Pallet strapping device

1. A pallet strapping device, comprising:

a platform comprising a horizontal conveying portion, a vertical frame portion, a first pivot portion and a second pivot portion, the horizontal conveying portion comprising a plurality of horizontal rollers and a lower guiding strap portion, the vertical frame portion equipped with an upper guiding strap portion;

a first guiding device comprising a first frame portion, a first guiding strap portion and a first driving portion, the first frame portion pivotally disposed at the first pivot portion via one end of the first frame portion, the first guiding strap portion disposed at the other end of the first frame portion, the first driving portion pivotally disposed on the platform, and the first driving portion connecting the platform with the first frame portion, the first driving portion used to control the first frame portion to be movable to at least a first position and a second position via taking the first pivot portion as an axis of the first frame portion, wherein when the first frame portion is located at the first position, the first guiding strap portion is spatially communicated with the lower guiding strap portion and the upper guiding strap portion, respectively;

a second guiding device comprising a second frame portion, a second guiding strap portion and a second driving portion, the second frame portion pivotally disposed at the second pivot portion via one end of the second frame portion, the second guiding strap portion disposed at the other end of the second frame portion, the second driving portion pivotally disposed on the platform, and the second driving portion connecting the platform with the second frame portion, the second driving portion used to control the second frame portion to be movable to at least a third position and a fourth position via taking the second pivoting portion as an axis of the second frame portion, wherein when the second frame portion is located at the third position, the second guiding strap portion is spatially communicated with the lower guiding strap portion and the upper guiding strap portion, respectively; and

an extendable mechanism comprising a telescopic control portion and a central guiding strap portion, the telescopic control portion used to control the central guiding strap portion to be movable to at least a retracted position and an extended position;

wherein when the first frame portion is located at the first position, the second frame portion is located at the third position and the central guiding strap portion is located at the retracted position, the lower guiding strap portion, the upper guiding strap portion, the first guiding strap portion and the second guiding strap portion are spatially communicated with one another to form a first guiding strap circulation path; when the first frame portion is located at the second position, the second frame portion is located at the fourth position and the central guiding strap portion is located at the extended position, the upper guiding strap portion and the central guiding strap portion are spatially communicated with each other to form a second guiding strap circulation path.

2. The pallet strapping device as claimed in claim 1 , wherein:

when the first frame portion is located at the second position, the first guiding strap portion is used to stagger the lower guiding strap portion and the upper guiding strap portion from each other; and

when the second frame portion is located at the fourth position, the second guiding strap portion is used to stagger the lower guiding strap portion and the upper guiding strap portion from each other.

3. The pallet strapping device as claimed in claim 1 , wherein:

the first driving portion is one of an electric gear cylinder, a pneumatic cylinder and a push-pull driving device.

4. The pallet strapping device as claimed in claim 3 , wherein:

when the first driving portion is the push-pull driving device, the push-pull driving device comprises an oblique push face portion, a pushed portion and a restoring portion, the oblique push face portion is connected to the central guiding strap portion and is adjacent to an end of the central guiding strap portion facing the platform, the pushed portion is uprightly disposed at the first frame portion, the restoring portion is connected with the platform and the first frame portion, respectively;

during movement of the central guiding strap portion from the retracted position to the extended position, the oblique push face portion simultaneously pushes the pushed portion, the pushed portion is configured to connectively and simultaneously move the first frame portion from the first position to the second position, and the moved first frame portion pulls the restoring portion to move at the same time; and

during movement of the central guiding strap portion from the extended position to the retracted position, the oblique push face portion is simultaneously withdrawn away from the pushed portion, the restoring portion generates a pulling force to pull the first frame portion, and the first frame portion is restored to move from the second position to the first position.

5. The pallet strapping device as claimed in claim 4 , wherein the restoring portion is an expansion spring.

6. The pallet strapping device as claimed in claim 1 , wherein the second driving portion is one of an electric gear cylinder and a pneumatic cylinder.