SUBJECT-MATTER OF THE INVENTION

The present invention relates to a method for treating already galvanized steel parts having a zinc coating, in particular for remanufacturing used galvanized steel parts, as well as an apparatus for this purpose, and a remanufactured galvanized steel part which has been remanufactured using the aforementioned method or/and the aforementioned apparatus.

PRIOR ART

Galvanized steel parts are used in a wide range of applications. It is well known that vehicle body parts have been galvanized for corrosion protection for quite some time. Likewise, scaffolding parts or guard rails of vehicle restraint systems, also known as crash barriers, as well as other components of such systems are galvanized to considerably increase their service life. When in use, such components are exposed to significant environmental influences. In addition to weathering during their service life, such components are also exposed to corrosion processes which may be intensified by reagents present in the immediate surroundings, for example due to air pollution, in particular due to vehicle exhaust gases, etc. Corrosion processes may also be caused by substances deliberately applied to the road surface. These include, for example, salts that are used in particular in cold climates to prevent snow and/or ice from forming on the road surface. Such salts may create particularly aggressive environmental conditions to which steel parts such as those of vehicle restraint systems are exposed. In addition to chemical stresses, mechanical stresses may occur, resulting in partially strong deformation of these components. Just think of the components of vehicle restraint systems on roadways that get deformed in vehicle collisions. After minor vehicle collisions in particular, the mechanical strength of the component may still be sufficient to meet the required safety standards. However, a corrosion coating that has been applied to the guard rail of the vehicle restraint system may be at least partially damaged.

Guard rail components may be required when a new road, a new road section, is built. Guard rail components may also be required when a new obstacle, e.g. a highway rest area, is constructed or when the road surface is renewed and the guard rail components are renewed in the process. In this case, the term “remake” is used. Furthermore, guard rail components may be required if there has been an accident and deformed components need to be replaced with new ones.

Although it was common practice in the past to no longer dispose of or melt down such galvanized steel parts, e.g. guard rail components, when no longer used or damaged, exclusively as steel scrap including the zinc coating in a blast furnace but to feed them into an improved recycling cycle, where applicable, where their zinc coating is removed, if necessary, and re-galvanizing takes place, there is a need for such components that are easier to remanufacture and can then be reused as intended. For reasons of sustainability, it is particularly desirable to avoid the complex process of completely melting down the galvanized steel parts, which involves high energy consumption and many work steps, for example. But even if galvanized steel parts, when no longer used or damaged, are completely stripped of their zinc coatings as part of the recycling cycle in the prior art to be mechanically remanufactured, if need be, and then coated or galvanized again, the associated remanufacturing process is extremely complex and detrimental to the environment. What applies to guard rail components also applies to all areas involving galvanized steel elements or steel parts. Examples include the construction of lattice masts and greenhouses.

DE 10 2016 106 756 A1 relates to a thermal spraying method for an anti-corrosion coating. It is disclosed that two or more body components are first joined together or a new surface is created by machining at least one body component, with the anti-corrosion coating then being applied to the joined or machined surface by thermal spraying of a thermal spray.

The article “Feuerverzinkter Stahl in der nachhaltigen Kreislaufwirtschaft” (hot-dip galvanized steel in the sustainable circular economy) published by the German galvanizers association (Industrieverband Feuerverzinken e.V.) in May 2021 discloses that components that have already been hot-dip galvanized can be subjected to a “remake”. “Remake” means that a hot-dip galvanized component is first dezincified completely and then re-galvanized.

WO 2006/091 070 A1 discloses a method for treating prefabricated metal objects in the form of blanks, wherein the metal objects are first subjected to a shot blasting process and then coated with a zinc coating.

AU 1 993 051 763 A1 discloses a method for maintaining a flux bath in a flux station of a galvanizing line, wherein a dezincification station is upstream of the flux station.

OBJECT

It is the object of the present invention to provide a method and an apparatus of the type described at the beginning, which enable simple and yet high-quality remanufacturing of used galvanized steel parts.

SOLUTION AND EMBODIMENTS ACCORDING TO THE PRESENT INVENTION

The aforementioned object is accomplished with a method for treating already galvanized steel parts having a zinc coating, in particular for remanufacturing used galvanized steel parts, comprising the following steps:

- A) checking the galvanized steel part for suitability with a view to remanufacturing;
- B) preparing the galvanized steel part mechanically and/or chemically; and
- C) rejuvenating the zinc coating of the steel part.

This helps to achieve simple yet high-quality remanufacturing of galvanized steel parts. There is no need to completely melt down the galvanized steel part and/or to completely remove the zinc coating from the galvanized steel part. Instead, the galvanized steel part including its original zinc coating—even if completely or partially damaged—can be reused so that the protective effect of the original residual zinc coating left on the component, if any, can also contribute to the protective effect of the re-galvanized steel part. The result is a rejuvenated zinc coating. Overall, costs can thus be saved. Furthermore, a high degree of sustainability can be achieved because energy-intensive (melting down) and environmentally harmful (complete removal of zinc coating) process steps can be avoided.

According to one aspect of the invention, it may be provided that in step C), the zinc coating of the steel part is rejuvenated by at least partially applying a new, additional zinc coating to the existing zinc coating. The coating may be applied by dipping the steel part in a melt, in particular one having a high zinc content. Alternatively, the coating may be applied by spraying or dabbing or coating the steel part with a zinc agent. The application may further include other types of application, for example thermal diffusion or mechanical processes. The additional zinc coating may further comprise a layer of zinc, an alloy containing zinc or a carrier material including zinc. Even if there is mention of a new zinc coating, rejuvenating means that the new zinc coating forms a uniform, homogeneous zinc coating—the rejuvenated zinc coating—with the original coating.

