EP0674030A1 - Procedure for the production of chenille yarn - Google Patents

Abstract

Produce chenille yarns, the control phases occur in a closed loop. The motor speed is taken at the time by at least one speed transducer (T) to give an electric signal (ST) of a set amplitude applicable to the current speed. The signal amplitude is compared with a reference signal (R) of constant amplitude, set at the required motor function speed. The difference between the signal (ST,R) amplitudes is converted into an error signal (E), to be converted into a signal with a frequency proportionally variable to the error signal (E) amplitude. The converted signal (C) is fed to a wave circuit (1) to change the constant voltage to a voltage value and frequency as a function of the error signal (E) amplitude. The wave circuit output signal (U) sets the motor to give an automatic operational speed instantly, according to the working.

Description

The present invention relates to a process for the production of chenille yarn.

It is known that a chenille yarn consists of two tying yarns which are appropriately twisted to engage the ends of an effect yarn. For this purpose, the machines for caterpillars comprise at least one group for forming the thread, with a "gauge" for the winding and the sizing of the effect thread, a blade for cutting the ends of the effect thread, two drive rollers with corresponding counter-rollers for advancing the binding threads with the ends of the effect thread and means for twisting the binding threads with the ends of the effect thread interposed.

A problem particularly felt in the sector of chenille yarn production is that of achieving high production, of high and constant reliability, of low cost and with the minimum of supervision on the part of the operator.

Also known, from document EP-A1-260206, is a machine for producing fancy yarns, with several groups for forming the yarns, in which each group comprises several rotary members, each of which is controlled by a corresponding electric motor, for feeding, training and assembling various threads intended to form the fancy thread and for the collection of the thread thus produced. Each motor of the machine is slaved to a central unit with programmable microprocessor, according to an open diagram comprising several branches or unidirectional lines of connection of the central unit with the various motors and a signal generator at known and predetermined frequency, in which, on each of said lines, upstream of the respective motor, there is a frequency divider which is slaved to the aforementioned generator to vary the frequency of the respective output signal according to a ratio programmed as a function of the desired fancy effect: said frequency divider being connected, downstream, with a converter supplied with direct current for controlling the corresponding motor online. In this way, the operating speed of each motor is adjusted by varying, each time, on each line, depending on the program, the division ratio of the frequency of the signal emitted by the generator, and by sending to the respective line converter. the control signal thus obtained; the different programmed frequency ratios determine the operating speed of the respective line motors.

However, this known machine is not expressly intended for the production of chenille yarn which must constantly have the same structural characteristics. The open system of driving the line motors of this known machine does not, in fact, allow active control and automatic regulation of the respective operating speeds as a function of the load conditions of the motors, which vary over time, so that the reliability of each line control, that is to say the constancy of the output speed of the motors of each wire formation unit, turns out to be closely dependent on that of the respective bodies for processing the signals received from the central unit and from the generator. sample signals, these organs, being arranged from the functional point of view in cascade on each line, subsequently reduce the reliability of the assembly. Consequently, this known system can be used almost exclusively only in the sectors of the textile industry in which it is not necessary to obtain a constant operating precision, as in the case of fancy yarns, whereas it does not prove to be useful in all other cases where it is desired to obtain complex yarns of high quality and structural characteristics and constant, as is the case of chenille yarn.

The main object of the present invention is to carry out a process for the production of chenille yarn which makes it possible to obtain, automatically, the maximum and constant qualitative level of the yarn and, at the same time, a high and very economical production.

This result has been achieved, in accordance with the invention, by adopting a process for the production of chenille yarn in a machine with one or more groups for forming the yarn, comprising, for each training unit, the winding and sizing phases. an effect yarn, cutting the effect yarn into sections of predetermined length, feeding two threads for binding and driving these yarns with the sections of the effect yarn and twisting the yarns of bonding with the sections of the interposed effect wire, by means of several corresponding operational members, each of which actuated separately by a corresponding electric motor, and which comprises, for each motor of each track formation unit, the following phases in circuit closed loop: record the operating speed of the motor using a speed transducer to generate an electrical signal of predetermined amplitude as a function of the speed thus i noted; comparing the amplitude of said signal thus generated with that of a reference signal of constant amplitude: the amplitude of said reference signal being known and predetermined as a function of the desired operating speed of the motor; note the difference between the amplitudes of the signals thus compared and convert the error signal which possibly derives therefrom into a signal whose frequency is variable in proportion to the amplitude of this error signal; supply an inverter circuit with the signal thus converted, so as to transform the DC voltage respective supply of an alternating voltage of predetermined value and frequency as a function of the amplitude of the error detected; control the motor with the output signal of said inverter circuit, so as to adjust, that is to say, instantly adapt, automatically, the respective operational speed to that of work, constant, predetermined.

