EP0577550B1 - Process and device for regulating the yarn tension in a warping machine - Google Patents

Description

The invention relates to a method for controlling the thread tension on a warping system according to the preamble of claim 1. The invention also relates to a device for carrying out this method according to the preamble of claim 2. The control of the thread tension in different operating states serves, on the one hand, during the warping process To ensure a uniform winding density, but also to prevent loose thread loops from forming even when the machine is at a standstill.

A known thread tensioning device in a warping device is e.g. disclosed in DE-A-37 06 872. The behavior during a machine standstill is not addressed in this document.

In the known methods and devices, an excessive decrease in the thread tension when the warping machine is at a standstill is prevented by the thread brakes being loaded somewhat compared to the normal operating position, regardless of whether the standstill was brought about in an emergency or intentionally. However, this has the disadvantage that, in both cases, a relatively large force has to be applied in order to manually transport individual threads or the entire thread bundle by a certain distance. The emergency, unwanted standstill is usually a thread break, which must be remedied by tying the thread again. The relatively high thread tension is justified here, since only the damaged thread has to be tightened. When the downtimes are scheduled as part of the processing process, however, work must usually be carried out in which the entirety of the threads has to be retightened somewhat, e.g. when the warp band is newly attached at the end of the warping process for a warp band or when crosshairs are formed by introducing cross cords. In the oversized coil gates with a large number of individual coils that are customary today, the resistance becomes so great that rational work is achieved is almost no longer possible.

It is therefore an object of the invention to control the thread tension in a more differentiated manner in order to make it easier for the operating personnel to handle it during the desired machine downtimes. In terms of the method, this object is achieved with a method with the features of claim 1 and in terms of the device with a device with the features of claim 2. By forming different control pulses depending on the type of machine standstill, it is possible to control the thread brakes differently, so that different braking forces can be set. With an intentional standstill, the standstill thread tension is kept lower than with an unwanted standstill, in that only a comparatively small braking force is applied to the thread brakes. This braking force is advantageously just large enough to avoid sagging of the threads due to their own weight.

Obviously, this means that even large thread bundles can be easily retightened manually, while the braking force remains relatively large in the event of an unwanted machine downtime due to thread breakage or the like. This is because, as a rule, repair work must be carried out on individual threads in which a change in position of adjacent threads is undesirable.

The clamping force for the desired standstill is particularly advantageously adjustable on an adjusting device on the control device. In this way, the desired thread tension can be set even during standstill.

Further advantages can be achieved if the clamping force control signal for the desired standstill can be switched off on the control device or can be set to a value which corresponds to that of the unwanted standstill. In In certain cases, it may be desirable for the clamping force to be the same, even when the machine is to be stopped between warping processes, as in the event of an emergency machine stop.

In order to always maintain the relationship between the operating thread tension and the standstill thread tension when the standstill is desired, the clamping force for both operating modes on the control device can preferably be set proportionally by a single adjusting device. With threads made of different materials and thus with different friction coefficients, approximately similar ratios of the clamping forces are always maintained.

Figur 1

eine Schäranlage mit der erfindungsgemässen Steuervorrichtung in stark vereinfachter Darstellung,

Figur 2

ein Diagramm mit der Schärgeschwindigkeit innerhalb verschiedener Betriebsphasen,

Figur 3

ein Diagramm mit dem Verlauf der Fadenspannung in den Betriebsphasen gemäss Figur 2 gemäss Stand der Technik,

Figur 4

ein Diagramm mit der Klemmkraft an den Fadenbremsen für die Erzielung der Fadenspannung gemäss Figur 3,

Figur 5

ein Diagramm mit dem Verlauf der Fadenspannung in den Betriebsphasen gemäss Figur 2 gemäss Erfindung und,

Figur 6

ein Diagramm mit der Klemmkraft zur Erzielung der Fadenspannung gemäss Figur 5.

An embodiment of the invention is illustrated in the drawings and will be described in more detail below. Show it:

Figure 1

a warping plant with the control device according to the invention in a highly simplified representation,

Figure 2

a diagram with the warping speed within different operating phases,

Figure 3

2 shows a diagram with the course of the thread tension in the operating phases according to FIG. 2 according to the prior art,

Figure 4

3 shows a diagram with the clamping force on the thread brakes for achieving the thread tension according to FIG. 3,

Figure 5

2 shows a diagram with the course of the thread tension in the operating phases according to FIG. 2 according to the invention and

Figure 6

5 shows a diagram with the clamping force to achieve the thread tension according to FIG. 5.