In general, it is to be noted that rejuvenating or rejuvenation of the zinc coating can also be understood to mean restoration of the zinc coating.

According to one embodiment of the invention, it may be provided that in step C), the zinc coating of the steel part is rejuvenated by at least locally applying additional zinc material to the existing zinc coating.

The rejuvenated zinc coating thus forms a continuous zinc coating in the sense of the invention. Preferably, this is homogeneous and/or forms a uniform coating with the original zinc coating. One could say that the rejuvenated zinc coating has been enriched with new and/or additional zinc material. In other words, rejuvenation does not produce a separate zinc coating on the original zinc coating but merely a common, i.e. rejuvenated, zinc coating. This means that the rejuvenated zinc coating comprises the original zinc coating and the additional zinc material. This makes it possible to continue using the protective effect of the original zinc material, with additional zinc material adding to the protective effect so that a necessary level of corrosion protection for the steel part is achieved or can be restored. Put simply, rejuvenation can achieve a (rejuvenated) zinc coating where it is impossible to find out by visual inspection or measurement that it comprises material of the original zinc coating and additional zinc material.

The added zinc material can be applied to such an extent that the thickness of the zinc coating the galvanized steel part had when previously manufactured is restored. However, more or less material may be applied—at least locally—so that at least portions of the rejuvenated zinc coating are thicker or thinner than the original zinc coating. Even then, the rejuvenated zinc coating may be homogeneous or uniform. A zinc coating portions of which are thinner may be the case, for example, if portions of the galvanized steel part had no or a very thin zinc coating before the method according to the invention was performed and today's requirements permit a thinner zinc coating. Where the rejuvenated zinc coating is the thinnest, its thickness will frequently be at least as thick and/or on average as thick as or thicker than the original zinc coating. The thickness of the rejuvenated zinc coating may vary in places or be substantially the same on the steel part.

According to one embodiment of the invention, it may be provided that sub-steps and/or a required scope of step B) and/or C) are determined on the basis of step A). Based on the check of the steel part and the zinc coating still present, the further course of the method can thus be adapted to the detected condition of the steel part and the zinc coating.

In one embodiment, the method according to the invention provides that in step A), the galvanized steel part is checked with a view to at least one of the following properties:

- type of the existing zinc coating: the types of the existing zinc coating include, without limitation, hot-dip galvanizing, spray galvanizing, sheradizing, diffusion galvanizing, galvanizing using zinc flakes or binder systems, electrogalvanizing, mechanical galvanizing and film galvanizing; furthermore, the type of zinc-iron phases can be checked;
- condition of the existing zinc coating: the condition of the existing zinc coating may include a local coating thickness and/or an areal distribution of the coating thickness and/or an average coating thickness on the steel part and/or a parameter comprising the degree of deviation from an average coating thickness; furthermore, the condition of the zinc coating may relate to an extent of corrosion of the existing zinc coating and/or also the presence of a specific zinc-iron phase;
- degree of contamination;
- concentration of deposits, in particular of salts, oxides, hydroxides, greases, etc.: this can be of particular advantage when selecting steps in the subsequent preparation of the steel parts, such as cleaning processes;
- type of deposits, in particular salts, oxides, hydroxides, greases, etc.;
- deformation of the steel part compared to its original initial shape;
- type of corrosion of the steel part;
- degree of corrosion of the steel part;
- wear of the steel part;
- material thickness of the steel part;
- marking of the steel part: The marking may be a marking by the original manufacturer or a CE marking or an embossing die; the marking of the steel part may further be a type of serial number; the marking may include traceability of the source material or the manufacturing period or the manufacturer of the steel part;
- presence of a fastening option or a fastener, in particular a bore and/or a thread and/or a hole and/or an elongated hole and/or a screw or a bolt or other fasteners;
- condition of a fastening option, in particular a bore and/or a thread and/or a hole and/or an elongated hole;
- color of the steel part;
- presence of dissimilar coating materials;
- material and/or material quality of the steel part.

According to one embodiment, it may be provided that in step A), it is determined on the basis of at least one of the aforementioned properties or parameters whether or not there is suitability for remanufacturing. For example, strong deformation and/or a high degree of corrosion and/or excessive wear of the steel part and/or a poor condition of fastening options may be an exclusion criterion that prevents remanufacturing. A strongly damaged steel part could then be sorted out and not be subjected to the further process steps B and C. The rejected steel part may then be intended to undergo conventional recycling. If, for example, it is determined that the steel substance is already corroded to such an extent that a predetermined maximum level of, for example, 30% corrosion-related loss is exceeded, there is no suitable for remanufacturing. According to another example, it may be provided that there is no suitability for remanufacturing if the thickness of the steel substance minus a manufacturing tolerance falls below a minimum value. For example, the thickness of the steel substance may be 3 mm and the manufacturing tolerance may be +/−0.17 mm, meaning that the minimum value is 3.00 mm-0.17 mm=2.83 mm.

