| 摘要 |
An improved-efficiency welding device in a plastic bag production machine, of the type comprising an upper welding bar (13) and a lower welding bar (14), at least one of which is driven with reciprocating vertical movement between a position separated from the plastics material to be welded and a position in contact with the plastics material and the lower or upper other bar, the movement of the at least one welding bar being imparted by a pair of vertically guided rods (15) driven by a first eccentric linkage (18, 20, 21) to which they are connected by a pin (27), the first linkage obtaining its movement from a central shaft (19), there being provided a second eccentric (30) between the rod and the first eccentric linkage (18, 20, 21) and driven by an additional motion transmission system (25, 26; 125, 126, 33) which rotates it to cause the at least one welding bar (13, 14) to undergo a further lowering and/or raising movement at a predetermined stage, with resultant welding engagement between the at least one welding bar (13, 14) and the other welding bar (14, 13). <IMAGE> |
