Method for prophylactic identification of shutdown state in drafting mechanism of spinning machine and drafting mechanism of spinning machine

Abstract

The invention relates to a method for preventing a drafting unit of a spinning preparation machine from being damaged due to winding, in which the drafting unit (S) has at least two drafting unit rollers (1-4, I-III) which can be pressed against each other and which can be pressed against each other by means of an application device (9a, 9b, 9c), the application device (9a, 9b, 9c) being connected to a running medium circuit (28), and the running medium circuit (28) being connected to the drafting unit rollers (1-4, I-III). The method comprises the following steps: detecting an actual operating medium pressure (p1-Ist) in the operating medium circuit (28) by means of at least one pressure sensor (29); monitoring a temporal change of the actual operating medium pressure (p1-Ist) by means of a control device (31) coupled to the pressure sensor (29); when a predetermined threshold value for the change over time of the actual operating medium pressure (p1-Ist) is exceeded, the drafting mechanism is shut down by the control device (31) and / or a signal is triggered by the control device (31). The invention also relates to a drafting mechanism of a spinning machine.

Description

Field of the Invention

[0001] The present invention relates to a method for prophylactically identifying a stopped state in a drafting mechanism of a spinning machine and to a drafting mechanism of a spinning machine according to the features of the independent claims. Background Art

[0002] In a drafting mechanism of a spinning machine, one or more fed sliver(s) respectively pass through the gap between pairs of rollers (one upper roller and one lower roller each) formed by the drafting mechanism rollers and are drafted into a composite sliver. This composite sliver can then be spun into a yarn in a further process.

[0003] When the drafting mechanism is running, due to the fibers of the sliver winding around the rollers, it often happens that the fiber material winds around the outer circumference of the upper roller or the lower roller, i.e., so-called winding formation. If not recognized, this accumulation can lead to severe winding and interfere with the operation of the drafting mechanism. In such a case, the drafting mechanism must be stopped and the winding removed. For this reason, corresponding monitoring devices have been developed in the past to detect the presence of winding. Thus, there are tactile monitoring devices that detect the already formed, i.e., existing, winding.

[0004] In such a known tactile monitoring device (EP 1428914A), the piston rods of pressure medium cylinders are mounted on two axial ends of the shaft of the upper roller. A switch disk is movably and frictionally mounted on the piston rod coaxially with the piston and cooperates with a switch for determining the position of the piston. The switch disk is at least partially permanent magnet in order to cooperate with an inductive sensor that serves as a switch for determining the piston position. If now fiber material forms a winding around the upper roller, then the floating-mounted upper roller is pressed against the pressure medium cylinder at one axial end of the shaft of the drafting roller. The pressure rod of the pressure medium cylinder contacting the upper roller thus moves towards the moved-in end position. When the pressure rod moves in, the switch disk frictionally mounted here closes the switch, and the drafting mechanism is shut down. Now, the drafting mechanism is manually opened and the winding removed. Then, the drafting mechanism is brought back into the operating position by closing the loading arm. The structure of such a tactile monitoring device for detecting winding is relatively complex and susceptible to influence.

[0005] It is known from DE 102108125547A1 that when the pressure of the upper roller of the drafting mechanism of such a drafting mechanism exceeds or falls below a specific threshold, the pressure is adjusted again. However, this document discloses using pressure monitoring not for detecting the formation or presence of winding, but for reducing the wear of the drafting mechanism rollers. Summary of the Invention

[0006] Therefore, starting from this, the task is to provide a method for prophylactically identifying a standstill state in the drafting mechanism of a spinning machine and a drafting mechanism of a spinning machine, both of which are improved compared to the prior art. In particular, the formation of winding at the drafting mechanism rollers of such a drafting mechanism should be identified early, and at the same time, a relatively low-cost, less complex and less susceptible structure of such a monitoring device should be provided.

[0007] This task is solved by a method according to the independent claims for prophylactically identifying a standstill state in the drafting mechanism of a spinning machine and such a drafting mechanism according to the invention.

[0008] Furthermore, this task is also solved by a drafting mechanism of a spinning machine according to the invention, which drafting structure has at least two opposing drafting mechanism rollers that can be pressed against each other by a working medium. Here, this can be a drafting mechanism with any number of upper and lower rollers, for example a four-over-three drafting mechanism, a two-over-two drafting mechanism or other variants of the drafting mechanism. The technical solutions described in the dependent claims are particularly preferred embodiments of the invention.