It is to be noted that according to one embodiment of the invention, checking the galvanized steel part for suitability for remanufacturing in step A) may at least comprise determining whether the steel part is galvanized at all. This helps to determine whether the steel part should and/or can be subjected to the method at all. Furthermore, checking in step A) may include determining whether the galvanized steel part falls below a maximum permissible size of the steel part and/or exceeds a minimum permissible size of the steel part. A minimum and/or maximum size of the steel part may be specified for the treatment, for example by system parameters.

According to one embodiment, it may be provided that after step A), the type of or method for rejuvenating the zinc coating is determined on the basis of the type of the existing zinc coating.

According to another idea of the invention, it may be provided that after step A), an extent of the rejuvenation of the zinc coating of the steel part is determined on the basis of the condition of the existing zinc coating.

According to one embodiment of the method according to the invention, it may be provided that in step A), the manufacturer and/or material of the steel part are determined on the basis of the marking of the steel part. For example, it may be provided that only steel parts of certain manufacturers and/or certain materials are suitable for remanufacturing. Furthermore, the marking may be decisive for whether and to what extent a warranty can be given for the remanufactured steel parts. Furthermore, the remanufactured steel parts may get a new marking on the basis of the determined marking.

According to one embodiment of the invention, it may be provided that step A) is performed using at least one optical and/or mechanical and/or inductive and/or electrical and/or chemical measuring device, in particular a camera, or/and by visual inspection, in particular manual inspection of the geometry of the galvanized steel part for dimensional accuracy or suitability using gauges or templates. The measuring device may be a mechanical probe that checks the geometry and/or material thickness of the steel part, for example. The measuring device may further be based on an inductive and/or electrical measuring method, such as an eddy current measuring method, which identifies the condition of the zinc coating. A chemical measuring device may, for example, determine a type of deposits and/or corrosion of the steel part. If it is determined that the galvanized steel part is not suitable for remanufacturing, the steel part may be sorted out so that it will not undergo steps B) and C).

According to one embodiment, it may be provided that the steel part is pre-cleaned in step A). This may serve to remove contaminants that are easy to remove. In the process, the surface of the steel part and thus the existing zinc coating are exposed. This is also important for measuring the geometry, where only the component itself is to be measured rather than the component including the contamination. This makes it easier to check the condition and/or properties of the steel part and/or the zinc coating and thus its suitability for remanufacturing. It also makes it easier to perform the subsequent process steps B) and/or C).

According to one embodiment of the present invention, it may be provided that after step A), the steel parts are sorted or categorized into groups. This may be done, for example, on the basis of the properties checked. This may be an advantage when grouping steel parts requiring similar remanufacturing processes for subsequent remanufacturing steps.

According to one embodiment, it may be provided that after step A), it is determined on the basis of the properties checked how or to what extent or in which sub-steps step B) and/or C) are carried out. For example, the concentration of deposits may be used to determine the intensity of preparations. Furthermore, the type of deposits may be used to determine the necessary steps of preparation. Furthermore, the condition of at least one fastening option may be used to determine whether a new and/or a remanufactured fastening option is introduced in an additional processing step.

According to another idea of the invention, it may be provided that step B) comprises a sub-step of cleaning the galvanized steel part. This may serve to remove contaminants. In the process, the surface of the steel part and thus the existing zinc coating are exposed. The residual zinc coating, i.e. the zinc coating left, is thus exposed. At this point, it is to be noted that cleaning may also be provided in step C). However, such cleaning primarily serves the purpose of chemically preparing the galvanizing process and is therefore not explained in more detail at this point.

According to the invention, it may be provided in this context that the cleaning comprises at least one of the following cleaning steps:

- subjecting at least portions of a galvanized steel part to a treatment by blasting using a blasting material, for example sandblasting or water blasting, in particular high-pressure water blasting, or dry ice blasting; the blasting material may be, for example, sand, corundum, water, dry ice and/or steel. An advantage of blasting using steel would be the possible subsequent separation of the blasting material and zinc coating by magnetic force.
- treating at least portions of the galvanized steel part by abrasion or brushing,
- treating at least portions of the galvanized steel part by applying a cleaning substance,
- dipping at least portions of the galvanized steel part into a cleaning bath,
- treating at least portions of the surface of the galvanized steel part with a laser.

Blasting, for example sandblasting and water blasting, may be used in particular to remove tenacious contaminants. Sandblasting and abrasion may be used in particular to remove existing corrosion from the steel part and/or the existing zinc coating. Cleaning substances may be used in particular to dissolve, soften or remove contaminants. The same applies to laser treatment. Immersion in a cleaning bath may be used in particular to dissolve or soften water-soluble or dissimilar contaminants.

According to an advantageous embodiment of the invention, it may be provided that step B) comprises the following sub-steps:

- measuring the galvanized steel part for deviations from nominal dimensions,
- checking whether the deviations are within specified tolerances,
- corrective forming of the galvanized steel part if deviations exceed the specified tolerances.

Corrective forming may be used to ensure that the galvanized steel part has nominal dimensions that are within specified tolerances. To keep stress on the galvanized steel part as low as possible, corrective forming should be carried out to an extent that is as small as possible yet necessary. Measuring may also be used to record and document the actual condition of the galvanized steel part.

In this context, one embodiment of the invention may provide that after corrective forming or after step C), a new marking is applied to the steel part, for example an embossing, an aperture, a serial number and/or a mark which may provide additional data such as, for example, the time of remanufacturing and/or data of the remanufacturer or manufacturer.

This new marking may be a manufacturer's marking and/or a marking of remanufacturing and/or a marking of the properties of remanufacturing and/or time of remanufacturing and/or a seal of quality and/or a legally required marking, in particular a CE marking, and/or a material marking.

