JP4505501B2 - Method and apparatus for galvanic electrocoating of metal items - Google Patents

Description

The present invention relates to a method and apparatus for the electrolytic deposition of a protective coating of metal items, typically screws and the like, with a zinc coating. Furthermore, it is obvious that simultaneously with such application, it is also applicable to other types of protective and / or decorative coatings with other metals and to any other kind of item. It will be mentioned in the future.

A conventional zinc coating apparatus consists essentially of an array of operation stations in which screws in a perforated barrel are protected through methods well known to those skilled in the art. It is known that various treatments necessary to obtain a coating can be performed. As an example, mention may be made of a plant with an operational capacity of 1800 kg / hour screw for a 12 μm thick zinc coating. Such a plant comprises the following phase / station arrangement:
-N. 2 Chemical cleaning station-N. 2 Washing station-N. 3 Acid Wash Station-N. 2 Washing station-N. 1 Electrochemical cleaning station (with 16V / 1000A rectifier)
-N. 2 Washing station-N. 12 Electrochemical zinc coating stations (with 16V / 1000A rectifiers each)
-N. 2 Washing station-N. 1 Neutralization station-N. 1 Blue Passivation Station-N. 1 Washing station-N. 1 Yellow Passivation Station-N. 1 Washing station-N. 1 Storage / Removal Station-N. 2 Drying station This is a plant with a total volume of about 40,000 liters of processing liquid and a length of over 40 m, with 34 stations.

With this conventional method and apparatus, by moving the barrel containing the item, the item moves from one station to another, so there are several significant drawbacks summarized below.
1. By transferring items in a barrel from one station to another, depending on the shape of the barrel itself, it may be necessary to purify due to very strong carry-over contamination from one station to another Large quantities of liquid will also be transferred, requiring large amounts of wash water and chemical products to be used to fill or empty the barrel with items.
2. The very large amounts of liquid and product required in the various phases of the process must be purified.
3. It is necessary to frequently analyze and confirm chemical solutions.
4. A large amount of highly contaminated liquid that constantly releases harmful vapors and poisonous gases outside the system must be purified.
5 occupies a very large space.
6. Very frequent machine maintenance is required to handle the plant system.
7. Labor is needed for storage / removal and phase management.
8. The plant, the accessories connected to the plant, and neighboring buildings deteriorate very quickly.

Accordingly, it is an object of the present invention to provide a method and apparatus that does not have the aforementioned drawbacks. The purpose of this is to use a centrifugal drum instead of a barrel, the processing phase and the next cleaning in the same station as the processing phase, and also the continuous processing before transferring the item to another station or at the same station. This is accomplished by using a method and apparatus for performing centrifugation prior to the phase.

The first major advantage of the present invention resides in the items being processed rather than moving the items to be processed from one chemical station to another using a bridge crane, and some of them in the same centrifuge The item remains as the liquid moves by filling and emptying the device with a hydraulic pump system during the treatment cycle. Therefore, by centrifuging between one process and another, the liquid can be completely regenerated by centrifugation, so that the internal chemical product and water consumption is very low.
A second important advantage is that there is a large carry-over contamination that causes contamination of the chemical solution that needs to be regenerated frequently between one phase and the other in the known method , or the process is accurate. While not implemented and this may result in waste of items, the new system is free of contamination thanks to the centrifugation of items between one chemical phase and another chemical phase, All this is not necessary.

  Yet another important advantage is a significant reduction in environmental impacts and lower plant costs, which is a complex and expensive solution given that there is no spent strength contaminated liquid outside the system. And an air purification system is not required.

