Method for Marking Workpieces and Workpiece

Abstract

In an embodiment a method includes providing a workpiece, attaching a marking to the workpiece such that the marking is integrally bonded to the workpiece, wherein attaching the marking includes applying at least one raw material for the marking, heating the workpiece with the at least one raw material such that the marking is formed from the at least one raw material and performing a surface treatment of the workpiece at least in an area with the marking, wherein performing the surface treatment includes shot peening, sand blasting or material-removing etching against which the marking is resistant to, wherein the marking remains readable on the workpiece at least until after performing the surface treatment, and wherein the marking has, in at least a part of a near ultraviolet, a visible and/or a near-infrared spectral range relative to the workpiece, at least one of a degree of reflection difference, a reflectance difference or an albedo difference of at least 10 percentage points.

Claims

1.-14. (canceled)

15. A method comprising: providing a workpiece; attaching a marking to the workpiece such that the marking is integrally bonded to the workpiece, wherein attaching comprises applying at least one raw material for the marking; heating the workpiece with the at least one raw material such that the marking is formed from the at least one raw material; and performing a surface treatment of the workpiece at least in an area with the marking, wherein performing the surface treatment comprises shot peening, sand blasting or material-removing etching against which the marking is resistant to, wherein the marking remains readable on the workpiece at least until after performing the surface treatment, wherein the marking has, in at least a part of a near ultraviolet, a visible and/or a near-infrared spectral range relative to the workpiece, at least one of a degree of reflection difference, a reflectance difference or an albedo difference of at least 10 percentage points, wherein the workpiece is made of a metallic base material, and wherein the method is performed in the order as recited.

16. The method according to claim 15, wherein performing surface treatment comprises shot peening, and wherein the workpiece is a metal sheet.

17. The method according to claim 15, wherein attaching the marking to the workpiece comprises applying the at least one raw material directly to the base material of the workpiece so that the marking is produced directly on the base material.

18. The method according to claim 15, wherein the workpiece comprises a coating, and wherein attaching the marking to the workpiece comprises applying the at least one raw material to the coating, which covers the base material of the workpiece at least in places such that the marking is produced directly on the coating and remains spaced apart from the base material.

19. The method according to claim 15, wherein the workpiece contains iron, and wherein a scaling layer is formed in regions next to the marking while heating the workpiece.

20. The method according to claim 19, wherein performing the surface treatment of the workpiece comprises removing the scaling layer.

21. The method according to claim 15, wherein heating the workpiece comprises: hot forming the workpiece, and forming the marking from the at least one raw material while hot forming the workpiece.

22. The method according to claim 15, wherein the at least one raw material comprises an inorganic adhesion promoter and inorganic pigment particles.

23. The method according to claim 22, wherein the adhesion promoter is a glass, a ceramic or a glass ceramic.

24. The method according to claim 22, wherein the pigment particles include at least one phosphor and/or at least one metal oxide.

25. The method according to claim 15, wherein providing the surface treatment comprises material-removing sand blasting, and wherein the marking is resistant to sand blasting so that the marking is retained at least until after providing the surface treatment.

26. The method according to claim 15, wherein the marking is raised above the workpiece after performing the surface treatment, and wherein performing the surface treatment is shot peening.

27. The method according to claim 26, wherein a hardness of the workpiece is increased by shot peening.

28. The method according to claim 15, wherein attaching the marking to the workpiece comprises pressing at least parts of the marking into the workpiece.

29. The method according to claim 15, wherein performing the surface treatment comprises pressing at least parts of the marking into the workpiece.

30. A workpiece comprising: a marking in places on a workpiece surface of the workpiece, wherein the marking is attached on the workpiece surface in a positive substance joining manner, and wherein the workpiece surface has been subjected to a shot peening or a sliding grinding.

31. The workpiece according to claim 30, wherein the workpiece surface has been subjected to the shot peening so that the workpiece surface comprises a plurality of impressions of balls of the shot peening and the impressions extend across the marking.

32. The workpiece according to claim 30, wherein the workpiece is produced by the method according to claim 15.

33. A method comprising: providing a workpiece; attaching a marking to the workpiece such that the marking is integrally bonded to the workpiece, wherein attaching the marking comprises applying at least one raw material for the marking to the workpiece; heating the workpiece with the at least one raw material such that the marking is formed from the at least one raw material; and performing a surface treatment of the workpiece at least in an area with the marking, wherein performing the surface treatment comprises shot peening, wherein the marking remains readable on the workpiece at least until after performing the surface treatment, wherein the marking has, in at least a part of a near ultraviolet, a visible and/or a near-infrared spectral range relative to the workpiece, at least one of a degree of reflection difference, a reflectance difference or an albedo difference of at least 10 percentage points, wherein the workpiece surface comprises a plurality of impressions of balls from shot peening and the impressions extend across the marking, wherein the workpiece is made of a metallic base material, and wherein the method is performed in the order as recited.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0055] A method described here and a workpiece described here are explained in more detail below with reference to the drawing on the basis of exemplary embodiments. Identical reference signs indicate identical elements in the individual figures. However, no true-to-scale references are shown; rather, individual elements may be exaggerated for a better understanding.

