GB2255839A - Drive motor control. - Google Patents

Description

1 2 2 5) 5 j -),? A METHOD OF AND SYSTEM FOR REGULATING A WARP BEAM DRIVE

OF A TEXTILE MACHINE The present invizantion relates to a method of and a system for regulating a drive motor for driving a warp beam of a textile machine, particularly a warp knitting loom or a power weaving loom.

In DE 39 35 205, a warp beam of a textile machine is driven by means of a regulatable motor. The motor is controlled in such a manner that the warp beam releases for each revolution of the main shaft of the machine a predetermined length of thread for processing. The inevitable irregularities sudden pattern changes as which arise in Darticular with a result of the inertia of the drive are taken up by an additional thread intermediate store. Associated with this thread intermediate store are at least two sensors which feed signals to a regulator for the motor. The regulator operates on the principle of the so-far generally known two-Dosition controllers. This tyPe of regulator suffers from the drawback that when the regulator is triggered as a result of the switching in of a higher basic voltage the drive is accelerated relatively quickly in such a way that the thread intermediate store activates the sensor in the other limiting position and the drive is then subjected dr '. or 2 to de-acceleration. This is a drawback since there is then 'hunting' with constant acceleration and retardation chanaes and much energy is consumed.

In addition, deflection of as a consequence of the different the thread intermediate store which is usually spring loaded, the tension in the thread is modified in the warp thread assemblage. This leads to differences in the working-in of the threads and in the surface weiahts of the textile surface structure thus produced.

To avoid this drawback attempts have been made on the one hand at reducing to the extreme the mass and the friction of the thread intermediate store, and at usina loading means which, over a relatively great movement of the thread intermediate store, subjects the thread assemblage to a low force which remains constant. The special loading means - particularly membrane pistons require, however. the introduction of an additional energy system of the machine. This makes the manufacture and the maintenance of this machine more costlv.

By means of special circuit elements it has been attempted to influence the regulation time constant and to promote the damping of these regulation fluctuations. As a result however, the known regulators became expensive, and they are then orientated towards a 3 specific operational condition - for example a specific working rotational speed. The use of analogue regulators could reduce these drawbacks further, but they could not be eliminated. For this reason and in the manufacture of warp knitting looms in particular, it was sought to determine a control program orientated towards the thread length to be processed, see DE 31 11 112. Incursions into the program are made only when extreme deviations occur. Otherwise, the operator relies upon the fact that in the region of the place of thread looping, elastic elements are present which absorb the thread length differences in the course of processing. However, this is not possible where thread processing elements are provided which have practically no elasticity. This is the case, in particular, when using pile sinkers.

The aim of the invention is to provide improved regulation of the drive so as to rule out as far as possible the differences in the working-in of threads and to avoid variations of the surface weight. In this connection, independently of the elasticity of the elements participating in the process, it is intended to secure constantly uniform favourable working conditions.

The invention seeks to structure the regulation process in such a manner that, on the one hand, extreme differences between the thread length supplied and 4 processed have no effect on the thread tensions before the processing point, and that the optimum feeding conditions can be reached again quickly and free from oscillations. The equipment should nevertheless remain simple and damage should be precluded with a high degree of reliability.

\ 0 In accordance with the invention a drive motor for a warp beam of a textile machine is controlled or regulated bv at least one program which involves the superimposition of a waveform, for example a rectanaular waveform, on a basic voltage to increase or decrease the basic voltage in steps for predetermined time intervals.

Accordina to one aspect of the invention there is provided a method of regulating a drive motor for driving a warp beam in a textile machine, particularly a warp knitting machines or a weaving machine, by initiatina an acceleration or braking program in dependence on the thread movement detected by engagement with contacts, wherein the acceleration program adds to a basic drive voltage U an additional voltage Uz of about 0.3 to 0.7 U for a-presettable time tl, the basic voltage U is raised stepwise by an amount Us of about 0.002 to 0.006 U, and the braking program subtracts from the basic voltage U, a voltage UB of some 0.3 to 0.7 U over a Dreset time t2.

