JPS61192620A - Powdered body transporter - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method and apparatus for supplying air-containing solid particulate powder material to a granular spray gun or powder dispenser. More particularly, the present invention relates to an improved blade method and apparatus for providing a uniform powder flow from a fluidized powder source to a powder spray gun or powder dispenser.

Powder is fed to the powder spray gun through a pneumatic conveyor line equipped with a powder pump with a low pressure venturi pump chamber. The low-pressure venturi pump chamber intersects with a powder supply passage through which powder is supplied from the fluidized bed hopper to the powder pump. In order to meter or control the flow of powder from a fluidized bed to a venturi pump chamber, such powder pumps conventionally provide a controlled air flow with a powder feed path that operates to inject a metering air flow. It had a road. The pressure of this metering air stream controls the amount of air that is mixed with the powder entering the pump, and thus also the flow rate of powder from the pump.

One drawback common to all powder spray devices, including those using powder pumps as described above, is that the powder discharged from the spray gun of the device flows non-uniformly. That is, the powder ejected from the gun periodically ejects all at once or collects in a cloud, and the density of the powder ejected from the gun periodically decreases. in this way,
When the density of the powder injected from the gun increases and decreases periodically,
The amount of powder applied to the target substrate becomes uneven. Therefore, such irregular changes in powder density are highly undesirable.

Many attempts have been made to minimize or reduce these irregularities in powder density ejected from powder spray guns. Such efforts have involved changing the design of the powder spray gun and changing the design and construction of the powder pump. Most of these modified methods improve some of the above problems, but
It's not enough.

The present invention therefore aims to provide an improved powder spraying device in which accidental or irregular variations in the flow rate of powder injected from a powder spray gun or dispenser are minimized. Or be excluded.

The present invention is based on the discovery that one cause of non-uniform powder flow from a powder spray gun or dispenser of a powder spray system is the configuration of the powder spray system between the fluidized bed powder source and the transfer gun. It is based in part on That part of the device has hitherto simply consisted of a siphon tube that feeds the powder from the fluidized bed to the powder pump, and a long supply hose that connects the powder pump and this pump to the gun. be. The present invention therefore aims to eliminate the variations in powder flow that have heretofore been attributed to the configuration of this part of the apparatus.

These objects are hereby achieved and the present invention also provides a method for connecting hoses from powder pumps to 5. Partly based on the idea of feeding powder to an auxiliary fluidized bed of powder located near the D8 Pensagan, and then feeding this powder from the auxiliary fluidized bed through an auxiliary powder pump and a relatively nearby hose. It is something.

The auxiliary fluidized bed and the auxiliary powder pump located near the outlet of the dispenser gun of the powder spray equipment described above have traditionally been attributed to the relatively long length of hose between the pump and the gun, and the fluidized bed powder Non-constant powder flow due to fluctuating levels of powder within the body image is reduced or completely eliminated.

The inventors have discovered that most of the flow rate variation in conventional powder spray equipment is due to two causes. These are due to the relatively long hoses located between the pump and the gun, as well as variations in the powder level of the fluidized bed powder source relative to the spray equipment. Longer hoses between the pump and the gun create flow variations due to the loops and curvatures inherent in such long hoses. Powder collects within these loops or bends, and the increased pressure behind the powder restriction is released from this restriction, which in turn causes the resulting powder mass to be ejected from the gun; At the same time, this causes an increase in the pressure in the hose and hence the powder flow to the gun. This powder then begins to collect in the bend or loop of the hose from which it was just released, until the powder forms a restriction in the hose and is released, attracting other powder groups, etc. .

The other major source of flow rate variation in conventionally arranged powder flow systems is the variation in powder levels contained in fluidized bed powder sources.
When the powder level changes in the fluidized bed, it causes a change in flow rate due to the different pressures required to draw the powder into the powder pump. In reality, the vacuum in the pump draws the powder into the pump, but does not change as the powder level in the fluidized bed hopper varies. On the other hand, the vacuum pressure remains the same, but the powder flow drawn into the pump changes as the powder level in the hopper changes.

