EP1358120B1 - Cross-wind bobbin - Google Patents

Abstract

The invention relates to a cross-wind bobbin (1) wherein the helical lines in which the yarn (4) is wound have a different pitch in adjacent positions. The winding ratios are selected in such a way that the amount which is drawn off is greater when the draw-off point is displaced from the draw-off side to the base than the amount which is drawn off when the draw-off point is moved from the base to the draw-off side.

Description

Cross-wound bobbins are supply bobbins from which a yarn is withdrawn which is fed to a yarn-consuming machine, for example a loom or a knitting machine. The cross-wound cheese of the cross-wound bobbin is self-supporting and does not require any end disks at the ends. The hold within the cross-wrap is achieved by winding the yarn at relatively high pitch helically, rather than close to tightness, as with a disk coil having end walls. The pitch of the helices is large, so that the thread crosses several times in the individual yarn layers and thus stabilizes the underlying layer. It forms, as it were, an enveloping surface for the underlying layer.

The pitch angle or crossing angle with which the threads cross in the individual layers prevents that the threads between the individual turns of the underlying layer einzunge, as would be the case with a parallel winding. At the ends of the cross-winding, the thread forms at a turning point the transition from one to another position, or a helix to another. The reversal points at the two ends constantly change their position within the cross-wound to stabilize the front ends.

The free accessibility of at least one front end of the cross-wound bobbin is needed to pull off the yarn overhead. When overhead take off the cross-wound bobbin remains alone. The yarn is withdrawn from the top of the stationary cross-wound bobbin through a loop of thread. The thread eyelet is located at a distance from the withdrawal side of the cross-wound bobbin and lies on the axis of symmetry of the cross-wound bobbin.

US-A-2,764,368 shows a cross-wound bobbin in which the yarn has a different pitch in the superposed winding layers. The bobbin is wound such that when over-the-head, which in the present case corresponds to peeling over the smaller diameter end, comparatively more yarn is obtained as the release point moves from the down side of the foot compared to the direction of movement of the release point from the foot side to the head side.

As a result, on the one hand, too high an edge structure in the region of the ends of the coil should be avoided and, on the other hand, a slippage of the thread during the reverse movement of the traverse stroke.

In order to obtain the known cross-wound bobbin, a cam curve is used, which rotates with unaltered transmission ratio relative to the coil during winding. As a result, over the entire diameter range of the cross-wound bobbin, the ratio of the respectively obtained yarn lengths, depending on the direction of movement of the separation point, remains constant.

Modern textile machines, in particular weaving machines, have reached a speed that is limited by the feeding speed of the yarn.

Fig. 1 illustrates schematically the deduction ratios of a known cross-wound bobbin 1. The cross-wound bobbin 1 consists of a cross-wound bobbin 2, which is wound on a tubular bobbin tube 3. The cross-winding 2 forms a thread or yarn 4. The yarn 4 is wound in layers by means of a known traversing device in turns. Two of these layers are shown schematically in partial detail. In one layer, the yarn 4 is denoted by 5 and in the other layer by 6. For example, be the layer 5, the radially inner layer or winding, while the layer 6 or winding is located radially further out. The one layer, for example the layer 5, form the turns of the yarn 4 a left-hand screw, while the turns of the yarn in the layer 6 produce a right-hand screw. The pitch angles, with which the yarn 4 is wound, are measured in terms of magnitude relatively large compared to a plane 7, which is perpendicular to the longitudinal axis of the bobbin tube 3. That is the pitch height The screws forming the layers 5 and 6 are many times larger than the thickness of the yarn 4. In this way it is prevented that the turns of the one layer can constrain between the turns of the other layer and the turns of this layer press apart.

