DE2208440A1 - CIRCUIT ARRANGEMENT FOR REGULATING THE THREAD SPEED IN WINDING DEVICES - Google Patents

Description

Circuit arrangement for regulating the yarn consistency in winding devices

The invention relates to a circuit arrangement for regulating the thread speed in winding devices, with the help of a device that detects the peripheral speed of the Iffiekel Device which emits a rectangular pulse sequence proportional to the circumferential speed, from one the variable corresponding to the actual value for the speed controller of the winder drive is formed.

The properties of thread-like materials _5, such as yarns in the textile industry, can be changed significantly if the pad tension changes during the winding process. Winding devices are therefore equipped with a thread tension control. In the case of extremely thin yarns, however, the thread tension cannot be detected in the usual way via a pendulum or Tänser roller arranged in the fabric path, so that one is forced to fall back on a substitute control variable, namely the thread speed. However, since the direct detection of the yarn speed also requires a complex measuring device:

is it appropriate

to use the peripheral speed of the reel as a control variable.

In a known drive of this type wirä su this purpose uses a feeler roller; the opposite surface of the roll is pressed. With the axis of the feeler roller ie "'as a precaution a contactless giver. z, 3, an opto-electrical encoder

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coupled. This emits a pulse sequence of variable frequency proportional to the circumferential speed of the roll. After appropriate pulse shaping via a frequency-voltage converter, this pulse sequence becomes the actual one The actual value of the controlled variable for the yarn speed controller is derived.

The use of a frequency-to-voltage converter not only represents additional expenditure, it also influences it the accuracy of the Regulation unfavorable.

The invention is therefore based on the object of providing a circuit arrangement of the type described at the beginning train that can be dispensed with a frequency-voltage converter. This object is achieved according to the invention solved in that the circumferential speed of the roll proportional rectangular pulse train via a differentiator and a rectifier is passed that the instantaneous value of the differentiated square-wave pulses with a DC voltage setpoint is compared and that the difference between this setpoint and instantaneous value of the differentiated Pulses is fed to an integrator. Instead of a frequency-voltage converter, there is a simple differentiator with rectifier, so that not only the circuit arrangement is simplified quite considerably, but also the The accuracy of the control increases because it is in the target / actual value circuit (Detection of the control deviation) only passive elements, such as an RC element and a diode, are present.

The invention is explained in more detail with reference to the drawing, in which an exemplary embodiment is shown; show it:

Figure 1 is a block diagram of an axle winder drive as it can be used in the textile industry, with a pad speed controller,

Figure 2 is a circuit diagram of the pad speed controller,

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FIG. 3 shows the square pulse train sent to the thread speed controller,

Figure 4 shows the differentiated rectangular pulse train and FIG. 5 shows the rectified pulse sequence according to FIG. 4.

A thread 1 runs over two godets at speed V and is fed via a pressure roller 3 onto a take-up roller

4 wound at a speed V ~. In front of the pressure roller 3, a thread guide, not shown, is provided, which by a periodic back and forth guidance of the thread in a direction parallel to the roller axis for a helical winding of the thread Provides a predeterminable crossing or fluctuation ratio. With the axis of the take-up roller 4 is a direct current motor

5 coupled, the actual speed value of which with the help of a the same axis seated Tachoma chine 'δ is detected. The direct current motor 5 is controlled by a direct current controller 7 controlled by a speed controller S.

The thread tension results from the difference between the two speeds V and V-. The circumferential speed V "is detected via the pressure roller 3, which is connected to an opto-electrical transmitter 20 via a shaft 19. This consists essentially of a rotating prismatic body 21, which with its reflective surfaces deflects light beams from a lamp 22 onto a photodiode 23, which then emits a _{pulse frequency x & corresponding to the speed of the pressure roller 3.} This pulse frequency is converted into a square-wave pulse sequence Χγ with the aid of a downstream pulse shaper stage 9, which can consist of an amplifier and a trigger amplifier. A desired value χ for the speed controller 8 is derived from this pulse sequence via a yarn speed controller 10. The size of the nominal value χ changes with increasing winding diameter so that the motor speed is reduced and thus the circumferential speed v «remains constant. The thread

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Speed controller 10 consists of a differentiator 11 with a downstream rectifier 12, an integrator 13 and a reversing amplifier 14. With 15 is a setpoint generator indicated with which the thread speed fine adjustment can be made. A resistor 16 is used to adjust the level, as will be explained in more detail below will. With a speed setpoint encoder is referred to, with which the coarse thread speed setting can be made. With a correction element 18 is designated.

