RU2456566C1 - Method for static balancing of rotor wheel of hydraulic turbine - Google Patents

Abstract

FIELD: physics.

SUBSTANCE: wheel centring is carried out on the side surface of the outer wall of the rim using a centre mark and supports in form of prisms which are rigidly attached to the working surface of platforms with force-measuring sensors, and forming at tangent points of the side surface of the wheel reference points for reading coordinates of the force-measuring sensors. The working surfaces of the platforms are set at the same horizontal level, and by loading the platform with the rotor wheel, its position is recorded by an upward vision video camera and the image is input into the computer of the measurement and result processing system. Using that system, which has signal converters and a controller, coordinates and values of loads on each platform are determined. Further, based on the obtained results, the centre of mass of the entire system is determined similarly. The obtained centre of mass coordinates are stored on the computer image of the outline of the rotor wheel, while determining disbalance, and balance weights are accurately installed.

EFFECT: high efficiency and accuracy of balancing.

5 cl, 9 dwg, 1 tbl

Description

The invention relates to hydraulic engineering, precision mechanics, measuring equipment and can be used to determine the coordinates of the center of mass and balancing products of complex shape.

To eliminate the imbalance of the impeller of a hydraulic turbine in all cases, various methods of technological balancing are used, which, however, do not provide the required level of accuracy due to the presence of existing errors, both during measurements and in the manufacture of impellers.

So known is a method of static balancing of the impellers of hydraulic turbines, performed on a stand of stable equilibrium, which consists of a support column, on the upper end of which a red-hot flat plate is fixed, which serves as a support for the swinging part of the stand.

In the body of the device, rigidly connected to the turbine wheel, a red-hot spherical support is strengthened and a set of interchangeable disks is placed, which is designed to regulate the position of the center of gravity of the system in height. To ensure a smooth lowering of the impeller to the support, hydraulic jacks evenly spaced around the circumference are used. If it is necessary to unload the stand, the impeller is lifted with the help of jacks, and then lowered onto the gaskets installed between its lower end and measuring stands. In order to ensure the swing of the balanced system near the position of stable equilibrium, the spherical support in the device is set so that the center of gravity of the system is below the center of the sphere.

The equilibrium equation of such a system, assuming that the center of gravity moves along an arc of a circle, is as follows:

P · R-G · Z · sinα-G · µ = 0,

where P is the mass of the balancing load, kg;

R is the radius of the balancing load, cm;

G is the mass of the balanced system (taking into account the mass of the device), kg;

Z is the distance from the center of gravity of the system to the center of the sphere, cm;

α is the angle of deviation of the system from the vertical axis;

µ is the coefficient of friction of rolling.

The technological process of balancing the impellers of hydraulic turbines is carried out in the following sequence.

The support column is set on the assembly plate so that the working surface of the flat red-hot plate is horizontal when checked by level. The impeller with the fixture mounted on it is mounted on measuring cabinets with gaskets so that the axes of the impeller and the support column are approximately the same, and between the spherical support and the flat plate there is a gap of 5-10 mm, then the wheel is lifted with jacks, the gaskets are removed and again lowered to the contact between the supports of the device, forming a gap between the rims of the impeller and the pedestals of 10-15 mm. After that, the actual position of the center of gravity of the system is determined, and the application of the minimum moment checks the sensitivity of the device. Next, two levels are set on the upper end of the impeller rim in two mutually perpendicular directions, with the help of which the angle of inclination of the balanced system to the horizon is determined. Laying in special cavities made on the upper or lower rim of the impeller, balancing the mass, the system is brought into a horizontal position. Moreover, the static moments created by the masses of levels must be compensated by the corresponding oppositely directed moments. The necessary balancing mass is calculated by the formula:

P = G · (Z · sinα-μ) / R

(see symbol in the above formula.)

(see G.A. Bronovsky, A.I. Goldfarb. Hydroturbine technology, Leningrad, Mechanical Engineering, 1978, p. 294-298).

The main disadvantages of this technical solution are low productivity and a large measurement error caused by the presence of subjectivity in assessing the vector and the magnitude of the wheel unbalance, due to the lack of installation automation, calculation of parameters and control over the course of balancing.

