FIELD OF THE INVENTION

The present invention relates to a device and a method for producing cladded yarn on a ring spinning frame.

BACKGROUND OF THE INVENTION

In the prior art devices for producing cladded yarns on ring spinning machines are described. The cladded yarn is produced in that a sliver of staple fibers passes a drawing unit in a ring spinning machine before it is spun into a yarn. A second yarn is added which is foreseen to enwrap the staple fibers at least partially. Different positions of adding fibers are known.

US2013040523 was published in February 201 3 in the name of The Japan Wool Textile Co. Ltd. It describes a heat-resistant flame-retardant protective suit fabric, which is formed of a spun yarn. The spun yarn for forming the fabric is a two-fold yarn prepared by twisting a first yarn of a uniform blended spun yarn, which is covered by a second yarn on a ring spinning frame.

DE19804341 was published in August 1 999 in the name of Maschinenfabrik Rieter AG. A sliver of staple fibers passes through a drawing unit in which the fibers are extended before the fibers leave the drawing unit by passing between two delivery rollers and are spun into a yam. Before the delivery rollers an additional yarn is added to the process from a supply package. The additional yarn passes between the delivery rollers and is foreseen to enwrap the fibers.

WO9409195 was published in April 1 994 in the name of the Wool Research Organisation of New Zealand and describes a process and apparatus for producing a yarn comprising staple fibres twisted together with one or more filament or pre- spun yarns on ring or other types of spinning frames. A proportion of staple fibres are overfed into the structure to provide a bulky sheath of fibres twisted around a central core consisting of one or more filament or pre-spun yarns and a second proportion of the staple fibres.

DE102010051434 was published in May 201 2 in the name of Zwickauer Kam- mgarn GmbH and is directed to a device which comprises different fiber material templates that are provided for different fiber materials. A drafting roller is provided for distortion of a fiber material. The fiber material which is detached from a clamping roller arranged at downstream side of the drafting roller, is then twisted into a first yarn. A cover yarn is formed by supplying fiber material from a fiber material supply unit for enwrapping the first yarn.

One drawback of the prior art is that the process of forming the cladded yarn cannot be controlled in a sufficient manner which results in an inconsistent result with respect to quality. Furthermore, the devices known from the prior art do not offer the opportunity to take influence on the process as such on a ring spinning frame with many spindles. Furthermore, the devices known from the prior art do not allow to arrange the spindles in a dense manner.

It is therefore an object of the invention to overcome the problems known from the prior art.

SUMMARY OF THE INVENTION

The invention is directed to a device and a method for producing a cladded yarn based on a ring spinning machine. If appropriate, the device can be used in a similar way on any other type of spinning frame. Per operative spindle (i.e. spindle foreseen to produce cladding yarn according to the invention) the device comprises a drafting unit with several drafting rollers rotating with different rotational speed. Thereby, the fibers of a roving (sliver of unwound fibers), which passes through the drafting unit, are drawn in a defined manner before they are spun in a conventional manner to a yarn by a traveler revolving around the spindle and wound onto a bobbin which is arranged on the related spindle and which rotates at a lower speed then the traveler. A cladding yarn is added to the spinning process in the region of the spinning triangle where the fibers exiting from the drafting unit are spun into a yarn. In principle the aim is to add the cladding fibers in a way that in the resulting cladded yarn they enwrap the yarn spun from the fibers of the roving. A device for making of cladded yarn on a ring spinning frame according to the invention comprises per operative spindle a first creel foreseen to hold at least one bobbin of roving and a second creel foreseen to hold at least one bobbin of cladding yarn. Furthermore, it comprises a draft control device suitable to adjust the draft of a cladding yarn removed from the bobbin of cladding yarn and before the cladding yarn enters the spinning process, respectively cladding process. The draft control device is preferably designed to adjust the draft in the cladding yarn in a flexible manner. In addition the draft control device can be foreseen to provide a force to unwind the cladding yarn from the thereto related bobbin of cladding yarn and/or the deliver the cladding yarn to the spinning, respectively cladding process, where the cladding yarn is cladded around the already spun yarn made out of the roving. If required, several draft control devices can be interlinked to each other such that draft is adjustable simultaneously on different operative spindles. In a preferred embodiment the draft control device is designed to individually interrupt the feeding process of the cladding yarn per spindle, which may be advantageous e.g. in the case of maintenance. Furthermore, the device may comprise a monitoring device to monitor the presence of the cladding yarn and to interrupt the supply of the roving to a related drafting unit if the cladding yarn is not present.

