EP1498529A1 - method for operation of a fast running warp knitting machine - Google Patents

Abstract

In a process to operate a high-speed self-acting knitting machine, the machine drive absolute position is determined by an absolute position sensor linked to a control system. In the vent that the machine working speed exceeds a pre-determined threshold, the position of the drive unit is determined by incremental values. Prior to operation the position of the drive system is determined absolutely with the drive in stationary mode and the value is logged by the control system. Incremental values are logged by the control system only with the drive system in operation. On shut-down, the drive system absolute position is logged and recorded in a non-volatile memory device. The absolute position is logged using stored supporting energy.

Description

The invention relates to a method for operating a fast-running knitting machine with at least one Drive in which one has an absolute position of the drive determined with an absolute encoder and connected to a Control transfers.

The invention will be described below using the example of a warp knitting machine explained. In a warp knitting machine work different active elements together, for example Punches, guide needles, boards etc. The individual Active elements are in groups on ingots attached. By controlling the movement of the ingots knitwear can be produced. In earlier years were the movements of the individual active elements mechanically coupled together. A central drive for All knitting elements took place via the main shaft of the warp knitting machine. To tie the active elements are sometimes relatively complicated gear required. These transmissions limit the possibilities of pattern design and make it difficult to change patterns.

It has therefore been more recently, electrical To use drives. It is omitted in the Usually a mechanical coupling between different Active elements. For controlling the active elements Therefore, information is necessary where these Active elements are located. This information is obtained on easiest about the position of the drive. With "Position the drive "is not the place of attachment in the following the drive in the knitting machine meant, but the position of the output part of the drive or a mechanically connected element relative to a stationary part of the drive. If as a drive a rotary drive is used, then the position the drive opposite the angular position of the rotor the stator.

The position of the drive is used in a control. The drive controller used for this purpose controls the drive so that its position certain specifications follows.

In particular, when starting the warp knitting machine is the knowledge of the absolute position of the drive is indispensable. For this reason, one must absolute encoder use that determine the absolute position of the drive and report to the controller. This absolute Position is also determined and to the Control reported when the drive moves. This is at lower working speeds Warp knitting machine readily technically feasible. However, difficulties arise when the Working speed of the warp knitting machine greater becomes. In this case, the amount of transferring increases Data accordingly. This amount of data is indeed with the technical means available today to manage something. The machine is thereby relatively consuming.

The invention is based on the object, the control of moving parts when operating fast-running To improve knitting machines.

This object is achieved in a method of the aforementioned Art solved by that when crossing a predetermined working speed the position incrementally determined by the drive.

Once the knitting machine has a predetermined working speed exceeds, you leave the absolute value measurement and confines itself to the change of Position of the drive compared to a previously occupied Position to determine. This allows the amount significantly reduce the data to be transmitted. In many cases one will proceed in such a way that one transmits analog signals and one resolution in Then makes increments in the controller. There it stands the required "intelligence", ie the necessary Computing capacity, usually available anyway. The determination of increments by the controller has In addition, the advantage that you a much higher Resolution can achieve. For an absolute encoder is due to space only a certain number of positions available where actually one Evaluation can be done. If one increments from analog signals Determines the resolution by one Multiple, for example the factor 10 to 100 or more, increase. This will be a much more accurate position determination possible. The regulation of the drive This is considerably improved. Of course it is also possible, the generation of the increments in the absolute encoder so that at the output of the incremental Information in digital form available stands. In the simplest case one must then instead of one Value containing an absolute position of the drive and usually only displayable in several bytes, only one piece of information is transferred from one bit consists. This not only simplifies data transfer. Also, the evaluation by the controller will easier and can be realized faster. In addition, the reduction in the amount of information the advantage that reduces the susceptibility to interference becomes. If, for example, by external interference Data lost, then it only affects an increment. Such an increment corresponds for example, a distance of 1/100 mm. A corresponding Disturbance in the transmission of an absolute Position could, however, affect a larger adjustment. When transmitting analog signals from the Position encoder for control eliminates this problem anyway. This approach is currently preferred.

It is preferred that one at standstill of the drive the position is absolutely determined and the absolute value transmits to the controller and only increments evaluates when the drive is moving. In this case the predetermined working speed is zero. As soon as the working speed is greater, the Position of the drive, so for example the angular position a rotor to the stator, only incremental determined. Because one is determined by the at rest Absolute position can be, you have handy over the entire movement sequence of the drive the information necessary to control the drive to disposal.

