EP0642391B1 - Method and device for powder-coating - Google Patents
Method and device for powder-coating Download PDFInfo
- Publication number
- EP0642391B1 EP0642391B1 EP93907803A EP93907803A EP0642391B1 EP 0642391 B1 EP0642391 B1 EP 0642391B1 EP 93907803 A EP93907803 A EP 93907803A EP 93907803 A EP93907803 A EP 93907803A EP 0642391 B1 EP0642391 B1 EP 0642391B1
- Authority
- EP
- European Patent Office
- Prior art keywords
- workpiece
- inductor
- coating
- powder
- pipe
- 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.)
- Expired - Lifetime
Links
- 238000000576 coating method Methods 0.000 title claims abstract description 106
- 239000011248 coating agent Substances 0.000 title claims abstract description 102
- 238000000034 method Methods 0.000 title claims abstract description 30
- 239000000843 powder Substances 0.000 claims abstract description 98
- 238000005507 spraying Methods 0.000 claims abstract description 28
- 238000002844 melting Methods 0.000 claims abstract description 7
- 230000008018 melting Effects 0.000 claims abstract description 7
- 239000007921 spray Substances 0.000 claims description 53
- 238000010438 heat treatment Methods 0.000 claims description 32
- 239000002245 particle Substances 0.000 claims description 10
- 230000001939 inductive effect Effects 0.000 claims description 8
- 230000006698 induction Effects 0.000 claims description 4
- 230000035515 penetration Effects 0.000 claims description 4
- 239000004922 lacquer Substances 0.000 claims description 3
- 210000000080 chela (arthropods) Anatomy 0.000 claims 1
- 238000004891 communication Methods 0.000 claims 1
- 239000003973 paint Substances 0.000 abstract description 2
- 239000010410 layer Substances 0.000 description 9
- 239000002318 adhesion promoter Substances 0.000 description 2
- 238000011109 contamination Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 238000003912 environmental pollution Methods 0.000 description 2
- 239000000155 melt Substances 0.000 description 2
- 239000013589 supplement Substances 0.000 description 2
- 239000004593 Epoxy Substances 0.000 description 1
- 239000011247 coating layer Substances 0.000 description 1
- 210000003298 dental enamel Anatomy 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 230000018109 developmental process Effects 0.000 description 1
- 230000005684 electric field Effects 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 238000010422 painting Methods 0.000 description 1
- 239000004033 plastic Substances 0.000 description 1
- 229920003023 plastic Polymers 0.000 description 1
- 239000004645 polyester resin Substances 0.000 description 1
- 229920001225 polyester resin Polymers 0.000 description 1
- 239000004814 polyurethane Substances 0.000 description 1
- 229920002635 polyurethane Polymers 0.000 description 1
- 239000000523 sample Substances 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 239000002904 solvent Substances 0.000 description 1
- 230000003746 surface roughness Effects 0.000 description 1
- 238000004381 surface treatment Methods 0.000 description 1
- 229920001169 thermoplastic Polymers 0.000 description 1
- 229920001187 thermosetting polymer Polymers 0.000 description 1
- 239000004416 thermosoftening plastic Substances 0.000 description 1
- 238000011144 upstream manufacturing Methods 0.000 description 1
- 238000010792 warming Methods 0.000 description 1
Images
Classifications
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
- B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
- B05D3/00—Pretreatment of surfaces to which liquids or other fluent materials are to be applied; After-treatment of applied coatings, e.g. intermediate treating of an applied coating preparatory to subsequent applications of liquids or other fluent materials
- B05D3/02—Pretreatment of surfaces to which liquids or other fluent materials are to be applied; After-treatment of applied coatings, e.g. intermediate treating of an applied coating preparatory to subsequent applications of liquids or other fluent materials by baking
- B05D3/0218—Pretreatment, e.g. heating the substrate
- B05D3/0245—Pretreatment, e.g. heating the substrate with induction heating
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
- B05B—SPRAYING APPARATUS; ATOMISING APPARATUS; NOZZLES
- B05B13/00—Machines or plants for applying liquids or other fluent materials to surfaces of objects or other work by spraying, not covered by groups B05B1/00 - B05B11/00
- B05B13/02—Means for supporting work; Arrangement or mounting of spray heads; Adaptation or arrangement of means for feeding work
- B05B13/04—Means for supporting work; Arrangement or mounting of spray heads; Adaptation or arrangement of means for feeding work the spray heads being moved during spraying operation
- B05B13/0442—Installation or apparatus for applying liquid or other fluent material to separate articles rotated during spraying operation
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
- B05B—SPRAYING APPARATUS; ATOMISING APPARATUS; NOZZLES
- B05B13/00—Machines or plants for applying liquids or other fluent materials to surfaces of objects or other work by spraying, not covered by groups B05B1/00 - B05B11/00
- B05B13/06—Machines or plants for applying liquids or other fluent materials to surfaces of objects or other work by spraying, not covered by groups B05B1/00 - B05B11/00 specially designed for treating the inside of hollow bodies
- B05B13/0645—Machines or plants for applying liquids or other fluent materials to surfaces of objects or other work by spraying, not covered by groups B05B1/00 - B05B11/00 specially designed for treating the inside of hollow bodies the hollow bodies being rotated during treatment operation
- B05B13/0654—Machines or plants for applying liquids or other fluent materials to surfaces of objects or other work by spraying, not covered by groups B05B1/00 - B05B11/00 specially designed for treating the inside of hollow bodies the hollow bodies being rotated during treatment operation and a treating nozzles being translated through the hollow bodies in a direction essentially parallel to the rotational axis
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
- B05B—SPRAYING APPARATUS; ATOMISING APPARATUS; NOZZLES
- B05B14/00—Arrangements for collecting, re-using or eliminating excess spraying material
- B05B14/10—Arrangements for collecting, re-using or eliminating excess spraying material the excess material being particulate
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
- B05B—SPRAYING APPARATUS; ATOMISING APPARATUS; NOZZLES
- B05B14/00—Arrangements for collecting, re-using or eliminating excess spraying material
- B05B14/30—Arrangements for collecting, re-using or eliminating excess spraying material comprising enclosures close to, or in contact with, the object to be sprayed and surrounding or confining the discharged spray or jet but not the object to be sprayed
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
- B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
- B05D1/00—Processes for applying liquids or other fluent materials
- B05D1/02—Processes for applying liquids or other fluent materials performed by spraying
- B05D1/12—Applying particulate materials
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
- B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
- B05D7/00—Processes, other than flocking, specially adapted for applying liquids or other fluent materials to particular surfaces or for applying particular liquids or other fluent materials
- B05D7/14—Processes, other than flocking, specially adapted for applying liquids or other fluent materials to particular surfaces or for applying particular liquids or other fluent materials to metal, e.g. car bodies
- B05D7/146—Processes, other than flocking, specially adapted for applying liquids or other fluent materials to particular surfaces or for applying particular liquids or other fluent materials to metal, e.g. car bodies to metallic pipes or tubes
Definitions
- the invention relates to a method and a device for powder coating electrically conductive workpieces by means of a coating powder, in particular by means of a powder coating.
- the powder coating is basically to be assigned to the area of surface treatment, a layer being applied here in an environmentally friendly manner by thermal action on the surface of a workpiece.
- a coating powder or a powder coating is applied to a surface to be coated, where the coating powder is melted by thermal action until a homogeneous layer is produced on the surface.
- Thermoplastics and thermosets are particularly suitable as coating powders if you want to create a kind of lacquer layer. Basically, however, coatings are possible with powders whose melting point is below the melting point of the workpiece to be coated.
- polyester resin and polyurethane powder as well as epoxy powder have proven their worth in the past.
- the known methods and devices for powder coating have a problem in that the workpieces to be coated are always heated in an oven, a chamber or the like so that the coating powder adhering to the surface can fuse to form a homogeneous layer.
- the temperature therefore acts on the workpiece from the outside, which depending on the heating time has an inward temperature gradient. Consequently, to carry out the known method for powder coating due to often large-sized workpieces, for example for coating long pipes or the like, enormously large industrial furnaces are required, which are extremely uneconomical in themselves due to the high energy requirement there.
- the invention is therefore based on the object of specifying both a device and a method for powder coating, according to which the coating powder used for coating can be applied to the workpiece to be coated using simple means and the coating can also be readily applied to the inside of a hollow body, for example a tube or the like.
- the method according to the invention for powder coating electrically conductive workpieces by means of a coating powder, in particular a powder coating in which the aforementioned object is achieved is characterized by the features of claim 1.
- the process according to the invention then takes place in the following process steps: First of all, the workpiece to be coated, which may have been cleaned and / or surface-treated, is inductively heated to the processing or melting or softening temperature of the coating powder. Then, that is to say immediately after the heating, the coating powder is applied to the inductively heated workpiece by means of a spray device. Due to the already heated condition of the workpiece, no further adhesion promoters are required, since the coating powder is melted immediately when it hits the surface of the workpiece and thus adheres to the workpiece.
- the temperature to be reached inductively on the surface of the workpiece is set in such a way that the coating powder not only melts, but also forms a smooth or homogeneous surface due to the surface tension which arises.
- the spraying of the coating powder begins after an upstream heating phase through the inductor and then continues with the heating and spraying. At the end of the coating process, the inductor is then deactivated and the remaining area is sprayed completely.
- the workpiece to be coated is an elongated part, for example a shaft or even a pipe
- this workpiece can be moved during its inductive heating and spraying because of its rotationally symmetrical design, preferably by means of a clamping device in a rotational movement about its longitudinal axis. Consequently, the inductor and the spray device could be arranged in a stationary manner here, so that the elongated part or the tube rotates in the effective area of the inductor and the spray device in order to achieve a homogeneous coating on all sides.
