High-Temperature Galvanizing Process for Ferrous Material Parts

Abstract

The invention relates to a method for high-temperature galvanization of ferrous material parts (10). The method comprises the production of zinc melt (12). The method further comprises saturating the iron concentration of the zinc melt (12) so that it is iron-saturated. In addition, the method comprises producing an undersaturation of the iron concentration of the zinc melt (12) so that it is iron-undersaturated. The method further comprises dipping the ferrous material parts (10) in iron-undersaturated zinc melt (12), whereby a galvanization layer (14) is formed on the ferrous material parts (10).

Claims

1. A method for high-temperature galvanization of ferrous material parts (10), comprising: generating a zinc melt (12); saturating the iron concentration of the zinc melt (12) so that it is iron-saturated; establishing an undersaturation of the iron concentration of the zinc melt (12) so that it is iron-undersaturated; and dipping the ferrous material parts (10) into the iron-undersaturated zinc melt (12), wherein a galvanization layer (14) is formed on the ferrous material parts (10).

2. A method according to any one of the preceding claims, wherein the iron-undersaturated zinc melt (12) is not in equilibrium in terms of its iron concentration.

3. A method according to any one of the preceding claims, wherein the iron-undersaturated zinc melt (12) is only temporarily iron-undersaturated, so that the zinc melt (12) automatically moves back to an iron-saturated state or at least towards an iron-saturated state after the ferrous material parts (10) have been dipped into the iron-undersaturated zinc melt (12).

4. A method according to any one of the preceding claims, further comprising: measuring the thickness of the galvanization layer (14) formed due to the dipping into the iron-undersaturated zinc melt (12); comparing the measured layer thickness with a threshold value; and increasing the undersaturation of the iron concentration of the zinc melt (12) so that it is more iron-undersaturated if the measured layer thickness exceeds the threshold value.

5. A method according to any one of the preceding claims, wherein establishing the undersaturation of the iron concentration of the zinc melt (12) comprises a reduction of the iron concentration.

6. A method according to claim 5, wherein at least one iron-binding device (16), which selectively binds iron from the zinc melt (12), is brought into contact with the zinc melt (12) in order to reduce the iron concentration.

7. A method according to any one of claims 1 to 4, wherein the iron concentration of the undersaturation of the iron concentration of the zinc melt (12) is essentially constant while being established.

8. A method according to any one of the preceding claims, wherein the iron saturation concentration of the zinc melt (12) is changed when establishing an undersaturation of the iron concentration.

9. A method according to any one of the preceding claims, wherein establishing the undersaturation of the iron concentration of the zinc melt (12) comprises increasing the temperature of the zinc melt (12).

10. A method according to claim 9, wherein increasing the temperature of the zinc melt (12) happens faster than a post-saturation of the zinc melt (12) with iron after the temperature has been increased, so that the iron concentration deviates at least temporarily from an iron saturation concentration of the zinc melt (12) at an elevated temperature due to the temperature increase.

11. A method according to claim 9 or 10, wherein the temperature of the zinc melt (12) is gradually increased, so that a plurality of different target temperatures of the zinc melt (12) are successively set, and wherein, at a plurality of different target temperatures of the zinc melt (12), respective ferrous material parts (10) are dipped into the zinc melt (12) in order to form a galvanization layer (14) thereon.

12. A method according to any one of claims 9 to 11, wherein increasing the temperature of the zinc melt (12) comprises a temperature change of at least 3 K, in particular of at least 4 K and optionally of at least 5 K and/or a temperature change of at most 15 K, in particular of at most 10 K and optionally of at most 7 K.

13. A method according to any one of the preceding claims, wherein the undersaturation of the iron concentration of the zinc melt (12) is adjusted in such a way that, after an initial formation of a galvanization layer (14) on the ferrous material parts (10) during dipping the ferrous material parts (10) into the zinc melt (12), a rate at which the galvanization layer (14) grows and a rate at which the formed galvanization layer (14) is skimmed essentially correspond.

14. A method according to any one of the preceding claims, wherein the undersaturation of the iron concentration of the zinc melt (12) is adjusted in such a way that a resulting layer thickness of the galvanization layer (14) formed upon dipping the ferrous material parts (10) into the iron-undersaturated zinc melt (12) is, at least for total dipping periods between a minimum period and a maximum period, essentially independent of the total dipping duration, wherein the minimum period and the maximum period are each in the order of minutes and differ from each other in the order of minutes.

