Starting Method for a Weaving Machine

Abstract

The invention relates to a method for the controlled run-up of a weaving and shedding machine, wherein the weaving and the shedding machine are connected with a controller, wherein the weaving machine is driven by means of a main drive, wherein the shedding machine is driven by means of an electric motor auxiliary drive, wherein the weaving and the shedding machine are connected by means of a common converter intermediate circuit for the energy flow transmission, wherein the shedding machine is started at a time point t0 and is run-up until to a time point t1 to an overspeed that lies above its operating rotational speed, wherein the time point t1 lies before a time point t3, wherein the weaving machine is started at a time point t2 and wherein the start phase of the weaving machine lies in the time interval from the time point t2 to the time point t3, and wherein a power transmission (feedback) by means of the converter intermediate circuit from the shedding machine to the weaving machine is carried out in the stated start phase. The method according to the invention is characterized in that the shedding machine is run-up to a predetermined overspeed between the time points t0 and t1, and that the gradient of the rotational speed progression of the shedding machine is more negative in a later section of the start phase than in an earlier section.

Claims

1. Method for the controlled run-up of a weaving and shedding machine, wherein the weaving and the shedding machine are connected with a controller, wherein the weaving machine is driven by means of a main drive, wherein the shedding machine is driven by means of an electric motor auxiliary drive, wherein the weaving and the shedding machine are connected by means of a common converter intermediate circuit for the energy flow transmission, wherein the shedding machine is started at a time point t0 and is run-up until a time point t1 to an overspeed that lies above its operating rotational speed, wherein the time point t1 lies before a time point t3, wherein the weaving machine is started at a time point t2, and wherein the start phase of the weaving machine lies in the time interval from the time point t2 to the time point t3, and wherein a power transmission (feedback) by means of the converter intermediate circuit from the shedding machine to the weaving machine is carried out in the stated start phase, characterized in that the shedding machine is run-up to a predetermined overspeed between the time points t0 and t1, and that the gradient of the rotational speed progression of the shedding machine is more negative in a later section of the start phase than in an earlier section.

2. Method according to claim 1, characterized in that in the temporal midpoint, the gradient of the rotational speed progression of the shedding machine between the time point t2 and a time point t is less negative than in the temporal midpoint between the time points t and t3.

3. Method according to claim 1, characterized in that the gradient of the rotational speed progression of the shedding machine toward the end of the start phase is the most negative in the entire time span of the start phase.

4. Method according to claim 1, characterized in that the gradient of the rotational speed progression of the shedding machine is a strictly monotonic declining function as of the later of the two time points t1 or t2.

5. Method according to claim 1, characterized in that the stated overspeed of the shedding machine is calculated by means of a computing unit with the use of machine data.

6. Method according to claim 5, characterized in that for the calculation of the overspeed and of the further rotational speed progression of the shedding machine, additionally process data, at least such data based on calculated or estimated weaving machine losses and advantageously also on shedding machine losses, preferably also based on the duration of the stated start phase of the weaving machine, flow into the stated calculations.

7. Method according to claim 1, characterized in that the rotational speed progression for the weaving machine in the stated start phase is prescribed in such a manner so that at least toward its end it comprises a decreasing, that is to say less positive, gradient.

Description

[0037] The invention will be described in the following in connection with example embodiments. It is shown by:

[0038] FIG. 1 a flow diagram for illustrating a calculation method of the feedback for the case of a constant energy transmission portion;

[0039] FIG. 2 a schematic rotational speed-time diagram with t1<t2 for clarifying the invention,

[0040] FIG. 3 a schematic rotational speed-time diagram with t1<t2 similar to FIG. 2, however with a local maximum of the rotational speed of the shedding machine, and

[0041] FIG. 4 a schematic rotational speed-time diagram with t1>t2.

[0042] FIG. 1 shows a calculation method that proceeds from the starting point to proportionally support the power demand of the weaving machine at every time point of the weaving machine start, wherein the proportion, seen relatively, remains constant (e.g. 40%). The weaving machine start shall proceed in such a manner so that the rotational speed calculated from the kinetic energy and the energetically average mass moment of inertia increases in a ramp-shape over time up to the operating rotational speed. Thus, in this regard the expected power requirement of the weaving machine is covered in a proportion or fraction that remains constant with respect to percentage, which is possible when the time point t2, that is to say the starting time point of the weaving machine, does not lie before the time point t1 at which the shedding machine has reached its predetermined overspeed.