- the workpiece can be moved relative to the inductor and the spray device or the inductor and the spray device can be moved relative to the workpiece.
- This relative movement could take place in the longitudinal direction of the workpiece, so that the rotary movement of the workpiece caused by the clamping device and the longitudinal movement in question could supplement either the workpiece or the inductor with the spray device to the effect that the workpiece, for example the tube, can be effectively coated overall, ie over its entire length.
- the induction heating of the pipe wall in particular via the setting of the frequency of the inductor current, is designed such that the pipe wall is completely warmed up to the inner wall or the inner surface, so that the pipe also can be sprayed or coated from the inside by means of a further spray device.
- a further spray device Such an embodiment of the method according to the invention would have the great advantage that the tube is heated inductively from the outside - zonally - this heating extending into the interior of the tube.
- a spray device connected downstream of the inductor could apply the coating powder inside and outside with nozzles arranged both outside and inside the tube, the coating powder adhering to the respective surfaces immediately after impact.
- the tube it would be conceivable for the tube to be heated both from the outside and from the inside, preferably simultaneously, by an independent inductor in each case and sprayed or coated by a corresponding spray device.
- the inductor to be inserted into the tube would have to be in the form of a probe, preferably rod-shaped, the two inductors being able to act completely independently of one another and also at different points. A partial coating of the tube both from the outside and from the inside is easily possible.
- the layer thickness to be achieved can be adjusted in a particularly advantageous manner via the feed rate of the inductor and the spraying device. Furthermore, the rotation speed of the workpiece and the heating rate of the inductor can be used to influence the layer thickness.
- the surface of the workpiece already sprayed with coating powder could be heated up again in a further advantageous manner by the inductor, so that the coating powder, which has at least partially been melted to date, can smoothen on the surface due to its specific surface tension in the molten or softened state.
- Such heating again could be understood as aftertreatment, provided that in the first run the coating powder may have merely adhered.
- a defined surface roughness or smoothness of the layer to be achieved could be set during further heating.
- the present invention furthermore relates to a device according to the invention, which achieves the device-based task on which this is based by the features of patent claim 9.
- a device for powder coating electrically conductive workpieces by means of a coating powder, in particular a powder coating preferably for using the previously discussed method according to the invention, characterized in that at least one inductor for inductively heating the workpiece and at least one spray device for spraying the heated workpiece with the coating powder are provided.
- the combined use of an inductor and a spraying device compensates for all the disadvantages which have occurred in previously known devices and methods for powder coating.
- the inductor is preferably connected to an inverter and can be supplied with an alternating current of variable frequency.
- the frequency of the inductor is preferably infinitely adjustable to influence the penetration depth of the eddy currents induced in the workpiece by the inductor. However, it is easily possible to specify individual levels for setting different frequencies.
- the inductor could be designed such that it encompasses the workpiece at least partially with a preferably adjustable distance.
- the inductor should be designed such that it acts on a relatively large area of the workpiece without any relative movement between the workpiece and the inductor.
- the inductor could advantageously be made approximately semicircular. A circular configuration is at least conceivable if the workpiece to be coated is tubular and the inductor can bring the workpiece over the tube from a free side.
- the inductor could also be designed approximately in the form of pliers, the respective parts of the pliers again being movable so that the inductor halves can be placed around the workpiece to be coated without influencing it and closed there to form a quasi-circular inductor.
- a clamping device preferably having two receptacles, is provided for the workpiece.
- Receptacles are particularly suitable for holding the workpiece, especially since it can then be held on both sides, for example from the end faces.
- the clamping device or the receptacles of the clamping device are driven in rotation, so that the clamped workpiece can be brought into rotation.
- a rotational movement of the workpiece to be coated has the great advantage that it can be heated on all sides without movement of the inductor and even with, for example, a semicircular configuration of the inductor and thus coated.
- the clamping device could be movable in the longitudinal direction of the workpiece, so that in addition to the rotational movement of the workpiece, it can be heated both over the entire circumference and over the entire length and then coated.
- the arrangement of the clamping device and thus the clamping of the workpiece could be realized such that the Workpiece is clamped horizontally extending.
- a vertically extending clamping of the workpiece would also be conceivable, in which case the inductor would then have to be adapted to the respective orientation or clamping of the workpiece both in terms of its arrangement and in terms of its possibility of movement.
- the inductor can be moved linearly along the workpiece, so that the clamping device would only have to carry out a rotary movement to rotate the workpiece.
- Both the inductor and the workpiece could also be movable in the longitudinal direction, so that only half the travel path would have to be carried out by both the inductor and the clamping device. The maximum movability of the inductor and the clamping device would thus be effectively reduced.
- Both the movement of the inductor and the linear movement of the clamping device could be variable with regard to the speed in order to be able to influence the coating process effectively.
- a further spray device could be provided which can be inserted into the tube for spraying or coating the inner wall of the tube, preferably via a gallows and a lance or a rope.
- the inductive heating of the tube which takes place from the outside, is designed in such a way that the eddy currents causing the heat have a sufficient depth of penetration into the tube, so that sufficient heating actually takes place on the inner surface of the tube.
- the second spraying device could then effect the coating from inside the tube parallel to the first spraying device working on the outside, both spraying devices working at approximately the same height and would move along the tube at approximately the same feed rate. If the pipe were to rotate, this would ensure coating on all sides.
- a further inductor could also be provided which, for heating the inner wall of the tube, could preferably be inserted into the tube via a gallows and a lance or a rope.
- This second inductor could supplement the heating power of the external inductor, so that the wall would be heated homogeneously overall.
- the spraying device it is advantageous if it is arranged downstream of the inductor, so that the inductively heated area of the workpiece lying behind the inductor in the feed direction of the inductor can always be sprayed with the coating powder, so that this due to the heating of the workpiece adheres to it or melts there and distributes itself homogeneously.
- the spray device could be permanently assigned to the inductor, i.e. for example, be mounted on a frame together with the inductor.
- the inductively heated area located behind the inductor would always be sprayable with the coating powder, as viewed in the feed direction of the inductor, movement of the inductor always resulting in an identical movement of the spray device, so that the possibly adjustable and thereby always predetermined distance between inductor and spray device does not change, at least during coating.
- the spraying device has a suction device is assigned, which serves to suction off the powder particles not melted onto the surface of the workpiece.
- the suction device could have an essentially funnel-shaped suction screen, which could at least partially extend around the spray device, ie could be at least slightly shaped or bent around the workpiece.
- Suction screens are quite conceivable here, which are adapted to the respective shapes of the workpieces to be coated, in order to ensure an absolutely effective suction or collection of excess particles of the coating powder.
- the suction device could convey the extracted powder into a collecting container.
- the suction device could be fluidly connected to a reservoir of the spray device, so that the suctioned off coating powder can be fed again and directly to the spray device.
- the nozzle of the spraying device could be matched to the workpiece to be coated precisely with regard to the workpiece geometry and to avoid large quantities of coating powder to be extracted.
- the nozzle of the spray device would have to be exchangeable, the layer thickness to be achieved in turn being adjustable via different nozzle shapes and feed speeds of the spray device or the inductor.
- the single figure shows a schematic, block-like representation, partly in section, of an exemplary embodiment of a device according to the invention for powder coating electrically conductive workpieces using a coating powder, an inductor and two spray devices being provided here.
- the single figure shows an embodiment of a device according to the invention for powder coating electrically conductive workpieces, the workpiece being a tube 1.
- a powder coating is provided as the coating powder in order to apply a coating layer to the surfaces of the tube 1.
- an inductor 2 is used for inductively heating the tube 1.
- the heated workpiece or tube 1 is sprayed with the coating powder by means of a spray device 3.
- the single figure also indicates that the inductor 2 is connected to an inverter 4.
- the inductor 2 can be supplied with an alternating current of variable frequency.
- the adjustability of the frequency of the inductor 2 serves to influence the penetration depth of the eddy currents induced on the tube 1 by the inductor 2 and is preferably infinitely adjustable.
- the inductor 2 partially encompasses the tube 1.
- the distance between tube 1 and inductor 2 is adjustable.
- the inductor 2 is approximately semicircular, an annular configuration and a tong-shaped configuration with two inductor parts being readily possible.
- a clamping device 5 which holds the tube 1 with two receptacles 6, 7.
- the clamping device 5 or the receptacles 6, 7 of the clamping device 5 are driven in rotation, so that the clamped tube 1 can be brought into rotation by the clamping device 5.
- Both the clamping device 5 and the inductor 2 can be moved in the longitudinal direction of the tube 1, so that the tube 1 can be coated effectively over its entire length.
- the clamping device 5 is arranged such that the workpiece or the tube 1 extends vertically in the clamped state.
- the inductor 2 can be moved linearly along the workpiece or the tube 1.
- the inductor 2 is moved at a variable or adjustable speed.
- the only figure shows that in addition to the spray device 3 there is a further spray device 8 which is used for spraying or coating the inner wall of the tube 1.
- This spray device 8 can be moved into the pipe 1 via a gallows 9 and a lance 10, this taking place through the upper receptacle 6.
- the spray devices 3, 8 are arranged downstream of the inductor 2 as seen in the feed direction of the inductor 2, so that the inductively heated area of the tube 1 lying behind the inductor 2 in the feed direction of the inductor 2 can always be sprayed with the coating powder. Furthermore, the spray device 3 is the inductor 2 on a common frame or Holder 11 firmly assigned so that the spray device 3 forcibly follows the inductor 2.
