DE2343997A1 - DEVICE FOR THE PRODUCTION OF TOP COATS FROM CHROME - Google Patents

Description

48S0 Heme, SOOO Munich 40,

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OipL Phys. Eduard Betzier ⁶ * ^M Dipl.-Ing. W. Herrmann-Trentepohl

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DOMIHION FOUNDRIES AND STEEL, LIMITED 1330 Burlington Street, East

Hamilton "Oatario (Canada)

Device for the production of cover layers from chrome

The invention relates to a device for producing top layer «! or »protective covers made of chrome Zinc or cadmium surfaces »Using the device according to the invention, an aqueous solution is applied to a strip which is or treatment part of the device moved. The device according to the invention also includes an arrangement for rinsing the surface of the strip if it has been in the treatment for longer than a predetermined time

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device stops.

It is known that there are difficulties in the application of protective coatings of zinc and cadmium to a substrate such as a strip or an object made of steel which is to be protected against corrosion. The protective coating of zinc or cadmium itself corrodes after a while and a white or whitish precipitate forms, which is generally referred to as storage rust or white rust. For these reasons, a thin protective coating is applied to the zinc or cadmium oxide surfaces, which normally consists of a chromium compound or compounds and which is referred to as the so-called "top layer ¹¹ ".

The topcoat is normally formed by applying a suitable aqueous chromium-containing solution to the Zinc or cadmium surface, the solution with the surface reacts and forms a thin gel-like film of complex chromates. The film is essentially non-porous to moisture and is also non-crystalline, making it a good paint bond with no absorption of the paint on the surface. Examples of methods of making such coatings are in U.S. Patent No. 3 457 124. The one specified there Solution contains specified amounts of sodium diachromate, Chromic acid, sulfamic acid, ammonium sulfate, boric acid, Sodium silicofluoride and nitric acid.

The solutions used in such procedures are very reactive and therefore very corrosive and the period of time

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during which the strip or object of the treatment solution is exposed, must be very precisely controlled and adjusted so that no adverse effects occur, such as discoloration or chemical burns. The high-speed machines used in industry are it is not always possible to prevent the production or the belt from stopping, which affects the materials to be treated are exposed to the treatment solution for a longer period of time and this results in production shares that are worse Quality that in part cannot be used. This also reduces the overall value of the entire strip. .

The invention is therefore based on the object of a novel, improved device for producing cover layers create on surfaces by means of which highly reactive liquid mixtures can be applied, without adverse effects occurring if the production device is unexpectedly stopped or runs slower.

The invention therefore relates to an apparatus for manufacturing a top layer or a coating on a surface by applying a liquid mixture, characterized by means of a device for moving or guiding a strip through a liquid application arrangement, a device for applying the liquid mixture to the surfaces of the strip, a device which acts on a Stopping the strip reacts and the attachment of the liquid mixture stops on the surfaces, and a device that stops the strip over a period longer than a predetermined period

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reacts and flushing liquid on the strip in the attachment assembly now / ?: at the end of such a period to rinse off the liquid mixture.

The device according to the invention preferably includes a device for collecting the unused liquid Mixture and the flushing liquid from the application device and a device for supplying the collected rinsing liquid to the collected liquid mixture for the purpose of Replenishment of the latter.

On the surfaces of the galvanized steel strip 10 a protective coating of chromium is to be applied according to the method according to the invention. The stripe is by means of the rollers or rollers 11 by a liquid-up Carrying device 12 carried out and then by means of a pair of gripping or pressure rollers 13 to the further stages of the treatment device performed in which the strip is dried and rolled up. The type and the arrangement of these further stages is the expert known and will not be described in detail here.

An aqueous solution with the Mj schunr according to the invention is stored in a container 14 and through the pump 15, the valve 16, the line 17, the automatically controlled valve 18 and. the capping device 19 to two spray nozzles 20, which are arranged above and below the steel strip 10 and spray the liquid directly onto the surfaces of the same. Excess liquid draining off the steel strips is collected in the collecting container 21 and returned to the container 14 through the automatically controlled valve 22, the valve 23 and the line 24.

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A second container 25, which is at a higher level than the container 14, contains rinse water, which is at Demand is passed through the pump 26, the line 27 and the automatically controlled valve 28 to the spray nozzles 20. 1 / ie with the mixture forming the coating, the rinsing liquid, which drips off the steel strip, collected in the collecting container 21 and by an automatically controlled Valve 29 »a valve 30 and the line 31 returned to the container 25. The container 14 is heated and kept at the required elevated temperature. The containers 14 and 25 are by means of a Leitun /? 32 or one Valve 33 connected to the contents of the container 25 if necessary as a make-up water for the liquid of the Container 14 to use. The contents of the container 25, the temperature of which can also be adjusted if necessary, can be topped up with demineralized water through the line 34 and the valve 35 located therein will.

