EP0159395A1 - Method for drafting a roving in a spinning machine - Google Patents

Abstract

A process for processing a roving (26) in a drafting system and the drafting system required for this purpose. The object of drafting a roving at high speed in a drafting system which is adaptable to a wide range of staple led to the following features: a) The roving (26) undergoing drafting is at the same time systematically deflected in such a way that the roving (26) can pass without further deflection into the downstream funnel (53), and thence the downstream pair of calender rolls (54). b) All the bottom cylinders (11, 12, 13, 14) are rigidly mounted. c) The first pressure cylinder (28) which bounds the predrafting zone and the first pressure cylinder (30) which bounds the main drafting zone are slidable along an arc (19, 20) about the axis of rotation (15, 17) of the corresponding bottom cylinders (11, 13), so that the drafting zones are adaptable to the fibre length. To be able to position these pressure cylinders (28, 30) evenly along the arc (19, 20) in relation to parallelity with the corresponding bottom cylinder (11, 13) there are provided indexed positions (32, 33, 34) coaxially to the arc (19, 20) for receiving the mounting block pairs (21, 23) which receive the pressure cylinders (28, 30). d) All the pressure cylinders (28, 29, 30, 31) and also the pressure rolls (27) are conjointly pivotable out of a servicing position into an operating position, and back, using a pivotable double arm (4). <IMAGE>

Description

The invention relates to a method for spinning machines, in particular for draw frames, for processing a sliver with a stacking area of short to long staple fibers.

DE-PS 1250315 shows and describes a drafting system with, viewed in the running direction of the sliver, an input cylinder pair, a middle cylinder pair and an output cylinder pair, each consisting of a lower cylinder and an associated pressure cylinder.

The input and the middle pair of cylinders together form a leading, while the middle and the output pair of cylinders form a main drawing zone.

The input cylinder pair is in the direction of the fiber seen bandes, linearly movable back and forth to change the length of the pre-stretching zone.

Both cylinders can be moved independently of each other.

The middle and the output lower cylinder are rigid, while the middle and the output pressure cylinder are arranged linearly displaceable in the same way as the input pressure cylinder.

All three printing cylinders can be moved vertically with respect to a base plate receiving the bearing blocks of the lower cylinders, so that when the printing cylinders are linearly displaced, they can move around the fixed or fixed lower cylinders in combination with the vertical mobility. This makes it possible to change the length of the main stretching zone and to adapt it to a certain extent to the stack length.

The output lower cylinder has a larger diameter than all other cylinders.

The bearing blocks of the printing cylinders are arranged so as to be linearly displaceable on the bearing blocks of the lower cylinders.

The pressure on the pressure cylinder is exerted by spring-loaded pressure pistons, which are attached to a swivel and lockable bracket.

Furthermore, CH-PS 426 570 shows and describes a drafting system with a pre-stretching and a main stretching zone, in which the pressure cylinder is about the axis of the lower cylinder are pivotally arranged around to lengthen or shorten the loop of the sliver on the lower cylinders.

In order to be able to adapt the clamping line distances in the drawing fields which delimit the preliminary and main drawing zone to the fiber length of the fiber material to be processed, the mutual distances of the roller groups can be changed.

The increase in performance of a drafting system inevitably leads to an increase in the belt speed. High belt speeds, e.g. of 800 m / min. or more of the stretched tape, i.e. at the exit of the drafting system result in high speeds of the drafting system cylinders and this in turn places higher demands on the bearing of the cylinders.

In addition to the speed and the load, the accuracy of the assembly is also decisive for the service life of a bearing, e.g. in relation to the parallelism of the pressure and sub-cylinders to one another and in relation to the exact alignment of the cylinder shafts to the elements driving the shafts.

If one looks at the drafting device of DE-PS 1250 315 from the above-mentioned points of view, it is found that for the displaceability or fixability, the bearing blocks for the input cylinder pair and the bearing blocks of the middle and output pressure cylinders, no special device for precise fixing is present, so that these storage positions are only relatively imprecise or only with special, neither shown nor be the setting aids are precisely adjustable. However, the use of such aids is time-consuming, cumbersome and therefore unsatisfactory.

Moreover, the mutual linear displacement of the printing cylinders with respect to the sub-cylinders, to thereby change the nip spacing of the stretching zones, the disadvantage that the spring forces of _D ruckkol- ben, depending on the position of the printing cylinder on the lower cylinders, due to the fact of changing the force components in the radial direction act on the belt with different force.

