RU2295821C1 - Method for diagnostics of planting tightness of tread rings on the barrel of rotor of electric machine - Google Patents

Abstract

FIELD: electric engineering, electro-mechanical industry, in particular concerns features of monitoring values of planting tightness of tread rings of rotors of large electric machines, such as turbo generators.

SUBSTANCE: in accordance to method, estimate of condition and change of planting tightness (Δδ_ring) is determined from expression: (Δδ_ring)=K_D(D_ext.con. - D_ext.or.), where D_ext.con. and D_ext.or. are external diameters of tread rings in planting zones, altered respectively during planned operation halt period of electric machine and duplicating control after planting of tread rings; K_d=δ_ring/(D_ext.or. - D_ext.free) - experimental deformation coefficient, where D_ext.or. and D_ext.free are, respectively, external diameters of tread ring in zone of its planting onto rotor barrel before disassembly of tread unit being in free state, when tread ring is removed and tightness equals zero; δ_ring - calculated tightness, determined by means of measuring during assembly and disassembly of tread unit and subtraction of mated diameter of rotor barrel (D_bar.r.) and internal planting diameter of planting surface of tread ring (D_ring.ext.) with usage of expression: δ_ring=(D_bar.r. - D_ring.ext.).

EFFECT: possible diagnostics of condition of planting tightness in tread ring unit without its disassembly while simultaneous increasing precision of measurements.

3 cl, 1 dwg

Description

The invention relates to the technology of electrical engineering, in particular to the control of the fit of the interference fit of the hot fit of the retaining rings of the rotors of large electrical machines, such as turbogenerators.

A known method of measuring interference in the retaining unit, shown in [1]. To determine the interference fit by this method, a complete disassembly of the retaining assembly, measurement of the diameters of the mating parts and comparison of the results with factory dimensions are required. The method is very time-consuming and not always feasible according to the operating conditions of the electric machine and economic opportunities.

The closest analogue to the prototype of the invention is a method for diagnosing the state of the interference fit in the retaining unit, given in [2]. According to this method, the diagnosis of the condition of the interference fit in the interface between the retaining ring and the rotor in its end part is carried out without disassembling the retainer assembly and includes determining the change in interference (Δδ _band ) in the turbine generator retainer assemblies by comparative measurements of the outer diameters of the retainer rings in the places of their fit before putting the turbogenerator into operation and during repair work, according to the formula:

D _beginning and D _nar.con. - the outer diameters of the retaining rings, measured respectively before landing and after landing on the end part of the barrel of the rotor when assembling the retaining assembly or during the planned shutdown of the turbogenerator compared to previously performed measurements,

λ _mouth. and λ _gangs. - accordingly, the ductility coefficients of the rotor barrel and the retaining ring at the landing site, taking into account the fact that when the retaining ring is hot-seated on the rotor barrel, the amount of plastic deformation in the radial direction (change in landing diameters) is proportional to the ductility coefficients of the rotor barrel and the retaining ring at the landing site.

The disadvantage of this method is the need to take into account the different ratios of the estimated yields of the rotor components mated by hot landing: the retaining ring and the end part of the rotor barrel, as well as the use of the calculation method for their calculation, which introduces significant errors in the calculation of the true values of the interference fit in the retainer assembly.

The proposed diagnostic method is devoid of these disadvantages. The technical result to which this invention is directed is to diagnose the state of the interference fit in the retainer assembly without disassembling it with increasing measurement accuracy.

The drawing shows the bandage assembly of the rotor of the turbogenerator containing the winding (1), the barrel of the rotor (2) and the retaining rings (3), the back of which is mounted on the centering ring (4), and the nose part on the end parts of the barrel, for example, through an insulating gasket ( 5). The coupling of the retaining ring with the barrel of the rotor is carried out by hot landing with an interference fit (δ _band ), and with the centering ring with an interference fit (δ _center ), the necessary values of which are determined by mechanical calculation. The use of a hot landing is due to the need for a tight connection of the parts of the retaining assembly, primarily at the operating speed.

