[go: up one dir, main page]

WO2008150790A1 - Pompe de revêtement par pulvérisation de haute densité et buse pour produire un motif de pulvérisation étroit et dense - Google Patents

Pompe de revêtement par pulvérisation de haute densité et buse pour produire un motif de pulvérisation étroit et dense Download PDF

Info

Publication number
WO2008150790A1
WO2008150790A1 PCT/US2008/064962 US2008064962W WO2008150790A1 WO 2008150790 A1 WO2008150790 A1 WO 2008150790A1 US 2008064962 W US2008064962 W US 2008064962W WO 2008150790 A1 WO2008150790 A1 WO 2008150790A1
Authority
WO
WIPO (PCT)
Prior art keywords
powder
nozzle
cross
hose
coating system
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.)
Ceased
Application number
PCT/US2008/064962
Other languages
English (en)
Inventor
Michael Ross Sanner
Robert Foster
Terrence M. Fulkerson
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Nordson Corp
Original Assignee
Nordson Corp
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Nordson Corp filed Critical Nordson Corp
Publication of WO2008150790A1 publication Critical patent/WO2008150790A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

Links

Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05B—SPRAYING APPARATUS; ATOMISING APPARATUS; NOZZLES
    • B05B5/00—Electrostatic spraying apparatus; Spraying apparatus with means for charging the spray electrically; Apparatus for spraying liquids or other fluent materials by other electric means
    • B05B5/025—Discharge apparatus, e.g. electrostatic spray guns
    • B05B5/03—Discharge apparatus, e.g. electrostatic spray guns characterised by the use of gas, e.g. electrostatically assisted pneumatic spraying
    • B05B5/032—Discharge apparatus, e.g. electrostatic spray guns characterised by the use of gas, e.g. electrostatically assisted pneumatic spraying for spraying particulate materials
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05B—SPRAYING APPARATUS; ATOMISING APPARATUS; NOZZLES
    • B05B1/00—Nozzles, spray heads or other outlets, with or without auxiliary devices such as valves, heating means
    • B05B1/14—Nozzles, spray heads or other outlets, with or without auxiliary devices such as valves, heating means with multiple outlet openings; with strainers in or outside the outlet opening

