IL34088A - Process and apparatus for the rolling of yarn of ribbon-like structures about their longitudinal axis - Google Patents

Description

-'• OT 0*03» OR d'sin n'?',?a17 o*opnm v^nn Dn ti* *)*ηκπ 3» 0 ono Process and apparatus for the rolling of yarn or ribbon-like stuctures about their longitudinal exis OLE-EEMDT RASMUSSEN G. 32413 This invention relates to a process for the rolling of yarn or ribbon-like structures about their longitudinal axis, the rolling taking place in a substantially linear zone between two rubbing bodies, the rubbing surfaces of which are moved relative to one another transversely of the structures, while these are being fed forward in their longitudinal direction.

Rolling processes of this nature are used for various purposes within the textile industry and related industries. It is e.g. known to perform such a rolling in combination with the spinning of staple yarn, the rolling being performed on the raw yarn in order to increase the coherence between the individual fibres and to make the cross section of the yarn more circular. The rolling is also employed in the texturation of yarn, where it is known to utilize such a rolling for producing a strong twist which is combined with a heat treatment or other fixation process suitable for giving the material an inclination to revert to the twisted state. Finally, it is known to use such a rolling process in the production of split fibres , orientated foil strips being split, usually under a relatively heavy pressure, into fibres, which still cohere in the form of a yarn. The orientation required for this purpose may e.g. be produced by a strong molecular orientation (although this as is well known does not always produce sufficient splittability), or it may be produced by a strong stretching of a mixed structure in molten state.

A rolling of the nature here considered is produced by means of two rubber rollers, which are mutually reciprocated along their axes, while at the same time rotating to feed the yarn forward longitudinally, or by similar means. However, the effect of these known rolling means will be relatively non- niform which is of articular disadvanta e in the roduction will result, and where the process is particularly critical owing to the required relatively high roller pressures. These drawbacks may to some extent be remedied either by feeding the yarn very slowly in relation to the time of reciprocation or by using a very large number of such rolling stations after one another. This, however, will tend to make the process relatively unpractical.

It is an object of the invention to remedy these drawbacks. A further object is to obtain a particularly high speed of operation.

According to the invention, there is used at least one rubbing body comprising a plurality of rubbing elements which are successively engaged with the other rubbing body and, while being so engaged, are moved transversely of the feeding direction of the structures, said rubbing elements being restored to their initial position during the periods of non-engagement with the other rubbing body.

Thus, in the process according to the invention the rolling is performed as a substantially continuous process with substantially constant rolling in the same direction, whereby the rolling effect will be uniform and the treatment can be carried out in a practical way and at a high feeding speed.

The minimum number of rubbing elements is two, but it is preferred to use a greater number, e.g. 8-15, because it then becomes possible to use higher speeds without substantial complication of the construction of the required apparatus .

The other rubbing body located on the opposite side of the structures may e.g. be a rotating roller having a rubbing surface or, in a very simple embodiment, a stationary body having a rubbing surface. However, to obtain the highest possible speed ferably likewise comprises a plurality of rubbing elements, which are successively engaged with the first rubbing body, the rubbing elements at any time engaged with each other being moved in opposite directions.

In a preferred manner of carrying out the process, one or both rubbing bodies consist of a roller having a plurality of separately axially displaceable roller sections, each extending over part of the circumference of the roller.

The rubbing surfaces may be sand blast or finely fluted metal surfaces or rubber coatings which are attached directly to the rubbing elements. However, in one manner of carrying out the process, the transverse movement of the rubbing elements is transferred to the structures by means of endless bands. Hereby the lifetime of the rubbing surfaces is increased. To avoid transverse slipping between the bands and the rubbing elements, one side of the bands, which is in direct contact with the elements, may be longitudinally fluted and the surfaces of the rubbing elements may be similarly fluted for engagement with the fluting pattern of the band.

For splitting and texturating purposes, the rubbing surfaces may advantageously be moved at mutually different speeds in the feeding direction. In this manner, a displacement treatment is obtained simultaneously with the rolling, which displacement treatment all the time affects the surfaces of the structures in opposite directions, an influence constantly taking place on different parts of the surfaces of the structures.

The invention also relates to an apparatus for carrying out the process. This apparatus comprises means for establishing a substantially linear zone between two rubbing bodies,aand means for moving the rubbing surfaces relative to one another ward, and according to the invention at least one of said rubbing bodies comprises a plurality of rubbing elements, the apparatus comprising means for successively engaging said rubbing elements with the other rubbing body, and means for displacing said rubbing elements transversely of the feeding direction of the structures during the periods of their engagement with the opposed rubbing body and for restoring said rubbing elements to their initial position during the periods of their non-engagement with the opposed rubbing body.

