JB/T 9601-1999 Balancing accuracy and process specification for rotors of single-phase series-excited motors for power tools
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This standard is the first revision of JB/Z239-85 "Balancing Accuracy and Process Specifications for Single-phase Series-excited Motor Rotors for Electric Tools". Unit 1: Drafting and Expression Rules for Standards Part 1: Specimen Standards are compiled in accordance with GB/T1.11993 "Basic Regulations for the Compilation of Standardization Work Guidelines".
This standard replaces JB/Z239-85 from the date of implementation. This standard is proposed and managed by the National Technical Committee for Standardization of Electric Tools. The drafting unit of this standard: Shanghai Electric Tool Research Institute. The main drafters of this standard: Luo Xuanqiang and Huang Yang. 65
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Standard of the Machinery Industry of the People's Republic of China
Balance accuracy and process rule of single--phase series motor rotor for electric tools
Balance accuracy and process rule of single--phase series motor of electric tools
JB/T 9601--1999
Replaces JB/Z239--85
This standard applies to the dynamic balance of single-phase series motor rotors (hereinafter referred to as rotors) in electric tools, for reference by manufacturers. 2 Terminology
2.1 Rigid rotor
The unbalance of the rotor is a fixed value and has nothing to do with the speed. Any rotor that can be corrected on two (optional) correction planes and, after correction, does not significantly exceed the unbalance tolerance at any speed up to the maximum operating speed, can be regarded as a rigid rotor. 2.2 Unbalance tolerance
The maximum permissible value of the center of gravity offset on the radial plane of a rigid rotor. The unbalanced state below this value is considered acceptable. 2.3 Dynamic unbalance
If the central principal inertia axis of the rotor does not coincide with the axis, the unbalanced state generated when the rotor rotates is called dynamic unbalance. The value of dynamic unbalance can be obtained by two equivalent unbalance vectors in two selected planes (perpendicular to the axis). These two equivalent unbalance vectors fully represent the unbalanced state of the rotor. 2.4 Unbalance
The product of the unbalanced mass and the distance of its center of gravity from the axis is the unbalanced value in the rotor (belonging to a certain plane), regardless of the unbalanced angular position.
The unit of unbalance is g·mm.
2.5 Rotor center of gravity offset
The unbalance divided by the mass of the rotor is the unbalance per unit mass of the rotor. The unit of the rotor center of gravity offset is μm.
2.6 Initial rotor center of gravity offset value
The center of gravity offset value of the rotor before balancing. 2.7 Residual rotor center of gravity offset value
The rotor center of gravity offset value that remains after balancing, represented by the symbol ε. 2.8 Permissible rotor center of gravity offset value
The maximum permissible rotor center of gravity offset value for a rigid rotor, represented by the symbol e. Any unbalanced state less than this value is permitted. 2.9 Correction plane
The plane perpendicular to the rotor axis for unbalance correction. 2.10 Measuring plane
The plane perpendicular to the rotor axis for measuring the center of gravity offset value and angular position. 2.11 Separation plane
Approved by the State Bureau of Machinery Industry on August 6, 1999, 66
Implemented on January 1, 2000
JB/T9601-1999
A plane perpendicular to the rotor axis for plane separation. 2.12 Calibration plane
A plane perpendicular to the rotor axis for calibrating the specific balancing accuracy of the rotor. 2.13 Calibration rotor
A rotor used to adjust the balancing machine, usually one of the same type. 2.14 Test rotor
A rigid rotor of appropriate mass used to calibrate the balancing machine. 2.15 Plane separation
For a specific rotor, the operation process of using the balancing machine to reduce the correction plane to the disturbance ratio. 2.16 Minimum achievable and residual rotor center of gravity offset value The minimum value of the residual rotor center of gravity offset value that can be achieved by the balancing machine. 2.17 Unbalance reduction rate
The ratio of the unbalance removed after a correction divided by the initial unbalance. Usually, the ratio is expressed as a percentage. 2.18 Correction plane interference ratio
The interference ratios IAs and IB4 of the two correction planes A and B of the rotor are obtained by the following relationship: UAB
Where: UAs and UBB are the indicated values of the unbalance amount generated on the correction planes A and B respectively after the unbalance amount is added to plane B. UBa
IBAUAA
Where: Us4 and U are the indicated values of the unbalance amount generated on the correction plane A of B respectively after the unbalance amount is added to plane A. 3 Technical requirements
3.1 Balancing accuracy of the rotor
(2)
The balancing accuracy of the rotor should preferably be G6.3. According to the different economic and technical requirements of various products, other accuracy levels can be used, but they must not be lower than G16.
