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WO1997012693A9 - Procede et dispositif d'alimentation en poudre pour installation de poudrage - Google Patents

Procede et dispositif d'alimentation en poudre pour installation de poudrage

Info

Publication number
WO1997012693A9
WO1997012693A9 PCT/SE1996/001263 SE9601263W WO9712693A9 WO 1997012693 A9 WO1997012693 A9 WO 1997012693A9 SE 9601263 W SE9601263 W SE 9601263W WO 9712693 A9 WO9712693 A9 WO 9712693A9
Authority
WO
WIPO (PCT)
Prior art keywords
powder
return
supply
container
fresh
Prior art date
Application number
PCT/SE1996/001263
Other languages
English (en)
Other versions
WO1997012693A1 (fr
Filing date
Publication date
Priority claimed from SE9503448A external-priority patent/SE9503448D0/xx
Application filed filed Critical
Priority to AU72340/96A priority Critical patent/AU7234096A/en
Publication of WO1997012693A1 publication Critical patent/WO1997012693A1/fr
Publication of WO1997012693A9 publication Critical patent/WO1997012693A9/fr

Links

Definitions

  • the invention relates to a method and a device for handling powder in powder coating plants, so that the powder may be supplied to powder spraying equipment in a rational manner.
  • the surface coating material which is based on a heat-fusible polymer, is applied in a pulverous state by means of spraying.
  • the powder is caused to temporarily adhere to the object, which is to be coated, by means of electrostatic forces or in another way, and until the powder is melted by heat and is caused to form a homogenous surface coating.
  • the powder is supplied to the spraying equipment by means of firstly being transferred from a transport container to a storage vessel associated with the spraying equipment. Thereafter, the powder is taken up by means of a suction device and is transferred from this to the spraying equipment.
  • the invention has as its object to provide a method and a device for the handling of the powder in the spraying process, so that the powder handling in the same may be executed in a rational way, with the smallest possible influence on the environment, and so that the prescribed quality requirements concerning the coating result are fulfilled and the risk of rejection is reduced.
  • an important object is to utilize the powder as completely as possible.
  • Fig.l shows a block diagram of a plant for powder spraying when powder coating
  • Fig. 2 shows a device for transportation o f the powder from the powder source to a spraying equipment.
  • a method for supply of powder and consumption of the powder in a spraying plant for powder coating in connection with powder varnishing is presumed to comprise the following steps: 1. Filling powder into transport containers, at the powder manufacturer's, which are preferably arranged for direct withdrawal of powder when used.
  • one of the main objects of the invention is to attain a utilization of the return powder which is as complete as possible under present conditions and quality requirements.
  • the following particulars must be determined in order to arrive at a solution: 1. Determination of data for the powder streams in different plants and in normally occurring coating operations. It may be expected that the ratio between the flow of fresh powder and return powder may vary within certain limits, from supply of solely fresh powder (powder which not has been used in the process is discarded), to a blend between fresh powder and return powder with the latter in a comparatively high proportion. These proportions, as well as the occurring volumes/weights of powder, are determined. These values should constitute a base for the ranges within which a buffer-blending container should be designed to operate and be adjusted for.
  • the system may be provided with an automatic regulation which reduces, respectively increases the proportion of return powder within set tolerances, so that a balance between produced return powder and the supply arises.
  • Such a regulation may have to be complemented with an alarm function, so that supervising personnel can observe that a set proportion is changed. An alarm is definitively required if, in spite of said regulation, the tolerances cannot be met.
  • a powder spraying plant is schematically shown as a block diagram, wherein the invention is applied.
  • a container for recently delivered, fresh powder is denoted by reference numeral 1.
  • this is conveniently a transport container, so that the powder, when consumed, may be drawn out directly without any refilling into any special container in the plant.
  • the container is provided with a nipple 5 through which a suction device 3 may be inserted. This will be further described in connection with the detailed device in Fig. 2.
  • a suction device in a probe form of the type which may be utilized in the present invention, is disclosed in for instance US A 5 271 695 (Bischof et al).
  • the container 1 is positioned diagonally, so that a corner thereof forms a lowest point towards which the powder may flow down as it is consumed by withdrawal via the device 3.
  • the powder which has been drawn up is transported to an inlet 8 of a buffer and blending container 9 by means of a pipe 6, which will also be described in connection with Fig. 2.
  • a pipe 11 for return powder To the container 9 there is also connected an inlet 10 from a pipe 11 for return powder.
  • the second end of the pipe 11 is connected to a collecting device 12 such as a channel in a spray booth 13.
  • a collecting device 12 such as a channel in a spray booth 13.
  • a number of powder spray guns for the coating of work pieces 15 which travel past the spray guns by means of a conveyor.
  • the spray guns are supplied with powder from the blending container 9, which for this purpose has an outlet 16 which is connected to the guns 14 by means of a pipe 17.
  • Compressed air is utilized for transportation of the powder from the suction device 3 and from the collecting device 12 to the blending container 9, and further to the guns 14.