[0009] A method according to the invention for prophylactically identifying a standstill state in a drafting mechanism of a spinning machine caused by the formation of winding between at least two opposing drafting mechanism rollers that can be pressed against each other, said drafting mechanism comprising at least two opposing drafting mechanism rollers that can be pressed against each other by means of a loading device. The loading device is connected to a working medium circuit.

[0010] At least one pressure sensor detects the actual working medium pressure (p 1-Ist ) in the working medium circuit. A control device coupled to the pressure sensor monitors the change in the actual working medium pressure (p 1-Ist ) over time. When a threshold value preset for the change in the actual working medium pressure (p 1-Ist ) over time is exceeded, the drafting mechanism is shut down and / or a signal is triggered by the control device (31).

[0011] The recognition on which the present invention is based is that when winding is formed between two drafting mechanism rollers, the actual working medium pressure differs from other operating states in terms of height and time course such that the formation of winding can be distinguished from spinning, thin point generation and bobbin change. In particular, the height of the pressure increase and the short time course give clues here, i.e., the control device can recognize the formation of winding by means of the change in the actual working medium pressure and can thus shut down the drafting mechanism and / or trigger an alarm or a signal. Here, when the change in the pressure curve of the actual working medium pressure is a pressure increase of at least 100 mbar, the control device can shut down the drafting mechanism.

[0012] In contrast to other operating states, the pressure increase persists for at least 100 milliseconds. A pressure increase within a shorter time can indicate thick spots in the sliver or thin spots that occur before bobbin change.

[0013] In order to locally determine the formation of a wrap, i.e., exactly between which pairs of drafting mechanism rollers the wrap is formed, the actual operating medium pressure in each pipeline can be determined individually for each top roller.

[0014] Supplemented, the actual operating medium pressure can be compared with the rated operating medium pressure in the control device, and when the rated operating medium pressure is exceeded, it can be used as an additional signal for shutting down the drafting mechanism and / or for triggering a signal or an alarm. Thus, the method for monitoring the formation of a wrap can be protected against possible false alarms.

[0015] Supplemented, the distance between the drafting mechanism rollers can be detected by means of a displacement sensor, and the control device can be configured to distinguish between spinning, thin spot generation, bobbin change, and wrap formation for each pair of drafting mechanism rollers. Here, the height, position, and time course of the distance change are also determining factors for distinguishing the respective operating states such as spinning, thin spot generation, bobbin change, and wrap formation. Determining the distance between the drafting mechanism rollers can be used to determine the location of wrap formation when there is only one pressure sensor arranged in the operating medium circuit, and / or for re-verifying the signal for shutting down the drawframe, i.e., for avoiding possible false shutdowns.

[0016] The drafting mechanism of a spinning machine according to the invention comprises at least one pair of rollers consisting of drafting mechanism rollers, which are constructed with a gap between them, and in the normal operation of the drafting mechanism, the fibrous material passes through the gap in the form of a sliver. The drafting mechanism has at least one loading device, which is configured to adjust the pressing pressure of at least one of the two drafting mechanism rollers relative to each other. The loading device is connected to the operating medium circuit in order to relatively press one of the at least two drafting mechanism rollers. At least one pressure sensor is arranged in the operating medium circuit, which is connected to a control device assigned to the drafting mechanism in order to place the drafting mechanism in a stop state when a wrap formation is recognized or to output an acoustic or optical signal to a signaling device connected to the control device. Here, the control device is configured to execute the method according to one of the method claims.

[0017] The operating medium circuit can be configured as a pneumatic circuit, where the operating medium is air or a gas mixture and the pressure sensor is configured as a compressed air sensor. Preferably, an air compressor, such as a compressor, is arranged in the pneumatic circuit.

[0018] The pressure sensor is arranged in the operating medium circuit for all upper rollers, or a pressure sensor for monitoring the nip pressure of each individual upper roller can be arranged in each pipeline. Thereby, the winding formation can be determined locally.

[0019] Each pair of drafting mechanism rollers can have a sensor for determining the distance between the drafting mechanism rollers, wherein these sensors are configured to transmit sensor data to the control device. Determining the distance between the drafting mechanism rollers can be used to determine the position of the winding formation when there is only one pressure sensor arranged in the operating medium circuit, and / or to re-verify the signal for shutting down the draw frame, that is, to avoid possible false shutdowns. The height, position, and time course of the distance change can be used to distinguish various operating states such as spinning, thin point generation, bobbin change, and winding formation. Brief Description of the Drawings

[0020] Hereinafter, together with the description of the preferred embodiments of the present invention, other measures for improving the present invention will be described in more detail with the aid of the drawings.

