Method for the preventive detection of a standstill in a drafting system of a spinning machine, and drafting system of a spinning machine
Patent Information
- Application Number
- EP2022840747
- Authority / Receiving Office
- EP · EP
- Patent Type
- Applications
- Current Assignee / Owner
- Filing Date
- 2022-12-21
- Publication Date
- 2025-10-29
AI Technical Summary
Existing monitoring devices for detecting coil formations in drafting systems of spinning machines are complex, vulnerable, and only detect wraps after they have formed, leading to disruptive system shutdowns and potential false alarms.
A method using pressure sensors and control devices to monitor changes in operating fluid pressure and distance between rollers, allowing for early detection of coil formations and preventing system shutdowns with a cost-effective and less complex design.
Enables preventive detection of coil formations, reducing system downtime and false alarms by distinguishing between different operating states through pressure and distance changes, ensuring accurate and reliable operation.
Smart Images
Figure 1.1
Abstract
Description
[0001] Title: Method for the preventive detection of a standstill in a drafting system of a spinning machine and drafting system of a spinning machine
[0002] Description
[0003] The invention relates to a method for the preventive detection of a standstill in a drafting system of a spinning machine and to a drafting system of a spinning machine according to the features of the independent claims.
[0004] In the drafting system of a spinning machine, one or more supplied fiber slivers are passed through the gap formed between a pair of drafting rollers (one upper and one lower roller) and drawn into a fiber strand. This fiber strand can then be spun into a yarn.
[0005] During drafting system operation, fiber material can often become wound up—known as lap formation—on the outer circumference of the upper or lower rollers. This occurs when fibers from the fiber slivers wrap around the rollers. If not detected, these accumulations would lead to massive winding and disrupt the operation of the drafting system. In such a case, the drafting system must be shut down and the lap removed. For this reason, appropriate monitoring devices have been developed in the past to detect the presence of laps. For example, there are tactile monitoring devices that detect a lap that has already formed, i.e., already present.
[0006] In such a known tactile monitoring device (EP 1 428 914 A), a piston rod of a pressure cylinder is attached to the two axial ends of the shaft of the top roller. A switching disc is mounted slidably on the piston rod and frictionally coaxial with a piston, which interacts with a switch for detecting the position of the piston. The switching disc is at least partially permanently magnetic in order to interact with an inductive sensor as a switch for detecting the position of the piston. When a lap of fiber material forms around the top roller, the floating top roller is pressed towards the pressure cylinder at one axial end of the shaft of the draw roller. The pressure rod of the pressure cylinder contacting the top roller consequently moves towards the retracted end position.When the pressure rod is retracted, the friction-mounted switching disc activates the switch, and the drafting system is shut down. The drafting system must now be opened manually and the lap removed. The drafting system is then returned to its operating position by closing the loading arm. The design of such a tactile monitoring device for lap detection is comparatively complex and fragile.
[0007] DE 10 2108 125 547 A1 discloses the readjustment of the pressure of the top rollers of such a drafting system when it exceeds or falls below a certain threshold. However, the document does not disclose the use of pressure monitoring to detect the formation or presence of laps, but rather to reduce wear on the drafting system rollers.
[0008] Based on this, the task is therefore to provide a method for the preventive detection of a downtime in a drafting system of a spinning machine, as well as a drafting system of a spinning machine, which are improved over the state of the art. In particular, lap formations on the drafting system rollers of such a drafting system are to be detected at an early stage, while at the same time, a comparatively cost-effective, less complex, and less susceptible design for such a monitoring device is to be provided.
[0009] The object is achieved by a method according to the invention for the preventive detection of a standstill in a drafting system of a spinning machine and such a drafting system according to the independent claims.
[0010] Additionally, the object is also achieved by a drafting system according to the invention for a spinning machine with at least two drafting system rollers that can be pressed against each other by the operating means. This can be a drafting system with any number of upper and lower rollers, for example, a 4-over-3 drafting system, a 2-over-2 drafting system, or other variants of a drafting system. The subject matter described in the dependent claims represents particularly preferred embodiments of the invention.