15. A method according to any one of the preceding claims, wherein the zinc melt (10) has a temperature of at least 500 C., in particular of at least 540 C. and optionally of at least 560 C. and/or a temperature of at most 700 C., in particular of at most 650 C. and optionally of at most 620 C.

16. A method according to any one of the preceding claims, wherein heat is supplied to the zinc melt (12) by means of inductive heating.

17. A method according to any one of the preceding claims, wherein the zinc melt (12) is generated in a ceramic boiler (18).

18. A method according to any one of the preceding claims, wherein a layer thickness of the galvanization layer (14), which is formed when the ferrous material parts (10) are dipped into the iron-undersaturated zinc melt (12), is at most 200 m, in particular at most 150 m and optionally at most 100 m, and/or is at least 30 m, in particular at least 50 m and optionally at least 80 m, on flat and/or uniform surfaces of the ferrous material parts (10), on which the layer thickness is essentially free of accumulation effects due to a geometry of the ferrous material parts (10).

19. A method according to any one of the preceding claims, further comprising: re-saturation of the iron concentration of the zinc melt (12), so that it is once again iron-saturated; dipping further ferrous material parts (10) into the now iron-saturated zinc melt (12), whereby a galvanization layer (14) is formed on the further ferrous material parts (10); re-producing an undersaturation of the iron concentration of the zinc melt (12) so that it is again iron-undersaturated; and dipping further ferrous material parts (10) into the now again iron-undersaturated zinc melt (12), whereby a galvanization layer (14) is formed on the further ferrous material parts (10).

20. A galvanization line (20) comprising a boiler (18) adapted to accommodate a high-temperature zinc melt and a heating device (22) provided to supply the boiler (18) with the amount of heat required to generate and maintain the high-temperature zinc melt, wherein the boiler (18) and the heating device (22) are specifically adapted to perform therewith a method according to any one of the preceding claims.

21. A galvanization line (20) according to claim 20, further comprising a control unit (24) provided to control components of the galvanization line (24) for the at least partially automated execution of a method according to any one of claims 1 to 19.

22. A control unit (24), provided to control components of a galvanization line (20) according to claim 20 for the at least partially automated execution of a method according to any one of claims 1 to 19.

23. A computer-readable medium (26) on which program code is stored which is provided for the at least partially automated execution of a method according to any one of claims 1 to 19 when executed by a computer.

24. Program code which, when executed by a computer, is provided for the at least partially automated execution of a method according to any one of claims 1 to 19.

Description

[0061] Subsequently, the present invention is described by way of example with reference to the attached figures. The drawing, the description and the claims contain numerous features in combination. The skilled person will expediently consider the features individually as well and use them sensibly in combination within the scope of the claims. It shows a:

[0062] FIG. 1a schematic representation of a galvanization line;

[0063] FIG. 2a schematic representation of a section of a galvanized ferrous material part;

[0064] FIG. 3a schematic flow chart of a method for high-temperature galvanization of ferrous material parts;

[0065] FIG. 4a schematic representation of an alternative galvanization line;

[0066] FIG. 5a schematic flow chart of an alternative method for high-temperature galvanization of ferrous material parts;

[0067] FIG. 6 schematic diagram illustrating the relation between a temperature of zinc melt and an iron saturation concentration of the zinc melt;

[0068] FIG. 7 schematic diagram illustrating a temperature curve of zinc melt over time during the method;

[0069] FIG. 8 schematic diagram illustrating a time curve of a degree of iron desaturation during the method;

[0070] FIG. 9 schematic flow chart illustrating the procedure for measuring a layer thickness;

[0071] FIG. 10 schematic diagram illustrating a temperature curve of zinc melt over time during a longer period of the method;

[0072] FIG. 11 schematic diagram illustrating a time curve of a degree of iron desaturation during a longer period of the method;

[0073] FIG. 12 schematic representation of another alternative galvanization line; and

[0074] FIG. 13 schematic representation of a control unit for a galvanization line.

[0075] FIG. 1 shows a galvanization line 20. This comprises a ceramic boiler 18, which is set up to hold a zinc melt 12. The galvanization line 20 is set up to carry out high-temperature galvanization.