Another disadvantage is the large diameter of the output lower cylinder, since this increases the distance between the clamping lines of the main stretching zone.

In addition, the drafting system has the disadvantage that in order to e.g. To be able to lead into a can, an additional deflection of the belt after the drafting system is required, which is necessary for the belt at belt speeds of 13.3 m / sec. and more results in an additional, undesirable centrifugal load and thereby creates a procedural disadvantage.

nicht übersteigt.The object of the invention is to remedy these disadvantages. The invention, as characterized in the claims, solves the problem in such a way that with increasing sliver speed due to thinning of the sliver in the stretching process, the direction of movement per stretching stage before and / or in the stretching zone is deflected such that the sliver running out relative to the incoming sliver gradually in the stretching process undergoes a deflection of essentially 90 angular degrees and, for each positive deflection, an acceleration value (r · ω ² ) of

does not exceed.

• a. durch die Umlenkung des Faserbandes im Streckprozess, trotz hoher Bandgeschwindigkeiten am Auslauf des Streckwerkes, die Radialbeschleunigungswerte an den Umlenkungen im Streckwerk in für das Faserband tragbaren Grössen bleiben.
• b. durch die Umlenkung im Streckprozess das im wesentlichen horizontal einlaufende Faserband nach dem Streckwerk ohne zusätzliche Umlenkung und mit kurzem Abstand in den Trichter, respektive in das nachfolgende eine Messgrösse abgebende Kalanderwalzenpaar geliefert werden kann, so dass ein optimal kurzes Stück fehlerhaftes Band zwischen dem letzten Zylinderpaar und den Kalanderwalzen weiter gefördert werden kann,
• c. durch die starre Anordnung der Unterzylinder eine von der Montage her bleibende präzise Ausrichtung der Lager gewährleistet ist, die einen positiven Beitrag an die Lebensdauer der Lager und eine Verkürzung der Einstelldauer zur Anpassung an andere Stapellängen erbringt,
• d. durch die Verschiebbarkeit der Druckzylinder um den genannten Bogen eine Anpassung des Streckwerkes an die Stapellänge des Faserbandes möglich ist, ohne Veränderung der Position der Unterzylinder,
• e. bei einer gleichbleibenden Kraftrichtung der Druckzylinder relativ zur Achse des entsprechenden Unterzylinders die Kraftwirkung auf das Faserband konstant bleibt.

The advantages achieved by the invention are essentially that:

• a. Due to the deflection of the fiber sliver in the drawing process, despite high belt speeds at the outlet of the drafting system, the radial acceleration values at the deflections in the drafting system remain in sizes that can be carried by the fiber sliver.
• b. Due to the redirection in the drawing process, the essentially horizontally entering sliver after the drafting unit can be delivered without additional redirection and with a short distance into the hopper or into the subsequent calender roller pair, so that an optimally short piece of defective belt between the last pair of cylinders and the calender rolls can be further promoted,
• c. The rigid arrangement of the lower cylinders ensures that the bearings are precisely aligned from the assembly, which makes a positive contribution to the life of the bearings and shortens the adjustment time to adapt to other stack lengths.
• d. due to the displaceability of the printing cylinders around the aforementioned sheet, it is possible to adapt the drafting system to the stack length of the fiber sliver without changing the position of the lower cylinders,
• e. with a constant direction of force of the pressure cylinder relative to the axis of the corresponding lower cylinder, the force effect on the sliver remains constant.

An advantageous embodiment of the drafting arrangement consists in the arrangement of the pressure cylinders on the pivotable arm. This means that even wide fiber slivers can be easily and safely inserted into the drafting system.

Another advantageous embodiment consists in that the displaceable printing cylinders can be adjusted by means of rastering to adapt to the stack length, and the extent of the displacement can be measured by means of a scale, so that they can be displaced quickly and precisely, which, despite the displaceability of the printing cylinders, ensures precise parallel guidance of the Pressure cylinder to the lower cylinders guaranteed.

Furthermore, the displacement of the second pressure cylinder delimiting the main stretching zone results in an arc around the axis of rotation of the corresponding lower cylinder Possibility of ensuring a tangential entry of the sliver into this pair of cylinders, regardless of whether a push rod with positive or negative deflection of the sliver is used.

The small diameter of the second lower cylinder delimiting the main drawing zone has the advantage that, despite the also advantageous large diameter of the previous lower cylinder, an optimally short clamping distance can be achieved.

Further advantageous configurations are contained in the other claims.

