EP0380923B1 - Textile machine, in particular a spinning machine - Google Patents

Description

The invention relates to a textile machine, in particular a spinning machine, with at least one drafting system comprising a plurality of strands, such as, in particular, roller pairs, cylinders / roller pairs or the like, for forming at least one draft zone located between two respective strands, which can be driven at different, in particular adjustable, speeds to produce the draft are, with at least two strands of the drafting device each being assigned a pulse generator and the output signals of the pulse generator depending on the cylinder speed in question have different pulse repetition frequencies in operation, and in which an electronic counter provides a trigger signal for an alarm, a machine downtime or the like.

With ring spinning machines, for example, efforts have recently been made to decentralize the previously common central, common drive system for a wide variety of drive elements. This applies in particular to the drafting system drive. A single tracker drive in particular makes change wheels unnecessary, allows simple and quick operation and creates the possibilities for remote control and fine adjustment.

It is now not only essential that the drafting system strands consisting of roller pairs or cylinder / roller pairs or the like run smoothly, moreover, the speed ratios between the strands are particularly important for yarn counting is vital. In particular, the strands must also start "gearwheel-precisely", that is, in a predetermined ratio, the angle of rotation from standstill and be stopped again when starting. Even during normal operation of the spinning machine in question, it is imperative to maintain the speed ratios mentioned in order to maintain a consistently high yarn quality.

Due to the separate drive of at least some of the drafting system strands, certain speed deviations cannot be excluded without further ado. Because of the extensive automation, there is only the risk that it will not occur at all, especially in the case of minor warping errors, i.e. discovered only in the laboratory or too late and the yarn quality is impaired in large parts of the material produced.

From JP 62-170538 a device of the type mentioned at the outset for detecting the rotational speed of individual drafting rollers is known, in which a signal for stopping a spinning machine to be operated is emitted when a drafting ratio between individual rollers deviates from a predetermined desired value. Rotation sensors are arranged on the shaft ends of the drafting rollers, which detect the rotational speed of the respective roller. The delay ratio calculated from this is compared with the predetermined one, and a signal for stopping an engine is emitted if a significant difference occurs between the measured and the predetermined ratio.

The disadvantage here, however, is that the sensors are connected directly to the shafts, whereby on the one hand the shaft can be influenced by an interaction between the sensor and the shaft and on the other hand the associated sensor must also be replaced when the shaft is exchanged. In addition, must the calculated ratio can only be compared with a predetermined target ratio before a possible shutdown signal can be emitted, which means an additional circuit effort.

From CH 459 334 a circuit arrangement for electronically regulating the speed of a drive device to a setpoint is known, in which a counting circuit contains two inputs, pulses derived from the setpoint being present at the first input and pulses derived from the current speed being present at the second input. Depending on whether the setpoint is greater than the actual value or vice versa, the counter circuit can only count up to a minimum value or upwards to a maximum value. The drive device is connected to the output of a counter stage. If the number selected in the counting range is undershot, the power supply is switched on, if it is exceeded, the power supply is blocked, as a result of which the speed of the drive device changes accordingly.

However, this circuit arrangement makes it impossible to monitor the speed ratio of different shafts.

From EP 0 088 626 a device for speed control of a rotating body is known, in which a tachometer rotor which is mechanically connected to a rotating body is provided with P teeth on the circumference. A sensor generates a pulse each time one of these teeth passes, resulting in a frequency signal with p times the rotational frequency, which is recorded by a counter. An output signal is generated after every (n · P) th pulse. In addition, the frequency of a high-frequency clock is counted by a second counter and the count result is stored in a memory. After each output pulse the counted result of the first counter is reset. A representation of the orbital time of the rotating body can be obtained, from which a comparator derives a speed control signal.

However, monitoring the speed ratio of rotating bodies is also not possible with this device.

The invention has for its object to provide a textile machine of the type mentioned, in which a reliable monitoring of the drafting system is ensured in an extremely simple manner, in particular with regard to compliance with predetermined speed ratios of the different drafting system strands.

