IL31831A - Process and device for crimping endless thermoplastic filaments of yarns - Google Patents

Description

moo ικ CBin io o¾ "jpnm v nn PROCESS AND DEVICE FOE CRIKPIMCr EITD1ESS THERMOPLASTIC FILAMENTS OR YARNS LAHZSTOFF AG.

This invention relates in general to a process and a device for crimping endless thermoplastics filaments or yarns.

More particularly the invention relates to a process for the continuous stuffing-box crimping of endless thermoplastics filaments or yarns, wherein the material to be treated is in the form of a filament bundle, is guided, with the aid of a flow of steam, through an injector nozzle into a stuffing box crimping chamber, is deposited in the stuffing box chamber in the shape of three-dimensional helical lines, is set in this shape and is finally pressed through the stuffing box chamber by the force of the material subsequently introduced, and relates also to a device for the performance ofthe process.

Processes of this kind are already known, together with associated devices.

Thus, for example, United States Patent Specification No. 3>296,677 discloses a process whereby the filament bundle guided in an injector nozzle, surrounded by a fluid softening medium, and thereafter is guided together with the fluid medium first of all through a conduit of uniform diameter and then through a conduit of diverging diameter.

Tn the latter conduit, the fluid medium expands gradually. As it does so, the filament bundle opens out, this being accompanied by an increase in volume. Immediately behind the diverging conduit, a small portion of the fluid medium escapes through two filament bundle through the short stuffing-box chamber the end of which is surrounded by a plate spring, and escapes from there into the environment. The stuffing-box crimped filament bundle leaves the stuffing box chamber, mainly against the resistance of the plate spring, and is doffed, via a delivery mechanism, for further processing.

The known process can involve a series of disadvantages. Thus, when using steam as the fluid medium, a steam pressure of approximately 5 atmospheres excess pressure and more, at' steam temperatures higher than 200°C. , is necessary. At such high steam pressures and/or temperatures, it is no longer possible to operate with inexpensive waste steam. On the contrary, what is required is live steam the preparation of which' either overloads the available steam feed system or even makes the provision of a separate steam boiler plant necessary.

Due to the high steam pressure and the fact that the steam flows freely out of the two outlet apertures, the proportion of the steam which escapes from the filament bundle behind the diverging conduit is far below 50$. The crimped yarn which leaves the stuffing box crimping chamber therefore contains moisture to a high degree.

The yarns prepared in accordance with this known process have an irregular, three-dimensional crimp. The plate spring acting on the end of the stuffing box chamber can constitute a considerable hindrance in in between the chamber and the plate spring and result in operational breakdown and capilliary rupture. A yarn of this kind frequently involves difficulty during further processing.

British Patent No..953,482 According to a further known process7, the treatment material is, after being surrounded by v a steam flow in an injector nozzle, conveyed by said steam flow through a wide conduit. The wall of the conduit has no apertures, so that the steam is able to act on the material being treated over a path several centimeters long. This path is additionally prolonged due to the fact that a helical sprin acting as a stuffing box chamber is disposed in a guide bush which is several centimetres long. Only behind this guide bush, i.e. towards the free end of the helical spring, is the steam able to separate itself gradually from the material being treated.

Due to the long path over which the steam and the material travel together, this known process produces a crimped yarn exhibiting a coarsely-arcuate, spiral crimp. If a yarn of this kind is twisted, as i conventional for many purposes of utilisation, then yarn having an extremely small bulk is generally obtained. Furthermore, this process does not guarante reliable conveying through the stuffing box, since individual capillaries may become jammed in between the turns of the helical spring.

Additionally, it is disadvantageous in this process that the steam pressure must be higher than An object of the present invention is to devise a process and an apparatus for the manufacture of a yam which exhibits, relatively to the yarns manufactured in accordance with known processes, an increased degree of crimp stability, a greater bulk, improved dyeing quantities and a high degree of yarn purity.