• Fig. 1 eine Seitenansicht des erfindungsgemässen Streckwerkes in Betriebsposition, halbschematisch dargestellt,
• Fig. 2 eine Frontansicht des Streckwerkes von Fig. 1 in Betriebsposition, halbschematisch dargestellt,
• Fig. 3 ein Detail des Streckwerkes von Fig. 1 von derselben Seite her gesehen, halbschematisch dargestellt,
• Fig. 4 das Detail von Fig. 3, teilweise im Schnitt gemäss Linie A-A, halbschematisch dargestellt,
• Fig.5+6 je eine Variante des Streckwerkes von Fig. 1, je als Ausschnitt von Fig. 1, vergrössert dargestellt.

The invention is explained in more detail below on the basis of illustrated exemplary embodiments. It shows:

• 1 is a side view of the drafting system according to the invention in the operating position, shown semi-schematically,
• 2 is a front view of the drafting arrangement of FIG. 1 in the operating position, shown semi-schematically,
• 3 shows a detail of the drafting arrangement of FIG. 1 seen from the same side, shown semi-schematically,
• 4 shows the detail of FIG. 3, partly in section along line AA, shown semi-schematically,
• Fig. 5 + 6 each a variant of the drafting system of Fig. 1, each as a detail of Fig. 1, enlarged Darge poses.

A drafting system 1 comprises a machine frame 2, on which the arm parts 4 forming a double arm are pivotably mounted by means of a hinge pin 3.

The arm parts 4 each comprise an arch part 5 and an arch part 6 and an end part 7. A notch 8 is provided on the end part 7 for receiving a fixing bolt 9 each. The fixing bolt 9 is part of a pneumatic cylinder 10. The fixing bolt 9 is designed as a part matching the notch 8 and serves to fix the double arm in the working position shown in solid lines in FIGS. 1 and 2. The operating position of the double arm is shown in Fig. 1 with dash-dotted lines.

Lower cylinders 11, 12, 13 and 14 are rotatably mounted on machine frame 2 by means of axes 15, 16, 17 and 18. The lower cylinders 11, 12, 13 and 14 are individually driven (not shown).

The arc parts 5 each include an arcuate guide slot 19 coaxial with the axis 15 and the arc parts 6 each have an arcuate coaxial with the axis 17 Guide slot 20. The guide slots 19 serve to guide a pair of bearing blocks 21 and 22 (only a part of the pair shown in FIG. 2), while the guide slots 20 serve to guide a pair of bearing blocks 23. In the end part 7, a guide slot 60 coaxial with the axis 18 is provided for guiding a pair of bearing blocks 25.

A pair of bearing blocks 22 is arranged at the entrance of the drafting system and a pair of bearing blocks 24 at the transition from the arch part 5 to the arch part 6 on the double arm 4.

Seen in the running direction of the sliver 26 (indicated by the arrow in FIG. 1), the drafting system 1 comprises in the following order a pressure roller 27, rotatably mounted in the bearing block pair 22, a first pressure cylinder 28 delimiting the beginning of the pre-stretching zone, rotatably supported in the bearing block pair 21, one the end of the pre-stretching zone delimiting second pressure cylinder 29, rotatably mounted in the bearing block pair 24, a first pressure cylinder 30 delimiting the beginning of the main stretching zone, rotatably supported in the bearing block pair 23 and a second pressure cylinder 31 delimiting the end of the main stretching zone, rotatably supported in the bearing block pair 25.

The cylinders 11 and 28 form the first, viewed in the running direction of the sliver, the cylinders 12 and 29 the second, the pre-stretch zone delimiting sliver.

The cylinders 13 and 30 form the first, the cylinders 14 and 31 the second, the main stretching zone delimiting fiber sliver.

The bearing block pairs 24 and 22 are arranged in a fixed manner, while the bearing block pairs 21 and 23, respectively, the guide slots 19 and 20, respectively, are arranged to be movable and fixable again in order to adapt to the length of the sliver to be processed. In addition, the pair of bearing blocks 25 is arranged in the guide slot 60 so as to be movable and fixable again in order to ensure the tangential entry of the sliver despite the changeable entry position of the sliver, caused by the displacement of the pressure cylinder 30.

