System for tensioning a drive belt of a traction device, with a traction device and a belt tensioner

Abstract

The invention relates to a drafting device for a spinning machine, having at least two roller pairs, each having an upper roller and a lower roller, and at least one drive motor for driving at least one of the lower rollers, wherein the at least one drive motor and the lower roller drivable by the at least one drive motor are arranged mounted at a lower roller holder, wherein the at least one drive motor connected to the lower roller via a transmission belt is arranged at the lower roller holder at a variable distance from the lower roller for adjusting the transmission belt tension. The invention also relates to a belt tensioning clamp for adjusting the transmission belt tension of a drafting device and to a system for tensioning a transmission belt of a drafting device, having a drafting device and a belt tensioning clamp. In order to provide a drafting device, a belt tensioning clamp and a system consisting of a drafting device and a belt tensioning clamp, such that an easy adjustment of the transmission belt tension is possible, the following is provided for the drafting device: The at least one drive motor is mounted at the drafting device, the at least one drive motor is pivotable about an axis of rotation and is mounted at the lower roller holder in such a way that it can be fixed in the adjusted position.

Description

[0001] This invention relates to a drafting device for a spinning machine, comprising: at least two pairs of rollers, each pair having an upper roller and a lower roller; and at least one drive motor for driving at least one of the lower rollers, wherein the at least one drive motor and the lower roller drivable by the at least one drive motor are arranged to be mounted at a lower roller frame, wherein the at least one drive motor, connected to the lower roller via a drive belt, is arranged at a variable distance from the lower roller at the lower roller frame to adjust the drive belt tension. The invention also relates to a belt tensioner for adjusting the drive belt tension of the drafting device, and a system having a drafting device and a belt tensioner for tensioning the drive belt of the drafting device.

[0002] Various implementations of drafting devices for spinning machines are known in the prior art. They are used to stretch or twist the fiber sliver, thereby reducing the cross-sectional area of ​​the fiber. During drafting, the fibers must be fed side-by-side as evenly as possible to obtain a uniform fiber sliver, which is a prerequisite for producing uniform yarn.

[0003] To stretch the fiber sliver, the drafting device typically has several pairs of rollers arranged sequentially, adjacent to each other, clamping the fiber sliver running between them. A roller pair here usually consists of a driven lower roller and an upper pressure roller abutting against the lower roller. In the fiber sliver's transport direction, determined by the rotation direction of the roller pairs, the circumferential speed increases progressively from roller pair to roller pair, thereby achieving the stretching of the fiber sliver.

[0004] To drive the lower rollers, which are rotatably mounted on the lower roller frame of the drafting unit, it is known that a drive motor assigned to each lower roller is used, which drives the lower rollers via a transmission belt. To ensure reliable power transmission from the drive motor to the lower roller, the transmission belt used to connect the drive motor and the lower roller needs to have a predetermined transmission belt tension.

[0005] In known drafting devices, to adjust the belt tension, a drive motor is mounted on a motor plate in a longitudinally movable manner. This longitudinal movement causes a change in the distance between the drive motor and the lower roller, which adjusts the belt tension. To this end, the drive motor moves from the motor plate to a predetermined position on the motor plate for the desired belt tension and is secured in that position with suitable fasteners.

[0006] Misalignment can occur during the fixing of the drive motor, so the belt tension needs to be checked after each tensioning process, which usually requires complex frequency measurements. This work is extremely costly and time-consuming, especially in drafting units where each lower roller is connected to the drive motor via a belt of different lengths.

[0007] Based on this, the object of the present invention is to provide a stretching device, a belt tensioner, and a system consisting of the stretching device and the belt tensioner, making it possible to easily adjust the tension of the drive belt.

[0008] The present invention achieves its objective through a drafting device having the features of claim 1, a belt tensioner having the features of claim 8 for adjusting the tension of the drive belt of the drafting device, and a system having a drafting device and a belt tensioner having the features of claim 12 for tensioning the drive belt of the drafting device. Preferred improvements of the invention are described in the dependent claims.

