WO2025104160A1 - Tufting unit for a tufting machine and method for inserting yarn portions into a substrate - Google Patents

Abstract

The invention relates to a tufting unit for a tufting machine, wherein the tufting unit has a yarn supply device, a plurality of insert elements, a yarn transfer gripper, a cutting unit and a yarn holding unit. The yarn holding unit is designed to independently hold the allocated yarn strand or yarn portion under every insert element. The invention also relates to a corresponding method for inserting yarn portions.

Description

Taffeta unit for a taffeta machine and method for inserting yarn sections into a substrate

The invention relates to a taffeta unit for a taffeta machine and a method for inserting yarn sections into a substrate.

Taffeta machines are typically used to insert yarn sections into a subsurface. In particular, this can be used to create artificial turf or to reinforce natural turf with yarn sections. The yarn sections are typically inserted so that they are partially embedded in the subsurface and partially protrude from it. In particular, each yarn section can have an at least substantially U-shaped form. Taffeta machines typically have taffeta units for this purpose, of which various shapes are known.

It is an object of the invention to provide a taffeta unit that is alternatively or better designed than known designs, for example, can use shorter yarn sections. It is also an object to provide a corresponding method. This is achieved according to the invention by a taffeta unit and a method according to the respective independent claims. Advantageous embodiments are claimed in the dependent claims. The invention relates to a taffeta unit for a taffeta machine. The taffeta unit has a yarn feed device for the simultaneous and parallel feeding of multiple yarn strands. The taffeta unit has multiple insertion elements. The taffeta unit has a yarn transport gripper, which is designed to transport a respective free end of the yarn strands away from the yarn feed device, so that each insertion element is assigned a respective yarn strand. The taffeta unit has a cutting unit, which is designed to cut the yarn strands, so that from each yarn strand assigned to an insertion element, a yarn section remains, assigned to the respective insertion element. The taffeta unit advantageously has a yarn holding device, which is designed to independently hold the associated yarn strand or yarn section beneath each insertion element. Each insertion element is advantageously designed to insert the respectively assigned yarn section into a substrate located beneath the taffeta unit.

Using such a taffeta unit, yarn sections can be independently held by the yarn holding unit. This means that a holding option for yarn sections exists, which can be positioned above the ground, preventing the respective yarn section from falling. During preparation for insertion, the yarn section can thus have its lowest point at a height significantly higher than that achievable with designs without a yarn holding unit. This allows for the use of shorter yarn sections overall compared to conventional designs.

A taffeta unit is understood to be a unit that can be used in a taffeta machine and is particularly designed to insert one or more yarn sections into a substrate simultaneously. The substrate is typically an artificial turf surface or a natural turf surface. In particular, the substrate can be formed essentially of earth, or an artificial filling material for artificial turf can be used. The yarn feed device can be designed in particular to actively feed the yarn strands, i.e., for example, to ensure a certain advancement of the yarn strands. This can, for example, take place simultaneously with the yarn strands being unwound from respective spools. For example, the yarn feed device can have a plurality of gripping elements, which can, in particular, be rotatably mounted. The yarn strands can be advanced by rotation. When the yarn transport gripper transports a free end of the yarn strands away from the yarn feed device, the yarn feed device is typically switched in such a way that the yarn strands can pass through freely. This allows the yarn transport gripper to pull the yarn strands away from the yarn feed device and thus typically also ensures unwinding of the respective spools. The insertion elements are typically designed as vertically movable taffeta needles. These can typically grip a yarn section from above and insert it downwards in a targeted manner. The cutting unit can be designed, for example, as a movable knife or as a combination of several movable knives. It can also have, for example, one or more rotating cutting discs, which can be movable in one or two dimensions for cutting. The yarn holding unit serves in particular to prevent yarn strands or yarn sections from falling. They can thus be held at a height above the ground which would not be possible without a yarn holding unit. Overall, this allows the use of significantly shorter yarn strands compared to designs known from the prior art.

The yarn holding unit can, in particular, have an actuatable first gripper designed to hold the yarn strands or yarn sections at a location between the insertion elements and the yarn feed device. Such a first gripper can, in particular, prevent them from falling at this location. It can, in particular, be designed to immobilize the yarn strands or yarn sections. In this case, neither movement of the respective yarn strand in its longitudinal direction nor in a plane transverse thereto is possible, in particular at the location predetermined by the first gripper. This allows the respective yarn strand to be completely held and secured.

The taffeta unit can, in particular, have an actuating unit, which can, in particular, be designed to initially close the first gripper during a vertical downward movement of the insertion elements and then open it when the yarn sections on both sides of the respective insertion element are of equal length. This makes it easy to ensure that the yarn sections on both sides of the insertion element are of equal length, resulting in a uniform formation of an artificial turf or a reinforced natural turf. In particular, the parts on both sides of the taffeta unit are then inserted in such a way that they protrude upwards from the ground by the same length.

The yarn holding unit can in particular have an actuatable second gripper which is designed to hold the yarn sections at a location which is located on a side of the insertion elements opposite the yarn feed device. This can also specifically prevent the yarn sections from falling down at this location. The second gripper can in particular hold the yarn sections in such a way that they remain movable along their longitudinal direction by the second gripper. This makes it possible for the yarn sections to be prevented from falling down, but to be movable along the longitudinal direction by the second gripper and thus, during an insertion process, to withstand the vertically downward directed movement of an insertion element can meet the increased demand for length adjacent to the insertion element. This is especially true in connection with the fact that the first gripper holds the yarn sections completely immobile, as already described above.

The taffeta unit can, in particular, have an actuating unit, which can, in particular, be designed to initially open the second gripper during a vertical downward movement of the yarn holding unit and then close it when the second gripper engages with the yarn sections. This allows the yarn sections to be initially held above the first gripper and can be displaced further downward by the vertical movement of the yarn holding unit. As soon as they engage with the second gripper, the latter can close, thus realizing the holding effect.

The yarn holding unit can, in particular, be designed to hold the yarn strands or yarn sections vertically spaced from other components of the taffeta unit arranged vertically below. In particular, such a component can be a taffeta plate, which typically has several holes formed therein, through which the insertion elements insert the yarn sections into the substrate. The yarn holding unit ensures that the yarn sections do not fall off, which, as already mentioned, offers the possibility of using shorter yarn sections.

The yarn holding unit can, in particular, be designed to be vertically movable. This can be seen particularly relative to the rest of the taffeta unit. Such vertical mobility allows the yarn holding unit to at least partially follow a downward movement of the insertion elements, thus ensuring improved guidance.