In another aspect the invention provides a system f or the regulation of the drive speed of a motor driving a warp beam of a textile machine comprising storage means storing an acceleration and a braking program and contact means for establishing contact with a contract element which moves in accordance with thread motion to initiate the braking or acceleration Drogram; wherein the acceleration Program adds to a basic voltage U a first constant additional voltage Uz which is about 0.2 to 0. 7 U for a constant reaulatable time tl, and increases the basic voltage U after each correction Process stepwise by an amount of about 0.002 to 0. 005 U and, the braking program subtracts from the basic voltage U a second constant voltage UB which is about 0.2 to 0.07 U for a constant,regulatable time t2.

The control functions set off on reachina the limitina positions of a thread intermediate store may now be structured according to cases. The thread intermediate store remains over a relatively long period vibrationfree in the optimum position. Also, when extreme differences between supplied and processed thread length arise, the optimum thread intermediate store position is again reached after a rapid sequence of regulation processes.

It is preferable that the basic voltage U after . IL Oh 6 correction has been made, is reduced stepwise by an additional voltage Us'' in the braking program This feature is very appropriate when on the loom it is necessary to work with warp beams having fairly large deviations one from the other in their initial winding diameters.

Various control parameters which have proved to be particularly worth while on warp knitting looms are set forth hereinafter.

The regulating system is easily incorporated with standard textile machines. On textile machines which as is usual nowadays - have electric controls, it is appropriate to associate the acceleration and braking programs with the constructional units available there. As a rule, the available storage space is sufficient for storing and utilizing these control programs in microprocessors.

The correction programs for each limiting position require respectively only one setting off pulse and this makes it possible -for a thread jack or rocker arranged directly in front of the looping elements, which compensate the tension differences occurring during the looping cycles, to initiate also the necessary pulse for the regulation of the thread supply. For this purpose, the contact means can be disposed at the limiting 7 positions.

An additional thread intermediate store with great storage capability is then necessary only for those thread systems for which considerable sudden alterations of thread usage are technologically demanded. For example, this is the case with pile thread systems which in pile free areas in the basic material are incorporated only as a permanent weft.

The invention will be described hereinafter in greater detail on the basis of examples of embodiments. In the accompanying drawings:- Figure 1 is a diagrammatic representation of the working elements of a warp thread supply of a warp knitting loom, employing a regulation system in accordance with the invention; Figure 2 is a voltage-time graphical representation of the acceleration and braking program depending upon pulses provided by the sensors associated with the thread intermediate store; and Figure 3 is a -diagrammatic representation of the working elements of a modified warp thread supply avoiding the use of an additional thread intermediate store.

The basic machine in accordance with the example of 8 embodiment is a warp knitting loom based on crochet galloon technological principles. It is used in particular for the production of "terry-type" pile fabrics. As shown in Figure 1, a group of warp threads 1 is supplied from a driven warp beam 8 to processing elements 2 via a thread jack or rocker 3 and a thread intermediate store 4.

the threads 1 taut.

The rocker 3 serves to maintain The thread intermediate store 4 consists of a stationery thread guide element 40 in the form of a roll and a movable thread guide element 45. The movable thread guide element 45 is mounted on a support lever 41. The loading of the support lever 41 is effected by means of a pivotally connected loading lever 42 on which there is engaged a stationarily suspended spring 43.

Part of the loading lever 42 f orms a contact element 421 which can cooperate with stationary contacts 51 and 52 which act as sensors. The contacts 51 and 52 are connected by means of leads 53 and 54 with program stores 55 and 56. The program store 55 contains an acceleration program and the program store 56 a braking program. If bne of the program stores 55,56 is activated through its respective contacts 51,52, the stored program is processed as control commands by a processing unit 57. The unit 57 controls a motor 7 which drives the warp beam 8 through a digital to analogue converter 58 and an amplifier 59. The motor 9 7 is connected to the beam 8 through a step-up gear 71.