The object is achieved according to the invention in a device of the type mentioned by the characterizing features of claim 1.

This design ensures that even the smallest deviations in the speed of the drafting system strands and therefore not easily detectable yarn defects can be reliably and quickly detected with the simplest means. The delicacy of the delay errors still to be recognized is due to the number of markings, in particular the differences the number of these markings for the cylinders of a respective strand pair, the width of the pulses generated and the width of the time interval or reset window can be specified.

The counter is replaced by the pulses of the first output signal, which has a higher pulse repetition frequency, e.g. counted up. After reaching the lower meter reading limit, a kind of reset window is opened, which is closed again after reaching the upper meter reading limit. If a pulse of the second output signal having a lower pulse repetition frequency falls into the open reset window, the counter is reset when this pulse occurs and then counted up again by the pulses of the first output signal. The pulse repetition frequency of the second output signal is chosen in particular by the relative number of markings such that at no time do two pulses of this signal fall into the reset window. If a relevant pulse of the second output signal occurs too early with respect to the reset window, the counter cannot be reset. As a result, e.g. the upper counter limit value is reached, after which the trigger signal for an alarm, a machine standstill or the like is issued. The same applies in the event that the relevant pulse of the second output signal occurs too late with respect to the reset window. Here too, the e.g. upper counter limit reached and the relevant trigger signal issued.

A counting counter can also be used in a corresponding manner. In this case, the decisive criterion for the release of the trigger signal is that the lower meter reading limit value is not reached.

Although the invention can preferably be used for monitoring the relative speeds of the drafting system strands, it can in principle also be used for corresponding monitoring of the relative speeds, in particular of the delivery line of the drafting system and the spindles. The drafting system (and the ring bench) are to be moved in relation to the spindles in such a way that, on the one hand, there are no thread breaks and, on the other hand, the yarn quality that occurs when starting or stopping corresponds to that of normal operation as far as possible.

It is also particularly advantageous that the drafting system monitoring according to the invention can be implemented using such simple and therefore inexpensive components, such as, in particular, electronic counters and the like.

The cylinder of the strand of the drafting system rotating during operation at a higher speed preferably has a higher number of markings than is the case with the strand rotating at a lower speed. In this way, a much higher pulse repetition frequency of the first output signal which effects the counting is additionally achieved in a simple manner, so that overall high resolution can be achieved with sufficiently narrow pulses of the second output signal. The highest resolution results from the smallest reset window or counting interval, which is determined, for example, by the distance between two pulses of the first pulse generator output signal which effects the counting. The cylinder with the smaller number of markings can expediently have only a single marking. As a result, the relative difference in the number of markings and thus the pulse repetition frequencies of the two pulse generator output signals is greatly increased, which results in an additional improvement in the resolution of the delay errors.

Here, the larger number of markings of the relevant cylinder can expediently be at least ten times, preferably ten times to thousands, and in particular one hundred times the smaller number of markings of the other cylinder concerned.

The markings are preferably arranged on the circumference of the cylinders in question and, in the case of a large number of markings per cylinder, are distributed uniformly over the circumference of this cylinder. In the case of rotating cylinders, this results in a constant pulse repetition frequency for a respective cylinder, provided that this cylinder is driven at a constant speed.

According to a preferred embodiment variant of the invention it is provided that on the one hand the rear or feed line and on the other hand the front or delivery line of the drafting device is assigned to each. This is particularly useful in the event that the middle strand and the rear strand of the drafting system are connected to one another via a gear and can be driven by a common drive, while the front or delivery strand can be driven separately.

In contrast, if all of the drafting system strands can be driven separately in a further decentralization of the drive, it is advantageous to assign a pulse generator to each string and to supply the output signals of the two pulse generators assigned to a respective pair of string to the counting input or reset input of a respective electronic counter. Here, the relative speed of the rear strand and the middle strand and / or the rear strand and the front strand and / or the middle strand and the front strand can be monitored.