In particular, the taffeta unit can have a drive unit, which can be configured, in particular, to partially move the yarn holding unit downwards during a vertical downward movement of the insertion elements. This can achieve better guidance of the yarn sections during the insertion movement. In particular, a movement of the yarn holding unit can mean a movement of the aforementioned grippers of the yarn holding unit.

In particular, the taffeta unit can have a taffeta plate on the underside. In this plate, at least one opening, preferably several openings, can be formed for guiding the respective yarn section during insertion, wherein the actuating unit can be designed to move the yarn holding unit downwards to the taffeta plate. Guiding the yarn sections through the yarn holding unit down to the taffeta plate.

The taffeta unit can be designed, in particular, to insert yarn sections with a maximum length of 24 cm. This corresponds to a shorter length than is typically possible with known designs. In particular, the corresponding dimensions of the taffeta unit can be suitable for such a length.

The invention further relates to a method for inserting yarn sections into a substrate, the method comprising the following steps:

Feeding several parallel yarn strands by means of a yarn feeding device, transporting the yarn strands under respective insertion elements by means of a yarn transport gripper,

Holding the yarn strands under the insertion elements by means of a yarn holding unit, cutting the yarn strands so that from each yarn strand assigned to an insertion element, a yarn section remains assigned to the respective insertion element, and

Inserting the yarn sections into the substrate using the insertion elements.

This advantageously allows for an insertion process, particularly with shorter yarn sections than is possible with prior art designs. Regarding the individual features, reference is made to the description provided above.

A yarn section is understood to mean, in particular, a part of a yarn strand after it has been cut.

Before cutting and at least partially during insertion, the yarn strands, in particular, can be held immobile at a location between insertion elements and yarn feed devices. This corresponds to the functionality of the first gripper described above. Reference is made to the above explanations.

During insertion, the yarn strands can be held immobile, particularly at the point between the insertion elements and the yarn feed device, only until the yarn strands are the same length on both sides of the insertion elements. This allows for simple length control. In particular, during insertion, the yarn sections can be held at a location on a side of the insertion elements opposite the yarn feed device such that they are movable along their longitudinal axis. This corresponds to the functionality of the second gripper already described above. Reference is made to the above explanations.

The method can be carried out, in particular, using a taffeta unit as described herein. With regard to the taffeta unit, all embodiments and variants described herein can be used. All aspects described with reference to the taffeta unit are also applicable to the method. All aspects described with reference to the method are also applicable to the taffeta unit.

The first gripper can, in particular, be designed as a double gripper. This can ensure the desired complete holding effect, especially with smooth or slippery threads. The double gripper design can, in particular, mean that two holding elements with the same or similar functions are used simultaneously.

In particular, after the insertion elements have been raised, the yarn transport gripper can pivot underneath the insertion elements towards the yarn feed device, where yarn strands are held ready. The yarn transport gripper can then pivot back and unwind the yarn strands, in particular from a respective spool. In particular, the yarn holding unit can be arranged so that the yarn strand is only placed in the first gripper, whereas the second gripper initially remains empty. The yarn holding unit can then be moved slightly downwards until the respective yarn strand is also placed in the second gripper. The grippers can then be closed. In the first gripper, the yarn strand is completely fixed. In the second gripper, the yarn strand is held in a sliding manner. The cutting device pivots in and cuts off the yarn strands, leaving yarn sections. The yarn holding unit can then move further downwards, whereby the respective yarn strand end present on the second gripper can slide into the second gripper. This ensures that the yarn strand or yarn section lies in a V-shape in front of the respective insertion element, with the sections or ends being the same length on both sides, or on the right and left. Sensors such as rotary encoders can detect the position of all moving components, such as the yarn transport gripper, yarn feed device, cutting unit, and yarn holding device, so that a control system always knows which component is located where.

A taffeta unit can be the part of a taffeta machine that is specifically responsible for the provision and insertion of yarn sections. For example, this may correspond to the functionality described herein. A taffeta machine typically includes such a taffeta unit and has, for example, additional components such as a chassis, drive, clutch, control, and/or other supporting systems. Furthermore, a taffeta machine typically also has means for storing yarns, which can then be used by means of the taffeta unit.

Parallel feeding can be understood, for example, as meaning that the yarn strands run parallel to one another. Simultaneous feeding can be understood, in particular, as meaning that the yarn strands, especially parallel yarn strands, are moved in the same direction. This has proven particularly advantageous, especially when a large number of yarn strands are to be processed simultaneously, in order to shorten the required processing time.

An insertion element can be understood, in particular, as the element that ensures that yarn sections are inserted into the substrate. This can be, for example, a taffeta needle, as will be described in more detail below. In particular, it can be provided that as many insertion elements as yarn strands are used, so that each yarn strand is assigned a respective insertion element that inserts yarn sections of the respective yarn strand into the substrate.

A yarn strand associated with a respective insertion element can, for example, be arranged beneath this insertion element. This allows for easy insertion into the substrate. This particularly means that the lowest point of the respective yarn strand is located directly beneath the insertion element. Other parts of the yarn strand can, in particular, protrude upwards, for example, in a V-shape.

The yarn feed device can, in particular, have a plurality of rotating yarn holders. Typically, each yarn holder can hold and release the yarn strands. A rotating arrangement can ensure particularly simple operation, since rotation about an axis is sufficient for advancement. The yarn holders can, for example, be designed to interact in pairs, so that each yarn strand is held by two yarn holders of a pair before being cut. This makes it possible to define a certain section in the yarn strands that lies between two yarn holders that interact in pairs. For example, the yarn strands can be cut between the yarn holders of a respective pair.

According to one possible embodiment, the yarn feed device has three pairs of yarn holders. According to another possible embodiment, the yarn feed device has four Pairs of yarn holders. Such designs have proven advantageous because three or four pairs of yarn holders ensure continuous operation and are easy to handle. However, any other number of pairs of yarn holders can, in principle, be used. It should also be noted that the yarn holders do not necessarily have to be grouped in pairs.

According to a preferred embodiment, the yarn transport gripper is designed to grip the free ends of the yarn strands by gripping respective end sections of the yarn strands, which are clamped between two yarn holders of a pair. By gripping the end section, the respective yarn strand can be gripped at a section where it is advantageously held. This avoids gripping errors. For example, the respective yarn strand can also be pulled further using the yarn transport gripper, whereby, for example, unwinding from a spool can also be provided.

