EP1687469A1

EP1687469A1 - Drafting arrangement for a spinning machine

Info

Publication number: EP1687469A1
Application number: EP04766749A
Authority: EP
Inventors: Peter Denz
Original assignee: Rieter Ingolstadt Spinnereimaschinenbau AG
Current assignee: Rieter Ingolstadt Spinnereimaschinenbau AG
Priority date: 2003-11-06
Filing date: 2004-09-09
Publication date: 2006-08-09
Anticipated expiration: 2024-09-09
Also published as: DE502004004053D1; CN100547135C; EP1687469B1; DE10352303A1; CN1878897A; WO2005045107A9; WO2005045107A1

Abstract

Disclosed is a drafting arrangement for a spinning machine, particularly a draft regulator, comprising at least two successive pairs of rollers, several electric motors (10, 20) for driving at least one respective roller (2, 3, 4) belonging to said roller pairs, and an electronic regulating ring (5) to which the electric motors (10, 20) are connected. The drafting arrangement is characterized in that an acceleration sensor (12, 22) is allocated to at least one electric motor (10, 20) and/or at least one roller (2, 3, 4).

Description

Description STRETCHER FOR A SPINNING MACHINE

The invention relates to a drafting system for a spinning machine, in particular a regulating section, with at least two successive pairs of rollers, with a plurality of electric motors for driving at least one roller each of said pairs of rollers and with an electronic control unit which the electric motors are connected to.

In regulated drafting systems, an exact synchronism of the roller pairs of the drafting system is of crucial importance for the quality or uniformity of the fiber sliver or slivers produced. Mechanical couplings via gears or belt drives are very suitable for this, since they ensure the basic synchronism of the roller pairs. However, they are not ideally suited for automation purposes.

The use of several direct drives, so-called individual drives, for driving the drafting system components offers the possibility of automating the machine settings for warping and tensioning conditions. Lines with such individual drives have been known for a long time. In known designs, the motor shafts of the drives or the roller shafts are assigned incremental rotary encoders for determining the speed, the speed of rotation, the angle of rotation or the like. The rotary encoders are usually designed as digital position (angle) sensors, from whose position signals (number of rotations per predetermined time window) speed or rotational speed information are obtained, which are used with the aid of an associated motor control device to readjust the respective motor speed ,

The disadvantage of these conventional drive systems containing a position and speed control using incremental encoders is that the formation of the signals for digital processing takes time. During this period there are no current values and it has to be interpolated. For the drive, this means a certain play in the motor shafts, which is very disturbing for the synchronicity in the dynamic range and greatly deteriorates the immunity to interference. Disturbances on the motor shafts, caused by load changes, belt vibrations, etc. cannot be effectively eliminated. The result is poor smoothness during constant running and unsynchronism between the drafting rollers.

It is therefore the object of the present invention to provide a drafting system of the type mentioned which avoids the disadvantages mentioned and in particular ensures an even further improved delay. This object is achieved in the drafting system of the type mentioned in that an acceleration sensor is assigned to at least one electric motor and / or at least one roller.

The advantages of the invention can be seen in particular in the fact that a real-time signal with regard to the acceleration is obtained, which immediately changes the load torque, i. Interferences, registered. These disturbance variables include, from the scanning gear, which is upstream of the drafting system, registered thick spots and the elasticity of drive belts and their vibrations. The load torque changes cause positive or negative accelerations of the motor shaft, which can be detected directly by the acceleration sensor. The signals output by the sensor can then be processed directly in order to readjust the motor current. In contrast to the use of incremental position sensors, no time-consuming processing of signals is necessary, the motors can be controlled immediately, quickly and precisely. It is thus possible to achieve synchronous and constant running of the roller pairs, which is superior to conventional drives.

[008] If the acceleration information were calculated using the known incremental rotary encoders, this would take a considerable amount of time. In addition, the necessary differentiation of the encoder signals would induce errors which negatively affect the control quality.

However, it is also possible to obtain speed or speed values from the acceleration values by integration, the arithmetic operations required for this causing fewer errors than the differentiations mentioned.

Another advantage of using acceleration sensors is their high sensitivity and, at the same time, relatively great robustness.

The said at least one acceleration sensor is particularly preferably designed as a relative acceleration sensor, since this does not take into account the disruptive influence of the acceleration due to gravity. The so-called Ferraris sensor, which is based on the eddy current principle and has a very high dynamic range, has proven to be a special, well-suited relative acceleration sensor.

In a preferred embodiment, the at least one acceleration sensor is arranged on a shaft of an electric motor and thus determines the real-time signals for accelerating this shaft directly on the shaft. When using a Ferrari sensor, signals are only output from it when the roller experiences a relative acceleration.

[013] In an alternative, the acceleration sensor is arranged on a shaft of a roller. The time advantage gained by means of the acceleration sensor can be retained if fast-switching, analog and / or digital circuit parts are used for essentially instantaneous signal evaluation of the sensors mentioned and their conversion into current signals for the motors.

