WO1997049850A1

WO1997049850A1 - Thread brake

Info

Publication number: WO1997049850A1
Application number: PCT/EP1997/003259
Authority: WO
Inventors: Ignace De Ro
Original assignee: Picanol N.V.
Priority date: 1996-06-26
Filing date: 1997-06-21
Publication date: 1997-12-31
Also published as: BE1010389A3

Abstract

In a thread brake (31) for braking weft threads (3) in a loom, there are several individual drive components (34 - 38) one behind the other in the direction of travel of the weft thread to be braked, which are individually controllable and by means of which a braking component (45) can be moved towards an opposite braking component (46).

Description

Thread brake

The invention relates to a thread brake for braking weft threads for a weaving machine with braking elements arranged on opposite sides of the weft thread to be braked.

In weaving machines, thread brakes are used for the weft threads, the braking force exerted on the respective weft thread varies.

To vary the braking force, it is known (US Pat. No. 2,537,476) to adjust braking elements by means of a cam drive derived from the main drive of the weaving machine.

A thread brake is also known (IT patent 593 034), which has a stationary and a spring-loaded braking element. The thread tension is detected by a detector and regulated in that pneumatic, hydraulic or electrical forces are superimposed on the spring-loaded braking element.

A thread brake is also known (US Pat. No. 4,875,506) which has a rigid braking body, one side of which is designed as a rigid braking surface. Controllable electromagnets are arranged within this brake body. On the a side of the weft thread is a brake plate, which consists of a thin metal band. The electromagnets can be controlled by means of a control unit of the weaving machine. The aim is to vary the braking force as a function of a curve stored in the control unit, which curve is assigned to the weft thread to be entered in the shed. The curve is determined, for example, as a function of the speed at which the weft thread is inserted. In the known design, the braking force applied by the thread brake to the weft thread is not only dependent on the strength of the current with which the electromagnets are controlled by the control unit. Rather, the thickness of the weft thread, which is located between the electromagnets and the brake disk, also plays a role, since the magnetic force changes when the distance between the electromagnets and the brake disk changes. In order to improve the magnetic force transmission, it is known (EP-A 0 498 758) to arrange soft-ferromagnetic, plate-shaped segments on the side of the brake disk facing away from the weft thread.

A thread brake for weft threads is also known (US Pat. No. 5,398,732) which has two leaf springs bent convexly towards one another as brake elements which are held in holders. The holder of the one leaf spring is loaded by means of springs or an electrodynamic drive in the direction of the other braking element. The electrodynamic drive is designed so that the maximum braking force is reached when the weft thread is not running. During operation, the strength of the current supplied is changed so that the braking force is reduced compared to the maximum braking force.

In the known thread brakes there is the problem that the thread brakes increase the weft thread tension relatively suddenly, especially if the weft thread has pimples or thick len or the like having. This can lead to overloading of the weft thread and thus to breakage of the weft thread.

The invention has for its object to provide a thread brake which is suitable for practically every type of weft thread and in which the braking force can be controlled so that an abrupt increase in the braking force can be avoided.

This object is achieved in that several individual drive elements are arranged one behind the other in the running direction of the weft thread to be braked, which can be controlled individually and which can be adjusted in the direction of an opposite braking element while taking a braking element with it.

The invention has the advantage that by individually controlling one or more of the individual drive elements, the braking force varies sensitively and can be adapted to the type of weft in question. Since the individual drive elements determine the braking force, the thickness of the respective weft thread does not play a decisive role.

In an embodiment of the invention it is provided that the individual drive elements are electro-dynamic linear motors which generate a force which is essentially only dependent on the strength of the supplied current. Such linear motors with a plunger armature pot magnet arrangement have characteristic curves proportional to the current force, so that the braking force caused by these individual drive elements is practically dependent only on the current intensity supplied. The braking forces generated by the individual drive elements can thus be determined very precisely without the strength of the weft thread having an influence on it.

In a further embodiment of the invention it is provided that the brake elements adjustable by means of the individual drive elements and / or the brake elements opposite the adjustable brake elements are replaceable components. This makes it possible to assign a particular type of braking element to the respective weft thread type, which is favorable in terms of reducing the risk of damage or the breaking of weft threads. The brake elements can be easily replaced even if they are worn.

Further features and advantages of the invention result from the following description of the exemplary embodiments shown in the drawing and the subclaims.

