RU1827555C - Method for dynamic tests of rotors - Google Patents

Abstract

The invention relates to mechanical engineering. In the method, a variable force is created by installing on a rotor, a load of a fixed mass, alternately in two diametrically positioned and equally spaced from the axis of rotation, three starts are made of the rotor, two of them with a load and one without it, and during the run-out rotor displacements are measured at fixed frequencies, and the number of fixed frequencies N is selected depending on the number of degrees of freedom and dynamic model taken into consideration by the formula. 3 ill.

Description

The invention relates to mechanical engineering and can be used to experimentally evaluate the dynamic quality of machine tools and other machines.

The purpose of the invention is to improve the accuracy and performance of dynamic tests.

Figure 1 presents a General view of the rotor: figure 2 - section aa in figure 1; Fig. 3 is a vector diagram of forces.

The rotor 1 under test contains an unbalanced load 3. mounted in an annular groove 2, fixed in a certain position by a screw 4 and a counter surface 5, with which a non-contact relative vibration sensor 6 interacts, which is connected by wires to instrumentation and a computer.

The method is implemented as follows.

The workpiece (not shown) is fixed on the rotor 1, the drive (not shown) of the rotor 1 is turned on. It drives the latter to

maximum speed and then shuts off. When the rotor 1 is coasting, a measurement is made of the amplitudes at N different fixed frequencies.

The rotor 1 is braked and the load is placed in the annular groove 2 at 0 ° (1 position), fixed with a screw 4, the mass of the cargo is known in advance. The drive engages and rotor 1 accelerates to maximum speed. On the coast of the rotor 1 (free rotation), the oscillation amplitudes are measured at the same fixed N frequencies. Next, the rotor 1 is braked and the load 3 is moved to the diametrically opposite position (180 °), secured with a screw 4, the drive is turned on and the rotor 1 is accelerated to the maximum speed. On the coast of the rotor 1, the sensor 6 measures the amplitude of the oscillations at the indicated fixed frequencies.

Denote the fixed oscillation amplitudes;

00

Nd

h

SL SL

R (1.1) (.2 ... N) (start without unbalance In the resulting system 3, two are unknown

load) quantities: natural frequency of oscillations

R (2,1) (. 2 ... N) (starting with a load at 0 °) of the rotor W0 and a logarithmic decrement

R {3,1) (, 2 ... N) (start with a load of 180 ° at the point) of oscillations 0.

Consider a vector diagram of action-5. The values of W (1), W (2) and W (3) are taken from the acting forces and the corresponding re-results of calibrating the resonant filterings of the relative spindle, and 0 (1), 0 (2) and 0 (3) are calculated from the headstock for any 1st experimental data according to formula (1), frequency (see Fig. 3). Moreover, their dimension does not matter

The module of the displacement vector is caused by -10 (μm, mV, etc.), since the left-hand side of the balancing-balanced system (3), which is equalized by centrifugal force, is immeasurable. We solve the system

th load, for each of N fixed 3 by Newton's iterations,

frequency, can be calculated according to the known Then the amplitude of the change formula is calculated that relates the values of the sides of a different force Fg caused by the unbalanced grumedian of the oblique triangle15 with mass mg

ID (2.0i4D (3, a /o;5TKl2.l)l2+0.5:Rl3.lf-(1.1))4 l2 mQ

 (1) Fg (l) -.W2 (l) tH, (.2.3) (4) where | DX2, I) |. | B (3, t) | are the modules of the displacement vectors caused by centrifugal forces20 where R is the distance from the center of mass of the unbalanced weight; the unbalanced load to the axis of rotation of the rotor. mg

N is the number of the fixed frequency. W (|) is fixed and the frequency is measured.

to determine the dynamic displacement, we Convert the linear values calculated by the formulas of the elastically suspended mass of the sine-25 (t) D (l) B values to the initial force. For example, in microns, using the formula of a single-mass dynamical system, we can write X ((I). D (l). (5)

  Xo3Q where X (1) is the amplitude of the dynamic variables -2 55 © 35-Densities at the 1st frequency, μm, V (W0 - W (у + (W (Ґ -W0К (0 - transmission coefficient of the 1st channel

(2) measuring system, microns / mV.

where X (1) is the dynamic compliance by 1, From formula (2) it is now possible to determine the frequency; 35 we can add the static compliance; the dynamic is the static compliance. μm / N, system X0, moreover, the calculation can

W0 - natural frequency of oscillations, make for all three frequencies and determine

Hz result

W0) - fixed frequency, Hz. s

0- logarithmic decrement count - 0 Xcr 2 X (0X

Banii. 3W 1 For a single-mass system, enough

take measurements on three fixed- (W2-W2)) 2 + (W2 (I) -W &

frequencies. Given that displacements W

proportional to the acting forces, 45 Then, using the formula (2),

we carry out a term-by-word division of the expressions, it is possible to calculate the dynamic sub-formula 2 and squared the left willow Р ° t ° Ra in the frequency of interest to us, the right-hand sides of the obtained expressions.nom range, as well as phase angles

shifts by the formula 50

D2 (D V (WQ w C2) 2) 2 + (g) 2 w V -WQJ-WCQW,

 (0 arct9w20-w2 (i) (7)

j- ш2Гоч 2, Г Х2Ш2Г.Ш255 All calculations and graphs are carried out

P (1) ... ° / W v3 W on a computer. Compared to the prototype, the accuracy rj2 / - .j .- 2-3 © 3-2 2-5 increases by 5 times, time - by 40

 ; (Wo - W (1) f + (jff W (1 f -Wo.) Three measurements are made during measurements (3) which is the minimum number of starts that

allows you to build a vector diagram (a triangle in which the median find the third side along the two sides - the amplitude of AC).

Claims (1)

SUMMARY OF THE INVENTION A method for dynamically testing rotors is as follows. that they rotate the rotor, apply a force of variable frequency and amplitude to it and record the relative oscillations of the rotor, about t and. that one. that, in order to increase accuracy and productivity, the force is created by installing a given mass on the rotor of the load in turn in two diametrically opposite positions, at least three rotor starts are made, two of them with the load, and one without it, and the relative oscillations of the rotor at fixed speeds when it is coasted, V / f # t # oe IEZ