DE1912214A1 - Process and system for the continuous application of a colored paint on a galvanized metal pipe - Google Patents

Description

March 6, 1969 Gzy / pa

Allied Tube & Conduit Corporation

Process and system for the continuous application of a colored paint on a galvanized metal pipe

U.S. Patent Nos. 3,122,144 and 3,230,615 are a method and a system for the continuous production of pipes from steel strips and for continuous galvanizing these pipes described. You can work with this at low cost and get a uniform zinc coating on the Outside of the formed tubes.

An object of the invention is to apply a colored paint to the galvanized pipe. The method according to the invention and the equipment allows this paint to be applied and hardened continuously in one operation with forming and galvanizing des_ pipe,

A coating of zinc on steel pipes improves their resistance to corrosion and forms a good base for a colored coat. In contrast to those applied directly to the steel pipe Paints do not chip off the paints according to the invention and are not easily damaged either. The colored one Painting gives the galvanized pipes a good appearance, a good weather resistance, a good color retention and a high strength at low cost. If you use a transparent colored paint, the pipe gets a metallic one A particularly beautiful gloss. Different shades of color can be obtained according to the composition of the paint with different dyes or pigments in one

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suitable carrier. ". -

A resin that can be cured at elevated temperatures is preferably used as the carrier. Such resins include alkyd resins, ζ ..B. Reaction products of polyvalent Al- ^. alcohols such as glycerine, pentaerythritol or glycol, with a polyvalent acid, such as phthalic acid, ththalic anhydride, maleic acid or maleic anhydride. The resins can also be modified with oil, for example linseed oil, soybean oil, or other completely or partially drying oils. It can also be a. Polyester resin or other conventional curable resin used in the heat advertising W the. Tough protective coatings with a good appearance and good color can also be obtained with other polymeric substances, for example polyamides (nylon), polyvinylidene chlorides (Saran), polyethylene or polyesters (Dacron) or with natural or synthetic rubbers in suitable carriers.

For dyeing, the usual means can be used, such as dyes, Pigments and the like commonly contained in paints. Since the invention does not concern the composition of the paint, no ins individual detailed descriptions of this are given. It should be mentioned, however, that you can use a colored, transparent paint k can use if you have a clear on the galvanized pipe Want to have coating. In other cases the paints can contain the usual pigments and fillers.

The method according to the invention and the system according to the invention can also be used in combination with other processes and equipment for continuous production and galvanizing of pipes. In the following, the invention is to be described in combination with the method described in the above-mentioned USA patents.

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The invention relates to a continuous process for applying a colored. Ans; tr, ichs auf. a galvanized metal tube kontinuierlich.aus metal strip formed continuously passed dur.eh:aein bath of molten zinc and continuously ge.kuh.lt ₄ through water that · pan on, die.Oberfläche, the method being characterized by the so- The pipe produced in this way is checked by applying a colored coat of resin, a solvent and a coloring substance, the pipe being painted in this way, heated in order to evaporate the solvent in a straight line _; .Line.by means that convey the pipe outside the zone. where the paint is applied and not yet hardened, -. attack, whereupon the pipe is aligned and cut to the desired lengths.

It is preferable to apply the paint after the electrostatic one -Vjer-drive on, ..

In. In some cases it is useful to remove the galvanized pipe before the Apply to dry the paint.

In the case of the method according to the invention, one can proceed in such a way that the pipe coated with the paint after heating and before it is seized from the subsidies, cool by tvasser. Here you can click on the tube between the heating of the By painting and cooling with water, inflate air so that part of the air faces the direction of water cooling and the other Part is deflected in the direction of heating.

It is advantageous that you pass the pipe during the conveyance the various process stages are monitored and the conveyance is interrupted if deviations from the straight alignment are found.