There is also known a method of static balancing of a hydraulic unit, which is carried out as follows. The hydraulic unit is centered in the guiding segment bearings, dynamometers are installed under its rim, the bearing segments are bred, the rim is lowered onto the dynamometers and the unbalance value is determined from their readings from the following ratios:

where S is the static moment of the unbalanced mass;

P _i - the force acting on the i-dynamometer;

n is the number of dynamometers;

X _i and Y _i - coordinates of the installation of dynamometers;

φ is the angle showing the direction of displacement of the center of mass.

After that, eliminate the imbalance by setting the balancing weight, the static moment of which is equal to S, and the installation angle is

φ ₂ = φ + π

(see USSR author's certificate No. 1150391, F03В 11/04, publ. 15.04.85, bull. No. 14).

However, this method also has the same drawbacks, namely low productivity and insufficient accuracy of parameter measurement due to the lack of automation of the entire process of balancing the unit.

The above analogues are consistent with the invention only for its intended purpose, i.e. to eliminate the imbalance of the impeller of a hydraulic turbine, but the operations themselves, the sequence of their execution, as well as the means of implementing the method are completely different, therefore, an analogue according to copyright certificate No. 1150391, F03B 11/04, publ. 04/15/85, bull. No. 14.

It became possible to solve the problem of eliminating the disadvantages of analogues by automating the entire process of balancing the impeller of a hydraulic turbine, or by using the method using the original design of measuring platforms.

EFFECT: increased productivity and balancing accuracy is achieved due to the fact that the impeller is centered on the lateral surface of the outer wall of the rim using a spring-loaded target core and stops in the form of prisms rigidly mounted on the working surface of the platform with force measuring sensors and forming a lateral touch point the surface of the wheel reference points of reference coordinates of the location of the load sensors, while all load sensors, and accordingly working surfaces platforms exhibit one horizon level. Having established a horizon level uniform for all platforms, then they are loaded, the wheel is fixed with an overhead camera, its image is entered into a computer of the measurement and processing system, and using this system, including signal converters and a controller, the coordinates and radius vector of the load application are determined attributable to each platform. Then, on the basis of these measurements, the center of mass of the entire wheel is determined similarly, and the resulting center of mass is superimposed on the computer image of the impeller contour, and then, taking into account the location of its imbalance, balancing weights are precisely set. The method also differs in that the system of measurements and processing of their results is formed from signal converters by the number of force sensors connected to the controller connected to the computer. As load sensors use strain gauge sensors.

The technical result of the method is also ensured by the fact that the force sensors coordinate on the platform surface according to the measuring range of the impeller mass, placing them graphically at the measurement value at the vertices of the squares displaced relative to each other. The accuracy of the positioning of the platforms relative to the impeller is performed using sight lines on their working surface.

In addition, the proposed method allows you to expand the balancing range of the impellers of hydraulic turbines of almost all existing sizes, since it provides unlimited ability to move the platforms relative to the measurement base - the side surface of the impeller rim, as well as the possibility of grouping force sensors according to their nominal value, placing them graphically at the vertices two squares offset relative to each other.

Three platforms with a range of 10 tons each (with three marks) are used with a turbine impeller weighing up to 30 tons and with a range of 50 tons each with a weight of 40 to 150 tons, and four platforms with a range of 10 tons each (with four points) are used for weighing from 30 to 40 tons and with a range of 50 tons each above 150 tons.

The method of static balancing of the impeller of a hydraulic turbine is new, since in the information sources the totality of the proposed features reflected in the claims, including in additional paragraphs, is not found.

The proposed method, as a technical solution, has an inventive step, because the combination and sequence of its actions using computer-aided calculation of parameters and video monitoring of the balancing process, orientation using the original design of the platforms with a special placement of power sensors can significantly increase the performance and accuracy of measurements, and moreover, it allows not only to automate the balancing process, but also due to the oriented application of the platforms, expand the balancing range to almost all known standard sizes of working their wheels of hydraulic turbines, which, in our opinion, cannot be attributed to the methods of conventional engineering design, and the combination of the video image of the wheel with the calculated position of the center of mass and the direction of the radius vector of the imbalance in relation to hydraulic engineering is not obvious.