The cladding yarn is preferably delivered to the spinning process, respectively the cladding process by an injector in the region of the spinning triangle of the spinning process of the roving. In a preferred embodiment, the injector is arranged adjustable with respect to the drafting unit of the related spindle, respectively the spinning point, to precisely introduce the cladding yarn into the spinning process. Good results can be achieved when the injector is adjustable with respect to at least two axis which are distanced with respect to each other. Depending on the design the at least two axis are arranged at an angle with respect to each other or are laying in a common plane.

A space saving arrangement can be obtained, when the second creel is arranged vertically above the first creel. Alternatively or in addition, the second creel can be integrated in the first creel.

In an embodiment of the draft control device, the cladding yarn is clamped between at least one drive shaft and a pulley as described hereinafter in an exemplary manner. If required, a pulley guiding means can be present which guides the pulley in lateral direction. Alternatively or in addition, the pulley guiding means can be foreseen to lift up the pulley from the drive shaft, thereby individually interrupting the influence of the draft control unit on the cladding yarn. Additional details and variations of the draft control device are described hereinafter in connection with the drawings.

In a variation, the draft control device comprises a first and a second disc arranged at a distance with respect to each other forming a circumferential channel by which the cladding yarn passes to adjust the draft of the cladding yarn.

Depending on the field of application, the monitoring device may comprise a sensor to monitor the presence of the cladding yarn and an actuator to interrupt the supply of roving when the sensor indicates a faulty state of the cladding yarn. In a low cost version, the monitoring device can be left away, although in this case the spinning process is not interrupted automatically if a problem with the cladding yarn occurs. In a further variation, the monitoring device is integrated in the draft control device.

In a preferred embodiment of the monitoring device, the sensor comprises a deflection pulley which is driven by the cladding yarn. The deflection pulley is interconnected to a transducer which provides a signal depending on the rotation speed of the deflection pulley and/or the tension in the cladding yarn. The actuator comprises a receiver suitable to receive and react upon the signal of the transducer, such that in case of a faulty status in the rotation speed of the deflection pulley and/or the tension in the cladding yarn, the supply of the roving is interrupted by the actuator. The monitoring device may comprise an indicator which optically and/or acoustically and/or via a bus indicates a faulty status of the related spinning station. The actuator may comprise or may be interconnected to a blade to interrupt the supply of the roving, e.g. by cutting the fibers of the roving.

In a preferred embodiment of the monitoring device, the actuator comprises or is interconnected to a wedge, which is arranged in a displaceable manner and can be introduced between the entry rollers of the drafting unit in a defined manner. Thereby the supply of the roving can be interrupted in a secure manner. The wedge can be driven by at least one roller of the drafting unit or a drive shaft therefore. When becoming active the actuator receives a signal from the sensor of the monitoring unit and then the actuator releases the wedge which is then moved between the entry rollers based on the rotation of the entry rollers. The wedge thereby temporarily lifts the entry rollers apart from each other against the force of a spring. When the wedge achieves a final position its movement is stopped by a block. Depending on the design the wedge can be straight or curved, e.g. sitting on a drive shaft acting upon at least one entry roller.

In a preferred variation, the draft control device is arranged in a vertical direction below the bobbin of cladding yarn. To improve precision a fiber guiding means may be arranged between the bobbin of cladding yarn and the draft control device guiding the cladding yarn from the bobbin of cladding yarn to the draft control device in a precise manner. Alternatively or in addition, an eyelet is arranged with respect to the moving direction of the cladding yarn before the draft control device for the cladding yarn taking influence on the interaction between the cladding yarn and the draft control device.

