초록 ▼

The apparatus for applying granules to a coated asphalt sheet has a nozzle for holding an accumulation of granules, an opening at the bottom of the nozzle for discharging the granules onto the coated asphalt sheet, a buffer chamber positioned in communication with the accumulation of granules, and a

The apparatus for applying granules to a coated asphalt sheet has a nozzle for holding an accumulation of granules, an opening at the bottom of the nozzle for discharging the granules onto the coated asphalt sheet, a buffer chamber positioned in communication with the accumulation of granules, and a vacuum source for reducing the pressure in the buffer chamber to stop the flow of granules through the opening.

대표청구항 ▼

[ We claim:] [1.] Apparatus for applying granules to a coated asphalt sheet comprising;a nozzle having an upper region for holding an accumulation of granules having a top surface and an opening at the bottom of the nozzle for discharging the granules onto the coated asphalt sheet, wherein the nozzl

[ We claim:] [1.] Apparatus for applying granules to a coated asphalt sheet comprising;a nozzle having an upper region for holding an accumulation of granules having a top surface and an opening at the bottom of the nozzle for discharging the granules onto the coated asphalt sheet, wherein the nozzle is wider at its upper region than at the nozzle opening;a buffer chamber positioned above the nozzle in communication with the top surface of the accumulation of granules so that a negative pressure in the buffer chamber provides an upwardly oriented drag force on the granules in the accumulation of granules;a hopper for supplying granules to the nozzle, the hopper having a throat for feeding granules to the accumulation of granules, wherein the hopper extends upwardly away from the buffer chamber and the nozzle, and is adapted to receive granules as a downwardly moving flow and to supply the granules to the accumulation of granules in the nozzle; andvacuum means connected to the buffer chamber for reducing the pressure in the buffer chamber to stop the flow of granules through the opening, wherein the vacuum means creates an upward flow of air through the granules at the opening, the upward flow of air being sufficient to prevent the granules from flowing down through the nozzle opening by gravity, but insufficient to create fluidization of the granules at the opening.