The yarn feed device can preferably be configured to further rotate and/or advance the yarn holders before each taffeta process. For example, new end sections of the yarn strands can be provided for gripping by the yarn transport grippers.

By continuing to turn or guide the yarn strands forward in a simple manner.

Preferably, the yarn holders are arranged so that they can rotate about a common axis. This allows for particularly easy rotation of the yarn holders.

According to a preferred embodiment, each yarn holder has a first yarn holder plate and a second yarn holder plate, which are movable relative to each other for holding and releasing the yarn strands. For example, yarns can be clamped between these two yarn holder plates. Yarn holders can also use yarn holder plates together, for example, yarn holders of a pair of yarn holders.

According to a preferred embodiment, each yarn holder has at least one upper, one middle, and one lower yarn holder plate. The middle yarn holder plate is preferably displaceable by a drive, in particular a hydraulic drive, relative to the other two yarn holder plates to hold and release the yarn strands. This allows, for example, yarn strands to be clamped between the middle and upper yarn holder plates, as well as between the middle and lower yarn holder plates. These can be released again by displacement. According to a preferred embodiment, each yarn holder has at least a first, a second, a third, and a fourth yarn holder plate. Preferably, the second and fourth yarn holder plates are displaceable by a drive, in particular a hydraulic drive, against the other two yarn holder plates to hold and release the yarn strands. This allows clamping between two pairs of plates, which enables particularly reliable clamping of the yarn strands.

Preferably, at least one yarn holder plate is displaced relative to the other yarn holder plate by means of a closing cam and an opening cam, each of which is preferably movable by a drive, in particular a hydraulic drive. By means of respective opening and closing cams, it can be achieved that a respective yarn holder plate is displaced solely by movement along a path, for example along a circular path during rotation, and thereby clamps or releases yarn strands at predetermined points. This does not require any further active elements, so that clamping or releasing takes place automatically. In addition, a drive, in particular a hydraulic drive, can enable movement of the closing cam and/or the opening cam, which allows, for example, actuation independent of movement along the path. This can thus achieve, for example, that yarn strands are released at a specific time without the yarn holder plate having to be moved further.

The yarn feed device is preferably designed to release the yarn strands during transport. This can be achieved, for example, by appropriately designing opening and/or closing cams or by actuation by means of a drive. Preferably, the yarn transport gripper pulls the yarn strands through the yarn feed device during transport. In this way, a corresponding feed can be achieved by means of the yarn transport gripper. It can also be provided that the yarn transport gripper unwinds the yarn strands from respective yarn spools during transport. In this way, a respective further feed of yarn from the yarn spools provided for this purpose can be achieved by means of the yarn transport gripper. Additional elements for unwinding or for a corresponding feed can preferably be dispensed with. It should be understood, however, that alternatively or additionally, an active unwinding of yarn spools can also be provided.

According to a preferred embodiment, the taffeta unit has an input-side deflection for guiding the yarn strands upstream of the yarn feed device. This allows for reliable provision of the yarn strands upstream of the yarn feed device. According to a preferred embodiment, the cutting unit comprises a cutting blade and a counterblade, which can be displaced relative to one another to cut the yarn sections. This allows the cutting unit to be implemented in a simple manner, particularly allowing for high scalability, i.e., a large number of yarn strands can be cut simultaneously using only one cutting blade and only one counterblade. Alternatively, however, separate cutting tools can also be provided for the respective yarn strands.

Preferably, the cutting blade is displaceable relative to the counterblade by means of a drive, in particular a hydraulic cylinder. This allows for simple actuation of the cutting blade. However, other options for actuating the cutting blade are also possible.

According to a preferred embodiment, each insertion element has a taffeta needle designed to grip and insert the respective yarn section into the substrate. Using such a taffeta needle, easy insertion of the respective yarn section is possible, whereby the taffeta needle is typically arranged vertically and moves only one-dimensionally, in particular in the vertical direction. This enables a very simple design. The taffeta needle can penetrate the substrate as far as necessary and then be withdrawn again. The desired depth can also be easily adjusted. The respective taffeta needle is preferably movable vertically and/or perpendicular to the substrate. This enables a simple insertion movement. The direction indication can refer in particular to a typical installation state in a taffeta machine traveling on a surface. This also applies to other direction or position indications. In particular, it can be provided that all taffeta needles of the taffeta unit can be moved together or uniformly.

The taffeta unit preferably has a taffeta plate on the underside, in which at least one opening is formed for guiding the yarn section. Such an opening can ensure that the yarn section remains in position during insertion and is also bent over if necessary. Furthermore, guidance of the respective taffeta needle or insertion element can be achieved.

Preferably, the taffeta unit has at least one needle guide for guiding the taffeta needles or for guiding a respective taffeta needle, wherein according to a preferred embodiment, each needle guide is partially movable with the taffeta needles, preferably up to the base or up to the taffeta plate. By means of such a needle guide, the taffeta needles can be moved in a preferred The needles can be stabilized and guided in a manner that effectively prevents malfunctions and associated downtime. The needle guide can, for example, be designed to enclose each taffeta needle, for example, with only a small amount of clearance, thus preventing movement of the respective taffeta needle transverse to the respective longitudinal direction.

For example, by moving the insertion elements or the taffeta needles, sections of equal length can be created.

The yarn transport gripper can, for example, be pivotally mounted on a pivot point. This allows for easy actuation of the yarn transport gripper. For example, the actuation can be achieved by means of a movable element that acts at a point different from the pivot point. The yarn transport gripper can thus be pivoted and thus perform a merely one-dimensional movement, which is easy to implement. With such a pivoting movement, the functionality of transporting yarn strands or unwinding yarn strands from spools can be realized, for example.

The taffeta unit can, for example, have an actuatable rod for pivoting the yarn transport gripper. The rod can be actuated hydraulically or by a crank drive, for example. Using this rod and/or the associated drive, the aforementioned pivoting movement of the yarn transport gripper can be advantageously realized.

The yarn transport gripper can, in particular, comprise a transport gripper for gripping the free ends of the yarn strands. The transport gripper can, in particular, be designed to hold and release the yarn strands or their free ends in order to implement the desired function. For example, a respective yarn strand can be held for transport, while it can be released, for example, for insertion.

The transport gripper can, for example, have a first transport gripper plate and a second transport gripper plate, which can be displaced relative to each other, particularly by a hydraulic drive, to grip and release the free ends. This allows for easy clamping and release of the yarn strands.