Definitions

  • the inventions involve a powder coating system having a high-density pump which provides a relatively dense stream of powder coating material to a spray gun that is designed to spray a narrow dense phase powder spray pattern useful for coating recesses and corners of products such as the inside of file cabinets, for example.
  • US Patent Nos. 6,840,463 and 6,622,937 are hereby incorporated by reference in their entirety.
  • a prior art pump is shown that supplies powder to a spray gun such as, for example, the gun shown Fig. 2 from US Patent 6,622,937.
  • the pump is commonly known as a venturi type pump.
  • compressed air is supplied to the pump which creates a low-pressure condition in the pump to pull powder from a power supply hopper into the pump and then push the powder through a hose to the spray gun.
  • One problem with this type of pump and gun in a powder coating system is that it is difficult, and realistically not possible, to spray a narrow dense spray pattern from the spray gun.
  • FIG. 1 Pending United States patent application serial number 10/711,434 (the "434 application") published as US patent application publication number 2005/0126476 on June 16, 2005, is also fully incorporated herein by reference.
  • the system shown therein includes a dense phase pump 402a that supplies a relatively dense stream of powder coating material through a relatively small diameter hose 406a to a spray gun 20a.
  • the pump is shown in detail in Fig. 1OB from the published patent application.
  • the pump has pinch valves 480, 481 that supply powder to powder transfer chambers 438, 440. Focusing on chamber 438, for example, suction is applied to the chamber to pull powder into the chamber from a powder supply through a pinch valve at the inlet to the chamber.
  • That pinch valve is then closed.
  • positive pressure is applied to the powder transfer chamber 438 while a pinch valve at the outlet of the chamber is opened to allow powder to be pushed out of the chamber through the hose 406a towards the spray gun 20a.
  • Two chambers 438, 440 are used in combination so that while one chamber is drawing powder in, the other chamber is pushing powder out, and vice versa, to provide a relatively constant supply of dense phase powder through the hose to the spray gun 20a.
  • the pump shown in Fig. 1OB of the published application is akin to a positive displacement pump meaning that once powder is pushed out of the chamber, it can only go in the direction through the hose to the spray gun.
  • the reason is that when the powder is pushed out of the chamber 438 (or 440) only the pinch valve that controls the flow from the chamber 438 to the gun is open.
  • the pinch valve that controls the flow of powder from the powder supply to the chamber 438 is closed. Consequently, powder cannot be pushed from the chamber 438 back towards the powder supply.
  • it is not possible for the pump to "reverse direction” like is possible with a Venturi pump as described above.
  • a nozzle for a spray gun used with a dense phase powder pump includes at least one flow passage that has at least a portion that is cylindrical. In an alternative embodiment, a plurality of such flow passages may be used.
  • the flow passage has an inlet and an outlet that have the same cross-sectional area
  • the combined cross-sectional area of a plurality of flow passages is equal to or greater than the cross-sectional area of a hose that supplies powder to the nozzle
  • each flow passage has a cross-sectional area that is small relative to the cross-sectional area of a hose that supplies powder to the nozzle, with one embodiment thereof being flow passages that each have a cross-sectional area no greater than twenty-five percent of the hose cross-sectional area.
  • the inventions further contemplate use of such nozzles with a spray gun in a dense phase powder coating system.
  • Fig. 1 is an exemplary spray gun suitable for use with the present inventions including one embodiment thereof, shown in longitudinal partial cross-section;
  • Fig. 2 is a front perspective of the spray gun of Fig. 1;
  • FIG. 3 is an enlarged illustration of the nozzle end of the spray gun of Fig. 1 ;
  • Figs. 4, 4A and 4B are sectional views of the spray nozzle of Figs. 1-3.
  • powder coating material is supplied from a powder pump and supply arrangement 50 through a powder feed hose 3 to the spray gun 1.
  • the hose 3 typically will be a small diameter hose compare to a hose such as would typically be used to connect a Venturi pump with the spray gun because a low density or dilute phase powder hose is primarily filled with transport air as described above, whereas a dense phase hose 3 is primarily filled with powder.
  • a dilute phase powder hose is typically a 0.500 inch diameter hose, whereas the dense phase hose 3 is typically a 0.236 inch diameter hose or about less than half the diameter.
  • a dense phase hose typically will have a diameter not greater than about 0.3 inches.
  • the density of the powder in a dilute phase system or hose is typically 0.0018g/cc, whereas the density of the powder in hose 3 for a dense phase system is typically O.OO33g/cc at a powder delivery rate of 225 g/min.
  • a venturi pump type system typically 2 - 4 cubic feet per minute (CFM) of air are sprayed from the spray nozzle of a gun in order to transport the powder through the nozzle, whereas in a typical system utilized with the present invention, .7 - .9 CFM of air are typically sprayed through the nozzle in order to transport the powder through the nozzle.
  • the 50 controls powder flow from a powder supply 52 to the gun 1 by the use of pneumatically actuated pinch valves 54, such as for example, bladder type pinch valves that open and close in response to external pressurized air.
  • the powder is pumped to the gun 1 via one or more powder pump or transfer chambers 56.