In accordance with an embodiment of the present invention, a powder spray apparatus consists of a primary fluidized bed hopper powder source and a small volume auxiliary fluidized bed hopper capped adjacent to or near the powder dispenser gun. A venturi-type pump and connecting hose conveys powder from the main hopper to the auxiliary hopper, and an auxiliary venturi-type powder pump and connecting hose conveys powder from the auxiliary hopper to the dispenser gun. An overflow tube extends between the auxiliary hopper and the main hopper and functions to maintain a constant level of powder within the auxiliary hopper. With the present invention, which uses an auxiliary venturi pump and an auxiliary fluidized bed hopper in close proximity to the powder spray gun of a powder spray device, sources of variation in powder flow changes can be eliminated. Flow variations that occur in the long hose between the main hopper and the auxiliary hopper do not affect the flow rate between the auxiliary powder pump and the spray gun. Additionally, the use of an overflow tube between the auxiliary fluidized bed hopper allows the powder level in the auxiliary hopper to be maintained at a constant level as long as excess powder is fed to the auxiliary fluidized bed. . This results in
Flow variations contributing to varying powder levels in the feed hopper are eliminated.

Referring now to the accompanying drawings, there is shown a powder spray apparatus 10 that sprays solid particulate powder material from a plurality of spray guns. Although three guns 12 are shown in the drawings, the powder spraying apparatus described above is equally applicable to powder sprays consisting of a single gun or a substantially larger number of guns 12. This gun 12 does not itself constitute any part of the invention of this application and is well known in the art. Such a gun suitable for use in this application is illustrated and described in Thomas E. Holstein et al., U.S. Pat. Are listed.

In addition to the gun 12, the powder spray device 10 includes a main supply hopper 14, an auxiliary hopper, and 1 and 2 main supply hoppers.
ff'f147! l' et al auxiliary 't'''lt<16LIC
It consists of a main air pump 18 that transfers the powder and a plurality of auxiliary air pumps 20 that transfer the powder from the auxiliary hopper 16 to the gun 12. The air pumps 18 and 20 are conventional powder pumps which do not themselves constitute any part of the invention of this application. One example of such a pump suitable for use in this application is described in U.S. Pat. No. 3,746,254 by Lane S. Duncan et al. Body Spray Method”.

Hoppers 14 and 16 are conventional fluidized bed hoppers;
Nor does it itself form any part of the invention of this application. Both of these hoppers 14 and 16 have a closed chamber 24 at the bottom of the hopper and an air-permeable ceiling 2 provided inside the closed chamber.
6. When high pressure air is applied to the inlet 28 of the closed chamber 24, this air passes through the ceiling 26 of the closed chamber 24 and operates to fluidize the powder 30 contained in the hopper above the closed chamber 24.

The difference between the two hoppers is that the auxiliary hopper 16 is smaller in size and has a smaller capacity than the supply hopper 14.

In one preferred embodiment, auxiliary hopper 16 supplies powder to eight guns 12, but auxiliary hopper 1G has a volume that is only about 1/16 of the volume of supply hopper 14.

The two hoppers 14, 16 also differ in that the feed hopper 14 has a vent hole 34 in its upper wall, whereas the auxiliary hopper 16 does not. Instead, the auxiliary hopper 16 is vented via an overflow pipe 36 that extends downwardly from the interior of the auxiliary hopper 16 through the closed chamber 24 of this hopper 16 and of the feed hopper 14. At the top, extending through the wall. As discussed in further detail below, the overflow tube 36 is connected to the auxiliary hopper 16.
It also functions to vent any excess powder from the auxiliary hopper 16 to the feed hopper 14.

