Abstract: To provide continuous fiber-reinforced thermoplastic pellets having a good dispersion property of a reinforcing fiber bundle in injection molded articles and capable of achieving a satisfactory outward appearance of the injection molded articles and satisfying a mechanical strength of the injection molded articles by fully exerting the reinforcing effect, and a manufacturing method of the same.

Abstract: A method for operating an open-end rotor spinning machine having a plurality of workstations, usually a large number, each including a spinning device with a rotor housing, to which negative pressure can be applied, in which a spinning rotor (23) revolves at a high rotational speed, to produce a yarn, as well as a winding device to produce a cross-wound bobbin (18), wherein the connection of the workstations to a central negative pressure supply can be selectively switched off. The application of negative pressure to the rotor housing is limited to the spinning devices which are producing yarn as well as the spinning devices which are repiecing.

Abstract: The invention is a method of manufacturing, by friction spinning, a reinforcing thread (1) for fabric covering or a technical textile intended to be incorporated in a textile base, in which: the spinning machine (7) is supplied with a core thread (2); and simultaneously with a silver (9) of fibers (3, 4), the fibers (3, 4) being individualised and then associated with the said core thread (2). The silver (9) of fibers is formed from a mixture of hot-melt fibers (3) and high melting point fibers (4).

Abstract: An air-spinning arrangement has an opening device having a feed device and an opening roller for opening a sliver into individual fibers. A perforated removal roller receives the opened fibers from the opening roller in the circumferential direction. A conveyor belt conveys the fibers from the removal roller to a nip with a following air-spin nozzle for forming a yarn. The conveyor belt is arranged axially-parallel with the removal roller. A sufficiently close spacing of the conveyor belt from the removal roller is selected such that the fibers conveyed to the removal roller can be picked up by mechanical contact, and the conveyor belt is driven such that it deflects the fibers by approximately 90° and conveys them to the combing location. The air-spinning arrangement allows the formation of a fiber structure that is well suited to the air-spinning process.

Abstract: Singled fibers from a fiber strand, separated by a rotor, are collected by suction on a continuously moving surface of a perforated belt or rotary drum. The fiber packet is not formed with a twist in this region and, only upon transfer to a downstream region is the twist applied, e.g. by a ring spindle.

Abstract: The spinning rotors of open-end spinning aggregates are supported on supporting discs. For the purposes of non-contact revolution counting, a front side of a supporting disc is provided with at least one permanent magnet. A signal receiver of a maintenance device selectively arrangeable at the spinning aggregates is arranged at the permanent magnet. The distance between the permanent magnet and the signal receiver is bridged by a ferromagnetic information transmitter, which is preferably arranged on a swivelling housing section of the spinning aggregate.

Abstract: A process for open-end spinning provides for at least one sliver being opened into single fibers. A wide fiber veil is formed from parallel single fibers extending in the direction of motion, which fiber veil is fed to a transporting surface by means of a moving collecting surface. The single fibers are transferred from the collecting surface to the transporting surface at a transfer point, whereby the direction of motion of the fiber veil is abruptly changed, however the current relative position of the single fibers remaining essentially constant. This motion direction change occurs at the transfer point, with the respective front part of the fiber veil being transferred to the transporting surface as a fiber group in a predetermined sequence, and the transporting surface moves transversely to the direction of motion of the collecting surface.

Abstract: A spinning process provides for opening at least one sliver to single fibers and for depositing the single fibers on a moving collecting surface in the form of an expanded fiber veil. During transport on the collecting surface and, if required on a moving drafting surface downstream thereof, the fiber veil is condensed, transversely to its direction of motion, to a strand. The roving-like strand is transported through a nipping line and twisted to a yarn under the action of a rotating air stream. Fiber ends are hereby spread out from the strand, which are helically wrapped around the yarn.

Abstract: In the case of an arrangement for open-end spinning, a driven suction roller is provided which in a take-up zone takes up fiber material opened to single fibers and transports it to a suctioned yarn formation line. The yarn formation line is defined by a suction insert arranged in the inside of the suction roller, and extends transversely to the transport direction of the suction roller on the surface thereof. In extension of the yarn formation line a twist device is provided. On the side facing away from the twist device, the suction roller is supported on the suction insert while freely overhanging same, so that the twist device reaches directly up to the suctioned yarn formation line. The yarn formation line is preferably inclined at an angle towards the take-up zone on the side facing away from the twist device.