1 shows a schematic representation of a rapier weaving machine with thread brakes for a plurality of weft threads to be fed,

Fig. 2 is a partially sectioned side view of a weft yarn brake on a larger scale ^'

3 is a side view of the weft brake according to FIG. 2 while braking a weft,

4 the weft brake according to FIG. 2 or 3 with a modified brake element in the rest position,

5 the thread brake according to FIG. 4 in the braking position,

6 shows the thread brake according to FIGS. 2 and 3, in which another type of brake element is opposite the adjustable brake elements,

7 the thread brake according to FIG. 6 in the braking position,

8 shows the thread brake according to FIGS. 6 and 7 with a modified type of brake element adjustable by individual drive elements, 9 shows the thread brake according to FIGS. 2 and 3 with another type of brake element drivable by the individual drive elements in the open position,

10 the thread brake according to FIG. 9 in the braking position,

11 shows the thread brake according to FIGS. 9 and 10 with a different arrangement of the individual drive elements and their braking element opposite braking elements,

12 shows a modified embodiment of a thread brake with individual drive elements for brake elements arranged on both sides of a weft thread to be braked,

13 shows a thread brake similar to FIG. 12 with an additional braking element and

Fig. 14, the thread brake according to Fig. 12 with two additional braking elements.

The rapier weaving machine shown in FIG. 1 has a donor rapier 1 and a slave rapier 2 for the transport of weft threads 3, 4 and 5 through a shed 6. The shed 6 is formed between warp threads 7, which are raised or lowered using shed forming means, not shown. The weft threads 3, 4, 5 are fed by a thread feeder 8 by means of needles 9, 10 and 11 to the donor gripper 1, picked up by the donor gripper, then cut off by means of scissors 12 on a guide 13 lying on the entry side 14 in the region of the selvedge 15 and then transported by means of the gripper 1 approximately in the middle of the shed 6. The slave gripper 2 moves into and out of the shed 6 essentially from the opposite side 16 in synchronism with the master gripper. Approximately in the middle of the shed 6, the wefts 3, 4 or 5 of the Slave gripper 2 taken over from master gripper 1 and transported by slave gripper 2 to side 16 of shed 6. On this side 16, the slave gripper 2 leaves the weft threads

3, 4 or 5 loose, which are struck by a reed 17 on the edge of the fabric 18, whereby they are bound by the warp threads 7. The master gripper 1 and the slave gripper 2 are transported through the shed 6 by means of driven gripper belts 19 and 20.

In the exemplary embodiment shown, the weft threads 3, 4 and 5 run from bobbins 21, 22 and 23 via prewinding devices 24, 25/26 and the needles 9, 10, 11 of the thread feeder 8 to the fabric edge 15. The prewinding devices 24, 25, 26 contain a stationary winding drum 27, onto which 28 windings of the weft threads 3, 4, 5 are placed by means of a motor-driven winding arm 28. Furthermore, the prewinding devices 24, 25, 26 at the front end of the winding drum 27 contain an output brake 29 for braking a unwound weft thread and a guide eye 30 through which the relevant weft thread 3,

4, 5 leaves the pre-winder 24, 25, 26.

Between the fastener devices 24, 25, 26 and the shed, i.e. Between the thread guides 30 of each pre-winding device 24, 25, 26 and the associated needle 9, 10, 11 of the thread feeder 8, a thread brake 31 according to the invention is arranged, which will be explained in more detail below. 1 also shows a control unit 32 which controls the winding devices 24, 25, 26, the thread brakes 31 and the thread feeder 8. The bobbins 21, 22, 23, the pre-winding devices 24, 25, 26, the thread feeder 8, the control unit 32 and the thread brakes 31 are attached to a frame 33.

2, the thread brake 31 contains a plurality of individual drive elements 34, 35, 36, 37, 38, each of which forms an electrodynamic linear motor. The individual drive units arranged one behind the other and parallel to one another in the running direction of the weft thread 3 to be inserted elements 34 to 38 each contain an armature 39 with a winding 41, which are supplied in a manner not shown by means of electrical lines from the control unit 32 with current. The anchors 39 each sit on a core 42, against which they are guided axially with little play. At the level of the core 42 and the windings 41, a permanent magnet 40 is provided in the housing 43, which builds up a magnetic field. In a modified embodiment, the permanent magnets are replaced by electromagnets, which are supplied by the control unit 32 by means of adjustable currents. An elastic cover 44 is provided between the armature 39 and the housing 43, which prevents weaving dust from penetrating into the individual drive elements 34 to 38. When a current is supplied to the windings 41, the armatures 39 are in the working position. Due to the arrangement of the permanent magnet 40, the windings 41, the core 42 and the housing 43, the individual drive elements 34, 35, 36, 37, 38 each generate a force which is largely independent of the position of the armature 39, however is dependent on the current strength of the current supplied to the windings 41. Due to the direct electro-dynamic drive of the armature 39 with the help of the permanent magnets 40, the windings 41, the core 42 and the housing 43, it is achieved that the thickness of the weft thread 3 has no influence on the force with which the respective armature 39 acts on the weft 3. The course of the braking force with which the thread brake 31 acts on the weft thread can be controlled in that current is supplied to the windings 41 in accordance with a specific curve profile by means of the control unit 32.

