REPAIRING DEFECTS IN A GLASS OR GLASS CERAMIC COVERING ON A METAL OR CERAMIC SUBSTRATE INCLUDING THE SUBSTRATE SURFACE

Abstract

The invention relates to a method for repairing at least one defect in glass or glass-ceramic coating. In this method, coating material is applied to the at least one defect by a coating method, excess coating material that protrudes is removed, the applied coating material is dried and then baked with the heat input. The invention further relates to a laser repair system for repairing defects, wherein the laser repair system according to the invention comprises at least one exchangeable pivoting device, an exchangeable heat irradiation device, and an energy supply unit.

Claims

1. A method for repairing at least one defect in a glass or glass-ceramic coating, wherein the glass or the glass-ceramic coating is arranged on a metallic or ceramic substrate, and for repairing defects on the metallic or ceramic substrate surface, wherein the method comprises the following method steps: applying enamel powder or enamel slip as a coating material to the at least one defect using a coating method, removing excess coating material that protrudes, drying applied coating material, baking the applied coating material with heat input, said baking comprising the following steps: a first focused, high-energy heat input by laser irradiation with an associated melting of a radiation spot, a second defocused, low-energy heat input with controlled continuous cooling of the radiation spot, wherein the second defocused, low-energy heat input takes place by laser irradiation or inductively.

2. The method according to claim 1, wherein the method has at least one cycle, wherein individual method steps are applicable multiple times in succession.

3. The method according to claim 1, further comprising a detection of the at least one defect before the application of the coating material and/or a check of the at least one treated defect after the baking of the applied coating material, wherein the detection and/or check take(s) place by means of an optical and/or electrical test, the visual test comprising a visual inspection, and the electrical test comprising a high-voltage test in accordance with DIN EN 14430 or a low-voltage test in accordance with DIN EN ISO 8289.

4. The method according to claim 1, further comprising a mechanical and/or chemical and/or thermal pretreatment of the at least one defect.

5. The method according to claim 1, wherein the laser irradiation is carried out by a pulsed solid-state laser in the near infrared range from 780 nm to 3 μm, the solid-state laser being designed as an Nd:YAG laser with pulse durations between 9 ns and 250 ns and a laser power of 5 W to 200 W.

6. The method according to claim 1, wherein the heat input takes place through a laser repair system, the laser repair system being placed on the glass or the glass-ceramic coating before the coating material is applied and removed from the glass or the glass-ceramic coating after the baking.

7. The method according to claim 1, wherein the coating material has the same properties as the glass with the at least one defect or the glass-ceramic coating and is designed as an enamel slip or enamel powder with grain sizes of 0.35 to 160 μm.

8. The method according to claim 1, wherein the coating method is selected from a spraying method, a brushing method, a squeegee method, a casting method, a flooding method, a dipping method, a screen-printing method, and/or a spraying process.

9. A laser repair system for repairing defects according to claim 1, comprising at least one exchangeable pivoting device, an exchangeable heat irradiation device, and an energy supply unit, wherein: the laser repair system is detachably arranged on the glass or the glass-ceramic coating, the heat irradiation device is movably and detachably arranged on the pivoting device, the heat irradiation device comprises at least one exchangeable laser machining head and at least one exchangeable laser, the pivoting device has at least two positions for positioning the heat irradiation device, a first position corresponding to a rest position and a second position corresponding to a machining position on top of the defect.

10. The laser repair system according to claim 9, wherein the pivoting device has at least two pivoting arms on which a platform is arranged, the heat irradiation device being mounted on the platform and the platform being designed to be movable by the pivoting arms in the xy direction along the horizontal dimension relative to the enameled object between the first and the second position.

11. The laser repair system according to claim 9, wherein the laser repair system is detachably arranged on the glass or the glass-ceramic coating by at least one fastening means attached to the underside of the pivoting device, the underside of the pivoting device pointing towards the glass or the glass-ceramic coating.

12. The laser repair system according to claim 9, further comprising a coating system and/or a pretreatment device and/or a detection system.

