Patent DE-102011114691-A1 (DE)
Title: Three-dimensional partial hot-working and subsequently partial hardening of a workpiece, comprises partially heating a workpiece by a heating device to a temperature, which is greater than or equal to the workpiece-specific-temperature
Inventor: ROSTEK WILFRIED
IPC: C21D7/13
Filed: 2011-10-04
Abstract: The method comprises partially heating a workpiece (2) by a heating device to a temperature, which is greater than or equal to the workpiece-specific-temperature and smaller than a workpiece-specific melting temperature, or to a temperature range, whose lower borders are greater than or equal to the workpiece-specific-temperature and whose upper borders are smaller than the workpiece-specific melting temperature, and providing recesses (6) present in a lower die. The workpiece is introduced into a mold cavity (3) of a die press. The method comprises partially heating a workpiece (2) by a heating device to a temperature, which is greater than or equal to the workpiece-specific-temperature and smaller than a workpiece-specific melting temperature, or to a temperature range, whose lower borders are greater than or equal to the workpiece-specific-temperature and whose upper borders are smaller than the workpiece-specific melting temperature, and providing recesses (6) present in a lower die. The workpiece is introduced into a mold cavity (3) of a die press. The recesses are partially filled with first and second type cooling fluids that are present as liquids. The heated workpiece is introduced into the mold cavity of the die press and partially transformed to reduce spacing between the lower die and an upper die in such a way that a portion of the workpiece is present during the entire reforming process on or above a workpiece-specific martensite-start-temperature. The portion of the workpiece is heated to the temperature range and corresponds to a range of high hardness in the finished workpiece. After the transformation of the workpiece, the portion of the transformed workpiece reaches the temperature below the martensite-start-temperature with a cooling speed, which is greater than or equal to a workpiece-specific lower critical cooling speed. The cooling fluids and/or the recesses are covered at a lower side of the workpiece. The heated workpiece is effected by a thermal radiation in the form of saturated vapor, from which the recesses emerge due to an associated increase of volume of fluid. The cooling fluids from the recesses located in the lower and/or upper dies are yielded by a reversible reduction of the effective free volume in each case of individual recess to the mold surface of the lower and/or upper dies. The first type cooling fluid and/or the second type cooling fluid: is partially flowed between the mold surface of the lower die and a bottom side of the workpiece and/or the mold surface of the upper die and a top side of the workpiece; and taken off from the mold cavity of the die press at edge areas of the mold surface of the lower and/or upper dies or the workpiece and/or channels passing through lower and/or upper dies, where the channels are opened for the mold surface of the lower and/or upper dies. The transformed workpiece is cooled to the temperature or the temperature range below the martensite-finish-temperature. The recesses in the lower die are partially filled with the first type cooling fluids and/or the recesses in the upper die are partially filled with the second type cooling fluids. During evaporation, the cooling fluids of the first type placed at the lower side of the workpiece and/or the cooling fluids of the second type placed at the top side of the workpiece are avoided by setting appropriate parameters such as boiling point and flow rate. The cooling fluid acts as cooling water, with which the boiling point of the fluids are adjusted by an addition of simmering additives and/or additives. The cooling process comprises cooling cycles, where each of the cooling cycles comprises the introduction of cooling fluids of the first and/or second types in the recesses in the lower and/or upper dies. A ratio of the volume of the cooling fluids introduced into the recesses to the volume of the cooling fluids introduced into the mold cavity of the die press is 1:1.01-1:2. Independent claims are included for: (1) a die press; and (2) a molded component for a motor vehicle.