Tufting unit and tufting machine

Abstract

The invention relates to a tufting unit for inserting yarn sections into a substrate, wherein the tufting unit comprises a tensioning device, one or more gripping elements, one or more retraction elements, a cutting device, and one or more insertion elements, wherein a yarn strand is tensioned by the tensioning device, gripped by the gripping element, formed by the retraction elements, and inserted by an insertion element. The invention further relates to a tufting machine with such a tufting unit.

Description

[0001] The invention relates to a tufting unit for inserting yarn sections into a substrate and to a tufting machine with such a tufting unit.

[0002] Tufting machines typically have a tufting unit and are used to insert yarn sections into a subsurface. This is particularly done to create artificial turf or to reinforce existing natural grass with yarn. Typically, it is considered important that a tufting unit can insert as many yarn sections as possible within a given period of time as reliably and smoothly as possible. This increases work efficiency.

[0003] The document DE 10 2007 027 114 A1 discloses a hollow needle tufting device with a narrow gauge.

[0004] The document DE 20 2016 102 177 U1 discloses a device for inserting artificial yarn strands into the ground.

[0005] Document US 2014 / 0 331 906 A1 discloses a system and method for forming artificial turf.

[0006] The document US 2019 / 0 390 386 A1 discloses a system and a method for forming artificial turf.

[0007] Document EP 4 249 658 A1 discloses a taffeta unit and a taffeta machine.

[0008] Document EP 4 357 506 A1 discloses a tufting machine and a method for introducing yarn strands into a substrate.

[0009] It is an object of the invention to provide a tufting unit that is alternative to or better than known tufting units. It is also an object of the invention to provide a tufting machine with such a tufting unit. This is achieved according to the invention by a tufting unit and a tufting machine according to the respective main claims. Advantageous embodiments are claimed in the subclaims.

[0010] The invention relates to a tufting unit for inserting yarn sections into a substrate. The tufting unit has a tensioning device for tensioning at least one yarn strand along a first direction. The tufting unit has one or more gripping elements. The tufting unit has one or more first retraction elements. The tufting unit has a cutting device. The tufting unit has one or more insertion elements. The gripping elements each have a first receiving element and a second receiving element spaced therefrom for receiving a yarn strand. Each gripping element is linearly movable along an axis. Each gripping element is designed to extend and thereby grip the respective yarn strand or strands with the first receiving element and the second receiving element when the yarn strand is tensioned along the first direction. The first retraction element or the first retraction elements is or are...are designed to encompass the yarn strand gripped by a gripping element, then retract it, and thereby shape the yarn strand such that it extends at least partially along the gripping element. The cutting device is designed to cut the yarn strand or strands, so that a yarn section held in the gripping element and extending at least partially along the gripping element is severed. Each insertion element is designed to insert a respective yarn section into the substrate.

[0011] Using such a tufting unit, it is particularly easy to obtain yarn sections, which can then be inserted into a substrate using the insertion elements. The respective yarn strand is first tensioned and then appropriately gripped by the gripping elements. The retraction elements ensure a shape suitable for insertion. The cutting device cuts the yarn strands to the appropriate length, creating yarn sections. The insertion elements then insert the yarn sections into the substrate. Compared to known designs, the tufting unit described here is particularly powerful because it requires few moving parts, and these typically only need to be moved over short distances.

[0012] Basically, a tufting unit can be understood as a device that inserts yarn sections into a subsurface and thereby creates, for example, an artificial turf pitch or reinforces an existing grass pitch with yarn sections. Yarn sections are typically cut parts of a yarn strand. A yarn strand is typically very long. It can, for example, be fed from a spool, which can be located in the tufting unit or in a tufting machine. The tensioning device typically serves to tension a yarn strand along the first direction. When the respective yarn strand is gripped by the gripping element, the respective yarn strand is typically taut so that it cannot be deflected from its taut state, or at least can only be deflected insignificantly. The gripping elements serve to at least partially bring the yarn strand into a position in which it can be gripped by the insertion elements.The retraction elements typically deform the yarn strand so that it runs at least partially along a gripping element. This gives the yarn strand a shape that at least approximately corresponds to a U-shape. Such a U-shape is typically the shape in which a yarn section is inserted.

