Patent Application
20120037494
The present invention belongs to the field of the treatment of surfaces of parts by immerging these parts in successive liquids contained in several treatment tanks and by transfer of the parts between these tanks, for example the electrochemical treatments of aluminum parts. As examples of such electrochemical treatments, the barrier anodizing or anodic passivation, the porous anodizing in acidic medium, the anodic dissolution, the hard or self-coloring anodizing, the electrolytic polishing and also electroplating such as nickel plating may be cited. The treating liquids may not only comprise electrolytes but also pre-treating liquids such as degreasing liquids, coloration liquids and rinsing liquids.
More particularly, the present invention provides an installation for the continuous surface treatment by immerging said parts in at least one treating liquid contained in a treatment tank, said installation including a plurality of tanks disposed in series, and a device for transferring the parts between the tanks, said tanks each comprising a rotary structure mounted on a rotation axle and able to receive said parts, the parts being immerged in said treatment liquid by a rotary movement of the rotary structure of the treatment tank selected in such a manner that air bubbles that may be formed during the immersion of said parts, are chased away from the surfaces of said parts.
The widest used installations for the treatment of the surface of aluminum parts are operated batchwise, i.e. by charges of a great volume. The document DE 2 119 401 describes the example of such an installation that comprises motorized carriages which move above several treatment tanks. The carriages are equipped with mobile arms for effecting vertical movements with large strokes for immerging important charges of objects to be treated and hanging from the mobile carriage, into successive tanks and to withdraw them therefrom. This kind of installation has several drawbacks:
As a result, such treatment units can only be installed within a chemical plant that is specialized in surface treatments and processing and can therefore respect severe environmental security standards. The parts must thus be transported from the metallurgical factory where they were machined, to the factory where the surface treatment is effected, and then to the end user; high costs for packaging and transportation will have to be incurred.
In the international patent application No. WO 2006/084973 whose disclosure is incorporated into the present document by reference, the Applicant has already described an installation for the continuous surface treatment of parts, formed by a plurality of treatment tanks which each are equipped with a motorized rotary drum and whose axle of rotation is disposed horizontally in such a manner that the major portion of the drum is immerged in a treatment liquid contained in the corresponding tank. The parts to be treated, in particular when they are small, can before be put in place as small batches on supports that have the shape of boxes, for example those described in the patent application No. EP-A1-1 433 537 in the name of the Applicant, and these boxes are then transported by a conveyor system destined to feed each tank with parts to be treated and to transport the already treated parts downstream. The conveyor system has two parallel conveyor chains disposed on both sides of the upper portion of the tanks, the drum axes being disposed perpendicularly with respect to the two conveyor chains. Each tank is equipped with a device that transfers the boxes, one after the other, by means of a hydraulic cylinder by a horizontal push perpendicularly with respect to the axes of the conveyor chains, alternatively from one conveyor chain to the other, after the passage through the tank where they are temporarily fastened on slide rails disposed at the periphery of the rotary drum and where they undergo one or more rotations in the treatment liquid. Each rotary drum is driven via a cogwheel on the shaft of its motor which meshes with the periphery of a toothed disk or with a succession of pins disposed between two disks, these disks constituting a terminal face of the drum. The gear point is situated above the level of the liquid contained in the tank. The drums are supplied with electric current through these disks by means of sliding contact shoes which bear against these disks and are disposed in the tank above the level of the treatment liquid, in the manner described in the patent application No. WO 2007/122471 in the name of the Applicant. The current is then transmitted by the drum to the supports of the parts and then to the parts to be treated.
The rotations of the parts within the treating liquids eliminate the air bubbles or pockets from the surface of the parts and allow to obtain an excellent surface quality. The elimination of vertical displacements of the parts in an appreciable extent above the tanks reduces the overall space requirement of the installation and the formation of droplets and vapors and allows therefore to reduce the power of the air filtration systems in the treatment unit. However, since each tank constitutes an autonomous treatment sub-unit with its motorized drum and its transfer device, that installation uses a conveyor system and a transfer system that are relatively complicated, requiring an excellent synchronization of all these components. The installation also requires a driving device for each conveyor chain and several devices for the transfer between the chains and the tanks, and the costs of these devices is not negligible.
