DE3536991C1 - Textile web monitoring device for registering defects - Google Patents

Description

The invention relates to a textile web monitoring device for registering defects with at least one optoelectric monitoring head based on light reflection as a signal generator and with an electrical signal evaluation circuit comprising a microprocessor and output signals for controlling at least one switching device delivers.

Textile web monitoring devices with optoelectric over guard heads are already known, for example by DE-OS 14 35 180 and 19 38 677. It is also a Textile web monitoring device with optoelectric over guard head known, the signal evaluation circuit one Microcomputer includes (DE-OS 31 33 428). The signal evaluations circuit has the disadvantage that it is not for the evaluation of samples of patterned or structured suitable textile webs. All previously known textile web monitoring devices have the disadvantage that their Sensitivity in time-consuming manual adjustment to one textile web to be monitored must be adapted and / or that they avoid a complicated circuit structure faulty switching.  

The invention has for its object a textile web Training device of the type mentioned in the beginning that there is an automatic adjustment of his sensitivity on the degree of reflection of the monitored Textile web allowed and thereby ensures a reliable error display.

The task is done with a textile web over Monitoring device of the type mentioned in the invention solved in that the monitoring head at least one Light pulses lie in a known manner with a predetermined clock remote light transmitter and an associated, accordingly clocked reflection light signals, optoelek trical light receiver, and that in the with connected at least one light receiver, one behind the other the one signal amplifier with several amplification stages fen, a trigger level and an error display level send signal evaluation circuit of the signal amplifier and the trigger level can be influenced by the microprocessor, the Trigger level one of the degree of amplification of the signal amplifier kers adjustable trigger level and at least an error display evaluation stage is provided.

It is known in principle from DD-PS 79 797 several amplifier stages, one trigger stage and one miss Level of display at a textile web monitoring facility device, but the amplifier stages and the trigger circuit to form a square wave signal. The trigger level is at a predetermined fixed level Value set that cannot be changed. The invention trained textile web monitoring device on the other hand, allows the monitoring to be calibrated automatically device before the start of error monitoring. This invented  Calibration method according to the invention is characterized in that first the signal amplifier on the to detect the over a specified calibration time or a specified relay active movement distance of the monitoring head on a fault-free Weakest occurring Reflection signals required amplification by the microprocessor is set and then using of the microprocessor the trigger level of the trigger stage at a preselectable distance below the set one Output level of the signal amplifier is shifted, be before the microprocessor the error display level take effect leaves.

In the textile web monitoring constructed according to the invention device and its microprocessor-controlled operating method is because of the different reflectance of Textile webs to be monitored inevitably sensitive speed setting of the monitoring device is therefore fully automatic table, and a trigger level for triggering an error signal is automatically set so that signal swan kungen when scanning a patterned textile web with Areas of different reflectance are essential are not triggering an error signal, but only holes and caused by incorrect stitch formation or the like Trigger a fault signal on thin spots in the textile web.

The operational safety of the textile web monitoring device is also due to the special structure of the optoelectri rule the monitoring head, which advantageously meh more infrared LEDs arranged in a row than May have light emitters, each of which one or more, each coupled with a preamplifier are ordered. Both the clocked infrared  light from the LEDs as well as from the monitoring object reflected light through at least one optical lens be directed, which is relative to the monitoring object on its Surface is moved.

The signal amplifier of the signal evaluation circuit can be used moderately upstream of a filter stage, and as an error Display stage of the signal evaluation circuit can be more advantageous example controlled by the pulse output signal of the trigger stage Mono flip-flop circuit may be provided, which at missing trigger stage output pulse an error pulse signal delivers.

The one or more error display evaluation levels of the Textile web monitoring device can preferably a Ma machine shutdown device and / or one with monitoring be coupled head marking device. Latter allows you to mark the detected errors. The signal Evaluation circuit that expediently in a known manner Error counter, at least one optical display device and a keyboard for entering values and / or for scarf device of the microprocessor can advantageously also one by the output pulse signal of the error display level triggerable time period for the temporary interruption of the Have activity of the error display level. The latter te facility is in monitoring the knitted hoses of circular knitting machines advantageous to prevent a mistake once identified in subsequent machines revolutions is registered again by the monitoring head. In circular knitting machines, where usually one by switching Processes in machine tool control-related errors There is a vertical streak in the knitted tube, which is from the Monitoring device should not be registered  expediently this or another interrupt circuit by a signal probing the longitudinal stripe area encoder to be triggered.