[0009] According to the drafting device of the invention, at least one drive motor of at least one lower roller rotatably mounted on the lower roller holder is pivotable about a rotation axis to adjust its distance from the associated lower roller, and is mounted on the lower roller holder in a manner that allows it to be fixed in the adjusted position. Therefore, according to the invention, the drive motor is also fixedly connected to the lower roller holder during the adjustment of its position on the rotation axis. Here, the rotation axis at the lower roller holder has such an orientation that the pivoting of the drive motor about the rotation axis causes a change in the distance between the drive motor and the lower roller, or between the drive shaft axis of the drive motor and the rotation axis of the lower roller. By arranging the drive motor in a fixed position on the rotation axis, it is possible to easily pivot the drive motor, which is pivotable relative to the lower roller holder, into a position where the necessary distance for the desired belt tension appears between the drive motor and the lower roller. Permanently maintaining the connection between the drive motor and the lower roller holder on the rotation axis reliably prevents the drive motor from tilting, resulting in the belt tension deviating from the belt tension set for this purpose at the adjusted position. To adjust the belt tension, markings can be set at the lower roller, for example, and these markings are assigned to the corresponding belt tension when the drive motor is in the corresponding position. Therefore, the drafting device according to the invention makes it possible to adjust the belt tension in a particularly simple and reliable manner, and thus ensures the reliable operation of the drafting device. Furthermore, this also allows for the compensation, for example, of circumferential tolerances between different production batches of the belt.

[0010] In principle, it is possible to arrange the axis of rotation (via which the drive motor is mounted at the lower roller carrier) and the lower roller and drive motor such that their drive shaft axes and rotation axes have different orientations. However, according to a preferred embodiment of the invention, at least one drive motor is pivotally mounted at the lower roller carrier such that the axis of rotation, the drive shaft axis of at least one drive motor, and the associated rotation axis of the lower roller are arranged parallel to each other. This embodiment of the invention not only ensures easy adjustment of the belt tension but also ensures reliable power transmission from the drive motor to the lower roller. Furthermore, the corresponding embodiment also ensures that the belt tension increases or decreases proportionally to the pivoting motion of the drive motor about the axis of rotation.

[0011] The degree of displacement of the drive motor at the lower roller carrier, i.e., the pivotability of the drive motor about its axis of rotation, can in principle be designed arbitrarily. However, according to a preferred embodiment of the invention, at least one drive motor at the lower roller carrier is arranged to be displaceable between a final position for determining the maximum distance from the lower roller and an initial position for determining the minimum distance from the lower roller. A corresponding embodiment of the invention ensures that when the drive motor is positioned in the area of ​​the initial position, the drive belt can be easily positioned at the drive motor and the associated lower roller. Furthermore, the final position also ensures that the belt tension does not exceed the maximum tension. Moreover, the limited displacement range of the drive motor reliably avoids mispositioning, which could otherwise damage the drive motor or adjacent units of the drafting device.

[0012] The orientation of the drive motor, particularly its axis of rotation, relative to the lower roller at the lower roller holder can, in principle, be accomplished in any manner, as long as it is ensured that a change in distance occurs between the drive motor and the lower roller when the drive motor pivots about its axis of rotation. According to a preferred embodiment of the invention, the drive motor is pivotally arranged at the lower roller holder such that, at an intermediate position coinciding with the initial and final positions, the plane unfolded by the axis of rotation and the associated drive shaft axis is perpendicular to the plane unfolded by the associated drive shaft axis and the associated lower roller's axis of rotation.

[0013] This embodiment of the invention ensures that the displacement movement of the drive motor from the intermediate position to the final or initial position consistently increases or decreases the belt tension. In both displacement directions, the displacement path is proportional to the increase or decrease in belt tension. Furthermore, the corresponding embodiment ensures an extremely compact design of the drafting device and good accessibility of the drive motor, thereby enabling comfortable adjustment of the belt tension.

[0014] The displacement of the drive motor can be achieved in any manner to adjust the tension of the transmission belt. According to a preferred embodiment of the invention, the drive motor is configured such that it has a sleeve bolt extending parallel to the associated support bolt at the lower roller, wherein the support bolt and the associated sleeve bolt are arranged spaced apart from each other such that changes in the distance between the sleeve bolt and the support bolt cause displacement of the drive motor between an initial position and a final position.