The individual drive elements 34 to 38 of the thread brake 31 according to FIG. 2 each have a brake element 45 which is formed from the approximately mushroom-shaped end face of the armature 39. These brake elements 45 form a first type of brake elements which are firmly connected to the individual drive elements 34 to 38 and which can interact individually with the weft thread 3 to be braked. The thread brake 31 contains a stationary brake element with a flat, flat brake shoe 46, which is part of a component 47, which is fastened with screws 48 to side brackets 49 of the thread brake 31. The side brackets 49 are fastened to the housing 43 with screws 50. The side brackets 49 are provided with thread guide eyelets 51 through which the weft thread 3 runs. The individual drive elements 34 to 38 are arranged one behind the other in the running direction of the weft thread 3, which results from the connecting line between the two thread guide eyes 51. The stationary brake shoe 46 is arranged opposite the individual drive elements 34 to 38 such that the weft thread 3 can be braked between this stationary brake shoe 46 and the brake elements 45 which can be actuated by the individual drives 34 to 38. To brake the weft thread 3, one or more of the individual drive elements 34 to 38 are actuated by the control unit 32, ie supplied with current of a predetermined strength, so that the weft thread 3 is pressed with a defined force between the brake elements 45 and the brake shoe 46. In the position shown in FIG. 2, none of the individual drive elements 34 to 38 is actuated, while in the position shown in FIG. 3 all of the individual drive elements 34 to 38 are supplied with a current of a defined magnitude. As can be seen from FIG. 3, the braking elements 45 are located on the side of their individual drive elements 34 to 38 with respect to the weft thread 3 to be braked. The braking force is controlled by the individual drive elements 34 to 38 each having a current corresponding current strength are supplied by the control unit 32 in accordance with the desired course of the braking force.

As will be explained with reference to FIGS. 4 to 14, the thread brake 31 according to the invention allows the use of different geometric shapes of the brake elements acting on the weft thread 3 in a simple manner, so that an adaptation to the respective weft thread type is possible by means of the shape of the brake elements is, that is, braking elements are selected can, in which there is only a slight risk of damage or breakage of the weft thread in the weft thread in question.

In the embodiment according to FIGS. 4 and 5, an elongated, thin leaf spring 52 is arranged between the weft thread 3 and the individual drive elements 34 to 38 and extends over all individual drive elements 34 to 38. This leaf spring 52 is held and guided by means of the side brackets 49 in such a way that the leaf spring 52, which now serves as the braking element, can move in the setting direction of the individual drive elements 34 to 38, but is fixed in the running direction of the weft thread 3. The ends 45 of the armatures 39 therefore no longer have the function of braking elements, since this function has been taken over by the leaf spring 52. The ends 45 only serve to press the leaf spring 52 against the weft thread 3 in such a way that the weft thread 3 is braked between the leaf spring 52 and the brake shoe 46. The leaf spring 52 can be attached very easily in the thread brake 31 and can accordingly be exchanged easily when wear occurs.

In the examples shown in FIGS. 1 to 5, the brake shoe 46 of the component 47 interacts with the weft thread to be braked. The component 47, which is, for example, an element with a U-shaped profile, is provided on the side facing away from the brake shoe 46 with a plurality of stationary brake elements in the form of cylindrical rods 55 which are fastened to projections 56. After loosening the screws 48, the component 47 can be rotated by 180 °, so that the cylindrical rods 55, which run transversely to the running direction of the weft thread 3, now face the weft thread 3, after which the screws 48 are tightened again. The cylindrical rods 55 are each located between two individual drive elements 34, 35; 35, 36; 36, 37; 37, 38, as shown in Figs. 6 and 7. In this arrangement, the weft thread 3 is braked as shown in FIG. 7, that it is deflected between the front ends 45 serving as braking elements, the armature 39 of the individual drive elements 34 to 38 and the rods 55, but is not clamped.

