| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a hot press-forming method which can achieve both shortening of cycle time and securing accuracy of a formed article. <P>SOLUTION: A steel sheet is heated at Ac3 point or higher as an average temperature. The steel sheet heated at the average temperature is press formed using a die, and cooled during press forming of the steel sheet. The formed article is released out of the die and cooled further. In the hot press-forming method, the lower the release temperature of the formed article is set, the smaller the shape deviation amount (t) of the formed article becomes. However, when the release temperature of the article is set at lower than 322°C, further improvement of precision of the article cannot be obtained. Furthermore, in such case, occupied time of the die by the article for cooling becomes longer. Meanwhile, when the release temperature is set at 510°C and lower, changing ratio of the shape deviation amount (t) to temperature change becomes remarkably larger so that precision improvement can be obtained. Therefore, the release temperature of the article is set at a temperature in the range between 322°C or higher and 510°C or lower. <P>COPYRIGHT: (C)2012,JPO&INPIT |
