Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05B—SPRAYING APPARATUS; ATOMISING APPARATUS; NOZZLES
  • B05B5/00—Electrostatic spraying apparatus; Spraying apparatus with means for charging the spray electrically; Apparatus for spraying liquids or other fluent materials by other electric means
  • B05B5/16—Arrangements for supplying liquids or other fluent material
  • B05B5/1608—Arrangements for supplying liquids or other fluent material the liquid or other fluent material being electrically conductive
  • B05B5/1616—Arrangements for supplying liquids or other fluent material the liquid or other fluent material being electrically conductive and the arrangement comprising means for insulating a grounded material source from high voltage applied to the material
  • B05B5/1625—Arrangements for supplying liquids or other fluent material the liquid or other fluent material being electrically conductive and the arrangement comprising means for insulating a grounded material source from high voltage applied to the material the insulating means comprising an intermediate container alternately connected to the grounded material source for filling, and then disconnected and electrically insulated therefrom
  • B05B5/1633—Arrangements for supplying liquids or other fluent material the liquid or other fluent material being electrically conductive and the arrangement comprising means for insulating a grounded material source from high voltage applied to the material the insulating means comprising an intermediate container alternately connected to the grounded material source for filling, and then disconnected and electrically insulated therefrom the arrangement comprising several supply lines arranged in parallel, each comprising such an intermediate container
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05B—SPRAYING APPARATUS; ATOMISING APPARATUS; NOZZLES
  • B05B12/00—Arrangements for controlling delivery; Arrangements for controlling the spray area
  • B05B12/14—Arrangements for controlling delivery; Arrangements for controlling the spray area for supplying a selected one of a plurality of liquids or other fluent materials or several in selected proportions to a spray apparatus, e.g. to a single spray outlet

