GB2078551A - Method and Apparatus for Spraying Powder - Google Patents
Method and Apparatus for Spraying Powder Download PDFInfo
- Publication number
- GB2078551A GB2078551A GB8119465A GB8119465A GB2078551A GB 2078551 A GB2078551 A GB 2078551A GB 8119465 A GB8119465 A GB 8119465A GB 8119465 A GB8119465 A GB 8119465A GB 2078551 A GB2078551 A GB 2078551A
- Authority
- GB
- United Kingdom
- Prior art keywords
- powder
- valve
- reservoir
- chamber
- opening
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
- 239000000843 powder Substances 0.000 title claims abstract description 59
- 238000005507 spraying Methods 0.000 title claims abstract description 20
- 238000000034 method Methods 0.000 title claims description 11
- 238000007789 sealing Methods 0.000 claims abstract description 5
- -1 polytetrafluoroethylene Polymers 0.000 claims description 6
- 238000007664 blowing Methods 0.000 claims description 5
- 229920001343 polytetrafluoroethylene Polymers 0.000 claims description 5
- 239000004810 polytetrafluoroethylene Substances 0.000 claims description 5
- 230000003213 activating effect Effects 0.000 claims description 4
- 238000004891 communication Methods 0.000 claims description 3
- 230000013011 mating Effects 0.000 claims 2
- 229910000831 Steel Inorganic materials 0.000 description 7
- 239000010959 steel Substances 0.000 description 7
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N Titan oxide Chemical compound O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 description 4
- 238000004519 manufacturing process Methods 0.000 description 3
- 229910052751 metal Inorganic materials 0.000 description 3
- 239000002184 metal Substances 0.000 description 3
- 238000010926 purge Methods 0.000 description 3
- XLOMVQKBTHCTTD-UHFFFAOYSA-N Zinc monoxide Chemical compound [Zn]=O XLOMVQKBTHCTTD-UHFFFAOYSA-N 0.000 description 2
- 230000000717 retained effect Effects 0.000 description 2
- 239000007921 spray Substances 0.000 description 2
- 239000004408 titanium dioxide Substances 0.000 description 2
- 230000004913 activation Effects 0.000 description 1
- 238000005054 agglomeration Methods 0.000 description 1
- 230000002776 aggregation Effects 0.000 description 1
- 230000008878 coupling Effects 0.000 description 1
- 238000010168 coupling process Methods 0.000 description 1
- 238000005859 coupling reaction Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 230000000994 depressogenic effect Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000007730 finishing process Methods 0.000 description 1
- 229940084430 four-way Drugs 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 239000012528 membrane Substances 0.000 description 1
- 239000003973 paint Substances 0.000 description 1
- 239000000049 pigment Substances 0.000 description 1
- 230000004044 response Effects 0.000 description 1
- 239000011787 zinc oxide Substances 0.000 description 1
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21C—MANUFACTURE OF METAL SHEETS, WIRE, RODS, TUBES OR PROFILES, OTHERWISE THAN BY ROLLING; AUXILIARY OPERATIONS USED IN CONNECTION WITH METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL
- B21C51/00—Measuring, gauging, indicating, counting, or marking devices specially adapted for use in the production or manipulation of material in accordance with subclasses B21B - B21F
- B21C51/005—Marking devices
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
- B05B—SPRAYING APPARATUS; ATOMISING APPARATUS; NOZZLES
- B05B7/00—Spraying apparatus for discharge of liquids or other fluent materials from two or more sources, e.g. of liquid and air, of powder and gas
- B05B7/14—Spraying apparatus for discharge of liquids or other fluent materials from two or more sources, e.g. of liquid and air, of powder and gas designed for spraying particulate materials
- B05B7/1481—Spray pistols or apparatus for discharging particulate material
- B05B7/1486—Spray pistols or apparatus for discharging particulate material for spraying particulate material in dry state
Landscapes
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Nozzles (AREA)
- Coating Apparatus (AREA)
- Application Of Or Painting With Fluid Materials (AREA)
Abstract
In the spraying of dry powder from a fluidized bed powder reservoir 10 through an injector pump 12 having a chamber which communicates with the reservoir through valve-controlled openings 34, 36 to admit fluidized powders and in which air is blown through said pump to flow said fluidized powders through a barrel assembly 16, a more concentrated quantity of powder can be sprayed at high velocity for a greater distance by opening the valve to admit a charge of powder then closing the valve, thereby effectively sealing the chamber, with a fixed quantity of powder therein, from the reservoir atmosphere before air is blown through the chamber to discharge the fixed quantity of powder therefrom. <IMAGE>
Description
SPECIFICATION
Method and Apparatus for Spraying Powder
The present invention relates to a method and apparatus for spraying powder. During various steel finishing processes wherein steel is shaped or formed while it is hot, it is often desirable to mark the hot steel for, for example, identification or marking defects. Since the steel is hot, marking materials such as paint cannot be used as these would quickly burn off. Hence the practice has been to apply dry powder pigments or metallic powders onto the hot steel surface, preferably by pneumatically spraying such powders.