Preferably, it is determined when stopping the drive the absolute position of the drive and places it in a non-volatile memory. This is attached each restart of the drive the information to Available where the drive stood during shutdown Has. With this information, the start can be essential better control.

It is preferred that one has a stored auxiliary energy used to determine the absolute position. Thus one secures oneself against disturbances, which by a Interruption of energy supply may occur. If for example due to a network outage or a other interruption the electrical energy to the operation the knitting machine is no longer available, You can rely on the auxiliary energy to the absolute Determine the position of the drive. The auxiliary energy can do this, for example, in a battery or an accumulator stored.

Preferably, one determines before a movement generation by the drive the current absolute position of the Drive, compares the current absolute position with the stored absolute position and leads under Taking into account a difference between the stored and the current absolute position a correction by. If you are the knitting machine for a particular Period shut down, for example, at a Business interruption at the end of a shift or over the weekend, then it is possible that the drive adjusted. In this case, the absolute position is correct when starting off with the stored absolute position. This could be unfavorable Cases lead to disturbances. To such disturbances too Avoid correcting the drive so that the risk of disturbances is low. Because the stored absolute Position is known, you can see the difference between the saved and the current position as Use criterion.

Preferably, one uses several drives, of which one controls a main shaft and one a guide bar, where one, if the current absolute position of the drive the guide bar does not match the stored absolute Position of the drive of the guide bar corresponds, the drive of the guide bar in the stored Position moves. In this case you put, so to speak restore the stored starting situation. This is a relatively simple measure to a trouble-free To ensure start-up.

It is preferred that, if the current absolute Position of the main shaft not with the stored absolute position of the main shaft, moves the drive of the guide bar to a position that corresponds to the current position of the main shaft. there Taking into account the fact that the main shaft in the rule has a preferred direction of rotation and the drive the main shaft is usually the strongest drive is in the knitting machine. So you do not to change the position of the main shaft, but one adjusts the absolute position of the guide bar to the current one absolute position of the main shaft. To every position the main shaft, more precisely to every position the drive of the main shaft, belongs to a position of Guide bar. This relationship is known. One can therefore track the guide bar of the main shaft. The Main shaft serves as a kind of "master", while the Drive the guide bar is used as a "slave".

Preferably, a cyclic absolute absolute value encoder is used and blocks the drive at standstill. A cyclic absolute absolute encoder distinguishes not between individual cycles, but he determined only the position of the drive in one cycle, for example the angular position of the rotor relative to the Stator. Whether it's the first, second, or nth Rotation is irrelevant here. such Absolute encoders are available at relatively low cost. They are sufficient to predict the position of the drive to determine the commissioning. If you go through the Blocking the drive at standstill prevents the position of the drive in such standstill phases is changed to a greater extent, then that is Use of a cyclic-absolute absolute value encoder also sufficient for the correction, after a comparison between a stored absolute position and a currently determined absolute position required is. The blocking does not have to be perfect be. Smaller movements of the drive are quite allowed. But these little movements transcend not a cycle. You do not have the drive in or block it on the drive itself. Because you have a shift prevent the driven by the drive active elements As a rule, if you want, the movement is also enough these elements, such as ingots, to block or to brake.

It is preferred that one at a difference between the current absolute position and the stored absolute position when correcting the position of the drive exceeds a cycle limit, if the difference is smaller than a predetermined proportion of Cycle is. So you do not necessarily go inside one Cycle to the stored value. For example can determine 100 absolute values per cycle and the stored position is 10 and the current one determined position at 90, then you will not correct the drive from 10 to 90 in the same cycle, but across a cycle boundary from 10 to 90 in the previous cycle.

It is preferred that this proportion is at most 49% is. So you can practically over half of the Correct cycle.

An absolute value transmitter is preferably used sin / cos encoder or a resolver. Both types of absolute value encoders are now available at reasonable cost offered in the market and are in a combination of Control device, drive and encoder as well as evaluation electronics good usable.

The invention will be described below with reference to a preferred embodiment in conjunction with the drawings. Herein shows the
only Fig. A warp knitting machine in a highly schematic and simplified representation.