3.2 Allowable rotor gravity center offset
The allowable rotor gravity center offset is calculated as follows: 1000G
Where: e--allowable rotor gravity center offset, μm; G-balance accuracy, mm/s
-rotor angular velocity, rad/s.
3.3 Allowable rotor gravity center offset in multi-speed power tools (3)
Multi-speed power tools should be based on the maximum working speed of the rotor. The allowable rotor gravity center offset e is calculated according to the formula specified in 3.2. 3.4 Allowable rotor gravity center offset on each calibration plane The allowable rotor gravity center offset on each calibration plane is half of the rotor gravity center offset e=Cr
Where: el--allowable rotor gravity center offset on the left plane, μm; er--allowable rotor gravity center offset on the right plane, um. (4)
If the center of mass of the rotor falls outside the middle one-third area of the support distance, its center of gravity offset value must be allocated according to the mass distribution of the rotor. 3.5 Expression method on the design drawing
The manufacturer shall provide the balancing accuracy grade specified in 4.1 or the allowable rotor center of gravity offset value for each correction plane, the position of the correction plane and other data on the rotor design drawing. 4 Process regulations
4.1 General requirements for dynamic balancing machines
JB/T9601-1999
4.1.1 The dynamic balancing machine shall be calibrated using the test rotor provided with the balancing machine. 4.1.2 The minimum achievable residual rotor center of gravity offset value of the dynamic balancing machine shall be less than 0.5um. 4.1.3 The unbalance reduction rate of the dynamic balancing machine shall be greater than 80%. 4.1.4 The sensitivity of the dynamic balancing machine shall not be less than 0.1μm/grid. 4.1.5 When the center of gravity offset value of the rotor is 0.5μm, the positioning error shall not exceed ±15, or the phase shall be unstable but not more than ±15°. The instrument indication shall be stable, and its variation amplitude shall be less than 5%. 4.1.6
The interference ratio of the correction plane shall be less than 10%.
For the same unbalance, the instrument indication values of the left and right planes shall be the same, and the error shall be less than 5%. 4.1.8
The center of the V-groove of the two pendulum frames shall be in the same straight line with the axis of the rotor. In addition to timely repair of faults, the dynamic balancing machine shall also be calibrated regularly. The dynamic balancing machine shall be installed horizontally on a solid and stable workbench and in a room with low vibration and electromagnetic interference. When there is no calibration rotor on the dynamic balancing machine, the instrument reading shall be zero.
4.2 Calibration rotor
A dynamic balancing machine without an electric simulation device shall be calibrated with a rotor. 4.2.1
The calibration rotor shall have the same shape, size and weight as the batch of rotors to be calibrated. 4.2.2
The residual center of gravity offset of the calibration rotor is less than 0.5μm. 4.2.3
The roundness and coaxiality of the calibration rotor journal are less than 2um, and the surface roughness is above Ra0.8. 4.2.4
The calibration rotor shall be properly stored and generally should not be placed horizontally but vertically to prevent its deformation. It should be recalibrated after a period of use. 4.2.5#
4.3 Technical requirements for rotors to be calibrated
4.3.1 The rotor to be calibrated must be equipped with a fan.
4.3.2 There shall be no paint film, burrs or other dirt on the journal of the rotor to be calibrated. 4.3.3 The initial rotor center of gravity offset caused by the processes of axial pressing of the core, winding, dripping of paint, and pressing of fans shall generally not exceed 50μm.
