EP0737520A1 - Verfahren und Vorrichtung zum Wechseln von Beschichtungsmaterial in einer Anlage zum Spritzen von Beschichtungsmaterial - Google Patents

Verfahren und Vorrichtung zum Wechseln von Beschichtungsmaterial in einer Anlage zum Spritzen von Beschichtungsmaterial Download PDF

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Publication number
EP0737520A1
EP0737520A1 EP96420118A EP96420118A EP0737520A1 EP 0737520 A1 EP0737520 A1 EP 0737520A1 EP 96420118 A EP96420118 A EP 96420118A EP 96420118 A EP96420118 A EP 96420118A EP 0737520 A1 EP0737520 A1 EP 0737520A1
Authority
EP
European Patent Office
Prior art keywords
product
conduit
phase
during
filling
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.)
Withdrawn
Application number
EP96420118A
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English (en)
French (fr)
Inventor
Philippe Foury
Eric Prus
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Sames SA
Original Assignee
Sames SA
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Sames SA filed Critical Sames SA
Publication of EP0737520A1 publication Critical patent/EP0737520A1/de
Withdrawn legal-status Critical Current

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    • 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 a method and a device for changing a product in an installation for spraying coating products. It considerably limits the loss of paint during color changes.
  • the purge valve which connects the connection conduit between the product change block and the projector on the one hand and the purge bypass on the other hand is then closed.
  • the head valve which is located at the base of the projector is then opened for an instant, for example 500 ms, to initiate the discharge of new product from the projector.
  • the projector is now ready to operate.
  • the latter solution is chosen to avoid any danger of bad spraying due to a lack of paint.
  • the duration of this phase is difficult to determine because it depends on the product supply pressure, which varies from one supply circuit to another, that is to say a product of coating to another, and its viscosity which may itself depend on the ambient temperature.
  • the higher the supply pressure the greater the quantity of product lost.
  • this quantity increases with the fluidity of the product used.
  • the filling rate of the duct must be high because a change of coating product must take place in the shortest possible time interval, this high flow rate is directly proportional to the amount of product lost during the change of product.
  • a flow meter of the type usually placed on the projector supply pipe and which allows the control of product flow during the spraying phases, cannot be used to regulate the quantity of product which fills the pipe because, during during the filling phase, this flow rate reaches several liters per minute while the operating range of such a flow meter is between a few tens and a few hundred cubic centimeters per minute. An uncontrolled quantity of coating product is thus discharged in purge each time the coating product is changed.
  • a sensor for example an optical or capacitive sensor to detect the arrival of paint at the level of the purge.
  • the sensor emits a signal which is interpreted to close the purge valve: this eliminates errors due to the variations set out above.
  • the response times of these sensors and valve control systems are around 500 ms. Taking into account the product flow during the filling phase, between the moment when the sensor detects the front of new product and the closing of the purge valve, approximately 30 cc of paint has flowed into the purge. Indeed, the response time of the sensor and the activation time of the valve add up to give a reaction time of the system close to one second.
  • It relates to a process for changing a product in an installation for spraying coating products comprising a supply duct for a projector with said product, of the type comprising a phase of filling said duct with a new product, characterized in that the downstream end of said duct is kept isolated during said filling phase.
  • the filling phase is followed by a separate phase, called the distribution phase, during which the flow rate of coating product can be controlled and reduced and which includes a step of evacuating the air accumulated in the downstream part of the duct and a stage of priming the projector.
  • the distribution phase a separate phase, called the distribution phase, during which the flow rate of coating product can be controlled and reduced and which includes a step of evacuating the air accumulated in the downstream part of the duct and a stage of priming the projector.
  • the flow meter is not active during the distribution phase.
  • the management of valve openings and closings is carried out by time delay.
  • the invention also relates to a product change device in an installation for spraying coating products comprising a supply duct for a projector, characterized in that it comprises an arrangement of valves arranged so as to fill said duct, during changes of coating product, by isolating said duct from said projector.
  • This device makes it possible to implement the method of the invention.
  • the operation is as follows: At the end of a spraying phase, when it is necessary to change the product, the valves of colors C 1 to C n are closed and the valves of air A and of solvent S are alternately open. Trains of air and solvent are thus sent into the duct 2 to clean it. With the head valve open, these trains air and solvent pass through the projector 3 and are discharged into a suitable place in the installation's coating booth, for example a grating. When the duct 2 and the projector 3 are cleaned, that is to say in practice after a few seconds of cleaning, the valves A and S are closed. The head valve T is then closed to isolate the projector 3 from the duct 2.
  • the valve C i corresponding to the coating product chosen for the next spraying phase is then opened and a filling phase takes place during which the coating product chosen is poured into the conduit 2, the downstream end of which is isolated from the headlight since the valve T is closed.
