Device for the electrostatic covering of articles also in finely divided form available materials

The invention concerns a device to the e1 ektr0 static covering of articles also in finely divided form over-lying materials, which are submitted in the device of a Durchwirbelung and/or a destruction and loaded through on Hochspannnng in relation to the article concerned lying LadeeleRtroden on an appropriate potential and led in such a way in a Teilchenwolke on the article. Such devices for electrostatic covering, with which the Stoffteilchen are led along the field lines of the electrical field developed between the Zerst uberhopf and the article which can be covered with them, possess meaning advantages, in particular higher uniformity in the strong one the coat layer, smaller losses in relation to the other usual procedures for the covering of Gegenständeu to Überzugsmaterial and better connection of the same on the surfaces of the article concerned which can be covered, whereby a Vorbeheizung of these surfaces becomes redundant. Such devices have from there in the last years a far Anwendtmgsfeld gewon - nen, in particular since then elektrostätische high-energy units in practical and pushed building method for the order, necessary for it. The invention is the basis the task to create a device of the kind initially specified which is particularly suitable for the execution of a procedure for the covering of articles, suggested already in former times, with which the Überzugsmaterial is powdered and is present in form of a Wirbelscbächt, whereby the powder is electrostatically loaded and tightened of to Uberziehenden Gegenständenals backplate electrode, so that it remains clinging on these in form of a layer. For this purpose a gas in a Vielzah becomes the Durchwirbelung of the powder into this! smaller currentunder pressure imported. In such a way whirled up Stoffteilchen are loaded by means of into this fluidised bed of projecting load electrodes electrically on the necessary potential in relation to the article concerned which can be covered. DieLadeetektroden exist hiebei in well-known way to sharpening, wires or sharp edges, which are arranged vorzngsweise on a porous base plate the fluidised bed of the powder of containing container, by which the Dmckgas into the powder layer flow in. Apart from the advantages of well-known devices for elektrostatäscheu the covering of articles, already mentioned, this suggested procedure mentioned above possesses still the preference/advantage that the relatively steady fluidised bed is particularly suitable to form a constant source of loaded Stoffteilchen which remain spatially relatively stationary at a coat plant, at which the articles which can be covered be sequentially led past can. Znr creation of the source of particle at the coat plant a minimum of work and energy is necessary. The further development this already in former times vorgeschlagenenVeffahrensund the Vorrichtnngen planned for its execution however proved, D ate the gescbaffene material particle cloud stability lacking aufweistoHiebei it than extremely with difficulty turned out to cause surely that within the container to a sufficient height up-increases the Stoffteilchen, in order freely by the article which can be covered are tightened to be able. Furthermore it was difficult to be avoided at the same time that the particles ascend so highly that they are buried beyond the container to a considerable ö extent, in particular if no workpiece or only a relatively small article in the coat plant is present. It is a principal purpose of the invention to create a device yields the mentioned disadvantage avoids and the 8toffteflchenwolke more exactly steers as well as their stability to increase lets. Furthermore it is purpose of the invention to plan improved performing with which the spatial extent of electrically loaded coat material particles in such a coat plant is steered, indifferently whether it hiebei around an atomizer pistol or a mechanism working after the DurchwirbelungsVerfahren concerns. This versatile Aufgabenstellnng becomes the erfindnngsgemäße device above all thereby fairly that one or more Stenerelektroden are intended, which on gegentlber that the drawer - electrodes substantially different potential Uegen and in the area are arranged, which is present between the load electrodes and the too tiberziehenden article and of the Teilcbenwolke pulled through becomes. This Steaerelektroden planned in accordance with the invention limits and regulates räumli - the che extent of the cloud of the Überzugsstoffteüchen. Further in the Unteransprüchen stated characteristics that vorgesehlagenenVorrtchmng and by 90 them obtained advantages come out here from the following Beschreibnng of the Zeächnungen, which illustrate a device effindnngsgemäß of the suggested kind in several execution forms for example selected schematiseh. Fig show. 1 on senkrechten average a first Ausführangsform of such a device, Fig.2 in a simplified, partly abgebroelmnen chart a further Ausführtmgsform of the hie suggested device. The device in accordance with Fig. 1 points a tank or a container! from electrically isolating material for the admission of the Überzugsmaterials up. In the distance to the ground of this container 1 is a horizontal partition wall 2 intended, which is partly air permeable, e.g. from a porous Keramikplatte or one with cheek by jowl lying small broke through provided Meta! lbleeh exists; the material of the partition wall 9 can be isolating electrically leading or. Within the container 1 a mass 3 from Überzngsmaterial, e.g. synthetic resin powders, Emailpulver, metallic powders or other fine-distributable materials is on the surface of its partition wall 2. A Rehfleitung 4 is attached at a side panel D of container 1 underneath its partition wall 9 and ftibxt at their other end too one-compressed gas-pours, e.g. compressed air, whereby not represented Ventüe is intended for the controlling of the Gasströmnng by the piping 4. If over the Rohrieitung 4 in dießodenkammer the container i underneath the partition wall 2 Dxuekgas is introduced and dnrch pores or break-throughs of the partition wall 2 it flows the gas rises by those powder layer 3 and through-whirls it to hold Nm it in such a way in a condition of constant movement and whirling whereby