If a common rear cylinder, a common front or delivery cylinder and possibly a common center cylinder are provided for several drafting systems, the markings are expediently arranged on the relevant common, preferably lower cylinders or rollers.

The electronic counter can be part of a digital tachometer so that, for example, the absolute speeds can also be indicated at the same time.

The predeterminable lower and upper counter limit values which determine the reset time window are preferably programmable in the electronic counter or digital tachometer. A battery-buffered memory is expediently provided for storing these lower and upper meter reading limit values, so that the entered values are still available even after restarting.

In a further practical embodiment variant of the textile machine according to the invention, the electronic counter or the digital tachometer has a digital display, in particular for displaying the measured speeds and / or speed differences.

The pulse generators that respond to the markings can include optical, inductive or capacitive sensors.

Fig. 1

eine schematische Darstellung eines drei Stränge aufweisenden Streckwerks einer Ringspinnmaschine,

Fig. 2

eine schematische Darstellung der mit Markierungen versehenen Hinter- und Lieferzylinder des in Fig. 1 gezeigten Streckwerks mit einer zugeordneten, das Drehzahlverhältnis überwachenden Einrichtung, und

Fig. 3

ein Zeitdiagramm zur Darstellung des dem Zähleingang zugeführten ersten und dem Rücksetzeingang zugeführten zweiten vom Vorderzylinder bzw. Hinterzylinder abgeleiteten Impulsgeber-Ausgangssignals sowie des Rücksetzzeitfensters des verwendeten elektronischen Zählers.

The invention is explained below using an exemplary embodiment with reference to the drawing; in this shows:

Fig. 1

2 shows a schematic representation of a drafting device of a ring spinning machine having three strands,

Fig. 2

a schematic representation of the rear and delivery cylinders provided with markings of the drafting system shown in FIG. 1 with an associated device which monitors the speed ratio, and

Fig. 3

a timing diagram showing the first input and the reset input supplied second pulse generator output signal derived from the front cylinder or rear cylinder and the reset time window of the electronic counter used.

In Fig. 1, a drafting device 52 is shown, for example, a ring spinning machine.

The drafting system shown comprises a rear or feed strand 54, a middle strand 56 and a front or delivery strand 58. The sliver or thread 16 is e.g. delivered to a spindle of the relevant ring spinning machine.

The strands 54, 56, 58 of the drafting unit 52 each comprise a lower cylinder, namely the rear or feed cylinder 10, the middle cylinder 12 and the front or delivery cylinder 14 and on the other hand each an overhead roller, namely the rear or feed roller 60, the middle one Roller 62 and the front or delivery roller 64.

The cylinders 10, 12, 14 located below are each intended simultaneously for several drafting systems on a respective machine side. A special drive 18, 20, 22 is assigned to each of these cylinders. These drives can each comprise, for example, a drive motor that is speed-controlled via the supply frequency.

The rotational speed of the drafting system strands 54, 56, 58 increases from the intake strand to the front delivery strand 58, so that a pre-drafting field 66 is formed between the first pair of strings 54, 56 and a main drafting field 68 is formed between the second pair of strands 56, 58.

2, the rear cylinder 10 and the delivery cylinder 14 are provided with markings 36, 38. These markings are each arranged on the circumference of the relevant cylinder 10, 14 and are detected by sensors 28, 30 of two pulse generators 24, 26. One pulse generator 24 or its sensor 28 is arranged in the peripheral region of the rear cylinder 10 driven at a lower speed, while the other pulse generator 26 is provided in the peripheral region of the front or delivery cylinder 14 rotating at a higher speed.

The pulse generator 26 supplies a first output signal S 1 via a signal line 34 to a counter input 42 of an electronic counter 70 formed, for example, by a digital tachometer. The pulse generator 24 assigned to the rear cylinder 10 supplies a second output signal S 2 to a reset input 40 of the electronic counter 70 via a signal line 32 .

