Blow molded hinge members and a mold for forming the hinge members

A hinge member for a blow molded article, comprising:

• at least two hinge arms adapted to be affixed to a first portion and a second portion of the article respectively, the two hinge arms comprising an upper hinge arm and a lower hinge arm, each of the at least two hinge arms comprising an axial hole defined therein, a hinge pin extending through the axial holes of the at least two hinge arms;
• and at least two openings defined in a wall of each of the at least two hinge arms and extending in a direction parallel to a horizontal plane at which the axis of the axial hole is located,
• wherein at least one of the at least two openings is positioned in the wall at each side of the horizontal plane, said at least two openings satisfy the following relationship:
• ∑
• i
• =
• 1
• n
• ⁢
• L
• i
• ≥
• L
• z
• ⁢
• ⁢
• and
• ⁢
• ⁢
• d
• ≤
• Bi
• <
• D
• ⁡
• (
• i
• =
• 1
• ,
• 2
• ,
• …
• ⁢
• ,
• n
• ;
• n
• ⁢
• ⁢
• represents
• ⁢
• ⁢
• a
• ⁢
• ⁢
• natural
• ⁢
• ⁢
• number
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• that
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• is
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• greater
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• than
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• 1
• )
• ;
• where,
• n stands for a number of openings defined in the wall of the each of the at least two hinge arms;
• Li stands for a length of the i-th opening along the axial direction of the axial hole;
• Lz stands for a length of the wall of the each of the at least two hinge arms along the axial direction of the axial hole;
• Bi stands for a width of the i-th opening projected on the horizontal plane that is perpendicular to the axial direction of the axial hole;
• d stands for an inner diameter of the axial hole;
• and
• D stands for an outer diameter of the wall of the each hinge arm.