Although there is a selection of commercially available equipment for spraying dry powders, such prior art equipment has not been completely suitable for spraying the types of powders used to mark hot steel. That is to say, the powders most commonly preferred for marking hot steel, for example, titanium dioxide or zinc oxide, tend to agglomerate when pneumatically pumped, and thus frequently plug and clog the powder spraying equipment.
United States Patent Specification No.
3,899,131 discloses a method and apparatus for spraying agglomerating powders such as titanium dioxide wherein the agglomeration problems are somewhat reduced. Although that method and apparatus are currently being used successfully in some commercial operations, they have certain limitations which render the practice unsuitable under certain conditions such as the marking of such hot products as bars, billets or slabs moving at high line speeds, that is, greater than 1000 feet per minute. Specifically, the impact of the marking powder on fast moving products has not been sufficient to ensure permanent adhesion to the product, and/or the volume of the marking powder reaching the product does not provide a marking of adequate contrast for visibility at remote distances.Indeed, the system requires close proximity of the marking apparatus to a stationary, or slow moving product in order to assure adequate contrast, but this is not always possible on some production lines as the spraying apparatus soon becomes damaged, or it is not possible to stop or slow the production line.
According to the present invention, there is provided a method of pneumatically spraying powder through an apparatus comprising a fluidized bed powder reservoir, a pump housing attached within said reservoir and having a chamber therein communicating with a barrel assembly and at least one opening in a wall thereof affording communication between the chamber and the interior of said reservoir, a valve for selectively opening and closing the or each said opening, a gas-tight seal between said valve and said housing for sealing said chamber with respect to the interior of said reservoir when the valve is closed, and means for blowing a gas through said housing and said barrel assembly: the method comprising activating said fluidized bed powder reservoir to fluidize powder therein, opening said valve to admit a quantity of fluidized powder through the or each opening into said chamber, closing said valve to isolate said quantity of fluidized powder within said chamber, and activating said blowing means to blow said quantity of fluidized powder out through said barrel assembly.
The invention also provides an apparatus, as specified above, for carrying out the method.
The invention is further described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is an elevation view in partial section showing an apparatus for spraying dry powder in accordance with this invention,
Figure 2 is a plan view in partial section of the apparatus shown in Figure 1 taken on line Il-Il of
Figure 1,
Figure 3 is a schematic diagram of the pneumatic control circuit for operating the apparatus shown in Figures 1 and 2,
Figure 4 is a sectional view of an improved nozzle design pursuant to one embodiment of this invention, and
Figure 5 is a sectional view of another embodiment of the improved nozzle design.
With reference to the drawings, the apparatus comprises a fluidized bed powder reservoir 10, a pump assembly 12, an air cylinder 14 and a barrel assembly 16. The pump 12 is supported as a single unit by a framework consisting of two side bars 20, a front plate 22 and a rear plate 24. The framework is attached within reservoir 10 by bolts 26 and 28. Such an arrangement isolates the pump housing from the outside atmosphere.
The pump itself consists of a tubular housing 30 welded to front plate 22, and is provided with a pair of elongate, opposed openings 34 and 36. A pump cylinder 38, consisting of a hollow metal barrel coated with polytetrafluoroethylene is slidably mounted within a polytetrafluoroethylene sleeve 40 which is retained within housing 30 by a keeper plate 42. Cylinder 38 thus acts as a valve closure member for selectively opening and closing openings 34 and 36. The forward end of cylinder 38 is fitted with a replaceable nozzle 44.
In the closed position as shown, nozzle 44 seats against a hollow cylindrical muzzle 46 which is fitted into the forward end of housing 30. Muzzle 46 is also made of polytetrafluoroethylene.
Attached to the forward end of the housing 30 by means of threaded nut 48, is the replaceable barrel assembly 16, which consists of a metal tube 50 having an adapter ring 52 soldered to its inside end. Tube 50 contains a polytetrafluoroethylene sleeve 54 retained therein by a metal cap 56 soldered to the forward end of tube 50 and having an open discharge bore therethrough.
