Apparatus for making plastic carrier bags

Claim 1

Apparatus for making plastic carrier bags of a preselected width from a tubular web of plastic film material, comprising: feeding means for intermittently feeding the tubular web along a path in successive steps each corresponding to the width of the bags to be made; cutting means along said path for cutting the tubular web at a central region thereof into half tubular webs along an undulating sinusoidal curve to form undulations having peaks and troughs in adjacent edges of the half tubular webs, said cutting means including a cutting member; a carriage mounted for movement transversely to the feeding direction of the tubular web, said cutting member of said cutting means being pivotably mounted on said carriage for pivoting movement about an axis perpendicular to a plane of the tubular web; first lever means for reciprocating said carriage transversely of the direction of advancement of the tubular web in synchronism with the intermittent feeding of the tubular web by said feeding means, such that said cutting member cuts the tubular web along the undulating sinusoidal curve, said first lever means being pivotably mounted adjacent one end and being pivotably connected adjacent an opposite end to said carriage; means comprising a first continuously driven control cam engaged with said first lever means for oscillating said first lever means to cause reciprocation of said carriage in said synchronism; second lever means for pivoting said cutting member in synchronism with the reciprocation of said carriage by said first lever means and the intermittent feeding of the tubular web by said feeding means, so as to maintain said cutting member substantially tangential to the undulating curve at the cutting point of the undulating curve, said second lever means being pivotably mounted and having one end connected to said pivotably mounted cutting member; means comprising a second continuously driven control cam engaged with said second lever means for pivoting said second lever means and thereby pivoting said cutting member in said synchronism; diverting means along said path for displacing the half tubular webs longitudinally relative to each other by half the width of the bags such that respective ones of the peaks and troughs of the half tubular webs are in an aligned opposed mirror image relationship to each other; and transverse welding and cutting means along said path for simultaneously welding and cutting the half tubular webs centrally through respective ones of the troughs of the half tubular webs which are in aligned opposed mirror image relationship to each other, to form the plastic tubular carrier bags.