DESCRIPTION

The present invention relates to an electrical connection device in an anodisation process.

As known, generally almost all aluminium alloys behave well during the anodisation process, even if the type of moulding treatment used influences the micro-structure of the surface layers and therefore also the result of anodisation. The principal effect of the alloy elements appears in the surface finish, a direct consequent of the chemical interactions which occur in the oxide - electrolyte interface.

In the known anodisation processes, the necessary current density is generally determined directly and consequently the voltage applied, in order to have a better control of the coating speed.

Different alloys require different voltages to circulate the same current density.

The current required per unit of thickness of the film depends principally on the effect of the alloy elements on the conductivity of the layer itself.

anodisation also requires a high degree of cleanness of the surface to be treated, since residues of processing oils or greases, but also only fingerprints from handling, diminish the efficacy of the electrolyte solution and produce irregular surfaces.

In the anodisation process, the phase and type of anchoring of the object to be treated on special supports, which have the dual function of mechanical support and electrical contact, is extremely important. The choice of anchoring type is restricted by many factors.

In the first place, it is necessary to guarantee the mechanical resistance of the structure, which is in very drastic conditions during operation.

The electrolyte solution is, in fact, very aggressive on most construction metals and the choice of materials with which to construct the supports is therefore restricted by these two considerations.

Furthermore, the support structure must not absorb too much current to the detriment of the articles, at the same time guaranteeing a good electrical contact. The contact points must be chosen carefully, generally in invisible zones, since the anodic coating will not extend in those zones.

The quantity of contact points depends, in the first place, on the need to maintain blocking during the entire treatment, but also on the consideration that, as the contact points increase, the possibility increases of transmitting the necessary current to the pieces to be treated, i.e. of improving the quality of the electrical connection, due to the possibility of dividing the total current between the various contact points and therefore lowering the precise value of the current which transits from the single contact point.

The supports must also guarantee sufficient space between the articles to allow correct circulation of the electrolyte.

Particular problems during the oxidation process occur in the case of long and hollow moulds, such as aluminium profiles with a closed contour.

In fact, arrangement of the electric field inside the cross-section of the profile is such as not to favour internal anodisation. In the case of hollow moulds with more complex geometries, it is necessary to use additional cathodes positioned in key points of said cavities.

When the coating thickness reaches the desired value, there is often a porosity sealing phase, obtained by means of immersion in hot water or steam, which hydrates the surface alumina.

The effect of this operation is making the surface more compact and uniform, making it impermeable and guaranteeing a longer duration and better surface appearance. The sealing operation may also be preceded by a colouring phase by means of pigments dispersed in the organic phase.

Automation of the industrial process therefore passes through a processing cycle which may be broken down into three principal phases.

Cleaning, which comprises all the sub-phases of basic and/or acidic washing, followed by the respective rinses in hot or cold water.

Anodisation, which normally operates with sulphuric acid in a concentration of 180÷220g/litre, 16-÷20V, at a temperature of 20÷30°C; usually, this coating is later coloured with organic products or depositing of metals and offers a wide range of applications.

The final process is sealing, which may be preceded by electro colouring.

As may be easily understood in light of what is indicated above, in plants which use the anodisation process, such as those for painting and treatment of aluminium profiles, there is low productivity, particularly due to transfer of the profiles and application of the optimal electrical contacts for performance of oxidation.

Furthermore, in processes of the known type, there is also a rapid deterioration of the support and electrical transmission materials for performance of the anodisation process.

In the case of flexible profiles, typically profiles with a reduced transversal cross- section, in processes of the known type electrical transmission involves a particular type and method of electrical contacts and support of the profiles is also necessary by means of intermediate supports positioned along said profiles and which are added to the attachment points of the profiles formed by the electrical contacts, with further wasting of time which negatively influences productivity of the entire profiled element surface treatment plant.

It must also be taken into account that in processes of the known type, on arrival of the articles to be treated, said articles are divided by shape and dimensions, with the purposes of standardising the process and electrical transmission parameters as much as possible with a further decline of productivity.

Therefore, the technical task proposed by the present invention is to create an electrical connection device in an anodisation process that eliminates the drawbacks of the prior art mentioned above.

Within the scope of this task, one object of the invention is to realize an electrical connection device in an anodisation process that is easily and rapidly activated independently of the open or closed shape and the dimensions of the element to be treated.

Another object of the present invention is to realize an electrical connection device in an oxidation process that is protected against the attack of the oxidation bath and does not reduce productivity of the painting or other type of treatment plant with which it is associated.