The cross-wound bobbin 1 thus obtained forms a withdrawal side 8, which is a substantially flat annular surface. In the area of the withdrawal side 8 there are reversal points 9 at which the yarn path changes from one to the other position and thus from one helix to the opposite helix. The reversal points 9 are distributed as randomly as possible in the region of the withdrawal side, namely randomly distributed both in the circumferential direction and with a certain scattering width in the axial direction. By these measures, on the one hand an effective stabilization of the withdrawal side to be achieved and on the other hand, an accumulation of material to be avoided.

At the other axial end of the cross-wound bobbin 1 there is the foot side, which is constructed in the same way as the deduction 8 visible in FIG.

The yarn 4 is withdrawn from the outer circumferential surface of the cross-wound bobbin 1 by an eyelet 11 which is axially spaced from the cross-wound bobbin 1 and lies on the axis of symmetry. The eyelet 11 is fixed in space. The cross-wound bobbin 1 also does not move during yarn withdrawal.

Due to the adhesion of the yarn on the effective surface of the coil, a defined separation point is formed 12, viewed from the direction of the yarn 4 when deduction, the course of the yarn no longer corresponds to the course of the yarn within the cross-wound bobbin 1. The Ablösungspünkt 12 runs in accordance with the helix, which forms the yarn 4 on the respective outer side of the cross-winding 2 in the circumferential direction, and at the same time moves the separation point 12 in the longitudinal direction of the cross-wound bobbin first

The speed at which the separation point 12 rotates in the circumferential direction, ie the angular velocity, is dependent on the yarn withdrawal speed and the diameter of the cheese 2. The larger the diameter of the cheese 2 and the lower the take-off speed, the smaller the angular velocity, with the detachment point 12 rotates. Conversely, the angular velocity increases when, at a constant take-off speed, the winding diameter has decreased as a result of increasing yarn consumption.

Because the separation point 12 rotates about the peripheral side of the cheese 2, the yarn section rotates between the eyelet 11 and the separation point 12 about the imaginary axis formed by the eyelet 11 and the axis of symmetry of the cheese 2. Due to the rotation creates a centrifugal force, which tends to urge the withdrawn yarn piece radially outward.

With still full cross-winding, the rotational speed of the separation point 12 of the yarn 4 from the top of the cross-wound 2.beibei given thread use speed is still relatively low. The occurring centrifugal force is not sufficient to the yarn 4 already immediately following the separation point 12 from the top of the Remove crosswrap 2. Beyond the separation point 12, the yarn 3 will first slide over the top of the cross-winding 2, before it passes into the free space after exceeding the withdrawal side 8.

The free-flying yarn defines a space of revolution in the space, the point of which lies at the thread eye 11. The generatrix of this surface of revolution is the respective exposed part of the yarn 4, which describes a complicated space curve. Both the centrifugal force and the air resistance act on this free-flowing piece of yarn so that the yarn course does not form a simple line lying in one plane. The bounded by the free-flying piece of yarn space is referred to as a thread balloon.

As the consumption increases, the outer diameter of the cross-wound bobbin 2 decreases. Since the thread withdrawal speed remains constant, the detachment point 12 must rotate faster to compensate for the reduction in length of thread along the circumference resulting from the reduction in diameter.

From a certain angular velocity, the centrifugal force will be large enough to lift the yarn 4 from the top of the cheese 2 immediately following the separation point 12.

The sticking of the yarn 4 to the underlying yarn layers, yarn unevenness due to structural changes, yarn tension variations and the like, cause the draw ratios to continuously vary between sliding on the yarn in a range of angular velocity of the peeling point 12 Alternate the surface of the cheese 2 and a flying over the surface. The inventors have found that this oscillation between the two trigger situations is also influenced by whether the detachment point 12 moves away from the withdrawal side 8 or towards the withdrawal side 8.

As the separation point 12 moves away from the take-off side 8, the speed of rotation and hence the centrifugal force increase, thus resulting in a tendency for the yarn 4 to detach from the top of the cheese neck 2 immediately following the separation point 12 and clear over the surface to fly. On the other hand, when the peeling point 12 moves toward the take-off side 8, the revolution speed and the centrifugal force decrease, so that the yarn 4 tends to drag over the top.

