Abstract:
In a textile machine, a device for controlling the transverse movement of a thread, such as a warp thread in a weaving machine, comprises a dragging element (2) for dragging a thread (4) moving in a transverse direction, whereby said dragging element (2) is attached on both sides to a frame (10) by means of springs (6,8). The device forms a system that oscillates freely at its natural frequency. Arresting devices (12,14) can adjustably and temporarily hold the dragging element in the extreme positions.

Description:
BACKGROUND OF THE INVENTION 
     1. Technical Subject 
     The innovation disclosed hereunder consists in a device for controlling at least one thread in a textile machine, especially a warp thread in a weaving loom. 
     2. State of the Art 
     Numerous devices for the controlling of the transverse movement of a thread in a textile machine, especially a warp thread are well known to those learned in the art. The threads are threaded through and guided by the eyes of heddles which are moved, according to a determined programme and via connecting structures, by different driving devices such as jacquard machines, heddle looms, treadle looms and colour control units. These machines and devices involve large numbers of different components, which unavoidably exerts a negative influence on the speed of the thread control mechanism. The already disclosed systems are additionally characterised by the following significant disadvantages: high forces of gravity, significant wear and tear, great emission of noise, significant vibration, enormous space requirements, high production and operating costs, poor ergonomic characteristics, etc. 
     So far, many attempts were made to eliminate these disadvantages. 
     Under U.S. Pat. No. 3,867,966, for example, a device of the type mentioned above was disclosed which attempts to eliminate the disadvantages described by way of introduction. This device comprises a dragging element inserted between two springs, which serves to drag at least one thread. An arresting device controlled by means of a control unit serves to temporarily arrest the dragging element in at least one extreme position. The dragging element is designed in the form of a heddle, which comprises a ribbon section, which contains a conductor and is located between two isolators. This ribbon section runs over a roller, which can be electrically activated. As soon as electrical current is fed to the roller or to the ribbon section, respectively, friction between the roller and the ribbon section increases so that the ribbon section can be dragged by the roller and moved to an extreme position where magnetic arresting devices are located which arrest the heddle as long as the electrical arresting devices are activated. A considerable disadvantage of this type of device, however, consists in the fact that the heddle must be equipped with a ribbon section, which contains electrically conducting elements and that dragging is effected by friction only. This causes high wear between the roller and the ribbon section. Additionally, even friction between the ribbon section and the roller cannot be guaranteed, because friction is constantly changing due to both wear and the accumulation of dirt. 
     SUMMARY OF THE INVENTION 
     The purpose of the invention disclosed hereunder consists in further improving a device of the type mentioned above. 
     The invention&#39;s characterising features employ springs and a dragging element. As the springs and the dragging element are designed as a system that oscillates freely at its natural frequency, the system, once activated, continues to oscillate independently, the only further requirement consisting in supplying a sufficient amount of energy to make up for system-related losses of energy, e.g. due to friction, etc. This energy supply, however, can be effected by extremely simple means. 
     Thus an extremely simple and economically viable device for controlling the transverse movement of at least one thread of a textile machine can be designed. Additionally, the design stands out for good wear-resistance and requires only a small energy supply to keep it operating. The arresting device allows selective control immediately at the thread-dragging element. With only few components and good wear-resistance, the device allows significantly higher drive speeds. 
     Several different advantageous designs are available. 
     One design allows programmed controlling of the device by very simple means. 
     In one design which is particularly advantageous an additional individual control can be achieved, for example, by keeping one shed open. It is, in particular, possible to adapt the oscillating system to the rotational speed of the machine connected thereto, in particular a weaving loom. The arresting device can be designed in a variety of different ways. It is, for example, possible to allocate a mechanically, pneumatically or electrically operated arresting pin to the dragging element. A particularly simple and low-wear design employs an arresting device with a releasable magnet device. The magnetic device can, for example, consist of a permanently magnetic device, which interacts with a ferromagnetic component and can be released by mechanical or pneumatic means. However, a design employing a permanent magnet influenced by an electromagnet is more advantageous. 
     To keep the oscillating system moving, energy must be supplied. This can be effected in different ways. In one design which is particularly recommended, the arresting device at the same time serves to supply the required energy as the dragging element is always lifted to the same height. A more active way of supplying energy is allowed by a piston and cylinder. In this case, a hydraulic fluid supplied to the piston and cylinder design can serve as a means to supply energy. In a particularly simple solution, on the other hand, the energy supply can be designed in such a way that it exceeds the amount of energy required to keep the oscillating system moving, thus allowing additional control effects to be achieved. 
