JB/T 6752-1993 Specification for static balance test of small and medium-sized turbine runners
Some standard content:
Mechanical Industry Standard of the People's Republic of China
Small and Medium-sized Water Turbine Runner Static Balance Test Procedure Subject Content and Applicable Scope
JB/T6752—1993
This standard specifies the balancing method, balancing quality grade and corresponding inspection method for the static balance of small and medium-sized water turbine runners. This standard is applicable to the inspection and acceptance of the balancing quality of axial flow, mixed flow, bucket and oblique impact water turbine runners with power equal to and less than 10MW. The runners of tubular, diagonal flow and double-stroke water turbines and pump turbine runners, as well as flywheels, rotating oil pans and other rotating parts of water turbines can be used as a reference.
2 Reference standards
GB2900.45
Electrical terminology Hydro turbines, water turbines and storage pumps GB6444
GB8564
GB9239
Balance vocabulary
Technical specification for installation of hydro-generators
Balance quality of rigid rotors Determination of allowable imbalance 3 Runner balancing conditions, allowable unbalance and balancing quality grade 3.1 Runner balancing conditions
The scope of application of static balance is expressed by the relationship between the runner size ratio b/D (b-runner height, D-runner maximum outer diameter) and the runaway speed n.
0.10.20.30.61.015235710
Runaway speed n, (×10°r/min)
The wheels below curve 1" in Figure 1 only need static balancing. The wheels above curve "2\ must be dynamically balanced. The wheels between curve "1" and curve "2" must be determined whether dynamic balancing is required based on factors such as the weight of the wheel, manufacturing process, processing conditions (partial processing or full processing) and the distance between the bearings.
3.2 Runner mass and permissible unbalance
Generally speaking, the larger the runner mass, the larger the permissible unbalance. Therefore, it can be expressed by formula (1): Approved by the Ministry of Machinery Industry on August 21, 1993
Implementation on October 1, 1993
-Permissible mass eccentricity, um;
Where: ep-
U--Permissible unbalance, g, mm;
M--Runner mass, kg.
3.3 Runaway speed and permissible unbalance Balance record
JB/T6752—1993
The allowable unbalance degree (i.e., allowable mass eccentricity) of the runner is generally inversely proportional to the runaway speed (angular velocity) of the runner, i.e.: cp.wconst.
In the formula, -
corresponds to the angular velocity (rad/s) at the maximum runaway speed of the turbine n, wn,/10. 3.4 Balance quality level
This regulation recommends that the balance quality level of the runner of small and medium-sized turbines be G4, with 4 mm/s. The balance quality level is expressed by formula (3): G=Cmr
is the balance quality level, mm/s.
Where: G-
3.5 Allowable unbalance
The allowable unbalance U of the runner of small and medium-sized turbines can be calculated according to formula (4): Um=4X10*·M
If the allowable unbalance mass at the maximum correction radius is less than 15g, take 15g.Static balance
The static balance of the runner is divided into horizontal static balance and vertical static balance. 4.1 Horizontal static balance
4.1.1 Scope of application
4.1.1.1 Generally, the runners of mixed flow turbines with D,<140cm and axial flow turbines with D,<200cm. 4.1.1.2 Impulse, oblique impact and double impact turbine runners. 4.1.2 Horizontal static balancing device
Figure 2 Schematic diagram of horizontal static balancing device
1. Rotating wheel
2. Special balancing mandrel
3. Blade support
4. Bracket
5. Platform
Several requirements for horizontal static balancing device: JB/T6752—1993
4.1.2.1 The blade width B of the blade support should be selected according to Table 1. Table 1
Weight of rotating wheel
≤300
>300~2000
Blade width
4.1.2.2 The length L of the working surface of the blade support ≥7d (d is the shaft diameter at the contact point between the two ends of the special balancing mandrel and the blade support). 4.1.2.3 The maximum allowable value of the roughness parameter Ra of the working surface of the blade support is 0.4μm. 4.1.2.4 The maximum allowable value of the journal roughness parameter Ra at the contact point between the two ends of the special balancing mandrel and the blade support is 0.8μm, and the hardness shall not be lower than HRC45.
