New fluidized bed powder supply bucket for the hot

New fluidized bed powder supply bucket for high-voltage electrostatic powder coating

New fluidized bed powder supply bucket for high-voltage electrostatic powder coating

March 29, 2004

high voltage electrostatic powder coating is one of the common coating methods today, and the powder supply bucket is one of the key equipment for high-voltage electrostatic powder coating equipment. This paper, published by the senior engineer of the technical support department of Xianghe coating phosphating (Chengdu) headquarters, introduces an improved fluidized bed powder supply bucket, including the basic principle, structure, process parameters, etc

powder electrostatic spraying is inseparable from spray guns, high-voltage electrostatic generators, powder supply barrels and other equipment, of which the powder supply barrel is one of the key equipment to transport powder

to the spray gun. In the past, the domestic general effect was ideal, and the backward suction powder supply barrel was widely used. Although measures such as electric

magnetic oscillator and mixing in the barrel were added, the blockage of venturi and uneven powder discharge were still the main problems, which seriously affected the spraying efficiency and surface spraying quality

after changing to a new type of fluidized bed powder supply bucket, the original situation has been greatly improved. It can continuously and uniformly supply powder to the spray gun in a fixed amount. In terms of feeding, it is easy to realize the advantages of mixing new powder and recycled powder, which is an ideal powder supply

2 basic principle

when an air flow passes through the venturi microporous plate, the powder on the microporous plate will appear the following situations. When the air velocity decreases

, the fluid just passes through the gap between stationary particles, and the powder does not move. With the increase of the air velocity, the particles

leave each other, and a small number of particles vibrate and swim to test the strength separation of coil springs and elastic elements. When the air flow speed increases, all particles will be suspended in the upward

flowing gas. At this time, it will be in a fluidized state. The outside of the powder supply barrel is connected with a venturi powder conveying pipe, and the powder will be conveyed to the

spray gun to spray the workpiece

3 basic requirements of fluidized bed powder supply bucket

(1) in the spraying process, it is required that the powder is evenly and stably discharged to maintain uniform coating thickness

if these table files are lost

(2) the venturi is not easy to be blocked to maintain the continuity of powder supply

(3) the feeding requirements are convenient, the structure is simplified, and the use is reliable

4 structure of fluidized bed powder supply bucket

fluidized bed powder supply bucket mainly includes fluidization bucket, gas chamber, microplate, venturi nozzle, powder conveying pipe, etc

4.1 the fluidized bed

is a rectangular barrel or a circular barrel. The outline dimension of rectangular barrel is 560 × three hundred and eighty × 380mm； The overall dimension of the circular barrel is

φ four hundred and fifty × 500mm, filled with powder for powder supply, with a capacity of 40kg. According to the test results, the injection pressure is 0.01 -

0.15mpa, and the diameter of Venturi nozzle φ 1.5mm； The diameter of the shrinkage hole of the powder collecting nozzle is φ When 5mm, epoxy/polyester powder

powder is used, and the powder supply rate is 4 ~ 5kg, it can be sprayed continuously for 8h without powder

4.2 air chamber

the function of the air chamber is to disperse and equalize the purified compressed air from the centralized state and rise evenly. In order to achieve the purpose of

, the intake pipe is designed into an annular porous structure, which is distributed below the annular pipe φ 5mm dense holes, the air flow is ejected and reflected upward through the small

holes, which improves the uniformity of the air flow

4.3 microporous plate

microporous plate is an important component of fluidized bed structure, which directly affects the market range of trillions of yuan from powder fluidization to the end of "1035". The pore size of microporous plate

is equal to the average size of powder particles

the main technical requirements for microplates are: ① uniform and dense ventilation; ② High mechanical strength; ③ It is not easy to bond to powder

the microplate produced by Guangzhou Institute of electrical science was selected

4.4 venturi nozzle

three kinds of Venturi nozzles were tested, and finally the venturi nozzle with the structure shown in Figure 2 was selected

, and the powder in the powder supply bucket is collected into the shrinkage hole of the "mixing

section" of the powder collecting nozzle. After passing through the pressurization section, the air flow containing powder is sent to the spraying place

the new powder supply bucket (see Figure 3) is characterized by simple structure and no moving parts in the whole system; Easy to manufacture,

maintenance and repair. When spraying powder, the powder supply barrel does not need to be sealed, and feeding can be carried out at the same time of powder supply. There is little

powder in the barrel, which is easy to clean and change. Even if only a small amount of powder is used, the spraying test can be carried out

the fluidized bed powder supply barrel has strong adaptability to the pressure of powder supply, and the pressure above 0.01Mpa can supply powder; Within a certain air pressure range, the powder supply is less affected by pressure. By changing the distance between the nozzle and the powder collecting nozzle, the powder supply can be adjusted, and the powder supply accuracy is 5 ~ 15%

4.5 main process parameters of the new powder supply barrel:

powder supply pressure: 0.45MPa fluidization pressure: 0.01-0.03mpa

spray pressure: 0.02-0.06mpa spray pressure: 0.01-0.15mpa

powder supply barrel capacity: 40kg powder supply volume: 4 ~ 8kg/h

the new powder supply barrel has passed the production test for nearly a year, which proves that it can safely meet the requirements of design and production, and is convenient for maintenance; Sealing is not required during operation; Simple feeding; Convenient color change; There is no powder in the barrel; The powder supply is not affected by pressure. Facts have proved that as long as strict scientific production management is strengthened, the normal operation of the electrostatic powder automatic line can be guaranteed, and high-quality products can be produced

the non adsorbed powder ejected from the electrostatic spray gun is collected by the powder collector, screened and returned to the powder supply bucket. At the same time,

add new powders in proportion, mix them evenly, and then reuse them repeatedly