RU2593676C1 - Balancing unit and low-frequency vibration system for its implementation - Google Patents

Abstract

FIELD: balancing equipment.

SUBSTANCE: invention relates to balancing equipment and can be used for rotor balancing. Balancing unit comprises a base, post and oscillating system containing cradle, suspension thrust and support tie rod. Balanced rotor is placed on the cradle, after acceleration the rotor unbalance causes oscillations of cradles that are converted by vibration sensors into electrical signals arriving into a measuring unit. Phase indicating device provides pulse onto each rotor revolution. Measuring unit displays the measurement result of unbalances. Unit is equipped with an oscillatory system in the form of at least one suspension and one support rods. Upper parts of suspension rods are movably arranged on the fixed part of the post, their lower parts are movably arranged on the cradle; top parts of support tie rods are movably arranged on the cradle, their lower parts are movably arranged on the fixed part of the post. Unit comprises several posts with oscillating systems. Design of an oscillating system allows adjusting its frequency. Rods are made of adjustable length, and the place of stacking (installing) the balanced object can move.

EFFECT: technical result consists in possibility of balancing at extremely low frequencies of rotation.

7 cl, 6 dwg

Description

The invention relates to mechanical engineering and can be used, for example, for balancing rotors.

In the art, balancing machines with a rotation drive of a product are widely known, comprising a bed with a flexible support mounted on it to accommodate a balanced product, vibration sensors mounted on the support. A flexible support is made in the form of cradles of two separate supports mounted on a bed, cradles of supports are connected to their bodies on a flexible suspension of two steel tapes providing a resonance balancing mode (Fundamentals of balancing technique edited by V.A. Schepetilnikov: Engineering, 1975, t. 2, p. 371). However, this structure of the oscillatory system of the balancing machine does not have sufficient linearity, which leads to an error in the balancing process.

There is also known a balancing machine containing a base, two guides placed on it, a flexible support made in the form of two parallel mounted racks placed with the possibility of moving along the guides, two cradles to accommodate a balanced object, each of which is pivotally connected to the corresponding rack by means of rods and placed with the possibility of plane-parallel movement relative to the rack, phase meter of rotation of the balanced object, the first and second sensors of the information signal and mi aroprocessor signal processing unit, characterized in that the information signal sensors are made in the form of vibration acceleration sensors, each of which is placed on a corresponding cradle of a flexible support, and the microprocessor signal processing unit is made in the form of a series-connected switch, a filter unit, an analog-to-digital converter, a microprocessor and an information display unit, a unit for setting measurement modes, the output of which is connected to the second input of the microprocessor, the output of which is connected to the third input of which of the rotation meter of the balanced object and the second input of the analog-to-digital converter, the second and third outputs of the microprocessor are connected respectively to the first input of the switch and the second input of the filter unit, the second and third inputs of the switch are connected respectively to the output of the first and second acceleration sensors. (See RF Patent 2046310). From the same patent, the oscillatory system of the balancing machine is known, containing traction and a cradle for securing the mass of the object being balanced (see Fig. 2G).

The well-known "balancing machine" is the closest analogue in technical essence and the achieved result to the proposed technical solution and adopted as a prototype. The well-known machine provides high precision balancing and reliable operation. However, since the oscillatory system of this machine is a variant of the mathematical pendulum, a sufficiently low natural frequency of oscillations cannot be achieved with acceptable overall dimensions, therefore balancing on this machine is carried out at high rotor speeds, which requires high energy costs, and for some types of rotors not applicable due to insufficient stiffness of the rotor or significant interaction with the surrounding air.

The aim of the invention is the creation of a balancing machine with an oscillating resonance system with an ultra-low natural frequency while maintaining overall dimensions at a level that is convenient in a constructive sense.

This is ensured by the fact that the balancing machine containing the base, the guides 9 parallel to it, a flexible support made in the form of one, two or more parallel mounted racks arranged to move along the guides, and oscillating systems containing the cradles to accommodate the balanced object connected to the corresponding rack articulated by means of support and suspension rods and placed with the possibility of plane-parallel movement relative to the rack, the phase shifter is rotary balancing object, vibration sensors and measuring unit.