Abstract: In a spinning process for producing a yarn, fiber material in the form of at least one sliver is opened to a fibrous veil consisting of single fibers, and is deposited on an air-permeable suctioned collecting surface. The speed of the fibrous veil transported on the collecting surface is preferably not higher than the speed of the drawn off yarn. Before reaching the yarn formation line located on the collecting surface, the fibrous veil is divided into a plurality of fiber accumulations and thereby pre-twisted to strands. The position and travelling direction of the strands on the collecting surface is defined by guiding edges of suction slits. The individual strands are guided off transversely to the yarn formation line, whereby the extent of the pre-twist and the extent of the transport force is determined by the angle of the strands to the yarn formation line. Pre-twisted strands are wound around each other along the yarn formation line so that a type of ply-twisted yarn arises.

Abstract: In a process for open-end spinning at least one sliver is opened to single fibers, which form a fiber veil. The single fibers are fed to a rotating collecting surface which is driven transversely to their travel direction, and are withdrawn from the collecting surface in the form of a yarn with twist along a yarn formation line before the completion of one single revolution of the collecting surface. The single fibers are never slowed down at any point in the sliver-to-yarn process. Immediately after their separation from the sliver, the single fibers are subjected to an exactly predetermined, mechanically controlled speed.

Abstract: Core/wrap yarn is produced by continuously forming air jet-spun yarn and uninterruptedly continuously passing it to a friction spinner for purposes of wrapping the air jet-spun yarn with fibrous material in the friction spinner, so as to form core/wrap yarn.

Abstract: In the case of an open-end spinning machine, a suction roller is provided which serves to transport a fiber veil, expanding transversely to the circumferential direction of the suction roller, to a yarn formation line. The length of the transport path and the width of the fiber veil are determined by defining edges of a suction insert located inside the suction roller. At least one of the defining edges extends at least along a section of the transport path at an acute angle to the circumferential direction. Thus the fiber veil is widened in comparison to the sliver-shaped fed fiber material and/or the fiber tip at the beginning of the yarn formation line is shortened.

Abstract: In a process in open-end spinning at least one sliver is opened into single fibers. A transfer surface, rotating at a higher speed than the opened single fibers, takes up same already in the opening area. The single fibers are taken along transversely to the rotational direction in the form of an expanded fiber veil. Before completion of one revolution of the transfer surface, the single fibers are transferred to a yarn forming line of a twist device, which, for example, comprises a friction roller pair, and are withdrawn, under the action of an imparted twist, along the yarn forming line thus forming a yarn. The yarn withdrawal takes place hereby transversely to the rotational direction of the transfer surface. The withdrawal speed corresponds at least to the speed of the single fibers as they arrive at the yarn forming line.

Abstract: In a process in open-end spinning at least one sliver is opened into single fibers. A collecting surface, rotating at a higher speed than the opened single fibers takes up these as soon as they have left the opening area. The single fibers are taken along by the collecting surface while being expanded transversely to the rotational direction of the collecting surface in the form of a fiber veil. Before the completion of one revolution of the collecting surface, the single fibers are withdrawn from the collecting surface along a collecting line under an imparted twist thus forming a yarn, namely transversely to the direction of rotation of the collecting surface. The withdrawal speed corresponds hereby at least to the arrival speed of the single fibers at the collecting line.

Abstract: Disclosed herein is process method and articles of plated coating having functions ranging from wear resistance, lubricity, corrosion resistance, and further incorporating therein particulate matter having light emitting properties. Having this codeposited light emitting particles within the functional layer provides a signal for the determination of the presence of the coating and its stage of deterioration.

Abstract: A method and apparatus for spinning fibres into yarn including providing a supply of fibres, providing a yarn-building region, opening fibres from the supply into the region, landing opened fibres in said region, removing energy from landing fibres, building and twisting the fibres landed in the region into a yarn and withdrawing the yarn from the region. The fibres may be landed leading-end first in said region. The fibre trailing-end may be flicked to remove energy from the landing fibre.

Abstract: A rubber article having a fiber reinforcement embedded therein. The reinforcement comprises a cylindrically braided cord of an even number of twisted yarns of four or more, an equal number having an twist, i.e. twisted to the right, and a Z-twist, i.e. twisted to the left. The angle difference between a first twisting angle of a yarn and a final twisting angle of the cylindrically braided cord is set at less than 10.degree..