The yarn transport gripper can, in particular, be designed to release the yarn sections during insertion. This allows free movement of the yarn sections during insertion. According to a preferred embodiment, the cutting unit can be pivotally mounted. This allows it to be moved into an appropriate position when necessary. Regarding the implementation and advantages of pivoting, reference is made to the above explanations regarding the yarn transport gripper.

The cutting unit can, for example, be designed to pivot toward the yarn strands before each cutting operation and away from the yarn strands after the cutting operation. This allows the yarn strands to move or be pulled forward independently of the cutting unit, while the cutting unit is only in the corresponding position when a cutting operation actually needs to be performed.

The taffeta unit preferably has an adjustment device for the end position of the yarn transport gripper and/or the position of the cutting device. This makes it possible, for example, to determine how far the respective yarn strands are pulled through the yarn transport gripper. It is also possible to determine the position in which the cutting device should cut the yarn strands. This allows, for example, adaptation to different intended uses, such as different insertion depths or different yarns. The respective adjustment device can be implemented mechanically, for example. It can be operated manually or electrically.

The taffeta unit preferably has a depth adjustment device for the penetration depth of the taffeta needles into the substrate. This makes it easy to set how far the taffeta needles should move downwards during insertion and thus also to determine how far individual yarn strands should be inserted into the substrate. This enables adaptation to different requirements regarding the depth at which the yarn sections should ultimately remain in the substrate. Depending on how the yarn strands are cut, it is also possible to set how far the yarn sections protrude from the substrate after the respective insertion process has been completed. The depth adjustment device can, for example, be implemented as a mechanical height adjustment. It can, for example, be operated manually or electrically.

The invention further relates to a taffeta machine for inserting yarn sections, each of which is positioned and cut off from a yarn strand by a taffeta unit according to the invention, into a substrate located beneath the taffeta unit. The taffeta machine has, in particular, a taffeta unit, which is, in particular, a taffeta unit according to the invention. All embodiments and variants described herein may be used.

In addition to the taffeta unit, the taffeta machine can, in particular, have further components such as a frame, a chassis, a drive, a coupling for attaching to a towing vehicle, a control system, an operating unit, yarn spools for storing and unwinding yarn strands, and other components. It can be provided that the yarn transport grippers each transport the end sections of the yarn held by the yarn feed device away from the yarn feed device, preferably in an alternating pivoting movement. It can also be provided that the yarn transport grippers assign each yarn strand to an insertion element and position it accordingly. After the cutting unit has cut the respective yarn sections from the respective yarn strands, the insertion element can insert the respective yarn sections into the substrate.

The invention is illustrated schematically in the drawings, particularly in exemplary embodiments. Figures 1 to 16 show a taffeta unit according to the prior art. Figures 17 to 20 show a taffeta unit according to the invention. They show:

Fig. 1 : a taffeta unit in a first state,

Fig. 2: the taffeta unit in a second state,

Fig. 3: the taffeta unit in a third state,

Fig. 4: the taffeta unit in a fourth state,

Fig. 5: the taffeta unit in a fifth state,

Fig. 6: a part of a yarn feeding device,

Fig. 7: another part of a yarn feeding device,

Fig. 8: Yarn holder of a yarn feeding device according to a first embodiment,

Fig. 9: Yarn holder of a yarn feeding device according to a second embodiment,

Fig. 10: a cross-section through parts of a yarn feeding device, Fig. 11 : an alternative embodiment of a yarn holder in a first state,

Fig. 12: the yarn holder of Fig. 11 in a second state,

Fig. 13: a transport gripper in a first state,

Fig. 14: the transport gripper of Fig. 13 in a second state,

Fig. 15: a cutting unit with actuating components,

Fig. 16: the cutting unit with actuating components of Fig. 15 with further components,

Fig. 17: a taffeta unit according to the invention,

Fig. 18: the taffeta unit of Fig. 17 in a further state,

Fig. 19: the taffeta unit of Fig. 17 in a further state, and

Fig. 20: the taffeta unit of Fig. 17 in a further state.

In the figures, identical or corresponding elements are designated by the same reference numerals and are therefore not described again unless expedient. The disclosures contained in the entire description apply mutatis mutandis to identical parts with the same reference numerals or the same component designations. Furthermore, the positional information chosen in the description, such as top, bottom, side, etc., refers to the directly described and illustrated figure and, if the position changes, is to be applied mutatis mutandis to the new position. Furthermore, individual features or combinations of features from the various embodiments shown and described can represent independent, inventive or inventive solutions in their own right.

Fig. 1 shows a taffeta unit 10 according to an embodiment of the prior art. The taffeta unit 10 is shown in Fig. 1 in a first state. The taffeta unit 10 is also shown in Figs. 2 to 5, each of which shows a different state. Overall, Figs. 1 to 5 show a typical process sequence for using the taffeta unit 10, which begins with the provision of appropriate yarn strands and ends with the insertion of yarn sections into a substrate 12. It should be understood that the The process sequence described can also be regarded as an independent aspect of the invention.

The taffeta unit 10 has a yarn feed device 20. The yarn feed device has a total of six yarn holders 22, which are grouped into three pairs of two yarn holders 22 each. Two yarn holders 22 of each pair are arranged in an approximately U-shaped configuration. The pairs are designated by the numbers 1, 2, and 3.

The yarn feed device 20 is designed to rotate about a central axis. A drive (not shown) is used for this purpose, which can be electrical or mechanical, for example. Upon such rotation of the yarn feed device 20, the yarn holders 22 rotate accordingly.

A plurality of yarn strands 30 are fed to the taffeta unit 10. These yarn strands 30 are not part of the taffeta unit 10, but are used, i.e., cut and inserted, by the taffeta unit 10. A deflection device 37, which ensures that the yarn strands 30 are fed along a predetermined curve, is used to feed the yarn strands 30.

The yarn strands 30 run parallel to each other, whereby only one yarn strand 30 is visible in the view of Fig. 1 and the other figures. The other yarn strands 30 run parallel to the visible yarn strand 30 behind the paper plane.

The yarn holders 22 are each configured to either grip or release the yarn strands 30. When the yarn strands 30 are gripped by a respective yarn holder 22, this means that the yarn strands 30 are carried along by a movement of the respective yarn holder 22, in particular during the rotation of the yarn feed device 20 already described. This allows, for example, additional yarn to be fed, which can be unwound, for example, from corresponding spools (not shown).