4.1.2.5 The flatness of the working surface of the blade support shall not exceed 0.02mm/m. The horizontal non-parallelism of the working surfaces of the two blade supports shall not exceed 1mm/m. 4.1.2.6
The flatness of the surface composed of the working surfaces of the two blade supports shall not exceed 0.04mm/m. 4.1.2.7
4.1.2.8 The hardness of the working surface of the blade support shall not be lower than HRC56~60. The coaxiality tolerance grade of the special balancing mandrel and the runner shall not be lower than grade 7. 4.1.2.9
4.1.2.10 Any other horizontal static balancing device or horizontal balancing machine with higher accuracy than the above requirements may be used. 4.1.3 Balancing method
The horizontal static balancing of the turbine runner is carried out in two steps: initial balancing and fine balancing. 4.1.3.1 Initial balancing
After assembling the runner and the special balancing mandrel, hang it on a balancing device that meets the above requirements and place the mandrel axis in a vertical position with the blade support length a.
direction
Rotate the runner to the left and right several times to correctly determine the unbalance angle (direction): Add weights to the runner until the entire balancing system appears to be in random balance; c.
If the actual weight position is different from the position of the measured unbalanced mass, it can be calculated according to formula (5): d.
M..R.-m·r
Where, M,-actual weight, g; R,--the distance between the center of mass of the actual weight and the rotation axis of the runner, mm; m*
measured unbalanced mass, g;
r--the distance between the center of mass of the measured unbalanced mass and the rotation axis of the runner, mm. 4.1.3.2 Fine balancing
Reinstall the wheel after initial balancing on the mandrel, hang it on the blade support, rotate the wheel to the left and right several times, check the balance quality, and adjust the remaining unbalance of the wheel until it is less than the allowable unbalance. 4.1.4 Check the balance quality
4.1.4.1 Divide the lower ring of the wheel or the end face of the wheel body into eight equal parts. When placing the wheel, first make any straight line passing through the center of rotation (such as 1-5 in Figure 3(a)) in a horizontal position. bZxz.net
4.1.4.2Add a test mass m(g) at the radius of mark (1) r(mm). Its size should just make the wheel tend to rotate to the left. This test mass is recorded as m1. If the wheel has already rotated to the left along the blade support without adding the test mass, a test mass should be added at the mark (5) opposite to mark (1). Its size should make the wheel still have the tendency to rotate to the left. This test mass can be recorded with a minus sign (-m). In this way, the minimum test mass m or -m1 for leftward rotation is completed at each angular position. 4.1.4.3 Similarly, the minimum test mass m or -mz required for each angular position when the wheel rotates to the right must be determined. 16
JB/T6752—1993
4.1.4.4 During the inspection, the distance r between the center of mass of the added test mass and the axis of rotation of the wheel should remain unchanged. 5
4.1.4.5 At each equally divided position, make points for the added test mass, and draw curves through these points (m, is a solid line, m: is a dotted line), and obtain two approximately sinusoidal curves (as shown in Figure 3(b)). 4.1.4.6 When the wheel rolls to the left, the residual unbalanced mass at r is measured: m,=(mimax+mmie)/2
When the wheel rolls to the right, the residual unbalanced mass at is measured: mz=(mzmx+mmin）/2
4.1.4.7 If m; and m: have the same absolute value, the balance can be considered accurate; if m; and m; have different absolute values, take their arithmetic mean as the residual unbalanced mass measured at ", that is: m=（| m,/+|m()/2
4.1.4.8 If mr≤Ur, the runner is considered qualified, otherwise it must be recalibrated until mr≤U. 4.2 Vertical static balancing
4.2.1 Scope of application
Generally, the runners of mixed flow turbines with D,≥140cm and axial flow turbines with D,≥200cm, 4.2.2 Vertical static balancing device
Requirements for vertical static balancing device, (8)
4.2.2.1 The balancing ball and balancing base plate shall be processed by forging steel roughness, and the hardness shall not be lower than HRC56-60. The maximum allowable value of the surface roughness parameter Ra is 0.4μm, and the local surface depression shall not exceed 0.03mm. 17
JB/T6752—1993
Figure 4 Schematic diagram of the static balance test device for the runner of a Francis turbine 1. Measuring dial gauge 2. Runner 3. Counterweight 4. Pressure plate 5. Balancing bracket 6. Adjusting screw 7. Screw sleeve 8. Centering plate 9. Balancing plate 12
10. Balancing ball 11. Balancing base plate 12. Balancing base plate seat 13. Foundation bolts 14. Concrete pier 15 , jack 13
JB/T6752-1993
1, jack head 2, support 3, micrometer for measurement 4, wheel 5, square level 13
6, lower end cover 7, counterweight 8, counterweight added during fine balancing 9, combined gum nail 10, balance base plate 11, balance ball 12, balance bracket 13, gasket 14, centering plate 15, platform 14
4. 2. 2. 4
4.2. 2.11
JB/T6752—1993
1. Measuring dial gauge 2. Square level 3. Sleeve 4. Bushing 5. Adjustment rod 6. Nut 7. Centering plate 8. Balancing ball
9. Balancing plate 10. Gland
11. Balancing base plate 12. Balancing base plate seat 13. Bracket 14. Base 15. Jack 16. Platform
Figure 5 Schematic diagram of static balancing test device for axial flow turbine runner The radius of the balancing ball is selected according to Table 2.
