Abstract
A method for hot or warm forming a workpiece may comprise providing the workpiece to be formed, at least partially pretreating the workpiece, at least partially heating the workpiece to a target temperature, and at least partially forming and/or hardening the workpiece. Furthermore, the workpiece may be at least partially cleaned in a cleaning step between the pretreating and the heating of the workpiece. In some examples, at least partially cleaning the workpiece may involve brushing the workpiece, using a cleaning bath, or heating the workpiece with a first burner to a cleaning temperature. Further, one or more burners used to heat or clean the workpiece may be operated with a fuel gas and/or an oxygen-containing gas.
Claims
1.-15. (canceled)
16. A method for hot or warm forming a workpiece, the method comprising: providing the workpiece; at least partially pretreating the workpiece; at least partially cleaning the workpiece that has been at least partially pretreated; at least partially heating the workpiece that has been at least partially cleaned to a target temperature in a heating station; and at least partially forming and/or hardening the workpiece.
17. The method of claim 16 wherein at least partially cleaning the workpiece comprises at least partially treating the workpiece chemically, mechanically, and/or thermally.
18. The method of claim 16 wherein at least partially cleaning the workpiece comprises cleaning at least a portion of the workpiece in a cleaning bath.
19. The method of claim 16 wherein at least partially cleaning the workpiece comprises brushing the workpiece.
20. The method of claim 16 further comprising transporting the workpiece as the workpiece is at least partially cleaned.
21. The method of claim 16 further comprising transporting the workpiece from a cleaning station to the heating station after the workpiece is at least partially cleaned and before the workpiece is at least partially heated.
22. The method of claim 16 wherein at least partially cleaning the workpiece comprises heating the workpiece with a first burner to a cleaning temperature.
23. The method of claim 22 further comprising heating the workpiece with a second burner to the target temperature.
24. The method of claim 23 wherein at least one of the first burner or the second burner is operated with a fuel gas and an oxygen-containing gas.
25. The method of claim 16 further comprising coating the workpiece with at least one of a protective material or a corrosion protection oil.
26. The method of claim 16 wherein at least partially forming and/or hardening the workpiece comprises positioning the workpiece in at least one of a forming die or a hardening die.
27. The method of claim 16 wherein the workpiece is a flat metal sheet.
28. A production plant for hot or warm forming a workpiece by at least partially pretreating the workpiece, at least partially cleaning the workpiece that has been at least partially pretreated, at least partially heating the workpiece that has been at least partially cleaned to a target temperature, and at least partially forming and/or hardening the workpiece, wherein the production plant comprises: a cleaning station for at least partially cleaning the workpiece; and a heating station for at least partially heating the workpiece to the target temperature.
29. The production plant of claim 28 further comprising a conveying mechanism.
30. The production plant of claim 28 wherein the cleaning station is structurally separate from the heating station.
Description
BRIEF DESCRIPTION OF THE FIGURES
[0024] FIGS. 1a to 1d show a method for hot or warm forming of a workpiece according to a sample embodiment of the present invention.
EMBODIMENTS OF THE INVENTION
[0025] In the various figures, the same parts are always provided with the same reference number and therefore as a rule will respectively only be mentioned or designated once.
[0026] FIGS. 1a to 1d represent a method for hot or warm forming of a workpiece 1 according to a sample embodiment of the present invention. For example, this involves a structural or chassis part of a motor vehicle, the workpiece 1 being provided as a semifabricated part, especially in the form of a tailored rolled blank or a metal sheet as shown in FIG. 1. The workpiece 1 consists, for example, of a material fabricated at least partially from a boron-manganese steel, especially 22MnB5. Thanks to the hot or warm forming, it is preferably provided that the workpiece 1 is converted into its final form as a component part. In order not to influence the properties and/or the form of the component fabricated afterwards, the workpiece 1 is subjected to a pretreatment. One example of such a pretreatment is the coating of the workpiece 1 with a corrosion protection oil or with a lubricant in order to prevent corrosion during the transport of the workpiece. Another example of the pretreatment is the application of a cutting oil to the workpiece 1 in order to facilitate a possible cutting of the sheet to size in advance of the hot or warm forming. Due to the pretreatment and other external circumstances, residues remain behind on the workpiece 1, such as those of the corrosion protection oil, the lubricant and/or the cutting oil. Upon heating of the workpiece 1 required for the hot or warm forming, these residues as contaminants would result in damage or impairment of the finished part, for example in the form of a material embrittlement. In order to avoid such impairment, it is provided that the pretreated workpiece 1 is cleaned, preferably directly before the heating of the workpiece 1 in a heating station 20, in a cleaning step. Preferably the cleaning step begins 60 seconds, preferably 20 seconds and especially preferably 5 seconds before the heating of the workpiece 1.