[0013] An embodiment is described below in which, in particular, the first direction can be a vertical direction.

[0014] In this embodiment, the tensioning device is typically designed to tension multiple yarn strands. This allows the yarn strands to be fed in parallel. The tufting unit preferably has one or more second retraction elements. Each gripping element is preferably rotatable about the axis. Each gripping element is preferably assigned a first retraction element and a second retraction element, wherein the gripping element is arranged between the first retraction element assigned to it and the second retraction element assigned to it, and wherein the retraction elements are linearly movable parallel to the axis. The gripping elements can in particular be designed to rotate after gripping the yarn strand, so that a section between the first receiving element and the second receiving element is oriented in a second direction which is different from the first direction.The first retraction element and the second retraction element can, in particular, be designed to encompass the yarn strand gripped by a gripping element, then retract it, and thus shape the yarn strand such that it extends at least partially along the gripping element. In particular, the first retraction element can be arranged above the respective gripping element, and the second retraction element can be arranged below the respective gripping element.

[0015] Such a design makes it possible to feed and process multiple yarn strands in parallel. Typically, each yarn strand is gripped by a single gripping element and two retracting elements to move it into the appropriate position. It can then be cut using the cutting device, creating a yarn section of a specific length. This can then be inserted using an insertion element. In principle, however, it is also possible to process just one yarn strand, for which only one gripping element with associated retracting elements is sufficient.

[0016] In particular, the first direction can be a vertical direction. In particular, the second direction can be a horizontal direction. In particular, the first direction can be oriented transversely to the second direction. In particular, the yarn strands can thus initially be tensioned vertically and then aligned horizontally between the two receiving elements of a respective gripping element after rotation of the respective gripping element. Such a horizontal section makes it easier for the insertion elements to grip the respective yarn section. The vertical feed along the first direction facilitates the simultaneous feeding of numerous parallel yarn strands.

[0017] In particular, it can be provided that when the gripping element is rotated, the yarn strand engages with the first retraction element and / or with the second retraction element. Thus, the aforementioned rotational movement of the gripping element can be used to bring the yarn strand into engagement with the retraction elements. In particular, undercuts can be provided in the retraction elements, which are designed such that when the yarn strand is rotated by means of the gripping element, the yarn strand engages in the respective undercut.

[0018] In particular, the associated first retraction element can be arranged above each gripping element. In particular, the associated second retraction element can be arranged below each gripping element. Such a design enables, in particular, easy holding of the yarn strand above and below the respective gripping element. With a vertical yarn feed, this can, in particular, ensure that the yarn strand can easily engage the respective retraction element or an undercut of the retraction element.

[0019] An alternative embodiment is described below. In this embodiment, the first direction can be a horizontal direction. In particular, each gripping element can be arranged between two first retraction elements. This can, in particular, provide for only a single yarn strand to be fed, which can then also be passed on to several gripping elements for further processing. The retraction elements are typically arranged alternately with the gripping elements. Second retraction elements are typically not present.

[0020] It should be noted that the tufting unit is designed to interact with yarn strands. The yarn strands are not considered part of the tufting unit.

[0021] In particular, it can be provided that the aforementioned elements, for example gripping elements, retraction elements, and insertion elements, as well as a cutting device, can be actuated electrically, hydraulically, mechanically, or otherwise. In particular, suitable control devices can be provided, for example an electronic control device and / or control paths along which control bodies can be guided. In particular, it can thus be provided that the described functionality is implemented, for example, that elements are extended and / or retracted or rotated at specific times.

[0022] In this context, extending is understood to mean, in particular, moving from a rest position, where typically no yarn strand is gripped in the rest position and a yarn strand is gripped after extending. Retracting is understood to mean moving in the opposite direction.

