JP4018192B2 - Dispersing system for powder spray equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method and apparatus for forming a powder cloud produced when a mixture of powder and air exits a powder spray device.
[0002]
This spraying device is particularly suitable for the case where a mixture of powder and air exits the flow chamber through a nozzle. However, it can also be used, for example, in a spray device in which a mixture of powder and air is supplied via a hose.
[0003]
[Prior art]
An unpublished German patent application P 195 370 89.9 discloses a powder spray device. This has a fluidized chamber, and fluidized powder is extracted from the fluidized bed through an extraction tube, and is discharged to the outside through a nozzle. Then, a high voltage electrode is provided in the outlet region so as to charge the discharged powder.
[0004]
In the above-mentioned application, it has been proposed to arrange a baffle as a spraying system in which a mixture of powder and air from a nozzle collides to generate a powder cloud.
[0005]
However, the use of this small baffle only produces a relatively small powder cloud and is not large enough for certain applications.
[0006]
And the use of large baffles is not allowed in this case as the powder accumulates on the baffles.
[0007]
In order to avoid powder accumulation and to generate a relatively wide powder cloud, EP A1 0574 305 proposes a spraying system with a high-speed rotating disc of 3000 rev / min or more.
[0008]
However, this system is mechanically sensitive and, in addition, has a short life as a spraying device.
[0009]
Further, the above two spray devices have a disadvantage that a flat nozzle (flat nozzle) cannot be inserted in order to generate a flat powder jet.
[0010]
[Problems to be solved by the invention]
Accordingly, the present invention provides a different spraying method and apparatus for generating a large spray cloud that spreads relatively widely, without using a rotating member, and without generating powder on the spraying apparatus. The issue is to provide.
[0011]
[Means for Solving the Problems]
In the case of the method for forming a powder cloud according to the premise part of claim 1, the above object is achieved by the configuration described in the characteristic part.
[0012]
In this method, the compressed air stream is directed tangentially over the mixture stream in the hollow body . Thus, the generated flow of the mixture with spin is spread out from the powder spray device.
[0013]
Moreover, in the case of the dispersion apparatus which forms the powder cloud as described in the premise part of Claim 3, it is achieved by the structure as described in the characteristic part.
[0014]
In the case of this spraying device, a mixture of powder and air flows out of the hollow body . The hollow body has a plurality of drill holes in the wall through which a stream of compressed air is introduced tangentially through the one or more holes.
[0015]
Another example of spray device is described in claim 9.
[0016]
In this case, the flow of the mixture leaving the nozzle impinges on the top of the conical baffle and flows along the surface of the cone towards the outlet. In this case, the flow of the mixture is guided in an annular gap between the conical surface and a funnel-shaped guide provided at a distance from it. An annular duct having a plurality of drill holes is also arranged in the region of the inlet nozzle, through which the controlled compressed air is directed tangentially onto the mixture flow .
[0017]
Instead of or in addition to this control air, control air is introduced from a drill hole drilled in the funnel-shaped guide wall.
[0018]
Other possible configurations are defined in other claims.
[0019]
DETAILED DESCRIPTION OF THE INVENTION
An example of the embodiment of the present invention will be described below with reference to FIG.
[0020]
FIG. 1 is a schematic diagram showing a cross section of the fluid tank 2 in a state where the fluid tank 2 is closed.
[0021]
In the tank 2, there is fluidized powder 8, which is extracted from the fluidized bed through an extraction pipe 25 and controlled by a closing device 13.
[0022]
In this example, the closing device 13 is a tube that opens into the extraction tube 25, and compressed air is introduced through the tube, and the fluidized powder 8 is closed in the closed tank 2 by this force. Pushed back.
[0023]
From the nozzle 11, the fluidized powder 8 enters the spraying device 1 as a mixture flow . Spraying device 1 is configured as a hollow body 3, the hollow body is formed by a pipe 4, the nozzle 11 as an inlet fluidized powder 8, also 12 has an outlet.
[0024]
The hollow body 3 may have other shapes. For example, a cone is used instead of the pipe 4. In this case, the nozzle 11 is disposed at the cone start portion having a small diameter.
[0025]
A plurality of drill holes 5 are formed in the pipe 4 in rows around the pipe. In addition, you may make it the drill hole 5 which makes such a row | line | column sequentially provided in an axial direction, ie, a spray direction.
