METHOD FOR TREATING STEEL PARTS WHICH ARE ALREADY GALVANISED AND HAVE A ZINC LAYER, IN PARTICULAR FOR REPROCESSING USED GALVANISED STEEL PARTS, APPARATUS THEREFOR, AND REPROCESSED GALVANISED STEEL PART

Abstract

The present invention relates to a method and an apparatus for treating already galvanized steel parts having a zinc coating, in particular for remanufacturing used galvanized steel parts. The method comprises 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.

Claims

1. 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.

2. The method of claim 1, wherein 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; 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 galvanized steel part compared to its original initial shape; type of corrosion of the galvanized steel part; degree of corrosion of the galvanized steel part; wear of the galvanized steel part; material thickness of the galvanized steel part; marking of the galvanized 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 galvanized steel part; presence of dissimilar coating materials; material and/or material quality of the galvanized steel part.

3. The method of claim 1, wherein 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.

4. The method of claim 1, wherein step B) comprises a sub-step of cleaning the galvanized steel part.

5. The method of claim 4, wherein the cleaning comprises 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 and/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.

6. The method of claim 1, wherein 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.

7. The method of claim 6, wherein the step of 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.

8. The method of claim 1, wherein 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 steel part, in particular dipping the steel part in a flux, preferably in an aqueous salt solution; drying the steel part; re-galvanizing the steel part, in particular by dipping the steel part into a zinc bath; post-processing the re-galvanized steel part, in particular cooling the re-galvanized steel part.

9. The method of claim 1, wherein 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.

10. The method of claim 1, wherein 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.

11. 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 claim 1:

12. The apparatus of claim 11, comprising 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.

13. The apparatus of claim 12, wherein 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.

14. The apparatus of claim 12, wherein the station for checking the galvanized steel part for suitability with a view to remanufacturing comprises an optical and/or mechanical and/or inductive and/or electrical and/or chemical measuring device, in particular a camera, or/and an area for visual inspection.

15. The apparatus of claim 12, wherein 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.

16. The apparatus of claim 12, wherein 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.

17. The apparatus of claim 16, wherein 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.

18. The apparatus of claim 12, wherein 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.

19. 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 according to the method of claim 1.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0157] In the following, the present invention is described by way of example with reference to the accompanying figures. In the drawings:

[0158] FIG. 1 is a schematic representation of a galvanized steel part in the form of a guard rail for a vehicle restraint system;

[0159] FIG. 2 is a schematic representation of a method for treating already galvanized steel parts;

[0160] FIG. 3 is a schematic representation of an apparatus for treating already galvanized steel parts; and

[0161] FIG. 4 is a schematic representation of exemplary profiles of galvanized steel parts.

DESCRIPTION OF IMPLEMENTATIONS

[0162] 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.

[0163] 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.

[0164] 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.

[0165] 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: [0166] A) checking the galvanized steel part 10 for suitability with a view to remanufacturing; [0167] B) preparing the galvanized steel part 10 mechanically and/or chemically; and [0168] C) rejuvenating the zinc coating of the steel part 10.

[0169] 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.

[0170] In step A), several properties of the galvanized steel part 10 are checked. These include: [0171] degree and extent of deformation of the steel part 10 compared to its original initial shape; [0172] wear of the galvanized steel part 10; [0173] material of the galvanized steel part 10; [0174] type of the existing zinc coating; [0175] degree of corrosion of the galvanized steel part 10; [0176] marking of the galvanized steel part 10.

[0177] Further properties may be checked. The properties listed above are merely exemplary, not exhaustive, and serve to explain the method.

[0178] 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.

[0179] Wear of the galvanized steel part 10 is within a permissible range, too.

[0180] 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.

[0181] 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).

[0182] 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).

[0183] 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): [0184] measuring the galvanized steel part 10 for deviations from nominal dimensions, [0185] checking whether the deviations are within specified tolerances.

[0186] 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.

[0187] In the subsequent step C), in which the zinc coating of the steel part 10 is rejuvenated, the following sub-steps are carried out: [0188] cleaning the galvanized steel part 10; [0189] pickling the galvanized steel part 10 using a pickling agent; [0190] rinsing the galvanized steel part 10 in a water bath; [0191] fluxing the galvanized steel part 10 by dipping the galvanized steel part 10 in a flux; [0192] drying the galvanized steel part 10; [0193] re-galvanizing the steel part 10, in particular by dipping the steel part into a zinc bath; and [0194] post-processing the re-galvanized steel part, in particular cooling the re-galvanized steel part.

[0195] 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.

[0196] 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.

[0197] The rinsing sub-step is carried out in a water bath.

[0198] 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.

[0199] The drying sub-step is carried out by air-drying.

[0200] 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.

[0201] The post-processing sub-step is carried out by cooling the steel part in air.

[0202] 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.

[0203] 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.

[0204] 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: [0205] a station 52 for checking the galvanized steel part 10 for suitability with a view to remanufacturing; [0206] a station 54 for preparing the galvanized steel part 10 mechanically and/or chemically; [0207] a station 56 for rejuvenating the zinc coating of the steel part 10; and [0208] 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.

[0209] 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.

[0210] 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.

[0211] 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.

[0212] 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.

[0213] FIG. 4 is a schematic representation of exemplary profiles of galvanized steel parts 10.

[0214] 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.

[0215] 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.

[0216] 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.

[0217] 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.

[0218] Implementation e) is an exemplary profile of a galvanized steel part 10 that comprises three wave crests and two wave troughs.

[0219] 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.

[0220] 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.

[0221] 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.

[0222] Implementation i) is an exemplary profile of a galvanized steel part 10 that is Z-shaped.

[0223] Implementation j) is an exemplary profile of a galvanized steel part 10 that is U-shaped.

[0224] Implementation k) is an exemplary profile of a galvanized steel part 10 that is shaped to resemble a flat dish.

[0225] 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.

[0226] Implementation m) is an exemplary profile of a galvanized steel part 10 that is H-shaped.

[0227] 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.

[0228] Implementation o) is an exemplary profile of a galvanized steel part 10 that is C-shaped, the opening of the C shape being small.

[0229] Further galvanized steel parts (not illustrated) may be, for example, corrugated sheet metal roofs, H?sch profiles, power poles, galvanized sheet pilings, etc.