| 摘要 |
A roll (50) of sheet material, such as plastic film wrap, having an inner layer wound at low tension and an outer layer wound under greater tension provides a coreless roll. Eliminating the need for a core reduces the cost of producing rolls of sheet material, and reduces the weight and outer dimensions of the roll with a consequent reduction in shipping and storage costs. An apparatus (10) and method for producing such a roll (50), from a pre-wound master roll (20) or as part of a production line for forming the sheet material, involves varying the longitudinal tension applied to the sheet material (22) as it is wound onto an expandable mandrel (100). After the roll (50) has cured, the mandrel (100) is collapsed and disengaged from the roll (50) to provide a coreless roll (50). The master roll (20) can be pre-stretched prior to forming the coreless roll (50), if desired, and can be pre-stretched as a step in the formation of the coreless roll (50).
|
