Hot press line and method of manufacturing hot-press-formed product

A hot press line comprising:

• a heating device adapted to heat a metal sheet;
• a first press device including a pair of first die parts movable relative to each other in a direction of pressing and adapted to press form the heated metal sheet by moving the first die parts closer to each other in the direction of pressing and, at a bottom-dead center, hold the metal sheet;
• a second press device including a pair of second die parts movable relative to each other in the direction of pressing and adapted, at a bottom-dead center of the second die parts, to hold the metal sheet press formed by the first press device;
• a first transportation device adapted to transport the metal sheet from the heating device to the first press device;
• and
• a second transportation device adapted to transport the metal sheet from the first press device to the second press device,
• wherein at least one of the pair of first die parts and the pair of second die parts includes a clearance portion recessed inwardly to create a clearance with the metal sheet while the die parts are at the bottom-dead center, and other pair of the pair of first die parts and the pair of second die parts includes an abutment surface located in at least part of a portion corresponding to the clearance portion of the least one of the pair of first die parts and the pair of second die parts and adapted to abut the metal sheet while the die parts are at the bottom-dead center, and
• wherein a die portion of the least one of the pair of first die parts and the pair of second die parts facing the clearance portion of the one pair is provided with the abutment surface for abutting the metal sheet when the die parts are at the bottom-dead center, and a die portion of the other pair of die parts facing the abutment surface of the other pair is provided with the clearance portion recessed inwardly for creating a clearance with the metal sheet when the die parts are at the bottom-dead center.

A method of manufacturing a hot press-formed product, comprising:

• heating a metal sheet;
• positioning the heated metal sheet between a pair of first die parts of a first press device;
• press forming the metal sheet by moving the first die parts closer to each other in a direction of pressing;
• a first bottom-dead-center holding step for holding the metal sheet while the pair of first die parts are at a bottom-dead center;
• after the first bottom-dead-center holding step, transporting the press-formed metal sheet to a pair of second die parts of a second press device and positioning the metal sheet therebetween;
• and
• a second bottom-dead center holding step for holding the metal sheet press formed by the first press device while the pair of second die parts are at a bottom-dead center,
• wherein, during one of the first bottom-dead-center holding step and the second bottom-dead-center holding step, a surface of the metal sheet has a non-abutment region that does not contact a die of one pair of first die parts or the pair of second die parts at a bottom-dead center, and at least part of the non-abutment region contacts a die of other pair of the pair of first die parts or the second die parts at a bottom-dead center during other bottom-dead-center holding step of the first bottom-dead-center holding step and the second bottom-dead-center holding step, and
• wherein during the one of the first bottom-dead-center holding step and the second bottom-dead-center holding step, a cooling rate in the non-abutment region is lower than in a region of the metal sheet to be abutted by the one pair of first die parts or the pair of second die parts by only forming a clearance between a clearance portion of at least one of the pair of first die parts and the pair of second die parts and the non-abutment region.

A method of manufacturing a hot press-formed product, comprising:

• heating a metal sheet;
• positioning the heated metal sheet between a pair of first die parts of a first press device:
• press forming the metal sheet by moving the first die parts closer to each other in a direction of pressing;
• a first bottom-dead-center holding step for holding the metal sheet while the pair of first die parts are at a bottom-dead center;
• after the first bottom-dead-center holding step, transporting the press-formed metal sheet to a pair of second die parts of a second press device and positioning the metal sheet therebetween;
• and
• a second bottom-dead center holding step for holding the metal sheet press formed by the first press device while the pair of second die parts are at a bottom-dead center,
• wherein, during one of the first bottom-dead-center holding step and the second bottom-dead-center holding step, a surface of the metal sheet has a non-abutment region that does not contact a die of one pair of first die parts or the pair of second die parts at a bottom-dead center, and at least part of the non-abutment region contacts a die of other pair of the pair of first die parts or the second die parts at a bottom-dead center during other bottom-dead-center holding step of the first bottom-dead-center holding step and the second bottom-dead-center holding step, and during the one bottom-dead-center holding step, at least part of a back side region of the metal sheet for the non-abutment region is abutted by a die part at the bottom-dead center, during the other bottom-dead-center holding step, and at least part of the back side region for the non-abutment region is not abutted by a die part.