Signal processing methods for melt pump outlet pressure analysis

This paper presents the development of an on-line monitoring system for a textile quality control application. The feature analyzed is the pack pressure associated with the melt spinning process. Any variations in the pack pressure will affect the rate of flow of melt through the spinnerette and this in turn will result in non-uniform diameter along the filament length. This paper focusses on variations caused by misalignment between the motor and melt pump shaft, and the meshing action of the gear teeth in the melt pump. A new method which uses the autocovariance of the pack pressure data to detect misalignment is proposed. Signal processing methods using median filtering and M-point averaging are presented which can be used to obtain useful information on the gear teeth structure.