  • the compressed air is generated in a unit 18 which, by means of pipes 19-21, is connected to the described units.
  • the device for transferring powder from the transport containers to the spraying plant is shown in greater detail in Fig. 2.
  • the delivery container 1 On the far left of the drawing, the delivery container 1 is depicted, placed in said position with the nipple 5 turned upwards.
  • a pipe 22 is brought through the nipple to the suction device 3. This is shown in section and it is thereby evident that its outer pipe 22 encloses an additional pipe 24, whereby a duct 25 is formed inside the pipe 24, and an annular duct 26 is formed between the pipes 22 and 24.
  • the duct 25 discharges at the outer end of the pipe 22 in an opening 27, and the duct 26 discharges on the outside of the pipe 22 in a plurality of openings 28 around the end of the pipe.
  • a hose connection 31 which is connnected to the duct 25, and a hose connection 32, which is connected to the duct 26.
  • the hose connection 32 is intended to be connected via the pipe 19 to the source 18 of compressed air, which consequently may stream out through the holes 28 via the duct 26.
  • the hose connection 31 is connected to the hose pipe 6, in which a negative pressure is produced, whereby a suction effect arises at the opening 27.
  • Another suction hose, the pipe 11, is connected to the collecting device 12 for return powder which during the powder spraying has not stuck to any object to be coated. In Fig. 2, this is indicated with a furrow, to the bottom of which the hose 11 is connected.
  • Fig. 2 the buffer and blending device 9 is also shown which can blend powder from different sources and forms a buffer stock for the powder.
  • both the hoses 6 and 11 are connected to an ejector device 38 for achieving the negative pressure in the hoses. This is shown in section in order to indicate how this negative pressure may be attained.
  • the ends of the inlet pipes 8 and 9, to which the hoses 6 and 11 are connected are enclosed by conical sleeves 41 and 42. The narrower ends of these are turned away from the ends of the inlet pipes 8 and 9 and discharge into outlet pipes 43 and 44.
  • the inlet pipes 20 and 21, which are connectable to said source of compressed air 18, are connected to the wider ends of the sleeves 41, 42, which with bottoms enclose the inlet pipes 6 and 11, respectively.
  • the pipes 43 and 44 discharge into a conical buffer container 48, for which the device 38 constitutes a lid. From the bottom of the container, the outlet pipe 16 starts, which in the same way as the pipes 8 and 10 is enclosed by conical sleeves 50 with a compressed air connection 51 and said outlet pipe 16.
  • the pipe 16 is intended, by means of the hose pipe 17, to be connected to one or several powder spray guns 14. These guns will not be described herein, but such are previously known.
  • the sprayed powder As a rule, they are designed to provide the sprayed powder with an electrostatic charge by means of which the powder, when sprayed out by compressed air, is well distributed in the room and forms a cloud which may encompass the object which is to be coated. Moreover, the electrostatic charge is frequently used in order to get the powder to temporarily stick to the object until homogenization and final adhesion of the powder material on the object occur by heating, so that the powder granules melt. It is previously known to achieve the electrostatic charge in two ways: either by supplying a high voltage to the gun, or by furnishing it with channels of a material which, by means of friction, provides the powder with an electric charge.
  • the device is provided with a control system.
  • regulating means 60, 61 for regulating the powder stream into the device 9, are inserted next to the connections 8 and 10 or inside the pipes leading thereto.
  • a sensor 62 adapted to detect the powder level in the container 48, is connected to the device 9.
  • An additional sensor 63 is arranged in the spray booth 13 and its collecting device 12 for return powder in order to detect the temporary supply of return powder, i.e. the powder which has not stuck on any workpiece but has accumulated in the booth.
  • the means are, preferably in an electrical way, connected to a control system which, however, is not shown in the drawing, but the function of which will be described in the following.
  • the following control functions should be effected:
  • the sensor 62 may either be arranged for measuring the powder level in the container or the temporary weight of the container.
  • the level measurement may be done with a photo-sensor or by measurement by means of an air stream.
  • one measurement pipe When measuring with an air stream, one measurement pipe may discharge at the minimum level and one at the maximum level. Thereby, it can be detected if these levels are exceeded or fallen short of by means of the resistance the air meets, at the muzzles of the pipes, when streaming out.
  • the function is, thereby, that the supply is choked when the maximum level has been reached and increased when the minimum level has been reached.
  • This may in its most simple way be done by means of starting and stoppimg of the regulating means which let the powder through, or in a more sophisticated way with continuous detection of the oscillations between the minimum and maximum level, so that a synchronization of the supply capacity of the regulating means may be done with the temporary consumption.
  • Such a more continuous filling process may probably be preferable in order to achieve stable blending conditions.
  • the regulating means should be synchronized so that when they regulate the supply of powder to the container, this is always done in certain proportions between return powder and fresh powder. These proportions must be possible to set from no admixture of return powder at all to the highest proportion of return powder which may be anticipated.
