FR2679572A1 - ELECTROLYTIC INSTALLATION, IN PARTICULAR FOR PAINTING AN AUTOMOTIVE VEHICLE BODY BY CATAPHORESIS. - Google Patents

Abstract

The present invention relates to an electrolytic installation, in particular for painting a motor vehicle body by cataphoresis. This installation comprises a sled (2) on which is transported a vehicle body, at least one hanger (1) to which the sled (2) can be suspended in an articulated manner, said sled (2) being connected to a current source by the establishment of an electrical contact between two contact elements (7, 9) connected to the sled (2) and to the hanger (1), at least one of the elements (7) comprising an elastic means for the permanent return said elements (7, 9) one against the other, and the two aforementioned elements being secured in rotation during the pivoting of the sled (2). This invention applies in particular to installations for painting motor vehicle bodies by cataphoresis.

Description

The present invention relates to an electrolytic installation in particular

to paint a box of

  motor vehicle by cataphoresis.

  The known processes for obtaining an electrophoresis (electroplating) coating on a motor vehicle body consist in immersing the body of a vehicle in a tank containing a bath of an electrically conductive paint, having introduced in this same bath, two electrodes (respectively anode and cathode) of a DC generator, the cathode being connected to the body of the vehicle in the case where the paint used is

cationic type.

  The paint coating is obtained by moving the paint particles towards the vehicle body, under the effect of the electric field produced by said generator. This process has a number of known advantages, in particular because, on the one hand, it lends itself to automation, on the other hand that the paint can access the interior parts of the body and is constantly renewed by an equivalent amount as it is applied. The implementation of this method is carried out in a manner known per se, by means of an installation comprising a conveyor driving one or more hangers moving on rails, and intended to transport a sled supporting the vehicle body towards the tank containing the paint bath The deposit of a layer of paint on a vehicle by this method requires the body of said vehicle to be connected to the negative pole of the current generator and generally to ground; this is done in order to avoid the undesirable traces left on the bodywork, while carrying the sled to the mass by means of a mechanism fixed to the base of the hoop and comprising two contact elements connected respectively to the sled

and one or more hangers.

  Now it turns out on the one hand, that the path of the hangers on the rails is not continuously rectilinear and has curves corresponding to the descents and ascents of the boxes in the paint bath, on the other hand, that the aforementioned mechanism will be immersed during the passage in the bath From these two considerations it follows that the aforementioned contact must meet certain conditions It will be necessary that the two aforementioned contact elements are clean and fixed relative to each other, and particularly during descents and lifts of vehicles to avoid the occurrence of arcing that can lead to unwanted welding It will be desirable that a minimum of mobile links between the parts are made but that remains a game between these elements to allow the painting to be evacuated so

  to prevent the risk of blockage of the flow of current.

  Several systems have been made to date to meet these requirements It has indeed been proposed to establish a direct contact between each hanger and the sledge Or this type of contact by four-point support obviously causes poor contact between l One of the hangers and the sled, and consequently leads to the formation of electric arcs In addition, the two opposite metal faces being covered with paint, an accumulation of uncured cataphoresis is formed in the contact zone producing a gap also

  likely to generate electric arcs.

  It has also been proposed to establish contact by means of a magnet supported by the hanger and connected to the cable for routing the mass, and a contact plate secured to the sledge Or this solution requires two stations automatic cleaning, one for the magnet, the other for the plate, which must have a very clean surface as far as the magnet is concerned, and a ground surface also very clean with regard to the plate. It is observed that the attractive force of the magnet decreases during

time.

  The present invention aims to solve these problems and proposes an electrolytic installation, in particular for painting a motor vehicle body by cataphoresis, easy design, and allowing a transmission of current between the (s) hoop (s) and sled particularly reliable, by avoiding the use of the cleaning devices of the electrical contact elements conventionally required in such

facilities.

