Aluminum alloy sheet for cold press forming, method of manufacturing the same, and cold press forming method for aluminum alloy sheet

Abstract

An Al-Mg-Si based aluminum alloy sheet having undergone normal-temperature aging (or being in an underage state) after a solution treatment thereof is, before press forming, subjected to a heating treatment (partial reversion heating treatment) in which the alloy sheet is partially heated to a temperature in the range of 150 to 350 DEG C for a time of not more than 5 minutes so that the difference in strength (difference in 0.2% proof stress) between the heated part and the non-heated part will be not less than 10 MPa. The alloy sheet thus treated is subjected to cold press forming in the condition where the heated part with low strength is put in contact with a wrinkle holding-down appliance of the press and the non-heated part with high strength is put in contact with the shoulder part (radius) of the punch. In the partial reversion heating treatment, the temperature rise rate and the cooling rate in cooling down to 100 DEG C or below are set to be not less than 30 DEG C/min. Further, the period for which the alloy sheet is left to stand at normal temperature after the partial reversion heating treatment until the cold press forming is set to be within 30 days.

Description

technical field [0001] The present invention relates to an Al-Mg-Si based aluminum alloy plate, which is used after forming, especially cold forming, and baking the coating on it, and also relates to a manufacturing method of the aluminum alloy plate, and the use of the aluminum alloy plate Cold press forming method of aluminum alloy plate. More specifically, the present invention relates to an Al-Mg-Si-based aluminum alloy plate, which is preferably used for various components and parts of automobiles, ships, aircraft, etc., or as building materials, structural materials, or Used in various devices, home appliances, parts thereof, etc., for example, automobile body panels and panels. Background technique [0002] Traditionally, automotive body panels have previously been obtained mainly by using cold-rolled steel sheets. However, due to the recent widespread awareness of the importance of reducing the weight of the vehicle body, rolled aluminum alloy sheets have been freq...

AI Technical Summary

Problems solved by technology

[0006] 1. The press (press) must have the function of heating and cooling the aluminum alloy plate, thus requiring a longer overall forming time compared with the case of cold forming, resulting in reduced production efficiency and increased forming cost

[0007] 2. Since the forming is carried out under warm conditions, ordinary lubricants for cold forming cannot be used, therefore, new lubricants need to be developed

[0008] 3. The press is structurally complex, which leads to increased equipment costs

[0009] 4. Since the press is more complicated, it increases the difficulty of quality control

In this case, however, the following problems were found: the strain is concentrated in the area under the punch and being softened, and the thickness of the plate is significantly reduced locally in this area, resulting in a decrease in the rigidity of the formed product.

Regarding this point, in the technology of Patent Document 3, only the area of ​​the plate located under the punch, that is, the central part of the plate, is heated, but the peripheral part of the plate remains in the state of aging precipitation due to aging at room temperature, and in the peripheral part The bending ability of the part is very poor, leading to cracking in the bending part

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