A textile web monitoring device according to the invention leaves train themselves as a compact device, its monitoring head can be easily adapted to special purposes, whereby this monitoring device is useful on machines Position of the textile webs to be monitored is arranged and a previously customary manual review of a finished one Makes textile web superfluous. The monitor is easy to use because thanks to the automatic Sensitivity adjustment of the device the adjustment processes on predeterminable, no professional skill restrict key operations required, for example for specifying a specific error setpoint number, up to its number Reach the machine can not be turned off should, or to specify the number of distance levels, which take the trigger level from the set amplifier level should, for example, only holes of a certain size to register as an error.

Below is an embodiment of a fiction moderately trained, for use on a circular knitting machine provided textile web monitoring device based on the Drawing explained in more detail. In detail shows

Figure 1 is a schematic overall representation of a circular knitting machine equipped with the monitoring device.

Figure 2 shows a cross section through a first embodiment example of the optoelectric monitoring head coupled to a marking device of the monitoring device.

Fig. 3 is an end view of the monitoring head in the direction of arrow III in Fig. 2;

FIG. 4 shows a schematic sectional illustration corresponding to FIG. 2 through a second exemplary embodiment of the monitoring head;

Fig. 5 is a block diagram of the electrical Signalaus value circuit of the monitoring device;

Fig. 6 is a block diagram of the signal amplifier and the trigger level of the signal evaluation circuit of the monitoring device;

FIGS. 7 and 8 two signal diagrams for explaining the effect We example of the signal amplifier and the trigger level of the signal evaluation circuit;

Fig. 9 is a signal diagram demonstrating the error display;

Fig. 10 is a schematic view of the display and operating side of the housing comprising the signal evaluation circuit of the monitoring device.

Fig. 1 shows the frame 10 of a circular knitting machine, with a laterally attached drive part 11 for a needle cylinder, not shown, which rotates within a stationary lock casing 12 , optionally together with a nadelbe set washer, and forms a knitted tube 13 in a known manner. The knitted tube 13 is monitored on its way from the stitch formation area to the take-off and winding device 14 of the circular knitting machine by a textile web monitoring device for knitted fabric defects. The monitoring device has an optoelectric monitoring head 15 which lies tightly against the outside of the knitted tube 13 and on which the rotating knitted tube 13 is moved past. The monitoring head 15 is connected to a signal evaluation circuit installed here in the drive part 11 of the circular knitting machine, of which only one display and operating side 16 can be seen in FIG. 1.

Figs. 2 and 3 show a first embodiment of the opto-electrical monitoring head 15. Being elongate and oriented in longitudinal direction of the knitted tube 13 the housing 17 is connected via links 18 and 19 to the frame 10 of the circular knitting machine and is held by a tension spring 20 with its touching side in tight contact against the knitted fabric hose. 13 On the tactile side, the housing 17 is closed by an insert body 21 , in which an elongated lens body 22 is inserted. In the interior of the housing 17 of the monitoring head 15 , a series of infrared light-emitting diodes 23, which are mounted at equal intervals, are arranged in the longitudinal direction of the housing 17 and the knitted tube 13 on one side of a partition wall 24 extending from the lens body 22 . On the other side of the partition wall 24 there is a corresponding series of photodiodes 25 that the reflected back from the fabric tube 13 in the Linsenkör by 22 proportion of clocked by the respectively associated light emitting diode 23 emitted and through the lens body 22 through the on the surface Take up knitted hose 13 directed infrared light and convert it in a known manner into an electrical signal which is passed into the evaluation circuit of the monitoring device. From the touching side of the monitoring head pointing Fig. 3 shows how the light emitting diodes 23 and their associated photodiodes 25 are arranged behind the insert body 21 with its lens body 22 are each in a row and at regular intervals.