[0015] According to this preferred embodiment of the invention, at least one drive motor is located at the lower roller, or if there are more than one drive motor, a support bolt is preferably assigned to each drive motor, the support bolt being arranged in a fixed position at the lower roller. Furthermore, each drive motor, whether at least one or more, preferably has a connecting bolt extending parallel to the corresponding support bolt. Thus, the drive motor can be positioned via variations in the distance between the connecting bolt and the support bolt. Therefore, this embodiment of the invention makes it possible, for example, to use a gauge with openings for the connecting bolt and the support bolt. The distance between these openings is here allocated to a defined belt tension, thereby allowing the gauge to be used for adjusting and checking the belt tension. To adjust the belt tension, it is only necessary to arrange the connecting bolt relative to the support bolt such that the connecting bolt aligns with the opening in the gauge.

[0016] Furthermore, the support bolts and socket bolts enable the use of compatible tools to adjust the distance between them, thereby allowing for reliable adjustment of the drive belt tension. According to a preferred embodiment, the socket bolt extends through a recess at the lower roller holder, wherein the recess is designed, for example, as an elongated hole, through which reliable guidance of the socket bolt can be comfortably ensured, and the final and initial positions can be precisely determined.

[0017] According to a preferred embodiment, the lower roller holder has an upper side and a lower side, wherein the lower roller is arranged to be mounted on the upper side of the lower roller holder, and a support element is provided projecting perpendicularly from the lower side, at which at least one drive motor is mounted. A drive belt extends from the drive motor to the associated lower roller across the lower and upper sides of the lower roller holder. According to a preferred embodiment, the lower roller holder and the support element can be formed in one piece or in multiple pieces. In a multiple-piece embodiment, the lower roller holder and the support element are further preferably connected or coupled to each other by common connecting and / or coupling elements.

[0018] According to a preferred embodiment, the lower roller carrier has a channel through which the drive belt extends. Preferably, the channel may be designed as an opening in the lower roller carrier, which is partially or completely surrounded by an edge. In the embodiment where the edge is partially surrounded, the opening edge used to surround the opening, and thus limit the opening, preferably also forms the edge side of the lower roller carrier. This makes it possible to easily access the channel from the edge side of the lower roller carrier. Equally preferably, a recess is provided in the lower roller carrier or its support element, through which the sleeve bolt preferably passes.

[0019] In principle, at least one drive motor can be fixed in the adjusted position in any manner. According to a preferred embodiment of the invention, the lower roller has at least one recess for receiving at least one stop bolt extending through the lower roller to fix at least one drive motor in the adjusted position. According to this embodiment, to fix the drive motor in the adjusted position, at least one bolt passes through the recess in the lower roller and is tightened onto the drive motor, thereby clamping the drive motor in the adjusted position via the bolt. The recess is sized such that the drive motor can be fixed in all predetermined positions between the initial and final positions.

[0020] Furthermore, the use of socket bolts and support bolts according to an advantageous improvement of the invention makes it possible to adjust the tension of the drive belt of the traction device using the belt tensioner according to the invention. The belt tensioner has two halves of the clamp, which are pivotally connected to each other via hinge bolts. One end of each half of the clamp is designed as a handle, and the other end each has a functional element, which together form a functional element pair. These functional elements are arranged in the same plane of motion and can be moved toward each other by manipulating the half-clamps. The belt tensioner according to the invention is characterized by a pre-tensioning element that pre-tensions the functional elements toward each other with a defined pre-tensioning force. These functional elements are designed as inserts for receiving support bolts and socket bolts and extend perpendicular to the plane of motion.

[0021] This embodiment of the belt tensioner according to the invention makes it possible to comfortably adjust the tension of the drive belt using the belt tensioner, which has insert sleeves designed to accommodate support bolts and sleeve bolts, through which the drive motor of the tensioning device can be displaced relative to the associated lower roller to tension the drive belt.

[0022] According to the present invention, the distance between the support bolt and the sleeve bolt is determined by the pre-tensioning element that pre-tightens the insert sleeve towards each other, and thus the positioning of the drive motor at the lower roller. By correspondingly selecting the pre-tensioning element, after the belt tensioner is arranged at the relevant support bolt and sleeve bolt using the insert sleeve, the belt tension is reliably and automatically adjusted according to the pre-tensioning force applied by the pre-tensioning element and acting on the drive belt. After the belt tensioner is arranged, the drive motor can be fixed in a predetermined position by the belt tensioner without further manual displacement of the half-clamp, thereby achieving accurate positioning of the drive motor with a predetermined belt tension.

