JP3566855B2 - Ejector nozzle - Google Patents

Description

[0001]
[Industrial applications]
The present invention relates to an ejector nozzle device for transferring powder from a negative pressure tank to a normal pressure tank in an electrostatic coating apparatus.
[0002]
[Prior art]
Conventionally, the ejector nozzle device uses compressed air force to maintain the powder storage amount in the storage tank at a constant level, and sends the powder to the storage tank from the cyclone tank that is brought into a negative pressure state by an exhaust fan or the like. In order to prevent the powder from flowing backward when the compressed air stops, a shutter that is rotated manually or by a deceleration motor etc. is provided at the tip of the ejector nozzle, and the powder in the storage tank is reduced to a certain amount. A sensor that detects that the shutter has reached the target and closes the shutter when the supply of compressed air is stopped has been widely used.
[0003]
In addition, as another means, a damper for closing a hopper hole for discharging air from the cyclone tank is provided, and a means for canceling the negative pressure in the cyclone tank manually or by closing the damper by a motor or a solenoid with stopping the supply of compressed air. Had been.
[0004]
[Problems to be solved by the invention]
Providing a shutter and a damper in the ejector nozzle device means that when the supply of compressed air for transferring powder from the cyclone tank under negative pressure to the storage tank is stopped, air is supplied from the high pressure storage tank to the low cyclone tank together with air. This is to prevent the powder from flowing backward.
[0005]
However, in the means for providing a shutter that is rotated by a deceleration motor or the like that can output a large torque at the tip of the ejector nozzle, in order to prevent the powder from being sandwiched between the shutter and the tip of the ejector nozzle and to be in a half-open state, On the other hand , it takes a long time to fully close, and the time from the supply of compressed air until the shutter is fully closed takes a large amount of backflow of powder. It had to be larger than the amount of body, and the difference between the upper and lower levels had to be increased.
[0006]
Also, as the particle size of the powder becomes smaller, the danger of a flash explosion increases, so that it is desirable to avoid using a device that generates a spark. This point deceleration motor or the like has a problem that an accident such as burnout of a coil and a necessity of making a gap between a shutter and an ejector nozzle narrow are likely to cause gouging, which may cause a spark.
[0007]
Also in the damper that closes the kipper hole used as another means, even if the operation time required to fully close the damper is shortened, since the volume of the cyclone tank is large, it is necessary to stop the backflow of the air powder. Since it takes a while, and a motor or an electromagnetic solenoid is used as a driving source, there is still a possibility of spark generation like a shutter.
[0008]
The present invention has been made in view of such problems, and a purpose thereof is to transfer powder from a cyclone tank or the like in a negative pressure state to another tank such as a storage tank. When powder decreases, it recovers in a short time and reduces the difference between the upper and lower limits of the powder level and keeps the powder storage amount constant. No inexpensive ejector nozzle is to be provided.
[0009]
[Means for Solving the Problems]
In order to solve the above-mentioned object, an ejector nozzle for ejecting a powder coating used in the electrostatic coating apparatus of the present invention has one end fixed to the outer periphery of the nozzle ejection opening, and the ejector nozzle at the other end in the longitudinal direction extending from the one end. Due to the pressure difference between the inside and outside of the nozzle and the self-soft elasticity, the end operates in a state in which the nozzle is in close contact with the nozzle orifice and a state in which the end is separated from a plane forming the nozzle orifice to close or open the nozzle orifice It is characterized by having a soft elastic plate-shaped member.
Due to the pressure difference between the inside and outside of the nozzle and the self-soft elasticity, when the compressed air or the powder coating material is fed into the soft elastic plate member, the free end operates in a state of being separated from the plane forming the nozzle injection port. When the supply of air or powder paint is stopped and the air or powder paint starts to flow backward, the free end operates in a state in which the nozzle orifice comes into close contact with the nozzle orifice, causing the nozzle to eject. Close your mouth.
That is, a plate member having soft elasticity, which is deformed by the pressure difference between the inside and outside of the nozzle generated when switching the supply of the compressed air or the powder coating material, closes or opens the nozzle injection port.
[0010]
Further, it is preferable that the distance from the position where one end of the plate-shaped member is fixed to the tip of the free end that closes or opens the nozzle outlet is longer than the diameter of the nozzle outlet. It is preferable that the shape is continuous with the handle portion including the fixed one end and at least covers the nozzle injection port.
By making the distance from the position where one end of the plate-shaped member is fixed to the tip of the free end portion longer than the diameter of the nozzle injection port, the moment acting on the free end portion can be increased, and a small pressure difference can be obtained. With this, the free end can be largely operated. Furthermore, by making the free end portion connected to the handle portion including the fixed one end at least cover the nozzle injection port, the free end portion accurately responds to the pressure difference applied between the inside and outside of the nozzle, and the entire nozzle ejection port is formed. Close.