  • the volume of air present in the duct 2 at the start of the filling phase is compressed at the downstream end of the duct, the compressed air pressure being equal to the pressure for supplying the coating product, ie in an installation industrial between 6 and 12 bar.
  • the filling flow can be high, of the order of several liters per minute, because the flow meter 4 is not active during this phase, the filling taking place until the air and product pressures s 'balance. No coating product was spilled in the cabin during the filling phase.
  • the flow rate in the duct 2 is of the same order of magnitude as during the spraying phases, for example 200 cubic centimeters per minute, since the regulator 5 establishes a sufficient pressure drop.
  • the flow meter 4 is thus able to provide a representative signal which can be integrated by the control unit to determine the volume of product entering the conduit.
  • the control unit closes the head valve as soon as a predetermined quantity of product has entered the duct.
  • the quantity of product which must enter the duct can be calculated as that equal to the volume V a of compressed air in the duct, plus a safety margin determined by the operator, this safety margin also serving to evacuate the possible solvent residues.
  • the control unit closes the head valve T as soon as the volume V has been detected by the flow meter 4 and the quantity of product lost during this evacuation step is zero or almost zero, at the response time of the control unit, which is a few milliseconds, which, taking into account the flow rate considered during this step corresponds to a maximum loss of 2 or 3 cc, this loss including the solvent residues pushed by the front of the new product .
  • the valve B is closed during the priming step. No new coating product is allowed in the duct, but the internal volume of the duct decreases during this step.
  • a pressure pulse is applied to the control input of the pressure regulator 5 so that the coating product contained in the chamber of the regulator which is part of the conduit is expelled from the latter.
  • the product does not rise upstream of the duct which is closed by the valve B but flows downstream of the duct where the valve T is open.
  • this valve is generally a pneumatic valve whose response time is longer than that of a solenoid valve.
  • the valves T and / or P can be controlled by time delay, that is to say kept open for a determined time interval corresponding to the estimated evacuation of the compressed air and the remains solvent.
  • the uncertainty on the quantities of product poured through the projector is divided in the ratio of the volumes V a and V b which corresponds to the inverse ratio of the pressures. If the product is supplied under a pressure of 6 bars, the uncertainty is therefore divided by 6 (ratio 6 to 1), which represents a substantial saving.
  • the device of FIG. 2 comprises certain elements identical to that of FIG. 1, the references of which are the same.
  • a purge bypass 8 is provided in the direction of a recovery system 9.
  • a purge valve P makes it possible to open or close the purge bypass according to the instructions given by the control unit.
  • the step of evacuating the compressed air in the duct 2 takes place by opening the valve P, a small amount of product, of the order of a few cc, being poured into the recovery system 9.
  • the valve B 'corresponding to valve B is a valve with a calibrated flow of small diameter which allows the flow of a low product flow when the valve is in the closed position.
  • the operation is as follows:
  • the cleaning phase is similar to that described with reference to FIG. 1.
  • the valve B ' is closed, the purge valve P is open while the head valve T stays closed. Due to the calibrated flow of the valve B ', the flow rate of coating product is limited to a lower value during the distribution phase than during the filling phase, which allows the flow meter 4 to ensure its counting function, in line 2.
  • the end of the evacuation step is calculated by the control unit according to the volume of product introduced into the conduit 2.
  • the valve P is then closed and the priming step takes place during which, the valve T being open, the new coating product enters the projector 3.
  • the flow meter operates as in the previous step and the same accuracy can be achieved.
  • the valve B ' is again opened to allow the product to flow without loss of pressure.
  • the function of the valve B ' can be achieved by means of a valve identical to the valve B in parallel with which is connected a calibrated branch of small diameter.
  • valve B ′ could be fulfilled by a pressure regulator similar to regulator 5, the pressure drop of which would be controlled to be greater during the distribution phase than during the filling phase, which would decrease the flow in the duct 2 and allows the flow meter 4 to fulfill its counting function under acceptable conditions.
  • the variations in viscosity and / or temperature of the products have little influence on the quantity of product poured into the purge during the changes. Indeed, the filling phase will be more or less long but no product will be lost during this phase.
  • the introduction of the product is controlled in volume and variations in viscosity have no effect. If the product supply pressure varies, for example from 6 to 8 bars, the volume of compressed air in line 2 will be lower at the end of the filling.
  • the distribution phase takes place as before and, if the computer receives the information of the pressure change, the volume corresponding to the closing of the valve P is adjusted by calculation.
  • the quantity of coating product discharged to the drain will be greater by a volume corresponding to the difference compressed air volumes, at 6 and 8 bars. This quantity remains much lower than that obtained with the installations of the prior art.
  • the method and the device of the invention can be used whatever the type of coating product, water-soluble or solvent-based and whatever the type of headlamp, electrostatic or not, pneumatic or with rotating bowl.
  • the invention also applies to the case where the head valve and the purge valve are integrated in the headlight.
  • the evacuation step and the priming step are then simultaneous.

