JP2010514945A - Machine loom backrest - Google Patents

Abstract

The invention relates to a back rest (1) for a mechanical loom, wherein the warp thread movements in the warp direction are leveled out by a thread deflection element that is arranged on a mass-optimized spring leaf so as to be able to oscillate. For this purpose, a base (4) of the back rest is arranged in a mechanical loom frame (5), at least one spring leaf (6) is rigidly connected to the base (4) on a mounting side (7) and at least one thread deflection element (10) guiding the warp threads is arranged on an exterior (8) of the spring leaf opposite the mounting side (7). The mass of the spring leaf (6) in relation to a unit of length decreases towards the exterior (8) of the leaf spring (6).

Description

  The invention relates to a loom backrest according to the preamble of claim 1.

  Such a backrest is composed of several parts, some of which may be fixed, and others may be provided so that they can operate and vibrate.

  The problem of such an unfavorable dynamic behavior of the backrest, in which the backrest's vibratable parts have a large moment of inertia, has already been described in German Patent Publication No. 3346030A1. In addition to the continuous and continuous movement of the warp resulting from the weaving into the woven fabric, the warp is excited mainly by the additional action and vibration due to the impact of the warp opening and the weft strike.

  The vibrable part of the backrest is subjected to movement and vibration in the warp moving direction due to movement and tension fluctuation caused by the warp. If it is assumed here that the vibrable part of the backrest is unable to follow the warp operation substantially without an appropriate phase shift due to its moment of inertia, the warp tension fluctuation is further amplified and a very high warp load is applied. appear. This warp load is particularly high if relatively hard warp materials are included. This results in a difference between excitation (eg opening motion) and system response (backrest motion) with an unbalanced and significant increase in warp tension, which is caused by the phase shift and elongation of the connected warp material as described above. .

  In addition to the quality of the product being reduced due to excessive stretching or excessive elongation of the warp and breakage of the warp, the loom is caused by the stop time caused by warp breakage or entanglement between warps due to lower warp tension. As a result, the rate of operation will also decline.

  In order to remedy these problems, German Patent Publication No. 3346030A1 is a loom equipped with a backrest, which is contacted by a warp sheet and vibrates in at least one elastic element of the backrest. A loom is provided having a thread deflection element supported in a possible manner.

  In order to reduce the weight of the yarn deflecting element and thereby further reduce the moment of inertia of the movable part of the backrest, in DE 33 46 030 A1, the width direction of the yarn deflecting element measured perpendicular to the warp Thus, it has been further proposed to distribute several elastic elements uniformly. This is because the yarn deflecting element can be made harder and lighter by doing so.

  German Offenlegungsschrift 3,346,030 A1 describes various possibilities for realizing an elastic element. For example, a part made of an elastomer material can be used, or a part made of a hard material having a shape that achieves a predetermined elasticity can be used. In particular, a leaf spring has been proposed as an elastic element.

  According to experience, the above-mentioned problems can only be solved in a limited rotational speed range by the solution described in German Patent Publication No. 3346030A1. Even at the high rotation speed of 500 revolutions per minute in the current loom, even the moment of inertia of the vibration component of the backrest reduced by the above-described measures is too high to follow the motion profile added from the outside. This is indicated, for example, by the removal of the warp from the yarn deflection element, for example, at a given phase of the weaving cycle, when using very hard warp materials such as aramid or glass. For this reason, fluctuations in the progress of the warp tension and in particular the maximum value of the warp tension are further amplified or increased. As a result, the above-described problem occurs again.

  Therefore, the underlying objective of the present invention is to ensure durable and stable or reliable operation and to ensure that the product is of high quality even when the loom is at a high rotational speed. To provide a backrest for the loom.

  The entire feature recited in claim 1 achieves the solution of this object according to the invention.

  The at least one yarn deflection element is fixed to the backrest base body in a oscillating manner via at least one leaf spring. For this reason, the leaf spring is fixedly connected to the base body on the mounting side. The yarn deflection element is provided on the outer side of the at least one leaf spring located on the opposite side of the mounting side. The leaf spring is configured to have a low weight in the outer region so that the yarn deflection element can follow the very fast rotational operation of the warp yarn when the loom is at a high rotational speed. That is, the weight with respect to the unit length of the leaf spring decreases from the mounting side toward the outside. In this connection, the weight per unit length of the leaf spring does not necessarily have to decrease continuously towards the outside, it decreases in steps and / or only part of the overall length of the leaf spring. May decrease.

