| 摘要 |
Apparatus for intermittently pull advancing a sheeting web, such as a tubular or semi-tubular web of synthetic thermoplastics material, which is to be fed to a succeeding transverse welding and transverse severing apparatus of a bagmaking machine, comprises an intermittently rotatably drivable pair of feed rollers (2,3) including an upper roller (3). The feed rollers (2,3) are connected to belt pulleys, cogged belt pulleys or chain sprockets, and a belt (5) or a chain is trained in S shape around said pulleys or sprockets rotatably to drive them jointly in mutually opposite directions. In one aspect of the invention the upper roller (3) is pivoted to the machine frame (1) by being mounted on those ends of parallel links (4) which are the forward end to the direction of travel of the sheeting web (12), at least one of which links (4) is biased by resilient means (15). In another aspect of the invention the upper roller (3) is mounted in at least substantially vertically displaceable bearings, at least one of which is biased by resilient means and in each case the belt (5) or chain extends at such an angle to the belt pulley or the chain sprocket associated with the upper roller (3) that the forces acting on the roller as a result of the driving belt or chain act to press the upper roller (3) more tightly against lower roller (2) preventing slippage of the web between the rollers. <IMAGE> |
