EP0088668A1 - Automatic device for painting the interiors of automobile bodies - Google Patents

Abstract

Automatic installation for painting comprises in combination a mechanism (1) carrying two electrostatic paint sprayers (21) and arranged to move them in three movements so as to modify respectively their spacing, their distance from the axis (5) and their general orientation relative to the axis, with in addition a work handling means (35) ensuring a fourth movement which consists in a controlled movement of the bodywork in the direction of the axis on the outward and return path.

Description

The invention relates to painting the interior surface of motor vehicle bodies or of any similar enclosure such as a cabin; container or wagon.

The painting of vehicle exteriors using centrifugal atomizing electrostatic spray heads is common. This process has the advantage of an excellent yield in the application of paint (quantity of paint deposited in relation to the flow rate of the paint). gun). However, the interior surfaces are not covered by the paint sprayed by an electrostatic sprayer placed outside because of the Faraday cage phenomenon which protects the interior space against the penetration of the electric field.

For this reason the painting of vehicle interiors is usually carried out by non-electrostatic sprayers which have to be moved in a relatively complex movement. This movement is carried out manually, in painful and unsanitary conditions. In addition, a significant part of the sprayed paint is hidden and deposited around it.

pas s'échapper de la carrosserie, et que la

s'échapper par les larges ouverturesn loin d'être perdue

par les effets electrostatiques sur les feuil-

The object of the invention is to avoid the above drawbacks by painting the interiors in a simple, efficient and economical manner. The invention consists in using at least one electrostatic spray head with ccentrifugal atomization which is moved with a simple movement inside the bodywork or the enclosure joined to ground. This results in a confinement phenomenon where an electric field inside the bodywork according to a Faraday cage phenomenon operating in opposite directions to each other so that the paint particles cannot

not escape from the body, and that the

escape through the wide openingsn far from being lost

by electrostatic effects on the sheets

The paint yield is therefore even better than in the case of usual exterior paints and the displacements necessary for the spray head (s). High-speed centrifugal atomization electrostats are greatly simplified

Thus, according to a first example of a device for implementing the invention, more particularly intended for large industrial vehicles, the installation uses a mechanism with three degrees of freedom carrying. two electrostatic sprayers and making it possible to modify their spacing, their distance to the vehicle axis respectively, and their overall orientation around this axis with work handling moving the vehicle in the direction of its axis of movement- back and forth.

In a second example of a device for implementing the invention, more particularly intended for touring bodies, these bodies run in a uniform movement on a chain while a single electrostatic rotating bowl is placed inside. and at the front of the vehicle in a fixed position, providing only a mechanism with two degrees of freedom to ensure the lateral retraction of the sprayer and of the arm which carries it, then on reversing to place it in the following interval and its advancement through the rear opening of the vehicle to the front position.

• la fig. 1 est une vue schématique de dessus de l'installation selon le premier mode de réalisation;
• la fig. 2 est une coupe verticale partielle de la partie essentielle de ce mécanisme;
• la fig. 3 est une vue de dessus de ce même mécanisme ;
• la fig- 4 est une vue en élévation de l'installation selon le deuxième exemple de réalisation;
• la fig. 5 est une vue de dessus de cette même installation; et
• la fig. 6 est une vue en bout de la chaîne montrant le mouvement de basculement.

Other features of the invention will appear in the following description of two embodiments corresponding to the two examples above and represented in the appended drawing, in which:

• fig. 1 is a schematic top view of the installation according to the first embodiment;
• fig. 2 is a partial vertical section of the essential part of this mechanism;
• fig. 3 is a top view of this same mechanism;
• fig- 4 is an elevational view of the installation according to the second embodiment;
• fig. 5 is a top view of this same installation; and
• fig. 6 is an end view of the chain showing the tilting movement.

The method according to the invention consisting in moving with a simple movement relative to the body to be painted at least one electrostatic bowl rotating at high speed, several solutions are possible to ensure this relative movement.

In the first exemplary embodiment, corresponding to FIGS. 1 to 3, the essential mechanism is shown in detail in FIGS. 2 and 3 We see that this mechanism includes a fixed support 2 firmly anchored in the ground 3 and itself supporting a cradle 4 movable in rotation relative to a horizontal axis 5 which is the main axis of the installation.

This cradle 4 essentially consists of a cage 5 terminated at the rear end by a shaft 6 rotating in a bearing 7 secured to the support 2, and at the front by a crown 8 resting on rollers 9 which rotate themselves around fixed axes carried by the support 2. The entire cradle 4 can be driven in a slow rotational movement over at least 3/4 of a turn using a servo-motor 10, preferably hydraulic , with an angular tracking device 11 constituted by a plate or a drum integral with the end of the shaft 6 and moving in front of one or more sensors making it possible to determine at any time the angular position of the cradle 4.

