| 摘要 |
In an apparatus useful for sealing layers of a web comprised of plastic film layers to one another in a bag-making machine, a sealing drum having a cylindrical surface is employed. A sealing blanket is deployed about plural blanket rolls and about the sealing drum so that a substantial portion of the cylindrical surface of the sealing drum is wrapped by the sealing blanket with the wrapping surface facing the cylindrical surface while the remaining portion of the cylindrical surface is not wrapped thereby at any given time. A nip roll acts together with one of the blanket rolls so as to define a nip. An idle roll is located near the nip. The sealing apparatus is operable so that the sealing blanket is drawn through the nip with the wrapping surface facing the nip roll, so that the web is drawn through the nip, between the nip roll and the wrapping surface of the sealing blanket, then around the idle roll, and then around the sealing drum, between the wrapping surface of the sealing blanket and the cylindrical surface of the sealing drum. The nip roll is pressed pneumatically with an adjustable pressure toward the blanket roll acting together with the nip roll, whereby the nip roll controls the tension on the web being drawn through the nip. <IMAGE> |
