FR2628657A1 - PILOTED PROJECTION INSTALLATION OF PAINT OR THE LIKE, WITH FREQUENT COLOR CHANGE, IN PARTICULAR FOR THE AUTOMOTIVE INDUSTRY - Google Patents

Abstract

The installation comprises a coating product projector 14 supplied, through a distribution circuit 12, by a combination of 5 primary units G to K for color change, connected by controlled valves 1g-6g, 1h-6h, 1i -6i, 1j-6j, 1k-6k to groups A to E of paint supply loops 1a-6a, 1b-6b, 1c-6c, 1d-6d, 1e-6e, each traversed by a coating material particular, and a secondary color change unit L, connected to the outputs of the primary units G to K by intermediate pipes 11g to 11k. Thus, the only pipes where the coating products could stagnate and settle are these intermediate pipes. In the general case, these intermediate pipes are purged and rinsed after use. However, to reduce paint and solvent loss, purging and flushing of a line is inhibited if, according to the color change forecast, at the first occurrence of use of the line after use with a color determined, and within a set period of time, the same color will be used.

Description

"Controlled installation of projection of paint or the like, with

  frequent change of color, especially for the automotive industry "The invention relates to a controlled installation for projecting coating product comprising at least one powered projector, through a distribution circuit comprising coating material propulsion means, from a coating product change apparatus connected to a multiplicity of feed loops, each traversed by a particular coating product, by as many controlled valves, the apparatus being further selectively fed with

  rinse aid and pressurized drying air.

  The invention is more particularly applicable to the use of metal or solid lacquers or bases of multiple colors, with rapid and frequent color changes of the coating product, in particular

  for the coating of automobile bodies.

  Known paint spraying installations provided with a programmed autopilot color change system, comprising a plurality of different color paint circulation circuits which will hereinafter be referred to as "feed loops", in each of which a paint flows continuously over a relatively large path, means for supplying rinsing product, also in the form of a continuous circulation circuit, compressed air supply means and a set of controlled valves and control systems. driver forming what is generally called a "color change block" having at least one output connected to one or more projectors located in a paint spray booth. The objects to be painted pass through this cabin. This type of installation is more particularly found in the automotive industry where one of the most severe operating constraints is that two bodies that succeed one another in the cabin must not generally be painted the same color , which requires to be able to perform a whole cycle of color change for a short period of time not exceeding the time required to bring a new object into position in the cabin. In this type of installation, it is known in itself to use conventional equipment, in which a single color changer, for each sprayer, has its own

  inputs connected to power loops, and possesses in.

  in addition to two specific inputs connected to a solvent circulation circuit, and to a distribution circuit

pressurized air.

  The power loops are in fact long conduits each defining a closed circuit. Each loop, in which paint is constantly circulating, is in communication with a paint tank of one color

  given, located remotely in the factory.

  Controlled valves allow the admission into the collector of the color change apparatus and therefore the arrival in the sprayer of as many products

  different than there are power loops.

  Valves allow injection into the rinse solvent and blowing air distribution circuit and

drying.

  In a conventional paint application station

  on bodywork, 9 sprayers are generally used.

  This station therefore generally comprises at least 9 similar circuits as just described, only the power loops being common to all

sprayers.

  All this arrangement is well known, the control and sequencing of the openings and closures of the valves which are integrated in the color change block, are conventional and allow successively to paint and rinse the circuits, then to paint again with another color or another product without pollution from the

  new color by the old color.

  The output of the color change block is connected to the projector via a distribution circuit successively including a motor pump unit and a conduit. The pump unit consists of a pump of the rinsable gear type, which can be short-circuited during the color change sequence, the input of which is directly connected to the output of the color change block, and a motor drive, for example of the step-by-step type, the rotation speed of which is considered to be proportional to the quantity of paint withdrawn from the feed loop and discharged to the sprayer. Pressure sensors control the

  inlet and outlet pressures of the pump.

  These conventional systems have many disadvantages: they require in effect for each color change, a complete rinsing of the color change block, resulting in a significant loss of solvent.

and painting.

  The color change block or equipment, always placed near the pump, is connected by a pipe of several meters in length to the feed loops, which leaves without movement and thus without mixing the contents of the pipes which do not correspond. to the product sprayed at the time. However, some products such as bases or water products, consisting of suspensions, sediment as soon as they are no longer in motion for a duration exceeding a few tens of minutes. In order to correct this last point, it was proposed to put Y-connectors at the inlet of each of the controlled valves of the product change apparatus, so that each valve is connected to a branch of the Y, arrival on a second branch and finally a return of paint to the power loop connected to the last branch of the Y. But experience has shown that besides that it leads to an inextricable forest of pipes, the number of colors sometimes exceeding thirty, this also causes enormous difficulties in regulating the flow in the feed loop permanently disturbed by the opening or closing of the valves of the different sprayers. Finally, a major disadvantage of such systems lies in the fact that when one of the many valves ordered fails, it is necessary to be able to disassemble it to close all the manual valves sectioning the connection to the power loops

  and therefore to stop the operation of the sprayer.