Abstract: The present invention relates to a spinning process and device for the production of yarn. Fibers are conveyed through a feeding channel from an opening roller and deposited onto a perforated collection surface, such as a perforated roll or disk, which is subjected to suction in at least one zone. The fibers are oriented on the collection surface along a main sense of orientation of the perforations. The fibers are conveyed through the suction zone and formed into a fiber accumulation along a collection line. A suction insert is included generally beneath the perforated collection surface and defines the suction zone and collection line for the fibers. The fibers forming into a fiber accumulation along the collection line are pre-twisted along the collection line. A separate twisting element independent from the collection surface is provided downstream from the collection surface and provides a final pre-twist to yarn drawn off of the collection surface.

Abstract: A preformed yarn useful for forming composite articles is disclosed which includes a core of a multiplicity of fibers, fine powder provided in the interstices between the fibers, and a flexible sleeve formed of a thermoplastic resin and surrounding the core. The fine powder is formed of a material which neither melts nor reacts with the thermoplastic resin at a temperature up to 450.degree. C. and at a temperature up to the melting point of the thermoplastic resin. The incorporation of the fine powder between the fibers is effected by injecting fine powder-containing air from a jet nozzle and blowing the air against a bundle of the fibers.

Abstract: The corespun yarn is formed on a friction spinning apparatus and comprises three components, including a core of high temperature resistant fibers, a core wrapper of low temperature resistant fibers surrounding and covering the core, and an outer sheath of low temperature resistant fibers surrounding and covering the core wrapper and the core. The high temperature resistant fibers of the core are selected from the group consisting essentially of aramid fibers (Kevlar and Nomex), and polybenzimidazole fibers (PBI). The low temperature resistant fibers of the core wrapper and the outer sheath are either natural or synthetic fibers, such a cotton and polyester.

Abstract: A friction spinning machine comprising a perforated roller (6) and an imperforate roller (19) is so designed that high-quality yarn can be produced in various sizes and with adequate strengths at a relatively high rate of output. The adjustment parameters necessary to solve this problem are specified in detail, more particulary those determining the position, orientation and shape of the fibre feed duct (5).

Abstract: For performing a start spinning operation in a friction spinning apparatus, upon starting or recommencing spinning of a yarn after yarn breakage, there are accomplished the following steps: fibers opened in a fiber sliver opening device are delivered by a fiber infeed duct to a rotating friction spinning drum and twisted into a twisted fiber structure or coil. When the coil has reached a substantially predeterminate diameter it is entrained by an air jet delivered by a blowing duct into a yarn entraining nozzle which deflects the coil and the yarn following the coil, before they reach the rotating yarn drawn-off rolls, axially of the yarn draw-off rolls, into a yarn guide duct. A suction device is located at the outlet of the yarn guide duct such that a negative pressure is produced therein for taking up the air from an injector part of the yarn entraining nozzle and the coil and the yarn following the coil and supplying such to the suction device.

Abstract: The wall of the friction spinning element has bores or holes with a predeterminate bore diameter and a coating on their side facing a fiber feed duct, the coating extending over the bore edges into the bores. Each bore or hole thus formed has a diameter at the bore or hole entrance or inlet which is smaller than the bore diameter of the related bore or hole. Each bore or hole has a cross-sectional area of less than 0.283 mm.sup.2, but amounting to at least 0.07 mm.sup.2. In this way, the undesirable penetration of fibers or fiber parts into the bores or holes is prevented as far as possible when air flows through the bores or holes at the side of the coating, while retaining a hole form or configuration which is favorable from the standpoint of airflow and blockage of the bores or holes.

Abstract: A friction spinning unit of a multi-position friction spinning machine includes a pressure tapping in the suction line to a suction port in the fibre feed duct. A suction transducer responsive to the suction in the tapping controls the fibre feed clutch of that particular friction spinning unit for disengaging the friction spinning unit when suction value sensed by the transducer deviates from a predetermined range of acceptable suction values, to shut-down the friction spinning unit well before the yarn quality has been impaired to a sufficient extent to cause a yarn break.

Abstract: The present friction spinning apparatus includes a draw frame section with an entrance trumpet including first and second fiber sliver guiding passageways for forming a three component corespun yarn. One of the guiding passageways directs a core roving into the draw frame section while the other sliver guiding passageway directs a core wrapper sliver into the draw frame section so that the core wrapper fibers surround the core fibers. Wrapping fibers are then wound about the core and core wrapper fibers in an elongated throat extending between a pair of rotating suction drums.