  To this end, the subject of the present invention is an electrolytic installation, in particular for painting a motor vehicle body by cataphoresis, of the type comprising a sled on which is transported a motor vehicle body in electrical contact with said sled, at least one hoop to which said sled can be suspended in an articulated manner, said hoop being moved by a conveyor to transport said sled to a station at which it penetrates at a certain inclination in a cataphoresis bath by pivoting around the hoop, said sled being electrically connected to one of the blades of a current source by the establishment of an electrical contact between two electrical contact elements connected respectively to the sled and the hoop, in the loaded sled position on the hangers, one of the two aforementioned elements retracting to allow the loading of the sled on the hoop, this installation characterized in that at least one of the two abovementioned contact elements comprises an elastic means permanently applying the two contact elements one against the other in the loaded position of the sled by pushing back at least one said elements during loading, and in that the sled and the hanger cooperate with a securing means of the two aforementioned contact elements during the pivoting of the sled relative to the hanger so as to maintain a fixed contact between these two elements during the descent of the body into the bath, at least one of the two contact elements being returned to the initial service position, opposite the other contact element so that the two aforementioned elements can make contact

  electric when loading later.

  According to a particular embodiment of the invention, one of the abovementioned contact elements is rotatably mounted with respect to the axis about which the sled rotates relative to the hoop and the aforementioned securing means is a means for securing in rotation

two elements mentioned above.

  The contact element supported by the hanger is secured to a sleeve rotatably mounted about the pivot axis of the sledge relative to the hanger, said sleeve having two fingers capable of coming into contact with a portion of the sled to secure in rotation the two contact elements Advantageously, the aforementioned part of said sled is the element of

  electrical contact with the luge itself.

  According to another characteristic of the invention, at least one of the abovementioned contact elements comprises at least one strip made in one

elastic and conductive material.

  According to an alternative embodiment, the two aforementioned contact elements are constituted for the first of several parts, and for the second of a part, said parts each comprising at least one edge, the two contact elements being applied against each other. the other via a spring, the respective edges of the parts of the first and second contact element being rubbed off against each other when loading the sled on the hanger Advantageously, the edges of the two elements mentioned above have different inclinations. It will be pointed out that the parts of the first contact element comprise a chamfered part cooperating with a corresponding chamfered part of the other part of the second contact element, favoring the retraction of one of the contact elements during the first contact element.

  set up the sledge on the hoop.

  According to another characteristic of the invention, one of the abovementioned contact elements is connected to the current source via a flexible element allowing current transmission.

  when rotating the sledge relative to the hoop.

  Advantageously this flexible element is a braid or a cable. According to another characteristic of the invention, the return spring of at least one of the contact elements after each operation is secured by one of its ends to the upper part of the hoop and by its other end to an intermediate piece. support member on which is fixed the contact element supported by the hoop and recalls one of the contact elements in the engagement position with the other contact element prior to loading a sled. According to another characteristic, said installation comprises means for checking the presence of the spring. These means comprise a presence detector of the hoop and a spring presence sensor, and means for checking the synchronization of the signals emitted by said sensors, set in action at the beginning

the return circuit of the hangers.

  According to another characteristic of the invention, the installation further comprises a means for controlling

  the continuity of the flow of current between two hangers.

  This means comprises an additional rail on which engages one of the rear hangers when one of the front hangers is in guided contact with a front rail connected to said current source, a device for subjecting the additional rail to a DC voltage. and a device for checking the passage of the current in the

circuit thus created.

  But other features and benefits of

  the invention will appear better in the description

  which follows and refers to the accompanying drawings given by way of example and in which Figure 1 is a partial front view in section, illustrating an electrolytic installation according to an embodiment of the invention, for the implementation

  in painting of a motor vehicle body.

  Figure 2 is a sectional view along II-II of the previous figure, illustrating the hinge without

sledding.

  FIG. 3 is a view similar to FIG. 1, but illustrating a second embodiment of the means of

  transmission of electric current between hoop and sledge.

  FIG. 4 is a sectional view along line IV-IV of FIG. 3, similar to FIG. 2, but illustrating a second embodiment of the device of FIG.

  current transmission between hanger and sled.

  FIGS. 5 and 6 are side views of the electrical contact elements according to the embodiment illustrated in FIGS. 3 and 4, whereas FIGS.

  and 8 are respectively front views.

  FIG. 9 is a schematic partial view of a hoop of an electrolytic installation equipped with a device for checking the presence of the return spring of the contact element in the initial position, and FIG. 10 is a schematic representation illustrating two hangers moved along the guide rails, and a control system of the

continuity of current flow.

  In FIGS. 1 and 2, part of the electrolytic installation I of the invention is shown for the transport of a vehicle body in a tank (not shown in this figure) in order to paint said box by This installation I comprises for each operation on the one hand, four hangers 1 (only one is shown in this figure) moving by their upper ends on guide rails when centralized by a conveyor (not shown), and a sled 2 suspended from the aforementioned hangers (the movement of the

  perpendicular to the plane of the figure).