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The invention also relates to a system for carrying out ^1,. this procedure. The plant is characterized by means for continuously forming a tube from strips, means for passing the tube through a bath of molten zinc, means for cooling the galvanized tube, means for continuously applying a colored paint to the galvanized tube, a heating chamber for heating of the painted pipe having an inlet opening and an outlet opening, rollers located outside the paint application device and outside the heating chamber which grasp and convey the pipe, means for aligning the painted pipe and means for cutting the pipe to the desired lengths. _;

The system can be characterized in that the means for continuous application of a colored paint from a., closed chamber with an inlet opening and an outlet opening for the tube and arranged within the chamber. Means for applying the colored paint exist.

The rollers that grip and convey the pipe can preferably be made of a plastic or a rubber-like one on their circumference Material.

Before the device for applying the colored paint can a chamber for drying the zinc coating can be arranged.

If necessary, there is a cooling chamber between the heating chamber and the rollers are provided for gripping and conveying the pipe. In . In this cooling chamber, the pipe is cooled with water.

A device for inflating air can be provided between the heating chamber and the cooling chamber. This device is designed so that part of the inflated Air in the direction of the water cooling, the other part in the

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Direction of the heating karamer is deflected.

The system according to the invention can be one or more to the promoted Having arranged around pipe devices for detecting deviations from the straight alignment. A The switch interrupts the delivery if deviations of the pipe from the straight alignment are detected. These Device can consist of a ring surrounding the tube, the inner diameter of which is greater than the outer diameter of the pipe. The device for determining deviations is preferably behind the device for applying the paint and arranged in front of the heating chamber.

It is expedient to use induction heating heated heating chamber.

The figures show, for example, an embodiment of the invention.

Figure T is a schematic flow diagram of the plant for forming the Pipe, for galvanizing and for ringing the paint.

Fig. 2 is a flow diagram of a portion of the plant of Fig. 1. Here, in particular, is the continuous application of the paint shown on the galvanized pipe.

Fig. 3 shows the device for application in cross section of the painting.

Fig. H shows in section the device for the determination of deviations from the straight alignment of the pipe and the associated switches.

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191.22H

Fig. 5 shows part of the plant where the paint has dried and is hardened.

Fig. 6 shows the rollers for gripping and conveying the pipe,

Figure 7 is a section through one made in accordance with the present invention Pipe.

According to FIG. 1, a metal strip 10 is taken from a roll 12
unwound, which is rotatably arranged on a support 14. The end of the strip is connected by the means 16 and kk to the end of the preceding strip and conveyed to the edge cutter 46, where the side edges of the strip are freshly cut and adapted to the circumference of the pipe to be produced.

From the edge cutter kb the strip arrives at a wiping device k 7 and into the device kb, where the strip is formed into a tube by rolling.

From the rollers hS the pipe passes through a welding device with a seam welder ^ O, a seam smoother 52 to a device 53, where it is cooled by spraying water. After the welding device $ k , the welded pipe 56 comes through
Washer 58 and 7 ^> a rinsing device 78, a device for washing with acid and a further device 96 for rinsing with water, to oxides, Schmiex'mit tel and the like from the
Remove the surface of the pipe and prepare it for subsequent galvanizing. ■

The welded and cleaned pipe 56 comes continuously from the cleaning to a steam blower 97 » ^w ° residues of fumes are removed from the surface. Then the pipe goes through

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Induction heater 120 where it is necessary to enter the bathroom 132_ is preheated from molten zinc. The preheater and the case with the melted! Zinc will be under an inert Maintained the atmosphere in order to reduce the oxidation of the tine and facilitate galvanizing.

Nozzles are positioned after the outlet from the molten zinc housing 132 to remove excess molten zinc from the surface. The galvanized pipe 56 is then passed through a device 164 for spraying Ivasser to solidify the zinc on the surface of the steel pipe. From here the pipe goes through another device 190 for spraying water to cool it down, then to the marking roller ^ 9 ^, the sizing rollers 192 and the cutting knives 19 ^ where the galvanized pipe is cut to the desired lengths.