According to patent application No. WO 2008/035199 whose contents are incorporated into the present document by reference, the Applicant has described an installation for the continuous surface treatment of parts of the above depicted kind and composed of tanks containing motorized rotary drums that are similar to those described in the document No. WO 2006/084973, and regarding the tanks effecting an electrochemical treatment step as such, it comprises an electric supply system similar to that which is described in the document No. WO 2007/122471. Each tank, with its motorized drum, constitutes therefore only an autonomous sub-unit of the installation and mechanically independent from the other tanks. However, this installation uses a unique conveyor chain destined to supply each tank with parts to be treated, to collect the already treated parts and to transfer them into the next treatment station. The conveying of the parts is effected horizontally and parallel to the drum axes. The conveyor chain comprises horizontal transfer slide rails disposed between the tanks to which the slide rails of the rotary drums become to be aligned when the latter come to their uppermost position which emerges from the treatment liquid. Motorized carriages disposed above these slide rails make reciprocating movements on one guide rail that is parallel to the axes. Each carriage is equipped with an articulated rocker bar system comprising vertical arms allowing to push the boxes that are in their upper position and to drive them at each reciprocating cycle lengthwise on the slide rails of the drums and on the transfer slide rails. In this installation, it is intended to realize a rinsing of the parts by jets when they are positioned on a transfer slide rail between two tanks and/or after the last tank.
This installation has the same advantages as that which is described in the document No. WO 2006/084973 and simplifies the construction of the conveyor system. However, it uses as many driving motors as drums and at least as many articulated carriages as tanks, and the costs of these devices is not negligible. The installation also requires an excellent synchronization of the components since all displacements must be operated in a clocked manner.
It can be observed that, in the two installations mentioned above, the electric contact plots which are of graphite are wearing parts which are situated in the very interior of the electrolytic treatment tank, and that the contact zones of a drum disk with electric supply and with mechanical drives are exposed to treatment liquids, some of them being corrosive. It may also be noted that each driving motor of a drum is situated near the latter and adjacent to the upper opening of the tank and thus to the surface of the liquid which is contained therein. The cabinet of the motor is therefore exposed to vapors, in particular to corrosive vapors emerging from this tank. Maintenance costs must thus be incurred, in particular the replacement of contact parts and motor parts, and these costs are not negligible.
In the two installations for a continuous treatment described above, the conveyor chain transports the treated parts after the last rinsing step into a drying tunnel disposed downstream in these installations. The air coming from the drying tunnel is conducted into the air filtering system of the surface treating plant.
A first object of the present invention is to provide an installation of the kind defined above wherein the synchronization of the displacement of the parts can easier be realized.
Another object of the present invention is to provide an installation wherein the maintenance costs of the devices for realizing the supply with electric power to the parts to be treated as well as of the devices for rotating the part in the tanks are minimized.
A third object of the present invention is to provide an installation, especially an installation for anodizing aluminum parts, which can be run within a plant for the manufacture and machining of metal parts that is not yet equipped with devices for the treatment of effluents corresponding to standards required by a plant for electrochemical treatments.
A first object of the invention is a machine for the surface treatment of metallic parts by the immersion of said parts into at least one treatment liquid contained in a treatment tank, said machine including a plurality of tanks arranged in series, and a transfer device for the transfer of the parts between said tanks, said tanks each comprising a rotary structure mounted on a rotation axle and capable of receiving said parts, said parts being immerged in said treatment liquid by a rotational movement of the rotary structure of the treatment tank, selected in such a manner that air bubbles that may be formed during the immersion of said parts, are chased away from the surfaces of said parts, wherein said rotation axles of said rotary structures in the series of tanks of this machine are in rotary interlock condition and are driven by a common driving device.
The rotary coupling of the axles of the rotary structures and their drive by a unique device eliminates the difficulties of a synchronization of the movements of the rotary structures.
The invention has also as another object an installation for the surface treatment of metallic parts, comprising the machine having the above indicated characteristics, lodged in a container containing confinement a and retreating means for the fluids flowing out of said machine. Consequently, the container is a treatment unit that can be installed and operated within a plant that is not specialized for surface treatments.
In the machine according to the invention, the tanks in series may be contiguous. The rotation axles of said rotary structures of the tanks may be aligned and assembled in a manner to form a common rotation shaft or axle that traverses the whole machine.
In the machine according to the invention, the common driving device may be realized by means of an electric motor that drives directly the common rotary shaft or its segments that are put together with rotary interlocking by coupling. This driving motor may be disposed at a first extremity of the tanks series, especially at the downstream end.
