GB2263333A - Heating yarns - Google Patents

Description

2263333 j YARN HEATING ASSEMBLY This invention relates to yarn heating

assemblies, and in particular to assemblies for heating a yarn during the false twisting stage of a yarn false twist texturing process. Such a heating assembly is described in British patent application No. 2250-40, the heating assembly in that case comprising an elongate heated surface and yarn guide means disposed relative to each other in operation to provide a yarn path which extends adjacent the heated surface. The various embodiments of heater described in that application comprise a plurality of yarn guides disposed along a door of the heater to guide the yarn along the desired yarn path adjacent the heated surface when the door is in its closed, operational position. The plurality of yarn guides facilitate the provision of a curved yarn path adjacent a curved heated surface and/or the adjustment of the disposition of at least a part of the yarn path relative to the heated surface. The plurality of yarn guides also provide good support for the running yarn within the heater to prevent instability at the required yarn throughput speeds.

However, with the efficient and rapid heating of textile yarns by means of high temperature non-contact heaters of the type described in the above-mentioned application, shorter lengths of heater are required than was the case with lower temperature contact heaters used previously. it has been found that unsupported lengths of yarn can be heated successfully by relatively short high temperature non-contact heaters whilst avoiding instability of the running yarn at the required yarn throughput speeds.

it is known to heat a running yarn by passing it through a heated tube without the yarn contacting the inner surface of the tube. However, the threading of such a yarn heater presents difficulties which increase considerably the threading time and which can only be overcome with the use of threading aids, thereby adding to the running costs and the initial cost of a textile machine incorporating a tube heater. in addition, for efficient heating over the relatively short length of a high temperature heater, the bore of the tube should be of only slightly larger diameter than the risk of the varn touching and being melted by the inner that of the yarn, which increases 2 surface of the tube during running and particularly during threading.

it is an object of the present invention to provide a yarn heating arrangement which retains the advantages associated with a high temperature non-contact heater, but avoids the disadvantages associated with the use of a heated tube having a relatively small bore.

The invention provides a yarn heating assembly comprising an elongate heated body and having a groove extending therealong to provide a yarn path through the body, the groove comprising a bore which in crosssection substantially surrounds the yarn path and a slot communicating with the bore and the outer surface of the heating assembly, guides disposed adjacent the ends of the groove to guide a yarn along the yarn path adjacent the surface of the bore, a heating device adapted to heat the body, and at least one baffle disposed in operation at the groove to restrict the flow of air along the yarn path. The slot may have a width which, at least in the region thereof which communicates with the bore, is a predetermined width sufficient only to allow the threading of a yarn therethrough.

The heating assembly may comprise a closing device disposed in operation substantially to close the slot, in which case the baffle may be integral with, or secured to, the closing device, and a plurality of baffles may be provided which project from the closing device and are mutually spaced longitudinally thereof. Alternatively, the baffle may comprise an elongate member secured to the closing device to extend longitudinally thereof, and may be spaced therefrom to provide an air gap therebetween. The baffle may be of a material having good heat reflecting properties, and the closing device may be of a material having good thermal insulating properties. The baffle may comprise a metal tube, and may be of stainless steel. The closing device may comprise a door which is pivotally mounted relative to the body so as to be movable between an open, threading position and a closed, operating position. The guides may be attached to the closing device so as to be movable therewith.

Alternatively, the slot may have a width, at the region which communicates with the outer surface of the heating J 3 assembly, which is the predetermined width.

Embodiments of the invention will be further described below with reference to the accompanying drawings in which Fig. i. is a side elevation of a first embodiment of yarn heating assembly, Fig. 2. is a section on line 2-2 of Fig. i.

Fig. 3. is an enlarged section corresponding to Fig. 2. of part of a second embodiment, Fig. 4. is an enlarged section corresponding to Fig. 2. of part of a third embodiment, Fig. 5. is a perspective view of the embodiment of Fig. 4., and Figs. 6 and 7. are enlarged sections corresponding to Fig. 4. of further embodiments.

