Press-forming method and press-formed part

A press-forming method comprising:

• determining a reference proportion for an area of a plate to be heated to a quenchable temperature relative to an area of another portion of the plate;
• preparing the plate to include a first portion, a second portion longer than the first portion along a first direction, a trapezoidal portion with a pair of sides connecting the first portion and the second portion along a second direction orthogonal to the first direction, and a region of an area between the first portion and the trapezoidal portion that is to be heated to the quenchable temperature;
• connecting a first electrode to one end of the plate in a direction orthogonal to a thickness direction of the plate and connecting a second electrode to an other end of the plate in the direction orthogonal to the thickness direction of the plate;
• heating the region to the quenchable temperature by passing current from the one end to the other end;
• and
• forming the plate into a final predetermined shape by pressing and cooling the plate after the heating,
• wherein preparing the plate to include the region includes positioning at least one of the pair of sides of the trapezoidal portion at an inclination angle corresponding to the reference proportion,
• wherein the inclination angle is an angle of the at least one of the pair of sides of the trapezoidal portion relative to the second direction,
• wherein positioning the at least one of the pair of sides of the trapezoidal portion at a smaller inclination angle increases a size of the region of the area between the first portion and the trapezoidal portion.

A press-forming method comprising:

• determining a reference proportion for an area of a plate to be heated to a quenchable temperature relative to an area of another portion of the plate,
• preparing the plate to have a trapezoidal shape and to include a first side, a second side parallel to and shorter than the first side in a first direction, and a region of an area extending from the second side to the first side that is to be heated to the quenchable temperature;
• connecting a first electrode to the first side of the plate and connecting a second electrode to the second side;
• heating only the region to the quenchable temperature by passing current from the first side to the second side;
• and
• forming the plate into a final predetermined shape by pressing and cooling the plate after the heating,
• wherein the region spreads from the second side to the first side in a second direction orthogonal to the first direction over a length that is less than a length of the plate between the second side and the first side in the second direction,
• wherein preparing the plate to include the region includes sizing a length of the second side relative to a length of the first side according to a ratio corresponding to the reference proportion,
• wherein sizing the length of the second side according to a smaller ratio increases an area of the region.