Preferably, the rotary structure of the treatment tank which is intended to realize an electrochemical treatment step is connected to an electric generator via the rotation axle of the treatment tank, and said rotation axle of said treatment tank is electrically insulated from other segments of the machine axle. According to a mode of realization, the connection is implemented by means of a rotary connector which is mounted on said rotation axle of the treatment tank. According to a particular realization mode, the rotary connector is placed at a second extremity of the tank series.
In an installation according to the invention, where the common driving device, in particular the electric motor driving the axle of the rotary structures and/or the electric connector mounted on this axle, are disposed at the end portions of this axle, the lengths of these terminal portions may be selected such that they traverse the walls of the container in such a manner that the driving device or devices and/or the electric connection device will be placed outside the container. In such a configuration, these devices are not in contact with corrosive vapors, the frequency of replacement of parts is reduced and the maintenance of the devices is rendered easier.
If the machine according to the invention uses supports for holding the parts to be treated, for example supports in the form of boxes, said rotary structures are equipped with retaining devices capable of temporarily retaining these supports during the rotation movements of said rotary structures and capable of allowing a transfer movement of the supports between two rotation movements, the dimensions of said supports being adapted to said retaining device. Said supports have in turn fastening means adapted for holding and fixing said parts on said supports during said whole surface treatment.
According to a preferred realization mode, said retaining devices comprise slide rails which are parallel to the axles of said rotary structures, and each rotary structure of a tank is aligned with a rotary structure situated respectively immediately upstream and/or downstream, so as to allow the transfer of said supports over a tank and from one tank to the next one by sliding along said slide rails, under the action of transfer means.
The machine according to the invention comprises a transfer device disposed above the tanks and synchronized with the driving device of the machine axle, equipped with grasping elements for the supports which are in their upper position on said rotary structures, said transfer device effecting a simultaneous transfer movement of said supports in high position, each support in high position taking, under the influence of the transfer movement, the emplacement that was occupied before said transfer movement by the support in its high position immediately downstream.
According to a realization mode, said grasping elements comprise a pivoting shaft which extends over the series of tanks, and a group of arms mounted on said shaft, each arm bearing at its free end two pins distant and perpendicular with respect to the arm, the distance between these two pins of the same arm corresponding to the distance that separates two successive supports in upper position, the distance between two arms corresponding to the length of one said support. Preferably, the length of the arms is adjustable, and the height of the pins is also adjustable.
Preferably, the transfer device includes means for an alternating displacement between upstream and downstream of said grasping elements, and a particular realization mode comprises a group constituted by a driving pinion and a toothed rack, said pinion being fastened to a frame and a slide rail and meshing with said toothed rack that is fastened to a slider block, the stroke of said means for an alternating displacement being equal to the distance between two successive emplacements of the supports in high position.
The transfer device comprises also means for releasing said grasping elements which, according to a realization mode, include a motorized unit formed by a connecting rod and a crank for acting on said pivoting shaft in order to simultaneously activate and simultaneously release said grasping elements of all supports in upper position.
A particular object of the invention is a machine that is defined as described above and is destined for anodizing aluminum parts, comprising from upstream to downstream:
Another, particular object of this invention is a machine that is defined as described above and is destined for the electrolytic nickel plating of steel parts, including from upstream to downstream:
In these machines, the rinsing tank may have compartments between its upstream and downstream portion, realized by one or more transverse separating walls, traversed by the rotation axle of said rinsing tank, said rotation axle bearing a rotary structure in each compartment. The downstream compartment has an entry opening for its supply with fresh rinsing liquid, and the upstream compartment has an exit opening for the used rinsing liquid, and the separation walls have a passage for the rinsing liquid. These passages may take the form of overflow openings installed in the upper portions of these transverse separations.
In the installation according to this invention, the bottom of the container forms a storage basin for liquids. The capacity of the storage basin may be selected such as to be able to receive the totality of the volume of the liquids contained in the machine.
Preferably, the container contains a reservoir for the treatment liquid, a reservoir for the used treatment liquid, and a reservoir for used rinsing liquid.
Preferably, a device for retreating the used treatment and rinsing liquids is lodged within the container. According to a realization mode, the device for the retreatment of used liquids is an evaporator which retreats these used liquids by distillation and condensation.
Preferably, the container includes a gas scrubbing station. Especially a station for washing gases, connected to a water circuit and disposed in the space above the tanks.