[0021] In the drawings:

[0022] Figure 1 A schematic side view showing a possible embodiment of a four-over-three drafting mechanism;

[0023] Figure 2 Another schematic side view showing an embodiment as a two-over-two drafting mechanism;

[0024] Figure 3 A fragment showing the time course of the actual nip pressure indirectly detected at two drafting mechanism rollers of the drafting mechanism designed according to the present invention. Detailed Description of the Invention

[0025] Figure 1 The drafting mechanism S according to the present invention is shown in a very schematic and thus non-scale side view. The drafting mechanism S can be part of a draw frame. In this embodiment, it is designed as a four-over-three drafting mechanism, that is, it consists of three lower rollers I, II, III (I is the output lower roller, II is the intermediate lower roller, and III is the input lower roller) and four upper rollers 1, 2, 3, 4. The roller pairs formed by the upper rollers 1, 2, 3, 4 and the lower rollers I, II, III are each provided with a gap therebetween, and the fiber sliver fed into the drafting mechanism passes through this gap and is drafted into a composite fiber sliver 5. Therefore, in the drafting mechanism S, the composite fiber sliver 5 is stretched, and this stretching consists of pre-stretching and main stretching.

[0026] In the present case, the roll pairs 4 / III and 3 / II form a pre-drawing zone, and the roll pairs 3 / II and 1 and 2 / I form the main drawing zone. The output lower roll I is driven by a main motor (not shown) and thus determines the supply speed. The input lower roll and the intermediate lower rolls III or II are driven by an adjusting motor (not shown).

[0027] At least one roll pair consisting of drafting mechanism rolls (such as the upper roll 4 and the lower roll III) is constructed with a distance a or a gap between each other, through which the composite fiber strip 5 can pass during the normal operation of the drafting mechanism. At least one drafting mechanism roll (here the upper roll 4) is movably supported relative to the other drafting mechanism roll in the roll pair (here the lower roll III) such that when the fiber material forms a wrap in the gap, it avoids the lower roll III when the distance a increases.

[0028] The upper rolls 1 - 4 are pressed onto the lower rolls I, II, III by the loading device 30 and thus obtain drive from the rotating lower rolls I, II, III through frictional engagement. The rotational directions of the drafting mechanism rolls I, II, III and 1, 2, 3, 4 are indicated by the curved arrows. The loading device 30 is provided with a plurality of pressure elements 9 1 to 9 4 , which are respectively connected in a flow-guiding manner to the operating medium circuit 28 through the pipelines 28a, 28b, 28c and 28d. The operating medium circuit 28 guides an operating medium, such as air or a gas mixture, in order to load the pressure elements 9 with the operating medium 1 to 9 4 , which pressure elements can be constructed as piston-cylinder units, for example. Correspondingly, the operating medium circuit 28 is currently constructed as a pneumatic circuit in which the operating medium pressure p 1 is adjustable. An air compressor, such as a compressor, can be arranged in the pneumatic circuit, and the adjustment of the operating medium pressure p 1 can be carried out through a regulating valve (not shown).

[0029] A pressure sensor 29 is also arranged in the operating medium circuit 28, which is constructed as a compressed air sensor. The pressure sensor 29 continuously detects the actual operating medium pressure p 1-Ist present in the operating medium circuit 28 here. The pressure sensor 29 is connected to the control device 31 assigned to the drafting mechanism S through a line (shown as a dotted line here). The control device 31 is configured to compare the actual operating medium pressure p 1-Ist with a preset rated operating medium pressure p 1-Soll . The upper rolls 1, 2, 3, 4 can be respectively provided with displacement sensors 10 1 -10 4 , which displacement sensors can be arranged on one side or both sides of the upper roll support or the pressure element 9 respectively1 -9 4 is above and integrated therein. The displacement sensor 10 1 -10 4 is likewise connected to the control device.