The sensors 28, 30 can be, for example, optical, inductive or capacitive sensors. The two pulse generators 24, 26 comprise pulse shaping circuits for delivering at least substantially rectangular pulses.

While the rear cylinder 10 rotating at a lower speed in operation is provided with only a single marking 36 provided on the circumference, the faster rotating front or delivery cylinder 14 has a larger number of such markings 38 on the circumference. In the present embodiment one hundred such markings 38 are provided for the delivery cylinder 14. While the pulse generator 24 emits only one pulse per revolution of the rear cylinder 10, the pulse generator 26 thus delivers one hundred such pulses per revolution of the delivery cylinder 14. The rear cylinder 10 can be driven, for example, in a speed range from 0.9 to 45 rpm and the delivery cylinder 14, for example, in a speed range from 15 to 480 rpm. This results in values of 0.75 Hz or 850 Hz for the maximum frequency.

The electronic counter 70 or digital tachometer has two control inputs 48, 50 for setting a lower and an upper counter limit value. A counting interval is defined by the two respectively set lower and upper counter reading limit values, which determines a reset time window T 1 to T 2 of the electronic counter 70 (cf. also FIG. 3). The electronic counter 70 can only be reset by a respective pulse of the pulse generator 24, ie the second pulse generator output signal S₂, during this predeterminable counting interval or reset time window. If a pulse derived from the mark 36 of this second pulse generator output signal S₂ with respect to the set reset time window T₁ to T₂ occurs too early or too late, then the electronic counter 70 is not reset, from which it follows that in the case of an incrementing counter the upper limit value of the counter and in the case of a down counter, the lower limit value is reached. After a corresponding passage through the reset time window and reaching the relevant counter reading limit value, the electronic counter 70 supplies a trigger signal S₃, for example for an alarm, a machine downtime or the like.

In the present exemplary embodiment, an up counter is provided as the electronic counter 70, as can be seen in particular from the time diagram according to FIG. 3.

In FIG. 3, the pulses 44 derived from the rear cylinder 10 are shown in the upper part of the time diagram. After the rear cylinder 10 is only provided with a single marking 36 (cf. FIG. 2), the time T _{U / Hz,} for example between the rising flanks of two pulses 44 occurring, indicates the time required for one revolution of the rear cylinder 10. During this orbital time T _{U / Hz} related to the rear cylinder 10, one hundred pulses 46 of the first pulse generator output signal S 1, derived from the markings 38 of the front cylinder 14, occur when the desired speed ratio is maintained. In the diagram according to FIG. 3 only part of the pulses 46 is shown.

The pulses 44, 46 of the two output signals S₂ and S₁ have the same amplitudes A. Although in the example shown the pulse width of the pulses 44 is smaller than that of the pulses 46, this pulse width generally does not matter; the edges of the impulses are decisive.

3, the reset window RF is opened at time T 1 and closed again at time T 2. In the present case, the RF signal has the logic zero state when the reset time window or resettor is open, while the logic one state prevails when the reset time window RF is closed.

The time T₁ is determined in the present embodiment by the rising edge of the pulse 46 'of the first pulse generator output signal S₁, when the counting electronic counter 70 occurs, the one by the first Control input 48 assumes the lower meter reading limit.

This lower counter reading limit value can be set to the value 3752, for example. The time T₂ forming the upper limit of the reset time window is determined by the rising edge of a pulse 46˝ of the first pulse generator output signal S₁, upon occurrence of which the electronic counter 70 assumes the upper counter limit value, which can be set by the second control input 50. In the present case, this upper counter limit is set to 3756.

Now occurs the pulse 44 within the reset time window T₁ to T₂, the electronic counter 70 is reset to then e.g. count up again until the next reset.