[0043] In the calculation step 1A, the initial maximum power demand or requirement of the weaving machine is determined from the machine and process data 1A. In this example, the operating rotational speed and the energetically average mass moment of inertia of the weaving machine are used as machine data. The expected losses or loss moments of the weaving machine and the starting duration, expressed as a time or as a transited angular range, are included as process data.

[0044] Suitably one first calculates the kinetic energy of the weaving machine toward the end of the starting process, thus at the operating rotational speed. This energy divided by the transited angular range gives the mechanically effective accelerating moment. To this is added the expected loss moment at the operating rotational speed, which is mainly dependent on the oil temperature in the transmissions. The thus-arising summed moment, multiplied by the operating rotational speed, provides the maximum required power of the weaving machine.

[0045] This maximum required power itself is compared to those machine data that characterize the network or supply conditions; this involves the characteristic data of a potential pre-transformer (rated power, short-circuit voltage or internal impedance) as well as the characteristic data of the supply unit for the converter intermediate circuit (passive or active network supply, if applicable a boost or step-up converter function, peak power). The comparison is an estimate. For example, at what peak power the pertinent pre-transformer or the pertinent supply unit will be expected to exhibit what extent of voltage drop is stored in tables. If the thus-expected total voltage drop in the converter intermediate circuit is then so strong or pronounced that either the voltage demand at the motor terminals can no longer be satisfied and/or the undervoltage detector of the converter intermediate circuit would be triggered and would bring about an interruption and stoppage of the starting process, then correspondingly additional energy or power on the part of the shedding machine must be supplied. This power fraction to be supplied as a supplement from the shedding machine is output as value 1a (demand) from the calculation step 1A.

[0046] It is suitable for the purpose if a calculation step 1B is carried out simultaneously or parallel close in time with the calculation step 1A, whereby the known peak torque or rotational moment of the shedding drive is multiplied with its operating rotational speed in the calculation step 1B. One obtains the peak power of the shedding drive. If applicable, a loss moment is previously deducted from the peak torque. The peak power of the shedding drive calculated in this manner is output as a value 1b (capacity or possibility) from the calculation step 1B.

[0047] In the calculation step 2, first 1a (demand or requirement) and 1b (capacity or possibility) are compared. If the demand is greater than the capacity, then problems of the abovementioned type during the starting up to the intended operating rotational speed cannot be excluded. Therefore a reaction is triggered in the step 2B. This can consist of a warning signal to the operator, if applicable in connection with the request to select a lower operating rotational speed and to start the machine in a testing manner, see path 2b. In this manner, the estimates from step LA can be corrected through an actually observed behavior of the converter intermediate circuit. Another possibility involves automatically reducing the operating rotational speed, under a corresponding information notification to the operator. In this case also, the pertinent machine start can serve for verification and if applicable correction of the assumptions from step 1A. In this regard, the reduced operating rotational speed should be calculated in such a manner so that for it the demand 1a is exactly as high as the capacity 1b.

[0048] The smaller of the two values 1a, 1bmathematically represented as Min(1a, 1b)is transferred as 2c to a calculation step 3. In that one multiplies half of this peak power with the required time of the weaving machine start, one obtains the energy that is to be provided as a supplement on the part of the shedding machine, which it must thus have available at the time point of the weaving machine start t2. Calculation from this supplemental energy, the operating rotational speed and the energetically average mass moment of inertia of the shedding machine gives the overspeed .sub.,FBM, which the shedding machine must havein comparison to the operating rotational speedat the time point t2. (For a further understanding also see the above given calculation example for a loss-free system).

[0049] The power requirement or demand of the weaving machine during the start-up develops proportionally to the rotational speed and time, and corresponding theretoaccording to the above arrangement or agreement for this methodalso to the power to be supplemented on the part of the shedding machine (finally up to the value 2c). From this fact and the already known value for .sub.,FBM(t2), it is now possible to calculate the value .sub.FBM(t) for the rotational speed of the shedding machine at any desired time point t up to the completion of the weaving machine start at the time point t3. By integration over time, one obtains the angle progression or curve .sub.FBM(t). Dependent on how the drive regulator or controller requires the prescribed instructions, e.g. for equidistant time points in the range [t2 . . . t3], pairs of values (support points) are formed with the associated ordinate value of .sub.FBM(t) or .sub.FBM(t), from which a software routine (if applicable in the drive regulator or controller itself) generates a mathematical expression corresponding to an electronic cam disk. The further transmission from the weaving machine of the data necessary for the calculation are referenced with 1a in FIG. 1.

[0050] A different advantageous calculation method is the use of polynomials, of which the coefficients are determined in such a manner so that thereby the rotational speed or the angular progression of the shedding machine is predefined for the range of the weaving machine start in the desired manner.

