How to solve the problem where the center of mass of a rotating object is not on its axis of rotation, resulting in eccentric force and force distance, causing vibration and unnecessary impact force on the support during rotation. It is necessary to use a balancing machine to perform dynamic balance detection, identify the eccentric weight, eccentricity distance, and eccentric direction; On this basis, eccentricity can be removed by adding weight and reducing weight, ensuring that the center of gravity of the rotating object is on its axis of rotation, while reducing vibration to ensure rotational balance.
Dynamic balance, also known as double-sided balance, can be used to balance the rotor with any imbalance. Static balance is not a solution, and can only be corrected on a dynamic balance machine. Before conducting dynamic balance testing, it is necessary to understand the professional terminology and calculation formula of dynamic balance testing.
If the balance accuracy of a motor rotor is required to be G6.3 level, the weight of the rotor is 0.2kg, the speed of the rotor is 1000rpm, and the correction radius is 20mm, the allowable unbalance of the rotor is: because the motor rotor is generally double-sided correction balance, the allowable unbalance allocated to each side is 0.3g. Before selecting a balancing machine, the required balancing accuracy of the rotor should be considered first.
Dynamic balance detection
1、 Explanation of dynamic balance terms:
1. Rotor balance quality: an indicator for measuring the quality of rotor balance
G=eper · Ω/1000, where:
G is the rotor balance mass, with a unit of mm/s, divided into 11 levels from G0.4-G4000;
Eper is the allowable unbalance rate of the rotor, in units of gmm/kg or rotor mass eccentricity um;
Ω is the angle of the highest working speed of the rotor, -2 π· m/60;
2. Permissible unbalance (rate) per unit mass of rotor:
Eper=G · 1000/Ω=G · 1000 · 60/(2 π· n)
≈ 9549 · G/n, in units of g · mm/kg or um;
2、 Simplified calculation formula for unbalanced quantity:
M=9549MG/r × n, where:
M - rotor mass unit (kg)
G - Selection of accuracy level
R - Correction radius unit (mm)
N - Working speed unit of the workpiece (rpm)
M - Unbalanced qualified quantity unit (g)
3、 The formula for calculating the allowable imbalance is:
Where mper=M * G * (60/2PI * r * n) X10 ^ 3 (g):
Mper - is the allowable unbalance amount;
M - represents the weight of the rotor itself;
The unit is - kg;
G - represents the balance accuracy level of the rotor;
The unit is - mm/s;
R - represents the correction radius of the rotor;
The unit is - mm;
N - represents the rotational speed of the rotor;
The unit is rpm.
Before selecting a balancing machine, you need to roughly determine the balance level of the rotor. The International Organization for Standardization (ISO) established the globally recognized ISO 1940 balance level in 1940. It divides the rotor balance level into 11 levels, with increments of 2.5 times between each level, ranging from the highest demand G0.4 to the lowest demand G4000, in mm/s, representing the distance of imbalance to the rotor axis. As shown in the table below:
G4000
The crankshaft drive component of a low-speed marine diesel engine with a rigid device with an odd number of cylinders
G1600
The crankshaft drive component of a large two-stroke engine with a rigid device
G630
The crankshaft drive component of a large four stroke engine with a rigid device; Crankshaft drive components for marine diesel engines with elastic devices
G250
The crankshaft drive component of a high-speed four cylinder diesel engine with a rigid device
G100
The crankshaft transmission components of six cylinder and multi cylinder high-speed diesel engines; Complete engine units for cars, trucks, and locomotives
G40
The crankshaft drive components of six cylinder and multi cylinder high-speed four stroke engines with sedan wheels, wheel hubs, wheel assembly, transmission shaft, and elastic device
G16
Drive shafts with special requirements (propeller, universal joint drive shaft); Parts of the crusher; Parts of agricultural machinery; Individual parts of a sedan engine; Crankshaft drive components for six cylinder and multi cylinder engines with special requirements
G6.3
The gears of the main turbine of merchant ships and seagoing vessels; The drum of the high-speed separator; Electric fan; The rotor components of aviation gas turbines; The impeller of the pump; Machine tools and common machine parts; General motor rotor; Individual parts of engines with special requirements
G2.5
Gas and steam turbines; Machine tool drive components; Medium and large motor rotors with special requirements; Small motor rotor; Turbopump
G1
Magnetic tape recorders and record players Drivers for CDs and DVDs; Grinding machine drive components; Small Armature with Special Needs
G0.4
The spindle of a precision grinder; Motor rotor; gyroscope
Dynamic balance, also known as double-sided balance, can be used to balance the rotor with any imbalance. Static balance is not a solution, and can only be corrected on a dynamic balance machine. Before conducting dynamic balance testing, it is necessary to understand the professional terminology and calculation formula of dynamic balance testing.