[0023] In particular, the gripping elements can be arranged along a horizontal line. This allows for easy provision of several yarn sections directly next to each other horizontally, so that the insertion elements can easily grip the yarn sections.

[0024] In particular, the gripping elements can each have a round cross-section, at least apart from a section in which the receiving elements are arranged.

[0025] In particular, the first receiving element can have a first projection and a second projection, between which a depression is formed, in which the yarn strand is received. In particular, the second receiving element can have a first projection and a second projection, between which a depression is formed, in which the yarn strand is received. By means of such a design with two projections and a depression formed therebetween, easy gripping of the respective yarn strand is possible. The yarn strand lies in the depression between the two projections. In particular, there can be an intermediate space between the two receiving elements. In this space, in particular a part of a yarn section, which is aligned horizontally, can be received by an insertion element and then inserted.

[0026] The axis can, in particular, be transverse to the first direction. The axis can, in particular, be transverse to the second direction. In particular, this allows the insertion elements and / or the retraction elements to be movable transversely to a plane spanned by the first direction and the second direction.

[0027] In particular, the first retraction element can have an undercut for gripping the yarn strand. In particular, the second retraction element can have an undercut for gripping the yarn strand. The respective yarn strand can be received in this undercut, in particular by rotating the respective gripping element, as already described above. When the respective retraction element retracts, the yarn strand typically remains in the respective undercut and is thus partially retracted by the retraction element.

[0028] In particular, in the case of a first retraction element and a second retraction element which are assigned to the same gripping element, the undercut of the first retraction element can be arranged in a plane transverse to the axis with respect to the gripping element, diagonally opposite the undercut of the second retraction element. This allows the yarn strand to be brought into the undercuts of both retraction elements by rotation of the gripping element in one direction. In particular, a plane can be defined for this purpose which is transverse to the axis of the gripping element, wherein, viewed in this plane, for example, the gripping element can be considered to be central and the undercut of the upper retraction element can be arranged at the top left and the undercut of the lower retraction element can be arranged at the bottom right.Alternatively, the undercut of the upper retraction element can be positioned at the top right and the undercut of the lower retraction element at the bottom left. This can apply, for example, to a top view of the gripping element from the front or, alternatively, from the rear.

[0029] In particular, after retraction of the first retraction element and / or the second retraction element, the yarn strand can be of equal length on both sides of the gripping element. This allows for a uniform design of the yarn section, especially after cutting. In particular, it can be provided that the yarn section is of equal length starting from a tip of the gripping element, at which the yarn strand or yarn section is held.

[0030] The insertion elements can, in particular, be designed as vertically movable tufting needles. This allows for easy insertion by moving the tufting needles downwards.

[0031] When gripping the yarn strand, the yarn strand can be deflected, in particular by means of the gripping element, at least partially in the direction of the extending gripping element. This allows, for example, the yarn strand to be at least approximately V-shaped, which can then be at least substantially U-shaped by the retraction elements. Furthermore, by deflecting the yarn strand, part of the yarn strand is moved to a location where it can be easily gripped by the insertion elements.

[0032] The first retraction element can, in particular, have a slot-shaped recess that stabilizes the yarn strand when gripped transversely to the axis. The second retraction element can, in particular, have a slot-shaped recess that stabilizes the yarn strand when gripped transversely to the axis. This can provide additional stability for the yarn strand. The respective slot-shaped recess can, in particular, extend along a direction predetermined by the axis of the respective gripping element.

[0033] According to an advantageous embodiment, the clamping device has a first clamping unit and a second clamping unit. The gripping elements are arranged in particular between the first clamping unit and the second clamping unit. In the first embodiment already described above, with a particularly vertical first direction, this can mean in particular that the first clamping unit is arranged above the gripping elements and the second clamping unit is arranged below the gripping elements. In the second embodiment already described above, with a particularly horizontal first direction, this can mean in particular that the first clamping unit is arranged to the left of the gripping elements and the second clamping unit is arranged to the right of the gripping elements. The reverse embodiment is also possible.

