Draw process

Details Draw process Draw process

1995-07-31

1997-09-09

Calvert, John J.

Textiles: manufacturing

Thread finishing

Surface modification of running length

D01D 512, D01D 516, G01L 504, G05D 2300

Patent

active

056643071

DESCRIPTION:

BRIEF SUMMARY
BACKGROUND OF THE INVENTION

This invention relates to a method of drawing yarns in a draw zone which is equipped with a tempering device for influencing the temperature of the yarn, and an apparatus for drawing a yarn advancing through a draw zone with a tempering device for influencing the yarn temperature.
Such a method or such an apparatus are known, for example, from DE-OS 38 08 854, as well as from DE-PS 33 46 677, and DE-AS 22 04 535. In the known draw systems, the yarn is drawn by pulling it off the spinneret at very high withdrawal speeds and/or by the speed difference of two interposed draw rolls, and in each case it is heated in the draw zone. This invention is, however, not limited to such methods, but is suitable for all draw systems, which are equipped with tempering devices for influencing the yarn temperature.
In the art, there exists a factor of uncertainty in keeping the process parameters and the produced yarn properties constant in time, namely, in that the heat transfer between the yarn and the tempering device for influencing the yarn temperature, for example, a heated draw roll, heated tube, or cooling device (see, for example German Utility Model 9306510) does not remain constant, but changes in the course of time. Such unintended changes in the heat transfer cannot be detected, since in a continuous operation it is not possible to accurately measure the yarn temperature from the viewpoint of the measuring technology, whereas the temperature of the device for influencing the yarn temperature (hereafter described as tempering device or temperature modulating device) is controllable, though, but fails to be indicative of the actual heat exchange. Such variations in the exchange of heat, may originate, for example, from contaminations or wear or other operational, but unforeseen changes.
It is the object of this invention to describe a method and an apparatus, which allow the detect and eliminate unforeseen variations in the heat exchange between the tempering device and the yarn or their consequences.


SUMMARY OF THE INVENTION

The above and other objects and advantages of the present invention are achieved by the provision of a method and apparatus for processing an advancing yarn which includes the steps of advancing the yarn along a path of travel, applying a drawing force to the advancing yarn in a draw zone located along the path of travel and so as to draw the advancing yarn, and monitoring the tension of the advancing yarn at a location along the path of travel downstream of the draw zone and producing a control signal which is representative of the monitored tension. Further, the temperature of the advancing yarn is modulated so that the temperature of the yarn is controlled as a function of the control signal.
In accordance with the invention, the method of drawing yarns in a draw zone equipped with a tempering device for influencing the temperature of the yarn is characterized in that the yarn temperature influencing effect of the tempering device on the yarn is controlled as a function of a control signal, which is derived from the yarn tensile force (yarn tension) that is continuously measured at a measuring point within or downstream of the draw zone, the measuring point being selected such that the yarn speed remains substantially constant between the heating system and the measuring point. The formation of a difference between the actual value of the yarn tension and an predeterminable desired value is a further development, which has the advantage that from the viewpoint of process engineering an optimal input of the yarn tension is initially possible, and that only the variations from this input are detected and converted for adjusting the temperature of the tempering device, i.e., the heating or the cooling system.
The invention relates likewise to an apparatus for drawing a yarn advancing through a draw zone, which is provided with a tempering device for influencing the yarn temperature, and especially suitable for carrying out the method of the present invention.

REFERENCES:
patent: 2617007 (1952-11-01), Atkins
patent: 2930102 (1960-03-01), Hitchin et al.
patent: 3211893 (1965-10-01), Barlow et al.
patent: 3395200 (1968-07-01), Mader, Jr. et al.
patent: 3509595 (1970-05-01), Mader, Jr. et al.
patent: 4404718 (1983-09-01), Tajiri et al.
patent: 4608736 (1986-09-01), Tajiri et al.
patent: 4902461 (1990-02-01), Schippers
Patent Abstracts of Japan, Publication No. JP5117929, Publication Date Feb. 9, 1993; Applicant: Murata Mach Ltd; Inventor: Matsui Isamu; Title: Cooling Plate For Draw-False Twister (JP5,117,929 pub. date May 1993).

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