| 摘要 |
Apparatus for forming transverse seam welds or separated transverse seam welds in tubular or semitubular plastic film webs, preferably for making bags, comprises transverse welding device having jaws which are adapted to be cyclically opened and closed and between which the film web is intermittently advanced when the jaws are open and is held in position during the welding times, and a rocker lever, which by means of a cam slot and a slide block imparts to the transverse welding device or to the film web a movement in the same or opposite direction, which movement is derived from a rotating eccentric cam wheel. In one embodiment of the invention, the lever is provided with a straight track, a first slide block is longitudinally guided in said track and is connected by a common pivot to a second slide block, which is movable in a straight slide track, which constitutes the base of a triangle, the legs of which are defined by the lever in both of its end positions, the slide track is movable parallel to itself and adapted to be fixed in position in the machine frame, and one of the slide blocks has connected to it a lever, which remains parallel to itself and is adapted to transmit the motion to the welding device or to the film web. In another embodiment of the invention, the lever is provided with a straight radial track, in which a slide block is longitudinally slidable, the axle of the slide block is mounted in a carrier, which is guided in the machine frame to be longitudinally slidable while remaining parallel to itself, the mounting provided in the carrier for the axle is movable transversely to the direction of movement of the carrier and adapted to be fixed in position, said mounting is movable along the base of a triangle which has legs defined by the lever in its end positions, and the carrier has connected to it a lever, which remains parallel to itself and is adapted to transmit the movement to the welding device or to the film web. |