The system according to the invention for applying a colored paint on the galvanized pipe in a continuous process, which is combined with the manufacture of the pipe and its galvanizing., is located immediately after the device-for Galvanizing, the device for removing excess Zinc, the device for cooling the zinc coating and the sizing and aligning rollers, but before the Cutting device in which the painted pipe is cut to the desired lengths.

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When applying a colored paint on the pipe 'together: *' "" "■ with the production and galvanizing "numerous' - '· * ■' · difficult problems. Since the continuous manufacture of the pipe and its galvanizing necessarily have a high <Jeschwin- * If this happens, a considerable amount of space is required for the painting to apply in a uniform thickness and to dry and harden it. However, such a work space is required to coat the kotir and to dry and cure the paint, without bladder forming in him-, * ■ --— · ■ - ■

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Another problem is the support and conveyance of the Of the pipe from galvanizing by coating and hardening,. '* without damaging the still damp or uncured paint.

lüin further problem arises due to possible deformations of the tube during coating, ^of: drying and curing. The subsequent alignment and dimensioning must therefore be done in such a way that if errors and inhibitions occur, the system is shut down immediately in order to save time, manpower and material. .. · ■ ·· ^: '■ "

These are just some of Maessen in the implementation of erfindungsge- W process problems. - - ■■ · "= * * - '

Fig. 2 shows that the pipe after galvanizing ,; after this ' Stripping off excess zinc and after cooling.-in a straight line through several dimensioning. Rolls 200 and aligning rollers 202 are passed therethrough. ■. · ■ "· '

The dimensioning rollers eliminate out-of-round stalls that subsequently prevent the pipe from passing through; the -additional.procedural stages, if. one wanted .such undenensioned * «·. R9.hre continue to process, so there would be a .considerable waste with · ■ -. ■ --- .

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loss of time, material and possible damage of the plant.

The dimensioning roles are of the usual type, so that they do not need to be described in detail here.

While not essential, it is desirable to be the exterior surface of the galvanized pipe with an aqueous solution To wet the chromates in order to prevent the zinc from being eaten by the rollers for dimensioning and aligning. The solution des Chromate also helps, to some extent, in preparing the surface of the zinc for painting firmly adheres.

The galvanized pipe moves continuously from the dimensioning ones Roll 200 to align roller 2O2 to align there prior to painting. The aligning roles are also usual construction.

From the aligning rollers and prior to entering the painting equipment, the galvanized pipe is continuously conveyed through a pre-drying chamber 204 where moisture and other volatiles are removed from the surface of the pipe. The drying chamber ZOh is elongated with an inlet 206 at one end and an in-line outlet 20B at the other end through which the tube continuously passes. Drying can be accomplished by circulating hot drying gases, preferably countercurrently, through chamber 204. Vent 210 releases the gases into the atmosphere.

The warm pipe comes out of the drying chamber continuously and in a straight line through a device 212 for painting. This consists of a closed housing 240, which has a tubular

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length of about 3 to 6 m. The case has a Inlet port 216 on one side wall and in a straight line an outlet opening 218 in the opposite wall. the Openings have a slightly larger cross-section than the outer diameter of the pipe, so that the pipe can be passed straight through without touching the walls. Spray guns 220 placed around the pipe are located in short ones Spaced radially from the tube, with their mouthpieces against the Pipe are directed.

Preferably, an electrostatic spray system, such as a Ransburg system, is used to apply the paint. For this purpose, an electrical connection is established with the pipe so that the sprayed paint is attracted to the galvanized surface of the pipe and a uniform coating is created. However, other painting methods can of course also be used. Preferably ^ is sprayed but the paint to form a uniformly thick ^coating: to obtain.