A further object of the present invention is to realize an electrical connection device in an anodisation process that allows automatic creation of optimal electrical contacts for any type and shape of profiled element.

The technical task, as well as these and other objects, according to the present invention, is obtained by providing an electrical connection device in an anodisation process comprising an oxidation tank inside which are placed the elements to be anodised and at least a first and at least a second electrical contact adapted to be engaged with a part of said elements, characterised in that it comprises movement means for the relative movement of said at least first contact and/or said at least second contact for their electrical connection with said elements to be anodised.

The characteristics described in the dependent claims also contribute to achievement of the task and the objects of the present invention.

Further characteristics and advantages of the invention will become more apparent from the description of some preferred, but not exclusive, embodiments of an electrical connection device in an anodisation process, in which:

figure 1 shows a perspective view of the electrical connection device in an anodisation process according to the invention; and

figure 2 shows a partial view from above of the first and second contact of the electrical connection device in an anodisation process.

The electrical connection device in an anodisation process according to the invention, indicated in its entirety by reference number 1, comprises an oxidation tank 2 of the elements to be anodised of any shape and dimension such as, preferably but not necessarily, aluminium profiles 3.

The profiles 3 may have an open profile or a closed profile, as shown in fig.2, and are retained during their transfer, for example by an aerial transport line not shown, or by hooks 4.

Consequently, in an anodisation tank 2 several profiles 3 of the same or different shape are simultaneously present, due to the fact that the electrical contacts automatically adapt to their geometry.

The device further comprises at least a first and at least a second electrical contact, generically indicated with 5 and 6, adapted to be engaged with an upper part of the profiles 3 which is not immersed in the oxidation bath and by means of which the profiles are connected to their translation hooks 4.

Advantageously, the device has movement means, indicated in their entirety by the reference number 20, for relative movement of the first contact 5 and/or the second contact 6 so as to allow their automatic electrical connection with the profiles 3 present in the tank 2 independently of their geometry.

In greater detail, the first electrical contact 5 is static and has a higher width than the width of each of the profiles 3 and, preferably, develops continuously .

The second electrical contact 6 is dynamic and has a lower width than the width of the profiles 3 so as to engage in an optimal way with one or more parts of their surface, independently of their shape and dimensions.

Thus, between the profiles 3 and electrical contacts 5 and 6 at least 2 contact points are always obtained and a good electrical connection of the profiles 3 is therefore guaranteed independently of their shape and dimensions.

The second contact 6 is formed of a plurality of independent bodies 7 and each activated singly by a pneumatic cylinder 8 forming part of the movement means 20.

The independent bodies 7 all have the same width and a constant spacing step and each of them has above a conducting braid 9 of the electrical current which, when idle, i.e. when each independent body is not in contact with the profiled element 3, a substantially vertical position with a wide curving radius so that, even after numerous cycles in which the dynamic body advances and moves backwards with respect to the profiled element 3, the braids are not subject to breakage or fraying due to yield of the material.

The cost of maintenance and replacement of the braids is thus greatly reduced. Opportunely, furthermore, below the braids 9, there is a first guide protection 10 thereof, which is also further back with respect to their mechanical connection 1 1 with the independent bodies 7.

The guide protection 10 has a flat part 12 having a portion 13 inclined and turned towards the braids and a wall 14 orthogonal with respect to the flat protection part 12 of the pneumatic cylinders 8.

The device 1 is also equipped with a second covering protection 15 of the mechanical connection 11.

In particular, the second covering protection 15 comprises a plurality of L-shaped blades 16 each of which is associated to each independent body 7 for total protection of the mechanical connection 11 and partial protection of the conducting braids 9 .

Advantageously, the pneumatic cylinders 8 are also arranged behind and below the first guide protection 10 and as close as possible to the barycentre of said independent bodies so as to offer, in addition to the mechanical advantage of reducing force and friction, also of moving into a protected and easily accessible position the entire pneumatic part, making maintenance and cleaning of the components much easier.

The device 1 also comprises a support 18 for guiding the independent bodies 7 during their movement from and towards the first static electrical contact 5 to contrast their bending moment.

The electrical connection device in an anodisation process according to the invention thus conceived is susceptible to numerous modifications and variants, all of which falling within the scope of the inventive concept. Moreover, all details may be replaced with other technically equivalent elements.

The materials used, as well as the dimensions, may in practice be of any type, according to needs and the state of the art.