[0056] FIGS. 1 to 5 show schematic sectional illustrations of steps of an exemplary embodiment of a method described here for producing workpieces described here;

[0057] FIGS. 6 and 7 show schematic sectional illustrations of steps of an exemplary embodiment of a method described here for producing workpieces described here;

[0058] FIGS. 8 to 10 show schematic sectional illustrations of steps of an exemplary embodiment of a method described here for producing workpieces described here;

[0059] FIGS. 11 and 12 show schematic sectional illustrations of steps of an exemplary embodiment of a method described here for producing workpieces described here;

[0060] FIGS. 13 to 15 show schematic sectional illustrations of steps of an exemplary embodiment of a method described here for producing workpieces described here;

[0061] FIG. 16 shows schematic sectional illustrations of individual steps of an exemplary embodiment of a method described here for producing workpieces described here;

[0062] FIGS. 17 and 18 show schematic sectional illustrations of exemplary embodiments of workpieces described here; and

[0063] FIGS. 19 and 20 show schematic plan views of exemplary embodiments of workpieces described here.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

[0064] An exemplary embodiment of a method for marking a workpiece 1 is illustrated in FIGS. 1 to 5. According to FIG. 1, the workpiece 1 is provided which still has no marking. The workpiece 1 is preferably a steel sheet.

[0065] In the step of FIG. 2, a raw material 2 for the later marking is applied in places onto a workpiece surface 10. The application of the raw material 2 is, for example, printing. The raw material 2 is preferably an ink or a paste. The raw material 2 is applied in the shape how the finished marking is to be designed later, seen in plan view. After application, the raw material 2 is preferably wiping-resistant.

[0066] FIG. 3 shows that a hot forming of the workpiece 1 with the raw material 2 takes place, for example, in a heated press mold 5. With the hot forming, the raw material 2 is simultaneously heated so that the marking 3 is formed. In this case, a component of the raw material 2 preferably melts and is fixedly connected to the workpiece surface 10. Alternatively, a component of the raw material 2 reacts on the workpiece surface 10 with a material of the workpiece 1. As a result, the marking 3 is permanently and materially bonded to the workpiece 1.

[0067] As shown in FIG. 3, a scaling layer 4 is optionally formed on the workpiece surface 10. The scaling layer 4 is preferably restricted to regions next to the marking 3. In particular, the marking 3 is made of a material that is not oxidized or not significantly oxidized or reduced during hot forming.

[0068] In the step of FIG. 4, balls 6, for example, of stainless steel, were shot onto the workpiece surface 10, for example, by means of air pressure or by means of a drum in which the workpiece 1 is located. The balls 6 impact equally on the marking 3 and on regions next to the marking 3. As also in all other exemplary embodiments, a sand blasting can be used instead of or in addition to a shot peening.

[0069] The shot peening and/or the sand blasting is preferably carried out in accordance with DIN 8200. Preferably, blasting agents 6 with the following properties are used: [0070] material group for the blasting agent 6: metallic, mineral, synthetic-organic, [0071] density of the blasting medium 6: preferably between 1 g/cm.sup.3 and 9 g/cm.sup.3 inclusive, [0072] hardness of the blasting medium 6 in the case of a metal: HV 30 to 1000, or hardness of the blasting medium 6 in the case of a mineral: MOHS≥3.

[0073] If, as an alternative or in addition to the shot peening and/or for sand blasting, a sliding grinding is used as surface treatment, the sliding grinding is preferably carried out in accordance with DIN 8589. A size of abrasive bodies is preferably between 0.5 mm and 50 mm. A sliding grinding is used, for example, for post-treatment of press-hardened metal sheets.

[0074] FIG. 5 shows the workpiece 1 after the shot peening. As a result of the shot peening, many impressions 7 of the balls 6 result in the workpiece surface 10, that is to say the workpiece surface 10 has a characteristic, pinned structure. This dented structure extends over the marking 3.