[0076] The galvanization line 20 comprises a dipping device 28 with a holding unit 30 to which the ferrous material parts 10 that are to be galvanized are attached. In the present case, the holding unit 30 has several beams on which the ferrous material parts 10 are suspended. The dipping device 28 is designed to lower and raise the holding unit 30, whereby the ferrous material parts 10 can be dipped into the zinc melt 12 for galvanization and removed from it again.

[0077] The galvanization line 20 further comprises a heating device 22, which is only shown schematically. In the exemplary embodiment according to FIG. 1, the heating device 22 comprises one or more gas burners which are directed onto a surface of the zinc melt 12. Heat can be supplied to the zinc melt 12 by means of these gas burners.

[0078] The zinc melt 12 is a high-temperature zinc melt and has a temperature of, for example, 580 C. during operation. In the present case, the temperature can be adjusted by suitably controlling the heating device 22. If necessary, the temperature of the zinc melt 12 can be changed.

[0079] In general, in the embodiments of the invention, zinc melt with a zinc content of at least 90%, in some cases at least 95% or even at least 98% can be used. The zinc melt can be in accordance with DIN EN ISO 1461, DASt 022 or also specific requirements of customers and/or associations.

[0080] FIG. 2 shows a schematic representation of a ferrous material part 10 that has already been galvanized. A galvanization layer 14 is present on the ferrous material part 10, which was formed during galvanization in the zinc melt 12. At the point marked with a double arrow, the galvanization layer 14 has a layer thickness of approximately 50 m, whereby this value is to be understood as purely exemplary. Depending on the ferrous material part, expected requirements, customer-specific wishes etc., other layer thicknesses can be selected.

[0081] The layer thickness of the galvanization layer 16 is very homogeneous due to the favorable flow behavior of the zinc during high-temperature galvanization and there are only slight accumulation effects at internal edges, recesses, in threads, etc. at most. The specified layer thickness is therefore to be understood as the general layer thickness of the galvanization layer 14, but in the case shown it nevertheless refers to a flat and/or uniform surface of the ferrous material part 10, on which the layer thickness is essentially free of such accumulation effects. The zinc is only limited in its flow in pots or on larger unevennesses, such as weldseams that have not been leveled or burrs from previous processing steps and corresponding deviations in the zinc layer thickness can occur.

[0082] FIG. 3 shows a schematic flow chart of a method for high-temperature galvanization of the ferrous material parts 10. The method can be carried out using the galvanization line 20.

[0083] In a first step S1, the zinc melt 12 is produced. Zinc and, if necessary, additives are melted. In a second step S2, the iron concentration of the zinc melt 12 is saturated so that it is iron-saturated.

[0084] For this purpose, pure iron or ferrous zinc is added to the zinc melt 12 as required. This can be done, for example, until hard zinc begins to precipitate or the added iron no longer migrates into the zinc melt. It should be noted that the melting point of iron is more than 1,000 K higher than that of zinc, so iron only enters the zinc melt up to its saturation concentration, but no liquid alloy is formed, as can be the case for alloys whose temperature exceeds the melting points of all components, provided the different metals do not separate due to differing densities.

[0085] Subsequently, in step S3, an undersaturation of the iron concentration is established so that the zinc melt 12 is iron-undersaturated. In the embodiment according to FIG. 1, the galvanization line 20 has an iron-binding device 16, which is optionally brought into contact with the zinc melt for this purpose. The iron-binding device 16 comprises an iron-binding unit 32. This can, for example, be arranged in a housing, the interior of which can optionally be brought into contact with the zinc melt 12, for example by motorized lifting of a wall and/or a base of the boiler 18. As an alternative, it can also be provided that zinc melt 12 is passed through and/or pumped through the iron-binding device 16 and thereby comes into contact with the iron-binding unit 32.

[0086] The iron-binding unit 32 has an iron-binding material that forms a large surface area. This is only indicated schematically in FIG. 1.

[0087] Preferably, the iron-binding material is structured, in particular microstructured, and thus has a greatly increased surface area on which large quantities of iron can be deposited.

[0088] By bringing the iron-binding device 16 into contact with the zinc melt 12, iron is removed from the zinc melt 12 and thus the iron concentration of the zinc melt is reduced. Thus, the iron concentration is lower than the iron saturation concentration, which serves as a starting point for initiating step S3. The zinc melt 12 is therefore iron-undersaturated.

