Patent ID: 7251897

Claim:
A blade clamping device for clamping a blade comprising: a cylindrical rotatable sleeve having a proximal end in which is formed an aperture for a blade; a rotatable member mounted substantially coaxially within the cylindrical rotatable sleeve and having a proximal end; a blade carrier disposed within the cylindrical rotatable sleeve and having a proximal end in which is formed a blade receiving slot for the blade and a distal end; an output shaft coupled to the distal end of the blade carrier; a torsion spring for biassing the clamping device from a non-clamping configuration in which the blade is insertable into the blade carrier to a clamping configuration in which the blade is able to be clamped in the blade carrier; a guide groove radially and axially extending from an exterior surface of the blade carrier ( 4 ) and communicating with the blade receiving slot; a locking member pivotally mounted in the guide groove on a pin; and a spiral surface disposed at the proximal end of the rotatable member, wherein the cylindrical rotatable sleeve is manipulable rotationally to the non-clamping configuration whereat the aperture is aligned with the blade receiving slot for inserting the blade into the blade carrier and wherefrom the cylindrical rotatable sleeve is biased back to the clamping configuration by the torsion spring whereat the aperture is non-aligned with the blade receiving slot so as to cause said proximal end of said rotatable sleeve to engage the blade and the spiral surface positively engages a curved surface of the locking member giving the locking member a tendency to rotate about the pin thereby causing the locking member to positively engage the blade in the blade carrier.