In a preferred embodiment at least the part of the injector which is responsible to deliver the cladding yarn to the cladding process is arranged movable (travelling) in an oscillating manner with respect to the fiber movement in lateral direction, i.e. parallel to the length direction of the spinning frame. This can e.g. be achieved in that the complete injector, if present the monitoring device and other guiding means for the cladding yarn are arranged travelling. The travelling of the cladding yarn in lateral direction is in principle synchronized with the travelling of the rov- ing with respect to the rollers of the drawing unit. Thereby it is possible to avoid extensive local wear of the rollers for the drafting unit.

Depending on the field of application and the effects to be achieved, the rollers of the drafting unit can be operated at variable speed, e.g. in that the speed of the entry rollers is increased in a sudden manner and/or the speed of the delivery rollers is reduced in a sudden manner for a defined period of time before both speeds are adapted to their normal value again. Thereby, the supply of the fibers of the roving is altered such that the resulting yarn comprises thereto related slubs which are then cladded by the cladding yarn.

A method according to the invention comprises the following method steps: a) providing a bobbin of roving and a bobbin of cladding yarn; b) supplying the roving from the bobbin of roving to a drafting unit of a ring spinning device, said drafting unit comprising a pair of entry rollers and a pair of delivery rollers; c) drawing the roving in a defined manner between the entry rollers and the delivery rollers of the drafting unit; d) spinning the fibers which exit from the drafting unit by the delivery rollers into a yarn and winding the yarn onto a bobbin; e) supplying the cladding yarn from the bobbin of cladding yarn to an injector which introduces the cladding yarn to the spinning, respectively cladding process in an area where the roving exits the drafting unit; f) adjusting the draft in the cladding yarn by a draft control device in an area between the bobbin of cladding yarn and the injector.

If required, the presence, respectively the status of the cladding yarn is monitored by a sensor of a monitoring device. The sensor is interconnected to an actuator foreseen to interrupt the supply of the roving when a faulty status is indicated by the sensor, i.e. when the cladding yarn is not present. The sensor of the monitoring device is preferably arranged between the injector and the bobbin of cladding yarn and the actuator between the entry rollers of the drawing unit and the bobbin of roving.

BRIEF DESCRIPTION OF THE DRAWINGS

The herein described invention will be more fully understood from the detailed description given herein below and the accompanying drawings which should not be considered limiting to the invention described in the appended claims. The drawings are showing:

Fig. 1 a device for making of cladded yarn in a perspective view from above and the left side; Fig. 2 the device according to Figure 1 in a perspective view from above and the right side;

Fig. 3 detail E of Figure 2;

Fig. 4 detail F of Figure 3;

Fig. 5 the device according to Figure 1 in a front view;

Fig. 6 the device according to Figure 1 in a side view;

Fig. 7 a partial view of the embodiment according to Figure 1 ;

Fig. 8 a monitoring device according to the invention.

DESCRIPTION OF THE EMBODIMENTS

The foregoing summary, as well as the following detailed description of the preferred embodiments, is better understood when read in conjunction with the appended drawings. For the purposes of illustrating the invention, an embodiment that is presently preferred, in which like numerals represent similar parts throughout the several views of the drawings, it being understood, however, that the invention is not limited to the specific methods and instrumentalities disclosed. Figure 1 shows a device 1 for producing cladded yarn in a perspective view from above and the left. Figure 2 shows the device 1 according to Figure 1 in a perspective view from above and the right. Figure 3 shows detail E according to Figure 2. Figure 4 is showing detail F of Figure 3. Figure 5 shows the device 1 according to Figure 1 in a front view and Figure 6 in a side view. Figure 7 shows parts of the device in a reduced manner. Figure 8 shows a monitoring device.

The shown device 1 incorporates, respectively is mounted on a ring spinning frame (not shown in detail) comprising several spindles arranged lateral to each other in a longitudinal direction of the ring spinning frame. In the herein described drawings, the ring spinning frame and details thereof are shown only when relevant for the description and understanding of the invention.