     The device should preferably be equipped with a resetting device which temporarily renders the springs of the oscillating system ineffective. Such a resetting device is especially recommended for applications where the thread dragging elements must be moved to a centre shed position for adjusting and/or repair work. From this position, the device cannot start itself as the spring forces offset each other. Thus, the thread dragging elements must be moved to the corresponding arresting devices in one of the extreme positions by means of the resetting device. From these extreme positions, the thread dragging elements can then, due to the corresponding spring tension, be released to oscillate. The resetting device can, for example, act directly on the thread-dragging element or relieve the springs on one side. 
     The thread can be connected to the dragging element in different ways. In the simplest design the thread-dragging element is located between the springs and designed in the form of an eye. However, the unit to which the thread is connected can be located outside the oscillating system by means of an extension of the dragging element. The oscillating system can be used to control a single thread or several threads at the same time. In the latter case the dragging element can be designed in the form of a heddle frame. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Examples for the design of the invention are described below on the basis of the following drawings showing the structures indicated below: 
     FIG. 1 shows the oscillating system of a device according to the invention disclosed hereunder in the raised position. 
     FIG. 2 shows the oscillating system illustrated in FIG. 1 in the lowered position. 
     FIG. 3 shows the theoretical ideal sequence of oscillations of the oscillation system illustrated in FIG. 1 and FIG. 2. 
     FIG. 4 shows the actual sequence of oscillations of the oscillation system illustrated in FIG. 1 and FIG. 2. 
     FIG. 5 shows the oscillating system illustrated in FIG. 1 and FIG. 2 including arresting devices in the extreme positions. 
     FIG. 6 shows a controlled sequence of oscillations of the oscillation system illustrated in FIG. 5. 
     FIG. 7 shows the curve of the oscillating system depending on the rotational position of the machine connected thereto at different rotational speeds. 
     FIG. 8 shows a vertical section of a combination of an arresting device and an energy supplying mechanism. 
     FIG. 9 and FIG. 10 show a vertical section of another arresting device in the two extreme positions. 
     FIG. 11 shows a vertical section of yet another arresting device. 
     FIG. 12 shows a schematic illustration of a weaving loom equipped with the device disclosed hereunder. 
     FIG. 13 shows the load characteristic of the upper and the lower spring of the device illustrated in FIG. 12 during half an oscillation cycle. 
     FIG. 14 shows a schematic lateral view of a weaving loom with arresting devices according to FIG. 11. 
     FIG. 15 shows the weaving loom illustrated in FIG. 14 with an arresting device according to FIG. 9 and FIG. 10. 
     FIG. 16 shows a schematic lateral view of a weaving loom with another modified version of the device disclosed hereunder. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIG. 1 and FIG. 2 as well as diagrams 3 and 4 illustrate the principle underlying the invention disclosed hereunder, i.e. an oscillating system consisting of a dragging element 2 for the transverse movement of a thread 4, the dragging element 2 being attached to a machine frame 10 by means of an upper spring 6 and a lower spring 8. In the ideal case, the oscillation system would, according to curve 13 in FIG. 3, continue to oscillate indefinitely at the natural frequency f (oscillations/second): ##EQU1## where: m=mass of the oscillating system, whereby also the mass of the spring and the mass of the threads to be moved must be taken into account. 
     c=spring constant of the oscillating system, taking into account not only the upper spring 6 and the lower spring 8, but also the restoring force caused by the transverse movement of the thread 4. 
     In the ideal case--which, however, doesn&#39;t exist--the oscillating system would oscillate according to curve 13 illustrated in FIG. 3, the amplitude A being a full oscillation during time T: ##EQU2## 
     This ideal case doesn&#39;t occur in real life. Instead, friction, work of deformation, etc. consume the oscillation energy, so that the oscillating system oscillates according to curve 13a illustrated in FIG. 4, the amplitude decreasing from one oscillation to the next by ΔA. To keep the system moving, it is therefore necessary to continuously supply a smaller or larger quantity of energy. 