[0034] In particular, it can be provided that the first tensioning unit is switchable between a first state and a second state, wherein it holds the yarn strand or strands in the first state and releases them in the second state. In particular, it can be provided that the second tensioning unit is switchable between a first state and a second state, wherein it holds the yarn strand or strands in the first state and releases them in the second state. In this way, tensioning of the yarn strands can be achieved, wherein in particular in the first state an already achieved tension can be maintained. By releasing the respective tensioning unit, in contrast, passage of the respective yarn strand through the respective tensioning device can be achieved.

[0035] In particular, the tensioning device can have a transport unit which can be designed in particular to grip the yarn strand or strands on a side of the first tensioning unit facing away from the gripping elements and to transport them on a side of the second tensioning unit facing away from the gripping elements, such that the yarn strand or strands can be held by the tensioning units. By means of such a transport unit, in particular, a respective further guidance or withdrawal of the yarn strands can be achieved, so that they can also be unwound. In particular, the yarn strand can be positioned such that respective yarn sections can be made available for insertion by the mechanisms described above.

[0036] In particular, the tufting unit can be configured to activate the transport unit after inserting one or more yarn sections into the substrate, so that it grips the yarn strand or strands on the side of the first tensioning unit facing away from the gripping elements and transports them to the side of the second tensioning unit facing away from the gripping elements, and then switches the first tensioning unit and the second tensioning unit to the first state. This allows a yarn strand or strands to be made available again after insertion so that they can be prepared for another insertion process.

[0037] In particular, the cutting device can have a cutting disc that can move at least substantially transversely to the yarn strand(s). This has proven to be a simple and practical design. For example, the cutting disc can be movable two-dimensionally. This allows for easy cutting. However, alternative designs are also possible. For example, the cutting device can be designed as a movable knife.

[0038] The invention further relates to a mobile tufting machine with a chassis for moving the tufting machine over a surface, and with a tufting unit as described herein. With regard to the tufting unit, all embodiments and variants described herein can be used. The chassis can be designed, in particular, to allow the tufting machine to travel over a surface such as a lawn. The chassis can be designed to be passive, so that the tufting machine is pulled, for example, by a towing vehicle or otherwise moved by an external device. The chassis can also be designed as an active chassis, so that it has its own drive, which can move the tufting machine over the surface.

[0039] The invention will now be described with reference to the figures, in which: Fig. 1: a section of a tufting unit, Fig. 2: a side view of the section of Fig. 1, and Fig. 3 to 9: different states of a tufting unit during an insertion process.

[0040] Fig. 1 shows purely schematically a section of a tufting unit 100 according to an embodiment.

[0041] The tufting unit 100 essentially comprises several gripping elements 200 arranged horizontally adjacent to one another. In the view shown here, however, only one such gripping element 200 is designated by a reference symbol. The others are obviously arranged adjacent to it and extend parallel. The functionality of this gripping element 200, which is provided with the reference symbol, will be explained below.

[0042] Each gripping element 200 has a Fig. 1, a tip directed to the front left comprises a first receiving element 210 and a second receiving element 220. The two receiving elements 210, 220 are arranged such that a gap 230 remains between them. The first receiving element 210 has a first projection 211 and a second projection 212, between which there is a recess 213. Likewise, the second receiving element 220 has a first projection 221 and a second projection 222, between which there is a recess 223. The two recesses 213, 223 are basically designed to accommodate a yarn strand 110, as will be described in more detail below.

[0043] The tufting unit 100 further comprises a first retraction element 310 and a second retraction element 320. The first retraction element 310 has an undercut 312. The second retraction element 320 has an undercut 322. In a plan view along a longitudinal extent of the gripping element 200, the two undercuts 312, 322 are arranged diagonally opposite one another with respect to the gripping element 200, with the undercut 312 of the first retraction element 310 being located at the top left and the undercut 322 of the second retraction element 320 being located at the bottom right. In alternative embodiments of the retraction elements 310, 320, it is possible to provide slot-shaped recesses which extend along the longitudinal extent of the retraction elements 310, 320 and can stabilize the yarn strand 110 while it is gripped by the gripping element 200.