In this cradle is mounted a cantilever beam 12, preferably a box beam with an evolving profile, the embedding end of which is articulated around an axis 13, perpendicular to the axis 5 and swiveling in the cradle 4 in the immediate vicinity of the crown 8. The beam 12 is thus capable of placing its own axis coinciding with the preceding horizontal 5, or of deviating angularly from this axis. The corresponding movement is caused by another servo-motor 14, also preferably hydraulic, which is articulated er 15 on the cage in which on a articulation 16 carried by the end of the beam 12 located inside the cage 4. This servo-motor 14 is naturally capable of angularly displacing the beam 12 to move it away from the axis 5 or bring it back in this axis , for all the angular positions of the cradle 4, this beam can in particular be to the right or to the left or above or even below this axis for four preferred orientations of the cradle 4

At the free end 17 of the beam 12 is fixed a perpendicular cross member 18 whose general direction is parallel to the hinge axis 13. Each end of this cross member 18 comprises a hinge 19 on which an arm 20 is articulated, the two articulation axes 19 carried by the crosspiece 18 being also parallel so that the two arms 20 are constantly in the same plane.

Each of the arms 20 carries at its free end a high-speed rotary electrostatic sprayer 21 of known type which is mounted at 22 on the arm 20 in an angularly adjustable manner in both directions. In addition, each riser sprayer 21 has its usual means for adjusting the jet as well as naturally supplying paint, energy and electrostatic potential.

The angular movement of each arm 20-with the cross-member 18 is obtained separately by means of a cylinder or a particular servo-motor 23 located in the cage 5 and acting at a distance by means of a rod or rod 24, preferably passing inside the beam 12 and articulated at 25 on the rod of the corresponding servo-motor 23 and at 26 at the end of a lever arm 27 substantially perpendicular to the corresponding arm 20. This remote action in particular makes it possible to lighten the free end of the beam to reduce the tilting torque of the support 2 and to avoid any hydraulic actuator (susceptible to oil leaks) in the enclosure to be painted.

There is also preferably provided another link 28 articulated at 29 on the crown 8 and at 30 on an extension. lower 31 of the cross member 18, the latter being further mounted as a whole movable in rotation about its own axis, so that the assembly of the beam 12 and the connecting rod 28 constitute an articulated parallelogram in order to maintain the plane above of the two arms 20 constantly parallel to the axis 5. This avoids variations in the incidence of the spray angle relative to the various walls. We see in particular in phantom in FIG. 3 the extreme position that the beam, the arms and all of the sprayers can take when the cradle assembly is oriented towards the right interior wall of the vehicle.

At the rear of the cradle 4, between the cage 5 and the bearing 7, there is provided a drum 32 on which is wound all of the flexible cables and pipes for supplying the various active members carried by the cradle 4 during the rotation of it.

It follows from the above description, that the two sprayers 21 can be moved so as to vary their spacing, in a symmetrical or asymmetrical manner relative to the beam 12 by separate action on the jacks 23, as well as their distance to axis 5 by causing the angulation of the beam 12 to act relative to this axis 5 by means of the servo-motor 14, and finally so as to vary the orientation of the entire assembly of the cradle by rotation around this axis 5 to orient the jets successively in the direction of the four main walls of the vehicle.

In addition to these three main movements, there is provided according to the invention a fourth movement which consists in moving the vehicle along its own axis. For this, each vehicle body 33 is arranged on a handling support frame 34 which accompanies it over a large part of the manufacturing process, and this frame 34 can be moved to a working handling 35 consisting of a slow speed conveyor and adjustable with incremental chassis position information device allowing to know at any time the position of the vehicle and to reposition the sprayers or change the painting parameters in progress based on this information. It is indeed necessary as will be seen later that this chassis performs two forward movements and two successive return movements to paint the four interior walls of the bodywork.

Naturally, in addition to this work handling conveyor which is an integral part of the painting assembly, the installation also comprises conventional serving conveyors intended to bring the bodies to paint and to evacuate the painted bodies, these conveyors having to be be adapted to the fact that the supply and the evacuation must be on the same side, since the bodywork cannot cross the obstacle constituted by the support 2. In particular, a transverse supply conveyor can be provided, shown diagrammatically the arrow 36 in fig. 1 and an in-line evacuation conveyor 37, with a common section of return 38, but it is also naturally possible to provide an in-line supply and a transverse evacuation.

