JP4421349B2 - Powder feeder - Google Patents

Description

  The present invention relates to a powder supply apparatus that can uniformly take out powder, particularly fine powder of 10 μm or less, without lump and supply it to a spraying apparatus.

As shown in FIG. 4, the electrostatic coating apparatus accommodates the powder paint 14 in a fluid tank 11 to which fluid air is supplied from the bottom porous plate 12, loosens the powder paint in the fluid tank 11, and injectors 15. The suction pipe 13 is inserted into the accumulation layer of the powder paint 14 in the fluid tank 11, and the powder paint 14 is sucked and conveyed to the electrostatic gun 16 so that the powder paint 14 is sprayed on the article A to be coated. .
In such an electrostatic coating apparatus, formation of a smooth coating film without powder coating lump is required, and Patent Document 1 discloses a technique for obtaining a uniform coating film by uniformizing the particle size of the powder coating material. Is also disclosed.

JP 2002-113409 A

By the way, in recent years, the fine skin of the powder coating has been demanded more beautiful skin.
However, the finer the powder is, the more difficult it is to flow in the fluid tank, the powders stick together, more likely to form lumps, and in the case of a fine powder of 10 μm or less such as alumina powder or silica powder, Even if fluid air is supplied from the bottom in the tank, it is as if the powder layer is filled with water on the bottom.
In particular, in the case of alumina powder having a size of 1 μm or less, not only does it flow in the fluid tank, but it naturally forms lumps and is easily generated on the surface of the object to be coated.
In such a case, even if you try to strengthen the flowing air from the bottom and flow the powder in the fluid tank, it will only flow in the state where the powder layer on the stagnated bottom is open with air holes. Sex is difficult to improve.

  Therefore, the present invention is intended to provide a powder supply apparatus that can draw out powder from a fluid tank without a lump even if it is a fine powder, and that can be uniformly dispersed on an object to be coated.

  According to the present invention, a powder take-out port is provided at the top of a fluid tank that contains powder and is supplied with fluid air from the bottom surface, and the powder is raised to a height position embedded in the powder layer accumulated on the bottom surface of the fluid tank. An air jetting means for making the atomized state is provided, and the atomized powder is taken out from the powder take-out port by the air pressure in the fluid tank.

As the air ejection means, it is possible to use a plurality of air ejection holes and air ejection slits formed on an air tube disposed along the inner peripheral wall of the fluid tank.
The air ejected from the air ejection holes and the air ejection slits is supplied so as to intersect with the flowing air on the bottom surface of the fluid tank, and as a result, the powder accumulated on the bottom surface of the fluid tank rises and becomes atomized. The air pressure in the fluid tank rises in accordance with the amount of air supplied into the fluid tank, and the air pressure in the fluid tank can take out the powder in an atomized state from the powder outlet of the fluid tank.

  Further, by providing a second air ejection means similar to the air ejection means installed in the powder layer on the bottom surface of the fluid tank at the top of the fluid tank filled with the atomized powder, the fine powder is further agglomerated. It can be in a state without.

  Then, an injector device that performs air conveyance may be provided at the powder extraction port of the fluid tank, and the powder may be conveyed to the spraying device. Since it flows out, the powder without a lump can be supplied to a spreading device as it is.

  As described above, according to the present invention, since the powder without atomized lump can be supplied to the object to be coated, even with a fine powder of 10 μm or less, it is possible to form a uniform coating film with extremely few irregularities. Is possible.

FIG. 1 is a schematic view showing a first embodiment of a powder supply apparatus according to the present invention.
The fluid tank 1 has a cylindrical shape with an inner diameter of 400 mm and has an inner bottom plate 2 formed of a perforated plate, and fluid air 3 flows into the tank from the lower surface side of the inner bottom plate 2. The powder layer 4 accumulated on the inner bottom plate 2 accommodated in the container is prevented from being hardened by the flowing air 3.

In the fluid tank 1, air jetting means 5 is provided at a height position buried in the powder layer 4 accumulated on the inner bottom plate 2 so as to cause the powder to rise to an atomized state. This air jetting means 5
The two air tubes installed along the inner surface of the tank are provided with a plurality of air ejection holes 5a for ejecting air so as to intersect with the flowing air. By the ejecting air intersecting with the flowing air, the powder layer No. 4 powder soars and becomes atomized powder.

  In this embodiment, an air tube having a diameter of 8φ is used, and the air ejection holes are 0.5 mm in diameter and are opened at equal intervals of 30 mm.