13. The laser repair system according to claim 9, wherein, during the application of the coating material to the at least one defect and/or the removal of protruding excess coating material and/or the drying of the coating material and/or the detection and/or check and/or the pretreatment by a laser, the laser machining head is aligned in the first position of the pivoting device and, during the baking of the applied coating material with the heat input and/or the thermal pretreatment, is aligned in the second position of the pivoting device.

14. A method for repairing defects in a substrate selected from a container or storage facility, cladding of room, pipe, sign, industrial part, consumer good, cooking vessel, apparatus, and panel in tunnels or subways, said method comprising performing on the substrate the method for repairing at least one defect in a glass or glass-ceramic coating according to claim 1.

15. The method according to claim 2, further comprising a detection of the at least one defect before the application of the coating material and/or a check of the at least one treated defect after the baking of the applied coating material, wherein the detection and/or check take(s) place by means of an optical and/or electrical test, the visual test comprising a visual inspection, and the electrical test comprising a high-voltage test in accordance with DIN EN 14430 or a low-voltage test in accordance with DIN EN ISO 8289.

16. The method according to claim 15, further comprising a mechanical and/or chemical and/or thermal pretreatment of the at least one defect.

17. The method according to claim 15, wherein the laser irradiation is carried out by a pulsed solid-state laser in the near infrared range from 780 nm to 3 μm, the solid-state laser being designed as an Nd:YAG laser with pulse durations between 9 ns and 250 ns and a laser power of 5 W to 200 W.

18. The method according to claim 15, wherein the heat input takes place through a laser repair system, the laser repair system being placed on the glass or the glass-ceramic coating before the coating material is applied and removed from the glass or the glass-ceramic coating after the baking.

19. The method according to claim 15, wherein the coating material has the same properties as the glass with the at least one defect or the glass-ceramic coating and is designed as an enamel slip or enamel powder with grain sizes of 0.35 to 160 μm.

20. The method according to claim 15, wherein the coating method is selected from a spraying method, a brushing method, a squeegee method, a casting method, a flooding method, a dipping method, a screen-printing method, and/or a spraying process.

Description

[0112] The invention is explained in more detail with reference to the drawings, in which:

[0113] FIG. 1 is a schematic sketch, not to scale, of the laser repair system according to the invention, which laser repair system is placed in the vicinity of an exemplary defect in an enameled object,

[0114] FIG. 2 shows the laser repair system according to the invention in a view from the front, with the pivoting device in the first position in FIG. 2a and the pivoting device in the second position in FIG. 2b,

[0115] FIG. 3 is an overview scheme for the laser repair method according to the invention.

[0116] FIG. 1 shows a schematic sketch, not to scale, of the laser repair system 3 according to the invention, which laser repair system is placed in the vicinity of a defect 2 in an enameled object 1. The laser repair system 3 is arranged on the surface of the enameled object 1 by means of fastening means 10. The enameled object 1 is designed in the present case as an enameled silo sheet. The fastening means 10 are designed as magnetic feet. The laser machining head 6 is part of the heat irradiation device (not shown in the figure) and is directed at the defect 2. As a result of the arrangement on the platform of the pivoting device (not shown in the figure), the laser machining head 6 is designed to be movable in the xy direction along the horizontal dimension 13.

[0117] FIG. 2 shows the laser repair system 3 according to the invention, which laser repair system has a pivoting device 4 and a heat irradiation device 5, in a view from the front. The laser repair system 3 can be placed on the surface of an enameled object 1 such as, for example, an enameled silo plate (not shown in the figure) via two fastening means 10 designed as magnetic feet. The fastening means 10 are designed as electromagnets. Furthermore, the fastening means 10 are magnetic in the current-carrying state and can therefore be fixed on the surface of the enamel layer of the enameled object 1 and are non-magnetic in the de-energized state and thus designed so as to be detachable from the enamel layer of the enameled object 1. The pivoting device 4 also has a platform 11 with four pivoting arms 12 arranged thereon. By means of the pivoting arms 12, the platform 11 and the heat irradiation device 5 arranged thereon are designed to be movable in the xy direction along the horizontal dimension 13. The heat radiation device 5 mounted on the platform 11 of the pivoting device has a laser machining head 6 which is the interface of the laser (not shown in the figure) attached in the heat irradiation device 5 to the enameled object 1.