[0026]
The shape of the drill hole 5 is clarified in the AA cross section display. Compressed air is then introduced from the drill hole 5 into the hollow body 3 as control air 6 tangentially contacting the mixture flow 16.
[0027]
This results in an enhanced helical movement of the mixture stream 16 towards the outlet 12. The outlet 12 can be configured to expand the funnel shape, thus forming a powder cloud 15 that is expanded by the centrifugal force of the rotating powder.
[0028]
In this example, the spraying device 1 has a double wall structure. The control air 6 is supplied to the outer chamber 7 through a supply line 9, and the control air 6 is introduced from there through the drill hole 5 into the hollow body 3.
[0029]
By placing the micro baffle 10 adjacent to the downstream side of the nozzle 11, the flow 16 of the mixture is widened. Thus, the spin action of the control air 6 is strengthened.
[0030]
The powder is charged outside the outlet 12 by the high voltage electrode 14.
[0031]
The shape of the powder cloud 15 is influenced not only by the supply of control air but also by the shape of the spraying device and the like.
[0032]
Important parameters are defined in FIG.
[0033]
The length L ₂ is from the inlet point 5 of the control air 6 to the starting point of the outlet 12, the length L ₁ is the distance between the nozzle 11 and the inlet point 5, D ₁ is the diameter of the pipe 4, D ₂ Is the diameter of the funnel-shaped expansion of the outlet 12, α ₁ is the expansion angle of the funnel, D ₃ is the opening diameter of the nozzle 11, and D ₄ is the diameter of the drill hole 5. In addition to these parameters, there are the number of drill holes 5.
[0034]
FIG. 3 shows a second modification of the spraying device 1.
[0035]
The fluidized powder 8 is introduced into the dispersing device in the axial direction through the nozzle 11.
[0036]
Mixture stream 16 generated by nozzle 11 impinges on conical baffle 17 immediately downstream of nozzle 11. Mixture stream 16 flows along the surface of conical baffle 17 toward outlet 12. In this case, the spread mixture stream 16 is guided to a guide wall 18 along the cone. The guide wall 18 is a part of the supply duct 19, and the control air 6 is introduced into the duct 19 through the supply line 9 and flows out through the drill hole 5. This drill hole 5 is shown in the AA arrow cross-sectional view and is directed tangentially to the flow 16 of the mixture .
[0037]
Instead of or in addition to the introduction of control air described above, control air 6 is directed axially from the annular duct 20 and tangentially to the mixture flow 16. For this purpose, the control air 6 is introduced into the annular duct 20 through the second supply line 21 and flows out from the drill hole 22.
[0038]
It flows from the annular duct 20 passes through the drilled hole 22, the control air 6 impinging tangentially to the flow 16 of the mixture, a stream 16 while accelerating in the axial direction of the mixture, adding a rotational movement. A high voltage electrode 14 is disposed in the outlet region 12. The powder cloud 15 exiting from the gap-shaped outlet 12 is particularly effectively charged as a result of the helical motion.
[0039]
The shape of the powder cloud 15 is influenced by the control air 6 supplied to the two supply lines 9 and 21.
[0040]
Control air 6 is a Rubeki limited to the amount required for the formation of the desired powder cloud 15. This is because the control air 6 reduces powder density which is essentially undesirable.
[0041]
The above-described first and second spraying devices and the method of simultaneously affecting the shape of the powder cloud described above are applied to a spraying device for a spraying device using a flow of a mixture having a high powder ratio, for example, as shown in FIG. It is particularly effective for the device.
[0042]
【The invention's effect】
The effect of the method and apparatus of the present invention is in particular that the shape of the powder spray cloud is not only defined by the shape of the configuration, but is also changed during operation by changes in the supply of control air.
[0043]
It is also possible to operate using a flat nozzle.
[0044]
In addition, the accumulation of powder in the spraying device is greatly avoided.
[0045]
Also, the helical movement of the powder in the powder cloud by the spreading device guides the powder to move close to the high voltage electrode. As a result, the electrostatic charge is improved, thereby improving the adhesion of the powder to the processed material.
[Brief description of the drawings]
FIG. 1 is an explanatory view of a first embodiment of a spraying device to which control air is introduced in a tangential direction according to the present invention, connected to a powder spray device.
FIG. 2 is an explanatory diagram of the shape and dimensions of the first embodiment.