In this context, one embodiment of the invention provides that corrective forming comprises at least one of the following sub-steps:

- cold forming by pressing;
- cold forming by rolling, in particular flat rolling or profile rolling;
- cold forming by bending;
- re-punching bores and/or holes and/or elongated holes;
- adding bores;
- cutting threads.

It may be the case that galvanized steel parts subjected to the method according to the present invention have inappropriate distances for the attachment of fasteners. This may be the case, for example, if industry standards or customer requirements have changed in the meantime. Re-punching may help to achieve that a galvanized steel part is adapted to a current standard or to customer requirements. This may increase the number of galvanized steel parts to be considered for the treatment method, which may positively affect the cost-effectiveness of the method. It may also maximize the recyclability of already galvanized steel parts and hence promote sustainability. In the case of guard rails, it may be necessary to re-punch a perforation at a distance of 1000 mm, thus supplementing an existing perforation at a distance of 1333 mm.

According to the invention, it may further be provided that step C) comprises at least one of the following sub-steps:

- cleaning the galvanized steel part;
- pickling the galvanized steel part using a pickling agent, in particular an acid containing zinc or a hydrochloric acid;
- rinsing the galvanized steel part in a water bath;
- fluxing the galvanized steel part, in particular dipping the galvanized steel part in a flux, preferably in an aqueous salt solution;
- drying the galvanized steel part;
- re-galvanizing the steel part, in particular by dipping the galvanized steel part into a zinc bath;
- post-processing the re-galvanized steel part, in particular cooling the re-galvanized steel part.

Cleaning may include a necessary, in particular wet chemical, pre-treatment prior to re-galvanizing the steel part. Cleaning may include degreasing using a degreasing agent and/or rinsing with water. Aqueous alkaline or acidic degreasing agents may serve as degreasing agents. Rinsing with water serves to prevent possible carry-over of a degreasing agent into a subsequent process or a subsequent bath, such as a galvanizing bath.

Pickling is used in particular to remove inherent impurities such as rust and scale. The duration of the pickling process and/or the concentration of the pickling agent may be adjusted depending on the extent of the impurities. It may be provided that the pickling agent has a predetermined temperature that aids pickling. Suitable pickling agents include: hydrochloric acid (HCL) with an acid content of between 1 and 18% and, depending on the application, a salt load due to iron and/or zinc salts.

Rinsing serves to prevent possible carry-over of the pickling agent. Rinsing may be repeated to achieve a particularly high level of rinsing. Carry-over of the pickling agent may thus be reduced further.

Fluxing serves to precision clean the steel part with a flux. The flux further serves to increase the wettability between the steel part and the zinc to be applied. The flux may be an aqueous salt solution, an aqueous solution of chlorides, for example a mixture of zinc chloride and ammonium chloride.

Drying serves to dry the flux, which aids the subsequent galvanizing process. This may be done in a drying oven or by air-drying.

Re-galvanizing the steel part serves to apply an additional zinc coating or additional zinc material to the steel part. The result is the rejuvenated zinc coating, which is preferably homogeneous. This means that the original zinc coating is rebuilt, enriched with new zinc material and/or reinforced. The zinc material of the original zinc coating can thus be reused at least partially, preferably completely, in the rejuvenated zinc coating. Thus, efficient, cost-effective remanufacturing of used galvanized steel parts can be provided. It may be provided that the zinc bath has a predetermined temperature ranging preferably between 400° C. and 620° C., particularly preferably between 440° C. and 460° C. The zinc bath may have a predetermined zinc content of preferably at least 98.5%. It may be provided that in the re-galvanizing process, a zinc coating is formed in compliance with a standard, regulation or guideline. The DIN EN ISO 1461 standard is cited as a non-limiting example.

The purpose of post-processing the re-galvanized steel part is to cool the re-galvanized steel part. This can be done in air or in a water bath. Post-processing may also include passivation which can maintain the shine or prevent white rust or form the basis for a subsequent coating.

According to one embodiment of the invention, it may be provided that in step C), the thickness of the zinc coating determined in step A) is used to determine properties of step C). It may in particular be provided that the thickness of the zinc coating determined in step A) is used to determine a thickness of the additional zinc coating applied in the re-galvanizing process or of the additionally applied zinc material. If the existing zinc coating already corresponds to a specified value, for example a minimum value required by law or a standard or a value specified by a customer, the additional zinc coating or the additional zinc material may be thin or even omitted. If the existing zinc coating is less than the specified value, the additional zinc coating or the additional zinc material may at least correspond to this value. The coating thickness used may be the local coating thickness and/or the areal distribution of the coating thickness and/or the average coating thickness on the steel part and/or the parameter indicating the degree of deviation from an average coating thickness.

This embodiment of the invention may help to achieve that the thickness of the entire rejuvenated zinc coating, i.e. the existing and the additional zinc coating or the additional zinc material, corresponds to a required minimum value. This can save costs. Further, it is possible to save resources by minimizing the amount of zinc required. In addition, the weight of the remanufactured steel part can be kept low. For example, it is possible to restore the weight of the original galvanized steel part because only the required missing thickness of the zinc coating is added. This embodiment is of particular advantage if, for treatment, galvanized steel parts can be divided into groups of the same properties, in particular the same condition of the zinc coating.

