GB2193979A

GB2193979A - Stretching and thermofixing a polyester filament

Info

Publication number: GB2193979A
Application number: GB08717559A
Authority: GB
Inventors: Hermann Mettler
Original assignee: METTLER SOEHNE MASCHF
Current assignee: METTLER SOEHNE MASCHF
Priority date: 1986-08-18
Filing date: 1987-07-24
Publication date: 1988-02-24
Also published as: GB8717559D0; CH671243A5; IT8721603A0; DE3724607A1; IT1222458B

Description

GB2193979A 1

SPECIFICATION merit.

According to the invention, there is provided Apparatus for stretching and thermofixing a an apparatus for stretching and thermofixing a polyester filament polyester filament, including a heating element 70 which is disposed in the path of the filament The invention relates to an apparatus for and which is preceded by a first godet roll stretching and thermofixing a polyester fila- and followed by a second godet roll, the per ment. ipheral speed of the second godet roll, at the Such an apparatus, known from DE-OS 35 first point of contact of the filament therewith 30 936, is suitable, in particular, for the pro- 75 being greater than the delivery speed of the duction of a sewing thread, ready for use, first godet roll by the stretching ratio wherein, from a freshly dyed and centrifuged dyeing in operation, the heating element is heated to bobbin and preferably comprises an-integrated a temperature above the second glass-point brightening device in order to carry out all the temperature of the filament and the second operations in a single run through of the fila- 80 godet roll, round which the filament is ment. As a result of the stretching and ther- wrapped a plurality of times, is heated to a mofixing, not only is the polyester filament temperature which is below or equal to the strengthened in its structure, in that its molesecond glass-point temperature and is con cules are aligned, but also its yield is in- stant over its length, the diameter of the sec creased, which has an advantageous effect 85 ond godet roll decreasing from said first point because sewing threads are sold by length. of contact of the filament therewith to the last The stretching and thermofixing is still not point of contact of the filament therewith, sufficient, however, to prevent shrinkage of thereby forming a shrinkage region.

the filament when the textiles sewn therewith The improvement according to the invention are boiled. Therefore, an apparatus known 90 prescribes first guiding the polyester filament from GB-PS 1 465 748 (the content of which over a heating element, the temperature of is largely the same as DE-OS 24 16 927) which is above the second glass- point temper comprises two successive shrinkage zones fol- ature of the filament, in order to stretch the lowing on two successive stretching zones. filament and then to guide it, with simulta The first stretching zone is formed between a 95 neous shrinkage, over a godet roll, the tem pair of rollers forming a nip and a first heated perature of which is at most equal to the sec godet roll. The second stretching zone is ond-glass point temperature of the polyester formed between the first heated godet roll filament.

and a second heated godet roll. The second transition point, at which the The second godet roll has two different dia- 100 mobility of the molecules increases consider- meters in order to form a first shrinkage zone. ably, as a result of which the desired longitu The second shrinkage zone is formed between dinal orientation of the molecules is facilitated the second heated godet roll and a following, during the stretching, is designated the second last, unheated godet roll. Instead of only two glass-point temperature. Whereas the first heated godet rolls, the known apparatus may 105 glass-point temperature for polyester is ap also comprise more than two heated godet proximately 75'C, the second glass-point tem rolls, in which case the temperature of each perature is approximately 180'C.

heated godet roll should be higher than that of Now the invention is based on recognition the preceding godet roll. In addition, a device of the fact that the shrinkage should take for winding the processed filament is neces- 110 place at a temperature which, at the most, sary after the last unheated godet roll. reaches the second glass-point temperature.

As a result of the cost of a relatively large As a result, assurance is provided that the number of driven rollers, godet rolls and a stretched and shrunk polyester filament has winding device, the known apparatus is rela- practically no more boiling shrinkage, with the tively expensive and. nevertheless is not suit- 115 minimum loss of length.

able for the production of a sewing thread Specific embodiments of the present inven- ready for use since further operations on se- tion will now be described in detail by way of parate devices connected with rewinding are example, and not by way of limitation, with necessary, for example between a dyeing bob- reference to the accompanying drawing in bin and the sewing thread ready for use. 120 which:

In addition, it has been found that with the FIG. 1 shows a diagrammatic arrangement known apparatus, a considerable proportion of of the individual elements of an apparatus for the length of the stretched filament is lost as processing a polyester filament to form a a result of the two-stage shrinkage. sewing thread ready for use.