Referring now to Figs. I and 2, there is shown a part of a textile machine 28 in which a heating assembly 40 is mounted. The machine 28 illustrated is a false twist texturing machine for texturing a yarn 11 and, in addition to the heating assembly 40, comprises a cooling plate 25 mounted on the frame 29 of the machine 28, and a first feed device 24 mounted on a creel 22.

The heating assembly 40 comprises an elongate heated body W, which is formed in two halves secured to each other by screws 12, rivets or clips, and has extending therealong a groove 23 in the form of a bore 13 and a slot 20. The bore!3 defines a path for the yarn ii to travel through the heating assembly 40, which yarn path is adjacent the surface of the bore 13 and is substantially surrounded thereby. The body 10 has the bore 13, a "neck" part 26 of the siot 20 which communicates with the bore 13, and a second bore 14 extending therealong. An electric heating element 27 extends along the second bore 14 to heat the body 10 to the required temperature, for example in the range 300 to 800 C. in operation, the yarn ii is guided by guides i5, 16 at the inlet and outlet end respectively of the heater 40 to travel along the bore i3 to be heated by the body 10. The body iO is enclosed substantially by a thermal insulating material 18 which is also in two halves within a casing i9, and is formed to have a slot 20 in which the body io is located. The sides of the slot 20 are lined with linings 2i of a rigid insulating material, e.g. fibre board, which serve to retain the body 10 in its location at the bottom of the slot 20, 4 A cover 22 closes the casing 19 and secures the heater 40 to the frame of the machine 28. A closing device or door 43 substantially closes the neck part 26, substantially fills the slot 20 and closes the outer end of the slot 20 during operation of the machine 28, and is pivotally mounted at pivot 44 provided on a door mounting bracket 57. The door 43 may be moved between a closed, operating position shown in Fig. 2. and in full lines in Fig. 1, and an open, threading position shown in broken lines in Fig. 1. When the door 43 and the first feed device 24 are in the open, threading position, the yarn ii travels from the creel 22 through the open nip of the first feed device 24, over a guide pin 46 on the door mounting arm 45 and then to the false twist device (not shown) without entering the heating body bore 13 or contacting the cooling plate 25.

The door 43 comprises a closing plate 47 of a good thermal insulating material which is attached to the mounting arm 45, and which is of a thickness such that it will just enter the slot 20 in the cover 42, casing 19 and insulating material 18 substantially to close it. Projecting from the inner edge of the closing plate 47 are several posts 48 by means of which a baffle 17 is supported on the closing plate 47. The baffle 17 comprises a tube of heat reflecting material, such as stainless steel, which is of a diameter such that it almost closes the neck part 26 of the slot 20 and hence the bore 13 in the heated body 10. Clips 41 retain the baffle tube 17 on the posts 48 and spaced from the closing plate 47 so as to provide an air gap therebetween which reduces the transfer of heat from the baffle tube 17 to the closing plate 47. By this means, loss of heat from the bore 13 is minimised. The baffle tube 17 also serves to reduce considerably the flow of air longitudinally of the heater 40 in the region of the bore i3, whether caused by convection or by entrainment by the yarn ii, and such airflow reduction has been found to increase the efficiency of heating 4- L,he yarn ii by an appreciable amount. The tube i7 may be closed at its ends to prevent airflow through it and consequential internal contamination. in an alternative embodiment, the posts 48 are of a size and shape such that at each post position the neck 26 opening of the slot 20 into the bore 13 is almost closed so as to form baffles 17 whereby airflow longitudinally of the bare 13 is restricted.

in a further embodiment, shown in Fig. 3, the width of the neck part 26 is reduced, compared with that of Fig. 2, to a predetermined width sufficient only to allow threading of the yarn ii therethrough, for example between 1.5 and 2.Omm.

