Method for operating a textile machine and a textile machine

Abstract

A method for operating a textile machine with several identical workstations which each have a basic requirement for negative pressure for regular production operation and an additional requirement for negative pressure following an interruption to production at the workstation, and with a vacuum system with limited suction force to exert the negative pressure on the workstations. A minimum negative pressure (p.sub.min) is set and the number workstations simultaneously supplied with additional negative pressure is limited so that the minimum negative pressure (p.sub.min) is always met. In accordance with the invention, a sub-negative pressure (p.sub.sub) is specified which is below the minimum negative pressure (p.sub.min) and, if a specified event occurs, the number of workstations simultaneously supplied with additional negative pressure is temporarily limited so that the sub-negative pressure (p.sub.sub) is always met.

Claims

1. A method for operating a textile machine with several identical workstations which each have a basic requirement for negative pressure for regular production operation and an additional requirement for negative pressure following an interruption to production at a workstation, and wherein the textile machine comprises a vacuum system with limited suction force to exert the negative pressure on the workstations, whereby a minimum negative spinning pressure (p.sub.min) is set, wherein, at said minimum negative spinning pressure (p.sub.min), an absolute value of the negative spinning pressure (p.sub.min) is at its lowest level during standard operation; and whereby the number of workstations to be supplied with additional negative pressure simultaneously is limited so that the minimum negative pressure (p.sub.min) is met, characterised in that a sub-negative spinning pressure (p.sub.sub) is set, wherein an absolute value of the sub-negative spinning pressure (p.sub.sub) is below the absolute value of the minimum negative spinning pressure (p.sub.min) and upon the occurrence of a specified event, the number of workstations simultaneously supplied with additional negative pressure is temporarily limited so that the sub-negative pressure (p.sub.sub) is met.

2. The method according to claim 1, characterised in that the event is a ramping-up of the textile machine following a machine stoppage, during which all workstations have an additional requirement for negative pressure.

3. The method according to claim 1, characterised in that the event is a ramping-up of a group of workstations which require additional negative pressure simultaneously.

4. The method according to claim 2, characterised in that during the event specified, the number of workstations supplied with additional negative pressure simultaneously is increased from a first number (Z.sub.1) to a second number (Z.sub.2) by the temporary reduction of the negative spinning pressure.

5. A textile machine with several identical workstations which each have a basic requirement for negative pressure for regular production operation and an additional requirement for negative pressure following an interruption to production at a workstation, and wherein the textile machine comprises a vacuum system with limited suction force to exert the negative pressure on the workstations, whereby a control unit is present and is used to specify a minimum negative pressure (p.sub.min), wherein, at said minimum negative pressure (p.sub.min), an absolute value of the minimum negative pressure (p.sub.min) is at its lowest level during standard operation, and wherein the control unit is designed so that the number of workstations simultaneously supplied with additional negative pressure is limited so that the minimum negative pressure (p.sub.min) is met, characterised in that, a sub-negative pressure (p.sub.sub) is specified at the control unit, wherein an absolute value of the sub-negative pressure (p.sub.sub) is below the absolute value for the minimum negative pressure (p.sub.min), and that the control unit is designed so that, if a specified event occurs, the number of workstations simultaneously supplied with additional negative pressure is temporarily limited so that the sub-negative pressure (p.sub.sub) is met.

6. The textile machine according to claim 5, characterised in that the control unit stores a ramping-up of the textile machine following a machine stoppage during which the workstations have an additional negative pressure requirement as an event.

7. The textile machine according to claim 5, characterised in that a ramping-up of a group of workstations which have a requirement for additional negative pressure at the same time is stored as an event in the control unit.

8. The textile machine according to claim 5, characterised in that during the event specified in the control unit, the number of workstations supplied with additional negative pressure simultaneously is increased from a first number (Z.sub.1) to a second number (Z.sub.2) by the temporary reduction of the negative spinning pressure.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The method in accordance with the invention is explained in greater detail below with an embodiment example shown schematically in the drawing. An open-ended rotor spinning machine is assumed in the embodiment example.