According to one aspect of the invention, the galvanized steel parts are preferably cold-formed or hot-rolled steel parts, in particular used guard rail components of vehicle restraint systems or parts thereof or used scaffolding parts or used steel girders or body parts of vehicles or used portable structures or galvanized substructures of, for example, greenhouses or, for example, trapezoidal roof coverings or sheet pilings. This means that overall, the method is versatile. Basically, the galvanized steel part may be any galvanized steel part. For example, the galvanized steel part may have the shape of a tube, a bracket, a polygon, a flat part or a combination of different geometries.

According to one embodiment of the invention, the galvanized steel part is composed of a plurality of individual parts, preferably a plurality of similar individual parts, particularly preferably a plurality of individual parts connected with or without connecting means or plug-in connections. The individual parts may be used guard rail components of vehicle restraint systems or parts thereof or used scaffolding parts or used steel girders or body parts of vehicles or used portable structures or galvanized substructures of, for example, greenhouses or, for example, trapezoidal roof coverings or sheet pilings. In the case of used guard rail components of vehicle restraint systems, for example, two or more guard rail components may be connected to one another. The two or more guard rail components may be connected to one another in the same way as they would be if they were used as intended. Specifically, for example, two guard rail components may overlap in a planar fashion and be firmly connected to one another via screws or rivets to form a pre-assembled assembly, for example.

This procedure is of advantage as the individual parts do not undergo the processing method individually but as an assembly, i.e. in a state in which the parts are connected to one another. This procedure therefore has the advantage that fewer individual parts are subjected to the processing method. As a result, the throughput and thus the efficiency can be increased, which may also have a beneficial effect on the time required and the cost-effectiveness of the method. Another advantage is that all individual parts are processed. In the case of two guard rail components that are already connected to one another, this assembled group can be maintained and the connecting means connecting the two guard rail components to one another are processed in the method as well. This procedure is limited by the maximum permissible dimensions for the method or steps or sub-steps of the method. A further advantage is that subsequent attachment of connecting means at a place of use is not necessary or only fewer connecting means need to be attached. This means that the risk of damage to the zinc coating of the steel part can be avoided or at least reduced.

According to one embodiment of the invention, it may be provided that step C) is followed by step D) which comprises:

- detecting the thickness of the zinc coating.

Step D) serves to document and ensure the thickness of the rejuvenated zinc coating for quality assurance. This may be necessary, for example, if the zink coating is to comply with a standard, regulation or guideline. The DIN EN ISO 1461 standard is cited as a non-limiting example. The coating thickness is understood to be the thickness of the entire rejuvenated zinc coating, i.e. the existing and the additional zinc coating.

According to one embodiment, it may be provided that a new marking is applied to the remanufactured steel part after step C), preferably in a step D). This new marking may be a manufacturer's marking and/or a marking of remanufacturing and/or a marking of the properties of remanufacturing and/or time of remanufacturing and/or a seal of quality and/or a legally required marking, in particular a CE marking, and/or a material marking.

According to one aspect of the invention, it may be provided that a galvanized steel part undergoes individual steps and/or sub-steps of the method several times. For this purpose, an additional step of checking whether or not the previous step was successful may be provided after each step or sub-step of the method. For example, it may be provided that the galvanized steel part is cleaned again in step B). It may further be provided, for example, that the step of corrective forming is repeated if it is determined that the corrective forming performed previously was not successful or at least not sufficient.

The aforementioned object is further achieved with an apparatus for treating already galvanized steel parts having a zinc coating, in particular for remanufacturing used galvanized steel parts, and in particular for performing the method of one of the types described above. It may therefore be provided that the apparatus is configured to perform the method of the type described above and has corresponding spatial and physical features configured to perform the method.

The apparatus according to the invention may comprise the following stations:

- a station for checking the galvanized steel part for suitability with a view to remanufacturing;
- a station for preparing the galvanized steel part mechanically and/or chemically; and
- a station for rejuvenating the zinc coating of the steel part.

It may be provided that the respective stations have sub-stations. For example, the stations for mechanical and chemical preparations may be configured with different, in particular spatially separated sub-stations. The stations may be arranged such that they are spatially separated from one another. It may further be provided that the stations are connected to one another by conveying means. It may be provided that the stations form a production line, at one end of which galvanized steel parts to be treated are fed into the production line and at the other end of which remanufactured steel parts are provided.

In one embodiment of the invention, it may be provided that at the station for checking the galvanized steel part for suitability with a view to remanufacturing, the galvanized steel part is checked with a view to at least one of the following properties:

- type of the existing zinc coating;
- condition of the existing zinc coating;
- degree of contamination;
- type of deposits, in particular salts, oxides, hydroxides, greases;
- concentration of deposits, in particular of salts, oxides, hydroxides, greases;
- deformation of the steel part compared to its original initial shape;
- type of corrosion of the steel part;
- degree of corrosion of the steel part;
- wear of the steel part;
- material thickness of the steel part;
- marking of the steel part;
- presence of a fastening option, in particular a bore and/or a thread and/or a hole and/or an elongated hole;
- condition of a fastening option, in particular a bore and/or a thread and/or a hole and/or an elongated hole;
- color of the steel part;
- presence of dissimilar coating materials;
- material and/or material quality of the steel part.

The marking may be a marking by the original manufacturer or a CE marking or an embossing die; the marking of the steel part may further be a type of serial number; the marking may include traceability of the source material or the manufacturing period or the manufacturer of the steel part.

