Positive control device for a yarn brake

The present invention relates to a device for positive control yarn brake for any type of ' textile machine as looms, spoolers...

Are already known many types of thread brakes, the braking effect whereof is adjustable depending on the nature of the wire worked, such as that described in the request 2,486 048 the same holder.

In this example, two blades The spring bear against each other for a part of their length, the variation of the braking effect is obtained by increasing or decreasing the pressure in the contact area of the two blades using a lever system.

It can be said that such a brake is continuous because after adjustment, 1' braking effect remains constant regardless of the yarn tension variations worked. Continuous Such a brake is abrupt, slightly modifies the:

yarn structure if it is fragile, and does not allow suppress variations of tension of the wire.

According to the invention, therefore is already known brakes provided with a control system for automatically varying the braking effect in time, it is the positively controlled brakes or positive brakes.

Typically, the positive brakes are controlled by mechanical means such as those shown schematically in Figure 3. A cam to sectors (b) mounted on the main shaft (a) of the machine, for example to a weaving loom, conduit the movement of a roller (f); the movement of the cam (f) is transmitted by a mechanical assembly of general reference (d) a movable blade (e) of a brake.

The mechanical assembly (d) can include any type of linkage and displacement multiplier (c) to the scope of the person skilled in the art, for transmitting linearly movement of the roller (f) to the movable blade (e).

On the other hand, the cam (b) comprises as many active sectors that periods of braking desired.

The main disadvantages of such a system are numerous:

-large number of parts thus many games and delicate settings

-delicate adjustment of the sectors of the cam and periods of braking is to be done by a specialist

The present invention addresses this by providing all disadvantages of the prior art. This is achieved, according to the invention, by a device for positive yarn brake of the type comprising a control system for the braking members, characterized in that said control system is electromagnetic means positioning, more particularly that of a speaker or the operative equivalent whose element motor is the movable member.

To transmit motion from the movable member to the braking member, is secured a rod substantially at the center of the movable member, facing toward the outside of the speaker and perpendicular to the surface on which it is secured.

The device according to the invention further comprises a system electronic control, advantageously micro-processor for driving the loudspeaker or the like by means of electric signals of any shape and any frequency adaptable to the requirements of the textile machine on which is mounted the device positive brake control.

With such an arrangement, the law of motion of the free end of the rod is the same as the law of motion the fastening point at the the movable member therefore in a report ' constant with the control law displayed to the input of the speaker.

It will be appreciated better the invention with the aid of the description hereinafter made with reference to the drawings appended to which;

Figure 1 is a block diagram showing an application of the invention to the control of a brake frame rapier weaving machine.

Figure 2 shows the control system and the control system for the brake of Figure 1.

Figure 3 is a sketch showing the principle of a mechanical control system for positive brake.

Figure 4 is a sketch showing the principle control loudspeaker according to the invention.

Figure 5 is a voltage curve of the weft thread measured at the output of a pressure, thus in the absence of driving.

Figure 6 is an outline of larger scale detail of the braking members and their settings.

Figure 7 shows a speaker adapted to drive a plurality of brakes.

Figures 8 and 9 show two examples of piloting curve.

As a non-limiting example hereinafter demanderessedécrit the use of the invention on a rapier weaving machine, this is represented schematically in Figure 1.

According to the known arrangement of lances: a wire (2) extract of a coil (1.) is called by a yarn feeder (3) passes through a multi-disc brake (5) avoiding the formation of tendrils, loop, , and another brake (4), (6) a weft stop motion, presentation means general reference (7) and a cutter (8); on the other hand a lance input (10) engages the wire (2) and introduced into the shed (9).

The means of presentation and the principle of the exchange of the frame between the lance a lance input and output (not shown) are known and are important in determining the tension of the weft yarn.

The weaving machine of this type operates according to cycles which are defined angularly 0° to 360° relative S the crankshaft of the machine and that each correspond to the insertion of a weft.

The shot comb corresponds to the value 0 °, the frame grabber substantially corresponds to the angle value 45 °, the exchange substantially to the value 180 °, and the output frame 360° or less in the délaizage.

Figure 5 represents the course weft tension measured during a cycle of the machine, to the output of a non-controlled brake (4), (performed on a rapier weaving machine).

Two peaks are observed more particularly large amplitudes (A) (A ') due to the acceleration d® lances and two minima amplitudes (B) (B') which are the minimum voltage corresponding to the voltages exchange and taking the frame by the lances y for that it must be ensured that these two operations are carried out correctly.