If a pulse 44 'or its rising edge occurs at a time T₀ before the reset time window T₁ to T₂, then this pulse 44' cannot reset the counter. After the time interval between the pulses 44 in particular is substantially larger than the time window T 1 to T 2, on the other hand, no pulse 44 occurs in the latter case during this reset time window, so that the counter 70 counts up to the upper limit value, in the present case 3756 , in order to then trigger signal S₃ for example issue an alarm, machine downtime, or the like. This upper counter reading limit value is reached according to FIG. 3 at time T₂.

The upper counter limit is reached with the same consequences even if a pulse 44˝ of the second pulse generator output signal S₂ occurs at a time T₃ after the time window T₁ to T₂. In this case, too in the time window T₁ to T₂ none of the pulses 44, so that the counter 70 can not be reset and yet the upper limit value is reached.

By entering the upper and lower counter limit values via the control inputs 48, 50, the width of the reset time interval T₁ to T₂ can be varied. The minimum width is predetermined, for example, by the distance between the rising edges of two successive pulses 46 of the first output signal S 1 emitted by the pulse generator 26.

The narrower the reset time window T₁ to T₂, the greater the sensitivity of the monitoring with regard to delay errors.

While only the rear cylinder 10 and the delivery cylinder 14 are provided with markings 36, 38 in the exemplary embodiment described, it is fundamentally also conceivable for all cylinders 10, 12, 14, i.e. in particular also to assign such markings to the central cylinder 12 and correspondingly to a pulse generator with sensor.

1 separate drives 18, 20 are assigned to the rear cylinder 10 and the middle cylinder 12, it is also conceivable to provide a common drive for these two cylinders and to couple the cylinders to one another via a mechanical transmission. In this case, it is sufficient to assign either the rear cylinder 10 or the middle cylinder 11 a pulse generator and to mark this cylinder accordingly.

In particular in the event that all drafting system strands 54, 56, 58, as shown in FIG. 1, can be driven separately, it can be provided that each line is assigned a pulse generator and the output signals of the two are assigned to a respective line pair 54, 58; 54, 56; 56, 58 assigned pulse generator to the counter input 42 or reset input 40 of a respective electronic counter.

It is particularly advantageous if the electronic counter 70 is formed by a part of a digital tachometer, by means of which, for example, the absolute speeds and / or the speed ratios can be displayed.

In order to ensure that each time the spinning machine is started up again, there are always defined operating conditions with regard to the intended drafting system monitoring, the predeterminable lower and upper counter limit values can be programmable in the electronic counter 70 or digital tachometer. In this case, it is expedient to provide a battery-buffered memory for storing the counter reading limit values, so that, for example, the relevant values are not lost even in the event of a power failure.

Although the markings 36, 38 are preferably arranged on the lower cylinders 10, 14 and possibly 12, it is in principle also conceivable to provide the rollers 60, 62, 64 on the top with these markings.

While there is a pure drafting system monitoring in the described embodiment, the monitoring device described can also be used to monitor the relative speed ratios, in particular of the delivery line 58 and the relevant spindles.

Instead of the one mark on the slower rotating cylinder, a higher number of markings, in particular the same number of markings as in the case of the faster-running strand, can also be provided. In this case, a divider module is expediently connected downstream of the connected pulse generator in order to again receive the one pulse per revolution.

Furthermore, it is also conceivable to assign such a pre-divider to the other strand or to both strands. Finally, such a divider module also eliminates the requirement that one of the two strands runs more slowly.

With the use of the divider modules mentioned it is u. a. possible to implement identical pulse generators or digital tachometers on both shafts. With the exception of the pulse generators, these elements can also be implemented, for example, as software modules of a microprocessor program.