The respective check may be carried out in one or more sub-stations.

Furthermore, it may be provided that the station for checking the galvanized steel part for suitability with a view remanufacturing has an optical and/or mechanical and/or inductive and/or electrical and/or chemical measuring device, in particular a camera, and/or an area for visual inspection, in particular for manually checking the geometry of the galvanized steel part for dimensional accuracy or suitability using gauges or templates. The measuring device may be a mechanical probe that checks the geometry and/or material thickness of the steel part, for example. The measuring device may further be based on an inductive and/or electrical measuring method, such as an eddy current measuring method, which identifies the condition of the zinc coating. A chemical measuring device may, for example, determine a type of deposits and/or corrosion of the steel part. It the check is performed in different ways, e.g. visually and mechanically, several sub-stations may be configured. If it is determined that the galvanized steel part is not suitable for remanufacturing, the steel part may be sorted out so that it will not undergo steps B) and C).

According to one embodiment, it may be provided that at the station for checking the galvanized steel part for suitability with a view to remanufacturing, a sub-station for pre-cleaning the steel part is provided. This may serve to remove contaminants. In the process, the surface of the steel part and thus the existing zinc coating are exposed. This makes it easier to subsequently check the condition and/or properties of the steel part and/or the zinc coating and thus its suitability for remanufacturing.

According to an optional aspect of the invention, it may be provided that a station for sorting the steel parts into groups is provided downstream of the station for checking the galvanized steel part for suitability with a view to remanufacturing. Sorting may be done, for example, on the basis of the properties checked. This may be an advantage when grouping steel parts requiring similar remanufacturing processes for subsequent remanufacturing steps.

According to one embodiment of the invention, the station for preparing the galvanized steel part mechanically and/or chemically comprises a sub-station for cleaning the galvanized steel part, wherein the sub-station for cleaning the galvanized steel part performs at least one of the following cleaning steps:

- subjecting at least portions of the galvanized steel part to a blasting treatment using a blasting material, for example sandblasting or water blasting, in particular high-pressure water blasting, or dry ice blasting,
- treating at least portions of the galvanized steel part by abrasion or brushing,
- treating at least portions of the galvanized steel part by applying a cleaning substance,
- dipping at least portions of the galvanized steel part into a cleaning bath,
- treating at least portions of the surface of the galvanized steel part with a laser.

The individual cleaning steps may be configured in different sub-stations.

One embodiment of the invention provides that the station for preparing the galvanized steel part mechanically and/or chemically comprises a sub-station for measuring the galvanized steel part for deviations from nominal dimensions, further comprises at least one sub-station for checking whether the deviations are within specified tolerances, and further comprises at least one sub-station for corrective forming of the galvanized steel part if deviations exceed the specified tolerances.

According to one aspect, the station for preparing the galvanized steel part mechanically and/or chemically comprises a sub-station performing at least one of the following steps:

- measuring the galvanized steel part for deviations from nominal dimensions,
- checking whether the deviations are within specified tolerances,
- corrective forming of the galvanized steel part if deviations exceed the specified tolerances.

Individual steps may be configured in different sub-stations.

It may be provided in this context that the sub-station for corrective forming is configured to form the galvanized steel part by carrying out at least one of the following sub-steps:

- cold forming by pressing;
- cold forming by rolling, in particular flat rolling or profile rolling;
- cold forming by bending;
- re-punching bores and/or holes and/or elongated holes;
- adding bores;
- cutting threads.

According to one embodiment of the invention, it may be provided that the station for rejuvenating the zinc coating of the steel part comprises at least one sub-station configured to perform at least one of the following sub-steps:

- cleaning the galvanized steel part;
- pickling the galvanized steel part using a pickling agent, in particular an acid containing zinc or a hydrochloric acid;
- rinsing the galvanized steel part in a water bath;
- fluxing the galvanized steel part, in particular dipping the galvanized steel part in a flux, preferably in an aqueous salt solution;
- drying the galvanized steel part;
- re-galvanizing the steel part, in particular by dipping the galvanized steel part into a zinc bath;
- post-processing the re-galvanized steel part, in particular cooling the re-galvanized steel part.

According to one embodiment, it may be provided that a station for applying a new marking to the remanufactured steel part is provided at a location of the apparatus before or after the steel part is fed into the station for rejuvenating the zinc coating of the steel part. This new marking may be a manufacturer's marking and/or a marking of remanufacturing and/or a marking of the properties of remanufacturing and/or time of remanufacturing and/or a seal of quality and/or a legally required marking, in particular a CE marking, and/or a material marking.

According to one embodiment of the invention, it may be provided that a station for detecting the thickness of the zinc coating is provided downstream of the station for rejuvenating the zinc coating of the steel part.

Overall, it is to be noted that processing parameters known from the prior art may be used with regard to, for example, conventional processing parameters for a cleaning process or for a galvanizing process.

As for the apparatus for treating already galvanized steel parts, it is to be noted in general that individual steps that the apparatus can perform may be configured in individual stations or sub-stations. These stations or sub-stations may be arranged such that they are spatially separated from one another. It may further be provided that the stations or sub-stations are connected to one another by conveying means. It may be provided that the stations or sub-stations at least partially form a production line. It may further be provided that at least some of the stations of the apparatus are configured at different locations and that conveying means such as trucks are provided to transport steel parts between the stations.

It is to be noted that any advantages, examples, implementations or embodiments described in connection with the method apply mutatis mutandis to the apparatus and vice versa.

