EP0679599A2 - Monitoring device for sliver - Google Patents

Abstract

The sliver supply (2a-2d) to a textile machine (1) is monitored by a sensor (3a-3d) in each transport path (R). Each sensor (3a-3d) gives a signal created by an element which responds to the forward movement (R) of the sliver (2). <IMAGE>

Description

The invention relates to a method and a device for monitoring the supply of fiber slivers to a textile processing machine, wherein a sensor unit for monitoring is arranged in the transport path of each fiber sliver.

When feeding a certain number of slivers to a textile processing machine via an infeed frame, it is necessary to monitor the feed of the individual slivers. Lines, flyers, winding-forming machines or other machines, which are loaded with fiber tapes, can be connected downstream of the infeed frame as textile processing machines. To avoid mass inequalities and technological disadvantages in the end product, which is formed in the textile processing machine, it is necessary to stop the machine and thus the sliver feed in the event of a sliver failure and to replace the missing sliver or to remedy any sliver breakage that may have occurred.

Various monitoring and parking systems are known from practice, which react to such a sliver break or sliver failure and trigger the machine to be shut down. For example, a device is known in which fiber slivers are drawn off from a correspondingly assigned can and are fed to the textile processing machine by means of take-off rollers mounted and driven on a feed frame. A swivel-mounted pressure roller lies on the take-off rollers and comes into contact with the take-off roller in the event of a sliver failure. This closes an electrical circuit, which triggers the shutdown of the textile processing machine becomes. A disadvantage of this device is that a fiber sliver break between the nip point of the draw-off roller and the pressure roller and the textile processing machine is not detected by this monitoring device. In addition, this monitoring system cannot indicate that the sliver transport has stopped.

From EP-A1-38 449 a storage device for feeding fiber slivers is known, the storage being carried out by the position of a rocker assigned to the fiber sliver. With this device, it is possible to detect a sliver break between the take-off roller and the textile processing machine, but this system is very complex and prone to contamination. In addition, a drive is required for each individual take-off roller, which is in front of the rocker.

From DE-A1-37 25 904 a tape guide with an integrated monitoring device is known. This tape guide recognizes whether there is a tape between the guide surfaces, but cannot detect a standstill of the tape transport in the event of a tape break after the tape guide.

The invention is therefore based on the object, based on the known prior art, of proposing a monitoring device which, on the one hand, enables simple design of a feed unit and ensures reliable monitoring of the feed of the slivers.

This object is achieved by the method according to claim 1 in that a signal output from the respective sensor unit is triggered by the transport movement of the fiber sliver.

In order to compensate for tolerances of the individual sensor units as well as different effects of the conveying conditions of the slivers on the sensor unit, it is proposed to transmit the signals to several sensor units of one evaluation unit and to detect sensor units outside the permissible tolerance by means of suitable computing algorithms.

In order to limit the inputs to a central control unit of a textile processing machine to a minimum, it is further proposed that the evaluation unit only output a signal to a control unit for controlling the textile processing machine based on the received and evaluated signals from the sensor units.

To take into account the operating conditions (e.g. starting up and shutting down the textile processing machine), it is proposed that the signal acquisition be controlled on the basis of the operating states of the textile processing machine.

To achieve the object, a device for carrying out the method according to claim 1 is further proposed, the sensor unit being designed as an element which detects the transport movement of the fiber sliver. This makes it possible to drag the slivers to the textile processing machine. This means that the feed unit for the fiber slivers does not require any driven feed or take-off rollers, since the fiber slivers are transported in the area of the feed unit by driven feed elements of the textile processing machine.

The element of the sensor unit is advantageously formed from a deflection roller guiding the fiber sliver, which is caused by the frictional connection between the fiber sliver and the roller the resulting rotational movement of the roller is scanned by a sensor assigned to the roller. The sliver is preferably on a wrap angle of about 90 ° on the roll.

In order to keep the sensor unit functional and to protect it from dirt, it is proposed that the sensor be encapsulated within the outer dimension of the roll.

In the case of a large number of sliver feeds in particular, for reasons of clarity, it is proposed to assign a group of sensor units to an evaluation unit, each of which is connected to the control unit of the textile processing machine.

This enables the entire monitoring system to be designed simply and clearly.

In order to take into account the different operating conditions (e.g. starting, running, stopping), it is proposed to equip the evaluation unit with a sensitivity control. When starting up until an operating speed is reached, there are sometimes very different conditions in the area of the sensor unit. When starting up, for example, the individual slivers are stretched lengthways during the pulling-in process. Since, as a rule, the fiber slivers are tensioned differently before the starting process, the sensor units are acted upon differently in this starting process in accordance with the different tension. These differences can be taken into account by the sensitivity control.