The powder pumps 18,20 are all the same except that the powder pump 20 of the auxiliary hopper 16 has a smaller capacity than the powder pump 18 of the feed hopper 14. Each of these powder pumps has an inlet port 40. An outlet port 42 and an atomizing air intake port 44 are provided. Additionally, each of these pumps has an internal powder flow path 46 through which powder is drawn into the pump's venturi pump chamber 48 via a siphon tube 50, where the siphon tube The inlet 52 of the body flow path 46 is connected to the fluidized bed 30 of powder from which the pump sucks the powder. The supply hopper pump 18 sucks powder from the hopper 14 and transfers the powder into the auxiliary hopper 16 via the transfer duct 54, and the auxiliary hopper pump 20 sucks the powder from the auxiliary hopper 16. The powder is also transferred to the dispenser gun 12 via a short transfer hose 56.

The pump 18.200A mouth port 40 is connected to a source of high pressure air 60 via an air line 58, while the atomizing air inlet port 44 of the pump is connected to the same source of high pressure air via an air line 62. A small air orifice is provided within each pump through which high pressure air from the air source 60 flows into the venturi pump chamber 48 to create a low pressure within that venturi pump chamber 48. This low pressure draws the powder upwardly through the siphon tube 50 into the venturi pump chamber 48 of the pump, thereby transferring the powder from the pump 18 to the hopper 16 via the hose 54, or in the case of the pump 20. It can be conveyed to dispenser gun 12 via hose 56 .

As detailed in the above-mentioned US Pat. No. 3,746.2 s 4, the air pressure supplied to the inlet port 40 causes the amount of powder to be drawn upwardly through the siphon tube into the venturi pump chamber 48 of the pump. The air pressure controlled and supplied to the atomization intake port 44 controls the ratio of air to powder mixture within the pump. Usually air line 58.6
2 has a pressure regulator (not shown) through which the air pressure supplied to the inlet port 44 controls the degree of vacuum drawn in the venturi pump chamber 48 of the pump, and Adjustments are made to control the relative amount of air to the powder mixture supplied to the venturi chamber through powder flow path 46.

During energization of the powder dispensing device, the air source 60 is connected to the inlet port 40.44 of the powder pump 18.20 and to the hopper 14.
．． High pressure air is supplied to the inlet ports 28 of the 16 air chambers 24 .

The high pressure air supplied to the inlet ports 2gK of the hoppers 14,16 operates to fluidize all of the powder 30 contained in the supply hopper 14 and the auxiliary hopper 16. Supply hopper 1
The fluidized powder 30 in the pump 18 is sucked upward through the siphon tube 50 by the venturi pump chamber 4B of the pump 18. The powder is then conveyed from the supply hopper pump 18 via a relatively long transfer hose 54 to the powder inlet 68 of the auxiliary hopper 16. The fluidized powder in the auxiliary hopper 16 is then transferred by the auxiliary pump 20 to the dispenser gun 12 via a relatively short hose 56. In practice, an excess amount of powder is transferred from the main hopper or feed hopper 14 to the auxiliary hopper 16, but this excess amount is greater than the capacity of all pumps 20. Consequently, excess fluidized powder returns to the feed hopper 14 through the inlet TO of the overflow tube 36. In this way, the level of powder in the auxiliary hopper 16 is always maintained at a constant level, ie at the upper edge level of the entry lower 0 of the overflow tube.

Powder pump 72 is coupled to overflow pipe 36 when gravity is too small to transport overflow powder to the main hopper. Such pumps are required in installations where there is a considerable distance between the two hoppers or where the main hopper is not located below the auxiliary hopper. If the powder pump 72 cooperates with the overflow tube 36, a ventilation hole (
(not shown) is provided.

Prior to the present invention, gun 1 was
Powder was directly transferred to 2.