The manner of operation of this regulation system for the supply of warp threads will be explained in conjunction with Figure 2, which is a voltage-time diagram with the pulse waveforms 511 and 521, associated with the contacts 51, 52 respectively.

If the thread intermediate store 4 with its movable thread guide element 45 is in a position in which the smallest thread length is stored, the contact element 421 of the loading lever 42 engages the contact 51. The pulse waveforms thus generated is designated 511 in Figure 2.

If the thread guide element 45 of the thread intermediate store 4 is in a position in which the largest reserve of thread is stored, the contact element 421 of the loading lever 42 engages the contact 52. The pulse waveform thus generated is designated 521 in Figure 2.

Each rising flank of a pulse in the waveforms 521, 511 initiates the respectively associated programs of the program stores 55 and 56. The acceleration program 55 which is set off by the contact 51 and the waveform 511 consists of a rectangular pulse the amplitude Uz of which is superimposed on a basic voltage U of the regulator.

Uz is about 50% of U The active time tl of this rectangular pulse may be, for example, 50 milliseconds. After this Deriod tl has exDired the voltage returns to a voltaae Us which is about 0.4 percent higher than the original basic voltage U. The new basic voltage U + Us now reached is the output voltage for the next regulation process triggered by the rising flank of the next DUlse of waveforms 11. The time-restricted increase of the voltage U by 50% to Uz is an empirical value and certainlv has onlv an exemDlification character. It is quite possible to apply this amplitude in other ratios e.g. between 30 and 70% of output voltage U.

Both parameters, aMD1itude and duration must be suitable for accelerating the warp beam 8 in such a way that the movable thread guide element 45 assumes a DOSition which can be held over a relatively long time Deriod. The position to be aimed at is one in which the contact element 421 is situated close the contact 51. The return of the regulation pulse to a basic voltage raised stepwise is intended to reduce the number of the regulation processes altogether.. It is thereby the aim to adapt this level of basic voltage inversely proportionally to substantially the reducing warp beam diameter. It will normally be the case that a correction is used only with an acceleration program of the program store 55. However, it may also happen that on the setting up of a new warp beam, or when working on 11 pile free areas, the braking program has to be applied. In principle, the braking program is equivalent to the acceleration program where the rising flank of the pulse in waveform 521 triggers braking. The difference lies purely in the fact that the voltage, U + Us is reduced bv means of a negative rectangular Dulse UB with an aMD1itude of about minus 50% of U + Us for a predetermined time t2.

In a further cycle the acceleration and braking programs are shown in Figure 2 at a higher level with the equivalent voltages signified by primes - Uz', UB1. In this case the application of the negative Pulse UB' causes a reduction by Us' I in the basic voltage which become U' - Us''.

It is possible to associate as desired in time terms, a negative or positive grading (Us, Us'') of the basic voltage depending on the respective setting up of the programs.

It is also possible to provide different acceleration and braking programs in each of the program store 55, 56. For the selection of the respective programs further contacts can be provided in addition to the two contacts 51 or 52. Thus, for example, the program selected by the contact 51 can be made dependent upon a rotational sDeed sianal of the main shaft which distinguishes 12 1 1 fa between operational rotational SDeed and creep. With resnect to the contact 52 and the braking program selected thereby it would be appropriate to differentiate whether the normal 0Derational state or the new work off the warD beam has started. Here, a manually 0Derated switch, or a time switch which senses from the time of the application of the new warp beam, can take over the selection function for the program.

With thread systems in which the thread consumption is not subjected to any great jumps, as, e.g. with a knitting thread or a weft thread incorporated into the background of the material the additional thread intermediate store 4 may be dispensed with. In this case, depicted in Figure 3 the contacts 51,52, would have to be associated with the thread rocker 3, which maintains the thread tension during the looping cycle. If the movement play of the thread rocker 3 migrates into the range of one of the contacts 51,52 the first pulse or one of the following pulses depending on the presetting - will set off the acceleration or braking program, and the motor 7 will be set to the new drive parameter for the drive of the warp beam 8.