A warp knitting machine 1 has a main shaft 2, which is rotationally driven in the direction of an arrow 3 becomes. To generate the rotational movement of the Main shaft 2, a drive 4 is provided, for example an electric motor via a coupling 5 with the main shaft 2 is connected.

The main shaft 2 is shown only schematically Coupling members 6 with a knitting needle bar 7 in conjunction. The needle bar carries a variety of Knitting needles 8 and is in the direction of a double arrow. 9 pivoted back and forth.

A guide bar 10 has a plurality of guide needles 11 on, in the position shown in Nadelgassen located between the knitting needles 8. The delivery cart 10 is connected to a drive 12, which is the guide bar 10 laterally in the direction of a double arrow 13th back and forth. In operation are now the movements the knitting needles 8 (pivoting movement) and the guide needles 11 (linear offset motion) so on each other agreed that a knitted fabric is formed. Naturally a knitting machine 1 will have further active elements, like slider boards, blanks or The like, which are also attached to bars can. Also, more than one guide bar may be present be. Each such barre can have its own drive or to the drive of another barre or the main shaft be coupled. For the sake of clarity However, the explanation is shown on the simplified example. A Transmission to multiple drives is for the expert but easily possible.

The two drives 4, 12 are as electric motors educated. Particularly suitable here are servomotors, For example, permanent magnet synchronous motors. But it is also possible asynchronous motors, To use DC motors or stepper motors, provided these engines have a positioning of the main shaft 2 or the guide bar 10 allow that is accurate enough.

In order to control the positioning, is a control device 14 is provided, which drives the drives 4, 12, for example, by impulses.

The drive 4 has an absolute value encoder 15 which an absolute position of the drive 4 determined. Under "absolute position" is the position of a moving one Elements in the drive 4 with respect to a stationary Element to understand, for example, the angular position a rotor opposite a stator. In the same Way, the drive 12 also has an absolute encoder 16, which determines the absolute position of the drive 12. The two absolute encoders 15, 16 can as be formed cyclic absolute absolute encoder i.e. they only generate an absolute value within one revolution of the drive. This is usually enough out. As absolute value encoder 15, 16 can be, for example use a sin / cos encoder or a resolver. It is of course possible, instead of cyclic-absolute Donors, also referred to as "single turn" donors are to use so-called "multi turn" boomers, which actually has a larger range of revolution determine the absolute position.

The absolute encoder 15 now reports the absolute position of the drive 4 of the main shaft 2 to the controller 14th The absolute position of the main shaft 2 can be out the position of the drive 4, more precisely that in it located moving part, determine. The representation the absolute position requires a relatively large amount of data, for example, several bytes. To illustrate this, a large data line 17 is shown, about the absolute position of the drive 4 to the Control device 14 can be transmitted.

Similarly, the absolute encoder 16 also reports via a data line 18, the absolute position to the Control device 14.

This data transmission is not critical, as long as enough Time is available. This is both at a standstill the main shaft 2 and at a standstill of the guide bar 10 without problems. Even with slower movements the main shaft 2 and the guide bar 10 arise with the transmission of the absolute position of guide bar drive 12 and main shaft drive 4 no problems.

It looks different when the warp knitting machine 1 with higher operating speeds to be operated.

In this case, you could still be the absolute Values over the data lines 17, 18 to the controller 14 transmitted. The effort for a transfer However, large amounts of data in a short time is considerably.

To work around this problem, use as soon as possible the drives 4, 12 have set in motion, no longer the absolute value of the position, but one determines the position of the drives 4, 12 incrementally. For this one no longer transmits binary coded information, So a digital signal, but analog signals, For example, sine and cosine signals of a sin / cos encoders, to the controller 14. To this illustrate, lines 19, 20 are shown. These lines 19, 20 do not have to physically exist. One can of course analog values physically transmitted over the same lines as absolute values the position. In the control device 14 These analog signals are then with a corresponding fast analog / digital converter evaluated to the Increments with high resolution to win, with which the further position determination is made.

To operate the warp knitting machine so, so long the drives 4, 12 no movement of the Main shaft 2 and the guide bar 10 generate the absolute Position of the drives 4, 12 fixed and transmits this absolute position to the control device 14th

As soon as the warp knitting machine 1 starts and the Actuators 4, 12 move, so the main shaft 2 and the Legebarre 10 drive, you switch and used no longer the values of the absolute positions, but only changes in the absolute positions, ie incremental values.