[0011] The inventive method for the preventive detection of a standstill in a drafting system of a spinning machine due to the formation of a lap between at least two drafting system rollers that can be pressed against each other comprises at least two drafting system rollers that can be pressed against each other by means of a loading device. The loading device is connected to an operating fluid circuit. At least one pressure sensor in the operating fluid circuit detects the actual operating fluid pressure (pi.actual). A control device coupled to the pressure sensor monitors a temporal change in the actual operating fluid pressure (pi-actual). If a predetermined threshold value for the temporal change in the actual operating fluid pressure (pi-actual) is exceeded, the drafting system is switched off by the control device (31) and / or a signal is triggered.
[0012] The invention is based on the finding that during the formation of a lap between two drafting system rollers, the actual operating fluid pressure differs in both magnitude and temporal progression from other operating states to such an extent that lap formation can be distinguished from piecing, the creation of a thin spot, and a can change. In particular, the magnitude and the short temporal progression of the pressure increase provide an indication that the control device can detect lap formation based on the change in the actual operating fluid pressure and thus switch off the drafting system and / or trigger an alarm or signal. The control device can switch off the drafting system if the change in the pressure curve of the actual operating fluid pressure amounts to a pressure increase of at least 100 mbar.
[0013] In contrast to the other operating states, the pressure increase persists for a period of at least 100 milliseconds. A pressure increase over a shorter period may indicate a thick spot in the fiber sliver or the formation of a thin spot before the can change.
[0014] To determine the lap formation locally, between which pair of drafting rollers the lap is currently forming, the actual operating fluid pressure in the lines can be determined separately for each top roller.
[0015] Additionally, the actual operating fluid pressure in the control device can be compared with a target operating fluid pressure. If the target operating fluid pressure is exceeded, this can be used as an additional signal to shut down the drafting system and / or trigger a signal or alarm. This protects the lap formation monitoring process against possible false alarms.
[0016] Additionally, the distance between the drafting system rollers can be detected using position sensors, and the control device can be configured to distinguish between piecing, the creation of a thin point, a can change, and lap formation for each pair of drafting system rollers. Here, too, the magnitude, location, and temporal progression of the distance change are crucial for distinguishing between the individual operating states such as piecing, thin point creation, can change, and lap formation. Determining the distance between the drafting system rollers can be used to determine the location of lap formation when a single pressure sensor is arranged in the operating circuit and / or to re-verify the signal to shut down the draw frame, thus preventing a possible false shutdown.
[0017] The drafting system of a spinning machine according to the invention comprises at least one pair of drafting system rollers, which together form a gap through which fiber material in the form of fiber slivers is passed during normal operation of the drafting system. The drafting system has at least one loading device, which is designed to adjust a contact pressure between at least one of the two drafting system rollers. The loading device is connected to an operating circuit to press at least one of the two drafting system rollers against each other. At least one pressure sensor is arranged in the operating circuit, which is connected to a control device assigned to the drafting system in order to bring the drafting system to a standstill upon detection of the formation of a lap or to output an acoustic or optical signal to a signaling device connected to the control device.The control device is designed to carry out a method according to one of the method claims.
[0018] The operating fluid circuit can be designed as a pneumatic circuit, in which the operating fluid is air or an air mixture, and the pressure sensor is designed as a compressed air sensor. A compressed air generator, such as a compressor, is preferably arranged in the pneumatic circuit.
[0019] The pressure sensor is located in the operating fluid circuit for all top rolls, or a pressure sensor can be located in each line to monitor the contact pressure of each individual top roll. This allows for the local determination of the lap formation.
[0020] Each pair of drafting system rollers can have a sensor for determining the distance between the drafting system rollers, wherein the sensors are configured to transmit the sensor data to the control device. Determining the distance between the drafting system rollers can be used to determine the location of lap formation when a single pressure sensor is arranged in the operating circuit and / or to re-verify the signal for shutting down the draw frame, thus preventing a possible false shutdown. The magnitude, location, and temporal progression of the distance change can be used to differentiate between the individual operating states such as piecing, thin-point generation, can change, and lap formation.