  This leaf spring embodiment reduces the moment of inertia of the translational part of the motion and the moment of inertia of the rotational part of the motion to an optimum value. As a result, it is possible to achieve a high natural frequency aimed at by the backrest capable of vibration.

  Reducing the outer weight of the leaf spring that operates faster has a particularly advantageous effect. This is because the acceleration acting against the inertial mass and the moment of inertia is particularly high there.

  This enhances the ability of the yarn deflection element to follow the warp operation without substantially proper phase shift. Such an embodiment can have a beneficial effect on the progress or progress of the warp tension. Especially when the rotational speed of the loom is high, the tension peak is reduced and the penetration or disappearance of the tension is prevented.

  The leaf spring referred to in the present invention is not necessarily configured integrally. In particular, leaf springs stacked in multiple layers are also included in the term leaf spring here.

  In a preferred embodiment of the present invention, the leaf spring has a structure having substantially the same or uniform thickness and decreasing in width toward the outside. For this reason, as a leaf | plate spring which can be produced easily, it has a triangular or trapezoid shape, for example. However, depending on the characteristics of the preferred leaf spring, the width of the leaf spring may decrease towards the outside based on a specific mechanical function. Further, the leaf spring may decrease in width with the thickness toward the outside, or the leaf spring may decrease only in thickness.

  The advantages of these leaf spring embodiments can be recognized by considering the tension distribution within the leaf spring. Due to the fact that the leaf spring is firmly fixed or attached to the base body, the highest bending moment is produced in this attachment-side region while the leaf spring is bent by warp movement. Due to the leaf springs becoming narrower or thinner towards the outside, the highest bending moment occurs in the widest or thickest region of the leaf springs, i.e. the mounting side. The bending moment that decreases toward the outside of the leaf spring is generated in a relatively narrow or thin portion of the leaf spring so as to correspond thereto. Thereby, the tension distribution in the leaf spring is made uniform as compared with, for example, a general leaf spring. In this way, it is possible to achieve an optimum material utilization for the reduction of the moment of inertia in relation to the strength requirements of the leaf spring.

  The spring function and the thread guide function are separated and assigned to each component, that is, the spring function is assigned to the leaf spring and the thread guide function is assigned to the yarn deflection element. It can be optimized in relation to the assigned function. For example, since the yarn deflection element is in direct contact with the warp, the yarn deflection element is optimized with respect to its surface properties. The surface properties of the yarn deflection element are therefore of considerable importance in the light of product quality.

  With regard to product changes, it is advantageous in that the yarn deflection elements can be easily and quickly exchanged for different yarn deflection elements whose surface properties are suitable for new products. The product can be changed more simply and quickly if the deflecting element is fixed or attached so that it can be easily removed from the leaf spring in the sense that it is connected for quick exchange. For this purpose, for example, a groove may be provided outside the at least one leaf spring, in which the deflection element is simply slidably mounted by means of a pair of pieces and firmly screwed or fastened. .

  On the other hand, efforts on the surface properties of leaf springs can be reduced to the benefit of making leaf spring products simple and advantageous. The reason is that the leaf spring does not contact the warp.

  A further aspect of the present invention is manifested by the use of several leaf springs arranged to be distributed over the width direction of the yarn deflection element extending perpendicular to the warp. With respect to changing the width of the product, a corresponding number of leaf springs in the end region can simply be removed or added to adapt the backrest to the changed product width. Thereby, it is possible to keep the spring characteristics of the backrest the same for the products of various widths with a little effort. In a further preferred embodiment, this results in a further advantage of the invention when the leaf spring is realized with different spring stiffness. By using a combination of several leaf springs with a hard yarn deflection element and different spring stiffnesses, the overall spring stiffness of the leaf springs that exerts an effect on the warp sheet is influenced as intended, And it is adjusted to a predetermined value.

  In that regard, a large selection of leaf springs with different spring stiffnesses can be set to allow for adjustment of a number of overall spring stiffnesses by making a good or clever combination and arrangement.

  By distributing the spring function and the thread guiding function for the leaf spring and the thread deflection element as described above, it is possible to optimally configure both components for each function and to reduce the mass as much as possible.

  For example, by using several leaf springs, when the yarn deflection element is supported at several locations in the warp width direction, the yarn deflection element is supported only at the end. Thus, the yarn deflection element can be realized with a relatively low strength and with it a relatively low mass.