[0118] FIG. 2a shows the pivoting device 4 in the first position 8 which functions as a rest position. FIG. 2b shows the pivoting device 4 in the second position 9 which functions as a machining position.

[0119] FIG. 3 shows an overview diagram of the laser repair method according to the invention. First, the defect is detected 14. This is done using a high-voltage test.

[0120] Subsequently, the laser repair system according to the invention is placed on 15. This is done by means of the magnetic feet, which are attached to the underside of the pivoting device and placed on the surface of the enameled silo sheet. The electromagnets are energized and ensure that the laser repair system is fixed on the surface.

[0121] Subsequently, the alignment of the laser 16 takes place. For this purpose, the laser machining head is moved into the machining position. The alignment of the laser 16 takes place by suitable positioning of the laser machining head over the defect. Image recognition software and a camera system with crosshairs ensure the exact positioning and alignment of the laser machining head with the associated localization of the defect. This allows for mechanical fine positioning.

[0122] Subsequently, the pretreatment 17 takes place. For the mechanical and chemical pretreatment, the heat irradiation device is in the rest position. The mechanical pretreatment comprises milling the defect, the chemical pretreatment comprises etching the defect. Furthermore, the defect and the intact region around the defect are degreased. For the thermal pretreatment, the heat irradiation device is moved into the machining position. With the help of the laser beam from the laser machining head, contaminants are evaporated on the surface of the defect and the intact region around it.

[0123] The coating material is then applied 18 to the defect. The coating material is designed as a top enamel slip and completely fills the defect. The composition and properties of the top enamel slip correspond to the top enamel of the enameled silo sheet. The top enamel slip is brought into and onto the defect using a spray system. When the coating material is applied to the defect 18, the heat irradiation device is moved into the rest position. Excess top enamel slip, which protrudes above the surface of the enameled silo sheet, is removed with a blade. Subsequently, the drying of the top enamel slip takes place at approx. 80° C. to 100° C.

[0124] Subsequently, the baking process 19 of the top enamel slip takes place. For this purpose, the defect is irradiated with a laser beam from the laser machining head. For this purpose, the heat irradiation device is moved into the machining position. This is a Nd:YAG laser operated in a pulsed manner with a wavelength of 1064 nm, a laser power of 10 W to 20 W, and a pulse duration of 100 ns.

[0125] The check 20 of the treated, repaired defect is carried out subsequently. For this purpose, the heat irradiation device is moved back into the rest position. The check is again carried out via a high-voltage test. If the check is successful 21 in that a homogeneous layer has been restored and no formation of cracks occurred, the process is complete 22. One cycle of the repair method according to the invention was thus sufficient to repair the defect, i.e. coat it once and irradiate it once.

[0126] If the check is unsuccessful 23, the repair method according to the invention must be repeated 24. The coating and the irradiation can be repeated as often as desired, one after the other. This continues until the check is successful 21.

REFERENCE SIGN

[0127] 1 Enameled object [0128] 2 Defect [0129] 3 Laser repair system [0130] 4 Pivoting device [0131] 5 Heat irradiation device [0132] 6 Laser machining head [0133] 7 Laser beam [0134] 8 First position of the pivoting device [0135] 9 Second position of the pivoting device [0136] 10 Fastening means [0137] 11 Platform [0138] 12 Pivoting arm [0139] 13 Movement in the xy direction along the horizontal dimension [0140] 14 Detect the defect [0141] 15 Place on the laser repair system [0142] 16 Alignment of the laser [0143] 17 Pretreatment [0144] 18 Apply coating material [0145] 19 Baking process [0146] 20 Check [0147] 21 Check successful [0148] 22 Process completed [0149] 23 Check unsuccessful [0150] 24 Repeat repair method