Patent ID: 8092070

Claim:
A method for vertically moving a gravimetric blender hopper cover upwardly away from the hopper open tops for changing the hoppers, and for cleaning the hoppers, the blender supplying components of plastic resin from the blender hoppers to a weigh bin portion thereof, a load cell of the blender continuously weighing the weigh bin and plastic resin components deposited therein by gravity flow from the hoppers, the blender emptying the weigh bin of the plastic components into a mixing chamber portion of the blender once a preselected weight of the bin and resin components has been reached, downwardly into a mixing chamber, and blending the plastic resin material components prior to injection or compression molding or extrusion thereof, with the cover vertically supporting a vacuum loader or other equipment for feeding resin material into the hopper, comprising: advancing the hopper cover upwardly from the hopper along a telescoping vertical guide having a vertical rod slideably telescoping into a vertically oriented guide tube, the rod being fixed to the hopper cover with the hopper cover extending horizontally respecting the rod and the tube being fixed to the blender, by application of pneumatic pressure to pistons of a pair of piston-cylinder combinations, the cylinder of each of the piston-cylinder combinations being affixed to the cover and the piston of each of the piston-cylinder combinations passing slideably through the hopper cover and being connected to a frame portion of the gravimetric blender, the pistons of the piston-cylinder combinations moving vertically, being horizontally oriented with respect to one another and being parallel to the vertical guide and spaced therefrom, to a position at which the cover is sufficiently remote from the hoppers that a worker can access the coverless hoppers and remove the hoppers from the blender frame, while maintaining the hopper cover in a horizontal orientation, as a result of the horizontally extending hopper cover being fixed to the guide rod and the piston rods passing slideably through nut-bushing combinations mounted in the cover, to continue support by the cover in a horizontal position of the vacuum loader or other equipment resting thereon for feeding resin material into the hopper.