The advantages obtained thanks to the present invention essentially consist in the fact that it is possible to achieve a high production of very high and constant quality chenille yarn, automatically, reliably and economically; in that it is possible to control at any time, the output speed of each motor member of the machine, and thus the quality of the wire produced; in that it is possible to regulate with extreme simplicity and speed the operating conditions of each unit for forming the chenille yarn, even individually or in predetermined groups, depending on the variation in the nature, conditions and characteristics of the wires used.

These advantages and characteristics of the present invention as well as others will be more and better understood by each person skilled in the art in the light of the description which follows and with the aid of the appended drawings given by way of practical example of the invention, but not to be considered in the limiting sense; drawings in which: Fig. 1 shows the partial and schematic side view of a machine for chenille yarn, in which is shown a unit for forming the chenille yarn, with three motors; Fig. 2 shows the functional block diagram of a circuit for implementing the process for the production of chenille yarn according to the invention, applicable to the machine of FIG. 1.

• relever la vitesse instantanée du moteur au moyen d'un transducteur de vitesse (T) correspondant pour générer un signal électrique (ST) d'amplitude prédéterminée en fonction de la vitesse ainsi relevée;
• comparer l'amplitude dudit signal ainsi généré avec celle d'un signal de référence (R) d'amplitude constante: l'amplitude dudit signal de référence étant connue et prédéterminée en fonction de la vitesse de fonctionnement désirée du moteur;
• relever la différence entre les amplitudes des signaux (ST, R) ainsi comparés et convertir le signal d'erreur (E) qui en dérive éventuellement en un signal dont la fréquence est variable proportionnellement à l'amplitude de ce signal d'erreur (E);
• alimenter un circuit onduleur (I) avec le signal (C) ainsi converti, de manière à transformer la tension continue respective d'alimentation en une tension alternative de valeur et fréquence prédéterminées en fonction de l'amplitude de l'erreur (E) relevée;
• piloter le moteur avec le signal (U) de sortie dudit circuit onduleur, de manière à régler, c'est-à-dire adapter, instantanément, de manière automatique, la vitesse opérationnelle respective, c'est-à-dire instantanée, sur celle de travail, constante, prédéterminée.

Reduced to its essential structure and with reference to the figures of the accompanying drawings, a process for the production of chenille yarn in a machine with one or more groups for forming the yarn, in accordance with the invention, comprises, for each training unit, the winding and sizing phases of an effect yarn, cutting the effect yarn into sections of predetermined length, feeding two binding yarns and driving these yarns with the sections of the effect yarn and twisting the binding threads with the sections of the interposed effect thread, by means of stretching cylinders (4), a pair of driving cylinders (6) and a blade (7) driven by a first motor (1), d '' a spinning head (5) actuated by a second motor (2) and a spindle (8) with weft pre-deliverer (9) actuated by a third motor (3), and comprises, for each motor (1, 2 , 3) of each track formation unit (G), the following phases in circuit closed loop:

• read the instantaneous speed of the motor using a corresponding speed transducer (T) to generating an electrical signal (ST) of predetermined amplitude as a function of the speed thus recorded;
• comparing the amplitude of said signal thus generated with that of a reference signal (R) of constant amplitude: the amplitude of said reference signal being known and predetermined as a function of the desired operating speed of the motor;
• note the difference between the amplitudes of the signals (ST, R) thus compared and convert the error signal (E) which possibly derives therefrom into a signal whose frequency is variable in proportion to the amplitude of this error signal (E );
• supply an inverter circuit (I) with the signal (C) thus converted, so as to transform the respective direct supply voltage into an alternating voltage of predetermined value and frequency as a function of the magnitude of the error (E) noted ;
• control the motor with the output signal (U) of said inverter circuit, so as to adjust, that is to say, instantly, automatically, adapt the respective operational speed, that is to say instantaneous, to that of work, constant, predetermined.

Advantageously, in accordance with the invention and with reference to FIG. 2 of the accompanying drawings, provision is made to amplify the sensor output signal (ST) (T) before comparing it with the known and constant reference (R).

Advantageously, it is also planned to amplify said error signal (E) before carrying out its frequency conversion.

Furthermore, advantageously and with reference to FIG. 2 of the accompanying drawings, in accordance with the invention, it is intended to send said signal (C) transformed into frequency to a control circuit of the PWM type upstream of the inverter circuit (I), to allow the value of the output voltage by varying the conduction and interruption intervals of the respective switching means (T1, T2, T3, T4, T5, T6).