FIG. 1 shows a warping system known per se, consisting of a creel 1 and a warping machine 25. In the creel 1 shown in a highly simplified manner, a large number of coils 2 are arranged in vertical and horizontal rows. The threads 12 are drawn off from these bobbins and fed to the warping machine 25. A thread brake 3 and a thread monitor 4 are assigned to each bobbin or thread. The thread brakes are arranged on a brake plate 18, wherein in each case a vertical row of thread brakes can be actuated together via an adjusting rod 19. In the present exemplary embodiment, plate brakes are shown in which the thread is pulled through two plates lying one on top of the other. The clamping force is determined by a compression spring, which can be more or less compressed using the adjusting rod 19.

All actuating rods of a brake plate 18 are actuated via an actuating motor 22, which can rotate a shaft 21. The actuating rods 19 are connected to the shaft 21 via eccentrics 20, so that rotation of the shaft 21 brings about a common lifting movement of all the actuating rods.

Of course, other adjusting devices for adjusting the thread brakes are also conceivable. In addition to the adjustment via purely mechanical gears, electromagnetic or hydraulic actuations for the thread brakes are also known. After all, the thread brakes do not necessarily have to be disc brakes.

The thread monitors 4 monitor the presence of a thread or the presence of a selectable thread tension. If a thread breaks or the thread tension drops below the limit value for other reasons, the thread monitors immediately switch off the warping machine 25. The thread monitors thus function as an emergency switching device, although other emergency switching devices may also be present on the warping system. For example, every system has an emergency switch 23 provided that can be operated by the operating personnel. However, safety devices for protecting the operating personnel, such as light barriers or the like, could also serve as an emergency switching device.

The threads 12 are guided through a cross reed 5 to a warping blade 6, where the thread array is arranged into a warping belt 7. The warping belt 7 is wound onto the warping drum 9 as a winding 8.

Before striking the winding 8, the warping belt is guided around a measuring roller 10 and around a deflection roller 11. The measuring roller is movably mounted and connected to a displacement sensor 13. With the help of the measuring roller 10, the effective warping band tension is measured immediately before the warping band 7 emerges and fed to a processor 14 as the actual value.

The processor 14 performs various tasks. With the help of an input station 16, different company-specific data can be stored in the processor 14. This also includes a specific setpoint for the warp tension, i.e. for the thread tension during operation. This setpoint value is continuously compared with the actual value from the measuring roller 10, the servomotor 22 being actuated to load or unload the thread brake 3 when a deviation is determined via the control device 15.

The control device 15 is also still in operative connection with the thread monitors 4 and with other emergency switching devices, such as e.g. with the emergency switch 23. If a thread 12a breaks, for example, the control device 15 immediately triggers the warping machine 25 to come to a standstill. At the same time, the servomotor 22 is actuated in order to load the thread brakes somewhat, so that the operating thread tension changes to a standstill thread tension.

The program data stored in the processor 14 Desired machine downtimes are also triggered on the control device 15, for example after a certain length of the warping belt 7, which may also be determined via the measuring roller 10. At this desired standstill, the servomotor 22 is also actuated, but the thread brakes 3 are relieved. The desired thread tension during the desired standstill can be set continuously on the setting device 24. However, this special function can also be switched off completely, so that the standstill thread tension is the same when the standstill is wanted as when the standstill is not wanted. The entered data and / or the respectively current operating data can be read off on the screen 17.

FIG. 2 shows a typical phase of a warping process with an unwanted machine standstill triggered by thread breakage and with a desired standstill triggered by the processor. Depending on the time t, the warping speed V is plotted in the diagram.

The warping machine starts at 26 and accelerates when starting up 27 until the operating speed is reached at 28. Production 29 then takes place until an unwanted stoppage is brought about by a thread monitor 4 at 30. The machine comes to a standstill at 32 via the relatively steep deceleration section 31. The repair takes place in time 33, that is, the torn thread is tied again. At 34, the machine is restarted until it in turn reaches the target speed for further production 37 via the acceleration path 35 at 36.

At 38, a deliberate standstill is triggered by the processor. The machine decelerates again over distance 39 and at 40 comes to a complete standstill. In the downtime 41, a job is carried out in which the entire thread field generally has to be retightened, for example, the new attachment of the warping belt. In this Fall at 42 cannot immediately be ramped up to operating speed. Rather, it is only accelerated to a creep speed, which is reached at 44. In the period 45, the machine runs in the crawl gear so that it can be determined whether the work carried out has been successfully completed. Only then can acceleration again take place at 46 in order to achieve the normal operating speed for production at 47.