According to the invention, a technical project was developed, platforms were made, their tests were carried out, positive results were obtained confirming the receipt of a technical effect, and a methodology was developed for balancing the impellers of hydraulic turbines by the weight method.

The invention is illustrated by drawings, in which Fig. 1 shows a diagram of the installation of the impeller assembly at its balancing position, Fig. 2 shows a complete assembly with load cells, stops and target core (top view), Fig. 3 shows a section along A -A in figure 2, in figure 4 and figure 5 - the impeller mounted on 3 and 4 platforms, figure 6 presents the layout of the load cells in a small measurement range with an inclination to the axis Y, Fig.7 - the same larger measuring range with a deviation from the Y axis, and Fig.8 and Fig.9 rendered the mass center position circuit impeller with 4 and 3 platforms.

The kit for oriented static balancing of the impeller of a hydraulic turbine includes a platform 1 with load cells 2 and 3, a video camera 4 top view and a system for measuring and processing their results, including signal converters (not shown) of each load cell 2 and 3 connected to the controller 5 connected to the computer 6. The platforms 1 are square in shape with angular bevels 7, mainly at an angle of 45 °, and corresponding schemes of displacements on their working surfaces 8 of force measuring sensors 2 of small weight (3 t) and sensors 3 of large weight (15 t). The placement of the load sensors 2 and 3 is oriented along the X and Y axes relative to the corner joints 9 of the bevels 7 and each of them is graphically located at the vertices of its square 10.

In the technical means used for alignment, including for platforms 1, the placement schemes of load sensors 2 and 3, shown in Fig.6 and 7, are used.

The arrangement (Fig. 6) of the arrangement of load cells 2 on a small measuring range with a 3 t NPI has an inclination towards the Y axis, and the arrangement (Fig. 7) of the arrangement of force transducers 3 with a large measuring range with a 15 t NPI is opposite from the Y axis.

Thus, the load cells 2 and 3 are grouped on the platform 1 according to the measuring range of the wheel mass, graphically placing them for ease of use at the measurement value at the vertices of the squares displaced relative to each other. The design of the platform 1 itself includes a lower base 11, on which sensors 2 and 3 are mounted, a support adjustment mechanism 12 and an upper base closing them 13. By adjusting the support mechanism 12 of the sensors 2 and 3, the platform is leveled to a horizontal level for any measuring range, in particular from 10 to 50 tons of the weight of the impeller of a hydraulic turbine (figure 3).

For oriented installation of the platform 1 relative to the impeller on its working surface 8 of the upper base 13, two stops 14 and a spring-loaded target core 15 are rigidly mounted, forming reference points A, B, C and F at the touch points of the side surface 19 and the rim 20 of the impeller the coordinates of the location of the load sensors 2 and 3. The stops 14, made in the form of prisms, and the target core 15 are motionlessly interconnected by a strip 16.

Sighting lines 17 and 18 are drawn on the working surface 8 of all platforms 1, and on the side surface 19 of the impeller rim 20, these lines are marked depending on the weight of the wheel, which is applied in the form of vertical strokes placed equidistant from each other. With the weight of the impeller up to 30 tons and with a weight of 40 to 150 tons, three marks at an angle α = 120 °, and with a weight in the range from 30 to 40 tons and more than 150 tons, four marks are applied at an angle β = 90 °.

Each platform 1 is adjusted so that the dimensions between the reference points A, B, C and F are constant and equal for all platforms, and the retractable sighting core 15 is located on any line of sight drawn on the side surface of the rim and the working surface 8 of the upper base 13 The marking and installation of the stops 14 is carried out relative to the sensors 2 and 3 on all platforms 1 equally, forming a single coordinate system relative to the axes X and Y.

In platforms 1, for working on the first or second ranges, a group of sensors 2 or 3 is used, respectively. Tuning to a range (10 or 50 t) is carried out by removing from the contact of the upper supports of the regulation mechanism 12 of one of the sensors and replacing them with others, while ensuring the same signal to each sensor.