The regularity of operation thus ensured for the different motors (1, 2, 3) of each unit (G) of wire formation allows the production of chenille wire of high and regular quality and constantly having the same structural characteristics. This allows, in the successive stages of wire processing, to obtain manufactured products of optimum quality.

• pour la transduction de la vitesse de sortie de chaque moteur, un inducteur de proximité inductif du type "pick-up", destiné à générer des impulsions de fréquence variable en fonction de la vitesse de sortie du moteur (M) correspondant et disposé sur l'axe dudit moteur. En aval du transducteur, il est possible de disposer un convertisseur D/A pour permettre la comparaison successive avec le signal de référence (R). Il va de soi qu'à la place du transducteur décrit, il est possible de prévoir n'importe quel transducteur de vitesse adapté à cette fonction, comme par exemple une dynamo tachymétrique ou un encodeur;
• pour générer le signal de référence (R), un circuit résistif, avec un potentiomètre de réglage, alimenté de façon appropriée, de manière à fournir, en sortie, un signal de tension prédéterminée, constante et correspondant à la vitesse de sortie désirée du moteur (M) correspondant;
• pour comparer le signal de référence (R) et le signal (ST) généré par le transducteur (T), un amplificateur différentiel dont la tension de sortie dépend de la différence entre celles du signal (R) et du signal (ST) respectivement.

Le circuit onduleur (I) est constitué par un groupe onduleur statique.For the practical implementation of the procedure described above, it is possible to use:

• for the transduction of the output speed of each motor, an inductive proximity inductor of the "pick-up" type, intended to generate pulses of variable frequency as a function of the output speed of the corresponding motor (M) and arranged on the axis of said motor. Downstream of the transducer, it is possible to have a D / A converter for allow the successive comparison with the reference signal (R). It goes without saying that instead of the transducer described, it is possible to provide any speed transducer adapted to this function, such as for example a tachometric dynamo or an encoder;
• to generate the reference signal (R), a resistive circuit, with an adjustment potentiometer, supplied in an appropriate manner, so as to provide, at output, a signal of predetermined voltage, constant and corresponding to the desired output speed of the motor (M) corresponding;
• to compare the reference signal (R) and the signal (ST) generated by the transducer (T), a differential amplifier whose output voltage depends on the difference between those of the signal (R) and the signal (ST) respectively.

The inverter circuit (I) consists of a static inverter group.

Claims (4)

1) Process for the production of chenille yarn in a machine with one or more groups for forming the yarn, comprising, for each of said groups, the phases of winding and dimensioning of an effect yarn, of cutting the yarn effect in sections of predetermined length, supplying two tying threads and driving these threads with the sections of the effect thread and twisting the tying threads with the sections of the effect thread interposed by means of cylinders stretchers (4), a pair of driving cylinders (6) and a blade (7) driven by a first motor (1), a spinning head (5) actuated by a second motor (2) and a spindle (8) with weft pre-deliverer (9) actuated by a third motor (3), characterized in that it comprises, for each motor (1, 2, 3) of each unit or group (G) of track formation , the following phases in a closed loop circuit: - reading the instantaneous speed of the motor by means of a corresponding speed transducer (T) to generate an electrical signal (ST) of predetermined amplitude as a function of the speed thus recorded; comparing the amplitude of said signal thus generated with that of a reference signal (R) of constant amplitude: the amplitude of said reference signal being known and predetermined as a function of the desired operating speed of the motor; - note the difference between the amplitudes of the signals (ST, R) thus compared and convert the error signal (E) which possibly derives therefrom into a signal whose frequency is variable in proportion to the amplitude of this error signal ( E); - supply an inverter circuit (I) with the signal (C) thus converted, so as to transform the respective direct supply voltage into an alternating voltage of predetermined value and frequency as a function of the magnitude of the error (E) noted; - control the motor with the signal (U) output from said inverter circuit, so as to adjust, that is to say, instantly, automatically, adjust the respective operational speed, that is to say instantaneous, on that of work, constant, predetermined. 2) Method according to claim 1, characterized in that it comprises the amplification of the signal (ST) output from the sensor (T) before its comparison with that known and constant reference (R). 3) Method according to claim 1, characterized in that it comprises the amplification of said error signal (E) before carrying out its frequency transformation. 4) Method according to claim 1, characterized in that it comprises the transmission of said signal (C) transformed into frequency to a control circuit of the PWM type upstream of the inverter circuit (I), to allow the value of the voltage to be varied output by varying the conduction intervals and interruption of the respective switching means (T1, T2, T3, T4, T5, T6).

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