[0089] The degree of undersaturation can be adjusted by controlling the contact of the zinc melt with the iron-binding device 16. For this purpose, a contact duration, a flow rate, a surface of the iron-binding unit 32 brought into contact, or the like can be varied.

[0090] Referencing FIG. 3 again, the method further comprises step S4 in which the ferrous material parts 10 are dipped into the iron-undersaturated zinc melt 12, whereby a galvanization layer 14 (cf. FIG. 2) is formed on the ferrous material parts 10.

[0091] The formation of the galvanization layer is thus determined by the two aforementioned processes: the loss of iron from the corresponding ferrous material part 10 into its growing galvanization layer 14 as well as the loss of iron from the growing galvanization layer 14 into the zinc melt 12. Depending on the selected undersaturation, these processes can take place at essentially the same rate, making the resulting layer thickness largely independent of the dipping time of the ferrous material parts 10.

[0092] Optionally, the method comprises pre-treatment steps that are carried out before dipping the ferrous material parts 10. This may be carried out in parallel with steps S2 and S3.

[0093] Optionally, the method further comprises another step in which the ferrous material parts 10 are removed from the zinc melt 12 after a predetermined dipping time. The galvanized ferrous material parts 10 can be cooled after dipping. Chromatization and/or passivation may also be provided. In addition, various post-treatment steps may be provided, for example for removing the ferrous material parts 10 from the holding unit 30 and/or for polishing and/or grinding the galvanized ferrous material parts 10.

[0094] FIG. 4 shows an alternative galvanization line 20. Analogously to the galvanization line 20 according to FIG. 1, the alternative galvanization line 20 has a ceramic boiler 18, which holds zinc melt 12. It further contains a dipping device 28 to which the ferrous material parts 10 that are to be galvanized are attached. In this regard, reference is made to the description of the dipping device 28 in FIG. 1.

[0095] The alternative galvanization line 20 has an inductive heating device 22. In the case shown, the heating device 22 is attached to the side of the boiler 18 and the zinc melt 12 can flow through it. Heat is thus supplied inductively to the zinc melt 12 within the heating device 22. The inductive heating used enables a very homogeneous temperature distribution to be achieved in the zinc melt 12.

[0096] The alternative galvanization line 20 further comprises a temperature measuring unit 35. The temperature measuring unit 35 may comprise and/or be configured as one or more thermocouples, as well as another type of suitable temperature sensor. The temperature measuring unit 35 may comprise a protective housing for the thermocouples and/or temperature sensors, which preferably continuously send a signal to a control unit of the galvanization line 20 (cf. FIG. 13). In the present embodiment, the temperature measuring unit 35 expediently comprises at least two thermocouples so that they can monitor each other and trigger an alarm or stop the heating in the event of corresponding deviations. The same applies when defined process limits are reached.

[0097] It is understood that a corresponding temperature measuring unit can also be provided in the embodiment according to FIG. 1. FIG. 5 shows a schematic flow chart of an alternative method for the high-temperature galvanization of ferrous material parts 10. This method can be carried out using the alternative galvanization line 20.

[0098] Similar to the method described above, the alternative method also comprises step S1 in which the zinc melt 12 is produced, step S2 in which the iron concentration of the zinc melt is saturated, step S3 in which an iron undersaturation is established, and step S4 in which the ferrous material parts 10 are dipped into the iron-undersaturated zinc melt 12, whereby a galvanization layer is formed on the ferrous material parts 10.

[0099] However, there are differences to the method described above with regard to the way in which the undersaturation is achieved in step S3. This emerges from the following description, whereby it is expressly pointed out that the mere mention of a fact does not mean that it must differ from the aforementioned method.

[0100] According to the alternative method, the iron-undersaturated zinc melt 12 is not in equilibrium with regard to its iron concentration. Instead, it is only temporarily iron-undersaturated. In the present case, this is controlled via the temperature of the zinc melt 12.

[0101] For a better understanding, the relationship between the temperature of a zinc melt and its iron saturation concentration is shown schematically in FIG. 6. Specific numerical values are not important for the basic principle, which is why the axes of the diagram are shown without units. The decisive factor is that the iron saturation concentration also increases with increasing temperature. The hotter the zinc melt, the more iron it can consequently absorb.

[0102] For explanation, reference is made below to FIG. 7 and FIG. 8. The time axes of the two schematic diagrams shown correspond to each other.

