Treatment plant for treating workpieces, and method for treating workpieces

Abstract

The present invention relates to a treatment plant (100) for treating workpieces, in particular for coating, for example dip-coating, vehicle bodies, the treatment plant (100) having a main conveying direction (102) and comprising the following: - at least one treatment zone (104) having at least one treatment tank (108), in particular at least one dip tank (110), for treating the workpieces with at least one treatment fluid, in particular dip-coating the workpieces with at least one coating; and - at least one rinsing zone (106) having at least one rinsing tank (112) for rinsing the treated workpieces with a filtrate of the at least one treatment fluid, in particular an ultrafiltrate of the at least one treatment fluid, the at least one rinsing zone (112) being downstream of the at least one treatment zone (104) in the main conveying direction (102), and the at least one treatment tank (108) of the treatment zone (104) being fluidically connected to at least one cooling circuit (124) for cooling at least part of the treatment fluid and / or to at least one filtrate circuit (128), in particular at least one ultrafiltrate circuit (130), for producing the filtrate, in particular the ultrafiltrate, and rinsing the treated workpieces with the filtrate, in particular the ultrafiltrate. The present invention also relates to a corresponding method for treating workpieces.

Description

[0001] Treatment system for treating workpieces and method for treating workpieces

[0002] The present invention relates to a treatment system for treating workpieces, in particular for coating, for example, dip-painting, vehicle bodies. The present invention further relates to a corresponding method for treating workpieces.

[0003] It is known from practice that treatment systems for the treatment of workpieces, in particular coating systems for the electrocoating of vehicle bodies, comprise a treatment zone with a dipping tank, in particular a paint dipping tank, and rinsing zones adjoining it in a main conveying direction, each with a rinsing tank, wherein each body passes through each zone, ie also each of the tanks, along the main conveying direction.

[0004] The rinsing basins can be either spray-rinsing or immersion-rinsing. Often, a spray-rinsing basin is provided in the first rinsing zone—adjacent to the treatment zone with the paint dip tank—and an immersion-rinsing basin is provided in the second zone.

[0005] Dip tanks typically have an overflow area separated by a weir with a slightly lower fluid level or bath level. This allows both the fluid level in the tank to be regulated and foam and other contaminants floating on the bath surface to be removed. The lower bath level is achieved and maintained by continuously removing treatment fluid or dip paint / varnish from the overflow area of ​​the tank via one or more circulation circuits and feeding it into the tank, i.e., the actual main volume.

[0006] In the known systems, a so-called ultrafiltrate from the dip coating is used as the rinsing fluid or rinsing medium. For this purpose, a portion of the treatment fluid is drained from the dip coating tank, treated by filtration, and then fed to the last rinsing zone, i.e., the zone furthest from the dip coating tank in the main conveying direction. From the last rinsing zone, the ultrafiltrate is conveyed in a cascade-like manner, counter to the main conveying direction, from rinsing zone to rinsing zone, and finally returned to the dip coating tank. The flow from one tank in one zone to the tank in the adjacent zone opposite the main conveying direction is achieved, for example, via a free overflow.Alternatively or additionally, the ultrafiltrate can also be fed from one tank to the next by means of a pump, which preferably conveys the filtrate to a large number of spray nozzles in the target tank, with which car bodies emerging from the target tank or which have just emerged from the target tank are rinsed.

[0007] Following the rinsing zones operated with ultrafiltrate, a further rinsing zone operated with demineralized water can be provided. In individual cases, a nanofiltrate produced from the previously produced ultrafiltrate can be used instead of the demineralized water.

[0008] The treatment fluid or paint must be continuously circulated in the dip tank to prevent separation. Furthermore, for a coating process such as electrocoating, it is advantageous if a certain flow prevails in the dip tank, which transports heat away from the surface of the car body being treated, delivers fresh treatment fluid to the surface of the car body being treated, and removes any gas bubbles that form on the surface of the car body being treated.

[0009] Another reason for circulation is that in the case of an electrocoating process, electrical power is introduced into the dipping tank and therefore the treatment fluid in the dipping tank, hereinafter also called bath, must be continuously cooled.

[0010] In addition, ultrafiltrate must be continuously generated for the rinsing zones, so three separate fluid circuits are typically provided. Each of these three circuits in a dip tank preferably has its own pumping device or pump, by means of which treatment fluid or paint is pumped out of the dip tank and finally back into the dip tank.

[0011] First, a cooling circuit is provided as one of three circulation circuits, in which the treatment fluid is passed through a heat exchanger and cooled there to the desired temperature. The circulation volume of the cooling circuit is approximately 30% to 40% of the required total circulation volume of the circuits. Second, an ultrafiltrate circuit is provided as a further circulation circuit, in which the treatment fluid or the paint for producing the ultrafiltrate is removed from the immersion tank and passed through filter modules, preferably with ultrafiltration membranes. The circulation volume of the ultrafiltrate circuit is 20% to 30% of the required total circulation volume of the circuits.

[0012] Thirdly, a bath flow circuit is provided as a third circulation circuit, through which the remaining amount of approximately 30% to 50% of the required total circulation volume of the circuits is circulated.

[0013] As a rule, all three circuits of a dip tank are equipped with filters or filter modules, which preferably have one or more bag filters, through which the circulated treatment fluid or the circulated paint is filtered.

[0014] For the return or supply of the treatment fluid or the filtrate from the three circuits into the immersion tank, nozzles or flood pipes are usually provided, which are preferably aligned in such a way that a flow favorable for the treatment process is established or promoted in the immersion tank, ie in the immersion bath.

[0015] For the dip-coating process of a vehicle body, a fixed process duration of, for example, 4 minutes per body is usually specified, with the bodies being moved sequentially and continuously through the dip tank in the main conveying direction. The extension of the dip tank in the main conveying direction, i.e., the longitudinal extension of the tank, is therefore dependent on the body length and the conveying speed, so that the required or specified process duration is just achieved during the passage of the respective body through the dip tank.