[0030] If the drafting mechanism S is started from a standstill state without a fiber sliver, then first, in order to set the desired pressing pressure of at least two of the drafting mechanism rollers 1 - 4, I - III of the drafting mechanism, the corresponding operating medium pressure p in the operating medium circuit 28 is set 1 . Thereby, the pressure element 9 of the loading device 30 1 to 9 4 presses the upper rollers 1 - 4 onto the lower rollers I - III respectively. The composite fiber sliver 5 passes through between the drafting mechanism rollers 1 - 4, I - III in the traction direction A and is drafted. This corresponds to the normal operation of the drafting mechanism S. At the same time, the distance a between the upper rollers 1 - 4 and the lower rollers I - III is less than the rated distance a - Soll , which is set based on the quality of the fiber sliver to be drafted, because at this time point no fiber sliver has passed through the drafting mechanism yet.

[0031] Now, the control device 31 monitors the actual operating medium pressure p present in the operating medium circuit 28 through the pressure sensor 29 1-Ist and thus monitors the pressure change exerted by the at least two drafting mechanism rollers 1 - 4, I - III on each other in order to determine the situation where the fiber material from the composite fiber sliver 5 forms a wrap around one of the drafting mechanism rollers 1 - 4, I - III.

[0032] Such a wrap can be indirectly detected by the actual operating medium pressure p 1-Ist , that is, when the fiber material begins to wrap around the roller 4, for example. Due to the wrapping, the distance a 4 / III between the upper roller 4 and the lower roller III increases, that is, the upper roller 4 moves away from the lower roller III and exerts a reaction force on the loading device 30 (here the pressure element 9 4 ). This change in distance can be detected by the displacement sensor 10 4 .

[0033] This reaction force cancels out the pressing force of the pressure element 9 1 caused by the operating medium pressure p 4 . The reaction force of the upper roller 4 on the pressure element 9 4 in turn causes the compression of the piston - cylinder unit of the pressure element 9 4 and thus causes the preset rated operating medium pressure p 1-Soll to rise to the actual operating medium pressure p 1-Ist . Due to the formation of a wrap, the distance a between the two drafting mechanism rollers 4, III4 / III be changed or increased.

[0034] Figure 2 Fig. shows a two-up-and-two-down drafting mechanism according to the present invention, which is configured as a single-zone drafting mechanism with a single drafting zone. Like the drafting mechanism of the embodiment of Figure 1 , it can be configured as a controlled or uncontrolled drafting mechanism.

[0035] The drafting mechanism S shown here consists of two lower rollers I, II (I is the output lower roller, II is the input lower roller) and two upper rollers 1, 2. The roller pairs formed by the upper rollers 1, 2 and the lower rollers I, II are respectively provided with gaps between each other. The sliver fed into the drafting mechanism passes through the gaps and is drafted into a composite sliver 5. That is to say, the stretching of the composite sliver 5 is carried out in the drafting mechanism S, and this stretching consists of pre-stretching and main stretching.

[0036] The output lower roller I is driven by a main motor (not shown) and thus determines the supply speed. The input lower roller II can be driven by an adjusting motor (not shown).

[0037] At least one roller pair formed by the drafting mechanism rollers (such as the upper roller 2 and the lower roller II) is provided with a distance a or a gap between each other. In the normal operation of the drafting mechanism, the composite sliver 5 can pass through the distance or gap along the traction direction A. Among them, at least one drafting mechanism roller (here is the upper roller 2) is movably supported relative to the other drafting mechanism roller in the roller pair (here is the lower roller II) so that when the fiber material forms a winding in the gap, it can avoid the lower roller II when the distance a is increased.

[0038] The upper rollers 1-2 are pressed against the lower rollers I, II by a loading device 30 and thus obtain drive from the rotating lower rollers I, II through frictional engagement. The loading device 30 is provided with a plurality of pressure elements 9 1 to 9 2 , and these pressure elements are respectively connected to the working medium circuit 28 in a flow-guiding manner through pipelines 28a, 28b. The working medium circuit 28 guides a working medium, such as air or a mixed gas, in order to load the pressure elements 9 1 to 9 2 , and these pressure elements can be configured as piston-cylinder units, for example. Correspondingly, the working medium circuit 28 is currently configured as a pneumatic circuit, in which the working medium pressure p 1 is adjustable. An air compressor, such as a compressor, can be arranged in the pneumatic circuit, and the adjustment of the working medium pressure p 1 can be carried out through a regulating valve (not shown).