Abstract: A suction insert assembly is disclosed for a suction roller of an open spinning unit having a pair of rotatably driven friction rollers defining a yarn forming wedge-shaped gap or slot therebetween.To accommodate ease of manufacture and provide variable adjustment of the suction effect at the wedge slot, the suction insert assembly for at least one of the friction rollers includes a pipe fitted to the machine frame, and an intermediate piece filling out the space between the pipe and the perforated friction roller shell. The pipe is connected to a vacuum line and has a pipe slot communicating with an intermediate slot of the intermediate piece. The pipe rotatably supports the perforated shell by roller bearings located near the pipe ends.

Abstract: In order to start or recommence spinning of a yarn in a friction spinning apparatus, in the course of starting of spinning or piecing after a yarn break, by means of a fiber transport duct, fibers separated by an opening device, are delivered to a rotating friction spinning drum and twisted to form a twisted fiber structure. When the twisted fiber structure has reached a substantially predetermined diameter, the twisted fiber structure is moved by an airstream delivered from a pressure air infeed channel towards and into a guide tube and from that location, into the convergent space of rotating withdrawal rolls. The twisted fiber structure is entrained at production speed by these withdrawal rolls and is delivered to the diverging or outlet side of the withdrawal rolls to a suction device placed in readiness. This suction device can transfer the formed yarn following the twisted fiber structure to the succeeding or downstream elements provided for further processing.

Abstract: The method of, and apparatus for, producing a yarn uses a friction spinning device comprising a perforated first friction spinning drum and a second friction spinning drum which can also be perforated. Two fiber feed passages project to the first friction spinning drum and are each supplied by opening assemblies which individualize or individually separate the fibers. The fibers are transported toward the first friction spinning drum using a feed air stream in the fiber feed passages. This feed air stream is produced by the first friction spinning drum which is maintained under sub-pressure. Advantageously, the fiber double-feed to the friction spinning drum permits supplying two different fiber types to the same yarn end. Also, different inclinations of the fibers at the friction spinning drum can be obtained by different inclinations of the fiber feed passages in order to produce yarns of different character.

Abstract: Slubs are removed from an open-end spinning chamber by the application of suction to a debris-extraction duct by a valve opened to a suction line as the chamber is opened to a suction line as the chamber is opened for cleaning.

Abstract: In the manufacture of friction spinning drums, in order to be able to select the size of the holes or perforations, on the one hand, to oppose technological fiber loss and jamming of sucked in foreign particles and, on the other hand, to provide airflow advantages, it is proposed to manufacture the friction spinning drum from a thick-walled support and a thin-walled perforated body. As a result, holes or perforations having a sufficiently small cross-section to counteract the above-mentioned fiber loss can be formed in the thin-walled perforated body. On the other hand, holes or perforations having a large enough cross-section to prevent jamming of sucked in foreign particles or other contaminants can be provided in the thick-walled support.

Abstract: An open-end spinning machine is provided which includes a cleaning element movable between two rows of adjacently aligned spinning units. The cleaning device sucks away and removes impurities from a stationary collecting device associated with impurity separation openings in opening devices of the spinning units. The cleaning device includes at least one suction element that extends into the stationary collecting element for drawing the impurities into the cleaning device.

Abstract: A false-twist spinning unit or apparatus comprises a first spinning disc, such as a top spinning disc and a second spinning disc, such as a bottom spinning disc rotating in opposite directions and arranged in staggered or offset relation at an inter-axis distance from one another such that friction rings thereof form a substantially rhomboid-like crossing surface. Disposed outside the friction rings are suction surfaces which engage the fibers of a sliver delivered from a nip line of an exit roll pair of a sliver feeder and convey such fibers to a yarn core line. The suction surfaces have suction apertures and sucked-off air is transported by suction nozzles coacting with the suction apertures. In operation, at the region of the nip line there is produced a false-twisted yarn core forming a spinning triangle.

Abstract: A method and apparatus of forming a fibre assembly to be spun to form a yarn. The separated fibres are entrained in an air stream (61) and delivered in a tangential direction into a converging annular passage (64). The fibres are straightened in their travel through the passage (64) and issue as a peripheral curtain into a fibre collection zone (67), where the fibres merge to form a coaxial fiber assembly with the passage (64), and are shed from the airstream which is diverted to be withdrawn rearwardly from the fibre collection zone (67). The cohered fibre assembly is withdrawn forwardly from the collection zone to be spun to form a yarn.