Advantageously at least one of said rubbing bodies consists of a roller comprising a plurality of separately axially displace-able roller sections, each extending over part of the circumference of the roller.

According to another preferred embodiment of the invention, said other rubbing body also comprises a plurality of rubbing elements, the apparatus comprising means for successively engaging said rubbing elements with said first rubbing body, and means for moving the rubbing elements at an time engaged with each other in opposite directions.

In the case where the rubbing body or bodies is or are in the form of a sectional roller, the rubbing elements may be connected with a core portion in such a manner as to be displaceable relative to this core portion in the longitudinal direction of the roller. The roller is also provided with means for reciprocating the sections synchroneously with the rotation of the roller. These means may advantageously consist of one or more stationary guiding tracks or guiding curves and one or more corresponding cams or contact members on each of the said sections.

The apparatus for carrying out the process according to the bing elements may be mounted on a set of chains, which are so arranged that the rubbing elements are moved transversely of the feeding direction of the structures, which in this case may be the direction of the chains.

Another aspect of the invention has to do with the molecular orientation of thermoplastic polymers in the form of one or more ribbon- like structures, the structures being heated and being stretched within a predetermined zone up to several times their original length.

A stretching for the molecular orientation of thermoplastic polymers is usually carried out by means of two sets of rollers, one of which being located at one end of the stretching zone and the other being located at the other end of the zone, the first mentioned set of rollers being rotated at a lower circumferential rate of speed than the last mentioned set of rollers .

It is customary to localize the position of the stretching zone accurately by means of a friction body (smooth metal surfaces will normally provide sufficient friction for this purpose), and moreover the input rollers may be replaced by friction bodies, the speed of the material across these bodies being then controlled by adjustment of the frictional effect.

To facilitate the stretching, the material is, as mentioned above, frequently heated either by means of a hot-air oven in the stretching zone or by heating the input rollers or the intermediate friction body.

It is an object of the invention to reduce the risk of rupture during the stretching.

According to the invention, this is obtained by subject-in the structure or structures in a continuous succession of in heated condition, the twisting being thereafter entirely or partly eliminated. The twisting is preferably carried out by rolling the structures about their longitudinal axes in the manner previously described, but other twisting methods, known per se, may alternatively be used.

It has been found that by the combined twisting and stretching a considerable reduction of the frequency of ruptures at a certain stretching ratio is obtained particularly where the material has distinct defective spots, e.g. resulting from occluded air blisters, an inhomogenous distribution of relatively high molecular and relatively low molecular components, a non-uniform thickness or notches at the edge of the ribbon-like structure or structures. By the twisting the structure or structures assume a more compact character, the individual portions of a cross section through the structure or structures being held together by frictional forces, whereby an initial rupture will have less possibility of developing. It is essential that a heating should be performed before the material is subjected to twisting, since it takes considerably longer time to heat the material in a twisted state.

For practical reasons it is preferable to produce the twist by rolling the structures between a pair of rubbing bodies located at the output end of the stretching zone. Usually a plurality of ribbon-like structures will be stretched simultaneously, and eventually these will be coiled in the form of individual structures or bundles of structures. It is not necessary to provide a separate twisting member for each structure or each bundle of structures, but a plurality of structures may according to the invention preferably be twisted by means of the same pair of rubbing bodies in different areas of their rubbing surfaces. the combined twisting and stretching process. This apparatus comprises means for subjecting one or more ribbon-like structures to a heating and means for subjecting the structures to a stretching to several times their original length and, according to the invention, further comprises means for subjecting the structures in a continuous sequence of operations to a twisting before or while they are being stretched in heated state, and for thereafter entirely or partly eliminating the twist.

When treating relatively wide foil strips, e.g. of a width of 3-30 cm, the danger of rupture may be further reduced by arranging the longitudinal axes of the input or heating rollers, and the auxiliary or stretching rollers respectively at an angle to each other. Hereby the twisting will take place sooner after the ribbon-like structures have left the last one of the sets of input rollers, whereby a possible notch or notch formation will be blocked before a rupture ensues. Likewise the resulting twisting of the structures will be more uniform. It has also been found that at a given stretching ratio the angle between the axes of the rollers should preferably have a value such that its cosinus is approximately equal to or smaller than the square route of the stretching ratio, defined as the ratios, between the speeds of travel at the input and output ends, respectively, of the stretching zone by selecting the angle such as to fulfil the condition, the danger of rupture at a given stretching ratio may be very considerably reduced.