[0051] Three exemplary progressions or curves of the rotational speeds of the shedding machine (FBM) and of the weaving machine (WM) as a function of time corresponding to the invention are illustrated in FIG. 2. The shedding machine is started at the time point to and is driven or run-up, up to the time point t1, to the predetermined, especially calculated, overspeed .sub.,FBM (see above). At the time point t2, the weaving machine is started and in a starting phase that extends from the time point t2 to a time point t3, it is run-up to an operating rotational speed .sub.arb. During this start phase, energy is fed or supplied back from the shedding machine to the weaving machine in a defined manner, whereby a possible calculation method pertaining to this has been presented above.

[0052] It is significant to the invention that the gradient of the rotational speed curve of the shedding machine is more negative in a later section of the start phase of the weaving machine (that lies between the time points t2 and t3) than in an earlier section. In this regard, the later section does not necessarily border on the time point t3 and/or the earlier section does not necessarily border on the time point t2 (or t1, if t1 lies later than t2, see FIG. 4); but rather gradient progressions within the time period between the time points t2 (or t1, if t1 lies later than t2) and t3 can be compared with one another.

[0053] From FIG. 2 it can be seen, that in this example embodiment, the gradient of the rotational speed curve of the shedding machine, which is illustrated with a solid line (here referenced as FBM), is even the most negative toward the end of the start phase with reference to the entire time span of the start phase, that is to say the curve comprises the greatest negative slope at the time point t3 within the range between t2 and t3. Preferably the gradient of the rotational speed curve of the shedding machine between the time point t2 and a time point t marked as an example in the FIG. 2 is less negative than in the temporal midpoint or center between the time points t and t3.

[0054] It is also possible that the rotational speed progression of the shedding machine between the time points t2 and t3 temporarily for a short time even has a positive gradient, that is to say a positive slope, in an earlier stage of the start phase, before the gradient then again becomes negative.

[0055] The rotational speed progression of the weaving machine (here referenced as WM) which is illustrated with a solid line, is illustrated rising linearly with a ramp-shape in FIG. 2, as this was assumed in the above calculation method. An alternative rotational speed progression for the weaving machine (here referenced as WM) is represented with a dashed line, wherein the rotational speed during the run-up between the time points t2 and t3 comprises a decreasing positive gradient. In such a progression, the power take-up is more uniform than in a linear run-up, because the power peak toward the end of the weaving machine start is less pronounced. An exemplary corresponding rotational speed curve of the shedding machine (here referenced as FBM) is similarly illustrated with a dashed line. The flatter curve in comparison to the rotational speed curve FBM, especially toward the end of the start phase of the weaving machine, that is to say at the time point t3, corresponds to the curve WM of the weaving machine which is flatter there, because the energy feedback toward the end of the start phase of the weaving machine is smaller than for the previously discussed case of the ramp-shaped increase or rise of the rotational speed WM of the weaving machine.

[0056] Furthermore, a third variant is illustrated with dash-dotted lines in FIG. 2. The rotational speed curve of the weaving machine (here referenced as WM) comprises an S-shape, which is also repeated in the rotational speed curve of the shedding machine, referenced (here as FBM). The energy feedback from the shedding machine to the weaving machine isafter respective flatter rotational speed curves adjoining on the time point t2especially large during the strongest or sharpest rise of the rotational speed of the weaving machine. Toward the end of the start phase of the weaving machine, both rotational speed progressions or curves, FBM and WM, again flatten off.

[0057] The above described case of a local maximum of the rotational speed of the shedding machine is illustrated in FIG. 3. It must respectively be tested or checked whether this lies above the permissible maximum rotational speed of the shedding machine.

[0058] The case in which the time point t1 lies later than the time point t2 is represented in FIG. 4. Becauseas described initiallyfrom the point of view of the demand or requirement, the weaving machine does not profit from a support on the part of the shedding machine at the beginning of the start phase, therefore the weaving machine can already be started (at the time point t2) before the shedding machine reaches its calculated overspeed at the time point t1. It is important that thereafter it is ready to transmit energy to the weaving machine in the time interval from t1 to t3.

[0059] The activation of the main drive of the weaving machine and of the electronic auxiliary drive of the shedding machine is taken over by a controller that is prior art, and therefore is not described in further detail here. The above calculations are carried out with a computing unit that is connected with the stated controller.

[0060] The present invention is not limited to the illustrated and described example embodiments. Modifications in the scope of the patent claims are just as possible as a combination of the features, even if these are illustrated and described in different example embodiments.