GB2053791A - Apparatus for use in the solidification of melt-spun polymer threads - Google Patents

Abstract

Apparatus suitable for use in the continuous preparation of a thread of a melt-spinnable polymer, which comprises one or more spinnerets 5 through which the polymer is spun, air blast supply means 8, and a blast shaft 7 in which the spun thread is cooled, in which the apparatus further comprises an air channel 9 and a deflection member 18 through which air from the supply means can flow and be deflected, substantially free of turbulence, across the direction of travel of the thread. <IMAGE>

Description

SPECIFICATION Apparatus for use in the continuous preparation of threads of melt-spinnable polymers It is well known that, for the continuous preparation of synthetic threads of polymers, e.g. of polyamide, polyester or polypropylene, a melt-spinning plant is necessary, as is described, e.g. in F. Fourn's " Preparation of Synthetic Fibres", 1964 page 72, or by G. Schubert in " Fibre Producer", June 1978, page 16.

A typical melt-spinning plant comprises a storage silo from which dried granulate passes into an extruder in which it is melted and passed under pressure, over a dividing system, to a spinning beam. Using one or more pumps, a predetermined, homogeneous stream of the polymeric material is delivered from one or more spinnerets and spun through a blast shaft. The storage silo, extruder and blast are arranged vertically.

The spun polymeric thread is solidified and cooled in the upright blast shaft with a horizontal stream of, for example, conditioned air at air speeds of, e.g. 0.3 to 0.8 m/sec. The blast tunnel may be 1.2 to 1.8 m long. For good yarn quality, the air blast must be free of turbulence. The air is usually directed to the blast shaft of one or more spinning apparatus from a common pressure chamber which, in order to direct the air without deflection into the blast shafts, is arranged under the blast shafts. In a connected spinning shaft, which may be about 4 m long, the thread is further cooled, to approximately room temperature.

The iower end of the spinning shaft generally comprises a small opening for the passage of the thread and thereby possesses a certain storage capability on breakage of the thread. Any windingup machine positioned below the spinning shaft can thereby be protected from damage on breakage of the yarn.

Often, a supplementary thread suction channel is provided at the upper level of the winding-up machine in the case of fast spinning apparatus.

Broken threads can be removed through this suction channel.

On winding-up, the thread is usually first provided with a film of a suitable spinning preparation, by means of rotating galettes or fixed preparation pins and dosage pumps. The thread can be led onto a winding-up spool over fixed or rotating galettes, the direction of travel of the thread thereby being changed. Depending on the conditions, the windingup speed may be 500 to 5000 m/min.

For high winding-up speeds, it may be necessary to collect the thread between the blast and spinning shafts, possibly with the simultaneous application of a suitable preparation; in this case, an advantageous thread stretching reduction can be achieved for the winding-up under given conditions, owing to the lower thread cross-section and the associated reduction in the amount of trapped air.

It is a disadvantage of the plants of the type described that they may be 14 to 16 m high. Owing to the differences in pressure between the stages of the apparatus, air pressure locks may be needed.

The vertical spacing of the stages means that simple regulation of operation is difficult. Further costs are incurred if a thread suction channel is used.

It has been proposed to reduce the height of such a plant by omitting the spinning shaft or by juxtaposing, horizontally, the spinning shaft and the windingup apparatus.

If the spinning shaft is omitted, a considerable deterioration oftheyarn quality must be accepted owing to the lack of stabilisation of the air blast.

Further, thread breakage may lead to disruption of operation and/or damage to the winding-up apparatus or the wound threads.

If the spinning shaft and the winding-up apparatus are juxtaposed, a vertical, but no absolute, space saving is achieved. Further, since the thread must undergo some deflection over stationary and/or rotating members, e.g. galettes, fine or sensitive yarns can be destroyed.

Surprisingly, it has now been found that good quality yarn with low wastage can be obtained in a vertical thread path by the use of a blast shaft which need only be 0.4 to 1.0 m long and with air speeds of 1 to 4 m/sec arid by positioning the blast shaft directly above the winding-up machine, if the air blast is delivered free of turbulence through a pressure-stabilising channel or area by means of rectilinear delivery channels and the winding-up machine, positioned at 1800 in relation to the blast shaft, is provided with an inclined thread transport chute.