  Each aforementioned hanger 1 comprises a vertical element 10 and a horizontal element 11 forming a hinge axis on which axis 11 said sled 2 is pivotally mounted to the upper part of the hanger 10 is fixed a support member 12 to which is connected perpendicularly by means of a screw assembly 120 and nut 121, one of the ends 30 of a braid 3 whose other end 31 is secured, also by means of a screw system 43 and nut 42, to a square 4 connecting said braid 3 to an intermediate support part 5 of a contact element 7, said intermediate part 5 being integral with a sleeve 8 rotatably mounted on another sleeve 111 secured to the shaft portion 11 of the hanger 1 Au instead of a braid, it is advantageous to use a flexible cable with metal lugs As for parts 5 and 8, they must be made of insulating material The aforementioned contact element 7, supported by the hanger 1, is According to this particular embodiment, four spring slats 70 are fastened to a metal part 5b by means of bolts 79 or screws placed from the outside, the part 5b being itself fixed on the part 5 by means of 5 a screw, the upper part of the intermediate part 5 being further connected by means of a second bracket 40 to a return spring 41 whose function will be explained later and whose end 411 is engaged in an orifice provided in said bracket 40 while the other end 412 is suspended from the support member 12 attached to the upper part of the hanger 1 The spring can also

  be held by pins on parts 5 and 12.

  The sleeve 111 fixed on and surrounding the part of the hinge 1 forming hinge pin 11 is formed of three parts of different diameters illa, lllb, 11 ic; the sleeve 8 is pivotally mounted around the central portion 11b having the smallest diameter and has on its side facing the sled 2 two fingers 80 incorporated and

  disposed on either side of said sleeve 111.

  Thus, in the use position of the assembly, the intermediate support part 5, the electrical contact element 7 and the rotary sleeve 8 and its incorporated fingers 80 are integral in rotation around the sleeve

  fixed 111 and the axis 11 of the hanger 1.

  The shaft portion 11 of the hanger 1 is intended, as already mentioned, to support the

  sled 2 on which will be arranged the vehicle body.

  This sled 2 consists of a pallet that can pivot about the axes of the hanger 1, and which has on one of its sides two electric contact plates 9 intended to cooperate with the aforementioned slats 70 of two hangers 1 opposite this rating

the sledge 2.

  According to a second embodiment of the invention, illustrated in Figures 3,4,5, the electrical contact element 7 supported by the hanger 1 (see also Figures 5, 6, 7 and 8) consists of four parts 71 72,73,74 of substantially trapezoidal section in contact with an intermediate support piece by their longer side, and mounted against a spring (not shown) applying them to the other contact element 94 These four parts comprise, on the opposite side to the intermediate support, projecting elements forming edges 75 parallel to each other, inclined with respect to the base of said parts. The contact element (FIG. 6 and FIG. to be supported by the sled 2 is for its part, a piece 94 of substantially parallelepipedal shape attached to the sled 2 and also having on its face opposite the sled 2 elements in

projection forming ridges 91.

  In addition, the upper part of the part forming the first contact element 7 above is chamfered (a) to cooperate with another chamfer (b) provided at the lower part of the other contact element 94 in the manner to be described. more forward

in the description.

  It will indeed be proceeded through what

  follows a description of the operation of

  the installation I first in its first embodiment. The sled 2, on which is arranged the vehicle body, is transported initially to above the parts forming axis 11 of the four hangers 1; then a table (not shown) transporting said sled 2, lowers the sled on the hangers with the effect of suspending said sled to said hoop During this lowering of the sled 2, the electrical contact plate 9 of the sled 2 compresses the resilient strips 7 thus establishing electrical contact with the mass conveyed from a cable running along the upper part of the hangers 1 and passing respectively through the screws and nuts 120, 121, 43, 42, the braid 3, the square 4 the screws 5a and 5b At this stage, the hangers 1 are moved by a conveyor along guide rails 50 (see figure) which bend at the level of the tank containing the paint bath, to allow the introduction of the body in said bath along a slope of 450 gold, when the first two hangers 1 move along the curved portion 51 of the guide rails 50, the sled 2 is pivoted about the axes 11 formed by the pa lower parts of hangers 1; this rotation of the electric contact plate 9 of the sled 2 causes the rotation of the two fingers 80 and consequently of the sleeve 8 to which they are incorporated and which is integral with the contact strips 7, which lamellae

  are in this way coupled with the movement of sled 2.