[0103] According to the alternative method, the temperature of the iron-saturated zinc melt 12 is increased comparatively erratic. This corresponds to the first steep slope of the temperature curve in FIG. 7, for example, starting from a temperature of 550 C. for the zinc melt. As shown in FIG. 8, this rise in temperature leads to an undersaturation of the iron concentration of the zinc melt 12. For this, we refer once more to the relation shown in FIG. 6. While the iron concentration is essentially constant, this iron concentration essentially corresponds to the saturation concentration before the temperature increase but is significantly lower after the temperature increase. Hereby the degree of desaturation of the zinc melt 12 is increased, as can be seen in FIG. 8.

[0104] In the case shown, the temperature is increased by 5 K by way of example. However, other values are also conceivable, as described above. In general, the temperature increase can be selected in such a way that the iron concentration after the temperature increase is a few percentage points below the new iron saturation concentration.

[0105] The ferrous material parts 10 can now be dipped into the iron-undersaturated zinc melt 12 (step S4). The total dipping time is 10 minutes, for example. Within the total dipping time, the temperature of the ferrous material parts 10 first adjusts to the temperature of the zinc melt 12. Subsequently, the aforementioned processes begin to take place at an approximately constant rate during the formation of the galvanization layer. The galvanization layer can then form in the manner described largely independently of the dipping time. A correspondingly galvanized ferrous material part 10 will correspond approximately to the ferrous material part 10 shown in FIG. 2.

[0106] As shown in FIG. 7, the temperature can slightly drop after the increase.

[0107] Depending on how the temperature of the zinc melt 12 is controlled and/or regulated, this effect can vary in intensity. However, a falling temperature is always accompanied by a falling iron saturation concentration (see FIG. 6), which leads to a falling degree of desaturation.

[0108] Another effect that can lead to a decreasing degree of desaturation is the loss of iron from the ferrous material parts 10 and, if applicable, from the dipping device 28 into the zinc melt 12. Any hard zinc can also contribute. Iron that enters the zinc melt 12 in a saturated or oversaturated state forms iron-zinc crystals with zinc of the zinc melt 12, which settle at the bottom of the boiler 18 due to their higher density than hard zinc. In the undersaturated state of the zinc melt 12, iron from the hard zinc enters the zinc melt 12, gradually increasing its iron concentration. This effect is superimposed on the effect of a slight drop in temperature. Even if the temperature is kept completely constant after it has been increased, the degree of desaturation will gradually decrease due to this loss of iron or the introduction of iron from the hard zinc, and the zinc melt 12 will consequently move towards its iron saturation concentration. It is therefore important for the alternative method that the temperature increase takes place more quickly than a re-saturation of the zinc melt 12.

[0109] After the desired total dipping time has elapsed, the ferrous material parts 10 are removed from the zinc melt 12. Step S5 can be provided for this purpose.

[0110] A further method step can then follow, in which the temperature of the zinc melt 12 is rapidly increased again. As a result, the degree of iron desaturation increases again and further ferrous material parts 10 can be galvanized. FIG. 7 and FIG. 8 show several of such galvanization cycles, each of which includes galvanization in the temporarily iron-undersaturated zinc melt 12. Accordingly, steps S3 to S5 can be carried out several times, if necessary, as indicated by the dashed arrow in FIG. 5. This means that several galvanization processes take place consecutively in iron-undersaturated zinc melt, whereby the temperature is gradually increased so that a galvanization process can take place at each stage.

[0111] In order to determine a suitable degree of desaturation or a suitable temperature increase, a layer thickness D of the formed galvanized layer 14 can be measured after a galvanization cycle. The relevant procedure is explained with reference to FIG. 9. The flow chart shown can serve as the basis for a regulation or adjustment. The measured layer thickness D is compared with a lower threshold value T.sub.1 and/or an upper threshold value T.sub.2. If a target layer thickness is 50 m, for example, the lower threshold value can be 40 m and the upper threshold value can be 60 m, although other values are also possible according to the invention. If the measured layer thickness D is below the lower threshold value T.sub.1, it can be concluded that the degree of desaturation and thus the loss of iron into the zinc melt during galvanization is too high. It is possible to react to this by using a smaller temperature rise, which in turn results in a comparatively lower degree of desaturation. If, however, the measured layer thickness D is above the upper threshold value T.sub.2, it can be concluded that the degree of desaturation and thus the loss of iron into the zinc melt during galvanization is too low. To remedy this, a higher temperature increase can be used in this case, which in turn results in a comparatively higher degree of desaturation.