According to the present invention, apparatus suitable for use in the continuous preparation of a thread of a melt-spinnable polymer comprises one or more spinnerets through which the polymer is spun, air blast supply means, a blast shaft in which the spun thread is cooled and, additionally, an air channel and a deflection member through which air from the supply means can flow and be deflected, substantially free of turbulence, across the direction of travel of the thread.

The flow through the air channel and the deflection member and across the thread travel direction should be substantially rectilinear either side of deflection. The flow path through the supply channel is preferably at least as long, and more preferably at least twice as long, as that through the deflection member.

It is also preferred that the supply channel and the deflection member, at their mutual joint, should have the same cross-section. The deflection of the air flow into the deflection member is preferably approximately 90 .

The deflection member itself preferably comprises a substantially flat deflection surface and substantially parallel side walls parallel to the direction of the air flow. This member may have a substantially rectangular deflection surface and trapezoidal side walls, the air flow entry and exit cross-sections being rectangular.

The treads spun in use of apparatus of the invention are derived from melt-spinnable polymers such as, for example, polyamides, polyesters or polypropylene. The spun threads can be used for the preparation of filaments and fibres. These threads or filaments or fibre are usually developed, directly on their preparation, or after collection, unwound into cans, or stretched and wound-up, or stretched, texturised and wound up, or (after collection of several threads) stretched, texturised and wound off into cans.

In the blast shaft, the threads can be handled further if desired, e.g. with handling fluids such as brightening agents, etc.

In a further preferred embodiment of the invention, the operation side of the winding-up machine is positioned turned at 1800 to the direction of the air blast stream. The reverse upper part of the windingup machine preferably contains a thread transport chute or is formed as such. This chute is preferably positioned at an angle of 30 to 70, particularly 40 to 500, to the horizontal.

When using apparatus according to the invention, e.g. for the fast spinning of pre-oriented yarn, without using transport galettes, the thread or thread bundies can be taken up on the winding-up machine from the transport chute at the beginning of production by means of a suitable injection gun, and collected there during the spinning phase.- On deposition in the preparation and thread delivery structures, the individual threads are separated and then laid on the spools for winding-up.

During the complete running of the process, the correct working of all machiney, such as spinnerets, blower, preparation equipment, thread duct and winding-up can be observed centrally from the winding-up machine.

On thread breakage, e.g. by faulty manipulation of the changing of the full spool or by a disruption in spinning, the thread bundle is increasingly deflected horizontally by the now reduced vertical stress of the thread through the air blast, whereby it leaves its normal path and passes onto the transport chute along which it can be lead continuously to a refuse collection holder.

If desired the thread can be lead over two or more stretchng galettes, before winding-up, for the preparation of fully-stretched filament yarn. The yarn is stretched owing to the different surface speed of the galettes.

Further, it is possible to conduct the thus-stretched thread through crimping equipment, before winding-up, so that a wool-like crimped yarn is obtained.

Apparatus according to the invention is particularly suitable where, after preparation application and sideways deflection, a large number of the threads are collected and deposited in an uptake apparatus (spinning can) by means of common removal apparatus. Owing to the low turbulence removal of the threads dragged along by the air blastthroughthe transport chute and the short free thread lengths between spinneret and first thread lead on the winding-up machine, adhesions can be low and the quality of the end product good.

The invention will now be described by way of example with reference to the accompanying drawing which is a schematic illustration of apparatus according to the invention. In the drawing, a meltextruder 1 is provided with the necessary material from a granulate silo 2. Melted-down polymer from the extruder passes into a spinning beam 3 via spinning pumps 4to one or more spinnerets 5.

Extruded thread 6 is solidified and cooled in the blast shaft 7 positioned vertically thereunder by means of an air blast from a pressure chamber 8 via supply channel 9 and deflection member 18.

The thread then passes to a winder 13 over thread preparation equipment 10 and a thread lead 11 in a winding-up machine 12 where it is wound up onto a spool 14.

On thread breakage, the thread 15, now further deflected by the air blast, is laid on the transport chute 16 on the rear side of the machine, from where it is lead aff into a refuse container collector 17.

The total height of the apparatus can be less than six metres.

In contrast to the standard forms of the apparatus, that according to the invention exhibits a number of advantages.