No intermediate or auxiliary hopper 16 was provided in the apparatus. Applicants have discovered that the long hose extending from the supply hopper 18 to the gun and the constantly changing powder level in the supply hopper 14 together contribute to and create the problem of varying powder flow from the gun. I found out. In particular, it has been found that long hoses extending from the feed hopper pump to the gun result in numerous bends or loops where powder can accumulate and attempt to regulate flow through the long hose. . This restricted flow then reduces the pressure in the hose towards the gun and the resulting drop in powder volume is transferred from the supply hopper to the gun. The pressure behind the powder periodically created a restriction to the point where the powder broke the restriction, thereby dispensing a dense powder puff from the gun. This in turn temporarily increased the air flow and powder flow from the pump to the gun as the air flow through the hose increased rapidly. This restriction will then accumulate within the hose as it is released from rupture and the above process begins to repeat.

Applicant furthermore utilizes an auxiliary hopper 16 between the feed hopper and the gun, and preferably in close proximity to the gun, to eliminate the gun caused by the powder restriction in the hose.

It has been found that erroneous powder flow is minimized or nearly eliminated. Additionally, the applicant has provided an auxiliary hopper 16
It has also been discovered that, using the same method, the flow of powder from the gun 12 can be maintained constant by maintaining a constant powder level in the hopper that supplies the powder to the gun 12. The powder level in the feed hopper is subject to change, and this change, prior to the present invention, caused a change in powder flow from gun 12.

These powder flow changes were due to changes in the air pressure required to draw the powder from the fluidized bed of powder into the venturi pump chamber 48 of the pump. As the powder level in the fluidized bed decreases, greater vacuum is required to pull the powder from the fluidized bed into the venturi chamber.

Or powder level.

′:′ As the pressure increases, less vacuum is required.
However, if the venturi pump inside the pump
°.

The degree of vacuum does not change as the powder level within the fluidized bed changes. Instead, the powder flow from the pump changes. According to the invention of the present application, a source of variation in powder flow from the gun can be eliminated if the powder level in the auxiliary hopper is constant.

Although the applicant has given only one embodiment of the invention, it will be obvious to those skilled in the art to which the invention pertains that many changes and modifications can be made without departing from the spirit of the invention. It is. Accordingly, we believe that no limitations shall be imposed except in accordance with the scope of the appended claims.

[Brief explanation of the drawing]

The accompanying drawing is a perspective view of a powder injection device incorporating an auxiliary powder hopper and an auxiliary powder pump. [Explanation of symbols of main parts] 10 ・・・・・・・・・・・・ Powder injection device 12 ・・・・・・・・・・・・・・・
Main supply hopper 16 ・・・・・・・・・・・・・・・ Auxiliary supply hopper 18 ・・・・・・・・・・・・・・・・・・ Main air pump 20 ・・・・・・・・・・・・・・・ Auxiliary air pump 30 ・・・・・・・・・・・・・・・
Powder 36 ・・・・・・・・・・・・・・・
Overflow pipe 48 ・・・・・・・・・・・・
・・・ Venturi pump chamber 50 ・・・・・・・・・
...... Siphon tube 54 ......
・・・・・・・・・ Transfer duct 56 ・・・・・・・・・
・・・・・・・・・ Transfer hose 60 ・・・−・・・
・・・・・・・・・ Air An engraving of the original drawing (
(No change in content) Procedural amendment February 6, 1986 Michibu Uga, Commissioner of the Patent Office1, Indication of the case 1985 Patent Application No. 2793762, Title of invention Powder transfer device3, Amendment Relationship with the patent applicant's name: Nordson Corporation 4. Agent: 5. Subject of amendment: "Drawings" 6. Contents of amendment: (1) As per the attachment, we will submit one official drawing.