  The yarn deflection element can be composed of, for example, lightweight synthetic plastic, fiber reinforced synthetic plastic, or other composite material. At the same time, the mass of the vibratable parts of the backrest is further reduced and the natural frequency of the device is increased.

  In a further preferred embodiment relating to the use of several leaf springs, the leaf spring in the end region of the yarn deflection element has a different spring stiffness compared to the leaf spring in the central region of the yarn deflection element. .

  In this way, undesired warp length fluctuations and thus the deviation of the warp tension in the end region are either completely offset or equalized or at least minimized. In this connection, it is advantageous if a multi-part or flexible yarn deflection element is provided.

  Similarly, in this embodiment, it is also possible to realize a shift in warp tension of the warp at the end, thereby realizing an advantageous weaving state in the end region of the woven fabric. Different shrinkage or weaving of the warp in the end region requires such means compared to the warp in the underlying fabric. This has, for example, a woven fabric with interwoven fabric ears, having a different weaving type different from the region of the fabric ears woven within the underlying fabric, thereby comparing to the remaining region of the woven fabric Thus, the optimum warp tension occurs in the region of the fabric ear.

  A different aspect of the invention consists of a superposition of the second movement with respect to the spring movement of the leaf spring. The superimposed second movement is preferably performed by the whole base body on which the component is mounted.

  For this reason, the base body of the backrest is movably arranged on the loom frame and is preferably actuated by the drive unit. For this reason, this drive is drawn from the main drive of the loom via drive means, or a separate drive for the movement of the base body movement is provided on the backrest.

  In this regard, the base body performs a translation operation together with the rotation operation. An electric, hydraulic, or pneumatic actuator can be used as the separate drive unit.

  In a preferred embodiment according to the present invention, the base body can be rotated with respect to a horizontal axis perpendicular to the warp direction by, for example, an electric drive unit, so that the leaf spring is rotated around an axis located in the vicinity of the attachment side. Can be rotated. Thereby, it is possible to positively influence the progress or progress of the warp tension at different phases of each weaving cycle.

  Furthermore, the second movement superimposed on the leaf spring movement can also be realized by a mounting element, which is on the mounting side of the leaf spring in order not to move all of the base body, It is arranged on the base body so as to be movable, for example, tiltable.

  A movably driven backrest is already known under the name "active backrest system", which is generally used in a similar way to compensate or flatten warp tension variations.

  Normal tension fluctuations repeated in each weaving cycle, for example tension fluctuations caused by opening formation, can be compensated or flattened most extensively or greatly by the active backrest system. Further, the leaf spring according to the present invention compensates for the generated warp length shift and tension peak (which occurs within a short temporary time). The drive part of the active backrest cannot react to the tension peak caused by it, for example, by hammering, in a reasonable time. In addition, fluctuations that cannot be predicted from the expected tension progression are compensated or flattened by the leaf springs.

  In terry weaving, when accompanied by such superimposed movements, fluctuations in tension of pile warp or ground warp can be reduced by actively introduced backrest movement. And at the same time, unpredictable tension fluctuations with extremely rapidly occurring tension peaks are compensated or flattened by the leaf springs. In addition, the pile or ground warp tension can be actively increased while weaving flat areas such as edges. Also, during terry weaving, the tension can be reduced again to obtain a uniform pile formation in the terry region.

  Tension progression in terry looms and other loom types of warp yarns can also be positively influenced by such embodiments. Thus, in order to obtain an improved fabric appearance, the ground warp yarns of a terry loom can be driven temporarily at high tension, for example for each complete beat-off time.

  There is a particularly advantageous application of this embodiment with superimposed movements at each stop of the loom. It is advantageous, especially during long stops of the loom, because the warp tension can be reduced in order to avoid unwanted damage of the warp. Such damage often leads to so-called start-up marks on the woven fabric and thereby leads to considerable quality degradation. In order to avoid this, at each machine stop, the base body is turned or slid to a direction in which the warp tension is lowered until it falls below a preset value.

  To start the loom again, unloading or tension removal is again stopped and the base body is swung or slid in the opposite direction until the warp tension required for the weaving operation is reached. This generates an almost jumping motion or a predetermined time corresponding to a ramp function. In the latter case, the warp tension increases continuously or stepwise until the desired value is reached.

  A different possible warp tension adjustment method during restart of the loom is, for example, to make the warp excessively short-term during the initial weaving beating. For this reason, before the first weaving operation, the warp tension is set to a value exceeding the warp tension value for the weaving operation, and thereafter, the warp tension is reduced in accordance with the specified progress or progress.

