Patent ID: 6623411
Filing Date: 2003-09-23
Classification: B31B

Abstract:
In a plastic bag making machine where a tubular web moves in a web feed direction past a web sensor and through a punch station, a sealing and cutting station, and a wicketer and stacking station, and where said web moving toward said punch station shifts beyond an allowable range in a transverse direction relative to said web feed direction affecting alignment of holes punched in said bags by a punch apparatus at said punch station with wicketing pins extending from wicketing stands on a conveyor at said stacking station, and where said punch apparatus is carried on a punch carriage movable in said transverse direction and said conveyor is carried on a conveyor carriage movable in said transverse direction, the improvement for aligning said punched holes in said bags with said wicketing pins at said stacking station, comprisinga. a first servo motor for driving said punch carriage in said transverse direction, and a first sensor/transducer to measure any transverse direction movement of said punch carriage relative to a reference position, b. a second servo motor for driving said conveyor carriage in said transverse direction, and a second sensor/transducer to measure any transverse direction movement of said punch carriage relative to a reference position, c. a servo controller electrically coupled to said web sensor, to said first and second servo motors and to said first and second sensor/transducers, whereby said web sensor detects transverse direction shift of said web beyond said allowable range as said web nears said punch apparatus and outputs a directional signal indicating this transverse shift of said web to said servo controller, said servo controller outputs a directional command to said second servo motor to move said conveyor carriage and wicketing pins carried thereon in said transverse direction corresponding to that of the transversely shifted web, said second sensor/transducer measures the transverse movement of said conveyor carriage and outputs a directional signal corresponding to this moved position to said servo controller, said servo controller in response to said output from said second sensor/transducer outputs a directional command to said first servo motor to move said punch carriage in said transverse direction corresponding to said transversely moved position of said conveyor carriage, said first sensor/transducer measures the transverse movement of said conveyer carriage and outputs a directional signal corresponding to this moved position to said servo controller, and said servo controller compares said outputs from said first and second sensor/transducers and continues to output said directional commands to said first and second servo motors as long as both of said sensor/transducers indicate transversely moved positions of said conveyor and punch carriages that are not the same, and said servo controller ceases to output directional commands to said first and second servo motors when said first and second sensor/transducers output the same directional signals indicating that said conveyor carriage and said punch carriage have the same transversely moved positions and that said punched holes in said bags will be aligned with said wicketing pins.