Other characteristics and advantages of the invention will become evident to the one skilled in the art from the following description of a realization mode that is only given by way of non limiting example, and with reference to the attached drawings wherein:
To
The treatment machine 1 comprises a group 100 of tanks, a group of rotary structures 800, and a transfer device 200. As can be seen in
The axle segment 810 of the electrolytic treatment tank 101 is connected to the axle segment 820 of the rinsing tank 102 through an element made of an electrically insulating material. This axle segment 810 bears at its other extremity that goes beyond the upstream wall of the electrolytic treatment tank, this axle segment 810 bearing a rotary connector 804 comprising three rolls which rotate in the interior and are in contact with a contact cylinder 806 which is connected to the rectifier block 705 that constitutes the device for supply with direct current.
As can be seen in
In the electrolytic treatment tank 101 as shown in
In the warming tank shown in
The slide rails bear resilient contact plots 813 whose positions and distances correspond to the length of the supporting boxes 850, 851 and to the compartments 108, 109, 110 of the rinsing tank 102, thus allowing to withhold said supporting boxes at a predetermined longitudinal position on the slide rails during the rotation movements, and the sliding of the supporting boxes is allowed under the action of the transfer device between two rotation movements only.
The machine according to the invention comprises a transfer device 200 whose mounting position above the series of tanks 100 is shown in
As it is shown in
As it is shown in
The transfer device 200 comprises also a system for the release of said grasping elements, including a driving motor 210 driving a unique group 209 composed of a connecting rod and a crank, this latter driving the alternating pivoting of the shaft 201 and thus of the arms 202, 205, and this swinging motion engages and disengages simultaneously the pins 203, 204 of all supporting boxes that are in high position and allows the rotary structure 800 to rotate. The arms 202 will pivot between a lowered position near to the horizontal plane and a heightened position. The shaft 201, the slider block 207 and the slide rail 208 are thus parallel with the supporting boxes but laterally offset with respect to the slide rail pairs in high position. When the grasping system is in its heightened position, the transfer device makes a translation of the shaft 201 in upstream direction thanks to the system of pinion and rack, and it will take the former position for the following transfer movement.
In a method for anodizing in using the treatment machine 1 that has been described above, the electrolytic treatment tank 101 is filled for example with a sulfuric acid solution and allows to realize the anodizing of aluminum parts attached to supporting boxes. For this kind of treatment, the tank 101 comprises two metal plates that form the cathode and are disposed on both sides of the rotary structure 801 near the lateral walls of the tank, the rotary structure being supplied with an electric current having the opposed polarity with respect to the electrodes, said electric current being transmitted to the parts to be treated via, successively, the axle 810, the transverse plates 807, 808, the slide rails 809, 811 and the supporting boxes 850. During the implementation of the method in the treatment installation according to the invention, each part is immerged in the tank 101 by having it undergo, according to the realization mode shown in the Figures, four complete revolutions in such a manner that air bubbles and air pouches which may be formed in the interior of the tank in contact with the parts, are eliminated, thus allowing the treatment liquid to integrally treat the surface of the parts and rendering the treatment perfectly homogeneous.
Thus, the supporting boxes which hold the parts not yet treated, brought about by the conveyor chain 706, are engaged by horizontal displacement at the upstream extremity of the pair of slide rails not immerged and situated momentarily at the summit of the rotary structure 801, each supporting box being positioned lengthwise on the upper pair of slide rails thanks to the transfer device 200 which cooperates with the resilient contact devices 813 of the pair of slide rails. The totality of the treatment machine shown in
At each sequence, namely after every rotation by 90° , one supporting box containing parts that have been treated by electrolysis, is transferred from the electrolytic treatment tank 101 onto the rotary structure 802 of the first compartment 110 of the rinsing tank 102 and is then immerged into the rinsing liquid during the next rotation, in order to make a complete revolution. Then, it is transported into the second compartment 109, makes a rotation of 360° therein, and then passes into the third compartment 108 where it makes a final rotation of 360° before being transported into the warming tank 103. The rinsing tank is continuously supplied with rinsing liquid. This rinsing liquid enters first into the third compartment 103 of the rinsing tank, then flows into the second compartment 109 through the opening in the separation wall 107 between these two compartments, and then into the first compartment 110 before being evacuated into a storing tank for used liquid. The one skilled in the art will have understood that, thanks to this arrangement, the rinsing operation is executed as a kind of “countercurrent washing” according to the terminology of the field of chemical separations.
