Metal member, battery, method for manufacturing same, and die set

A metal member comprising:

• a valve body;
• an annular part provided so as to surround the valve body;
• and
• a member main body provided around the annular part and connected to the valve body via the annular part, wherein
• the annular part includes a thin part having a thickness smaller than thicknesses of the valve body and the member main body, and being formed so as to be continuous with one surface of the member main body in a thickness direction thereof, and
• the valve body is disposed on a side opposite to the member main body relative to the thin part in the thickness direction, and has, in a cross-sectional view of the metal member, a curved shape protruding to the side opposite to the member main body in the thickness direction, or an undulating shape that undulates in the thickness direction.

A die set for manufacturing a metal member, the die set comprising:

• a punch including a punch top surface, a punch shoulder continuous with an outer peripheral edge of the punch top surface and having an arc shape or a tapered shape in a cross-sectional view, and a punch side surface connected to the punch top surface via the punch shoulder;
• a die including a die flange surface having an annular shape, a die shoulder continuous with an inner peripheral edge of the die flange surface and having an arc shape or a tapered shape in a cross-sectional view, and a die side surface connected to the die flange surface via the die shoulder, wherein,
• when the punch and the die are disposed coaxially such that the punch top surface is opposed to an opening of the die flange surface, the punch top surface is disposed inward of the die flange surface, the punch shoulder is opposed to the die shoulder, and the punch side surface is disposed outward of the die side surface, as viewed along an axial direction of the punch and the die, and
• the punch and the die are configured to satisfy the following expressions (1), (2), and (3):
• Cpd
• ≤
• 1.
• (
• 1
• )
• 0.1
• ×
• Cpd
• ≤
• w
• ⁢
• 1
• (
• 2
• )
• w
• ⁢
• 1
• <
• w
• ⁢
• 2
• (
• 3
• )
• where Cpd represents a distance [mm] from a boundary between the punch shoulder and the punch side surface to a boundary between the die shoulder and the die side surface in a direction perpendicular to the axial direction in cross sections of the punch and the die, w1 represents a radius of curvature [mm] of the punch shoulder when the punch shoulder has an arc shape as viewed in the cross section of the punch, and represents a length [mm] of the punch shoulder in the direction perpendicular to the axial direction when the punch shoulder has a tapered shape as viewed in the cross section of the punch, and w2 represents a radius of curvature [mm] of the die shoulder when the die shoulder has an arc shape as viewed in the cross section of the die, and represents a length [mm] of the die shoulder in the direction perpendicular to the axial direction when the die shoulder has a tapered shape as viewed in the cross section of the die.