  To palliate-. these drawbacks, the invention proposes a controlled installation for projecting coating product comprising at least one powered projector, through a distribution circuit comprising coating material propulsion means, from a product change equipment. coating connected to a multiplicity of feed loops, each traversed by a particular coating product, by as many valves controlled, the apparatus being further selectively fed with rinsing product and drying air, under pressure, characterized in that said apparatus is split into a plurality of coating product change units, here called primary units, arranged in parallel in close proximity to the multiplicity of feed loops and each having an output, and in that that a unit of change of coating product, here called secondary unit, has a plurality entries provided with controlled valves, each connected via an intermediate duct to the output of a respective primary unit, rinse-off conduit after

  use from this respective primary unit.

  By arranging the primary product change units in the immediate vicinity of the coating product feed loops, product stagnation between the feed loops and the controlled valves of the primary units is eliminated, stagnation being possible only in the intermediate channels, which are reduced in number, and can be cleaned by rinsing and blowing from the primary units of coating product change. In addition, damage to a controlled valve of a primary unit can be repaired by isolating the primary unit from the only power loops - to which this unit is connected, while the rest of the installation continues to operate with the colors who

  do not correspond to the isolated primary unit.

  In preferred arrangement, the installation is computer-controlled where a coating product change sequence prediction is stored and this computer is programmed to inhibit rinsing of an intermediate pipe after use with a particular coating product if this pipe must be reused at the first occurrence by the same product of

  coating, within a specified period of time.

  This reduces the frequency of rinsing the intermediate pipes, and the amounts of lost coating product and rinsing product consumed, by removing rinsing whenever the coating product remained in the intermediate pipe would be reusable. Statistical studies on the frequencies of use of the various coating products, which will be discussed in more detail below, allow, by affecting the feed loops corresponding to the various primary units to the various coating products according to their frequency of operation. use, maximize the probability of occurrence of successive use of the same product

  in the same intermediate pipe.

  Preferably, the propulsion means comprises, at the outlet of the secondary unit for changing the coating product, a pumped. driven by a variable speed motor controlled by a servo device sensitive to the difference between a signal emitted by a flow sensor

  in series with said pump, and a set signal.

  Since the precise control of the flow rate of spray coating material is a paramount condition of the efficiency and repeatability of the spray coating, it will be understood that the use of a flow controlled pump permits such precise adjustment, regardless of the pressure under which the coating product is supplied to the distribution circuit; However, because of the multiplicity of power loops, flow rate variations provided by these loops, and pressure losses resulting from the length of the pipes o circulate the coating products, the flow control or 1o propellant sprayer by an overpressure

  upstream is causing considerable difficulties.

  Preferably, a controlled valve is arranged in parallel with the pump. This valve will be open during

cleaning cycles.

  The features of the invention, with their

  benefits will become clearer from the description that

  will follow by way of example, with reference to the accompanying drawings in which: - Figure 1 shows schematically an installation according to the present invention; FIG. 2 schematically represents the means

  propulsion coating product to the projector.

  According to the embodiment chosen and shown in FIG. 1, a coating product spraying installation according to the invention, with a controlled change of coating product, is fed by a multiplicity of

  power loops (here 30) grouped into a plurality.

  (here 5) blocks A, B, C, D, E of six loops referenced 1 'to 6 with the lower case letter of its block. Each supply loop comprises, as represented here for the loop d, a tank R, a circulation pump P, a supply line Q and a return line S. On each supply loop Nx (N = 1 to 6, x = ae)

  is arranged a stitching with a manual valve N'x.

  Each block A, B, C, D, E of six feed loops is associated with a primary coating product change unit, respectively G, H, I, J, K, comprising six pneumatic control valves Ny with N = 1 to 6 in correspondence with the power loops, and y = g, h, i, j, k in correspondence with the reference of

the product change unit.

  In addition, each primary unit G-K comprises two pneumatically controlled valves 8 (g-k) and 9 (g-k), respectively connected to lines of rinsing product 20 and air under blowing and rinsing pressure 21, and

output 10 (g-k).

  It will be noted that the connections between the manual valves 1'a-6'a, 1'b-6'b, 1'c-6'c, 1'd-6'd, l'-6'e and the controlled valves lg-6g, lh-6h, li-6i, lj-6j, lk-6k, are

as short as possible.

  Moreover, the five outlets 10g-10k of the covering product change units are connected by 11g-11k pipes of length of the order of one meter to pneumatically controlled valves 11, 21, 31, 41, 51 respectively. a secondary unit L of coating product change, of conventional structure similar to that of the primary units GK. This secondary unit L also has pneumatic control valves 81 and 91 respectively connected to the lines 20 and 21 for supplying rinsing product and blowing air.

and drying, and an outlet 101.

  This secondary coating product changing unit L is located at a short distance from the product spray booths. Its output 1-01 is connected to a distribution circuit 12 comprising a product propulsion unit 40 as a whole, which will be described in more detail with reference to FIG. 2, which discharges into a pipe

  flexible 41 of connection to the projector 14.

  In practice, a car body covering station can have up to 9 projectors, each independently powered by a

  installation just described.