From the housing, the painted tube is fed directly into an elongated heating chamber 222 where the solvents are removed and the resin of the paint is cured. In the embodiment shown, the heating chamber 222 consists of an elongated chamber with electrical induction heating, by means of which the tube is brought to the temperature required for curing the resin. The temperature inside the heating chamber is kept at around 200 to 320 ° C. to remove the solvents quickly and to accelerate the hardening of the resin. Higher temperatures can be used, which also depends 4 ^e s tube and the length of the heating chamber of the conveying speed. ^:

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Middle to. Hold and; only then can be used to continuously convey the pipe; when the paint is dry and: hardened.t -is; Otherwise -, see = - unwanted marks and 'Missing in. The painting would be imprinted. Behind the heating chamber there are ... also means for carrying and conveying the pipe, two drive rollers. 22 | ^ and 22.6-nrit. concave surfaces. They are so far: apart from each other, that they grasp the painted pipe between them. In order to achieve a firm grip and to avoid spoiling the fresh paint, these rollers are made of a plastic or hard rubber or, as in Fig. 6 , it shows off .metallic. RpIlen 22b with a layer of hard rubber or. .Plastic-. 230 on the circumference to ensure a firm hold. The rollers are rotated so that they convey the pipe in the desired direction. This not only reduces the stresses in the preceding process sections, but also makes the pipe straight. that a bulging or sagging is prevented, that ^a. uftreten could, if one pushes through the tube through the system supported by the, different portions.

To ensure. That the paint is in contact with the rollers. are cured means for cooling the pipe and paint after the heating chamber 222, but before the rollers and 226 are provided. If .the resin of the paint is through the Heat is sufficient, hardened so. is such an intermediary Cooling not required. Used for cooling an elongated closed chamber 23I with an inlet port and an outlet opening at the opposite ends, through which the pipe can be conveyed in a straight line. Within The chamber has spray devices for water through it which the pipe is quickly cooled.

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Used together with or without this water cooling one. Air blower 232, that immediately afterwards the outlet end of the heating chamber and between the heating chamber and the cooling chamber, if the latter is present. The air blower is designed so that part of the air flow in the opposite direction with the Haüptstrotn axially into the Inlet opening of the cooling chamber is deflected, so that from there no water can get into the heating boiler. Another part of the air flow is diverted into the outlet opening of the heating chamber and contributes to the circulation of the gases in it. This will cause the solvent to evaporate from the paint accelerates, and the fumes are carried away. For this The purpose of the chamber 222 is a trigger 224, preferably on the in * - inner end, which can optionally be connected to a system for recovering the solvents, if valuable organic solvents can be used.

It is expedient to arrange a switch 236 in the device, preferably immediately behind the outlet opening of the chamber for producing the paint. This switch shows deviations or bends in the pipe which could lead to an obstruction. As FIG. K shows, a ring 23o is arranged elastically at a distance from the housing. The pipe runs through the opening of this ring. The inner diameter of the ring is larger than the outer diameter of the tube so that it can easily pass through without contact if the procedure is normal. If, however, bending or buckling of the tube occurs, which can lead to a jamming or the like, the tube comes into contact with a part of the surrounding ring 230 and displaces it from the normal position. This sets the arms of one or more switches 240 in motion, giving a signal for

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an impending inhibition and interrupt the promotion of the Pipe. Instead of a surrounding ring, others can also be used Switch devices can be arranged around the pipe. Important is only that they give a signal about deviations that can lead to an inhibition. If such means were not available, this could lead to inhibitions that not only damage the system and cause difficulties, but also lead to losses of time and material would result, especially if one was at high conveyor speeds.

After drying and straightening through the rollers, the procedure continued in the usual way. The tube is passed through the aligning rollers 242 and cut at 244 into the desired ones Lengths as described in the aforementioned US patents is.

7 shows a pipe made according to the invention. It exists made of steel or other metal 246, a zinc layer 248 and an outer layer of paint 250. Bas tube has one pleasant metallic sheen, which can be kept in different shades if the coat of paint is made from a clear varnish and a coloring agent. The paint can also be opaque if it is composed accordingly. The angry Coating ^ is permanent, does not chip and is weatherproof. Protective coatings made of polyamides (nylon), polyvinylidene chlorides (Saran), polyethylene, polyester can also be used in a similar manner (Mylar or Dacron), natural or synthetic rubber be applied, with or without pigments, so that a tough elastic coating is formed. Manufactured according to the invention Pipes can be used as fences, as structural elements in buildings, to equip playgrounds and the like. where it depends on strength, weather resistance, resistance to Chipping and good looks matter.