The taffeta unit 10 in this case has a plurality of insertion elements 40. Each insertion element 40 is designed as a taffeta needle 42. The taffeta needle 42 is, as shown, vertically aligned. It can be moved in a vertical direction, i.e., one-dimensionally, which corresponds to an up-and-down movement.

The taffeta unit 10 has as many taffeta needles 42 as it processes yarn strands 30.

Each yarn strand 30 is thus assigned a respective taffeta needle 42. Each taffeta needle 42 serves This basically involves inserting a respective yarn section into the substrate 12 under the taffeta unit 10. The exact functionality will be discussed in more detail below.

The taffeta unit 10 further includes a needle guide 44, which is arranged such that the taffeta needles 42 extend through the needle guide 44. The needle guide 44 stabilizes the taffeta needles 42. This means, in particular, that they can essentially only move according to the intended up and down movement. Temporarily breaking away and any associated malfunctions are thus reliably prevented.

The taffeta unit 10 has a yarn transport gripper 50. The yarn transport gripper 50 is pivotally mounted about a pivot point 52. To actuate the yarn transport gripper 50, the taffeta unit 10 has an actuatable rod 54, which in this case is designed to be hydraulically actuated. The actuatable rod 54 is connected to the yarn transport gripper 50 at a location different from the pivot point 52. Thus, a pivoting movement of the yarn transport gripper 50 can be induced by means of the actuatable rod 54.

The yarn transport gripper 50 has a transport gripper 56. The transport gripper 56 is designed to clamp or release the yarn strands 30. When the transport gripper 56 clamps the yarn strands 30, they can be transported and, for example, pulled further, in particular by means of the pivoting movement just described. This can also, for example, induce the yarn strands 30 to unwind from the respective spools. The exact functionality will be discussed in more detail below.

The taffeta unit 10 has a cutting unit 60. As shown, the cutting unit 60 is also designed to be pivotable, specifically about a pivot axis 62. The cutting unit 60 is designed to cut the yarn strands 30. This can occur, in particular, in a state illustrated in Fig. 3. The yarn strands 30 run through the cutting unit 60 as shown, which is why the cutting unit 60 can easily cut them. This will be discussed in more detail below. For further method steps, the cutting unit 60 can then be pivoted so that the yarn strands 30 can be transported independently of the cutting unit 60 or can assume corresponding positions in space.

Below the needle guide 44, the taffeta unit 10 has a taffeta plate 70. In this plate, respective openings 75 are formed. Each taffeta needle 42 is assigned a respective opening 75, wherein the respective taffeta needle 42 passes through the respective opening 75 when the the respective taffeta needle 42 is moved downwards. This will be discussed in more detail below.

By means of the taffeta plate 70, the taffeta needles 42 can be additionally stabilized shortly before insertion into the substrate 12. This reliably prevents lateral breakage or other malfunctions.

Fig. 2 shows the taffeta unit 10 in a state in which process steps have been carried out starting from the state shown in Fig. 1.

In particular, the yarn transport gripper 50 was pivoted to the right, which occurred by extending the actuatable rod 54. As a result of this pivoting movement, the transport gripper 56 now engages the yarn strands 30, specifically at a point between two paired yarn holders 22. The transport gripper 56 can then grip the yarn strands 30, which can be done in particular by sliding a first transport gripper plate against a second transport gripper plate, wherein the yarn strands 30 can typically be clamped between the two transport gripper plates. However, more than two transport gripper plates can also be used, for example, which can be at least partially shifted against one another.

It should be understood that the pivot point 52 in the figures appears to be located only coincidentally above the taffeta needles 42. There is no mechanical connection here.

Fig. 3 shows the taffeta unit 10 in a further state after a further method step, which in particular consists in pivoting the yarn transport gripper 50 to the left. As already mentioned, the yarn strands 30 were previously gripped by the transport gripper 56. The yarn strands 30 are then released from the yarn holders 22 so that the yarn transport gripper 50 can pull the yarn strands 30 from spools (not shown). The yarn strands 30 are now located at least partially below the needle guide 44. A yarn strand 30 is now assigned to each taffeta needle 42 in such a way that a yarn strand 30 is located below the respective taffeta needle 42. On the left side, the yarn strands 30 are now held by the yarn transport gripper 50. On the right side, they are held by the yarn feed device 20.

To achieve the state shown in Fig. 3, the yarn strands 30 were pulled by the yarn transport gripper 50 through a pivoting movement under the respectively assigned taffeta needle 42, so that the yarn strands 30 are now 56 and lie directly below a respective associated taffeta needle 42 on the needle guide 44.

Fig. 4 shows the taffeta unit 10 in yet another state. The taffeta needles 42 have been moved downward, and with them the needle guide 44 has also been moved downward. The needle guide 44 now borders directly on the taffeta plate 70. As shown, the respective taffeta needle 42 protrudes beyond the needle guide 44 at the bottom, so that the respective underlying yarn strand 30 is gripped and pressed downward. This leads to the tip of the yarn strand 30, which can be seen in Fig. 4 directly below the taffeta needle 42. The yarn strands 30 are pulled a little further. The yarn strands 30 are then cut by the cutting unit 60, so that the state shown in Fig. 5 can be transitioned to.

The taffeta needles 42 were moved downwards until they penetrated the substrate 12. On the right-hand side, the areas of the yarn strands 30 which pass beneath the taffeta needles 42 were cut by the cutting unit 60. On the left-hand side, the respective free ends were released by the transport gripper 56. Thus, each taffeta needle 42 is assigned a respective yarn section 35 which is no longer connected to the rest of the respective yarn strand 30. The downward movement of the respective taffeta needle 42 carries the respective yarn section 35 downwards into the substrate 12. It is inserted in such a way that part of the yarn section 35 is located in the substrate 12, but part of it protrudes upwards. Thus, the respective yarn section 35 is anchored in the substrate 12 on the one hand, but also has sections protruding upwards on the other. These can, for example, protrude 20 mm above the subsurface 12, although other values are also possible. This corresponds to a typical design of artificial turf, with the upwardly protruding sections forming the visible and perceptible part of the artificial turf.

During the transition from the state illustrated in Fig. 4 to the state illustrated in Fig. 5, the yarn feed device 20 was further rotated 120° to the left. As a result, yarn strands 30 are now again located between yarn holders 22, so that the transport gripper 56 can grasp them and pull them to the left, as already described above. The process sequence described herein can then begin again.

