CH654555A5 - ELECTROMAGNETIC BRAKING DEVICE WITH ELECTRONICALLY CONTROLLED ROTATION TORQUE. - Google Patents

Description

The present invention relates to an electromagnetic braking device with electrically controlled torque. It very advantageously applies to all types of winders (metallic threads in general, textile fibers, paper, etc.) and makes it possible to program the tension of the thread to be wound and in particular to keep this tension constant in all phases of the winding , by varying the number of turns and the dimensions of the coil cores. The devices known up to now are essentially of the mechanical type and have the defect of changing their braking characteristics according to the temperature and the humidity. In addition, they fail to keep the thread tension constant enough in the acceleration and deceleration phases. These drawbacks do not make it possible to increase the working speed beyond certain limits. This invention, on the other hand, makes it possible to adjust the thread tension with remarkable consistency because it is independent of ambient factors, and the possibility - by electronic control - of optimally adjusting the thread tension during the acceleration and deceleration. These advantages make it possible to increase the working speed well beyond the 50% of what can be obtained with traditional devices.

This device includes the features listed in claim 1.

The attached drawing illustrates schematically and by way of example an embodiment of the device according to the invention.

Figs. la and 1b illustrate in front and rear view an actuating device.

Fig. 2 is a block diagram.

Fig. 3 is a detail of the electronic circuit with sensors.

Fig. 4 is a tachometric diagram with reader blocks.

The actuating device illustrated in FIG. 1 comprises a main support indicated by 1, a compensating arm 2, a calibrated spring 3 of the arm 2, a pulley 4 fixed to the arm 2 which gives tension to the wire, idler pulleys 5 and 6, a shoe for cleaning the wire 7, a wire guide eyelet 8, an optical sensor 9 and a disc 10 crimped on the pulley 4 to provide information on the speed of rotation of the pulley 4 and an inductive sensor 11 and a ferromagnetic sensor 12, fixed to the arm 2 to give information on the position of the arm 2, an electromagnetic device 13 which supplies the braking torque of the pulley 4, an electronic control circuit 14, complement of the potentiometer 15 for adjusting the mechanical tension according to the diameter of the wire to roll up.

The operation of the device described is as follows:

The wire to be wound passes from its spool through the eyelet 8, the cleaning member 7, is wound on the return pulley 5, on the braking pulley 4, on the second return 6 and from there on the guide. - machine wire to be fixed on the core to be wound.

Depending on the diameter of the wire to be wound, two calibrations must be made:

1) adjust the spring tension 3

2) position the potentiometer 15.

If for any reason voltage variations occur during the winding (for example irregular shape of the core), two things are to be checked:

1) that the compensation arm 2 be lowered or raised if the thread tension increases or decreases;

2) that the pulley 4 slows down or accelerates if the thread tension increases or decreases.

The lowering of the arm 2 causes the ferromagnetic sector 12 which is attached to it to move, and consequently the sensor 11 will send a variable signal relating to the previous situation of the electronic control system. This is subdivided into four fundamental modules (fig. 2) operating as follows:

In the first module A, the voltage created by the inductive sensor 11 will be discriminated to obtain a linear variation proportional to the displacements of the axis. The second module B uses this signal from the sensor 11 as a modulation signal; this voltage makes it possible to obtain at the output of module B a variable continuous voltage between the minimum value and the maximum value required, by means of two control trimmers calibrated in phase. The minimum value gives a signal between 0 and 100%; with the maximum value, the signal is between 100 and 200%. The output signal of module B therefore makes possible a linear variation in percent from 0 to 200% referring to the voltage value of potentiometer 15. Thus, this signal functions as a modulating signal for the third module C which transmits to its output a voltage depending on the imposed voltage value, potentiometer 15, the percentage of the modulator signal supplied to the input. This voltage is then presented to the input of the fourth module D which is a voltage-current converter which regulates the current in the brake F, thus determining the final braking torque. This device can therefore instantly change the braking rotation torque of the pulley 4 in order to keep the thread tension constant, if this is the objective to be achieved. In particular, the signal S 1 (fig. 3) at the output of the inductive sensor 11 enters the operational amplifier OP 1 on which the potentiometer P 1 also acts and at the output, we will have a signal S 2 proportional to the displacement of the arm 2. This signal S 2 enters a voltage controlled amplifier OP 2 which, by adjusting the potentiometers P 2 and P 3 on which the field of action is located in percent, supplies the voltage controlled amplifiers OP 3 , OP 4, OP 5 a signal which is used to modulate the voltage of the potentiometer P 15. This voltage enters a voltage-current converter CVI which supplies the braking current.