[0075] This structure with the impressions 7 is preferably also present below the marking 3 in the workpiece surface 10. The marking 3 preferably forms this structure. This means that the structure of the workpiece surface 10 is preferably recognizable on a marking side facing away from the workpiece surface 10.

[0076] Deviating from the illustration in FIG. 5, the scaling layer 4 can also be present at least partially on the workpiece 1 after the surface treatment.

[0077] A further method is shown schematically in FIGS. 6 and 7. According to FIG. 6, the workpiece 1 with the raw material 2 is placed in a furnace 8. The furnace 8 is, for example, an induction furnace or a flame furnace. As a result of heating in the furnace 8, the marking 3 is created from the raw material 2.

[0078] Deviating from the illustration in FIG. 6, the workpiece 2 can have already been deformed before the application of the raw material 2, and thus before the introduction into the furnace 8. This deformation can thus be carried out before or even only after the raw material 2 has been applied. Alternatively, only the workpiece 1 with the finished marking 3 is deformed after the process step in the furnace. This optional downstream deformation is not shown in FIG. 6.

[0079] In the subsequent step, see FIG. 7, a shot peening again takes place. In this case, the workpiece surface 10 is hardened, for example. In addition, it is possible for a slight removal of material from the workpiece surface 10 due to the shot peening, wherein the marking 3 is preferably not significantly impaired by the shot peening.

[0080] Otherwise, the explanations regarding FIG. 4 apply to FIG. 7, and vice versa.

[0081] A further method is illustrated in connection with FIGS. 8 to 10. As shown in FIG. 8, the workpiece 1 is composed of a base material 11, for example, a steel sheet, and a coating 12. Preferably, the entire workpiece surface 10 is formed by the coating 12. Such a construction of the workpiece 1 can also be present in all other exemplary embodiments.

[0082] The marking 3 is applied to the coating 12, for example, as described in connection with FIG. 2, 3 or 6.

[0083] According to FIGS. 9 and 10, the shot peening is carried out, preferably analogously to FIGS. 4 and/or 7. In the variant of FIG. 9, the impressions 7 are formed in the coating 12, with the impressions 7 preferably continuing as far as the base material 11. Alternatively, the impressions 7 are damped by the coating 12 and are no longer present or only present in an attenuated manner in the base material 11. In this case, the coating 12 remains present, so that the shot peening does not or does not significantly remove the coating 12.

[0084] In the variant of FIG. 10, on the other hand, the coating 12 is specifically removed by the shot peening. In this case, the marking 3 preferably acts as a type of protective layer, so that the coating 12 remains below the marking 3. Deviating from the illustration in FIG. 10, it is not absolutely necessary for the impressions 7 to continue in the region of the marking 3 from the base material 11 to the marking 3.

[0085] The coating 12 is, for example, a scaling protection layer, for example, of an aluminum-silicon alloy. A thickness of the scaling protective layer is, for example, at least 100 nm or 250 nm or 1 μm and/or at most 30 μm or 10 μm or 2 μm. A preferred composition of the scaling layer is: 87% Al, 10% Si and 3% Fe. The preferred thickness of the scaling layer is 1.5 μm. These properties preferably also apply to coatings 12 in other exemplary embodiments.

[0086] The marking 3 is preferably thicker than the coating 12. This is preferably also true in all other exemplary embodiments.

[0087] In the method of FIGS. 11 and 12, the finished marking 3 is exposed to an etching agent 9, see FIG. 11. The marking 3 is not influenced or not significantly influenced by the etching agent 9, so that the marking 3 overcomes the etching and remains without loss of function. However, by means of the etching means 9, material removal from the base material 11 takes place, see FIG. 12. Thus, under the regions for the marking 3, a plurality of bases 13 are produced from the base material 11. Unlike in FIG. 12, smaller undercuts can also extend below the regions with the marking 3, so that the bases 13 can be narrower than the regions with the marking 3.

[0088] Optionally, a coating on the base material 11 is also present in the method of FIGS. 11 and 12. The etching may then be limited to the coating or may concern both the coating and the base material 11.

[0089] The composition of the raw material 2 and of the marking 3 is described in more detail in FIGS. 13 to 15. The statements relating to FIGS. 13 to 15 apply equally to all other exemplary embodiments. In the steps of FIGS. 13 to 15, the workpiece surface 10 is formed directly by the base material or also by the coating.

[0090] According to FIG. 13, the raw material 2 is applied to the workpiece 1 as a paste or as an ink. In this case, the workpiece surface 10 preferably has a roughening 14, which results, for example, from a rolling of the workpiece 1. In particular on account of a surface tension, it is possible for the raw material 2 to rest on tips of the roughening 14, but not to contact the workpiece 1 over its entire surface.