[0039] In the operating medium circuit 28, a pressure sensor 29 is also arranged, which is configured as a compressed air sensor. The pressure sensor 29 continuously detects here the actual operating medium pressure p present in the operating medium circuit 28 1-Ist . The pressure sensor 29 is connected via a line (represented here by a dashed line) to the control device 31 assigned to the drafting mechanism S. The control device 31 is configured to compare the actual operating medium pressure p 1-Ist with a preset nominal operating medium pressure p 1-Soll . The upper rollers 1, 2 can each be equipped with a displacement sensor 10 1 -10 2 , and these displacement sensors can be arranged on one or both sides of the upper roller support or the pressure element 9 1 -9 2 respectively and integrated therein. The displacement sensors 10 1 -10 2 are likewise connected to the control device.

[0040] If the drafting mechanism S is started from a stopped state without a sliver, then first, in order to set the desired pressing pressure of at least two of the drafting mechanism rollers 1-2, I-II of the drafting mechanism, the corresponding operating medium pressure p in the operating medium circuit 28 is set 1 . Thereby, the pressure elements 9 1 to 9 2 of the loading device 30 press the upper rollers 1-2 against the lower rollers I-II respectively. The composite sliver 5 passes between the drafting mechanism rollers 1-2, I-II and is drafted. This corresponds to the normal operation of the drafting mechanism S. At the same time, the distance a between the upper rollers 1-2 and the lower rollers I-II is less than the nominal distance a- Soll , which is set based on the mass of the sliver to be drafted, because no sliver is running through the drafting mechanism at this time point.

[0041] Now, the control device 31 monitors the actual operating medium pressure p present in the operating medium circuit 28 via the pressure sensor 29 1-Ist and thus monitors the pressure change exerted by the at least two drafting mechanism rollers 1-2, I-II on each other in order to determine the situation where the fiber material from the composite sliver 5 forms a wrap around one of the drafting mechanism rollers 1-2, I-II.

[0042] Such a wrap can be detected indirectly by the actual operating medium pressure p 1-Ist , i.e., when the fiber material begins to wrap around the upper roller 2, for example. Due to the wrapping, the distance a 2 / II between the upper roller 2 and the lower roller II increases, i.e., the upper roller 2 moves away from the lower roller II and acts on the loading device 30 (here the pressure element 9 2)Apply a reaction force. This distance change can be detected by the displacement sensor 10 2 and detected.

[0043] This reaction force cancels out the pressing force of the pressure element 9 1 caused by the operating medium pressure p 2 The upper roller 2's reaction force on the pressure element 9 2 in turn causes the compression of the piston-cylinder unit of the pressure element 9 2 and thus causes the preset rated operating medium pressure p 1-Soll to be raised to the actual operating medium pressure p 1-Ist . Due to the formation of winding, the distance a 2 / II between the two drafting mechanism rollers 2, II changes or increases.

[0044] Three diagrams are shown stacked one above the other in Figure 3 and refer to the embodiment of Figure 2 . Of course, this diagram also applies to the embodiment of Figure 1 where the input drafting mechanism roller 4 / III replaces the input drafting mechanism roller 2 / II at a distance a 4 / III predicted. The output drafting mechanism roller 1 / I remains marked unchanged.

[0045] A possible pressure-time diagram fragment is shown in the lower diagram, which shows the time course of the pressing pressure indirectly detected by the actual operating medium pressure p 1-Ist at the two relatively pressed input drafting mechanism rollers 2 and II of the drafting mechanism S designed according to the invention. The dashed line shows the rated operating medium pressure p 1-Soll , and the actual operating medium pressure p 1-Ist deviates from this rated operating medium pressure over time. The actual operating medium pressure p 1-Ist is detected by the pressure sensor 29.

[0046] The distance a1 / I of the output roller pair 1 / I at the same time course is shown in the middle diagram.

[0047] The distance a2 / II of the input roller pair 2 / II at the same time course is shown in the upper diagram.

[0048] The time courses of all three diagrams are the same.

[0049] Before the start of spinning, i.e., before time t 0 , all the drafting mechanism rollers are separated from each other, so that the distance a 2 / II of the input roller pair 2 / II shown in the diagram 1 / I and the distance a

[0050] At time point t 0 , the drafting mechanism S transfers from the stopped state to normal operation, i.e., the composite fiber sliver 5 is introduced between the drafting mechanism rollers 1-2, I-II, and the pressure element 9 1 -9 2 is loaded with the operating medium, and the drafting mechanism rollers 1-2, I-II move towards each other, are relatively pressed together and rotate. Initial pressure = actual operating medium pressure p 1-Ist , which is higher than the rated operating medium pressure p 1-Soll and levels off below the rated operating medium pressure p 1-Soll .