Air resistance effects at the top of the cheese 2 will also have a corresponding influence here.

Only when the angular velocity of the detachment point has increased even further, no folding into the triggering situation with over the surface of sliding yarn will occur more.

The progressive thread consumption causes the diameter of the cross-wound package 2 to shrink progressively and the angular velocity of the detachment point 12 to continue to increase. The higher speed of the thread in the air causes the initially forming simple balloon to a so-called double balloon with two clearly recognizable voluminous balloon sections which are interconnected via a constriction. The associated course of the flying Garnstücks is shown in Fig. 2.

The transition from the situation according to FIG. 1 to the situation according to FIG. 2 likewise takes place in a region in which the conformation according to FIG. 1 and the conformation according to FIG. 2 alternate one from the other. Only at a certain angular velocity, only the conformation of Fig. 2 will be formed.

When the winding diameter is very small, a triple thread balloon is finally formed, on which two necking points can be seen. The thread course associated with this triple balloon is shown in FIG. Also, the transition from the conformation of Fig. 2 to the conformation of Fig. 3 extends over an angular velocity range in which the balloon alternates constantly between two and three times back and forth. The individual types of balloon definitely include different forces and thread tensions occurring in the thread.

The strength of a yarn obeys a bell-shaped distribution distributed around an average tensile strength value. Due to the scattering of the strength values, there are sections in the yarn which have a significantly higher breaking strength and vice versa but also sections which tear even at significantly smaller forces.

In turn, the thread-consuming device by no means generates only a single constant force, but also here the force is distributed according to a bell curve be. Yarn breaks are to be expected in the region in which the Gaussian curve of the actually occurring force coincides with the strength distribution of the yarn, ie the region in which the two Gaussian curves form an intersection. The larger this area is, the greater the likelihood that the yarn will break on the side of yarn consumption, resulting in corresponding machine downtime.

A very critical route that must pass through the yarn from the cross-wound bobbin to the finished textile structure is the withdrawal from the cross-wound bobbin 1 itself.

Fig. 4 shows the course of the thread tension plotted against the winding diameter of the cross-wound bobbin 1. The unit of measure of the winding diameter are millimeters and the unit of measure of tensile force cN (grams). A strongly jagged upper curve 13 shows the progression of the maximum force occurring, in each case per 100 measured values. Below this is a dark-colored, tubular or band-shaped region 14, which illustrates the statistical standard deviation of the measured tensile force values. Approximately in the middle of this band is the statistical average of the tensile force occurring. In the longitudinal direction, the diagram is divided into zones numbered 1 to 6.

The withdrawal of the yarn 4 from the cross-wound bobbin 1 starts at the maximum diameter of the cross-wound bobbin of about 280 mm. At this diameter, the angular velocity of the separation point 12 is too small for the centrifugal force to detach the yarn directly to the release point 12 from the top of the cross-wound bobbin 1. The yarn 4 grinds over the surface in this operating situation and produces relatively very high strain maxima, although the mean is relatively low, and also the standard deviation is not too large as band 14 indicates. The high tensile maxima are mainly due to the fact that the yarn 4 sliding on the surface gets entangled with the yarn layer over which it slides because the yarn surface is not smooth. It consists of individual fibers.

The operating situation with sliding yarn remains in its pure form up to a winding diameter of approx. 260 mm.

From about 260 mm, ie at the transition between the designated 1 and the 2 zone in the diagram, the withdrawal situation will occur sporadically, in which the yarn 4 dissolves immediately after the separation point 12 from the top. In the areas in which the balloon is already formed from the detachment point 12, the maximum withdrawal force suddenly decreases, which immediately increases again when the balloon is formed only after the withdrawal side 7. In section 2, therefore, very large fluctuations in the maximum pull-off force and also relatively large fluctuations in the range of the standard deviation can be observed.