[0021] Further measures improving the invention are described in more detail below together with the description of a preferred embodiment of the invention with reference to the figures.
[0022] It shows:
[0023] Fig. 1 is a schematic side view of a possible embodiment of a 3-over-4 drafting system;
[0024] Fig. 2 is a further schematic side view of an embodiment as a 2-over-2 drafting system;
[0025] Fig. 3 shows a section of a temporal course of an indirectly recorded actual contact pressure on two drafting system rollers of a drafting system set up according to the invention.
[0026] Fig. 1 shows a highly schematic and therefore not to scale side view of a drafting system S according to the invention. The drafting system S can be part of a draw frame. In this embodiment, it is designed as a 4-over-3 drafting system, i.e. it consists of three bottom rollers I, II, III (I output bottom roller, II middle bottom roller, III input bottom roller) and four top rollers 1, 2, 3, 4. Opposing pairs of top rollers 1, 2, 3, 4 and bottom rollers I, II, III form a gap through which fiber slivers fed to the drafting system are passed and drawn to form a fiber strand 5. The drafting of the fiber strand 5, which is made up of the pre-draft and the main draft, takes place in the drafting system S.
[0027] In this case, roller pairs 4 / III and 3 / II form the pre-drafting section, and roller pairs 3 / II and 1 and 2 / I form the main drafting section. The exit bottom roller I is driven by the main motor (not shown) and thus determines the delivery speed. The entry and middle bottom rollers III and II, respectively, are driven by a variable-speed motor (not shown).
[0028] At least one pair of drafting system rollers (e.g. the upper roller 4 and the lower roller III) form a distance a or gap through which the fiber strand 5 can be passed during normal operation of the drafting system, wherein at least one of the drafting system rollers, here the upper roller 4, is movably mounted relative to the other drafting system roller of the roller pair, thus here the lower roller III, in such a way that when laps of fiber material are formed in the gap relative to the lower roller III, the distance a increases. The upper rollers 1-4 are pressed against the lower rollers I, II, III via a loading device 30 and thus receive their drive from the rotating lower rollers I, II, III via frictional engagement. The direction of rotation of the drafting system rollers I, II, III and 1, 2, 3, 4 is indicated by curved arrows.The loading device 30 is assigned a plurality of pressure elements 9i to 94, each of which is fluidly connected to an operating fluid circuit 28 via lines 28a, 28b, 28c, and 28d. The operating fluid circuit 28 carries an operating fluid, such as air or an air mixture, in order to pressurize the pressure elements 9i to 94, which can be designed, for example, as piston-cylinder units, with the operating fluid. Accordingly, in the present case, the operating fluid circuit 28 is designed as a pneumatic circuit in which an operating fluid pressure pi can be adjusted. A compressed air generator, such as a compressor, can be arranged in the pneumatic circuit, and the operating fluid pressure pi can be adjusted via control valves (not shown).
[0029] Furthermore, a pressure sensor 29, which is designed as a compressed air sensor, is arranged in the operating fluid circuit 28. The pressure sensor 29 constantly records the actual operating fluid pressure pi-ist- prevailing in the operating fluid circuit 28. The pressure sensor 29 is connected via a line, indicated here by dashed lines, to a control device 31 assigned to the drafting system S. The control device 31 is designed to compare the actual operating fluid pressure pi-ist with a predetermined target operating fluid pressure pi-soii. The top rollers 1, 2, 3, 4 can each be assigned a displacement sensor 10i - 104, which can be arranged and integrated on one or both sides of the top roller bearing or on the pressure elements 9i - 94. The displacement sensors 10i - 104 are also connected to the control system.
