摘要 |
<p>A longitudinal welding apparatus in a packaging machine for products fed on a conveyor belt, comprising a rocking circular welder which overlies the superposed longitudinal edges of a continuous plastics film in which the products are wrapped, the rocking circular welder consisting of at least two independently powered, separate semicircular welding elements, the welder being rotatable to position one of its welding elements on the superposed edges of the film, sensors being provided to measure the speed of advancement of the film and to control, via an electronic control device, both the rotation of the welder and the variation in the feed voltage of at least one of the welding elements. <IMAGE></p> |