EP1387899B1 - Spring dampened shedding device - Google Patents

Abstract

A shedding device in a jacquard loom, having a heddle with a retracting spring rigidly anchored in the loom or to the floor for urging the heddle to a lower shed forming position. To suppress the development of resonance in the spring, a core element is provided, which contacts the inside of the spring at points spaced apart from one another and forces the spring to take a course which deviates from the rectilinear. As a result, friction forces that contribute to damping the spring motion are created between the spring and the core element.

Description

In jacquard weaving machines in particular, the strands are inevitably moved in one direction while being pulled in the other direction by a spring. In general, the strand is moved by the spring to form the lower compartment. The spring is stationary or anchored to the ground at the other end in the weaving machine and keeps the harness cord and the heddle under tension in any operating condition.

Like any spring-loaded system, the arrangement of spring, heald and harness cord shows resonance phenomena including the propagation of waves passing through the linear system. The self-resonances of the system play no role as long as the speed of movement of the heald is small compared to the resonance frequency. But at the moment, where the moving speed of the heddle reaches the resonance frequency range, unpleasant waves occur in the spring. The waves are excited in the spring by the movement of the heald and run towards the fixed end, where they are reflected and run back towards the heald. Under unfavorable circumstances, it may even happen that the heald is tension-free, because the returning shaft in the connection between the spring and the heald a phase position, which is directed against the initialized by the movement of the Harnischkordel movement.

The resonances within the spring also provide for increased mechanical stress and premature breakage. This is typical break points.

To dampen the resonances in the spring it is out of the EP 0 678 603 known to provide the lower spring attachment point with a damping device. The lower spring attachment point consists of a plastic molded part, on which a threaded pin is formed. On the threaded pin, the coil spring is screwed. The threaded pin carries at its free end two resiliently mutually movable legs which protrude into the interior of the spring and press against the spring. The two legs are in turn connected to each other at the end remote from the threaded pin and go over into two other legs, which form an open fork.

It has been found that this type of spring damping is not without problems. If the contact force with which the legs act against the inside of the spring coils is too hard, no useful damping effect occurs on. Rather, the incoming waves are largely undiminished at those locations where the legs touch the inside of the spring. On the other hand, if the contact pressure is too low, sufficient damping will not occur.

This unfavorable phenomenon is exacerbated because the spring elasticity of the plastic shows fatigue and is also temperature dependent.

Finally, threading the open leg ends into the spring is not easy.

Proceeding from this, it is an object of the invention to provide a shedding device, in which the problems described above do not occur.

This object is achieved by the shedding device with the features of claim 1.

As in the prior art, the heald between the Harnischkordel and the coil spring is kept taut. The remote from the heald end of the coil spring is anchored stationary. In order to achieve the desired damping, a damping element is present, which is in contact at least at several spaced locations with the coil spring and the originally straight coil spring imposes a non-straight course. In this way, the coil spring is at points spaced from each other with the damping element in touch. The contact force of the coil spring on the damping element is determined by the inherent elasticity of the spring and the degree of deflection. The elasticity of the damping element By contrast, it plays virtually no role.

Due to the substantially punctual contact between the coil spring and the damping element, a part of the vibration energy can be converted into friction at each contact point. The reflections of the mechanical shaft occurring at the points of contact are too small in magnitude, as they would be able to produce a significant return wave, which would lead to spring breaks. Between the points of contact, however, the spring is reasonably free.

Since the extent to which the spring is pressed against the damping element only depends on the geometric extent of the non-straight course which the helical spring assumes as a result of the damping element, very precisely reproducible pressure forces are achieved. The modulus of elasticity of the steel coil spring is much less temperature dependent than the modulus of elasticity of plastic, and moreover, the modulus of elasticity changes less over time.

Finally, there is virtually no permanent deformation in the steel spring in such a way that it gradually adapts to the non-straight course of the damping element. The damping element, however, needs compared to the resilience of the coil spring to have no elasticity at all. It may be rigid relative to the force exerted by the coil spring in such a way that it is not pressed into another shape by the coil spring. In this way, it is possible, very accurate reproducible contact forces and thus very accurate reproducible frictional forces between the spring and the damping element to create.

In particular, it is possible to interact over a comparatively long distance the damping element with the coil spring.

It is also possible that the degree of deformation, ie. the wavelength and / or the amplitude which urges the damping element of the coil spring changes over the length of the damping element. For example, in this way an increasing damping or coupling of the vibrations can be achieved. The damping element is first relatively little deformed in the direction of the heald from the straight course and the deformation increases in the direction of the anchoring end of the coil spring. With very little dispersion, a very good damping is achieved on the damping element.