The rearward end of cylinder 38 is fitted with an angled adapter 60 for accommodating an air inlet supply hose 62, and for attachment of a push rod 64. Push rod 64 extends through the rear wall of reservoir 10 with its outer end connected to air cylinder rod 66 of the air cylinder 14 by coupling 68. A bellows 70 is supported on rod 64 and attached to the rear plate 24. Accordingly, reciprocal activation of air cylinder 14 will cause cylinder 38 to reciprocate between the closed position as shown, and an open position wherein the inside of-housing 30 is exposed to the atmosphere within reservoir 10 through openings 34 and 36.
For operation, cylinder 14 is actuated to the closed position and the powder to be sprayed through barrel assembly 1 6 is placed into reservoir 10 and fluidized by air passing through a porous membrane 72. Thereafter, purging air or other gas is admitted at low velocity through hose 62. This low velocity purging gas flows through cylinder 38, muzzle 46 and barrel assembly 16.
The apparatus is thus activated and ready to spray powders on demand. To spray powders pursuant to prior art practices, the velocity of air or gas admitted through hose 62 would be increased as cylinder 38 is opened by air cylinder 14 to admit fluidized powder within housing 30. Thus admitted, the powder would be pneumatically ejected through muzzle 46 and barrel assembly
16. When it is desired that powder spraying be discontinued, air cylinder 14 would be activated to close cylinder 38 as the air admitted therethrough is reduced back to a low velocity purging blow to keep the passageway clear of accumulated powders.
Pursuant to the prior art practice therefore,
cylinder 38 would remain in the open position throughout the entire period that of spraying. In contrast thereto, the present invention requires that cylinder 38 be closed when spraying. That is, cylinder 38 is opened just prior to the blow in order to admit the desired quantity of fluidized powder within housing 30. Thereafter, cylinder 38 is closed, trapping a small quantity of fluidized powder within cylinder 38. When cylinder 38 is completely closed, the small quantity of powder within cylinder 38 is blown through barrel
assembly 1 6 using a relatively low pressure, for
example, 40 psig, to effect a substantially higher
rate of speed than is possible with an open cylinder 38.Although a significantly smaller
volume of powder is so blown, its greater speed
provides a greater impact force on a more
concentrated area of impact. The powder as so
projected has a stronger adhesion on the target
area and its more concentrated nature renders a
more visible area. In addition, the powder can be sprayed over a greater distance and still leave a
readily visible mark, even on products traveling at
line speeds in excess of 1000 feet per minute.
In order to achieve a high velocity of powder through barrel assembly 16, it is necessary that the seal between nozzle 44 and muzzle 46 be very effective. Any leakage therebetween will cause turbulence in muzzle 46 and reduce velocity. Referring to Figure 4, the sealing face of
nozzle 44 is tapered to provide a contact angle a of from 400 to 500. In the alternative, a spherical contact surface may be provided as shown in
Figure 5 where the tangent to radius R at the contact point with nozzle 44 is between 400 and 500.
The interior surfaces of muzzle 46 and barrel assembly 16 should be streamlined to minimize turbulence, that is, sharp corners on any orifices should be removed to avoid turbulence which would tend to reduce air velocity. The ideal velocity should approach but should not exceed sonic velocity.
The pneumatic control circuitry of the apparatus is shown in Figure 3. A main air supply line 76 from a manifold 74 connects to a fourway valve 78 which supplies air to the air cylinder 14 either at its forward end 80 or rearward end 82 depending on the position of valve 78.
Solenoid 84, which activates valve 78, is energized by any suitable power supply 86 through a spring return switch 88. A second solenoid valve 90 is provided on air line 76 which supplies air supply to pump inlet supply hose 62.
Solenoid 90 is energized by any suitable power supply 92 through a spring return switch 94. Air is continuously supplied to the fluidized bed reservoir 10 via line 96 through regulator 98.
In operation, when reservoir 10 is fluidized, the operator may depress switch 88 which sends air to inlet 80 on air cylinder 14. This causes cylinder 38 to be retracted, thereby admitting fluidized powder into housing 30. Release of switch 88 causes air cylinder to reverse its direction, thus closing cylinder 38 trapping a metered or fixed quantity of powder in housing 30. Switch 94 is then depressed which opens solenoid valve 90 and permits full air supply pressure to suddenly surge through hose 62 and cylinder 38 projecting the fixed quantity of powder through barrel assembly 1 6. In an actual production line application, switches 88 and 94 are usually operated automatically in sequence in response to a signal for spraying powder.