  This results in the establishment of a fixed electrical contact between the aforementioned lamellae 70 and the contact plate 90, which advantageously avoids the electric arcs produced when the parts slide relative to each other, which is d as much more necessary as the mechanism is immersed in painting; the realization of an elastic electrical contact also contributing to the suppression of electric arcs, and to maintain over time a good quality electrical contact regardless of variations in the size of the sleds for example, dimensional dispersions of equipment in general, and the wear of the mechanism over time The pickling of the electrical contact elements is carried out on the descent 11 of the sled 2, the paint being removed by friction of the slats 70 against the plate 90 As for the unloading of the sled 2 of the hangers 1, it is obtained by raising the sled 2 by means of the lifting table, which produces the decompression of the slats from the plate 90, the sleeve assembly 8, intermediate part 5, slats 70, braid 3, being recalled in the vertical position by the spring 41 in the perspective of a new load It should be noted that in this embodiment stripping is performed a utomatically, only on the slats 70 during loading, the plate 9 secured to the sled 2 requiring stripping by shot blasting The slats 70 are preferably made of treated stainless steel to have a low elasticity and therefore a stripping

easy automatic.

  The means of transmitting the mass to the sled 2 according to the second embodiment operates in the same manner as previously described The loading of the sled 2 on the hoop 1 produces the engagement of the two chamfers (a) (b) respectively provided at the upper portions of the contact pieces 71, 72, 73 and 74 and at the bottom of the other piece 94, resulting in the displacement of the aforesaid pieces 71, 72, 73, 74 opposite the aforesaid spring, which makes it possible to realize a pressure of the pieces 71,72,73,74 against the

94.

  It should be noted that in the latter case, the contact parts 71, 72, 73, 74 are made of tungsten carbide for scraping the cataphoresis cooked and the significant intensity of the current

  electroplating (750 A max).

  The control of the continuous flow of current between the hoop and the sled is carried out as follows. When the hoop 1 reaches the curvature of the rails allowing the sled to penetrate into the tank, it engages on a grounding rail 52 then that the rear hangers 13 engage on a control rail 53 whose voltage is measured (FIG. 10). This control is carried out via a stabilized power supply U, for example 24 VDC, and a relay. voltage R at threshold. The state of the relay R is scanned for the duration of the control by a PLC A Any fault detected triggers the storage M of the image of the number of the rear hijacker 13; this number is then visualized (E) in the control room where it triggers an alarm that warns

a maintenance team.

  Before the cataphoresis operation and prior to the loading of the sled 2 on the hanger 1, the presence of the spring 41, which is essential for the sling to be satisfactorily completed, is checked. This check is carried out by the intermediate of two pallet sensors 16,15 in the beginning of the return loop hangers 1, which hangers are equipped with systems of grounding and can move in vertical position The pivoting of the vanes 15,16 at the passage of the spring 41 and the upper part of the hoop respectively generates a signal, any desynchronization between the state of the two sensors 16,15 triggering an alarm stored in the control room to prevent a maintenance team. It will be noted also on the one hand that the parts 8, 111, 12 will advantageously be made of a plastic material in order to prevent the hoop from being grounded, on the other hand that the contact elements will preferably be disposed of. only one side of the sleds to facilitate placement, and that the conductive surfaces in contact with the bath will be protected by

a cataphoretic deposit cooked.

  An electrolytic installation has therefore been made possible thanks to the invention, in particular for painting a motor vehicle body by cataphoresis, eliminating the risk of arcing between the respective contact elements of the hoop and the sled, thanks to a contact permanent throughout the duration of the electroplating due to the elastic connection, and the rotational connection, not requiring a particular surface quality as is the case with the magnet, while compensating for dimensional variations sleds, and not requiring the establishment of chemical stripping stations requiring maintenance, use and treatment of products

Mandatory and expensive chemicals.

  Of course, the invention is in no way limited to the described and illustrated embodiments which

  have been given only as examples.

  On the contrary, the invention comprises all the technical equivalents of the means described and their combinations if they are carried out according to its spirit. Furthermore, it does not apply solely to motor vehicle bodies, but may be used for the treatment of motor vehicles. a basket of spare parts by

example.