  • the chamber 56 receives positive and negative pressure 58, 60 in a controlled sequence whereby under negative pressure powder is pulled into the chamber 56 and under positive pressure powder is pushed out of the chamber 56 into the hose 3 to the spray gun 1.
  • the pinch valves 54 selectively operate to seal the chamber 56 from the supply 52 when the chamber is under positive pressure so that powder is only able to flow to the spray gun 1.
  • the pinch valves 54 also selectively operate to seal the chamber 56 from the gun when the chamber is under negative pressure so that powder is only able to flow into the chamber from the supply. Accordingly, the dense phase system operates with a positive displacement pump that in this embodiment comprises the pinch valves 54, the chamber(s) 56 and the pneumatic sources 58, 60.
  • An electrical power and control system 62 may be used to control operation of the gun 1, as well as the supply and pump system 50.
  • the spray gun may be an electrostatic spray gun, although the inventions herein are not limited to electrostatic spray technologies.
  • the spray gun 1 may thus include a multiplier 64 which receives a low input voltage and produces a high output voltage to an electrode 66 having an electrode tip 9 that is preferably but not necessarily disposed in the center of the output spray pattern 70 produced by the gun 1.
  • Actuation and control of the spray gun and a coating operation may be effected by one or more trigger mechanisms 72 on the gun.
  • Automatically triggered guns may alternatively be used, such as may be typically mounted on a robotic arm (not shown). Further details of a complete dense phase system including the gun 1, the supply and pump arrangement 50 and the power and control system 62 are provided in the above referenced '434 publication. Other systems may alternatively be used as needed.
  • Figs. 4, 4 A and 4B which will be described in more detail below, illustrate a spray nozzle 5 in an embodiment of a closed end cap 100 having a number of powder flow passages 7 extending through the cap 100.
  • a spray nozzle 5 were put on a dilute phase spray gun, for example, a great deal of back pressure would be created in the hose extending from the Venturi pump to the spray gun. The result would be that very little or no powder would be sprayed from the nozzle. It is likely that so much back pressure would be created, that more flow resistance would be created between the pump and the gun than between the pump and the powder supply hopper.
  • These streams may form like small diameter ropes of dense powder flow from the passages 7, with one stream for each passage 7.
  • these streams may recombine a distance from the outlet ends 8 of the passages 7, such as for example, one inch. This distance is not critical and may be achieved by controlling the angle of the passages 7 relative to a centerline X of the nozzle, as well as the cone angle as will be described herein below.
  • the streams may recombine along or near the cenlerline X of the nozzle but this is optional.
  • the tight narrow stream pattern of dense powder helps to make the spray pattern less susceptible to air flow and movement of the nozzle, such as for example when the nozzle is on a gun that is moved by a robotic arm.
  • the nozzle 5 may have a number of powder flow passages 7 with outlet ends 8 surrounding the charging electrode tip 9. Although ten passages are shown in Fig. 2, the number of passages may be selected based on the overall spray pattern shape desired. A single stream pattern using one passage 7 may even be used.
  • the nozzle 5 may be provided with an optional flat 102 on its forward end to facilitate positioning the electrode tip 9, but alternatively the forward end of the nozzle 5 may have any desired profile.
  • a portion 104 of the nozzle face may be provided to run the electrode 9 through the nozzle body interior (see Fig. 3), but alternatively the electrode may be routed through a rib along the outer surface of the nozzle 5, for example.
  • the nozzle 5 may include an interior passage 106 that receives the electrode 66 which extends forward to the electrode tip 9.
  • the electrode 66 may include a spring like contact 108 that contacts an electrically conductive ring 110 that makes an electrical connection to a contact 112 from the power supply (not shown).
  • the nozzle 5 may be retained on the spray gun by any suitable means, in this example a threaded ring 114 that pulls the nozzle up snug against the gun body when the ring 114 is tightened.
  • a nozzle insert 116 mates with a forward end of a hose connector 118 that slips into the back end of the insert 116.
  • the hose connector 118 may include a barbed extension 120 that the powder hose 3 is pushed onto.
  • An optional retaining ring 122 cooperates with the hose connector 118 to keep the powder flow path tight and sealed.
  • the hose connector 118 may include a throat having a reduced diameter portion 111 as illustrated. This reduced diameter will tend to create turbulence and re-direct powder towards the center of the connector 118 before the powder is introduced into the main flow volume of the nozzle. This helps to direct the dense tight powder flow towards the tip of the cone (128) for better diffusion and distribution of powder to all the flow passages 7.
  • the nozzle insert 116 also retains an optional air permeable filter 124 in the shape of a truncated cone. This filter allows air to be added to the powder stream inside the nozzle to facilitate dispersion and atomizing/fluidizing the powder, and also to direct the powder flow generally along the axis X. Air is provided through air passages 126 in the insert 116 which communicate with a flow of pressurized air in the gun body (not shown). [0023]
  • the nozzle 5 may include an optional conical projection 128 that extends rearward from the closed end cap 130 of the nozzle. By closed end cap is meant that the only outlet for powder or air through the nozzle is through the small powder flow passages 7.