As shown in FIG. 8, it is readily possible to arrange a leaf spring 52 even when the component 47 according to FIGS. 6 and 7 is arranged between the weft thread 3 and the individual drive elements 34 to 38, as is shown in FIG. 4 and 5 has been explained. In this modification, which can be carried out simply and with little assembly effort, the weft thread 3 is clamped between the leaf spring 52 and the individual rods 55 and is thereby braked.

In the embodiment according to FIGS. 9 and 10, a bar 53 is arranged between the individual drive elements 34 to 38 and the weft thread 3, which bar is provided with a plurality of cylindrical rods 54 which are held at regular intervals and which extend transversely to the running direction of the Weft 3 are aligned. The bar 53 is held fixed in the side holders 49 in the running direction of the weft thread 3, but is adjustable in the direction of the weft thread 3 by means of the individual drive elements 34 to 38. In the embodiment according to FIGS. 9 and 10, the component 47 is mounted such that the brake shoe 46 faces the weft thread 3. The weft thread 3 is clamped between the rods 54 and the brake shoe 46 and is therefore braked.

As shown in FIG. 11, the thread brake 31 according to FIGS. 9 and 10 can be modified in a simple manner in that the component 47 is arranged rotated by 180 °, so that the rods 55 face the weft thread 3. The bars 55 and the bars 54 of the strip 53 are arranged with respect to one another in such a way that the bars 55 each protrude into a gap between two bars 54. In this arrangement, the weft thread 3 is braked in that it is deflected on the rods 54 and 55. If the strip 53 is made relatively stiff, it is sufficient in the exemplary embodiments according to FIGS. 9 to 11 to control only one or two of the individual drive elements 34 to 38 by means of the control device 32 and to apply current with a predetermined strength. In this case, for example, only the central individual drive element 36 could be controlled. It is also possible to control only the two outer individual drive elements 34 and 38. If a weaving machine is only to be operated with a thread brake 31 in accordance with the exemplary embodiments according to FIGS. 9 to 11, the thread brake 31 could be simplified as a whole by only providing a single drive element, for example the individual drive element 36 Bar 53 is sufficiently flexible, so by varying the control of the individual drive elements 34 to 38, the course of the braking force can be further influenced in the exemplary embodiments according to FIGS. 9 and 10 and also in the exemplary embodiment according to FIG. 11.

In the exemplary embodiments shown in FIGS. 12 to 14, the component 47 has been replaced by a housing 66 in which individual drive elements 62 to 65 are arranged, which are designed in accordance with the individual drive elements 34 to 38. These individual drive elements 62 to 65 can also be individually controlled by the control unit 32. The individual drive elements 62 to 65 are arranged such that the ends 61 of their anchors are each arranged between the ends 45 of the individual drive elements 34 to 38, so that in the braking position they each touch two adjacent ends 45 of the plunger anchors 39 and the weft thread 3 there jam. In a modified embodiment, it is provided that individual drive elements are provided in the same number as the individual drive elements 34 to 38 and are diametrically opposed to those with respect to the weft thread 3.

As shown in FIG. 13, the thread brake 31 according to FIG. 12 can be modified in its function in that a A leaf spring 52 held in the side brackets 49 is arranged between the weft thread 3 and the front ends 45 of the individual drive elements 34 to 38.

As shown in Fig. 14, it is also possible to arrange a leaf spring 67 between the weft 3 and the individual drive elements 62 to 66, which is guided in a corresponding manner in the side brackets 49. It is also possible to change the embodiment shown in FIG. 12 by arranging one or possibly two oppositely arranged strips 53 with rods 54 between the individual drives 34 to 38 and 62 to 65 and the weft thread 3 .

The individual drive elements 34 to 38 and / or 62 to 65 of course do not have to be controlled simultaneously by the control unit 32 in order to brake a weft thread. Only selected drive elements, for example the drive elements 34, 36, 38 or, in the case of another weft thread, the drive elements 35 and 37 can be selected and controlled for braking a specific weft thread 3. The individual individual drive elements can be controlled by the control unit 32 at different times and with different force (current strength). In addition, it is also readily possible to use combinations of different braking elements in a thread brake, i.e. to combine the braking elements shown in the previous exemplary embodiments within a thread brake 31.

