UT4-04-Spectrogram..doc

Contents 4 Mass Spectrogram 1 4.1 Normal Spectrogram shapes according to different fiber types 1 4.2 Periodic faults (chimneys) 2 4.2.1 Distinguishing disturbing periodic faults from tolerable faults 3 4.2.2 Multiple Periods 4 4.2.3 Examples of common periodic fault types in textile practice 5 4.2.4 Spectrogram calculations / Finding the source of periodic faults 6 4.2.5 Calculation examples of periodic faults originating in drafting systems 8 4.2.6 Calculation example of a periodic fault caused in the machine’s gear sector 10 4.3 Drafting Faults 11 4.3.1 Examples of drafting faults originating in different process stages 12 4.4 Special Spectrogram faults 14 4.4.1 Coiler periodicity 14 4.4.2 Protection twist periodicity 14 4.4.3 Faults caused by Autolevellers 15 4.4.4 Comber periodicity 16 4.4.5 Card faults 17  Mass Spectrogram [物]光谱图, 光谱照片, 声谱图 The mass spectrogram graphically illustrates the amount and intensity of linear mass variations of the test material according to the wavelength of the variations. In most cases, the spectrogram results should be regular shapes with minor deviations. For each type of material, depending on the fiber length and length distribution, different basic spectrogram shapes will result after testing. Normal Spectrogram shapes according to different fiber types: Combed Cotton yarn, main crest at ~7cm OE Cotton yarn, main crest at ~5cm Wool yarn, main crest at ~22cm Cut staple yarn, main crest at ~9cm, dip at ~3.5cm (dip at the actual fiber length) The main crest, i.e. the top of the main ?hill“ of the spectrogram is approximately 2.8 times the average fiber length in mm.  Among the natural random variations present in the test material, there can be undesired systematic variations, which make the spectrogram appear different than normal. They appear as “chimney” peaks or “hill” crests in the spectrogram. Periodic faults (chimneys) Ex