All further processes will correspond to those which were described with respect to the thread intermediate store 4. If this regulation is considered quite apart from the rest it will be seen that there is a pure thread 13 tension regulation. Practice has shown that with this thread tension regulation a greater regularity of surface weight of the textile product manufactured is obtained, as this makes thread-length controlled systems possible.

A further advantage consists in that the thread tension, before the processing elements, can be set to the technologically optimum level, and held there with a high degree of reliability.

The number of thread breaks can, also with very sensitive yarns - e.a. with cotton yarns spun according to the open-ended principle, be reduced verv considerablv.

On the setting-up of a new warp beam 8 it will be possible as a rule to dispense with the input of the starting diameter if the diameter can be secured within specific, quite coarse limits. If a warD beam 8 can be set with a very small initial diameter, it will be appropriate to-input over the program the parameters suited for the purpose. The regulation process can then begin in the normal way.

The principle of the regulation is analogous to an onand-off regulator but when a definite regulation deviation occurs, the value to be regulated is returned to the optimum position according to the presettable 14 permanent control program.

In this control program machine-specific parameters can also be considered and additional damDina elements in the regulation system are not necessary.

W p 1 is

Claims (11)

1. A method of regulating a drive motor for driving a warp beam in a textile machine, particularly a warp knitting machines or a weaving machine, by initiating an acceleration or braking program in dependence on the thread movement detected by engagement with contacts, wherein the acceleration program adds to a basic drive voltage U an additional voltage Uz of about 0.3 to 0.7 U for a presettable time tl, the basic voltage U is raised stepwise by an amount Us of about 0.002 to 0.006 U, and the braking program subtracts from the basic voltage U, a voltage UB of some 0.3 to 0.7 U over a preset time t2.

2. A method according to claim 1, wherein the basic voltage U after correction has been made, is reduced stepwise by an additional voltage Us' ' in the braking program

3. A method according to claim 1 or 2, wherein the time of effect tI, t2 of the additional voltage Uz, UB is settable and preferably to about 50 milliseconds.

4. A method according to any one of claims 1 to 3 wherein the additional voltage Uz, UB is about 50% of the basic voltage U before each correction process.

5. A method according to any one of claims 1 to 4 wherein the value of the step to the new basic voltage after each correction is approximately 0.004 of the original valve U + Us or U' + Us''.

16 0

6. A method of regulation substantially as described with ref erence to anv one or more of the Fiaures of the accompanying drawings.

7. A system for the regulation of the drive speed of a motor drivina a warD beam of a textile machine comprising storage means storing an acceleration and a brakina Droaram and contact means for establishina contact with a contract element which moves in accordance with thread motion to initiate the braking or acceleration program; wherein the acceleration program adds to a basic voltage U a first constant additional voltaae Uz which is about 0.2 to 0.7 U for a constant reaulatable time tl, and increases the basic voltaae U after each correction process steDwise by an amount of about 0.002.to0.005 U and, the braking program subtracts from the basic voltage U a second constant voltage UB which is about 0.2 to 0.07 U for a constant regulatable time t2.

8. A regulation system according to claim 7 wherein the acceleration program and the braking program are each stored in a microprocessor the input of which is electrically connected with pulse generators initiated by the contact means and the output of which leads through a diaital to analoaue converter and an amplifier to the motor.

9. A regulation system according to claim 7 and 8 wherein the DU1Se generators and contact means are 17 associated with a thread rocker directlv mounted uDstream of thread processing elements.

10. A regulation system substantially as described with reference to, and as illustrated in any one or more of the Figures of the accompanying drawings.

11. A textile machine employing a regulation system or method in accordance with any one of the preceding claims.