[0051] At time point t 1 , after the drafting mechanism S has started and is thus in normal operation, the composite fiber sliver 5 is drafted as desired. For this purpose, the corresponding actual operating medium pressure p of the drafting mechanism rollers 1-2, I-II appears 1-Ist , which is briefly higher than the rated operating medium pressure p 1-Soll , but then continuously drops below the rated operating medium pressure p 1-Soll . The distances a 1 / I and a 2 / II decrease with spinning and level off to a consistent level between time point t 1 and t 2 without significant changes.

[0052] At time point t 2 , a bobbin change is carried out, which causes a pressure change and is due to a thin spot in the composite fiber sliver 5 resulting from the change. The distance a briefly decreases at the output roller pair 1 / I 1 / I , while the distance a of the input roller pair 2 / II 2 / II remains almost constant without sudden changes, and its level only drops slightly. The actual operating medium pressure p of the drafting mechanism rollers 1-2, I-II 1-Ist constantly remains below the rated operating medium pressure p 1-Soll .

[0053] At time point t 2 after a thin spot has occurred in the composite fiber sliver 5, the bobbin change starts at time point t 3 . Here, the drafting mechanism S can operate at a slightly reduced processing speed, which becomes noticeable at the input roller pair 2 / II by a brief accumulation of fiber material, whereby the distance a 2 / II first suddenly increases and then decreases. The actual operating medium pressure p 1-Ist also suddenly rises by a small value, but still remains below the rated operating medium pressure p 1-Soll . At the same time, the distance a of the output roller pair 1 / I 1 / I slightly decreases.

[0054] Now, at time point t 4 , a winding is formed between the rollers 2 / II of the drafting mechanism. Here, the instantaneous actual operating medium pressure p 1-Ist detected by the pressure sensor 29 suddenly increases and rises above the rated operating medium pressure p 1-Soll within at least a short time interval of 100 ms, and then suddenly drops again. The control device 31 identifies the sudden pressure increase based on the slope of the curve and shuts down at least the drafting mechanism S. The control device is configured to shut down the drafting mechanism when the actual operating medium pressure p 1-Ist changes by at least 100 mbar within at least 100 ms.

[0055] In addition to the sudden increase in the actual operating medium pressure p 1-Ist , the control device is also configured to shut down the drafting mechanism S when the rated operating medium pressure p 1-Soll is exceeded. The two limit values can be combined with each other, where only the change in the actual operating medium pressure p 1-Ist is sufficient to identify a winding.

[0056] Shortly before the sudden increase in the actual operating medium pressure p 1-Ist , the distance a 2 / II at the input roller pair 2 / II suddenly increases to the level before time point t 0 (i.e., before spinning). This occurs because, for example, the upper roller 2 entangled by the fiber material of the composite fiber sliver 5 is now pushed away from the lower roller II due to material accumulation. As a result, the distance a 2 / II of the input roller pair 2 / II changes with a sudden change, while at the same time, the distance a 1 / I of the output roller pair 1 / I suddenly decreases because less sliver passes through the drafting mechanism S due to the formation of a winding.

[0057] To continuously monitor the possible formation of a winding, the control device 31 now detects the change in the actual operating medium pressure p 1-Ist of at least two drafting mechanism rollers 1-2, I-II, or rather its change over time, so as to be able to determine the pressure change. For this purpose, the control device 31 detects the current actual operating medium pressure p 1-Ist by means of the pressure sensor 29.

[0058] Additionally, the actual operating medium pressure p 1-Ist is compared with a preset rated operating medium pressure p 1-Soll . The rated operating medium pressure p 1-Soll can be preset here as a fixed value, corresponding to the dashed line. During the comparison, the control device 31 now forms the preset rated operating medium pressure p 1-SollThe difference from the actual operating medium pressure p 1-Ist If the actual operating medium pressure p 1-Ist now exceeds the rated operating medium pressure p 1-Soll , then in addition to the change in the pressure curve of the actual operating medium pressure p 1-Ist , the control device 31 can also infer the presence of winding.