The invention further relates to a galvanized steel part, in particular a cold-formed or hot-rolled steel part, preferably a used guard rail component of a vehicle restraint system or a part thereof or a used scaffolding part or a used steel girder or a used body part of a vehicle or a part of a used portable structure or a part of a sub-structure or trapezoidal roof coverings or a sheet piling, which has been treated or remanufactured using the method of the type described above.

BRIEF DESCRIPTION OF THE FIGURES

In the following, the present invention is described by way of example with reference to the accompanying figures. In the drawings:

FIG. 1 is a schematic representation of a galvanized steel part in the form of a guard rail for a vehicle restraint system;

FIG. 2 is a schematic representation of a method for treating already galvanized steel parts;

FIG. 3 is a schematic representation of an apparatus for treating already galvanized steel parts; and

FIG. 4 is a schematic representation of exemplary profiles of galvanized steel parts.

DESCRIPTION OF IMPLEMENTATIONS

FIG. 1 is a schematic representation of a used galvanized steel part 10 in the form of a guard rail component for a vehicle restraint system. The galvanized steel part 10 has a wave-shaped cross-section or profile and extends perpendicular to the wave shape along a direction in depth.

The illustration shows that the galvanized steel part 10 is free from damage such as deformation, cracks or twisting. Although the zinc coating of the galvanized steel part 10 is not explicitly shown in FIG. 1, the galvanized steel part 10 should have a uniform zinc coating that was applied in a hot-dip galvanizing process. However, the zinc coating of the galvanized steel part 10 becomes damaged and/or worn and/or weathered over time. Nevertheless, the extent of the damage is such that the steel substance of the galvanized steel part 10 is not significantly impaired.

The galvanized steel part further has a marking 12 indicating the original manufacturer of the galvanized steel part 10 and the actual material of the galvanized steel part 10. The marking 12 is exemplary and could also be provided in a different way or in a different position.

FIG. 2 is a schematic representation of a method for treating already galvanized steel parts. At the beginning of the method, the galvanized steel part 10 shown in FIG. 1 is fed. The method comprises the following steps:

- A) checking the galvanized steel part 10 for suitability with a view to remanufacturing;
- B) preparing the galvanized steel part 10 mechanically and/or chemically; and
- C) rejuvenating the zinc coating of the steel part 10.

Further, the dashed arrows show that a galvanized steel part 10 may undergo individual steps of the method once again. This also applies to sub-steps of the method.

In step A), several properties of the galvanized steel part 10 are checked. These include:

- degree and extent of deformation of the steel part 10 compared to its original initial shape;
- wear of the galvanized steel part 10;
- material of the galvanized steel part 10;
- type of the existing zinc coating;
- degree of corrosion of the galvanized steel part 10;
- marking of the galvanized steel part 10.

Further properties may be checked. The properties listed above are merely exemplary, not exhaustive, and serve to explain the method.

If in the step in which the deformation of the galvanized steel part 10 compared to its original initial shape is checked, it is determined that the deformation exceeds a permissible range, the galvanized steel part 10 has a property that prevents processing or remanufacturing. The range is selected such that reshaping using, for example, corrective forming, is no longer possible. The steel part is then marked as scrap, for example, and sorted out of the process without undergoing a further step B) or C). In the present case, however, it is determined that the deformation of the galvanized steel part 10 is within a permissible range.

Wear of the galvanized steel part 10 is within a permissible range, too.

By checking the marking, the manufacturer of the original galvanized steel part 10 and the actual material of the galvanized steel part 10 are determined.

All of the aforementioned properties, which are checked in step A), lead to the result that the exemplary galvanized steel part 10 can be subjected to the subsequent steps of the method, e.g. steps B) and C).

If a checked property were such that remanufacturing using the method is not possible, the galvanized steel part 10 would, for example, be marked as scrap and sorted out and thus not be subjected to any of the subsequent step B) or C).

In step B), the galvanized steel part 10 is prepared mechanically and/or chemically. In a first sub-step, the galvanized steel part 10 is cleaned by, for example, removing contaminants from the surface of the galvanized steel part 10 using high-pressure water blasting. Subsequently, the following sub-steps are carried out in step B):

- measuring the galvanized steel part 10 for deviations from nominal dimensions,
- checking whether the deviations are within specified tolerances.

In the present case, it is determined that the deviations are within specified tolerances. Subsequent corrective forming is therefore not necessary for the galvanized steel part 10 shown.

In the subsequent step C), in which the zinc coating of the steel part 10 is rejuvenated, the following sub-steps are carried out:

- cleaning the galvanized steel part 10;
- pickling the galvanized steel part 10 using a pickling agent;
- rinsing the galvanized steel part 10 in a water bath;
- fluxing the galvanized steel part 10 by dipping the galvanized steel part 10 in a flux;
- drying the galvanized steel part 10;
- re-galvanizing the steel part 10, in particular by dipping the steel part into a zinc bath; and
- post-processing the re-galvanized steel part, in particular cooling the re-galvanized steel part.

Cleaning using an alkaline or acidic solution as the first sub-step of a wet chemical process ensures that any grease adhering to the galvanized steel part 10 is completely removed. The galvanized steel part 10 is dipped into a bath containing the solution. In another sub-step, the galvanized steel part 10 is then dipped into a water bath.