Values of D _gangs. and d ' _gangs. - respectively, the outer diameters of the retaining ring in the area of its landing on the barrel of the rotor and the centering ring.

When the retaining ring is planted on the end part of the rotor barrel through a multilayer insulating gasket due to its delamination, as well as due to the burning of combustible components of the insulating gasket at high heating temperatures of the retaining rings, tension can be weakened. This deviation of the tightness of the retaining ring is very important to diagnose in a timely manner.

In the event of the aforementioned defects, as well as in case of burns and riveting of metal in the landing zones of the retainer assembly, the interference is weakened with a decrease in the outer diameter of the retainer ring in the area of hot landing on the rotor barrel.

The indicated change in the outer diameters of the retaining rings will be fully identical to the change in the magnitude of the interference fit, if we take into account with a high degree of certainty the influence on the measurement of the difference in diameters of the ductility of the components of the retaining assembly mating with a hot fit that are different not only for different types of electric machines of different series of the same type, but often have individual values even for identical machines of the same series electrically. The degree of reliability of determining the ratio of these compliance actually determines the error in diagnosing the state of landing interference by the proposed method. Therefore, it seems most promising to determine the magnitude of the ratio of these compliance experimentally for each diagnosed electric machine

Therefore, in order to improve the accuracy of measurements, the assessment of the state and changes in the interference fit (Δδ _band. ) Is determined from the expression:

Here D _nar.nach. and D _nar.con. - the outer diameters of the retaining rings in the landing zone, measured respectively during the duplicate control after landing of the retaining rings and during the planned shutdown of the electric machine.

Initially, experimentally determine the correction coefficient of deformation (Cd) to the difference in diameters (D _b.d. and D _b.con. ) To obtain reliable values of the interference fit (δ _band. ) And its changes (Δδ _band. ) By the ratio: Cd = δ _gangs. / (D _add. - D _add. ), Where

D _beginning and D, _freed. - accordingly, the outer diameters of the retaining ring in the area of its landing on the barrel of the rotor before disassembling the retaining assembly in the assembled state and in a free state (the retaining ring is removed, the interference is zero);

δ _gang. - the calculated interference fit, determined in the traditional way by measuring when assembling or disassembling the retainer assembly and subtracting the diameters of the mating components - the outer barrel of the rotor (D _barrel ) and the inner - retaining ring (D _band.v. ).

δ _gang. = (D _b.r.- D _gang .).

In the presence of an insulating gasket under the spout of the retaining ring, the calculated landing interference, determined in the traditional way, is calculated by the formula: δ _gang. = (D _barrel.- D _band.vn. ) + 2σ, where σ is the thickness of the gasket.

The proposed method allows you to check the current condition of the interference _fit (δ _{band. Tech.} ), Determining its change (Δδ _band. ) During operation of the electric machine without removing the retaining, when measuring the outer diameter of the retaining rings (D _nar.kontek. ) compared with previously performed measurements (D _beginning ).

Relation (1) also indicates that for a particular electric machine, a specific value of the retaining interference of the retaining ring on the rotor barrel (δ _gang ) corresponds to a completely defined value of the outer diameter of the retaining ring in the area of its fit (D _beginning ). Hence, the possibility arises of performing duplicate control of the actual value of the fit of the interference fit during the assembly of the rotor and putting on the retaining rings to identify technological deviations in the assembly process of the retaining assembly. These deviations can be detected by the deviation of the outer diameter of the retaining ring (D _{add. Act.} ), Measured with duplicate control, from the standard value (D _{add. Norm.} ), Corresponding to the standard value of the interference fit.

Duplicate control to detect deviations of the fit of the retaining ring retaining rings on the rotor barrel after the assembly of the retaining band uses the ratio (1) with some clarification:

At the same time, for example, if when disassembling the retaining assembly, the normative value of the seating tension and the outer diameter of the retaining ring at the place of its seating were fixed, then later on after assembling the retaining assembly, as well as during operation of the electric machine, you can constantly use this fixed normative value of the seating interference and the corresponding value of the outer diameter of the retaining ring.

