| 摘要 |
Starting with a continuous flat sheet upper forming means define a central portion of the sheet which will form the top of the wrapper and two side flaps each of which is situated between the central portion and a respective longitudinal edge of the sheet. Lower forming means fold these side flaps downwardly under a plate for closure of the wrapper and, due to the advance of the folded sheet, cause the joining of the longitudinal edges of the sheet and the consequent formation of a tubular wrapper. The forming means consist of rollers whose position relative to the closure plate as well as their relative positions, can be selectively adjusted while the geometry of formation of the sheet is kept substantially unaltered.
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