FIG. 3 is an explanatory diagram of a second embodiment of a spraying device in which control air is introduced in a tangential direction.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Spreading device, 5 ... Drill hole, 6 ... Control air, 9, 21 ... Supply line, 10 ... Baffle, 12 ... Outlet, 14 ... High pressure electrode, 16 ... Flow of mixture , 17 ... Conical baffle, 18 ... Guide wall 22-24 ... drill hole, 25 ... extraction tube.

Claims (9)

A method for forming a powder cloud consisting of a mixture of powder and air exiting a powder spray device for electrostatic coating,
A stream (16) of the mixture is blown into the hollow body (3) from the nozzle (11) in the axial direction of the spray, and compressed air is used as control air (6) for this mixture stream (16). Flow in the tangential direction of the cross section of the flow (16), and in addition to the axial momentum, the tangential momentum is imparted to the flow (16) of the mixture, thus forming a powder cloud (15). In a method in which the spread of the mixture stream (16) is promoted:
A baffle (10) is disposed in the hollow body (3) adjacent to the nozzle (11) and between the nozzle (11) and the cross section into which the control air (6) is blown. (10) widens the cross section of the flow (16) of the mixture,
A method of forming a powder cloud characterized by the above.   The said control air (6) is blown in the said tangential direction toward the said flow (16) of the mixture from several places, The flow of the control air divided | segmented into plurality is formed. 2. A method for forming a powder cloud according to 1. A spraying device (1) for forming a powder cloud (15) comprising a mixture of powder and air (8, 16) exiting a powder spray device for electrostatic coating,
It has a hollow body (3), and this hollow body (3)
a) for the flow of the mixture (16), with a nozzle (11) oriented in the axial direction of the spray ;
b) The wall (4, 18) has a plurality of drill holes (5) through which the control air (6) is directed to the mixture flow (16) and the mixture flow. (16) is blown in the tangential direction of the cross section,
c) also having an outlet (12) for the flow (16) of the mixture having a spin by the control air (6),
In the spraying device,
d) a baffle (10) is disposed in the hollow body (3) adjacent to the nozzle (11) and between the cross section through which the nozzle (11) and the control air (6) are blown; The baffle (10) widens the cross-section of the mixture stream (16);
A spraying device characterized by.     4. Dispersion according to claim 3, characterized in that the hollow body (3) is a pipe (4) having a drill hole (5) in its wall for introducing the control air (6, 9). apparatus.   The hollow body (3) is formed as a cone with a drill hole for introducing control air, and the inlet for the flow of the mixture is provided on the small diameter side. Item 4. A spraying device according to item 3.   The spraying device has a double wall structure, and the control air (6) is introduced into the outer chamber (7, 19) between the double walls, and the air is the inner wall of the double wall. It is guided in the tangential direction of the cross section of the mixture flow (16) toward the mixture flow (16) through a plurality of drill holes drilled in (4, 18). The spraying device according to any one of claims 3 to 5, wherein the spraying device is characterized.   The spraying device according to any one of claims 3 to 6, wherein a flat nozzle is fixed on the outlet.   The spraying device according to any one of claims 3 to 7, wherein the outlet (12) is formed in a funnel shape for expanding the hollow body (3). A spraying device (1) for forming a cloud of powder consisting of a mixture of powder and air exiting a powder spray device for electrostatic coating,
a) a nozzle (11) through which the flow (16) of the mixture passes and enters the spraying device (1) in the axial direction of the spray;
b) a conical baffle (17), arranged downstream and adjacent to the nozzle (11), the flow of the mixture (16) impinges on the top of the cone and exits along the conical surface ( 12) a conical baffle (17) directed to
c) wherein a conical baffle (17) of the conical surface from being placed at a predetermined distance a funnel-shaped guide wall (18), forming an annular gap (3), the flow of the mixture through the gap ( 16) a guide wall (18) guided by the outlet (12);
d) an annular duct (20) disposed downstream of the nozzle (11) and provided with a plurality of drill holes (22) ;
Have
e) The flow of the mixture (6), in which the control air (6) is introduced mainly tangentially to the spray direction through the drill hole (22) provided in the annular duct (20) and flows towards the outlet ( 16) giving a turning motion ,
f) On the downstream side of the drill hole (22) provided in the annular duct (20), control air (6) passes through the drill hole (5) provided in the guide wall (18) and passes through the mixture. Being introduced in the tangential direction of the cross section of the flow (16) of
A spraying device characterized by .

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