Abstract: To control the yarn quality of a yarn produced by a textile machine, for instance a friction spinning apparatus, there is provided at the end of the friction spinning operation, however, forwardly of the pair of withdrawal rolls for the outfeed of the produced yarn, a yarn tension measuring device. Upon deviating from or falling outside of a predeterminate yarn tension tolerance value or range the yarn tension measuring device controls operation of the friction spinning apparatus such that, as required, there is accomplished an appropriate increase or decrease of the yarn tension of the yarn produced by the friction spinning apparatus. Alteration of the yarn tension can be acheived, for instance, by acting upon the drive for one of the friction spinning elements, to control the rotational speed thereof, or by selectively positioning the suction nozzle of a friction spinning element, or by controlling the size of the nip between coacting friction spinning elements, or selected combinations of such measures.

Abstract: In order to piece to an open-end friction spinning device with two friction spinning elements driven in the same direction and forming a nip subjected to suction, fibers fed into such nip are twisted into a fiber bundle. The fiber bundle is partially conveyed out of the nip in a longitudinal direction, grasped there, and then transferred to a winding device. An auxiliary conveying device is provided to convey the fiber bundle from a thread forming zone adjacent the spinning element nip up to the draw-off side end of such friction spinning elements. A grabber is provided to grasp the fiber bundle as it leaves such nip of the friction spinning elements and to transfer the forming thread to a draw-off device.

Abstract: To piece up to a spinning station consisting of two friction spinning elements (101) driven in the same direction and forming a nip, a thread 30 is conveyed to the nip so that said thread 30 reaches the thread forming zone (104) with its free thread end first. Feeding of the fibers into the nip is controlled so that the thread end (300) comes into contact with the fibers simultaneously with its reaching the thread forming zone (104). The friction spinning elements (101) are covered by a cover (130) which incorporates a fiber feeding channel (24). The cover, in addition to the fiber feeding channel (24), is equipped with a thread insertion slit (14) extending essentially in the longitudinal direction of the friction spinning elements (101). The thread insertion slit (14) extends from the outside of the cover (130) up to its inside, and from the end on the draw-off side up to the outlet end (240) on the side away from the drawoff.

Abstract: A friction spinning apparatus includes first and second perforated drums forming a spinning wedge therebetween with a spinning zone. The drums are driven in the same direction with the first drum having a greater circumferential speed than the second drum and with the first drum rotating into the spinning wedge and the second drum rotating out of the spinning wedge. The drums define an imaginary line at a location at which the drums are closest to each other. First and second suction devices are disposed in the interior of the first and second drums. The suction devices each have an intake slit formed therein. The intake slits follow paths diverging from each another and from the imaginary line at least at forward ends thereof. The intake slits are directed against the spinning wedge and each discharge in the vicinity of the inner surface of a respective one of the drums.

Abstract: A friction spinning apparatus includes two drums being driven in the same direction and defining a wedge-shaped gap therebetween with a spinning region. A suction device is disposed in at least one of the drums and directed against the wedge-shaped gap. A yarn draw-off apparatus draws off yarn produced in the wedge-shaped gap. A fiber supply device is provided with a fiber guide channel. The fiber guide channel has one side with a slit-like fiber dispersion opening formed therein and disposed in the wedge-shaped gap and another side facing away from the fiber dispersion opening. A variable ventilation opening is formed in the other side of the fiber guide channel for varying fiber mass distribution in the spinning region.

Abstract: A friction spinning unit employs two rotatable bodies to define the spinning gap, at least one of the bodies being in the form of a cone whose surface moves towards the friction spinning gap from the same side as that from which separated fibres are fed by a fibre feed means. This configuration of the bodies generates a self-conveying action which propels the bundle of fibres axially along the friction spinning gap so that the bundle itself enters twist-blocking means which facilitates the piecing action and dispenses with the need for a seed yarn to be returned to the friction spinning gap to piece up after a yarn break or after shutdown.

Abstract: An open-end friction spinning machine is provided having a plurality of spinning units arranged next to one another. A suction device assigned to each spinning unit which acts in the area of the yarn formation zone may be selectively switched off such as in the case of a yarn breakage. So that the air throughput balance does not change in the area of the other spinning units when the suction device of a single unit is switched off, devices are provided for maintaining the air throughput relatively constant. Air throughput normally used by the suction devices in the yarn forming area of the spinning unit is diverted, for cleaning and maintenance purposes.

Abstract: A process for operating an open-end friction spinning machine is provided in which the spinning units each have at least two friction areas that form a yarn-forming region. At least a part of the friction effect is determined separately for each friction surface. The friction effect is compared between such friction surfaces. A corresponding open-end friction spinning machine apparatus is also provided.