According to one aspect of the present invention, there is provided a process for the continuous compression crimping and heat setting of a synthetic thermoplastic multifilament yarn which comprises: continuously propelling the initially uncrimped and compact yarn by a jet of steam through a tubular acceleration passagewa having a substantially constant diameter of 2 to 4,8 times the diameter of said compact yarn| passing the yarn and steam -flowing therewith directly from said passageway into an expansion chamber having a diameter of from 8 to 22 times the diameter of said compact yarn while drawing off a major proportion of said steam through lateral openings in said expansion chamber arranged at an interval spaced from the inlet side of said chamber of 0.5 to 2 times the diameter of said chamber, thereby suddenly expanding the flow of steam and opening up the compact yarn with the individual filaments being spread apart? depositing the spread-apart filaments in an elongated compression chamber arranged as a longitudinal extension of said expansion chamber, said filaments being crimped and forced through said compression chamber by the jet action of said steamj passing the remaining minor proportion of said steam through said compression chamber at a temperature sufficiently high to heat said ilaments; and According to another aspect of the present invention, there is provided apparatus for the continuous compression crimping and heat setting of a synthetic thermoplastic multifilament yarn which comprises: an annular steam jet nozzle surrounding a tubular yarn entry passage with means to supply steam to said nozzle; an interchangeable elongated acceleration tube of substantially constant diameter arranged to receive steam and yarn from said nozzle and entry passage for propulsion longitudinally thereof; a separately interchangeable tubular expansion chamber concentrically mounted at the discharge end of said acceleration tube, said expansion chamber having a larger diameter than said acceleration tube and being provided with lateral openings for the discharge of steam therefrom, said openings being arranged at an interval spaced from the inlet side of said expansion chamber of 0.5 to 2 times the diameter of said chamber* a steam discharge line in fluid connection with said expansion chamber through said lateral openings; a tubular extension of said expansion chamber connected thereto and adapted to receive said yarn for compression crimping; and means to collect the crimped yarn from the discharge end of said tubular extension.

We have surprisingly ascertained that an important factor influencing the properties of the yarn is the steam flow proportion drawn off shortly before the stuffing box. Correspondingly, in the process according to the invention, the greater portion of the steam flow is drawn off shortly before the stuffing box. With this arrangement, i is to be possible to regulate the 31831 2 ' proportion of the a earn flow being withdrawn* A further influencing factor is the shape of the transition portion between the acceleration conduit and the subsequent chamber. Since a gradually diverging transition results in unsatisfactory yarn properties, the transition is according to the invention, sudden. Furthermore, by making the acceleration conduit and the inserts forming the chamber replaceable, it is possible to so vary the ratio of conduit to chamber diameter that optimum crimping may be achieved with every type of material to be treated.

It will also be appreciated that the present invention is based on the use of a conveying and setting medium which is inexpensive and is readily available in operation. For this purpose, steam and in particular saturated steam obtained waste steam, is suitable.

As stated, saturated steam is preferred as the conveying medium. The temperatures or steam pressures of the saturated steam entering the injector nozzle are downwardly limited by the requirement to provide a compressed steam which is capable of expansion, and upwardly limited by the requirement that the yarn shall not be thermally damaged by the steam.

The steam properties (pressure, temperature, degree of saturation) determine the essential properties of the crimped yarn (crimp durability, bulk effect, dyeing properties, and the like. When using saturated steam, an optimum is achieved in respect of many yarn properties by employing steam temperatures between 120°C. and 1 5°C. The crimp durability can, however, be still more improved by the preferred process steps mentioned hereinbelow, and all of which contribute to a decrease in the moisture content of the finally crimped yarn.

The crimp durability may be increased by laterally drawing off 70 to 9 of the steam flow through the chamber apertures.

In order to reduce further the moisture proportion in the treated material emerging out of the stuffing box v shortly before the free end of the stuffing box.

The same object may also be achieved by blowing hot air at a temperatures between 100°C. and 150°C, into the free end of the stuffing box.

In order to exclude any possibility of condensati of the steam on the chamber wall, provision may be made for supplementary heating of the chamber.

Finally, it is also possible so to heat parts of the injector nozzle that the steam, originally available as saturated steam, is superheated. By this means, the moisture content of the crimped yarn may again be diminished.

' The material crimped in the stuffing box may, after leaving the stuffing box, be deposited in cans or wound on through the agency of a delivery mechanism.

As previously set forth, the device according to the invention comprises an injector nozzle having a steam feed pipe, an inlet conduit for the treatment material and a replaceable insert which forms the acceleration conduit, a replaceable insert formed with steam discharge apertures over portions of its walls and constituting the chamber, a steam discharge pipe and a stuffing box.

If the residue of the steam flow is to be laterally drawn off a short distance before the free end of the stuffing box, then use is made of a stuffing box the free end of which is formed with a row of steam discharge apertures and which is surrounded by a steam discharge pipe.

The steam discharge apertures at the free end of hot air. For this purpose, it is merely necessary to connect a hot air blower to the arrangement.