On the housing 17 of the monitoring head 15 , a marking device 26 is fastened, which on its knitted tube 13 facing end face has one or more marking pins 27 , which or the knitted tube 13 can be electromagnetically advanced to one registered by the signal evaluation circuit To mark the defect in the knitted tube. The associated circuit parts of the monitoring head, for example with the photo diode coupled preamplifier, clock generator and power supply parts, are mounted on a circuit board 29 arranged in the housing 17 .

Fig. 4 shows a modified embodiment of an opto-electric monitoring head 15 , in which behind a translucent end plate 21 a of the housing 17 a of the housing 17 a held in abutment against the knitted tube 13 a glass light guide 28 are arranged in front of the row of infrared LEDs 23 a . The photodiodes 25 a are arranged next to the front end of this glass fiber 28 . All of these parts are mounted directly on the circuit board 29 a .

Fig. 5 shows a block diagram of the signal evaluation circuit of the monitoring device. In the circuit, signal transmission paths are represented by simple arrow lines or by double lines with triangle arrows. It shows a network part 30 , which can be coupled to a battery, not shown, so that the data stored in the microprocessor can be saved in the event of a power supply failure. Furthermore, Fig. 5 shows a microprocessor 31 with associated control circuits, a monitoring head input 32 which is connected to a series circuit of a filter stage 33, a signal amplifier 34, a trigger stage 35 and an error display step 36. A machine switch-off stage 37 is shown of several possible error display evaluation stages. As signal lines are a line 38 leading from the monitoring head connection 32 to the filter stage 33 , a line 40 leading from a further monitoring head connection 39 to the microprocessor 31 , a line 42 leading from a sensor connection 41 (e.g. inductive transmitter) to the microprocessor, a leading of the error display circuit 36 to a control and display circuitry of the microprocessor 31 line 43, one of a control circuit of the microprocessor 31 to the machine func switching stage 37 carrying line 44, a Darge set by a control circuit of the microprocessor 31 to that in Fig. 2 marking device 26 leading line 45 and a line 47 leading from a key switch 46 to the microprocessor 31 are shown. Microprocessor control lines 48 and 49 lead from the microprocessor 31 to the signal amplifier 34 and the trigger stage 35 . In addition, microprocessor control lines 50 and 51 are shown, which lead to a key board 52 and an optical display part 53 .

The signal evaluation circuit has, in a known manner, an error counter (not shown individually here), which is triggered by the output signals of the error display stage 36 , and whose counting state in the optical display part is visible with a display area 58 shown in FIG. 1. The error counter may be formed as a comparison stage, which is coupled to a reference value transmitter, which on the key board 52 in a specific and appears in the display area 58 minimum number of errors can be keyed, when engine shut down is to take place only after reaching a certain minimum number of errors. Also not shown is an inserted into the control circuit of the microprocessor 31 , which temporarily turns off the error indicator stage when an error signal occurs at the error indicator stage 36 in order to avoid double registration of the same error. The shutdown status can be indicated, for example, by the flashing of a green operating indicator lamp, while a red operating indicator lamp indicates that the machine has been switched off.

Fig. 6 shows schematically the structure of the signal amplifier 34 and the trigger stage 35 of the signal evaluation circuit. The signal amplifier 34 has a switching stage 54 controlled by the microprocessor, with which the degree of amplification of the actual amplifier circuit 55 in a total of z. B. six ten levels is changeable. In a similar way, the trigger stage 35 is provided with a switching stage 56 which can be controlled by the microprocessor, with which the trigger level of the actual trigger circuit 57 is set to e.g. B. sixteen different values is adjustable.

FIG. 10 shows the display and operating side 16 of the housing containing the signal evaluation circuit with the circuit parts shown in FIG. 5. It has the opti cal display field 58 , the key board 52 , the lock opening of the key switch 46 , two operation indicator lamps 59 and 60 , an on / off switch 61 , a power cord 62 and three flange sockets 63, 64 and 65 for connecting the monitoring head 15th of the encoder (e.g. inductive encoder) and the machine shutdown device 37 .