Fig. 6 shows part of the yarn feeding device 20.

The yarn feed device 20 is rotatable about an axis 21. The yarn feed device 20 has a shaft 23 on which the previously described yarn holders 22 are mounted. As already mentioned with reference to Fig. 1, the yarn holders 22 are arranged in pairs, namely in this case in three pairs. The yarn holders 22 are rotationally connected to the shaft 23.

A motor 84 is used to drive the shaft 23. This motor also serves as the left-hand bearing for the shaft 23. On the right-hand side, the shaft 23 is mounted in a ball bearing 88.

To the left of the motor 84 there is a timing wheel 86 and a sensor 87 arranged above it. This allows the rotation of the shaft 23 to be monitored.

Directly above the shaft 23, a part of a yarn holder 22 is schematically shown in Fig. 6. This has a movable yarn holder plate 24, which is mounted in such a way that it can be moved only one-dimensionally in a limited horizontal direction. The yarn holder 22 also has a guide wheel 26, which is rigidly connected to the movable yarn holder plate 24. Thus, a movement of the guide wheel 26 is directly transmitted to the movable yarn holder plate 24. An opening cam 80 and a closing cam 82 serve to determine the movement of the movable yarn holder plate 24. These are each designed as solid bodies.

In the state shown in Fig. 6, the guide wheel 26 rests directly against the opening cam 80. This controls the horizontal movement of the movable yarn holder plate 24, with the guide wheel 26 moving along the opening cam 80 in accordance with the previously described rotation of the yarn holder 22 around the axis 21. The design of the surface of the opening cam 80 facing the guide wheel 26 thus enables a horizontal movement of the guide wheel 26 and thus also a corresponding horizontal movement of the movable yarn holder plate 24.

As will be described in more detail below, the yarn holder 22 also has at least one fixed yarn holder plate, wherein the movable yarn holder plate 24 is movable in particular relative to this fixed yarn holder plate. Due to the design of the two plates, yarn strands can be clamped between the two plates. In particular, yarn strands can be clamped when the movable yarn holder plate 24 is in a state following a horizontal displacement to the right. If, on the other hand, the movable yarn holder plate 24 is displaced to the left, for example as just described by the opening cam 80, the yarn strands are released so that they can move freely along their respective longitudinal direction. The yarn feed device 20 further comprises a drive 90, which serves to move the opening cam 80 and the closing cam 82 in the horizontal direction. This allows opening or closing to be effected independently of the movement of the respective yarn holder 22 along the circular path. This will be described in more detail below with reference to Fig. 7.

Fig. 7 shows the yarn feed device 20 from a different view and in a different state. Regarding the components already described, reference is made to the description of Fig. 6.

The drive 90 is connected to one or more guide rods, one of which, 92, is visible in Fig. 7. The guide rods 92 are rigidly connected to the opening cam 80 and the closing cam 82, with the opening cam 80 and the closing cam 82 being mounted in such a way that they have limited horizontal movement. Thus, by moving the guide rods 92, the opening cam 80 and the closing cam 82 can also be moved in the same way.

By means of the drive 90, which can move the guide rods 92, a horizontal movement of the opening cam 80 and the closing cam 82 is thus possible. This allows, for example, the release of yarn strands independently of a movement of the respective yarn holder along the intended circular path.

It should be understood that the closing cam 82 acts on the movable yarn holder plate 24 in a similar manner to that described with reference to the opening cam 80, but in particular in the opposite direction. In particular, the closing cam 82 can cause the movable yarn holder plate 24 to be displaced to the right, so that, for example, the yarn strands can be clamped.

Fig. 8 shows the yarn feed device 20 in a sectional view from a direction transverse to that of Figs. 6 and 7. The combination of two yarn holders 22 in pairs in a respective U-shape is clearly visible. It also shows their internal structure.

Two fixed yarn holder plates 27 are installed on the outside, which are not movable and are firmly connected to the shaft 23.

The movable yarn holder plate 24 is arranged centrally between the two fixed yarn holder plates 27. As already mentioned, this is designed to be horizontally movable. The already described configuration of the yarn holder plates 24, 27, not visible in Fig. 8, allows yarn strands 30 to be clamped or released between these two yarn holder plates 24, 27. Clamping makes it possible, in particular, for the corresponding yarn strands 30 to be carried along by rotation of the yarn feed device 20.

Fig. 9 shows an alternative embodiment of the yarn feed device 20. In contrast to the previously described embodiment, not six, but a total of eight yarn holders 22 are provided, which are also arranged in pairs in a respective U-shape. Thus, a total of four pairs of yarn holders 22 are present. Otherwise, with regard to functionality and the specific embodiment, reference is made to the description above. Three of the pairs of yarn holders 22 are shown only schematically in Fig. 9.

Fig. 10 shows a plan view of the opening cam 80. It can be seen that the opening cam 80 is approximately horseshoe-shaped or U-shaped, with the previously described guide wheel 26 running on the opening cam 80 for part of its intended rotation and otherwise not running on the opening cam 80. If, for example, the guide wheel 26 is in a state in which it is not in contact with the opening cam 80, it will enable a movement of the movable yarn holder plate 24 onto the opening cam 80. Such a movement can be triggered in particular by the closing cam 82. If the guide wheel 26 comes into contact with the opening cam 80 again, the movable yarn holder plate 24 is typically pushed away from the opening cam 80.

Fig. 11 schematically shows an alternative embodiment of a yarn holder 22. Instead of just one movable yarn holder plate 24, two movable yarn holder plates 24 are provided. These are moved in a coupled manner.

The sequence from top to bottom is that first a movable yarn holder plate 24, then a fixed yarn holder plate 27, then another movable yarn holder plate 24 and then another fixed yarn holder plate 27 are provided.

Fig. 11 shows an open state, with a total of eight yarn strands 30 shown here also being drawn. These pass freely through respective recesses in the yarn holder plates 24, 27, so that they are not clamped anywhere. This means, in particular, that the yarn strands 30 can be moved freely along their respective longitudinal directions, even though they are located within the yarn holder 22. It should be noted that any other number of yarn strands can also be used. Fig. 12, in contrast, shows a state in which the movable yarn holder plates 24 have been shifted to the right. It can be seen that the yarn strands 30 have been clamped between the movable yarn holder plates 24 and the stationary yarn holder plates 27.