[0059] In all embodiments of the drafting mechanism according to Figure 1 and Figure 2 , monitoring only the change in the pressure curve of the actual operating medium pressure p 1-Ist is sufficient to identify the formation of winding. In addition, the actual operating medium pressure p 1-Ist exceeding the rated operating medium pressure p 1-Soll can protect the system against false shutdown. Both can be carried out simultaneously for all upper rollers 1, 2, 3, 4 by means of a pressure sensor 29 in the operating medium circuit 28. Alternatively, a separate pressure sensor can be arranged in each of the pipelines 28a, 28b, 28c, 28d, which monitors the formation of winding for each individual upper roller 1, 2, 3, 4.

[0060] Another supplementary solution for the two variants of monitoring the formation of winding can be achieved by the measurement results of the displacement sensor 10 1 -10 4 , because with the formation of winding, the distance between the corresponding upper roller and the lower roller also changes. This does not necessarily always have to be carried out at the input roller 4 / III.

[0061] Only the change in the pressure curve of the actual operating medium pressure p 1-Ist is sufficient for the control device to identify the formation of winding. If the pressure sensor 29 is only arranged in the operating medium circuit 28, then by means of the measurement results of the displacement sensor 10 1 -10 4 , not only can false operation be prevented, but also the position where the winding is formed can be identified by the control device. For this purpose, it is not necessary to introduce a signal that the actual operating medium pressure p 1-Ist exceeds the rated operating medium pressure p 1-Soll . However, this signal can make the method operate more safely.

[0062] If the pressure sensor 29 is arranged separately in each of the pipelines 28a, 28b, 28c, 28d, then by means of the measurement results of the displacement sensor 10 1 -10 4 , not only can false operation be prevented, but also both through the change in the pressure curve of the actual operating medium pressure p 1-Ist , and through the measurement results of the displacement sensor 10 1 -104 The signal is used by the control device to identify the position where the winding is formed. For this purpose, it is not necessary to introduce the actual operating medium pressure p to prevent incorrect operation. 1-Ist exceeding the rated operating medium pressure p 1-Soll of the signal. However, this signal can make the method operate more safely.

[0063] As Figure 1 and Figure 2 shown, the control device 31 is connected to the signal device 32 via a line (dashed line) so as to output an acoustic or optical signal to the signal device 32 when the winding formation is recognized. Alternatively, it can subsequently automatically place the drafting mechanism S in a stopped state.

[0064] Therefore, with the aid of the present invention, the formation of winding at the drafting mechanism rollers of such a drafting mechanism can be recognized at an early stage without providing a complex and vulnerable structure for triggering the monitoring device.

[0065] In addition, with the aid of the present invention, it can also be recognized whether a change in the pressing pressure relates to winding (i.e., a harmful pressure change) or an innocuous pressure change in the pressing pressure. Such an innocuous pressure change in the pressing pressure may be caused, for example, by bobbin change or automatic spinning. During automatic spinning, the upper roller has been loaded by a loading device or a pressure element.

[0066] In Figure 1 the embodiment, the pressure sensor 29 is integrated in the pipeline 28, so that the pressure sensor 29 simultaneously detects the formation of winding at all four upper rollers 1, 2, 3, 4. In this embodiment, it is necessary to evaluate the displacement sensor 10 1 -10 4 , in order to determine the position where the winding is formed.

[0067] In each pipeline 28a, 28b, 28c, 28d, a separate pressure sensor 29 is arranged for each upper roller 1, 2, 3, 4. This arrangement enables the detection of the formation of winding and the winding position (i.e., at which pair of rollers the winding is formed). Of course, each sensor is also separately connected to the control device 31. For this purpose, the evaluation or availability of the displacement sensor is not required, but incorrect operation can be avoided. For the control device 31, the monitoring of the height of the actual operating medium pressure p 1-Ist higher than the rated operating medium pressure p 1-Soll is likewise not necessary for identifying the formation of winding, but can additionally be used to avoid incorrect operation. The control device 31 can compare the values via the signals of each pressure sensor and is thus configured to distinguish between spinning, winding, and bobbin change.