[0011]
In addition, the plate-like member is preferably made of silicone rubber having soft elasticity. This is because the powder coating does not adhere to the silicone rubber, so that the adhesion of the powder coating to the nozzle ejection port due to the powder coating adhering to the plate-shaped member is prevented.
[0012]
[Action]
The plate-like member having one end fixed to the outer periphery of the nozzle outlet has a free end portion at the other end extending from the fixed one end. The free end closes or opens the nozzle outlet due to the pressure difference between the inside and outside of the nozzle and the self-soft elasticity. This plate-shaped member is a member having soft elasticity by itself, and preferably silicon rubber can be adopted.
[0013]
When the supply of the powder paint to the storage tank is started, the pressure inside the nozzle outlet becomes larger than the pressure inside the storage tank. The free end of the plate-shaped member is operated by the pressure difference and the self-soft elasticity so as to be separated from the plane forming the nozzle orifice to open the nozzle orifice. When the supply of the powder paint is sufficient and the supply of the compressed air is stopped, the pressure inside the nozzle injection port becomes smaller than the pressure in the storage tank. The free end of the plate-shaped member operates by the pressure difference and the self-soft elasticity so as to be in close contact with the nozzle outlet, and closes the nozzle outlet.
In this operation, the free end of the plate member operates in a state in which the free end of the plate-like member is in close contact with the nozzle outlet with the fixed end as a fulcrum, and is separated from the plane forming the nozzle outlet. This operation is based on the energy due to the pressure difference between the inside and outside of the nozzle and the energy due to the soft elasticity of the nozzle itself.
For this reason, for example, the distance from the position where one end of the plate-shaped member is fixed to the tip of the free end that closes or opens the nozzle injection port is made longer than the diameter of the nozzle injection port, thereby fixing the fulcrum. The (one end) is separated from the free end serving as an action point, and a large moment acts on the free end. When the nozzle is open, the nozzle outlet is largely opened, and when the nozzle is closed, the nozzle outlet can be closed quickly.
Further, by forming the free end portion connected to the handle portion including one end at least to cover the nozzle injection port, compressed air does not leak from the nozzle injection port at the time of closing, and the free end portion reduces the pressure difference between the inside and outside of the nozzle. Detect accurately and perform closing or opening according to the pressure difference.
[0014]
The loose fitting portion is formed so that a part of the soft elastic plug is loosely fitted to the nozzle. When the supply of the compressed air is stopped and the air and powder in the storage tank flow back to the nozzle, the cross-sectional area of the nozzle is adjusted. And increasing the flow rate of air to increase the pressure difference between the pressure in the storage tank and the pressure in the injection port, thereby enabling faster sealing.
[0015]
【Example】
Hereinafter, the ejector nozzle of the present invention will be described with reference to the drawings. FIG. 4 is an explanatory view of the flow path of the powder used in the electrostatic coating apparatus. Reference numeral 21 denotes a dust collecting device which sucks a light, fine dust-like material floating in the cyclone hopper 24 among the powders 8 together with air through a dust collecting hose 33, and separates powder having a certain particle size into a cyclone. Collect in the tank 25. The small-particle or light-weight powder 8 is supplied to the cyclone hopper 24 together with air in a collecting pipe 30 and a storage tank 26 for newly replenishing the powder 8 serving as a coating material for electrostatic coating. In this case, the cyclone hopper 24 and the cyclone tank 25 are at a pressure lower than the body pressure due to the exhaustion by the dust collecting device 21, and the cyclone hopper together with the flowing air 34 for fluidizing and uniformizing the powder 8 from the lower part of the cyclone tank 25. An updraft is generated in the inside 24, and a part of the lightweight powder 8 supplied from the collecting pipe 30 is discharged from the cyclone hopper 24 to the dust collecting device 21 via the dust collecting hose 33. A filter 22 and an unnecessary powder hopper 23 are provided in the dust collecting device 21 and are separated so that dust does not enter the exhausted air.
[0016]
The powder 8 accumulated in the cyclone tank 25 is supplied to the ejector nozzle 1 via the ejector 10 and the granular material supply hose 9. At this time, since the cyclone tank 25 is in a negative pressure state with respect to the body pressure, the compressed air 4 supplied from the inside of the cyclone tank 25 to the ejector 10 through the compressed air supply electromagnetic valve 11 transfers the powder 8. Help. Although not shown, the ejector 10 and the ejector nozzle 1 may be integrally formed as another embodiment.