[0016] The conveyor speed is determined by the required workpiece throughput through the system in question. The more car bodies are to be treated or produced per unit of time, the higher the conveyor speed and, likewise, the greater the required length of the paint dip tank.

[0017] The resulting disadvantages of such a treatment system are readily apparent: the successive process sequence in the main conveying direction results in very long systems. The actual dipping tank, in particular, is very long for high workpiece throughputs. To increase system capacity, i.e., throughput, the dipping tank must be extended, and consequently, the rinsing zones must be shifted along the main conveying direction. The cost and time required for such measures are considerable. Alternatively, systems must be designed with a space reserve from the outset, or an oversized dipping tank must be provided.

[0018] Conversely, this of course means that if the throughput is reduced, the immersion tank is unnecessarily long and therefore largely runs empty.

[0019] Furthermore, the immersion tank has to be completely emptied for maintenance and / or repair work, which requires the system to be temporarily shut down. This also makes optimization measures, such as the iterative adjustment of the nozzle alignment, very complex and expensive.

[0020] Furthermore, a mixed treatment of different car body types with different process times is not possible in such a treatment line. The same applies to the treatment of different car body types with different treatment fluids or paints.

[0021] The present invention is therefore based on the object of providing a treatment system for treating workpieces which enables more flexible and cost-effective treatment process adjustments and is easier to maintain.

[0022] This object is achieved according to the invention by a treatment plant having the features according to claim 1.

[0023] The treatment plant is in particular a treatment plant for treating workpieces.

[0024] Preferably, the treatment plant is a plant for coating vehicle bodies, in particular a plant for dip-coating vehicle bodies.

[0025] The treatment system has a main conveying direction along which the workpieces are conveyed during their treatment. The treatment system further comprises the following: at least one treatment zone with at least one treatment tank, in particular at least one dip tank, for treating the workpieces with at least one treatment fluid, in particular dip-coating the workpieces with at least one paint; and at least one rinsing zone with at least one rinsing tank for rinsing the treated workpieces with a filtrate of the at least one treatment fluid, in particular an ultrafiltrate of the at least one treatment fluid.

[0026] The at least one rinsing zone is arranged in the main conveying direction after the at least one treatment zone.

[0027] Furthermore, the at least one treatment basin of the treatment zone is fluidically connected to at least one cooling circuit for cooling at least a portion of the treatment fluid and / or at least one filtrate circuit, in particular at least one ultrafiltrate circuit, for producing the filtrate, in particular the ultrafiltrate, from which at least one treatment fluid and rinsing the treated workpieces with the filtrate, in particular the ultrafiltrate.

[0028] The invention is based on the basic idea that a treatment plant comprises up to three immersion tanks into which the workpieces to be treated, in particular vehicle bodies, are introduced and removed from a main conveyor line alternatively, i.e., into only one of the immersion tanks at a time. Subsequently, all workpieces treated in one of the immersion tanks pass through the rinsing zone, which preferably comprises several consecutive rinsing tanks, wherein the workpieces are rinsed in the rinsing zone with a filtrate produced from the treatment fluid of all the immersion tanks. The immersion tanks in operation are preferably aligned parallel to one another and arranged on one side of the main conveyor line, whereby the immersion tanks are easier to maintain, retrofit, and / or replace.Furthermore, providing multiple immersion tanks not only increases the throughput of workpieces to be treated, but also allows for more flexible responses to different workpieces or treatment parameters. It may be advantageous if the at least one treatment tank in the treatment zone is also fluidly connected to at least one circulation circuit for circulating at least a portion of the treatment fluid.

[0029] In other words, the at least one treatment tank can advantageously be fluidly connected to three circuits, namely the cooling circuit, the filtrate circuit and the circulation circuit.

[0030] In the event that at least one treatment tank is only connected to the cooling circuit and the filtrate circuit, these should preferably be dimensioned larger in order to be able to at least approximately take over the function of the circulation circuit.

[0031] It is preferably provided that the immersion tanks can be coupled fluidically or fluidically, so that a continuous mixing of the treatment fluid, in particular of the paint, takes place in order to obtain an approximately identical quality of the treatment fluid in the immersion tanks.

[0032] It may be advantageous if each immersion tank can also be operated individually, particularly without mixing the treatment fluid with fluid from the other immersion tanks. This also means that each immersion tank can be shut down and / or emptied individually or separately, without affecting the treatment process in the other immersion tanks.

[0033] The treatment system according to the invention is preferably modularly expandable, meaning that additional immersion tanks can be easily added. This is possible primarily because the treatment system comprises a main conveyor line with a main conveying direction, adjacent to which the treatment zone and the rinsing zone are located. The workpieces are conveyed into and out of the zones by the main conveyor line, thus overcoming the disadvantages of a linear arrangement of the tanks.

[0034] Preferably, the treatment tank includes an overflow area for regulating the level of the treatment fluid in a main volume of the treatment tank. The amount of treatment fluid contained in the main volume of the treatment tank is also called the fluid bath, and the level of the treatment fluid to be regulated is accordingly the fluid bath level.

[0035] Furthermore, it can be provided that the sink is a spray sink or a plunge sink.

[0036] In a preferred embodiment of the invention, it can be provided that the rinsing zone comprises a spray rinsing basin and a dip rinsing basin.

[0037] It may be advantageous for each circuit to comprise at least one pump device and at least one filter device.

[0038] Furthermore, it can be provided that the at least one cooling circuit comprises at least one heat transfer device for cooling the treatment fluid.

[0039] In one embodiment of the invention, it can be provided that the at least one rinsing basin is integrated into the at least one filtrate circuit.

[0040] In other words, the workpieces are rinsed in the rinsing tanks with the filtrate produced in the filtrate circuit.

[0041] It may be advantageous if the at least one filtrate circuit comprises a collecting tank upstream of the at least one rinsing basin.

[0042] If several treatment tanks, in particular immersion tanks, are provided, the filtrate produced from the treatment fluid of these tanks is collected in the common collection tank and then passed on to the rinsing zone.