- the spraying devices 3, 8 are each assigned a suction device 12, 13, which is used to suction the powder particles not melted onto the surface of the workpiece or tube 1.
- These suction devices 12, 13 each have an essentially funnel-shaped suction screen 14, 15.
- the suction screen 14, 15 is directed in the direction of the tube 1, which completely surrounds the nozzle of the spray device 3, 8 on the side opposite the spray direction.
- a further suction device 20 is provided, which sucks the opening of the pipe 1 as a whole.
- This suction device 20 is assigned to the lower receptacle 7 or an integral part of the lower receptacle 7.
- the single figure shows that the suction devices 12, 13, 20 are connected to the flow via compressed air hoses 16, 17, 21 with a reservoir 18 of the spray device 3, 8, so that the coating powder which has been sucked off can be fed to the spray devices 3, 8 again.
- compressed air provided in a pressure container 19
- the coating powder is then fed back to the spray devices 3, 8 via further compressed air hoses 22, 23.
Landscapes
- Life Sciences & Earth Sciences (AREA)
- Engineering & Computer Science (AREA)
- Wood Science & Technology (AREA)
- Application Of Or Painting With Fluid Materials (AREA)
- Coating Apparatus (AREA)
- Electrostatic Spraying Apparatus (AREA)
Abstract
Description
Die Erfindung betrifft ein Verfahren und eine Vorrichtung zum Pulverbeschichten elektrisch leitfähiger Werkstücke mittels eines Beschichtungspulvers, insbesondere mittels eines Pulverlacks.The invention relates to a method and a device for powder coating electrically conductive workpieces by means of a coating powder, in particular by means of a powder coating.
Verfahren und Vorrichtungen zum Pulverbeschichten sind seit Jahren aus der Praxis bekannt. Die Pulverbeschichtung ist grundsätzlich dem Bereich der Oberflächenbehandlung zuzuordnen, wobei hier eine Schicht auf umweltschonende Weise durch thermische Einwirkung auf die Oberfläche eines Werkstücks verbracht wird. Im Gegensatz zu dem herkömmlichen Lackieren mit lösungsmittelhaltigen Lacken wird hier ein Beschichtungspulver bzw. ein Pulverlack auf eine zu beschichtende Oberfläche verbracht, wo das Beschichtungspulver durch thermische Einwirkung geschmolzen wird, bis eine homogene Schicht auf der Oberfläche erzeugt ist.Methods and devices for powder coating have been known in practice for years. The powder coating is basically to be assigned to the area of surface treatment, a layer being applied here in an environmentally friendly manner by thermal action on the surface of a workpiece. In contrast to conventional painting with solvent-based paints, a coating powder or a powder coating is applied to a surface to be coated, where the coating powder is melted by thermal action until a homogeneous layer is produced on the surface.
Ein grundsätzliches Problem bei der Pulverbeschichtung ist jedoch das zwingend erforderliche Anhaften des Beschichtungspulvers an der zu beschichtenden Oberfläche. Dieses zwingend erforderliche Anhaften vor der die Schicht erzeugenden Wärmebehandlung wird durch die ebenfalls aus dem Stand der Technik bereits bekannte elektrostatische Pulverbeschichtung erreicht, die auf der Tatsache beruht, daß sich Teile mit entgegengesetzter elektrischer Ladung anziehen. Folglich eignen sich hier ausschließlich leitende oder thermisch stabile Festkörper für die Pulverbeschichtung. Bislang werden Haushaltsmaschinen, Büromöbel, Gartenmöbel, Autozubehör, Armaturen, Drahtwaren, Profile, Fassadenelemente, etc. auf diese Art und Weise beschichtet.However, a fundamental problem with powder coating is the absolutely necessary adhesion of the coating powder to the surface to be coated. This absolutely necessary adhesion before the heat treatment producing the layer is achieved by the electrostatic powder coating, which is also known from the prior art and is based on the fact that parts attract each other with opposite electrical charges. Consequently, only conductive or thermally stable solids are suitable for powder coating. So far, household machines, office furniture, garden furniture, car accessories, fittings, wire goods, profiles, facade elements, etc. have been coated in this way.
Das bislang bekannte Verfahren vollzieht sich derart, daß trockenes Beschichtungspulver in einen Vorratsbehälter gefüllt, fluidisiert oder umgerührt und mittels Druckluft zu einer Sprühpistole gefördert wird. In der Pistole entsteht aus einer Niederspannung von etwa 10 Volt nach dem Kaskadenprinzip Hochspannung und eine oder mehrere Elektroden laden hier das Pulver beim Sprühen mit 60 bis 100 Kilovolt auf. Zwischen der Pistole und dem geerdeten Werkstück bildet sich ein elektrisches Feld. Die Pulverpartikel folgen dessen Feldlinien und bleiben aufgrund der Restladung auf dem zu beschichtenden Objekt haften. Auf diese Weise veredelte Werkstücke können manuell oder automatisch zu einem nachgeschalteten Trockner gefördert werden, wo das ganz überwiegend aus Kunststoff bestehende Beschichtungspulver bei Temperaturen bis zu etwa 200 °C zu einem glatten Film geschmolzen und ausgehärtet wird. Im Falle der Verwendung von Emailpulver als Beschichtungspulver sind Temperaturen um etwa 800 °C erforderlich.The previously known process takes place in such a way that dry coating powder is filled into a storage container, fluidized or stirred and conveyed to a spray gun by means of compressed air. In the gun, a low voltage of about 10 volts creates high voltage based on the cascade principle and one or more electrodes charge the powder with 60 to 100 kilovolts when sprayed. An electrical field is created between the gun and the grounded workpiece. The powder particles follow its field lines and stick to the object to be coated due to the residual charge. Workpieces refined in this way can be conveyed manually or automatically to a downstream dryer, where the coating powder, which consists predominantly of plastic, is melted and hardened into a smooth film at temperatures up to about 200 ° C. If enamel powder is used as the coating powder, temperatures of around 800 ° C. are required.
Als Beschichtungspulver kommen vor allem Thermoplaste und Duroplaste in Frage, wenn man eine Art Lackschicht erzeugen will. Grundsätzlich sind jedoch Beschichtungen mit solchen Pulvern möglich, deren Schmelzpunkt unterhalb des Schmelzpunktes des zu beschichtenden Werkstücks liegt. Insbesondere Polyesterharz- und Polyuretanpulver sowie Epoxid-Pulver haben sich in der Vergangenheit bewährt.Thermoplastics and thermosets are particularly suitable as coating powders if you want to create a kind of lacquer layer. Basically, however, coatings are possible with powders whose melting point is below the melting point of the workpiece to be coated. In particular, polyester resin and polyurethane powder as well as epoxy powder have proven their worth in the past.
Aus WO-A-9 007 984 ist eine Vorrichtung und ein Verfahren gemäß dem Oberbegriff der Ansprüche 1 bzw. 9 bekannt.From WO-A-9 007 984 a device and a method according to the preamble of
Die bekannten Verfahren zur Pulverbeschichtung weisen jedoch das gemeinsame Problem auf, daß die zur Beschichtung dienenden Beschichtungspulver irgendwie auf das zu beschichtende Werkstück aufgebracht werden müssen. Die dazu erforderlichen Maßnahmen bzw. die dazu dienenden Verfahren erfordern einen meist hohen apparativen Aufwand bzw. führen zu der Verwendung sogenannter Haftungsvermittler, die entweder die Beschichtung selbst behindern oder im Hinblick auf die Umwelt bedenklich sind.The known methods for powder coating, however, have the common problem that the coating powders used for coating must somehow be applied to the workpiece to be coated. The measures required for this or the methods used for this usually require a high level of apparatus complexity or lead to the use of so-called adhesion promoters which either coat the coating hinder themselves or are environmentally harmful.
Des weiteren weisen die bekannten Verfahren und Vorrichtungen zum Pulverbeschichten ein Problem dahingehend auf, daß die zu beschichtenden Werkstücke stets in einem Ofen, einer Kammer oder dgl. erwärmt werden, damit das auf der Oberfläche haftende Beschichtungspulver zu einer homogenen Schicht verschmelzen kann. Die Temperatur wirkt demnach von außen auf das Werkstück, wobei dieses je nach Heizdauer einen nach innen gerichteten Temperaturgradienten aufweist. Folglich sind zur Durchführung des bekannten Verfahrens zur Pulverbeschichtung aufgrund oftmals großdimensionierter Werkstücke, beispielsweise zur Beschichtung langer Rohre oder dgl., enorm große Industrieöfen erforderlich, die für sich gesehen aufgrund des dort hohen Energiebedarfs äußerst unwirtschaftlich sind.Furthermore, the known methods and devices for powder coating have a problem in that the workpieces to be coated are always heated in an oven, a chamber or the like so that the coating powder adhering to the surface can fuse to form a homogeneous layer. The temperature therefore acts on the workpiece from the outside, which depending on the heating time has an inward temperature gradient. Consequently, to carry out the known method for powder coating due to often large-sized workpieces, for example for coating long pipes or the like, enormously large industrial furnaces are required, which are extremely uneconomical in themselves due to the high energy requirement there.
Schließlich ist es nach den bekannten Verfahren äußerst schwierig, Rohre auf der Innenfläche wirksam zu beschichten, zumal die von außen einwirkende Wärme nur ungleichmäßig bis zur Innenwandung durchdringt. Allenfalls eine sehr lange Aufheizphase zur Erwärmung des gesamten Werkstücks könnte hier Abhilfe schaffen, was jedoch äußerst kostenintensiv ist.Finally, according to the known methods, it is extremely difficult to effectively coat pipes on the inner surface, especially since the heat acting from the outside only penetrates unevenly to the inner wall. At most, a very long heating phase to heat the entire workpiece could remedy this, but this is extremely cost-intensive.