[0017]
The ejector nozzle 1 is attached to a storage tank 26 that always stores a fixed amount of the powder 8, and supplies the powder 8 in the cyclone tank 25 to the storage tank 26 as needed. The storage tank 26 is provided with an A level sensor 27 and a B level sensor 28 for monitoring the storage amount of the powder 8, and the A level sensor 27 detects the powder to close the compressed air supply electromagnetic valve 11. Then, the supply of the powder 8 is stopped together with the supply of the compressed air 4. When the B level sensor 28 stops detecting the powder, that is, when the level of the powder 8 is lowered, the compressed air supply electromagnetic valve 11 is opened to supply the powder 8 to the storage tank 26 together with the compressed air 4. . In this way, the powder 8 is stored in the storage tank 26 so as to be always within a certain level. Fluid air 34 is supplied from the lower part of the storage tank 26 to agitate and uniform the powder 8 in the tank and blow up fine powder upward to be returned to the cyclone hopper 24 via the powder circulation hose 32. . Although not shown, a plurality of hoses may be provided in the collecting pipe 30 so that excess powder can be collected in the collecting pipe 30 from various parts of the apparatus. The air filter 29 is provided on the upper part of the storage tank 26 and performs an auxiliary function so that a negative pressure is not generated by the suction force from the dust collecting device 21 only by the flowing air 34. At this time, it is provided so that dust and the like outside cannot enter.
[0018]
The storage tank 26 always plays an important role in constantly supplying a constant amount of the powder 8 to the surface to be coated by electrostatic coating or the like, since the constant amount of the powder 8 is stored. For example, the storage tank disclosed in Japanese Patent Application Laid-Open No. 9-70452 is capable of constantly supplying a constant amount of powder to a fluidizing tank for fine coating since the powder 8 is at a certain level.
[0019]
FIG. 3 is an operation explanatory view of an ejector nozzle using a soft elastic stopper. In order to feed the powder 8 from the negative pressure cyclone hopper 24 and the cyclone tank 25 to the storage tank 26 at the same atmospheric pressure as the atmospheric pressure, the compressed air supply solenoid valve 11 for controlling the supply of the compressed air 4 is operated, and the ejector is operated. When the compressed air 4 is directly sucked into 10, the powder 8 at the inlet of the ejector 10 is also sent to the powder supply hose 9 together. At this time, since the powder 8 in the tank is uniformly dispersed by the flowing air 34 in the cyclone tank 25, the periphery of the powder 8 sent to the ejector 10 can be filled and the powder 8 can be continuously formed. 8 can be fed into the powder supply hose 9. The porous plate 35 is a plate for blowing the flowing air 34 over a wide range in order to stir the powder 8 uniformly, and is also used for the storage tank 26.
[0020]
The powder 8 and the compressed air 4 sent to the powder supply hose 9 are sent out via the ejector nozzle 1 attached to the storage tank 26. The ejector nozzle 1 is formed of a cylindrical nozzle 3 in which the nozzle outlet 2 at the tip is machined so as to have a smooth surface, and a soft elastic material such as silicone rubber, which can completely seal the nozzle outlet 2. It is composed of an elastic plug 5. One end of the soft elastic plug 5 is fixed to a plug fixing portion 12 provided at the outer edge of the nozzle injection port 2 by a fixing metal or the like, and the free end 6 closes the nozzle injection port 2. The soft elastic plug 5 for closing the nozzle injection port 2 is deformed by the compressed air 4 and the pressure of the powder 8, the nozzle injection port 2 is opened, the powder 8 is supplied into the storage tank 26, and the A level sensor 27 It continues until the body 8 is detected. When the A level sensor 27 detects the powder 8, the compressed air solenoid valve 11 stops supplying the compressed air 8. At this time, the pressure in the storage tank 26 becomes larger than the pressure in the cyclone tank 25, and the flow of air is reversed. Therefore, the powder 8 that has been supplied to the storage tank 26 until now flows back to the cyclone tank 25.
[0021]
The soft elastic plug 5 reverses the pressure applied to the soft elastic plug 5 due to the backflow of the air and the backflow of the powder 8, and easily ejects the nozzle from the shape of the soft elastic plug 5 that seals the nozzle outlet 2 originally provided. The mouth 2 is sealed, and the backflow of the powder 8 can be prevented in a short time. Therefore, the circulation efficiency of the powder 8 is greatly improved as compared with the conventional one, and the interval between the A level sensor 27 and the B level sensor 28 can be narrowed by the amount that the powder 8 does not flow back to the cyclone tank 25. Can be
[0022]
FIG. 1 is a diagram showing one embodiment of the ejector nozzle of the present invention. The flange 13 is a fixing member for fixing to the storage tank 25, and positions the nozzle and the soft elastic plug 5 in the storage tank 26. The right end of the flange 13 is provided with a hose connection part 14 for connecting the powder supply hose 9. At an end of the nozzle 3, a nozzle injection port 2 is provided. The nozzle orifice 2 has a shape obtained by cutting the cylindrical nozzle 3 in one plane, and is processed smoothly. The plug fixing portion 12 is provided on the outer edge side of the nozzle injection port 2, and fixes one end such that one surface of the free end portion 6 of the soft elastic plug 5 formed of silicon rubber or the like is in close contact with the nozzle injection port 2. In FIG. 1, the soft elastic plug 5 is fixed to the plug fixing portion 12 with the fixing band 17, but may be screwed or the like.