When assessing the technical condition of the seating interference of the retaining ring on the rotor barrel, it is often very important to determine how much the landing diameter of the rotor barrel has decreased and the mounting diameter of the retaining ring in the process of their mutual connection has increased to the total diameter of the landing joint (D _{band.vn.total} ). This assessment can be made by experimentally determining the change in the outer diameters of the retaining rings in a free (D _outfit ) and assembled (D _outfit ) condition and calculating the values of the experimental ductility coefficients of the retaining rings (λ _band. ) And the rotor barrel (λ _mouth. ) in the area of their mating with a hot landing according to the ratios:

L _village , P, E, μ - respectively, the length of the landing surface, the specific pressure on the landing diameter, the modulus of elasticity of steel and the Poisson's ratio;

K = D _gang. / D _freed

It should be noted that when the proposed diagnostic method is used at different times, it is necessary to maintain the same temperature of the components of the retaining unit or to enter the necessary temperature corrections into the measurements.

In a similar way, one can determine the fit of the retaining rings of the retaining rings on the centering ones (δ _center.tech ) and change them without disassembling the retaining assembly, for which, in relations (1) and (2), instead of the data of the rotor barrel, the data of the centering ring are entered.

Information sources

1. Handbook for repair of turbogenerators. Edited by P.I.Ustinov. - M .: Energy, 1978, p. 258.

2. Patent for the invention of the Russian Federation "Method for diagnosing the condition of the interference fit of retaining rings on the components of the rotor of an electric machine (options)" No. 2145144, 09/09/1999

Claims (3)

1. A method for diagnosing the condition of tightness of retaining rings on the rotor components of an electric machine containing a rotor barrel, a winding and centering rings, including assessing the change in tightness at the seats of the retaining rings by comparatively measuring the outer diameters of the retaining rings in the area of their fit, measured respectively before starting the electric machine in operation (D _nar.nach.) and during operation while it is stopped (D _nar.kon.), characterized in that the assessment of the state changes and the landing interference (Δδ _bands.) Definition determined from the expression Δδ _gang. = K _d (D _nar.con. -D _nar.nach. ), where K _d = δ _gang. / (D _beginning- D- _free ) - experimental strain factor; D _beginning and D _nar.svobod - respectively, the outer diameter of the retaining ring in the zone of its landing on the barrel of the rotor before disassembling the retaining assembly and the outer diameter of the retaining ring in a free state when the retaining ring is removed and the interference is zero; δ _gang. - the calculated tightness determined by measuring during assembly and disassembly of the retainer assembly and subtracting the mating diameters of the rotor barrel (D _barrel ) and the inner bore diameter of the seating surface of the retaining ring (D _band.v. ) using the expression: D _bands. = (D _b.r.- D _gang .). 2. The method according to claim 1, characterized in that the condition and changes in the seating interference fit (Δδ _band ) are evaluated while performing a duplicate control of the actual value of the interference fit value during the assembly of the rotor and putting on the retaining rings and identifying technological deviations according to the ratio: _{Δδ band double} = K _d (D _normal. -D _normal. ), where D _nar.norm. and D _nar.fact - the outer diameters of the retaining ring in the area of its landing on the rotor barrel, measured respectively at the standard value of the interference fit and when performing duplicate control. 3. The method according to claim 1, characterized in that when assessing the condition of the seating interference fit (Δδ _band. ), The experimental values of the ductility coefficients of the retaining rings (λ _band. ) And the barrel of the rotor (λ _mouth. ) In the zone of their mating hot landing are determined by the ratios :

Where

L _village , P, E, μ - respectively, the length of the landing surface, the specific pressure on the landing diameter, the modulus of elasticity of steel and the Poisson's ratio; K = D _band.vn ./D _nar.svob. ; D _gang. - the diameter of the landing surface on the barrel of the rotor and the retaining ring after landing; (D _band.vn. ) - the inner bore diameter of the seating surface of the retaining ring.