the particles zufglligeßahnen for instance in such a manner from molecules a liquid describe. However particle wool remains stationary as whole within the container verhälmismäßig. In such a condition of the Durchwirbelnng naturally the upper border of particle wool leans dazn, substantially more tiber the upper level in the static to rise thus not through-whirled condition powder layer present 3. At the ground of the container 1 with 5 a hint vibrator is if necessary intended to introduce over the eddy effect and/or or zuverbessem. To electrical loading of the particles in the finely divided Tei! before cloud are intended several pointed electrodes 6 arranged in a row, which can be metallically or from a Halbleitergefertägt. The electrodes 6 by carrier seaweeds a t0 above the porous partition wall 2 is fallen, how the points are upward arranged this after electrodes and the electrodes in the enterprise within the Wtxbelschtcht and/or the Tei! chenwolke to lie come. The electrodes 6 are over those carrier seaweeds 10 and an insulating AnsohluNeitung 11 to a clamp einerHochspnnnnngque! le 7 electrically switched, one high DC voltage approximately into the Größenordnnng from. kV and more delivers 100, e.g. an electrostatic generator, whereby the other connection clamp of this source of high voltage is grounded. Preferably the electrodes 6 are arranged in spatial relationship in 5g of an even row, which extends waagmcht by the Teilchenwolke. In the enterprise of this so far device suggested already in former times. i.e. with attached high - 3 - Nr.24? 997 supply terminal, the powder layer 3 is transferred of 7 and with compressed air supply by the Rohrleimng 4 into the container 1 into a Wlrbelschicht, and on the one hand particles of the material cloud work the peak electrodes 6 the source of high voltage 7 appropriate high electrical Potentia by direct contact with the whirled up particles and on the other hand over ionized air molecules, around a11en! to mediate. If the not represented are led past, grounded to überzäehenden article, e.g. by a chain conveyor before long distance over the upper opening the containers of the 1, then strong that-concerned the electrical field developed between denIonisierelektrodea 6 and article causes that the particles of the material cloud are led along the field lines of this field to the surface of the article concerned which can be covered. This surface is occupied thereby rapidly and effectively with the powder, which remains sticking to that surface of the article by electrostatic attraction firmly. As already it say-had to be able itself to steer as difficult put out, effectively those height, around which the cloud of finely divided particles in the container rises. Resisting in addition, this height naturally partly of the flow quantity and flow rate over the Rohrleimng 4 introduced Dmckgases depends, plays electrical factors a role. The loaded Tei! - chen are inclined to push off each other. In particular with absence of a relatively large article, which presents itself the Teilchenwolke, electrical Streuoder perturbative fields is inclined to set Stoffteilchen off on neighbouring grounded articles. Thus it lacks the Stoffteilehen - cloud at stability, it is uneven in its characteristics and is inclined to rise too highly and be buried over the edge of the container. According to invention by the fact it is met to these difficulty that gate electrodes 8 are intended. These gate electrodes possess for example the form by peak electrodes, the same the load electrodes 6 and to the metal or a Widerstandsoder semiconductor material manufactured to be can. They are supported of the side walls of the container 1 in a pre-determined height above that charge electrodes 6. Their points project into the container 3. The gate electrodes 8 are attached to earth. ImBetrieb cause these expensive electrodes 8 that them approaching particles unload themselves of the material cloud either by direct contact, above all however by ionization of the air molecules, which ions with that of the Pulverteilchen of opposite polarization schafferi. The Erfahrüngzeigt. that the number and situation of gate electrodes 8 can be determined in such a way that the height of the StoffteiIchenwolke with one good-accuracy-measured, regardless of the presence or absence one-grounded Gegcnstandes above the container, to be regulated can. Likewise it makes the presence of gate electrodes possible in accordance with the invention to cover thes subject of small dimensions with powder without powder from the container in unwanted A usmaße is verschattet or wasted. The electrodes 8 let develop an electrostatic Steueffeld within the container 1, in him contained loaded Teilchenwolke opposite unerwtlnschtenNebenfeldern less sensitively make and thus the stability of the Teilchenwolke improved. With in Fig. 2 represented Ausftihrungsform is intended a container 1, which contains a powder layer 3. Furthermore is as one-facility-intended during the device represented in Fig.1 (represented, by the powder layer 3 does not through-blow the one compressed gas, e.g. air in small rivers, in order to transform this in a fluidised bed and a Teilchenwolke. Furthermore are for example the electrodes 6 the Fig. 1 appropriate mechanisms intended, which can take however also different forms; e.g. .kann the Pulvemehicht 3 basic broken through horizontal partition wall meta! lischund as load electrode in accordance with proposals made already in former times trained its. With this execution form the Stenerelektroden is in accordance with the invention of fine, in the top of the eddy container,1 isolates strained wires 8 ", e.g. stainless steel wires with a diameter of 0, 1 or 0, g mm in an educated manner. For example here two such wires are intended, around the inner wall of the container extend and perpendicularly to each other arranged and by the container wall through tsolierstützen 9 held being both wires 8 ' are because of earth. Of course one can use also only one such wire 8 • or more than two. The mode of operation of the execution form in accordance with Fig.2 does not need to be described, since it is essentially the same as with the Ausführnngsform in accordance with Fig. 1. PATENT CLAIMS; 1. Device for the electrostatic covering of articles also in feinverteHter form pre