Computer Control of Heat-Setting Conditions for Synthetic Yarns

In the earlier designs the steam atmosphere was essentially static, which simplified control but limited the rate of yarn temperature rise and hence restricted throughput. Later models therefore incorporated a steam circulation system, which improved throughput potential but posed problems for temperature control in the cooling zones, as the steam/air interface drifted.

In addition to automatic control of steam pressure and therefore temperature in the control chamber, the equipment as supplied was equipped with a manual control system for the outlet air pressure. Increasing this pressure forces the steam/air boundary back up the tunnel and effectively lowers the temperature of the outlet cooling zone.

This manual control requires continual adjustment for maintaining the temperature differential between the two cooling zones, a parameter shown to be important for the manufacture of high quality uniformly dyeing yarn.

Accordingly, Superba now produce a computer-controlled system which senses the temperature at each end of the tunnel and continually adjusts air flow to each end to achieve a temperature differential within limits. This system is acceptable if all components such as valves are working satisfactorily, but in practice it does not always achieve automatic control and some manual adjustment, such as opening or closing the nip at the tunnel exit or entrance, is necessary to maintain control.

Fibremakers have introduced a more sophisticated computer system which, along with other refinements, controls the differential pressure between the cooling zones, as well as the differential temperature. This makes the control more positive and precise, and therefore a tighter differential temperature range is obtainable. It also simplifies analysis when control problems arise (for example, the extent to which the steam valve is open is monitored on the screen, along with chamber and cooling zones temperatures and pressures, and/or differential values).

There is much evidence that in the past 200 years Australia has been capable of good technological innovation. At times these have been prompted by a need for survival and there is little doubt that whilst the Australian textile industry continues to exist, innovations such as those described above will continue to be made. No doubt there have been many missed opportunities and if they had been taken up the state of the industry would have been much healthier.

These missed opportunities reflect management weaknesses rather than an inability to develop new technologies and it is mainly those management weaknesses which give rise to the growing fears that there will soon be no textile industry base from which to innovate. If such should be the case, the writer of a similar Chapter to celebrate Australia's Tri-Centenary will have to rely heavily on the contributions made by those Australian innovations which have been made with the intention of increasing the use of Australia's principal natural fibres in the textile industries of other countries.

Australian Academy of Technological Sciences and Engineering