It is also possible to set certain start-up and stop periods by interposing a timer Suppress evaluation unit and control unit from the transmission to the central control unit.

For better localization of the band failure that has occurred and reported by the sensor unit, it is proposed that the respective evaluation unit be provided with an optical display for each sensor unit. It is also possible to equip each sensor unit directly with an optical display.

So that when a sliver runs out of the roll due to the flywheel mass of the roll 8, no further rotary movements of the roll can take place without being acted upon by the sliver, a braking element can be provided which counteracts the free rotary movement.

Further advantages of the invention are shown and described in more detail with reference to the following exemplary embodiments.

Fig. 1

eine schematische Seitenansicht eines Einlaufgestelles mit einer erfindungsgemässen Überwachungseinrichtung,

Fig. 2

eine Draufsicht nach Figur 1,

Fig. 3

ein Diagramm zur Impulsdarstellung,

Fig. 4

eine schematische Draufsicht eines Ausführungsbeispiels nach Fig. 1,

Fig. 5

eine vergrösserte Seitenansicht einer Sensoreinheit nach Fig. 1,

Fig. 6

ein Diagramm zur Darstellung der Maschinendrehzahl,

Fig. 7

ein Diagramm zur Darstellung der Impulsverhältnisse.

Show it:

Fig. 1

2 shows a schematic side view of an inlet frame with a monitoring device according to the invention,

Fig. 2

2 shows a top view according to FIG. 1,

Fig. 3

a diagram for pulse representation,

Fig. 4

2 shows a schematic top view of an exemplary embodiment according to FIG. 1,

Fig. 5

2 shows an enlarged side view of a sensor unit according to FIG. 1,

Fig. 6

a diagram showing the machine speed,

Fig. 7

a diagram to illustrate the pulse ratios.

FIG. 1 shows a textile processing machine 1, which in the example shown is a draw frame. However, the machine 1 could also be a machine for winding formation. The type of machine 1 for the further processing of the slivers 2a to 2d is not essential. It is only necessary that the textile machine 1 is provided with a driven drawing-in element 7 which is driven by a drive 13 and is provided for drawing in the fiber slivers.

The textile machine 1 is preceded by an inlet frame 6 with a frame 12. Rollers 8a to 8d are rotatably mounted on the frame 12. Below each roll 8a to 8d, a can K is placed in the infeed frame, from which the slivers 2a to 2d are drawn off via the rolls 8a to 8d and fed to the textile machine 1 via the feed element 7.

As can be seen in particular from FIG. 2, the slivers 8a to 8c are guided on their transport path to the textile machine 1 on further guide rollers 15 which are rotatably mounted on the frame 12. Instead of the guide rollers 15, other e.g. fixed guide elements can be provided for further guidance of the slivers.

Sensors 9a to 9d are assigned to the rollers 8a to 8d. The combination, for example, of a roller 8a with a sensor 9a is referred to in the example shown as sensor unit 3a.

Such a sensor unit 3 is shown on an enlarged scale in FIG. 5, the attachment of a sensor 9 with respect to the roller 8 being shown schematically. The sensor 9 is attached to the frame-fixed part in the area of the roller bearing (not shown) and detects it Rotary movement of the roller 8. As a rule, the sensor 9 emits a pulse signal S to the evaluation unit A when the roller 8 has completely rotated once. However, two or more pulses per revolution can also be tapped. This depends on the design of the sensor unit or the desired sensitivity. The rotational movement of the roll 8 is generated by the withdrawal of the sliver 2 in the transport direction R. Due to the friction between the roll 8 and the sliver 2, the roll 8 is dragged along when the sliver 2 is drawn off and set in rotation.

Depending on the application and the take-off speed of the sliver 2, the sensor unit 3 can be designed such that a pulse is emitted even with less than one revolution of the roll 8. Commercially available sensors can be used as sensors 9, which are able to detect a rotary movement and to transmit the detected rotary movement to an evaluation unit A by emitting pulses. The pulses emitted by the individual sensors 9a to 9d are transmitted to an evaluation unit A via lines. As can be seen from FIG. 2, the evaluation unit A is provided with optical displays 11 for each sensor unit 3a to 3d. In addition, the evaluation unit A has an input part 17, via which corresponding specifications for the evaluation can be entered manually. The evaluation unit A is connected to a central control unit 4 via a line 18.