Runner mass
>5000~10000
>10000
The fit between the balancing ball and the centering plate should be H7/r6. The fit between the balancing base plate and the balancing base plate seat or pier should be H7/r6. The fit between the centering plate and the inner hole of the balancing bracket should be H7/k6. The fit between the balancing bracket and the wheel body should be H7/k6. The radius of the balancing ball
≥>50
Under the gravity of the wheel to be balanced, the horizontality of the balancing base plate should be less than 0.02mm/m. The parallelism of the two contact surfaces of the gasket should be less than 0.02mm/m, and the balancing base plate should have no pressure decay.
There should be no indentation at the balancing contact point.
The horizontality of the platform working surface should be less than 0.03mm/m. Sensitivity of the static balancing device.
The sensitivity of the static balancing device can be expressed by the distance between the center of gravity of the wheel and the center of the balancing ball (as shown in Figure 6). 20
JB/T67521993
(PR-μM)R
The distance between the center of gravity of the balanced wheel and the center of the balancing ball, mm; where, h
H The sinking amount of the lower ring of the wheel or the end face of the wheel body, mm; u--rolling friction coefficient, mm. For steel and steel, it is 0.010.02mm; R--the distance between the measuring point of the sinking amount of the lower ring of the wheel or the end face of the wheel body and the axis of rotation of the wheel, mm; P--the mass of the test weight added at the lower ring of the wheel or the end face of the wheel body, kg; M-the mass of the balanced wheel, kg.
4.2.2.13 Adjust the sensitivity of the static balancing device to meet the requirements of Table 3. Table 3 Distance h from the center of the balancing ball to the center of gravity of the runner Runner mass
>5000~10000
>10000
Maximum distance h..
4.2.2.14 Any vertical static balancing device or vertical balancing machine with a higher accuracy than the above requirements can be used. 4.2.3 Matters to be noted in vertical static balancing Minimum distance h
4.2.3.1 For welded runners, the assembly welding, heat treatment and grinding should be completed before static balancing to meet the requirements of the drawings. If there is a pressure relief plate, the pressure relief plate should be pre-installed.
4.2.3.2 For axial flow propeller turbine runners, the assembly of blades, runner body and blade operating mechanism (except operating rod and relay piston) should be completed with counterweight before vertical static balancing. 4.2.3.3 When performing vertical static balancing, measures should be taken to prevent the runner from overturning. 4.2.3.4 When welding the counterweight, the balancing ball should be separated from the balancing base plate. 4.2.4 Balancing method
The vertical static balancing of the turbine runner is carried out in two steps: initial balancing and fine balancing. 4.2.4.1 Initial Balance
4.2.4.1.1 Stability Check
Put the rotating wheel with the balancing tool on the top of the platform hall and keep the balancing ball at a certain distance from the balancing bottom plate; a.
Gently lower the jack to make the balancing ball contact the balancing bottom plate slowly; 21
JB/T6752—1993
Observe whether the rotating wheel is in a stable state under the support of the balancing ball; d.If the rotating wheel has a tendency to fall in any direction (i.e., it is in an unstable state), the rotating wheel must be lifted up with a jack, the height of the adjusting screw or the thickness of the gasket ring must be adjusted, and then the rotating wheel must be slowly lowered until the rotating wheel is supported by the balancing ball and can shake flexibly and is in a stable state.
4.2.4.1.2 Sensitivity Check
After the rotating wheel is in a stable state, perform a sensitivity check on the static balancing device. Place the weights P1, Pz, Ps of different masses at the same position of the lower ring of the wheel or the end face of the wheel body; a.