The invention will now be described in further detail with reference to the accompanying drawings, in which Fig. 1 shows diagrammatically , in a perspective view, a set of rollers for use in carrying out the process accordin to the invention the uidin means bein Fig. 2 the guiding means of a roller of the kind illustrated in Figure 1, as viewed from the side with parts in section, Fig. 3 a cross section along the line I-I in Figure 2, Fig. 4 diagrammatically, in a perspective view, an apparatus according to the invention for use in false twisting and, if desired, simultaneously splitting, Fig. 5 an apparatus according to the invention for use in the splitting of ribbon-like structures in four stages, Fig. 6 illustrates diagrammatically a process for the stretching of ribbon-like structures, the twisting being performed by means of two endless rubbe ' ands , Fig. 7 illustrates a process for stretching, in which the twiating is produced by means of a single sectional roller co-operating with an ordinary roller, and Fig. 8 illustrates diagrammatically another process for the stretching of ribbon-like structures.

In Figures 1, 2 and 3, 1 is a roller core, which is rotated by drive means not shown, and 2, 3, 4 and 5 are sections of an outer roller portion. The core 1 and the sections 2, 3, 4 and 5 are so constructed that the sections are forced to take part of the rotation of the core, but are free to reciprocate in the longitudinal direction of the roller. The illustration is strongly simplified and in practice the movements should preferably be transferred through bearings, which can e.g. be rows of rollers. The sections are held together by means of rings, one of which, 6, is shown in Figures 2 and 3. As another possibility the sections and the core could be assembled by means of dovetail con- guiding groove 8 in the ring 6. This construction too is shown in a simplified form and in practice the connections should be established by means of bearings. E.g. each pin 7 may be in the form of a ball or roller bearing. Each section is provided with a rubber coating 9.

In Figure 1, the directions of rotation of the two rollers and the longitudinal directions of movement of the sections 2 and 4 of each roller are indicated by arrows. The sections 3 and 5 are stationary in the moment where they are in one and the other extreme position respectively. When the rollers have made one fourth of a revolution,, the section 2 of the upper roller has been displaced by smooth sliding movement to the position assumed in the drawing by the section 5. Thus, each section is caused to perform a reciprocating movement, which is synchronized with the rotation of the roller. If relatively few sections are used, such as illustrated in the drawing - and on principle it is possible to use as few as two sections - the guiding groove 8 should have a substantially constant pitch over a relatively long distance about the zone in which it guides the movement in the clamping zone. The guiding groove should have a configuration such that the roller sections move at a constant sliding speed at any rate from the time where the sliding edge of a section reaches the clamping zone to the time when the trailing edge of the same section leaves the clamping zone, i.e. during one fourth of a revolution when four sections are used as illustrated. If, on the other hand, 10 or more sections are used, it is usually permissible to let the speed change gradually.

In the apparatus illustrated in Figure 4, a group of yarns or film strips (for clarity film strips are shown) is fed through a set of ordinar rubber rollers 11 and then throu h a set of ences resulting from rubbing elements, each carrying out a predetermined cycle. Instead of a set of sectional rollers, it is possible to use e.g. one sectional roller co-operating with an ordinary roller. It is also possible to use a combination of an ordinary roller and an array of sections, which are advanced in a closed path by means of endless chains and at the same time carry out transverse movements analogous with those of the roller sections described above.

When the yarns or strips 10 are introduced in non-twisted state, the rolling will cause them to be twisted when leaving the rollers 11. The twisted yarns or strips are denoted by 13. This twisted state is fixed thermally, the material being heated in an oven 14 and subsequently cooled by means of a blower 15 before entering the set of rollers 12. After the rolling the material is passed on for coiling or spooling (not shown).

The twisting will thereby be eliminated and the material will therefore leave the set of rollers 12 in a false twisted state indicated at 16. If the material consists of strongly orien tated strips, a splitting may take place at the same time and will be effected to a lesser extent in the zone where the strips are twisted, i.e. when they leave the rollers 11, and to a greater extent in the zone where they are subjected to rolling by the rollers 12.

