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EP-4735650-A1 - METHOD AND DEVICE FOR HEAT TREATING A CAST COMPONENT FOR A MOTOR VEHICLE

EP4735650A1EP 4735650 A1EP4735650 A1EP 4735650A1EP-4735650-A1

Abstract

The invention relates to a method for heat treating a cast component for a motor vehicle, in which the heat treatment comprises a solution annealing (12) and ageing (14) of the cast component. The cast component is removed from a casting mould and subjected to the solution annealing (12) to homogenise at least one alloy constituent of the cast component. The hardness of the cast component is increased by the ageing (14). At least one part of the cast component is provided with at least one coating material before the ageing (14), which can be cured by applying heat. The ageing (14) is at least partially effected by heat, which is applied to the cast component for curing the at least one coating material. The invention further relates to a device for heat treating a cast component for a motor vehicle.

Inventors

  • HUMMEL, MARC
  • KOHLHEPP, Marius

Assignees

  • AUDI AG

Dates

Publication Date
20260506
Application Date
20240612

Claims (10)

  1. 1. Method for heat treating a cast component (10) for a motor vehicle, in which the heat treatment comprises solution annealing (12) and ageing (14) of the cast component (10), wherein the cast component (10) is removed from a casting mold and subjected to solution annealing (12) to homogenize at least one alloy component of the cast component (10), and wherein the ageing (14) increases a hardness of the cast component (10), characterized in that at least a partial area of the cast component (10) is provided with at least one coating material prior to ageing (14), which can be hardened by applying heat, wherein the ageing (14) is at least partially brought about by the heat with which the cast component (10) is applied to harden the at least one coating material.
  2. 2. Method according to claim 1, characterized in that the cast component (10) is removed from the casting mold by means of a handling device, in particular provided by at least one robot (18), wherein the cast component (10) is introduced into a heating device (20) by means of the handling device, and wherein the heating device (20) heats the cast component (10) to a temperature at which the solution annealing (12) takes place.
  3. 3. Method according to one of the preceding claims, characterized in that the cast component (10) is heated by means of a heating device (20) emitting infrared radiation to a temperature at which the solution annealing (12) takes place, wherein a receiving space (22) of the heating device (20), into which the cast component (10) is introduced, is brought to a heating temperature which is at least 50 percent, in particular at least 75 percent, higher than the Temperature at which solution annealing (12) takes place.
  4. 4. Method according to claim 3, characterized in that a uniform heat distribution is set in the receiving space (22) by operating a plurality of infrared radiators (24) of the heating device (20), in particular providing a heating temperature of up to approximately 900 °C, and/or by means of reflection elements (40) and/or convection elements of the heating device (20).
  5. 5. Method according to claim 3 or 4, characterized in that the cast component (10) brought to the temperature to be set for the solution annealing (12) by means of the heating device (20) is introduced into a temperature-maintaining device (42), in particular designed as a circulating air furnace, in which the temperature to be set for the solution annealing (12) is maintained.
  6. 6. Method according to claim 5 in its dependence on claim 2, characterized in that the cast component (10) is removed from the heating device (20) by means of the handling device and is introduced into the temperature holding device (42) by means of the handling device.
  7. 7. Method according to one of the preceding claims, characterized in that the cast component (10) is subjected to solution annealing (12) for a period of time of about 2 minutes to about 6 minutes, wherein the cast component (10) is brought to a temperature of about 300 °C to about 530 °C during the period.
  8. 8. Method according to one of the preceding claims, characterized in that the cast component (10), in particular die-cast component, is made of a silicon-containing aluminum alloy.
  9. 9. Method according to one of the preceding claims, characterized in that the cast component (10) is cooled after the solution annealing (12) by exposure to water and/or air, wherein the cast component (10) is subjected to a pre-aging (34) by heating after cooling and before providing the cast component (10) with the at least one coating material.
  10. 10. Device for heat treating a cast component (10) for a motor vehicle, wherein the device has means for carrying out the method according to one of the preceding claims.

Description

Method and device for heat treating a cast component for a motor vehicle DESCRIPTION: The invention relates to a method for heat treating a cast component for a motor vehicle, in which the heat treatment comprises solution annealing and ageing of the cast component. The cast component is removed from a casting mold and subjected to solution annealing to homogenize at least one alloy component of the cast component. Ageing increases the hardness of the cast component. The invention further relates to a device for heat treating a cast component for a motor vehicle. DE 10 2010 009 118 A1 describes a method and a device for heat treatment of light metal die-cast parts by solution annealing, cooling and ageing. The cast parts are solution annealed using infrared rays directly after removal from the mold or while still in the mold before removal, then quenched and age-hardened. Naturally hard alloys can be used to produce aluminum die-cast components, which reach their final strength immediately after casting or pouring. Such naturally hard alloys do not become harder through subsequent heat treatment or exposure to heat. Furthermore, hardenable alloys can be used to produce aluminum die-cast components, which undergo at least one heat treatment step linked to the casting in order to achieve certain final properties. The hardenable alloys are similar to the naturally hard alloys. in terms of the strength that can be achieved, but also in terms of formability. This is particularly true if the alloy is an aluminum alloy containing silicon. Hardenable alloys are therefore preferable if die-cast components with thin walls and the lowest possible weight are to be produced, as can be the case in particular in the production of cast components for motor vehicles. There are various process routes for the heat treatment of cast components made from hardenable alloys. In the so-called T5 heat treatment, the cast component is only aged in a separate step after casting, i.e. after removal from the mold, and solution annealing for the purpose of homogenizing the material is omitted. One advantage of this variant or process route is that it is a comparatively lean process, through which high strengths can still be achieved. However, this variant does not exploit the maximum possible properties, especially with regard to the deformability of the cast component produced. In particular, when an aluminum alloy containing silicon is subjected to T5 heat treatment, the deformability is given to a much lesser extent than would be the case if solution annealing were also carried out as a heat treatment step. Another process route or variant is the so-called T6 heat treatment or T7 heat treatment. Here, after the cast component has been cast, it is first solution annealed at high temperatures. Solution annealing is particularly effective in re-dissolving certain alloy components, which enables increased formation of precipitates during later aging. In T6/T7 heat treatment, the cast component is quenched after solution annealing and then aged until the cast component has reached the desired final strength. This type of heat treatment does indeed achieve very good properties of the cast component in terms of strength and formability. However, the separate process in the form of solution annealing requires an additional furnace system. This is associated with higher process costs. In addition, with T6 or T7 heat treatment, the high temperatures for solution annealing are maintained over a relatively long period of time, for example 10 minutes to 40 minutes. Because aluminum alloys in particular are comparatively soft, solution annealing during such a period can lead to undesirable deformations due to the dead weight of the cast component. This in turn can lead to the finished cast component not meeting the desired dimensional accuracy requirements. In other words, deviations in dimensional accuracy can occur, particularly significant ones. In particular, if the cast component is comparatively large, T6 heat treatment or T7 heat treatment is therefore not suitable. There is therefore a conflict of objectives with regard to the heat treatment steps of solution annealing and artificial aging. In order to achieve good deformation properties of the cast material, which can be achieved by solution annealing, high annealing temperatures are required, which can, however, be accompanied by reduced dimensional stability or distortion. Furthermore, a heat treatment system for solution annealing is complex. In particular, when producing voluminous die-cast components, a fairly large heat treatment system must also be provided for solution annealing. This is expensive on the one hand. In addition, such a large heat treatment system for solution annealing requires a lot of space. In addition, it is difficult to achieve sufficiently rapid quenching after solution annealing when producing voluminous or large cast components. Solution annealing over a