The machine is equipped with an oscillating system made in the form of at least one suspension and one support rod so that the suspension rods with the upper end are fixed with the possibility of swinging on the fixed part of the rack, and the lower end are fixed with the possibility of swinging on the cradle, the supporting rods are fixed with the upper end with the possibility of swinging on the cradle, and the lower end fixed with the possibility of swinging on the fixed part of the rack. This is ensured by the fact that the balancing machine contains several racks with oscillatory systems. This is also ensured by the fact that the rods are made of adjustable length and in the balancing machine the place of laying (mounting) of the balanced object is made with the possibility of movement. This is also ensured by the fact that the oscillating system of the predominantly balancing machine comprises rods and a cradle for securing the mass, where the rods consist of suspension and support rods, so that the suspension rods with the upper end are fixed with the possibility of swinging on the fixed part of the rack, and the lower end are fixed with the possibility of swinging on the cradle, the support rods are fixed with the upper end with the possibility of swinging on the cradle, and the lower end is fixed with the possibility of swinging on the fixed part of the rack. Rods can be made of adjustable length. In the oscillatory system, the place of laying (installation) of the mass is made with the possibility of movement.

In FIG. 1A is a schematic side view of a balancing machine;

in FIG. 1B schematically shows a balancing machine, front view;

in FIG. 2A is a diagram of an oscillatory system;

in FIG. 2B - diagram of the oscillatory system - option;

in FIG. 2B is a diagram of a variant of an oscillatory system with a designation of characteristic dimensions for calculation;

in FIG. 2G is a diagram of a prototype oscillatory system with a designation of characteristic dimensions for calculation.

The balancing machine (Fig. 1A and 1B) contains a base 6, parallel guides 9 mounted on it, a flexible support made in the form of one, two or more parallel mounted racks (5, 10), placed with the possibility of movement along the guides 9, and vibration systems containing cradles 2, 12 (according to the number of racks, Fig. 1 shows a variant with two racks) for placing a balanced object 7, connected to the corresponding rack articulated by means of support 4 and suspension 8 rods and placed with the possibility of plane-parallel movable relative to rack 1 rotation fazootmetchik object 7 to be balanced, vibration sensor 3 and the measuring unit 11. The machine is equipped with a vibrating system using a combination of support and suspension rods 4 8.

The balancing machine operates as follows.

A balanced object 7 (for example, a rotor) is placed on prismatic supports 13, 12 and includes a drive (not shown) for shaft rotation. After the rotor is accelerated to the required speed, the process of measuring imbalance begins. In this case, the imbalance of the rotor 7 causes centrifugal forces, exciting vibrations of the rotor and cradles 2, converted by vibration sensors 3 into electrical signals, which are amplified and transmitted to the measuring unit 11. The phase meter gives one pulse for each revolution of the rotor during the passage of the "zero point". This provides information on the instantaneous angular position of the rotor to represent centrifugal forces in the polar coordinate system.

Based on the signals from the vibration sensors, the signal from the "zero point" sensor, the measuring unit displays information on the angles and amplitudes of imbalances on each measurement plane. After making the appropriate calculations, taking into account the accumulated measurement data and the matrix of dynamic influence coefficients, the measuring unit displays the masses and installation angles of the corrective (balancing) weights on each correction plane, taking into account the mutual influence of the planes. Based on the obtained values, the required correction masses are set, i.e. balancing is carried out in one of the known ways.

The oscillatory system of the machine (Fig. 2A and 2B), consisting of:

a) pivotally attached to point B of the tie rod 8,

b) pivotally attached to point A of the support rod 4,

c) pivotally connected at the ends with rods 8 and 4 of the cradle 2,

d) mass 7, mounted on the cradle 2. (7 - balanced object).

The hinges and axles of the rods 4 and 8 and the cradle 2 all lie in one plane, allow vibrations only in this plane (coincides with the plane of the picture).

If we take the mass of rods 4 and 8 and cradle 2 equal to zero, the friction and backlash in all hinges are equal to zero, then provided that the length BD is equal to the length AC, the center of mass of 7 coincides with point M lying on the segment CD, and the lengths of MD and CM are equal, then for small angular deviations of the rods from the vertical, the system has an indifferent equilibrium, i.e. infinite period of natural oscillations (zero frequency).

Consider the influence of the ratio of lengths (shoulders) in the system on the frequency of natural vibrations of the system. In this case, each time we will change only one length while maintaining the remaining lengths equal to the initial ones (as in the previous paragraph).