The damping element is preferably a core element which is arranged in the coil spring and linear. In this way, additional space for the damping element is saved, because it is located at the point that is already inevitable anyway.

In order to obtain the desired deformation, the core element may have a non-straight course deviating from the straight course. Another possibility is to use a per se straight core element which carries at a distance from each other discretely distributed wart-like projections or bumps with which the coil spring of the desired not straight course is imposed. The diameter in the region of the projection or hump is smaller than the inside diameter of the helical spring.

In the case of the non-linearly extending core element, this essentially represents a cylindrical structure which exhibits a wave-shaped course. Conveniently, the waves define a regression line, so that on average a straight course of the spring comes about.

The wave-shaped course can be created by the core element forming a screw or by the core element forming waves which lie in a common plane.

In any case, a projection of the core element on a plane generates a wave-shaped band whose width corresponds to the diameter of the core element and whose wave-like nature substantially coincides with the wave or helical course of the core element. The dimensions of the wave-shaped course are expediently defined on this band resulting from projection in the plane. The wave-shaped course shows in the projection a wave depth, measured at an edge of the band, which lies between a wave crest and a wave trough between 0.1 and 3 mm. The strength of this shaft stroke depends on how the diameter ratio between the core element and the inside diameter of the coil spring is dimensioned, and how strongly the coil spring is to be deflected or pressed against the core element. The distances between wave crest and wave trough can be between 2 and 20 mm.

In the case of using projections or bumps they can be arranged along a helical line, or in the simplest case zigzag, ie in each case two adjacent protrusions are located on opposite sides with respect to the core element. The distance between the projections is suitably in the range between 5 mm and 30 mm, preferably between 5 mm and 20 mm.

The projections or bumps are expediently integral with the core element and can be either molded or molded, when the core element is manufactured in this form in the primary molding process. Another possibility is to produce the bumps by local deformation, for example, the crimping of ears. The last possibility is appropriate if the core element consists of a permanently deformable material, for example metal.

The length of the core element is expediently dimensioned such that at least one full wave having the above dimensions can be produced.

The core element may be loose in the coil spring or fixedly connected to the lower anchoring means.

Suitable materials for the core element are thermoplastics such as polyamide, polyethylene and polyurethane or other materials such as metal, ceramic, thermosets or vulcanizable materials in question.

The shed forming device according to the invention is preferably used in jacquard weaving machines. However, because of the very good damping effect and the small footprint, the arrangement according to the invention is not on Jacquard machines but can also be used in normal weaving machines for producing un-patterned woven fabrics or dobby machines. Accordingly, the shed-forming device is also, for example, a dobby, a Jacquard machine or a comparable drive device in order to set the strands in motion.

In order to connect the heald with the coil spring, the heald may be provided at the respective end of the heddle shaft with a plastic molded part having, for example, a screwed into the coil spring thread.

The connection of the coil spring with the lower or the upper anchoring member can be done according to the prior art.

Furthermore, those combinations of features of the subclaims are claimed that are not reproduced by a specific embodiment.

Fig. 1

eine schematische Darstellung einer Fachbildeeinrichtung gemäß der Erfindung,

Fig. 2

das Kernelement in einer vergrößerten Darstellung,

Fig. 3

die obere Verbindung zwischen dem Litzenschaft und der Rückzugsfeder,

Fig. 4

eine andere Ausführungsform des Kernelementes mit seitlichen Vorsprüngen oder Höckern, in einer vergrößerten Darstellung.

Fig. 5

das Kernelement nach Fig. 4 in einem Querschnitt geschnitten auf der Höhe eines Vorsprungs,

Fig. 6

ein erfindungsgemäßes Kernelement, bei dem die Vorsprünge durch lokales Umformen erzeugt sind, in einer vergrößerten Darstellung und

Fig. 7

das Kernelement nach Fig. 6 in einem Querschnitt geschnitten auf der Höhe eines Vorsprungs.

Moreover, further developments are the subject of dependent claims. In the drawing, an embodiment of the article is shown in the invention. Show it:

Fig. 1

a schematic representation of a shedding device according to the invention,

Fig. 2

the core element in an enlarged view,

Fig. 3

the upper connection between the Litzenschaft and the return spring,

Fig. 4

another embodiment of the core element with lateral projections or bumps, in an enlarged view.

Fig. 5

the core element after Fig. 4 cut in a cross section at the height of a projection,

Fig. 6

a core element according to the invention, in which the projections are produced by local forming, in an enlarged view and

Fig. 7

the core element after Fig. 6 cut in a cross section at the height of a projection.