[0043] It can further be provided that the treatment plant comprises at least one spray rinsing tank and at least one immersion rinsing tank, wherein the spray rinsing tank is arranged between the treatment tank and the immersion rinsing tank with respect to the main conveying direction.

[0044] It is also advantageous if the filtrate can be conveyed in a cascade from sink to sink, counter to the main conveying direction, wherein the filtrate can be supplied to each sink indirectly via a plurality of spray nozzles and / or directly via a supply line or an overflow.

[0045] It can further be provided that the treatment plant comprises at least two, preferably three, dipping tanks arranged parallel to one another, wherein a longitudinal extent of the dipping tanks is aligned transversely to the main conveying direction, and wherein the workpieces can be conveyed into the dipping tanks transversely to the main conveying direction and / or out of the dipping tanks transversely to the main conveying direction.

[0046] In one embodiment of the invention, it can be provided that the filtrate circuit of each immersion tank has a shut-off valve upstream of the collecting tank.

[0047] It may also be advantageous if the treatment fluids carried in the circulation circuits of the immersion tanks can be mixed in a common mixing pipe with at least one pipe section.

[0048] In one embodiment of the invention, it can be provided that a bypass line is provided in each of the circulation circuits of the immersion tanks.

[0049] Bypass lines can be used to avoid the mixing of the treatment fluids in the circulation circuits, which may be necessary, for example, if mixing of the treatment fluids is not permitted for quality reasons.

[0050] The object of the invention can further be achieved by a method for treating workpieces having the features according to claim 14.

[0051] The process is in particular a process for coating, for example dip painting, vehicle bodies.

[0052] The procedure includes the following steps:

[0053] Treating workpieces in at least one, preferably three, dip tanks of a treatment zone arranged parallel to one another with treatment fluid, wherein each workpiece is preferably treated in only one dip tank;

[0054] Spray rinsing of the treated workpieces in at least one spray rinsing tank of a rinsing zone; and immersion rinsing of the treated and spray-rinsed workpieces in at least one immersion rinsing tank of the rinsing zone.

[0055] Accordingly, each workpiece is preferably treated in only one of the possible immersion tanks of the treatment zone with the treatment fluid of the corresponding immersion tank and then rinsed in each of the spray rinse tanks and each of the immersion rinse tanks of the rinsing zone.

[0056] A portion of the treatment fluid in each immersion tank is cooled in a separate cooling circuit using a heat transfer device.

[0057] In addition, ultrafiltrate is produced from a further part of the treatment fluid of each immersion tank for the rinsing processes, which is returned in an ultrafiltrate circuit from a common collecting tank in a cascade manner from the immersion rinsing tank via the spray rinsing tank to the at least one immersion tank, preferably three immersion tanks.

[0058] It may also be advantageous if another part of the treatment fluid from each immersion tank is fed into a separate circulation circuit to generate flow and mix.

[0059] In one embodiment of the invention, it can be provided that the circulation circuits are operated in a bypass mode for circulating the treatment fluid of the respective immersion tank and / or in a mixed mode for mixing the treatment fluids conducted in the circulation circuits in a common mixing pipe with at least one pipe section

[0060] The method preferably has one or more of the features and / or advantages described in connection with the treatment plant.

[0061] Furthermore, the treatment plant preferably has one or more of the features and / or advantages described in connection with the method.

[0062] Further preferred features and / or advantages of the invention are the subject of the following description and the drawings of embodiments. The figures show:

[0063] Fig. 1 is a schematic representation of a first embodiment of a treatment plant according to the invention;

[0064] Fig. 2 is a schematic representation of a filtrate circuit of a second embodiment of a treatment plant according to the invention with three immersion tanks;

[0065] Fig. 3 is a schematic representation of two circulation circuits of a third embodiment of a treatment plant according to the invention with two immersion tanks;

[0066] Fig. 4 is a schematic representation of three circulation circuits of the second embodiment of a treatment plant according to the invention with three immersion tanks; and

[0067] Fig. 5 is a schematic representation of the complete second embodiment of a treatment plant according to the invention with three immersion tanks.

[0068] Identical or functionally equivalent elements are provided with the same reference numerals in all figures.

[0069] A first embodiment of a treatment system, designated as a whole by 100, for treating workpieces (not shown), shown in Fig. 1.

[0070] The treatment system 100 is used in particular for coating workpieces designed as vehicle bodies with a treatment fluid (not shown).

[0071] Preferably, the treatment system 100 is used for electrocoating vehicle bodies with a paint.

[0072] The treatment plant 100 comprises a treatment zone 104 and a rinsing zone 106 arranged one behind the other in a main conveying direction 102. The treatment zone 104 comprises a treatment tank 108, which is designed as an immersion tank 110.

[0073] The rinsing zone 106 comprises two rinsing basins 112, one of which is designed as a spray rinsing basin 114 and the other as a dip rinsing basin 116.

[0074] The spray rinse basin 114 is arranged between the immersion basin 110 and the immersion rinse basin 116.

[0075] It should be understood that further spray rinse tanks 114 may be arranged between the dip tank 110 and the dip rinse tank 116 and further dip rinse tanks 116 may be arranged downstream of the first dip rinse tank 116 with respect to the main conveying direction 102.

[0076] In the dipping tank 110, the workpieces are treated with a treatment fluid; preferably, the workpieces are electrocoated with a paint in the dipping tank 110.

[0077] The treatment fluid volume contained in an immersion tank 110 is hereinafter also referred to as the fluid bath.

[0078] In the spray rinsing tank 114 and the immersion rinsing tank 116, the workpieces are rinsed with a filtrate of the treatment fluid, preferably with an ultrafiltrate of the treatment fluid.

[0079] The immersion tank 110 has an overflow area 118, which is separated by a weir 120 from a main volume 122 of the immersion tank 110, which is filled with the treatment fluid or contains the fluid bath. The bath level of the fluid contained in the overflow area 118 is preferably lower than the bath level of the treatment fluid in the main volume 122 of the immersion tank 110.