4.4 Frequency selection
4.4.1 The frequency selection must be performed with a calibrated rotor equipped with an unbalanced weight plate. 4.4.2 Adjust the support frame of the dynamic balancing machine so that the middle position of the rotor's shaft neck is supported at the center of the V-frame, and there is no axial vibration or up and down jump during rotation.
4.4.3 Adjust the balancing speed or the working frequency of the balancing machine circuit system so that the pointer of the microammeter reaches the maximum value. If the frequency selection is correct, when changing the selection of weighting and deweighting, the phase of the unbalanced quantity is just opposite and the phase is stable. 4.4.4 For the flash type dynamic balancing machine, the phase of the unbalanced quantity should be correctly reflected in the horizontal position. If the frequency double signal appears, the flash stops and the image appears double, the speed should be readjusted.
4.4.5 In order to ensure the positioning accuracy, the following measures can be taken: a) When starting, add a little lubricating oil to the journal; b) Apply a little talcum powder on the transmission belt;
c) Replace the transmission belt with poor elasticity after being loosened in time; d) Replace the worn plastic support in time.
4.4.6 The dynamic balancing machine should be equipped with a frequency stabilizing and voltage stabilizing device. If the voltage and frequency of the power grid are unstable, and the dynamic balance has no frequency stabilizing and voltage stabilizing device, the frequency should be selected frequently during the calibration process.
4.5 Plane separation
JB/T9601—1999
4.5.1 Dynamic balancing machines without electric simulation devices must use calibration rotors for plane separation. 4.5.2 The separation plane should generally be consistent with the calibration plane. 4.5.3 The unbalanced mass used for plane separation should be 510 times the precision calibration mass of the calibrated rotor to increase the effect of plane separation.
4.5.4 Plane separation should minimize the interference ratio of the calibration plane, that is, when the above unbalanced amount is added to the calibration rotor plane A, the instrument indication value of plane B should be the minimum, and vice versa. 4.5.5 Plane separation should be repeated multiple times. 4.6 Rotor balancing speed and direction
4.6.1 The balancing speed should not be less than one-tenth of the actual working speed of the rotor-4.6.2 If the driving device of the dynamic balancing machine is an induction motor, the balancing speed should avoid the forbidden area of its synchronous speed. 4.6.3 The balancing speed remains unchanged during the calibration of the rotor. 4.6.4 The direction of rotation of the rotor to be calibrated on the dynamic balancing machine should be consistent with the actual working direction. 4.7 Calibration
4.7.1 The unbalanced mass used for calibration accuracy on each calibration plane is calculated according to the following formula: XM
Where: mL--unbalanced mass of the left plane, g; M--rotor mass, kg;
-radius of the left plane counterweight, mm. rt
Where: mR-
unbalanced mass of the right plane, g;
radius of the right plane counterweight, mm.
4.7.2 The calibration plane must be consistent with the calibration plane. &
4.7.3 Place the unbalanced mass calculated based on the allowable rotor center of gravity offset value on the left and right planes on the left and right calibration planes of the calibration rotor respectively, drive it to the balancing speed, and use the appropriate attenuation gear and spot range. Make the instrument's microampere values I and Ix indicate on the appropriate integer scale, then the scale is the calibration value of the determined allowable rotor center of gravity offset value. In order to make full use of the sensitivity of the balancing machine and consider the convenience of observation during operation, the calibration value of the instrument should not be too small. 4.7.4 When the dynamic balancing bracket is readjusted, or the type and specification of the calibrated rotor is changed, the rotor of this type and specification must be re-selected for frequency-plane separation and calibration.
4.8 Correction method
4.8.1 The rotor is approximately a rigid rotor and should be dynamically balanced. 4.8.2 Different correction methods such as de-weighting, weighting or a combination of de-weighting and weighting are allowed. Generally, weights can be placed on the core surface or fan. 4.8.3 Weighting rules:
4.8.3.1 The position of the weight (or correction plane) should be selected as close to the rotor journal as possible. 4.8.3.2 If weights are placed on the core of the rotor, the length of the weights on each plane shall not exceed two-fifths of the total length of the laminated core unless the unbalances on the two calibration planes are in phase.