When the warp knitting machine 1 is stopped, it is by a conscious action of an operator or by a power failure, then one determines, as soon as the machine stands, the absolute positions of the main shaft drive 4 and the guide bar drive 12 and puts the absolute position of the main shaft drive 4 in one Memory 21 and the absolute position of the guide bar drive 12 in a memory 22 from. Both memories 21, 22 are not volatile, so can the stored Maintain information even if the energy supply fails. In case of failure of the supply energy, the positions to be able to determine is a battery 23, a capacitor or other energy storage provided the memories 21, 22 and the absolute value encoder 15, 16 supplied.

Once the warp knitting machine 1 stops, fall Brakes 24, 25, the main shaft 2 and the guide bar 10 prevent another move. smaller Movements, for example in the range of one millimeter or 3 °, are of course still possible. Major changes in the Position of the drives 4, 12 are prevented.

Before you start the machine again, set the absolute value encoder 15, 16 the current positions of the drives 4, 12 and compare them with those in the Save 21, 22 stored positions. If deviations result, one corrects the deviations following the procedure:

When the current position of the guide bar drive 12 does not match the saved position, then the guide bar drive 12 is actuated to the to reach stored position.

When the current position of the main shaft drive 4 does not match the saved position, then you leave the main shaft drive 4 in the current Position and actuates the guide bar drive 12th The guide bar drive 12 now moves the guide bar 10 in a position corresponding to the position of the Knitting needle 7, i. the main shaft 2 corresponds. Even from such a position is a commissioning possible. It is only important that the individual active elements have a predetermined association with each other.

For a cyclic-absolute absolute value encoder 15, 16 is it possible that in the downtime of the Machine 1, a movement of the main shaft drive. 4 or the guide bar drive 12 results, the one cycle limit exceeds. For example, if a cycle of the guide bar drive 12 divided into 100 steps is and you immediately after stopping the Machine has detected a position 10 later determined current position but is 90, then Will not you be able to drive the 12 gauge pulley drive from 90 to 90? same cycle back to 10, but from 90 to advance the current cycle to 10 in the next cycle. Such a cycle-crossing movement becomes one make as long as the difference to the stored value in the next or previous cycle is less than half of the cycle. Only if this difference is greater As half of the cycle, one gets a correction in the same cycle.

Claims (11)

Method for operating a high-speed knitting machine with at least one drive, in which one determines an absolute position of the drive with an absolute encoder and transmits to a controller, characterized in that it determines the position of the drive incrementally when a predetermined operating speed is exceeded. Method according to Claim 1, characterized in that, when the drive is at a standstill, the position is determined absolutely and the absolute value is transmitted to the controller and only increments are evaluated when the drive moves. A method according to claim 1 and 2, characterized in that one determines the absolute position of the drive when stopping the drive and stores in a non-volatile memory. Method according to Claim 3, characterized in that a stored auxiliary energy is used to determine the absolute position. Method according to Claim 3 or 4, characterized in that , before the movement is generated by the drive, the current absolute position of the drive is determined, the current absolute position is compared with the stored absolute position and, taking into account a difference between the stored and the current absolute position Correcting. A method according to claim 5, characterized in that one uses a plurality of drives, one of which controls a main shaft and a guide bar, wherein, if the current absolute position of the drive of the guide bar does not match the stored absolute position of the drive of the guide bar, the Drive the guide bar moved to the stored position. Method according to Claim 6, characterized in that , if the current absolute position of the main shaft does not coincide with the stored absolute position of the main shaft, the drive of the guide bar is moved to a position corresponding to the current position of the main shaft. Method according to one of claims 1 to 7, characterized in that one uses a cyclic-absolute absolute encoder and blocks the drive at a standstill. A method according to claim 8, characterized in that a difference between the current absolute position and the stored absolute position in the correction of the position of the drive exceeds a cycle limit when the difference is smaller than a predetermined portion of the cycle. A method according to claim 9, characterized in that this proportion is at most 49%. Method according to one of Claims 1 to 10, characterized in that a sin / cos encoder or a resolver is used as the absolute value encoder.

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