  The selection of an appropriate starting method for restart depends on the warp material, the weaving type, and other factors. Appropriate tension measuring elements are well known as adjustment devices necessary for tension removal and re-tensioning and are therefore not described in further detail here.

  A further preferred embodiment of the invention includes at least one mechanical stop for limiting the movement of the yarn deflection element. This may be securely attached to the loom frame or may be configured to be adjustable. With the stop member, the spring-loaded backrest can be a rigid backrest or the spring action of the leaf spring can be limited to a defined value. The effect of the stop member may be turned on and off manually or by a corresponding drive. A controlled drive for actuating the stop member allows, for example, a weaving operation performed in a predetermined phase by a rigid backrest and a weaving operation performed in another phase by a spring-loaded backrest. To do.

  The stop member may be actuated by superimposing the second movement described above on the spring movement of the leaf spring. For this reason, the base body of the backrest, which is movably mounted on the loom and to which the leaf spring is fixed, is driven in the direction of the stop member firmly attached to the loom until it acts on the leaf spring. The

  According to a further preferred embodiment of the invention, the second stop member is provided on the side opposite to the first stop member relative to the leaf spring. Since there is one stop member on each side of the leaf spring, the movement of the leaf spring is restricted not only when unloading the leaf spring but also when applying a load. When applying a load to a leaf | plate spring, a stop member plays the role which prevents that the load of a leaf | plate spring becomes excess.

  For example, in order to relieve or reduce the warp tension while the machine is stopped, the warp is fed out from, for example, a warp beam. The leaf spring is relaxed or tensioned and moves until it abuts the corresponding stop member. As soon as the leaf spring comes into contact with the corresponding stop member during tension removal and further while the warp is fed out, the warp tension goes to zero in such a way that it almost jumps. In this case, the warp tension is sharply reduced without feeding the warp from the warp beam so long.

  The last tension removal step can be performed by sending the cloth instead of the warp until the leaf spring comes into contact with the stop member, or by sending the warp along with the cloth. it can.

  The yarn deflection element preferably consists of a laterally extending batten or bar and is firmly attached to the leaf spring. However, in other preferred embodiments, the yarn deflection element is movably attached to the leaf spring and may be constructed from different shapes. If, for example, a deflection roller is used as the deflection element, the warp yarn no longer slides on the surface of the yarn deflection element, but rather rolls on the surface. In such an embodiment, it is possible to prevent an additional warp tension from being generated due to the sliding frictional force between the warp and the deflection element.

  Damping means acting on the leaf springs characterize a further preferred embodiment of the invention. If a laminated leaf spring is already used, a predetermined damping behavior is caused. In addition, one or more thin friction layers are available between each layer to adjust and set for a predetermined attenuation.

  The present invention includes a loom having the above-described backrest and a leaf spring used for such a backrest.

  The invention and further advantages resulting therefrom will be described in more detail in connection with embodiments.

The perspective view which shows the backrest by this invention containing the structure in the loom frame. 1 is a side view of a loom according to the present invention having a backrest. The enlarged view of the backrest in FIG. The graph which compares progress of warp tension between the conventional backrest and the backrest by this invention.

  The configuration and structure of the backrest according to the present invention is shown in FIGS. 1, 2, and 3. FIG.

  The warp yarn 9 from the warp beam 2 passes over the backrest 1 and reaches the opening means 3, and finally is wound as a woven fabric on a cross beam (not shown).

  In the illustrated embodiment, the base body 4 of the backrest 1 is connected to the loom frame 5 via base body support portions 15 and 15 '. Thereby, the backrest 1 having the base body 4 can slide in the vertical direction via the linear motion guides 11 and 11 ', and can slide in the horizontal direction via the linear motion guides 13 and 13'. is there. However, during the weaving operation, the backrest 1 is fixed in its predetermined position by firmly tightening the fixing screws 12, 12 ', 14, 14' of the linear motion guide. The bearing stand bearings or plummer blocks 16, 16 'are provided on the linear guides 13, 13' which are slidable and fixable horizontally. The base body 4 is firmly supported in a bearing stand bearing or plummer block 16, 16 '. In the illustrated embodiment, the base body 4 is configured in a tube shape, but may have other desired cross-sectional shapes.

  Several holding veils or clips 17 distributed in the weaving width direction fix the holding plate 18 on the base body 4 by means of fixing washers 20 and nuts 19.

