MXPA99008899A - Device for surface treatment by immersion - Google Patents

Abstract

The invention relates to a surface treatment device, especially for electrochemical coating followed by electrophoretic coating. The material to be processed is moved along one or several planes through coating receptacles. Said movement occurs by means of layered frame conveyors provided with brackets for trays upon which the material to be processed is placed. Horizontal electrodes protrude in between the braces for each level or into the area between trays. The trays are moved along said electrodes.

Description

DEVICE FOR THE TREATMENT BY IMMERSION OF SURFACES Description of the invention The invention relates to a device and a method for the treatment of surfaces in which the material to be treated is conducted through a bath and in this is treated chemically, galvanically and / or electrophoretically. The methods and devices of this nature serve to provide a surface whose technical and optical properties are adapted to the particular purpose of use in objects constituted at least partially by an electrically conductive material. This can be achieved by the chemical or electrochemical treatment of the surface, for example by chromatization of the surface of a metal workpiece as well as by the electrolytic or electrophoretic application of a coating layer. The known wet methods are very complex by virtue of the fact that the material to be treated must be conducted through a row of containers with the most diverse treatment liquids, for example cleansing agents, electrolytes and electrodeposition lacquers, arranged one after the other. This happens in a discontinuous way by means of the immersion of individual objects or portions of small pieces, or in installations of continuous treatment by means of conveyors that transport the material to be treated individually or, in the case of small pieces in row one after another of the immersion tank. in an immersion tub through a treatment line. For this purpose, it is suitable, for example, a conveyor that receives the material to be treated. A device of this type is known from German patent document 41 42 997. By virtue of the fact that in the case of the chemical treatment of surfaces as well as in the case of the electrolytic coating and the electrophoretic coating, it is a process that is a function of time, a certain interval of permanence of the material to be treated in the individual immersion vats is required, depending on the respective treatment agent and the material to be treated. This very different residence interval in each individual case defines the necessary treatment path and consequently the dimensions of the individual immersion tubs in the direction of transport in the case of a determined transport speed or passage. By virtue of the fact that only the large-sized material to be treated can be individually driven through the individual baths, and the small parts only with a limited pile-up height in order to obtain a homogeneous surface, the conventional installations are very complex and its throughput is relatively low. A particular problem lies in achieving a uniform surface treatment everywhere, for example galvanizing and / or lacquering the entire surface without defective spots. Such defective points occur particularly at the points of contact between the material to be treated and the means of transportation to transport the material to be treated through the individual baths. As a means of transport, in particular for small parts or bulk material, drums, but in part also conveyor belts, and for larger parts, special transport racks which are designed according to the configuration of the material to be treated and consequently are expensive. It is also possible to move medium and large parts through the individual immersion vessels with the help of a conveyor belt; however, in this case the pieces must be arranged one behind the other on the conveyor so that the treatment agent has access to its surface as much as possible. However, an arrangement of this kind on a plane goes hand in hand with the disadvantage that the throughput is considerably reduced compared to a transport on racks with parts arranged within certain limits on top of each other. ThereforeThe object of the invention is to improve the economy of known methods and devices without impairing the quality of the surface of the material to be treated. The solution to this task is based on the idea of multiplying the throughput in the individual immersion tanks at a given transport speed by driving the material to be treated at several superimposed levels through the individual immersion tanks. This can be done with the help of a movable stepped frame between whose steps, according to the same screen, several treatment elements are arranged, for example stationary electrodes or stationary nozzles, for treatment liquid or drying air. In this way, the material to be treated is passed in front of the stationary treatment elements with optimal access to its surface, and the throughput is increased according to the number of levels or steps of transportation. The method according to the invention further opens the possibility of effecting the application to the material to be treated from above and from below, for example by spraying it or blowing drying air. Additionally, a better distribution of the thickness of the layer is achieved by virtue of the electrodes being arranged linearly with respect to the material to be treated. In order to obtain a surface as uniform as possible without defective points, the material to be treated can be transposed within the bath or also between two baths, in order to expose contact points and make them accessible for the treatment agent. . The transposition can be effected by shaking, with the help of magnets or with the help of a rake whose fingers grip like a comb between the rods or lamellae of a support for the material to be treated, for example a grid. To carry out the method according to the invention, a device is particularly suitable in which the material to be treated is arranged placed or hung at several levels in a stepped frame of a conveyor, which drives the material to be treated through at least one container, for example an immersion container. The material to be treated preferably is on a grid and can be placed in the stepped frame by means of a supply conveyor, preferably a two-leg conveyor. In order to be able to feed the steps or individual levels of the frame, the stepped frame preferably comprises a vertically movable skate with support arms disposed at a distance from one another. In this way it is possible to bring the support arms one after the other to the transport plane for lifting and in this way take, for example, a grid of lamellas of the conveyor. For its part, the lift shoe can be driven on a horizontally movable frame carriage, which moves the frame through the respective cover container. Because during the loading the material to be treated arrives one after the other, that is to say, delayed in time to the bath by immersion, there are no disadvantages and especially no different residence intervals, if the material to be treated is without current (electrical) in this stage. In this way it is possible to introduce the material to be treated carefully to the bath by immersion, since in doing so it moves vertically downwards and remains immobile on its base due to its weight. The invention will now be explained in more detail on the basis of an embodiment shown in the drawing. In the drawing show: Figure 1 a plan view on a device according to the invention in schematic representation, Figure 2 a vertical longitudinal section through an immersion vessel of figure 1, figure 3 a sectional view cross section of figure 2, figure 4 a grid for transporting the material to be treated, figure 5 a section according to line IV-IV of figure 3, figure 6 a side elevational view of a transfer station, with a conveyor and a hook , Figure 7 shows a plan view on the hook of Figure 6, Figure 8 shows the side elevation of a transposition station, Figure 9 a grid placed as an electrode circuit, Figure 10 the amplified representation of a point. of contact of the grid, figure 11 a nacelle with two grids, and figure 12 a cut according to line XII-XII of figure 11.

