than the sum of the thickness of the elastic member and the grinding margin, and 
 forming a nonporous tubular elastic body having a plurality of columnar recesses corresponding to the projections in an inner peripheral surface of the elastic body by preheating the vulcanization mold, locating the shape-imparting inner surface of the outer mold and the shape-imparting outer surface of the inner mold of the vulcanization mold coaxially with each other, filling a space defined between the shape-imparting inner surface and the shape-imparting outer surface with a rubber composition as a material for the elastic member, and vulcanizing the rubber composition; and 
   (2) grinding an outer peripheral portion of the elastic body by the grinding margin to expose the columnar recesses in an outer peripheral surface of the resulting elastic body to form the plurality of through-holes in the elastic member.