  The selection of the different coating products comprises, analogously to the conventional process of product change, the opening of the valve controlled in the group la-6a, 1b-6b, 1c-6c, 1d-6d, the -6e, which corresponds to the feed loop assigned to the desired coating product, and simultaneously that of the valve of the group 11-51 of the secondary unit L which corresponds to the appropriate group in the plurality AK of feed loops. The projection completed, and during the replacement of the painted body by the following in

  the cab, the secondary product change units L--

  and that of the G-K primary units that were used are

  rinsed, as well as the distribution circuit 12.

  A priori, that of intermediate channels 11g to 11k that has just been used should be purged of the paint it contains, then rinsed and dried from '. the primary coating product change unit at the outlet from which it is connected. However, the purge and cleaning of this intermediate pipe is useless if the next use of the same pipeline is to be done with the same coating product, and before the product that remains stagnant in the pipeline has begun to sediment. It will be understood that if the computer has memorized the prediction of the use of the coating products for a duration greater than the non-sedimentation time of the products, it is within the abilities of those skilled in the art to program this computer to identify the occurrence of the succession of use of the same product in the non-sedimentation time interval, and to control in response the inhibition of the purge and cleaning operation of the intermediate pipe of the

plurality 11g-11k.

  - However, to optimize the savings of coating and cleaning products,

  get as much frequency as possible from these.

  occurrences. However, if the succession of colors corresponding to the orders of the customers is random, the attraction of the various colors for the customers makes that the frequency of choice of the different.couleurs, or probability of use

  of each of the coating products is determinable.

  Without going into the details of probability calculations, it should be noted that the probability of successive use of the same coating product increases with the probability of use of this product. In addition, since each intermediate channel 11g-11k corresponds to a group of coating products, the probability of successive use occurrence increases with the probability that after a first use, the requests for other products will occur in other groups. Thus, after estimating the choice frequencies of the different colors, the five colors will be affected by the folds requested from each of the five groups of power loops A to E, then the five lower frequency colors. and so on in descending order of frequency, by operating for the different groups of five colors permutations to better equalize the probabilities of use of the five units

  Primary G to K of product change.

  It will further be appreciated that if a failure occurs in one of the primary coating product change units G to K, especially on a pneumatically operated valve, one can continue to work with the other primary units and change the product of coating, while one will intervene on the deficient organ after closing of the manual valves x to 6'x group X of -boucles supply corresponding to the primary unit Y down. It will be noted, moreover, that the decrease in manufacturing efficiency compared to the programmed orders will be substantially the same regardless of the primary unit in damage, since the coating products have been distributed to the primary units G to K to equalize at best their

Probability of use.

  As shown in FIG. 2, the propulsion means 40 comprise a rinsable pump 55, of the gear type, driven by a motor 50 with fast response time, and further connected to the output 101 of the secondary unit L of change. of coating product. The motor 50 is powered by a control electronics 51 with a comparator 52 which receives, on the one hand, a flow signal delivered by a flow sensor 53, and on the other hand, on an input 54, a signal of setpoint developed by a management automation principle known per se. In parallel, on the pump 55 is disposed a controlled valve 56 which can be open, either to discharge the pump in case of downstream overpressure, or to derive the rinsing product when the pump does not rotate. Between the pump 55 and the flow sensor 53 is disposed a three-way valve 57, which makes it possible to divert the rinsing product parallel to the flow sensor, which does not have to work.

in rinsing phase.

  Pressure sensors 58, 59 respectively upstream and downstream of the propulsion means 40 provide the safety functions to protect the pump 55 and the

flow sensor 53.

Claims (3)

  1- controlled installation for projecting coating product comprising at least one projector (14) supplied, through a distribution circuit (12) comprising means (40) for propelling coating product, from a switchgear coating material (G, H, I, J, K, L) connected to a multiplicity of feed loops (la-6a, lb-6b, lc-6c, ld-6d, -6e) each traversed by a particular coating product, by as many controlled valves, the apparatus being further selectively fed with rinsing product and pressurized drying air, characterized in that said apparatus is fractionated.in a plurality of units of coating product change (G to K), here referred to as primary units, arranged in parallel in close proximity to the multiplicity of feed loops (1a to 6e) and each having an output (10g-10k), and in that a unit of change of coating product t (L), here said secondary unit, has a plurality of inputs provided with controlled valves (11-51), each connected through an intermediate pipe (11g-11k) to the output of a respective primary unit (G to K), flush pipe after use from this respective primary unit. 2Installation according to claim 1, which control is provided by a computer o is stored a coating product change sequence forecast, characterized in that the computer is programmed to inhibit the rinsing of an intermediate pipe (11g-llk ) after use with a particular coating product if that line is to be reused at the first occurrence, by the same product of   coating, within a specified period of time.   3- Installation according to one of claims 1 and   2, characterized in that said propulsion means (40) comprises at the outlet (101) of the secondary unit (L) for changing the coating product a pump (55), preferably of the gear type, driven by a variable speed motor (50) controlled by a device (51, 52) responsive to the difference between a signal emitted by a flow sensor (53) in series with said pump (55) and a set signal (54).   4- Installation according to claim 3, characterized in that a controlled valve (56) is arranged in parallel with the pump (55).