Claims (6)
1. A method of pneumatically spraying powder through an apparatus comprising a fluidized bed powder reservoir, a pump housing attached within said reservoir and having a chamber therein communicating with a barrel assembly and at least one opening in a wall thereof affording communication between the chamber and the interior of said reservoir, a valve for selectively opening and closing the or each said opening, a gas-tight seal between said valve and said housing for sealing said chamber with respect to the interior of said reservoir when the valve is closed, and means for blowing a gas through said housing and said barrel assembly; the method comprising activating said fluidized bed powder reservoir to fluidize powder therein, opening said valve to admit a quantity of fluidized powder through the or each opening into said chamber, closing said valve to isolate said quantity of fluidized powder within said chamber, and activating said blowing means to blow said quantity of fluidized powder out through said barrel assembly.
2. An apparatus for pneumatically spraying powder, comprising a fluidized bed powder reservoir, a pump housing attached within said
reservoir and having a chamber therein scommunicating with a barrel assembly and at
least one opening in a wall thereof affording
communication between the chamber and the
interior of said reservoir, a valve for selectively
opening and closing the or each said opening, a
gas-tight seal between said valve and said
housing for sealing said chamber with respect to
the interior of said reservoir when the valve is
closed, and means for blowing a gas through said
housing and said barrel assembly.
3. An apparatus as claimed in claim 2, in which
said valve is a nozzle slidably mounted in said
housing and said gas-tight seal comprises a
polytetrafluoroethylene muzzle secured within the forward end of said chamber and contacted by said nozzle on closure of the valve at a mating surface tapered at 400 to 500 to the direction of sliding of the nozzle.
4. An apparatus as claimed in claim 3, in which said nozzle and muzzle contact along mating partspherical surfaces, a tangent to the part-spherical surfaces at the contact area being inclined at 400 to 500 to the direction of sliding of the nozzle.
5. A method of pneumatically spraying powder substantially as hereinbefore described with reference to the accompanying drawings.
6. An apparatus for pneumatically spraying powder, constructed and adapted to operate substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US16285280A | 1980-06-25 | 1980-06-25 |
Publications (2)
Publication Number | Publication Date |
---|---|
GB2078551A true GB2078551A (en) | 1982-01-13 |
GB2078551B GB2078551B (en) | 1984-05-16 |
Family
ID=22587396
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
GB8119465A Expired GB2078551B (en) | 1980-06-25 | 1981-06-24 | Method and apparatus for spraying powder |
Country Status (7)
Country | Link |
---|---|
JP (1) | JPS5735968A (en) |
AU (1) | AU7216381A (en) |
CA (1) | CA1169718A (en) |
DE (1) | DE3124870A1 (en) |
FR (1) | FR2485401A1 (en) |
GB (1) | GB2078551B (en) |
IT (1) | IT8167880A0 (en) |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GB2354464A (en) * | 1999-09-24 | 2001-03-28 | Takao Kinzoku Kogyo Kk | Defect marking apparatus. |
Families Citing this family (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
FR3140288A1 (en) * | 2022-09-29 | 2024-04-05 | Safran Nacelles | Nozzle, dynamic projection device, coating method and repair method associated therewith |
Family Cites Families (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2564896A (en) * | 1946-06-17 | 1951-08-21 | Binks Mfg Co | Sound deadening gun |
FR2233257B1 (en) * | 1973-06-18 | 1976-05-07 | Air Ind | |
US3913795A (en) * | 1974-07-29 | 1975-10-21 | Eppco | Pulsating powder metering and dispensing device |
-
1981
- 1981-06-10 CA CA000379432A patent/CA1169718A/en not_active Expired
- 1981-06-24 AU AU72163/81A patent/AU7216381A/en not_active Abandoned
- 1981-06-24 DE DE19813124870 patent/DE3124870A1/en not_active Withdrawn
- 1981-06-24 GB GB8119465A patent/GB2078551B/en not_active Expired
- 1981-06-24 IT IT8167880A patent/IT8167880A0/en unknown
- 1981-06-25 FR FR8112535A patent/FR2485401A1/en active Pending
- 1981-06-25 JP JP9762181A patent/JPS5735968A/ja active Pending
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GB2354464A (en) * | 1999-09-24 | 2001-03-28 | Takao Kinzoku Kogyo Kk | Defect marking apparatus. |
Also Published As
Publication number | Publication date |
---|---|
IT8167880A0 (en) | 1981-06-24 |
CA1169718A (en) | 1984-06-26 |
JPS5735968A (en) | 1982-02-26 |
FR2485401A1 (en) | 1981-12-31 |
AU7216381A (en) | 1982-01-07 |
GB2078551B (en) | 1984-05-16 |
DE3124870A1 (en) | 1982-03-18 |
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Legal Events
Date | Code | Title | Description |
---|---|---|---|
PCNP | Patent ceased through non-payment of renewal fee |