A separate motor control device is advantageously assigned to the electric motors. This particularly preferably comprises a speed controller and a downstream current controller for the respective motor. With such an arrangement, position and speed signals of the motor (or also a roller shaft driven by the motor) are obtained, for example, from incremental rotary encoders (encoders with bar code disks, resolvers based on the transformer principle, Sincos encoders). These actual signals are then applied to the speed controller, which compares them with the target values of the regulating devices. The output signal of the speed controller is applied to the current controller as a setpoint, which also receives its current actual value from the motor. In addition, according to the invention, an acceleration sensor is provided at a suitable point on the engine, preferably on its output side. The signals from the acceleration sensor can then be connected directly to the current controller in order to compensate for short or fast load changes.

The signal of the acceleration sensor is particularly preferred in its analog form, i.e. without analog-digital conversion, used and preferably connected to the motor device and in this case the current controller. In such a direct connection of the signals of the acceleration sensor, the current controller is expediently designed as a hybrid controller which can process both analog and digital signals (the latter are in particular the output signals of the speed controller). The use of analog acceleration values or the voltage values proportional to them from the at least one acceleration sensor has the advantage that these signals can be processed in real time.

[017] As an alternative to connecting the acceleration signals to the motor device and, in this case, preferably the current controller, they can also be connected to the regulating device, also in this case preferably but not necessarily in analog form.

In addition, a tachometer generator for exact speed measurement can be assigned to at least one of the electric motors, the preferably analog, real-time signals of the tachometer generator preferably being connected to an input of the speed controller. With this tachogenerator, short or fast speed changes on the motor shaft can also be detected and incorporated into the speed control. Even at slow speeds, more precise speed values can be measured in an analog form than with a digital and therefore graduated moving encoder. For the evaluation of these analog signals, the speed controller is also preferably designed as a hybrid controller.

Instead of using hybrid controllers which ensure that the disturbance variables are recorded without loss of time, the analog signals can also be processed by analog modules, in particular amplified, weighted, evaluated, etc.

Advantageous developments of the invention are characterized by the features of the subclaims.

The invention is explained below with reference to the figures. Show it:

[022] Figure 1 is a schematic plan view of a drafting system according to the invention, and

[023] Figure 2 is a block diagram of a motor control device.

[024] FIG. 1 schematically shows a regulating drafting device 1 according to the invention, which comprises an input roller pair, a middle roller pair and an output roller pair. Only the lower rolls of these pairs are shown in FIG. the input lower roller 2, the middle lower roller 3 and the output lower roller 4. Only these lower rollers 2, 3, 4 are driven in the present case, while the upper rollers, not shown, are pressed onto the associated lower rollers 2, 3, 4, so that the fiber ribbon or fibers FB, which is only indicated schematically be clamped between the pairs of rollers. The two lower rollers 2, 3 are driven by a common electric motor 10, which causes a predetermined advance between the pair of input rollers and the center rollers via a gear stage (not shown) with belt drives 6. The output lower roller 4 is driven by means of its own electric motor 20 via belt drives 7, not shown. The speeds of the electric motors 10, 20 can be regulated with the aid of a regulating device 5 in such a way that a warping of the sliver or slivers FB regulating the sliver mass fluctuations is realized between the middle and the exit roller pair. For this purpose, the regulating device receives 5 tape measures or Band cross-sectional signals from a measuring device upstream of the drafting device 1, not shown here. The regulating device 5 can be designed as a microcomputer which, in addition to the electronic regulation, also takes over the machine control.

[025] The electric motors 10, 20 are each assigned their own electronic motor control units 3 and 23, which are each connected to the regulating device 5 via lines 8 and 9 and receive setpoint values relating to the motor speeds from the latter. The motor control devices 13 and 23 are each connected to the respective electric motor 10, 20 via a line 18 or 28. Furthermore, an incremental rotary encoder 11 or 21 is connected to the electric motors 10, 20 via lines 16 or 26, which is designed, for example, as a known encoder or resolver and is used to detect the speeds of the respective motor shaft. During a shaft revolution, the incremental encoder 11 or 21 outputs, for example, approximately 100 pulses, so that the pulses per unit time of the respective shaft can be concluded from the pulses within a predetermined time window and the position of the motor rotor. The digital signals from the rotary encoders 11 and 21 are transmitted to the respective motor control device 13 and 23 with the aid of lines 17 and 27, where they are used to adjust the motor current of the electric motors 10, 20.

[026] Furthermore, according to the invention, each of the electric motors 10 and 20 is assigned an acceleration sensor 12 or 22, which in the present case is designed as a relative acceleration sensor, for example as a Ferraris sensor. The acceleration sensors 12 and 22 are assigned to the respective motor shafts of the electric motors 10, 20 via lines 14 and 24, the acceleration sensors 12 and 22 being highly dynamic acceleration signals in the form of actual voltage values via lines 15 and 25 to the respective motor control device 13 and 23 transmit.