[0091] The raw material 2 is preferably composed of an adhesion promoter 31, for example, a low-melting glass, of pigment particles 32, preferably phosphor particles or alternatively ceramic pigments, and of a binder and/or solvent 33.

[0092] The raw material 2 is preferably an ink-jet-capable ink, in particular having a viscosity in the range of from 1 mPas to 20 mPas and/or with a surface tension in the range from 20 mN/m to 60 mN/m, especially at the temperature at which the raw material 2 is printed.

[0093] The ink-jet-capable raw material 2 is preferably composed as follows: [0094] 1% by weight to 10% by weight, with respect to the total formulation of the raw material 2: solids, [0095] 75% by weight to 95% by weight, with respect to the total formulation: solvent, [0096] 0.1% by weight to 10% by weight, with respect to the solids in the raw material 2: binder, [0097] 0.1% by weight to 10% by weight, with respect to the solids in the raw material 2: dispersant, [0098] 1% by weight to 10% by weight, with respect to the total formulation: additives.

[0099] If the raw material 2 is a screen printing paste, the raw material 2 preferably has a viscosity between 1 dPas and 200 dPas at the application temperature and is composed, in particular, as follows: [0100] 40% by weight to 80% by weight: solids, [0101] 10% by weight to 35% by weight: solvent, [0102] 1% by weight to 10% by weight: binder, [0103] 1% by weight to 10% by weight: dispersant, [0104] 1% by weight to 5% by weight: plasticizer, and [0105] 1% by weight to 5% by weight: additives.

[0106] FIG. 14 shows the marking 3 resulting by a temperature treatment from the raw material 2. In this case, the adhesion promoter 31 forms a matrix material into which the pigment particles 32 are preferably embedded and uniformly distributed. A coherent marking field 39 is thus formed by the temperature treatment. The marking field 39 can be more even on a side facing away from the workpiece surface 10 than the workpiece surface 10. That is, by means of the marking 3, the workpiece 1 is smoother in places of the marking 3 than in other regions of the workpiece surface 10.

[0107] Unlike in FIG. 14, a plurality of islands 38, each comprising one or more of the pigment particles 32, are formed by the temperature treatment in FIG. 15. The islands 38 preferably also each comprise the adhesion promoter 31. As a result of this structure of the marking 3, the workpiece 1 is optionally rougher in the region of the marking 3 than in other regions of the workpiece surface 10.

[0108] In the method step of FIG. 16, it is illustrated that the marking 3 is still a continuous, coherent marking field 39 at the beginning of the shot peening with the balls 6; see the left-hand side of FIG. 16. It is possible that the marking 3 is split into individual islands 38 by the shot peening; see the right-hand side of FIG. 16. However, the marking field 39 remains clearly identifiable as such.

[0109] To simplify the illustration, the impressions 7 in FIG. 16 are not shown. In addition, the coating on the base material can also be present in FIG. 16.

[0110] The fragmentation of the marking 3 during the shot peening illustrated in FIG. 16 optionally also occurs in the methods and workpieces 1 of FIGS. 1 to 10, 17 and 18. Alternatively, the markings 3 in FIGS. 1 to 10, 17 and 18 each remain as closed, gapless or predominantly gapless marking fields.

[0111] FIGS. 17 and 18 each show workpieces 1 after the surface treatment. According to FIG. 17, the marking 3, in particular by the shot peening, is partially pressed into the coating 12. Deviating from the illustration in FIG. 17, the marking 3 can also be pressed through the entire coating 12 and can touch the base material 11. In addition, it is possible that the coating 12 and the marking 3 terminate flush with one another.

[0112] In FIG. 18, the marking 3 is completely or substantially completely pressed into the workpiece surface 10. Thus, the marking 3, which is preferably split as shown in FIG. 16, on the right side, is flush or approximately flush with the base material 11 and is partially or completely pressed into the base material 11.

[0113] FIGS. 19 and 20 illustrate that the marking 3 is designed as a code in plan view, in particular as machine-readable code. By means of the marking 3, for example, a lettering, a bar code or a QR code is formed.

[0114] In this case, the marking 3 can be formed by the coherent marking fields 39 present as closed layers; see FIG. 19. Alternatively, the marking fields 39 are composed of a plurality of adjacent islands 38, see FIG. 20.

[0115] The invention described here is not limited by the description on the basis of the exemplary embodiments. Rather, the invention encompasses any novel feature and any combination of features, which in particular includes any combination of features in the claims, even if this feature or this combination itself is not explicitly specified in the claims or exemplary embodiments.