The central control unit 4 serves to control the drive of the textile machine 1. As can be seen from FIG. 2, a control element Z can be inserted in the line 18 between the evaluation unit A and the control unit 4, with which control element Z influences the signals to be transmitted the line 18 can be exercised. The functioning of the control element Z will be discussed later.

FIG. 4 shows a further exemplary embodiment, in each case a group of 4 sensor units 3a to 3d and 3a to 3d being combined to form a group, which transmit the pulse signals to an evaluation unit A1 or A2 assigned to the respective group.

The signal generated by the evaluation unit A1 or A2 is transmitted to the central control unit 4 via the line 18 or 18 '.

The monitoring device works as follows:
As soon as the textile machine 1 and thus also the feed element 7 is started, the slivers 2a to 2d are drawn off from the cans K via the rollers 3a to 3d and fed to the textile machine 1.

The starting process of the textile machine is shown, for example, in the diagram of FIG. 6, the textile machine 1 being ramped up to the operating speed n _B in the time t _A up to the time T _A. This speed n _B is maintained until the machine is stopped or shut down over time t _S at time T _S. The speed n _B could also be variable.

As soon as the fiber slivers are pulled off, the roller 8 is rotated due to the friction between the rollers 8 and the fiber slivers 2. This rotary movement is converted into pulses by the sensors 9, which are transmitted to the evaluation unit A as a pulse signal S.

If exactly the same conditions were present on all the rollers 8a to 8d, the sensors 9a to 9d would transmit exactly the same number of pulses per unit of time to the evaluation unit A. In practice, however, these are ideal Ratios per sensor unit 3a to 3d not available. On the one hand, this is due to different frictional relationships between the roll 8 and the sliver 2, different friction in the roll bearing, different tensions in the sliver, and also different tolerances between the sensors 9. The result of this is that the transmission of a pulse between the individual sensor units 3a to 3d will generally never take place at the same time. The pulse output moves within a pulse bandwidth I _T , which is shown for example in FIG. 3. At the time t 1, the number of pulse signals S 2 to S 4 emitted move within the bandwidth I _T1 . The evaluation unit A is now specified (by software) that between the pulse signal S2, which has delivered the most pulses per unit time and the signal S4, which in the example shown at the time t 1 has delivered the fewest pulses per unit time. A difference of, for example, a maximum of 20% may be present. As can be seen from Fig. 3, these requirements are met at time t 1. The signal S4 lies within the tolerance limit I _T1 . This means that the evaluation unit A does not emit a stop signal to the central control unit 4 via the line 18.

Since the signal S with the highest number of pulses is not an absolute value and can also fluctuate, the evaluation unit A is set so that the signal is always used as the output value for determining the tolerance limit I _T , which delivers the most pulses per unit of time. As a result, this monitoring system is very variable and can be used for different operating states.

At time t₆, signal S1 delivers the most pulses per unit of time. The signal S3 is below the tolerance limit I _T6 , whereby a stop signal from the Evaluation unit A is transmitted to the central control unit 4 via the line 18. As a result, the textile machine 1 and thus the feed element 7 are stopped via the central control unit 4. The supply of the slivers is now interrupted.

The reason for the low transmission of pulses per unit of time by the signal S3 can result either from the sliver 2c running out or from its breakage or from excessive contamination. The entrainment of the roll 8c by the sliver 2c is thereby interrupted, as a result of which the sensor 9c no longer emits pulses to the evaluation unit A. This means that as soon as one of the signal values is outside the tolerance range I _T , the evaluation unit A transmits a stop signal to the central control unit 4. These calculation rules are predefined for the control unit.

The differences in the emitted pulses per unit of time between the individual sensor units 3a to 3d can be greater than during the operating time t _B , in particular in the start-up phase t _A and the stop phase t _S.

In order to take this into account, the tolerance range I _T between the sensor unit with the most emitted pulses per unit of time and the sensor unit with the fewest emitted pulses per unit of time is increased in these start-up or stop periods, as is shown, for example, in FIG. 7. From Fig. 7 it can be seen that from the start time T _o to the time T 1, a pulse ratio between the sensor unit with the most pulses and with the fewest pulses is from 4 to 1 in the permissible tolerance range (dashed area) without a stop signal the central control unit 4 is delivered. From Time T 1 to time T _A , a pulse ratio of 2 to 1 is allowed. From this point in time T _A , the textile machine 1 is at the operating speed I _B and the permissible tolerance range I _T is 20%.