[0112] It is understood that in the case of the method according to FIG. 3 or the control of undersaturation by removing iron from the zinc melt, instead of the aforementioned changes to the temperature increases, an influence of the zinc melt can be changed instead by the iron-binding device. For example, a contact period with the iron-binding device can be increased in order to increase the degree of desaturation, or correspondingly vice versa.

[0113] Further optional steps of the alternative method are explained below with reference to FIG. 10 and FIG. 11. In principle, the method can comprise galvanization in iron-undersaturated zinc melt and galvanization in iron-saturated zinc melt. For example, one or more cycles can first be carried out in iron-undersaturated zinc melt, for example as described with reference to FIG. 7 and FIG. 8. Subsequently, one or more cycles can be carried out in iron-saturated zinc melt, for example in order to galvanize other ferrous material parts with thicker layers, for which precise layer thickness control may not be necessary.

[0114] The method can accordingly include step S6 (see FIG. 5), in which the iron concentration of the zinc melt is saturated once more. For this purpose, for example, after a final galvanization in iron-undersaturated zinc melt, there is a longer waiting period and, if necessary, iron is added until the zinc melt is no longer iron-undersaturated. This may also involve leveling the temperature. In FIG. 11, this state corresponds to the long unchanged process after the first peaks in the degree of iron desaturation or the first multi-stage temperature increase.

[0115] In a step S7, further ferrous material parts 10 can be dipped into the now iron-saturated zinc melt. It is then galvanized in the conventional manner, meaning without iron undersaturation. Step S7 can include several dipping processes while the zinc melt is essentially unchanged.

[0116] Subsequently, an iron undersaturation can be established once more in order to galvanize ferrous material parts in iron-undersaturated zinc melt.

[0117] Accordingly, the method can return to step S3 and be carried out up to step S7 several times. This is shown in FIG. 5 by a dot-dashed arrow.

[0118] It is also understood that the methods described may comprise one or more galvanization processes in the iron-saturated zinc melt even before they are initially galvanized in the iron-undersaturated zinc melt.

[0119] At a suitable point during or after carrying out the method according to the invention, the temperature of the zinc melt 12 can be temporarily reduced in a targeted manner. This reduces the iron saturation concentration to such an extent that a current iron concentration of the zinc melt exceeds the new iron saturation concentration. This causes iron to precipitate. Hard zinc 34 is formed, which is shown schematically in FIG. 4. Due to its higher specific weight, the hard zinc 34 sinks in the zinc melt 12. It can then be extracted, whereby iron is removed from the system. The temperature of the zinc melt 12 is then increased again and further galvanization can be carried out in iron-saturated and/or iron-undersaturated zinc melt. This can mean that the method schematically illustrated in FIG. 5 can start again from the beginning.

[0120] A further alternative galvanization line 20 is shown in FIG. 12, which also has a boiler 18 that holds zinc melt 12. The methods described are also shown in the case of the further alternative galvanization line 20. It can basically be designed in the same manner as galvanization line 20 or alternative galvanization line 20. Corresponding further units and devices are omitted in FIG. 12 and only the differences between this embodiment and the other embodiments are described below.

[0121] The further alternative galvanization line 20 has a heating device 22, which comprises a number of fuel rods 36. These protrude into the boiler 18, whereby a uniform heat input can be achieved. Ferrous material parts can be, for example, dipped between and/or above the fuel rods 36.

[0122] In general, the heating rods can be introduced into the zinc melt from above or, as shown, from below. Heating elements 38, which are illustrated as spirals in FIG. 12, can be arranged in the heating rods 36 respectively. These can be gas burners, inductive heating elements, resistive heating elements, etc.

[0123] FIG. 13 schematically depicts a control unit 24, which is set up to control the described galvanization lines 20, 20, 20. The control unit 24 comprises a computer-readable medium 26 as well as a processor 40 and possibly other required electronic components such as a working memory, connections, lines, etc. The control unit 24 can also be set up to control a user interface via which a user can, for example, enter a target temperature, a predetermined temperature curve, layer thickness thresholds, measured layer thicknesses and the like.

[0124] The computer-readable medium 26 includes program code that implements the semi-automated and, in some embodiments, automated performance of one or all of the described methods.