In the pickling sub-step, contaminants such as rust and scale are removed. For this purpose, the galvanized steel part 10 is dipped into a bath containing hydrochloric acid, the hydrochloric acid being at approximately room temperature. In the present case, the steel part 10 continues to have a zinc coating after pickling.

The rinsing sub-step is carried out in a water bath.

The fluxing sub-step is carried out by dipping the galvanized steel part 10 into a bath containing the flux, the flux being based on an aqueous salt solution.

The drying sub-step is carried out by air-drying.

The sub-step of re-galvanizing the galvanized steel part 10 is carried out by, for example, dipping the steel part 10 into a bath having a zinc content of at least 98.5% and a temperature of approximately 450° C. Re-galvanizing may produce a rejuvenated zinc coating comprising the original zinc coating and additional zinc material.

The post-processing sub-step is carried out by cooling the steel part in air.

Step C) is followed by step D). The thickness of the zinc coating of the re-galvanized steel part is measured to check the previous steps. In addition, the thickness of the zinc coating of the re-galvanized steel part is documented for quality assurance.

In addition, a new marking is applied to the steel part between steps B) and C). The new marking must at least indicate that the re-galvanized steel part has been remanufactured, who performed the method and what material the steel part is made of.

FIG. 3 is a schematic representation of an apparatus 50 for treating already galvanized steel parts. In the present case, the apparatus 50 comprises the following:

- a station 52 for checking the galvanized steel part 10 for suitability with a view to remanufacturing;
- a station 54 for preparing the galvanized steel part 10 mechanically and/or chemically;
- a station 56 for rejuvenating the zinc coating of the steel part 10; and
- a station 58 for detecting the thickness of the zinc coating of the re-galvanized steel part and for marking the re-galvanized steel part.

The Figure further illustrates that the galvanized steel part 10 is initially fed to the apparatus 50. Having been treated successfully, a re-galvanized or rejuvenated galvanized steel part 10′ leaves the apparatus 50 and can be used again as intended in practice.

The apparatus 50 is configured to perform the method described with reference to FIG. 2. Consequently, step A) is carried out in station 52 for checking the galvanized steel part 10 for suitability with a view to remanufacturing, step B) is carried out in station 54 for preparing the galvanized steel part 10 mechanically and chemically, step C) is carried out in station 56 for rejuvenating the zinc coating of the steel part 10, and step D) is carried out in station 58 for detecting the thickness of the zinc coating of the re-galvanized steel part and for marking the re-galvanized steel part.

The apparatus 50 is schematically illustrated as explained. It is to be noted that the apparatus 50 is a type of production line in which steps A), B), C) and D) are carried out and the galvanized steel part 10 is conveyed between the stations and respective sub-stations by respective conveying means such as conveyor belts, cranes, lift trucks or trucks over long distances, etc.

Station 58 is shown in dashed lines to indicate that station 58 for detecting the thickness of the zinc coating of the re-galvanized steel part may be provided in the present case but need not necessarily be provided, i.e. it is purely optional. Also, the re-galvanized steel part 10′ may leave the apparatus 50 without passing through station 58 for detecting the thickness of the zinc coating of the re-galvanized steel part and for marking the re-galvanized steel part.

FIG. 4 is a schematic representation of exemplary profiles of galvanized steel parts 10.

Implementation a) is an exemplary profile of a galvanized steel part 10 that substantially corresponds to the profile of the guard rail component shown in FIG. 1. The profile has two wave crests and one wave trough.

Implementation b) is an exemplary profile of a galvanized steel part 10 in which the two wave crests are flat and formed by a deep wave trough having a straight wave trough portion.

Implementation c) is an exemplary profile of a galvanized steel part 10 that comprises three wave crests and two wave troughs. The galvanized steel part is thus similar to implementation a). However, the crests have straight sections.

Implementation d) is an exemplary profile of a galvanized steel part 10 that comprises three wave crests and two wave troughs. The galvanized steel part is thus similar to implementations a) and c). However, the wave crests and troughs have a continuous course and no straight sections.

Implementation e) is an exemplary profile of a galvanized steel part 10 that comprises three wave crests and two wave troughs.

Implementation f) is an exemplary profile of a galvanized steel part 10 that is U-shaped in a middle section, wherein the U-shaped section is enclosed by a respective wave end.

Implementation g) is an exemplary profile of a galvanized steel part 10 that is C-shaped. Top, middle and bottom sections of the C shape are configured with respective straight sections.

Implementation h) is an exemplary profile of a galvanized steel part 10 that is C-shaped as is similar to implementation g), wherein the middle area of the C shape is shorter.

Implementation i) is an exemplary profile of a galvanized steel part 10 that is Z-shaped.

Implementation j) is an exemplary profile of a galvanized steel part 10 that is U-shaped.

Implementation k) is an exemplary profile of a galvanized steel part 10 that is shaped to resemble a flat dish.

Implementation l) is an exemplary profile of a galvanized steel part 10 that is C-shaped as is similar to implementation g), the middle section of the C shape tapering to a point.

Implementation m) is an exemplary profile of a galvanized steel part 10 that is H-shaped.

Implementation n) is an exemplary profile of a galvanized steel part 10 that is H-shaped. Compared to implementation m), a middle section is small relative to the respective side sections.

Implementation o) is an exemplary profile of a galvanized steel part 10 that is C-shaped, the opening of the C shape being small.

Further galvanized steel parts (not illustrated) may be, for example, corrugated sheet metal roofs, Hösch profiles, power poles, galvanized sheet pilings, etc.