[0044] The gripping element 200 is movable along an axis A and also rotatable about this axis A. It can thus extend, which is shown in the illustration of Fig. 1 corresponds to a movement to the left and forward, and retract, which corresponds to an opposite movement. Likewise, the two retraction elements 310, 320 can extend and retract. However, the retraction elements 310, 320 are not rotatable.

[0045] The tufting unit 100 is used to insert yarn strands, of which Fig. 1 only one yarn strand 110 is shown. In principle, several yarn strands 110 can be processed simultaneously, and this is done in the same way as described below.

[0046] Above the gripping element 200 and the first retraction element 310 there is a first clamping unit 410, which Fig. 1 is shown only schematically. The first tensioning unit 410 is switchable between a first state and a second state, wherein it holds the yarn strand 110 or the yarn strands 110 in the first state and releases them in the second state. Likewise, a second tensioning unit 420 is arranged below the gripping element 200 and the second retraction element 320, which in Fig. 1 is also shown only schematically. This is also switchable between a first state and a second state, holding the yarn strand 110 or the yarn strands 110 in the first state and releasing them in the second state. Furthermore, above the previously mentioned arrangements, insertion elements 500 in the form of tufting needles are arranged, which are vertically movable and in Fig. 1 are also only schematically indicated in the form of an insert element 500.

[0047] A vertically oriented upper guide plate 600 serves to at least partially guide the yarn strand 110 or strands 110. Openings 610 through which the gripping elements 200 pass, as well as further openings 620, 625 through which the retraction elements 310, 320 pass, are located therein. A guide element 700 is arranged above the upper guide plate 600. V-shaped recesses 710 are formed in said guide element, in each of which a yarn strand 110 is guided. This facilitates the correct positioning of the yarn strands 110, so that they can be easily grasped by the respective gripping element 110.

[0048] As in Fig. 1, a first direction R1 and a second direction R2 are defined. The first direction R1 is vertical in the present case, the second direction R2 is horizontal. Typically, a yarn strand 110 is first tensioned along the first direction R1, i.e. vertically, in such a way that it lies directly against the upper guide plate 600. It extends directly in front of an opening 610 of the upper guide plate 600. In this case, the two retraction elements 310, 320 as well as the gripping element 200 are in a retracted state. They therefore do not contact the yarn strand 110. Then, first, the gripping element 200 is extended, whereby, in comparison to the Fig. 1, so that the first receiving element 210 is located above the second receiving element 220. When the gripping element 200 is extended, the yarn strand 110 is thus inserted into the two troughs 213, 223. The gripping element 200 is then extended further so that the yarn strand 110 is deflected slightly outwards. For this purpose, the first tensioning unit 410 is switched to its second state, whereas the second tensioning unit 420 remains in its first state. When the gripping element 200 is extended further, some yarn strand 110 is thus pulled in, for example, unwound from a spool (not shown).

[0049] The retraction elements 310, 320 then extend and position themselves such that the undercuts 312, 322 are positioned such that the yarn strand 110 has not yet been received therein, but can be received therein by rotating the gripping element 200 about its axis A. The gripping element 200 is then rotated 90° to the left about its axis A, as seen from the front, so that the yarn strand 110 is inserted into the undercuts 312, 322. Then again, the two retraction elements 310, 320 move back, taking the yarn strand 110 with them at one point each. The yarn strand 110 then has a shape in which it extends partially essentially along the gripping element 200. This corresponds approximately to a U-shape, with the legs of the U being slightly deflected against each other.

[0050] The yarn strand 110 is then passed through a Fig. 1, a cutting device (not shown) cuts the yarn section, leaving a yarn section held by the components already mentioned. Subsequently, an insertion element 500 can move vertically downward and grip the yarn section between the two receiving elements 210, 220. The gripping element 200 then moves back, and the insertion element 500 moves further downward. The yarn section is inserted into a substrate.