  • the optional conical projection 128 may have a different profile, including but not limited to a frusto-conical shape, a rounded tip and so on.
  • the conical projection 128 may be used to help shape the spray pattern 70 produced by the nozzle, particularly the width of the pattern.
  • the cone angle a (referenced to the centerline X of the nozzle) may be selected to minimize impact fusion while at the same time directing a more uniformly dispersed powder flow outward toward the powder flow passages 7.
  • the powder stream that exits the connector 118, along with the assist of air from the optional filter 124, tends to be a cylinder shape of dense phase powder, so that the cone 128 helps to disperse and diffuse that flow pattern more uniformly towards the passages 7.
  • an optional annular recess or groove 132 may be formed (Fig. 3).
  • the powder flow passages 7 may then be machined from the recess 132, through the closed end cap 130 to the outlet ends or orifices 8.
  • each passage 7 in the Fig. 4 view, only two passages 7a and 7b are visible) may be formed as simple round through holes of uniform diameter from an inlet end 10 to the outlet end 8.
  • the selected geometry, shape and configuration of the passages 7 are not limited to cylinder shapes, but may be any shape including but not limited to square, triangular, octagonal, oval and so on.
  • each passage 7 may be formed at an angle ⁇ (also relative to the centerline X of the nozzle). This angle may be selected based on the size of the desired spray pattern 70 (for example, the width of the overall spray pattern 70 produced from the nozzle 5), the amount of dispersion of the pattern desired, the location that the streams recombine, if at all, and so on.
  • the angle ⁇ may equal the angle a, which avoids the presence of a lip or radius at the juncture between the groove 132 and the inlet 10 of each passage, hi the illustrated embodiments, however, the angle a is slightly greater than the angle ⁇ , so that a small radius 134 is present.
  • the inlets of the passages 7, as well as the angle ⁇ , may be selected as needed to reduce impact fusion effects of this radius, hi the Fig. 4 embodiment the angle ⁇ is positive meaning that the powder streams from the nozzle will be diverging to some extent, even though the overall design may have them recombining a distance from the nozzle.
  • the angle ⁇ may alternatively be negative (again with reference to the centerline X as drawn in Fig.
  • each passage 7 is preferably but not necessarily kept uniform from inlet to outlet in order to maintain a consistent velocity of powder through each passage and for all the passages. If all the passages also preferably though not necessarily have the same shape and cross-sectional area, then the overall spray pattern will tend to be uniform with a consistent powder distribution in all the streams.
  • the total combined cross-sectional areas of the passages 7 (based on the inside diameter of each passage wall) be equal to or greater than the cross-sectional area of the hose 3 (based on the hose inside diameter). If the passages had a total cross-sectional area smaller than the hose area, there could be undesired acceleration of the powder.
  • the cross-sectional area is about .0467 in 2 so that if there are ten circular passages 7 each passage would have a cross-sectional area of at least .00467 in and a diameter of about .09 inches for the passages 7 to have about the same or somewhat greater cross-sectional combined area as the hose 3. If the combined cross- sectional area of the passages 7 is somewhat greater than the hose cross-sectional area, then the powder flow will decelerate as it passes through the nozzle. Whether such deceleration is needed will depend on overall system design and spray pattern criteria. A typical nozzle for a dense phase powder coating system using ten passages 7 will have passage diameters in the range of about .08 inches to about 0.1 inches.
  • each passage 7 will typically have a length that is substantially longer than the diameter, for example a length to width ratio of about 3:1 or more.
  • a typical length for a passage 7 is about 0.29 inches. This can help assure a uniform narrow flow of dense phase powder from the passage.
  • each passage will have a cross-sectional area of about ten percent of the cross-sectional area of the hose 3.
  • each passage will be determined by the size and number of passages 7 used, it may typically be that each passage will be no more than about ten to twenty-five percent, and preferably about fifteen percent, of the hose cross-sectional area for narrow dense phase powder streams 70. All of the above exemplary numbers, dimensions, ratios and so on are intended to be exemplary and non-limiting as the actual values will depend on overall system, nozzle and gun design criteria. But, these example demonstrate the overall concept of using one or more narrow passages through a closed end cap nozzle to produce narrow well-defined and stable dense phase spray patterns.
  • the powder is sprayed through the nozzle of the present invention with less transport air, the powder is sprayed from the nozzle at a much lower velocity and thus the powder spray pattern does not expand like spray patterns of the prior art. Therefore, the spray pattern remains somewhat tubular and constant in diameter as compared to the conical expanding spray patterns of prior art spray guns.
  • the spray gun can be mounted on a robot, for example, and moved at a higher speed relative to the product while still achieving good quality powder coating than was possible with prior art spray systems. This improves the production efficiency.
  • each of the flow passages could be parallel to the longitudinal centerline of the nozzle, or angled inwardly relative to the longitudinal centerline of the nozzle, or any combination thereof, to create an even a narrower spray pattern or another desired spray pattern.

