Abstract: A follower travels the inside contour of a rotating eyeglass frame and the movement caused by changing radii is detected by a linear variable differential transformer and converted into electrical signals which actuate an electrically operated valve. The valve, in turn, controls the movement of a hydraulic cylinder which dictates the positioning of a lens blank to be edged relative to the grinding periphery of an abrading wheel taking into account the position of the lens edge on the abrading surface.
Abstract: Disclosed is a system for blocking an ophthalmic lens blank by means of a vacuum. The lens blank rests on the chuck and forms an air pocket or cavity therebetween which is evacuated by means of a vacuum pump. After evacuation, an elastic plug is inserted in an aperture in the chuck by atmospheric pressure to maintain the vacuum. The lens is disengaged from the chuck by peeling the plug back and thereby releasing the vacuum.
Abstract: Disclosed is a system for blocking an ophthalmic lens blank by means of a vacuum. The lens blank rests on the chuck and forms an air pocket or cavity therebetween which is evacuated by means of a vacuum pump. After evacuation, an elastic plug is inserted in an aperture in the chuck by atmospheric pressure to maintain the vacuum. The lens is disengaged from the chuck by peeling the plug back and thereby releasing the vacuum.