  In addition, an air ejection means 6 similar to the air ejection means 5 is also installed along the inner surface of the fluid tank 1 filled with the atomized powder. The air jetting means 6 is provided with a plurality of air jetting holes 6a for jetting air on an air tube installed along the inner surface of the tank. The powder is further dispersed to prevent the formation of a lump of powder.

  The air tubes of the air ejection means 5 and 6 are preferably provided along the inner surface of the tank, but the position may be a position from the center.

  In the upper part of the fluid tank 1, a powder outlet 7 is installed, and the air pressure in the fluid tank 1 rises according to the flowing air and the amount of air inflow from the air ejection means 5, 6. From the fluidized tank 1 flows out of the fluid tank 1.

  The atomized powder that has flowed out of the fluid tank 1 is conveyed to the electrostatic gun 9 via the hose 8 and dispersed on the article A to be coated.

Using the powder supply apparatus according to the first embodiment, a dispersion experiment of alumina powder having an average particle diameter of 1 μm was performed.
When only air from the bottom surface is supplied into the fluid tank 1 without air from the air ejection means 5 and 6, the powder layer 4 seems to have water on the bottom surface even at an air pressure of 0.1 Mpa. The state remained. When this air pressure is further increased, the powder layer 4 can only have a large number of needle-like air holes, and the powder layer 4 remains in a state where water is stationary, and the powder flows out from the powder outlet 7. No, the powder could not be sprayed on the article A to be coated by the electrostatic gun 9.
Next, when air was ejected from the air ejection means 5 and 6 at an air pressure of 0.1 Mpa to 0.15 Mpa, the flow state of the powder layer 4 gradually became active, and the powder of the powder layer 4 became muddy and misty. The fluid tank 1 is filled with mist-like powder, and the air pressure in the fluid tank 1 causes the atomized powder to flow out of the fluid tank 1 through the hose 8 as it is. It was conveyed to the electric gun 9 and powder could be sprayed on the article A to be coated.
As a result of visually confirming the coating film of the object A spread as described above, the occurrence of scum remaining on the coating film of the object A is as shown in Table 1 and the ejection of air from the air ejection means 5 and 6 It was decreasing according to the amount.
Table 1 shows the average value of 10 times when the setting of flowing air and air from the air jetting means 5 and 6 is performed with the target adhesion amount set to 50 mmg for the object A of 200 mmH × 300 mmL. It is a thing.

  Next, Table 2 used air jetting means 5 and 6 having an 8 mm diameter air tube with a 0.3 mm cutter and a vertical 5 mm air jet slit perpendicular to the tube length.

  The powder used was a three-time recycled powder of a polyester powder coating material containing 55% having a particle size of 5 μm or less.

  In Table 2, the setting of flowing air and air from the air jetting means 5 and 6 is performed with a target adhesion amount of 30 μm thickness on the object A of 200 mmH × 300 mmL, and the average value of 10 times showed that.

  In the above embodiment, the atomized powder is conveyed to the electrostatic gun 9 as it is by the air pressure supplied into the fluid tank 1, but as shown in FIG. The injector 10 may be installed, and the powder may be pumped to the electrostatic gun 9 by forced suction by the injector 10, but in this case, as shown in FIG. B is easy.

(A) is the schematic of 1st embodiment of this invention, (b) is a top view of an air tube. It is the schematic of 2nd embodiment of this invention. It is explanatory drawing of the injector part of embodiment of FIG. It is the whole electrostatic coating apparatus schematic.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Fluid tank 2 Inner bottom board 3 Fluid air 4 Powder layer 5, 6 Air ejection means 5a, 6a Air ejection hole 7 Powder extraction port 8 Hose 9 Electrostatic gun 10 Injector

Claims (6)

  A powder take-out port is provided in the upper part of the fluid tank that contains the powder and fluid air is supplied from the bottom. An apparatus for supplying powder, characterized in that an air jetting means is provided, and the atomized powder is taken out from the powder outlet by air pressure in a fluid tank.   The powder supply apparatus according to claim 1, wherein a plurality of air ejection holes are formed in an air tube arranged along the inner peripheral wall of the fluid tank to constitute the air ejection means.   2. The powder supply apparatus according to claim 1, wherein a plurality of air ejection slits are formed in an air tube arranged along the inner peripheral wall of the fluid tank to constitute the air ejection means.   The powder supply apparatus according to any one of claims 1 to 3, wherein a second air blowing means is provided in an upper part of the powder flow tank.   The powder supply apparatus of any one of Claims 1-4 which provided the injector apparatus which performs air conveyance in the powder extraction opening of a fluid tank.   The powder coating apparatus which takes out powder with the powder supply apparatus in any one of Claims 1-5, and supplies it to a dispersion device.

Images