Plastic Strapping Machines - How they work

 


Strapping Machine Mechanism

An article is placed on a strapping machine table (31) - a slide anvil (32) is used for releasing the article from the table (31) after the strapping operation is completed and is movable in the transversal direction and the lower surface (32') of the slide table  forms a horizontal surface. 

A micro-lever (33) is placed under and to the slide anvil (32) under  to detect when a plastic strap (B) is taken over a package andits leading end is inserted back under the anvil 

 A center guide (34) is used to guide the plastic band (B) into an arch guide in the automatic system; or a band projection guide in a semi automatic system; the center guide (34) is movable in the transversal direction.

A first gripper (35) grips the end of the plastic band (B) between the underside of the anvil (32) and the gripper when the plastic band (B) is fed so as to contact with the micro-lever (33). 


A feeding and tightening mechanism (36) for the plastic strapping band (B) comprises a feed roller (37), a return roller (38). When the band (B) is pressed on the feed roller (37) by a rocker roller (39), the band (B) is fed out. When the band (B) is pressed on the return roller (38) by a rocker roller (40), the band (B) is tightened. A compression plate (41) has flat horizontal surface (41') as its upper surface and is pivoted to the shaft (42') of a compression rod (42). A stopper for the compression plate (41) is adjusted to give an angle β for feeding the band (B) by the horizontal surface (41'). The compression rod (42) is hollow and a spring (52) and a leg (43) are kept in it and a roller (44) is connected at a lower end of the leg (43). The roller (44) is always contacted with the cam ring (46) connected to a cam shaft (45). A tensile spring (48) is fitted between the rod (42) and a pin (47) mounted on a frame. A second gripper (42") is projected at the upper end of the rod (42). The band is gripped between the second gripper (42") and the slide table (32) by the elevation of the rod (42) depending upon the cam ring (46) after tightening the band (B) 

 

The spring (52) is used for the gripping. A cutter plunger (49) has a hollow part and a leg (50) and a spring (52) are kept in the hollow part. A roller (44) connected to the lower end of the leg (50) is contacted with a cam ring (51). A tensile spring (53) actuates to pull down the cutter plunger (49). The upper surface of the cutter plunger (49) is contacted with the compression plate (41). When the plunger (49) is elevated by the cam shaft, the compression plate (41) is pulled up by its upper surface. A cutter (54) is projected upwardly from one side of the plunger (49) and the band (B) is cut between the cutter and the side surface of the first gripper (35). The first gripper (35) has a hollow part and a spring (52) and a leg (55) are kept in the hollow part. A roller (44) connected to the lower end of the leg (55) is always contacted with a cam ring (57). A tensile spring (56) is fitted.

Although one embodiment of the band-feeding and tightening system has been illustrated, it is possible to modify the band feeding and tightening system as desired in view of the conventional structures.

Referring to FIGS. 1 and 2, one embodiment of the semiautomatic-automatic strapping machine in the form of the automaticsystem will be illustrated.

A casing (2) is covered by a table (3) having a longitudinal gap (4) for passing a plastic band (B). A heat-pressing part (5) is located in front of the feed roller (7) so as to melt-bond the end of the plastic band (B) overlapped on the other end of the plastic band (B) by pressing and heating the overlapped part of the plastic band (B) between the receiving part (6) and the heat pressing part (5). The feed rollers and the return rollers (7), (7') and a band roller (8) are used for feeding and tightening the plastic band (B). A package (G) is strapped by the plastic band (B). An arch (11) is fitted on the upper side of the casing (2) with a fitting such as a nut and a bolt or a key. The arch (11) has an arch guide (13) which is opened by the tightening force of the plastic band (B) wound along the arch guide. The lower part (13'), (13') of the arch guide (13) has a space (14') in which a band gripper is located. One end of the lower part (13') of the arch guide (13) is adjacent to a center guide (34) as shown in FIG. 7.

 

The End Result - See the Video

 

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