[0030] If the drafting system S is started from a standstill without fiber slivers, a corresponding operating fluid pressure pi is first set in the operating fluid circuit 28 to set a desired contact pressure for at least two of the drafting system rollers 1-4, l-lll. As a result, the pressure elements 9i to 94 of the loading device 30 press the upper rollers 1-4 against the lower rollers l-lll. The fiber strand 5 is guided through the drafting system rollers 1-4, l-lll in the take-off direction A and drawn. This corresponds to the intended operation of the drafting system S. At the same time, the distance a between the upper rollers 1-4 and the lower rollers l-lll is smaller than the desired distance a-soii, which is set for the fiber sliver mass to be drawn, since at this time no fiber sliver is yet running through the drafting system.
[0031] The control device 31 now monitors the actual operating medium pressure pi-ist prevailing in the operating medium circuit 28 via the pressure sensor 29 and thus the pressure changes which the at least two drafting system rollers 1-4, l-lll exert on one another in order to determine the formation of a lap of fiber material from the fiber structure 5 around one of the drafting system rollers 1-4, l-lll.
[0032] Such a winding can be indirectly controlled via the actual operating fluid pressure pi.| S t can be detected, namely when fiber material begins to wind, for example, around the upper roller 4. As a result of the winding, the distance a4 / m between the upper roller 4 and the lower roller III increases, i.e., the upper roller 4 moves away from the lower roller III and exerts a counterforce on the loading device 30, in this case the pressure element 94. The change in distance can be detected via the displacement sensor IO4.
[0033] This counterforce acts against the pressing force of the pressure element 94 due to the operating fluid pressure pi. This counterforce of the top roller 4 against the pressure element 94, in turn, causes a compression of the piston-cylinder unit of the pressure element 94 and thus an increase from the preset target operating fluid pressure pi-soii to the actual operating fluid pressure pi-ist. Due to the formation of the lap, the distance a4 / m between the two drafting system rollers 4, III changes or increases.
[0034] Figure 2 shows a 2-over-2 drafting system according to the invention, designed as a single-zone drafting system with a single drafting zone. Like the drafting system of the embodiment shown in Figure 1, it can be designed as a controlled or uncontrolled drafting system.
[0035] The drafting system S shown here consists of two bottom rollers I, II (I output bottom roller, II input bottom roller) and two top rollers 1, 2. Opposing pairs of top rollers 1, 2 and bottom rollers I, II form a gap through which fiber slivers fed to the drafting system are passed and drawn into a fiber strand 5. Thus, the drafting of the fiber strand 5, which consists of the pre-draft and the main draft, takes place in the drafting system S.
[0036] The output bottom roller I is driven by the main motor (not shown) and thus determines the delivery speed. The input bottom roller II can be driven by a control motor (not shown).
[0037] At least one pair of drafting rollers (e.g. the upper roller 2 and the lower roller II) form a distance a or gap through which the fiber structure 5 can be guided in the take-off direction A during normal operation of the drafting system, wherein at least one of the drafting rollers, here the upper roller 2, is movably mounted relative to the other drafting roller of the pair of rollers, here the lower roller II, in such a way that when laps of fiber material are formed in the gap, it can move away from the lower roller II, increasing the distance a.
[0038] The upper rollers 1-2 are pressed against the lower rollers I, II via a loading device 30 and are thus driven by the rotating lower rollers I, II via frictional engagement. The loading device 30 is assigned a plurality of pressure elements 9i to 92, which are each connected to an operating medium circuit 28 via lines 28a, 28b. The operating medium circuit 28 carries an operating medium, such as air or an air mixture, in order to pressurize the pressure elements 9i to 92, which can be designed as piston-cylinder units, for example. Accordingly, the operating medium circuit 28 is designed as a pneumatic circuit in which an operating medium pressure pi can be adjusted. A compressed air generator, such as a compressor, can be arranged in the pneumatic circuit, and the operating medium pressure pi can be adjusted using control valves (not shown).
