Apparatus and method for folding blanks

Device for folding by approximately 180.degree. a first surface portion located at one end of a blank about a score line onto a second surface portion of the blank adjacent to the first surface portion, the blank being disposed on a rotating drum, the score line being in a plane tangent to a cylindrical outer surface of the drum such that the first surface portion overhangs an end face of the drum, the device comprising:

• a shaping rail comprising a generally circular annulus segment disposed at the end face of the drum, a first portion of said segment at an upstream end of said rail, and a second portion of said segment at a downstream end of said rail,
• said first portion comprising a first edge directed toward the drum and being generally parallel to the score line, a first outer convex face positioned beneath the overhanging first surface portion of the blank as the blank rotates with the drum and which comprises an outer frustoconical beveled surface, and a first inner concave face,
• said second portion comprising a second inner concave face positioned above the overhanging first surface portion of the blank as the blank rotates with the drum, said first and second inner concave faces comprising an inner frustoconical beveled surface, and a spiral edge directed toward the drum, extended from the first edge and having a spiral shape gradually advancing in the direction of the drum,
• wherein, as the drum and the blank disposed thereon rotate, the first surface portion of the blank is guided along the outer beveled surface toward the first edge, along the first edge, along the spiral edge and along the inner beveled surface to be folded approximately 180.degree. about the score line onto the second surface portion.

Device for folding by approximately 180.degree. a first surface portion located at one end of a blank about a score line onto a second surface portion of the blank adjacent to the first surface portion, the blank being disposed on a rotating drum, the score line being in a plane tangent to a cylindrical outer surface of the drum such that the first surface portion overhangs an end face of the drum, the device comprising:

• a shaping rail comprising a generally circular annulus segment disposed at the end face of the drum, a first portion of said segment at an upstream end of said rail, and a second portion of said segment at a downstream end of said rail,
• said first portion comprising a first edge directed toward the drum and being generally parallel to the score line, a first outer convex face positioned beneath the overhanging first surface portion of the blank as the blank rotates with the drum, which comprises an outer beveled surface,
• said second portion comprising an inner concave face positioned above the overhanging first surface portion of the blank as the blank rotates with the drum, said inner concave face comprising an inner beveled surface, and a spiral edge directed toward the drum, extended from the first edge and having a spiral shape gradually advancing in the direction of the drum,
• wherein, as the drum and the blank disposed thereon rotate, the first surface portion of the blank is guided along the outer beveled surface toward the first edge, along the first edge, along the spiral edge and along the inner beveled surface to be folded approximately 180.degree. about the score line onto the second surface portion.

Device for folding by approximately 180.degree. a first surface portion located at one end of a blank about a score line onto a second surface portion of the blank adjacent to the first surface portion, the blank being disposed on a rotating drum, the score line being in a plane tangent to a cylindrical outer surface of the drum such that the first surface portion overhangs an end face of the drum, the device comprising:

• a shaping rail comprising a generally circular annulus segment disposed at the end face of the drum, a first portion of said segment at an upstream end of said rail, and a second portion of said segment at a downstream end of said rail,
• said first portion comprising a first edge directed toward the drum and being generally parallel to the score line, a first outer convex face positioned beneath the overhanging first surface portion of the blank as the blank rotates with the drum,
• said second portion comprising an inner concave face positioned above the overhanging first surface portion of the blank as the blank rotates with the drum, and a spiral edge directed toward the drum, extended from the first edge and having a spiral shape gradually advancing in the direction of the drum,
• wherein, as the drum and the blank disposed thereon rotate, the first surface portion of the blank is guided along the outer convex face toward the first edge, along the first edge, along the spiral edge and along the inner concave face to be folded approximately 180.degree. about the score line onto the second surface portion, the outer convex face, the spiral edge and the inner concave face shaped to fold the first surface portion.