The design shown in Figs. 11 and 12, which is based on a total of four yarn holder plates 24, 27, has proven to be even more advantageous compared to a design with three yarn holder plates. In particular, the yarn strands 30 can be clamped even more reliably. Figs. 13 and 14 separately show the transport gripper 56 with continuous yarn strands 30. Fig. 13 shows an open state in which the yarn strands 30 are freely movable along their respective longitudinal directions. Fig. 14 shows a closed state in which the yarn strands 30 are held by the transport gripper 56.

The transport gripper 56 has a first transport gripper plate 58 and a second transport gripper plate 59. These are movable relative to one another. The yarn strands 30 can be guided between the transport gripper plates 58, 59 through respective recesses, wherein they are freely movable along their respective longitudinal direction in the state shown in Fig. 13. If the first transport gripper plate 58 is moved to the right relative to the stationary second transport gripper plate 59, the yarn strands 30 are clamped between the two transport gripper plates 58, 59. This is shown in Fig. 14. This state makes it possible, for example, to pull the yarn strands 30 to the left during the pivoting movement from right to left of the yarn transport gripper 50 described above and, for example, to unwind new yarn from the respective yarn spools. If yarn sections are to be inserted subsequently, the open state shown in Fig. 13 can be assumed again, for example.

Fig. 15 shows a sectional view through a part of the already mentioned shaft 23 and the cutting unit 60. The pivot axis 62 is also shown, about which the cutting unit 60 can be pivoted.

The cutting unit 60 has an additional ball bearing 64. A knob wheel 28 is mounted on the shaft 23 and is connected to the shaft 23 in a rotationally fixed manner. Thus, the knob wheel generally rotates with the shaft 23. Three recesses 29 are formed in the knob wheel 28, into which the additional ball bearing 64 can engage, as shown, at corresponding rotational positions of the knob wheel 28. When the additional ball bearing 64 engages in one of the recesses 29, as shown, the cutting unit 60 is in a pivoted-in position. This can be used, in particular, for a cutting process. If the shaft 23 continues to rotate, the knobbly wheel 28 also continues to rotate, thus pushing the additional ball bearing 64 outwards. This pivots the cutting unit 60 outwards so that it is spaced apart from the yarn strands 30. This allows, for example, the yarn strands 30 to be pulled further. The implementation shown in Fig. 15 ensures that the shaft 23, via the knobbly wheel 28 and the additional ball bearing 64, automatically ensures the correct pivoted position of the cutting unit 60.

Fig. 16 shows a further sectional view, wherein, in addition to the components shown in Fig. 15, the opening cam 80 can be seen. This is located in front of the cam wheel 28. As soon as a respective yarn holder 22 has gripped the yarn strands 30, the opening cam 80 can be actuated. This releases the yarn strands 30 and the yarn transport gripper 50 can pull the yarn strands 30 further. After that, in one possible embodiment, the taffeta needles 42 move downward. Subsequently, the closing cam 82 can be actuated and thus the opening cam 80 can be retracted. As the taffeta needles 42 move further down, the shaft 23 can be rotated at the same time in order to transport the yarn strands 30 to a position in which the yarn transport gripper 50 can grip the yarn strands 30 again. To enable the yarn holders 22 to pick up the yarn strands 30 again, the yarn holders 22 are opened again before passing the deflection 37. This is done by two ball bearings below the opening cam 80. When moving onto the closing cam 82, the yarn holders 22 are closed again, thus clamping the yarn strands 30.

In summary, a possible procedure can be described as follows.

Gripping yarn strands using the yarn transport gripper, releasing the yarn strands in the yarn feed device, pivoting the yarn transport gripper away from the yarn feed device, arranging the yarn strands under the insertion element, moving the cutting element into a cutting position, cutting the yarn strands, thereby creating yarn sections, releasing the yarn sections,

Inserting the yarn sections using a respective insertion element.

This process sequence can be understood as an independent aspect of the invention.

Fig. 17 shows a taffeta unit 10 according to an embodiment of the invention. Regarding most of the components used, reference is made to the description of Fig. 1 to 16. The following essentially discusses the differences from the prior art. Figs. 18, 19, and 20 show the same taffeta unit 10 as Fig. 17, but in different states.

In contrast to the prior art design, the design according to Fig. 17 includes a yarn holding unit 100 in addition to the components already described.

The yarn holding unit 100 is arranged, as shown, at the lower end of the taffeta needles 42. It is vertically movable, independently of the taffeta needles 42.

The yarn holding unit 100 has a first gripper 110 and a second gripper 120.

These move as part of the yarn holding unit 100 during an up and down movement of this unit.

The first gripper 110 is arranged between the taffeta needles 42 and the yarn feed device 20. The second gripper 120 is arranged on a side of the taffeta needles 42 opposite the yarn feed device 20. This applies in the horizontal direction.

The first gripper 110 can assume an open state and a closed state. In the open state, the yarn strands, which are not shown in Figs. 17 to 20, are not held by the first gripper 110. In the closed state, they are completely fixed, so that they are not movable at the location of the first gripper 110 either in the longitudinal direction or in a plane transverse thereto.

The second gripper 120 can also assume an open state and a closed state. In the open state, the yarn strands are not secured by the second gripper 120. In the closed state, the yarn strands are held by the second gripper 120 in such a way that they can move along their longitudinal direction, but are not, or at least barely, movable in a plane transverse to it. Overall, the two grippers 110, 120 can thus prevent yarn strands from falling.

Fig. 17 shows a state in which the yarn transport gripper 50 is pivoted completely to the right. In this state, it can grasp and hold a loose end of the yarn strands on the yarn feed device 20.

The yarn transport gripper 50 is then pivoted to the left, so that the state shown in Fig. 18 is assumed. Typically, the yarn strands come with the initially open first gripper 110. The first gripper 110 is then closed, thus holding the yarn strands vertically above the taffeta plate 70. Subsequently, the cutting unit 60 is activated to cut yarn sections from the yarn strands. However, these yarn sections do not fall down because the yarn sections are held to the left by the yarn transport gripper 50 or its transport gripper 56 and to the right by the first gripper 110.

Subsequently, the taffeta needles 42 and the yarn holding unit 100 are moved vertically downward. The state shown in Fig. 19 is assumed. Typically, in the initial situation shown in Fig. 18, a yarn section on the left side of the respective taffeta needle 42 is longer than on the right side. The first gripper 110 is held in its closed state as long as this is the case.