[0039] A pressure sensor 29, designed as a compressed air sensor, is also arranged in the operating fluid circuit 28. The pressure sensor 29 continuously detects the actual operating fluid pressure pi prevailing in the operating fluid circuit 28. S t. The pressure sensor 29 is connected via a line, indicated here by dashed lines, to a control device 31 assigned to the drafting system S. The control device 31 is designed to compare the actual operating fluid pressure pi-actual with a predetermined target operating fluid pressure pi-soii. A displacement sensor 10i - 102 can be assigned to each of the top rollers 1, 2, which can be arranged and integrated on one or both sides of the top roller bearing or on the pressure elements 9i - 92. The displacement sensors 10i - 102 are also connected to the control system.
[0040] If the drafting system S is started from a standstill without any slivers, a corresponding operating fluid pressure pi is first set in the operating fluid circuit 28 in order to set a desired contact pressure for at least two of the drafting system rollers 1-2, l-ll. As a result, the pressure elements 9i to 92 of the loading device 30 press the upper rollers 1-2 against the lower rollers l-ll. The fiber strand 5 is guided between the drafting system rollers 1-2, l-ll and drawn. This corresponds to the intended operation of the drafting system S. At the same time, the distance a between the upper rollers 1-2 and the lower rollers l-ll is smaller than the desired distance a-soii, which is set for the fiber sliver mass to be drawn, since at this time no fiber sliver is yet running through the drafting system. The control device 31 now monitors the actual operating fluid pressure pi prevailing in the operating fluid circuit 28 via the pressure sensor 29.| St and thus the pressure changes which the at least two drafting rollers 1-2, l-ll exert on each other in order to determine the formation of a lap of fibre material from the fibre structure 5 around one of the drafting rollers 1-2, l-ll.
[0041] Such a winding can be indirectly controlled via the actual operating fluid pressure pi.| S t can be detected, namely when fiber material begins to wind, for example, around the top roller 2. As a result of the winding, the distance a2 / n between the top roller 2 and the bottom roller II increases, i.e., the top roller 2 moves away from the bottom roller II and exerts a counterforce on the loading device 30, in this case the pressure element 92. The change in distance can be detected via the displacement sensor IO2.
[0042] This counterforce acts against the pressing force of the pressure element 92 due to the operating fluid pressure pi. This counterforce of the top roller 2 against the pressure element 92, in turn, causes a compression of the piston-cylinder unit of the pressure element 92 and thus an increase from the preset target operating fluid pressure pi-soii to the actual operating fluid pressure pi-ist. Due to the formation of the lap, the distance a2 / n between the two drafting rollers 2, II changes or increases.
[0043] In Fig. 3, three diagrams are shown one above the other and refer to the embodiment shown in Fig. 2. Naturally, the diagram also applies to the embodiment shown in Fig. 1, whereby instead of the input drafting rollers 2 / II, the input drafting rollers 4 / III are used with a spacing a4 / m. The output drafting rollers 1 / 1 have the same designation.
[0044] The diagram below shows a section of a possible pressure-time diagram, which shows the time course of a pressure determined by the actual operating medium pressure pi-i s t indirectly detected contact pressure on the two input drafting system rollers 2 and 11 pressed against each other of a drafting system S configured according to the invention. The dashed line shows the target operating fluid pressure pi-s0n, from which the actual operating fluid pressure pi-ist deviates over time. The actual operating fluid pressure pi-ist is detected by means of the pressure sensor 29.
[0045] The middle diagram shows the distance ai / i of the output roller pair 1 / 1 over the same time course. The upper diagram shows the distance a2 / n of the input roller pair 2 / II over the same time course.
[0046] The time course of all three diagrams is the same.
[0047] Before the start of piecing, i.e. before the time to, all drafting system rollers are moved apart so that the distance a2 / n of the input roller pair 2 / 11 shown in the diagram and the distance ai / i of the output roller pair 1 / 1 are above a target distance.
[0048] At time t0, the drafting system S is transferred from standstill to its intended operation, ie, a fiber strand 5 is placed between the drafting system rollers 1-2, 1-11, the pressure elements 91-92 are subjected to the operating fluids, the drafting system rollers 1-2, 1-11 are moved toward each other, pressed against each other, and rotate. The initial pressure = actual operating fluid pressure pi.| S t is above the target operating pressure pi-soii and settles below the target operating pressure pi-soii.