  • the adjustment means may thereby be arranged solely for manual adjustment or, as mentioned in the following, also for automatic regulation.
  • a fixed proportion of this should be set and also, in order to seek to reach a balance between the supply and the output, the tolerances within which this proportion should be allowed to fluctuate.
  • the determination of these set points may be done by utilizing tables with experience values from certain typical cases, by utilizing calculation formulas and/or by test spraying in order to calibrate the settings.
  • the sensor 63 may be designed according to a principle similar to the sensor 62 for the quantity in the container
  • means for transporting return powder which falls out to a measurement container, from which the powder is transported to the spray guns may be arranged.
  • means of a similar type may be arranged for measuring oscillations between a maximum and a minimum level.
  • the control gear thereby controls the regulating means 60, 61 in order to increase the proportion of return powder, and in order to reduce it when the minimum level is fallen short of. If the minimum level cannot be maintained, as well as if the maximum level is constantly exceeded in spite of changes of the proportion within the tolerance limits, there should be an alarm in order to summon control staff so that necessary adjustments in order to maintain a regulated quality can be made.
  • the powder may namely, because of friction during its transportation, be heated up so that an agglomeration is brought about, which jeopardizes the spraying process. This may be avoided if the powder is kept at a low temperature.
  • Such a cooling down may of course be done in many different ways and in different sections of the system.
  • a convenient way is to keep the compressed air entering through the connections 46, 47 and 51 at an appropriately low temperature.
  • the container 48 should thereby be designed as a blending chamber. In Fig. 2, it is indicated how the pipes 43 and 44 are curved at their ends so that the entering powder forms a vortex in which the particles are intimately blended. It is desirable that the container 48 has a volume as small as possible. When a spraying series is finished, there will, namely, always be powder left in the container which may not find any further use and thus must be discarded.
  • ionized air is to be used for the final evacuation and cleaning of the transport container 1, this may be supplied through an intermediate nipple 55, see Fig. 2. This is inserted into the container nipple 5 and encloses the pipe 22 of the device 3. By means of a hose connection 56, the ionized air is blown in and streams out through openings 57 along the walls of the container. Powder residues are thereby neutralized and fall down towards the lower portion of the container and may be drawn out.
  • the device 23 may be arranged to start the air-flushing when the container starts to become empty. The sinking-down of the pipe 22, as the powder is consumed, may be utilised for this purpose.
  • the described system functions in the following way: when a container is to be connected to the system, it is positioned in a rack so that the nipple is directed upwards.
  • the nipple 5 is opened by removing a transport closure and the pipe 22 to the device 3 is inserted into the nipple 5.
  • compressed air is connected to the connection 32 and to the connection 46. This causes air to stream out from the holes 28 at the outer end of the pipe 22 which rests against the powder surface closest to the nipple when the container is filled.
  • the compressed air, through the connection 46 will stream around the pipe 39 in the chamber in the conical sleeve 41 and out through the pipe 43. Thereby, a negative pressure is formed by means of ejector action in the hose 6 and the connection 31, and thereby in the duct 25 inside the inner pipe 24.
  • the compressed air which streams out through the openings 28 the powder closest to the opening 27 is fluidized and is transported by the negative pressure and is brought through the pipe 43 and into the container by the compressed air.
  • a device 3 is inserted into the next container in the transportation line for delivery of powder as soon as the supply from the first container has stopped, possibly also with a contemporaneous supply from this container during a final phase of its emptying process.
  • the powder in the container 48 constitutes a buffer quantity which prevents the supply to the spray guns from ceasing, even if the supply from a transport container temporarily should be interrupted. Accordingly, an alternative possibility is to provide a mechanism for the transfer of a single device 3 from one container, when a ceased flow indicates it is empty, to a filled container. During the short interruption of the supply of fresh powder, however, an output is obtained by means of the buffer quantity which is left in the container 48. This quantity should, however, be as small as possible.
  • the head 30 of the suction device 3 may be provided with a sensor, see 54 in Fig. 3, for instance a switch for an electric control circuit.
  • a sensor see 54 in Fig. 3, for instance a switch for an electric control circuit.
  • an alarm or a control signal indicating that a new container should be switched in, may be obtained when the pipe 22, because of the consumption of the powder, has sunk so deep into the container that the sensor 54 has reached the nipple 5.
  • the pipe 22 may also be provided with the previously described intermediate nipple 55, with its compressed air outlet 57 for air-flushing of the transport container during said final phase of the emptying of the container, so that powder residues are flushed down to the suction opening 27 for an evacuation which is as complete as possible.
  • the sensor 54 or the like may be utilized for the activation of such flushing.