[0080] The overflow area 118 serves to regulate the level of the bath in the main volume 122 and to safely discharge foam and / or other contaminants floating on the surface of the fluid bath.

[0081] The workpieces are preferably introduced into and / or removed from the dipping tank 110 transversely to the main conveying direction 102, wherein workpieces designed as vehicle bodies are preferably conveyed in a transverse orientation along the main conveying direction 102 and are accordingly introduced into or removed from the dipping tank 110 along their longitudinal axis.

[0082] Consequently, the treatment plant 100 preferably comprises a main conveyor line with a main conveyor device (both not shown in Fig. 1), in particular a horizontal and / or rectilinear main conveyor line, wherein the immersion tank 110, the spray rinsing tank 114 and the immersion rinsing tank 116 are arranged on one side of the main conveyor line or on different sides of the main conveyor line, preferably each with a shorter side of the tank adjacent to the main conveyor line.

[0083] The workpieces are conveyed along the main conveyor line in the main conveying direction 102 and from there the workpieces are introduced into and / or removed from the dip tank 110, the spray rinsing tank 114 and the dip rinsing tank 116.

[0084] It is also conceivable that the spray rinsing tank 114 is arranged or integrated in the area of ​​the main conveyor line in such a way that each workpiece is conveyed along the main conveying direction 102 through the spray rinsing tank 114, ie without transverse conveyance into a tank arranged next to the main conveyor line.

[0085] The immersion tank 110 is preferably designed for a throughput of 5 to 15 car bodies per hour, preferably up to 10 car bodies per hour.

[0086] The immersion tank 110 is fluidly connected to a cooling circuit 124, a circulation circuit 126 and a filtrate circuit 126, which is preferably an ultrafiltrate circuit 128 or is designed as such, through each of which at least a portion of the treatment fluid is continuously passed.

[0087] The cooling circuit 124 comprises a pump device 132, a filter device 134 and a heat transfer device 136, wherein the filter device 134 is preferably arranged downstream of the pump device 132 and the heat transfer device 136 is preferably arranged downstream of the filter device 134.

[0088] By means of the heat transfer device 136, the portion of the treatment fluid passed through the cooling circuit 124 is continuously cooled, since the treatment fluid heats up during the electrocoating in the main volume 122 of the dip tank 110 due to the process-related input of electrical power.

[0089] A sufficient amount of treatment fluid is pumped through the cooling circuit 124 to keep the fluid bath in the immersion tank 110 at a desired temperature even at maximum throughput of workpieces to be treated.

[0090] The volume flow in the cooling circuit 124 is at least one time, preferably one and a half times, the fluid bath of the immersion tank 110 per hour.

[0091] The circulation circuit 126 also comprises a pump device 132 and a filter device 134 arranged downstream thereof.

[0092] The circulation circuit 126 continuously supplies fluid from the overflow area 118 of the

[0093] diving basin 110 and feeds it to the main volume 122 of the diving basin 110.

[0094] By continuously draining the fluid from the overflow area 118, a lower bath level can be achieved there than in the main volume 122.

[0095] It can be provided that several circulation circuits 126 are provided on a dip tank 110, which circulate the fluid from the overflow area 118 into the main volume 122 of the dip tank 110.

[0096] The circulation circuit 126 is designed so that, together with the two other circuits 124 and 128, sufficient circulation of the treatment fluid in the main volume 122, i.e. the fluid bath, is achieved.

[0097] The volume flow in the circulation circuit 126 is preferably approximately one to two times, preferably one and a half times, the fluid bath in the immersion tank 110 per hour.

[0098] In the ultrafiltrate circuit 130, as much treatment fluid is circulated as is required to produce a sufficient amount of ultrafiltrate for the downstream rinsing processes.

[0099] Preferably, approximately two liters of ultrafiltrate per square meter of workpiece surface are used. The amount of ultrafiltrate produced is determined according to the maximum throughput of the workpieces to be treated and remains constant even at reduced throughput.

[0100] The volume flow in the ultrafiltrate circuit 130 is preferably approximately one times that of the fluid bath of the immersion tank 110 per hour.

[0101] To generate the ultrafiltrate in the ultrafiltrate circuit 130, fluid is preferably pumped out of the overflow area 118 by means of a pump device 132 and passed through a filter device 134. The filtered fluid is then passed through an ultrafiltrate filter device 138, which has an ultrafiltration membrane, whereby a portion of the fluid components with small particle size penetrates the ultrafiltration membrane. This ultrafiltrate is collected in a collection container 140. The remaining fluid is fed to the main volume 122.

[0102] From the collection container 140, the collected ultrafiltrate is fed to the immersion rinsing tank 116 by means of a further pump device 132.

[0103] The ultrafiltrate can be fed to the immersion rinse tank 116 directly via a supply line 142 into the fluid bath of the immersion rinse tank 116 or indirectly via a plurality of spray nozzles 144, with which the ultrafiltrate is preferably applied to workpieces emerging from the tank or which have just been immersed.

[0104] By means of two valve devices 146, one of which is provided for the direct supply line 142 and the other for the indirect supply by means of the spray nozzles 144, it is possible to switch between the type of supply.

[0105] The spray nozzles 144 are preferably active whenever a workpiece is emerging from the immersion rinse tank 116. For this purpose, the spray nozzles 144 can be arranged, for example, along the upper edge of the immersion rinse tank 116 or can be arranged as a ring or ring-like arrangement on the front side of the immersion rinse tank 116, through which the immersed workpiece is guided.

[0106] Ultrafiltrate is continuously conveyed from the immersion rinse tank 116 to the spray rinse tank 114. The ultrafiltrate can be conveyed directly via a free overflow 148 and / or indirectly by means of spray nozzles 144 arranged on the spray rinse tank 114. The spray nozzles 144 of the spray rinse tank 114 are preferably provided for rinsing the already rinsed workpieces in the spray rinse tank again, which is particularly the case when the workpieces leave the area or zone of the spray rinse tank 114 and are conveyed further to the immersion rinse tank 116.