It is therefore an object of the invention to 125 FIG. 2 shows a stepped godet roll for provide an improved apparatus for stretching shrinking the polyester filament; and and thermofixing a polyester filament such that FIG. 3 shows a godet roll decreasing contin- the shrinkage of the filament otherwise occur- uously in diameter for shrinking the polyester ing during boiling is less than 1% while retain- filament.

ing the maximum possible length of the fila- 130 With reference now to the accompanying 2 GB2193979A 2 drawing, a machine frame 10 serves as a rection by the stretching process.

common support for the elements to be de- Before Figure 1 is explained further, Figure 2 scribed hereinafter. A supply bobbin 12, pre- will be explained which illustrates the second ferably a freshly dyed and centrifuged dyeing godet roll 32 in a side view. In order to allow bobbin, is on a mounting device 14 so that its 70 the polyester filament 16 to shrink, the sec filament 16 can be withdrawn overhead. The ond godet roll 32 has a diameter decreasing filament 16 then travels successively through from the first point of contact 74 of the fila a thread brake 18 and a thread cutter 20. ment 16 to the last point of contact 76, as A first godet roll 22 as a feed delivery already mentioned. For this purpose, the go- mechanism with which a guide roller 24 is 75 det roll illustrated in Figure 2 is provided with associated, serves to withdraw the filament. a plurality of steps 72. The region between The filament 16 is usually wrapped round the the first point of contact 74 and the last point godet roll 22 and the guide roller 24 a plural- of contact 76 serves as a shrinkage zone 78.

ity of times. After the guide roller 24, a heat- In order to render the shrinking possible and ing element 26, round which the filament is 80 to achieve a permanent stability of the poly wrapped a plurality of times, is disposed in ester filament 16, the second godet roll 32 is the path of the filament. The heating element heated, its surface temperature being below 26 comprises a first heating surface 26' and a the second glass-point temperature of the second heating surface 2W. Both heating sur- polyester filament or at most reaching this faces are curved outwards and are bridged at 85 value, in contrast to the heating element 26.

each of their two ends by a freely rotatable Whereas the heating element 26 (Figure 1) roller 28 and 30 respectively. preferably has a surface temperature of 200- The filament 16 may preferably wrap round 230'C, the second godet roll 32 preferably the stationary heating element 26 ten to has a constant surface temperature over its twenty times. In the course of this, the fila- 90 length of between 130 and 180'C. Such a ment 16 is pulled over the heating surfaces temperature in the shrinkage zone 78 encour 26' and 2W. ages the shrinkage of the polyester filament After leaving the heating element 26, the 16 and ensures a permanent fixing thereof in filament 16 wraps round a second godet roll order to avoid shrinkage during the boiling of 32 as a delivery mechanism and an associated 95 the textiles to be sewn therewith.

guide roller 34. The filament 16 also wraps The decrease in the diameter of the second round this second godet roll 32 and the guide godet roll 32 from step to step is preferably roller 34 a plurality of times. The second go- 1 to 2%. Thus the diameter of the largest det roll 32 has a decreasing diameter from the step at the first point of contact 74 may be first point of contact of the filament to its last 100 100 mm for example, while the diameter of point of contact. At the first point of contact the smallest step at the last point of contact of the filament, the peripheral speed of the 76 is 97 mm. The width of a step is prefera second godet roll 32 is greater, by the de- bly 25 mm, each step being wrapped round sired stretching ratio, than the delivery speed by two turns of the polyester filament. Hard of the first godet roll 22. Consequently there 105 chrome plated aluminium or steel is particularly is a stretching zone 36 between the first go- suitable as a material for the production of the det roll 22 and the second godet roll 32 in second godet roll 32. A stationary heating the region of the heating element 26. element 68 (Figure 1), particularly an induction It is also possible to use a ro tating heating coil, which is disposed inside the godet roll element in the form of a further godet roll, 110 and which renders possible a contactless round which the filament is wrapped a plural- heating of the rotating godet roll, is particu ity of times, instead of the stationary heating larly suitable for heating the godet roll 32. The element 26. The stationary heating element induction coil can be fed through an associ 26 renders possible a more precise tempera- ated regulator which is controlled by a tem ture control, however, than is the case with a 115 perature sensor PT 100.

rotating roller. The time the filament 16 re- Instead of the stepped godet roll 32 as mains on the heating element can be fixed by shown in Figure 2, a form of embodiment as the number of loops it makes round the heat- shown in Figure 3 is also possible, wherein ing element. As a result, an adaptation to the the godet roll 32' comprises a region 80 with state and the nature of the filament is pos- 120 a diameter decreasing continuously. Only in sible. With a freshly dyed supply spool 12, the region of the first point of contact and in the heating element 26 additionally serves to the region of the last point of contact does dry the filament. Thetemperature of the heat- the godet roll 32' comprise cylindrical regions ing element 26 is abpve the second glass- 82 and 84 respectively. The cylindrical regions point temperature (second transition point), al125 82 and 84 preferably have diameters of 100 ready mentioned, of the polyester filam.ent of and 97 mm respectively.

about 180'C. The stretching ratio in the region of the At such a temperature, the molecules of the stretching zone 36 as shown in Figure 1 is polyester filament are sufficiently mobile to be preferably of the order of magnitude of 6%. It permanently orientated in the longitudinal di- 130 can be varied by the rigid speed correlation 3 GB2193979A 3 between the two godet rolls 22 and 32 for the second godet roll 32 and hence also of adaptation to different requirements. the first godet roll 22 in order to ensure a The shrinkage following on the stretching uniform thread tension between the second operation is defined by the variation in dia- godet roll 32 and the winding device 54.