     FIG. 5 and diagram 6 show the oscillating system of FIG. 1 and FIG. 2, the device, however, being supplemented by an upper arresting device 12 and a lower arresting device 14, which are designed as electromagnetic units and can be controlled by a control unit 16. The arresting devices 12 and 14 deflect the oscillating dragging element 2 during each oscillation into the extreme position determined by the amplitude A. Thereby, the arresting devices 12 and 14 serve both to supply energy, as they make up for the reduction of the oscillation by ΔA, and to control the oscillating system. Thus the dragging element can for an adjustable period ts, for example for a full oscillation, be kept in the upper or lower position as this is illustrated by curve sections 13b and 13c of curve 13 in FIG. 6. Thus, the transverse movement of the thread 4 can be individually controlled in the way required, for example, for the production of patterned fabrics on a weaving loom. 
     FIG. 7 shows the curve travelled by the device during one rotation of the main shaft of a weaving loom at different rotational speeds π (rotations/second). Curve 13 shows the borderline case where the rotational speed of the weaving loom equals the frequency of the oscillating system. When the weaving loom works more slowly, the oscillating system must be stopped at periodic intervals so as to synchronise the oscillating system with the rotational speed of the weaving loom. Curve 13d shows the situation that prevails in the case of fast operating weaving looms where the arresting time per half oscillation is 2×ts1. The arresting time increases when the rotational speed of the weaving loom is reduced and amounts, for example in curve 13e where the situation prevailing when the weaving loom works more slowly is illustrated, to 2×ts2. FIG. 7 also indicates the area 15 available for weft insertion. 
     FIG. 8 shows another design of the device for the transverse movement of a thread. In this case, the dragging element 2a is provided with a rod 18 on which a piston-shaped element 20 is mounted which consists of a permanent magnet. This piston-shaped element moves within a cylinder 22 which is provided with a ferromagnetic terminal section 24 and 26 at the upper and lower end against which element 20 is arrested in the upper or lower extreme position, respectively. Cylinder 22 contains a coil 28, which is connected with the control unit 16 via wires 30. Depending on the activation of the coil 28, this device performs different tasks. On the one hand, the coil can be used to release element 20 from the ferromagnetic terminal section 24 or 26 so as to trigger the oscillating movement. On the other hand, the coil 28 can be activated in such a way that it supports the movement of the element 20 and, thus, the movement of the dragging element 2a against the terminal section 24 or 26, respectively. In this case, coil 28 serves to supply the oscillating system with energy. The system can be designed in such a way that the cylinder 22 extends over the entire travelling distance of the dragging element 2a. It is, however, also possible to divide the cylinder 22 and to limit it, as shown in FIG. 11, to the extreme positions of the oscillating system. Instead of the coil, the cylinder can also be connected to a hydraulic fluid system, which can serve to provide a controlled energy supply. 
     FIG. 9 and FIG. 10 show another dragging element 2b which is provided with a rod 32 on which two piston-shaped elements 34 and 36 are mounted between arresting devices 12b and 14b which are mounted in block-type arrangement. In this case the arresting device 12b, which marks the upper extreme position and to which the piston-shaped element 34 adheres, is located at the bottom and the arresting device 14b, which marks the lower extreme position and to which element 36 adheres, at the top. The arresting devices 12b and 14b consist of permanently magnetic rings 38 arranged in such a way that their identical poles are facing each other. Within each ring 38, there are electromagnets 40, which can be operated by the above-mentioned control unit 16. As soon as the extreme position is reached, the piston-shaped elements 34 and 36 adhere to the respective arresting devices 12b and 14b and are released only upon activation of the electromagnets 40 to perform another oscillating movement. 
     FIG. 11 shows the device illustrated in FIG. 9 and FIG. 10, the arresting devices 12c and 14c, however, being arranged at a distance from each other which defines the travelling distance and the dragging element 2c being provided with only one piston-shaped element 42 which moves between the two arresting devices 12c and 14c. 
     FIG. 12 contains a schematic illustration of a weaving loom provided with the devices disclosed hereunder. The weaving loom contains a warp beam 44 around which warp threads 46 are wound and which are fed over a guide roller 48 to the weaving site 50. The devices 52 disclosed hereunder are used to control the warp threads 46 and to create the shed 54 into which weft threads 56 are inserted and arrested by means of a weaving reed 58. The resulting fabric 60 is removed via an outfeed unit 62. The control unit 52 contains a dragging element 2a and an arresting device 12a and 14a according to FIG. 8. The dragging element 2a is provided with a heddle 64, which contains an eye 66 for the dragging of a warp thread 46. The control unit 52 is, additionally, provided with a resetting device 68 which comprises an arm 72 which swivels around axle 70 and to which the lower end of the respective lower spring 8 is attached. An actuator 74 can move the swivelling arm upwards, thus relieving the springs 8. The resetting device 68 is used to take the control unit 52 back into the initial position required to put the system into operation in which the piston-shaped element 20 adheres to the respective arresting device 12a or 14a, should a reset be required for any reason, e.g. after adjustment or repair work. Such a situation exists, for example, when the eyes are located in the centre shed 76. Then the lower springs 8 are relieved upon operation of the actuator 74 whereupon the spring force of the upper springs 6 prevails so that the piston-shaped elements 20 can be moved towards and adhere to their respective upper arresting devices 12a. 