Per spindle, the ring spinning frame comprises a drafting unit 2 comprising several drafting rollers 3 rotating with different rotational speed with respect to each other. The drafting unit 2 comprises a pair of entry rollers 4, at least one pair of intermediate rollers 5 and a pair of delivery rollers 6. A roving 7 consisting of parallel not yet spun fibers (not shown in detail) is unwound from a bobbin of roving 8 passes through the drafting unit 2 before it becomes subject of the spinning process. As the rotating speed of the rollers 5, 6, 7 increases in the flow direction of the fibers of the rowing 7 passing through the drafting unit, the fibers are drawn in a defined manner before they leave the drafting unit and are spun in a conventional manner into a yarn 8 by a traveler revolving on a ring around the spindle and wound onto a bobbin which is arranged on the spindle and which rotates at a lower speed then the traveler (not shown in detail). Although in reality the roving 7 has a variable thickness over its length, in the drawings the roving 7 is shown in an exemplary manner as individual line. Instead of a roving 7 in principle consisting of unwound fibers, it is possible to use alternatively or in addition a yarn instead which consists of spun or partially spun elastic and/or non- elastic fibers.

Per spindle a bobbin of roving 8 is arranged vertically above at a distance from the drafting unit mounted on a first creel 1 0. From there, the roving 7 is guided to the drafting unit where it enters the above described process.

Furthermore, the device 1 comprises per spindle a bobbin of cladding yarn 1 1 which is arranged on a second creel 1 2. If appropriate, the second creel 1 2 can be attached to or be integrated into the first creel 1 0. In an embodiment, the second creel 1 2 is arranged vertically above the first creel 1 0. A cladding yarn 1 3 is unwound from the bobbin of cladding yarn 1 1 and is guided by guiding means 1 4 to a draft control device 1 5 which is normally arranged in a vertical direction above the drafting unit 2 but below the bobbins of roving 8. The guiding means 1 4 of the here shown variation of the invention incorporates a tube 1 4 which helps to guide the cladding yarn from the bobbin of cladding yarn 1 1 to the draft control device 1 5. As it can be seen, the cladding yarn 1 3 is unwound from the bobbin of cladding yarn 1 1 over the top and enter the air tube 1 4 at the upper end of the bobbin of cladding yarn 1 1 . In the shown variation, the air tube 1 4 simultaneously acts as holding device for the bobbin of cladding yarn 1 1 , If appropriate the air tubes 1 4 can be at least temporarily charged with compressed air to convey a loose end of a cladding yarn 1 3 from the bobbin of cladding yarn 1 1 to the lower end of the air tube 1 4. This is in particular helpful when preparing the spinning process.

In the shown variation, the draft control device 1 5 comprises at least one rotating drive shaft 1 6 which extends in longitudinal direction (x-direction) of the spinning frame and which interacts with more then one spindle. The drive shaft 1 6 is mounted on cantilever arms 1 7 which are attached to a frame of a spinning machine. Other ways to support the at least one drive shaft are possible. Further embodiments will be described herein after. The drive shaft 1 6 is driven by an actuator (not visible) at a speed which is adjustable to adjust the tension in the cladding yarn 1 3 and in relation to the production speed of the spinning frame. During operation, the cladding yarn 1 3 is clamped between at least one drive shaft 1 6 and a pulley 1 8 which is supported by at least one drive shaft 1 6 and guided at least laterally by pulley guiding means 1 9. In the shown variation the pulley 1 8 is supported by two drive shafts 1 6 arranged parallel to each other and rotating in principle at the same speed. To avoid unwanted travelling of the cladding yarn, a first eyelet 20 is arranged upstream to the draft control device 1 5 making sure that the cladding yarn 1 3 is properly clamped between the pulley 1 8 and at least one drive shaft 1 6. To interrupt the process, the pulley guiding means 1 9 can be foreseen to act as or form part of a pulley lift up device as schematically shown in Figure 2. Therefore, the pulley guiding means 1 9 is attached to a retaining rod 21 in a swiveling manner such that the pulley 1 8 can be lifted up from the drive shaft 1 6. This offers the advantage, that the spinning process can be individually interrupted per spindle.