[0107] The spray nozzles 144 of the spray rinsing basin 114 can also be switched on or off via a valve device 146.

[0108] The ultrafiltrate from the immersion rinse tank 116 is fed to the spray nozzles 144 of the spray rinse tank 114, preferably by means of a pump device 132.

[0109] From the spray rinsing tank 114, the ultrafiltrate is fed by means of a further pump device 132 directly via a feed line 142 to the overflow area 118 of the immersion tank 110 and / or indirectly to the main volume 122 by means of spray nozzles 144 which are arranged on the immersion tank 110.

[0110] The type of supply of the ultrafiltrate to the immersion tank 110 or the return to the immersion tank 110 can also be switched via two valve devices 146, one of which is assigned to the direct supply line 142 into the overflow area 118 and the other to the indirect supply by means of the spray nozzles 144.

[0111] However, it is also conceivable that the direct supply line 142 of the ultrafiltrate from the spray rinsing basin 114 is made into the main volume 122 or into both the main volume 122 and the overflow area 118.

[0112] With the spray nozzles 144 of the immersion tank 110, the ultrafiltrate is preferably applied to workpieces emerging from the immersion tank 110 or just emerging from the immersion tank 110, such as vehicle bodies, and / or to parts or sections of the conveyor system (not shown) provided for the insertion and removal of the workpieces, which are immersed in the fluid bath of the immersion tank 110.

[0113] The spray nozzles 144 of the immersion tank 110 are preferably only active when a workpiece is emerging from the immersion tank 110 in order to rinse off any foam adhering to it or any treatment fluid still running down. The spray nozzles 144 of the immersion tank 110 can be arranged along the upper edge of the tank, similar to the spray nozzles 144 of the immersion rinse tank 116, or can be arranged as a ring or ring-like arrangement on the front side of the immersion rinse tank 116, through which the immersed workpiece is guided.

[0114] The flow or stream of the ultrafiltrate from the immersion rinsing tank 116 to the immersion tank 110 is thus opposite to the main conveying direction 102.

[0115] The fill level of the fluid bath in the immersion rinsing tank 116 and in the immersion tank 110 is further preferably detected and / or monitored via at least one fill level measuring device 150 in each case.

[0116] Fig. 2 shows a second embodiment of a treatment plant 100, which comprises three immersion tanks 110, which are preferably arranged parallel to one another and border the main conveying line with one of their short sides.

[0117] The second embodiment in Fig. 2 essentially shows the filtrate circuit 128.

[0118] It should nevertheless be understood that each of the immersion tanks 110 is connected to a cooling circuit 124 and a recirculation circuit 126, as can be seen in Figs. 4 and 5.

[0119] The rinsing zone 106, which comprises a spray rinsing tank 114 and a dip rinsing tank, is preferably passed through by all workpieces of the three dip tanks 110.

[0120] In order to provide the required amount of ultrafiltrate, filtrate produced from all three immersion tanks 110 is combined to feed the rinsing zone 106.

[0121] For this purpose, the ultrafiltrate from each immersion tank 110 is collected in the collection container 140 after the ultrafiltrate filter device 138.

[0122] From there, it is fed to the last rinsing basin 112, i.e. here the only immersion rinsing basin 116, and then, as described in connection with the first embodiment in Fig. 1, in a cascade manner against the main conveying direction 102 of

[0123] Rinse basin 112 to rinse basin 112. Following the rinse basin 112, which is directly adjacent to the immersion basins 110, i.e. the spray rinse basin 114 in Fig. 2, the ultrafiltrate is distributed among the immersion basins 110.

[0124] By feeding the ultrafiltrate into the rearmost rinsing basin 112 in the main conveying direction 102, i.e. in this case the immersion rinsing basin 116, and the cascade-like continuation into the adjacent rinsing basin 112 opposite to the main conveying direction 102, it is ensured that the workpieces which are conveyed in the main conveying direction 102 from the immersion basin 110 to the (last) immersion rinsing basin 116 are rinsed with purer ultrafiltrate in each of the successive rinsing processes in the rinsing zone 106 than in the respective preceding rinsing process.

[0125] Conversely, with each rinsing cycle towards the dip tank 110, the ultrafiltrate absorbs more components of the treatment fluid, in particular paint components, which are finally returned to the dip tank 110.

[0126] The three immersion tanks 110 are preferably all of the same type and designed for a combined throughput of 25 to 35 workpieces per hour, preferably 30 workpieces, in particular vehicle bodies, per hour.

[0127] A treatment system 100 with three dip tanks 110 in the treatment zone 104 as well as a spray rinsing tank 114 and a dip rinsing tank 116 in the rinsing zone 106 is the preferred embodiment, in particular for the electrocoating of vehicle bodies.

[0128] In order to keep the composition of the treatment fluid and the fill level or bath level constant in all three immersion tanks 110, it should be ensured that the same amount of ultrafiltrate is returned to each immersion tank 110 as was generated from its treatment fluid and fed to the rinsing zone 106.

[0129] For this purpose, for each immersion tank 110, the amount of filtrate or ultrafiltrate produced per hour is recorded using a separate measuring device 152, preferably a flow measuring device 154, which is preferably arranged between the ultra-filter device 138 and the collection container 140. In addition, for each immersion tank 110, the amount of ultrafiltrate returned per hour via the direct supply line 142 or the spray nozzles 144 is recorded using a further measuring device 152, preferably a flow measuring device 154.

[0130] The valve devices 146 of the supply line 142 and the spray nozzles 144 of the immersion tanks 110 are preferably designed as automatic valves, so that by means of these automatic valves it can be regulated that the respectively returned amount of ultrafiltrate corresponds at least approximately to the respectively produced amount of ultrafiltrate.

[0131] Since the flow in the return line to the immersion tanks 110 can fluctuate due to the activation and deactivation of the spray nozzles 144, it is advisable to use average values ​​over defined periods of time, for example from a few minutes to one hour, instead of actual values ​​for the flow rate control.

