Conveyors: fluid current – Intake to fluid current conveyor – Load receptacle type
Patent
1995-11-21
1998-11-17
Pike, Andrew C.
Conveyors: fluid current
Intake to fluid current conveyor
Load receptacle type
406 61, 406138, 198657, 198952, 2221466, B65G 5348
Patent
active
058367225
DESCRIPTION:
BRIEF SUMMARY
The invention concerns a feed method and device for a powdered product projection plant, notably a coating product in powder form. It concerns also a projection plant for such a powdered product.
In numerous industrial applications, the powdered product, normally termed "powder", is led from a product reservoir to its point of use, for example a sprayer of the pneumatic or centrifugal type. The powder is entrained by an air jet in a conduit having a substantial length, often convoluted and of relatively small diameter.
It is essential that the feeding of powder be continuous, homogenous, and stable during an extended period and regulatable with precision and rapidity. For this purpose, one can use an aspiration device of the Venturi type. One can also use a worm screw or an Archimedes screw mounted at the bottom of a hopper, ending at a nozzle supplied with entrainment air by an injector. Such a system presents advantages with respect to a powder aspiration device, notably because of the regularity of the mass flow of powder despite variable pressure losses.
The powders utilized are generally intended to be baked at around 180.degree. C. after having been applied. Now, it has been noted that this baking phase causes yellowing of certain powders. New powders which have recently been developed which require a baking at no more than 140.degree. C. This permits resolution of the problem of yellowing but introduces a supplemental limitation because these powders experience rapid alteration at ambient temperature. They must be stored at low temperatures, preferably between 5.degree. C. and 10.degree. C. In addition, the polymerization point of these powders is low and they are liable to polymerize at points where the temperature has a tendency to be elevated, such as, for example, around the worm screw of a mechanical entrainment system. It is necessary to retain in the reservoir only the powder consumed during a period less than that beyond which the powder deteriorates. This requires frequent fillings of the reservoir.
The powder must traverse a relatively long trajectory, of the order of 10 meters for example, in the conduit situated between the feeding device and the sprayer with which it is associated. Friction in this conduit can raise the temperature of the powder and deteriorate it or cause it to polymerize.
In addition, if the device is halted at the end of a work day or at the end of a week, the reservoir and the associated drive system of necessity contain remains of powder. They must be completely emptied of powder and this latter must be stored in a cool and dry place such as a refrigerator during the period of stoppage of the installation. It is imperative to clean the reservoir and the worm screw very carefully because, if powder remains therein during a prolonged period, there is a risk that it will be degraded or agglutinated, for example along the worm screw, which would be troublesome during restarting of the device. This require operations which are long, difficult, and frequent.
One of the essential advantages of coating with a powdered product is that the product which has not reached the target, i.e. the object to be painted, can be recycled by an appropriate device for recovering the powder in the booth and a device for transporting this recovered powder toward the powder feed device of the installation where it is mixed with new powder. Now, the powder undergoes heating during spraying; if its temperature at the outlet of the feed device is too high, there is thus a risk that it will not be recoverable. In addition, there is a risk that the recovered powder will raise the temperature of the new powder during mixing, even if this latter has been stored in a refrigerator until the moment when it is poured into the reservoir of the feed system.
The invention resolves the totality of these problems.
It concerns a feed method for a powdered product projection plant such as particularly a powdered coating product characterized in that the product is cooled at the interior of the product feed d
REFERENCES:
patent: 1450903 (1923-04-01), Newhouse
patent: 4183702 (1980-01-01), Bonnel
patent: 4488838 (1984-12-01), Herud
patent: 4691865 (1987-09-01), Hoffman et al.
patent: 4759500 (1988-07-01), Hoffman et al.
patent: 4826361 (1989-05-01), Merz
patent: 5061510 (1991-10-01), Nussbaumer et al.
patent: 5209608 (1993-05-01), Edwards
Patent Abstracts of Japan, vol. 9, No. 287 (C-314) 14 Nov. 1985 of JP,A,60 132 632 (Matsushitas Denki Sangyo KK).
Patent Abstracts of Japan, vol. 14, No. 439 (C-761) 19 Sep. 1990 of JP,A,02 172 551 (Babcock Hitachi).
Pike Andrew C.
Sames S.A.
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