The device substantially comprises an immersion vessel 1, a discharge station 2 with a withdrawal conveyor 3 and a transverse conveyor 4, a return rail 5, another transverse conveyor 6, and a loading station 7 with a supply conveyor 8 . The immersion container 1 is inside a stack 9 and is provided with electrodes 10 arranged in stationary form at several levels, one above the other. In their front faces, the immersion vessel 1 leaves free in each case an area 11, 12 for introducing and removing the material to be treated. There can be found in each case a bath by aspersion. A rail 13 extends along the immersion vessel 1 or next to the stack 9 in the longitudinal direction, on which several runners 15 which, viewed in cross section, are formed in the form of claws and each provided with an element 14, are guided. of drive. In the runners 15, lifting racks 16 or staggered, vertically movable are carried. These frames basically comprise a frame with two U-shaped rails 17 in which the driven rollers 18 mounted in bearing on the slide 15 attack. The horizontal support arms 19 for the racks 20 are attached to the rails 17.

The support surface of the grids 20 is constituted by individual rods or lamellas 21, for example with a serrated profile in the manner of a saw, as shown in detail in the German patent document 44 28 789. Figure 2 shows in FIG. simplified representation in a cross-sectional view from the left in figure 1 to the first lifting frame 16 either stepped, still not descending, and to the third lifting and stepped frame 16 fully submerged within the immersion vessel 1. In the immersion container 1 there is a transposition frame 22 with fingers 23 protruding in a comb-like manner, which are arranged in the same distribution as the rods or lamellas 21 of the grids 20 in the stepped frame 16 . With these fingers it is possible to lift and rearrange the material to be treated that rests on the rods or lamellas 21 of the grids 20, when on one side the rods 21 of the grids and on the other side the fingers 23 of the frame 22 of transposition are facing each other's gaps. When the lifting shoe 17 or the support arms 19 are lowered, the stationary fingers grip the material to be treated lying on the grids 20 below, so that it is possible, with the aid of the stepped frame, to move the grids laterally a small stretch without the material to be treated. If now the lifting frame is raised again and the supporting arms 19 and the grids 20 return to their previous position, then the material to be treated is again on the grids, but nevertheless with other contact points on the lamellae Sawtooth. When loading the staggered frames 16, the grids 20 supplied by the conveyor 8 are gradually placed on the support arms 19, while the stepped frame 16 moves step by step upwards to the feeding area. In this the support arms in each case come to rest under a grid that is on the conveyor, and in the next step of the movement they lift it from the conveyor, while the conveyor moves forward along the width of a pallet. and take the next grid to a transfer position. As soon as all of the support arms 19 are occupied with grids, the slide 15 leads to the stepped frame 16 on the immersion vessel. After the descent and the immersion of the stepped frame which is joined thereto, the skate 15 leads to the stepped frame 16 passing it in front of the electrodes 10 to the transposition station. There the stepped frame remains as long as is necessary to lift the material to be treated with the help of the fingers 23 of the lifting frame 22. As soon as this happens, the skate 15 moves to the chassis 16 stepped by a small stretch, which is less than the distance between two horizontal rods 21, after which the lifting frame 22 again lowers the fingers 23, whereby the fingers return to place the material to be treated on the rods of the grids. By virtue of the relative movement between the material to be treated on the fingers 23 and the pallet, new support points are thus created, so that the previous support points are accessible for immersion bathing. After transposition the skate 15 again leads to the stepped frame 16 in its submerged position by passing it in front of the electrodes 10 to the other end of the immersion vessel 1 and, after an elevation, to the withdrawal area 12. There the stepped frame 16 moves step by step downwards by the distance of the support arms 19, whereby the grids 20 are placed on the withdrawal conveyor 3 when the support arms 19 are submerged in the conveyor 3.