In addition, these handling devices 35, 36, 37 and 38 and the essential mechanism 1 which has just been described, the entire installation shown in FIG. 1 includes a paint booth 39, which therefore has only one opening on the side of the conveyor 38 and which is adjacent to a control room 40, which comprises a programmable controller 41, a console 42 for computerized recording of the various parameters paint and positioning to introduce the various types of bodywork that must be treated on the installation, and for each type the various sprayer position parameters and paint parameters such as flow rate and spray width. A video screen 43 makes it possible to read in automatic mode the operating diagram of the machine and in recording or reading mode to view the tables, that is to say the succession of clear orders over time or as a function of the position of the vehicles on work handling 35 for each of the pre-registered types. Finally, a console 44 makes it possible to clearly select in the form of a decision tree, taking into account the very large number of possible variants, the type of bodywork and the desired color to automatically cause all movement and adjustment of the paint parameters necessary for the execution of the paint, including purging and cleaning of the sprayers in case of color change. The references 45 and 46 respectively designate the pneumatic cabinet and the hydraulic group for supplying the installation.

This automatic assembly therefore produces the displacement of the chassis 34 and of the vehicle 33 carried by the latter, the rear opening of which naturally occurs first for the engagement of the beam 12, and ensures, in a first recoil pass, the painting of the right interior face, for example, by constantly modifying if necessary during displacement the spacing of the sprayers 21, as well as their distance to the axis 5 by angulation of the beam and so as for example to bypass the passage of the wheels. After the front interior wall of the vehicle has come to the vicinity of the sprayers 21, the device automatically reverses the direction of movement to move the vehicle forward at the same time as the cradle 4 rotates a quarter of a turn to orient the sprayers towards the roof, all the other settings being revised accordingly and permanently modified if necessary during the second advance stroke of the vehicle. We also paint the left side face after a second quarter turn of the cradle 4 and with the help of a new recoil movement, then paint the floor in a final movement of advance, after which the chassis 34 is evacuated.

For small vehicle bodies, in particular for conventional light cars, a single rotating bowl projecting forward, placed along the axis of the vehicle and moving in a relative movement along this axis may be sufficient for painting all interior surfaces. In this these. it is possible to suppress not only the movements of separation but also all the movements of rotation and inclination of the beam, that is to say to be satisfied with a fixed beam by moving the bodywork with a movement of va- back and forth as before.

However, to better adapt to the high productivity that these light vehicles generally require, it is preferable to use the installation according to the second embodiment, corresponding to FIGS. 4 to 6.

In this example, the bodies 51 are painted on parade while being handled by a conveyor on the ground or overhead, not shown, at a constant running speed. However, it is necessary to provide between two successive bodies a sufficient space, of the order of 1 m 50 on average, but which may vary depending on the size of the body.

The paint bowl 52, of the same type as the previous bowls 21 but this time unique, projects the paint forward with a large angle of diffusion and it is arranged horizontally along the axis of the vehicle by being carried by a beam angled 53 which successively comprises: - A lower part 54, parallel to the axis of the chain and located on the side thereof as shown in FIG. 6; - Towards the rear end of this part 54, leaves in a substantially perpendicular direction, a part 55, which is approximately vertical in the position of use; - To the latter follows a part 56, substantially horizontal and transverse to the chain in the position of use to pass over the hood of the vehicle according to the interval; - This part 56 follows a straight rectilinear part 57 constituting the essential part of the beam, at the front end of which a doubly bent part 58 supports the bowl 52.

Naturally, all these parts 54 to 58, rigidly integral with each other, contain the electrical and paint supplies.

Furthermore, the base portion 54 is capable of a double movement, namely a sliding in the direction of its axis by an amount substantially equal to the interval between two vehicles, and on the other hand a rotational movement around of this axis to move the assembly from the indicated position, where the bowl 52 is in the axis of the vehicle, to a lateral position shown in dashed lines on the right side of FIG. 6 and where no part of the beam 53 or of the bowl 52 constitutes an obstacle for the passage of the bodies 51.

As a variant, the tilting movement around 54 could be replaced by a horizontal translational movement perpendicular to the chain.

If one starts for example from the position where the bowl is at 52a in the cleared and retracted position, when a detector 59 detects the arrival of the vehicle, its information triggers the tilting movement which causes the sprayer to engage between the two successive vehicles, this sprayer therefore passing from position 52a to position 52, in the axis of the vehicle. The end of travel of this movement triggers a longitudinal translational movement in the direction of arrow 60 of part 54 which moves the bowl from position 52 to position 52c, position in which the sprayer is still in the axis of the vehicle but inside it and at the desired distance near the front wall. This stroke 60 is limited by a translation stop not shown which is adjusted so that, even if the chain stops at the start of the first movement, the sprayer does not collide with the dashboard of the vehicle to the end of the second movement.

A detector 61 detects the arrival of the vehicle in a position such that the desired distance between the spray bowl 52c and the front interior wall of the vehicle is reached. This detector 61 then triggers the spraying operation, which continues as a function of the incremental chain advance information. However, in the event of the chain stopping, spraying is automatically interrupted to resume on restarting.

The relative position of the sprayer with respect to the vehicle is known at all times thanks to an incremental chain advance detection, which makes it possible to vary the paint parameters (flow rate, diameter of the spray) in function tion of the relative position of the sprayer with respect to the vehicle.