Der Erfindung liegt daher die Aufgabe zugrunde, sowohl eine Vorrichtung als auch ein Verfahren zum Pulverbeschichten anzugeben, wonach das zur Beschichtung dienende Beschichtungspulver mit einfachen Mitteln auf das zu beschichtende Werkstück aufbringbar ist und die Beschichtung ohne weiteres auch auf der Innenseite eines Hohlkörpers, beispielsweise eines Rohres oder dgl., erfolgen kann.The invention is therefore based on the object of specifying both a device and a method for powder coating, according to which the coating powder used for coating can be applied to the workpiece to be coated using simple means and the coating can also be readily applied to the inside of a hollow body, for example a tube or the like.
Das erfindungsgemäße Verfahren zum Pulverbeschichten elektrisch leitfähiger Werkstücke mittels eines Beschichtungspulvers, insbesondere eines Pulverlacks, bei dem die zuvor genannte Aufgabe gelöst ist, ist durch die Merkmale des Patentanspruches 1 gekennzeichnet. Danach vollzieht sich das erfindungsgemäße Verfahren in folgenden Verfahrensschritten: Zunächst einmal wird das zu beschichtende Werkstück, welches ggf. gereinigt und/oder oberflächenbehandelt ist, induktiv auf die Verarbeitungs- bzw. Schmelz- oder Erweichungstemperatur des Beschichtungspulvers erwärmt. Anschließend, d.h. gleich nach der Erwärmung, wird das Beschichtungspulver auf das induktiv erwärmte Werkstück mittels einer Sprüheinrichtung aufgebracht. Aufgrund des bereits erwärmten Zustandes des Werkstücks sind keine weiteren Haftungsvermittler erforderlich, da das Beschichtungspulver beim Auftreffen auf die Oberfläche des Werkstückes sofort angeschmolzen wird und so am Werkstück haftet. Die induktiv zu erreichende Temperatur an der Oberfläche des Werkstücks wird dabei derart eingestellt, daß das Beschichtungspulver nicht nur anschmilzt, sondern aufgrund der sich einstellenden Oberflächenspannung eine glatte bzw. homogene Oberfläche bildet.The method according to the invention for powder coating electrically conductive workpieces by means of a coating powder, in particular a powder coating in which the aforementioned object is achieved is characterized by the features of
Erfindungsgemäß ist demnach erkannt worden, daß einerseits das Problem des Haftens des Beschichtungspulvers am zu beschichtenden Werkstück und andererseits das Problem einer von außen auf das zu beschichtende Werkstück gerichteten Erwärmung, insbesondere im Hinblick auf sonst übliche große Industrieöfen, dadurch in quasi einem Arbeitsgang gelöst werden kann, indem nämlich das Werkstück bereits vor der eigentlichen Beschichtung - induktiv - aufgewärmt wird und gleich nach dem Aufwärmen - im aufgewärmten Zustand - mit dem Beschichtungspulver besprüht wird. In erfindungsgemäßer Weise ist weder ein aufwendiges Verfahren bzw. eine aufwendige Vorrichtung zum Anhaften des Beschichtungspulvers an dem Werkstück noch ein aufwendiger Industrieofen zum anschließenden Anschmelzen des aufgebrachten Beschichtungspulvers erforderlich. Vielmehr erfolgen die zuvor unabhängigen Vorgänge des Anhaftens und Anschmelzens in quasi einem Arbeitsgang, nämlich durch induktives Erwärmen und nachgeschaltetes Beschichten, wobei hier nur ein unwesentlicher zeitlicher Versatz zwischen Erwärmung und Beschichtung erfolgt. Beide miteinander quasi verschmolzenen Arbeitsvorgänge finden an einem Ort statt, so daß ein zeitraubender und daher kostenintensiver Transport von einer Bearbeitungsstation zur anderen entfällt.According to the invention, it has accordingly been recognized that, on the one hand, the problem of the coating powder adhering to the workpiece to be coated and, on the other hand, the problem of heating directed from the outside onto the workpiece to be coated, in particular with regard to the otherwise usual large industrial furnaces, can thereby be solved in virtually one work step , namely by inductively warming up the workpiece before the actual coating and spraying it with the coating powder immediately after it has warmed up. In the manner according to the invention, neither a complex method or a complex device for adhering the coating powder to the workpiece, nor a complex industrial oven for subsequent melting of the coating powder applied is required. Rather, the previously independent processes of sticking and melting take place in quasi one operation, namely by inductive heating and subsequent coating, with only an insignificant time lag between heating and coating. Both work processes, which are virtually merged with one another, take place in one place, so that time-consuming and therefore cost-intensive transport from one processing station to another is eliminated.
Im Hinblick auf den eigentlichen Beschichtungsvorgang ist es von besonderem Vorteil, wenn das Aufsprühen des Beschichtungspulvers nach einer vorgeschalteten Erwärmungsphase durch den Induktor beginnt und dann mit der Erwärmung und dem Besprühen fortgeführt wird. Zur Beendigung des Beschichtungsverfahrens wird dann der Induktor deaktiviert und der verbleibende Bereich vollends besprüht.With regard to the actual coating process, it is particularly advantageous if the spraying of the coating powder begins after an upstream heating phase through the inductor and then continues with the heating and spraying. At the end of the coating process, the inductor is then deactivated and the remaining area is sprayed completely.
Sofern es sich bei dem zu beschichtenden Werkstück um ein längliches Teil, beispielsweise um eine Welle oder gar um ein Rohr, handelt, kann dieses Werkstück während des induktiven Erwärmens und Besprühens aufgrund seiner rotationssymmetrischen Ausgestaltung vorzugsweise über eine Einspannvorrichtung in Drehbewegung um seine Längsachse verbracht werden. Folglich könnten hier der Induktor und die Sprüheinrichtung ortsfest angeordnet sein, so daß das längliche Teil bzw. das Rohr im Wirkungsbereich des Induktors und der Sprüheinrichtung dreht, um eine allseitige homogene Beschichtung zu erreichen.If the workpiece to be coated is an elongated part, for example a shaft or even a pipe, this workpiece can be moved during its inductive heating and spraying because of its rotationally symmetrical design, preferably by means of a clamping device in a rotational movement about its longitudinal axis. Consequently, the inductor and the spray device could be arranged in a stationary manner here, so that the elongated part or the tube rotates in the effective area of the inductor and the spray device in order to achieve a homogeneous coating on all sides.
Des weiteren ist es von Vorteil, wenn während des induktiven Erwärmens und Besprühens das Werkstück relativ zu dem Induktor und der Sprüheinrichtung oder der Induktor und die Sprüheinrichtung relativ zu dem Werkstück bewegbar ist bzw. sind. Diese Relativbewegung könnte in Längsrichtung zum Werkstück erfolgen, so daß sich die durch die Einspannvorrichtung hervorgerufene Drehbewegung des Werkstücks und die in Rede stehende Längsbewegung entweder des Werkstückes oder des Induktors mit der Sprüheinrichtung dahingehend ergänzen könnten, daß das Werkstück, beispielsweise das Rohr, insgesamt, d.h. auf seiner gesamten Länge, wirksam beschichtet werden kann.Furthermore, it is advantageous if, during inductive heating and spraying, the workpiece can be moved relative to the inductor and the spray device or the inductor and the spray device can be moved relative to the workpiece. This relative movement could take place in the longitudinal direction of the workpiece, so that the rotary movement of the workpiece caused by the clamping device and the longitudinal movement in question could supplement either the workpiece or the inductor with the spray device to the effect that the workpiece, for example the tube, can be effectively coated overall, ie over its entire length.
Gerade bei zu beschichtenden Rohren ist es von Vorteil, wenn die Induktionserwärmung der Rohrwandung, insbesondere über die Einstellung der Frequenz des Induktorstromes, derart ausgelegt ist, daß eine komplette Durchwärmung der Rohrwandung bis hin zur Innenwandung bzw. zur Innenfläche erfolgt, so daß das Rohr auch von innen mittels einer weiteren Sprüheinrichtung besprühbar bzw. beschichtbar ist. Eine solche Ausgestaltung des erfindungsgemäßen Verfahrens hätte den großen Vorteil, daß das Rohr von außen - zonal - auf induktivem Wege erwärmt wird, wobei diese Erwärmung bis in das Rohrinnere hinein reicht. Eine dem Induktor nachgeschaltete Sprüheinrichtung könnte bei sowohl außerhalb als auch innerhalb des Rohres angeordneten Düsen das Beschichtungspulver innen wie auch außen auftragen, wobei das Beschichtungspulver gleich nach Auftreffen auf die jeweiligen Flächen anhaften würde.Especially in the case of pipes to be coated, it is advantageous if the induction heating of the pipe wall, in particular via the setting of the frequency of the inductor current, is designed such that the pipe wall is completely warmed up to the inner wall or the inner surface, so that the pipe also can be sprayed or coated from the inside by means of a further spray device. Such an embodiment of the method according to the invention would have the great advantage that the tube is heated inductively from the outside - zonally - this heating extending into the interior of the tube. A spray device connected downstream of the inductor could apply the coating powder inside and outside with nozzles arranged both outside and inside the tube, the coating powder adhering to the respective surfaces immediately after impact.