Fig. 1 shows very schematically the essential for understanding the invention functional parts of the shed-forming device in a Jacquard loom. To the shed-forming device includes a drive device 1, of which a pulley 2 is illustrated. From the reel pull 2, a strung cord fastened to a strupter bottom 3 goes out, which merges into a harness cord 4 which passes between a glass grate or a guide bottom 5. The Harnischkordel 4 continues to a chorus board 6 and exits through a hole 7 down. At the lower end, ie at the end of the Harnischkordel 4, which is spaced from the pulley 2, a heald 8 is attached. The heald 8 has an eyelet or an eye 9 for a warp thread 11. From the eyelet 9 go from an upper and a lower heddle shaft 12, 13, which lie on a common line. The lower end of the lower heddle shaft is connected to a return spring 14, which is anchored at 15 on the machine frame or on the ground.

The movement of the pulley 2 is transmitted via the Harnischkordel 4 on the heald 8. As a result, the Harnischkordel 4 is pulled up and the eye 9 pulled up from the neutral position to form the upper compartment. The return spring 14 is thereby stretched more than in the neutral position of the heddle 8, which corresponds to the closed shed. When the harness cord 4 is lowered, the return spring 14 moves downwardly as the harness cord 4 moves down, the heald 8 downward. As a result, the respective warp thread 11 forms the lower compartment.

As will be readily appreciated, the upward movement of the heald 8 is an inevitable motion which is imposed rigidly over the longitudinally inconvenient harness cord 4. The opposite direction, on the other hand, is a movement initiated by the return spring 14 and, to that extent, only conditionally inevitable or rigid.

The harness of harness 4, heald 8, warp 11 and return spring 14 is a spring-mass system having one or more resonant frequencies. At high machine speeds, the frequency with which the heald 8 is brought from the closed shed neutral position to the upper shed position or the lower shed position is about 10 Hz. These frequencies are determined by the drive system 1 imposed, are in the order of the resonance frequencies of the entire system, or the resonance frequency of subsystems. In addition, harmonics occur and it can Form at these frequencies waves on the linear structure between the chorus board 6 and the anchoring point 15 in the return spring 14, which are reflected without appropriate countermeasures to the anchoring point 15 and become standing waves in the return spring 14. As a result, the return spring 14 is extremely heavily loaded at certain points and tends to break. To dampen the resonances, the lower anchoring point of the return spring 14 is according to Fig. 2 educated.

To connect the return spring 14, the in Fig. 2 is shown in sections, belongs to an anchoring element 16 which is formed substantially rod-shaped. The anchoring element 16 has at its lower end an eyelet 17 which is to be hooked into a corresponding rail which is fixedly mounted on the machine frame. From the eyelet 17 is a substantially cylindrical shaft 18, which is provided at its upper end with a collar 19. Concentric with the shaft 18 extends above the collar 19, an external thread pin 21. The external thread pin has a length corresponding to about 10 spring coils. On these threaded pin 21, the return spring 14 is screwed. The return spring 14 is a cylindrical spring wound from a cylindrical steel wire, in which the turns in the relaxed state usually lie on each other.

At its free end, the threaded pin 21 passes into a core element 22, which, as shown, has a non-straight course. The core element 22 forms valleys 23 and vertices 24. It is deformed such that the area defined by the valleys and vertices represents a plane. This means that in a 90 ° rotated side view, compared to Fig. 2 , the core element 22 is straight.

As can be easily recognized, the wave trough 23 on the opposite side of the core element 22 leads to a wave vertex, which deforms the spring 14 in the correspondingly opposite direction, like the vertex 24.

The core element 22 has a circular cross section at all points, wherein the diameter of the cross section is smaller by about 5-30% than the inner diameter of the helical spring 14. The diameter of the core element 22 may be constant over its length or decreasing towards the tip. The core member 22 is integrally molded together with the threaded stem 21, the shaft 18 and the eyelet 17 made of plastic. Suitable plastics are polyamide, polyethylene, polyurethane, polyester.

The wave-shaped course which the core element 22 describes is so strong that the wave troughs and wave crests 23, 24 of the helical spring 14 impose a corresponding course. The coil spring 14 no longer runs straight in the region of the core element, but with a zigzag movement, which corresponds to the core element 22, as indicated by the dashed lines 25 and 26. The deflection of the spring 14 in the lateral direction is mitigated in accordance with the difference in diameter between the outer diameter of the core member 22 and the clear width of the coil spring 14.