In the third tank 103 which contains a rotary structure 803 whose length is equivalent to two positions of the supporting boxes, these latter make two complete revolutions before being engaged by the transfer device 200 against the conveyor chain 709 downstream the installation. This warming tank does not contain any liquid but is traversed by a hot air flow supplied by the turbine 111, 112. Thanks to the rotation of the parts in the tank 103 with respect to the direction of the air flow, the droplets of the rinsing liquid are efficiently eliminated from the walls of the parts, even if the parts have cavities and hollow portions. Such a rotation is not provided in conventional drying tunnels.
The air that is charged with humidity and exits the drying tank 103, is collected and mixed with the air charged with vapors sucked off by the hood 401 disposed above the oxidation tank 101 and above the rinsing tank 102 and then treated in a block 402 containing a fan and a gas scrubber, installed within the container 701. The hourly aspiration capacity of the hood 401 and the fan and scrubber block 402 may be selected to be 2 to 8 times, typically 4 times, the inner volume of the container. This kind of apparatus is as such well known to the one skilled in the art of surface treatment. The air that exits from this gas collecting and scrubbing station 400 may be blown without any restriction into the surrounding atmosphere.
The water which exits from the gas scrubber is collected in an intermediate storage tank. This water is mixed with used rinsing liquids and retreated in the evaporator 300 which forms a small distillation-condensation unit. The distillate is recycled as a rinsing liquid. The residue that is composed of an acidic electrolyte solution is transferred to an intermediate storage tank and then mixed with fresh electrolyte.
The used electrolyte is also stored in an intermediate storage tank and then retreated in the evaporator; the distillate being combined with fresh electrolyte, and the distillation residue whose volume is small is stored for an external retreatment. Seen as a whole, the installation according to the invention only produces a small volume of rejections that cannot be treated in situ, and the installation can thus be used in a factory which does not have facilities of a plant for the electrochemical surface treatments.
Each supporting box that traverses the machine according to the invention makes a path that may globally be qualified as helical although it is in fact composed of a succession of rotations and translations. Furthermore, the path of each supporting box is composed of clocked sequences of these movements but the overall processing by treating a great number of supporting boxes should be considered as a continuous process. It is therefore possible to adjust the flow rate of the supplies of fluids, treatment liquids, rinsing liquids and air so as to operate an established continuous processing, the volumes and concentrations of the fluids in all tanks 100 of the series remaining constant. Therefore, the quality of the treated parts remains perfectly constant.
Furthermore, the quality of the air rejected by the gas scrubber installation remains also perfectly constant. The retreatment of the liquid effluents within the container can be executed as a continuous or a batchwise process thanks to the tanks 500, 600 that allow an intermediate storage.
The installation described above and whose group of tanks is illustrated in
The container of this installation, shown in
An installation according to the invention has been used for electrolytic nickel plating, namely an electroplating method but not a conversion method, of steel parts for motor car manufacture. The parts had been degreased before in a solvent.
In order to carry out this process, the installation uses 9 tanks comprising a total of 14 compartments:
The intensity of the electric current that is applied to the electrodes and the parts in the nickel plating tank is about 0.5 A/square decimeter. The nickel deposition formed on the surface of the parts presents an essentially constant thickness of 3 to 5 micrometers. The rate of rejection of defective parts is lower than 0.1%.
It will be noted that all rinsing tanks comprise two or three compartments for washing and rinsing the parts by countercurrent with the purpose of eliminating as completely as possible the residues of the active solutions in the treatment tank situated upstream and for avoiding a pollution of active solutions in the downstream treating tank.
a) Electrolytic treatments
Cathodic electrolytic coatings of:
Anodic transformations:
Paints:
Electrolytic polishing of stainless steels
b) Electroplating of plastics
c) Various chemical treatments such as:
Of course, the above listing of treatments is not exhaustive and is given as non-limiting examples only. The one skilled in the art will know how to adapt, for every concrete application, the number of tanks and of compartments of the machine as well as the equipment provided for the treatment of the effluents.
Of course, the invention is not limited to the realization modes that have been described above, but it comprises numerous technical variants and their combinations:
| Number | Date | Country | Kind |
|---|---|---|---|
| 09158977.0 | Apr 2009 | EP | regional |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/IB2010/051827 | 4/27/2010 | WO | 00 | 10/28/2011 |