The design of the platforms 1 is such that each of the sensors 2 or 3, mounted on the lower base 11, is connected to a separate normalizing converter (not shown in Fig.), And the outputs of all the transducers are connected via a serial interface to a controller 5. Thus, when a load is applied to the platform, the radius vector of the load application can be determined on each of the four sensors of 2 or 3 ranges by the output code G _i :

or the coordinates of its application to the j-th platform:

Then the center of mass of each platform 1 will be determined by the following formula:

1. On a small range, sensors with NPI 3 t (scheme 1) along the X and Y axis

where X is _{the cm} - the center of mass of the platform along the X coordinate;

X _1.1 ; X _1.2 ; X _1.3 and X _1.4 are the coordinates of each of the four sensors on the platform;

G ₁ ; G ₂ ; G ₃ and G ₄ - support reactions on each of the four platform sensors. Similarly, along the Y axis, all the source coordinates and reactions of the supports are read.

2. Over a wide range of sensors with NPI 15 t (scheme 2)

where X is _5.1 ; X _5.2 ; X _5.3 and X _5.4 - the coordinates of each of the four sensors on the platform along the X axis;

Y _5.1 ; Y _5.2 ; Y _5.3 and Y _5.4 are the coordinates of each of the four sensors on the platform along the Y axis;

G _R - the weight of the impeller per each platform;

X _ts.m. and Y _ts.m , - coordinates of the center of mass of each platform.

The top-view video camera 4, which is mounted on a console with the possibility of rotation on the rack 21, is connected to the computer 6 and is designed to fix the position of the impeller installed at the balancing position with the subsequent introduction of its image on the display of the said computer 6.

To transport the installation to the position of balancing of the impeller, it is equipped with a temporarily used device 22.

The method of static balancing the impeller of a hydraulic turbine is as follows.

The installation of platforms 1 under the impeller, in limbo, is carried out by sliding until the fixed stops 14 and the sighting core 15 touch the side surface 19 of the rim 20. In this case, the positioning of the platforms 1 relative to the center of rotation of the impeller is observed. The platforms 1 are installed with a sighting line 17 or 18 according to the marking risk applied to the outer rim 20 of the impeller and are accurately positioned by the stops 14 and the sighting core 15, forming reference points A, B, C and F of the reference coordinate location of the load sensors 2 and 3. In this case all load cells 2 and 3, and accordingly the working surfaces 8 of the platforms 1 are set to the same level of the horizon, after which the platforms 1 are loaded with a balanced wheel, the position of the impeller is recorded by the video camera 4 of the upper view and emit it in the computer image measurement system 6 and the processing results.

When the platforms 1 are loaded with the impeller, the signal from each sensor 2 or 3 is sent to the controller 5 and fed to the computer 6, automatically determining the coordinates of each sensor and the corresponding load on each platform 1. Due to the fact that each of the platforms 1 has four interrogated sensors each measurement range, this allows you to determine the coordinates of the application of forces on the platform as a whole without significant errors, and therefore, it is sufficient to accurately determine the center of mass and the vector of application of forces of the entire platform 1.

When balancing the impeller of a hydraulic turbine, three or four platforms 1 will be used depending on its weight.

The initial values for the calculations will be the values of the load vectors determined for each platform 1 in accordance with the above formulas (1, 2, 3).

The position of the center of mass of the impeller as a whole is determined by the formulas:

where X _rk - the coordinate of the center of mass of the impeller along the X axis;

Y _p.k - coordinate of the center of mass of the impeller along the Y axis;

X _ni is the coordinate of each platform along the X axis;

Y _ni is the coordinate of each platform along the Y axis;

- вес рабочего колеса, приходящийся на каждую платформу;

- the weight of the impeller per each platform;

- статический момент рабочего колеса от каждой платформы по оси Х;

- the static moment of the impeller from each platform along the X axis;

- статический момент рабочего колеса от каждой платформы по оси Y;

- the static moment of the impeller from each platform along the Y axis;

- общий вес рабочего колеса.

- the total weight of the impeller.