  The leaf spring carrier 21 is fixed on the holding plate 18 by screws 22. The fastening block 25 is fixedly connected to the leaf spring carrier 21 by, for example, screwing.

  In the region of the free end of the leaf spring carrier 21, the deflection plate 23 is fixedly connected to the leaf spring carrier by screws 24. The deflection plate 23 plays a role of deflecting the warp 9 and is subjected to a corresponding surface treatment. This surface treatment may be changed according to the warp material used in order to prevent the fabric quality from being deteriorated by the contact of the warp sliding on the deflection plate.

  The leaf spring 6 is firmly sandwiched between the fastening surface 27 of the fastening block 25 and the pressing piece 26 on the attachment side 7 thereof. For this reason, the pressing piece 26 is fastened by the fastening screw 28.

  Thereby, the attachment side 7 of the leaf spring 6 is fixedly connected to the base body 4.

  At the free end of the leaf spring 6, that is, at the outer side 8, the thread deflection element 10 is fixedly connected to the leaf spring 6 by a mounting screw 29 and a mounting nut 30.

  The mechanical stop member 31 in the form of a stop screw is spaced in the region of the outer side 8 of the leaf spring 6 with a gap in the direction of tension, that is, the direction in which the leaf spring 6 bends while increasing the tension of the warp 9. Has been placed. This stop member is fixed at a predetermined position by a counter nut 32.

  In the illustrated embodiment, the feature of the present invention that the weight with respect to the unit length of the leaf spring 6 decreases toward the outside 8 direction is achieved by the triangular shape of the leaf spring. Thus, the weight of the outer 8 region of the leaf spring 6 that moves relatively fast is reduced, which counteracts the acceleration caused by the movement of the warp 9 with relatively low mass inertia. Thus, the entire backrest vibrable system reacts very dynamically and keeps the tension in the warp within a low range throughout the weaving cycle.

  The function of the backrest according to the invention can be seen in FIG. During the application of the warp 9 tension, the force generated by the warp tension acts on the yarn deflection element 10 and bends the leaf spring 6 toward the stop member 31. In the weaving operation, the leaf spring 6 is located between the first position of the leaf spring indicated by the solid line and the second position indicated by the broken line where the outer side 8 of the leaf spring is located in the vicinity of the stop member 31.

  In the first position shown, the leaf spring 6 is completely loosened or tensioned or unloaded. In the illustrated second position, the leaf spring 6 is extended to the maximum. The stop member 31 is adjusted so that the leaf spring 6 is not overloaded. In different embodiments, the mechanical stop member 31 is configured to be adjustable during operation and allows for different phases of operation to allow limiting and expanding the maximum travel of the leaf spring. It may be arranged in a position.

  During the weaving operation, the leaf spring 6 normally does not move the entire range from the fully tensioned first position to the fully extended position on the stop member 31, but between the two extreme positions. Move within a limited range of either The width of this range, i.e. the amplitude of the leaf spring vibration in the weaving operation, depends on various factors such as the spring properties of the leaf spring, the warp material and the size of the opening stroke.

  While the loom is stopped, the warp tension is reduced and the warp is fed from the warp beam or the woven fabric is fed from the cross beam. Thereby, the leaf spring 6 is detensioned and the yarn deflection element 10 moves in the direction of the unloaded first position until a suitable low leaf spring tension is achieved.

  If warp shift is limited during this tension removal process, this can be achieved by a second stop member not shown here. The second stop member is disposed on the side of the leaf spring 6 opposite to the stop member 31, and the second stop member is in the direction of the first position where the leaf spring 6 is unloaded during the tension removal of the warp 9. After a slight movement, the second stop member is adjusted so as to hit. When the warp or the woven fabric is further fed out from the warp beam or the cross beam, the warp tension is reversed to the zero side.

  The embodiment according to claim 8 makes it possible to superimpose the second movement on the leaf spring, but this is not shown. Starting from the embodiment shown in FIG. 1, such an embodiment can be easily achieved, in which case the tubular base body 4 is placed in a bearing stand bearing or plummer block 16. It is supported so that it can rotate. The controlled rotation drive unit is fixedly disposed on the plummer block, and the drive shaft of the rotation drive unit is operatively connected to a base body 4 supported so as to be able to rotate. The rotary drive section preferably obtains a corresponding control signal from the loom control section via an appropriate signal line.

  A further possible configuration for producing a superimposed second movement is to support the fastening block 25 on the leaf spring carrier 21 so as to be rotationally movable or translationally slidable, and to control the fastening block by means of a controlled drive. To drive.