Landscapes

  • Nozzles (AREA)
  • Electrostatic Spraying Apparatus (AREA)

Abstract

L'invention concerne une buse (5) devant être utilisée avec un pistolet de pulvérisation (1) d'un système d'application de poudre en phase dense qui comprend un capuchon fermé (100, 130) avec un certain nombre de passages d'écoulement (7) de poudre qui conduisent à un motif de pulvérisation de poudre dense et étroit. Les passages d'écoulement (7) peuvent avoir une forme transversale quelconque, les passages cylindriques étant un exemple. Une buse typique (5) peut avoir un ou plusieurs de ces passages, la buse en exemple (5) utilisant dix desdits passages.
PCT/US2008/064962 2007-05-29 2008-05-28 Pompe de revêtement par pulvérisation de haute densité et buse pour produire un motif de pulvérisation étroit et dense Ceased WO2008150790A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US93213607P 2007-05-29 2007-05-29
US60/932,136 2007-05-29

Publications (1)

Publication Number Publication Date
WO2008150790A1 true WO2008150790A1 (fr) 2008-12-11

Family

ID=39829108

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/US2008/064962 Ceased WO2008150790A1 (fr) 2007-05-29 2008-05-28 Pompe de revêtement par pulvérisation de haute densité et buse pour produire un motif de pulvérisation étroit et dense

Country Status (1)

Country Link
WO (1) WO2008150790A1 (fr)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2014154373A1 (fr) * 2013-03-26 2014-10-02 Gema Switzerland Gmbh Pistolet pulvérisateur, pour revêtement par pulvérisation d'objets au moyen d'une poudre de revêtement
EP2408568B1 (fr) 2009-03-19 2016-12-21 Dürr Systems AG Ensemble d'électrodes pour un pulvérisateur électrostatique
US9745148B2 (en) 2013-04-03 2017-08-29 Gema Switzerland Gmbh Powder conveyor and associated operating method

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0516462A1 (fr) * 1991-05-29 1992-12-02 Nordson Corporation Revêtement par poudrage électrostatique
US6247657B1 (en) * 1999-05-28 2001-06-19 Delphi Technologies, Inc. Power gun spray nozzle and method
US20050126476A1 (en) * 2003-11-05 2005-06-16 Nordson Corporation Improved particulate material application system
US20050229845A1 (en) * 2003-08-18 2005-10-20 Nordson Corporation Particulate material applicator and pump

