Apparatus for making carrier bags from two half-tubes running side-by-side

Claim 1

Apparatus for making carrier bags from pairs of preprinted plastics half tubes having printed marks thereon, said apparatus comprising: means for moving the pairs of tubes side-by-side in parallel through said apparatus; first means for turning and folding back at least one edge of each tube to thereby expose inner marginal zones of each half tube; second means including a station for applying handle hole reinforcing strips to the exposed inner marginal zones; handle hole punches for punching holes in portions of both tubes reinforced by the strips; transverse welding and separating means for simultaneously transversely welding said tubes to thereby form and separate individual bags from both tubes; said second means including: means for supporting a web of reinforcing strips; means including rotating knives for severing individual strips from the web; means for moving said web from said supporting means to said severing means; conveying means for conveying severed strips to the station for applying the strips to the tubes; first photocell means for scanning and for generating first signals representative of printed marks on each of the webs; means for sensing and for generating second signals representative of phase positions of said knives of said means for severing; and means for comparing said first and said second signals and for generating control signals when the sensed positions of the printed marks on the tubes relative to the phase positions of corresponding ones of said knives exceed predetermined values; said means for moving including: loop-forming indexing rollers associated with each half tube and positioned downstream of the station for applying reinforcing strips; electric motors for independently controlling the positions of each of said indexing rollers, said motors being responsive to respective ones of said control signals so that the positions of the rollers are determined by the relationship between sensed printed marks on the tubes and sensed phase positions of said knives; feeding means for feeding tubes from said indexing rollers to said transverse welding and separating means; and second photocell means for sensing printed marks on the tubes and for independently stopping said feeding means so that the tubes are correctly positioned with respect to said transverse welding and separating means.