In order to ensure the parallelism of the printing cylinders 28 and 30, respectively, to the lower cylinders 11 and 13, respectively, seen in the radial direction to the axes 15 and 17, on the one hand, raster teeth 32 and 32 are shown on the arc parts 5 and 6 (FIGS. 3 and 4). and a raster scale 33 corresponding to the number of teeth and, on the other hand, a raster device 34 which engages in the teeth 32 is provided on the bearing block pairs 21 and 23. This grid device 34 is assigned to each individual bearing block of the bearing block pairs 21 and 23. Such a bearing block comprises a bearing block lower part 35 with a guide port 36 for receiving and guiding a shaft bearing 37 of a pressure cylinder shaft 38. Depending on a _D impression cylinder shaft 38 is used to hold the platen roller 27 and the printing cylinders 28, 29, 30 and 31st

The lower bearing block 35 is also designed as a cylinder, with a piston 39, an associated piston rod 40, a spring 41, a compressed air connection 42 and a ventilation opening 43.

The end of the cylinder is used with the bearing block terteil 35 fixed bearing block upper part 44.

A guide pin 45 belonging to the raster device 34 is firmly screwed into the bearing block upper part 44 by means of thread 46 and serves to guide a raster part 47. A compression spring 48 clamped between the raster part 47 and a guide pin upper part 45.1 presses the raster part 47 against the bearing block upper part 44. The raster part 47 can be against the Force of the spring 48 can be lifted off the upper bearing block 44.

The raster teeth 32 provided on the arch parts 5 and 6 engage in the teeth 49 provided in the raster part 47 when the raster part 47 rests on the bearing block upper part 44.

Furthermore, two guide pins 50 are pressed into the bearing block upper part 44, which protrude into the guide slots 19 and 20, respectively, and which are selected in diameter in such a way that this results in precise sliding guidance of the individual bearing block 21, 23, 25 along the guide slot 19, 20, 60 results.

A fixing screw 51 with nut 52 fixes the individual bearing blocks on the arch parts 5 and 6, or respectively on the end part 7.

If the bearing block pairs 21 and / or 23 are now to be displaced, the fixing screw 51 (FIGS. 3 and 4) is loosened, the raster part 47 is lifted from the upper part 44 of the bearing block 44 by manual force against the force of the spring 48, and the bearing block pair 21 is manually lifted and / or 23 on the arch part 5, respectively 6, adjacent to the Guide slot 19 or 20, along. The degree of displacement can be read on the raster scale 33.

The bearing block pairs 24, 25 and 22 comprise the same elements as the described bearing block pairs 21 and 23 with the exception that the raster device 34 is omitted.

The bearing block pairs 24 and 22 are arranged in a fixed manner. The mobility of the bearing block pairs 25 will be described later.

Furthermore, the sliver 26 after the last sliver clamping point, given by the cylinders 14 and 31, is combined in a hopper 53 and passed on to a rotatably mounted pair of calender rolls 54 known per se. The pair of calender rolls 54 consists of a fixedly arranged calender roll 55 and a calender roll 56 arranged displaceably therefrom.

The funnel 53 is arranged such that it can be tilted in the direction of the arrow B and projects with the sliver outlet part 57 into the sliver feed gap (not shown) of the pair of calender rolls 54.

When the roller 56 is displaced away, the funnel 53 can be tilted in order to be able to comfortably guide the strip discharged from the last rollers 14 and 31 into the funnel.

The drafting device 1 can also be provided with a so-called push rod 58 (FIG. 5), which, provided in the main drawing zone, deflects the fiber sliver positively and in the process guides the fibers within the drawing zone as an aid. A positive deflection means a deflection with a radius directed away from the machine frame 2 that will. The push rod 58 is provided in the main stretching zone in such a way that when the clamping stretch of the main stretching zone is extended, given by the clamping points of the cylinder pairs consisting of the cylinders 13 and 30, or respectively 14 and 31, by pushing back the pressure cylinder 30 against that in FIG. 1 Position shown with dash-dotted line, the deflection around the push rod 58 is reduced. The reduction in the deflection ends when the distance connecting the push rod 58 and the clamping point between the cylinders 13 and 30 forms a tangent to the circumference of the cylinders 13 and 30. This first clamping distance is indicated in FIG. 5 by arrow E, while the maximum clamping distance of 85 mm is reached at the point indicated by arrow F.

When the push rod 58 is used, the bearing block pair 25 is positioned or fixed in such a way that the sliver 26 is tangentially caught by the cylinders 14 and 31.

Furthermore, the drafting system 1 can be provided as a variant to the push rod 58 with a push rod 59 (FIG. 6) which deflects the sliver negatively. With this solution, the deflection of the sliver given by the push rod remains constant. In order to allow the fiber sliver to be tangentially gripped by the cylinders 14 and 31 in this variant as well, the bearing block pair 25 is shifted into the position shown in FIG. 6. In this position, the upper guide pins 50 (seen in the viewing direction according to FIG. 1) of the bearing block pair 25 rest against the upper end (not visible) of a guide slot 60 provided in both end parts 7, while for the variant with the push rod 58 the lower guide pins 50 of the pair of bearing blocks 25 bear against the lower end 61 (FIG. 6) of the guide slots 60.