[0051] To achieve further stabilization during insertion into the ground, a lower guide plate 750 is arranged at the bottom, in which several openings 760 are formed. An insertion element 500 passes through each of these openings 760 on its downward path, thereby preventing lateral deviation from the intended movement.

[0052] Fig. 2 shows a side view of the section of the tufting unit 100 of Fig. 1. This shows a state in which the gripping element 200 is extended so far that a yarn section 115, which was created from a yarn strand 110 by cutting it, can be gripped by the insertion element 500. The retraction elements 310, 320 are retracted so far that the yarn section 115 has at least approximately a U-shape, wherein the yarn section 115 extends approximately along the gripping element 200 between the retraction elements 310, 320 and the tip of the gripping element 200.

[0053] The Fig. Figures 3 to 9 show different states of a tufting unit 100 during an insertion process. The components shown are predominantly the same as in Fig. 9, however, the upper guide plate 600 is not shown. Additionally, a cutting device 800 is shown, which has a cutting disk 810. The cutting device 800 can be moved horizontally in two directions, so that the yarn strands 110 can be cut as needed to obtain yarn sections 115. The cutting action takes place in the guide element 700.

[0054] Furthermore, the clamping device 400 is shown in more detail. As already mentioned, the first clamping unit 410 is located above the gripping elements 200 and the second clamping unit 420 is located below the gripping elements 200. Furthermore, in the Fig. 3, a transport unit 430 is arranged above the first tensioning unit 410, which is movable. The transport unit 430 also has a first state and a second state, wherein in the first state it holds the yarn strands 110 and in the second state it releases them. The transport unit 430 is part of the tensioning device 400.

[0055] The structure of the tensioning units 410, 420 and the transport unit 430 is explained using the second tensioning unit 420. This is constructed of three plates, namely an upper plate 421, a middle plate 422, and a lower plate 423. The upper plate 421 and the lower plate 423 are fixed, whereas the middle plate 422 is movable relative to them. Respective recesses 424 are provided in the plates 421, 422, and 423, through which the yarn strands 110 are guided. Fig. Figure 3 shows the second state, where yarn strands 110 can pass freely through the recesses 424. If the middle plate 422 is moved, the yarn strands 110 are clamped between the plates 421, 422, and 423. This represents the first state.

[0056] Fig. Figure 3 shows an initial state at the beginning of an insertion process. The yarn strands 110 are gripped by the transport unit 430 above the first tensioning unit 410.

[0057] Fig. 4 shows a state in which the transport unit 430 has moved downwards to a position below the second clamping unit 420. Starting from the Fig. In the state shown in Figure 4, the first and second tensioning units 410, 420 can be switched to the first state to keep the yarn strands 110 taut, and the transport unit 430 can be switched to the second state to release the yarn strands 110. The transport unit 430 can then return to its upper position.

[0058] Fig. 5 shows a state in which starting from Fig. 4 the gripping elements 200 were extended. The yarn strands 110 were thereby deflected, as in Fig. 4. To enable this, the first tensioning unit 410 can be switched to the second state, at least temporarily. This allows yarn to be fed in. The retraction elements 310, 320 are also extended.

[0059] Fig. 6 shows a state in which the gripping elements 200 are in comparison to the Fig. 5, have been rotated by 45°. As a result, a section of the yarn strands 110 located between the receiving elements 210, 220 is also rotated. Overall, the gripping elements 200 are rotated by 90°, which results in Fig. 7. The section of the yarn strands 110 located between the receiving elements 210, 220 is then horizontal. In this case, the respective yarn strand 110 also engages the undercuts 312, 322 of the retraction elements 310, 320.

[0060] If the retraction elements 310, 320 are then retracted, the Fig. 8. The yarn strands 110 are approximately U-shaped and extend partially along the gripping elements 200. The bending of the yarn strands 110 above the first retraction element 310 is effected by the upper guide plate 600, which is Fig. 8 is not shown, but nevertheless exerts its effect. The yarn strands 110 can then be cut off by the cutting device, creating yarn sections 115.