Des weiteren wäre es denkbar, daß das Rohr sowohl von außen als auch von innen, vorzugsweise gleichzeitig, durch jeweils einen unabhängigen Induktor erwärmt und durch eine entsprechende Sprüheinrichtung besprüht bzw. beschichtet wird. Der in das Rohr einzufahrende Induktor müßte in Form einer Sonde, vorzugsweise stabförmig, ausgeführt sein, wobei die beiden Induktoren völlig unabhängig voneinander und auch an unterschiedlichen Stellen wirken könnten. Eine partielle Beschichtung des Rohres sowohl von außen als auch von innen ist ohne weiteres möglich.Furthermore, it would be conceivable for the tube to be heated both from the outside and from the inside, preferably simultaneously, by an independent inductor in each case and sprayed or coated by a corresponding spray device. The inductor to be inserted into the tube would have to be in the form of a probe, preferably rod-shaped, the two inductors being able to act completely independently of one another and also at different points. A partial coating of the tube both from the outside and from the inside is easily possible.
In besonders vorteilhafter Weise läßt sich die zu erzielende Schichtdicke über die Vorschubgeschwindigkeit des Induktors und der Sprüheinrichtung einstellen. Des weiteren können die Rotationsgeschwindigkeit des Werkstücks sowie die Aufheizgeschwindigkeit des Induktors zur Beeinflussung der Schichtdicke herangezogen werden.The layer thickness to be achieved can be adjusted in a particularly advantageous manner via the feed rate of the inductor and the spraying device. Furthermore, the rotation speed of the workpiece and the heating rate of the inductor can be used to influence the layer thickness.
Die bereits mit Beschichtungspulver besprühte Fläche des Werkstücks könnte in weiter vorteilhafter Weise durch den Induktor nochmals aufgeheizt werden, damit sich das zumindest bislang teilweise aufgeschmolzene Beschichtungspulver aufgrund seiner spezifischen Oberflächenspannung im schmelzflüssigen bzw. erweichten Zustand an der Oberfläche glätten kann. Ein solches nochmaliges Erwärmen könnte als Nachbehandlung verstanden werden, sofern im ersten Durchgang möglicherweise lediglich ein Anhaften des Beschichtungspulvers erreicht worden ist. Auf jeden Fall könnte beim weiteren Erwärmen eine definierte Oberflächenrauhigkeit bzw. Glätte der zu erzielenden Schicht eingestellt werden.The surface of the workpiece already sprayed with coating powder could be heated up again in a further advantageous manner by the inductor, so that the coating powder, which has at least partially been melted to date, can smoothen on the surface due to its specific surface tension in the molten or softened state. Such heating again could be understood as aftertreatment, provided that in the first run the coating powder may have merely adhered. In any case, a defined surface roughness or smoothness of the layer to be achieved could be set during further heating.
Beim Aufsprühen des Beschichtungspulvers auf das induktiv erwärmte Werkstück ist es stets von Vorteil, das Pulver nicht strahlförmig bzw. punktuell auf das Werkstück zu richten, sondern vielmehr das Pulver in Form eines Sprühnebels, d.h. mit einer gewissen Streubreite, auf das Werkstück zu richten. Dabei läßt es sich nicht vermeiden, daß wesentlich mehr Pulverpartikel in Richtung des Werkstücks gesprüht werden, als das Werkstück in der Lage ist aufzunehmen. Zur Vermeidung von Verschmutzungen und somit einer Umweltbelastung durch das Beschichtungspulver und zur Vermeidung enormer Pulververluste und somit zur Reduzierung der Kosten ist es von ganz besonderem Vorteil, wenn die gesprühten und nicht an dem Werkstück angeschmolzenen Pulverteilchen über eine besondere Absaugeinrichtung abgesaugt werden. Die abgesaugten Pulverteilchen könnten dann wieder der Sprüheinrichtung zum weiteren Sprühen zugeführt werden, wobei diese von der Absaugeinrichtung zunächst in einen Sammel- oder Vorratsbehälter rückgeführt und und von dort aus wieder der Sprüheinrichtung zugeführt würden.When spraying the coating powder onto the inductively heated workpiece, it is always advantageous not to direct the powder onto the workpiece in the form of a jet or at points, but rather to direct the powder onto the workpiece in the form of a spray, ie with a certain spread. It cannot be avoided that much more powder particles are sprayed in the direction of the workpiece than the workpiece is able to take up. To avoid contamination and thus environmental pollution from the coating powder and to avoid enormous powder losses and thus to reduce costs, it is of particular advantage if the sprayed powder particles that have not melted onto the workpiece are sucked off using a special suction device. The suctioned off powder particles could then be fed back to the spraying device for further spraying, whereby the suctioning device firstly into one Collection or storage container returned and from there would be fed back to the spraying device.
Gegenstand der vorliegenden Erfindung ist des weiteren eine erfindungsgemäße Vorrichtung, die die hier zugrundeliegende vorrichtungsbezogene Aufgabe durch die Merkmale des Patentanspruches 9 löst. Danach ist eine Vorrichtung zum Pulverbeschichten elektrisch leitfähiger Werkstücke mittels eines Beschichtungspulvers, insbesondere eines Pulverlacks, vorzugsweise zur Anwendung des zuvor erörterten erfindungsgemäßen Verfahrens, dadurch gekennzeichnet, daß mindestens ein Induktor zum induktiven Erwärmen des Werkstücks und mindestens eine Sprüheinrichtung zum Besprühen des aufgeheizten Werkstückes mit dem Beschichtungspulver vorgesehen sind. Auch hier ist erfindungsgemäß erkannt worden, daß der kombinative Einsatz eines Induktors und einer Sprüheinrichtung sämtliche Nachteile ausgleicht, die bei bislang bekannten Vorrichtungen und Verfahren zum Pulverbeschichten aufgetreten sind.The present invention furthermore relates to a device according to the invention, which achieves the device-based task on which this is based by the features of
Der Induktor ist vorzugsweise an einen Wechselrichter angeschlossen und mit einem Wechselstrom variabler Frequenz beaufschlagbar. Die Frequenz des Induktors ist zur Beeinflussung der Eindringtiefe der durch den Induktor im Werkstück induzierten Wirbelströme vorzugsweise stufenlos einstellbar. Die Vorgabe einzelner Stufen zur Einstellung unterschiedlicher Frequenzen ist jedoch ohne weiteres möglich.The inductor is preferably connected to an inverter and can be supplied with an alternating current of variable frequency. The frequency of the inductor is preferably infinitely adjustable to influence the penetration depth of the eddy currents induced in the workpiece by the inductor. However, it is easily possible to specify individual levels for setting different frequencies.
Sofern es sich bei dem zu beschichtenden Werkstück um ein längliches Werkstück, vorzugsweise um ein Rohr, handelt, könnte der Induktor so ausgestaltet sein, daß er das Werkstück zumindest teilweise mit vorzugsweise einstellbarem Abstand umgreift. Dabei sollte der Induktor so ausgestaltet sein, daß er bereits ohne Relativbewegung zwischen Werkstück und Induktor einen relativ großen Bereich des Werkstücks beaufschlagt. In besonders vorteilhafter Weise könnte der Induktor in etwa halbkreisförmig ausgeführt sein. Eine kreisringförmige Ausgestaltung ist zumindest dann denkbar, wenn das zu beschichtende Werkstück rohrförmig ausgeführt ist und der Induktor das Werkstück von einer freien Seite her über das Rohr verbracht werden kann. Schließlich könnte der Induktor auch in etwa zangenförmig ausgeführt sein, wobei die jeweiligen Zangenteile wiederum bewegbar ausgeführt sein könnten, damit die Induktorhälften ohne Beeinflussung des zu beschichtenden Werkstücks um dieses herumgelegt und dort zum quasi kreisförmigen Induktor geschlossen werden können.If the workpiece to be coated is an elongated workpiece, preferably a tube, the inductor could be designed such that it encompasses the workpiece at least partially with a preferably adjustable distance. The inductor should be designed such that it acts on a relatively large area of the workpiece without any relative movement between the workpiece and the inductor. Especially The inductor could advantageously be made approximately semicircular. A circular configuration is at least conceivable if the workpiece to be coated is tubular and the inductor can bring the workpiece over the tube from a free side. Finally, the inductor could also be designed approximately in the form of pliers, the respective parts of the pliers again being movable so that the inductor halves can be placed around the workpiece to be coated without influencing it and closed there to form a quasi-circular inductor.
Zum sicheren Halt des zu beschichtenden Werkstückes ist es von weiterem Vorteil, wenn eine vorzugsweise zwei Aufnahmen aufweisende Einspannvorrichtung für das Werkstück vorgesehen ist. Zur Aufnahme eignen sich besonders zum Halten des Werkstücks dienende Aufnahmen, zumal dieses dann beidseitig, beispielsweise von den Stirnflächen her, gehalten werden kann.For a secure hold of the workpiece to be coated, it is a further advantage if a clamping device, preferably having two receptacles, is provided for the workpiece. Receptacles are particularly suitable for holding the workpiece, especially since it can then be held on both sides, for example from the end faces.
In weiter vorteilhafter Weise ist die Einspannvorrichtung bzw. sind die Aufnahmen der Einspannvorrichtung drehangetrieben, so daß das eingespannte Werkstück in Rotation verbringbar ist. Eine Rotationsbewegung des zu beschichtenden Werkstücks hat den großen Vorteil, daß dieses ohne Bewegung des Induktors und auch bereits bei beispielsweise halbkreisförmiger Ausgestaltung des Induktors allseitig erwärmt und somit beschichtet werden kann.In a further advantageous manner, the clamping device or the receptacles of the clamping device are driven in rotation, so that the clamped workpiece can be brought into rotation. A rotational movement of the workpiece to be coated has the great advantage that it can be heated on all sides without movement of the inductor and even with, for example, a semicircular configuration of the inductor and thus coated.