At the position where the weights are added, use a table to measure the sinking amount H, H2, H, of the lower ring of the wheel or the end face of the wheel body after the weights are placed: Substituting P, P, and Hi, Hz into formulas (10) and (11), the sensitivity h (unit: mm) of the static balancing device and the rolling friction coefficient μ (unit: mm) between the balancing ball and the balancing base plate can be calculated; (P,-P,)·R
（H=H)·M
(P,·H,-P,·H,)·R
(HH,)·M
Wherein: R—the distance between the weight center and the axis of rotation of the wheel, mm; M—the mass of the wheel, kg.
d. Use P, and H, to check the calculation results of formulas (10) and (11); if the h value meets the numerical range specified in Table 3, the sensitivity of the static balancing device is considered to be qualified. e
If it does not meet the specified requirements, the wheel must be lifted with a dry pound, and the height of the adjustment screw or the thickness of the gasket ring must be readjusted with the h value obtained as a reference. Repeat the above a, b, c, and d until the sensitivity of the straight chamber static balancing device meets the requirements. f. After the sensitivity of the static balancing device is adjusted to be qualified, measures must be taken to prevent the adjustment screw from loosening. 4.2.4.1.3 Remove the test weight base and balance the weight on the wheel. Use a level gauge or a spirit level to measure the difference △H between the highest and lowest points of the lower ring of the runner or the end face of the runner body, and calculate the mass of the required counterweight according to formula (12):
P'=M(AH.b/2+u·R)
wherein; P' is the mass of the counterweight required to make the lower ring of the runner or the end face of the runner body horizontal, kg; M is the mass of the runner, kg; R is the distance between the center of mass of the added counterweight and the axis of rotation of the runner, mm; AH is the difference between the highest and lowest points of the lower ring of the runner or the end face of the runner body, mm; h is the sensitivity of the static balancing device, calculated using formula (10), mm; μ is the rolling friction coefficient between the balancing ball and the balancing base plate, calculated using formula (11), mm. b. If the actual counterweight position is different from the calculated counterweight position, it can be calculated according to formula (13): P.·R,=P\.R
Where: P,--actual counterweight mass, kg
R.--the distance between the center of mass of the actual counterweight and the axis of rotation of the wheel, mm; P\ is the mass of the balancing counterweight obtained by formula (12), kgR--the distance between the center of mass of the calculated counterweight and the axis of rotation of the wheel, mm. c. According to the above calculation results, counterweight is placed on the lighter side of the wheel. 4.2.4.2 Fine balancing
After the counterweight is completed, slowly drop the wheel and support it with the balancing balls. Check the balance quality and adjust the remaining unbalance of the wheel until it is less than the allowable unbalance.
4.2.5 Balance quality inspection
4.2.5.1 Use a micrometer or a level to measure the difference between the highest point and the lowest point of the runner lower ring or the end face of the runner body, △H. The actual runner sinking value H' is:
JB/T6752—1993
H'=△H'/2(mm)
4.2.5.2 The allowable sinking value H of the runner is calculated according to formula (15) or (16): H,
(Upm/1000~μ·M)·R
(40-μ.ng).R
In the formula, Ur is the allowable measurement, g·mm
-the maximum runaway speed of the turbine, r/min; np
(mm)
μ——the rolling friction coefficient between the balancing ball and the balancing base plate, the calculated value of formula (11), mm; h——the sensitivity of the static balancing device, the calculated value of formula (10), mm; R is the distance between the measuring point of the micrometer or horizontal needle and the rotating axis of the runner, mmM——the mass of the runner, kg.
4.2.5.3 If H'≤H., the runner is considered qualified. Otherwise, readjust the size and position of the counterweight until H'≤H. 5 If the runner structure and strength allow, the unbalance should be corrected by counterweight or weight removal on the non-flow surface. (14)
6 The static balancing of the turbine is the last step in the production of the turbine. After the static balancing, the turbine shall not be subjected to any processing that changes the mass distribution of the turbine. Error of allowable unbalance
Due to the inherent accuracy errors of the balancing device and measuring instruments and equipment, as well as the balancing errors caused by operation and calibration, the recommended allowable deviation of the unbalance for turbine manufacturers is -10%, and the recommended allowable deviation of the unbalance for user acceptance is +15%. 8 The marking method of the turbine balance quality grade on the drawing can refer to the relevant provisions of GB9239 standard. Sorting out the test results
The test report shall record the following items:
Test purpose, test date, static balancing device, fixtures and auxiliary equipment, test person in charge and participants; turbine number, drawing number, diameter, weight, maximum working (runaway) speed, Uer, IIo; static balancing device assembly record, stability and sensitivity inspection record; balance quality inspection record;
Evaluation of the test results.
Additional Notes:
This standard was proposed and managed by Tianjin Electric Drive Design Institute of the Ministry of Machinery Industry. This standard was drafted by Tianjin Electric Drive Design Institute of the Ministry of Machinery Industry. The main drafters of this standard are Lu Chuxun and Yang Baozhu. 23
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