As in the herein shown embodiment the draft control device 1 5 may be designed to be responsible for the continuous and accurate feeding of the cladding yarn 1 3 to the spinning, respectively cladding process where the cladding yarn is cladded around the already spun yarn 9. Therefore the draft control device 1 5 does not only control the draft in the cladding yarn but also provides the force to unwind the cladding yarn from the related bobbin with cladding yarn and delivery of the cladding yarn 1 3 to the injector 27. The cladding yarn 1 3 is clamped between the at least one drive shaft 1 6 and the pulley 1 8. The resulting force is at least partially responsible to pull the cladding yarn 1 3 off from the bobbin of cladding yarn 1 1 along the guiding means 1 4 and if present across other guiding means. However the same force is responsible to prevent unwanted sliding of the cladding yarn upstream or downstream. Figure 4 shows in a schematic manner how the cladding yam 1 3 is cladded around the spun fibers of the roving 7 forming the cladded yarn 9. In the shown variation the cladding takes place when the fibers of the roving 7 are already spun to a yarn.

Depending on the field of application, the draft control device 1 5 may comprise alternatively or in addition two discs (not shown in detail) which are arranged parallel to each other at a certain distance forming a circumferential channel. The two discs are foreseen to clamp the cladding yarn 1 3 in a defined manner in be- tween the two discs. Each disc may comprise grooves which are arranged in lat ^¬ eral direction and which are aligned with respect to the grooves of the opposite disc. By adjusting the distance between the two discs, the resistance exerted on the cladding yarn 1 3 can be adjusted. If required, the discs can be actively driven by at least one drive shaft 1 6 as described above.

As visible e.g. in Figure 3 and shown in more detail in Figure 8 the cladding yarn 1 3 interacts with a monitoring device 22 which interrupts the supply of the roving 7 when the supply of the cladding yarn 1 3 is interrupted. In the shown variation, the monitoring device 22 is fully mechanical and comprises a roll 23 which is me ^¬ chanically interconnected to a blade 24 by a lever 25. The lever 25, the thereto connected roll 23 and the blade 24 are attached in a swiveling manner to a holding frame 26. The roll 23, the lever 25 and the thereto interconnected blade 24 can be moved between a closed and an open position, whereby the in the open position the roving 7 can freely pass across the monitoring device 22 and in the closed position the blade 24 is pressed against the holding frame 26 and thereby interrupts the supply of the roving 7 to the drafting unit. Good results may be achieved by an adopted version of the monitoring device as described in WO2010/006955 of the same applicant. The roll 23 acts as sensor as it meas ^¬ ures the tension in the cladding yarn 1 3. The blade 24 acts as actuator which is interconnected via the lever 25 to the sensor. Therefore, the actuator interrupts the supply of the roving 7 when the tension in the cladding yarn falls below a de ^¬ fined level. Alternatively or in addition, the blade 24 of the monitoring device 22 can be controlled in an electro mechanical manner. Therefore, each monitoring device 22 comprises a sensor which monitors the presence of the cladding yarn 1 3 and if not present or faulty, interrupts the supply of the roving 7 to the drafting unit 2.

Alternatively or in addition, the monitoring device 22 may comprise an indicator which optically and/or acoustically and/or via a bus indicates a faulty status of the related spinning station.