The permissible pulse ratio can also be changed linearly, as was shown, for example, by the stop time t _S. The time t _A or t _S can be specified manually for the evaluation unit A via the input 17 or can be set by the central control unit 4 on the basis of the speed.

As indicated by dash-dotted lines in FIG. 2, the range t _A and t _S can be filtered out via a control element controlled by the central control unit 4. This means that the stop signals emitted in this area on the line 18 due to the different pulse ratios are filtered out by the control element Z during this time and do not reach the control circuit of the central control unit 4. However, in this embodiment it must be accepted that a missing one Band is not recognized during these times.

For visual monitoring of the individual sensor units 3, on the one hand, each sensor unit 3 can be provided directly with an optical display 10. This means that as soon as the sensor unit 3 no longer sends pulses, the display 10 lights up.

However, it is clearer to arrange the display 11 for each sensor unit directly at the evaluation unit A. In this way, the sensor unit can be determined from a central point, which delivers no or too few pulses.

The proposed monitoring device makes it possible to design a simple infeed frame 6 without driven take-off rollers, only one monitoring point being required per sliver. Tolerances and different operating conditions between the individual monitoring units can be easily compensated.

The attachment of such a monitoring device to infeed racks is particularly effective, with 36 or more cans K being presented to the textile machine 1.

The division into two evaluation units A1 and A2 shown in FIG. 4 makes it possible to remove certain areas of the can template from the monitoring system in which no fiber sliver is currently being drawn off. This means that the machine can be easily converted to different jug templates without the monitoring device having to be laboriously adapted.

So that when a sliver 2 runs out of the roll 8, due to the flywheel mass of the roll 8, no further rotational movements of the roll can take place without being acted upon by the sliver, a braking element (not shown in more detail) can be provided which counteracts the free rotary movement.

If this braking element is permanently in engagement with the roller, the braking force should only be selected so large that the rotational movement transmitted by the sliver 2 to the roller 8 is not prevented. This means that the braking effect only occurs in this case when the roll 8 is no longer carried along by the sliver 2.

It is also conceivable that a braking element is only connected to the roll 8 when the sliver end leaves the roll. With such a device, an additional trigger mechanism is necessary, which detects the sliver running out and delivers the braking element to the roll.

Claims (13)

Method for monitoring the supply of fiber slivers (2a-2d) to a textile processing machine (1), a sensor unit (3a-3d) for monitoring being arranged in the transport path (R) of each fiber sliver,
characterized,
that a signal output (S1-S4) of the respective sensor unit (3a-3d) is triggered by the transport movement (R) of the sliver (2). Method according to Claim 1, characterized in that the signals (S) from a plurality of sensor units (3a-3d) are transmitted to an evaluation unit (A) and, by means of suitable computing algorithms, sensor units are recognized outside the permissible tolerance. Method according to Claim 2, characterized in that the evaluation unit (A) uses the received and evaluated signals (S1-S4) from the sensor units (3a-3d) to send a signal (S5) to a control unit (4) for controlling the textile-processing machine (1 ) issues. Method according to one of claims 1 to 3, characterized in that the signal detection is controlled on the basis of operating states of the textile processing machine (1). Device for monitoring the feed of fiber slivers (2a-2d) to a textile processing machine (1) according to the method of claim 1, characterized in that the sensor unit (3) as an element (()) detecting the transport movement (R) of the fiber sliver (2) 3) is formed. Apparatus according to claim 5, characterized in that the element is formed from a deflection roller (8) guiding the fiber sliver and the rotary movement of the roller (8) resulting from the frictional connection between the fiber sliver (2) and the roller is carried out by a sensor (9) assigned to the roller is scanned. Apparatus according to claim 5, characterized in that the sliver (2) rests on the roll (8) at approximately a wrap angle of 90 °. Apparatus according to claim 5, characterized in that the sensor (9) is attached encapsulated within the outer dimensions of the roller (8). Device according to one of claims 5 to 8, characterized in that an evaluation unit (A1, A2) is assigned to a group (G1, G2) of sensor units (3a-3d; 3a'-3d '), which with the control unit (4) the textile processing machine (1) is connected. Apparatus according to claim 9, characterized in that the evaluation unit (A, A1, A2) is equipped with a sensitivity control. Apparatus according to claim 9, characterized in that the evaluation unit (a) is connected to the central control unit (4) via a control element (Z). Device according to one of claims 9 to 11, characterized in that the evaluation unit (A) or the sensor unit is provided with an optical display (11) for each sensor unit. Apparatus according to claim 6, characterized in that the roller (8) is assigned a braking element or can be activated.

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