Definitions

• the invention relates to an installation for spraying a coating product, such as for example a paint or a varnish, at a controlled rate; it proposes improvements making it possible to precisely control the flow rate of said coating product during a spraying phase and the quantity stored, without the elements for circulating the latter or the elements for measuring the flow rate or the quantity stored being liable to 'be damaged by said product. It relates more particularly to an installation of this type making it possible to very quickly change the coating product.
• the flow rate of the coating product feeding the projector is desirable to constantly adapt the flow rate of the coating product feeding the projector, as a function of the surface to be covered per unit of time.
• the flow rate of coating product must be lower, all other things being equal.
• the paint flow rate should be able to be changed at will throughout a spraying phase.
• the amount needed to paint a given object may vary.
• the product to be sprayed can be abrasive and / or chemically aggressive. Consequently, precision devices ensuring metering and controlling the flow rate, such as pumps, geared sensors, pressure regulators, must be able to resist the action of such products.
• the product to be sprayed can be a non-liquid
• the invention provides a generally satisfactory solution with regard to all these problems thanks to the integration of a particular type of intermediate tank in an installation designed to allow very rapid change of coating product, which constitutes a necessity. absolute in certain industrial fields, in particular the automobile industry.
• the invention makes it possible to avoid, in such an installation, bringing the vulnerable control or measurement members into contact with the coating product by placing them in a hydraulic circuit for controlling the flow and / or metering associated with each intermediate tank.
• the invention therefore relates to a coating product projection installation comprising at least one projector of said product placed opposite a location or passage path for an object to be coated, and intermediate tanks capable of each receiving a predetermined quantity of such a product and connected to supply said projector, characterized in that it comprises two branches for distributing said coating product arranged in parallel between a coating product change unit and said projector and each incorporating an intermediate tank mentioned above and in that each intermediate reservoir contains a movable or deformable wall separating two adjacent chambers, a chamber of coating product inserted in the branch corresponding between said color changing unit and said projector and an actuation chamber filled with a controllable volume of liquid by being connected to means for supplying a controlled flow rate, of such a liquid.
• the installation which has just been defined above is particularly suitable for the case of electrostatic spraying of a conductive coating product, such as for example a water-based paint.
• the single figure is a block diagram of a coating product spraying installation implementing the improvements of the invention.
• the installation comprises a coating product changing unit 211, known per se, also called a color changing unit and at least one electrostatic projector 213 isolated from the ground and connected to a high voltage source 214 adjustable and / or interruptible , which may be taken out of service outside of product projection periods.
• a coating product changing unit 211 known per se, also called a color changing unit
• at least one electrostatic projector 213 isolated from the ground and connected to a high voltage source 214 adjustable and / or interruptible , which may be taken out of service outside of product projection periods.
• the installation comprises two similar distribution branches 200a, 200b each incorporating an intermediate tank 212a, 212b, respectively. These two branches are arranged in parallel between the coating product change unit 211 and the electrostatic projector 213.
• the similar elements belonging to such and such a distribution branch will bear the same reference numerals with the index a or, respectively.
• Each intermediate reservoir 212a, 212b has a variable volume coating product chamber 216a, 216b, inserted between the outlet of the color changing unit 211 and the electrostatic projector 213.
• the projector 213 is of the type known from. rotating "bowl". It has two nozzles directed towards the rotating part and capable of projecting the coating product into said rotating part. The two nozzles correspond to the two distribution branches mentioned above.
• Each intermediate tank is connected to the color changing unit via a conduit 218a, 218b made of insulating material and a controlled valve 219a, 2Î9b located in the immediate vicinity of the intermediate tank and controlling the introduction of the product coating in the corresponding chamber 216a, 216b.
• An outlet from this same chamber is connected to the projector by a controlled valve 220a, 220b, located in the immediate vicinity of the corresponding intermediate tank and a conduit made of insulating material 224a, 224b.
• corrugated valves 226a, 226b are respectively inserted between the conduits 224a, 224b and the projector.
• Another controlled valve 221a, 221b is interconnected between each conduit 218a, 218b, respectively and a discharge conduit 217a, 217b made of insulating material.
• the valves 221a, 221b are close to the valves 219a, 219b, respectively.
• These two evacuation conduits open into a common conduit connected to drain means 222 connected to the ground.
• the valves 226a, 226b are in the immediate vicinity of the projector and mounted on the same block 227 as the projector isolated from the ground.
• each conduit 224a, 224b, connected to the valve 226a, 226b is also connected to the purge means 222 via a controlled valve 228a, 228b carried by the block 227 and a conduit made of insulating material 229a, 22913 respectively. These two conduits meet in a common conduit 229 connected to the purge means 222 mentioned above.