Brake elements, between which the weft thread is braked over a relatively large distance, as is the case, for example, in the exemplary embodiment according to FIGS. 4 and 5, are suitable for weak and few twisted weft threads. Brake elements between which the weft threads are braked only over a relatively short distance, as is the case, for example, in the exemplary embodiments according to FIGS. 2 and 3 and according to FIGS. 9 and 10, are suitable for weak and less twisted weft threads that released weaving dust. Brake elements with which the weft threads are deflected, as is the case, for example, in the exemplary embodiment according to FIGS. 6 and 7 or the exemplary embodiment according to FIG. 11, are suitable for weft threads that are rotated or release weaving dust. The brake elements shown in the embodiment according to FIG. 8 are suitable for weft threads with knobs. Depending on the type of weft thread to be braked, the brake elements of the thread brake 31 are to be determined by experiments, taking into account the above orientation guidelines, so that the most suitable brake elements are used for the respective weft thread. Since several different types of brake elements can be used in the thread brake 31 according to the invention, the thread brake is suitable for braking practically any type of weft thread.

As is also shown in FIG. 1, a device for determining the angular position of this shaft 57 is assigned to a drive shaft 57, which runs synchronously with the main drive shaft of the rapier weaving machine. In the exemplary embodiment, an angle of rotation encoder disk 58 is arranged on the shaft 57 in a rotationally fixed manner and cooperates with a sensor 59, the signals of which are input into the control unit 32 as signals of the angular position of the shaft 57. The control unit 32 evaluates these signals in order to determine the workflow of the weaving machine. An input device 60 is connected to the control unit 32, with which the course of the braking force can be entered, which is assigned to a weft thread 3, 4, 5 to be entered in the shed 6. This course of the braking force can be defined, for example, as a function of the speed course of the weft thread 3, 4, 5 entered in the shed 6, which is entered into the control unit 32.

In the embodiment according to FIG. 1, three different weft threads 3, 4, 5 are inserted in a predetermined order in the shed 6 introduced. If weft threads 3, 4, 5 of different types are introduced into the shed 6, the associated thread brakes 31 can accordingly be designed differently, ie they can each have different brakes adapted to the type of weft thread concerned elements included.

The thread brake 31 explained above is not only suitable for rapier weaving machines, but also for braking weft threads in other types of weaving machines, for example in jet weaving machines, projectile weaving machines or other types of weaving machines.

The invention is not restricted to the exemplary embodiments shown. It is readily possible to use modifications of the individual exemplary embodiments and in particular combinations of the different braking elements simultaneously with one another. The scope of protection is only determined by the patent claims.

Claims

claims

1. Thread brake (31) for braking weft threads (3, 4, 5) for a weaving machine with brake elements arranged on opposite sides of the weft thread to be braked, characterized in that ß in the running direction of the weft thread to be braked (3, 4, 5) meh¬ rere individual drive elements (34-38; 62-65) are arranged one behind the other, which can be individually controlled and which can be adjusted with the aid of a braking element in the direction of an opposite braking element.

2. Thread brake according to claim 1, characterized in that the individual drive elements (34-38, 62-65) are electrodynamic linear motors which generate a force which is essentially dependent only on the strength of the current supplied.

3. Thread brake according to claim 1 or 2, characterized gekenn¬ characterized in that the by means of the individual drive elements (34-38, 62-65) adjustable brake elements and / or the brake elements opposite the adjustable brake elements are interchangeable components.

4. Thread brake according to claim 1 or 2, characterized gekenn¬ characterized in that the individual drive elements (34-38, 62-65) with individual brake elements (45, 61) are connected.

5. Thread brake according to one of claims 1 to 3, characterized in that a common braking element (52, 53, 67) is provided which is adjustable by means of one or more of the individual drive elements (34-38, 62-65).

6. Thread brake according to claim 5, characterized in that between the weft thread to be braked (3, 4, 5) and the individual drive elements (34-38, 62-65) a leaf spring extending in the direction of the weft thread (52, 67) is arranged.

7. Thread brake according to one of claims 1 to 6, characterized in that between the weft thread to be braked (3, 4, 5) and the individual drive elements (34-38, 62-65) a bar (53) with transverse to the direction of the weft thread extending deflection elements (54) is arranged.

8. Thread brake according to one of claims 1 to 7, characterized in that the or the individual drive elements (34-38, 62-65) associated brake elements (52, 53, 67) are interchangeably attached to the thread brake (31).

9. Thread brake according to one of claims 1 to 8, characterized in that opposite to the by means of the individual drive elements (34-38) adjustable brake elements stationary brake elements (46, 55) are arranged.

10. Thread brake according to claim 9, characterized in that a component is provided which is provided with two or more, preferably different sets of brake elements (46, 55), the component (47) being in this way on a holder (49) is held that one of the sets of brake elements optionally faces the weft thread (3, 4, 5).