The image of the impeller housing on the computer monitor 6, obtained using the top-view video camera 4 mounted on the console rack 21, shows the coordinate of the center of mass of the impeller housing and the radius vector

,

,

the connecting center of the impeller housing and its center of mass. The radius r, on which the balancing weight can be installed, is specified constructively.

The diagrams conventionally show the position of the center of mass of the impellers, the magnitude and radius of their imbalance relative to the X and Y axes with four and three platforms (Fig. 8 and Fig. 9).

In accordance with schemes 3 and 4, the radius of imbalance is determined by the formula:

Accordingly, the moment arising due to the mismatch of the center of mass and the axis of rotation of the wheel will be:

where G _pk = G ₁ + G ₂ + G ₃ -G ₀ or G ₁ + G ₂ + G ₃ + G ₄ -G ₀ ;

R is the radius of the displacement vector of the axes of rotation and the center of mass;

G ₁ , G ₂ , G ₃ , G ₄ - the weight of the impeller attributable to each of the platforms 1;

G ₀ - the weight of the device 22.

To perform balancing, a balancing weight is precisely imposed, the mass of which is determined from the equation:

where G _b - balancing load;

r is the radius of the wheel;

R _∂ is the imbalance radius;

G _PK is the weight of the wheel.

Thus, in the process of carrying out the static balancing of the impeller, the system for measuring and processing the results automatically indicates on the computer monitor 6 the position of the center of mass relative to its rotation axis, and also determines the value of X _r.k. , Y _p.k. and R, and if R is found, it accurately sets the weight and location of the balancing weight, which increases the productivity of the unbalance measurements of the hydraulic turbine.

The proposed method provides high accuracy of balancing the impeller, as it has a low degree of measurement error and a high sensitivity threshold for torque, which are ensured by the constructive construction of platform 1 as a whole, as well as by the precise installation of force sensors 2 and 3 and emphasis prisms 14 on its working surface 8 and its non-verticality.

The calculations of the accuracy of positioning the platforms 1 under the impellers of turbines with a weight of 15, 40, 150 and 200 tons with a marking error of 0.5 mm are summarized in table 1.

An analysis of the results of calculating the positioning of the platforms in table 1 shows that the total sensitivity threshold for the moment of balancing for all impellers under consideration remains on average 1.5 times lower than the permissible value.

Therefore, the proposed method allows to increase the performance and accuracy of balancing the impellers of hydraulic turbines and to further expand the range of their balancing through the use of platforms with force measuring sensors of the original design, the use of software measurement and evaluation results.

Currently, these platforms are designed and manufactured in production, their tests have been carried out, and positive results have been obtained. A technique for balancing the impellers of hydraulic turbines by the weight method has been developed.

Claims (5)

1. The method of static balancing of the impeller of a hydraulic turbine, characterized in that the centering of the wheel is carried out on the side surface of the outer wall of the rim using a spring-loaded target core and stops in the form of prisms, rigidly mounted on the working surface of platforms with force sensors and forming at the touch points of the side surface wheels are reference points of reference for the coordinates of the location of load sensors, while all load sensors, and, accordingly, working rotations the platform values are set to the same level of the horizon, after which the platforms are loaded with a balanced wheel, the impeller is fixed with a top-view camera, its image is entered into the computer of the measurement and processing system, and using this system, including signal converters and a controller, the coordinates and value are determined the load attributable to each platform, and then on the basis of these obtained results, the center of mass of the entire wheel is determined similarly, and the coordinates obtained Inats of the center of mass impose the impeller contour on a computer image, determine the imbalance, precisely set the balancing weights. 2. The method according to claim 1, characterized in that the measurement system and the processing of their results are formed from signal converters by the number of load sensors connected to the controller connected to the computer. 3. The method according to claim 1, characterized in that as load cells use strain gauge sensors. 4. The method according to claim 1, characterized in that for the exact positioning of the platform relative to the impeller using sight lines applied on its working surface. 5. The method according to claim 1, characterized in that the load cells coordinate on the surface of the platform according to the measuring range of the mass of the impeller, placing them at the nominal value at the vertices of the squares offset from each other.

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