A splitting may, however, also be effected without maintaining any false twist in the final product, the heat treatment or other fibre fixation treatments illustrated being then omitted When the process is also to be used for splitting, it is advantageous to repeat the rolling several times by means of several stations of the same kind arranged in immediate succession. This is illustrated in Fi e In the l ttin met d lus rated rolling about their longitudinal axes without any dislocation along the longitudinal axes taking place at the same time. This has been found to be preferably for the starting of the splitting.. This treatment takes place by means of a set of rollers 18 constructed with displaceable sections such as explained above with reference to Figures 1, 2 and 3. A sequence of subsequent sets of rollers 1 s 20 and 21 is also constructed with displaceable sections, but during the passage through these a combined rolling about the longitudinal axes of the structures and a dis-location along these axes takes place.

To determine the conditions to be fulfilled, the structures are to be subjected to a pure rolling about their longitudinal axes, and when they are at the same time to be subjected to dislocation along the longitudinal axes, respectively, the resultant of the circumferential speed of rotation and the speed of displacement should be considered for each of the two rubbing surfaces engaging one another. If this resultant is numerically equal (but differently directed) for the two rubbing surfaces, the structures are subjected to a pure rolling about the longi-tudinal axes. If on the other hand the two resultants have different numerical values (and different directions), a dislocation along the longitudinal axes of the yarns takes place at the same time. It is observed that it is possible without substantial drawbacks to select the speed of rotation and displacement of the roller sections in such a manner that the feeding direction of the structures differs considerably from 90° to the axis of the rollers. Immediately before moving into the set of rollers 19, the structures travel through eyes of a reciprocating rod 22 and are thereby introduced into the clamping zone in a zig-zag pattern, which in this stage usually promoted the splitting. set of rollers 23 and 2 » which subject the structures to a stretching in order to remove kinks and the like that my be formed when the structures are subjected to dislocation along their longitudinal axes. The same function is performed by two additional sets of rollers 25 and 26, which are arranged after the set of rollers 20, and two further sets of rollers 27 and 28, which are arranged afte the set of rollers 21. Moreover, an ove 29 is provided immediately before the set of rollers 29 and serves to soften the material Immediately before it reaches the last splitting station, fhe heating in this oven and the cooling, which is effected by means of a blowe 30 and takes place after th splitting station and while the split fibre yarns are held in a relatively slack state, serves to fix the ruffled state, into which the fibres are brought in the splitting process when they are subjected to dislocation along the longitudinal axes o the yarns. Eventually the yarns are spooled.

In the process illustrated in Figure 6, a plurality of ribbon-like structures 31 to be orientated are moved in flat non-twisted state through a heated pair of rollers 32 (the heating means not being shown) and thereafter between a pair of crossing endless rubber bands 33 shown only in part in the figure, he driving rollers and other rollers for the rubber bands 33 and the guiding means thereof are no shown. he dash-dotted line 34 indicates the nip zone between two sectional rollers (not shown) which clamp the rubbe bands together on the bundle of strips in a substantially .linear zone. The two rubber bands are moved at an angle to each other and thereby cause the strips clamped therebetween to be rolled. At the same time the strips are pulled orward b the rubber component of speed of the rubber bands in the longitudinal direction of the machine. The pair cf rollers 32 rotate at a lower circumferential speed, the ratio between the said component of speed and the circumferential speed being substantially equal to the desired stretching ratio. The strips are thereby simultaneously stretched and twisted. Both stretching and twisting take place predominantly in the zone adjacent the rollers 32 immediately after the strips have left these rollers. A set of rollers 35 rotates at a circumferential speed corresponding to the said component of the movement of the rubber bands and thereby support the stretching effect of these. If these rollers were not provided, it would be necessary to clamp the rubber bands particularly hard against one another, which would be unpractical. The twisting produced by the rubber bands will be at any rate substantially eliminated when the strips leave the clamping zone between the rubber bands. In addition to the heating of the rollers 32 a hot-air oven may be arranged between these rollers and the clamping zone of the rubber bands. The stretching zone and the twisting zone may thereby be extended, whereby it becomes possible to use higher feeding speeds.

In Figures 7, 31» 32 and 35 have the same significance as in Figure 6. In Figure 7, however, the rubber bands have been replaced by a set of rollers 40,4l. The roller Ί*ϋ is shown in dotted lines and is located between the strips 31 and the observer and is an ordinary roller. The roller 4l on the other side of the strips is a sectional roller of the same kind as that shown in Figures 1, 2 and 3. The roller 40 is shown as consisting of a relatively great number of sections, which is usually advantageous. The dotted line 42 indicates the projection of the composed movement performed by any particular point sections along the roller are not shown. When the pitch of the curve described by each point of a section in the clamping zone is to be 2a, it is usually advantageous to arrange the rollers 40 and 4l at an angle a to the rollers 32 and 35 and besides the composite speed of the frictional surface of the sections in the clamping zones should be equal to the circumferential speed of the roller 40. Seeing that the feeding direction becomes the bisecting line of the angle between the movements of the two roller surfaces, the strips will on principle travel linearily through the stretching apparatus. To prevent them from drifting longitudinally of the rollers, it is, however, advantageous in practice to control the introduction of the strips into the clamping zones by means of a comb 43.