[0132] Due to evaporation and carryover, i.e. ultrafiltrate still adhering to the workpieces during discharge, of ultrafiltrate in the course of discharging or conveying the workpieces out of the last rinsing tank 112, in this case from the immersion rinsing tank 116, in the direction of the main conveying section, there is a continuous loss of ultrafiltrate from the filtrate circuit 128.

[0133] This loss is preferably compensated by adding demineralized water 156 to the last rinsing basin 112, ie the immersion rinsing basin 116.

[0134] The amount of demineralized water 156 added can be regulated so that the fill level of the immersion rinse tank 116 remains constant, ie the bath level of the immersion rinse tank 116 remains constant, wherein the fill level is detected and / or monitored via the fill level measuring device 150 arranged on the immersion rinse tank 116.

[0135] The supply of demineralized water 156 can be effected directly from a supply line into the (last) immersion rinsing basin 116 or in the form of a cascade-like supply from a further rinsing zone 106 downstream in the main conveying direction 102, the rinsing basins 112 of which are operated with demineralized water.

[0136] It may be provided that different treatment fluids or different paints, in particular paints of different colors, are used in the immersion tanks 110, provided that mixing of the ultrafiltrate produced from these treatment fluids is permissible in terms of process technology and / or quality.

[0137] Downstream of the respective ultrafiltrate filter device 138, a shut-off valve 158 is preferably provided, by means of which the associated immersion tank 110 can be taken out of operation.

[0138] This may be necessary, for example, to maintain, repair, or replace an individual immersion tank 110. Consequently, the treatment system 100 is modular, at least with respect to the immersion tanks 110.

[0139] By closing the corresponding line from the immersion tank 110 to the collecting tank 140 by means of the respective shut-off valve 158, the affected immersion tank 110 is at least temporarily removed from the filtrate circuit 128.

[0140] Fig. 3 shows a third embodiment of a treatment plant 100, which comprises two parallel immersion tanks 110.

[0141] In Fig. 3, only the circulation circuits 126 of the immersion tanks 110 are shown, the cooling circuits 124 and the filtrate circuit 128 are hidden for the sake of clarity.

[0142] In principle, the respective circulation circuit 126 is intended to generate sufficient circulation in the main volume 122 of the immersion tank 110 so that the workpiece to be treated is sufficiently supplied with the treatment fluid for the treatment process and that the treatment fluid is sufficiently mixed.

[0143] It should be understood that the other two circuits 124, 128 also contribute to the circulation in the immersion tanks 110.

[0144] It may be necessary or desirable for the treatment fluids of the various immersion tanks 110 to be continuously mixed, for example, to ensure a virtually identical quality of the treatment fluid in all immersion tanks 110. By coupling the circulation circuits 126, the individual immersion tanks 110 also react less sensitively to process changes. Furthermore, the effort required for regularly monitoring the fluid bath parameters can be reduced, since not all parameters need to be measured for each immersion tank 110.

[0145] The mixing of the treatment fluids can be achieved by passing the respective treatment fluid, preferably downstream of the filter device 134 of the respective circulation circuit 126, through a common mixing pipe 160 with at least one pipe section 162.

[0146] The diameter of the pipe section 162 is preferably selected such that the flow velocity of the treatment fluid in the mixing pipe 160 does not exceed the value of 2 m / s when all immersion tanks 110 are in operation and does not fall below the value of 1 m / s when an immersion tank 110 is shut down.

[0147] The flow velocity in all operating conditions is preferably between 1.1 m / s and 1.7 m / s.

[0148] The mixing pipe 160 has a larger diameter than the other pipes of the circulation circuits 126.

[0149] The treatment fluids are fed to the mixing tube 160 at a first end 164 and divided at a second end 166 into the partial flows of the involved circulation circuits 126 and returned to the immersion tanks 110.

[0150] The mixed fluid is preferably returned directly to the main volume 122 of the immersion tanks 110.

[0151] The distribution of the partial flows into the individual immersion tanks 110 is controlled by automatic valves 168 in the return lines 170.

[0152] The position of the automatic flaps 168 is controlled based on the fill levels in the immersion tanks 110, for which each immersion tank has a fill level measuring device 150.

[0153] The aim of the control is to keep the fill level in all immersion tanks 110 approximately the same. Consequently, the automatic flap 168 of an immersion tank 110 whose fill level deviates upwards from the mean of the fill levels of all immersion tanks 110 is at least partially closed, while automatic flaps 168 of immersion tanks 110 whose fill levels deviate downwards from the mean, i.e., are lower than the mean, are simultaneously opened further.

[0154] For simplified initial adjustment, flow measuring devices 154 can be provided in the return lines 170.

[0155] For example, a deviation of a filling level of 1% from the mean value can be defined as a permissible deviation or as a triggering criterion for readjustment of the automatic flaps 168 in order to keep the total deviation preferably within a range of approximately 2%.

[0156] In order to be able to take the immersion tanks 110 out of operation individually, for example for retrofitting or maintenance, or to be able to operate individual immersion tanks 110 independently of the other immersion tanks 110, a bypass line 172 can additionally be provided in each circulation circuit 126, which allows the mixing pipe 160 to be bypassed.

[0157] For this purpose, a shut-off valve 158 is provided in the bypass line 172, which is opened for bypassing, while the supply to the mixing pipe 160 and the return from the mixing pipe are also blocked by means of shut-off valves 158.

[0158] The provision of a bypass line 172 allows the affected immersion tank 110 to be emptied, for example, for maintenance work or the operation of individual immersion tanks 110 with a different treatment fluid, for which mixing via the circulation circuits 126 is not permitted, but mixing of the filtrates produced from the different treatment fluids is permitted.

[0159] In a configuration of a treatment plant 100 with two immersion tanks 110, as shown in Fig. 3, the mixing pipe 160 comprises only one pipe section 162 with a constant diameter.