Reducing the length of B-D due to a downward shift of point B leads to the fact that the system acquires the property of stable equilibrium and the state when both rods are vertical is in equilibrium. In this case, the frequency of natural oscillations becomes greater than zero and monotonically increases with decreasing B-D length. An increase in the B-D length makes the system unstable; therefore, this case is not considered.

An increase in AC length due to a downward shift of point A leads to the fact that the system acquires the property of stable equilibrium and a state in which both rods are vertical is in equilibrium. In this case, the frequency of natural oscillations becomes greater than zero and monotonically increases with decreasing length A-C. Reducing the length of AC makes the system unstable, therefore, this case is not considered.

The increase in the length of SM due to the shift of the point M closer to the point D leads to the fact that the system acquires the property of stable equilibrium and the equilibrium state is when both rods are vertical. At the same time, the frequency of natural oscillations becomes greater than zero and monotonically increases with increasing length of C-M (and decreasing length of M-D). The reverse shift of point M towards point C makes the system unstable, therefore, this case is not considered.

Thus, by changing the ratios of the above lengths, it is possible to construct an oscillatory system with stable equilibrium and any previously set natural vibration frequency, provided that it will be less than the natural frequency of a commensurate mathematical pendulum for any set overall dimensions of the system.

The natural frequency of the system oscillations is determined during design.

It is possible to constructively provide for the operational restructuring of this parameter when setting up the machine for one or another type of balanced object. This can be realized through the use of rods 4 and 8 of adjustable length, by moving the place of laying (installation) of the balanced object 7.

Below are the results of calculations of the period of natural oscillations T and their frequency F for three variants of the following characteristic dimensions of the oscillatory system. For clarity, the value of the effective length L of the equivalent mathematical pendulum with the same natural frequency is also given.

As can be seen from a comparison of options 1 and 2, as well as 1 and 3, with small changes in the characteristic dimensions, significant changes in the natural frequency F. are achieved.

For comparison, option No. 4 is given — the oscillatory system of the prototype — the circuit in FIG. 2G. As can be seen from comparing the natural frequency F for options 1 and 4, the implementation of the oscillatory system of the proposed design with the indicated characteristic dimensions allows reducing the natural frequency by 4.52 times in the same dimensions. The same result using the design of the prototype could be achieved only with an increase in size by 20.3 times.

There may also be a balancing machine in which the oscillatory system consists of two, three or more of the single oscillatory systems discussed above. Moreover, these unit vibrational systems are located in parallel planes so that, in equilibrium, the points M of all vibrational systems lie on one straight line.

Claims (7)

1. A balancing machine containing a base, a flexible support placed on it, made in the form of a rack with a cradle to accommodate a balanced object, the cradle is hinged to the rack by means of rods and placed with the possibility of plane-parallel movement relative to the rack, a phase meter of rotation of the balanced object, a vibration signal sensor and measuring unit, characterized in that it is equipped with an oscillating system made in the form of at least one suspension and one support rod, so that the suspension rod is vertical These end attached swingably on a fixed part of the rack, and a lower end mounted swingably on a cradle, the support rods are fixed to the upper end pivotably on the cradle, and a lower end mounted pivotally to the fixed part of the rack. 2. The balancing machine according to claim 1, characterized in that it contains several racks with oscillatory systems. 3. The balancing machine according to claim 1, characterized in that the rods are made of adjustable length. 4. The balancing machine according to claim 1, characterized in that the place of laying (installation) of the balanced object is made with the possibility of movement. 5. Oscillating system of a predominantly balancing machine, comprising rods and a cradle for securing the mass, characterized in that the rods consist of suspension and support rods, so that the suspension rods with their upper end are fixed with the possibility of swinging on the fixed part of the rack, and the lower end are fixed with the possibility of swinging on the cradle, the support rods are fixed with the upper end with the possibility of swinging on the cradle, and the lower end is fixed with the possibility of swinging on the fixed part of the rack. 6. The oscillation system of the predominantly balancing machine according to claim 5, characterized in that the rods are made of adjustable length. 7. The oscillation system of the predominantly balancing machine according to claim 5, characterized in that the place of laying (installation) of the mass is made with the possibility of movement.

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