| 摘要 |
In a spraying gap (7), reduced pressure is produced by compressed air supplied (1) to a nozzle through a tube. Into the gap a powder suspension is discharged. This is induced through suction openings, from a fluidized powder bed. At the gap, the suspension is atomized to a cloud of powder. Conductive electrodes (8) are connected to high electrical potential (11). Thus a cloud of powder is charged electrostatically. Charged powder particles deposit on to an object immersed in the cloud. An Independent claim is included for corresponding equipment. Preferred features: A dilute fluidized powder layer at a low height of e.g. 10 cm is induced basally through a suction funnel using little air. The suspension is charged to /!5-/!15 kV. It passes via powder supply channels in the pipe and is atomized at a baffle, to deposit on the earthed object. The cloud, free of ions, overcomes the Faraday effect and penetrates into the cavity. Charging electrodes (8) and their supply are covered by insulating panels hung completely over the entire wall of the vessel (4), up to the (small) height of the powder layer. They separate the coating zone from the parts at high voltage, increasing safety. In the suction funnel a honeycomb electrode close to the conductive electrode is connected to another high voltage source. It superimposes charge, increasing that of the cloud. Further suction funnels, on pivoting arms with adjustable baffles cover the base. Powder clouds are produced for the sides of the earthed object. Further baffle and honeycomb arrangements are indicated, which reinforce coating. An insulant partition with openings for return flow of powder increases safety. The suction funnel is slowly raised and lowered, achieving a more dense charged powder cloud. The vessel is made of non-combustible material e.g. TROVICEL 200 (RTM).
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