Claims (12)

1. A textile machine, in particular a spinning machine, with at least one drafting arrangement (52) comprising several lanes (54, 56, 58) such as pairs of rollers, cylinder/roller pairs or the like, for example, for forming at least one draft zone lying between two respective lanes (66, 68), which are drivable at different speeds for producing the draft, whereby one electronic pulse generator (24, 26) is provided for at least two lanes (54, 58) of the drafting arrangement (52) and the output signals (S1, S2) of the electronic pulse generators (24, 26) have pulse repetition frequencies which depend on the respective cylinder speed and which differ during the operation, and an electronic counter (70) supplies a trigger signal (S3) for an alarm, a machine standstill or the like, characterized in that the electronic pulse generators (24, 26) respond to the markings (36, 38) of a roller or a cylinder (10, 14) of the respective lane, that the respective pulse repetition frequencies which are different during the operation depend on the respective number of markings, that the output signal (S1) which is provided with a higher pulse repetition frequency is supplied to a counter input (42) and the second output signal (S2) which is provided with a lower pulse repetition frequency is supplied to a reset input (40) of the electronic counter (70), that the counter of the second output signal (S2) can only be reset by a counter interval (T1-T2) which is predefinable by a lower counter reading limit and an upper counter reading limit, and that the electronic counter (70) supplies a trigger signal (S3) after passing through said counter interval forming a reset window, whereby in particular the cylinder (14) of the lane (58) which rotates at higher speed during the operation is provided with a higher number of markings (38) than is the case in the lane (54) rotating at a lower speed.
2. A textile machine as claimed in claim 1, characterized in that the higher number of markings (36) of the respective cylinder (14) is at least ten times, preferably ten to one thousand times and particularly one hundred times the lower number of markings (36) of the respective cylinder (10).
3. A textile machine as claimed in claim 1 or 2, characterized in that the cylinder (10) with the lower number of markings is only provided with a single marking (36).
4. A textile machine as claimed in claim 1, characterized in that a divisor module is arranged behind at least one of the two electronic pulse generators (24, 26) and that the allocated cylinder (10) is provided with more than one marking (36), preferably with the same number of markings as is provided on the cylinder (14) allocated to the other electronic pulse generator (26).
5. A textile machine as claimed in one of the previous claims, characterized in that the markings (36, 38) are provided on the circumference of the cylinders (10, 14) and that they are evenly distributed over the circumference of the cylinder (14) in the event of a plurality of said markings (38) per cylinder (14).
6. A textile machine as claimed in one of the previous claims, characterized in that a pulse generator (24, 26) is each allocated, on the one hand, to the rear or drawing-in lane (54) and, on the other hand, to the front or delivery lane (58) or that a pulse generator (24, 26) is each allocated, on the one hand, to the central lane (56) and, on the other hand, the front or delivery lane (58).
7. A textile machine as claimed in one of the previous claims, characterized in that all drafting lanes (54, 56, 58) are seperately drivable, that every lane is provided with a pulse generator (24, 26) which responds to the markings arranged on the allocated cylinders (10, 14), and that the output signals (S1, S2) of the two pulse generators allocated to the respective pair of lanes (54, 58; 54, 56; 56, 58) is supplied to the counter input (42) or reset input (40) of a respective electronic counter (70).
8. A textile machine as claimed in one of the previous claims, characterized in that one common back roll (10), front or delivery cylinder (14) and optionally intermediate cylinder (12) are provided for several drafting arrangements, whereby the markings (36, 38) are arranged on the respective common cylinders (10, 12, 14).
9. A textile machine as claimed in one of the previous claims, characterized in that the electronic counter (70) is a digital counter or that the electronic counter (70) is part of a digital tachometer.
10. A textile machine as claimed in one of the previous claims, characterized in that the predefinable lower and upper counter reading limits are memory-programmable in the electronic counter (70) or digital tachometer, whereby a battery-buffered memory is provided in particular for storage of the lower and upper counter reading limits.
11. A textile machine as claimed in one of the previous claims, characterized in that the electronic counter (70) or digital tachometer comprises a digital display, in particular for displaying the measured speeds and/or differences in the speeds.
12. A textile machine as claimed in one of the previous claims, characterized in that the pulse generators (24, 26) responsive to the markings (36, 38) comprise optical, magnetic, inductive or capacitative sensors (28, 30).

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