Bag forming-filling-packaging machine

A bag forming-filling-packaging machine comprising:

• a seal bar supporting frame which reciprocates along a transfer orbit of a tube film for packaging therein an object;
• a pair of seal bars disposed on said frame;
• and a crank mechanism for transmitting a swinging motion of an arm having a support shaft on its one end as its fulcrum to said seal bar supporting frame through a connecting rod, thereby allowing said frame to reciprocate along said transfer orbit of said tube film, wherein
• both said seal bars are allowed to carry out block motion by a combined motion of the reciprocating motion of said frame, and an approaching motion and a separating motion of said pair of seal bars disposed on said frame such as to sandwich said tube frame, and
• while said tube film is being gripped with pressure by said seal bars, air in said film is sucked and removed through a cut formed in a pressure-gripped region of the film, and then said cut is heat sealed,
• said bag forming-filling-packaging machine further comprising:
• a mechanism for slidably engage a slider supported by a crankshaft with a guide formed along said arm, and swings said arm by said crankshaft which is revolved by a servo motor;
• and
• a controller defining opposite sides of the arm swinging region as deceleration regions, and sending a calculation signal to said servo motor to cause a swinging speed of said arm to be constant in a region having a rotation angle of 180° of said crankshaft inside said deceleration regions.