Powered sharpener with controlled deflection of flexible abrasive member

Abstract

Apparatus and method for sharpening a cutting tool having a blade portion with a cutting edge, such as but not limited to a kitchen knife. In some embodiments, a powered sharpener moves a flexible abrasive member such as a belt or disc along a neutral plane. A support member contactingly supports a back side of the flexible abrasive member at a medial location along the neutral plane. The support member is positioned adjacent a contact region of an abrasive surface on an opposing front side of the flexible abrasive member against which a cutting edge is brought during a sharpening operation. In some cases, the support member is a stationary or moveable support member such as a pin or roller offset from the contact region. In other cases, the support member is a platen that projects forward to support the contact region.

What is claimed is: 
     
         1 . A sharpener for sharpening a cutting tool, comprising:
 a flexible abrasive belt that is moved by an electric motor along a belt path comprising at least a first roller and a second roller, the flexible abrasive member comprising an outer abrasive surface and an inner backing layer;   a platen assembly positioned between the first and second rollers, the platen assembly spring biased to exert a biasing force upon the inner backing layer of the flexible abrasive belt to advance the flexible abrasive belt beyond a tangential plane extending from the first roller to the second roller, the platen assembly moveable independently of the tangential plane; and   a guide assembly adjacent the flexible abrasive member comprising a side support surface configured to contactingly support a side surface of the cutting tool during a sharpening operation in which a cutting edge of the cutting tool is presented against the outer abrasive surface of the flexible abrasive belt at a position opposite the platen assembly.   
     
     
         2 . The sharpener of  claim 1 , wherein an amount of force supplied to the cutting tool by the outer abrasive surface during the sharpening operation is controlled by the biasing force supplied by the platen assembly. 
     
     
         3 . The sharpener of  claim 1 , wherein the platen assembly has opposing first and second ends, wherein the first end of the platen assembly is attached to a frame coupled to at least a selected one of the first or second rollers, and wherein the second end of the platen assembly is configured to move with respect to the frame. 
     
     
         4 . The sharpener of  claim 1 , wherein the platen assembly places a segment of the flexible abrasive belt extending between the first and second rollers along a neutral plane, the neutral plane having a first linear segment that extends from the first roller to the platen assembly and a second linear segment that extends from the second roller to the platen assembly, the second linear segment non-parallel to the first linear segment. 
     
     
         5 . The sharpener of  claim 1 , wherein the platen assembly comprises a platen surface that contactingly engages the inner backing layer along a length of the belt path less than an overall distance between the first and second rollers. 
     
     
         6 . The sharpener of  claim 5 , wherein the platen surface is nominally flat. 
     
     
         7 . The sharpener of  claim 5 , wherein the platen surface is curvilinear. 
     
     
         8 . The sharpener of  claim 1 , further comprising a limit stop feature that limits a desired spring travel of the platen assembly. 
     
     
         9 . The sharpener of  claim 1 , wherein a selected one of the first or second rollers is characterized as a drive roller coupled to the electric motor and a remaining one of the first or second rollers is characterized as an idler roller. 
     
     
         10 . The sharpener of  claim 9 , further comprising a biasing member coupled to the idler roller to maintain a desired tension in the flexible abrasive belt during the sharpening operation. 
     
     
         11 . The sharpener of  claim 1 , wherein the platen assembly comprises an elongated, flexible plate. 
     
     
         12 . The sharpener of  claim 1 , wherein the first roller has a first outermost diameter and the second roller has a different, second outermost diameter. 
     
     
         13 . The sharpener of  claim 1 , wherein the electric motor is disposed within a housing, the housing having a user handle portion configured to be gripped by a hand of a user and held in free space during the sharpening operation. 
     
     
         14 . The sharpener of  claim 1 , wherein the guide assembly is moveable with respect to the platen assembly. 
     
     
         15 . The sharpener of  claim 1 , wherein no additional rollers apart from the first and second rollers are disposed along the belt path. 
     
     
         16 . The sharpener of  claim 1 , wherein the belt path is characterized as a triangular belt path. 
     
     
         17 . A sharpener for sharpening a cutting tool, comprising:
 a flexible abrasive belt that is moved by an electric motor and supported by at least a first support roller along a neutral plane having opposing proximal and distal ends, the flexible abrasive belt having a front side with an abrasive surface and a back side opposite the front side;   a guide assembly adjacent the flexible abrasive member to support the cutting tool during a sharpening operation in which a cutting edge of the cutting tool is presented against the flexible abrasive member, the guide assembly having a side support surface to contactingly support a side surface of the cutting tool;   a platen member disposed to contactingly support the back side of the flexible abrasive member between the proximal and distal ends of the neutral plane opposite the contact region, the platen member applying a biasing force to displace the flexible abrasive member toward the contact region beyond an initial tangential plane established by the first support member; and   a limit stop feature that limits a desired spring travel of the platen assembly during the sharpening operation.   
     
     
         18 . The sharpener of  claim 17 , further comprising a biasing member attached to the platen member to advance the medial portion of the flexible abrasive member toward the contact region away from the tangential plane to the neutral plane. 
     
     
         19 . The sharpener of  claim 17 , wherein the electric motor is disposed within a housing, the housing having a user handle portion configured to be gripped by a hand of a user and held in free space during the sharpening operation. 
     
     
         20 . The sharpener of  claim 17 , wherein the guide assembly is moveable with respect to the platen assembly.