The stuffing box may, if necessar , beadditionally heated in known manner. The same applies to the injector nozzle.

The diamter of the inlet conduit is preferably from 1.3 to 2.3 times as large as the thickness of the material to be treated.

In this connection, the expression "thickness of the material to be treated" is to be understood to mean the sum of the diameters of all the individual filaments in the diameter direction of a cylindrical yarn strand.

In order to avoid knot-formation, the chamber diameter is, when processing yarn bundles having a total count of from 1000 to 000 den. , preferably from .5 to 7.5 mm.

The ratio of the cross-sectional area of the acceleration conduit to the total cross-sectional area of the steam discharge apertures is preferably from 1:3 to 1:60.

The invention will now be discussed in greater detail with reference to the accompanying drawings, wherein:- Figure 1 is a longitudinal section through one embodiment of a device according to the invention for the continuous stuffing-box crimping of endless thermoplastics filaments or yarns; Figure 2 is a 'longitudinal section through another the continuous stuffing-box crimping of endless, thermoplastics filaments or yarns; Figure 3 is a diagrammatic sketch illustrating the process according to the invention; and Figure is a diagrammatic sketch illustrating a variant of the process according to the invention.

Referring to Figure 1, a housing 9 has welded thereon a chamber wall 6 and has a nozzle insert 1 adapted to be screwed into the housing and containing a yarn inlet conduit 2. The arrangement is such that there are formed an upper annular chamber 2δ and a lower annular chamber 29 connected together by steam apertures 3. With this arrangement, the nozzle insert 1 is sealed relatively to the housing 9 by a packing ring 30. Laterally entering the upper annular chamber 28 is a steam feed pipe adapted to be connected, in this case via a cap nut 5, with a steam supply pipe (not shown).

The nozzle insert 1 forms, with the housing 9> a steam passage conduit 7. Formed in the interior of the housing 9 is a fitting bore (not shown in detail) into which a cylindrical insert 27 having an acceleration conduit S may be fitted in such manner as to be replaceable and securable by means of a screwthreaded pin 26. A second cylindrical insert 12 is pushed over the protruding free end of the insert 27 and encloses a chamber 11 v/hich is in direct communication with the acceleration conduit S.

The diameter of the chamber 11 will be referred to herein as D^, whilst the diameter of the acceleration In consequence of the fact that it is possible to replace the cylindrical insert 27, with the diameter D-j^ of the /a cJ3lQr.ak^fta-e«a .uiJ;—H remainin unchanged, it is possible to select the desired diameter D£ of the acceleration conduit 8, whereby the ratio Dj1^ may readily be varied. Since the ratio is of great importance for the yarn properties, it therefore becomes possible to influence the quality of the yarn by the selection of Dg.

The insert 12 is also replaceable.

The walls of the insert 12 contain a series of steam discharge apertures 25. The upper end of the insert 12 is centred by a lower centring means 14 which is itself centred in the housing 9 and is releasably secured by screws 13 to a housing 22 welded to the housing 9.

The housing 9 and the insert 12 form an inner annular chamber 21. The housing 9 and the housing 22 from an outer annular chamber 23 which is connected on the one hand with a lower steam discharge conduit 24 and on the other hand, via steam passage apertures 10 , with the inner annular chamber 21.

A stuffing box tube 17 is pushed on to, and a protective tube 18 is screwed into, the lower centring means 14· At the free end of the protective tube 18, with the aid of a bayonet closure arrangement having two retaining pins 15 , there is firmly fitted an upper centring means lo serving for centring the free end of the stuffing box tube 17 with a stuffing Figure 2 shows a further embodiment of the device according to the invention, this embodiment differing from the one shown in Figure 1 in that it contains a second arrangement for steam discharge.

Corresponding parts of the two embodiments are indicated by like reference numerals in Figures 1 and 2.

For the purpose of providing the second arrangement for steam discharge, the free ends of the stuffing box tube 17 and the protective tube IS have been slightly varied. A chamber insert 31, which itself is guided in the protective tube IS, provides in this case for the centring of the stuffing box tube 17 and forms, together with the protective tube IS, an upper annular chamber 34 conneeted on the one hand with an upper steam discharge conduit 32, and on the other hand, via steam discharge apertures 33, with the stuffing box 1 . A closure means 20, connected by a bayonet closure arrangement and with the aid of the two retaining pins 15 with the protective tube IS, prevents axial displacement of the chamber insert 31· In the following text, the process according to the invention is to be discussed in greater detail with reference to Figures 1 to » As can be seen from Figure 3, the material to be treated which is available in the form of a filament bundle 39, is doffed endwise from a bobbin 3S and passes, travelling over a yarn guide ifO and a first delivery stuffing box crimping device 35, i.e. into the yarn inlet conduit2.