Abstract: In a method and an apparatus for producing a yarn by means of friction spinning drums, a fiber sliver is transformed into a body of fibers and transferred to a first perforated friction spinning drum of such friction spinning drums. At this first perforated friction spinning drum, the fibers are entrained by a suction air stream, produced by a suction passage located in the first perforated friction spinning drum, and are then fed into a converging space formed by and between the friction spinning drums. In this converging space the fibers are twisted into a spun yarn. The spun yarn is withdrawn by withdrawal rollers located near end faces of the friction spinning drums. The suction air stream required for entraining or catching the fibers is limited by walls forming the suction passage. The advantage of this apparatus is that the fibers are mechanically guided over the whole length of their travel path, i.e. from the body of fibers to the twisted yarn. As a result, the fibers never swim freely.

Abstract: An apparatus for making a yarn (6) comprises two juxtaposed, closely spaced apart twisting drums (1, 2), which rotate in the same sense and between themselves define a generally triangular twisting space (4), to which a vacuum is applied, fiber-feeding means and withdrawing means (7) for withdrawing the yarn (6) which has been formed in that the fibers fed to said twisting space have been twisted together in said twisting space.

Abstract: Open end friction spinning apparatus is provided in which there are one or more spinning units with respectively two adjacently arranged rollers, rotating in the same direction, and disposed to form a wedge-shaped slot therebetween for accepting fibers and spinning them into a thread of yarn by means of a friction effect. Devices are provided for monitoring the friction effect and adjusting the friction effect when necessary in order to maintain uniform spinning conditions at the individual spinning units and thereby control the quality of yarn produced.

Abstract: The method of, and apparatus for, producing a yarn uses a friction spinning device comprising a perforated first friction spinning drum and a second friction spinning drum which can also be perforated. Two fiber feed passages project to the first friction spinning drum and are each supplied by opening assemblies which individualize or individually separate the fibers. The fibers are transported toward the first friction spinning drum using a feed air stream in the fiber feed passages. This feed air stream is produced by the first friction spinning drum which is maintained under sub-pressure. Advantageously, the fiber double-feed to the friction spinning drum permits supplying two different fiber types to the same yarn end. Also, different inclinations of the fibers at the friction spinning drum can be obtained by different inclinations of the fiber feed passages in order to produce yarns of different character.

Abstract: A friction surface construction for open-end friction spinning of the type having a movable friction spinning member with yarn forming surface portions that imparts friction to fibers and to forming yarn is provided. The yarn forming surface portions include first surface areas surrounding air passage openings in the friction spinning member. Second surface areas are provided in between the first surface areas. At least a portion of the first surface areas include a section having a coefficient of friction value different than a coefficient of friction value of the second surface areas. A process for forming the friction surface construction is also provided.

Abstract: In an open-end spinning process, fibers are twisted together into a yarn, alongside a suction slit, in a spinning nip formed by two friction rollers, in close proximity of each other and driven in the same direction, and subsequently drawn off therefrom. The length of the suction orifice of the suction slit is varied, before beginning the spinning process, in accordance with the thickness of the yarn to be produced. The spinning process is then started after such adjustments are made. Practice of the invention improves quality of the yarn, and saves power consumption and other resources by reducing required air consumption.

Abstract: An open-end friction spinning arrangement is disclosed with two adjacently arranged rollers driven in the same rotational direction in forming a wedge-shaped year forming gap with their cover surfaces. It is provided that a suction device generates an air current directed into the wedge-shaped gap. This suction device creates differential suction forces at different zones of the wedge-shaped gap. The suction device includes different length suction slots in the respective friction rollers. An air inlet device having varying cross-sections along the length of the yarn forming gap is provided to optimize the effect of the slots and the air inlet opening in the forming yarn.

Abstract: An open-end spinning machine includes a low inertia sensing wheel frictionally engaging the package so that the rate of rotation of the frictional sensing wheel is sensed by a tachometer generator to provide a "winding rate" signal fed to a controller for controlling the speed of a stepper motor driving the fibre feed roller of the fibre opening unit during piecing, in response to the take-up of yarn at the package. Optionally, the sensing wheel is supported on a link such that the angular position of the link indicative of the diameter of the package is sensed by an angular position transducer and the signal of the transducer is also fed to the controller.Yarn delivery rolls are separated, during piecing, to allow the rate of withdrawal of the yarn from the doffing tube of the open-end spinning unit in response solely to the accelerating package.The draft is non-linear during piecing, in accordance with a predetermined programme.