Gravimetric blender with power hopper cover

A method for separating a gravimetric blender hopper cover that supports equipment for feeding resin material into the hoppers, from the hoppers for cleaning, material changeover, the cover being planar and horizontally oriented, the hoppers supplying components of plastic resin to a weigh bin portion of the blender, a load cell of the blender continuously weighing the weigh bin and plastic resin components deposited therein, 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 components has been reached into a mixing chamber, and blending the plastic resin material components prior to injection or compression molding or extrusion thereof, comprising;

• a) pneumatically actuating a pair of vertically extendable piston-cylinder combinations having the cylinders mounted on the hopper cover and the piston rods extending vertically downward and slideably through the cover for advancing the hopper cover vertically away from the hoppers along a vertically extending telescoping guide having a guide rod slideably telescoping into a tube with the cover being fixedly connected to the guide rod to a position at which the cover is sufficiently remote from the hoppers that a worker can access the coverless hoppers and disconnect the hoppers from a frame portion of the gravimetric blender, the guide rod being fixed to the cover proximate the center of the cover, the piston rods being spaced from one another and from the guide rod on either side of the guide rod, while
• b) restraining the hopper cover in a horizontal orientation by three point support provided by the two piston rods and the telescoping guide rod to continue support of the equipment for feeding resin material into the hopper.

A method for raising and lowering a planar cover for the hoppers of a gravimetric blender for hopper cleaning, material changeover and the like, the cover supporting a vacuum loader or other equipment for feeding resin material into the hoppers, the hoppers supplying components of plastic resin by gravity flow to a weigh bin portion of the blender positioned below the hoppers, a load cell of the blender continuously weighing the weigh bin and plastic resin components dropping thereunto due to gravity as valves open and close resin discharge openings at the bottom of 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 components has been reached in the weigh bin, and blending the preselected weight of plastic resin material components prior to injection or compression molding or extrusion thereof, comprising:

• actuating a pair of vertically oriented piston cylinder combinations, the cylinders of which are connected to and on the top of the cover and the pistons of which extend vertically slideably through nut-bushing combinations in the cover into receptacles connected to a frame of the gravimetric blender, thereby advancing the hopper cover upwardly from a position covering the hoppers along a telescoping vertical guide having a guide rod slideably telescoping into a tube, and with the piston rods being spaced from each other and positioned on opposite sides and being spaced from the vertical guide rod, the piston rods and the vertical guide rod being horizontally aligned, the spaced alignment of the guide and piston rods preventing tilting of the cover, with the cover being horizontal, fixedly connected to the rod, and extending transversely with respect thereto, to a position at which the cover is sufficiently remote from the blender that the requisite blender cleaning, material changeover and the like can be performed, while maintaining the hopper cover in a horizontal orientation by fixed connection to the guide rod to continue supporting the vacuum loader or other equipment for feeding resin material into the hopper.

A method for temporarily sparingly separating a planar, horizontally oriented cover from the hoppers of a gravimetric blender, the hoppers of the blender supplying components of plastic resin by downward, gravity induced flow to a weigh bin portion thereof, a load cell of the blender continuously weighing the weigh bin and plastic resin components deposited therein, 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 components has been reached into a mixing chamber, and blending the plastic resin material components prior to injection or compression molding or extrusion thereof, the planar cover supporting equipment for feeding material into the hopper, to facilitate access to the hopper for cleaning, material changeover and the like, comprising:

• a) advancing the cover along a two-piece telescoping vertically extending guide, one of the telescoping pieces having the cover fixedly connected thereto, away from the hopper by application of force to pistons of a piston-cylinder combinations, each of the cylinders being affixed to the cover and each of the pistons being connected to the blender and passing slideably through the cover, the pistons moving vertically respecting the cylinders and parallel with the guide, to a position at which the cover is sufficiently separated from the hopper that a worker can access the coverless hopper, while maintaining the hopper cover in a horizontal orientation continuing support of equipment thereon for feeding material into the hopper.

A method for separating a planar horizontally elongated cover from the hoppers of a gravimetric plastic resin material blender, the hoppers supplying components of plastic resin to a weigh bin portion thereof, a load cell of the blender continuously weighing the weigh bin and plastic resin components deposited therein, the blender emptying the weigh bin of the plastic components into a mixing chamber of the blender once a preselected weight of the bin and components has been reached, and blending the plastic resin material components prior to injection or compression molding or extrusion thereof, the cover supporting equipment for feeding material into the hopper, to space the cover from the hopper in order to facilitate cleaning, material changeover, comprising:

• a) Actuating a pair of piston-cylinder combinations, the cylinders being mounted on the cover, and the pistons passing through the cover and being connected to the blender frame, the pistons being horizontally aligned with and space from the vertical guide, the pistons being on opposite sides of the guide and thereby pneumatically vertically advancing the cover along a two-piece telescoping vertically extending guide, one of the telescoping pieces having the cover fixedly connected thereto, away from the hopper to a position at which the cover is separated from the hopper for worker access to the hopper interior, while maintaining the hopper cover horizontal for supporting equipment thereon for feeding material into the hopper by continued actuation of the pistons.