As visible in Figure 6, the draft control device 1 5 of the shown variation comprises a first and a second drive shaft 1 6 arranged parallel to each other extending in longitudinal direction (x-direction) of the spinning frame (not shown in detail) and rotating simultaneously around their axis in the direction of an arrow A. The first and the second drive shaft 1 6, which are in Figure 6 shown only partially, are supported by a cantilever 1 7 which is attached directly or indirectly to the spinning frame (not shown in detail). Of the cantilever 1 7 only half is shown, such that the inside becomes visible. As it can be seen, each of the drive shafts 1 6 are supported inside the cantilever 1 7 by a first and a second bearing 31 , 32 having parallel axis of rotation but are arranged at an angle a as shown in the drawing. The angle a is in the shown variation in the range of 1 25° to 1 75° and prevents the first and second drive shaft to jump of from the bearings 3 1 in an unwanted manner. The first and the second drive shaft 1 6 are composed from segments which are put together (i.e. interconnected to each other) by bushings 33. The bushings 33 form in the shown variation on one hand the interconnection (link- age) between two segments of the drive shafts 1 6 (only one shown) and on the other hand provide a bearing surface 34 on the outside which interacts with the bearings 3 1 , 32 attached to the cantilever 1 6. Via the bushings 33 the drive shafts can be interconnected to each other providing modular extensible solution. An outer surface 35 of the drive shafts 1 6 can be equipped with a friction increasing features such as knurls (not shown in detail). As visible in the drawings, the drive shafts 1 6 are foreseen to receive a pulley 1 8 which sits between the two drive shafts 1 6 and rotates in the opposite direction. The pulley 1 8 comprises a circumferential running surface 36 which, if required, can be made out of a traction increasing material such as rubber to prevent unwanted slip. During production cladding yarn 1 3 runs between at least one of the drive shafts 1 6 and the pulley 1 8 which is foreseen to press the cladding yarn 1 3 in a controlled manner against the at least one drive shaft 1 6 and thereby to adjust the draft of the clad ^¬ ding yarn. As the drive shafts 1 6 interact with more then one spindle (here only one of them is shown in an exemplary manner) it is very simple to adjust the draft on all spindles simultaneously. To make sure that the pulley 1 8 stays on track, on either side of the pulley 1 8, a pulley guiding means 1 9 (as e.g. shown in Figure 1 ) can be foreseen.

Furthermore, as among others visible in Figures 1 to 3 the device 1 comprises per operating spindle an injector 27 which in the shown variation of the invention is arranged in moving direction of the roving 7 behind the delivery rollers 6 of the drafting unit 2. As best visible in Figure 3, the injector 27 comprises a first and a second bail 28, 29 which are arranged at a distance with respect to each other and which serve to deliver the cladding yarn 1 3 to the spinning process, respectively the cladding process. The first and the second bail 28, 29 are mounted to a holder 30 which in the shown embodiment is adjustable with respect to the position where the cladding yarn 1 3 is introduced into the spinning process. The holder 30 is itself mounted on an arm 37 which an itself be arranged swiveling with respect to a mount 38 interconnected to a fastening bar 39 which can be arranged oscillating in x-direction along with the monitoring device 22 which in the shown variation is attached to the same fastening bar 39. In Figure 3 the oscillation movement of the injector 27, here parallel to the x-direction, is schematically indicated by arrow 40.

In the shown embodiment, the first and the second bail 28, 29 are arranged at an angle of approximately 90° with respect to each other. Other arrangements are possible if required, as long as the introducing of the cladding yarn 1 3 takes place at the right position. The holder 30 shown in the examples is made out sheet metal. Alternatively or in addition, the holder can be made out of injection molded plastic and/or bent wire.

Rather, the words used in the specification are words of description rather than limitation, and it is understood that various changes may be made without departing from the Spirit and scope of the invention. LIST OF DESIGNATIONS

1 Device for making cladded 2 1 Retaining rod

yarn 22 Monitoring device

2 Drafting unit 25 23 Roll (monitoring device)

3 Drafting rollers 24 Blade (monitoring device)

4 Entry roller 25 Lever (monitoring device)

5 Intermediate roller 26 Holding frame (monitoring

6 Delivery roller device)

7 Roving 30 27 Injector

8 Bobbin of roving 28 First bail

9 Yarn 29 Second bail

1 0 First Creel 30 Holder

1 1 Bobbin of cladding yarn 3 1 First bearing

1 2 Second creel 35 32 Second bearing

1 3 Cladding yarn 33 Bushing

1 4 Guiding means, air tube 34 Bearing surface

1 5 Draft control device 35 Outer surface

1 6 Drive shaft 36 Running surface (pulley 1 8)

1 7 Cantilever arm (cantilever) 40 37 Arm

1 8 Pulley 38 Mount

1 9 Pulley guiding means 39 Fastening bar

20 Eyelet 40 Oscillation ( Injector)