Hot press-forming method for steel sheets, hot press-forming device for steel sheets, and steel formed member
A technology of hot-press forming and steel plate, which is applied in the field of hot-press forming of steel plate, hot-press forming device of steel plate and steel forming parts, which can solve problems such as decreased bendability, reduced joint strength, shortened service life of processing tools, etc., to ensure Processability and large degree of freedom effect
Active Publication Date: 2012-05-16
NIPPON STEEL CORP
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Problems solved by technology
[0004] However, if the entire steel plate is rapidly cooled, depending on the location, the hardness of the molded product will increase, causing disadvantages.
For example, the bendability of the periphery of the welded part is reduced, the strength of the joint is reduced, or the processing of the molded product becomes difficult in the post-process such as drilling processing or shearing processing, or the life of the processing tool is shortened.
Method used
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Examples
Experimental program
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Effect test
Embodiment
[0094] As an example, a plated steel sheet K was hot-press-formed using the hot-press forming apparatus 1, and a confirmation test of reheat temperature and hardness was performed. Table 1 shows the results of the confirmation test. Here, a confirmation test was performed by varying the width δ of the local quenching section Kc, the thickness t of the plated steel sheet K, the number N of reheating stages 12 , and the presence or absence of heating by the heating device 80 on the reheating stage 12 . As the plated steel sheet K with relatively low hardness, steel containing 0.2% by mass of C and trace amounts of Mn, B, and Si is used to implement 80g / m 2 The electroplated steel plate mainly containing Al (Example 1-6). In addition, as plated steel sheet K with relatively high hardness, 80 g / m 2Electroplated steel sheets mainly composed of Al (Examples 7-11). The initial temperature Ti of the plated steel sheet K is 950°C, the temperature Tc1 during quenching of the partial ...
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Before hot press-forming a flat plated steel sheet (K) that has been uniformly heated to a temperature equal to or greater than an A1 transformation point, a partial rapid cooling stage (11) rapidly cools a prescribed region of the plated steel sheet (K) to a temperature equal to or less than the martensite start (Ms) temperature, and then the rapidly cooled region of the plated steel sheet (K) is reheated to a temperature greater than the martensite start (Ms) temperature. After the plated steel sheet (K) is reheated, a forming / rapid-cooling stage (13) simultaneously forms the plated steel sheet (K) and rapidly cools same to a temperature equal to or less than the martensite finish (Mf) temperature.
Description
technical field [0001] The present invention relates to a forming method, a forming device, and a formed part that facilitate processing of the portion in a subsequent process by forming a tempered martensite-containing structure at an arbitrary portion of a steel sheet during hot press forming. Background technique [0002] In recent years, hot press forming, which has been widely used as a method of forming steel sheets for automobile parts using high-strength steel sheets, forms steel sheets at a higher temperature than cold press forming. If hot press forming is performed, the deformation resistance of the steel sheet during press forming is reduced, and through the reduction of the deformation resistance, it is possible to press form a desired shape without causing cracks, wrinkles, etc., and more conform to the shape of the mold. shape. [0003] In the hot press forming method, the punch is lowered to the bottom dead center in the state where the steel plate heated to...
Claims
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IPC IPC(8): B21D22/20B21D24/00
CPCB21D22/02B21D37/16C21D1/62C21D1/673C21D8/005C21D9/46C21D2221/00C21D1/18C21D1/26
Inventor 石森裕一福地弘岛哲男
Owner NIPPON STEEL CORP