In this way, the same drafting system is suitable for the use of both push rod variants without changing a part.

A pneumatic cylinder 62, which is pivotally connected to the machine frame 2 and whose piston rod end part 63 is connected to the two arm parts by means of a rod 64, serves to lift the arm parts 4 into the operating position shown in dash-dotted lines in FIG. 1 and thus to introduce a sliver into the drafting system 4 is connected.

The fiber sliver is placed over the lower cylinders 11, 12, 13, 14 and the funnel 53 tilted in direction B for introduction into the drafting system in the open position of the drafting system.

The drafting system is closed again by reversing the function of the cylinder 62 and locked again by reversing the function of the cylinder 10.

After start-up in slow speed, the drawn material is fed into the hopper 53 and into the pair of calender rolls 54. The drafting system can then be switched to production.

The term "short to long staple fibers" is intended to mean cotton and chemical fibers with a staple length of up to 80 mm.

For those lower cylinders that are the beginning of the pre-ver The stretching zone, or the main stretching zone, is chosen to have a diameter of 90 mm, so that, when processing fibers with a stack length of 80 mm, a wrap angle of the fiber sliver on the lower cylinders mentioned can be guaranteed by experience of a maximum of 45 angular degrees.

With wrap angles of more than 45 degrees, the rope friction between the fiber sliver and the lower cylinder becomes too great when the lower cylinders are corrugated.

The high belt speeds mentioned at the beginning result in high centrifugal forces, i.e. high radial acceleration values.

For example, at a belt speed of 1000 m / min. at the outlet of the drafting system and a diameter of 90 mm for the first lower cylinder 13 of the main drawing zone and a draft ratio for the drawing zone of 4: 1, a radial acceleration value a = r · ω ² = 385 m / sec. ² , which corresponds to approximately 38 times the acceleration due to gravity.

If you wanted to use a drafting system according to the prior art mentioned, which with 1000 m / min. delivered sliver with a radial acceleration value of a _r = 385 m / sec. Redirect ² so would have a _U mlenkradius of 720 elected mm, which would be device moderately unfavorable.

In order to achieve an optimally short clamping distance for the stretching of fibers with short, despite the advantageous large diameter of the first lower cylinder 13 of the main stretching zone To obtain zen stack lengths, a diameter was selected for the second sub-cylinder 14 of the main drawing zone which corresponds essentially to one third of the diameter of the first sub-cylinder 13 mentioned, for example of 28 mm.

By choosing a small diameter for this cylinder 14, the high belt speeds result in high speeds, which on the other hand results in high radial acceleration values. However, since the deflection of the sliver on this cylinder is zero or a few degrees of angle, and therefore no or a very small sliver mass has to be deflected, there are no or relatively small centrifugal forces (Z = mrω ² ) for the self-contained sliver. The situation is different for detached individual fibers directed away from the cylinder 14 from the self-contained sliver. Such fibers are deflected until the deflected mass results in a centrifugal force that is greater than the adhesive forces between the fibers and the cylinder.

To counteract possible electrostatic charging of the fibers, ionizers can be used in a manner known per se.

Claims (5)

1. A method for processing a sliver with a stacking area from short to long staple fibers in a drafting system for spinning machines, in particular for draw frames, in which the sliver is stretched several times in drawing stages containing drawing zones, characterized in that with increasing sliver speed due to thinning of the sliver in the stretching process, the direction of movement per stretching stage upstream and / or in the stretching zone is deflected so positively that the outgoing sliver (26) in relation to the incoming sliver (26) gradually experiences an overall positive deflection of essentially 90 degrees and per positive deflection does not exceed a radial acceleration value (r.ω ² ) of 400 m 2. s 2. The method according to claim 1, characterized in that the sliver in the main stretching zone is additionally deflected around a push rod (58, 59) and is thereby guided in the alternative. 3. The method according to claim 1 and 2, characterized in that in the individual deflection of the sliver, the deflection of the longest fiber contained therein is not more than 45 degrees. 4. The method according to claim 1, characterized in that the stretching process comprises a preliminary and a main stretching zone. 5. The method according to claim 1, characterized in that the sliver (26) is compressed before stretching.

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