To reduce the risk of breaking the wire is therefore advantageously reduce the minimum amplitudes (A) (A')to obtain a voltage curve the most uniform possible, or the closest possible to a constant corresponding to a predetermined voltage value and necessary to the correct operation of the machine.

Another interest for regularizing the frame voltage is to improve the regularity of the fabric and its quality.

All these aims are accomplished by driving the thread brake (4) by a predetermined piloting curve, generated by a microprocessor (15), and transferred to the brake element by electromagnetic means positioning (11), see in Figure 2.

A positive brake (4') includes a fixed blade (17) and a movable blade (18), the movable blade (18) is moved by means of one end of a rod (12), the other end of the rod (12) being integral with a mobile element (19), a speaker (11), said speaker (11) receiving the electrical signals generated by a microprocessor (15) or any suitable electronic mounting.

The rod (12) can, for example, be threaded on one of its end at least, then secured substantially at the center (13) of the movable member (19) by means of a nut.

The rod is guided during its movement into translation by any guide system (14) suitable e.g. a tube fixed to the housing of the loudspeaker (II).

Figure 6 represents in detail the structure of the positive brake used.

A blade (17) received in a holder (20) is tensioned by a spring (21), the spring (21) is, for example, as on the fig-(6) mounted parallel to the blade (17) by a deflection (22), the tension of the spring (21) is adjusted by a screw system (23) conventional, for adjusting the flexibility of the blade at a predetermined value.

A blade (18) is rotatable, at one of its ends, about an axis (24), the other end of the blade receiving the control movement by means of the end (30) of the rod (12).

The weft yarn (2) passes between two blades (17) (18) which are

for example by cortact only over part of the length.

A spring return (25) is tensioned by example between the support (20) and an extension (26) of the rotation guide (27) of the blade about the axis (see Figure 6).

To operate the device it is sufficient to program the microprocessor to generate a piloting curve predetermined.

In 1*application at rapier weaving machine, the movement

of the shaft (12) must open a brake (4¹ ) during acceleration and close the said brake (4^T ) during the presentation, of the exchange, and the output.

A first example of piloting curve representing intensity of the signal (I) pilot cycle of the loom is represented in Figure 9. The speaker (11) receives signals in the form of castellations of suitable magnitude to the type of speaker used.

By way of example, the selected program of the microprocessor is such that the rod (12) supported on the blade (18) at the beginning of each cycle up to around 40 °, during exchange of from about 165° to 195 °, for example in wire exit from 240° or 315° according to the délaizage , and continuously up at the beginning of the next cycle.

A second example piloting curve is represented in Figure 9.

The curve continuous controlling generated by the microprocessor (15) has a substantially symmetric shape that of the figure 5 such that movement of the shaft is driven along the cycles of the loom in the closing direction when the voltage of the wire decreases and in the opening direction when the voltage of the wire increases i.e. to control said thread tension for that it approaches in all times a substantially constant value (C), (see Figure 9).

It can well heard integrating the microprocessor to a central computer machine control, and providing a plurality of control curves. In this case the adjustment, based on the délaizage , is obtained immediately by pressing keys of a keyboard control, and without requiring the intervention of a specialist.

By comparing Figures 3 and 4, the simplification provided by

the device according to the invention appears obvious.

Of course, the same electromagnetic means may be a positioning adapted to simultaneously controlling more brakes, multicolor for machines for example.

Figure 7 shows the means (11), its control rod (12) translatable secured to the center of the movable element (19) and suitably connected to a guide (28) mounted for rotation about an axis (31).

The guide (28) has an extension (29) or block carrying as many fingers (30') as freihs to drive. The respective positions and the dimensions of the blocks (29), fingers (30'), rod (12) will be selected according to the space requirements on the loom.

Finally, whereby the brake is satisfactory even for high speeds insertion, for example 900 m/min or 1200 m/min, it is possible to adjust the voltage of the upper blade (17) by means of the screw (23) so that the resonant frequency of the brake is greater than the frequency of the pulses received by the said brake.

The advantages of the device according to the invention are many:

-reducing the number of parts and game

-simplify assembly and settings

-ability to steer the engine by any electrical signals adaptable to problems of the machine on which is mounted the brake (frames, other type of loom...)

response time low-

-good performance even at high speed.

Of course may also be built from the device of Figure 2, a true regulating voltage in frame by sending to the microprocessor (15), the signals emitted by a voltage sensor provided upstream of the brake controlled (4 '), between the said brake (4') the prëdélivreur and (3).