(2) FIG. 1 shows schematically using a diagram with a curve 1 how the negative pressure p in the vacuum system of a textile machine changes.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

(3) Referring to FIG. 1, curve 1 shows how the negative pressure p changes, both during regular spinning operation and following the ramping up of the textile machine following a lot change or an involuntary machine stoppage. Curve 1 particularly shows the level of the negative spinning pressure that can be specified in the area of the workstations of a rotor spinning machine in the rotor housing of the open-ended spinning devices.

(4) Curve 2 shows schematically how the speed of the drive motor of the vacuum unit of the textile machine changes, i.e. the change in speed of the drive motor both during regular spinning operation and following the ramping up of the textile machine following a lot change or an involuntary machine stoppage.

(5) With Z.sub.1 and Z.sub.2, the number of workstations of the rotor spinning machine that can be simultaneously supplied with additional negative pressure and can therefore pieced up again is shown graphically.

(6) Z.sub.1 shows the number of workstations that can be supplied with additional negative pressure if the workstations have a minimum negative spinning pressure p.sub.min. Z.sub.2 shows the number of workstations that can be supplied with additional negative pressure if the workstations have a sub-negative spinning pressure p.sub.min.

(7) The x-axis shows the progress of time for the method in accordance with the invention, whereby the various points in time described in more detail below are identified as A, B, C etc.

(8) The vertical axis shows the level of negative spinning pressure in the rotor housing with p, as well as the speed level of the drive motor of the vacuum unit of the textile machine with d.

(9) As can be seen, the drive motor of the vacuum unit of the open-ended rotor spinning machine runs during regular spinning operation of the textile machine at a lower speed d.sub.ist compared to its maximum speed.sub.max.. In the area of the rotor housing of the open-ended spinning devices of the workstations, a specifiable minimum negative spinning pressure p.sub.min is applied during this time. Because all workstations initially run regularly, the number of workstations that need to be supplied with additional negative pressure simultaneously is 0 at this time.

(10) At time A, a number of workstations require additional negative pressure, for example because there are spinning interruptions at the workstations due to yarn breaks and the workstations need to be pieced up again.

(11) In such a case, the control unit of the textile ensures that the drive motor of the vacuum unit is accelerated to its maximum speed d.sub.max.. This maximum speed d.sub.max. is reached, for example at point in time B.

(12) Due to the maximum speed d.sub.max of the drive motor of the vacuum unit the level of negative spinning pressure in the vacuum system is increased to a maximum negative spinning pressure p.sub.max., as is indicated by the dashed line 1′, if at point in time B no additional negative pressure is required by the aforementioned workstations that need to be pieced up again, which is significantly greater than the minimum negative spinning pressure p.sub.min.

(13) However, the control unit of the textile machine has simultaneously calculated the number Z.sub.1 of workstations that can be supplied with additional negative pressure simultaneously from point in time B, i.e. simultaneously pieced up again, without the negative spinning pressure in the vacuum system sinking below the minimum negative spinning pressure p.sub.min., i.e. despite a number Z.sub.1 of workstations being supplied with additional negative pressure, the negative spinning pressure in the vacuum system remains at a minimum negative spinning pressure p.sub.min.. It has calculated this number from the difference between the maximum negative spinning pressure p.sub.max. and minimum negative spinning pressure p.sub.min. as well as the additional negative pressure requirement of an individual workstation.

(14) If, for example, at point in time C the piecing up of a number of workstations Z.sub.1 is completed, the maximum speed d.sub.max of the drive motor of the vacuum unit is returned to the speed d.sub.ist, which occurs at point in time D. The level of negative spinning pressure in the vacuum unit remains at a minimum negative spinning pressure p.sub.min.

(15) E shows the point in time at which a significant disruption to operation occurs. This means that at time E the rotor spinning machine switches off, for example due to an interruption in the electricity supply, and stops, which occurs at time F. At time F the speed of the drive motor is d.sub.0 and the negative pressure in the vacuum system is accordingly p.sub.0.

(16) Because such a machine stoppage results in spinning interruptions at all workstations of the textile machine, all of the workstations of the rotor spinning machine must be pieced up again after the machine stoppage is over.