Finally, a further advantage is that the space occupied by the plant is small due to the small number of stations and that the labor required is reduced by 100% automation of the storage and retrieval system for centrifugation. . As a comparison, it is conceivable to make a plant having the same operation capability as a conventional plant, the station described below is sufficient, and the total length is about 30 m.
-N. 1 Storage Station-N. 2 Chemical cleaning station-N. 3 Acid Wash Station-N. 1 Electrochemical cleaning station (with 16V / 1000A rectifier)
-N. 6 Electrochemical zinc coating station (each with 16V / 1000A rectifier)
-N. 1 Passivation station-N. 2 Drying station-N. 1 Extraction station

In short, the method and apparatus of the present invention allows less than 70% liquids and chemicals to operate automatically in a plant with fewer than 50% stations, without operators, with the same production capacity with very low environmental impact. Obtainable.

Additional advantages and characteristics of the method and apparatus of the present invention will be apparent to those skilled in the art from the following detailed description of embodiments thereof with reference to the accompanying drawings.

  1 and 2, it can be seen that the plant according to the invention consists of stations A arranged in a line for chemical and electrochemical processing, which is equipped with a rectifier R. The plant is provided with an automatic storage station L at the entrance, an automatic take-out station U at the exit, and two drying stations A ′ upstream of the automatic take-out station U.

  The item to be processed is stored in a cylindrical drum D (similar to a washing machine drum) with an open top and a hole, which is on the station throughout the plant length from storage station L to pick-up station U. It automatically moves from one station A to another station A using a carriage C running on the extending rail B.

  By using these open drums D instead of the traditional barrels closed by the door, the labor is greatly reduced without danger to the health of the operator, and the storage and retrieval of items in a fully automated manner It can be executed at the end station.

FIGS. 3 and 4 illustrate a part of building one of the aforementioned stations A, in particular one of the stations for the electrochemical zinc coating process.
Such a station has a centrifuge F which is closed by an upper lid E, in which a motor M 'rotates a drum D which is introduced vertically into the centrifuge F by one of the aforementioned air carriages C. Upon closing, the centrifuge F can be tilted about 45 ° about the axis X using the motor M while maintaining an electrical connection as well as a hydraulic connection to the rectifier R. In fact, the processing liquid is sent to the centrifuge F through the delivery pipe G and the drain pipe H, respectively, and is discharged from the centrifuge F. The delivery pipe G and the drain pipe H extend from the bottom of the centrifuge F to the hydraulic connector S. Concentrate on. The delivery pipe G comes from the upper tank T placed on the scaffold K at a high position with respect to the centrifuge F, while the drain pipe H is placed below the scaffold K at a position lower than the centrifuge F. It reaches the lower tank T ′.

  The two tanks T, T ′ are further connected hydraulically with the help of the pump P, which makes it possible to return the regenerated and purified liquid from the lower tank T ′ to the upper tank T. It becomes. Other pipes, pumps and valve means (not shown) are also provided for the delivery and discharge of the liquid in the two tanks.

In light of the above description, the method of the invention and the operation of a suitable apparatus are readily understood.
The items to be processed are automatically stored in the drum D, taken sequentially through the conventional chemical and electrochemical processing phases at different stations A, and finally finally in an automatic manner at the plant outlet.

The main new aspect of the method is given by the fact that it is not essential to move items from one station to another in order to carry out the various phases, which is the liquid introduced into the centrifuge. This is because more processing can be performed alternately with centrifugation without moving the drum at the same station. Theoretically, all phases could even be collected in one station, but such extreme solutions only make sense for extremely small productions where the overall cost of the multi-station plant is not justified. Absent.

All intermediate solutions between the fully developed plant shown in FIG. 2 and the phase concentrated to one station are of course possible, so that the number of stations for each phase is necessary. You may change according to. In other words, a typical method consists of the following steps.
a) introducing the drum containing the items into the centrifuge b) sending the first chemical treatment liquid to the centrifuge c) performing the treatment d) discharging the first chemical treatment liquid from the centrifuge e) Performing centrifugation of the item to regenerate the liquid f) Sending wash water to the centrifuge g) Performing washing h) Draining the wash water from the centrifuge i) The water C) centrifuge the item to recycle it j) move the drum to another station or add another chemical treatment and repeat the previous step

  It should be noted that at the same station, cleaning is performed after the chemical processing phase, where the number of stations is significantly reduced thanks to the processing already performed. In addition, centrifugation after all processing or washing can prevent the problem of carry-over contamination of liquid from one station to another and regenerate liquids with reduced consumption as described above. And also prevent environmental pollution.