     FIG. 13 shows the spring force characteristics of the springs 6 and 8, Ko referring to the upper spring 6 and Ku to the lower spring 8, Kr being the force characteristics resulting for the dragging element 2a. This illustration shows that no force acts upon the dragging element when the dragging element 2a is located in the centre shed 76, which means that a resetting device 68 is needed to take the dragging element 2a back to one of the arresting devices. 
     FIG. 14 shows a schematic illustration of another weaving loom designed in analogy to the weaving loom shown in FIG. 12 but provided with arresting devices 12c and 14c according to FIG. 11. FIG. 15 contains a schematic illustration of the equipment of a weaving loom with the arresting devices 12b and 14b according to FIG. 9 and FIG. 10. 
     FIG. 16 shows the weaving loom schematically illustrated in FIG. 14, the eye 78 for the dragging of the warp thread 46, however, not being located within, i.e. between the upper and the lower spring 6 and 8 but outside. For this purpose, the dragging element 2d is designed in the form of a rod which is extended upward through the upper spring 6 and provided with the eye 78 in this extended section. 
     In the designs presented, the thread-dragging element is usually illustrated as an eye for the dragging of a single thread. The arrangement, however, can also be designed in such a way that the dragging element is, instead of an eye, connected to a known heddle frame design which can be used to control several threads at the same time. 
     Due to the elimination of the state of the art connecting elements and the known upstream shedding machines, the device disclosed hereunder can, for example, be used to achieve the following significant characteristics or advantages, respectively: 
     Significantly reduced space consumption. Thus the workplace can be optimally designed. 
     The top of the machine need not be provided with additional structures. This offers the advantage of an optimal view over the entire machine and better handling. 
     Small forces of inertia as fewer parts are moving. Therefore, higher rotational speeds are possible. 
     Small number of wearing points and practically no vibrations. This allows a high reduction of the noise emission level. 
     Dramatic reduction of the danger of accidents due to fewer critical moving parts. 
     Simple maintenance due to simple parts and few components. 
     The workplace can be optimally equipped from an ergonomic point of view. 
     The cost of the device disclosed hereunder is extremely low, as no expensive additional components are required. Economically viable textile production is possible both in high and in low wage countries. 
     No harness, no beams and utilisation of the oscillation energy. Thus enormous energy savings are possible. Energy is only supplied to make up for friction losses. 
     No force from spring restoring devices and no forces of inertia due to acceleration of the connecting elements. 
     
         ______________________________________LIST OF REFERENCES______________________________________A             amplitudeΔA      lost share of the amplitudeT             durationTs            arresting timets1           arresting time at fast operationts2           arresting time at slow operation 2            dragging element 2a           dragging element 2b           dragging element 2c           dragging element 2d           dragging element 4            thread 6            spring, upper 7            spring, lower10            machine frame12            arresting device, upper12a           arresting device, upper12b           arresting device, upper12c           arresting device, upper13            oscillation curve (ideal)13a           oscillation curve (actual)13b           curve section, upper13c           curve section, lower13d           oscillation curve, fast operation13e           oscillation curve, slow operation14            arresting device, lower14a           arresting device, lower14b           arresting device, lower14c           arresting device, lower15            weft insertion area16            control unit18            rod20            piston-shaped element22            cylinder24            ferromagnetic terminal section26            ferromagnetic terminal section28            coil30            wire32            rod34            piston-shaped element36            piston-shaped element38            ring40            electromagnets42            piston-shaped element44            warp beam46            warp thread48            deflection roller50            weaving site52            control unit54            shed56            weft thread58            weaving reed60            fabric62            outfeed unit64            heddle66            eye68            resetting device70            axle72            arm74            actuator76            centre shed78            eye______________________________________