The shape of the representation of the core element 22 in FIG Fig. 2 corresponds to a projection of the core element 22 on a plane, and that projection in which the by the The projection produced a meandering band that has the largest amplitude. Considering each of the boundary lines thus obtained as the course of a vibration and used for the description of the usual in vibration terminology, the amplitude of the oscillation measured between tip and tip about 0.1 to 3 mm, preferably 0.1 to 1 mm, while the Wavelength of the vibration is between about 4 and 40 mm; both values can vary along the core element 22.

The amplitude of the wavy line, i. increase the degree of lateral deflection, starting from the free end of the core member 22 to the threaded pin 21. This ensures that the spring 14 rests with its turns on the first wave crest with small lateral force, because it is less deformed than at a wave crest, which is closer to the threaded pin 21.

In Fig. 3 Finally, for the sake of completeness, the connection between the lower strut shaft 13 and the return spring 14 is illustrated. As can be seen there, at the free end of the Litzenschaftes 13, a plastic molded body 27 is formed, which corresponds in terms of its construction to the opposite end of the anchoring element 16. The plastic molded body forms a collar 28, and a threaded pin 29 which extends coaxially to the heddle shaft 13. The threaded pin 29 carries an external thread, which may be cylindrical or conical and on which, as described above, the return spring 14 is screwed until the end, as shown, abuts the collar 28.

The operation of the core element 22 as an attenuator in the spring 14 is approximately as follows:

When a shock is initiated by the upper end of the return spring 14 through the heald 8, the shock passes as a wave in the direction of the anchoring element 16. The shock runs as a longitudinal wave on the tensioned return spring 14. It is ensured in normal operation that the Spring coils of the return spring 14 in no operational situation lie on each other. Due to the shock wave, however, such a clash may well happen.

In any case, passes through the spaced windings of the spring through the shock wave, which now reach the core element 22 accordingly. Between the relevant moving spring coils and the respective shaft crest 23, 24 of the core element creates a friction. The friction converts the kinetic energy of the spring coils into heat, thus depriving the system of energy. Amplitudes of amplitudes due to resonances are effectively suppressed. In particular, the damping ensures that a running in the direction of the threaded pin 21 shock wave reaches the fixed end of the threaded pin 21 of the coil spring 14 only weakened and causes a corresponding reduced in amplitude echo, which in turn is further attenuated during the return along the core element ,

The core element 22 thus effectively provides for suppression of standing waves on the return spring 14. The damping effect by the core element 22, the total length of which is between 5% and 40%, preferably between 10% and 30% of the operationally tensioned return spring 14, also ensures that longer-frequency waves are effectively damped to suppress the formation of standing waves whose wavelength is on the order of the tensioned spring.

For assembly reasons, it is expedient to connect the core element 22 in one piece with the threaded pin 21. However, there is no need for this. Rather, the core element can be provided to provide its damping effect at any point. In particular, it would also be conceivable to connect the core element 22 in one piece with the anchoring member 27, via which the lower heddle shaft 13 is coupled to the return spring 14.

In Fig. 4 another embodiment of a core member 22 is shown, which serves to impose a non-straight course of the coil spring 14, at the same time only a point contact between the core member 22 and the coil spring 14 comes about to produce the damping effect described above.

The core element 22 consists of a straight shaft 31 whose diameter is significantly smaller than the inside diameter of the cylindrical interior within the coil spring 14. On the outside of the shaft 31 are wart-like projections or bumps 32 which are arranged along a helical line. In this case, the bumps or extensions 32 are mutually offset by 90 °, ie it arises in the projection, as the cross section of Fig. 5 shows a four-pointed star. In the area of each hump 32 is still the largest diameter However, since the projection of two diametrically opposed projections 32 on a plane which intersects the axis of the shaft 31 at right angles, is greater than the diameter, the coil spring 14 is made of their natural exactly straight shape in forced a helical shape.

The height of the hump 32 measured in the radial direction with respect to the axis of the shaft 31 and the distance of the projections 32 measured in the longitudinal direction of the shaft 31 define the force with which the coil spring 14 abuts against the apices of the extensions 32.

In the embodiment of the FIGS. 4 and 5 consists of the core element 22 in one piece from a plastic molding. The wart-like extensions 32 are integrally formed. Their axial extension is smaller than their axial distance from each other. Instead of integrally forming the wart-like projections 32 on a plastic molding, there is also the possibility according to Fig. 6 to use a core element 22 whose shaft 31 consists of an originally cylindrical metal wire. The projections or bumps 32 are formed by the starting material is crushed sideways, so that as the cross section according to Fig. 4 shows the material is forced radially outward. The result is "ears" that protrude radially beyond the contour of the original circular cross-section. The effect is the same as before with reference to the embodiment according to Fig. 2 described.