[0068] List of reference numerals

[0069] 1, 2, 3, 4 upper rollers

[0070] 5 composite fiber strip

[0071] 9 1 、9 2 、9 3 、9 4 pressure element

[0072] 10 1 、10 2 、10 3 、10 4 displacement sensor

[0073] 28 operating medium circuit

[0074] 28a, 28b, 28c, 28d pipelines

[0075] 29 pressure sensor

[0076] 30 loading device

[0077] 31 control device

[0078] 32 signal device

[0079] I, II, III lower rollers

[0080] A traction direction

[0081] a 4 / III 、a 3 / II 、a 2 / I 、a 1 / I distance

[0082] p pressure

[0083] p 1 operating medium pressure

[0084] p 1-Ist actual operating medium pressure

[0085] p 1-Soll rated operating medium pressure

[0086] t 1 、t 2 、t 3 、t 4 time point

[0087] S drafting mechanism

Claims

1. A method for preventing damage to the drafting mechanism of a spinning preparation machine due to winding formation, wherein, the drafting mechanism (S) has at least two drafting mechanism rollers (1-4, I-III) that can be relatively pressed together, and these drafting mechanism rollers can be relatively pressed together by means of loading devices (9a, 9b, 9c), wherein the loading devices (9a, 9b, 9c) are connected to a working medium circuit (28), and the method includes the following steps: Detecting the actual operating medium pressure (p 1-Ist ) in the operating medium circuit (28) by means of at least one pressure sensor (29); Monitoring of the temporal variation of the actual operating medium pressure (p 1-Ist ) by means of a control device (31) coupled to a pressure sensor (29); When a threshold value preset for the change over time exceeding the actual operating medium pressure (p 1-Ist ) is exceeded, the drafting mechanism is shut down by the control device (31) and / or a signal is triggered by the control device (31).

2. The method according to claim 1, characterized in that, The change in the actual operating medium pressure (p 1-Ist ) is at least 100 mbar.

3. The method according to claim 1 or 2, characterized in that, the temporal change of the preset threshold is at least 100 milliseconds.

4. The method according to claim 2, characterized in that, For each upper roll (1, 2, 3, 4), the actual operating medium pressure (p 1-Ist ) in each pipeline (28a, 28b, 28c, 28d) is determined individually.

5. The method according to any one of the above claims, characterized in that, In the control device (31), the actual operating medium pressure (p 1-Ist ) is compared with the rated operating medium pressure (p 1-Soll ), and when the rated operating medium pressure (p 1-Soll ) is exceeded, it is used as an additional signal for shutting down the drafting mechanism (S) and / or for triggering a signal or an alarm.

6. The method according to any one of the above claims, characterized in that, With the aid of a displacement sensor (10 1 -10 4 ), the distance between the rollers (1 - 4, I - III) of the drafting mechanism is detected, and the control device (31) is configured to distinguish, for each pair of rollers (1 - 4, I - III) of the drafting mechanism, between spinning, thin point generation, bobbin change, and winding formation.

7. A drafting mechanism (S) of a spinning machine, including at least one pair of rollers composed of drafting mechanism rollers (1-4, I-III), and there are gaps between these drafting mechanism rollers. In the normal operation of the drafting mechanism (S), the fibrous material can pass through the gaps in the form of a sliver. The drafting mechanism has a loading device (30), and the loading device relatively presses at least one of the at least two drafting mechanism rollers (1-4, I-III) in order to adjust the pressing pressure, wherein, the loading device (30) is connected to the working medium circuit (28) so as to relatively press at least one of the two drafting mechanism rollers (1-4, I-III). At least one pressure sensor (29) is arranged in the working medium circuit (28), and the pressure sensor is connected to a control device (31) assigned to the drafting mechanism (S). So as to place the drafting mechanism (S) in a stop state or output an acoustic or optical signal to a signal device (32) connected to the control device (31) when winding formation is recognized. Wherein, the control device (31) is designed to execute the method according to any one of claims 1 to 6.

8. The drafting mechanism (S) according to claim 7, characterized in that, the working medium circuit (28) is configured as a pneumatic circuit, wherein the working medium is air or a mixed gas, and the pressure sensor (29) is configured as a compressed air sensor.

9. The drafting mechanism (S) according to claim 8, characterized in that, an air compressor, such as a compressor, is arranged in the pneumatic circuit.

10. The drafting mechanism (S) according to any one of claims 7 to 9, characterized in that, the pressure sensor (29) is arranged in the working medium circuit (28) for all upper rollers (1, 2, 3, 4), or a pressure sensor (29) for monitoring the pressing pressure of each individual upper roller (1, 2, 3, 4) is arranged in each pipeline (28a, 28b, 28c, 28d).

11. The drafting mechanism (S) according to any one of claims 7 to 9, characterized in that, Each pair of drafting mechanism rollers (1-4, I-III) has a sensor for determining the distance between the drafting mechanism rollers (1-4, I-III), wherein these sensors are configured to transmit sensor data to a control device (31).

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