[0023]
FIG. 2 is a view showing another embodiment of the ejector nozzle of the present invention. The loose fitting portion 7 shown in FIG. 2 (a) is a convex portion formed at a position where the loose end 6 of the soft elastic plug 5 loosely fits into the nozzle injection port 2, and the supply of the compressed air 4 is stopped. When the air flows backward, the nozzle injection port 2 can be closed quickly by narrowing the cross-sectional area of the nozzle injection port 2 and increasing the flow velocity of the air flowing backward.
[0024]
FIG. 2B shows a modification of the ejector nozzle shown in FIG. 1 in which the nozzle injection port 2 is formed obliquely, and the soft elastic plug 5 closes the nozzle injection port 2 from obliquely above. The force for closing the nozzle injection port 2 when the supply is stopped is a value obtained by adding the weight of the soft elastic plug 5 to the pressure difference between the storage tank 26 and the cyclone tank 25, and the nozzle injection port 2 is more closed. to be certain.
[0025]
FIG. 2C shows a nozzle funnel-shaped nozzle orifice 2 arranged upward and a lightweight ball member 16 fitted to the nozzle orifice 2. When the supply of the compressed air 4 is stopped, the ball member 16 descends by its own weight and closes the nozzle injection port 2. Further, the pressure difference between the storage tank 26 and the cyclone tank 25 can more reliably close the nozzle injection port 2. The fixed band 17 regulates the ball member 16 blown up by the compressed air 4 so that it cannot return to the funnel-shaped nozzle injection port 2.
[0026]
【The invention's effect】
As described above, the ejector nozzle of the present invention has the following effects.
[0027]
The soft elastic plug 5 and the ball member 16 for opening and closing the nozzle injection port 2 have a simple configuration, have no complicated electric and mechanical components, and have few failures. It is also cheap.
[0028]
In addition, it is difficult to generate a twist or the like between the nozzle injection port 2 and the soft elastic plug 5 and the ball member 16 , and since no electric device or the like is used, there is no trouble such as occurrence of a spark due to a failure or the like and fine powder is used. Eliminate ignition and explosion causes.
[0029]
The soft elastic plug 5 and the ball member 16 are lightweight and operate by directly sensing the compressed air 4 or the backflow of air, so that the opening and closing response of the nozzle injection port 2 is good, and the powder 8 sent into the storage tank 26 is compressed. The amount of backflow by stopping the air 4 can be reduced, the interval between the A level sensor 27 and the B level sensor 28 can be reduced, and the storage tank of the powder 8 in the storage tank 26 can be stabilized.
[Brief description of the drawings]
FIG. 1 is a diagram showing an embodiment of an ejector nozzle of the present invention.
FIG. 2 is a view showing another embodiment of the ejector nozzle of the present invention.
FIG. 3 is a diagram illustrating the operation of an ejector nozzle.
FIG. 4 is an explanatory view of a flow path of powder used in the electrostatic coating apparatus.
[Explanation of symbols]
1 ejector nozzle 2 nozzle injection port 3 nozzle 5 soft elastic plug 7 loose fitting portion 8 powder

Claims (1)

Ejector nozzle provided so that the nozzle injection port faces the storage tank in order to suction the powder coating material accumulated in the cyclone tank of the electrostatic coating apparatus using compressed air and to spray it into the storage tank. At
One end is fixed to the outer periphery of the nozzle outlet provided so as to face the inside of the storage tank, and a free end at the other end in the longitudinal direction extending from the one end is shaped to cover the nozzle outlet, and the nozzle Due to the pressure difference between the inside and outside and the self-soft elasticity, it operates in a state of being in close contact with the nozzle orifice and in a state of being separated from the plane forming the nozzle orifice, and has a soft elasticity that closes or opens the nozzle orifice. A silicon rubber plate member is provided,
An ejector nozzle, wherein a distance from a position where one end of the plate-shaped member is fixed to a tip end of the free end portion that closes or opens the nozzle outlet is longer than a diameter of the nozzle outlet.

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