[0049] At time ti, after the drafting system S has started up and is thus in normal operation, the fiber strand 5 is drawn as desired. For this purpose, a corresponding actual operating fluid pressure pi is established.| S t of the drafting system rollers 1-2, l-ll, which briefly exceeds the target operating pressure pi-soii, but then continuously drops below the target operating pressure pi-soii. The distance ai / i and a2 / n decreases with piecing and settles at a uniform level between times h to t2 without significant change.
[0050] At time t2, a can change is performed, which leads to a pressure change and is attributable to a thin spot in the fiber strand 5 caused by the change. At the output roller pair 1 / 1, the distance ai / i is briefly reduced, while the distance a2 / n of the input roller pair 2 / II remains almost constant without any sudden change and only drops very slightly in level. The actual operating fluid pressure pi.| S t of the drafting rollers 1-2, I- II is constantly below the target operating pressure pi-soii-
[0051] At time ta, a can change is initiated after a thin spot was created in the fiber structure 5 at time t2. The drafting system S can be operated at a slightly reduced processing speed, which is noticeable at the input roller pair 2 / II by a brief build-up of the fiber material, causing the distance a2 / n to first increase abruptly and then decrease. The actual operating fluid pressure pi-actual also increases abruptly by a small amount, but is still below the target operating fluid pressure pi-soii-. At the same time, the distance ai / i of the output roller pair 1 / 1 decreases slightly.
[0052] At time t4, a lap is now formed between the drafting system rollers 2 / 11. The instantaneous actual operating fluid pressure pi-ist, detected by the pressure sensor 29, increases abruptly and rises above the target operating fluid pressure pi-soii for a short time interval of at least 100 ms, before also dropping abruptly again. The control device 31 detects the sudden pressure increase due to the slope of the curve and switches off at least the drafting system S. The control system is designed to switch off the drafting system if the actual operating fluid pressure pi-ist changes by at least 100 mbar over a period of at least 100 ms.
[0053] In addition to the sudden increase in the actual operating pressure pi.| S t the control is designed to switch off the drafting system S if the target operating pressure pi-s0n is exceeded. Both limit values can be combined with each other, whereby the change in the actual operating pressure pi.|S t alone is sufficient to detect the wrap.
[0054] Shortly before the sudden increase in the actual operating pressure pi.| S At time t, the distance a2 / n of the input roller pair 2 / II increases abruptly to a level that exists before time t, i.e., before piecing. This occurs because, for example, the upper roller 2, around which the fiber material of the fiber strand 5 is wound, is now pushed away from the lower roller II as a result of the material accumulation. As a result, the distance a2 / n of the input roller pair 2 / II changes abruptly, while at the same time the distance ai / i of the output roller pair 1 / 1 decreases abruptly, since less fiber sliver passes through the drafting system S due to the formation of the lap.
[0055] In order to continuously monitor a possible winding formation, the control device 31 now detects a change in the actual operating fluid pressure pi.| St of at least two drafting rollers 1-2, l-ll, or a temporal change thereof, so that the pressure change can be determined. For this purpose, the control device 31 detects the current actual operating fluid pressure pi-ist using the pressure sensor 29.
[0056] In addition, the actual operating pressure pi-actual is compared with a specified target operating pressure pi-soii. The target operating pressure pi-soii can be specified as a fixed value here, see the dashed line. During the comparison, the control device 31 calculates a difference between the specified target operating pressure pi-soii and the actual operating pressure pi-i. s t. If the actual operating fluid pressure pi-actual now exceeds the desired operating fluid pressure pi-soii, the control device 31 can conclude the presence of a coil in addition to the change in the pressure curve of the actual operating fluid pressure pi-actual.