• the two intermediate tanks 212a, 212b are part of a set 230, here installed at a fixed station, electrically isolated from the ground. The two intermediate tanks are also isolated from each other. Valves 219, 220 and 221 are also part of this isolated assembly as well as injection valves of cleaning product 232a, 232b, ordered.
• valves 232a (here two in number) associated with the tank 212a have their inputs interconnected and supplied in common by a cleaning unit 234a (external and connected to the ground) via a conduit made of insulating material 233a.
• valves 232b associated with the intermediate tank 212b have their inputs interconnected and supplied in common by a cleaning unit 234b, via a conduit made of insulating material 233b.
• the valves 232 are respectively connected to injectors (not visible in the diagram) opening into the corresponding coating product chamber 216 at locations and according to chosen orientations.
• Each of these valves thus interposed between a cleaning unit 234a or 234b and an injector, is here directly mounted on the side of the case of the intermediate tank, in the immediate vicinity of the corresponding injector.
• a discharge valve 223a, 223b is connected between the chamber 216a, 216b and the discharge conduit 217a, 217b, respectively.
• a bypass valve 225a, 225b is connected between the common inputs of the valves 232a, 232b and the evacuation pipe
• Each cleaning unit 234a, 234b and others which will be mentioned later, comprises controlled connection means, constituted here by valves 240, 241, able to put successively and sequentially in communication with the chamber 216 (via the conduit 233 ) either a circuit for the circulation of cleaning product 242, under pressure, or a compressed air distribution circuit 243.
• the cleaning product can be water added with alcohol.
• Each intermediate reservoir 212a, 212b contains a movable wall consisting of a deformable membrane 245a, 245b in the form of a disc, dividing the internal space of the intermediate reservoir into two adjacent chambers, the coating product chamber 216a, 216b with which the valves 219, 220, 223 and 232 and an actuation chamber 246a, 246b, respectively, whose role will be analyzed below.
• the chambers 216 and 246 each have the shape of a spherical cap when the membrane is in its middle position in the absence of stress, as shown in the drawing.
• the radius of curvature of the fixed wall of each chamber is determined so that the membrane can be applied against this wall, if necessary, and thus reduce the volume of said chamber to a practically zero residual value.
• the two in ectors are substantially diametrically opposite and open into the chamber 216, along the perimeter of the membrane and close to the latter. They can be oriented approximately tangentially. Their role is to create swirling movements of air and / or cleaning product in chamber 216 to obtain rapid and effective cleaning.
• a controlled valve 231a, 231b, located in the vicinity of the valve 220a, 220b is connected between the conduit 224a, 224b and a cleaning unit 235a, 235b via a conduit 237a, 237b made of insulating material, respectively.
• the projector 213 is capable of being placed in communication by a controlled valve 248a and a conduit 249a made of insulating material with a cleaning unit 250a.
• the valve 248a is connected to the outlet of the valve 226a and in the immediate vicinity thereof.
• the projector 213 is capable of being put in communication, by a controlled valve 248b and a conduit
• the cleaning units 250a, 250b are therefore more specifically responsible for cleaning the projector 213, alternately, during successive color change cycles.
• the coating product change unit 211 comprises a set of selection valves 210 making it possible to put its outlet manifold 2 ′ 52 (connected to the conduits 218a and 218b via a gate valve three-way 215) in communication with one of the following circuits:
• Controlled drying valves 238a, 238b are interconnected between the compressed air distribution circuit 243 and each of the outputs of the three-way valve 215, respectively.
• At least one of the conduits made of insulating material connecting the color change unit 211 or a cleaning unit 234, 235, 250, to the insulated assembly 230 comprises a section S shaped as a serpentine.
• a serpentine section is provided on each of these conduits 218, 233, 237 and 249.
• Similar serpentine sections S are provided on the conduits 217 and 229 returning to the purging means 222 and on the conduits 224 connecting the intermediate tanks to the projector.
• Each coil S is preferably oriented so that its axis is substantially horizontal. This prevents the formation of a continuous film of liquid inside the conduit when it is not full.
• the electrical "path” is thus cut at each turn and the droplets of residual liquid are "trapped” while waiting for their complete evaporation in the substantially horizontal parts of the coil.
• means are provided for permanently blowing air into the aforementioned insulating material conduits, for at least part of the time during which the high voltage is applied to one or other of the branches of distribution 200a, 200b, via the projector 213, brought to high voltage and the conductive coating product. This is done by leaving some of the valves described above open to let air circulate in these conduits between the air distribution circuit 243 and the purge means 222.
• the action chamber between 246a, 246b of each intermediate reservoir 212a, 212b is filled with a variable volume of actuating liquid by means of supply means with controlled flow 260.
• supply means comprise a tank 258 for the storage of actuating liquid 257, a pump 261 connected between this reservoir and the inlet of a three-way valve 264 and two conduits made of insulating material 259a, 259b respectively connected to each of the outlets of the three-way valve • tracks 264.
• These two conduits open respectively into the actuation chambers 246a, 246b.
• Flow sensors 262a, 262b are respectively inserted in the conduits 259a, 259b. These are sensors
• volumemetric whose structure is very similar to that of a gear pump.
• the pump 261 is also preferably a positive displacement pump such as for example a gear pump. It is driven by a self-piloted synchronous motor M and protected against overpressure by a limiter 280.
