Packaging machine and method

A method of tensioning a web within a packaging machine comprising the steps of:

• a) supplying the web from a web source;
• b) relatively positioning pivotally connected upper and lower dancer frames respectively carrying upper and lower dancer roll sets such that the roll sets are on opposite sides of an imaginary plane;
• c) feeding the web generally along the plane while the roll sets are so positioned on opposite sides of it;
• d) moving the upper frame to position its roll set on the other side of the plane in a web feed position in a tension control range;
• e) feeding the web through a bagger included in the packaging machine;
• f) monitoring the relative positions of the dancer frames in response to the feeding of web through the bagger;
• and
• g) controlling the feed of the web in response to the relative positions of the dancer frames.

A method of feeding a web through a packaging machine comprising the steps of:

• a) driving at least one roll member of a nipped pair of roll members near a load station;
• b) driving at least four belts wrapped around a pair of roll members along one side of a web path of travel;
• c) driving at least four opposing belts wrapped around an opposing pair of roll members along an opposite side of the web path of travel;
• d) placing the web in contact with certain of the roll members and the belts at a location spaced from the load station;
• e) clamping the web between the opposing belts while the web is between the opposing roll members;
• and
• f) feeding the web by continuing to drive the belts.

In a bagging machine including a web supply station, a work station and structure defining a path of web travel for a chain of pre-opened bags from the supply station downstream to the work station, an improved web tensioning system comprising:

• a) upper and lower dancer roll sets;
• b) upper and lower dancer frames respectively carrying the upper and lower sets;
• c) the frames being relatively movably connected together and being selectively relatively positionable in a web feed position and a web tension control range;
• d) the upper roll set when in the web feed position being on one side of an imaginary plane located by the axes of the upstream most and downstream most rolls of the lower set, the upper set being on the opposite side of the plane when in the tension control range;
• e) a frame motion-sensing mechanism operatively connected to the frames and adapted to sense relative motion of the frames when in the control range;
• and
• f) a web feed rate control means positioned to engage a web being fed along the path for controlling the feed rate of the web in response to mechanism sensed relative motion of the frames.

A packaging machine of the type with which a web in the form of a chain of pre-opened plastic bags is fed along a path of travel through the machine to a loading station with the bags each oriented closed end first, a web feed mechanism comprising:

• a) opposed conveyor belts respectively positioned on opposite sides of the path;
• b) opposed pairs of spaced roll members respectively positioned on opposite sides of the path;
• c) each of the belts being stretched around the roll member pair on the like side of the path and delineating as to each belt a feed reach adjacent the path and a return reach spaced from the path;
• d) drive means coupled to at least one of the roll members selectively to rotate the coupled members and thereby cause the feed reaches to move in directions toward the load station and,
• e) one roll member of each pair being nipped to form a pair of nip rolls positioned on opposite sides of the path at a downstream location along the path of travel.

A method of feeding a web through a packaging machine comprising the steps of:

• a) driving at least one roll member of a nipped pair of roll members near a load station;
• b) driving at least one belt wrapped around a pair of roll members along one side of a web path of travel at a surface speed less than the surface speed of the one roll member;
• c) driving at least one opposing belt wrapped around an opposing pair of roll members along an opposite side of the web path of travel at a surface speed less than the surface speed of the one roll member;
• d) placing the web in contact with certain of the roll members and the belts at a location spaced from the load station;
• e) clamping the web between the opposing belts while the web is between the opposing roll members;
• and
• f) feeding the web by continuing to drive the belts.

A packaging machine of the type with which a web in the form of a chain of pre-opened plastic bags is fed along a path of travel through the machine to a loading station with the bags each oriented closed end first, a web feed mechanism comprising:

• a) opposed conveyor belts respectively positioned on opposite sides of the path;
• b) opposed pairs of spaced roll members respectively positioned on opposite sides of the path;
• c) each of the belts being stretched around the roll member pair on the like side of the path and delineating as to each belt a feed reach adjacent the path and a return reach spaced from the path;
• d) drive means coupled to at least one of the roll members selectively to rotate the coupled members and thereby cause the feed reaches to move in directions toward the load station;
• and,
• e) the pairs of roll members located upstream along the path of travel being offset relative to one another.

In a bagging machine including a web supply station, a bagging station and structure defining a path of web travel for a chain of pre-opened bags from the supply station downstream to the bagging station, an improved web tensioning and feed system having three discrete sections in which tension in each section is isolated from tension in the other sections comprising:

• a) a supply section including a feed motor driven pair of supply nip rolls adapted to pull a web from a supply while isolating down stream portions of the path from tensions between the supply and the supply nips;
• b) an intermediate section including:
• i) upper and lower dancer roll sets;
• ii) upper and lower dancer frames respectively carrying the upper and lower sets;
• iii) the frames being relatively movably connected together and being selectively relatively positionable in a web feed position and a web tension control range;
• iv) the upper roll set when in the web feed position being on one side of an imaginary plane located by the axes of the upstream most and downstream most rolls of the lower set, the upper set being on the opposite side of the plane when in the tension control range;
• v) a frame motion-sensing mechanism operatively connected to the frames and adapted to sense relative motion of the frames when in the control range;
• and
• vi) a web feed rate control means positioned along the path for controlling the speed of the feed motor and thereby controlling feed rate of the web in response to mechanism sensed relative motion of the frames;
• and,
• c) a bagging station feed section including:
• i) opposed conveyor belts respectively positioned on opposite sides of the path and adapted to isolate intermediate section tensions from the bagging station section;
• ii) opposed pairs of spaced roll members respectively positioned on opposite sides of the path;
• iii) each of the belts being stretched around the roll member pair on the like side of the path and delineating as to each belt a feed reach adjacent the path and a return reach spaced from the path;
• and
• iv) drive means coupled to at least one of the roll members selectively to rotate the coupled members and thereby cause the feed reaches to move in directions toward the load station.

A method of tension control in a packaging machine comprising:

• a) feeding an elongate web from a supply along a first section of a path of travel through a first web grasping and feeding mechanism by tensioning the web between the supply and the first mechanism while isolating such tensioning from downstream path sections;
• b) feeding the web from the first mechanism along a second section of the path through a second web grasping and feeding mechanism while isolating tension in the second section from a third downstream section of the web;
• c) controllably tensioning the web in the second section as the web is fed through the second section;
• and
• d) applying tension to a third section of the web downstream from the second mechanism by applying differential feed rates with two components of the second mechanism.