Hot forming die, press forming apparatus, and hot press forming method

A hot forming die which is configured to press-form a heated steel plate and to cool the heated steel plate by ejecting a cooling medium onto the heated steel plate, the hot forming die comprising:

• a main supply path configured to facilitate the cooling medium to pass there through;
• a plurality of branch supply paths extending from the main supply path and including ejection ports which are configured to eject the cooling medium externally from the hot forming die;
• and
• at least one nozzle member fixed on an ejection port side of each of the branch supply paths and configured to restrict a passage amount of the cooling medium via a passage hole which facilitates the cooling medium to pass there through.

A press forming apparatus, comprising:

• a first die and a second die used in combination with the first die, wherein at least one of the first die or the second die includes a hot forming die which is configured to press-form a heated steel plate and to cool the heated steel plate by ejecting a cooling medium onto the heated steel plate, the hot forming die comprising:
• a main supply path configured to facilitate the cooling medium to pass there through,
• a plurality of branch supply paths extending from the main supply path and including ejection ports which are configured to eject the cooling medium externally from the hot forming die, and
• at least one nozzle member fixed on an ejection port side of each of the branch supply paths and configured to restrict a passage amount of the cooling medium via a passage hole which facilitates the cooling medium to pass there through;
• and
• a pressurizing arrangement configured to control a pressure of a cooling medium in the main supply path and the branch supply paths of the hot forming die at at least two stages.

A hot press forming method comprising

• a. press-forming a heated steel plate and cooling the heated steel plate by ejecting a cooling medium onto the heated steel plate using a press forming apparatus which includes a first die and a second die used in combination with the first die,
• wherein at least one of the first die or the second die includes a hot forming die which is configured to press-form a heated steel plate and to cool the heated steel plate by ejecting a cooling medium onto the heated steel plate, the hot forming die comprising:
• a main supply path configured to facilitate the cooling medium to pass there through,
• a plurality of branch supply paths extending from the main supply path and including ejection ports which are configured to eject the cooling medium externally from the hot forming die, and
• at least one nozzle member fixed on an ejection port side of each of the branch supply paths and configured to restrict a passage amount of the cooling medium via a passage hole which facilitates the cooling medium to pass there through, and
• wherein the press forming apparatus further includes a pressurizing arrangement configured to control a pressure of a cooling medium in the main supply path and the branch supply paths of the hot forming die at at least two stages;
• and
• b. before the press forming of the heated steel plate, maintaining the cooling medium in the main supply path and the branch supply paths on standby after being pressurized to a degree at which the cooling medium unejected, and further pressurizing the cooling medium to a pressure higher than a pressure at a time of the standby at a predetermined timing at least one of during or after pressing and then ejecting the cooling medium onto a formed metal plate.