Blade sharpening and guide mechanism

An apparatus for sharpening a cutting blade of a numerically controlled cutting apparatus, comprising:

• means for supporting one or more layers of material to be cut on a cutting surface;
• carriage means disposed above said cutting surface for movement across said cutting surface;
• a cutting head assembly disposed on said carriage means, said cutting head assembly including a cutting blade and means for raising and lowering said cutting blade with respect to said cutting surface, said cutting head assembly further including means for rotating said cutting blade about an axis perpendicular to said cutting surface and grinding means for sharpening said cutting blade, said rotating means being operable to rotate said cutting blade from a first angular position at which cutting is performed to a second angular position at which said grinding means is operable to sharpen said cutting blade, said first angular position being variable with respect to said axis and said second angular position being fixed with respect to said axis, said grinding means being operable during a sharpening operation to sharpen one side of said cutting blade for a predetermined period of time and then to sharpen the other side of said cutting blade for another predetermined period of time, said grinding means including a sharpening motor fixedly mounted on said carriage means, grinder support means pivotally mounted on said rotating means, a pair of grinding wheels rotatably supported on said grinder support means, and means for engaging an output shaft of said sharpening motor with said grinder support means and said grinding wheels such that said grinder support means biases one of said grinding wheels in contact with one side of said cutting blade when said output shaft is rotated in one direction and said grinder support means biases the other one of said grinding wheels in contact with the other side of said cutting blade when said output shaft is rotated in an opposite direction, said engaging means driving said grinding wheels in rotation while biasing said grinder support means, said engaging means comprising a shaft rotatably supported on said rotating means, said shaft pivotally supporting said grinder support means and biasing said grinder support means upon rotation of said shaft, said engaging means further including belt means extending between said grinding wheels and said shaft whereby rotation of said shaft effects rotation of said grinding wheels;
• and
• programmable controller means for determining when sharpening of said cutting blade is to be performed, said programmable controller means being operatively connected to said raising and lowering means for actuation thereof whereby said cutting blade is raised such that a bottom end thereof is spaced from said cutting surface during said sharpening operation, said programmable controller means being further operably connected to said rotating means for actuation thereof whereby said cutting blade is rotated from said first angular position to said second angular position prior to said sharpening operation, said programmable controller means being further operably connected to said grinding means for actuation thereof during said sharpening operation whereby said grinding means sharpens one side of said cutting blade for a predetermined period of time and then sharpens the other side of said cutting blade for another predetermined period of time after which said programmable controller means actuates said rotating means and said raising and lowering means to return said cutting blade to said first angular position and lower said bottom end thereof, respectively.

A method of sharpening a cutting blade of a numerically controlled cutting apparatus comprising:

• raising said cutting blade such that a bottom end thereof is spaced above a cutting surface;
• rotating said cutting blade about an axis perpendicular to said cutting surface from a first angular position at which cutting is performed, to a second angular position at which sharpening is performed, said first angular position being variable with respect to said axis and said second angular position being fixed with respect to said axis;
• sharpening said cutting blade by actuating grinding means to first sharpen one side of said cutting blade for a predetermined period of time and then to sharpen the other side of said cutting blade for another predetermined period of time;
• and
• rotating said cutting blade from said second angular position to said first angular position;
• and
• lowering said blade to begin a cutting operation.