  In order to use the treatment liquid most effectively, it is desirable that the treatment be carried out in a centrifuge tilted approximately 45 °, whereas for centrifugation it is better to return the drum to a vertical position. Thus, in such a case, the listed steps include processing and cleaning (steps) in addition to returning the centrifuge to a vertical orientation prior to centrifugation (steps “e” and “i”). It may be supplemented to tilt the centrifuge prior to “c” and “g”).

It will be appreciated that the above-described and illustrated method and apparatus embodiments of the present invention are merely examples of which various modifications are possible. In particular, the members that make up the device may be replaced with other members that are mechanically homogeneous or that are partially modified according to specific needs. For example, the shape of the centrifuge and the corresponding drum may be different, and the centrifuge may be inclined at different angles and / or about differently adjusted axes.

  Similarly, the hydraulic circuit that controls the flow of liquid between centrifuges may vary, for example, with more tanks and / or more pumps, or to supply multiple centrifuges through manifold valves 1 With two tanks, etc.

It is a front view of the plant of the present invention as in the comparative example described above. FIG. 2 is a top plan view of the plant of FIG. 1. It is a side view of the apparatus of the apparatus corresponding to the station of the said plant. It is the front view which showed one of the centrifuges of the station which attached the rectifier in detail.

Claims (8)

A method of galvanic electrocoating a metal item by a series of chemical or electrochemical processing phases comprising:
a) placing the item to be processed into a centrifuge (F);
b) sending the treatment liquid to the centrifuge via the delivery pipe (G);
c) executing the process;
d) discharging the treatment liquid from the centrifuge via a drain pipe (H);
e) performing centrifugation of said item to recover said liquid,
A method characterized in that the delivery pipe (G) and the drain pipe (H) are concentrated on a hydraulic connector (S) extending from the bottom of the centrifuge (F). The method of claim 1, comprising tilting the 45 ° centrifuge prior to performing the process and returning the centrifuge to a vertical position prior to centrifugation. 3. A method according to claim 1 or 2, characterized in that, in the first step in which the treatment liquid is washing water and the item is placed in the centrifuge, the item in the centrifuge that has been subjected to the aforementioned treatment is removed. . 4. A method according to any one of the preceding claims, wherein a plurality of chemical or electrochemical treatments and suitable post-cleaning are carried out continuously in the same centrifuge. One or more tanks (T, T ′) for storage and regeneration of treatment liquid with a longitudinal centrifuge (F) with removable drum (D) open at the top, suitable valves and pumping means ), And a feeding pipe (G) for feeding and discharging the processing liquid to and from the centrifuge (F), means for hydraulically connecting the drain pipe (H), and the centrifuge (F) electrically Having a connected current rectifier (R);
  An apparatus for galvanic electrical coating of metallic material, characterized in that the feed pipe (G) and the drain pipe (H) are concentrated on a hydraulic connector (S) extending from the bottom of the centrifuge (F). 6. Device according to claim 5, characterized in that it comprises means (M) for tilting the centrifuge (F) by 45 [deg.] Around the horizontal axis (X). 7. An apparatus according to claim 5 or 6, comprising an automatic storage station (L) at the inlet, an automatic removal station (U) at the outlet, and two drying stations (A ') upstream of the automatic removal station (U). A plant for galvanic electrocoating of metal items, characterized in that it comprises an array of stations (A) in line. A carriage (C) running on rails (B) extending over the station over the entire plant length, said carriage (C) having means for moving the drum (D) from one station to another The plant according to claim 7, wherein the plant is provided.