When the yarn holding unit 100 is lowered, the initially open second gripper 120 is also closed so that it holds the yarn sections independently of the yarn transport gripper 50 and prevents them from falling vertically. The transport gripper 56 is then opened, in particular so that yarn can be pulled in. As the taffeta needles 42 move vertically downwards, the yarn sections are transported downwards, changing the length ratio in that the length on the left side becomes shorter and the length on the right side becomes longer. When the yarn sections are the same length on both sides, the first gripper 110 is opened. This ensures that the yarn sections remain in a state in which they are the same length on both sides of the respective taffeta needle 42. The taffeta needles 42 are then moved even further downwards, achieving the state shown in Fig. 20. In this state, the yarn sections are finally inserted into the base 12, where they remain. Subsequently, the taffeta needle 42 is pulled upward again, and the yarn holding unit 100 also moves back to its uppermost position. The process illustrated in Figs. 17 to 20 can then begin again.

Overall, by holding the yarn sections vertically above the taffeta plate 70 by means of the yarn holding unit 100, shorter yarn sections can be used compared to the prior art. Furthermore, it is easily ensured that the yarn sections to be used are of equal length on both sides of the respective taffeta needle.

The invention is not limited to one of the embodiments described above, but can be modified in many ways. All features and advantages arising from the claims, the description and the drawings, including design details, spatial arrangements and method steps, can be essential to the invention both individually and in a wide variety of combinations.

Reference symbol list

Taffeta unit substrate yarn feed device axis

Yarn holder shaft yarn holder plate guide wheel yarn holder plate recesses yarn strands yarn section deflection insert element

Taffeta needle needle guide

Yarn transport gripper pivot point rod

Transport gripper Transport gripper plate Transport gripper plate Cutting unit Swivel axis Ball bearing Taffeta plate

Openings Opening curve Closing curve Motor

Timing wheel sensor ball bearing drive guide rod yarn holding unit 110 first gripper

120 second gripper

Claims

Patent claims 1. Taffeta unit (10) for a taffeta machine, the taffeta unit (10) comprising: • a yarn feeding device (20) for the simultaneous and parallel feeding of several yarn strands (30), • several insert elements (40), • a yarn transport gripper (50) which is designed to transport a respective free end of the yarn strands (30) away from the yarn feed device (20), so that each insertion element (40) is assigned a respective yarn strand (30), • a cutting unit (60) which is designed to cut the yarn strands (30) so that from each yarn strand (30) assigned to an insertion element (40), a yarn section (35) remains which is assigned to the respective insertion element (40), and • a yarn holding unit (100) which is designed to independently hold the associated yarn strand (30) or yarn section (35) under each insertion element (40), • wherein each insertion element (40) is designed to insert the respectively associated yarn section (35) into a substrate (12) located under the taffeta unit (10). 2. Taffeta unit (10) according to claim 1, characterized in that the yarn holding unit (100) has an actuatable first gripper (110) which is designed to hold the yarn strands (30) or yarn sections (35) at a location between insertion elements (40) and yarn feed device (20). 3. Taffeta unit (10) according to claim 2, characterized in that the first gripper (110) is designed to immovably fix the yarn strands (30) or yarn sections (35) on the first gripper (110). 4. Taffeta unit (10) according to one of claims 2 or 3, characterized in that the taffeta unit (10) has an actuating unit which is designed to first close the first gripper (110) during a vertical downward movement of the insertion elements (40) and then to open it when the yarn sections (35) on both sides of the respective insertion element (40) are of the same length. 5. Taffeta unit (10) according to one of the preceding claims, characterized in that the yarn holding unit (100) has an actuatable second gripper (120) which is designed to hold the yarn sections (35) at a location which lies on a side of the insertion elements (40) opposite the yarn feed device (20). 6. Taffeta unit (10) according to claim 5, characterized in that the second gripper (120) holds the yarn sections (35) in such a way that they remain movable along their longitudinal direction by the second gripper (120). 7. Taffeta unit (10) according to one of claims 5 or 6, characterized in that the taffeta unit (10) has an actuating unit which is designed to first open the second gripper (120) during a vertical downward movement of the yarn holding unit (100) and then to close it when the second gripper (120) comes into engagement with the yarn sections (35). 8. Taffeta unit (10) according to one of the preceding claims, characterized in that the yarn holding unit (100) is designed to hold the yarn strands (30) or yarn sections (35) vertically spaced from further components of the taffeta unit (10) arranged vertically below. 9. Taffeta unit (10) according to one of the preceding claims, characterized in that the yarn holding unit (100) is designed to be vertically movable. 10. Taffeta unit (10) according to one of the preceding claims, characterized in that the taffeta unit (10) has a drive unit which is designed to partially move the yarn holding unit (100) downwards during a vertical movement of the insertion elements (40) downwards. 11. Taffeta unit (10) according to claim 10, characterized in that the taffeta unit (10) has a taffeta plate (70) on the underside, in which at least one opening (75) is formed for guiding the yarn section during insertion, and wherein the actuating unit is designed to move the yarn holding unit (100) downwards to the taffeta plate (70). 12. Taffeta unit (10) according to one of the preceding claims, characterized in that the taffeta unit (10) is designed for inserting yarn sections (35) with a length of at most 24 cm. 13. A method for inserting yarn sections (35) into a substrate (12), the method comprising the following steps: • Feeding several parallel yarn strands (30) by means of a yarn feeding device (20), • Transporting the yarn strands (30) under respective insertion elements (40) by means of a yarn transport gripper (50), • Holding the yarn strands (30) under the insertion elements (40) by means of a yarn holding unit (100), • Cutting the yarn strands (30) so that from each yarn strand (30) assigned to an insert element (40), a yarn section (35) remains assigned to the respective insert element (40), and • Inserting the yarn sections (35) into the substrate (12) using the insertion elements (40). 14. The method according to claim 13, wherein before cutting and at least partially during insertion, the yarn strands (30) are held immobile at a location between insertion elements (40) and yarn feed device (20). 15. The method according to claim 14, wherein the yarn strands (30) are held immobile at the location between the insertion elements (40) and the yarn feed device (20) during insertion only until the yarn strands (30) on both sides of the insertion elements (40) are of equal length. 16. Method according to one of claims 13 to 15, wherein during insertion the yarn sections (35) are held at a location which lies on a side of the insertion elements (40) opposite the yarn feed device (20) in such a way that they are movable along their longitudinal axis. 17. Method according to one of claims 13 to 16, which is carried out by means of a taffeta unit (10) according to one of claims 1 to 12.