(17) Because, as is known, the machine ramp-up time of a textile machine is also decisive for the overall efficiency of a machine, it is advantageous if all of the workstations of an affected textile machine are brought back into operation as quickly as possible following a machine stoppage. Therefore, in order to keep the ramp-up time of the textile machine as short as possible, as many workstations as possible must be pieced up again simultaneously, i.e. supplied with additional negative pressure simultaneously.

(18) To this end, the operating personnel set a sub-negative spinning pressure p.sub.sub in the control unit of the textile machine. This means that, during the ramping up of the open-ended rotor spinning machine, a sub-negative spinning pressure p.sub.sub, is temporarily applied in the area of the vacuum system of the textile machine, which is below the minimum negative spinning p.sub.min. which is standard during regular operation of the rotor spinning machine.

(19) The restarting of the rotor spinning machine occurs at time G. Because there are a number of demands for additional negative pressure from workstations simultaneously at time G, which all want to be pieced up again immediately following a stoppage, the control unit of the textile machine ensures that the drive motor of the vacuum unit accelerates to its maximum speed d.sub.max., which is reached at time H. This means that, if there were no requirement for additional negative pressure from workstations wanting to be pieced up again, there would be a maximum negative spinning pressure p.sub.max. in the vacuum system of the textile machine at this point, as indicated by the dashed curve 1′. However, the control unit of the textile machine simultaneously calculated, from the difference between the set sub-negative spinning pressure p.sub.sub and the maximum negative spinning pressure p.sub.max. as well as the respective negative pressure of an individual workstation, the number Z.sub.2 of workstations that need to be supplied with additional negative pressure simultaneously during the ramp-up of a textile machine, without the risk occurring that the negative pressure in the vacuum system of the textile machine would fall below the pre-specified sub-negative spinning pressure p.sub.sub.

(20) From time H onwards, a maximum possible number Z.sub.2 of workstations is continuously simultaneously supplied with additional negative pressure, whereby, as explained above, it is ensured that the negative pressure in the vacuum system does not fall below the sub-negative spinning pressure level p.sub.sub. After a specific time, indicated by time I, all workstations of the textile machine are pieced up again, i.e. there is no longer any additional requirement for negative pressure from the workstations. This means that at time I there is a situation where the negative pressure provided by the vacuum unit exceeds the demand for negative pressure due to the drive motor rotating at maximum speed d.sub.max.. At time I, the speed d.sub.max. of the drive motor of the vacuum unit begins to be reduced, and at time K the speed is d.sub.ist once more. At the same time, the control unit of the textile machine corrects the negative spinning pressure set in the vacuum system of the textile machine. This means that the sub-negative spinning pressure p.sub.sub, temporarily applied in the area of the vacuum system of the textile machine during ramping up of the open-ended rotor spinning machine is increased to the minimum negative spinning p.sub.min. which is standard during regular operation of the rotor spinning machine.

LIST OF REFERENCE NUMBERS

(21) Curve 1 negative pressure level in the vacuum system Curve 1′ negative pressure at p.sub.max without additional pressure consumers Curve 2 motor speed of the vacuum unit A Time B Time C Time D Time E Time F Time G Time H Time I Time K Time p.sub.0 negative pressure for a stopped vacuum unit p.sub.sub sub-negative spinning pressure p.sub.min minimum negative spinning pressure p.sub.max maximum negative spinning pressure d.sub.0 speed of the motor in a stopped suction unit d.sub.ist current speed of the motor d.sub.max maximum speed of the motor Z.sub.1 number of additional workstations at p.sub.min Z.sub.2 number of additional workstations at p.sub.sub

(22) It will therefore be readily understood by those persons skilled in the art that the present invention is susceptible of broad utility and application. Many embodiments and adaptations of the present invention other than those herein described, as well as many variations, modifications and equivalent arrangements, will be apparent from or reasonably suggested by the present invention and the foregoing description thereof, without departing from the substance or scope of the present invention. Accordingly, while the present invention has been described herein in detail in relation to its preferred embodiment, it is to be understood that this disclosure is only illustrative and exemplary of the present invention and is made merely for purposes of providing a full and enabling disclosure of the invention. The foregoing disclosure is not intended or to be construed to limit the present invention or otherwise to exclude any such other embodiments, adaptations, variations, modifications and equivalent arrangements.