JP5665394B2 - Powder conveying device - Google Patents

Description

  The present invention relates to a powder conveying device that sucks powder paint from a powder paint tank and supplies it to a powder coating gun, for example.

  Conventionally, this type of powder conveyance device includes an injector that sucks powder from a powder tank and performs air conveyance of the powder from a discharge port via a conveyance hose.

  The injector has a main air nozzle connected to a compressed air source via a flow restrictor, and the main air supplied from the main air nozzle generates a negative pressure in the injector body. This is a device that sucks powder from a tank and discharges powder together with main air from a discharge port.

  By the way, the powder discharged from the injector main body is transported in the transport hose by the main air. In order to supply stable transport air into the transport hose, the injector is supplied with a compressed air source through a flow restrictor. In general, a sub-air nozzle that is connected to each other and supplies sub-air together with main air into the transport hose is commonly used (Patent Documents 1 and 2).

JP 2002-273282 A JP 2006-102708 A

  By the way, the total amount of air discharged from the powder coating gun needs to be increased or decreased in accordance with the coating conditions such as the uneven shape of the object to be coated and workability.

  The total amount of air discharged from the powder coating gun is the sum of the main air amount and the sub air amount. The volume and sub air volume are adjusted.

  For example, when painting is performed at a main air amount of 60 l / min, a sub air amount of 40 l / min, and a total air amount of 100 l / min, the total air amount is reduced by 10% depending on the conditions of the object to be coated and the conveyance hose. In this case, control is performed to adjust the opening degree of the flow restrictor by the controller so that the main air amount and the sub air amount are respectively reduced by 10%.

  That is, the main air amount is adjusted from 60 l / min to 54 l / min of 90%, the sub air amount is adjusted from 40 l / min to 90 l of 36 l / min, and the total air amount is 90% of 100 l / min. It is set to 90 l / min.

  However, when such adjustment of the total air amount is performed, even if the total air amount can be optimized to the target value, if the total air amount is increased or decreased, according to the ratio of the increased or decreased amount, The amount of main air will increase or decrease.

  When the main air amount increases or decreases, the amount of powder sucked by the injector changes, so that the amount of powder discharged from the powder coating gun per unit time changes.

  If the amount of powder discharged from the powder coating gun per unit time is not constant, it is difficult to perform an accurate coating operation, and it is liable to cause coating failure.

  Accordingly, an object of the present invention is to maintain a constant amount of powder per unit time discharged from a powder coating gun even if the total air amount is adjusted.

In order to solve the above-described problems, the present invention has a main air nozzle connected to a compressed air source via a flow restrictor, and the main air supplied from the main air nozzle causes the powder from the powder tank. And a sub air nozzle connected to the compressed air source via a flow restrictor, which is provided with an injector that carries air from the discharge port through a transfer hose and supplies the sub air to the injector. Injector while maintaining a constant amount of powder discharged from a powder coating gun in a powder transfer device equipped with a controller for adjusting the flow throttle valve of the air nozzle and the flow throttle valve of the sub air nozzle when adjusting the total air quantity of conveying air supplied to the conveying hose from the main supplied from the main air nozzle While maintaining the earth amount constant, the adjustment of the total air amount, in order to perform the Sabuea amount supplied from the sub-air nozzle, by the controller, the main air amount supplied from the main air nozzle, the conveying hose from the discharge port Control the amount of sub-air supplied from the sub-air nozzle to the amount obtained by subtracting the main air amount from the set amount of the total air amount supplied to the transfer hose. It is what I did.

  That is, according to the present invention, when increasing or decreasing the total air amount discharged from the discharge port of the injector, the main air amount supplied from the main air nozzle is kept constant, and the increase or decrease amount of the total air amount is increased from the sub air nozzle. The flow rate throttle valve of the sub air nozzle is adjusted by the controller so as to cover the sub air amount supplied.

According to the present invention, as described above, there is no change in the main air amount supplied from the main air nozzle even if the total air amount discharged from the injector discharge port is increased or decreased. The amount of powder per unit time contained in the total air amount can be kept constant.
Therefore, when the powder conveying device of the present invention is used for powder coating, even if the total amount of air discharged from the coating gun is adjusted according to the shape of the object to be coated and the conditions of the conveying hose, the powder per unit time Since the body weight can be kept constant, it is easy to control the film thickness of the object to be coated, and stable coating work can be performed regardless of the skill level of the operator.

It is a whole lineblock diagram showing one embodiment of a powder conveyance device concerning this invention.

Embodiments of the present invention will be described below.
FIG. 1 shows a powder conveying device used in a powder coating apparatus for sucking a powder coating A from a fluid type powder coating tank 1 by an injector 2 and air conveying and discharging the powder coating to a coating gun 3. Is shown. Examples of the coating gun 3 include a corona electrostatic coating gun having a corona electrode at the tip of the gun, and a friction charging electrostatic coating gun having a friction tube in the gun body.