[0023] The tension applied by the belt tensioner to the support bolts and socket bolts, and thus to the drive belt, and the positioning of the drive motor at the lower roller, depend on the preload generated by the preload element and the distance between the insert sleeve and the hinge bolt of the belt tensioner. Therefore, the interchangeability of the advantageously arranged preload element makes it possible to adjust the drive belt tension generated by the belt tensioner. According to a preferred embodiment of the invention, the functional elements in a functional element pair are further arranged at the same distance from the hinge bolt. This embodiment of the invention particularly prevents erroneous operation of the belt tensioner because, according to this embodiment, the location of the support bolts and socket bolts at which insert sleeve is irrelevant.

[0024] According to another embodiment of the invention, at least two pairs of functional elements with different distances from the hinge bolt are arranged at the other end of the half-clamp. Since the distances between the sockets of the at least two pairs of functional elements and the hinge bolt are different, different preloads can be transmitted to the support bolts and associated socket bolts using the belt tensioner, depending on the number of functional element pairs, without replacing the preload elements. Therefore, a corresponding embodiment of the belt tensioner makes it possible to use the belt tensioner alone to adjust the drive belt tension at the traction devices where several drive motors operate with different drive belt tensions.

[0025] The implementation of the preload element is, in principle, free to be chosen, as long as it generates a preload force that preloads the insert sleeves toward each other. For example, this preload can be achieved by a compression spring arranged in the handle area. However, according to a preferred embodiment of the invention, the preload element is designed as a tension spring, which is arranged in the half-clamp area between the functional element pair and the hinge bolt. The use of a tension spring ensures the defined preload of the insert sleeves of the functional element pair in a particularly simple and reliable manner. Furthermore, the tension spring can be replaced particularly easily when appropriate, thus allowing the belt tensioner to be used to apply different tension forces.

[0026] Furthermore, the present invention also achieves its purpose through a system for tensioning a drive belt in a tensioning device, the system having

[0027] -The drawing device described above according to the present invention or further improvements, and

[0028] -The belt tensioner according to the present invention or further improvements thereof, wherein,

[0029] - The insert sleeve located at the belt tensioner is designed to fit with the sleeve bolt and the support bolt.

[0030] The system according to the invention, consisting of a drafting device and a belt tensioner, allows for the adjustment of the belt tension of the drive belt connecting the lower roller to the drive motor in a particularly simple and reliable manner. It is particularly advantageous that the pre-tensioning element at the belt tensioner is designed such that the belt tensioner, located at the support bolts and sleeve bolts, pre-tensions the drive belt to a predetermined belt tension. This corresponding system of drafting device and belt tensioner makes it possible for the machine operator to set the required belt tension for operation in a particularly simple and reliable manner. Therefore, after the belt tensioner ensures reliable belt tension, the drafting device can be set, maintained, and serviced in a particularly simple manner. Furthermore, no additional tools are required for subsequent belt tension checks.

[0031] According to a preferred embodiment of the invention, the drafting device has at least two pairs of rollers, each pair having a drive motor connected to the lower roller, and the belt tensioner has two pairs of functional elements for adjusting different belt tensions. According to this embodiment of the invention, the belt tensioner can apply different preloads to the sleeve bolt and the support bolt via the two functional elements, each having a socket arranged at a different distance from the hinge bolt. This makes it possible to adjust the drafting device of the drive belt with different desired drive belt tensions using the belt tensioner. According to this embodiment of the invention, the tension of the second drive belt can be adjusted without using a separate belt tensioner.

[0032] An embodiment of the present invention will now be described with reference to the accompanying drawings. Wherein:

[0033] Figure 1 This is a perspective schematic diagram of the first embodiment of the drawing device.

[0034] Figure 2 This is a perspective view of the lower part of the drawing device according to the second embodiment of the drawing device.

[0035] Figure 3 for Figure 2 Another perspective view of the lower part of the drawing device.

