Textiles: fiber preparation – Working – Drafting
Patent
1997-01-10
1998-10-06
Crowder, C. D.
Textiles: fiber preparation
Working
Drafting
19236, 19239, D01H 532
Patent
active
058158898
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The invention relates to a method of regulating a drafting arrangement and, more particularly, to a method of regulating a drafting arrangement in which inconsistencies in thickness of a sliver are corrected during the drafting process. The invention also relates to a regulating device for carrying out the method.
Methods directed to achieving such regulation of a drafting arrangement have been addressed in the art, one such method described for example in German DE-OS 36 22 584. In accordance with the disclosed method, the thickness of the sliver is measured at the feed and delivery ends of the drafting arrangement. The measured values are evaluated with a time delay and, depending on the measured mass per unit of length and a set value for the mass per unit of length, are converted into an adjusting signal. From the difference between the measured mass and the preset value, a desired value is obtained by means of a first regulating circuit. This target value and a mass deviation evaluated with a time delay are used to generate, by means of a second regulating circuit, a correcting variable for setting the draft of the drafting arrangement.
This type of procedure has considerable disadvantages. For example, the draft may not always be reliably corrected exactly where the deviation from the set value has been detected within the sliver. Although the evaluation of the second measuring signal and the second control action reduces the probability of possible error thereby increasing likelihood of achieving an accurate, deviation-controlled drafted sliver as compared with a system with a single means for regulation, there still remains a chance of error.
In another regulating process described in German DE 42 02 352 A1, measuring devices are also arranged at the feed and delivery ends of the drafting arrangement and their measured values are compared with one another. The result is corrected by means of stored information and converted into an adjusting signal.
Such a regulator is relatively expensive, and the thickness of the sliver ascertained at the feed end of the drafting arrangement is not always corrected where necessary.
In this method it has been suggested that the time delay from the measuring point at the feed end of the drafting arrangement to the time of the output of the correcting command be represented as a variable of certain empirical values and other parameters. However, the results obtained in this way are still unsatisfactory insofar as random factors cannot be excluded (DE 42 15 682 and 42 02 352).
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide a method of regulating a drafting arrangement which overcomes the drawbacks of the prior art.
It is a further object of the present invention to provide a method of regulating a drafting arrangement in which the thickness of the sliver is reliably corrected in the place where the deviation has been detected.
It is still a further object of the invention to provide a device for carrying out the regulation method in a form which provides ease of operation and low maintenance, and which guarantees consistently good control results at any adjusted speed of the machine.
Briefly stated, the invention relates to a method of regulating a drafting arrangement, in which measuring signals are acquired at a feed end of the drafting arrangement, compared with a set value to provide a differential signal, and an adjusting signal for the control unit of a variable speed motor for the pair of drafting rollers is derived from the differential signal, provides reliable control results and adjustment of the sliver where a difference has been detected. Set values are entered by a transfer address from a set-point register. The basic speed is derived from actual speed of a doffer and supplied as basic voltage to the control unit of the variable speed motor. A measuring clock pulse of low frequency is generated, dependent upon a roller of the drafting arrangement. With every measuring clock pulse
REFERENCES:
patent: 4819301 (1989-04-01), Konig et al.
patent: 5384934 (1995-01-01), Dammig
patent: 5388310 (1995-02-01), Haworth
patent: 5509179 (1996-04-01), Mondini et al.
Barth Gerhard
Enghardt Thomas
Heinecke Thomas
Zeidler Gert
Crowder C. D.
CSM-Saechsische Spinnereimaschinen GmbH
Worrell Jr. Larry D.
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