One can also use the paintwork to identify different ones Use pipes, electric wires and the like,

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Claims (16)

Claims Ί J Process for the continuous application of a colored surface stroked a galvanized metal pipe that continuously came out Metal strips formed continuously by a bath of molten Zinc is continuously cooled by water, characterized in that it is applied to the surface the pipe thus produced is continuously painted with a colored paint composed of a resin, a solvent and a coloring agent Applies fabric, quickly heats the painted pipe to to evaporate the solvent and to harden the resin, and fe that the pipe is conveyed in a straight line through means, which attack the pipe outside the zone where the paint is applied and not yet hardened, at which point the pipe is aligned and cut to the desired lengths, 2. The method according to claim 1, characterized in that 'that the Applying paint using the electrostatic method. 3. The method according to claim 1 or 2, characterized in that the galvanized pipe is dried before the paint is applied. 4. The method according to any one of claims 1 to 3 »thereby marked-P draws that one gripped the pipe coated with the paint after the heating and before 'it by the conveying means is cooled by water. 5. The method according to claim k, characterized in that air is inflated on the tube between the heating of the paint and the cooling with water, that a part is deflected in the direction of water cooling, the other part in the direction of heating. 909840/1108 6. The method according to any one of claims 1 to 5, characterized that fflan monitors the pipe during the conveyance through the various process stages and interrupts the conveyance! if deviations from the straight alignment are found. 7. Plant for carrying out the method according to one of claims 1 to 6 _f, characterized by means (48) for continuously forming a tube from strips, means for passing the tube through a bath (132) of molten zinc, means (164) for cooling of the galvanized pipe, means (2T2) for continuously applying a colored paint to the galvanized pipe, a heating chamber (222) for heating the painted pipe with an inlet port and an outlet port, outside and outside the apparatus for applying the paint Heating chamber (222) arranged rollers (224, 226) which grasp and convey the pipe, means (242) for aligning the painted pipe, and means (244) for cutting the pipe to the desired lengths. 8. Plant according to claim 7 »characterized in that the means for continuously applying a colored paint a closed chamber (.212) with an inlet opening (216) and an exit opening (218) for the tube and within means (220) arranged in the chamber for applying the colored paint. 9. Plant according to claim 7 or 8, characterized in that the rollers (224, 226) that grasp and convey the pipe are made of a plastic or a rubber-like material on their circumference Material. 90 9840/1108 10. Plant according to one of claims 7 to 9 »characterized by" one in front of the device (212) for applying the colored Paint-arranged chamber (204) for drying the galvanizing, 11. Plant according to one of claims 7 to 10, characterized by a cooling chamber (231) between the heating chamber (222) and the V Rollers (224, 226) for gripping and conveying the pipe in which the tube is cooled with water. 12.Anlage according to claim 11, characterized by a device (232) for inflating air according to claim 5 13. Plant according to one of claims 7 to 12, characterized by a device (236) arranged around the conveyed pipe for detecting deviations from the straight line Alignment, and by a switch (24o) which interrupts the delivery if deviations of the pipe from the straight alignment are detected. H. System according to claim 13, characterized in that the device (236) for determining deviations consists of a ring (238) surrounding the pipe, the inner diameter of which is greater than the outer diameter of the pipe. 15.Anlage according to claim 13 or 14, characterized in that the device (236) for detecting deviations behind the device (212) for applying the paint and is arranged in front of the heating chamber (222). 16. Plant according to one of claims 7 to 15, characterized by a heating chamber (222) heated by induction heating. 909840/1108 "ί Empty © rf e