The steam flow, entering the stuffing. bcx crimping device 35 at B, in the direction of the arrow, flows via the upper annular chamber 2β and the lower annular chamber 29 into the steam passage conduit 7, there surrounds the filament bundle arriving through the yarn inlet conduit 2 and conveys it through the acceleration conduit 8 into the chamber 11. There, the steam suddenly expands, causing the filament bundle to open, accompanied by an increase in bulk. After the steam flow and the filament bundle have travelled together through the chamber 11 for a few millimetres, they come into the proximity of the series of steam discharge apertures 25 in the wall of the insert 12. Their number varies in the case of the various replaceable inserts 12 and determines to a very considerable extent the proportion of steam drawn off.

Through these steam discharge apertures 25, the greater part of the steam flow is drawn off into the inner annular chamber 21 and from there, through the steam padsage apertures 10 and the outer annular chamber 23, to the lower steam discharge conduit 2 · For this purpose, the lower steam discharge conduit 2 may be connected with a source of negative pressure. The steam leaves the stuffing box crimping device in the direction of the arrow C.

The opened filament bundle travels, due to the high degree of kinetic energy imparted to it by the steam flow, into the stuffing box 19 and is deposited there. in a three-dimensional spiral line. Under the influence of wallfric ion, the treatment material is accumulated in the stuffing box 19 , so that it is subjected to stuffing box crimping and it is set in this shape. The yarn column which builds up is pressed, by the material subsequently introduced, in the direction of the arrow D, out of the stuffing box 19.

If it is desired to produce a yarn having an extremely small moisture component, then the embodiment of Figure 2 is used. The residue of the steam flow which accompanies the material being treated on its travel through the stuffing box 19 is, shortly before the free end of the stuffing box tube 17 , drawn off through the steam discharge apertures 33 , the upper annular chamber 34 and the upper steam discharge conduit 32 connected with a source of negative pressure, being thereby removed in the direction of the arrow E from the material which has been treated.

In order to obtain a yarn having an extremely small moisture component, this can also be achieved by connection of a source of hot air to the steam discharge conduit 32 (not shown). In that case, hot air is blown into the stuffing box 19 in the direction opposite to that of the arrow E. Additionally, it is possible to provide in known manner (not shown) an additional means for heating the stuffing box 19.

The stuffing box crimped material (indicated by the reference numeral 42 ) can be deposited in cans 41 (Figure 4) or be fed via a second delivery mechanism It will be apparent that the embodiment of the device according to the invention shown in the drawings may be varied in many ways, without thereby losing the properties which are essential to the invention.

Specific Examples of the invention will' now be described.

Example.1 For the manufacture of a carpet yarn from polyamide filaments having a total count of 3420 den. ( 3800 dtex), a texturing device was used which corresponded to the one shown in Figure 4 > except that the delivery mecha'nism 36 was not used.

The dimensions of the device were as follows: Diameter of the acceleration conduit β 1. 5 mm.

Internal diameter of the insert 12 .« 6.0 mm.

Diameter of the stuffing box 19 6.0 mm.

Number of steam discharge apertures 25 in the insert 12 16 Diameter of the steam discharge apertures 25 ... 1. 3 mm.

With a steam pressure of 2 atmospheres excess pressure and a steam temperature of 130°C, the injector nozzle doffed the filament bundle under a filament tension of 12 g. at 360 m/min.

The material accumulated in the can 1 had a spiral crimp exhibiting a crimp contration of 20 , b high bulk and excellent durability. It was possible to manufacture carpets from the yarn in accordance with the conventional methods, for example twisting and tufting.

Example 2 For the manufacture of a high-bulk yarn from a approximately 3000 den, ( 3300 dtex) and an individual count of 18 den. ( 20 dtex) a texturing device such as is sketched in Figure 3 was used.

The dimensions of the device were as follows: Diameter of the acceleration conduit $ Internal diamter of the insert 12. . .