The time / speed diagram shown in FIG. 2 subsequently serves to represent the thread tension and the clamping force on a device according to the prior art in FIGS. 3 and 4 and on a device according to the invention in FIGS. 5 and 6.

In the diagram according to FIG. 3, the thread tension F is plotted in cN, for example, in the same time period. During the acceleration phase, the thread tension reaches the desired operating thread tension 49. In the event of an unwanted standstill, a standstill thread tension 50 is set which is somewhat lower than the operating thread tension. Without increasing the clamping force on the thread brakes, the standstill thread tension would decrease further. After restarting the machine, the operating thread tension is again reached with a slight overshoot, until the standstill thread tension 50 is reached again even when the standstill is desired, but this is the same as when the standstill is undesired. The operating thread tension must then also be reached in the crawl gear, since correct tape application must be ensured even when the machine is running slowly.

In Figure 4, the clamping force p is shown on a thread brake. In order to achieve a standstill thread tension that is only slightly below the operating thread tension in the event of an unwanted standstill, the clamping force must be increased slightly. As can be seen from Figure 4, however, both when unwanted standstill, as well as when wanted standstill approximately the same clamping forces.

The situation is different in the method according to the invention, the relationships of which are shown in FIGS. 5 and 6. In the case of both diagrams, the conditions in the case of an unwanted standstill are exactly the same as in FIGS. 3 and 4. When the standstill is desired, however, a standstill thread tension 51 is reached which is considerably lower than the standstill thread tension 50 when the standstill is inadvertent. Accordingly, the thread brake is relieved according to FIG. 6, which further supports the tendency of the thread tension to decrease when the machine is at a standstill.

Claims (5)

1. Method of controlling the yarn tension on a warping plant, a plurality of yarns (12) being withdrawn from the bobbins (2) of a bobbin creel (1) and in each case guided to a warping machine (25) via a yarn tensioner (3) and a yarn monitor (4) and, ordered to a yarn warp (7), wound at said warping machine onto a beaming drum (9), and said yarn tensioners (3) being controlled by a control device (15) in such a way that, during operation of the warping machine, an operating yarn tension is maintained and, during stoppage of the machine, a stationary yarn tension is maintained, and the operation of the warping machine furthermore being able to be interrupted by means of intentional stoppage triggered by a processor (14) according to parameters determined by the technicalities of the method, or by means of involuntary stoppage triggered by emergency switching devices (4, 23), characterized in that varying control impulses for the control device can be generated by intentional and involuntary stoppage, and that the stationary yarn tension in the case of intentional stoppage is maintained at a lower level than in the case of involuntary stoppage.
2. Device for controlling the yarn tension on a warping plant, a plurality of yarns (12) being withdrawn from the bobbins (2) of a bobbin creel (1) and in each case guided to a warping machine (25) via a yarn tensioner (3) and a yarn monitor (4) and, ordered to a yarn warp (7), wound at said warping machine onto a beaming drum (9), and the yarn tensioners (3) being controlled by a control device (15) in such a way that, during operation of the warping machine, an operating yarn tension is maintained and, during stoppage of the machine, a stationary yarn tension is maintained, and the operation of the warping machine furthermore being able to be interrupted by means of intentional stoppage triggered by a processor (14) according to parameters determined by the technicalities of the method, or by means of involuntary stoppage triggered by emergency switching devices (4, 23), characterized in that varying control signals can be generated within the control device (15) by an intentional or by an involuntary stoppage and that the yarn tensioners (3) can, in the case of intentional stoppage, be controlled to exert a clamping force that is less than in the case of involuntary stoppage, so that the stationary yarn tension in the case of intentional stoppage is less than in the case of involuntary stoppage.
3. Device according to claim 2, characterized in that, at the control device (15), the clamping force for the intentional stoppage can be set on an adjustment device (24).
4. Device according to claim 2, characterized in that, at the control device (15), the control signal for the intentional stoppage can be switched off or set at a value that corresponds to that of the involuntary stoppage.
5. Device according to one of the claims 2 to 4, characterized in that, at the control device (15), the clamping force for the intentional stoppage is, together with the clamping force for maintenance of the operating yarn tension, able to be proportionally adjusted.

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