[0036] Figure 4 for Figure 2 A perspective view of the lower section of the drawing device.

[0037] Figure 5 for Figure 2 A perspective view of the first drive motor at the bottom of the middle drawing device.

[0038] Figure 6 for Figure 2 A perspective view of the second drive motor at the bottom of the middle drawing device.

[0039] Figure 7 This is a perspective view of a belt tensioner according to one embodiment.

[0040] Figure 8 for Figure 2 The lower part of the middle drawing device and Figure 7 A perspective diagram illustrating the first common action of the belt tensioner, and...

[0041] Figure 9 for Figure 2 The lower part of the middle drawing device and Figure 7 A perspective diagram illustrating the second combined action of the belt tensioner.

[0042] exist Figure 1 The diagram shows a perspective view of a drafting device 17, which can be assigned to a spinning position on a textile machine (not shown) and can be fixed on the textile machine via a locking hook 21. The drafting device 17 here has an upper drafting device 19, which is hinged to a lower drafting device 18a, and is pivoted via a control handle 20.

[0043] exist Figure 1 In the operating position shown, the upper part 19 of the drafting device abuts against the corresponding driven lower rollers 2a and 2b of the lower part 18a of the drafting device. The upper part of the drafting device has four upper rollers arranged sequentially in the direction of travel of the fiber strip (not shown here) through the drafting device 17.

[0044] The second embodiment of the lower part 18b of the drawing device is in Figure 2 and Figure 3As shown in the perspective view, the lower part 18b of the drafting device has two lower rollers 2a and 2b, which are rotatably mounted on the upper side of the lower roller frame 1 via the lower roller bearing 5. To drive the lower rollers 2a and 2b, the lower part 18b of the drafting device has two drive motors 16a and 16b, each assigned to one of the lower rollers 2a and 2b. The drive motors 16a and 16b are each pivotally mounted on the support element 1b via hinge bolts 11a and 11b, which extend through bushings 12a and 12b at the support element 1b of the lower roller frame 1. The support element 1b is plate-shaped and extends perpendicularly from the lower side 1c of the lower roller frame 1. According to this preferred embodiment, the lower roller frame 1 and the support element 1b are designed as a single piece, in other words, they form a single unit. According to a preferred embodiment (not shown), the lower roller frame 1 and the support element 1b can be implemented as multiple pieces and connected or coupled to each other via common coupling or connecting elements. Two drive belts 3a, 3b are used to transmit the drive motion of the drive motors 16a, 16b to the lower rollers 2a, 2b. Each of these two drive belts is wound around the pulley 4 of the drive motors 16a, 16b and the lower rollers 2a, 2b. They each extend across the lower side 1c and upper side 1b of the lower roller frame 1 through corresponding channels of the lower roller frame 1.

[0045] In order to adjust the tension of the drive belts 3a and 3b, the drive motors 16a and 16b can pivot via predetermined rotation axes 7a and 7b of the hinge bolts 11a and 11b, thereby adjusting the distance between the pulleys 4 of the lower rollers 2a and 2b and the corresponding pulleys 4 of the drive motors 16a and 16b.

[0046] To adjust the position of drive motors 16a and 16b relative to lower rollers 2a and 2b at lower roller frame 1, support bolts 13 and sleeve bolts 14, fixedly arranged at support element 1b, are provided at drive motors 16a and 16b. These support bolts 13 are connected to the corresponding support bolts 13. Figure 2 and Figure 3 In the embodiment shown, the socket bolt 14 extends through the elongated hole 9b or the recess 33, and... Figure 4In the illustrated embodiment, elongated holes 9a and 9b extend through the support element 1b, thereby arranging the support bolt 13 and the sleeve bolt 14 in a plane and aligning them parallel to each other. The recess 33 differs from the elongated holes 9b or 9a and 9b in that it extends to the edge side of the support element 1b, thus forming the edge side of the support element 1b or the lower roller 1, thereby enabling accessibility via the edge side. The length of the elongated holes 9a and 9b or the recess 33 restricts the displacement movement of the drive motors 16a and 16b. The distance between the support bolt 13 and the sleeve bolt 14 defines the position of the drive motors 16a and 16b at the support element 1b of the lower roller frame 1. The adjusted positions of the drive motors 16a and 16b are each locked by a stop bolt 15, which passes through additional elongated holes 10a, 10b, 22a, and 22b and is screwed into the openings 23 in the corresponding drive motors 16a and 16b. This clamps the drive motors 16a and 16b to their adjusted positions at the support element 1b (see...). Figure 5 and 6 ).