When operating the device shown in the drawing, the strip of the one not shown here Feed unrolled and fed at a constant speed through the device in which it is with the liquid is sprayed from the container 14. Excess liquid is removed from the steel strip and a certain control and control of the thickness of the resulting top layer or of the protective coating produced in this way is achieved by the pressure rollers 13 which are pressed into contact with each other in a predetermined Pressure by means of the air powered motor 36, the conveying speed of the steel strip and the distance between the nozzles 20 and the rollers 13 is set so that

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that the desired effective immersion time of the steel strip is obtained in the liquid. This is preferably 1 to 10 seconds.

A suitable detector 37, which is coupled to the rollers or rollers 13, determines the speed of the itself by the device 12 moving steel strip. The detector control relay 38 regulates and controls the operation the valves 18, 22, 28 and 29 and the pumps 15 and 26. Under normal operating conditions, the relay 38 operates so that it keeps the valves 18 and 22 open, the valves 28 and closed, the pump 15 fully in operation and the Pump 26 stops operating or stops idling with the pressure released by a check valve 39. On the Detector 37, which senses that the speed of the steel strip has fallen below a predetermined value, the relay 38 acts so that the valves 18 and 22 are closed and the pump 15 is stopped, whereby the supply the liquid is shut off from the container 14. After a short variable period of time, the valves will 28 and 20 open and the pump 26 operates to supply rinse water to the nozzles 20 and the liquid rinsed off the steel strip. This prevents parts of the strip from being unduly exposed to the action of the liquid are exposed, thereby adversely affecting it due to discoloration. A normal operation resumes when the strip moves above the minimum speed again. The length the above period is set so that a normal short stop of the tape is enabled without that the flushing device is put into operation.

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The control and management of the pressure exerted by the Rolling 13 exerted on the strip is essential to achieve the desired results and properties. It it was found that the roles have to be replaced relatively often during operation of the device, since these wear out. This changes the weight of the rollers and thus also the pressure control properties. the Roles have to be processed back to the required »profile will. These disadvantages are avoided by the method of the invention in that the bridge motors 36 double-acting cylinders are, wober "the upper ones, and the lower parts of the cylinder independently with compressed Lui'-t from lines 40 and 41, which the valves 42 and 43 contained, to be supplied. When a new set of rollers has been installed in this way, air will run out of the pipe 40 fed to the lower part of the cylinder until the weight of the upper rollers is just fully supported. The required Air pressure is then established in the upper part of the cylinder and determines the compressive effect of the folds and regardless of their weight.

Patent claims:

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BATH ORIGINAL

Claims (5)

Claims 1. Device for producing a cover layer or a Protective coating on a surface by applying a liquid mixture, characterized by a device for moving a strip through a liquid attachment arrangement, a device for applying the liquid mixture to the surfaces of a strip, a device which is responsive to the Strip reacts and stops the application of the liquid mixture to the surfaces, and a device that on stopping of the strip is responsive to a period longer than a predetermined period of time and in the attachment device Rinse liquid on the strip at the end of such a period leads to rinse off the liquid mixture. 2. Apparatus according to claim 1, characterized by a device for catching and collecting the unused liquid mixture and the rinsing liquid of the mounting arrangement and a device for supplying the collected flushing liquid to the collected one liquid lip mixture to fill up the latter. 3. Device according to claim 2, characterized by a collecting and collecting device for collecting the unused liquid mixture and the rinsing liquid, a first line that has a first control and control valve included by the collection device leads to a first container for the liquid mixture, a second line that carries a second control 409810 / 11U " ⁹ " and control valve included by the containment and collection device leads to a second container for the rinsing liquid, these responsive devices being the first Close the valve and open the second valve when the strip stops. 4. Apparatus according to claim 3, g e k e nn is characterized by a third line with a third control and Control valve between the first and the second container for the purpose of supplying the liquid from the first in the second container. 5. Device according to claims 1 to 4, characterized by pressure rollers or pressure rollers, which engage the strip in the liquid application assembly to remove excess liquid, and a device for compensating for changes in the rollers in order to maintain a constant pressure of the Ensure rollers or rollers. 409810 / 11U Blank page