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1、6th International DAAAM Baltic Conference INDUSTRIAL ENGINEERING 24-26 April 2008, Tallinn, Estonia ACTIVE VIBRATION CONTROL OF A PAPER MACHINE ROLL Juhanko.J; Porkka, E.; Kuosmanen, P.; Valkonen, A; Jrviluoma, M. Abstract: In process machines unexpected vibration behaviour may cause severe problems
2、 when passing the resonance frequencies. In paper machines it is often impossible to avoid sub-critical rotation speeds because of great number of different type of rolls and continuously changing process parameters. Uneven moment of inertia of the rotor and second harmonic of rotational error motio
3、n of the bearings are the main reasons for the second harmonic response at critical frequency which often restricts the running speed of a paper machine. By using active vibration control better runnability, less quality variation of paper and increased life time of roll covers and bearings could be
4、 achieved. Key words: rotor dynamics, active vibration control, roll 1. INTRODUCTION Resonant vibration of large-scale rotors used in turbines, generators, paper machines etc. is normally an unwanted effect and may cause major problems. Typically there are several rotation speeds (sub-critical speed
5、s) even below the first critical speed where superharmonic hits and excites the narrow band resonance. In process machines unexpected vibration behaviour may cause severe problems when passing the resonance frequencies. In paper machines it is often impossible to avoid sub-critical rotation speeds b
6、ecause of great number of different type of rolls and continuously changing process parameters. Uneven moment of inertia 1 of the rotor and second harmonic of rotational error motion of the bearings are the main reasons for the second harmonic response at critical frequency which often restricts the
7、 running speed of a paper machine 2. By using active vibration control better runnability, less quality variation of paper and increased life time of roll covers and bearings could be achieved. 2. EXPERIMENTAL SETUP In this research a servohydraulic device was built for active vibration control of l
8、arge-scale rotors. The test rotor was 5 meter long paper machine roll, which was supported by standard roller bearings. The device was a rigid frame with three servohydraulic cylinders loading the third bearing unit at the open end (Fig. 1). Measurement arrangement is described in Fig. 2. Fig. 1. Te
9、st arrangement with hydraulic active damper. 2.1 Control hardware The control system hardware consists of sensors, analog electronics, digital signal processing board DAP300a/415 with analog output extension board, a standard PC and three electrohydraulic servo valves and cylinders. 4000 210 2050 21
10、0 440440 M, (4880) 5000 1,2 3,4 5,6 7,8 p 75 75 11,12 13,14 9,10 380 yz Fig. 1. Measurement quantities in x-y directions: laser displacement sensors 1-6, acceleration sensors 7-10, relative motion between the bearing housing and the shaft 11-14, and rotary pulse encoder p. Location of the actuator i
11、s marked with red arrows. The control system uses signals p, 3 and 4. The commands for the signal processor card are given from the PC using DAPL command language and DAPVIEW user interface. The signal processor card is used for generating reference signals for the analog PID controllers, which cont
12、rol the forces of the cylinders. The oil pressures in both sides of the cylinder pistons in the three hydraulic cylinders are measured with pressure sensors. The analog force signals are generated from pressure measurements with analog amplifiers proportional to the piston areas. The force signals a
13、re fed both to the digital processor board and the analog PID controllers. The force control is implemented using servo valves with analog amplifiers. The digital processor card gives the set value signals for the PID controllers. Manual input to the processor board is provided by manual potentiomet
14、ers. These are used for force adjustment during start up and shutdown operations. The vibration of the rotor is measured in horizontal and vertical directions (x- and y-directions) with laser distance sensors (resolution 1 m) in the middle (lengthwise) of the rotor. In active damping the force set v
15、alue signals are then generated in the processor board by analysing the vibration signals and using information of the transfer characteristics of the actuator/rotor system. The force, vibration and manual input signals are fed to AD-converters through antialiasing filters. The rotation speed of the
16、 rotor is measured with a pulse sensor and separate pulse counter electronics with analog output. This pulse counter output signal gives the position angle of the rotor and the rotation speed signal is generated with software in the processor board by counting the number of control intervals which are spent during ten full revolutions. This way the maximum error in measuring the duration of ten full revolutions is one sample interval and maximum error in rotatio