A shed-forming device in a Jacquard weaving machine has the formation of, for example, the lower shed a return spring, the einendes is rigidly anchored in the weaving machine or on the ground. In order to suppress the formation of resonances in the spring, a core element is provided which applies at spaced locations on the inside of the spring and the spring imposes a course which deviates from the straight course. As a result, frictional forces between the spring and the core element are generated, which contribute to the damping of the spring movement.

Claims (27)

1. Shedding device (1) for a weaving machine, in particular for a Jacquard weaving machine,
   with a drive means (2) for generating a longitudinal movement,
   with at least one heald (8), which contains an eyelet (9) and from which heald shafts (12, 13) extend to diametrically opposed sides, one (12) of which shafts being coupled to the drive means (2),
   with a connection means (27) on the other heald shaft (13),
   with a coil spring (14), which is associated with the at least one heald (8) and one end of which is attached to the connection means (27) and which serves to pull back the heald (8),
   with an anchoring means (16) to fixedly anchor the other end of the coil spring (14), and
   with a damping element (22), which is in contact with the coil spring (14) at least at a plurality of spaced locations,
   characterised in that the damping element forces the coil spring on a non-straight course.
2. Shedding device according to claim 1, characterised in that the damping element (22) is a core element (22), which is arranged in the coil spring (14) and is line-shaped.
3. Shedding device according to claim 2, characterised in that the core element (22) has a non-straight course.
4. Shedding device according to claim 2, characterised in that the core element (22) bears discrete projections (32) spaced along its extent, wherein the diameter of the core element (22) measured at the height of a respective projection (32) is smaller than the width of the coil spring (14).
5. Shedding device according to claim 2, characterised in that the core element (22) is a cylindrical or laterally flattened structure that presents an undulating course.
6. Shedding device according to claim 2, characterised in that the core element (22) is shaped in an undulating form such that the undulations lie in a common plane.
7. Shedding device according to claim 2, characterised in that the core element (22) has a helical course.
8. Shedding device according to claim 2, characterised in that the core element (22) has a substantially constant cross-section over the length.
9. Shedding device according to claim 2, characterised in that the projection of the core element (22) onto a plane provides an undulating band with two parallel edges, wherein the undulating line, which one of the edges describes, has an amplitude measured between an undulation trough (23) and an undulation peak (24) of between 0.1 and 3 mm.
10. Shedding device according to claim 9, characterised in that the spacing between an undulation peak (24) and an undulation trough (23) amounts to between 2 and 20 mm.
11. Shedding device according to claim 2, characterised in that the core element (22) is configured such that its projection provides at least one complete undulation.
12. Shedding device according to claim 4, characterised in that the projections (32) are arranged along a helical line.
13. Shedding device according to claim 4, characterised in that the projections (32) project alternately to different sides of the core element (22).
14. Shedding device according to claim 4, characterised in that the projections (32) are configured in one piece with the core element ().
15. Shedding device according to claim 4, characterised in that the projections (32) are generated by local squeezing of the core element (22).
16. Shedding device according to claim 4, characterised in that the projections (32) have a spacing from one another of between 5 mm and 30 mm, preferably between 5 mm and 20 mm.
17. Shedding device according to claim 2, characterised in that the material for the core element is a thermoplastic such as polyamide, polyethylene and polyurethane or also another material such as metal, ceramic, thermosetting plastic or a material that can be vulcanised.
18. Shedding device according to claim 1, characterised in that the damping element (22) is fixedly connected to the anchoring means (16) or the connection means (27).
19. Shedding device according to claim 1, characterised in that the drive means (1) is a shedding device of a Jacquard weaving machine.
20. Shedding device according to claim 1, characterised in that the connection means (27) is formed by a plastic moulding, which is integrally and/or positively connected to the respective end of the heald shaft (13).
21. Shedding device according to claim 18, characterised in that the connection means (27) is a thread (29).
22. Shedding device according to claim 1, characterised in that the anchoring means (16) is a thread (21).
23. Shedding device according to claim 21 or 22, characterised in that the thread (21) is an external thread.
24. Shedding device according to claim 23, characterised in that the thread (21) is a tapered thread.
25. Shedding device according to claim 24, characterised in that starting from a diameter value which is smaller than the width of the coil spring (14), the core diameter of the thread (21) increases to a diameter, which is equal to or larger than the width of the coil spring (14).
26. Shedding device according to claim 1, characterised in that the coil spring (14) is a coil tension spring, in which the individual spring coils lie one on top of the other in the relaxed state.
27. Shedding device according to claim 1, characterised in that the coil spring (14) is made of steel.

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