The mode of operation of the textile web monitoring device is the following:

The monitoring head 15 , which is attached to the textile web to be monitored, here the knitted tube 13 , supplies corresponding signals through its photodiodes 25 to the clocked reflected infrared light received by them. The signals from the photodiodes 25 arrive after a gain and summary in the monitoring head 15 via the connection 32 in the signal evaluation circuit and there via the signal line 38 in the filter stage 33 . Via the connection 39 and the signal line 40 , the microprocessor 31 can recognize whether a monitoring head is connected. In the filter stage 33 , interference signals and noise signals are filtered out. In the following signal amplifier 34 there is a gain by a gain previously set during a calibration process, which will be described below, and the signal amplified in this way is passed on to the trigger stage 35 , the trigger level of which has also been previously defined during the calibration process to be described . The diagram in FIG. 9 shows the trigger level 66 set during calibration and the signal curve 67 resulting from the peaks of the individual clock signals amplified in the signal amplifier 34 . If the knitted fabric is free of defects, the amplified clock signals are all above the trigger level 66 . In the case of holes in the knitted tube, however, the reflected amount of light is so small or completely absent that the signal which occurs at the fault and is uniformly amplified in the signal amplifier 34 is so weak that it is below the trigger level 66 . Fig. 9 shows the course of the signal curve at a first, caused by a small hole flaw 68 and at a second and larger hole caused by a flaw 69th Only a clock signal that exceeds the trigger level 66 generates an output signal at the trigger stage 35 .

The error display stage 36 is a so-called mono-flip-flop circuit, the cycle duration of which is somewhat longer than the cycle interval of the signals supplied by the monitoring head 15 . Accordingly, the mono-flip-flop circuit of the error display stage 36 is kept at the signal level 70 shown in FIG. 9, as long as 35 output signals appear at the output of the upstream trigger stage in the sampling clock. However, if an output signal from the trigger stage 35 is missing, which is the case with the errors 68 and 69 , the signal level 70 is interrupted over a shorter period 71 or a longer period 72 . These interruptions lead to output signals of the error display stage 36 , which are passed to control circuits of the microprocessor 31 for evaluation via the signal line 43 .

The degree of amplification of the signal amplifier 34 and the trigger level 66 of the subsequent trigger stage 35 are automatically set in a calibration process preceding the error monitoring in adaptation to the nature of the knitted hose 13 to be monitored. For this purpose, the scanning signals supplied by the monitoring head 15 over at least one full turn of the circular knitting machine from an error-free knitted area are evaluated by the microprocessor 31 and the degree of amplification of the signal amplifier 34 is adapted to the weakest signal, that is to say the smallest degree of reflection of the error-free substance. The degree of amplification of the signal amplifier is thus set to one of its sixteen stages so that there is good amplification even of the weakest scanning signals. With patterned fabrics, the signal levels can vary significantly. Practically none for single-color and simply structured fabrics. It is also ensured by the microprocessor 31 that the gain level maintains a sufficient distance from the modulation limit of the signal amplifier 34 .

The diagrams of FIGS. 7 and 8 illustrate in their left half the processes in the signal amplifier 34 during the calibration process. In the exemplary embodiment according to FIG. 7, the degree of amplification is gradually increased in adaptation to the amplitude of the incoming clocked scanning signals, which results in a step curve 73 . If this staircase curve exceeds the maximum level 66 max shown in the diagram of the subsequent trigger level 35 , which is the case in the curve area 73 a , the microprocessor 31 controls the gain level back to an amplification level whose amplitude value is below the maximum level 66 max of the trigger level 35 , so that the curve 73 takes the course of the area 73 b of FIG. 7. The even curve in area 73 b shows that a single-color knitted tube is scanned.

In the exemplary embodiment according to FIG. 8, the degree of amplification of the signal amplifier 34 is downgraded at the beginning from a maximum trigger level 66 max via an increasing amplification range with the curve profile 73 a to a gain range below with the curve profile 73 b .