Zur homogenen Beschichtung der gesamten Fläche des Werkstücks könnte die Einspannvorrichtung in Längsrichtung des Werkstücks verfahrbar sein, so daß in Ergänzung zu der Rotationsbewegung des Werkstücks dieses sowohl über den gesamten Umfang als auch über die gesamte Länge hinweg erwärmbar und danach beschichtbar ist. Die Anordnung der Einspannvorrichtung und somit die Einspannung des Werkstücks könnte derart realisiert sein, daß das Werkstück sich horizontal erstreckend einspannbar ist. Eine sich vertikal erstreckende Einspannung des Werkstückes wäre ebenfalls denkbar, wobei dann jeweils der Induktor auf die jeweilige Orientierung bzw. Einspannung des Werkstücks sowohl in seiner Anordnung als auch in seiner Bewegungsmöglichkeit angpaßt sein müßte.For the homogeneous coating of the entire surface of the workpiece, the clamping device could be movable in the longitudinal direction of the workpiece, so that in addition to the rotational movement of the workpiece, it can be heated both over the entire circumference and over the entire length and then coated. The arrangement of the clamping device and thus the clamping of the workpiece could be realized such that the Workpiece is clamped horizontally extending. A vertically extending clamping of the workpiece would also be conceivable, in which case the inductor would then have to be adapted to the respective orientation or clamping of the workpiece both in terms of its arrangement and in terms of its possibility of movement.
Auch wäre es denkbar, daß der Induktor längs des Werkstücks linear verfahrbar ist, so daß die Einspannvorrichtung lediglich eine Drehbewegung zur Rotation des Werkstücks durchführen müßte. Auch könnte sowohl der Induktor als auch das Werkstück in Längsrichtung bewegbar sein, so daß sowohl vom Induktor als auch von der Einspanneinrichtung jeweils nur der halbe Verfahrweg durchzuführen wäre. Die maximale Verfahrbarkeit des Induktors und der Einspanneinrichtung wäre somit wirksam verringert.It would also be conceivable that the inductor can be moved linearly along the workpiece, so that the clamping device would only have to carry out a rotary movement to rotate the workpiece. Both the inductor and the workpiece could also be movable in the longitudinal direction, so that only half the travel path would have to be carried out by both the inductor and the clamping device. The maximum movability of the inductor and the clamping device would thus be effectively reduced.
Sowohl die Bewegung des Induktors als auch die lineare Bewegung der Einspannvorrichtung könnte im Hinblick auf die Geschwindigkeit variabel sein, um auch dadurch den Beschichtungsvorgang wirksam beeinflussen zu können.Both the movement of the inductor and the linear movement of the clamping device could be variable with regard to the speed in order to be able to influence the coating process effectively.
Sofern es sich bei dem zu beschichtenden Werkstück um ein Rohr handelt, könnte eine weitere Sprüheinrichtung vorgesehen sein, die zum Besprühen bzw. Beschichten der Innenwandung des Rohrs vorzugsweise über eine Galgen und eine Lanze oder ein Seil in das Rohr einfahrbar ist. Dabei müßte jedoch gewährleistet sein, daß die von außen erfolgende induktive Erwärmung des Rohrs derart ausgelegt ist, daß die die Wärme verursachenden Wirbelströme eine hinreichende Eindringtiefe in das Rohr aufweisen, so daß auch tatsächlich eine hinreichende Erwärmung auf der Innenfläche des Rohrs stattfindet. Die zweite Sprüheinrichtung könnte dann parallel zu der außen arbeitenden ersten Sprüheinrichtung die Beschichtung von innerhalb des Rohrs bewirken, wobei beide Sprüheinrichtungen in etwa auf gleicher Höhe arbeiten und sich in etwa sich mit gleicher Vorschubgeschwindigkeit längs des Rohres bewegen würden. Eine dabei erfolgende Drehbewegung des Rohrs würde ein allseitiges Beschichten gewährleisten.If the workpiece to be coated is a tube, a further spray device could be provided which can be inserted into the tube for spraying or coating the inner wall of the tube, preferably via a gallows and a lance or a rope. However, it would have to be ensured that the inductive heating of the tube, which takes place from the outside, is designed in such a way that the eddy currents causing the heat have a sufficient depth of penetration into the tube, so that sufficient heating actually takes place on the inner surface of the tube. The second spraying device could then effect the coating from inside the tube parallel to the first spraying device working on the outside, both spraying devices working at approximately the same height and would move along the tube at approximately the same feed rate. If the pipe were to rotate, this would ensure coating on all sides.
Alternativ zu der voranstehend erörterten Ausgestaltungsmöglichkeit könnte auch ein weiterer Induktor vorgesehen sein, der zum Erwärmen der Innenwandung des Rohrs vorzugsweise über einen Galgen und eine Lanze oder ein Seil in das Rohr einfahrbar wäre. Dieser zweite Induktor könnte die Heizleistung des außen wirkenden Induktors ergänzen, so daß die Wandung insgesamt homogen erwärmt würde.As an alternative to the configuration option discussed above, a further inductor could also be provided which, for heating the inner wall of the tube, could preferably be inserted into the tube via a gallows and a lance or a rope. This second inductor could supplement the heating power of the external inductor, so that the wall would be heated homogeneously overall.
Im Hinblick auf die Anordnung der Sprüheinrichtung ist es von Vorteil, wenn diese dem Induktor nachgeordnet ist, so daß stets der in Vorschubrichtung des Induktors gesehen hinter dem Induktor liegende, induktiv erwärmte Bereich des Werkstücks mit dem Beschichtungspulver besprühbar ist, so daß dieses aufgrund der Erwärmung des Werkstücks an diesem anhaftet bzw. dort anschmilzt und sich homogen verteilt. Die Sprüheinrichtung könnte dabei dem Induktor fest zugeordnet sein, d.h. beispielsweise gemeinsam mit dem Induktor auf einem Rahmen montiert sein. Auch hier wäre dann in Vorschubrichtung des Induktors gesehen stets der hinter dem Induktor liegende, induktiv erwärmte Bereich mit dem Beschichtungspulver besprühbar, wobei eine Bewegung des Induktors stets eine identische Bewegung der Sprüheinrichtung zur Folge hat, so daß sich der möglicherweise einstellbare und dadurch stets vorgegebene Abstand zwischen Induktor und Sprüheinrichtung zumindest während des Beschichtens nicht ändert.With regard to the arrangement of the spraying device, it is advantageous if it is arranged downstream of the inductor, so that the inductively heated area of the workpiece lying behind the inductor in the feed direction of the inductor can always be sprayed with the coating powder, so that this due to the heating of the workpiece adheres to it or melts there and distributes itself homogeneously. The spray device could be permanently assigned to the inductor, i.e. for example, be mounted on a frame together with the inductor. Here, too, the inductively heated area located behind the inductor would always be sprayable with the coating powder, as viewed in the feed direction of the inductor, movement of the inductor always resulting in an identical movement of the spray device, so that the possibly adjustable and thereby always predetermined distance between inductor and spray device does not change, at least during coating.
Insbesondere im Hinblick auf eine Vermeidung von Umweltbelastungen bzw. Verschmutzungen sowie im Hinblick auf einen geringst möglichen Materialverbrauch des Beschichtungspulvers ist es von weiterem Vorteil, wenn der Sprüheinrichtung eine Absaugeinrichtung zugeordnet ist, die zum Absaugen der nicht an der Oberfläche des Werkstücks angeschmolzenen Pulverteilchen dient. Die Absaugeinrichtung könnte einen im wesentlichen trichterförmigen Absaugschirm aufweisen, wobei dieser sich zumindest teilweise um die Sprüheinrichtung herum erstrecken könnte, d.h. zumindest geringfügig um das Werkstück herum geformt bzw. gebogen sein könnte. Hier sind durchaus Absaugschirme denkbar, die den jeweiligen Formen der zu beschichtenden Werkstücke angepaßt sind, um ein absolut wirkungsvolles Absaugen bzw. Auffangen überschüssiger Teilchen des Beschichtungspulvers zu gewährleisten.In particular with a view to avoiding environmental pollution or contamination and with regard to the lowest possible material consumption of the coating powder, it is of further advantage if the spraying device has a suction device is assigned, which serves to suction off the powder particles not melted onto the surface of the workpiece. The suction device could have an essentially funnel-shaped suction screen, which could at least partially extend around the spray device, ie could be at least slightly shaped or bent around the workpiece. Suction screens are quite conceivable here, which are adapted to the respective shapes of the workpieces to be coated, in order to ensure an absolutely effective suction or collection of excess particles of the coating powder.
Die Absaugeinrichtung könnte das abgesaugte Pulver in einen Sammelbehälter hinein fördern. Ebenso könnte die Absaugeinrichtung mit einem Vorratsbehälter der Sprüheinrichtung strömungsverbunden sein, so daß das abgesaugte Beschichtungspulver erneut und dabei direkt der Sprüheinrichtung zuführbar ist.The suction device could convey the extracted powder into a collecting container. Likewise, the suction device could be fluidly connected to a reservoir of the spray device, so that the suctioned off coating powder can be fed again and directly to the spray device.