Landscapes

  • Spray Control Apparatus (AREA)
  • Application Of Or Painting With Fluid Materials (AREA)
EP96420118A 1995-04-11 1996-04-10 Verfahren und Vorrichtung zum Wechseln von Beschichtungsmaterial in einer Anlage zum Spritzen von Beschichtungsmaterial Withdrawn EP0737520A1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR9504672 1995-04-11
FR9504672A FR2732908B1 (fr) 1995-04-11 1995-04-11 Procede et dispositif de changement de produit dans une installation de projection de produits de revetement

Publications (1)

Publication Number Publication Date
EP0737520A1 true EP0737520A1 (de) 1996-10-16

Family

ID=9478248

Family Applications (1)

Application Number Title Priority Date Filing Date
EP96420118A Withdrawn EP0737520A1 (de) 1995-04-11 1996-04-10 Verfahren und Vorrichtung zum Wechseln von Beschichtungsmaterial in einer Anlage zum Spritzen von Beschichtungsmaterial

Country Status (2)

Country Link
EP (1) EP0737520A1 (de)
FR (1) FR2732908B1 (de)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2416720A (en) * 2004-08-03 2006-02-08 Decoma Int Inc Multiple fluid delivery system

Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1120058A (en) * 1965-07-08 1968-07-17 Devilbiss Co A control system for a spray apparatus
US3672570A (en) * 1970-09-04 1972-06-27 Nordson Corp Sequence control of color change
US3939855A (en) * 1974-05-10 1976-02-24 The Gyromat Corporation Recovery system for spray painting installation with automatic color change
FR2572662A1 (fr) * 1984-11-05 1986-05-09 Ransburg Sa Procede et appareil pour le revetement automatique par pulverisation electrostatique
FR2618087A1 (fr) * 1987-07-15 1989-01-20 Graco France Sa Procede de selection d'un fluide avec commande et regulation de son debit et dispositif mettant en oeuvre le procede et installation d'application de peinture avec selection de couleur mettant en oeuvre le procede
US4881563A (en) * 1986-09-05 1989-11-21 General Motors Corporation Paint color change system
EP0459892A1 (de) * 1990-05-31 1991-12-04 Sames S.A. Farbspritzanlage mit kontrolliertem Durchfluss
EP0568910A1 (de) * 1992-05-04 1993-11-10 ABB Fläkt Ransburg GmbH Verfahren und Vorrichtung zum Reinigen einer Farbbeschichtungseinrichtung

Patent Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1120058A (en) * 1965-07-08 1968-07-17 Devilbiss Co A control system for a spray apparatus
US3672570A (en) * 1970-09-04 1972-06-27 Nordson Corp Sequence control of color change
US3939855A (en) * 1974-05-10 1976-02-24 The Gyromat Corporation Recovery system for spray painting installation with automatic color change
FR2572662A1 (fr) * 1984-11-05 1986-05-09 Ransburg Sa Procede et appareil pour le revetement automatique par pulverisation electrostatique
US4881563A (en) * 1986-09-05 1989-11-21 General Motors Corporation Paint color change system
FR2618087A1 (fr) * 1987-07-15 1989-01-20 Graco France Sa Procede de selection d'un fluide avec commande et regulation de son debit et dispositif mettant en oeuvre le procede et installation d'application de peinture avec selection de couleur mettant en oeuvre le procede
EP0459892A1 (de) * 1990-05-31 1991-12-04 Sames S.A. Farbspritzanlage mit kontrolliertem Durchfluss
EP0568910A1 (de) * 1992-05-04 1993-11-10 ABB Fläkt Ransburg GmbH Verfahren und Vorrichtung zum Reinigen einer Farbbeschichtungseinrichtung

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2416720A (en) * 2004-08-03 2006-02-08 Decoma Int Inc Multiple fluid delivery system

Also Published As

Publication number Publication date
FR2732908B1 (fr) 1997-05-16
FR2732908A1 (fr) 1996-10-18

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