  The lower part of the powder coating tank 1 is partitioned by the porous plate 4, and the compressor air 5 dehumidified and deoiled is introduced from below the porous plate 4. The powder coating A in the powder coating tank 1 is dehumidified by the flowing air discharged from the porous plate 4 and dispersed in a fluid state.

  In the upper part of the powder coating tank 1 is installed an injector 2 that sucks the powder coating A in the powder coating tank 1 and air-transports the powder coating A to the coating gun 3 via the transfer hose 6. ing.

  The injector 2 is provided with a main air nozzle 7 and a sub air nozzle 8.

  The main air nozzle 7 and the sub air nozzle 8 are connected to a compressed air source 9 such as a compressor to which compressed air is supplied via flow restrictors 10 and 11, respectively.

  A pressure reducing valve 15 is installed between the compressed air source 9 and the flow restrictors 10 and 11.

The opening degree of the flow restrictors 10 and 11 is automatically adjusted by the controller 13.
In the controller 13, the relationship between the opening of the flow restrictors 10 and 11, the powder suction amount corresponding to the main air amount of the main air nozzle 7, and the actually measured value of the sub air amount of the sub air nozzle 8 is previously set as a command value. Have been entered.

  The compressed air supplied from the main air nozzle 7 of the injector 2 is called main air. The powder paint A is given a negative pressure to the suction port 12 by the Venturi principle and the powder paint A is passed through the suction pipe 16. Has a function of sucking and transporting to the coating gun 3. Generally, when the pressure and amount of the main air are increased, the venturi effect from the suction port 12 increases, the discharge amount from the discharge port 14 increases, and the amount of powder per unit time from the coating gun 3 increases. Become.

  Next, since the sub air supplied from the sub air nozzle 8 mainly differs in the length and resistance of the transport hose 6 depending on the installation location of the paint tank 1 and the gun arrangement, the powder paint is uniform in the transport hose 6. It is responsible for transporting at a stable speed.

  At the time of painting, the main air and sub air are supplied from the main air nozzle 7 and the sub air nozzle 8 to the injector 2, and the powder paint A in the paint tank 1 is supplied to the suction pipe 16, the suction port 12, and the discharge port. 14. Powder coating A is discharged from the coating gun 3 through the transport hose 6.

Adjustment of main air and sub air in the present invention is performed as follows.
The main air amount (l / min) is set so that the discharge amount (g / min) of the powder coating material per unit time discharged from the coating gun 3 becomes the target discharge amount.

  The sub air amount (l / min) is set to an amount obtained by subtracting the main air amount from the total air amount set according to the shape of the object to be coated.

  When the total air amount is changed, for example, when the total air amount is reduced to 90 (l / min) and the painting work that has been operated at the total air amount is 100 (l / min), the main air amount is changed. The controller 13 adjusts the opening degree of the flow restrictor 11 of the sub air nozzle 8 so that only the sub air amount is reduced by 10 (l / min) without changing the air amount.

  Therefore, according to the present invention, even if the total air amount is changed, the main air amount is not changed, so that the discharge amount (g / min) of the powder coating material can be kept constant.

DESCRIPTION OF SYMBOLS 1 Powder coating tank 2 Injector 3 Coating gun 4 Porous board 5 Compressor air 6 Conveyance hose 7 Main air nozzle 8 Sub air nozzle 9 Compressed air sources 10 and 11 Flow rate throttle valve 12 Suction port 13 Controller 14 Ejection port 15 Pressure reducing valve 16 Suction tube A Powder paint

Claims (3)

It has a main air nozzle connected to the compressed air source via a flow restrictor, and the main air supplied from the main air nozzle sucks the powder from the powder tank, and then discharges the powder from the discharge port via the transport hose. Provided with a sub-air nozzle connected to the compressed air source via a flow restrictor, and equipped with an injector that carries the body air, and supplied with sub-air to the injector, and the flow rate of the main air nozzle and the flow of the sub-air nozzle In a powder transport device equipped with a controller that adjusts the throttle valve, the total amount of transport air supplied from the injector to the transport hose is maintained while maintaining a constant amount of powder discharged from the powder coating gun . when adjusting, while maintaining the main air amount supplied from the main air nozzle constant, the total air quantity of tone And to perform the Sabuea amount supplied from the sub-air nozzle, by the controller, the main air amount supplied from the main air nozzle, and the amount of set ejection amount of supplied powder to the conveying hose from the discharge port can be obtained The powder conveying apparatus, wherein the sub air amount supplied from the sub air nozzle is controlled to an amount obtained by subtracting the main air amount from the set amount of the total air amount of the conveying air supplied to the conveying hose.   2. The powder conveying apparatus according to claim 1, wherein the powder is a powder paint, and a powder coating gun is connected to the conveying hose.   The powder conveying device according to claim 2, wherein the powder coating gun is an electrostatic coating gun.

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