The mode of operation of the arrangement according to FIG. 1 is as follows:

The square pulse sequence xr according to FIG. 3 is converted in the differentiating element 11 into needle pulses according to FIG. 4, which are rectified with the aid of a rectifier 12, as FIG. 5 shows. The rectified needle pulses x ~ are at one of the desired thread speed V _n . corresponding setpoint χ «compared. The difference between the instantaneous value of the pulse train xr and the nominal value X ₃ ^ (= voltage) is fed to the integrator 13, in which the arithmetic mean of the difference is formed. The output voltage of the integrator 13 is amplified in the reversing amplifier 14 and represents the target value χ _ΟΛ according to the setting of the setpoint generator 17 for the speed controller 8.

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If the speed initially remains constant, its circumferential speed V _{f will also} increase as the diameter of the roll increases. The period T of the rectangular pulse train xr is correspondingly reduced. The thus increased mean value of the difference between the differentiated and the rectified pulses x ^ and the setpoint x _g ^ causes a lowering of the integrator output voltage and thus a reduction in the speed setpoint x _o _. This reduces the speed of the motor and with the now reduced peripheral speed of the roll, the period T increases again. The mean value of the square pulse train Xj decreases and thus the difference between the target value χ «and

sf

the actual value x ^. smaller. If the deviation has become zero, i.e. the thread speed corresponds to the nominal value,

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the output voltage of the integrator does not change more. The process is reversed if the peripheral speed is too low *

The output voltage of the integrator and thus the engine speed will generally be set in such a way as to be the difference between the yarn speed setpoint and us. dsr as a first approximation to the actual yarn speed value proportional circumferential speed of the roll on KuIl will.

Due to the special comparison method _E, in which the nominal value is compared with the instantaneous value of a differentiated square pulse sequence and the difference is used to control an integrator, the otherwise commonly used frequency-voltage converter can be dispensed with. This also eliminates its additional temperature and voltage-dependent errors. Until the point of comparison, if temperature-sensitive components are used in the differentiating element, only the constancy of the input voltage U- _{P is} determined ,

As FIG. 2 shows, the differentiating element consists of an RC combination consisting of a capacitor 24 and a. a resistor 25. The differentiated pulses are then picked up at a resistor 26 and via limiter diodes 27 fed to the input of the integrator 13 «

The integrator 13 is an invextling amplifier 25 with differentiating feedback, which consists of one, two capacitors 29 and 30, the output voltage of which is limited in the positive direction to approximately - * - 0.7 volts by a blade 31. The integration time is determined by the capacitance value of the two capacitors 29 and 30 υτΛ the size of the control current. With a positive input current, ie when the thread speed. corresponding setpoint x _s ^ is smaller than the differentiated pulse train x ~, the two capacitors 29 and 30 are charged to one

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negative voltage value.

The inverting amplifier consists of the two transistors 32 and 33, the transistor 32 having a gain of 1 for reversal and the transistor 33 serving as an emitter follower for current amplification. The inverting amplifier 14 is balanced by the resistors 34 to 37 so that at an output voltage of + _{0.7 volts of the integrator, the voltage across a resistor 38 corresponds to the supply voltage -U n} , a deviation of 0.7 volts but already a decrease causes. The voltage at resistor 38 represents the setpoint for the speed controller.

To ensure that the integrator 13 at each thread speed can pass through its full output voltage range, the thread speed is not sufficient can only be set via the setpoint generator 15. The setting is therefore divided into a coarse and a fine setting divided. A voltage of -5 to -10 volts is required as a target value for the fine adjustment. The coarse adjustment takes place via the setpoint potentiometer 17 of the speed controller 8, which is connected to the output of the inverting amplifier 14 is.

By introducing a voltage via a terminal 39, the speed value of several drives can be controlled from a central Body can be controlled from.

The actual thread speed can be influenced by changing the crossing ratios through the introduction a correction variable proportional to the winding diameter can be compensated for via the correction element 18.

1 claim
5 figures

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Claims (1)

Claim Circuit arrangement for regulating the Padengeschwinäigkeit in winding devices with the help of a device which detects the circumferential speed of the roll and which emits a Hecliteck pulse sequence proportional to the circumferential speed, from which a variable corresponding to the actual value is formed for the pad speed controller of the winding drive, characterized in that the one proportional to the circumferential speed of the roll Square-wave pulse train (xj) is passed through a differentiator (11) and a rectifier (12) so that the instantaneous value (x ^) of the differentiated square-wave pulses is compared with a direct voltage target value (Xgf) and that the difference between this target value (x _g f) and instantaneous value (x ~) of the differentiated pulses (X ₄ ,) is fed to an integrator (13). 309b35 / 0716