meter of the second godet roll 32 and is 3% 70 As a result of the temperature of the sec- with the values given as preferred. ond godet roll 32, which is lower in compari- After the second godet roll 32, the son with the heating element 26, the shrin stretched and shrunk filament 16' is guided kage zone 78 is restricted to the time which over a knocking-off motion 38 and a compen- the filament 16 spends on the second godet sating arm 40 before it enters a brightening 75 roll 32, so that no uncontrolled after-shrinkage device 42. The brightening device 42 corn- can occur in the following course of the fila prises a bath container in which a distributing ment.

roller 46, driven in rotation, dips partially into

Claims

a brightening bath. The filament 16' is tangent CLAIMS to the distributing

roller 46 over a component 80 1. An apparatus for stretching and therregion of its upwardly directed circumference, mofixing a polyester filament, including a heat being guided over two stationary spindles 50. ing element which is disposed in the path of After leaving the brightening device 42, the the filament and which is preceded by a first brightened filament 1W arrives, via a guide godet roll and followed by a second godet 52, at a winding device 54 to be wound in 85 roll ' the peripheral speed of the second godet the form of a precision package to form a roll at the first point of contact of the filament delivery bobbin 56. The heating element 26 is therewith being greater than the delivery in a chamber 58 which is connected through a speed of the first godet roll by the stretching pipeline or hose 60 to a suction device 62 ratio, wherein, in operation, the heating ele comprising a blower 64. The suction device 90 ment is heated to a temperature above the 62 serves not only to draw off the vapours second glass-point temperature of the filament forming in the region of the heating element and the second godet roll, round which the but also to stimulate precipitation. The va- filament is wrapped a plurality of times, is pours to be drawn off are, on the one hand heated to a temperature which is below or the humidity residues of dyes and on the 95 equal to the second glass- point temperature other hand the vapours formed during the and is constant over its length, the diameter heating up of the polyester material. The of the second godet roll decreasing from said chamber 58 is bounded by a housing 66 first point of contact of the filament therewith which is easy to open and is partially open at to the last point of contact of the filament the bottom. The housing 66 fulfils its purpose 100 therewith, thereby forming a shrinkage region.

not only in enclosing the chamber 58 neces-
2. An apparatus as claimed in claim 1, sary for the suction but also it prevents, wherein the diameter of the second godet roll within wide limits, heat radiation from the decreases in a plurality of steps.

heating element 26, to save energy.
3. An apparatus as claimed in claim 2, As a result of the spatial arrangement of the 105 wherein the decrease in the diameter of the individual elements in relation to one another, second godet roll is 1 to 2% from step to as illustrated in the drawing, a relatively low step.

structural height can be achieved so that a
4. An apparatus as claimed in claim 1, machine equipped therewith is easy to watch wherein the diameter of the second godet roll and easy to operate. The drawing in of the 110 decreases continuously.

filament or twisted yarn can be carried out
5. An apparatus as claimed in claim 4, directly by hand without any aids such as wherein the diameter of the second godet roll hooks, rods, starting etc. has a cylindrical region both before and after Of the device illustrated and described, a the region decreasing continuously.

plurality of such units are disposed side by 115
6. An apparatus as claimed in any one of side and combined to form a machine which the preceding claims, wherein altogether the may comprise a common suction device for all decrease in the diameter of the second godet units. roll is of the order of magnitude of 4%.

The device described is not combined with
7. An apparatus as claimed in any one of a twisting frame because then the processing 120 the preceding claims, wherein the stretching speed is generally limited to about 50 m/min ratio is of the order of magnitude of 6%.

whereas the device described permits a speed
8. An apparatus as claimed in any one of of passage of 300-600 m/min. the preceding claims, wherein the second go- Varying the degree of stretching of the fila- det roll is heated by means of a built-in induc- ment 16 in the stretching zone 36 is possible 125 tion coil.

by exchanging crown wheels, not illustrated,
9. An apparatus as claimed in claim 8, through which the godet rolls 22 and 32 are wherein the induction coil is heated via an driven through toothed belts. associated regulator which is controlled by a A compensating arm 40 provided with a temperature sensor.

compensating roller 41 regulates the speed of 130
10. An apparatus for stretching and ther- 4 GB2193979A 4 mofixirig a polyester filament substantially as hereinbefore described with reference to, and as shown in, the accompanying drawing.

Published 1988atThe Patent Office, State House, 66/71 High Holborn, London WC I R 4TP. Further copies may be obtained frorn The Patent Office; Sales Branch, StMary Cray, Orpington, Kent BR5 3RD.

Printed by Burgess & Son (Abingdon) Ltd. Con. 1/87.