4.8.3.3 On the circumference of the rotor, the sector angle of the weights shall not exceed 120°. 4.8.3.4 For rotors that are difficult to balance, dynamic balancing shall be performed using balancing blocks. 4.8.3.5 The side with the larger unbalance shall be balanced first, and the left and right planes shall be rotated until the balance is below the calibration scale. 4.8.4 Before installation, if the rotor that has been dynamically balanced is accidentally deformed due to falling or collision, the rotor shall be recalibrated. 5 Method for measuring the center of gravity offset of the remaining rotor 5.1 Direct method
JB/T9601—1999
According to the calibration values I. and IR in 4.7.3, calculate the center of gravity offset represented by the instrument unit microampere. b.
Where: br.——rotor gravity center offset value in microamperes on the left plane, μm/μA; IL——calibration value of the instrument on the left plane, uA. br
Where: bk—rotor gravity center offset value in microamperes on the right plane, um/μA; IR—calibration value of the instrument on the right plane, μA. (7)
Put the rotor to be calibrated on a movable horizontal gear with a calibrated scale for the rotor gravity center offset value, and the i. and iR values can be directly read from the instrument. =bi
Where: Et. residual gravity center offset value on the left plane, um; i-
—electricity indication value on the left plane, A.
ER=bR·ig
Where: ER—residual gravity center offset value on the right plane, um; ir—electricity indication value on the right plane, μA. 5.2 Sine method
. (9)
Select a test block whose mass is equal to 5 to 10 times the estimated residual unbalanced mass of the rotor. The test block should be weighed on an analytical balance. Record the mass of the test block, the mass of the rotor, and the radius of the counterweight. Add the test blocks to the rotor calibration surface (two planes respectively) at each equally divided point. The equally divided points are generally 12 points. The test blocks should be applied as unsequentially as possible, usually in a few points, as shown in Figure 1. Read the readings at the corresponding angle positions from the instrument and make a record. If two positions reflect the same maximum and minimum values, it is necessary to make an additional measurement between the two points and take the larger or smaller value. If the angle of the test unbalanced mass is used as the horizontal coordinate and the instrument reading is used as the vertical coordinate, the readings at the corresponding angle positions form an approximate sine curve on the coordinate plane, as shown in Figure 2. 1
Test imbalance
Test procedure for residual imbalance
Residual imbalance
ji(μA)
JB/T9601—1999
Residual imbalance angle
Figure 2 Measurement diagram of residual imbalance
Residual rotor gravity center offset value on each plane: Where: il.max
-maximum value of the left plane electricity indication, μA; iLmin—minimum value of the left plane electricity indication, μA; W,-mass of the test block on the left plane, g.
Wr—mass of the test block on the right plane, g.
6 Inspection rules
ILeax +iLmin
iRmex + iRmin
The residual rotor gravity center offset value of both planes shall not exceed the allowable value specified in 3.5, and the tolerance is +15%, which can be regarded as qualified. If one of the planes exceeds, it can be regarded as unqualified. 714 The direction of rotation of the rotor to be calibrated on the dynamic balancing machine should be consistent with the actual working direction. 4.7 Calibration
4.7.1 The unbalanced mass used for calibration accuracy on each calibration plane is calculated according to the following formula: XM
Where: mL--unbalanced mass of the left plane, g; M--rotor mass, kg;
-radius of the left plane counterweight, mm. rt
Where: mR-
unbalanced mass of the right plane, g;
radius of the right plane counterweight, mm.