If the balance accuracy of a motor rotor is required to be G6.3 level, the weight of the rotor is 0.2kg, the speed of the rotor is 1000rpm, and the correction radius is 20mm, the allowable unbalance of the rotor is: because the motor rotor is generally double-sided correction balance, the allowable unbalance allocated to each side is 0.3g. Before selecting a balancing machine, the required balancing accuracy of the rotor should be considered first.
Dynamic balance detection
1、 Explanation of dynamic balance terms:
1. Rotor balance quality: an indicator for measuring the quality of rotor balance
G=eper · Ω/1000, where:
G is the rotor balance mass, with a unit of mm/s, divided into 11 levels from G0.4-G4000;
Eper is the allowable unbalance rate of the rotor, in units of gmm/kg or rotor mass eccentricity um;
Ω is the angle of the highest working speed of the rotor, -2 π· m/60;
2. Permissible unbalance (rate) per unit mass of rotor:
Eper=G · 1000/Ω=G · 1000 · 60/(2 π· n)
≈ 9549 · G/n, in units of g · mm/kg or um;
2、 Simplified calculation formula for unbalanced quantity:
M=9549MG/r × n, where:
M - rotor mass unit (kg)
G - Selection of accuracy level
R - Correction radius unit (mm)
N - Working speed unit of the workpiece (rpm)
M - Unbalanced qualified quantity unit (g)
3、 The formula for calculating the allowable imbalance is:
Where mper=M * G * (60/2PI * r * n) X10 ^ 3 (g):
Mper - is the allowable unbalance amount;
M - represents the weight of the rotor itself;
The unit is - kg;
G - represents the balance accuracy level of the rotor;
The unit is - mm/s;
R - represents the correction radius of the rotor;
The unit is - mm;
N - represents the rotational speed of the rotor;
The unit is rpm.
Before selecting a balancing machine, you need to roughly determine the balance level of the rotor. The International Organization for Standardization (ISO) established the globally recognized ISO 1940 balance level in 1940. It divides the rotor balance level into 11 levels, with increments of 2.5 times between each level, ranging from the highest demand G0.4 to the lowest demand G4000, in mm/s, representing the distance of imbalance to the rotor axis. As shown in the table below:
G4000
The crankshaft drive component of a low-speed marine diesel engine with a rigid device with an odd number of cylinders
G1600
The crankshaft drive component of a large two-stroke engine with a rigid device
G630
The crankshaft drive component of a large four stroke engine with a rigid device; Crankshaft drive components for marine diesel engines with elastic devices
G250
The crankshaft drive component of a high-speed four cylinder diesel engine with a rigid device
G100
The crankshaft transmission components of six cylinder and multi cylinder high-speed diesel engines; Complete engine units for cars, trucks, and locomotives
G40
The crankshaft drive components of six cylinder and multi cylinder high-speed four stroke engines with sedan wheels, wheel hubs, wheel assembly, transmission shaft, and elastic device
G16
Drive shafts with special requirements (propeller, universal joint drive shaft); Parts of the crusher; Parts of agricultural machinery; Individual parts of a sedan engine; Crankshaft drive components for six cylinder and multi cylinder engines with special requirements
G6.3
The gears of the main turbine of merchant ships and seagoing vessels; The drum of the high-speed separator; Electric fan; The rotor components of aviation gas turbines; The impeller of the pump; Machine tools and common machine parts; General motor rotor; Individual parts of engines with special requirements
G2.5
Gas and steam turbines; Machine tool drive components; Medium and large motor rotors with special requirements; Small motor rotor; Turbopump
G1
Magnetic tape recorders and record players Drivers for CDs and DVDs; Grinding machine drive components; Small Armature with Special Needs
G0.4
The spindle of a precision grinder; Motor rotor; gyroscope
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