Method of controlling end seal time in bag-making, filling and packaging machine

A method of controlling an end-sealing time period for a bag forming, filling and packaging machine, comprising:

• longitudinally sealing a packaging film at its both film edges to provide a packaging cylinder,
• feeding said packaging cylinder downwardly with a film feeding device at a speed determined by a packaging capacity of the machine,
• sealing said packaging cylinder at two-lateral rows, and cutting an intermediate position between said rows with a box-motion end-sealing/cutting device, one row being located at an upper side of a product to be packaged that is filled into said packaging cylinder, and the other row being located at a lower side of a product to be packaged that is to be filled into said packaging cylinder subsequently, wherein said end-sealing/cutting device is moved successively along (i) an end-sealing section from an end-sealing starting position to an end-sealing completed position during a sealing time period, and (ii) a returning section from the end-sealing completed position to the end-sealing starting position during a returning time period, so as to form a box motion, and
• controlling servo-motors for forming said box motion so as to shorten the returning time period and to decrease a descending speed of said packaging cylinder and a descending speed of said end-sealing/cutting device simultaneously in the end-sealing section of a constant length determined by a rotation angle of cams for forming said box motion for the sealing section so as to elongate the end-sealing time period without changing the speed determined by the packaging capacity of the machine.