[0027] As an example of a cleaning step, the embodiment in FIGS. 1a to 1d shows in FIG. 1b a thermal treatment in a cleaning station 10. In the present embodiment, the cleaning station 10 comprises a burner belt or roller conveyor 4, arranged underneath the workpiece 1 being delivered by the burner belt or roller conveyor 4. Furthermore, the cleaning station 10 preferably comprises a burner 2, which is arranged above and/or beneath the transportable workpiece 1. It is furthermore provided that the burner 2 heats the workpiece 1 to a cleaning temperature. For this, the burner 2 is operated in particular with a mixture of a burner gas and an oxygen-containing gas. Furthermore, when using a burner 2 for heating the workpiece 1 to the cleaning temperature, a burner flame 3 occurs which makes direct contact with the workpiece 1 in the cleaning station 10, for example, or which is held at a distance from the workpiece. In particular, the burner belt or roller conveyor 4 has a recess 6 in one position so that the burner flame 3 can heat the workpiece 1 unhindered. Furthermore, it is provided that the workpiece 1 is heated on both sides by one burner 2 apiece, in order to free as much of the surface of the workpiece 1 as possible from residues. It is conceivable that the burner 2 is moved along a direction running perpendicular to a conveyance direction of the burner belt or roller conveyor 4, preferably in oscillating manner, in order to realize by this motion the heating along a transverse dimension of the workpiece 1. In particular, it is conceivable that the cleaning temperature is adjusted or realized by the determination of a conveyance speed with which the workpiece 1 is delivered by the burner belt or roller conveyor 4, the determination of a distance of the burner 2 from the workpiece 1 and/or by the determination of an oxygen content of the oxygen-containing gas mixed in with the fuel gas. Furthermore, it is preferably provided that the burner flame 3 of the burner 2 in the cleaning station 10 heats the workpiece 1 homogeneously, i.e., uniformly along the surface. Furthermore, it is conceivable that the cleaning station 10 comprises an exhaust air system in order to carry away the pollution gases arising during the thermal treatment by the exhaust air system. In this way, it is possible to prevent the pollutants contained in the pollution gas from being deposited on the plant parts of the cleaning station 10. In order to further prevent the pollutants contained in the pollution gas from being deposited on plant parts which are situated for example in a heating station 20, the cleaning station 10 in the depicted embodiment is structurally separate from the heating station 20, as shown in FIG. 1c.
[0028] FIG. 1c shows a heating station 20 in the form of a furnace 5, the workpiece 1 being arranged for the heating inside the preferably enclosed furnace 5. In particular, it is provided that the target temperature is greater than the cleaning temperature. Furthermore, it is provided that the workpiece 1 is heated in the heating station 20 with an additional burner or by radiant heating, the additional burner being operated preferably with a mixture of a fuel gas and an oxygen-containing gas. In particular, the additional burner in the heating station 20 is operated with a technical-grade oxygen whose oxygen content is preferably greater than 75%, especially preferably greater than 90%. For example, the heating in the heating station 20 can be used to adjust material properties of the component fabricated afterwards. For example, the workpiece 1 is specifically heated in at least a first region to a temperature below AC3, especially below AC1, in order to avoid a complete austenitization and/or at least in a second region to a temperature above AC3, in order to bring about an austenitization. It is also conceivable for the workpiece 1 to be precoated after the cleaning step and before the heating in order to ensure by this precoating the formation of an alloy layer on the surface of the workpiece 1. Furthermore, it is provided that the cleaning station 10 is connected to the heating station 20 via a conveying mechanism 4. In particular, the cleaned workpiece 1 is delivered by the conveying mechanism 4 to the furnace 5.
[0029] After the heating of the cleaned workpiece 1 it is provided that the workpiece 1 is placed in a preferably cooled forming and/or hardening die 30 and formed and/or hardened therein, as shown in FIG. 1d. In particular, the forming and/or hardening die 30 comprises a mold which is adapted to the component to be fabricated. Furthermore, it is conceivable that the conveying mechanism delivers the workpiece 1 along the conveyance direction in a production plant through the cleaning station 10 and the heating station 20 to the forming and/or hardening die 30.
LIST OF REFERENCE NUMBERS
[0030] 1 Workpiece [0031] 2 Burner [0032] 3 Burner flame [0033] 4 Conveying mechanism, burner belt, roller conveyor [0034] 5 Furnace [0035] 6 Recess [0036] 10 Cleaning station [0037] 20 Heating station [0038] 30 Forming and/or hardening die