[0061] If the insertion elements 500 are moved downwards and, if necessary, the gripping elements 200 are extended further, the Fig. 9. The insertion elements 500 grip the respective horizontal section of the yarn sections 115. After retracting the respective gripping element 200, the respective insertion element 500 can be moved downward and insert the yarn section 115 into a substrate (not shown).

[0062] It should be noted that specifications such as “above”, “below”, “vertical” or “horizontal” refer to an orientation of the tufting unit or tufting machine in a typical operating condition. List of reference symbols 100 tuft units 110 skeins of yarn 115 yarn section 200 gripping element 210 first receiving element 211 first lead 212 second lead 213 trough 220 second receiving element 221 first lead 222 second lead 223 hollow 230 space 310 first retraction element 312 undercut 320 second retraction element 322 undercut 400 clamping device 410 first clamping unit 420 second clamping unit 421 upper plate 422 middle plate 423 lower plate 424 recess 430 transport unit 500 insert element 600 upper guide plate 610 Opening 620 further opening 625 further opening 700 guide element 710 recesses 750 lower guide plate 760 openings 800 cutting device 810 cutting disc

Claims

[1] Tufting unit (100) for inserting yarn sections (115) into a substrate, the tufting unit (100) comprising: a) a tensioning device (400) for tensioning at least one yarn strand (110) along a first direction (R1), b) one or more gripping elements (200), c) one or more first retraction elements (310), d) a cutting device (800), and e) one or more insert elements (500), f) wherein the gripping elements (200) each have a first receiving element (210) and a second receiving element (220) spaced therefrom for receiving a yarn strand (110), wherein each gripping element (200) is linearly movable along an axis (A), g) wherein each gripping element (200) is designed to extend and thereby grip the or a yarn strand (110) with the first receiving element (210) and the second receiving element (220) when the yarn strand (110) is tensioned along the first direction (R1), h) wherein the first retraction element (310) or the first retraction elements (310) are designed to encompass the yarn strand (110) gripped by a gripping element (200), then retract it and thereby shape the yarn strand (110) such that it extends at least partially along the gripping element (200), i) wherein the cutting device (800) is designed to cut off the yarn strand (110) or the yarn strands (110) so that a yarn section (115) which is held in the gripping element (200) and extends at least partially along the gripping element (200) is severed, and j) wherein each insertion element (500) is designed to insert a respective yarn section (115) into the substrate. [2] Tufting unit (100) according to claim 1, a) wherein the tensioning device (400) is designed to tension a plurality of yarn strands (110), b) wherein the tufting unit (100) has one or more second retraction elements (320), c) wherein each gripping element (200) is rotatable about the axis (A), d) wherein each gripping element (200) is assigned a first retraction element (310) and a second retraction element (320), wherein the gripping element (200) is arranged between the first retraction element (310) assigned to it and the second retraction element (320) assigned to it, and wherein the retraction elements (310, 320) are linearly movable parallel to the axis (A), e) wherein the gripping elements (200) are designed to rotate after gripping the yarn strand (110) so that a section between the first receiving element (210) and the second receiving element (220) is oriented in a second direction (R2) which is different from the first direction (R1), f) wherein the first retraction element (310) and the second retraction element (320) are designed to encompass the yarn strand (110) gripped by a gripping element (200), then retract it and thereby shape the yarn strand (110) such that it extends at least partially along the gripping element (200). [3] Tufting unit (100) according to claim 2, a) wherein the first direction (R1) is a vertical direction, and / or b) wherein the second direction (R2) is a horizontal direction, and / or c) wherein the first direction (R1) is oriented transversely to the second direction (R2). [4] Tufting unit (100) according to one of claims 2 or 3, wherein upon rotation of the gripping element (200) the yarn strand (110) engages with the first retraction element (310) and / or with the second retraction element (320). [5] Tufting unit (100) according to one of claims 2 to 4, a) wherein the associated first retraction element (310) is arranged above each gripping element (200), and / or b) wherein the associated second retraction element (320) is arranged under each gripping element (200). [6] The tufting unit (100) of claim 1, wherein the first