Claims (11)

  Electrolytic installation, in particular for painting a motor vehicle body by cataphoresis, of the type comprising a sled on which is transported a body of an automobile vehicle in electrical contact with said sledge, at least one hangman to which said sled can be suspended in an articulated manner, said hanger being moved by a conveyor to convey said sled to a station at which it penetrates at a certain inclination in a cataphoresis bath by pivoting around the hanger, said sled being connected to one of the p 8 of a current source by establishing an electrical contact between two electrical contact elements respectively connected to the sled and supported by the hanger in the loaded sled position on the hanger, one of the two aforementioned elements retracting to allow loading the sled on the hoop, characterized in that at least one of the two contact elements stitches (7, 9) comprises an elastic means permanently applying the two contact elements (7, 9) one against the other in the loaded position of the sledge (2) by pushing back at least one of said elements contact (7,9) during loading, and in that the sled (2) and the catch (1) cooperate with a means for securing the two abovementioned contact elements (7, 9) during the pivoting of the sled ( 2) relative to the hanger (1) so as to maintain a fixed contact between these two elements during the descent of the body in the bath, at least one of the two contact elements (7,9) being returned to the initial position service vis-à-vis with the other   contact element after each operation.   2 Installation according to claim 1, characterized in that one of the aforementioned contact elements (7,9) is rotatably mounted relative to the axis (11) about which pivots the sled (2) relative to the hoop (1 ) and in that the aforementioned securing means is a means for securing in rotation the two aforementioned elements. 3 Installation according to claim 1, characterized in that the contact element (7) supported by the hanger (1) is integral with a sleeve (8) rotatably mounted about the pivot axis (11) of the sled (2) with respect to the hanger (1), said sleeve (8) having two fingers (80) capable of coming into contact with a portion of the sled (2) to rotate the two contact elements (7, 9) in rotation; when pivoting sledding.   4 Installation according to claim 3, characterized in that the aforementioned part of said sled is the electrical contact element (9) integral with the toboggan (2) himself.   Installation according to any one of   preceding claims, characterized in that one   at least one of the abovementioned contact elements (7, 9) comprises at least one lamella (70) made of a material elastic and conductive.   6 Installation according to any of the   Claims 1 to 4, characterized in that the two   aforementioned contact elements (7, 9) are constituted for the first, of several pieces (71, 72, 73, 74) and for the second of a piece (94), said pieces each comprising at least one edge (75, 91), the two contact elements (7, 9) being biased against each other by means of a spring, and the respective edges (75, 91) of the parts of the first contact element (7). and the part of the second contact element (9) being etched by friction against each other during   loading of the sled (2) on the hoop (1).   7 Installation according to claim 6, characterized in that the ridges (75,91) of the two aforementioned contact elements (7,9) have different inclinations.   8 Installation according to claim 6 or 7, characterized in that the parts (71,72,73,74) of the first contact element (7) comprise a chamfered portion (a) cooperating with a corresponding chamfered portion (b) of the another piece (90) constituting the second contact element (90), favoring the retraction of one of the contact elements (7, 9) during the implementation   toboggan square (2) on the hoop (1).   9 Installation according to any of the   preceding claims, characterized in that one   said contact elements (7, 9) are connected to the current source by means of a flexible element (3) allowing the transfer of the current during the   rotation of the sledge (2) relative to the hoop (1).   Installation according to claim 9, characterized in that the aforementioned flexible element is a braid (3) or cable.   11 Installation according to any of the   preceding claims, characterized in that   spring (41) of return of at least one of the contact elements after each operation is secured by one of its ends (412) of the upper part of the hoop (1), and by its other end (411), d an intermediate support part (5) on which is fixed   the contact element (7) supported by the hanger (1).   12 Installation according to claim 11, characterized in that it comprises means for   checking the presence of the spring (41).   13 Installation according to claim 12, characterized in that these means comprise a presence sensor (16) of the hoop (1) and a sensor (15) for the presence of the spring (41), and means for checking the synchronization of the signals transmitted by the two sensors (15,16), activated at the beginning of the return of the hangard (1).   14 Installation according to any of the   preceding claims, characterized in that   further comprises means for controlling the continuity   the passage of the current between two hangers (1).   Installation according to claim 14, characterized in that this means comprises an additional rail (53) on which engages one of the hangers (13) rear, when one of the front hangers (14) is in guided contact with a rail (52) forward connected to the power source, a device for subjecting the additional rail (53) to a DC voltage, and a device for checking the passage of current in the circuit thus created.