As the reduction in diameter continues, ie to the right of section 2, the balloon remains stable following the separation point 12. There is no more sliding deduction. The occurring maximum tensile force goes down abruptly. The standard deviation becomes smaller and also the mean value decreases. Obviously, to the right of the area 2, the yarn 4 becomes mechanical during the withdrawal significantly less burdened. It significantly reduces the likelihood of yarn breakage.

Up to a diameter of about 160 mm, i. Within zone 3 the conditions remain stable and the thread tension increases only slowly. The increase in yarn tension is due to the higher speed of rotation and the associated higher air resistance load, as well as the larger yarn mass found in the balloon.

To the right of zone 3 is a clear increase in the maximum tension and also in the mean value. The balloon assumes even larger dimensions, which lead to higher tensile stresses due to greater centrifugal force. In addition, a randomized change occurs between the single balloon and the double balloon. Finally, towards the end of zone 4, the situation finally reverses in favor of the double balloon, which suddenly reduces the centrifugal forces and thus also the tensile stresses that occur. Both the standard deviation and the occurring maximum stresses, ie the outliers of the voltage in the direction of very large values, decrease abruptly. Finally, at the end of zone 5, with a diameter of less than 60 mm, a change to a triple balloon can be observed. At the end of zone 5, the maximum force increases again relatively strong to collapse abruptly when the triple balloon has formed stationary.

Based on this, it is an object of the invention to provide a cross-wound bobbin, which is suitable, the occurring maximum tensile stresses in the yarn amount to reduce and / or confined to a reduced operating range to reduce the likelihood of yarn breakage.

This object is achieved by the cross-wound bobbin with the features of claim 1.

In the cross-wound bobbin according to the invention, the individual layers are wound with different pitches of the helices. They are wound so that the withdrawn thread length is greater as the separation point moves from the head side to the foot side compared to the thread length which is withdrawn as the separation point moves from the foot side to the head side. In other words, the screw along which the separation point moves from the head side to the foot side has a much smaller pitch than the helix along which the separation point moves from the foot side toward the head side. By virtue of this measure, the unfavorable influence on the yarn balloon, which is due to the fact that the separation point moves away from the yarn balloon at a comparatively high speed, can be reduced. Due to the small pitch of the helix as the separation point moves away from the balloon, the axial velocity of the separation point away from the balloon is significantly reduced and the adverse effect on balloon formation is reduced.

For smaller diameters, the cross-wound bobbin according to the invention will clearly show the transition to the double balloon, which, as illustrated above, is more favorable with regard to the maximum stress occurring. Again, the diameter range, over which a back and forth occurs between the single and the double balloon. be significantly reduced. Smaller areas correspondingly reduce the likelihood of yarn breakage.

If a sliding trigger occurs, the constant sway between the sliding thread take-off and the free-running thread take-off in the cross-wound bobbin according to the invention is reduced to a much smaller diameter range.

Compared with the prior art, a stationary flying balloon will be formed even at much larger outer diameters of the cheese, starting at the separation point.

In both cases, the invention allows a higher take-off speed.

By appropriate free choice of the pitches of the helices within the cross-wound can be controlled within certain limits, when the folding into the other type of withdrawal or conformation of the balloon occurs, i. when irreversibly takes place the change from the sliding detachment to the free-floating detachment after the separation point, or the double balloon or the triple balloon.

Moreover, further developments of the invention are the subject of dependent claims.

In Fig. 5, the cross-wound bobbin 1 according to the invention is shown very schematically.