[0047] exist Figures 2 to 4 The intermediate position shown (in this intermediate position, the sleeve bolt 14 is arranged at the same distance from both ends of the elongated holes 9a and 9b, see reference) Figure 4 The rotation axes 7a and 7b, together with the drive shaft axes 8a and 8b of the associated drive motors 16a and 16b, unfold into a plane that is perpendicular to the plane unfolded by the drive shaft axes 8a and 8b and the rotation axes 6a and 6b of the associated lower rollers 2a and 2b, wherein the drive shaft axes 8a and 8b, the rotation axes 6a and 6b, and the rotation axes 7a and 7b are parallel to each other.

[0048] Figure 7 The belt tensioner 24 shown in the perspective view is used to adjust the belt tension of drive belts 3a and 3b. It has two half-clamps 26a and 26b, which are hinged together via a hinge bolt 25. On one side of the hinge bolt 25, each half-clamp 26a and 26b forms a handle 27; conversely, on the side opposite the handle 27, each half-clamp 26a and 26b has two functional elements spaced apart and designed as insert sleeves 28a and 28b. The functional elements 28a and 28b each form a pair of functional elements 31a and 31b, which are preloaded towards each other with a defined preload force via a preload element designed as a tension spring 30. Due to the different distances between the functional elements 28a and 28b and the hinge bolt 25, the pairs of functional elements 31a and 31b transmit different preload forces via the insert sleeves 28a and 28b.

[0049] The insertion sleeves 28a and 28b are adapted to the sleeve bolts 14 and support bolts 13 of the lower part 18b of the stretching device, thereby enabling the belt tensioner 24 (such as...) Figure 8 and Figure 9 (As shown) can be used to adjust the belt tension of drive belts 3a and 3b. Figure 8 In the illustrated embodiment, the functional element pair 31b is used to adjust the belt tension of the drive belt 3b that connects the second lower roller 2b to the drive motor 16b. Since the belt length of the first drive belt 3a differs from that of the second drive belt 3b, the belt tensioner 24 must apply different preloads to the socket bolt 14 and the support bolt 13 to achieve the desired belt tension, thus adjusting the drive motor 16a. For this purpose, the belt tensioner 24 utilizes the insertion sleeve 28a of the functional element pair 31a positioned at the support bolt 13 and socket bolt 14 connected to the drive motor 16a.

[0050] The preload is determined by a tension spring 30, which is located at a support 32 in the area between the hinge bolt 25 of the half clamps 26a and 26b and the functional element pairs 31a and 31b. The tension spring 30 is fixed at the support 32 in an interchangeable manner, so that the belt tensioner 24 can be used to adjust different preloads by changing the tension spring 30.

[0051] Appendix Label Table

Claims

1. A drafting device (17) for a spinning machine, comprising: at least two pairs of rollers, each pair having an upper roller and a lower roller (2a, 2b); and at least one drive motor (16a; 16b) for driving at least one of the lower rollers (2a; 2b), wherein, The at least one drive motor (16; 16b) and the lower roller (2a; 2b) that can be driven by the at least one drive motor (16; 16b) are arranged to be mounted at the lower roller holder (1), wherein the at least one drive motor (16a; 16b) connected to the lower roller (2a; 2b) via a transmission belt (3a; 3b) is arranged at the lower roller holder (1) at a variable distance from the lower roller (2a; 2b) to adjust the transmission belt tension. Its features are, The at least one drive motor (16a; 16b) is mounted on the lower roller bracket (1) in a manner that allows it to pivot about a rotation axis (7a; 7b) and be fixed in an adjusted position, thereby adjusting the distance between the lower roller (2a; 2b) and the at least one drive motor (16a; 16b). The at least one drive motor (16a; 16b) has a sleeve bolt (14) extending parallel to an associated support bolt (13) at the lower roller (1), wherein the support bolt (13) and the associated sleeve bolt (14) are arranged spaced apart from each other such that a change in the distance between the sleeve bolt and the support bolt causes displacement of the drive motor (16a; 16b) between an initial position and a final position.