[0057] In all embodiments of the drafting system according to Figures 1 and 2, the change in the pressure curve of the actual operating fluid pressure pi is monitored.| S t alone is sufficient to detect the formation of a coil. In addition, exceeding the actual operating pressure pi.| S t protect the system against false shutdowns via the target operating fluid pressure pi-soii. Both can be achieved simultaneously in the operating fluid circuit 28 by means of a pressure sensor 29 for all top rollers 1, 2, 3, 4. Alternatively, a separate pressure sensor can be arranged in each line 28a, 28b, 28c, 28d, which then monitors the lap formation for each individual top roller 1, 2, 3, 4.
[0058] A further addition to both winding formation monitoring variants can be achieved through the measurement results of the position sensors 10i - 104, since the distance between the respective top roller and the bottom roller changes with the winding process. This does not always necessarily have to occur at the input rollers 4 / III.
[0059] The change in the pressure curve of the actual operating fluid pressure pi-actual is sufficient for the control system to detect coil formation. If the pressure sensor 29 is located only in the operating fluid circuit 28, the measurement results of the position sensors 10i - 104 can not only prevent a malfunction, but also allow the control system to detect the location of the coil formation. For this purpose, the signal indicating that the actual operating fluid pressure pi-actual exceeds the target operating fluid pressure pi-s0n does not need to be used to safeguard against a malfunction. However, it can serve to make the process more reliable.
[0060] If a pressure sensor 29 is arranged separately in each line 28a, 28b, 28c, 28d, the measurement result of the displacement sensors 10i - 10I4 can not only prevent a malfunction, but the location of the coil formation can also be detected by the control system both through the change in the pressure curve of the actual operating fluid pressure pi-actual and through the signal from the displacement sensors 10i - 10I4. For this purpose, the signal indicating that the actual operating fluid pressure pi-actual exceeds the target operating fluid pressure pi-s0n does not need to be used to safeguard against a malfunction. However, it can serve to make the process more reliable.
[0061] The control device 31 is, as shown in Figs. 1 and 2, connected to a signaling device 32 via a line (dashed lines) to output an acoustic or optical signal to the signaling device 32 upon detection of the formation of a lap. Alternatively, it can then automatically stop the drafting system S. By means of the invention, lap formations on the drafting system rollers of such a drafting system can thus be detected early on without the need for a complex and vulnerable structure for triggering the monitoring device.
[0062] Furthermore, the invention can also be used to determine whether the change in contact pressure is a windage, i.e., a damaging pressure change, or a harmless change in contact pressure. Such a harmless change in contact pressure can be caused, for example, by a can change or automatic piecing. During automatic piecing, the top rollers are already loaded by the loading device or pressure elements.
[0063] In the embodiment of Figure 1, the pressure sensor 29 is integrated into the line 28, so that one pressure sensor 29 simultaneously detects the winding formation on all four top rollers 1, 2, 3, 4. In this embodiment, the evaluation of the position sensors 10i - 104 is necessary to determine the location of the winding formation.
[0064] The arrangement of a separate pressure sensor 29 in each line 28a, 28b, 28c, 28d for each top roll 1, 2, 3, 4 enables the detection of a lap formation and the location of the lap, i.e., on which roll pair the lap is formed. Naturally, each sensor is then separately connected to the control device 31. For this purpose, the evaluation or availability of displacement sensors is not necessary, but can prevent malfunctions. Monitoring the level of the actual operating fluid pressure pi-i s t above the target operating fluid pressure p-son is also not necessary for the control device 31 to detect lap formation, but can be used additionally to prevent malfunctions. The control device 31 can compare the values using the signals from each pressure sensor and is thus designed to distinguish between piecing, lap, and can change.