[0160] If the corresponding bypass line 172 for one of the two immersion tanks 110 is opened and the corresponding shut-off valves 158 in the supply and return lines are closed, for example, to prevent mixing or to shut down the affected immersion tank 110, the bypass line 172 of the other immersion tank 110 is also opened and the corresponding shut-off valves 158 in the supply and return lines are closed. Consequently, in this case, no flow passes through the common mixing pipe 160.

[0161] In order to achieve better mixing in the mixing tube 160 by means of stronger swirling, the inlet of the partial flows from the involved circulation circuits can be tangential at the first end 164 of the mixing tube 160 and / or swirling-promoting internals can be provided at the first end 164 in the mixing tube 160.

[0162] In comparison to the third embodiment of a treatment plant 100 with two immersion tanks 110, as shown in Fig. 3, Fig. 4 shows the interaction of the circulation circuits of the second embodiment of a treatment plant 100 with three immersion tanks 110.

[0163] In a configuration of the treatment plant 100 with three immersion tanks 110, the mixing pipe 160 preferably comprises two pipe sections 162 with different diameters, wherein the pipe section 162 into which the partial flows of the recirculation circuits 126 enter or flow, ie the pipe section with the first end 164 of the mixing pipe 160, has the larger of the two pipe section diameters.

[0164] The mixing of the treatment fluids of all immersion tanks 110 therefore takes place in the pipe section 162 with the larger diameter, hereinafter referred to as the second pipe section.

[0165] At the end of the second pipe section, a branch of a partial flow is provided for the return to one of the immersion tanks 110, so that the adjoining pipe section 162 with the smaller diameter, hereinafter referred to as the first pipe section, is only flowed through by a reduced fluid flow, which preferably corresponds to the partial flows of two immersion tanks 110.

[0166] In the event that only treatment fluid from two immersion tanks 110 is to be mixed and one of the immersion tanks 110 is operated in bypass mode, both pipe sections 162 of the mixing pipe 160 are nevertheless flowed through by the partial flows from the two remaining immersion tanks 110. In the event that two immersion tanks 110 are to be operated in bypass mode, the third immersion tank 110 must also be operated in bypass mode, meaning that in this case, no flow passes through the mixing pipe 160.

[0167] The provision of two pipe sections 162 with different diameters ensures that the flow velocity in the mixing pipe 160 is in a value range of 1 m / s to 2 m / s when operating one or two immersion tanks 110 in the bypass.

[0168] To expand a treatment system 100 from one immersion tank 110 to two immersion tanks 110, whose treatment fluids are to be mixed, only the mixing pipe 160, the bypass line 172, and the shut-off valves 158 need to be retrofitted. To expand from two immersion tanks 110 to three immersion tanks 110, the mixing pipe 160 is essentially extended by a pipe section 162, and the supply is relocated to its end, the then adapted first end 164 of the mixing pipe 160.

[0169] Due to evaporation and the entrainment of treatment fluid by the treated workpieces conveyed out of the immersion tanks 110, treatment fluid is continuously discharged from the immersion tanks 110, causing the fill level or the fluid bath to drop during operation. To counteract this, demineralized water 156 is added to the overflow areas 118 of the immersion tanks 110, as shown in Figs. 3 to 5.

[0170] The amount of demineralized water 156 added is regulated based on the fill level in the main volume 122 of the respective immersion tank 110 so that the level of the bath surface remains approximately constant, wherein the fill level is detected and / or monitored by a fill level measuring device 150.

[0171] For immersion tanks 110 coupled via the mixing pipe 160, the total fill level of all immersion tanks 110 is preferably considered to determine the amount of demineralized water 156 to be refilled. Either a lower limit value for the total fill level or the temporal development of the total fill level can be considered as a criterion.

[0172] Finally, Fig. 5 shows the complete second embodiment of the treatment system 100 with three immersion tanks 110, wherein Fig. 5 shows all cooling circuits 124, all circulation circuits 126 with a common mixing tube 160, and the connected filtrate circuits 128. The treatment of the workpieces, in particular the coating of vehicle bodies, results in a constant discharge of components of the treatment fluid, in particular paint components such as pigments, binders, and additives, which must be continuously replenished or replaced to ensure consistent quality of the treated workpieces.

[0173] Since the consumption or discharge of these components depends on the throughput of the workpieces to be treated and is therefore individual for each immersion tank 110, the addition or replenishment preferably takes place in the respective cooling circuit 124 and the filtrate circuit 128, wherein for a rapid mixing of these components the component to be re-dosed or re-supplied takes place upstream of the first pump device 132.

[0174] Pigment paste 174, particularly highly viscous pigment paste, is preferably added in the cooling circuit 124, whereas the non-solids-containing mixture 175 of binder and solvent is introduced upstream of the pump device 132 of the filtrate circuit 128, which is arranged between the immersion tank 110 and the collection tank 140. The separation of these two components according to circuits is based on the fact that both components should not be added simultaneously at the same point, since undesirable effects, such as agglomeration, can occur in high concentrations if they are mixed directly. Alternatively or additionally, the binder can also be added in the overflow area 118 of the immersion tank 110, where additional components such as an acid 176 can also be added to regulate the pH of the treatment fluid.

[0175] For continuous monitoring of the fluid bath parameters, such as pH, conductivity, or treatment fluid composition, a measuring or sampling point can ideally be provided downstream of the mixing tube 160. In this way, the fluid bath parameters for all mixed immersion tanks 110 can be analyzed simultaneously. If necessary, additional measurements can be performed in the individual immersion tanks 110.

[0176] It should be understood that the first, second or third embodiment of a treatment plant 100 according to the invention preferably has one or more of the features and / or advantages described in connection with the other two embodiments.