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0516462A1 (fr) * 1991-05-29 1992-12-02 Nordson Corporation Revêtement par poudrage électrostatique
US6247657B1 (en) * 1999-05-28 2001-06-19 Delphi Technologies, Inc. Power gun spray nozzle and method
US20050229845A1 (en) * 2003-08-18 2005-10-20 Nordson Corporation Particulate material applicator and pump
US20050126476A1 (en) * 2003-11-05 2005-06-16 Nordson Corporation Improved particulate material application system
EP1728558A2 (fr) * 2005-05-31 2006-12-06 Nordson Corporation Pistolet de pulvérisation de poudre et pompe

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP2408568B1 (fr) 2009-03-19 2016-12-21 Dürr Systems AG Ensemble d'électrodes pour un pulvérisateur électrostatique
US9901942B2 (en) 2009-03-19 2018-02-27 Duerr Systems Gmbh Electrode assembly for an electrostatic atomizer
US10464084B2 (en) 2009-03-19 2019-11-05 Dürr Systems GmbH Electrode assembly for an electrostatic atomizer
EP2408568B2 (fr) † 2009-03-19 2019-12-25 Dürr Systems AG Ensemble d'électrodes pour un pulvérisateur électrostatique
WO2014154373A1 (fr) * 2013-03-26 2014-10-02 Gema Switzerland Gmbh Pistolet pulvérisateur, pour revêtement par pulvérisation d'objets au moyen d'une poudre de revêtement
US10159994B2 (en) 2013-03-26 2018-12-25 Gema Switzerland Gmbh Spray-coating gun for spray coating objects with coating powder
US9745148B2 (en) 2013-04-03 2017-08-29 Gema Switzerland Gmbh Powder conveyor and associated operating method
US10604360B2 (en) 2013-04-03 2020-03-31 Gema Switzerland Gmbh Dense phase powder pump and corresponding operating method

Similar Documents

Publication Publication Date Title
US8123147B2 (en) Powder coating system and components
JP6908215B2 (ja) 加圧空気アシスト式フルコーンスプレーノズル組立体
CN103619486B (zh) 用于容器的密相粉末涂覆系统
US9302281B2 (en) High swirl air cap
US8783208B2 (en) Powder hopper with quiet zone, a combination of a powder hopper and a powder spray gun and a method of operating a powder hopper
US20180311688A1 (en) Powder gun configurable for supply from venturi or dense phase pump
US20100038101A1 (en) Fire extinguishment systems and nozzles
WO2008150790A1 (fr) Pompe de revêtement par pulvérisation de haute densité et buse pour produire un motif de pulvérisation étroit et dense
EP1066116B1 (fr) Pistolet pulverisateur a commande commune de soupape de fluide et d'air
JP2000254554A (ja) 微粒化ノズル
JP2008161789A (ja) 粉体塗装スプレーガンの調節弁装置
JP3574934B2 (ja) 静電粉体塗装における加速エア吹込器
CN102962151A (zh) 一种干湿分离比例可调的混合喷涂枪外混合室
JP5487372B2 (ja) 粉体ガンのデフレクター
CN213760329U (zh) 一种高挥发性气体喷嘴
EP3493926B1 (fr) Vanne cyclone et procédé de nettoyage de pompes
CN119907717A (zh) 用于限制喷漆枪的材料针行程的材料量调节装置、具有材料量调节装置的喷漆枪和用于涂覆覆层材料的方法
JP2006143903A (ja) 電磁波吸収性塗布剤の製造方法及び装置
JPH105689A (ja) 粉体の表面被覆方法

Legal Events

Date Code Title Description
121 Ep: the epo has been informed by wipo that ep was designated in this application

Ref document number: 08756358

Country of ref document: EP

Kind code of ref document: A1

NENP Non-entry into the national phase

Ref country code: DE

122 Ep: pct application non-entry in european phase

Ref document number: 08756358

Country of ref document: EP

Kind code of ref document: A1