[027] The acceleration sensors 12, 22 preferably only deliver signals when positive or negative accelerations actually occur on the motor shafts. These are caused by changes in the load, which cause changes in the load torque and thus the engine speed. The analog acceleration signals of the acceleration sensors 12, 22 can now be used directly as real-time signals for current control of the electric motors 10, 20. The combined evaluation of the position values measured with the aid of the incremental rotary encoders 11 and 21 and the acceleration values of the sensors 12 and 22 ensure precise, fast motor control, in particular in the case of rapid and / or short load changes. Overall, the control quality can thus be increased considerably.

[028] FIG. 2 shows a block diagram of a motor control device 13, this device 13 being constructed analogously to the motor control device 23. The motor control device 13 comprises a speed controller 34 and a downstream current controller 36, the latter being connected to the electric motor 10 via the line 18 and transmitting a current target value to the latter. On the one hand, the aforementioned acceleration sensor 12 is assigned to the motor 10 and, on the other hand, a tachometer generator 30 (not present in the exemplary embodiment in FIG. 1) is assigned via a line 31. This determines the actual speed of the motor shaft and forwards its analog output signal to the speed controller 34 via a line 32. The speed controller 34 also receives digital signals from the incremental rotary encoder 11 and, via line 8, a speed setpoint “target” from the regulating device 5. Since the speed controller 34 thus processes analog and digital signals, it is designed as a hybrid controller. Its output signals are via a line 35 the current controller 36 is connected, which also the current actual value of the Motor 10 and via line 15 receives a voltage value proportional to the instantaneous acceleration value (if acceleration is present) from the acceleration sensor 12. Advantageously, these voltage values are directly applied in an analog form to the current regulator 36, so that it is also expediently designed as a hybrid regulator. Furthermore, the current regulator 36 receives the information “Max” for the maximum permissible motor current via a line 38.

[029] The motor control device 13 together with the speed controller 34 and the current controller 36 preferably has fast-switching, analog and digital circuit parts in order to be able to carry out the signal evaluation and the conversion into current signals essentially without delay. The motor control device 13 is preferably controllable by software.

The above statements regarding the motor control device 13 apply analogously to the motor control device 23.

[031] The electric motors involved can either operate in mast / slave mode or in parallel setpoint mode.

[032] Other individual drive arrangements are possible without deviating from the basic idea of the invention, as set out in the claims.

Claims

Expectations

Drafting system for a spinning machine, in particular a regulating section, with at least two successive pairs of rollers, with a plurality of electric motors (10, 20) for driving at least one roller (2, 3, 4) each of said pairs of rollers and with an electronic regulator (5 ), to which the electric motors (10, 20) are connected, characterized in that at least one electric motor (10, 20) and / or at least one roller (2, 3, 4) is assigned an acceleration sensor (12, 22).

Drafting system according to claim 1, characterized in that the at least one acceleration sensor (12, 22) is designed as a relative acceleration sensor.

Drafting system according to claim 2, characterized in that the at least one acceleration sensor (12, 22) is a Ferraris sensor.

Drafting system according to one of the preceding claims, characterized in that the at least one acceleration sensor (12, 22) is arranged on a shaft of the at least one electric motor (10, 20).

Drafting system according to one of claims 1 to 3, characterized in that the at least one acceleration sensor (12, 22) is arranged on a shaft of a roller (2, 3, 4).

Drafting system according to one of the preceding claims, characterized by fast-switching, analog and / or digital circuit parts (13, 23) for essentially instantaneous signal evaluation of the at least one acceleration sensor (12, 22) and their conversion into current signals for the respective motor ( 10, 20).

Drafting system according to one of the preceding claims, characterized in that the at least one electric motor (10, 20) and / or at least one roller (2, 3, 4) an incremental rotary encoder (11, 21) for recording the speed, the Direction of rotation and / or the angle of rotation is assigned.

Drafting system according to one of the preceding claims, characterized in that the at least one electric motor (10, 20) is assigned its own motor control device (12, 23).

[009] Draw frame according to claim 8, characterized in that the motor control device (13, 23) comprises a speed controller (34) and a current controller (36) for the at least one electric motor (10, 20).

Drafting system according to one of the preceding claims, characterized in that the signals of the acceleration sensor (12, 22) associated with the at least one electric motor (10, 20) on the regulating device (5) or the Motor control device (13, 23), preferably an input of the current controller (36), are switched.

Drafting system according to claim 10, characterized in that the signals of the acceleration sensor (12, 22) associated with the electric motor (10, 20) are applied in analog form without prior analog-digital conversion.

Drafting system according to one of the preceding claims, characterized in that a tachometer generator (30) is provided for determining the speed of the at least one electric motor (10, 20).

Drafting system according to claim 12, characterized in that the signals of the tachometer generator (30) on the motor control device (13, 23), preferably an input of the speed controller (34), are switched.

Drafting system according to claim 12 or 13, characterized in that the tachometer generator (30) transmits analog signals.