Schließlich könnte die Düse der Sprüheinrichtung gerade im Hinblick auf die Werkstückgeometrie und zur Vermeidung großer Mengen abzusaugender Beschichtungspulver jeweils auf das zu beschichtende Werkstück abgestimmt sein. Dazu müßte die Düse der Sprüheinrichtung austauschbar sein, wobei über unterschiedliche Düsenformen und Vorschubgeschwindigkeiten der Sprüheinrichtung bzw. des Induktors wiederum die zu erzielende Schichtdicke einstellbar wäre.Finally, the nozzle of the spraying device could be matched to the workpiece to be coated precisely with regard to the workpiece geometry and to avoid large quantities of coating powder to be extracted. For this purpose, the nozzle of the spray device would have to be exchangeable, the layer thickness to be achieved in turn being adjustable via different nozzle shapes and feed speeds of the spray device or the inductor.
Es gibt nun verschiedene Möglichkeiten, die Lehre der vorliegenden Erfindung in vorteilhafter Weise auszugestalten und weiterzubilden. Dazu ist einerseits auf die den Patentansprüchen 1 und 12 nachgeordneten Ansprüche, andererseits auf die nachfolgende Erläuterung eines Ausführungsbeispiels der Erfindung anhand der Zeichnung zu verweisen. In Verbindung mit der Erläuterung des bevorzugten Ausführungsbeispiels der Erfindung anhand der Zeichnung werden auch im allgemeinen bevorzugte Ausgestaltungen und Weiterbildungen der Lehre erläutert.There are now various possibilities for advantageously designing and developing the teaching of the present invention. For this purpose, reference is made on the one hand to the claims subordinate to patent claims 1 and 12, and on the other hand to the following explanation of an exemplary embodiment of the invention with reference to the drawing. In connection with the explanation of the preferred embodiment of the invention based on The drawing also explains generally preferred refinements and developments of the teaching.
In der Zeichnung zeigt die einzige Figur in schematischer, blockmäßiger Darstellung, teilweise geschnitten, ein Ausführungsbeispiel einer erfindungsgemäßen Vorrichtung zum Pulverbeschichten elektrisch leitfähiger Werkstücke mittels eines Beschichtungspulvers, wobei hier ein Induktor und zwei Sprüheinrichtungen vorgesehen sind.In the drawing, the single figure shows a schematic, block-like representation, partly in section, of an exemplary embodiment of a device according to the invention for powder coating electrically conductive workpieces using a coating powder, an inductor and two spray devices being provided here.
Die einzige Figur zeigt ein Ausführungsbeispiel einer erfindungsgemäßen Vorrichtung zum Pulverbeschichten elektrisch leitfähiger Werkstücke, wobei es sich bei dem Werkstück um ein Rohr 1 handelt. Als Beschichtungspulver ist hier ein in der Figur nicht dargestellter Pulverlack vorgesehen, um an den Oberflächen des Rohrs 1 eine Lackschicht aufzubringen.The single figure shows an embodiment of a device according to the invention for powder coating electrically conductive workpieces, the workpiece being a
In erfindungsgemäßer Weise dient ein Induktor 2 zum induktiven Erwärmen des Rohrs 1. Mittels einer Sprüheinrichtung 3 wird das aufgeheizte Werkstück bzw. das Rohr 1 mit dem Beschichtungspulver besprüht.In the manner according to the invention, an
In der einzigen Figur ist des weiteren angedeutet, daß der Induktor 2 an einen Wechselrichter 4 angeschlossen ist. Dadurch ist der Induktor 2 mit einem Wechselstrom variabler Frequenz beaufschlagbar. Die Einstellbarkeit der Frequenz des Induktors 2 dient zur Beeinflussung der Eindringtiefe der durch den Induktor 2 am Rohr 1 induzierten Wirbelströme und ist vorzugsweise stufenlos einstellbar.The single figure also indicates that the
In der einzigen Figur ist des weiteren angedeutet, daß der Induktor 2 das Rohr 1 teilweise umgreift. Der Abstand zwischen Rohr 1 und Induktor 2 ist einstellbar. Des weiteren ist der Induktor 2 in etwa halbkreisförmig ausgeführt, wobei eine kreisringförmige Ausgestaltung sowie eine zangenförmige Ausgestaltung mit zwei Induktorteilen ohne weiteres möglich ist.In the single figure it is further indicated that the
Zur Halterung des Rohrs 1 ist eine Einspannvorrichtung 5 vorgesehen, die das Rohr 1 mit zwei Aufnahmen 6, 7 hält. Die Einspannvorrichtung 5 bzw. die Aufnahmen 6, 7 der Einspannvorrichtung 5 sind drehangetrieben, so daß das eingespannte Rohr 1 durch die Einspannvorrichtung 5 in Rotation verbringbar ist. Sowohl die Einspannvorrichtung 5 als auch der Induktor 2 können in Längsrichtung des Rohrs 1 verfahrbar sein, so daß das Rohr 1 im Verlaufe seiner gesamten Länge wirksam beschichtbar ist.To hold the
Bei dem hier gewählten Ausführungsbeispiel ist die Einspannvorrichtung 5 derart angeordnet, daß sich das Werkstück bzw. das Rohr 1 im eingespannten Zustand vertikal erstreckt. Der Induktor 2 ist hier längs des Werkstücks bzw. des Rohrs 1 linear verfahrbar. Die Bewegung des Induktors 2 erfolgt mit variabler bzw. einstellbarer Geschwindigkeit.In the embodiment selected here, the
Weiterhin zeigt die einzige Figur, daß zu der Sprüheinrichtung 3 eine weitere Sprüheinrichtung 8 hinzukommt, die zum Besprühen bzw. Beschichten der Innenwandung des Rohrs 1 dient. Diese Sprüheinrichtung 8 ist über einen Galgen 9 und eine Lanze 10 in das Rohr 1 einfahrbar, wobei dies durch die obere Aufnahme 6 hindurch erfolgt.Furthermore, the only figure shows that in addition to the
Die Sprüheinrichtungen 3, 8 sind dem Induktor 2 in Vorschubrichtung des Induktors 2 gesehen nachgeordnet, so daß stets der in Vorschubrichtung des Induktors 2 gesehen hinter dem Induktor 2 liegende, induktiv erwärmte Bereich des Rohrs 1 mit dem Beschichtungspulver besprühbar ist. Des weiteren ist die Sprüheinrichtung 3 dem Induktor 2 auf einem gemeinsamen Rahmen bzw. Halter 11 fest zugeordnet, so daß die Sprüheinrichtung 3 dem Induktor 2 zwangsweise folgt.The
Den Sprüheinrichtungen 3, 8 ist jeweils eine Absaugeinrichtung 12, 13 zugeordnet, die zum Absaugen der nicht an der Oberfläche des Werkstücks bzw. Rohrs 1 angeschmolzenen Pulverteilchen dient. Diese Absaugeinrichtungen 12, 13 weisen jeweils für sich einen im wesentlichen trichterförmigen Absaugschirm 14, 15 auf. Der Absaugschirm 14, 15 ist in Richtung des Rohrs 1 gerichtet, wobei dieser die Düse der Sprüheinrichtung 3, 8 auf der der Sprührichtung entgegensetzten Seite völlig umgibt.The
Am unteren Ende des Rohrs 1 ist eine weitere Absaugeinrichtung 20 vorgesehen, die die Öffnung des Rohrs 1 insgesamt absaugt. Diese Absaugeinrichtung 20 ist der unteren Aufnahme 7 zugeordnet bzw. integraler Bestandteil der unteren Aufnahme 7.At the lower end of the
Schließlich läßt die einzige Figur erkennen, daß die Absaugeinrichtungen 12, 13, 20 über Druckluftschläuche 16, 17, 21 mit einem Vorratsbehälter 18 der Sprüheinrichtung 3, 8 strömungsverbunden sind, so daß das abgesaugte Beschichtungspulver erneut den Sprüheinrichtungen 3, 8 zuführbar ist. Mittels in einem Druckbehälter 19 zur Verfügung gestellter Druckluft wird das Beschichtungspulver dann wieder den Sprüheinrichtungen 3, 8 über weitere Druckluftschläuche 22, 23 zugeführt.Finally, the single figure shows that the
Das voranstehend erörterte Ausführungsbeispiel dient lediglich zum besseren Verständnis der erfindungsgemäßen Lehre, schränkt diese jedoch nicht auf das Ausführungsbeispiel ein.The exemplary embodiment discussed above serves only for a better understanding of the teaching according to the invention, but does not restrict it to the exemplary embodiment.
Claims (20)
- Method of powder-coating electrically-conductive workpieces (1) by means of a coating powder, particularly a lacquer powder, in which the cleaned and/or surface-treated workpiece (1) is heated to the processing temperature or the melting or softening point of the coating powder and the coating powder is sprayed onto the inductively heated workpiece (1) by means of a spray device (3), and in which, during the inductive heating and the spraying, the workpiece (1) is moved relative to the inductor (2) and to the spray device (3), or the inductor (2) and the spray device (3) are moved relative to the workpiece (1), characterized in that the inductively heated region of the workpiece (1) disposed immediately behind the inductor (2), viewed in the direction of advance, is sprayed with the coating powder so that the coating takes place outside the induction region with a delay after the heating.
- Method according to Claim 1, characterized in that the spraying of the coating powder starts after a preceding heating phase by means of the inductor (2) and is then continued synchronously with the heating.
- Method according to Claim 1 or Claim 2, in which the workpiece (1) to be coated is an elongate element, preferably a pipe, characterized in that, during the inductive heating and spraying, the workpiece (1) is preferably set in rotary motion about its longitudinal axis by means of a clamping device (5).