Unlike the case described above, the electronic control circuit not only receives and compensates for the speed variations of the pulley 4, but it is able to vary the current applied to the braking torque in order to have a lower current in phase. acceleration, a stable current in normal operating phase and a larger current in deceleration phase.

For this purpose, the system (fig. 4) is then based on pulses produced by an encoder 10 mounted on the same axis as the pulley 4 to be checked. The frequency supplied by this disk 10 is 128 pulses per revolution and supplies a pulse generator G.

This frequency will be transformed by a frequency / voltage converter F / V 1 which has two distinct level scales: FS 1 for control up to the low frequency regime, that is to say with a low number of turns, and FS 2 for a wider control extending to the whole field of action. The first FS 1 conversion, therefore the finest, produces a signal called VA which enters a level D2 discriminator; this circuit selects, among the various voltage signals having different characteristics, only those used for operating the system; it supplies the qualification signal VA 1 to the control logic L which determines the value

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minimum intervention threshold adjustable from 0 to 2000 Hz. The second voltage, called VB, in turn enters a level discriminator D4 and a dV / dT branch circuit. The latter provides two voltages, V INC and V DEC, which indicate the tendency of the system to accelerate or decelerate. The task of the INC and DEC level discriminators is, on the contrary, to exclude interventions on current control at a threshold value which can be set by the operator, or in the control phase. All these voltage levels, appropriately discriminated, will be presented to the control logic L which, by developing the logic signals, will in turn produce four logic type signals with the following functions:

The first (NOR) supplies the nominal current to the system, the second (DEC) the current during the acceleration phase, the third (INC) the current during the deceleration phase and the fourth (INOR) determines the current during the start-up phase.

These four signals arrive on the analog multiplexer M, which in turn conveniently elaborates the adjustments made by means of four potentiometers:

P 1 stabilizes the starting rotation torque; 5 P 2 stabilizes the torque during acceleration;

P 3 stabilizes the torque during deceleration;

P 4 stabilizes the braking current and delivers a signal to the current generator 7 which converts these voltage signals into a current supplying the brake, and which determines the braking torque.

These descriptions refer to the particular case where a winding of the wire is sought with a constant tension. If a variable thread tension is desired due to given parameters or special rules, the sensor 11 must be replaced by an output signal from another electronic circuit, in order to develop the desired parameters, or else must be programmed with the required rules.

4 sheets of drawings

Claims (4)

654,555 1. Electromagnetic braking device with electrically controlled torque, characterized in that it comprises an electromagnetic brake, a compensation arm adjusted by mechanical means, electronic means for controlling the position of the compensation arm, all arranged so as to be able to brake a winding wire having a constant tension with a constant torque. 2. Device according to claim 1, characterized in that it further comprises a sensor for the speed of the brake wheel and an electronic control with the characteristic of being able to brake a wire to be wound of constant tension with a constant torque . 2 3. Device according to claim 1, characterized in that it comprises an analog circuit for braking a wire to be wound of variable voltage with a variable braking torque according to the information provided by the analog circuit. 4. Device according to claim 1, characterized in that it comprises an inductive sensor indicating the position of the compensation arm.