Abstract: A stretch wrapping system including apparatus and process is disclosed in which rotation of a non-cylindrical or off-centered load draws film web at a continually fluctuating speed from a film roll through a prestretching device to wrap the load. The prestretching device includes an upstream roller coupled to a braking device and a downstream roller coupled to a positive torque device. The speed of the downstream roller is proportional to the take-up speed of the web on the load and the feedback device continually senses the speed of both rollers and adjusts the braking device so that the speed ratio of the rollers produces a constant stretch of the film web above its yield point. The feedback device also continually senses the forces contributed by the braking device and the torque device and continually adjusts the torque device so that the force on the web between the downstream roller and the load is held constant at a level below the yield point of the web.

Abstract: A stretch wrapping system including apparatus and process is disclosed in which rotation of a noncylindrical or off-centered load draws film web at a continually fluctuating speed from a film roll through a prestretching device to wrap the load. The prestretching device includes an upstream roller coupled to a braking device and a downstream roller coupled to a positive torque device. The speed of the downstream roller is proportional to the take-up speed of the web on the load and the feedback device continually senses the speed of both rollers and adjusts the braking device so that the speed ratio of the rollers produces a constant stretch of the film web above its yield point. The feedback device also continually senses the forces contributed by the braking device and the torque device and continually adjusts the torque device so that the force on the web between the downstream roller and the load is held constant at a level below the yield point of the web.