4.7.2 The calibration plane must be consistent with the calibration plane. &
4.7.3 Place the unbalanced mass calculated based on the allowable rotor center of gravity offset value on the left and right planes on the left and right calibration planes of the calibration rotor respectively, drive it to the balanced speed, and use the appropriate attenuation gear and spot range. Make the instrument's microampere values I and Ix indicate on the appropriate integer scale, then the scale is the calibration value of the determined allowable rotor center of gravity offset value. In order to make full use of the sensitivity of the balancing machine and consider the convenience of observation during operation, the calibration value of the instrument should not be too small. 4.7.4 When the dynamic balancing bracket is readjusted, or the type and specification of the calibrated rotor is changed, the rotor of this type and specification must be re-selected for frequency-plane separation and calibration.
4.8 Correction method
4.8.1 The rotor is approximately a rigid rotor and should be dynamically balanced. 4.8.2 Different correction methods such as de-weighting, weighting or a combination of de-weighting and weighting are allowed. Generally, weights can be placed on the core surface or fan. 4.8.3 Weighting rules:
4.8.3.1 The position of the weight (or correction plane) should be selected as close to the rotor journal as possible. 4.8.3.2 If weights are placed on the core of the rotor, the length of the weights on each plane shall not exceed two-fifths of the total length of the laminated core unless the unbalances on the two calibration planes are in phase.
4.8.3.3 On the circumference of the rotor, the sector angle of the weights shall not exceed 120°. 4.8.3.4 For rotors that are difficult to balance, dynamic balancing shall be performed using balancing blocks. 4.8.3.5 The side with the larger unbalance shall be balanced first, and the left and right planes shall be rotated until the balance is below the calibration scale. 4.8.4 Before installation, if the rotor that has been dynamically balanced is accidentally deformed due to falling or collision, the rotor shall be recalibrated. 5 Method for measuring the center of gravity offset of the remaining rotor 5.1 Direct method
JB/T9601—1999
According to the calibration values I. and IR in 4.7.3, calculate the center of gravity offset represented by the instrument unit microampere. b.
Where: br.——rotor gravity center offset value in microamperes on the left plane, μm/μA; IL——calibration value of the instrument on the left plane, uA. br
Where: bk—rotor gravity center offset value in microamperes on the right plane, um/μA; IR—calibration value of the instrument on the right plane, μA. (7)
Put the rotor to be calibrated on a movable horizontal gear with a calibrated scale for the rotor gravity center offset value, and the i. and iR values can be directly read from the instrument. =bi
Where: Et. residual gravity center offset value on the left plane, um; i-
—electricity indication value on the left plane, A.
ER=bR·ig
Where: ER—residual gravity center offset value on the right plane, um; ir—electricity indication value on the right plane, μA. 5.2 Sine method
. (9)
Select a test block whose mass is equal to 5 to 10 times the estimated residual unbalanced mass of the rotor. The test block should be weighed on an analytical balance. Record the mass of the test block, the mass of the rotor, and the radius of the counterweight. Add the test blocks to the rotor calibration surface (two planes respectively) at each equally divided point. The equally divided points are generally 12 points. The test blocks should be applied as unsequentially as possible, usually in a few points, as shown in Figure 1. Read the readings at the corresponding angle positions from the instrument and make a record. If two positions reflect the same maximum and minimum values, it is necessary to make an additional measurement between the two points and take the larger or smaller value. If the angle of the test unbalanced mass is used as the horizontal coordinate and the instrument reading is used as the vertical coordinate, the readings at the corresponding angle positions form an approximate sine curve on the coordinate plane, as shown in Figure 2. 1
Test imbalance
Test procedure for residual imbalance
Residual imbalance
ji(μA)
JB/T9601—1999
Residual imbalance angle
Figure 2 Measurement diagram of residual imbalance
Residual rotor gravity center offset value on each plane: Where: il.max
-maximum value of the left plane electricity indication, μA; iLmin—minimum value of the left plane electricity indication, μA; W,-mass of the test block on the left plane, g.
Wr—mass of the test block on the right plane, g.