Diameter of the stuffing box 19 Number of steam discharge apertures 25 in the insert 12 Diameter of the steam discharge apertures 25 The travel velocity of the first delivery mechanism 36 was 100 m/min., that of the second delivery mechanism 36 90 m/min. , and that of the reeling device 37 was 80 m/min. The injector nozzle was operated with steam (1.7 atmospheres excess pressure, 125°C).

The high-bulk yarn manufactured was distinguished by very great bulk, excellent crimp durability and a crimping contraction of 20 .

Claims (1)

1. « A process for the continuous compression crimping and heat setting of a synthetic thermoplastic multifilament yarn which comprises: continuously propelling the initially uncriraped and compact yarn by a jet of steam through a tubular acceleration passageway having a substantially constant diameter of 2 to 4.8 times the diameter of said compact yam; passing the yarn and steam flowing therewith directly from said passageway into an expansion chamber having a diameter of from 8 to 22 times the diameter of said compact yarn while drawing off a major proportion of said steam through lateral openings in said expansion chamber arranged at an interval spaced fromthe inlet side of said chamber of 0.5 to 2 times the diameter of said chamber, thereby suddenly expanding the flow of steam and opening up the compact yarn with the individual filaments being spread apart! depositing the spread-apart filaments in an elongated compression chamber arranged as a longitudinal extension of said expansion chamber, said filaments being crimped and forced through said compression chamber by the jet actio n of said steam; passing the remaining minor proportion of said steam through said compression chamber at a temperature sufficiently high to heat said filaments; and withdrawing the crimped filaments at the outlet end of said compression chamber. 2· A process as claimed in claim 1 wherein the steam jet introduced into, said acceleration passageway is saturated steam. 3· A process as claimed in claim 2 wherein the saturated steam is maintained at a temperature of about 120°C to 145°C. expansion chamber* 5* A process as claimed in claim 1 wherein the minor proportion of steam flowing through said compression chamber is drawn off laterally at a short distance from the outlet end of said compression chamber* 6» A process as claimed in claim 1 wherein hot air at a temperature of about 100°C# to 150°C. is injected laterally at a short distance from the outlet end of said compression chamber* 7· Apparatus for the continuous compression crimping and heat setting of a synthetic thermoplastic multifilament yarn which comprises; an annular steam jet nozzle surrounding a tubular yarn entry passage with means to supply steam to said nozzle; an interchangeable elongated acceleration tube of substantially constant diameter arranged to receive steam and yarn from said nozzle and entry passage for propulsion longitudinally thereofj a separately interchangeable tubular expansion chamber concentrically mounted at the discharge end of said acceleration tube, said expansion chamber having a larger diameter than said acceleration tube and being provided with lateral openings for the discharge of steam therefrom, said openings being arranged at an interval spaced from the inlet side of said expansion chamber of 0.5 to 2 times the diameter of said chamber. a steam discharge line in fluid connection with said expansion chamber through said lateral openings; a tubular extension of said expansion chamber connected thereto and adapted to receive said yarn fr compression crimping; and means to collect the crimped yarn from the discharge end of said tubular extension. 8« Apparatus as claimed in claim 7 wherein the diameter of said expansion chamber is approximately 2 to 10 times the diameter of said acceleration tube. 9. Apparatus as claimed in claim 7 wherein the diameter of said entry passage is about 1.3 to 2.3 times thediameter of the yarn entering therethrough. 10. Apparatus as claimed in claim 7 wherein the diameter of said expansion chamber is about 4.5 to 7*5 mm. 11* Apparatus as claimed in claim rherein the' ratio of the cross-sectional area of the acceleration tube to the total cross-sectional area of the lateral openings in saidexpanslon chamber is from about ll3 to 1:60. 12» Apparatus as claimed in claim 7 wherein at least one of said steam jet noasle and saidtubular extension of the expansion chamber is provided with means for heating the same. 13· Apparatus as claimed in claim 7 wherein a fluid conduit is arranged at the discharge end of said tubular extension in fluid connection with the crimping chamber formed by said extension through a second set of lateral openings» 14· Apparatus as claimed in c3¾m 13 wherein the diameterbfsaid expansion chamber is approximately 2 to 10 times the diameter of said acceleration tube. 15© Apparatus as claimed in claim 14 wherein the diameter of said expansion chamber is about 4·5 to 7«5 aua* 16« Apparatus as claimed in claim 13 wherein said fluid conduit is connected to means for blowing hot air into said tubular extension. 17. Apparatus as claimed in claim 13 wherein said fluid conduit is a second steam discharge line. 18. A process as claimed in claim 1 wherein the yarn being treated