- Method according to any one of Claims 1 to 3, in which the workpiece is a pipe (1), characterized in that the induction heating of the pipe wall is designed, particularly by means of the frequency of the inductor current, in a manner such that heat penetrates as far as the internal wall, and in that the pipe (1) is also sprayed and coated from the inside by means of a further spray device (8)
- Method according to any one of Claims 1 to 4, characterized in that the pipe (1) can be heated by respective inductors (2) and is sprayed and coated by means of a spray device (3, 8), both from the outside and from the inside, preferably simultaneously.
- Method according to any one of Claims 1 to 5, characterized in that the coating thickness to be achieved is controlled by the speed of advance of the inductor (2) and of the spray device (3, 8) and/or by the speed of rotation of the workpiece (1) and/or by the heating-up rate.
- Method according to any one of Claims 1 to 6, characterized in that the surface of the workpiece (1) already sprayed with coating powder is heated again by the inductor (2) so that the at least partially melted-on coating powder can flatten out on the surface in the molten or softened condition owing to its specific surface tension.
- Method according to any one of Claims 1 to 7, characterized in that the powder particles sprayed and not melted onto the workpiece (1) are exhausted by means of a suction device (12, 13), and in that the powder particles exhausted are optionally supplied to the spray device (3, 8) again for further spraying.
- Device for the powder-coating of electrically-conductive workpieces (1) by means of a coating powder, particularly a lacquer powder, in which an inductor (2) is provided for the inductive heating of the workpiece (1) and at least one spray device (3) is provided for spraying the heated workpiece (1) with the coating powder, and in which, during the inductive heating and spraying, the workpiece (1) is movable relative to the inductor (2) and to the spray device (3) or the inductor (2) and the spray device (3) are movable relative to the workpiece (1),
characterized in that the spray device (3, 8) is disposed downstream of the inductor (2), viewed in the direction of advance, so that the inductively heated region of the workpiece (1) disposed behind the inductor can be sprayed with the coating powder, and so that the coating takes place outside the induction region with a delay after the heating. - Device according to Claim 9, characterized in that the inductor (2) is connected to an inverter (4) and can be acted on by an alternating current of variable frequency, the frequency of the inductor (2) being adjustable, preferably continuously, in order to influence the depth of penetration of the eddy currents induced in the workpiece (1) by the inductor (2).
- Device according to Claim 9 or Claim 10, in which the workpiece (1) is elongate, preferably in the form of a pipe, characterized in that the inductor (2) extends at least partially around the workpiece (1), preferably with adjustable clearance, and is approximately semicircular, or extends around the pipe (1) in the form of a ring and, optionally, is formed in two parts or in the form of pincers.
- Device according to any one of Claims 9 to 11, characterized in that a clamping device (5) preferably having two seats (6, 7) is provided for the workpiece (1), in that the clamping device (5) or the seats (6, 7) of the clamping device (5) is or are rotated to enable the clamped workpiece (1) to be set in rotation, can optionally travel longitudinally of the workpiece (1), and is arranged in a manner such that the workpiece (1) can be clamped so as to extend horizontally or vertically.
- Device according to any one of Claims 9 to 12, characterized in that the inductor (2) can travel linearly along the workpiece (1) at variable speed.
- Device according to any one of Claims 9 to 13, in which the workpiece is a pipe (1), characterized in that a further spray device (8) is provided and can be introduced into the pipe (1), preferably by means of a boom (9) and a lance (10) or a cable, in order to spray or coat the internal wall of the pipe (1).
- Device according to any one of Claims 9 to 14, in which the workpiece is a pipe (1), characterized in that a further inductor is provided and can be introduced into the pipe (1), preferably by means of a boom (9) and a lance (10) or a cable, in order to heat the internal wall of the pipe (1).
- Device according to any one of Claims 9 to 15, characterized in that a suction device (12, 13) is associated with the spray device (3, 8) and serves to exhaust the powder particles which are not melted onto the surface of the workpiece (1).
- Device according to any one of Claims 9 to 16, characterized in that the suction device (12, 13) has a substantially funnel-shaped suction screen (14, 15), and in that the suction screen (14, 15) extends at least partially around the spray device (3, 8).
- Device according to any one of Claims 13 to 17, characterized in that a further suction device (20) is provided at the lower end of the pipe and exhausts the opening of the pipe (1) as a whole, and in that the suction device (20) is associated with the lower seat (7) and is an integral component of the lower seat (7).
- Device according to any one of Claims 16 to 18, characterized in that the suction devices (12, 13, 20) are in flow communication with a reservoir (18) of the spray device (3, 8) so that the coating powder exhausted can be supplied to the spray device (3, 8) again.
- Device according to any one of Claims 9 to 18, characterized in that the nozzle of the spray device (3, 8) is exchangeable, and in that the coating thickness to be achieved is adjustable by means of the nozzle shape and speed of advance of the spray device (3, 8) and of the inductor (2).
Applications Claiming Priority (3)
Application Number | Priority Date | Filing Date | Title |
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DE4217754A DE4217754C2 (en) | 1992-05-29 | 1992-05-29 | Method and device for powder coating |
DE4217754 | 1992-05-29 | ||
PCT/DE1993/000339 WO1993024242A1 (en) | 1992-05-29 | 1993-04-16 | Method and device for powder-coating |
Publications (2)
Publication Number | Publication Date |
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EP0642391A1 EP0642391A1 (en) | 1995-03-15 |
EP0642391B1 true EP0642391B1 (en) | 1997-07-09 |
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Application Number | Title | Priority Date | Filing Date |
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EP93907803A Expired - Lifetime EP0642391B1 (en) | 1992-05-29 | 1993-04-16 | Method and device for powder-coating |
Country Status (12)
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EP (1) | EP0642391B1 (en) |
JP (1) | JPH07505337A (en) |
KR (2) | KR950701844A (en) |
CN (1) | CN1043906C (en) |
AT (1) | ATE155052T1 (en) |
AU (1) | AU3887693A (en) |
CA (1) | CA2136866A1 (en) |
DE (2) | DE4217754C2 (en) |
ES (1) | ES2105238T3 (en) |
MX (1) | MX9303176A (en) |
TW (1) | TW239084B (en) |
WO (1) | WO1993024242A1 (en) |
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NL7800645A (en) * | 1978-01-19 | 1979-07-23 | Ver Buizenfab | METHOD AND DEVICE FOR MANUFACTURING OUTSIDE COATED TUBE FROM STEEL STRIP AND TUBE MANUFACTURED THEREFORE. |
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NL8204427A (en) * | 1982-11-15 | 1984-06-01 | Troost Houdstermaatschappij B | Internally plastic-coating pipe - by introducing pulverised plastic in horizontal pipe and rotating whilst heating |
JPS63100977A (en) * | 1986-10-17 | 1988-05-06 | Dai Ichi High Frequency Co Ltd | Apparatus for lining pipeline |
CN86206501U (en) * | 1986-11-07 | 1987-08-05 | 上海第五钢铁厂 | Stainless pipe spray-coating and baking device |
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US5071672A (en) * | 1990-05-29 | 1991-12-10 | Commercial Resins Company | Girth weld heating and coating method |
US5202157A (en) * | 1990-08-28 | 1993-04-13 | Mitsui Petrochemical Industries, Ltd. | Method for lining internal surfaces of pipelines |
CN1028496C (en) * | 1990-11-13 | 1995-05-24 | 王理泉 | Method of smearing of metal pipe and its products |
-
1992
- 1992-05-29 DE DE4217754A patent/DE4217754C2/en not_active Expired - Lifetime
-
1993
- 1993-04-16 DE DE59306892T patent/DE59306892D1/en not_active Expired - Lifetime
- 1993-04-16 KR KR1019940704333A patent/KR950701844A/en not_active IP Right Cessation
- 1993-04-16 AT AT93907803T patent/ATE155052T1/en active
- 1993-04-16 CA CA002136866A patent/CA2136866A1/en not_active Abandoned
- 1993-04-16 ES ES93907803T patent/ES2105238T3/en not_active Expired - Lifetime
- 1993-04-16 WO PCT/DE1993/000339 patent/WO1993024242A1/en active IP Right Grant
- 1993-04-16 KR KR1019940704333A patent/KR0127775B1/en active
- 1993-04-16 AU AU38876/93A patent/AU3887693A/en not_active Abandoned
- 1993-04-16 EP EP93907803A patent/EP0642391B1/en not_active Expired - Lifetime
- 1993-04-16 JP JP6500066A patent/JPH07505337A/en active Pending
- 1993-05-28 MX MX9303176A patent/MX9303176A/en unknown
- 1993-05-29 CN CN93106508A patent/CN1043906C/en not_active Expired - Lifetime
- 1993-07-09 TW TW082105494A patent/TW239084B/zh active
Also Published As
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ES2105238T3 (en) | 1997-10-16 |
KR950701844A (en) | 1995-05-17 |
AU3887693A (en) | 1993-12-30 |
CA2136866A1 (en) | 1993-12-09 |
WO1993024242A1 (en) | 1993-12-09 |
KR0127775B1 (en) | 1997-12-30 |
DE4217754A1 (en) | 1993-12-02 |
CN1043906C (en) | 1999-06-30 |
DE59306892D1 (en) | 1997-08-14 |
MX9303176A (en) | 1994-05-31 |
TW239084B (en) | 1995-01-21 |
DE4217754C2 (en) | 1998-04-16 |
EP0642391A1 (en) | 1995-03-15 |
ATE155052T1 (en) | 1997-07-15 |
CN1083127A (en) | 1994-03-02 |
JPH07505337A (en) | 1995-06-15 |
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