After this adjustment of the degree of amplification of the signal amplifier 34 , the trigger level 66 of the trigger stage 35 is gradually switched back from the maximum level 66 max by the microprocessor 31 , as can be seen from the right half of the diagrams in FIGS. 7 and 8. The trigger level 66 is reset at least to the level level 66 a shown in FIGS . 7 and 8, which is clearly below the curve area 73 b of the signal amplifier 34 . If only coarser errors are to be displayed, the trigger level 66 is lowered even further to level 66 b or 66 c , which the operator can set on the keyboard 52 of the front plate 16 of the signal evaluation circuit.

Only after the calibration process described has been completed does the error display stage 36 take effect and does the actual error monitoring process begin with the effect described above with reference to the diagram in FIG. 9.

Claims (10)

1. Set textile web monitoring device for registering errors, with at least one optoelectric monitoring head based on light reflection as a signal generator and with an electrical signal evaluation circuit which comprises a microprocessor and provides output signals for controlling at least one switching device, characterized in that the monitoring head ( 15 ) at least one light transmitter ( 23, 23 a) delivering light pulses in a known manner with a predetermined clock and an associated optoelectric light receiver ( 25, 25 a) detecting the corresponding clocked reflection light signals, and in that with the at least one light receiver ( 25 , 25 a) connected, one behind the other a signal amplifier ( 34 ) with several amplification stages, a trigger stage ( 35 ) and an error display stage ( 36 ) having signal evaluation circuit of the signal amplifier ( 34 ) and the trigger stage ( 35 ) of the microprocessor ( 31 ), the trigger rstufe ( 35 ) of the level of amplification of the signal amplifier ( 34 ) adjustable trigger level ( 66 ) and at least one error display evaluation stage ( 37 ) is provided. 2. Textile web monitoring device according to claim 1, characterized in that the optoelectric monitoring head ( 15 ) has a plurality of infrared light-emitting diodes ( 23, 23 a) arranged in a row as light emitter, which several, each with a preamplifier coupled photo receiver ( 25, 25th a) are assigned. 3. textile web monitoring device according to claim 1 and 2, characterized in that both the clocked infrared light of the light emitting diodes ( 23, 23 a) and the object to be monitored (knitted tube 13 ) reflected light through at least one lens body ( 22 ) or light guide body ( 28 ) is guided, which is moved relative to the monitoring object on its surface. 4. Textile web monitoring device according to one of claims 1 to 3, characterized in that a filter stage ( 33 ) is connected upstream of the signal amplifier ( 34 ) of the signal evaluation circuit. 5. Textile web monitoring device according to one of claims 1 to 4, characterized in that the Fehleranzeigestu fe ( 36 ) of the signal evaluation circuit is a mono-flip-flop circuit controlled by the pulse output signal of the trigger stage ( 35 ), which in the absence of trigger stage off gangsimpuls delivers an error pulse signal. 6. Textile web monitoring device according to one of claims 1 to 5, characterized in that a machine switch-off device ( 37 ) and a coupling device ( 26 ) coupled to the monitoring head ( 15 ) are provided as an error display evaluation stage. 7. textile web monitoring device according to one of claims 1 to 6, characterized in that the signal evaluation circuit in a known manner, an error counter, min least an optical display device ( 58 ) and a keyboard ( 52 ) for entering values and / or for switching device of the microprocessor ( 31 ). 8. textile web monitoring device according to one of claims 1 to 7, characterized in that the signal evaluation circuit has a triggerable by the output pulse signal of the error display stage ( 36 ) time step for interruption th activity of the error display stage ( 36 ). 9. Textile web monitoring device according to one of claims 1 to 8, characterized in that the error counter of the Signal evaluation circuit as with a setpoint generator coupled comparison stage is formed. 10. The method for automatically calibrating a textile web monitoring device according to one of claims 1 to 9, characterized in that first the Signalver stronger ( 34 ) on the detection distance over a given calibration time or a predetermined Relativbewe movement distance of the monitoring head ( 15 ) an error-free textile web area weakest reflection signal required gain is set by the microprocessor ( 31 ) and then by means of the microprocessor ( 31 ) the trigger level ( 66 ) of the trigger stage ( 35 ) to a preselectable distance ( 66 a , 66 b , 66 c) below the set output level (curve section 73 b) of the signal amplifier ( 34 ) is shifted before the microprocessor ( 31 ) makes the error display stage ( 36 ) effective sam.