A withdrawal hook 24 brings the material to be treated to other grids for the next treatment step, which may be a rinsing station followed by, for example, a chromatization step and a station for the electrophoretic coating with anodes soluble or insoluble. These stations differ from the stations for the galvanic coating represented in FIGS. 1 to 7 basically only by the fact that a material for anodic or cathodic coating is found in the respective immersion vessel. However, the coating station can also consist of a device as described in the German patent application 44 28 789, the content of which forms an integral part of this description. Because this device also works with grids or pallets, it is only necessary to transpose the material to be treated to these grids or pallets, so that during the transition from one stage of the process to the next stage of the process is not required a deployment of personnel. For transpose, a hook 24 is arranged between a horizontal rack conveyor 25 and the loading station of the next dip container. The hook 24 has a drive not shown and can be moved on rails 26 in the longitudinal direction of the conveyor, between the conveyor 25 and the immersion vessel; it is equipped with two spindles 27 driven on which are arranged opposite one another, bridges 28 with support arms 29. The bridges 28 move closer to one another as the spindles 27 rotate, and grab the material to be treated from a grid 20 that is in each case on a lifting table 30 arranged in extension of the conveyor 25. When descending the table The support arms take the material to be treated from the grid 20. By lateral displacement of the longitudinal shoe 28 the material to be treated is taken to the next stage of the treatment above a grid 31, which is also on a lifting table integrated in a conveyor. When the lifting table is raised, the grid 31 takes the material to be treated from the support arms 29 of the hook 24. When the hook is opened, with the subsequent lowering of the lifting table the grid arrives on the conveyor and from there to a frame stepped from the next immersion vessel in the manner described in connection with FIG. 1, or also to an aerial conveyor according to German patent application 44 28 789. The grid is then taken by those support arms of the stepped frame which is located at feeding side of the immersion vessel, which are placed a little below the plane of movement of the grid. When the stepped frame is raised a small distance, the corresponding support arms take the grid 20 of the conveyor coming from the hook. In order to be able to circuit the grids 20 as electrodes, they are provided with at least one contact chamber 32. The contact chambers 32 are open downwards and contain contact sockets 33 also open downwards into which the contact pins 34 which are on the support arms 19 of the stepped frames 16 fit. The contact pins have a conical tip 35 which creates a contact in a linear fashion with the inner edge of the contact socket. In this way, the grid 20 is put in circuit as an electrode with the material to be treated, which rests on the tips of the lamellae 21. By virtue of the fact that the coating agent solution only penetrates a little inside the contact chamber, there is a danger that the contact pins and the contact sockets will also be covered, thus losing the electrical contact. The material to be treated can also be conducted through the immersion vessel with the aid of an overhead conveyor as described in German patent application No. 44 28 789. For this purpose, a nacelle 36 provided with spigots 37 is used which houses two grids 38, 39. In this case, it is a galvanizing grid 38 and a lacquering grid 39 which precisely fit one into the other. The galvanizing grid 38 is insulated with respect to the nacelle 36 and therefore is not exposed to the danger of being coated. After lacquering the galvanizing grid is removed from the centering pins 37 by pulling it upwards, and the material to be treated is transferred back to the galvanizing grid. It is not necessary that the grids are provided with sawtooth lamellae; other support elements that ensure a contact area as small as possible with the material to be treated also come into consideration. The most convenient is a substantially tip-shaped contact. The great economy of the method according to the invention is due in the first place to the fact that the expense in personnel is very reduced, and that in comparison with methods that operate in a single level of transportation with conventional transportation devices for the material to be treated, the throughput is substantially higher. To this we must add a high quality of the surface due to the good access that the treatment agent has to the material to be treated. The invention is particularly suitable for an electrochemical treatment, for example to apply a layer of zinc, zinc / iron or zinc / nickel, which is then hardened if after electroplating follows an electrophoretic coating. In this way it is possible to provide a metal / lacquer coating on the surfaces very economically.

