Textiles: fiber preparation – Working – Drafting
Patent
1993-10-05
1995-07-04
Crowder, Clifford D.
Textiles: fiber preparation
Working
Drafting
D01H 538
Patent
active
054288703
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to a method for regulating the draw of a drawing unit, in which each drawing zone formed by pairs of rollers is driven by a separate motor and the desired draw is adjustable by means of a corresponding control of the speed of the motors.
BACKGROUND OF THE INVENTION
CH-A-650,280 describes a drawing frame which, for each pair of rollers, has a separate drive motor, the speed of which is adjustable by means of a frequency divider. A computer containing an input and an indicator device calculates the speed ratios for the motors according to the input data and adjusts the drawing frame accordingly. The computer can also be assigned a measuring member for the fineness of the fibre sliver, from the measurement signal of which can be derived a non-uniformity signal characterising the non-uniformity of the fibre sliver.
When deviations of the draw from the input values occur on this drawing frame, these can be recognised only indirectly from their effects on the non-uniformity of the fibre sliver. This method of regulating the draw by means of the fibre sliver constitutes a so-called long-time regulation which, in view of its inertia, cannot satisfy the practical demands for a regulation of the draw. In addition, the deviations in the draw become noticeable as non-uniformity of the sliver only when a particular value is exceeded, and therefore, in particular, a drift of the system as a whole can be recognised only with great difficulty by means of the non-uniformity of the sliver.
SUMMARY OF THE INVENTION
Therefore, the invention is intended to provide a regulation of the draw which allows a rapid reaction to fluctuations in the draw and in which the necessary corrections can be made as simply as possible and which permits as drift-free an operation as possible.
In a method of the type mentioned in the introduction, this object is achieved by means of the following steps: unit; unit; the deviation between these; quantity; and quantity.
The method according to the invention is based on forward compensation which is also designated as desired-quantity integration. In addition to the rapid reaction to fluctuations in the draw and the possibility of simple execution of corrections, it is characterised, in particular, in that the system is independent of drift. In fact, the system has no overall drift, because a possible drift of individual components is corrected out.
The invention relates, furthermore, to a device for carrying out said method, with a drawing unit consisting of pairs of rollers and having a constant and a variable drawing zone, with drive motors assigned to the pairs of rollers, and with a regulating unit for adjusting the drawing frame.
The device according to the invention is characterised in that the variable drawing zone is assigned two drive motors, in that first and second means for measuring the sliver speed at the entrance and at the exit of the drawing unit respectively are provided, and in that said means are connected to the regulating unit, in which an evaluation of the measured sliver speed takes place, and in that one of the two drive motors is designed as a variable-speed motor and is controlled by the regulating unit.
BRIEF DESCRIPTION OF THE DRAWING FIGURES
The invention is explained in more detail below by means of exemplary embodiments and the drawings; in these:
FIG. 1 shows a basic diagram of a draw regulation according to the invention in a drawing frame; and
FIG. 2 shows a diagram of a drawing frame with a draw regulation according to the invention and a sliver-regulating control in a representation different from that of FIG. 1.
DETAILED DESCRIPTION OF THE PRESENT INVENTION
FIG. 1 illustrates a drawing unit of a two-headed drawing frame for the folding or drawing of fibre slivers, to which two groups of fibre slivers are fed in the direction of the arrows VI and which delivers two fibre slivers at its exit (arrows VA). However, the arrangement of two deliveries is not essential to the invention, nor is the inventi
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"Autolevelling Systems at Carding and Drawing from a Technological Point of View", Uster News Bulletin, No. 30, pp. 1-22 (Aug. 1982).
Baechler Francois
Rutz Hansjorg
Crowder Clifford D.
Izaguirre Ismael
Zellweger Luwa AG
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