6 Inspection rules
ILeax +iLmin
iRmex + iRmin
The residual rotor gravity center offset value of both planes shall not exceed the allowable value specified in 3.5, and the tolerance is +15%, which can be regarded as qualified. If one of the planes exceeds, it can be regarded as unqualified. 714 The direction of rotation of the rotor to be calibrated on the dynamic balancing machine should be consistent with the actual working direction. 4.7 Calibration
4.7.1 The unbalanced mass used for calibration accuracy on each calibration plane is calculated according to the following formula: XM
Where: mL--unbalanced mass of the left plane, g; M--rotor mass, kg;
-radius of the left plane counterweight, mm. rt
Where: mR-
unbalanced mass of the right plane, g;
radius of the right plane counterweight, mm.
4.7.2 The calibration plane must be consistent with the calibration plane. &
4.7.3 Place the unbalanced mass calculated based on the allowable rotor center of gravity offset value on the left and right planes on the left and right calibration planes of the calibration rotor respectively, drive it to the balanced speed, and use the appropriate attenuation gear and spot range. Make the instrument's microampere values I and Ix indicate on the appropriate integer scale, then the scale is the calibration value of the determined allowable rotor center of gravity offset value. In order to make full use of the sensitivity of the balancing machine and consider the convenience of observation during operation, the calibration value of the instrument should not be too small. 4.7.4 When the dynamic balancing bracket is readjusted, or the type and specification of the calibrated rotor is changed, the rotor of this type and specification must be re-selected for frequency-plane separation and calibration.
4.8 Correction method
4.8.1 The rotor is approximately a rigid rotor and should be dynamically balanced. 4.8.2 Different correction methods such as de-weighting, weighting or a combination of de-weighting and weighting are allowed. Generally, weights can be placed on the core surface or fan. 4.8.3 Weighting rules:
4.8.3.1 The position of the weight (or correction plane) should be selected as close to the rotor journal as possible. 4.8.3.2 If weights are placed on the core of the rotor, the length of the weights on each plane shall not exceed two-fifths of the total length of the laminated core unless the unbalances on the two calibration planes are in phase.
4.8.3.3 On the circumference of the rotor, the sector angle of the weights shall not exceed 120°. 4.8.3.4 For rotors that are difficult to balance, dynamic balancing shall be performed using balancing blocks. 4.8.3.5 The side with the larger unbalance shall be balanced first, and the left and right planes shall be rotated until the balance is below the calibration scale. 4.8.4 Before installation, if the rotor that has been dynamically balanced is accidentally deformed due to falling or collision, the rotor shall be recalibrated. 5 Method for measuring the center of gravity offset of the remaining rotor 5.1 Direct method
JB/T9601—1999
According to the calibration values I. and IR in 4.7.3, calculate the center of gravity offset represented by the instrument unit microampere. b.
Where: br.——rotor gravity center offset value in microamperes on the left plane, μm/μA; IL——calibration value of the instrument on the left plane, uA. br
Where: bk—rotor gravity center offset value in microamperes on the right plane, um/μA; IR—calibration value of the instrument on the right plane, μA. (7)
Put the rotor to be calibrated on a movable horizontal gear with a calibrated scale for the rotor gravity center offset value, and the i. and iR values can be directly read from the instrument. =bi
Where: Et. residual gravity center offset value on the left plane, um; i-
—electricity indication value on the left plane, A.
ER=bR·ig
Where: ER—residual gravity center offset value on the right plane, um; ir—electricity indication value on the right plane, μA. 5.2 Sine method
. (9)
Select a test block whose mass is equal to 5 to 10 times the estimated residual unbalanced mass of the rotor. The test block should be weighed on an analytical balance. Record the mass of the test block, the mass of the rotor, and the radius of the counterweight. Add the test blocks to the rotor calibration surface (two planes respectively) at each equally divided point. The equally divided points are generally 12 points. The test blocks should be applied as unsequentially as possible, usually in a few points, as shown in Figure 1. Read the readings at the corresponding angle positions from the instrument and make a record. If two positions reflect the same maximum and minimum values, it is necessary to make an additional measurement between the two points and take the larger or smaller value. If the angle of the test unbalanced mass is used as the horizontal coordinate and the instrument reading is used as the vertical coordinate, the readings at the corresponding angle positions form an approximate sine curve on the coordinate plane, as shown in Figure 2. 1
Test imbalance
Test procedure for residual imbalance
Residual imbalance
ji(μA)
JB/T9601—1999
Residual imbalance angle
Figure 2 Measurement diagram of residual imbalance
Residual rotor gravity center offset value on each plane: Where: il.max
-maximum value of the left plane electricity indication, μA; iLmin—minimum value of the left plane electricity indication, μA; W,-mass of the test block on the left plane, g.