The cross-wound bobbin 1 according to the invention shows the same basic structure as cross-wound bobbin 1 according to the prior art. It has a bobbin tube 3, on which the cross-wound bobbin 2 is applied. The course of the yarn 4 on the top of the cross-winding 2 is illustrated schematically. When deducting the indicated flow point 12 moves in the upper visible yarn layer in the direction of an arrow 15 from the foot 16 to the trigger or head 8. The situation forms a right-hand screw. As soon as the upper visible layer has been removed, the detachment point 12 changes to the position underneath, where the detachment point 12 '(provided with an apostrophe because it is in the next position) is moved in the direction of the arrow 17. This layer contains the yarn 4 in a left-hand screw.

As FIG. 5 clearly shows, the detachment point 12 'performs 2.5 turns as it moves from the head or withdrawal side 8 to the foot side 16 and only approximately one movement during the movement from the foot 16 to the withdrawal side 8 In the case shown, the turns ratio would be 1 to 2.5. Deviating from the turns ratio shown, other turns ratios up to 1:10, preferably 1: 5, are conceivable and, depending on the thread ratios, provide improved values of the peel force compared to a cross-wound bobbin in which the turn ratio in the successive layers is 1: 1. Winding ratio is here understood to be the number of turns in which the yarn is wound on the way from the foot side to the head side, compared with the number of turns which describes the yarn in the opposite way.

In other words, the amount of angle α that yarn 4 is capable of with the right-hand screw with the plane 7 is greater than the amount of angle .beta. Which the yarn 4 is able to engage with the level-7 left-hand screw.

Apart from the difference explained, the cross-wound bobbin 1 according to FIG. 5 is manufactured according to the same criteria as usual. It is desirable to avoid accumulation of material due to the reversal point 9 on both the withdrawal side 8 and the base 16. It is also desirable to align the thread path, based on the next layer with the same sense of winding, as random as possible in order to avoid Moirébildungen or regularities, which leads to disturbances.

Apart from the conical shape, as shown in Fig. 5, the cross-wound bobbin 1 can also be designed by suitable winding so that its cone angle varies depending on the diameter or, for example, towards the end, i. at small diameters turns into a cylindrical shape. It would also be conceivable to produce a cross-wound bobbin 1, in which the cross-wound bobbin 2 is initially cylindrical following the withdrawal side 8 and then merges into a frusto-conical region. It is thus approximated hyperboloid.

The cross-winding can also be cylindrical over the entire length and all diameters, as is customary today.

Based on previous findings from a series of experiments, the improvement can be tabulated in tabular form for the diameter-100 mm as follows. gear ratio 1: 1 prior art 1: 2 1: 2.5 1: 3 maximum strength 25 cN 18 cN 11 cN 17 cn standard deviation ± 5 cN ± 4 cN ± 3 cN ± 4 cN Average 6 cN 5 cN 3 cN 5 cN

For a winding diameter of about 65 mm results in the following comparison. gear ratio 1: 1 prior art 1: 2 1: 2.5 1: 3 maximum strength 35 cN 18 cN 15 cN 12 cN standard deviation ± 6 cN ± 4 cN ± 3 cN ± 2 cN Average 7 cN 4 cN 4 cN 2 cN

The pitch angles α and β may be constant except for the edge areas on the take-off side 8 and the foot 6 side. You can also talk about the axial length On the other hand, they can also be dependent on the radial distance. Finally, it is conceivable to produce a conical angle which increases towards the full coil by providing windings in the interior of the cross-wound, with respect to the radial extent, which do not have the full axial length, ie windings are produced which, for example, proceed from the foot 16 only to about half the length of the cross-winding 2 rich.

Which shape and which angle ratio is chosen in each case must be determined experimentally in detail, because in the runnability of the yarn are very much the type of yarn and the yarn material and the yarn diameter. Ring spun yarns have different properties than yarns made of rotor spinning machines. Optimization by means of trial series will therefore be unavoidable.

In a cross-wound spool, the helices in which the yarn is wound have different pitch in adjacent layers. The winding ratios are selected such that the amount withdrawn is greater when the release point moves from the withdrawal side to the base side as compared to the withdrawn amount as the separation point moves from the foot side to the withdrawal side.

