Stamping tool with a sub pad within a forming steel and method of forming a panel from a sheet metal workpiece

A stamping tool for forming a panel from a sheet metal workpiece, the stamping tool comprising:

• a lower pad including a first lower pad surface, a lower forming surface, and a second lower pad surface, the lower forming surface at least partially defining a recess between the first lower pad surface and the second lower pad surface, the recess being recessed in a first direction from the first lower pad surface and the second lower pad surface;
• an upper pad including a first upper clamp surface, the upper pad being movable relative to the lower pad along a second direction between a retracted pad position and an extended pad position, the second direction being transverse to the first direction, wherein in the extended pad position, the first upper clamp surface is configured to hold the workpiece against the first lower pad surface, wherein in the retracted pad position, the first upper clamp surface is further from the first lower pad surface than when in the extended pad position;
• a forming steel including a first forming surface, the forming steel being movable relative to the lower pad along the first direction between a retracted steel position, an extended steel position, and an intermediate steel position that is between the retracted steel position and the extended steel position, wherein in the extended steel position, the first forming surface is received in the recess, wherein in the retracted steel position, the first forming surface is disposed outside of the recess;
• a sub-pad including a second upper clamp surface opposing the second lower pad surface, the sub-pad being coupled to the forming steel such that the forming steel moves the sub-pad in the first direction as the forming steel moves from the retracted steel position to the intermediate steel position and, at the intermediate steel position, the sub-pad is configured to hold the workpiece against the second lower pad surface while the forming steel continues to move to the extended position;
• and
• a biaser that biases the sub-pad relative to the forming steel in the first direction toward the second lower pad surface.

A method of forming a panel from a sheet metal workpiece, the method including:

• positioning the workpiece on a lower pad;
• clamping a first portion of the workpiece between an upper pad and a first lower pad surface of the lower pad;
• and
• moving a base of a first forming steel in a first direction from a retracted steel position, through an intermediate steel position, to an extended steel position such that the base moves a sub-pad in the first direction while moving from the retracted steel position to the intermediate steel position, the sub-pad clamps a third portion of the workpiece to a second lower pad surface of the lower pad while the base moves from the intermediate position to the extended position, and a first forming surface of the first forming steel deforms a second portion of the workpiece on a second forming surface of the lower pad, that is between the first lower pad surface and the second lower pad surface, by extending further in the first direction than the sub-pad,
• wherein the second forming surface of the lower pad is recessed in the first direction from the first lower pad surface and the second lower pad surface.