Referring again to Figs. i and 2, also mounted on the closing plate 47, on opposed faces thereof, are two side members 49 which are joined to each other by slider pins 50 passing through slots 51 in the closing plate 47. A longitudinally extending lip 52 on one of the side members 49 is engaged by two cranked arms 53, each of which is pivotally mounted on the closing plate 47 at pivots 54, and is biassed by a spring 55 to push the side members 49 to a position in which they lie on opposed sides of the baffle tube 17 to shield it and protect it from damage when the door 43 is in the open, threading position. Yarn guides 15, i6 are mounted also on the door 43.

When the door 43 is moved from the open, threading position, and the first feed device 24 is closed, the yarn engages the yarn guides 15, 16 and is moved to its operating position within the bore 13 and in contact with the cooling plate 25. As the door 43 closes and the yarn ii, the baffle tube i7 and the closing plate 47 enter the slot 20, the side members 49 come into contact with the cover 42 and are caused to slide relative to the closing plate 47 as slider pins 50 move along the slide slots 51 and arms 53 rotate against the force of the springs 55. A spring 56 extending between the door mounting bracket 57, mounted on the machine frame 29, and the door mounting arm 45, biases the door 43 towards the closed operating position. To retain the door 43 in either the open or closed position, a spigot 58 is provided on the door mounting arm 45, and is engageable in recesses in the rim of a locator plate 59 provided on the door mounting bracket 57 concentrically with the P,vot 44.

Referring now to Figs. 4 and 5, there is shown a heating assembly 30 comprising a heated body 10 of similar construction to that shown in Fig 3. The body iO is substantially surrounded Dy heat insuiating material 18 housed in a casing 19 and cover 42 similar to that described in relation to the previous 6 embodiments. As in the previous embodiments also, a slot 20, having sides lined with linings 21 of fibreboard, communicates with bore 13 and the outside of the heating assembly 30. However, in this embodiment, the door 43 is replaced by a different formation of slot 20. A capping 31, conveniently a puttrusion,_secures the fibreboard slot linings 21 relative to the cover 42 and provides an opening 32 which, as with neck 26, is reduced also compared with the width of the slot 20 of this and the previous embodiments, to the predetermined width sufficient only to allow threading of the yarn 11 therethrough. The pultrusion cappings 31 reduce the transfer of heat by conduction from the fibreboard linings 21 to the cover 42, and the relatively small slot width at the neck 26 and opening 32 reduces heat loss by radiation or convection from the bore i3. The flow of air along the bore 13 or slot 20 is restricted in this embodiment by means of baffle plates 33 provided at each end of the heating assembly 30. The baffle plates 33 have a slot 34 of width similar to that of opening 32 and neck 26 aligned centrally with the slot 20, and an opening 35 aligned with the bore 13 and slightly enlarged compared with the slot 34 oniy to minimise the risk of contact between the yarn il and the baffle plate 33 due to ballooning or vibration during running.

Referring now to Figs. 6 and 7, there are shown two further embodiments which are similar to that described above and shown in Figs. 4 and 5, except that in these cases the block of brass forming the heated body 10 has been replaced by sheets of stainless steel formed to provide the bore 13 and to enclose one (see Fig. 6) or two (see Fig. 7) heating elements 27. Such assemblies are less costly than the previously described embodiment and reduce the mass of the heat sink whilst providing a high degree of heat reflection towards the yarn 11.

Alternative embodiments of yarn heating assembly in accordance with the invention wili be readfly apparent to persons skilled in the art. For example, the baffle 47 may be of a cross -section other than circular, and may be solid instead o-&;' tubular. in the event zhat it is desired that the yarn path be curved, individual baffles 48 may be provided and formed as yarn guides aisposed in operation to be substantially equidistant from the longitudinally curved bottom of the groove 7 23. Particularly in such a case the cooling plate 25 may be curved upwardly and the yarn ji run on the upper surface thereof as a means of reducing the angle of wrap of the yarn ji around the guide 16 at the exit end of the heater 40 and entry of the cooling plate 25.