To give the rollers a sufficient frictional surface, they may be sand blast or rubber coated, but it is also possible to transfer the transverse movements from these rollers to the strips through endless rubber bands. The rubber bands and the roller surfaces may then engage with each other by means of a pattern of flutes or grooves preventing transverse slipping.

The process illustrated in Figure 8 serves for the stretching of wide strips in such a manner as to reduce the risk of rupture of the strips, which is obtained by arranging the longitudinal axis of the main preneating roller set and the drawing rollers at an angle to each other. Ribbon-like foil strips 51 pass through a set of preheating rollers 52 and a set of main preheating rollers 53, whereafter they are twisted in a set of rollers 4, one roller of which consists of two or more axially displaceable roller sections each extending over part of the periphery of the roller, while the other is a roller performing travel through a set of auxiliary or stretching rollers 55 s the circumferential speed of which is equal to the sum of the components in the direction of travel of the circumferential and axial speeds of the sections of the first mentioned rollers 54 in the nip zone and also equal to the component in the direction of travel of the circumferential speed of the other roller 4. As illustrated in the drawing, the twisting of the individual strips will start immediately after these have left the pair of rollers 53.

Claims (12)

WHAT I CLAIM IS:

1. A process for the rolling of yarn or ribbon-like structures about their longitudinal axis, in which the rolling takes place in a substantially linear zone between two rubbing bodies, the rubbing surfaces of which are moved relative to one another transversely of the structures, while these are being fed forward in their longitudinal direction, c h a r a c t e r i z e d by using at least one rubbing body comprising a plurality of rubbing elements, which are successively engaged with the other rubbing body and, while being so engaged, are moved transversely of the feeding direction of the structures, said rubbing elements being restored to their initial position during the periods of non-engagement with the other rubbing body.

2. A process as in claim 1, c h a r a c t e r i z e d iv by using, as a rubbing body, a roller having a plurality of separately axially displaceable roller sections, each extending over part of the circumference of the roller.

3. A process as in claim 1, c h a r a c t e r i z e d in that said other rubbing body also comprises a plurality of rubbing elements, which are successively engaged with said first rubbing body, the rubbing elements at any time engaged with each other being moved in opposite directions.

4. A process as in claim 39 in which the transverse movements of the rubbing bodies are transferred to the structures by means of endless bands.

5. A process as in claim 1, in which the rubbing surfaces are moved at mutually different speeds in the feeding direction.

6. An apparatus for carrying out the process according to claim 1, comprising means for establishing a substantially linear zone between two rubbing bodies, and means for moving the rubbing surfaces relative to one another transversely of the structures, while these are being fed forward, c h a r a c t e r i z e d in that at least one of said rubbing bodies comprises a plurality of rubbing elements, the apparatus comprising means for successively engaging said rubbing elements with the other rubbing body, and means for displacing said rubbing elements transversely of the feeding direction of the structures during the periods of their engagement with the opposed rubbing body and for restoring said rubbing elements to their initial position during the periods of their non-engagement with the opposed rubbing body.

7. An apparatus as in claim 6, in which at least one of said rubbing bodies consists of a roller comprising a plurality of separately axially displaceable roller sections, each extending over part of the circumference of the roller.

8. An apparatus as in claim 6, in which said other rubbing body also comprises a plurality of rubbing elements, the apparatus comprising means for successively engaging said rubbing elements with said first rubbing body, and means for moving the rubbing elements at any time engaged with each other in opposite directions.

9. A process preferably according to claim 1, in which the ribbon-like structure or structures consist of thermoplastic polymers, c h a r a c t e r i z e d by subjecting the structure or structures in a continuous succession of operations, to a twisting before or while they are being, stretched in heat * eliminated.

10. A process as in claim 9, c h a r a c t e r i z e d in that the heating of the ribbon-like structure or structures is performed before the twisting thereof.

11. A process as in claim 93 c h a r a c t e r i z e d in that the twist is produced by rolling the structure between a pair of rubbing bodies located at the output end of the stretching zone.

12. A process as in claim 9, c h a r a c t e r i z e d in that the ribbon-like structure or structures are drawn off from the pair of rollers at the input end of the twisting at an oblique angle.