Claims (13)

1. CLAIMS A device for treating surfaces comprising an immersion vessel with treatment elements arranged in a stationary manner, and a stepped submersible transportation frame which guides the material to be treated in several levels superimposed through the immersion vessel, passing it in front of the elements of treatment that protrude between the steps of the stepped transport frame.
2. Device in accordance with the claim 1, characterized in that stationary treatment elements protrude between the steps of the transportation frame.
3. Device according to claim 1 or 2, characterized in that the stepped frame is constituted by a vertically movable lifting shoe with support arms disposed at a distance from one another.
4. Device in accordance with the claim 2, characterized in that the lifting shoe is driven in a horizontally movable shoe.
5. Device according to one of claims 1 to 4, characterized in that the treatment elements are constituted by electrodes, and that the steps are placed in circuit as electrodes.
6. Device according to one of Claims 1 to 5, characterized by an immersion vessel with cantilevered projection electrodes disposed at a vertical distance from one another.
7. Device according to one of claims 1 to 6, characterized by supports for the material to be treated in the form of grids having rods.
8. 8. Device in accordance with the claim 7, characterized in that the grids are provided with open contact chambers downwards.
9. 9. Device in accordance with the claim 8, characterized in that contact pins fit into the contact chambers.
10. 10. Device in accordance with the claim 9, characterized in that the contact pins are in contact with contact sockets within the contact chambers.
11. Device according to one of Claims 7 to 10, characterized in that a transpositional frame is placed in the immersion vessel with projecting fingers, the distribution and spacing of which corresponds to the distribution and to the spacing of the rods of all the grids arranged in a stepped frame.
12. Method for surface treatment, characterized in that - the material to be treated is arranged on a movable stepped frame, and moves through a treatment area with treatment elements intervening between the steps at several levels.
13. 13. Method according to claim 12, characterized in that the material to be treated moves through an electrolyte. Method according to claim 13, characterized in that after the electrolytic treatment the material to be treated is electrophoretically coated. Method according to one of claims 12 to 14, characterized in that the material to be treated is transposed during the travel through the immersion vessel. Method according to one of claims 12 to 14, characterized in that the material to be treated is traversed between two paths.