| 摘要 |
A packaging machine and method for simultaneously loading, sealing and severing bags forming part of at least two independent chains of bags. Two juxtaposed nip roll assemblies including axially aligned feed roll portions can be independently actuated in order to selectively feed one or two webs. A drive motor, having a dual output, is selectively coupled to the nip roll assemblies by clutch/brake units which can be selectively actuated. After a bag or bags are loaded, a sealing mechanism is actuated to seal the loaded bag or bags. A sensor monitors movement in a seal unit member and terminates the sealing cycle if movement in the seal member occurs prior to the pressure bar reaching a predetermined position. While a bag or bags are being sealed, a tear off mechanism including a rod-like member is advanced into and through the web path in order to sever the loaded bag from the remainder of the web. Actuators operatively connected to distal ends of the member are actuated sequentially in order to move one end of the rod into contact with the web before the other end makes contact. As a consequence, severance of a bag along a line of weakness begins at one marginal edge of the bag and proceeds towards its opposite marginal edge. In an alternate embodiment, the stepper motor drive is used to advance bags to a loading station and when using loading funnels, are used to retract the bag in order to have a mouth of the bag engage a loading funnel. In addition, the stepper motor drive can be used to sever loading bags from the remainder of the web by reverse feeding the webs either concurrently or in a staggered relationship.
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