Patent ID: 8511129

Claim:
A method of press forming a metal sheet with a blank holder, a punch and an upper die comprising: supplying fluid with a kinematic viscosity of 500 mm 2 /s or lower (40° C.), as a lubricant, to a space between the metal sheet and the blank holder, a space between the metal sheet and the punch, and a space between the metal sheet and the upper die; starting forming of the metal sheet by contacting the metal sheet with the punch while the metal sheet is held by the blank holder and the upper die; before the punch reaches a bottom dead center and forming is completed, in the middle of forming before the punch reaches a stroke end, detaching the blank holder from the metal sheet, wherein the metal sheet remains attached to the punch; and resuming forming of the metal sheet using the same punch, the same upper die, and the same blank holder, wherein dies, a surface roughness of which is an arithmetical mean roughness Ra of 7.5 μm or smaller, are used as the punch, the upper die, and the blank holder.