Claims (1)

[Claims] 1. An apparatus for dispensing solid particulate powder, the dispensing apparatus comprising: a main fluidized bed hopper having an interior chamber for receiving and fluidizing solid particulate powder material; an inlet port and an outlet; A main powder air pump with a port, the air pump having a low pressure venturi pump chamber and a powder flow path intersecting with the pump chamber, the powder flow path being connected to the main fluidized bed hopper via a siphon pipe. a main powder air pump having an inlet connected to the inner chamber of the main powder air pump; means for connecting the inlet port of the main powder pump to a source of high pressure air; an auxiliary fluidized bed hopper having an interior chamber of substantially smaller capacity; duct means connecting the outlet port of the main powder air pump to the interior chamber of the auxiliary fluidized bed hopper; and an inlet port and an outlet port. at least one auxiliary powder air pump having a low pressure venturi pump chamber and a powder flow path intersecting the venturi pump chamber, the powder flow path being connected to the powder flow path through a siphon tube. at least one auxiliary powder air pump having an inlet connected to the interior chamber of the auxiliary fluidized bed hopper; at least one powder distributor; and duct means connected to a distributor. 2. A powder stream further comprising a plurality of auxiliary powder pumps and a plurality of powder distributors, each of the auxiliary powder pumps being connected to the inner chamber of the auxiliary fluidized bed hopper via a siphon pipe. 2. A dispensing device as claimed in claim 1, characterized in that said auxiliary powder pumps each have an outlet port connected to one of said powder distributors via duct means. 3. The dispensing device of claim 1 further comprising means for maintaining a constant level of fluidized powder within said auxiliary fluidized bed hopper. 4. The means for maintaining the fluidized powder at a constant level in the auxiliary fluidized bed hopper comprises an overflow pipe extending between the auxiliary fluidized bed hopper and the main fluidized bed hopper; 2. The dispensing device of claim 1, wherein said auxiliary fluidized bed hopper has an inlet spaced upwardly from the bottom of said interior chamber of said auxiliary fluidized bed hopper. 5. An apparatus for dispensing a relatively constant flow of solid particulate powder material from a powder distributor, the dispensing apparatus comprising: a main hopper of relatively large capacity for fluidizing the solid particulate material; means for transferring the solid particulate material from the main hopper to the auxiliary hopper; means for fluidizing the solid particulate material in the auxiliary hopper; and means for transferring said solid particulate material from a hopper to said powder distributor. 6. The means for transferring the solid particulate material from the main hopper to the auxiliary hopper is configured to transfer a larger amount of solid particulate powder material to the auxiliary hopper than is transferred from the auxiliary hopper to the distributor. A dispensing device according to claim 5, which is operable. 7. said means for transferring said solid particulate powder from said main hopper to said auxiliary hopper is a first relatively long hose; and said means for transferring said solid particulate powder from said auxiliary hopper to said distributor; 6. Dispensing device according to claim 5, wherein the means is a second substantially shorter hose. 8. An apparatus for dispensing a relatively constant flow rate of solid particulate powder material from a plurality of powder distributors, the dispensing apparatus comprising: a relatively large capacity main hopper for fluidizing the solid particulate material; an auxiliary hopper of substantially smaller capacity; means for transferring the solid particulate material from the main hopper to the auxiliary hopper; and means for fluidizing the solid particulate material in the auxiliary hopper. means comprising a plurality of powder pumps, each of the powder pumps operable to transfer the solid particulate material from the auxiliary hopper to one of the powder distributors; A dispensing device for solid granular powder material, characterized by: 9. A method for maintaining a relatively constant flow of solid particulate powder material from a powder distributor, the method comprising: fluidizing the solid particulate material in a relatively large volume main hopper; transferring the solid particulate material from the main hopper into a substantially smaller volume auxiliary hopper; fluidizing the solid particulate material in the auxiliary hopper; and transferring the solid particulate material from the auxiliary hopper. and transferring a solid particulate powder material to a powder distributor. 10. transferring a larger amount of solid particulate material from the main hopper to the main hopper than is transferred from the auxiliary hopper to the distributor; 10. A method according to claim 9, comprising the step of transferring excess solid particulate material so as to maintain a constant fluidized powder level.