A detector not shown triggers the lateral tilting movement which moves the spray bowl from position 52c to position 52d in the figures, this position and this movement being such that there is no risk of encountering the parts of the body of the vehicle, as well as its tailgate 62. The end of travel of this last movement then triggers the longitudinal translation movement in the direction opposite to the arrow 60 which replaces the bowl at 52a awaiting the signal from the detector 59 to start again a new cycle for the next vehicle.

Naturally, the various vehicle position detectors which have just been described could be replaced by an equivalent device, for example by counting increments from a single detector.

Each movement, executed in all or nothing, must be completed before the completion of a determined maximum period, failing which additional safety devices trigger the emergency stop in order to avoid any collision. In addition, it is naturally possible to provide a device for purging the sprayer which comes into action in the event of a change in color.

Thanks to the great distance which reigns between the spraying end of the bowl 52 and the various longitudinal and transverse walls of the vehicle, the positioning and marking, both longitudinal and transverse of the bodywork does not need to be carried out with extreme precision, since wide tolerances in absolute value correspond to small relative variations of this distance. This is what makes it possible to use all-or-nothing commands without requiring precise control. The whole thus combines great simplicity with great productivity, always with the quality and high yield linked to the process itself.

Claims (7)

1. A method of painting the interiors of automobile bodies, or similar enclosures, characterized in that at least one electrostatic spraying head with centrifugal atomization (21; 52) is used which is moved with a simple relative movement with respect to the body (33; 51) and inside it, and the body is joined to ground in such a way that the electric field is confined inside this body (cage phenomenon of Faraday operating in the opposite direction to the usual direction). 2. Automatic installation for painting vehicle body interiors comprising a large rear opening, in particular for industrial vehicles, by implementing the method according to claim 1, characterized in that it comprises in combination a mechanism (1 ) carrying two electrostatic paint sprayers (21) and arranged to move each of them in three movements so as to modify their spacing, their distance from the axis (5) and their general orientation relative to the axis respectively, with in addition a work handling means (35) ensuring a fourth movement which consists of a controlled movement of the bodywork in the direction of the axis on the outward and return path. 3. Installation according to claim 2, characterized in that it comprises in combination: a cradle (4) movable in rotation about a horizontal main axis (5) in a fixed support (2), with a servo-motor (10) for orientation; a cantilevered longitudinal beam (12) articulated on the cradle (4) around an axis (13) transverse to the main axis (5), with a servo-motor (14) for tilting control the axis of the beam relative to the main axis, said beam comprising at its free end a crosspiece (18) parallel to the transverse axis (13); two arms (20) articulated on the crosspiece (18) around axes (19) parallel so that the arms (20) are substantially in the same plane, with a servo motor (23) for each of the arms (20) so as to modify the position of this arm in this plane, each of the arms carrying at its free end an electrostatic paint sprayer (21) by means of an orientation adjustment device (22); finally, a work handling device (35) moving the bodywork (33), and possibly the chassis (34) which supports it, parallel to the main axis (5) of a movement at controlled speed and according to several trips and returns. 4. Installation according to claim 3, characterized in that said crosspiece (18) is rotatably mounted around its own axis and associated with an articulated parallelogram (12, 28) for maintaining the common plane of the two arms (20) constantly parallel to the main axis (5). 5. Installation according to one of claims 2 to 4, characterized in that the assembly is grouped in a paint booth (39) having a single opening, opposite the support (2) of the beam, and through which is made l entry and exit of the bodywork by means of suitable transport conveyors (36, 37, 38), and that it furthermore comprises electrical, hydraulic, pneumatic and computer control means for ensuring the manual or automatic operation of the assembly and manual or automatic adaptation of the various parameters to the various types, dimensions and color of the bodies to be painted. 6. Automatic installation for painting the interiors of vehicle bodies having a large rear opening, in particular of light vehicles, by implementing the method according to claim 1, and operating on bodies transported in a continuous scrolling movement by a conveyor,
characterized in that a single sprayer (52) is mounted at the end of a beam (53) of bypassed shape to avoid obstacles, and remains in a fixed position inside and in the axis of the body during the painting operation, this beam comprising means for ensuring its transverse movement of clearance, then its axial movement in the direction opposite to the direction of movement of the chain, its movement of re-engagement in the axis of the line of carros series then its longitudinal advance movement to the initial position in the following bodywork, a suitable space being provided between two successive bodies on the chain in order to allow these movements. 7. Installation according to claim 6, characterized in that the lateral release movement and re-engagement of the beam (53) and the bowl (52) which it carries is a tilting movement around the longitudinal axis (54 ) along which the translation takes place, simple position detectors or an equivalent device ensuring the succession of the four displacements linked to these two movements in synchronism with the advance of the bodies.

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