| 摘要 |
An open-end spinning machine includes a low inertia sensing wheel frictionally engaging the package so that the rate of rotation of the frictional sensing wheel is sensed by a tachometer generator to provide a "winding rate" signal fed to a controller for controlling the speed of a stepper motor driving the fibre feed roller of the fibre opening unit during piecing, in response to the take-up of yarn at the package. Optionally, the sensing wheel is supported on a link such that the angular position of the link indicative of the diameter of the package is sensed by an angular position transducer and the signal of the transducer is also fed to the controller. Yarn delivery rolls are separated, during piecing, to allow the rate of withdrawal of the yarn from the doffing tube of the open-end spinning unit in response solely to the accelerating package. The draft is non-linear during piecing, in accordance with a predetermined programme.
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