Gravimetric blender with power hopper cover

A method for moving an upwardly and downwardly movable hopper cover of a gravimetric blender, the gravimetric blender receiving granular resin materials, weighing the granular resin materials according to a recipe, and mixing the weighed granular resin material into a homogenous blend, the cover being movable from a position at which the cover contacts and covers upwardly facing opening of the hopper to a position at which the cover is vertically spaced away from the hopper upwardly facing opening, for facilitating cleaning and material changeover within the hopper, the cover being adapted for supporting a vacuum loader for feeding resin material into the hopper, the method comprising:

• a) advancing the hopper cover upwardly from the hopper along a guide by application of pneumatic pressure to a piston-cylinder combination, the cylinder being affixed to the cover and the piston being connected to the blender frame, to a position at which the cover is sufficiently remote from the hopper that a worker can access the now coverless hopper and remove the hopper from the blender frame, while maintaining the hopper cover in orientation to facilitate continued support of a vacuum loader resting on the hopper cover for feeding resin material into the hopper.

In a method for removing a hopper from a gravimetric blender, the gravimetric blender receiving separate individual granular resin materials, weighing the separate individual granular resin materials according to a recipe, and mixing the weighed separate individual granular resin materials into a homogeneous blend, the gravimetric blender having a cover for vertically supporting a vacuum loader for feeding resin material into the hopper, the hopper being removed from the gravimetric blender for cleaning and material changeover, the improvement to the method comprising;

• a) advancing the hopper cover upwardly from the hopper slidably along a path defined by a telescoping guide to a position at which the cover is sufficiently remote from the hopper that a worker can access the coverless hopper and disconnect the hopper from the blender frame, while
• b) pneumatically maintaining the hopper cover in a horizontal orientation while positioned remotely from the hopper to continue support of any vacuum loader resting thereon for feeding resin material into the hopper.

In a method for raising a hopper cover from a gravimetric blender, the hopper cover supporting equipment for feeding resin material into the hopper, for blender cleaning and material changeover, the gravimetric blender receiving separate individual granular resin materials, weighing separate portions of the individual granular resin materials according to a recipe, and mixing the weighed separate portions of the individual granular resin materials into a homogeneous blend, the improvement to the method comprising:

• a) advancing the hopper cover upwardly from the hopper along a predefined path defined by an upwardly oriented guide connected to the blender frame, to a position at which the cover is sufficiently remote from the hopper that blender cleaning and material changeover can be performed, while maintaining the hopper cover in a horizontal position to continue supporting the equipment for feeding resin material into the hopper;
• by applying pressure to piston-cylinder combinations, affixed to the cover and to the blender frame thereby moving the hopper cover upwardly along the guide path in response to pressure applied to the cylinder of the piston-cylinder combination.

In a gravimetric blender including a hopper and a hopper cover, the gravimetric blender receiving separate individual granular resin materials, weighing portions of the separate individual granular resin materials according to a recipe, and mixing the weighed portions of the separate individual granular resin materials into a homogeneous blend, the improvement comprising:

• a) pneumatic means for moving the hopper cover towards and away from the hoppers;
• b) means for guiding the hopper cover upwardly along a predefined path during movement thereof while maintaining the cover in a fixed orientation relative to the hopper during cover movement.

In a gravimetric blender having hoppers and a hopper cover, the gravimetric blender receiving separate individual granular resin materials, weighing portions of the separate individual granular resin materials according to a recipe, and mixing the weighed separate portions of the individual granular resin materials into a homogeneous blend, the improvement comprising:

• a) telescoping means for vertically guiding the hopper cover during movement thereof relative to the hoppers.