direction (R1) is a horizontal direction. [7] Tufting unit (100) according to claim 6, wherein each gripping element (200) is arranged between two first retraction elements (310). [8] Tufting unit (100) according to one of the preceding claims, wherein the gripping elements (200) are arranged along a horizontal line. [9] Tufting unit (100) according to one of the preceding claims, a) wherein the first receiving element (210) has a first projection (211) and a second projection (212), between which a trough (213) is formed, in which the yarn strand (110) is received, and / or b) wherein the second receiving element (220) has a first projection (221) and a second projection (222), between which a trough (223) is formed in which the yarn strand (110) is received. [10] Tufting unit (100) according to one of the preceding claims, a) wherein the axis (A) is transverse to the first direction (R1), and / or b) wherein the axis (A) is transverse to the second direction (R2). [11] Tufting unit (100) according to one of the preceding claims, a) wherein the first retraction element (310) has an undercut (312) for gripping the yarn strand (110), and / or b) wherein the second retraction element (320) has an undercut (322) for gripping the yarn strand (110). [12] Tufting unit (100) according to claim 11, wherein in a first retraction element (310) and a second retraction element (320) which are associated with the same gripping element (200), the undercut (312) of the first retraction element (310) is arranged in a plane transverse to the axis (A) with respect to the gripping element (200) diagonally opposite the undercut (322) of the second retraction element (320). [13] Tufting unit (100) according to one of the preceding claims, wherein after retraction of the first retraction element (310) and / or the second retraction element (320), the yarn strand (110) is of the same length on both sides of the gripping element (200). [14] Tufting unit (100) according to one of the preceding claims, wherein the insertion elements (500) are designed as vertically movable tufting needles. [15] Tufting unit (100) according to one of the preceding claims, wherein when gripping the yarn strand (110) by means of the gripping element (200), the yarn strand (110) is deflected at least in sections in the direction of the extending gripping element (200). [16] Tufting unit (100) according to one of the preceding claims, a) wherein the first retraction element (310) has a slot-shaped recess which stabilizes the yarn strand (110) when gripping transversely to the axis (A), and / or b) wherein the second retraction element (320) has a slot-shaped recess which stabilizes the yarn strand (110) when gripped transversely to the axis (A). [17] Tufting unit (100) according to one of the preceding claims, a) wherein the clamping device (400) comprises a first clamping unit (410) and a second clamping unit (420), b) wherein the gripping elements (200) are arranged between the first clamping unit (410) and the second clamping unit (420), c) wherein the first tensioning unit (410) is switchable between a first state and a second state, holding the yarn strand (110) or the yarn strands (110) in the first state and releasing them in the second state, and d) wherein the second tensioning unit (420) is switchable between a first state and a second state, wherein it holds the yarn strand (110) or the yarn strands (110) in the first state and releases them in the second state. [18] Tufting unit (100) according to claim 17, wherein the tensioning device (400) has a transport unit (830) which is designed to grip the yarn strand (110) or the yarn strands (110) on a side of the first tensioning unit (410) facing away from the gripping elements (200) and to transport them to a side of the second tensioning unit (420) facing away from the gripping elements (200), so that the yarn strand (110) or the yarn strands (110) can be held by the tensioning units (410, 420). [19] Tufting unit (100) according to claim 18, which is configured to activate the transport unit after insertion of a yarn section (115) or several yarn sections into the substrate, so that it grips the yarn strand (110) or the yarn strands (110) on the side of the first tensioning unit facing away from the gripping elements (200) and transports them to the side of the second tensioning unit (420) facing away from the gripping elements (200), and then switches the first tensioning unit (410) and the second tensioning unit (420) to the first state. [20] Tufting unit (100) according to one of the preceding claims, wherein the cutting device (800) comprises a cutting disc (810) movable at least substantially transversely to the yarn strand (110) or to the yarn strands (110). [21] A mobile tufting machine comprising a chassis for moving the tufting machine over a surface, and a tufting unit (100) according to any one of the preceding claims.