Wr—mass of the test block on the right plane, g.
6 Inspection rules
ILeax +iLmin
iRmex + iRmin
The residual rotor gravity center offset value of both planes shall not exceed the allowable value specified in 3.5, and the tolerance is +15%, which can be regarded as qualified. If one of the planes exceeds, it can be regarded as unqualified. 71(9)
Select a test block whose mass is equal to 5 to 10 times the estimated residual unbalanced mass of the rotor. The test block should be weighed on an analytical balance. Record the mass of the test block, the mass of the rotor, and the radius of the counterweight. Add the test blocks to the equally divided points on the rotor calibration surface (two planes respectively). There are generally 12 equally divided points. The test blocks should be applied in a non-sequential manner as much as possible, usually in a few points, as shown in Figure 1. Read the readings at the corresponding angle positions from the instrument and make a record. If two positions reflect the same maximum and minimum values, it is necessary to make an additional measurement between the two points and take the larger or smaller value. If the angle of the test unbalanced mass is used as the horizontal coordinate and the instrument reading is used as the vertical coordinate, the readings at the corresponding angle positions form an approximate sine curve on the coordinate plane, as shown in Figure 2. 1
Test imbalance
Test procedure for residual imbalance
Residual imbalance
ji(μA)
JB/T9601—1999
Residual imbalance angle
Figure 2 Measurement diagram of residual imbalance
Residual rotor gravity center offset value on each plane: Where: il.max
-maximum value of the left plane electricity indication, μA; iLmin—minimum value of the left plane electricity indication, μA; W,-mass of the test block on the left plane, g.
Wr—mass of the test block on the right plane, g.
6 Inspection rules
ILeax +iLmin
iRmex + iRmin
The residual rotor gravity center offset value of both planes shall not exceed the allowable value specified in 3.5, and the tolerance is +15%, which can be regarded as qualified. If one of the planes exceeds, it can be regarded as unqualified. 71(9)
Select a test block whose mass is equal to 5 to 10 times the estimated residual unbalanced mass of the rotor. The test block should be weighed on an analytical balance. Record the mass of the test block, the mass of the rotor, and the radius of the counterweight. Add the test blocks to the equally divided points on the rotor calibration surface (two planes respectively). There are generally 12 equally divided points. The test blocks should be applied in a non-sequential manner as much as possible, usually in a few points, as shown in Figure 1. Read the readings at the corresponding angle positions from the instrument and make a record. If two positions reflect the same maximum and minimum values, it is necessary to make an additional measurement between the two points and take the larger or smaller value. If the angle of the test unbalanced mass is used as the horizontal coordinate and the instrument reading is used as the vertical coordinate, the readings at the corresponding angle positions form an approximate sine curve on the coordinate plane, as shown in Figure 2. 1
Test imbalance
Test procedure for residual imbalance
Residual imbalance
ji(μA)
JB/T9601—1999
Residual imbalance angle
Figure 2 Measurement diagram of residual imbalance
Residual rotor gravity center offset value on each plane: Where: il.max
-maximum value of the left plane electricity indication, μA; iLmin—minimum value of the left plane electricity indication, μA; W,-mass of the test block on the left plane, g.
Wr—mass of the test block on the right plane, g.
6 Inspection rules
ILeax +iLmin
iRmex + iRmin
The residual rotor gravity center offset value of both planes shall not exceed the allowable value specified in 3.5, and the tolerance is +15%, which can be regarded as qualified. If one of the planes exceeds, it can be regarded as unqualified. 71
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