[0177] List of reference symbols

[0178] Treatment plant

[0179] Main conveying direction

[0180] Treatment zone

[0181] Rinse zone

[0182] Treatment pool

[0183] plunge pool

[0184] sink

[0185] Spray sink

[0186] Plunge sink overflow area weir

[0187] Main volume

[0188] Cooling circuit

[0189] Circulation circuit

[0190] Filtrate circuit

[0191] Ultrafiltrate circuit

[0192] Pump device Filter device

[0193] Heat transfer device Ultrafiltrate filter device Collection tank

[0194] supply line

[0195] Spray nozzles

[0196] Valve device free overflow level measuring device

[0197] measuring device

[0198] Flow measuring device demineralized water butterfly valve

[0199] mixing tube

[0200] Pipe section first end of the mixing pipe second end of the mixing pipe automatic flap return line bypass line pigment paste non-solids mixture acid

Claims

Patent claims 1. Treatment system (100) for treating workpieces, in particular coating, for example dip painting, vehicle bodies, wherein the treatment system (100) has a main conveying direction (102) and comprises the following: at least one treatment zone (104) with at least one treatment tank (108), in particular at least one dip tank (110), for treating the workpieces with at least one treatment fluid, in particular dip painting the workpieces with at least one paint;and at least one rinsing zone (106) with at least one rinsing basin (112) for rinsing the treated workpieces with a filtrate of the at least one treatment fluid, in particular an ultrafiltrate of the at least one treatment fluid, wherein the at least one rinsing zone (112) is arranged downstream of the at least one treatment zone (104) in the main conveying direction (102), and wherein the at least one treatment basin (108) of the treatment zone (104) is fluidly connected to at least one cooling circuit (124) for cooling at least a portion of the treatment fluid and / or at least one filtrate circuit (128), in particular at least one ultrafiltrate circuit (130), for producing the filtrate, in particular the ultrafiltrate, from the at least one treatment fluid and rinsing the treated workpieces with the filtrate, in particular the ultrafiltrate.; 2. Treatment plant (100) according to claim 1, characterized in that the at least one treatment basin (108) of the treatment zone (104) is further fluidically connected to at least one circulation circuit (126) for circulating at least a portion of the treatment fluid.

3. Treatment plant (100) according to claim 1 or 2, characterized in that the treatment tank (108) comprises an overflow area (118) for regulating a level of the treatment fluid in a main volume (122) of the treatment tank (108).

4. Treatment plant (100) according to one of claims 1 to 3, characterized in that the rinsing basin (112) is a spray rinsing basin (114) or an immersion rinsing basin (116).

5. Treatment plant (100) according to one of claims 1 to 4, characterized in that each circuit (124, 126, 128) comprises at least one pump device (132) and at least one filter device (134).

6. Treatment plant (100) according to one of claims 1 to 5, characterized in that the at least one cooling circuit (124) comprises at least one heat transfer device (136) for cooling the treatment fluid.

7. Treatment plant (100) according to one of claims 1 to 6, characterized in that the at least one rinsing basin (112) is integrated into the at least one filtrate circuit (128).

8. Treatment plant (100) according to one of claims 1 to 7, characterized in that the at least one filtrate circuit (128) comprises a collecting container (140) upstream of the at least one rinsing basin (112).

9. Treatment plant (100) according to one of claims 4 to 8, characterized in that the treatment plant (100) comprises at least one spray rinsing tank (114) and at least one immersion rinsing tank (116), wherein the spray rinsing tank (114) is arranged between the treatment tank (108) and the immersion rinsing tank (116) with respect to the main conveying direction (102).

10. Treatment plant (100) according to claim 9, characterized in that the filtrate can be conveyed in a cascade manner from rinsing basin (112) to rinsing basin (112) counter to the main conveying direction (102), wherein the filtrate can be fed to each rinsing basin (112) indirectly via a plurality of spray nozzles (144) and / or directly via a feed line (142) or an overflow (148).

11. Treatment plant (100) according to one of claims 1 to 10, characterized in that the treatment plant (100) comprises at least two, preferably three, immersion tanks (110) arranged parallel to one another, wherein a The longitudinal extent of the dipping basins (110) is aligned transversely to the main conveying direction (102), and wherein the workpieces can be conveyed into the dipping basins (110) transversely to the main conveying direction (102) and / or out of the dipping basins (110) transversely to the main conveying direction (110).

12. Treatment plant (100) according to claim 11, characterized in that the filtrate circuit (128) of each immersion tank (110) has a shut-off valve (158) upstream of the collecting tank (140).

13. Treatment plant (100) according to claim 11 or 12, characterized in that the treatment fluids conducted in the circulation circuits (126) of the immersion tanks (110) can be mixed in a common mixing pipe (160) with at least one pipe section (162).

14. Treatment plant (100) according to one of claims 11 to 13, characterized in that a bypass line (172) is provided in each of the circulation circuits (126) of the immersion tanks (110).

15. A method for treating workpieces, in particular coating, for example dip painting, vehicle bodies, the method comprising the following steps: Treating workpieces in at least one, preferably three, parallel dip tanks (110) of a treatment zone (104) with treatment fluid, each workpiece preferably being treated in only one dip tank (110); Spray rinsing the treated workpieces in at least one spray rinsing tank (114) of a rinsing zone (106); and Immersion rinsing of the treated and spray-rinsed workpieces in at least one immersion rinsing tank (116) of the rinsing zone (106), wherein a portion of the treatment fluid of each immersion tank (110) is cooled in a separate cooling circuit (124) by means of a heat transfer device (136), and wherein ultrafiltrate is produced from a further portion of the treatment fluid of each immersion tank (110) for the rinsing processes, which ultrafiltrate is returned in an ultrafiltrate circuit (130) from a common collecting container (140) in a cascade manner from the immersion rinsing tank (116) via the spray rinsing tank (114) to the immersion tanks (110).

16. The method according to claim 15, characterized in that a further part of the treatment fluid of each immersion tank (110) is guided in a separate circulation circuit (126) for flow generation and mixing.

17. The method according to claim 15 or 16, characterized in that the circulation circuits are operated in a bypass mode for circulating the treatment fluid of the respective immersion tank (110) and / or in a mixing mode for mixing the treatment fluids conducted in the circulation circuits (126) in a common mixing tube (160) with at least one tube section (162).

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