[0065] Reference symbol
[0066] 1, 2, 3, 4 top rollers
[0067] 5 fiber association
[0068] 9l ,02, 93, 04 printing elements
[0069] 10i, 102, 103, 104Displacement sensor
[0070] 28 Equipment circuit
[0071] 28a, 28b, 28c, 28d line
[0072] 29 Pressure sensor
[0073] 30 loading device
[0074] 31 Control device
[0075] 32 Signaling device
[0076] I, II, III bottom rollers
[0077] Pull-off direction a4 / m, a3 / n, a2 / i, ai / i distance
[0078] P pressure
[0079] Pi operating fluid pressure pi-lst actual operating fluid pressure
[0080] Pi-setpoint Target operating pressure t1, t2, t3, t4 Time
[0081] S drafting system
Claims
AMENDED CLAIMS received by the International Bureau on 15 August 2023 (15.08.2023) 1. A method for preventing damage to a drafting system of a spinning preparation machine as a result of lap formation, wherein the drafting system (S) has at least two drafting system rollers (1-4, l-lll) which can be pressed against one another and which can be pressed against one another by means of a loading device (9a, 9b, 9c), wherein the loading device (9a, 9b, 9c) is connected to an operating medium circuit (28), and the method comprises the following steps: Detecting an actual operating fluid pressure (pi-ist) in the operating fluid circuit (28) by at least one pressure sensor (29); Monitoring a temporal change in the actual operating fluid pressure (pi-ist) by a control device (31) coupled to the pressure sensor (29); when a predetermined threshold value for the temporal change in the actual operating fluid pressure (pi-i st) by at least 100 milliseconds, switching off the drafting system by the control device (31) and / or triggering a signal by the control device (31).
2. Method according to claim 1, characterized in that the change in the actual operating fluid pressure (pi-ist) is at least 100 mbar.
3. Method according to claim 2, characterized in that the actual operating fluid pressure (pi-ist) in the lines (28a, 28b, 28c, 28d) is determined separately for each top roller (1, 2, 3, 4).
4. Method according to one of the preceding claims, characterized in that the actual operating fluid pressure (pi-actual) in the control device (31) is compared with a desired operating fluid pressure (p-1-soii), and when the desired operating fluid pressure (pi-soii) is exceeded, is used as an additional signal for switching off the drafting system (S) and / or for triggering a signal or an alarm.
5. Method according to one of the preceding claims, characterized in that the distance between the drafting rollers (1-4, l-lll) is detected by means of displacement sensors (10i - 104), and the control device (31) is designed to distinguish for each pair of drafting rollers (1-4, l-lll) between piecing, the creation of a thin point, a can change and lap formation. 18 AMENDED SHEET (ARTICLE 19) 6. Drafting system (S) of a spinning machine, comprising at least one pair of drafting system rollers (1-4, l-lll) which together form a gap through which, during normal operation of the drafting system (S), fiber material in the form of fiber slivers can be passed, with a loading device (30) which presses at least one of the two drafting system rollers (1-4, l-lll) against each other to set a contact pressure, wherein the loading device (30) is connected to an operating means circuit (28) in order to press at least one of the two drafting system rollers (1-4, l-lll) against each other, in the operating means circuit (28) at least one pressure sensor (29) is arranged which is connected to a control device (31) assigned to the drafting system (S) in order to bring the drafting system (S) to a standstill upon detection of the formation of a lap or to transmit an acoustic or optical signal to a control device connected to the control device (31) connected signaling device (32),wherein the control device (30) is arranged to carry out a method according to one of claims 1 to 5., 7. Drafting system (S) according to claim 6, characterized in that the operating medium circuit (28) is designed as a pneumatic circuit in which the operating medium is air or an air mixture and the pressure sensor (29) is designed as a compressed air sensor.
8. Drafting system (S) according to claim 7, characterized in that a compressed air generator, such as a compressor, is arranged in the pneumatic circuit.
9. Drafting system (S) according to one of claims 6 to 8, characterized in that the pressure sensor (29) is arranged in the operating medium circuit (28) for all top rollers (1, 2, 3, 4), or that a pressure sensor (29) for monitoring the contact pressure of each separate top roller (1, 2, 3, 4) is arranged in each line (28a, 28b, 28c, 28d).
10. Drafting system (S) according to one of claims 6 to 8, characterized in that each pair of drafting system rollers (1-4, l-lll) has a sensor for determining the distance between the drafting system rollers (1-4, l-lll), wherein the sensors are designed to transmit the sensor data to the control device (31). 19 AMENDED SHEET (ARTICLE 19)