The IP.com Prior Art Database
A rotary sieve having a cantilever mounted shaft for rotating a rotor within a sieve screen The sieve screen may be installed with a cartridge configuration without having to remove the rotor or remove a bearing that supports the shaft A sieve housing is provided in the form of a shroud that can be easily removed for cleaning and access to the sieve interior The rotary sieve may be used to receive direct powder feed from a dense phase pump or gravity fed Methods for color change and cleaning the sieve are also disclosed
Powder Sieve For Color Change And Method To Clean Sieve
Field of the Inventions
disclosure relates generally to the art of sieving powdered and other
particulate material. More particularly,
the disclosure and inventions herein relate to a rotary sieve which may be
used, as one example, to sieve powder coating material.
Background of the Disclosure
industries, it has become common practice to apply paints and other coatings to
products in the form of dry particulate powder.
Powder coatings offer a number of advantages over traditional liquid
coatings and paints, among them are lower cost, reduced pollution, shorter
curing times and improved physical properties.
materials are applied to workpieces by spraying. The powder is drawn from a container or
hopper by a pump, fed through hoses to one or more spray guns and sprayed
towards the workpiece by means of pneumatic force. Powder coating application is also commonly
although not exclusively done with electrostatic spray guns in which the
workpiece is held at one electrical potential or polarity, such as ground for
example, and the powder is electrostatically charged to an opposite polarity
such as by using a negative voltage. The
electrostatic charge may be applied to the powder coating particles by an
electrode. Powder coating systems may
use virgin powder which has not been sprayed previously, or may reclaim and
re-spray powder overspray.
may be pumped from a container or hopper in two basic forms, in dense phase or
dilute phase. In a dense phase system, the
amount of air that is mixed with the powder in order to transport the powder
from a pump to the spray gun is substantially reduced as compared to a dilute
phase system, thus providing a high powder to air ratio or in other words a
powder rich mixture. In a dilute phase
system, a large volume of air is used to push the powder from a Venturi pump to
the spray gun, thus providing a low powder to air ratio or in other words a
powder lean mixture.
material is typically sieved prior to being pumped to a spray gun. Using sieved powder typically improves the
overall efficiency of the application process and the overall appearance and
finish of the product. Sieving may be
done on both virgin powder as well as reclaimed powder.
In terms of
overall system efficiency, in addition to the pumps, spray booth, hoses and
spray guns, a rotary sieve represents another component that must be purged or
cleaned for each changeover of material, such as for example, a color change. Known sieves to date, including vibratory
deck sieves and rotary sieves, are time consuming to clean and therefore
represent a significant inefficiency in terms of being able to use a coating
material application system for long run large volume coating operations or
frequent changeover short run coating operations.
of the Disclosur...