Method to fabricate a tolerance ring with edge rounding from opposite major faces

Abstract

A novel method, for fabricating a tolerance ring suitable for use in applications such as an actuator assembly for a disk drive, is disclosed. The tolerance ring may be fabricated by steps including stamping a sheet metal section from a strip of sheet metal that has first and second edges that are parallel to a strip axis. A leading axial edge may be rounded from an inner major face and from an outer major face. A plurality of protrusions may be formed from the first major face. The sheet metal section may be bent into a substantially cylindrical shape having a central axis that is normal to the strip axis.

What is claimed is: 
     
         1 . A method of fabricating a tolerance ring, comprising:
 stamping a sheet metal section from a strip of sheet metal, the strip of sheet metal having first and second edges that are parallel to a strip axis, the strip of sheet metal having a first major face that is opposite a second major face;   rounding the first edge from the first major face and from the second major face;   forming a plurality of protrusions from the first major face; and   bending the sheet metal section into a substantially cylindrical shape having a central axis that is normal to the strip axis.   
     
     
         2 . The method of  claim 1  further comprising rounding the second edge from the first major face and from the second major face. 
     
     
         3 . The method of  claim 1  wherein the sheet metal section is a rectangular blank having third and fourth edges that are parallel to the central axis of the cylindrical shape after bending. 
     
     
         4 . The method of  claim 3  wherein the substantially cylindrical shape includes a circumferential gap between the third and fourth edges after bending. 
     
     
         5 . The method of  claim 2  wherein the first and second edges are rounded by skiving before the sheet metal section is stamped from the strip of sheet metal. 
     
     
         6 . The method of  claim 2  wherein the first and second edges are rounded by coining after the sheet metal section is stamped from the strip of sheet metal. 
     
     
         7 . The method of  claim 1  wherein forming the plurality of protrusions from the first major face comprises forming a plurality of bumps in the sheet metal section. 
     
     
         8 . The method of  claim 1  wherein forming the plurality of protrusions from the first major face comprises forming a plurality of corrugations in the sheet metal section. 
     
     
         9 . The method of  claim 1  wherein the sheet metal comprises stainless steel having a sheet thickness in the range of 0.076 to 0.100 mm. 
     
     
         10 . The method of  claim 2  wherein the strip of sheet metal defines a sheet thickness between the first and second major faces, and rounding the first and second edges comprises rounding at least 15% of the sheet thickness from each of the first and second major faces. 
     
     
         11 . The method of  claim 9  wherein the first edge rounding extends away from the first edge by a distance measured parallel to the central axis that is in the range of 0.025 mm to 0.140 mm. 
     
     
         12 . The method of  claim 2  wherein the second edge rounding extends away from the second edge by a distance measured parallel to the central axis that is in the range of 0.025 mm to 0.140 mm. 
     
     
         13 . A method of fabricating a tolerance ring, comprising:
 stamping a sheet metal section from a strip of sheet metal, the strip of sheet metal having first and second edges that are parallel to a strip axis, the strip of sheet metal having a first major face that is opposite a second major face;   rounding the first edge from the first major face and from the second major face by coining;   forming a plurality of bumps protruding from the first major face; and   bending the sheet metal section into a substantially cylindrical shape having a central axis that is normal to the strip axis.   
     
     
         14 . The method of  claim 13  further comprising rounding the second edge from the first major face and from the second major face. 
     
     
         15 . The method of  claim 14  wherein the strip of sheet metal defines a sheet thickness between the first and second major faces, and rounding the first and second edges comprises rounding at least 15% of the sheet thickness from each of the first and second major faces. 
     
     
         16 . The method of  claim 13  wherein the first edge rounding extends away from the first edge by a distance measured parallel to the central axis that is in the range of 0.025 mm to 0.140 mm,
 the first and second edges are rounded by skiving before the sheet metal section is stamped from the strip of sheet metal. 
 
     
     
         17 . A method of fabricating a tolerance ring, comprising:
 stamping a sheet metal section from a strip of sheet metal, the strip of sheet metal having first and second edges that are parallel to a strip axis, the strip of sheet metal having a first major face that is opposite a second major face;   rounding the first edge from the first major face and from the second major face by skiving prior to the stamping;   forming a plurality of protrusions from the first major face; and   bending the sheet metal section into a substantially cylindrical shape having a central axis that is normal to the strip axis.   
     
     
         18 . The method of  claim 17  further comprising rounding the second edge from the first major face and from the second major face by skiving prior to the stamping. 
     
     
         19 . The method of  claim 18  wherein the strip of sheet metal defines a sheet thickness between the first and second major faces, and rounding the first and second edges comprises rounding at least 15% of the sheet thickness from each of the first and second major faces. 
     
     
         20 . The method of  claim 17  wherein the first edge rounding extends away from the first edge by a distance measured parallel to the central axis that is in the range of 0.025 mm to 0.140 mm.