2. The drawing device (17) according to claim 1, characterized in that, The at least one drive motor (16a; 16b) is pivotally mounted on the lower roller frame (1) such that the rotation axis (7a; 7b), the drive shaft axis (8a; 8b) of the at least one drive motor (16a; 16b) and the rotation axis (6a; 6b) of the associated lower roller (2a; 2b) are arranged parallel to each other.

3. The drawing device (17) according to claim 1, characterized in that, The at least one drive motor (16a; 16b) is arranged at the lower roller frame (1) to be displaced between the final position for determining the maximum distance from the lower roller (2a; 2b) and the initial position for determining the minimum distance from the lower roller (2a; 2b).

4. The drawing device (17) according to claim 2, characterized in that, The at least one drive motor (16a; 16b) is pivotally arranged at the lower roller (1) such that, at an intermediate position corresponding to the distance between the initial position and the final position, the plane unfolded by the rotation axis (7a; 7b) and the associated drive shaft axis (8a; 8b) is perpendicular to the plane unfolded by the associated drive shaft axis (8a; 8b) and the rotation axis (6a; 6b) of the associated lower roller (2a; 2b).

5. The drawing device (17) according to claim 1, characterized in that, The connecting bolt (14) extends through the recess (9a; 9b; 33) at the lower roller (1).

6. The drawing device (17) according to claim 5, characterized in that, The recess (33) forms the edge side of the lower roller frame (1).

7. The drawing device (17) according to any one of claims 1 to 6, characterized in that, The lower roller holder (1) has an upper side (1b) and a lower side (1c), wherein the lower rollers (2a; 2b) are arranged to be mounted on the upper side (1b) of the lower roller holder (1), and a support element (1a) is provided protruding perpendicularly from the lower side (1c) to the lower side (1c), at which at least one drive motor (16a; 16b) is mounted, wherein the drive belt (3a; 3b) extends from the drive motor (16a; 16b) to the associated lower roller (2a; 2b) across the lower side (1c) and the upper side (1b) of the lower roller holder (1).

8. The drawing device (17) according to claim 7, characterized in that, The lower roller (1) has at least one channel (1e) through which the drive belt (3a; 3b) extends.

9. The drawing device (17) according to any one of claims 1 to 6, characterized in that, The lower roller holder (1) has at least one elongated hole (10a; 10b; 22a; 22b) for receiving at least one stop bolt (15) extending through the lower roller holder (1) to fix the at least one drive motor (16a; 16b) in the adjusted position.

10. A system for tensioning a drive belt (3a; 3b) of a drafting device (17), the system having a drafting device (17) according to any one of claims 1 to 9 and a belt tensioning clamp (24) for adjusting the tension of the drive belt of the drafting device (17), the belt tensioning clamp having two half-clamps (26a, 26b) pivotally connected to each other via a hinge bolt (25), one end of each half-clamp being designed as a handle (27), and the other end each having a functional element (28a, 28b), the functional elements forming a functional element pair (31a, 31b), the functional elements being arranged in the same plane of motion and movable toward each other by manipulating the half-clamps (26a, 26b), wherein, The preload element (30) preloads the functional elements (28a, 28b) toward each other with a defined preload force. The functional elements are designed to accommodate the inserts of the support bolt (13) and the socket bolt (14), and extend perpendicular to the plane of motion. Its features are, The insert sleeves (28a, 28b) arranged at the belt tensioner (24) are adapted to the sleeve bolts (14) and support bolts (13) at the stretching device (17).

11. The system according to claim 10, characterized in that, The pretensioning element (30) at the belt tensioner (24) is designed such that the belt tensioner (24) arranged at the support bolt (13) and the sleeve bolt (14) pretensions the drive belt (3a, 3b) with a predetermined belt tension.

12. The system according to claim 10 or 11, characterized in that, The drafting device (17) has two roller pairs, each of which has a drive motor (16a, 16b) connected to the lower roller (2a, 2b), and the belt tensioner (24) has two pairs of functional elements (31a, 31b) for adjusting different belt tensions.

Images