• Return valves 266a, 266b, controlled are respectively interconnected between each of the outputs of the three-way valve 264 and the tank 258.
• the elements supply means 260 are grounded as is the reservoir 258.
• the liquid 257 is an insulating liquid, not tonic, such as oil, so that no particular precaution is to be taken with regard to concerns the electrical insulation between said supply means, the reservoir 258 and the intermediate reservoirs 212,
• the installation also comprises means for controlling the flow of liquid when the latter flows towards one or the other of rooms 246a, 246b.
• control means include the sensors 262a, 262b and control the pump 261. They include transducers 268a, 268b coupled respectively to the sensors 262a, 262b and deliver usable electrical signals, a comparator 269 and a computer 270. The setpoint signal of the comparator is developed by the computer. The output of the comparator 269 is applied to a motor control input M which drives the pump 261.
• the signals delivered by the sensors 262a, 262b are alternately selected by the computer and applied to the comparator 269.
• the flow sensors 262a, 262b can be used regardless of the direction of circulation of the actuating liquid in the conduits 259a, 259b, respectively. In a direction corresponding to the filling of a chamber 246, the sensor is part of the pump flow control chain. In the other direction of circulation, it only measures the quantity of liquid returning to the reservoir 258, which makes it possible to know at any time the volume of coating product introduced into the corresponding chamber 216.
• the computer 270 also controls the sequencing of all the valves of the installation and selects the transducer 268a, 268b depending on whether it is to fill the actuation chamber 246a or 246b.
• the computer 270 can contain and / or receive all the data making it possible to determine the law of variation of the flow rate of the coating product when it is discharged towards the projector 213, by acting on the filling of the actuation chamber 246a , 246b corresponding.
• the computer controls the filling of the chamber 216a, 216b by controlling the opening of the valve 266a, 266b of the valve 210 and of the corresponding valve 219a, 219b thus that the positioning of the three-way valve 264 and by controlling the quantity of coating product introduced into a chamber 216 via the measurement of the quantity of actuating liquid returning to the reservoir.
• the computer 270 is programmed to control the sequencing of all the valves according to a sequence which will now be described. 11
• the projector 213 is supplied with coating product contained in the intermediate tank 212b.
• the valves 232b, 219b and 223b are closed. Valves 220b and 226b are open.
• the pump 261 delivers actuating liquid into the conduit 259b via the three-way valve 264 and the flow sensor 262b.
• the coating product is therefore discharged into the conduit 224b and the actuation chamber 246b is filled with actuation liquid.
• the coating product is therefore applied by the electrostatic headlamp 213 brought to high voltage.
• another coating product supplied by the coating product changing unit 211 passes through the three-way valve 215 and flows into the conduit 218a.
• the coating product is introduced into the chamber 216a through the open valve 219â.
• the actuating liquid is expelled from the chamber 246a and returns to the reservoir 258 by passing through the flow sensor 262a and the valve 266a.
• the insulation is maintained in the duct 218b by a flow of air flowing from the valve 238b, open, to the purge means 222, the valve 221b being open.
• valve 219a Towards the end of the period tank • use of intermediate 212b and when a predetermined amount of coating material was introduced into the tank 11 via 212a, the valve 219a is closed and the cleaning agent and air flow in the conduit 218a, from the coating product change unit to the purge means 222, the valve 221a being open.
• the projector 213 When the projector is not facing any object to be painted, the projector 213 itself is cleaned and dried, from the cleaning unit 250b and from the conduit 249b, the valve 248b being open and the valve 226b being closed.
• the cleaning of the duct 224b is carried out simultaneously from the cleaning unit 235b, the cleaning product and the air flowing successively through the duct 237b and the valve * 231b, the valve 228b being open towards the means of purge.
• it begins to circulate new coating product through the conduit 224a by introducing actuating liquid into the chamber 246a, the valve 226a being open and the two valves 248a and 228a being closed.
• the actuating liquid is discharged to the reservoir 258 via the conduit 259b, the flow sensor 262b and the valves 266b, 219b and 210.
• the computer controls the closing of the valve 266b.
• the intermediate tank 212b is then full and ready for a new use.
• the conduit 218b begins to be cleaned from the coating product change unit 211, the valve 221b being open.
• the high voltage is cut and cleaning of the projector is started through the conduit 249a and cleaning of the conduit 224a from the cleaning unit 235a.
• Actuating liquid is injected into the chamber 246b of the intermediate reservoir 212b to prime 13 the discharge of the new coating product to the projector.
• the valves 248a and 228a are then closed and the projector 213 is ready to paint a new object from a coating product coming from the intermediate tank 212b.
• the same operations are then repeated in the same order indicated above.

Landscapes

• Electrostatic Spraying Apparatus (AREA)
• Spray Control Apparatus (AREA)

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Publications (2)

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ID=9378711

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• 1990
  • 1990-02-12 WO PCT/FR1990/000100 patent/WO1990009244A1/fr active IP Right Grant
  • 1990-02-12 DE DE90903378T patent/DE69003621T2/de not_active Expired - Fee Related
  • 1990-02-12 EP EP90903378A patent/EP0411098B1/de not_active Expired - Lifetime
• 1991
  • 1991-01-02 US US07/576,450 patent/US5106024A/en not_active Expired - Fee Related

Non-Patent Citations (1)

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