Abstract

Procédé et dispositif d'alimentation en poudre pour installation de poudrage comportant un certain nombre de pistolets pulvérisateurs (14) ou analogue. Afin d'assurer l'alimentation en poudre des pistolets, on a prévu un dispositif (3) pour l'extraction de la poudre à partir de récipients (1) contenant de la poudre neuve, ainsi qu'un dispositif collecteur (12) pour la réception de la poudre non utilisée dans le processus de pulvérisation en vue de revêtir les pièces d'usinage (15). L'alimentation d'un dispositif mélangeur (9) en poudre neuve et en poudre collectée se fait selon des proportions déterminées, dans certaines limites de tolérance déterminées, et indépendamment du débit de poudre dite recyclée par rapport à la consommation du processus de pulvérisation. Cependant, au cas où il se produirait un excédent de poudre recyclée, on laisse celui-ci s'accumuler, et lorsqu'il y a un manque de poudre recyclée, on intervient sur le processus de pulvérisation de sorte qu'il s'interrompt ou qu'une indication est donnée quant à la nécessité d'un réglage manuel.
PCT/SE1996/001263 1995-10-05 1996-10-04 Procede et dispositif d'alimentation en poudre pour installation de poudrage WO1997012693A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AU72340/96A AU7234096A (en) 1995-10-05 1996-10-04 Method and device for handling powder in powder coating plants

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
SE9503448-4 1995-10-05
SE9503448A SE9503448D0 (sv) 1995-10-05 1995-10-05 System för hantering av pulver i pulverlackeringsanläggningar

Publications (2)

Publication Number Publication Date
WO1997012693A1 WO1997012693A1 (fr) 1997-04-10
WO1997012693A9 true WO1997012693A9 (fr) 1997-05-29

Family

ID=20399707

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/SE1996/001263 WO1997012693A1 (fr) 1995-10-05 1996-10-04 Procede et dispositif d'alimentation en poudre pour installation de poudrage

Country Status (3)

Country Link
AU (1) AU7234096A (fr)
SE (1) SE9503448D0 (fr)
WO (1) WO1997012693A1 (fr)

Families Citing this family (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE19808765A1 (de) * 1998-03-02 1999-09-16 Wagner Int Pulverbeschichtungsanlage und -verfahren zum Speisen und Mischen von Pulver in einer Beschichtungsanlage
DE10251161B4 (de) * 2002-10-31 2016-02-18 Harro Höfliger Verpackungsmaschinen GmbH Verfahren und Vorrichtung zum Verfüllen von Behältnissen mit pulvrigem Füllgut
DE102007005309A1 (de) * 2007-02-02 2008-08-07 Itw Gema Ag Pulversprühbeschichtungsanlage und Pulversprühbeschichtungsverfahren
SE532457C2 (sv) * 2008-07-03 2010-01-26 Esab Ab Pulverhanteringsanordning för svetsning under pulver
ES2881631T3 (es) 2016-05-12 2021-11-30 Hewlett Packard Development Co Estructura de salida
CN111826625B (zh) * 2020-07-22 2022-08-16 厦门佰事兴新材料科技有限公司 一种合金靶材的制备方法及用该方法制得的合金靶材
CN113863625A (zh) * 2021-11-23 2021-12-31 深圳市壕润机电设备有限公司 一种建筑业用围墙腻子粉喷涂设备
CN114377870A (zh) * 2021-12-31 2022-04-22 广州泽亨实业有限公司 一种粉末比例混合设备及方法

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4505623A (en) * 1982-09-17 1985-03-19 Nordson Corporation Apparatus for transferring powder from bulk drums
EP0184994B2 (fr) * 1984-09-26 1992-11-19 Siegfried Frei Dispositif d'aspiration pour poudre
US5271695A (en) * 1990-07-07 1993-12-21 Gema Volstatic Ag Device for pneumatically feeding powder from a container

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