Claims (18)

1. Cross-wound bobbin (1)
   with a bobbin core and
   with a cheese (2), which consists of yam (4) applied onto the bobbin core (3) in layers, and which has a doffing side (8), from which the yam (4) can be drawn off overhead, and has a base side (16),
   wherein the yam (4) runs in the cheese (2) along a spiral line from the doffing side (8) to the base side (16) and also in another spiral line in opposite winding direction from the base side (16) to the doffing side (8), and the pitches of the spiral lines differ from one another in such a manner that, at least in a region of the cheese (2), the yarn length is greater when drawn off in this region when the separation point (12') of the yarn (4) on the outside of the cheese (2) has moved along a spiral line from the doffing side to the base side (16), calculated on the basis of the yam length removed in this region when the separation point (12) has moved along a spiral line from the base side (16) to the doffing side (8), and
   characterised in that the two spiral lines form a pitch ratio and the pitch ratio is dependent on the radial distance.
2. Cross-wound bobbin according to Claim 1, characterised in that the region is a region, which extends from a first diameter to a second diameter.
3. Cross-wound bobbin according to Claim 1, characterised in that the region is a region, which extends from a first location to a second location axially spaced from the first location.
4. Cross-wound bobbin according to Claim 1, characterised in that there is at least a further region comprising another winding ratio according to Claim 1.
5. Cross-wound bobbin according to Claim 1, characterised in that the bobbin core (3) is formed by a bobbin case.
6. Cross-wound bobbin according to Claim 1, characterised in that the cheese (2) is free from coverings on the doffing side (8).
7. Cross-wound bobbin according to Claim 1, characterised in that one yam layer merges into another yam layer respectively at a return point (9), wherein consecutive return points (9) do not lie directly one above the other either on the base side (16) or on the doffing side (8).
8. Cross-wound bobbin according to Claim 7, characterised in that the return points (9) are offset relative to one another in the peripheral direction and/or in the longitudinal direction in relation to the axis of the cheese (2).
9. Cross-wound bobbin according to Claim 1, characterised in that the cheese (2) is configured such that consecutive layers do not form a moiré pattern.
10. Cross-wound bobbin according to Claim 1, characterised in that the cheese (2) at least of the full cross-wound bobbin (1) is cylindrical.
11. Cross-wound bobbin according to Claim 10, characterised in that the cheese (2) is cylindrical over the entire operating area.
12. Cross-wound bobbin according to Claim 1, characterised in that the cheese (2) at least of the full cross-wound bobbin (1) tapers conically towards the doffing side (8).
13. Cross-wound bobbin according to Claim 1, characterised in that the cheese (2) is configured such that the full cross-wound bobbin (1) forms a conical cheese (2), the structure of which changes into the cylindrical structure as the removal of yarn increases.
14. Cross-wound bobbin according to Claim 1, characterised in that the yarn belongs to a group comprising spun yarns, monofilament yarns, multifilament yarns and twisted yarns thereof.
15. Cross-wound bobbin according to Claim 1, characterised in that the yam is a yarn for textile or textile technology application.
16. Cross-wound bobbin according to Claim 1, characterised in that the angle (α, β), at which the yam (4) is wound in one yam layer, amounts to between 30° and 12°, respectively measured in relation to a plane (7) lying at right angles to the axis of the cheese (2), and that the angle (α, β), at which the yam (4) is wound in the other yam layer, amounts to between 0.5° and 15°, measured in relation to the same plane (7).
17. Cross-wound bobbin according to Claim 1, characterised in that the winding ratio between the winding from the base side (16) to the doffing side (8) and the winding from the doffing side (8) to the base side (16) lies between 1:1.2 and 1:10, preferably between 1:1.5 and 1:8.
18. Cross-wound bobbin according to Claim 1, characterised in that the cross winding has a truncated-cone-shaped structure on the doffing side (8) and/or the base side (16).

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