The apparatus can, on account of its low building height, less than 40% of the standard building height, by put up with unaltered horizontal extent in a building of about 6 metres height without the use of racket floors. Expensive installations such as vertical transport means, pressure difference control and communication means between the production areas can therefore be avoided. The technical force necessary for the operation of the operation of the apparatus can be reduced, as spinning and windingup can be controlled and serviced from one level.

The short thread path from the spinneret to the winding-up allows working with low thread tension.

The improved handling of yarn resulting therefrom is shown in high quality and yield. The working-up of the yarn to the spool bundle can be substantially problem-free.

No compressed air need be used to remove broken thread. Further, the thread removal means which is part of this invention reduces damage to the wound aggregates in the winding-up machine.

By allowing correct regulation of the air blast inlet, and a sufficiently large pressure equalisation area, there are equal blast conditions for all threads in the blast shaft. This allows good and consistent yarn quality, especially for multi-thread spinning systems.

Moreover, by using a vertical thread path, many individual spinning units can be juxtaposed in one plant.

The following Examples illustrate the invention.

Example I In apparatus of the type illustrated in the accompanying drawing, dried polyethylene terephthalate was melted in the extruder and, using a pump having an output of 87.5 g/min, through a 30- hole spinneret. The blast shaft was about 0.7 m long. The filaments were cooled using a horizontal air stream having a speed of about 2 m/sec. The threads were wound up at a speed of 3500 m/min. The total plant height was 5.8 m.

The wound spools thus prepared had straight, smooth sides and could be worked up satisfactorily.

The spool surface temperature, on removal of the spools from the winding-up machine, was no different from that of spools which had been prepared under analogous conditions in a conventional plant Over a 12 hour period for 8 simultaneously prepared threads, no thread breakage or capillary tearing was observed. The yarn could be worked up to a high-grade textile yarn with the nominal titre of 167/30 dtex.

Example 2 The same apparatus was used as in Example 1 except that, between preparation and winding-up, two spinning stretching galettes, each with an incidental roll, were introduced into the thread path.

Dried poly--caproamide (nylon 6) was melted down in the extruder and spun out using a spinning pump with an output of 20.0 g/min through a spinneret with 12 holes into a blast shaft 0.7 m long.

after cooling the filaments using a horizontal air steam having an air speed of about 1.6 m/sec, and the application of a spinning preparation, the threads were wound repeatedly round each of the two galettes with the incidental rollers and wound up. The speed of the first galette was 4,000 m/min, and that of the second 5,200 m/min, corresponding to a stretching between the galettes of 1:1.3.

The thus-prepared, fully stretched yarn, with a titre of 44/12 dtex, had outstanding uniformity for such yarns of conventional solidity and elongation. The spinning stretching discharge was good, no capillary breakages being observed over about nine hours.

The total height of the plant was 5.8 m.

Claims (11)

1. Apparatus suitable for use in the continuous preparation of a thread of a melt-spinnable polymer, which comprises one or more spinnerets through which the polymer is spun, air blast supply means, and a blast shaft in which the spun thread is cooled, in which the apparatus further comprises an air channel and a deflection member through which air from the supply means can flow and be deflected, substantially free of turbulence, across the direction of travel of the thread.

2. Apparatus according to claim 1 in which the supply channel and the deflection member allow substantially rectilinear flow either side of deflection.

3. Apparatus according to claim 1 or claim 2 in which the flow path through the supply channel is at least as long as that through the deflection member.

4. Apparatus according to claim 3 in which the flow path through the supply channel is at least twice as long as that through the deflection member.

5. Apparatus according to any preceding claim in which the supply channel and the deflection member, at their mutual joint, have the same crosssection.

6. Apparatus according to any preceding claim in which the deflection member causes deflection member causes deflection of the air flow through approximately 90".

7. Apparatus according to any preceding claim in which the deflection member comprises a substantially flat deflection surface and substantially parallel sidewalls parallel to the direction of the air flow.

8. Apparatus according to any preceding claim additionally comprising a thread winding-up machine oriented at 1800 to the thread travel direction.

9. Apparatus according to claim 1 substantially as herein described with reference to the accompanying drawing.

10. A method for the continuous preparation of threads of a melt-spinnable polymer, which comprises spinning the polymer through apparatus according to any preceding claim.

11. Any novel feature described herein, alone or in combination with any other feature, novel or otherwise.