Patent ID: 7380495

Claim:
A strap feeding and withdrawing structure for a packing machine comprising: a conveying device composed of a main body, a driving member, a strapping member, an electromagnetic switch unit, a pull member and a strap withdrawal detecting member; said main body having one side provided thereon with a driving wheel and a strapping wheel, said main body transversely fixed with a combining member between said driving wheel and said strapping wheel, said combining member having its rear side extended backward to form an extension portion; said driving member movably and pivotally disposed with an auxiliary driving wheel to be rotated together with said driving wheel of said main body, said driving member having one side pivotally assembled on said combining member of said main body, said driving member having one side, which is distant from said combining member, formed with a fastening portion; said strapping member movably and pivotally provided thereon with an auxiliary strapping wheel to be rotated together with said strapping wheel of said main body, said strapping member having one side pivotally combined with said combining member of said main body, said strapping member having one side, which is distant from said combining member, formed with an interacting portion; said electromagnetic switch unit composed of an electromagnetic valve and a connecting rod set, said connecting rod set having one end pivotally fixed with said fastening portion of said driving member, said connecting rod set having another end pivotally connected to said electromagnetic valve, said connecting rod set fitted with a shaft in its center, said connecting rod set actuated by said electromagnetic valve to turn, with said shaft acting as a pivot; said pull member composed of a connecting rod and a pawl, said connecting rod pivotally combined with said extension member of said main body and able to be turned for a preset angle, said pawl secured at a rear end of said connecting rod, and said actuating pawl having its free ends pivotally combined with said interacting portion of said strapping member; and said strap withdrawal detecting member secured at one outer side of said driving member to be rotated together said auxiliary driving wheel, said strap withdrawal detecting member functioning to detect rotating conditions of said auxiliary driving wheel.