  In the graph of FIG. 4, the loom rotation angle is shown in degrees (°) on the abscissa over about two motion cycles. The corresponding warp tension is given in centimeters (cN) on the ordinate. Both of these characteristic curves are recorded at a loom speed of 600 rpm.

  A first characteristic curve 33 drawn by a solid line shows the progress of the warp tension when the loom having the backrest of the present invention is operated.

  A second characteristic curve 34 drawn in broken lines shows typical warp tension progression with a conventional backrest system that does not have a mass optimized backrest. Since the vibratable parts in the conventional system have a higher inertial mass, the system can no longer follow the rapid movement of the warp in the high speed loom, and the warp is out of the deflection element at a predetermined phase in the weaving cycle. It is sent out and strikes the spring-stretched deflection element again shortly thereafter. The rapid movement of the warp is caused, for example, by the rapid movement of the opening forming means in a corresponding high speed loom.

  This gives rise to a maximum value of high warp tension, which can be clearly seen in the course of the characteristic curve.

  In particular, the decrease and increase of the warp tension gradient in the course of the characteristic curve is indicative of the process described above, including the delivery of the warp from the deflection element and the subsequent impact on the deflection element. Such a large change in warp tension within a short period of time means a high load of warp tension and a cause of defects in the entire weaving process.

  When comparing the characteristic curves 33 and 34, it becomes clear that the warp tension progression 33 with the very dynamic backrest according to the invention is advantageously offset or equalized. That is, the maximum value of the warp tension is considerably low and the minimum value of the warp tension is considerably high. Therefore, the value of the generated warp tension can be limited to a very narrow limited range.

  This makes it possible to optimally adjust the warp tension for each product. The warp load and damage are significantly reduced, increasing process assurance in the weaving operation and improving the quality of the fabric.

Claims (12)

In the loom backrest (1), located in the warp path behind the loom warp beam (2),
A base body (4) provided in the loom frame (5);
At least one thread deflection element (10) supported in a oscillating manner on at least one elastic element of the backrest (1) configured as a leaf spring (6),
The at least one leaf spring (6) is fixedly connected to the base body (4) on the mounting side (7);
The at least one thread deflection element (10) is provided on an outer side (8) of the at least one leaf spring (6) located on the opposite side of the mounting side (7);
The backrest of the loom characterized by the above-mentioned. The weight with respect to the unit length of the said at least 1 leaf | plate spring (6) is comprised so that it may decrease toward the said outer side (8) direction of the said leaf | plate spring (6). .   2. The backrest according to claim 1, further comprising a deflection plate (23), whereby the warp slides on the deflection plate (23) and on the yarn deflection element (10).   The backrest according to claim 1 or 2, characterized in that the at least one leaf spring (6) has a triangular or trapezoidal shape with a substantially uniform thickness.   4. The backrest according to claim 1, wherein several leaf springs (6) are arranged so as to be distributed over the width direction of the warp (9).   The leaf springs (6) have different spring stiffnesses, in particular the leaf springs (6) in the end region of the yarn deflection element (10) and the leaf springs (6) in the center have different spring stiffnesses. The backrest according to any one of claims 1 to 4, wherein the backrest is characterized in that   6. The mounting side (7), wherein the at least one leaf spring (6) is fixedly connected to a fastening block (25) fixed to the base body (4). The backrest as described in any one of Claims.   The yarn deflection element (10) is composed of several individual parts, which are arranged side by side so as to be distributed over the width direction of the warp (9). The backrest as described in any one of thru | or 6.   A second movement can be superimposed on the spring movement of the leaf spring (6), in particular the base body (4) is said to be caused by movement of the base body (4). Displaceably arranged on the loom frame (5), in particular the drive for the controlled operation of the second movement is caused by the main drive of the loom or for the controlled operation of the second movement The backrest according to any one of claims 1 to 7, wherein a separate electric, hydraulic, or pneumatic driving unit is provided.   At least one mechanical stop member (31) for limiting the movement of the at least one leaf spring (6) is provided, and the mechanical stop member (31) is configured to be adjustable. The backrest according to any one of claims 1 to 8.   10. The backrest according to claim 1, wherein the yarn deflection element (10) is movably fixed to the leaf spring (6), in particular configured as a deflection roller.   11. A backrest according to any one of the preceding claims, characterized in that a damping means acting on the at least one leaf spring (6) is provided.   A loom characterized by a backrest according to any one of the preceding claims.

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