8

Claims (1)

1. A yarn heating assembly comprising an elongate heated body and having a groove extending therealong to provide a yarn path through the body, the groove comprising a bore which in cross-section substantially surrounds the yarn path, and a slot communicating with the bore and the outer surface of the heating assembly, guides disposed adjacent the ends of the groove to guide a yarn along the yarn path adjacent the surface of the bore, a heating device adapted to heat the body, and at least one baffle disposed in operation at the groove to restrict the flow of air along the yarn path.

2. A heating assembly according to claim 1, wherein the slot has a width which, at least in the region thereof which communicates with the bore, is a predetermined width sufficient only to allow the threading of a yarn therethrough.

3. A heating assembly slot has a width which, at communicates with the bore, according to claim 2, wherein the least in the region thereof which is between 1.5 and 2.Omm.

4. A heating assembly according to any one of claims i to 2,1 ,, comprising a closing device disposed in operation substantially to close the slot.

5. A heating assembly according to claim 4, wherein the closing device comprises a door which is pivotally mounted relative to the body so as to be movable between an open, threading position and a closed, operating position.

6. A heating assembiy according to claim 5, wherein the closing device comprises a plate of a thickness such that it will just enter the slot substantially to close it.

7. A heating assembly according to claim 6, wherein two side members are mounted on the plate on opposed faces thereof and are slidable relative thereto.

8. A heating assembly according to claim 6 or claim 7, wherein the plate is of a material having good thermal insulating properties.

9. A heating assembly according to any one of claims 4 to 8, whercin the guides are attached to the closing device so as to be movable therew2#tfi.

J0.

I. A heating assembly according to a.ny one of claims 4 to 9, wherein the balfle -is integral with, or is secured to, the the closing device.

11. A heating assembly according to any one of claims 4 to iO, comprising a plurality of baffles which project from the closing device and are mutually spaced longitudinally thereof.

12. A heating assembly according to claim il, wherein the baffle comprises an elongate member secured to the closing device to extend longitudinally thereof.

13. A heating assembly according to claim 12, wherein the baffle is s paced from the closing device to provide an air gap therebetween.

14. A heating assembly according to claim 13, wherein the baffle is a metal tube.

15. A heating assembly according to claim i4, wherein the tube is closed at its ends.

16 A heating assembly according to claim 14 or claim i5, wherein the baffle is of a material having good heat reflecting properties.

17. A heating assembly according to claim 16, wherein the baffle is of stainless steel.

i8. A heating assembly according to claim 2 or claim 3, wherein the slot has a width, at the region which communicates with the outer surface of the heating assembly, which is substantially the predetermined width.

19. A heating assembly according to claim 18, comprising cappings which provide an opening for the slot in the region which communicates with the outer surface of the heating assembly.

20. A heating assembly according to claim ig, wherein each capping is a pultrusion.

2i. A heating assembly according to any one of claims i8 to 20, wherein a baffle plate is provided at each end of the heating assembly.

22. A heating assembly according to claim 2i, wherein each ba-,;'-,--ie piave has a siot therein of WIC th suDsyantiaiiy equai to -h, and an opening aligined wit L.he predetermined widt 41h the bore.

23. A heat-'ng assembly according to any one of claims 1 to ri 1 22, wharsin the devilce comprises a heating ejement whici., extends along a second bore provided in the body to extend therealong.

1 j 0 24. A heating assembly according to any one of claims j to 23, wherein the body is enclosed substantially by a thermal insulating material.

25. A heating assembly according to claim 24, wherein the thermal insulating material is in two halves within a casing.

26. A heating assembly according to any one of claims i to 2,5, wherein the sides of the slot are lined with linings of a rigid insulating material.

27. -A heating assembly according to claim 26, wherein the iinings are of fibreboard.

28 A heating assembly according to any one of claims 1 to 27, wherein the body is in two halves secured to each other.

29. A heating assembly according to any one of claims i to 27, wherein the body is formed of a sheet of metal.

30. A heating assembly according to claim 29, wherein the sheet of metal is stainless steel.