Patent Application
20060177280
The invention relates to a fluidizing unit for a powder conveyor and a powder conveyor for conveying powder required for coating with a fluidizing unit. In order to be able to convey the powder required for coating—which hereinafter shall be called powder in short—more easily from a powder storage reservoir, the powder conveyor is equipped with a fluidizing unit. The fluidizing unit is arranged at the end of the powder suctioning pipe of the powder conveyor and blows fluidizing air into the powder reserve in the suction area of the powder suctioning pipe so that the powder is fluidized and as a result is more easily suctioned and transportable.
A powder conveying device with a fluidizing unit is known from the state of the art U.S. Pat. No. 6,398,462 B1. The powder conveyor described there has a powder suctioning pipe, at whose inlet-side end the fluidizing unit is arranged. This unit includes a fluidizing ring consisting of a porous, air-permeable material, through which fluidizing air is blown directly at the inlet of the powder suctioning pipe into the powder. The fluidizing ring has a conical area for this purpose on its inside, through which the fluidizing air escapes from the fluidizing ring. While the powder suctioning pipe covers the inner shell side of the fluidizing ring, the outer surface area of the fluidizing ring is surrounded by an airtight locking housing, which is simultaneously used for the holding the fluidizing ring. The fluidizing air is consequently forced to escape on the conical inside of the fluidizing ring. However the described fluidizing unit has the disadvantage that only the part of the powder, which is directly below the powder suctioning opening, is fluidized. This can lead to the fact that the part of the powder reserve, which laterally surrounds the powder suctioning pipe, does not continue flowing or does not sufficiently continue flowing to the powder suctioning opening. In order to counteract that, the fluidizing air quantity must be then increased, what leads to a reduction of the powder suctioning capacity of the powder conveyor, because more fluidizing air is sucked in.
A powder conveying device with a fluidizing unit is also known from the state of the art DE 295 18 478 Ul. The fluidizing unit is arranged at the end of the powder conveying head immersed into the powder reserve. In operation, the fluidizing air flows through a porous disk and escapes from the area of the porous disk. The powder suctioning openings, however, are in the upper area of the powder conveying head and as a result arranged above the fluidizing disk. Such an embodiment has the disadvantage that as soon as the powder reserve in the powder storage reservoir sinks below a certain level, no more powder can be sucked in from the powder conveyor, because the powder suctioning openings at the powder suctioning head are not arranged sufficiently far below.
An object of the invention is to provide a fluidizing unit for a powder conveyor and a powder conveyor with fluidizing unit with which a sufficiently large quantity of powder can also be fluidized with a low fluidizing airflow.
With the embodiment of the fluidizing unit according to the invention, a big umbrella-shaped fluidizing of the powder can be reached, what on the other hand leads to an even and homogeneous fluidizing of the powder in and around the area of the powder suctioning opening. In that way, relatively lot of powder is fluidized with relatively less fluidizing air.
Advantageously it can be achieved, using the fluidizing unit according to the invention, that the powder conveyor still smoothly conveys the powder even on the base of the powder storage reservoir.
The object is solved by a fluidizing unit for a powder conveyor with the characteristics according to claim 1.
The fluidizing unit according to the invention for a powder conveyor has a powder suctioning opening, a powder suctioning canal and a fluidizing ring, in which case the fluidizing ring is arranged above the powder suctioning opening and concentrically to the powder suctioning canal. Moreover the fluidizing unit has fixing means for holding the fluidizing ring, which are developed in a way that the outer surface area of the fluidizing ring remains at least partially free.
In addition, the object is solved by a powder conveyor for conveying coating powder with the characteristics according to claim 9 together with the characteristics stated above.
Advantageous further developments of the invention result from the characteristics stated in the dependent claims.
In a first further development of the fluidizing unit according the invention for a powder conveyor, the fluidizing unit has an air-permeable material.
In a second further development of the fluidizing unit for a powder conveyor, an annular fluidizing air canal is provided, to which the fluidizing ring connects on the outlet side. This ensures that the fluidizing ring is evenly supplied with fluidizing air.
Advantageously the fixing means of the fluidizing unit according to the invention for a powder conveyor have an annular stopper and a crown, between which the fluidizing ring is arranged.
Furthermore it is of advantage, if the crown has several spacers in the fluidizing unit according to the invention. This prevents that the packaging foil, in which the powder reserve is kept, is suctioned.
In another embodiment of the fluidizing unit according to the invention, it is provided that the crown can be screwed on the powder suctioning canal. This has the advantage that the fluidizing ring can simply be replaced by first unscrewing the crown from the powder suctioning canal and subsequently removing the fluidizing ring.
According to another characteristic of the invention, the fluidizing ring can include several segments. As a result the crown must not be completely unscrewed in order to be able to replace the fluidizing ring, but it suffices to loosen the crown a bit. Then the individual segments of the fluidizing ring can be pulled out laterally.
Furthermore it is of advantage, if in the case of the fluidizing unit according to the invention for a powder conveyor, the crown has the powder suctioning openings.
Finally, the powder conveyor according to the invention can have a powder injector working with compressed air for conveying coating powder.
These and other aspects of the invention are apparent from and will be elucidated in details with reference to two figures described hereinafter.
The upstream end of the powder conveying pipe 3 and the fluidizing unit 4 are represented in a section in
The fluidizing ring 5 has an air-permeable material. It can be produced from air-permeable synthetic material, as for example polyethylene, in sintering process or consists of porous structures from metal balls with hollow spaces or has one of these materials. The fluidizing ring 5 can also be composed of several segments.
The arrangement of the fluidizing ring 5 above the powder suctioning opening 11, as this is shown in
The spacers 6.2 of the crown 6 have also the advantage that a simple, oblong tool, for example a screwdriver, can be put into the recesses between the spacers 6.2, with whose help the crown 6 can be then unscrewed without great effort.
The preceding description of the embodiments according to the present invention is used only for illustrative purposes and not for the purpose of restricting the invention. Different alterations and modifications are possible within the framework of the invention without leaving the scope of the invention and its equivalents.
| Number | Date | Country | Kind |
|---|---|---|---|
| 20 2005 001 307.2 | Jan 2005 | DE | national |
